| 1. |
- Holmkvist, Petra, et al.
(författare)
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IL-18Rα-deficient CD4+ T cells induce intestinal inflammation in the CD45RBhi transfer model of colitis despite impaired innate responsiveness
- 2016
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980. ; 46:6, s. 1371-1382
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Tidskriftsartikel (refereegranskat)abstract
- IL-18 has been implicated in inflammatory bowel disease (IBD), however its role in the regulation of intestinal CD4+ T-cell function remains unclear. Here we show that murine intestinal CD4+ T cells express high levels of IL-18Rα and provide evidence that IL-18Rα expression is induced on these cells subsequent to their entry into the intestinal mucosa. Using the CD45RBhi T-cell transfer colitis model, we show that IL-18Rα is expressed on IFN-γ+, IL-17+, and IL-17+IFN-γ+ effector CD4+ T cells in the inflamed colonic lamina propria (cLP) and mesenteric lymph node (MLN) and is required for the optimal generation and/or maintenance of IFN-γ-producing cells in the cLP. In the steady state and during colitis, TCR-independent cytokine-induced IFN-γ and IL-17 production by intestinal CD4+ T cells was largely IL-18Rα−dependent. Despite these findings however, IL-18Rα−deficient CD4+ T cells induced comparable intestinal pathology to WT CD4+ T cells. These findings suggest that IL-18-dependent cytokine induced activation of CD4+ T cells is not critical for the development of T-cell-mediated colitis.
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| 2. |
- Jensen, Benjamin A H, et al.
(författare)
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Lysates of Methylococcus capsulatus Bath induce a lean-like microbiota, intestinal FoxP3+RORγt+IL-17+ Tregs and improve metabolism
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between host and gut microbial communities are modulated by diets and play pivotal roles in immunological homeostasis and health. We show that exchanging the protein source in a high fat, high sugar, westernized diet from casein to whole-cell lysates of the non-commensal bacterium Methylococcus capsulatus Bath is sufficient to reverse western diet-induced changes in the gut microbiota to a state resembling that of lean, low fat diet-fed mice, both under mild thermal stress (T22 °C) and at thermoneutrality (T30 °C). Concomitant with microbiota changes, mice fed the Methylococcus-based western diet exhibit improved glucose regulation, reduced body and liver fat, and diminished hepatic immune infiltration. Intake of the Methylococcu-based diet markedly boosts Parabacteroides abundances in a manner depending on adaptive immunity, and upregulates triple positive (Foxp3+RORγt+IL-17+) regulatory T cells in the small and large intestine. Collectively, these data point to the potential for leveraging the use of McB lysates to improve immunometabolic homeostasis.
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| 3. |
- Laursen, Martin F., et al.
(författare)
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Bifidobacterium species associated with breastfeeding produce aromatic lactic acids in the infant gut
- 2021
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 6, s. 1367-1382
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Tidskriftsartikel (refereegranskat)abstract
- Breastfeeding profoundly shapes the infant gut microbiota, which is critical for early life immune development, and the gut microbiota can impact host physiology in various ways, such as through the production of metabolites. However, few breastmilk-dependent microbial metabolites mediating host–microbiota interactions are currently known. Here, we demonstrate that breastmilk-promoted Bifidobacterium species convert aromatic amino acids (tryptophan, phenylalanine and tyrosine) into their respective aromatic lactic acids (indolelactic acid, phenyllactic acid and 4-hydroxyphenyllactic acid) via a previously unrecognized aromatic lactate dehydrogenase (ALDH). The ability of Bifidobacterium species to convert aromatic amino acids to their lactic acid derivatives was confirmed using monocolonized mice. Longitudinal profiling of the faecal microbiota composition and metabolome of Danish infants (n = 25), from birth until 6 months of age, showed that faecal concentrations of aromatic lactic acids are correlated positively with the abundance of human milk oligosaccharide-degrading Bifidobacterium species containing the ALDH, including Bifidobacterium longum, B. breve and B. bifidum. We further demonstrate that faecal concentrations of Bifidobacterium-derived indolelactic acid are associated with the capacity of these samples to activate in vitro the aryl hydrocarbon receptor (AhR), a receptor important for controlling intestinal homoeostasis and immune responses. Finally, we show that indolelactic acid modulates ex vivo immune responses of human CD4+ T cells and monocytes in a dose-dependent manner by acting as an agonist of both the AhR and hydroxycarboxylic acid receptor 3 (HCA3). Our findings reveal that breastmilk-promoted Bifidobacterium species produce aromatic lactic acids in the gut of infants and suggest that these microbial metabolites may impact immune function in early life.
