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- Kumawat, Ashok Kumar, 1982-
(författare)
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Adaptive immune response in the intestinal mucosa of microscopic colitis patients
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microscopic colitis (MC) is a chronic diarrhoeal disease of unknown aetiology, comprising collagenous colitis (CC) and lymphocytic colitis (LC). The nature of the adaptive local immune responses in the mucosa of MC patients is however far from elucidated. The present study investigates phenotypic and functional characteristics of the adaptive local immune responses in the colonic mucosa of these patients.Our immunohistochemistry and flow cytometry studies (Paper I & II) demonstrated increased frequencies of CD8+ T cells in the colonic epithelium and lamina propria of both LC and CC patients compared to controls, whereas the frequencies of CD4+ T cells were unaltered or reduced. Our flow cytometry data revealed increased local activation of both CD4+ and CD8+ T cells in the lamina propria as well as the intraepithelial compartment of CC and LC patients compared to controls, demonstrated as increased proportions of these cells expressing the active/memory marker CD45RO and the proliferation marker Ki67.Analysis of recent thymic emigrants by measuring T cell receptor excision circle (TREC) levels in the colonic mucosa of CC and LC patients revealed reduced TRECs levels in these patients compared to controls (Paper III). These results suggests that the observed increased numbers of T cells in the mucosa of CC and LC patients is due to the expansion of local resident T cells rather than direct recruitment of recent thymic emigrants to the mucosa.Molecular analysis of T helper (Th) cell and cytotoxic T lymphocyte (Tc) mucosal cytokines at messenger and protein levels in the colonic biopsies from CC and LC patients demonstrated a mixed Th17/Tc17 and Th1/Tc1 mucosal cytokine profile and revealed significant differences in the mucosal cytokine levels in CC and LC patients compared to controls (Paper IV).Finally, we have set up an in vitro model to investigate how the colonic milieu affects the activation and differentiation of T lymphocytes (Paper V). Our preliminary data indicate increased production of both pro inflammatory and antiinflammatory cytokines by peripheral blood T cells in the presence of soluble factors from the inflamed colonic mucosa of CC patients compared to controls.
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| 2. |
- Günaltay, Sezin, 1986-
(författare)
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Dysregulated mucosal immune responses in microscopic colitis patients
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microscopic colitis (MC), comprising collagenous colitis (CC) and lymphocytic colitis (LC) is a common cause of chronic watery diarrhea. The diagnosis relies on typical histopathological changes observed upon microscopic examination. The studies in this thesis investigated innate and adaptive immune responses in the colonic mucosa of MC patients, also comparing patients with active disease (CC and LC) and histopathologically in remission (CC/LC-HR). We first analyzed expression of interleukin-1/Toll-like receptor (IL-1/TLR) signaling regulators in MC patients (Paper I). Our results showed enhanced IRAK-M, microRNA-146a, -155 and -21 expressions, whereas IL-37 gene expression was reduced in CC and LC patients as compared to non-inflamed controls. These results suggest different pathophysiological mechanisms in MC patients. The mixed inflammatory cell infiltrations seen in the lamina propria of MC patients might be a result of dysregulated expression of chemotactic mediators. In Paper II, we showed that MC patients display mainly an increased expression of chemokines and chemokine receptors in active disease as compared to noninflamed controls. In Paper III, we examined if the decreased IL-37 expression seen in Paper I could mediate the upregulation of chemokines seen in Paper II. We showed that a relatively small reduction in the ability of epithelial cells to produce IL-37 results in mainly increased chemokine expressions in a pattern similar to the findings in Paper II. In order to understand the nature of infiltrating T cells commonly observed in MC patients, we analyzed the T cell receptor (TCR) β chains in colonic biopsies of MC patients (Paper IV). Our results showed significant differences in TCRβ repertoire, which suggests selectively expanded T cell clones in active MC and histopathologically in remission patients. Altogether, these results i) increase the knowledge of MC pathogenesis by showing changes in TLR signaling regulators, enhanced chemokine and their receptor expressions involved in a mixed immune cell infiltrations and selectively expanded T cell clones in CC and LC patients, as well as in histopathological remission ii) might potentially increase the possibility of more target-specific therapies based on IL-37 induction, chemokines or chemokine receptor inhibitions, or hindering T cell infiltration according to TCR clonality.
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