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Sökning: WFRF:(Lindén Sara K. 1974)

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1.
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2.
  • Padra, Médea, 1986, et al. (författare)
  • Increased MUC1 plus a larger quantity and complex size for MUC5AC in the peripheral airway lumen of long-term tobacco smokers
  • 2020
  • Ingår i: Clinical Science. - : Portland Press Ltd.. - 0143-5221 .- 1470-8736. ; 134:10, s. 1107-1125
  • Tidskriftsartikel (refereegranskat)abstract
    • There is little information on mucins versus potential regulatory factors in the peripheral airway lumen of long-term smokers with (LTS+) and without (LTS-) chronic obstructive pulmonary disease (COPD). We explored these matters in bronchoalveolar lavage (BAL) samples from two study materials, both including LTS+ and LTS- with a very similar historic exposure to tobacco smoke, and healthy non-smokers (HNSs; n=4-20/group). Utilizing slot blot and immunodetection of processed (filtered and centrifuged), as well as unprocessed BAL samples from one of the materials, we compared the quantity and fraction of large complexes of mucins. All LTS displayed an enhanced (median) level of MUC5AC compared with HNS. LTS- displayed a higher level of large MUC5AC complexes than HNS while LTS+ displayed a similar trend. In all LTS, total MUC5AC correlated with blood leukocytes, BAL neutrophil elastase and net gelatinase activity. Large mucin complexes accounted for most MUC5B, without clear group differences. In all LTS, total MUC5B correlated with total MUC5AC and local bacteria. In the same groups, large MUC5B complexes correlated with serum cotinine. MUC1 was increased and correlated with BAL leukocytes in all LTS whereas MUC2 was very low and without clear group differences. Thus, the main part of MUC5AC and MUC5B is present as large complexes in the peripheral airway lumen and historic as well as current exposure to tobacco smoke emerge as potential regulatory factors, regardless of COPD per se. Bacteria, leukocytes and proteinases also constitute potential regulatory factors, of interest for future therapeutic strategies.
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3.
  • Padra, Médea, 1986, et al. (författare)
  • Mucin Binding to Moraxella catarrhalis During Airway Inflammation is Dependent on Sialic Acid.
  • 2021
  • Ingår i: American journal of respiratory cell and molecular biology. - 1535-4989. ; 65:6, s. 593-602
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic obstructive pulmonary disease (COPD) is associated with colonization by bacterial pathogens and repeated airway infections, leading to exacerbations and impaired lung function. The highly glycosylated mucins in the mucus lining the airways are an important part of the host defense against pathogens. However, mucus accumulation can contribute to COPD pathology. Here, we examined whether inflammation is associated with glycosylation changes that affect interactions between airway mucins and pathogens. We isolated mucins from lower airway samples (LAS, n=4-9) from long-term smokers with and without COPD and from never-smokers. The most abundant terminal glycan moiety was N-acetylneuraminic acid (Neu5Ac) among smokers with and without COPD and N-acetyl-hexoseamine among never-smokers. Moraxella catarrhalis bound to MUC5 mucins from smokers with and without COPD. M. catarrhalis binding correlated with inflammatory parameters and Neu5Ac content. M. catarrhalis binding was abolished by enzymatic removal of Neu5Ac. Furthermore, M. catarrhalis bound to α2-6 sialyl-lactose suggesting that α2-6 sialic acid contributes to M. catarrhalis binding to mucins. Further, we detected more M. catarrhalis binding to mucins from patients with pneumonia than to those from control subjects (n=8-13) and this binding correlated with C-reactive protein and Neu5Ac levels. These results suggest a key role of inflammation induced Neu5Ac in adhesion of M. catarrhalis to airway mucins. Inflammation induced ability of MUC5 mucins to bind M. catarrhalis is likely a host defense mechanism in the healthy lung, although it cannot be excluded that impaired mucociliary clearance limits the effectiveness of this defense in COPD patients.
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4.
  • Pournaras, N., et al. (författare)
  • Glucose Homeostasis in Relation to Neutrophil Mobilization in Smokers with COPD
  • 2022
  • Ingår i: International Journal of Chronic Obstructive Pulmonary Disease. - 1178-2005. ; 17, s. 1179-1194
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) are common comorbidities in chronic obstructive pulmonary disease (COPD), but the underlying pathogenic mechanisms are poorly understood. Given that these morbidities all display increased neutrophil mobilization, the current study aimed to address whether glucose homeostasis relates to signs of neutrophil mobilization in COPD. Methods: The study population included healthy non-smokers (HNS) and long-term smokers without (LTS) and with COPD (LTS +COPD). No subject had T2DM or MetS. Serum cotinine was quantified to evaluate current smoking. Capillary blood glucose was measured after overnight fasting and during an oral glucose tolerance test (OGTT). Neutrophils were quantified in blood and bronchoalveolar lavage samples (BAL). The neutrophil-related cytokines IL-36 alpha, -beta and -gamma were quantified (ELISA) along with IL-6, IL-8, INF-gamma and CXCL10 (U-Plex (R)) in plasma and cell-free BAL fluid (BALF). In addition, we quantified neutrophil elastase (ELISA) and net proteinase activity (substrate assay) in BALF. Results: The LTS+COPD group had lower fasting glucose, greater change in glucose during OGTT and higher neutrophil concentrations in BAL and blood compared with HNS. Fasting glucose correlated in a positive manner with blood neutrophil concentration, forced expiratory volume in 1 second/forced vital capacity ratio (FEV1/FVC) and FEV1 (% of predicted) in LTS+COPD. In this group, the concentration of IL-36 alpha in BALF correlated in a negative manner with fasting glucose, blood neutrophil concentration and FEV1, while the CXCL10 concentration in BALF correlated in a negative manner with glucose at the end of OGTT (120 min). We observed no corresponding correlations for neutrophil elastase, net proteinase or gelatinase activity. Conclusion: In smokers with COPD, altered glucose homeostasis is associated with local and systemic signs of increased neutrophil mobilization, but not with local proteinases. This suggests that other specific aspects of neutrophil mobilization constitute pathogenic factors that affect glucose homeostasis in COPD.
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5.
  • Stockfelt, Marit, et al. (författare)
  • Increased CD11b and Decreased CD62L in Blood and Airway Neutrophils from Long-Term Smokers with and without COPD
  • 2020
  • Ingår i: Journal of innate immunity. - : S. Karger AG. - 1662-8128 .- 1662-811X. ; 12:6, s. 480-489
  • Tidskriftsartikel (refereegranskat)abstract
    • There is incomplete mechanistic understanding of the mobilization of neutrophils in the systemic and local compartment in smokers with chronic obstructive pulmonary disease (COPD). In this pilot study, we characterized how the adhesion molecules CD11b and CD62L, surface markers indicative of priming, are altered as neutrophils extravasate, and whether surface density of CD11b and CD62L differs between long-term tobacco smokers (LTS) with and without COPD compared with healthy never-smokers (HNS). Unstimulated blood neutrophils from LTS with (<i>n</i> = 5) and without (<i>n</i> = 9) COPD displayed lower surface density of CD62L compared with HNS (<i>n</i> = 8). In addition, surface density of CD11b was higher in bronchoalveolar lavage (BAL) neutrophils from LTS without COPD compared with those with COPD and HNS. Moreover, in BAL neutrophils from all study groups, CD62L was lower compared with matched blood neutrophils. In addition, BAL neutrophils responded with a further decrease in CD62L to ex vivo TNF stimulation. Thus, neutrophils in the airway lumen display a higher state of priming than systemic neutrophils and bear the potential to be further primed by local cytokines even with no smoking or the presence of COPD, findings that may represent a universal host defense mechanism against local bacteria. Moreover, systemic neutrophils are primed in LTS regardless of COPD. Further studies in larger materials are warranted to determine whether the priming of neutrophils is protective against COPD or merely preceding it.
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6.
  • Åberg, Anna, et al. (författare)
  • Helicobacter pylori adapts to chronic infection and gastric disease via ph-responsive baba-mediated adherence
  • 2017
  • Ingår i: Cell Host and Microbe. - : Elsevier BV. - 1931-3128 .- 1934-6069. ; 21:3, s. 376-389
  • Tidskriftsartikel (refereegranskat)abstract
    • The BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease.
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7.
  • Andersson, Anders, et al. (författare)
  • IL-36 Cytokines Promote Inflammation in the Lungs of Long-term Smokers
  • 2021
  • Ingår i: American journal of respiratory cell and molecular biology. - 1535-4989. ; 64:2, s. 173-182
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory lung disease with high morbidity and mortality. The IL-36 family are proinflammatory cytokines that are known to shape innate immune responses, including those critical to bacterial pneumonia. To determine whether IL-36 cytokines promote a proinflammatory milieu in the lungs of long-term smokers with and without COPD. Levels of IL-36 cytokines were measured in plasma and bronchoalveolar lavage fluid from subjects in a pilot study (n=23) of long-term smokers with and without COPD in vivo, and from a variety of lung cells (from 3-5 donors) stimulated with bacteria or cigarette smoke components in vitro. Pulmonary macrophages were stimulated with IL-36 cytokines in vitro, and chemokine and cytokine production was assessed. IL-36α and -γ are produced to varying degrees in murine and human lung cells in response to bacterial stimuli and cigarette smoke components in vitro. Moreover, while IL-36γ production is upregulated early after cigarette smoke stimulation and wanes over time, IL-36α production requires a longer duration of exposure. IL-36α and -γ are enhanced systemically and locally in long-term smokers with and without COPD, and local IL-36α levels display a positive correlation with declining ventilatory lung function and increasing proinflammatory cytokine levels. In vitro, IL-36α and -γ induce proinflammatory chemokines and cytokines in a concentration-dependent fashion that requires IL-36R and MyD88. IL-36 cytokine production is altered in long-term smokers with and without COPD and contributes to shaping a proinflammatory milieu in the lungs.
