| 1. |
- Abdillahi, Suado M, et al.
(author)
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The Pulmonary Extracellular Matrix Is a Bactericidal Barrier Against Haemophilus influenzae in Chronic Obstructive Pulmonary Disease (COPD) : Implications for an in vivo Innate Host Defense Function of Collagen VI
- 2018
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9
-
Journal article (peer-reviewed)abstract
- Non-typeable Haemophilus influenzae (NTHi) is a Gram-negative human commensal commonly residing in the nasopharynx of preschool children. It occasionally causes upper respiratory tract infection such as acute otitis media, but can also spread to the lower respiratory tract causing bronchitis and pneumonia. There is increasing recognition that NTHi has an important role in chronic lower respiratory tract inflammation, particularly in persistent infection in patients suffering from chronic obstructive pulmonary disease (COPD). Here, we set out to assess the innate protective effects of collagen VI, a ubiquitous extracellular matrix component, against NTHi infection in vivo. In vitro, collagen VI rapidly kills bacteria through pore formation and membrane rupture, followed by exudation of intracellular content. This effect is mediated by specific binding of the von Willebrand A (VWA) domains of collagen VI to the NTHi surface adhesins protein E (PE) and Haemophilus autotransporter protein (Hap). Similar observations were made in vivo specimens from murine airways and COPD patient biopsies. NTHi bacteria adhered to collagen fibrils in the airway mucosa and were rapidly killed by membrane destabilization. The significance in host-pathogen interplay of one of these molecules, PE, was highlighted by the observation that it confers partial protection from bacterial killing. Bacteria lacking PE were more prone to antimicrobial activity than NTHi expressing PE. Altogether the data shed new light on the carefully orchestrated molecular events of the host-pathogen interplay in COPD and emphasize the importance of the extracellular matrix as a novel branch of innate host defense.
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| 2. |
- Agarwal, Vaibhav, et al.
(author)
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An Alternative Role of C1q in Bacterial Infections: Facilitating Streptococcus pneumoniae Adherence and Invasion of Host Cells.
- 2013
-
In: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 191:8, s. 4235-4245
-
Journal article (peer-reviewed)abstract
- Streptococcus pneumoniae (pneumococcus) is a major human pathogen, which evolved numerous successful strategies to colonize the host. In this study, we report a novel mechanism of pneumococcal-host interaction, whereby pneumococci use a host complement protein C1q, primarily involved in the host-defense mechanism, for colonization and subsequent dissemination. Using cell-culture infection assays and confocal microscopy, we observed that pneumococcal surface-bound C1q significantly enhanced pneumococcal adherence to and invasion of host epithelial and endothelial cells. Flow cytometry demonstrated a direct, Ab-independent binding of purified C1q to various clinical isolates of pneumococci. This interaction was seemingly capsule serotype independent and mediated by the bacterial surface-exposed proteins, as pretreatment of pneumococci with pronase E but not sodium periodate significantly reduced C1q binding. Moreover, similar binding was observed using C1 complex as the source of C1q. Furthermore, our data show that C1q bound to the pneumococcal surface through the globular heads and with the host cell-surface receptor(s)/glycosaminoglycans via its N-terminal collagen-like stalk, as the presence of C1q N-terminal fragment and low m.w. heparin but not the C-terminal globular heads blocked C1q-mediated pneumococcal adherence to host cells. Taken together, we demonstrate for the first time, to our knowledge, a unique function of complement protein C1q, as a molecular bridge between pneumococci and the host, which promotes bacterial cellular adherence and invasion. Nevertheless, in some conditions, this mechanism could be also beneficial for the host as it may result in uptake and clearance of the bacteria.
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| 3. |
- Agarwal, Vaibhav, et al.
(author)
-
Binding of Streptococcus pneumoniae endopeptidase O (PepO) to complement component C1q modulates the complement attack and promotes host cell adherence.
- 2014
-
In: Journal of Biological Chemistry. - 1083-351X. ; 289:22, s. 15833-15844
-
Journal article (peer-reviewed)abstract
- The Gram-positive species Streptococcus pneumoniae is a human pathogen causing severe local and life-threatening invasive diseases associated with high mortality rates and death. We demonstrated recently that pneumococcal endopeptidase O (PepO) is an ubiquitously expressed, multifunctional plasminogen and fibronectin binding protein facilitating host cell invasion and evasion of innate immunity. In this study we found that PepO interacts directly with the complement C1q protein, thereby attenuating the classical complement pathway and facilitating pneumococcal complement escape. PepO binds both free C1q and C1 complex in a dose-dependent manner based on ionic interactions. Our results indicate that recombinant PepO specifically inhibits the classical pathway of complement activation in both hemolytic and complement deposition assays. This inhibition is due to direct interaction of PepO with C1q, leading to a strong activation of the classical complement pathway and results in consumption of complement components. In addition, PepO binds the classical complement pathway inhibitor C4BP, thereby regulating downstream complement activation. Importantly, pneumococcal surface-exposed PepO-C1q interaction mediates bacterial adherence to host epithelial cells. Taken together, PepO facilitates C1q-mediated bacterial adherence, while its localized release consumes complement as a result of its activation following binding of C1q, thus representing an additional mechanism of human complement escape by this versatile pathogen.
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| 4. |
- Agarwal, Vaibhav, et al.
(author)
-
Enolase of Streptococcus pneumoniae Binds Human Complement Inhibitor C4b-Binding Protein and Contributes to Complement Evasion.
- 2012
-
In: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 189:7, s. 3575-3584
-
Journal article (peer-reviewed)abstract
- Streptococcus pneumoniae (pneumococcus) is a pathogen that causes severe local and life-threatening invasive diseases, which are associated with high mortality rates. Pneumococci have evolved several strategies to evade the host immune system, including complement to disseminate and to survive in various host niches. Thus, pneumococci bind complement inhibitors such as C4b-binding protein (C4BP) and factor H via pneumococcal surface protein C, thereby inhibiting the classical and alternative complement pathways. In this study, we identified the pneumococcal glycolytic enzyme enolase, a nonclassical cell surface and plasminogen-binding protein, as an additional pneumococcal C4BP-binding protein. Furthermore, we demonstrated that human, but not mouse, C4BP bound pneumococci. Recombinant enolase bound in a dose-dependent manner C4BP purified from plasma, and the interaction was reduced by increasing ionic strength. Enolase recruited C4BP and plasminogen, but not factor H, from human serum. Moreover, C4BP and plasminogen bound to different domains of enolase as they did not compete for the interaction with enolase. In direct binding assays with recombinant C4BP mutants lacking individual domains, two binding sites for enolase were identified on the complement control protein (CCP) domain 1/CCP2 and CCP8 of the C4BP α-chains. C4BP bound to the enolase retained its cofactor activity as determined by C4b degradation. Furthermore, in the presence of exogenously added enolase, an increased C4BP binding to and subsequently decreased C3b deposition on pneumococci was observed. Taken together, pneumococci specifically interact with human C4BP via enolase, which represents an additional mechanism of human complement control by this versatile pathogen.
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| 5. |
- Agarwal, Vaibhav, et al.
(author)
-
Streptococcus pneumoniae endopeptidase O (PepO): a multifunctional plasminogen and fibronectin binding protein, facilitating evasion of innate immunity and invasion of host cells.
