GPR43 stimulation on TCRαβ+ intraepithelial colonic lymphocytes inhibits the recruitment of encephalitogenic T-cells into the central nervous system and attenuates the development of autoimmunity

Abstract

Introduction Gut microbiota plays a critical role in the regulation of immune homeostasis. Accordingly, several autoimmune disorders have been associated with dysbiosis in the gut microbiota. Notably, the dysbiosis associated with central nervous system (CNS) autoimmunity involves a substantial reduction of bacteria belonging to Clostridia clusters IV and XIVa, which constitute major producers of short-chain fatty acids (SCFAs). Here we addressed the role of the surface receptor-mediated effects of SCFAs on mucosal T-cells in the development of CNS autoimmunity. Methods To induce CNS autoimmunity, we used the mouse model of experimental autoimmune encephalomyelitis (EAE) induced by immunization with the myelin oligodendrocyte glycoprotein (MOG)-derived peptide (MOG35-55 peptide). To address the effects of GPR43 stimulation on colonic TCRαβ+ T-cells upon CNS autoimmunity, mucosal lymphocytes were isolated and stimulated with a selective GPR43 agonist ex vivo and then transferred into congenic mice undergoing EAE. Several subsets of lymphocytes infiltrating the CNS or those present in the gut epithelium and gut lamina propria were analysed by flow cytometry. In vitro migration assays were conducted with mucosal T-cells using transwells. Results Our results show a sharp and selective reduction of intestinal propionate at the peak of EAE development, accompanied by increased IFN-γ and decreased IL-22 in the colonic mucosa. Further analyses indicated that GPR43 was the primary SCFAs receptor expressed on T-cells, which was downregulated on colonic TCRαβ+ T-cells upon CNS autoimmunity. The pharmacologic stimulation of GPR43 increased the anti-inflammatory function and reduced the pro-inflammatory features in several TCRαβ+ T-cell subsets in the colonic mucosa upon EAE development. Furthermore, GPR43 stimulation induced the arrest of CNS-autoreactive T-cells in the colonic lamina propria, thus avoiding their infiltration into the CNS and dampening the disease development. Mechanistic analyses revealed that GPR43-stimulation on mucosal TCRαβ+ T-cells inhibits their CXCR3-mediated migration towards CXCL11, which is released from the CNS upon neuroinflammation. Conclusions These findings provide a novel mechanism involved in the gut-brain axis by which bacterial-derived products secreted in the gut mucosa might control the CNS tropism of autoreactive T-cells. Moreover, this study shows GPR43 expressed on T-cells as a promising therapeutic target for CNS autoimmunity.

Increased regulatory activity of intestinal innate lymphoid cells type 3 (ILC3) prevents experimental autoimmune encephalomyelitis severity

“…Similarly, it has also been shown that Ffar2-mediated potentiation of ILC3 activity to produce IL-22 was beneficial to ameliorating Clostridium difficile infection [ 17 ]. Recently, it has been reported that colonic intraepithelial cells treated with a different Ffar2 agonist (4-CMTB) in vitro and then adoptively transferred into EAE recipient mice during the inductive phase of the disease efficiently ameliorated EAE [ 30 ]. In our study, we build upon these previous findings by demonstrating that dosing of Cpd1 during the inductive phase of EAE significantly reduces the severity of disease.…”

“…In our study, we build upon these previous findings by demonstrating that dosing of Cpd1 during the inductive phase of EAE significantly reduces the severity of disease. In the work of Prado and colleagues [ 30 ], the focus of the study was on the influence of the Ffar2 agonist 4-CMTB on colonic T cells. They were able to demonstrate that encephalitogenic T cells migrate into the colonic intraepithelial compartment before they infiltrate CNS.…”

“…They were able to demonstrate that encephalitogenic T cells migrate into the colonic intraepithelial compartment before they infiltrate CNS. Furthermore, transfer of 4-CMTB-treated intraepithelial cells into EAE mice led to retention of encephalitogenic cells in the gut mucosa, and consequently prevented their infiltration into CNS [ 30 ]. This study delineates the importance of Ffar2 signaling in colonic T cells for counteracting CNS autoimmunity.…”

Identification of master regulator genes controlling pathogenic CD4+ T cell fate in inflammatory bowel disease through transcriptional network analysis

“…The isolation of lamina propria lymphocytes from the colon was performed as previously described with minor modifications 13 . Briefly, colons were cut open longitudinally and washed with cool HBSS containing 10 mM HEPES to remove feces and debris.…”

“…qRT-PCR quantifications were performed as described before 13 . Total RNA was treated with DNase using the Ambion TURBO DNA-free kit (Life Technologies) and then used to synthesize cDNA catalyzed by the M-MLV reverse transcriptase (Life Technologies).…”