| 1. |
- Hansson, Malin, 1967, et al.
(författare)
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DC-LAMP(+) Dendritic Cells Are Recruited to Gastric Lymphoid Follicles in Helicobacter pylori-Infected Individuals
- 2013
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 81:10, s. 3684-3692
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Tidskriftsartikel (refereegranskat)abstract
- Infection with Helicobacter pylori is associated with development of ulcer disease and gastrointestinal adenocarcinoma. The infection leads to a large infiltration of immune cells and the formation of organized lymphoid follicles in the human gastric mucosa. Still, the immune system fails to eradicate the bacteria, and the substantial regulatory T cell (Treg) response elicited is probably a major factor permitting bacterial persistence. Dendritic cells (DCs) are professional antigen-presenting cells that can activate naive T cells, and maturation of DCs is crucial for the initiation of primary immune responses. The aim of this study was to investigate the presence and localization of mature human DCs in H. pylori-infected gastric mucosa. Gastric antral biopsy specimens were collected from patients with H. pylori-associated gastritis and healthy volunteers, and antrum tissue was collected from patients undergoing gastric resection. Immunohistochemistry and flow cytometry showed that DCs expressing the maturation marker dendritic cell lysosome-associated membrane glycoprotein (DC-LAMP; CD208) are enriched in the H. pylori-infected gastric mucosa and that these DCs are specifically localized within or close to lymphoid follicles. Gastric DC-LAMP-positive (DC-LAMP(+)) DCs express CD11c and high levels of HLA-DR but little CD80, CD83, and CD86. Furthermore, immunofluorescence analyses demonstrated that DC-LAMP(+) DCs are in the same location as FoxP3-positive putative Tregs in the follicles. In conclusion, we show that DC-LAMP(+) DCs with low costimulatory capacity accumulate in the lymphoid follicles in human H. pylori-infected gastric tissue, and our results suggest that Treg-DC interactions may promote chronic infection by rendering gastric DCs tolerogenic.
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| 2. |
- Oertli, Mathias, et al.
(författare)
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DC-derived IL-18 drives Treg differentiation, murine Helicobacter pylori-specific immune tolerance, and asthma protection.
- 2012
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Ingår i: The Journal of clinical investigation. - 1558-8238. ; 122:3, s. 1082-96
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Tidskriftsartikel (refereegranskat)abstract
- Persistent colonization with the gastric bacterial pathogen Helicobacter pylori causes gastritis and predisposes infected individuals to gastric cancer. Conversely, it is also linked to protection from allergic, chronic inflammatory, and autoimmune diseases. We demonstrate here that H. pylori inhibits LPS-induced maturation of DCs and reprograms DCs toward a tolerance-promoting phenotype. Our results showed that DCs exposed to H. pylori in vitro or in vivo failed to induce T cell effector functions. Instead, they efficiently induced expression of the forkhead transcription factor FoxP3, the master regulator of Tregs, in naive T cells. Depletion of DCs in mice infected with H. pylori during the neonatal period was sufficient to break H. pylori-specific tolerance. DC depletion resulted in improved control of the infection but also aggravated T cell-driven immunopathology. Consistent with the mouse data, DCs infiltrating the gastric mucosa of human H. pylori carriers exhibited a semimature DC-SIGN(+)HLA-DR(hi)CD80(lo)CD86(lo) phenotype. Mechanistically, the tolerogenic activity of H. pylori-experienced DCs was shown to require IL-18 in vitro and in vivo; DC-derived IL-18 acted directly on T cells to drive their conversion to Tregs. CD4(+)CD25(+) Tregs from infected wild-type mice but not Il18(-/-) or Il18r1(-/-) mice prevented airway inflammation and hyperresponsiveness in an experimental model of asthma. Taken together, our results indicate that tolerogenic reprogramming of DCs ensures the persistence of H. pylori and protects against allergic asthma in a process that requires IL-18.
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| 3. |
- Flach, Carl-Fredrik, 1977, et al.
(författare)
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Mucosal vaccination increases local chemokine production attracting immune cells to the stomach mucosa of Helicobacter pylori infected mice.
- 2012
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Ingår i: Vaccine. - : Elsevier BV. - 1873-2518 .- 0264-410X. ; 30:9, s. 1636-1643
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Tidskriftsartikel (refereegranskat)abstract
- Background: Vaccination is an attractive approach for the prevention of Helicobacter pylori infection and disease. In a mouse model, infection induces an accumulation of dendritic cells, macrophages, granulocytes, and B- and T cells to the stomach mucosa, which is further heightened when the infection is preceded by a mucosal immunization. We have studied the chemokines and chemokine receptors guiding infection- and vaccination-induced immune cells to the stomach and their relation to protection against H. pylori infection in mice. Materials and methods: C57BL/6 mice were immunized sublingually with H. pylori lysate antigens and cholera toxin adjuvant or left unimmunized, and then challenged with live H. pylori bacteria. Stomach tissue was taken at 3, 7, 14 and 21 days after challenge and bacterial colonization, chemokine and chemokine receptor gene expression, and influx of cells into the stomach mucosa were evaluated. Results: RT-PCR array screening revealed differential expression of a broad range of chemokine and chemokine receptor genes between immunized and unimmunized mice. A significant upregulation of chemokines known to attract, among other cells, eosinophils (CCL8), T cells (CXCL10, CXCL11) and neutrophils (CXCL2, CXCL5) and of their cognate receptors CCR3, CXCR3 and CXCR2, preceded or coincided with vaccine-induced protection, which was first evident 7 days after infection and was then sustained at the later time-points. Consistent with the increase in chemokines and chemokine receptors flow cytometric analysis indicated a sequential accumulation of CD4+ T cells, eosinophils, neutrophils and CD103+ dendritic cells in the gastric lamina propria of immunized mice. Conclusions: This study provides insights into vaccination-induced chemokines that guide the influx of protective immune cells into the stomach of H. pylori infected mice.
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| 4. |
- Quiding-Järbrink, Marianne, 1964, et al.
(författare)
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Enhanced M1 macrophage polarization in human Helicobacter pylori-associated atrophic gastritis and in vaccinated mice
- 2010
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Ingår i: PLOS one. - : Public Library of Science (PLoS). - 1932-6203. ; 5:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Infection with Helicobacter pylori triggers a chronic gastric inflammation that can progress to atrophy and gastric adenocarcinoma. Polarization of macrophages is a characteristic of both cancer and infection, and may promote progression or resolution of disease. However, the role of macrophages and their polarization during H. pylori infection has not been well defined. Methodology/Principal Findings By using a mouse model of infection and gastric biopsies from 29 individuals, we have analyzed macrophage recruitment and polarization during H. pylori infection by flow cytometry and real-time PCR. We found a sequential recruitment of neutrophils, eosinophils and macrophages to the gastric mucosa of infected mice. Gene expression analysis of stomach tissue and sorted macrophages revealed that gastric macrophages were polarized to M1 after H. pylori infection, and this process was substantially accelerated by prior vaccination. Human H. pylori infection was characterized by a mixed M1/M2 polarization of macrophages. However, in H. pylori-associated atrophic gastritis, the expression of inducible nitric oxide synthase was markedly increased compared to uncomplicated gastritis, indicative of an enhanced M1 macrophage polarization in this pre-malignant lesion. Conclusions/Significance These results show that vaccination of mice against H. pylori amplifies M1 polarization of gastric macrophages, and that a similar enhanced M1 polarization is present in human H. pylori-induced atrophic gastritis.
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