scRNAseq analysis of cytokine-treated human islet cells
Pancreatic beta-cells are essential for survival, being the only cell type capable of insulin secretion. While they are believed to be vulnerable to damage by inflammatory cytokines such as interleukin-1 beta (IL-1beta) and IFN-gamma, we have recently identified physiological roles for cytokine signaling in rodent beta-cells that include that stimulation of antiviral and antimicrobial gene expression and the inhibition of viral replication. In this study, we examine cytokine-stimulated changes in gene expression in human islets using single-cell RNA sequencing. Surprisingly, the global responses of human islets to cytokine exposure were remarkably blunted compared to our previous observations in the mouse. The small population of human islet cells that were cytokine responsive exhibited increased expression of IL-1beta-stimulated antiviral guanylate binding proteins, just like in the mouse. Most human islet cells were not responsive to cytokines, and this lack of responsiveness was associated with high expression of genes encoding ribosomal proteins. We further correlated the expression levels of RPL5 with stress response genes, and when expressed at high levels, RPL5 is predictive of failure to respond to cytokines in all endocrine cells. Further, we postulate that donor cause of death and isolation methodologies may contribute to stress of the islet preparation. Our findings indicate that induction of stress responses in human islets (associated with isolation and/or cause of death) limit cytokine stimulated gene expression, and we urge caution in the evaluation of studies that have examined cytokine-stimulated gene expression in human islets without evaluation of stress-related gene expression. Overall design: Eight samples each (no cytokine treatment, 6 hr IL-1b, 6 hr IFNg, 6 hr IL-1b + IFNg, 18 hr IL-1b, 18 hr IL-1b + IFN-g, 18 hr IL-1b + IFN-g + NMMA, and 18 hr NMMA) from three experimental replicates of human islets were prepared using 10x Genomics Chromium platform