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Single-cell transcriptome profiling of pancreatic islets from early diabetic mice identifies Anxa10 for Ca2+ allostasis toward β-cell failure

Type 2 diabetes (T2D) is a progressive disorder denoted by hyperglycemia and impaired insulin secretion. Although a decrease in β-cell function and mass is a well-known trigger for diabetes, the comprehensive mechanism is still unidentified. Here we carried out single-cell RNA sequencing (scRNA-seq) of pancreatic islets from prediabetic and diabetic db/db mice, an animal model of T2D. We discovered a diabetes-specific transcriptome landscape of endocrine and nonendocrine cell types with subpopulations of β and α cells. We recognized a new prediabetic gene, Anxa10, that was induced by, and regulated Ca2+ influx from metabolic stresses. Anxa10-overexpressed β cells displayed suppression of glucose-stimulated intracellular Ca2+ elevation and potassium-induced insulin secretion. Pseudotime analysis of β cells predicted this Ca2+-surge responder-cluster proceeded to mitochondria dysfunction and also endoplasmic reticulum stress. Other trajectories comprised dedifferentiation and transdifferentiation, emphasizing acinar-like cells in diabetic islets. Altogether, our data provides a new insight into Ca2+ allostasis and β cell failure processes.</p

Treg induction by a rationally selected mixture of Clostridia strains from the human microbiota

Manipulation of the gut microbiota holds great promise for the treatment of inflammatory and allergic diseases1, 2. Although numerous probiotic microorganisms have been identified3, there remains a compelling need to discover organisms that elicit more robust therapeutic responses, are compatible with the host, and can affect a specific arm of the host immune system in a well-controlled, physiological manner. Here we use a rational approach to isolate CD4+FOXP3+ regulatory T (Treg)-cell-inducing bacterial strains from the human indigenous microbiota. Starting with a healthy human faecal sample, a sequence of selection steps was applied to obtain mice colonized with human microbiota enriched in Treg-cell-inducing species. From these mice, we isolated and selected 17 strains of bacteria on the basis of their high potency in enhancing Treg cell abundance and inducing important anti-inflammatory molecules—including interleukin-10 (IL-) and inducible T-cell co-stimulator (ICOS)—in Treg cells upon inoculation into germ-free mice. Genome sequencing revealed that the 17 strains fall within clusters IV, XIVa and XVIII of Clostridia, which lack prominent toxins and virulence factors. The 17 strains act as a community to provide bacterial antigens and a TGF-β-rich environment to help expansion and differentiation of Treg cells. Oral administration of the combination of 17 strains to adult mice attenuated disease in models of colitis and allergic diarrhoea. Use of the isolated strains may allow for tailored therapeutic manipulation of human immune disorders