Insights into the Role of Commensal-Specific T Cells in Intestinal Inflammation.

Trillions of microorganisms exist in the human intestine as commensals and contribute to homeostasis through their interactions with the immune system. In this review, we use previous evidence from published papers to elucidate the involvement of commensal-specific T cells (CSTCs) in regulating intestinal inflammatory responses. CSTCs are generated centrally in the thymus or peripherally at mucosal interfaces and present as CD4+ or CD8+ T cells. Bacteria, fungi, and even viruses act commensally with humans, warranting consideration of CSTCs in this critical relationship. Dysregulation of this immunological balance can result in both intestinal inflammation or damaging autoimmune responses elsewhere in the body. Given the relative novelty of CSTCs in the literature, we aim to introduce the importance of their role in maintaining immune homeostasis at barrier sites such as the intestine.

Insulin is expressed by enteroendocrine cells during human fetal development.

Generation of beta cells via transdifferentiation of other cell types is a promising avenue for the treatment of diabetes. Here we reconstruct a single-cell atlas of the human fetal and neonatal small intestine. We identify a subset of fetal enteroendocrine K/L cells that express high levels of insulin and other beta cell genes. Our findings highlight a potential extra-pancreatic source of beta cells and expose its molecular blueprint.