- 2013
-
In: Journal of Biological Chemistry. - 1083-351X. ; 288:10, s. 6849-6863
-
Journal article (peer-reviewed)abstract
- Streptococcus pneumoniae infections remain a major cause of morbidity and mortality worldwide. Therefore a detailed understanding and characterization of the mechanism of host cell colonization and dissemination is critical in order to gain control over this versatile pathogen. Here we identified a novel 72 kDa pneumococcal protein endopeptidase O (PepO), as a plasminogen and fibronectin binding protein. Using a collection of clinical isolates, representing different serotypes, we found PepO to be ubiquitously present both at the gene and at the protein level. In addition, PepO protein was secreted in a growth-phase dependent manner to the culture supernatants of the pneumococcal isolates. Recombinant PepO bound human plasminogen and fibronectin in a dose-dependent manner and plasminogen did not compete with fibronectin for binding PepO. PepO bound plasminogen via lysine residues and the interaction was influenced by ionic strength. Moreover, upon activation of PepO bound plasminogen by urokinase-type plasminogen activator, generated plasmin cleaved complement protein C3b thus assisting in complement control. Furthermore, direct binding assays demonstrated the interaction of PepO with epithelial and endothelial cells that in turn blocked pneumococcal adherence. Moreover, a pepO-mutant strain showed impaired adherence to and invasion of host cells compared to their isogenic wild-type strains. Taken together, the results demonstrated that PepO is ubiquitously expressed plasminogen and fibronectin binding protein, which plays role in pneumococcal invasion of host cells and aids in immune evasion.
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| 6. |
- Ahl, Jonas, et al.
(author)
-
High incidence of septic shock caused by Streptococcus pneumoniae serotype 3-a retrospective epidemiological study
- 2013
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In: BMC Infectious Diseases. - : Springer Science and Business Media LLC. - 1471-2334. ; 13
-
Journal article (peer-reviewed)abstract
- Background: More than 90 immunologically distinct serotypes of Streptococcus pneumoniae exist, and it is not fully elucidated whether the serotype is a risk factor for severity of invasive pneumococcal disease (IPD). Our hypothesis is that serotypes differ in their capacity to cause septic shock. Methods: We performed a retrospective study in Southern Sweden based upon 513 patients with IPD in the pre-vaccine era 2006-2008. The serotype, co-morbidity, and sepsis severity were determined. Serotypes were compared to serotype 14 as a reference and grouped according to their invasive potential, that is, high (serogroups 1, 5 and 7), intermediate (serogroups 4, 9, 14 and 18) and, finally, low invasive potential (serogroups 3, 6, 8, 15, 19, 23 and 33). Results: Patients with S. pneumoniae serotype 3 had significantly more often septic shock (25%, odds ratio (OR) 6.33 [95% confidence interval (CI) 1.59-25.29]), higher mortality (30%, OR 2.86 [CI 1.02-8.00]), and more often co-morbidities (83%, OR 3.82 [CI 1.39-10.54]) when compared to serotype 14. A significant difference in age and co-morbidities (p= 0.001) was found when patient data were pooled according to the invasive potential of the infecting pneumococci. The median age and percentage of patients with underlying co-morbidities were 72 years and 79%, respectively, for serogroups associated with low invasiveness, 68 years and 61%, respectively, for serogroups with intermediate invasiveness, and, finally, 62 years and 48%, respectively, for serogroups with high invasiveness. No difference in sepsis severity was found between the three groups. Conclusions: S. pneumoniae serotype 3 more often caused septic shock compared to serotype 14. Our results support the hypothesis that serotypes with high invasiveness mainly cause IPD in younger patients with less co-morbidities. In contrast, serogroups with low and intermediate invasive potential mostly cause IPD in the elderly with defined co-morbidities, and thus can be considered as opportunistic.
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| 7. |
- Ahl, Jonas, et al.
(author)
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Prevalence of penicillin-non-susceptible Streptococcus pneumoniae in children in day-care centres subjected to an intervention to prevent dispersion.
- 2015
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In: Infectious Diseases. - : Informa UK Limited. - 2374-4243 .- 2374-4235. ; 47:5, s. 338-344
-
Journal article (peer-reviewed)abstract
- Background: The aim of this study was to evaluate the day-care interventions implemented in southern Sweden to restrict the dispersion of penicillin-non-susceptible pneumococci with a minimum inhibitory concentration of penicillin G of at least 0.5 mg/l (PNSP0.5). Methods: A retrospective epidemiological study was performed and data from 109 day-care centre interventions from 2000 to 2010 were analysed, including screening results from 7157 individuals. Results: It was found that 42% of the children were carriers of pneumococci and 5% of the screened children were PNSP0.5 carriers. Very few personnel were PNSP0.5 carriers and they were carriers for only a short time. Significantly more contact cases with the same serogroup as the index case were found in the first screening and in the same department as the index case, but a substantial number of contact cases were found in adjacent departments. Conclusions: Screening of personnel is not worth the effort. Based on our results, procedures to restrict dispersion of PNSP0.5 in day-care centres could be improved. To find the majority of contact cases with PNSP0.5 an early screening including adjacent departments seems to be the best approach.
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| 8. |
- Ahl, Jonas, et al.
(author)
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Risk Factors for Pneumococcal Carriage in Day Care Centers: A Retrospective Study During a 10-year Period.
- 2014
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In: Pediatric Infectious Disease Journal. - 1532-0987. ; 33:5, s. 536-538
-
Journal article (peer-reviewed)abstract
- In this retrospective epidemiologic study, we present pneumococcal carriage data from 109 Swedish day care centers over a period of 10 years. Aspects of season, age, personnel and group size were studied. We found a significant seasonal variation in pneumococcal carriage. Group size was a significant risk factor for pneumococcal carriage. Pneumococcal carriage was 4.5 % in personnel.
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| 9. |
- Ahrén, Irini Lazou, et al.
(author)
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The importance of a β-glucan receptor in the nonopsonic entry of nontypeable Haemophilus influenzae into human monocytic and epithelial cells
- 2001
-
In: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 184:2, s. 150-158
-
Journal article (peer-reviewed)abstract
- Previous reports showed that nontypeable Haemophilus influenzae (NTHi) reside in macrophage-like cells in human adenoid tissue. This study investigated the ability of nonopsonized NTHi and encapsulated H. influenzae type b (Hib) to enter human monocytic and epithelial cells. The number of intracellular bacteria was determined by a viability assay and flow cytometry. To characterize the mechanisms responsible for the internalization of NTHi, different inhibitors of surface molecules, receptor turnover, and the cytoskeleton were used. Hib were found in monocytic cells at very low numbers (<100 bacteria/2 × 105 cells). In contrast, a great variation in intracellular numbers was detected between the different NTHi isolates (range, 0.0007%-0.28% of the inoculum for monocytes and 0.053%-3.5% for epithelial cells). NTHi entered human monocytic and epithelial cells via a receptor-mediated endocytosis involving mainly a β-glucan receptor that could be blocked by laminarin.
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| 10. |
- Ahren, IL, et al.
(author)
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Nontypeable Haemophilus influenzae activates human eosinophils through beta-glucan receptors
- 2003
-
In: American Journal of Respiratory Cell and Molecular Biology. - 1535-4989. ; 29:5, s. 598-605
-
Journal article (peer-reviewed)abstract
- Eosinophils are a characteristic component of the inflammatory response seen in several diseases, including allergic asthma and chronic obstructive pulmonary disease. After activation, eosinophil-derived products may exert proinflammatory effects and cause considerable tissue damage. In the present study, we investigated innate interactions between the respiratory tract pathogen nontypeable Haemophilus influenzae (NTHi) and human eosinophils. Bacterial binding to eosinophils was dependent on (1-3)-beta-D-glucan receptors, as deduced from blocking experiments using the soluble glucan derivatives laminarin and scleroglucan. In addition, expression of the beta-glucan receptor dectin-1 was shown in eosinophils by reverse transcriptase-polymerase chain reaction. Activation of the beta-glucan receptors by bacteria elicited a time- and dose-dependent respiratory burst in eosinophils. NTHi caused increased expression of the proinflammatory chemokine interleukin-8 as measured by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay. Incubation of eosinophils in the presence of NTHi for 4.5 h revealed upregulation of 245 different genes as detected by microarray. Signal transduction-related transcripts were most strongly upregulated, followed by cytokine mRNAs. Our findings suggest that NTHi can induce an innate inflammatory response in eosinophils that is mainly mediated via beta-glucan receptors. This points to possible pathophysiologic mechanisms involving innate recognition of NTHi by eosinophils during infection of the airways, thus promoting inflammation in chronic pulmonary disease.
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| 11. |
- Alamiri, Feiruz, et al.
