| 1. |
- Althage, Magnus, et al.
(författare)
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Cross-linking of transmembrane helices in proton-translocating nicotinamide nucleotide transhydrogenase from Escherichia coli: implications for the structure and function of the membrane domain.
- 2004
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Ingår i: Biochimica et biophysica acta. - : Elsevier BV. - 0006-3002 .- 0005-2728. ; 1659:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- Proton-pumping nicotinamide nucleotide transhydrogenase from Escherichia coli contains an alpha and a beta subunit of 54 and 49 kDa, respectively, and is made up of three domains. Domain I (dI) and III (dIII) are hydrophilic and contain the NAD(H)- and NADP(H)-binding sites, respectively, whereas the hydrophobic domain II (dII) contains 13 transmembrane alpha-helices and harbours the proton channel. Using a cysteine-free transhydrogenase, the organization of dII and helix-helix distances were investigated by the introduction of one or two cysteines in helix-helix loops on the periplasmic side. Mutants were subsequently cross-linked in the absence and presence of diamide and the bifunctional maleimide cross-linker o-PDM (6 A), and visualized by SDS-PAGE. In the alpha(2)beta(2) tetramer, alphabeta cross-links were obtained with the alphaG476C-betaS2C, alphaG476C-betaT54C and alphaG476C-betaS183C double mutants. Significant alphaalpha cross-links were obtained with the alphaG476C single mutant in the loop connecting helix 3 and 4, whereas betabeta cross-links were obtained with the betaS2C, betaT54C and betaS183C single mutants in the beginning of helix 6, the loop between helix 7 and 8 and the loop connecting helix 11 and 12, respectively. In a model based on 13 mutants, the interface between the alpha and beta subunits in the dimer is lined along an axis formed by helices 3 and 4 from the alpha subunit and helices 6, 7 and 8 from the beta subunit. In addition, helices 2 and 4 in the alpha subunit together with helices 6 and 12 in the beta subunit interact with their counterparts in the alpha(2)beta(2) tetramer. Each beta subunit in the alpha(2)beta(2) tetramer was concluded to contain a proton channel composed of the highly conserved helices 9, 10, 13 and 14.
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| 2. |
- Bhuiyan, Taufiqur Rahman, 1974, et al.
(författare)
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Comparison of mucosal B- and T-cell responses in Helicobacter pylori-infected subjects in a developing and a developed country.
- 2008
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Ingår i: FEMS immunology and medical microbiology. - 0928-8244. ; 54:1, s. 70-9
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori is highly endemic in developing countries, but comparatively little is known about mucosal immune responses to H. pylori in these settings. Therefore, we have compared B- and T-cell responses, with a focus on the gastrointestinal mucosa, in H. pylori-infected adults in a developing (Bangladesh) and a developed (Sweden) country. We found comparable numbers of CD19(+) B cells and CD4 (+)T cells and similar levels of H. pylori-specific IgA antibodies in gastric mucosa from Bangladeshi and Swedish volunteers. However, about threefold higher numbers of CD19(+) B cells and 12-fold increased levels of H. pylori-specific IgA antibodies were found in the duodenum of Bangladeshi subjects. The gastric and duodenal immune responses in Bangladeshi asymptomatic carriers and duodenal ulcer patients were comparable. Bangladeshi subjects had about twofold lower titers of H. pylori-specific IgA and IgG antibodies in the circulation compared with Swedish volunteers. In conclusion, our findings suggest that Bangladeshi individuals have comparable gastric immune responses, but lower systemic antibody responses to H. pylori, compared with Swedish volunteers. Increased inflammation is present in the duodenum of Bangladeshi volunteers, maybe as a result of frequent exposure to enteric infections in these individuals.
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| 3. |
- Enarsson, Karin, 1975, et al.
(författare)
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Function and recruitment of mucosal regulatory T cells in human chronic Helicobacter pylori infection and gastric adenocarcinoma.
- 2006
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Ingår i: Clinical immunology (Orlando, Fla.). - : Elsevier BV. - 1521-6616. ; 121:3, s. 358-68
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Tidskriftsartikel (refereegranskat)abstract
- CD4(+)CD25(high) FOXP3-expressing regulatory T cells (Treg) can suppress immune responses to infections and tumors, thereby promoting microbial persistence and tumor progression. However, little is known about the phenotype and function of human mucosal Treg. Therefore, we analyzed the suppressive activity and homing phenotype of Treg in gastric mucosa of Helicobacter pylori-infected gastric adenocarcinoma patients. We found increased numbers of CD4(+)FOXP3(+) Treg in the tumor compared to tumor-free gastric mucosa. Gastric Treg cells were able to suppress H. pylori-induced T cell proliferation and IFN-gamma production. Furthermore, gastric Treg expressed increased levels of l-selectin and CCR4, compared to non-Treg cells, suggesting that these receptors contribute to Treg recruitment. The presence of functional antigen-specific Treg in H. pylori-infected gastric mucosa supports an important role for these cells in suppression of mucosal effector T cell responses, which probably contribute to bacterial persistence and possibly also to gastric tumor progression.