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8.
  • Aspholm-Hurtig, Marina, et al. (författare)
  • Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin.
  • 2004
  • Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 305:5683, s. 519-22
  • Tidskriftsartikel (refereegranskat)abstract
    • Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.
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9.
  • Gustafsson, Jenny K, 1981, et al. (författare)
  • Carbachol-induced colonic mucus formation requires transport via NKCC1, K(+) channels and CFTR.
  • 2015
  • Ingår i: Pflugers Archiv : European journal of physiology. - : Springer Science and Business Media LLC. - 1432-2013 .- 0031-6768. ; 467:7, s. 1403-1415
  • Tidskriftsartikel (refereegranskat)abstract
    • The colonic mucosa protects itself from the luminal content by secreting mucus that keeps the bacteria at a distance from the epithelium. For this barrier to be effective, the mucus has to be constantly replenished which involves exocytosis and expansion of the secreted mucins. Mechanisms involved in regulation of mucus exocytosis and expansion are poorly understood, and the aim of this study was to investigate whether epithelial anion secretion regulates mucus formation in the colon. The muscarinic agonist carbachol was used to induce parallel secretion of anions and mucus, and by using established inhibitors of ion transport, we studied how inhibition of epithelial transport affected mucus formation in mouse colon. Anion secretion and mucin exocytosis were measured by changes in membrane current and epithelial capacitance, respectively. Mucus thickness measurements were used to determine the carbachol effect on mucus growth. The results showed that the carbachol-induced increase in membrane current was dependent on NKCC1 co-transport, basolateral K(+) channels and Cftr activity. In contrast, the carbachol-induced increase in capacitance was partially dependent on NKCC1 and K(+) channel activity, but did not require Cftr activity. Carbachol also induced an increase in mucus thickness that was inhibited by the NKCC1 blocker bumetanide. However, mice that lacked a functional Cftr channel did not respond to carbachol with an increase in mucus thickness, suggesting that carbachol-induced mucin expansion requires Cftr channel activity. In conclusion, these findings suggest that colonic epithelial transport regulates mucus formation by affecting both exocytosis and expansion of the mucin molecules.
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10.
  • Gustafsson, Jenny K, 1981, et al. (författare)
  • Dynamic changes in mucus thickness and ion secretion during Citrobacter rodentium infection and clearance.
  • 2013
  • Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
  • Tidskriftsartikel (refereegranskat)abstract
    • Citrobacter rodentium is an attaching and effacing pathogen used as a murine model for enteropathogenic Escherichia coli. The mucus layers are a complex matrix of molecules, and mucus swelling, hydration and permeability are affected by many factors, including ion composition. Here, we used the C. rodentium model to investigate mucus dynamics during infection. By measuring the mucus layer thickness in tissue explants during infection, we demonstrated that the thickness changes dynamically during the course of infection and that its thickest stage coincides with the start of a decrease of bacterial density at day 14 after infection. Although quantitative PCR analysis demonstrated that mucin mRNA increases during early infection, the increased mucus layer thickness late in infection was not explained by increased mRNA levels. Proteomic analysis of mucus did not demonstrate the appearance of additional mucins, but revealed an increased number of proteins involved in defense responses. Ussing chamber-based electrical measurements demonstrated that ion secretion was dynamically altered during the infection phases. Furthermore, the bicarbonate ion channel Bestrophin-2 mRNA nominally increased, whereas the Cftr mRNA decreased during the late infection clearance phase. Microscopy of Muc2 immunostained tissues suggested that the inner striated mucus layer present in the healthy colon was scarce during the time point of most severe infection (10 days post infection), but then expanded, albeit with a less structured appearance, during the expulsion phase. Together with previously published literature, the data implies a model for clearance where a change in secretion allows reformation of the mucus layer, displacing the pathogen to the outer mucus layer, where it is then outcompeted by the returning commensal flora. In conclusion, mucus and ion secretion are dynamically altered during the C. rodentium infection cycle.
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11.
  • Maiti, Arpan K., et al. (författare)
  • Colonic levels of vasoactive intestinal peptide decrease during infection and exogenous VIP protects epithelial mitochondria against the negative effects of IFN gamma and TNF alpha induced during Citrobacter rodentium infection
  • 2018
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Citrobacter rodentium infection is a model for infection with attaching and effacing pathogens, such as enteropathogenic Escherichia coli. The vasoactive intestinal peptide (VIP) has emerged as an anti-inflammatory agent, documented to inhibit Th1 immune responses and successfully treat animal models of inflammation. VIP is also a mucus secretagogue. Here, we found that colonic levels of VIP decrease during murine C. rodentium infection with a similar time dependency as measurements reflecting mitochondrial function and epithelial integrity. The decrease in VIP appears mainly driven by changes in the cytokine environment, as no changes in VIP levels were detected in infected mice lacking interferon gamma (IFN gamma). VIP supplementation alleviated the reduction of activity and levels of mitochondrial respiratory complexes I and IV, mitochondrial phosphorylation capacity, transmembrane potential and ATP generation caused by IFN gamma, TNF alpha and C. rodentium infection, in an in vitro mucosal surface. Similarly, VIP treatment regimens that included the day 5-10 post infection period alleviated decreases in enzyme complexes I and IV, phosphorylation capacity, mitochondrial transmembrane potential and ATP generation as well as increased apoptosis levels during murine infection with C. rodentium. However, VIP treatment failed to alleviate colitis, although there was a tendency to decreased pathogen density in contact with the epithelium and in the spleen. Both in vivo and in vitro, NO generation increased during C. rodentium infection, which was alleviated by VIP. Thus, therapeutic VIP administration to restore the decreased levels during infection had beneficial effects on epithelial cells and their mitochondria, but not on the overall infection outcome.
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12.
  • Maiti, Arpan K., et al. (författare)
  • IL-4 Protects the Mitochondria Against TNF alpha and IFN gamma Induced Insult During Clearance of Infection with Citrobacter rodentium and Escherichia coli
  • 2015
  • Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • Citrobacter rodentium is a murine pathogen that serves as a model for enteropathogenic Escherichia coli. C. rodentium infection reduced the quantity and activity of mitochondrial respiratory complexes I and IV, as well as phosphorylation capacity, mitochondrial transmembrane potential and ATP generation at day 10, 14 and 19 post infection. Cytokine mRNA quantification showed increased levels of IFN gamma, TNF alpha, IL-4, IL-6, and IL-12 during infection. The effects of adding these cytokines, C. rodentium and E. coli were hence elucidated using an in vitro colonic mucosa. Both infection and TNF alpha, individually and combined with IFN gamma, decreased complex I and IV enzyme levels and mitochondrial function. However, IL-4 reversed these effects, and IL-6 protected against loss of complex IV. Both in vivo and in vitro, the dysfunction appeared caused by nitric oxide-generation, and was alleviated by an antioxidant targeting mitochondria. IFN gamma -/- mice, containing a similar pathogen burden but higher IL-4 and IL-6, displayed no loss of any of the four complexes. Thus, the cytokine environment appears to be a more important determinant of mitochondrial function than direct actions of the pathogen. As IFN gamma and TNF alpha levels increase during clearance of infection, the concomitant increase in IL-4 and IL-6 protects mitochondrial function.
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13.
  • Navabi, Nazanin, 1969, et al. (författare)
  • Helicobacter pylori Infection Impairs the Mucin Production Rate and Turnover in the Murine Gastric Mucosa
  • 2013
  • Ingår i: Infection and Immunity. - 0019-9567. ; 81:3, s. 829-837
  • Tidskriftsartikel (refereegranskat)abstract
    • To protect the surface of the stomach, the epithelial cells secrete a mucus layer, which is mainly comprised of the MUC5AC mucin. Further protection is provided by a thick glycocalyx on the apical surface of the epithelial cell, with the cell surface mucin MUC1 as a major component. Here, we investigate the production rate and turnover of newly synthesized mucin in mice and analyze the effects of early colonization and chronic infection with H. pylori. Metabolic incorporation of an azido GalNAc analog (GalNAz) was used as a nonradioactive method to perform pulse experiments in the whole animal. First, the subcellular movement of newly synthesized mucin and mucin turnover was determined in uninfected mice. Based on the time line for mucin transport and dissemination, 2, 6, and 12 h after GalNAz injection was selected to collect the stomachs from mice infected with H. pylori strain SS1 during early colonization (7 days) and chronic infection (90 days). The results demonstrated that the speed from the start of glycosylation to the final destination is faster for the membrane-bound mucin to reach the glycocalyx (2 h) than for the secretory mucins to become secreted into the mucus layer (5 h). Furthermore, infection with H. pylori reduces the rate of mucin turnover and decreases the levels of Muc1. Since H. pylori colonizes this mucus niche, the decreased turnover rate indicates that H. pylori creates a more stable and favorable environment for itself by impairing the defense mechanism for clearing the mucosal surface of pathogens by mucus flow.
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14.