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| 4. |
- Luda, Katarzyna M., et al.
(författare)
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IRF8 Transcription-Factor-Dependent Classical Dendritic Cells Are Essential for Intestinal T Cell Homeostasis
- 2016
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Ingår i: Immunity. - : Elsevier BV. - 1074-7613. ; 44:4, s. 860-874
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Tidskriftsartikel (refereegranskat)abstract
- The role of dendritic cells (DCs) in intestinal immune homeostasis remains incompletely defined. Here we show that mice lacking IRF8 transcription-factor-dependent DCs had reduced numbers of T cells in the small intestine (SI), but not large intestine (LI), including an almost complete absence of SI CD8αβ+ and CD4+CD8αα+ T cells; the latter requiring β8 integrin expression by migratory IRF8 dependent CD103+CD11b- DCs. SI homing receptor induction was impaired during T cell priming in mesenteric lymph nodes (MLN), which correlated with a reduction in aldehyde dehydrogenase activity by SI-derived MLN DCs, and inefficient T cell localization to the SI. These mice also lacked intestinal T helper 1 (Th1) cells, and failed to support Th1 cell differentiation in MLN and mount Th1 cell responses to Trichuris muris infection. Collectively these results highlight multiple non-redundant roles for IRF8 dependent DCs in the maintenance of intestinal T cell homeostasis.
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| 5. |
- Persson, Emma, et al.
(författare)
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IRF4 Transcription-Factor-Dependent CD103(+)CD11b(+) Dendritic Cells Drive Mucosal T Helper 17 Cell Differentiation.
- 2013
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Ingår i: Immunity. - : Elsevier BV. - 1074-7613. ; 38:5, s. 958-969
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Tidskriftsartikel (refereegranskat)abstract
- CD103(+)CD11b(+) dendritic cells (DCs) represent the major migratory DC population within the small intestinal lamina propria (SI-LP), but their in vivo function remains unclear. Here we demonstrate that intestinal CD103(+)CD11b(+) DC survival was dependent on interferon regulatory factor 4 (IRF4). Mice with a DC deletion in Irf4 displayed reduced numbers of intestinal interleukin 17 (IL-17)-secreting helper T 17 (Th17) cells and failed to support Th17 cell differentiation in draining mesenteric lymph nodes (MLN) following immunization. The latter was associated with a selective reduction in CD103(+)CD11b(+) MLN DCs and DC derived IL-6. Immunized Il6(-/-) mice failed to support Th17 cell differentiation in MLN in vivo and CD103(+)CD11b(+) MLN DCs supported IL-6-dependent Th17 cell differentiation in vitro. Together, our results suggest a central role for IRF4-dependent, IL-6 producing CD103(+)CD11b(+) DCs in intestinal Th17 cell differentiation.
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| 6. |
- Pool, Lieneke, et al.
(författare)
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Deletion of IRF4 in Dendritic Cells Leads to Delayed Onset of T Cell-Dependent Colitis
- 2020
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 204:4, s. 1047-1055
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Tidskriftsartikel (refereegranskat)abstract
- Classical dendritic cells (cDC) can be classified into two major subsets: Irf8-dependent cDC1 and Irf4-expressing cDC2. Although these subsets play distinct roles in intestinal immune homeostasis, their functions in T cell-driven colitis remain unknown. To assess the role of IRF4 expression in cDC2 in T cell-driven colitis, CD11c-Cre.Irf4fl/fl and Irf4fl/fl mice were backcrossed onto a Rag-1-/- background and used as recipients of CD45RBhiCD4+ T cells. Colitis score and innate immune cell influx were reduced in Cre+ mice 4 wk posttransfer, and these changes were associated with reduced CD4+ T cell counts in both the mesenteric lymph nodes and colon. By 7 wk, colitis score and colon CD4+ T cell numbers were similar in Cre+ and Cre- mice despite a selective reduction in Th17 cells in the colon of Cre+ mice and a continued reduction in CD4+ T cell numbers in mesenteric lymph nodes. Cotransfer of CD25+CD45RBlo CD4+ T cells prevented CD45RBhiCD4+ T cell-driven colitis in both Cre+ and Cre- recipients, demonstrating that IRF4 expression by cDC is not required for CD4+ regulatory T cell-mediated control of colitis. Collectively these results suggest a role for IRF4 expression in cDC2 in the generation of colitogenic CD4+ T cells, which becomes redundant as colitis progresses.
