Project description:Th17 cells are a heterogeneous population that is critical for tissue homeostasis and inflammation during clearance of infections and autoimmunity. Despite substantial efforts distinguishing homeostatic and inflammatory roles of Th17 cells, the mechanism underlying the divergent functions of inflammatory Th17 cells is poorly understood. In this study, we show that the inflammatory Th17 engaged in autoimmune colitis and those involved in infection-induced colitis are two distinguishable populations illustrated by their distinct responses to a pharmacological molecule, clofazimine (CLF). Distinct from existing Th17 inhibitors, CLF selectively inhibits pro-autoimmune Th17 cells while preserving the functional state of infection-elicited Th17 cells through restricting Aldh1l2expression. Using single-cell RNA sequencing, we explored inflammatory Th17 transcriptional response to CLF from the colonic tissue of mice during autoimmune colitis and Citrobacter rodentiuminfection using Rorc gfp/+ reportor mice. Notably, we identified a unique suppression in the transcription of signature inflammatory genes in Th17 cells from autoimmune colitis with a marginal effect on those elicited by infection. Additionally, we illustrate with these data that the transcriptionally programming of pro-autoimmune Th17 cells are, indeed, unique compared to infection-elicited Th17 cells. Finally, we analyzed the impact of CLF on human inflammatory Th17 cells from the inflammed colon of a patient with IBD.
Project description:Secretory IgA (SIgA) is critical for maintaining the intestinal barrier. A dysregulated B-cell compartment and altered Ig secretion have been well documented in Crohn’s disease (CD) patients, although their origin is unknown. To unravel the role of mucosal humoral immunity in CD pathogenesis, we in-depth phenotype colonic plasma cell (PC) differentiation in CD at the single-cell level, linked to ex vivo functional characterization and experimental mouse models with a congenital mitochondrial defect or under glucose-free high-protein dietary intervention. Here, we demonstrate that despite expanded colonic B cells, CD patients in remission present significantly diminished mucosal dimeric IgA and fecal SIgA. Colonic plasmablasts and immature CD19+CD45+ PCs are increased at the expense of the mature CD19-CD45- phenotype. Accordingly, CD-derived ex vivo differentiated PCs display impaired maturation into dimeric IgA-secreting PCs. In this study, patient-derived data from colonic RNA-seq, spatial single-cell proteomics, and plasma metabolomics are combined with data from both mouse models and highlight the crucial role of mitochondrial oxidative phosphorylation in colonic IgA+-PC differentiation, suggesting promising directions for future therapeutic strategies.
Project description:Single cell RNA sequencing of the mouse colonic mesenchyme. Mesenchymal/lamina propria cells were isolated from the middle and distal colon of wild type mice and were pooled. The vast majority of intestinal epithelial cells were depleted by Ethylenediaminetetraacetic acid (EDTA) treatment of the tissue samples and mesenchymal/lamina propria cells were isolated after enzymatic treatment with collagenase XI and dispase. Single cell RNA sequencing was performed with the Drop-seq protocol.