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| 4. |
- Hanssen, A. M., et al.
(författare)
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Localization of Staphylococcus aureus in tissue from the nasal vestibule in healthy carriers
- 2017
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Colonization of the body is an important step in Staphylococcus aureus infection. S. aureus colonizes skin and mucous membranes in humans and several animal species. One important ecological niche of S. aureus is the anterior nares. More than 60% of the S. aureus in the nose are found in vestibulum nasi. Our aim was to describe the localization of S. aureus in nasal tissue from healthy carriers. Methods: Punch skin biopsies were taken from vestibulum nasi from healthy volunteers (S. aureus carriers and non-/intermittent carriers, n = 39) attending the population-based Tromso 6 study. The tissue samples were processed as frozen sections before immunostaining with a specific S. aureus antibody, and finally evaluated by a confocal laser-scanning microscope. Results: Our results suggest that S. aureus colonize both the upper and lower layers of the epidermis within the nasal epithelium of healthy individuals. The number of S. aureus in epidermis was surprisingly low. Intracellular localization of S. aureus in nasal tissue from healthy individuals was also detected. Conclusions: Knowledge of the exact localization of S. aureus in nasal tissue is important for the understanding of the host responses against S. aureus. Our results may have consequences for the eradication strategy of S. aureus in carriers, and further work can provide us with tools for targeted prevention of S. aureus colonisation and infection.
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| 5. |
- Kassem, Ali, et al.
(författare)
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TLR5, a novel mediator of innate immunity-induced osteoclastogenesis and bone loss
- 2015
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Ingår i: Faseb Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 29:11, s. 4449-4460
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Tidskriftsartikel (refereegranskat)abstract
- Accumulating evidence points to the importance of the innate immune system in inflammation-induced bone loss in infectious and autoimmune diseases. TLRs are well known for being activated by ligands expressed by bacteria, viruses, and fungi. Recent findings indicate that also endogenous ligands in inflammatory processes are important, one being a TLR5 agonist present in synovial fluid from patients with rheumatoid arthritis (RA). We found that activation of TLR5 by its specific ligand, flagellin, caused robust osteoclast formation and bone loss in cultured mouse neonatal parietal bones dependent on increased receptor activator of NF-kappa B ligand (RANKL): osteoprotegerin ratio, with half-maximal stimulation at 0.01 mu g/ml. Flagellin enhanced Rankl mRNA in isolated osteoblasts by a myeloid differentiation primary response gene 88 and NF-kappa B-dependent mechanism. Injection of flagellin locally over skull bones in 5-wk-oldmice resulted in increased mRNA expression of Rankl and osteoclastic genes, robust osteoclast formation, and bone loss. The effects in vitro and in vivo were absent in Tlr5(-/-) mice. These data show that TLR5 is a novel activator of RANKL and osteoclast formation and, therefore, a potential key factor in inflammation-induced bone erosions in diseases like RA, reactive arthritis, and periodontitis. TLR5 might be a promising novel treatment target for prevention of inflammatory bone loss.
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| 6. |
- Kindlund, Bert, 1969, et al.
(författare)
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CD4(+) regulatory T cells in gastric cancer mucosa are proliferating and express high levels of IL-10 but little TGF-β.
- 2017
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Ingår i: Gastric cancer : official journal of the International Gastric Cancer Association and the Japanese Gastric Cancer Association. - : Springer Science and Business Media LLC. - 1436-3291 .- 1436-3305. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- An increase of regulatory T cells, defined as CD25(high)- and/or FOXP3(+)-expressing CD4(+) T cells, within tumors has been reported in several studies. Tregs promote tumor growth by modulating the antitumor immune response, mainly through inhibition of T-cell-mediated tumor cell killing: this has been suggested to be dependent on IL-10 and/or TGF-β. In stomach cancer, the mechanisms behind the accumulation of Tregs in tumor tissue has not been fully elucidated, and neither has Treg gene expression in situ.
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| 7. |
- Kindlund, Bert, 1969, et al.