(author)
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A role of epithelial cells and virulence factors in biofilm formation by Streptococcus pyogenes in vitro
- 2020
-
In: Infection and Immunity. - 1098-5522. ; 88:10
-
Journal article (peer-reviewed)abstract
- Biofilm formation by Streptococcus pyogenes (GAS) in model systems mimicking the respiratory tract is poorly documented. Most studies have been conducted on abiotic surfaces, which poorly represent human tissues. We have previously shown that GAS forms mature and antibiotic-resistant biofilms on physiologically relevant epithelial cells. However, the role of the substratum, extracellular matrix (ECM) components, or GAS virulence factors for biofilm formation and structure is unclear. In this study, biofilm formation was measured on respiratory epithelial cells and keratinocytes by determining biomass and antibiotic resistance, and biofilm morphology was visualized using scanning electron microscopy. All GAS isolates tested formed biofilms that had similar, albeit not identical, biomass and antibiotic resistance for both cell types. Interestingly, functionally mature biofilms formed more rapidly on keratinocytes but were structurally denser and coated with more ECM on respiratory epithelial cells. The ECM was crucial for biofilm integrity, as protein- and DNA-degrading enzymes induced bacterial release from biofilms. Abiotic surfaces supported biofilm formation, but these biofilms were structurally less dense and organized. No major role of M protein, capsule, or Streptolysin O was observed in biofilm formation on epithelial cells, although some morphological differences were detected. NAD-glycohydrolase was required for optimal biofilm formation, whereas Streptolysin S or cysteine protease SpeB impaired this process. Finally, no correlation was found between cell adherence or auto-aggregation and GAS biofilm formation. Combined, these results provide a better understanding of the role of biofilm formation in GAS pathogenesis and can potentially provide novel targets for future treatments against GAS infections.
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| 12. |
- Alamiri, Feiruz, et al.
(author)
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HAMLET, a protein complex from human milk has bactericidal activity and enhances the activity of antibiotics against pathogenic Streptococci
- 2019
-
In: Antimicrobial Agents and Chemotherapy. - 1098-6596. ; 63:12
-
Journal article (peer-reviewed)abstract
- HAMLET is a protein-lipid complex derived from human milk that was first described for its tumoricidal activity. Later studies showed that HAMLET also has direct bactericidal activity against select species of bacteria, with highest activity against Streptococcus pneumoniae Additionally, HAMLET in combination with various antimicrobial agents can make a broader range of antibiotic-resistant bacterial species sensitive to antibiotics. Here, we show that HAMLET has direct antibacterial activity not only against pneumococci, but also against Streptococcus pyogenes (GAS) and Streptococcus agalactiae (GBS). Analogous to pneumococci, HAMLET-treatment of GAS and GBS resulted in depolarization of the bacterial membrane followed by membrane permeabilization and death that could be inhibited by calcium and sodium transport inhibitors. Treatment of clinical antibiotic-resistant isolates of S. pneumoniae, GAS, and GBS with sublethal concentrations of HAMLET in combination with antibiotics decreased the minimal inhibitory concentrations of the respective antibiotic into the sensitive range. This effect could also be blocked by ion transport inhibitors, suggesting that HAMLET's bactericidal and combination treatment effects used similar mechanisms. Finally, we show that HAMLET potentiated the effects of erythromycin against erythromycin-resistant bacteria more effectively than it potentiated killing by penicillin G of bacteria resistant to penicillin G. These results show for the first time that HAMLET effectively kills three different species of pathogenic Streptococci using similar mechanisms and also potentiate the activity of macrolides and lincosamides more effectively than combination treatment with beta-lactams. These findings suggest a potential therapeutic role for HAMLET in repurposing antibiotics currently causing treatment failures in patients.
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| 13. |
- Andersson, Madelen, et al.
(author)
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Outbreak of a beta-lactam resistant non-typeable Haemophilus influenzae sequence type 14 associated with severe clinical outcomes
- 2015
-
In: BMC Infectious Diseases. - : BioMed Central. - 1471-2334. ; 15
-
Journal article (peer-reviewed)abstract
- Background: During October 2011 several residents and staff members at a long-term care facility (LTCF) for elderly fell ill with respiratory symptoms. Several of the residents required hospitalization and one died. Non-typeable Haemophilus influenzae (NTHi) was identified as the causative pathogen. Methods: A descriptive analysis of the outbreak and countermeasures was performed. For each identified bacterial isolate implied in the outbreak, standard laboratory resistance testing was performed, as well as molecular typing and phylogenetic analysis. Results: The identified H. influenzae was beta-lactamase negative but had strikingly high MIC-values of ampicillin, cefuroxime and cefotaxime. All isolates displayed the same mutation in the ftsI gene encoding penicillin-binding protein (PBP) 3, and all but one were identified as sequence type 14 by Multilocus Sequence Typing (MLST). In total 15 individuals in connection to the LTCF; 8 residents, 6 staff members and one partner to a staff member were colonized with the strain. Conclusion: This report illustrates the existence of non-typeable H. influenzae with high virulence, and furthermore emphasizes the importance of continuous surveillance of possible outbreaks in health care facilities and prompt measures when outbreaks occur.
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| 14. |
- Appelqvist, Emma, et al.
(author)
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Parental views and the key role of nurses for high vaccine acceptance in Sweden – a focus group study
- 2023
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In: BMC Public Health. - 1471-2458. ; 23:1
-
Journal article (peer-reviewed)abstract
- Background: In Sweden, vaccine uptake is exceptionally high due to an efficient child immunization program. More than 97% of Swedish children were vaccinated at child health care centers (CHCs) according to the schedule at 2 years of age in 2021. From the age of 6 years, vaccinations are given within the school health care. Maintaining high vaccination coverage over time is one of the central motives to explore and understand drivers for vaccine acceptance. The current study aimed to assess parental vaccine acceptance concerning the national immunization program and explore factors contributing to the high vaccine acceptance in Sweden. Methods: Parents of children aged 1–2 years and 8–12 years were recruited through purposive sampling and asked to participate in focus groups held in three cities in Sweden, in February and March 2019. In total, 47 parents participated in two focus groups per city, one session for parents of younger (1–2 years) and older (8–12 years) children respectively. The focus group discussions were analyzed using qualitative content analysis. Results: Parents of children aged 1–2 years expressed the themes; strong compliance to and protection of the value of vaccinations; parents feel safe with an attentive relationship with their nurse; the spectrum of communication needs is essential to meet. For parents to children aged 8–12 years, the themes expressed were; vaccinate to do good for the individual and society; a foundation of trust is built at CHCs for decisions later on; decisions for vaccination become more complex as children get older; communication changes as children get older and need to be explicit and tailored to the situation. Conclusion: Both individual and societal perspectives were shown to influence the vaccination decision for childhood immunizations, as manifested in parental reflections and experiences. As nurses have a key role, it is important to provide them with continued support and tools to facilitate their support for parents in making informed decisions. Continuous work for supporting driving factors for vaccination over time is needed to maintain high vaccine acceptance in Sweden.
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| 15. |
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| 16. |
- Aung, Kyaw Min, et al.
(author)
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Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U
- 2016
-
In: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 8:3, s. 269-283
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Journal article (peer-reviewed)abstract
- Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.
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| 17. |
- Barfod, Anders, et al.