  • Padra, Médea, 1986, et al. (författare)
  • Carbohydrate-Dependent and Antimicrobial Peptide Defence Mechanisms Against Helicobacter pylori Infections
  • 2019
  • Ingår i: Molecular Mechanisms of Inflammation: Induction, Resolution and Escape by Helicobacter pylori. - Cham : Springer. - 9783030151386 ; , s. 179-207
  • Bokkapitel (refereegranskat)abstract
    • The human stomach is a harsh and fluctuating environment for bacteria with hazards such as gastric acid and flow through of gastric contents into the intestine. H. pylori gains admission to a stable niche with nutrient access from exudates when attached to the epithelial cells under the mucus layer, whereof adherence to glycolipids and other factors provides stable and intimate attachment. To reach this niche, H. pylori must overcome mucosal defence mechanisms including the continuously secreted mucus layer, which provides several layers of defence: (1) mucins in the mucus layer can bind H. pylori and transport it away from the gastric niche with the gastric emptying, (2) mucins can inhibit H. pylori growth, both via glycans that can have antibiotic like function and via an aggregation-dependent mechanism, (3) antimicrobial peptides (AMPs) have antimicrobial activity and are retained in a strategic position in the mucus layer and (4) underneath the mucus layer, the membrane-bound mucins provide a second barrier, and can function as releasable decoys. Many of these functions are dependent on H. pylori interactions with host glycan structures, and both the host glycosylation and concentration of antimicrobial peptides change with infection and inflammation, making these interactions dynamic. Here, we review our current understanding of mucin glycan and antimicrobial peptide-dependent host defence mechanisms against H. pylori infection.
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15.
  • Saraiva-Pava, K., et al. (författare)
  • New NCI-N87-derived human gastric epithelial line after human telomerase catalytic subunit over-expression
  • 2015
  • Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327. ; 21:21, s. 6526-6542
  • Tidskriftsartikel (refereegranskat)abstract
    • AIM: To establish a cellular model correctly mimicking the gastric epithelium to overcome the limitation in the study of Helicobacter pylori (H. pylori) infection. METHODS: Aiming to overcome this limitation, clones of the heterogenic cancer-derived NCI-N87 cell line were isolated, by stably-transducing it with the human telomerase reverse-transcriptase (hTERT) catalytic subunit gene. The clones were first characterized regarding their cell growth pattern and phenotype. For that we measured the clones' adherence properties, expression of cell-cell junctions' markers (ZO-1 and E-cadherin) and ability to generate a sustained transepithelial electrical resistance. The gastric properties of the clones, concerning expression of mucins, zymogens and glycan contents, were then evaluated by haematoxylin and eosin staining, Periodic acid Schiff (PAS) and PAS/Alcian Blue-staining, immunocytochemistry and Western blot. In addition, we assessed the usefulness of the hTERT-expressing gastric cell line for H. pylori research, by performing co-culture assays and measuring the IL-8 secretion, by ELISA, upon infection with two H. pylori strains differing in virulence. RESULTS: Compared with the parental cell line, the most promising NCI-hTERT-derived clones (CL5 and CL6) were composed of cells with homogenous phenotype, presented higher relative telomerase activities, better adhesion properties, ability to be maintained in culture for longer periods after confluency, and were more efficient in PAS-reactive mucins secretion. Both clones were shown to produce high amounts of MUC1, MUC2 and MUC13. NCI-hTERT-CL5 mucins were shown to be decorated with blood group H type 2 (BG-H), Lewis-x (Le(x)), Le(y) and Le(a) and, in a less extent, with BG-A antigens, but the former two antigens were not detected in the NCI-hTERT-CL6. None of the clones exhibited detectable levels of MUC6 nor sialylated Le(x) and Le(a) glycans. Entailing good gastric properties, both NCI-hTERT-clones were found to produce pepsinogen-5 and human gastric lipase. The progenitor-like phenotype of NCI-hTERT-CL6 cells was highlighted by large nuclei and by the apical vesicular-like distribution of mucin 5AC and Pg5, supporting the accumulation of mucus-secreting and zymogens-chief mature cells functions. CONCLUSION: These traits, in addition to resistance to microaerobic conditions and good responsiveness to H. pylori co-culture, in a strain virulence-dependent manner, make the NCI-hTERT-CL6 a promising model for future in vitro studies.
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16.
  • Sharba, Sinan, et al. (författare)
  • Interleukin 4 induces rapid mucin transport, increases mucus thickness and quality and decreases colitis and Citrobacter rodentium in contact with epithelial cells
  • 2019
  • Ingår i: Virulence. - : Informa UK Limited. - 2150-5594 .- 2150-5608. ; 10:1, s. 97-117
  • Tidskriftsartikel (refereegranskat)abstract
    • Citrobacter rodentium infection is a murine model for pathogenic intestinal Escherichia coli infection. C. rodentium infection causes an initial decrease in mucus layer thickness, followed by an increase during clearance. We aimed to identify the cause of these changes and to utilize this naturally occurring mucus stimulus to decrease pathogen impact and inflammation. We identified that mucin production and speed of transport from Golgi to secretory vesicles at the apical surface increased concomitantly with increased mucus thickness. Of the cytokines differentially expressed during increased mucus thickness, IFN-gamma and TNF-alpha decreased the mucin production and transport speed, whereas IL-4, IL-13, C. rodentium and E. coli enhanced these aspects. IFN-gamma and TNF-alpha treatment in combination with C. rodentium and pathogenic E. coli infection negatively affected mucus parameters in vitro, which was relieved by IL-4 treatment. The effect of IL-4 was more pronounced than that of IL-13, and in wild type mice, only IL-4 was present. Increased expression of Il-4, Il-4-receptor alpha, Stat6 and Spdef during clearance indicate that this pathway contributes to the increase in mucin production. In vivo IL-4 administration initiated 10 days after infection increased mucus thickness and quality and decreased colitis and pathogen contact with the epithelium. Thus, during clearance of infection, the concomitant increase in IL-4 protects and maintains goblet cell function against the increasing levels of TNF-alpha and IFN-gamma. Furthermore, IL-4 affects intestinal mucus production, pathogen contact with the epithelium and colitis. IL-4 treatment may thus have therapeutic benefits for mucosal healing.
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17.
  • Venkatakrishnan, Vignesh, 1987, et al. (författare)
  • Protein N-glycosylation in the bronchoalveolar space differs between never-smokers and long-term smokers with and without COPD.
  • 2023
  • Ingår i: Glycobiology. - 1460-2423. ; 33:12, s. 1128-1138
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic obstructive pulmonary disease (COPD) kills millions of people annually and patients suffering from exacerbations of this disorder display high morbidity and mortality. The clinical course of COPD is associated with dysbiosis and infections, but the underlying mechanisms are poorly understood. Glycosylation of proteins play roles in regulating interactions between microbes and immune cells, and knowledge on airway glycans therefore contribute to the understanding of infections. Furthermore, glycans have biomarker potential for identifying smokers with enhanced risk for developing COPD as well as COPD subgroups. Here, we characterized the N-glycosylation in the lower airways of healthy never-smokers (HNS, n=5) and long-term smokers (LTS) with (LTS+, n=4) and without COPD (LTS-, n=8). Using mass spectrometry, we identified 57 highly confident N-glycan structures whereof 38 oligomannose, complex, and paucimannose type glycans were common to BAL samples from HNS, LTS-, and LTS+ groups. Hybrid type N-glycans were identified only in the LTS+ group. Qualitatively and quantitatively, HNS had lower inter-individual variation between samples compared to LTS- or LTS+. Cluster analysis of BAL N-glycosylation distinguished LTS from HNS. Correlation analysis with clinical parameters revealed that complex N-glycans were associated with health and absence of smoking whereas oligomannose N-glycans were associated with smoking and disease. The N-glycan profile from monocyte-derived macrophages differed from the BAL N-glycan profiles. In conclusion, long-term smokers display substantial alterations of N-glycosylation in the bronchoalveolar space, and the hybrid N-glycans identified only in long-term smokers with COPD deserve to be further studied as potential biomarkers.
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18.
  • Aspholm, Marina, et al. (författare)
  • Helicobacter pylori adhesion to carbohydrates
  • 2006
  • Ingår i: Methods in Enzymology. - 0076-6879 .- 1557-7988. ; 417, s. 293-339
  • Tidskriftsartikel (refereegranskat)abstract
    • Adherence of bacterial pathogens to host tissues contributes to colonization and virulence and typically involves specific interactions between bacterial proteins called adhesins and cognate oligosaccharide (glycan) or protein motifs in the host that are used as receptors. A given pathogen may have multiple adhesins, each specific for a different set of receptors and, potentially, with different roles in infection and disease. This chapter provides strategies for identifying and analyzing host glycan receptors and the bacterial adhesins that exploit them as receptors, with particular reference to adherence of the gastric pathogen Helicobacter pylori.
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19.
  • Bachar-Wikstrom, Etty, et al. (författare)
  • Identification of Novel Glycans in the Mucus Layer of Shark and Skate Skin
  • 2023
  • Ingår i: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES. - 1661-6596 .- 1422-0067. ; 24:18
  • Tidskriftsartikel (refereegranskat)abstract
    • The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage. While the mucus layers of various bony fish species have been investigated, the composition and glycan profiles of shark skin mucus remain relatively unexplored. In this pilot study, we aimed to explore the structure and composition of shark skin mucus through histological analysis and glycan profiling. Histological examination of skin samples from Atlantic spiny dogfish (Squalus acanthias) sharks and chain catsharks (Scyliorhinus retifer) revealed distinct mucin-producing cells and a mucus layer, indicating the presence of a functional mucus layer similar to bony fish mucus albeit thinner. Glycan profiling using liquid chromatography-electrospray ionization tandem mass spectrometry unveiled a diverse repertoire of mostly O-glycans in the mucus of the two sharks as well as little skate (Leucoraja erinacea). Elasmobranch glycans differ significantly from bony fish, especially in being more sulfated, and some bear resemblance to human glycans, such as gastric mucin O-glycans and H blood group-type glycans. This study contributes to the concept of shark skin having unique properties and provides a foundation for further research into the functional roles and potential biomedical implications of shark skin mucus glycans.