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| 7. |
- Rivollier, Aymeric, et al.
(författare)
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Physiological Role of TNF in Mucosal Immunology : Regulation of Macrophage/Dendritic Cell Function
- 2015
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Ingår i: Anti-Tumor Necrosis Factor Therapy in Inflammatory Bowel Disease. - : S. Karger AG. - 0302-0665. - 9783318054743 ; 34, s. 9-26, s. 9-26
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Bokkapitel (refereegranskat)abstract
- Intestinal mononuclear phagocytes, comprising macrophages (Mφs) and dendritic cells (DCs), play important roles in the generation and the regulation of immune responses to intestinal antigens, and alterations in the development and/or the function of these cells are thought to contribute to the pathogenesis of inflammatory bowel disease. In this review, we discuss the role of tumor necrosis factor-α (TNF) in regulating multiple aspects of intestinal Mφ and DC physiology, including their differentiation, migration, maturation, survival and effector functions. In inflammatory bowel disease, TNF signaling has been implicated in reprogramming monocyte differentiation from the anti-inflammatory Mφ lineage towards the pro-inflammatory mononuclear phagocyte lineage. These cells become a major source of TNF and, thus, may contribute to the chronic inflammatory process. Finally, we highlight some of the important gaps in our current knowledge regarding the role of TNF in Mφ and DC physiology and suggest important directions for future research in this field.
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| 8. |
- Valatas, V., et al.
(författare)
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Host-dependent control of early regulatory and effector T-cell differentiation underlies the genetic susceptibility of RAG2-deficient mouse strains to transfer colitis
- 2013
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Ingår i: Mucosal Immunology. - : Elsevier BV. - 1933-0219. ; 6:3, s. 601-611
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Tidskriftsartikel (refereegranskat)abstract
- De novo differentiation of CD4(+) Foxp3(+) regulatory T cells (induced (i) Tregs) occurs preferentially in the gut-associated lymphoid tissues (GALT). We addressed the contribution of background genetic factors in affecting the balance of iTreg, T helper type 1 (Th1), and Th17 cell differentiation in GALT in vivo following the transfer of naive CD4(+) CD45RB(high) T cells to strains of RAG2-deficient mice with differential susceptibility to inflammatory colitis. iTregs represented up to 5% of CD4(+) T cells in mesenteric lymph nodes of less-susceptible C57BL/6RAG2(-/-) mice compared with <1% in highly susceptible C57BL/10RAG2(-/-) mice 2 weeks following T-cell transfer before the onset of colitis. Early Treg induction was correlated inversely with effector cell expansion and the severity of colitis development, was controlled primarily by host and not T-cell-dependent factors, and was strongly associated with interleukin-12 (IL-12)/23 production by host CD11c(+) CD103(+) dendritic cells. These data highlight the importance of genetic factors regulating IL-12/23 production in controlling the balance between iTreg differentiation and effector-pathogenic CD4(+) T-cell expansion in lymphopenic mice and indicate a direct role for iTregs in the regulation of colonic inflammation in vivo.
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| 9. |
- Wendland, Kerstin, et al.
(författare)
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Retinoic acid signaling in thymic epithelial cells regulates thymopoiesis
- 2018
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 201:2, s. 524-532
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Tidskriftsartikel (refereegranskat)abstract
- Despite the essential role of thymic epithelial cells (TEC) in T cell development, the signals regulating TEC differentiation and homeostasis remain incompletely understood. In this study, we show a key in vivo role for the vitamin A metabolite, retinoic acid (RA), in TEC homeostasis. In the absence of RA signaling in TEC, cortical TEC (cTEC) and CD80loMHC class IIlo medullary TEC displayed subset-specific alterations in gene expression, which in cTEC included genes involved in epithelial proliferation, development, and differentiation. Mice whose TEC were unable to respond to RA showed increased cTEC proliferation, an accumulation of stem cell Ag-1hi cTEC, and, in early life, a decrease in medullary TEC numbers. These alterations resulted in reduced thymic cellularity in early life, a reduction in CD4 single-positive and CD8 single-positive numbers in both young and adult mice, and enhanced peripheral CD8+ T cell survival upon TCR stimulation. Collectively, our results identify RA as a regulator of TEC homeostasis that is essential for TEC function and normal thymopoiesis.
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