(author)
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In Vitro Selection of RNA Aptamers Directed Against Protein E: A Haemophilus influenzae Adhesin. : a Haemophilus influenzae adhesin
- 2014
-
In: Molecular Biotechnology. - : Springer Science and Business Media LLC. - 1559-0305 .- 1073-6085. ; 56:8, s. 714-725
-
Journal article (peer-reviewed)abstract
- Protein E (PE) of Haemophilus influenzae is a highly conserved ubiquitous surface protein involved in adhesion to and activation of epithelial cells. The host proteins-vitronectin, laminin, and plasminogen are major targets for PE-dependent interactions with the host. To identify novel inhibitory molecules of PE, we used an in vitro selection method based on systematic evolution of ligands by exponential enrichment known as SELEX in order to select 2'F-modified RNA aptamers that specifically bind to PE. Fourteen selection cycles were performed with decreasing concentrations of PE. Sequencing of clones from the 14th selection round revealed the presence of semiconserved sequence motifs in loop regions of the RNA aptamers. Among these, three aptamers showed the highest affinity to PE in electrophoretic mobility shift assays and in dot blots. These three aptamers also inhibited the interaction of PE with vitronectin as revealed by ELISA. Moreover, pre-treatment of H. influenzae with the aptamers significantly inhibited binding of vitronectin to the bacterial surface. Biacore experiments indicated that one of the aptamers had a higher binding affinity for PE as compared to the other aptamers. Our results show that it is possible to select RNA inhibitors against bacterial adhesins using SELEX in order to inhibit interactions with target proteins.
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| 18. |
- Barthel, Diana, et al.
(author)
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Haemophilus influenzae Uses the Surface Protein E To Acquire Human Plasminogen and To Evade Innate Immunity
- 2012
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In: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 188:1, s. 379-385
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Journal article (other academic/artistic)abstract
- Pathogenic microbes acquire the human plasma protein plasminogen to their surface. In this article, we characterize binding of this important coagulation regulator to the respiratory pathogen nontypeable Haemophilus influenzae and identify the Haemophilus surface protein E (PE) as a new plasminogen-binding protein. Plasminogen binds dose dependently to intact bacteria and to purified PE. The plasminogen-PE interaction is mediated by lysine residues and is also affected by ionic strength. The H. influenzae PE knockout strain (nontypeable H. influenzae 3655 Delta pe) bound plasminogen with similar to 65% lower intensity as compared with the wild-type, PE-expressing strain. In addition, PE expressed ectopically on the surface of Escherichia coli also bound plasminogen. Plasminogen, either attached to intact H. influenzae or bound to PE, was accessible for urokinase plasminogen activator. The converted active plasmin cleaved the synthetic substrate S-2251, and the natural substrates fibrinogen and C3b. Using synthetic peptides that cover the complete sequence of the PE protein, the major plasminogen-binding region was localized to a linear 28-aa-long N-terminal peptide, which represents aa 41-68. PE binds plasminogen and also vitronectin, and the two human plasma proteins compete for PE binding. Thus, PE is a major plasminogen-binding protein of the Gram-negative bacterium H. influenzae, and when converted to plasmin, PE-bound plasmin aids in immune evasion and contributes to bacterial virulence. The Journal of Immunology, 2012, 188: 379-385.
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| 19. |
- Bernhard, Sara, et al.
(author)
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The outer membrane protein OlpA contributes to Moraxella catarrhalis serum resistance via interaction with factor H and the alternative pathway.
- 2014
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In: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 210:8, s. 1306-1310
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Journal article (peer-reviewed)abstract
- Factor H is an important complement regulator of the alternative pathway commonly recruited by pathogens for increased survival in the human host. The respiratory pathogen Moraxella catarrhalis that resides in the mucosa is highly serum resistant and causes otitis media in children and respiratory tract infections in individuals with underlying diseases. In this study, we show that M. catarrhalis binds factor H via the outer membrane protein OlpA. M. catarrhalis serum resistance was dramatically decreased in the absence of either OlpA or factor H, demonstrating that this inhibition of the alternative pathway significantly contributes to the virulence of M. catarrhalis.
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| 20. |
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| 21. |
- Bettoni, Serena, et al.
(author)
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C4BP-IgM protein as a therapeutic approach to treat Neisseria gonorrhoeae infections
- 2019
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In: JCI Insight. - : American Society for Clinical Investigation (ASCI). - 2379-3708. ; 4:23
-
Journal article (peer-reviewed)abstract
- Gonorrhea is a sexually transmitted infection with 87 million new cases per year globally. Increasing antibiotic resistance has severely limited treatment options. A mechanism that Neisseria gonorrhoeae uses to evade complement attack is binding of the complement inhibitor C4b-binding protein (C4BP). We screened 107 porin B1a (PorB1a) and 83 PorB1b clinical isolates randomly selected from a Swedish strain collection over the last 10 years and noted that 96/107 (89.7%) PorB1a and 16/83 (19.3%) PorB1b bound C4BP; C4BP binding substantially correlated with the ability to evade complement-dependent killing (r = 0.78). We designed 2 chimeric proteins that fused C4BP domains to the backbone of IgG or IgM (C4BP-IgG; C4BP-IgM) with the aim of enhancing complement activation and killing of gonococci. Both proteins bound gonococci (KD C4BP-IgM = 2.4 nM; KD C4BP-IgG 980.7 nM), but only hexameric C4BP-IgM efficiently outcompeted heptameric C4BP from the bacterial surface, resulting in enhanced complement deposition and bacterial killing. Furthermore, C4BP-IgM substantially attenuated the duration and burden of colonization of 2 C4BP-binding gonococcal isolates but not a non-C4BP-binding strain in a mouse vaginal colonization model using human factor H/C4BP-transgenic mice. Our preclinical data present C4BP-IgM as an adjunct to conventional antimicrobials for the treatment of gonorrhea.
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| 22. |
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| 23. |
- Blom, Anna, et al.
(author)
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Complement evasion strategies of pathogens-Acquisition of inhibitors and beyond.
- 2009
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In: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 46, s. 2808-2817
-
Journal article (peer-reviewed)abstract
- Activation of the complement system and resulting opsonisation with C3b are key events of the innate immune defense against infections. However, a wide variety of bacterial pathogens subvert complement attack by binding host complement inhibitors such as C4b-binding protein, factor H and vitronectin, which results in diminished opsonophagocytosis and killing of bacteria by lysis. Another widely used strategy is production of proteases, which can effectively degrade crucial complement components. Furthermore, bacterial pathogens such as Moraxella catarrhalis and Staphylococcus aureus capture and incapacitate the key complement component C3. The current review describes examples of these three strategies. Targeting binding sites for complement inhibitors on bacterial surfaces and complement-degrading proteases with vaccine-induced antibodies may be used to enhance a common vaccine design strategy that depends on the generation of complement-dependent bactericidal and opsonophagocytic antibody activities.
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| 24. |
- Blom, Anna, et al.
(author)
-
Streptococcus pneumoniae phosphoglycerate kinase is a novel complement inhibitor affecting the membrane attack complex formation.
- 2014
-
In: Journal of Biological Chemistry. - 1083-351X. ; 289:47
-
Journal article (peer-reviewed)abstract
- The Gram-positive bacterium Streptococcus pneumoniae is a major human pathogen that causes infections ranging from acute otitis media to life-threatening invasive disease. Pneumococci have evolved several strategies to circumvent the host immune response, in particular the complement attack. The pneumococcal glycolytic enzyme phosphoglycerate kinase (PGK) is both secreted and bound to the bacterial surface and simultaneously binds plasminogen and its activator tPA. In the present study, we demonstrate that PGK has an additional role in modulating the complement attack. PGK interacted with the membrane attack complex (MAC) components C5, C7 and C9, thereby blocking the assembly and membrane insertion of MAC resulting in significant inhibition of the hemolytic activity of human serum. Recombinant PGK interacted in a dose-dependent manner with these terminal pathway proteins, and the interactions were ionic in nature. In addition, PGK inhibited C9 polymerization both in the fluid phase and on the surface of sheep erythrocytes. Interestingly, PGK bound several MAC proteins simultaneously. While C5 and C7 had partially overlapping binding sites on PGK, C9 did not compete with either one for PGK binding. Moreover, PGK significantly inhibited MAC deposition via both the classical and alternative pathway at the pneumococcal surface. Additionally, upon activation plasmin(ogen) bound to PGK cleaved the central complement protein C3b thereby further modifying the complement attack. In conclusion, our data demonstrate for the first time, to our knowledge, a novel pneumococcal inhibitor of the terminal complement cascade aiding complement evasion by this important pathogen.
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| 25. |
- Bredberg, Anders, et al.