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20.
  • Bachar-Wikstrom, Etty, et al. (författare)
  • Mass Spectrometry Analysis of Shark Skin Proteins
  • 2023
  • Ingår i: International Journal of Molecular Sciences. - 1661-6596 .- 1422-0067. ; 24:23
  • Tidskriftsartikel (refereegranskat)abstract
    • The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage in which proteins play a key role. While proteins in the skin mucus layer of various common bony fish species have been explored, the proteins of shark skin mucus remain unexplored. In this pilot study, we examine the protein composition of the skin mucus in spiny dogfish sharks and chain catsharks through mass spectrometry (NanoLC-MS/MS). Overall, we identified 206 and 72 proteins in spiny dogfish (Squalus acanthias) and chain catsharks (Scyliorhinus retifer), respectively. Categorization showed that the proteins belonged to diverse biological processes and that most proteins were cellular albeit a significant minority were secreted, indicative of mucosal immune roles. The secreted proteins are reviewed in detail with emphasis on their immune potentials. Moreover, STRING protein–protein association network analysis showed that proteins of closely related shark species were more similar as compared to a more distantly related shark and a bony fish, although there were also significant overlaps. This study contributes to the growing field of molecular shark studies and provides a foundation for further research into the functional roles and potential human biomedical implications of shark skin mucus proteins.
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21.
  • Banerjee, Debashish, et al. (författare)
  • Epithelial MUC1/Muc1 Promotes Cell migration, Reduces Apoptosis and Affects Levels of Mucosal Modulators During Acetylsalicylic Acid (Aspirin) Induced Gastropathy.
  • 2015
  • Ingår i: The Biochemical journal. - 1470-8728. ; 465:3, s. 423-431
  • Tidskriftsartikel (refereegranskat)abstract
    • MUC1 is a transmembrane mucin highly expressed in the stomach. While extensive research has uncovered many of its roles in cancer, knowledge about the functions of MUC1 in normal tissues is limited. Here we showed that acetylsalicylic acid (Aspirin, ASA) upregulated MUC1/Muc1 expression in the gastric mucosa of humans and wild type mice. ASA induced mucosal injury in all mice to a similar extent, however wild type animals and those chimeras with Muc1 on the epithelia recovered faster than Muc1 knock-out mice and chimeras carrying Muc1 on haematopoietic but not epithelial cells. MUC1 enhanced proliferation and migration of the human gastric cell line MKN-7, and increased resistance to apoptosis. The repeated treatment regime used caused a reduction in cyclooxygenase-1 expression, though wild type animals returned faster towards pre-treatment levels, and had increased cyclooxygenase-2 and vascular endothelial growth factor levels during recovery. Thus, we found that epithelial Muc1 is more important for the healing process than haematopoetic Muc1, and Muc1/MUC1 facilitates wound healing by enhancing cell migration and proliferation, protecting against apoptosis and mediating expression of mucosal modulators. Thus, MUC1 plays essential roles during wound healing, and development of treatment modalities targeting enhanced expression of MUC1 may be beneficial to treat mucosal wounds.
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22.
  • Benktander, John, et al. (författare)
  • Aeromonas salmonicida binds α2-6 linked sialic acid, which is absent among the glycosphingolipid repertoires from skin, gill, stomach, pyloric caecum, and intestine
  • 2022
  • Ingår i: Virulence. - : Informa UK Limited. - 2150-5594 .- 2150-5608. ; 13:1, s. 1741-1751
  • Tidskriftsartikel (refereegranskat)abstract
    • Carbohydrates can both protect against infection and act as targets promoting infection. Mucins are major components of the slimy mucus layer covering the fish epithelia. Mucins can act as decoys for intimate pathogen interaction with the host afforded by binding to glycosphingolipids in the host cell membrane. We isolated and characterized glycosphingolipids from Atlantic salmon skin, gill, stomach, pyloric caeca, and intestine. We characterized the glycosphingolipids using liquid chromatography–mass spectrometry and tandem mass spectrometry and the glycan repertoire was compared with the glycan repertoire of mucins from the same epithelia. We also investigated Aeromonas salmonicida binding using chromatogram and microtiter well based binding assays. We identified 29 glycosphingolipids. All detected acid glycans were of the ganglio-series (unless shorter) and showed a high degree of polysialylation. The non-acid glycans were mostly composed of the neolacto, globo, and ganglio core structures. The glycosphingolipid repertoire differed between epithelia and the proportion of the terminal moieties of the glycosphingolipids did not reflect the terminal moieties on the mucins from the same epithelia. A. salmonicida did not bind the Atlantic salmon glycosphingolipids. Instead, we identified that A. salmonicida binding to sialic acid occurred to α2–6 Neu5Ac but not to α2–3 Neu5Ac. α2–6 Neu5Ac was present on mucins whereas mainly α2–3 Neu5Ac was found on the glycosphingolipids, explaining the difference in A. salmonicida binding ability between these host glycoconjugates. A. salmonicida´s ability to bind to Atlantic salmon mucins, but not the glycosphingolipids, is likely part of the host defence against this pathogen.
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23.
  • Benktander, John, et al. (författare)
  • Characterization of the rainbow trout (Oncorhynchus mykiss) mucosal glycosphingolipid repertoire and Aeromonas salmonicida binding to neutral glycosphingolipids
  • 2024
  • Ingår i: GLYCOBIOLOGY. - 0959-6658 .- 1460-2423. ; 34:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Infections pose a challenge for the fast growing aquaculture sector. Glycosphingolipids are cell membrane components that pathogens utilize for attachment to the host to initiate infection. Here, we characterized rainbow trout glycosphingolipids from five mucosal tissues using mass spectrometry and nuclear magnetic resonance and investigated binding of radiolabeled Aeromonas salmonicida to the glycosphingolipids on thin-layer chromatograms. 12 neutral and 14 acidic glycosphingolipids were identified. The glycosphingolipids isolated from the stomach and intestine were mainly neutral, whereas glycosphingolipids isolated from the skin, gills and pyloric caeca were largely acidic. Many of the acidic structures were poly-sialylated with shorter glycan structures in the skin compared to the other tissues. The sialic acids found were Neu5Ac and Neu5Gc. Most of the glycosphingolipids had isoglobo and ganglio core chains, or a combination of these. The epitopes on the rainbow trout glycosphingolipid glycans differed between epithelial sites leading to differences in pathogen binding. A major terminal epitope was fucose, that occurred attached to GalNAc in a alpha 1-3 linkage but also in the form of HexNAc-(Fuc-)HexNAc-R. A. salmonicida were shown to bind to neutral glycosphingolipids from the gill and intestine. This study is the first to do a comprehensive investigation of the rainbow trout glycosphingolipids and analyze binding of A. salmonicida to glycosphingolipids. The structural information paves the way for identification of ways of interfering in pathogen colonization processes to protect against infections in aquaculture and contributes towards understanding A. salmonicida infection mechanisms.
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24.
  • Benktander, John, et al. (författare)
  • Effects of Size and Geographical Origin on Atlantic salmon, Salmo salar, Mucin O-Glycan Repertoire
  • 2019
  • Ingår i: Molecular & Cellular Proteomics. - 1535-9476. ; 18:6, s. 1183-1196
  • Tidskriftsartikel (refereegranskat)abstract
    • Diseases cause ethical concerns and economic losses in the Salmonid industry. The mucus layer comprised of highly O-glycosylated mucins is the first contact between pathogens and fish. Mucin glycans govern pathogen adhesion, growth and virulence. The Atlantic salmon O-glycome from a single location has been characterized and the interindividual variation was low. Because interindividual variation is considered a population-based defense, hindering the entire population from being wiped out by a single infection, low interindividual variation among Atlantic salmon may be a concern. Here, we analyzed the O-glycome of 25 Atlantic salmon from six cohorts grown under various conditions from Sweden, Norway and Australia (Tasmania) using mass spectrometry. This expanded the known Atlantic salmon O-glycome by 60% to 169 identified structures. The mucin O-glycosylation was relatively stable over time within a geographical region, but the size of the fish affected skin mucin glycosylation. The skin mucin glycan repertoires from Swedish and Norwegian Atlantic salmon populations were closely related compared with Tasmanian ones, regardless of size and salinity, with differences in glycan size and composition. The internal mucin glycan repertoire also clustered based on geographical origin and into pyloric cecal and distal intestinal groups, regardless of cohort and fish size. Fucosylated structures were more abundant in Tasmanian pyloric caeca and distal intestine mucins compared with Swedish ones. Overall, Tasmanian Atlantic salmon mucins have more O-glycan structures in skin but less in the gastrointestinal tract compared with Swedish fish. Low interindividual variation was confirmed within each cohort. The results can serve as a library for identifying structures of importance for host-pathogen interactions, understanding population differences of salmon mucin glycosylation in resistance to diseases and during breeding and selection of strains. The results could make it possible to predict potential vulnerabilities to diseases and suggest that inter-region breeding may increase the glycan diversity.
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25.
  • Benktander, John, et al. (författare)
  • Gill Mucus and Gill Mucin O-glycosylation in Healthy and Amebic Gill Disease-Affected Atlantic Salmon.