(författare)
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FOXP3-expressing CD4(+) T-cell numbers increase in areas of duodenal gastric metaplasia and are associated to CD4(+) T-cell aggregates in the duodenum of Helicobacter pylori-infected duodenal ulcer patients.
- 2009
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Ingår i: Helicobacter. - : Wiley. - 1523-5378 .- 1083-4389. ; 14:3, s. 192-201
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We have previously demonstrated that Helicobacter pylori infection is associated with an increased number of CD4(+)CD25(high) regulatory T cells in the gastric and duodenal mucosa. In this study, we determined the number and localization of CD4(+) cells expressing the regulatory T-cell-specific transcription factor FOXP3 in the antrum and duodenum of duodenal ulcer patients, asymptomatic carriers, and uninfected individuals. We also determined gene expression levels of FOXP3 as well as anti- and proinflammatory cytokines before and after H. pylori eradication. METHODS: Cellular FOXP3 expression was studied by immunofluorescence and flow cytometry, and transcription levels of FOXP3, interleukin (IL)-10, transforming growth factor-beta, CD4, and interferon-gamma were analyzed by real-time reverse transcription-polymerase chain reaction. RESULTS: We found an increased (6-fold) frequency of CD4(+)FOXP3(+) T cells in H. pylori-infected gastric mucosa; interestingly 26% of these cells did not co-express CD25. The increase of FOXP3-expressing T cells in the antrum of infected individuals was dependent on the presence of H. pylori, since eradication therapy resulted in 4-fold lower levels of FOXP3 and IL-10 mRNA in the antrum. Furthermore, higher numbers of CD4(+)FOXP3(+) T cells were found in areas of duodenal gastric metaplasia in the duodenum of duodenal ulcer patients compared to duodenal gastric metaplasia of asymptomatic individuals and healthy mucosa in both patient groups. In duodenal ulcer patients, the CD4(+)FOXP3(+) T cells were more highly associated to aggregates in the duodenal mucosa. CONCLUSION: The numbers of CD4(+)FOXP3(+) T cells are increased and localized in CD4(+) T-cell aggregates in areas of duodenal gastric metaplasia in duodenal ulcer patients.
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| 8. |
- Kindlund, Bert, 1969
(författare)
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Regulatory CD4+FOXP3+ T cells in Helicobacter pylori-induced disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Helicobacter pylori colonize the gastric or duodenal mucosa of approximately half of the worlds’ population. Although most individuals are asymptomatic, H. pylori infection cause peptic ulcers or gastric cancer in 10-15 % and 1-2 %, respectively, of the infected individuals. It has previously been suggested by us and others that the life-long infection caused by H. pylori may be due to dysregulation of the immune response and that the host often fails to eradicate the infection due to the presence of regulatory T cells that down-regulate the proper immune response. In this thesis we have further analyzed the suppressive capacity, frequency, location and proliferation of regulatory T cells both locally at the site of infection and systemically in the blood in individuals with duodenal ulcer and gastric cancer. We could show by immunohistochemistry that FOXP3-expressing CD4+ T-cell numbers increase in areas of duodenal gastric metaplasia compared to normal duodenal mucosa and are associated to CD4+ T-cell aggregates in the duodenum of Helicobacter pylori-infected duodenal ulcer patients. The increase of FOXP3-expressing T cells in the antrum of infected individuals was dependent on the presence of Helicobacter pylori, since eradication therapy resulted in 4-fold lower levels of FOXP3 and IL-10 mRNA in the antrum. Higher numbers of CD4+FOXP3+ T cells were found in duodenal ulcer patients than in asymptomatic H. pylori infected individuals. These results show that CD4+FOXP3+ expressing T cells are increased at the site of infection and decrease when the bacteria are eradicated. When analysing patients with gastric cancer we found increased numbers of CD4+FOXP3+ T cells in the tumor compared to tumor-free gastric mucosa. We could determine that gastric CD4+CD25high T cells expressed FOXP3 and were able to suppress H. pylori-induced T-cell proliferation and IFN-γ production. These regulatory T cells (Treg) expressed increased levels of the homing receptor L-selectin and CCR4, which indicated that the increased levels of CD4+FOXP3+ Tregs in tumors are due to active recruitment to the tumor mucosa. Suppressive activites of Tregs have been proposed to be exerted by the anti-inflammatory cytokines IL-10 or TGF-β. To evaluate the immune response in individuals that developed gastric cancer compared to asymptomatic individuals we stimulated T cells from both peripheral blood and gastric mucosa of H. pylori-infected gastric cancer patients with H. pylori antigens. All T cells from gastric cancer patients produced high amounts of IL-10, while the