(author)
-
4-quinolone antibiotics : Positive genotoxic screening tests despite an apparent lack of mutation induction
- 1989
-
In: Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis. - : Elsevier BV. - 1879-2871 .- 0027-5107. ; 211:1, s. 171-180
-
Journal article (peer-reviewed)abstract
- The effects of different 4-quinolone antibiotic derivatives (4-Qs) in a number of short-term tests commonly employed for the evaluation of genetic toxicity were studied. Incorporation of [3H]thymidine into mitogen-stimulated peripheral blood lymphocytes was strongly enhanced at a low concentration (1.56 μg/ml) for most of the tested 4-Qs, whereas DNA strand breakage in lymphoblastoid cells was evident only for ciprofloxacin (10 μg/ml and upwards), ofloxacin (80 μg/ml) and norfloxacin (160 μg/ml). Ciphrofloxacin induced a significant amount of unscheduled DNA synthesis, but was found to be negative in a shuttle vector plasmid mutation test. Ciprofloxacin (80 μg/ml) did not inhibit enzymes involved in the early steps of pyrimidine biosynthesis. Cell growth was slightly depressed at a concentration of 20 μg/ml, becoming marked at 80 μg/ml. In conculsion, this study seeks to contribute to an improved evaluation of genotoxic screening test data, by focuding attention on the conflicting effects imposed by the 4-Qs on a battery of such tests.
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| 26. |
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| 27. |
- Bråbäck, Martin, et al.
(author)
-
Susceptibilities of Mycobacterium marinum to Gatifloxacin, Gemifloxacin, Levofloxacin, Linezolid, Moxifloxacin, Telithromycin, and Quinupristin-Dalfopristin (Synercid) Compared to Its Susceptibilities to Reference Macrolides and Quinolones.
- 2002
-
In: Antimicrobial Agents and Chemotherapy. - 1098-6596. ; 46:4, s. 1114-1116
-
Journal article (peer-reviewed)abstract
- The susceptibility pattern of Mycobacterium marinum was determined. Quinupristin-dalfopristin and telithromycin were less active than clarithromycin. Linezolid showed good antimicrobial activity at clinically achievable concentrations. Gatifloxacin, levofloxacin, and moxifloxacin displayed activities similar to those of ciprofloxacin. Gemifloxacin was less active. The Etest method showed variable agreement with the reference method.
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| 28. |
- Byström, Emma, et al.
(author)
-
Confidence in the National Immunization Program among parents in Sweden 2016 – A cross-sectional survey
- 2020
-
In: Vaccine. - : Elsevier BV. - 0264-410X. ; 38:22, s. 3909-3917
-
Journal article (peer-reviewed)abstract
- Background: Vaccination coverage for infant vaccinations in the Swedish National Immunization Program (NIP) has been high for more than a decade, with approximately 97% of 2-year-old children fully immunized. Vaccination coverage against Human Papilloma Virus (HPV) has been around 80% since introduction for girls in 2012. This indicates high parental confidence in the NIP, but as seen in other European countries rapid shifts in confidence may occur. This study examined vaccine confidence and attitudes towards vaccinations among parents in the Swedish population. Methods: A web-based survey was sent to 1046 parents with children aged 0–15 years, in a panel administrated by The Public Health Agency of Sweden. The survey included questions on vaccination awareness, safety and information channels. The response rate was 87%. Data were weighted to adjust for non-responders and for representativeness of the Swedish population. Results: Parents were categorized as acceptors (79%), questioning acceptors (19%) or selective refusers (2%). When excluding responses for HPV vaccination, the proportion of acceptors increased to 91%. The main reasons for questioning or refusing a vaccine were worry over adverse events, negative or lack of information. Along a spectrum of beliefs, acceptors and questioning acceptors were more similar compared to selective refusers. Nurses at child health clinics constituted the most used vaccination information source for acceptors, whereas selective refusers to a greater extent searched information online and in social media. Conclusions: The study demonstrates that parents in Sweden have confidence in and are positive towards vaccinations given within the NIP. One in five parents question vaccines, particularly regarding the HPV vaccine, but still concur to the NIP. Information on vaccines online and at vaccination appointments, including vaccine safety, is important for maintaining confidence in vaccination. Conducting recurring studies is valuable for monitoring vaccine confidence and changes in attitudes towards vaccination.
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| 29. |
- Che, Karlhans F., et al.
(author)
-
Complex Involvement of Interleukin-26 in Bacterial Lung Infection
- 2021
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 12, s. 1-18
-
Journal article (peer-reviewed)abstract
- Pneumonia is a global cause of mortality, and this provides a strong incentive to improve the mechanistic understanding of innate immune responses in the lungs. Here, we characterized the involvement of the cytokine interleukin (IL)-26 in bacterial lung infection. We observed markedly increased concentrations of IL-26 in lower airway samples from patients with bacterial pneumonia and these correlated with blood neutrophil concentrations. Moreover, pathogen-associated molecular patterns (PAMPs) from both Gram-negative and -positive bacteria increased extracellular IL-26 concentrations in conditioned media from human models of alveolar epithelial cells, macrophages, and neutrophils in vitro. Stimulation with IL-26 inhibited the inherent release of neutrophil elastase and myeloperoxidase in unexposed neutrophils. This stimulation also inhibited the expression of activity makers in neutrophils exposed to Klebsiella pneumoniae. In addition, priming of human lung tissue ex vivo with exogenous IL-26 potentiated the endotoxin-induced increase in mRNA for other cytokines involved in the innate immune response, including the master Th17-regulator IL-23 and the archetype inhibitory cytokine IL-10. Finally, neutralization of endogenous IL-26 clearly increased the growth of Klebsiella pneumoniae in the macrophage culture. These findings suggest that IL-26 is involved in bacterial lung infection in a complex manner, by modulating critical aspects of innate immune responses locally and systemically in a seemingly purposeful manner and by contributing to the killing of bacteria in a way that resembles an antimicrobial peptide. Thus, IL-26 displays both diagnostic and therapeutic potential in pneumonia and deserves to be further evaluated in these respects.
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| 30. |
- Chen, Daxin, et al.
(author)
-
Regulated inhibition of coagulation by porcine endothelial cells expressing P-selectin-tagged hirudin and tissue factor pathway inhibitor fusion proteins
- 1999
-
In: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337. ; 68:6, s. 832-839
-
Journal article (peer-reviewed)abstract
- Background. Thrombotic vascular occlusion resulting in infarction occurs during hyperacute rejection of allografts transplanted into sensitized patients and remains a major problem in experimental xenotransplantation. A similar process is also found in disorders of diverse etiology including atherosclerosis, vasculitis, and disseminated intravascular coagulation. Methods. We have previously constructed two membrane-tethered anticoagulant fusion proteins based on human tissue factor pathway inhibitor and the leech anticoagulant hirudin and demonstrated their functional efficacy in vitro. These constructs have now been modified by the addition of a P-selectin sequence to the cytoplasmic tail to localize them in Weibel-palade bodies. They have been transfected into Weibel-palade body-positive endothelial cells isolated from the inferior vena cava of normal pigs. Results. In resting endothelial cells, fusion protein expression colocalized with P-selectin and was confined to Weibel-palade bodies. These cells had a procoagulant phenotype in recalcified human plasma. However, after activation with phorbol ester the anticoagulant proteins were rapidly relocated to the cell surface where they specifically inhibited the clotting of human plasma. Conclusions. Novel anticoagulant molecules may prove useful therapeutic agents for gene therapy in thrombotic disease and postangioplasty or for transgenic expression in animals whose organs may be used for clinical xenotransplantation. Expression in vascular endothelial cells may be regulated by inclusion of P-selectin cytoplasmic sequence, to restrict cell surface expression to activated endothelium.
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| 31. |
- Chen, Kang, et al.