  • 2020
  • Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 8:12
  • Tidskriftsartikel (refereegranskat)abstract
    • Amoebic gill disease (AGD) causes poor performance and death in salmonids. Mucins are mainly comprised by carbohydrates and are main components of the mucus covering the gill. Since glycans regulate pathogen binding and growth, glycosylation changes may affect susceptibility to primary and secondary infections. We investigated gill mucin O-glycosylation from Atlantic salmon with and without AGD using liquid chromatography-mass spectrometry. Gill mucin glycans were larger and more complex, diverse and fucosylated than skin mucins. Confocal microscopy revealed that fucosylated mucus coated sialylated mucus strands in ex vivo gill mucus. Terminal HexNAcs were more abundant among O-glycans from AGD-affected Atlantic salmon, whereas core 1 structures and structures with acidic moieties such as N-acetylneuraminic acid (NeuAc) and sulfate groups were less abundant compared to non-infected fish. The fucosylated and NeuAc-containing O-glycans were inversely proportional, with infected fish on the lower scale of NeuAc abundance and high on fucosylated structures. The fucosylated epitopes were of three types: Fuc-HexNAc-R, Gal-[Fuc-]HexNAc-R and HexNAc-[Fuc-]HexNAc-R. These blood group-like structures could be an avenue to diversify the glycan repertoire to limit infection in the exposed gills. Furthermore, care must be taken when using skin mucus as proxy for gill mucus, as gill mucins are distinctly different from skin mucins.
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26.
  • Benktander, John, et al. (författare)
  • Stress impairs skin barrier function and induces α2-3 linked n-acetylneuraminic acid and core 1 o-glycans on skin mucins in atlantic salmon, salmo salar
  • 2021
  • Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:3
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The skin barrier consists of mucus, primarily comprising highly glycosylated mucins, and the epithelium. Host mucin glycosylation governs interactions with pathogens and stress is associated with impaired epithelial barrier function. We characterized Atlantic salmon skin barrier function during chronic stress (high density) and mucin O-glycosylation changes in response to acute and chronic stress. Fish held at low (LD: 14–30 kg/m3) and high densities (HD: 50-80 kg/m3) were subjected to acute stress 24 h before sampling at 17 and 21 weeks after start of the experiment. Blood parameters indicated primary and secondary stress responses at both sampling points. At the second sampling, skin barrier function towards molecules was reduced in the HD compared to the LD group (Papp mannitol; p < 0.01). Liquid chromatography–mass spectrometry revealed 81 O-glycan structures from the skin. Fish subjected to both chronic and acute stress had an increased proportion of large O-glycan structures. Overall, four of the O-glycan changes have potential as indicators of stress, especially for the combined chronic and acute stress. Stress thus impairs skin barrier function and induces glycosylation changes, which have potential to both affect interactions with pathogens and serve as stress indicators.
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27.
  • Benktander, John, et al. (författare)
  • The Repertoire of Glycosphingolipids Recognized by Vibrio cholerae
  • 2013
  • Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The binding of cholera toxin to the ganglioside GM1 as the initial step in the process leading to diarrhea is nowadays textbook knowledge. In contrast, the knowledge about the mechanisms for attachment of Vibrio cholerae bacterial cells to the intestinal epithelium is limited. In order to clarify this issue, a large number of glycosphingolipid mixtures were screened for binding of El Tor V. cholerae. Several specific interactions with minor complex non-acid glycosphingolipids were thereby detected. After isolation of binding-active glycosphingolipids, characterization by mass spectrometry and proton NMR, and comparative binding studies, three distinct glycosphingolipid binding patterns were defined. Firstly, V. cholerae bound to complex lacto/neolacto glycosphingolipids with the GlcNAcβ3Galβ4GlcNAc sequence as the minimal binding epitope. Secondly, glycosphingolipids with a terminal Galα3Galα3Gal moiety were recognized, and the third specificity was the binding to lactosylceramide and related compounds. V. cholerae binding to lacto/neolacto glycosphingolipids, and to the other classes of binding-active compounds, remained after deletion of the chitin binding protein GbpA. Thus, the binding of V. cholerae to chitin and to lacto/neolacto containing glycosphingolipids represents two separate binding specificities.
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28.
  • Birchenough, George M. H., et al. (författare)
  • Muc2-dependent microbial colonization of the jejunal mucus layer is diet sensitive and confers local resistance to enteric pathogen infection
  • 2023
  • Ingår i: Cell Reports. - Cambridge : Elsevier BV. - 2211-1247. ; 42:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Intestinal mucus barriers normally prevent microbial infections but are sensitive to diet-dependent changes in the luminal environment. Here we demonstrate that mice fed a Western-style diet (WSD) suffer regiospe-cific failure of the mucus barrier in the small intestinal jejunum caused by diet-induced mucus aggregation. Mucus barrier disruption due to either WSD exposure or chromosomal Muc2 deletion results in collapse of the commensal jejunal microbiota, which in turn sensitizes mice to atypical jejunal colonization by the enteric pathogen Citrobacter rodentium. We illustrate the jejunal mucus layer as a microbial habitat, and link the re-giospecific mucus dependency of the microbiota to distinctive properties of the jejunal niche. Together, our data demonstrate a symbiotic mucus-microbiota relationship that normally prevents jejunal pathogen colo-nization, but is highly sensitive to disruption by exposure to a WSD.
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29.
  • Breugelmans, T., et al. (författare)
  • In-Depth Study of Transmembrane Mucins in Association with Intestinal Barrier Dysfunction During the Course of T Cell Transfer and DSS-Induced Colitis
  • 2020
  • Ingår i: Journal of Crohns & Colitis. - : Oxford University Press (OUP). - 1873-9946. ; 14:7, s. 974-994
  • Tidskriftsartikel (refereegranskat)abstract
    • Background and Aims: There is evidence for a disturbed intestinal barrier function in inflammatory bowel diseases [IBD] but the underlying mechanisms are unclear. Because mucins represent the major components of the mucus barrier and disturbed mucin expression is reported in the colon of IBD patients, we studied the association between mucin expression, inflammation and intestinal permeability in experimental colitis. Methods: We quantified 4-kDa FITC-dextran intestinal permeability and the expression of cytokines, mucins, junctional and polarity proteins at dedicated time points in the adoptive T cell transfer and dextran sodium sulfate [DSS]-induced colitis models. Mucin expression was also validated in biopsies from IBD patients. Results: In both animal models, the course of colitis was associated with increased interleukin-1 beta [IL-1 beta] and tumour necrosis factor-alpha [TNF-alpha] expression and increased Muc1 and Muc13 expression. In the T cell transfer model, a gradually increasing Muc1 expression coincided with gradually increasing 4-kDa FITC-dextran intestinal permeability and correlated with enhanced IL-1 beta expression. In the DSS model, Muc13 expression coincided with rapidly increased 4-kDa FITC-dextran intestinal permeability and correlated withTNF-alpha and Muc1 overexpression. Moreover, a significant association was observed between Muc1, Cldn1, Ocln, Par3 and aPKC zeta expression in the T cell transfer model and between Muc13, Cldn1, Jam2, Tjp2, aPkc zeta, Crb3 and Scrib expression in the DSS model. Additionally, MUC1 and MUC13 expression was upregulated in inflamed mucosa of IBD patients. Conclusions: Aberrantly expressed MUC1 and MUC13 might be involved in intestinal barrier dysfunction upon inflammation by affecting junctional and cell polarity proteins, indicating their potential as therapeutic targets in IBD.
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30.
  • Chahal, Gurdeep, et al. (författare)
  • A Complex Connection Between the Diversity of Human Gastric Mucin O-Glycans, Helicobacter pylori Binding, Helicobacter Infection and Fucosylation
  • 2022
  • Ingår i: Molecular & Cellular Proteomics. - : Elsevier BV. - 1535-9476 .- 1535-9484. ; 21:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Helicobacter pylori colonizes the stomach of half of the human population. Most H. pylori are located in the mucus layer, which is mainly comprised by glycosylated mucins. Using mass spectrometry, we identified 631 glycans (whereof 145 were fully characterized and the remainder assigned as compositions) on mucins isolated from 14 Helicobacter spp.-infected and 14 Helicobacter spp.-noninfected stomachs. Only six identified glycans were common to all individuals, from a total of 60 to 189 glycans in each individual. An increased number of unique glycan structures together with an increased intra-individual diversity and larger interindividual variation were identified among O-glycans from Helicobacter spp.-infected stomachs compared with noninfected stom-achs. H. pylori strain J99, which carries the blood group antigen-binding adhesin (BabA), the sialic acid-binding adhesin (SabA), and the LacdiNAc-binding adhesin, bound both to Lewis b (Leb)-positive and Leb-negative mucins. Among Leb-positive mucins, H. pylori J99 bind-ing was higher to mucins from Helicobacter spp.-infected individuals than noninfected individuals. Statistical corre-lation analysis, binding experiments with J99 wt, and J99 Delta babA Delta sabA and inhibition experiments using syn-thetic glycoconjugates demonstrated that the differences in H. pylori-binding ability among these four groups were governed by BabA-dependent binding to fucosylated structures. LacdiNAc levels were lower in mucins that bound to J99 lacking BabA and SabA than in mucins that did not, suggesting that LacdiNAc did not significantly contribute to the binding. We identified 24 O-glycans from Leb-negative mucins that correlated well with H. pylori binding whereof 23 contained alpha 1,2-linked fucosylation. The large and diverse gastric glycan library identified, including structures that correlated with H. pylori binding, could be used to select glycodeterminants to experimen-tally investigate further for their importance in host- pathogen interactions and as candidates to develop glycan-based therapies.