IL-10 production from blood T cells of H. pylori-infected asymptomatic subjects was low. Furthermore, the mRNA levels of IL-10 were increased in the gastric mucosa of GC patients and the frequency of activated CD8+ T cells was markedly reduced compared to asymptomatic individuals. Finally, we analysed CD4+FOXP3+ T cells from gastric cancer patients by flow cytometry. We found that CD4+FOXP3+ T cells from gastric cancer patients have significantly higher levels of proliferation than CD4+FOXP3- T cells within the tumor, and that CD4+FOXP3+ cells within tumors proliferate significantly more than CD4+FOXP3+ cells in tumor free mucosa and in blood. When CD4+ T cells were isolated directly from the tumor and tumor free mucosa and sorted into CD25high and CD25low/- populations we found that CD4+CD25 low/- T cells express higher transcription levels of both IFN-γ and TGF-β compared to CD4+CD25high T cells, but CD4+CD25high have a higher IL-10 / IFN-γ ratio, which indicates a suppressive function. Furthermore, the tumor mucosa had a higher expression of the pro-inflammatory cytokines IFN-γ and IL-8 compared to tumor-free mucosa. In conclusion, we show increased numbers of CD4+FOXP3+ T cells both in the mucosa of duodenal ulcer patients and in gastric tumor tissue. This increase is associated to the presence of H. pylori, local inflammation or cancer, and is mediated by both increased recruitment into the mucosa and increased proliferation of resident FOXP3+ cells. Furthermore, the local CD4+FOXP3+ T cells are associated to IL-10 expression but lack of IFN-γ, while TGF-β is produced to a larger extent by other T cells. We believe that these findings contribute to increased understanding of the immunoregulatory processes related to H. pylori-induced diseases.
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| 9. |
- Lundin, Samuel B, 1970, et al.
(författare)
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The local and systemic T-cell response to Helicobacter pylori in gastric cancer patients is characterised by production of interleukin-10.
- 2007
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Ingår i: Clinical immunology (Orlando, Fla.). - : Elsevier BV. - 1521-6616. ; 125:2, s. 205-13
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori causes a life-long infection that may lead to development of gastric adenocarcinoma (GC) and thereby cause major worldwide health problems. The present study was designed to study whether those that develop GC have an altered immune response to H. pylori compared to individuals that remain asymptomatic. When stimulated with H. pylori antigens, T cells from both peripheral blood and gastric mucosa of H. pylori-infected GC patients produced high amounts of IL-10, while the IL-10 production from blood T cells of H. pylori-infected asymptomatic subjects was low. Furthermore, mRNA levels of IL-10 were increased in the gastric mucosa of GC patients. In addition, the frequency of activated CD8(+) T cells was markedly reduced in stomach mucosa of patients with GC compared to asymptomatic individuals. We propose that the increased production of the suppressive cytokine IL-10 in H. pylori-infected GC patients leads to a diminished cytotoxic anti-tumour T-cell response in the stomach, which may contribute to tumour progression in subjects suffering from GC.
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| 10. |
- Movérare-Skrtic, Sofia, et al.
(författare)
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Osteoblast-derived WNT16 represses osteoclastogenesis and prevents cortical bone fragility fractures.
- 2014
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 20:11, s. 1279-88
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Tidskriftsartikel (refereegranskat)abstract
- The WNT16 locus is a major determinant of cortical bone thickness and nonvertebral fracture risk in humans. The disability, mortality and costs caused by osteoporosis-induced nonvertebral fractures are enormous. We demonstrate here that Wnt16-deficient mice develop spontaneous fractures as a result of low cortical thickness and high cortical porosity. In contrast, trabecular bone volume is not altered in these mice. Mechanistic studies revealed that WNT16 is osteoblast derived and inhibits human and mouse osteoclastogenesis both directly by acting on osteoclast progenitors and indirectly by increasing expression of osteoprotegerin (Opg) in osteoblasts. The signaling pathway activated by WNT16 in osteoclast progenitors is noncanonical, whereas the pathway activated in osteoblasts is both canonical and noncanonical. Conditional Wnt16 inactivation revealed that osteoblast-lineage cells are the principal source of WNT16, and its targeted deletion in osteoblasts increases fracture susceptibility. Thus, osteoblast-derived WNT16 is a previously unreported key regulator of osteoclastogenesis and fracture susceptibility. These findings open new avenues for the specific prevention or treatment of nonvertebral fractures, a substantial unmet medical need.
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