(author)
-
Immunoglobulin D enhances immune surveillance by activating antimicrobial, proinflammatory and B cell-stimulating programs in basophils
- 2009
-
In: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 10:8, s. 121-889
-
Journal article (peer-reviewed)abstract
- Immunoglobulin D (IgD) is an enigmatic antibody isotype that mature B cells express together with IgM through alternative RNA splicing. Here we report active T cell-dependent and T cell-independent IgM-to-IgD class switching in B cells of the human upper respiratory mucosa. This process required activation-induced cytidine deaminase (AID) and generated local and circulating IgD-producing plasmablasts reactive to respiratory bacteria. Circulating IgD bound to basophils through a calcium-mobilizing receptor that induced antimicrobial, opsonizing, inflammatory and B cell-stimulating factors, including cathelicidin, interleukin 1 (IL-1), IL-4 and B cell-activating factor (BAFF), after IgD crosslinking. By showing dysregulation of IgD class-switched B cells and 'IgD-armed' basophils in autoinflammatory syndromes with periodic fever, our data indicate that IgD orchestrates an ancestral surveillance system at the interface between immunity and inflammation.
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| 32. |
- Colineau, Lucie, et al.
(author)
-
Interaction of Streptococcus pyogenes with extracellular matrix components resulting in immunomodulation and bacterial eradication
- 2020
-
In: Matrix Biology Plus. - : Elsevier BV. - 2590-0285. ; 6-7
-
Journal article (peer-reviewed)abstract
- Streptococcus pyogenes is a major human pathogen that causes a variety of diseases ranging from mild skin and throat infections to fatal septicemia. In severe invasive infections, S. pyogenes encounters and interacts with components of the extracellular matrix (ECM), including small leucine rich-proteoglycans (SLRPs). In this study, we report a novel antimicrobial role played by SLRPs biglycan, decorin, fibromodulin and osteoadherin, specifically in promoting the eradication of S. pyogenes in a human sepsis model of infection. SLRPs can be released from the ECM and de novo synthesized by a number of cell types. We reveal that infection of human monocytes by S. pyogenes induces the expression of decorin. Furthermore, we show that the majority of genetically distinct and clinically relevant S. pyogenes isolates interact with SLRPs resulting in decreased survival in blood killing assays. Biglycan and decorin induce TLR2 and TLR4 signaling cascades resulting in secretion of proinflammatory and chemotactic molecules and recruitment of professional phagocytes. Surprisingly, SLRP-mediated elimination of S. pyogenes occurs independently of TLR activation. Our results indicate that SLRPs act in concert with human serum, enhancing deposition of complement activation fragments and the classical activator C1q on the bacterial surface, facilitating efficient microbial eradication. Addition of the complement C3 inhibitor compstatin significantly reverses SLRP-induced blood killing, confirming active complement as a key mediator in SLRP-mediated bacterial destruction. Taken together our results add to the functional repertoire of SLRPs, expanding to encompass their role in controlling bacterial infection.
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| 33. |
- Corbascio, Matthias, et al.
(author)
-
CTLA4Ig combined with anti-LFA-1 prolongs cardiac allograft survival indefinitely.
- 2002
-
In: Transplant Immunology. - 1878-5492. ; 10:1, s. 55-61
-
Journal article (peer-reviewed)abstract
- CTLA4Ig and anti-LFA-1 are members of a new generation of immunomodulatory drugs which inhibit important signaling pathways in T cell activation. Both substances target molecules which have pivitol functions in the activation of CD4+ and CD8+ T cells and have been theorized to have an interdependent relationship. These drugs have been used independently in various treatment regimens and have shown great promise in prolonging the survival of allografts. In order to test whether these substances have synergistic or potentiating effects when combined, we performed mixed lymphocyte reactions, skin transplantation and vascularised heterotopic heart transplantation in the Balb/c (H-2(d)) to C3H/HeJ (H-2(k)) strain combination. When anti-LFA-1 and CTLA4Ig were combined at low doses, there was a substantial inhibition of lymphocyte proliferation. When each drug was used as a mono-therapy in skin graft recipients, there was no significant effect on median graft survival (anti-LFA-1, 15 days; CTLA4Ig, 16 days) when compared to untreated controls (13 days), whereas a combination of anti-LFA-1 and CTLA4Ig extended graft survival significantly to 32 days. Untreated vascularised heart grafts rejected at a median of 8 days, CTLA4Ig-treated mice rejected at a median time of 79 days and anti-LFA-1-treated mice rejected at 43 days (n = 9). When CTLA4Ig and anti-LFA-1 were combined, all animals had functioning heart grafts at 100 days after transplantation. Histological analysis of combined-therapy hearts showed no signs or only minor changes associated with chronic rejection. In conclusion, these results indicate a synergistic effect of combining anti-LFA-1 with CTLA4Ig in inhibiting lymphocyte proliferation and prolonging the survival of fully MHC-mismatched allografts.
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| 34. |
- de Vries, Stefan P W, et al.
(author)
-
Genome analysis of Moraxella catarrhalis strain RH4, a Human Respiratory Tract Pathogen.
- 2010
-
In: Journal of Bacteriology. - 0021-9193. ; 192:14, s. 3574-3583
-
Journal article (peer-reviewed)abstract
- Moraxella catarrhalis is an emerging human-restricted respiratory tract pathogen that is a common cause of childhood otitis media and exacerbations of chronic obstructive pulmonary disease in adults. Here, we report the first completely assembled and annotated genome sequence of an isolate of M. catarrhalis: strain RH4, originally isolated from blood of an infected patient. The RH4 genome consists of 1,863,286 nucleotides harboring 1,886 protein-encoding genes. Comparison of the RH4 genome to the ATCC 43617 contigs demonstrated that the gene content of both strains is highly conserved. In silico phylogenetic analyses based on both 16S rRNA and multilocus sequence typing revealed that RH4 belongs to the seroresistant lineage. We were able to identify close to the entire repertoire of known M. catarrhalis virulence factors, and mapped the members of the biosynthetic pathways for lipooligosaccharide, peptidoglycan, and type IV pili. A reconstruction of the central metabolic pathways suggests that RH4 relies on fatty acid and acetate metabolism, as the genes encoding the enzymes required for the glyoxylate pathway, tricarboxylic acid cycle, gluconeogenic pathway, non-oxidative branch of the pentose phosphate pathway, beta-oxidation pathway of fatty acids, and acetate metabolism were present. Moreover, pathways important for survival under in vivo challenging conditions such as iron-acquisition pathways, nitrogen metabolism, and oxidative stress responses were identified. Finally, we showed by microarray expression profiling that approximately 88% of the predicted coding sequences are transcribed under in vitro conditions. Overall, these results provide a foundation for future research into the mechanisms of M. catarrhalis pathogenesis and vaccine development.
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| 35. |
- Deknuydt, Florence, et al.
(author)
-
Diversion of the host humoral response: a novel virulence mechanism of Haemophilus influenzae mediated via outer membrane vesicles.
- 2014
-
In: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 95:6, s. 983-991
-
Journal article (peer-reviewed)abstract
- The respiratory tract pathogen Haemophilus influenzae frequently causes infections in humans. In parallel with all Gram-negative bacteria, H. influenzae has the capacity to release OMV. The production of these nanoparticles is an intriguing and partly unexplored phenomenon in pathogenesis. Here, we investigated how purified human peripheral blood B lymphocytes respond to OMV derived from unencapsulated, i.e., NTHi and the nonpathogenic Haemophilus parainfluenzae. We found that H. influenzae OMV directly interacted with the IgD BCR, as revealed by anti-IgD pAb and flow cytometry. Importantly, H. influenzae OMV-induced cellular activation via IgD BCR cross-linking and TLR9 resulted in a significant proliferative response. OMV isolated from the related species H. parainfluenzae did not, however, interact with B cells excluding that the effect by H. influenzae OMV was linked to common membrane components, such as the LOS. We also observed an up-regulation of the cell surface molecules CD69 and CD86, and an increased IgM and IgG secretion by B cells incubated with H. influenzae OMV. The Igs produced did not recognize H. influenzae, suggesting a polyclonal B cell activation. Interestingly, the density of the cell surface receptor TACI was increased in the presence of OMV that sensitized further the B cells to BAFF, resulting in an enhanced IgG class-switch. In conclusion, the ability of NTHi OMV to activate B cells in a T cell-independent manner may divert the adaptive humoral immune response that consequently promotes bacterial survival within the human host.