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31.
  • Chahal, Gurdeep, et al. (författare)
  • Streptococcus oralis Employs Multiple Mechanisms of Salivary Mucin Binding That Differ Between Strains
  • 2022
  • Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media SA. - 2235-2988. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • Streptococcus oralis is an oral commensal and opportunistic pathogen that can enter the bloodstream and cause bacteremia and infective endocarditis. Here, we investigated the mechanisms of S. oralis binding to oral mucins using clinical isolates, isogenic mutants and glycoconjugates. S. oralis bound to both MUC5B and MUC7, with a higher level of binding to MUC7. Mass spectrometry identified 128 glycans on MUC5B, MUC7 and the salivary agglutinin (SAG). MUC7/SAG contained a higher relative abundance of Lewis type structures, including Lewis b/y, sialyl-Lewis a/x and alpha 2,3-linked sialic acid, compared to MUC5B. S. oralis subsp. oralis binding to MUC5B and MUC7/SAG was inhibited by Lewis b and Lacto-N-tetraose glycoconjugates. In addition, S. oralis binding to MUC7/SAG was inhibited by sialyl Lewis x. Binding was not inhibited by Lacto-N-fucopentaose, H type 2 and Lewis x conjugates. These data suggest that three distinct carbohydrate binding specificities are involved in S. oralis subsp. oralis binding to oral mucins and that the mechanisms of binding MUC5B and MUC7 differ. Efficient binding of S. oralis subsp. oralis to MUC5B and MUC7 required the gene encoding sortase A, suggesting that the adhesin(s) are LPXTG-containing surface protein(s). Further investigation demonstrated that one of these adhesins is the sialic acid binding protein AsaA.
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32.
  • Cheng, Liu, et al. (författare)
  • The Helicobacter heilmannii hofE and hofF Genes are Essential for Colonization of the Gastric Mucosa and Play a Role in IL-1β-Induced Gastric MUC13 Expression
  • 2016
  • Ingår i: Helicobacter. - : Wiley. - 1083-4389 .- 1523-5378. ; 21:6, s. 504-522
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Helicobacter heilmannii is a zoonotic bacterium associated with gastric disease in humans. We recently showed that H. heilmannii binds to human gastric mucins and epithelial cells and highlighted a potential role for the murine Muc13 mucin in gastric Helicobacter colonization. The aims of this study were to investigate the role of the H. heilmannii hof gene locus encoding HofH/F/E/G/C/D in adhesion to the gastric mucosa and induction of increased gastric Muc13 expression. Methods: Bacterial hof gene and host gene expression experiments, Helicobacter binding assays and experimental infection studies in mice were performed. H. pylori and its ΔhofF mutant were included for comparison. Results: Helicobacter heilmannii strains lacking HofE or HofF showed a clear decrease in binding to gastric mucins and epithelial cells as well as a lower gastric colonization level in the stomach of Balb/c mice at 4 and 9 weeks post-infection compared to the H. heilmannii wildtype strain. Interestingly, H. heilmannii ΔhofE and ΔhofF and H. pylori ΔhofF did not induce an increased expression of MUC13 in human gastric epithelial cells and of Muc13 in the stomach of mice. Finally, we demonstrated that IL-1β is induced in the stomach as a response to Helicobacter colonization which on its turn is involved in the expression of MUC13/Muc13 in the gastric epithelium. Conclusion: These novel results in Helicobacter research identified H. heilmannii HofE and HofF as adhesins and suggest an important role of H. heilmannii HofE and HofF and H. pylori HofF in IL-1β-induced gastric MUC13/Muc13 expression.
  •  
33.
  • Constantino, M. A., et al. (författare)
  • Bipolar lophotrichous Helicobacter suis combine extended and wrapped flagella bundles to exhibit multiple modes of motility
  • 2018
  • Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • The swimming strategies of unipolar flagellated bacteria are well known but little is known about how bipolar bacteria swim. Here we examine the motility of Helicobacter suis, a bipolar gastric-ulcer-causing bacterium that infects pigs and humans. Phase-contrast microscopy of unlabeled bacteria reveals flagella bundles in two conformations, extended away from the body (E) or flipped backwards and wrapped (W) around the body. We captured videos of the transition between these two states and observed three different swimming modes in broth: with one bundle rotating wrapped around the body and the other extended (EW), both extended (EE), and both wrapped (WW). Only EW and WW modes were seen in porcine gastric mucin. The EW mode displayed ballistic trajectories while the other two displayed superdiffusive random walk trajectories with slower swimming speeds. Separation into these two categories was also observed by tracking the mean square displacement of thousands of trajectories at lower magnification. Using the Method of Regularized Stokeslets we numerically calculate the swimming dynamics of these three different swimming modes and obtain good qualitative agreement with the measurements, including the decreased speed of the less frequent modes. Our results suggest that the extended bundle dominates the swimming dynamics.
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34.
  • Dahlhoff, Maik, et al. (författare)
  • A new mouse model for studying EGFR-dependent gastric polyps.
  • 2012
  • Ingår i: Biochimica et biophysica acta. - : Elsevier BV. - 0006-3002. ; 1822:8, s. 1293-1299
  • Tidskriftsartikel (refereegranskat)abstract
    • Hyperactivation of the epidermal growth factor receptor (EGFR) in gastric cells due to excess of its ligand transforming growth factor-α (TGFA) is associated with hyperplastic lesions in Ménétrier's disease patients and in transgenic mice. Other EGFR ligands, however, have never been associated with stomach diseases. Here, we report that overexpression of the EGFR ligand betacellulin (BTC) results in a severe, age-dependent hyperplasia of foveolar epithelium. The stomach weight of affected mice reached up to 3g representing more than 10% of total body weight. The preexisting corpus mucosa was severely depleted, and both parietal and chief cells were replaced by proliferating foveolar epithelium. The lesions were more severe in male as compared to female transgenic mice, and partially regressed in the former after castration-mediated androgen removal. The gastric hyperplasia fully disappeared when BTC-tg mice were crossed into the Egfr(Wa5) background expressing a dominant-negative EGFR, indicating that the phenotype is EGFR-dependent. This is, to our knowledge, the first report of hyperplastic gastric lesions due to the overexpression of an EGFR ligand other than TGFA. BTC-tg mice are therefore a new, promising model for studying EGFR-dependent gastric polyps.
  •  
35.
  • de Klerk, N., et al. (författare)
  • Lactobacilli Reduce Helicobacter pylori Attachment to Host Gastric Epithelial Cells by Inhibiting Adhesion Gene Expression
  • 2016
  • Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 84:5, s. 1526-1535
  • Tidskriftsartikel (refereegranskat)abstract
    • The human gastrointestinal tract, including the harsh environment of the stomach, harbors a large variety of bacteria, of which Lactobacillus species are prominent members. The molecular mechanisms by which species of lactobacilli interfere with pathogen colonization are not fully characterized. In this study, we aimed to study the effect of lactobacillus strains upon the initial attachment of Helicobacter pylori to host cells. Here we report a novel mechanism by which lactobacilli inhibit adherence of the gastric pathogen H. pylori. In a screen with Lactobacillus isolates, we found that only a few could reduce adherence of H. pylori to gastric epithelial cells. Decreased attachment was not due to competition for space or to lactobacillus-mediated killing of the pathogen. Instead, we show that lactobacilli act on H. pylori directly by an effector molecule that is released into the medium. This effector molecule acts on H. pylori by inhibiting expression of the adhesin-encoding gene sabA. Finally, we verified that inhibitory lactobacilli reduced H. pylori colonization in an in vivo model. In conclusion, certain Lactobacillus strains affect pathogen adherence by inhibiting sabA expression and thereby reducing H. pylori binding capacity.
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36.
  • Fernandez, Harvey Robert, et al. (författare)
  • The aspirin metabolite salicylate inhibits lysine acetyltransferases and MUC1 induced epithelial to mesenchymal transition
  • 2017
  • Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • MUC1 is a transmembrane mucin that can promote cancer progression, and its upregulation correlates with a worse prognosis in colon cancer. We examined the effects of overexpression of MUC1 in colon cancer cells, finding that it induced epithelial to mesenchymal transition (EMT), including enhanced migration and invasion, and increased Akt phosphorylation. When the clones were treated with the aspirin metabolite salicylate, Akt phosphorylation was decreased and EMT inhibited. As the salicylate motif is necessary for the activity of the lysine acetyltransferase (KAT) inhibitor anacardic acid, we hypothesized these effects were associated with the inhibition of KAT activity. This was supported by anacardic acid treatment producing the same effect on EMT. In vitro KAT assays confirmed that salicylate directly inhibited PCAF/Kat2b, Tip60/Kat5 and hMOF/Kat8, and this inhibition was likely involved in the reversal of EMT in the metastatic prostate cancer cell line PC-3. Salicylate treatment also inhibited EMT induced by cytokines, illustrating the general effect it had on this process. The inhibition of both EMT and KATs by salicylate presents a little explored activity that could explain some of the anti-cancer effects of aspirin.
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37.
  • Flahou, Bram, et al. (författare)
  • Evidence for a primate origin of zoonotic Helicobacter suis colonizing domesticated pigs.
  • 2018
  • Ingår i: The ISME journal. - : Springer Science and Business Media LLC. - 1751-7370 .- 1751-7362. ; 12:1, s. 77-86
  • Tidskriftsartikel (refereegranskat)abstract
    • Helicobacter suis is the second most prevalent Helicobacter species in the stomach of humans suffering from gastric disease. This bacterium mainly inhabits the stomach of domesticated pigs, in which it causes gastric disease, but it appears to be absent in wild boars. Interestingly, it also colonizes the stomach of asymptomatic rhesus and cynomolgus monkeys. The origin of modern human-, pig- or non-human primate-associated H. suis strains in these respective host populations was hitherto unknown. Here we show that H. suis in pigs possibly originates from non-human primates. Our data suggest that a host jump from macaques to pigs happened between 100000 and 15000 years ago and that pig domestication has had a significant impact on the spread of H. suis in the pig population, from where this pathogen occasionally infects humans. Thus, in contrast to our expectations, H. suis appears to have evolved in its main host in a completely different way than its close relative Helicobacter pylori in humans.
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38.
  • Jin, Chunsheng, et al. (författare)
  • Atlantic Salmon Carries a Range of Novel O-Glycan Structures Differentially Localized on Skin and Intestinal Mucins
  • 2015
  • Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 14:8, s. 3239-3251
  • Tidskriftsartikel (refereegranskat)abstract
    • Aquaculture is a growing industry, increasing the need for understanding host-pathogen interactions in fish. The skin and mucosal surfaces, covered by a mucus layer composed of mucins, is the first point of contact between fish and pathogens. Highly O-glycosylated mucins have been shown to be an important part of the defense against pathogens, and pathogens bind to host surfaces using lectin-like adhesins. However, knowledge of piscine O-glycosylation is very limited. We characterized mucin O-glycosylation of five freshwater acclimated Atlantic salmon, using mass spectrometry. Of the 109 O-glycans found, most were sialylated and differed in distribution among skin, pyloric ceca, and proximal and distal intestine. Skin O-glycans were shorter (2-6 residues) and less diverse (33 structures) than intestinal O-glycans (2-13 residues, 93 structures). Skin mucins carried O-glycan cores 1, 2, 3, and 5 and three types of sialic acids (Neu5Ac, Neu5Gc, and Kdn) and had sialyl-Tn as the predominant structure. Intestinal mucins carried only cores 1, 2, and 5, Neu5Ac was the only sialic acid present, and sialylated core S was the most dominant structure. This structural characterization can be used for identifying structures of putative importance in host-pathogen interactions for further testing in biological assays and disease intervention therapies.
  •  
39.
  • Jin, Chunsheng, et al. (författare)
  • Structural diversity of human gastric mucin glycans.
  • 2017
  • Ingår i: Molecular & cellular proteomics : MCP. - 1535-9484.
  • Tidskriftsartikel (refereegranskat)abstract
    • The mucin O-glycosylation of 10 individuals with and without gastric disease was examined in depth in order to generate a structural map of human gastric glycosylation. In the stomach, these mucins and their O-glycosylation protect the epithelial surface from the acidic gastric juice and provide the first point of interaction for pathogens such as Helicobacter pylori, reported to cause gastritis, gastric and duodenal ulcers and gastric cancer. The rational of the present study was to map the O-glycosylation that the pathogen may come in contact with. An enormous diversity in glycosylation was found, which varied both between individuals and within mucins from a single individual: mucin glycan chain length ranged from 2-13 residues, each individual carried 34-103 O-glycan structures and in total over 258 structures were identified. The majority of gastric O-glycans were neutral and fucosylated. Blood group I antigens, as well as terminal α1,4-GlcNAc-like and GalNAcβ1-4GlcNAc-like (LacdiNAc-like), were common modifications of human gastric O-glycans. Furthemore, each individual carried 1-14 glycan structures that were unique for that individual. The diversity and alterations in gastric O-glycosylation broaden our understanding of the human gastric O-glycome and its implications for gastric cancer research and emphasize that the high individual variation makes it difficult to identify gastric cancer specific structures. However, despite the low number of individuals, we could verify a higher level of sialylation and sulfation on gastric O-glycans from cancerous tissue than from healthy stomachs.
  •  
40.
  • Joosten, Myrthe, et al. (författare)
  • Divergence between the highly virulent zoonotic pathogen Helicobacter heilmannii and its closest relative, the low virulent Helicobacter ailurogastricus sp. nov.
  • 2016
  • Ingår i: Infection and immunity. - 1098-5522. ; 84:1, s. 293-306
  • Tidskriftsartikel (refereegranskat)abstract
    • Helicobacter heilmannii naturally colonizes the stomach of dogs and cats, and has been associated with gastric disorders in humans. Nine feline Helicobacter strains, classified as H. heilmannii based on ureAB and 16S rRNA gene sequences, were divided into a highly virulent and a low virulent group. The genomes of these strains were sequenced to investigate their phylogenetic relationships, to define their gene content and diversity and to determine if the differences in pathogenicity were associated with the presence/absence of potential virulence genes. The binding capacity of these helicobacters to the gastric mucosa was investigated as well.Our analyses revealed that the low virulent strains do not belong to the H. heilmannii species, but to a novel, closely related species for which we propose the name H. ailurogastricus. Several homologs of H. pylori virulence factors, such as IceA1, HrgA and jhp0562-like glycosyltransferase, are present in H. heilmannii but absent in H. ailurogastricus. Both species contain a VacA-like autotransporter, from which the passenger domain is remarkably larger for H. ailurogastricus compared to H. heilmannii. In addition, H. ailurogastricus shows clear differences in binding to the gastric mucosa compared to H. heilmannii. These findings highlight the low virulent character of this novel Helicobacter species.
  •  
41.
  • Kenny, Diarmuid T., et al. (författare)
  • Presence of terminal N-acetylgalactosamineβ1-4N-acetylglucosamine residues on O-linked oligosaccharides from gastric MUC5AC: involvement in Helicobacter pylori colonization?
  • 2012
  • Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 22:8, s. 1077-85
  • Tidskriftsartikel (refereegranskat)abstract
    • Isolation of MUC5AC mucins from the gastric mucosa from two secretor individuals (one from normal mucosa from a patient with gastric cancer and one from a control) showed different abilities to bind and induce the proliferation of the Helicobacter pylori strain J99. Analysis of the released O-linked oligosaccharides by LC-MS from these individuals showed a very heterogeneous mixture of species from the cancer patient containing both neutral and sialylated structures, whereas the normal sample showed dominating neutral blood group H terminating structures as well as neutral structures containing the di-N-acetyllactosamine (lacdiNAc) unit GalNAcβ1-4GlcNAcβ1- on the C-6 branch of the reducing end GalNAc. The linkage configuration of these epitopes were determined using C-4-specific fragmentation for the GalNAcβ1-4GlcNAcβ1- glycosidic linkage, comparison of the MS(3) fragmentation with standards for linkage configuration and N-acetylhexosamine type as well as exoglycosidase treatment. It was also shown that the lacdiNAc epitope is present in both human and porcine gastric mucins, indicating that this is an epitope preserved between species. We hypothesize that the termination on gastric MUC5AC with lacdiNAc is in competition with complex glycosylation such as the Le(b) and H type 1 as well as complex sialylated structures. These are epitopes known to bind the H. pylori BabA and SabA adhesins.
  •  
42.
  • Lindén, Sara K., 1974, et al. (författare)
  • H. pylori adhesion to the gastric surface.
  • 2010
  • Ingår i: Helicobacter pylori in the 21st Century. - Nottingham : CABI.
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
  •  
43.
  • Lindén, Sara K., 1974, et al. (författare)
  • Microbes at the host surface
  • 2010
  • Ingår i: Current Research, Technology and Education Topics in Applied Microbiology and Microbial Biotechnology. ; , s. 591-596
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • The human body encounters pathogenic bacteria every day although establishment of infections after such contacts is rare. The skin and mucosal surfaces, which comprise the barrier between the body and the external milieu, are the first lines of defense, and colonization of these surfaces is normally the first step in bacterial disease. As a physical barrier, the skin is reinforced by dry, slightly acidic conditions, sloughing of cells and a resident microflora. The non-keratinized mucosal surfaces have functions such as secretion of digestive enzymes and absorption of nutrients that require the barrier to be ‘semi-permeable’ with ensuing demands on their design. In addition to a resident microflora and sloughing of cells, the mucosal surfaces are protected by a mucus layer. This gel-like layer is formed by highly glycosylated proteins referred to as mucins and is efficient in trapping microorganisms. The underlying cells relay signals to activate the immune system and mobilization of tissue and blood defense mechanisms is an important aspect of host defense. However, such mechanisms may be accompanied by tissue damage, and infectious diseases are often aggravated by an excessive host response to the invading pathogen. Invading pathogens also have weapons to fight the host with, for example mucindegrading enzymes to disrupt mucus, toxins to disrupt epithelial integrity, and structures to adhere to the host and facilitate invasion. This review will focus on the interplay between the host and bacteria at the mucosal surfaces, which forms a barrier between the inside and the outside of the body.
  •  
44.
  • Lindén, Sara K., 1974, et al. (författare)
  • MUC1 limits Helicobacter pylori infection both by steric hindrance and by acting as a releasable decoy.