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| 36. |
- Dieudonné-Vatran, Antoine, et al.
(author)
-
Clinical isolates of Streptococcus pneumoniae bind the complement inhibitor C4b-binding protein in a PspC allele-dependent fashion.
- 2009
-
In: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:12, s. 7865-7877
-
Journal article (peer-reviewed)abstract
- The complement system constitutes an important component of the innate immune system. To colonize their host and/or to cause disease, many pathogens have evolved strategies to avoid complement-mediated bacterial lysis and opsonophagocytosis. In this study, using a collection of 55 clinical isolates of Streptococcus pneumoniae, we demonstrate for the first time that pneumococci bind the complement inhibitor C4b-binding protein (C4BP). C4BP binding seems to be restricted to certain serotypes such as serotype 4, 6B, 7F, and 14, of which the strains of serotype 14 are the strongest binders. We show that bacteria-bound C4BP retains its functional activity and down-regulates the activation of the classical pathway. Thus, this major respiratory pathogen may escape immune recognition and eradication by the complement system. Furthermore, we show that C4BP binding varies between strains but is dependent on the expression of pneumococcal surface protein C, PspC of group 4. The study of the distribution of group 4 pspC locus shows that most of high-binder serotype 14 isolates harbor an allelic variant of group 4 pspC. Using PspC-negative mutant strains, we identified a new allelic variant of PspC (PspC4.4) as a major ligand for C4BP, revealing a new function for this important pneumococcal virulence factor. Thus pneumococci exploit host C4BP for complement evasion in a PspC allele-dependent manner.
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| 37. |
- Duell, Ben, et al.
(author)
-
Host–pathogen interactions of nontypeable Haemophilus influenzae : from commensal to pathogen
- 2016
-
In: FEBS Letters. - : Wiley. - 0014-5793. ; 590:21, s. 3840-3853
-
Research review (peer-reviewed)abstract
- Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis, acute otitis media in preschool children, exacerbations in patients suffering from chronic obstructive pulmonary disease, as well as conjunctivitis and bacteremia. Since the introduction of a vaccine against H. influenzae serotype b in the 1990s, the burden of H. influenzae-related infections has been increasingly dominated by NTHi. Understanding the ability of NTHi to cause infection is currently an expanding area of study. NTHi is able to exert differential binding to the host tissue through the use of a broad range of adhesins. NTHi survival in the host is multifaceted, that is, using virulence factors involved in complement resistance, biofilm, modified immunoglobulin responses, and, finally, formation and utilization of host proteins as a secondary strategy of increasing the adhesive ability.
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| 38. |
- Filipe, Matuba, et al.
(author)
-
Fluoroquinolone-resistant Alcaligenes faecalis related to chronic suppurative otitis media, Angola
- 2017
-
In: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 23:10, s. 1740-1742
-
Journal article (peer-reviewed)abstract
- We found that 20 (10.6%) of 188 patients with chronic suppurative otitis media in Angola were co-colonized with fluoroquinolone-resistant Alcaligenes faecalis, commonly found in birds. A likely explanation for our findings was the use of bird feces by residents as a traditional remedy to prevent ear secretions caused by primary ear infection.
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| 39. |
- Filipe, Matuba, et al.
(author)
-
Suppurative otitis media in Angola : clinical and demographic features
- 2020
-
In: Tropical Medicine & International Health. - : Wiley. - 1360-2276 .- 1365-3156. ; 25:10, s. 1283-1290
-
Journal article (peer-reviewed)abstract
- Objective: To describe the demographics and clinical findings in patients with otorrhoea in Angola. Methods: A total of 411 patients with otorrhoea presenting in the ear, nose and throat clinic in Luanda and healthcare centres in other Angolan provinces underwent interview and clinical examination. We describe the demographics and clinical characteristics of the patients. Results: The majority (64%) of patients were children <15 years (age ranged from 1 month to 77 years; median age 10.9 years) while 31% were children <5 years. In 83% of the patients, otorrhoea had lasted >14 days at the time of the examination indicating chronic suppurative otitis media (CSOM), which was confirmed with otoscopy in 72% of patients. Acute otitis media occurred in 16% of patients and was more common in children than in adults (22% vs. 10%; P = 0.007). Median duration of otorrhoea was >12 months. Earache (67%), fever (20%), dizziness (17%), nausea and/or vomiting (6%) were the main symptoms. Adult patients reported noticing hearing impairment (HI) more often than the parents of child patients (72% vs. 50%; P < 0.0001). Reported HI correlated with otorrhoea duration (P < 0.0001), presence of earache, dizziness, and measles or meningitis in history. The level of education in the family did not correlate with symptom duration. Conclusions: Otorrhoea is mainly due to CSOM and affects patients long-term in Angola. Otorrhoea duration is the strongest predictor of HI. Education on OM and its treatment is needed to prevent HI.
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| 40. |
- Fish, Abigail I., et al.
(author)
-
The Rickettsia conorii Adr1 interacts with the c-terminus of human vitronectin in a salt-sensitive manner
- 2017
-
In: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 7
-
Journal article (peer-reviewed)abstract
- Spotted fever group (SFG) Rickettsia species are inoculated into the mammalian bloodstream by hematophagous arthropods. Once in the bloodstream and during dissemination, the survival of these pathogens is dependent upon the ability of these bacteria to evade serum-borne host defenses until a proper cellular host is reached. Rickettsia conorii expresses an outer membrane protein, Adr1, which binds the complement inhibitory protein vitronectin to promote resistance to the anti-bacterial effects of the terminal complement complex. Adr1 is predicted to consist of 8 transmembrane beta sheets that form a membrane-spanning barrel with 4 peptide loops exposed to the extracellular environment. We previously demonstrated that Adr1 derivatives containing either loop 3 or 4 are sufficient to bind Vn and mediate resistance to serum killing when expressed at the outer-membrane of E. coli. By expressing R. conorii Adr1 on the surface of non-pathogenic E. coli, we demonstrate that the interaction between Adr1 and vitronectin is salt-sensitive and cannot be interrupted by addition of heparin. Additionally, we utilized vitroenctin-derived peptides to map the minimal Adr1/vitronectin interaction to the C-terminal region of vitronectin. Furthermore, we demonstrate that specific charged amino acid residues located within loops 3 and 4 of Adr1 are critical for mediating resistance to complement-mediated killing. Interestingly, Adr1 mutants that were no longer sufficient to mediate resistance to serum killing still retained the ability to bind to Vn, suggesting that Adr1-Vn interactions responsible for resistance to serum killing are more complex than originally hypothesized. In summary, elucidation of the mechanisms governing Adr1-Vn binding will be useful to specifically target this protein-protein interaction for therapeutic intervention.
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| 41. |
- Fleury, Christophe, et al.
(author)
-
Identification of a Haemophilus influenzae Factor H-Binding Lipoprotein Involved in Serum Resistance.
- 2014
-
In: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 192:12, s. 5913-5923
-
Journal article (peer-reviewed)abstract
- Haemophilus influenzae is a Gram-negative human pathogen that resides in the upper respiratory tract. Encapsulated H. influenzae type b (Hib) and type f (Hif) are the most common serotypes associated with invasive disease. H. influenzae displays various strategies to circumvent the host innate immune response, including the bactericidal effect of the complement system. In this study, we identified an H. influenzae lipoprotein having the ability to bind factor H (FH), the major regulator of the alternative pathway of complement activation. This protein, named protein H (PH), was surface exposed and was found in all clinical Hib and Hif isolates tested. Deletion of the gene encoding for PH (lph) in Hib and Hif significantly reduced the interaction between bacteria and FH. When Hib and Hif PH variants were separately expressed in nontypeable (unencapsulated) H. influenzae, which did not bind FH, an increased FH affinity was observed. We recombinantly expressed the two PH variants in Escherichia coli, and despite sharing only 56% identical amino acids, both FH-binding Haemophilus proteins similarly interacted with the complement regulator FH short consensus repeats 7 and 18-20. Importantly, Hib and Hif resistance against the bactericidal effect of human serum was significantly reduced when bacterial mutants devoid of PH were tested. In conclusion, we have characterized a hitherto unknown bacterial protein that is crucial for mediating an interaction between the human pathogen H. influenzae and FH. This novel interaction is important for H. influenzae resistance against complement activation and will consequently promote bacterial pathogenesis.
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| 42. |
- Fleury, Christophe, et al.
(author)
-
Prevalence, distribution and transfer of small β-lactamase-containing plasmids in Swedish Haemophilus influenzae.
- 2014
-
In: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 1460-2091 .- 0305-7453. ; 69:5, s. 1238-1242
-
Journal article (peer-reviewed)abstract
- The β-lactamase genes of Haemophilus influenzae are commonly positioned on large integrative and conjugative elements, but a group of blaTEM-carrying small plasmids (4000-6000 bp) with a common structural backbone have recently been characterized. In this study we investigated the epidemiological significance and potential for transfer of this group of small plasmids.
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| 43. |
|
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| 44. |
- Forsgren, Arne, et al.
(author)
-
Isolation and characterization of a novel IgD-binding protein from Moraxella catarrhalis
- 2001
-
In: Journal of Immunology. - 1550-6606. ; 167:4, s. 2112-2120
-
Journal article (peer-reviewed)abstract
- A novel surface protein of the bacterial species Moraxella catarrhalis that displays a high affinity for IgD (MID) was solubilized in Empigen and isolated by ion exchange chromatography and gel filtration. The apparent molecular mass of monomeric MID was estimated to approximately 200 kDa by SDS-PAGE. The mid gene was cloned and expressed in Escherichia coli. The complete mid nucleotide gene sequence was determined, and the deduced amino acid sequence consists of 2123 residues. The sequence of MID has no similarity to other Ig-binding proteins and differs from all previously described outer membrane proteins of M. catarrhalis. MID was found to exhibit unique Ig-binding properties. Thus, in ELISA, dot blots, and Western blots, MID bound two purified IgD myeloma proteins, four IgD myeloma sera, and finally one IgD standard serum. No binding of MID was detected to IgG, IgM, IgA, or IgE myeloma proteins. MID also bound to the surface-expressed B cell receptor IgD, but not to other membrane molecules on human PBLs. This novel Ig-binding reagent promises to be of theoretical and practical interest in immunological research.
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| 45. |
- Forsgren, Arne, et al.
(author)
-
New Quinolones : In Vitro Effects as a Potential Source of Clinical Toxicity
- 1989
-
In: Reviews of Infectious Diseases. - 0162-0886. ; 11, s. 1382-1389
-
Journal article (peer-reviewed)abstract
- 4-Quinolones affect mammalian cellular functions in vitro in several ways. High concentrations inhibit DNA replication, but individual genes are perhaps sensitive to lower concentrations of drug. Inhibition of cell proliferation differs widely among 4-quinolones. Ciprofloxacin and norfloxacin are the most antiproliferative, inhibiting cell growth by -30% at 20 mg/L. Genotoxicity tests with 4-quinolones are probably “false-positive” as a result of increased [3H]thymidine uptake that is not related to DNA damage. Ciprofloxacin at ≥ 10 mg/L causes significant strand breaks in DNA, which seemingly are quickly repaired and do not cause mutations or cancer. Production of immunoglobulin is inhibited by ciprofloxacin at a concentration of 5 mg/L, but production of the growth factor interleukin 2 (IL-2) is increased by 4-quinolones at the same concentration and is hyperinduced at higher concentrations. Thus the effects are very contradictory. Increased production of IL-2 may contribute to central nervous system adverse effects. 4-Quinolones in combination with theophylline or antiinflammatory drugs may inhibit γ-aminobutyric acid receptor binding and thereby have adverse effects on the central nervous system. Some 4-quinolones induce crystalluria, which may be nephropathic.
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| 46. |
- Forsgren, Arne, et al.
(author)
-
Protein D of Haemophilus influenzae: a protective nontypeable H. influenzae antigen and a carrier for pneumococcal conjugate vaccines.
- 2008
-
In: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1537-6591 .- 1058-4838. ; 46:5, s. 726-731
-
Research review (peer-reviewed)abstract
- Protein D (PD) is a highly conserved 42 kDa surface lipoprotein found in all Haemophilus influenzae, including nontypeable (NT) H. influenzae. PD is involved in the pathogenesis of respiratory tract infections, in the context of which it has been shown to impair ciliary function in a human nasopharyngeal tissue culture model and to augment the capacity to cause otitis media in rats. A likely mechanism indicating that PD is a virulence factor is its glycerophosphodiesterase activity, which leads to the release of phosphorylcholine from host epithelial cells. PD has been demonstrated to be a promising vaccine candidate against experimental NT H. influenzae infection. Rats vaccinated with PD cleared NT H. influenzae better after middle ear and pulmonary bacterial challenge, and chinchillas vaccinated with PD showed significant protection against NT H. influenzae-dependent acute otitis media. In a clinical trial involving children, PD was used as an antigenically active carrier protein in an 11-valent pneumococcal conjugate investigational vaccine; significant protection was achieved against acute otitis media not only caused by pneumococci but also caused by NT H. influenzae. This may have great clinical implications, because PD is the first NT H. influenzae antigen that has induced protective responses in humans.
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| 47. |
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| 48. |
- Gjörloff Wingren, Anette, et al.
(author)
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The novel IgD binding protein from Moraxella catarrhalis induces human B lymphocyte activation and Ig secretion in the presence of Th2 cytokines.
- 2002
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In: Journal of Immunology. - 1550-6606. ; 168:11, s. 5582-5588
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Journal article (peer-reviewed)abstract
- Moraxella IgD binding protein (MID) is a novel bacterial outer membrane protein with IgD-binding properties. MID was purified from the respiratory pathogen Moraxella catarrhalis and is here shown to have B cell stimulatory properties. Purified MID in the range of 0.01-0.1 microg/ml was optimal to induce a proliferative response in human PBL. MID coupled to Sepharose and formalin-fixed M. catarrhalis preparations induced similar proliferative responses in PBL cultures. MID or MID-Sepharose stimulated purified human peripheral B cells as measured by proliferation. In contrast, MID or MID-Sepharose did not activate T cells. Preincubation of purified B cells with anti-IgD Abs inhibited MID-Sepharose-induced B cell proliferation. The addition of IL-4 specifically induced IL-6 production in MID-Sepharose-activated B cells. IgM secretion was detected in B cell cultures stimulated with MID or MID-Sepharose and IL-2 for 10 days. Secretion of IgG and IgA was efficiently induced in cultures from purified B cells stimulated with the combination of MID or MID-Sepharose and IL-4, IL-10, and soluble CD40 ligand, suggesting that Th2-derived cytokines were required for optimal plasma cell generation. Taken together, MID has properties that make it an important tool to study IgD-targeted activation of B cells.
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| 49. |
- Gutbier, Birgitt, et al.
(author)
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Moraxella catarrhalis induces an immune response in the murine lung which is independent of human CEACAM5 expression and long-term smoke exposure.
- 2015
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In: American Journal of Physiology: Lung Cellular and Molecular Physiology. - : American Physiological Society. - 1522-1504 .- 1040-0605. ; 309:3, s. 250-261
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Journal article (peer-reviewed)abstract
- In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared to wild type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5- expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.
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| 50. |
- Hadzic, Radinka, et al.
(author)
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alpha1-Antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release.
- 2006
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In: Immunology Letters. - : Elsevier BV. - 0165-2478 .- 1879-0542. ; 102:2, s. 141-147
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Journal article (peer-reviewed)abstract
- alpha 1-Antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 mu g/ml MID induces B cell proliferation and stimulates IL-6 release (p < 0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p < 0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymefized (9.9-fold, p < 0.001) as compared to native AAT (2.8-fold, p < 0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2 h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.
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