  • 2009
  • Ingår i: PLoS pathogens. - : Public Library of Science (PLoS). - 1553-7374. ; 5:10
  • Tidskriftsartikel (refereegranskat)abstract
    • The bacterium Helicobacter pylori can cause peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. The cell-surface mucin MUC1 is a large glycoprotein which is highly expressed on the mucosal surface and limits the density of H. pylori in a murine infection model. We now demonstrate that by using the BabA and SabA adhesins, H. pylori bind MUC1 isolated from human gastric cells and MUC1 shed into gastric juice. Both H. pylori carrying these adhesins, and beads coated with MUC1 antibodies, induced shedding of MUC1 from MKN7 human gastric epithelial cells, and shed MUC1 was found bound to H. pylori. Shedding of MUC1 from non-infected cells was not mediated by the known MUC1 sheddases ADAM17 and MMP-14. However, knockdown of MMP-14 partially affected MUC1 release early in infection, whereas ADAM17 had no effect. Thus, it is likely that shedding is mediated both by proteases and by disassociation of the non-covalent interaction between the alpha- and beta-subunits. H. pylori bound more readily to MUC1 depleted cells even when the bacteria lacked the BabA and SabA adhesins, showing that MUC1 inhibits attachment even when bacteria cannot bind to the mucin. Bacteria lacking both the BabA and SabA adhesins caused less apoptosis in MKN7 cells than wild-type bacteria, having a greater effect than deletion of the CagA pathogenicity gene. Deficiency of MUC1/Muc1 resulted in increased epithelial cell apoptosis, both in MKN7 cells in vitro, and in H. pylori infected mice. Thus, MUC1 protects the epithelium from non-MUC1 binding bacteria by inhibiting adhesion to the cell surface by steric hindrance, and from MUC1-binding bacteria by acting as a releasable decoy.
  •  
45.
  •  
46.
  • Lindén, Sara K., 1974, et al. (författare)
  • Mucin dynamics in intestinal bacterial infection.
  • 2008
  • Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 3:12
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Bacterial gastroenteritis causes morbidity and mortality in humans worldwide. Murine Citrobacter rodentium infection is a model for gastroenteritis caused by the human pathogens enteropathogenic Escherichia coli and enterohaemorrhagic E. coli. Mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract. METHODOLOGY/PRINCIPAL FINDINGS: Using Immunohistochemistry, we investigated intestinal expression of mucins (Alcian blue/PAS, Muc1, Muc2, Muc4, Muc5AC, Muc13 and Muc3/17) in healthy and C. rodentium infected mice. The majority of the C. rodentium infected mice developed systemic infection and colitis in the mid and distal colon by day 12. C. rodentium bound to the major secreted mucin, Muc2, in vitro, and high numbers of bacteria were found in secreted MUC2 in infected animals in vivo, indicating that mucins may limit bacterial access to the epithelial surface. In the small intestine, caecum and proximal colon, the mucin expression was similar in infected and non-infected animals. In the distal colonic epithelium, all secreted and cell surface mucins decreased with the exception of the Muc1 cell surface mucin which increased after infection (p<0.05). Similarly, during human infection Salmonella St Paul, Campylobacter jejuni and Clostridium difficile induced MUC1 in the colon. CONCLUSION: Major changes in both the cell-surface and secreted mucins occur in response to intestinal infection.
  •  
47.
  • Lindén, Sara K., 1974, et al. (författare)
  • Role of mucin Lewis status in resistance to Helicobacter pylori infection in pediatric patients.
  • 2010
  • Ingår i: Helicobacter. - : Wiley. - 1523-5378 .- 1083-4389. ; 15:4, s. 251-8
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Helicobacter pylori causes gastritis, peptic ulcer and is a risk factor for adenocarcinoma and lymphoma of the stomach. Gastric mucins, carrying highly diverse carbohydrate structures, present functional binding sites for H. pylori and may play a role in pathogenesis. However, little information is available regarding gastric mucin in children with and without stomach diseases. MATERIALS AND METHODS: Expression of mucins and glycosylation was studied by immunohistochemistry on gastric biopsies from 51 children with and without H. pylori infection and/or peptic ulcer disease. RESULTS: In all children, MUC5AC was present in the surface epithelium and MUC6 in the glands. No MUC6 in the surface epithelium or MUC2 was detected in any section. The Le(b) and Le(a) blood group antigens were present in the surface epithelium of 80% and 29% of children, respectively. H. pylori load was higher in Le(b) negative children than in Le(b) positive individuals (mean +/- SEM 17.8 +/- 3.5 vs 10.8 +/- 1.5; p < 0.05), but there was no correlation between Le(a) or Le(b) status and gastritis, nodularity, and gastric or duodenal ulcer (DU). Expression of sialyl-Le(x) was associated with H. pylori infection, and DU. CONCLUSIONS: Mucin expression and glycosylation is similar in children and adults. However, in contrast to adults, pediatric H. pylori infection is not accompanied by aberrant expression of MUC6 or MUC2. Furthermore, the lower H. pylori density in Le(b) positive children indicates that H. pylori is suppressed in the presence of gastric mucins decorated with Le(b), the binding site of the H. pylori BabA adhesin.
  •  
48.
  • Liu, Cheng, et al. (författare)
  • Gastric de novo Muc13 expression and spasmolytic polypeptide-expressing metaplasia during Helicobacter heilmannii infection.
  • 2014
  • Ingår i: Infection and immunity. - 1098-5522. ; 82:8, s. 3227-39
  • Tidskriftsartikel (refereegranskat)abstract
    • Helicobacter heilmannii is a zoonotic bacterium that has been associated with gastric disease in humans. In this study, the mRNA expression of mucins in the stomach of BALB/c mice was analyzed at several time points during a 1-year infection with this bacterium, during which gastric disease progressed in severity. Markers for acid production by parietal cells and mucous metaplasia were also examined. In the first 9 weeks postinfection, the mRNA expression of Muc6 was clearly upregulated in both the antrum and fundus of the stomach of H. heilmannii-infected mice. Interestingly, Muc13 was upregulated already at 1 day postinfection in the fundus of the stomach. Its expression level remained high in the stomach over the course of the infection. This mucin is, however, not expressed in a healthy stomach, and high expression of this mucin has so far only been described in gastric cancer. In the later stages of infection, mRNA expression of H(+)/K(+)-ATPase α/β and KCNQ1 decreased, whereas the expression of Muc4, Tff2, Dmbt1, and polymeric immunoglobulin receptor (pIgR) increased starting at 16 weeks postinfection onwards, suggesting the existence of spasmolytic polypeptide-expressing metaplasia in the fundus of the stomach. Mucous metaplasia present in the mucosa surrounding low-grade mucosa-associated lymphoid tissue (MALT) lymphoma-like lesions was also histologically confirmed. Our findings indicate that H. heilmannii infection causes severe gastric pathologies and alterations in the expression pattern of gastric mucins, such as Muc6 and Muc13, as well as disrupting gastric homeostasis by inducing the loss of parietal cells, resulting in the development of mucous metaplasia.
  •  
49.
  • Loibman, Stefany Ojaimi, 1988, et al. (författare)
  • Aeromonas salmonicida AI-1 and AI-2 quorum sensing pathways are differentially regulated by rainbow trout mucins and during in vivo colonization
  • 2024
  • Ingår i: FISH & SHELLFISH IMMUNOLOGY. - 1050-4648 .- 1095-9947. ; 153
  • Tidskriftsartikel (refereegranskat)abstract
    • Aeromonas salmonicida is an opportunistic pathogen with relevance for aquaculture. Fish epithelia are covered by a mucus layer, composed mainly by highly glycosylated mucins, which are the first point of contact between fish and pathogens. Quorum sensing (QS), a bacterial communication mechanism through secreted autoinducer signals that governs gene expression, influences bacterial growth and virulence. The main A. salmonicida autoinducers are mediated by the luxS and asaI genes, corresponding to inter- and intraspecies communication, respectively. The aim of this study was to determine the effect of the mucins that pathogens encounter during colonization of the gill and skin on A. salmonicida QS. We found that expression of A. salmonicida asaI, but not luxS, was increased after culture at 20 degrees C compared to 10 degrees C. Rainbow trout gill and skin mucins up-regulated asaI expression 2-fold but down-regulated luxS 10-fold. The downregulation of luxS was reflected by a reduction in autoinducer-2 secretion. Mucins isolated from skin had a stronger inhibitory effect than mucins isolated from gills on both luxS expression and A1-2 secretion, consistent with a higher relative abundance of N-Acetylneuraminic acid on skin mucins than on gill mucins. Reduction of AI-2 production by mucins or luxS-deletion lead to a reduced A. salmonicida auto-aggregation. Furthermore, after colonization of the gill, luxS was down regulated whereas asaI expression was upregulated. Both in vivo and in vitro, the expression of luxS and asaI were thus differentially regulated, frequently in an inverse manner. The strong AI-2 inhibiting effect of the skin mucins is likely part of the mucin-based defense against pathogens.
  •  
50.
  • McGuckin, MA, et al. (författare)
  • Mucin Dynamics and Enteric Pathogens
  • 2011
  • Ingår i: Nature Reviews Microbiology. - : Springer Science and Business Media LLC. - 1740-1526 .- 1740-1534. ; 9:4, s. 265-78
  • Forskningsöversikt (refereegranskat)abstract
    • Abstract: The extracellular secreted mucus and the cell surface glycocalyx prevent infection by the vast numbers of microorganisms that live in the healthy gut. Mucin glycoproteins are the major component of these barriers. In this Review, we describe the components of the secreted and cell surface mucosal barriers and the evidence that they form an effective barricade against potential pathogens. However, successful enteric pathogens have evolved strategies to circumvent these barriers. We discuss the interactions between enteric pathogens and mucins, and the mechanisms that these pathogens use to disrupt and avoid mucosal barriers. In addition, we describe dynamic alterations in the mucin barrier that are driven by host innate and adaptive immune responses to infection.
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