Human Peripancreatic Adipose Tissue Paracrine Signaling Impacts Insulin Secretion, Blood Flow, and Gene Transcription.

Abstract

Adipose tissue accumulation around nonadipose tissues is associated with obesity and metabolic disease. One relatively unstudied depot is peripancreatic adipose tissue (PAT) that accumulates in obesity and insulin resistance and may impact β-cell function. Pancreatic lipid accumulation and PAT content are negatively related to metabolic outcomes in humans, but these studies are limited by the inability to pursue mechanisms. We obtained PAT from human donors through the Human Pancreas Analysis Program to evaluate differences in paracrine signaling compared to subcutaneous adipose tissue (SAT), as well as effects of the PAT secretome on aortic vasodilation, human islet insulin secretion, and gene transcription using RNA sequencing. PAT had greater secretion of interferon-γ and most inflammatory eicosanoids compared to SAT. Secretion of adipokines negatively related to metabolic health were also increased in PAT compared to SAT. We found no overall effects of PAT compared to SAT on human islet insulin secretion; however, insulin secretion was suppressed after PAT exposure from men compared to women. Vasodilation was significantly dampened by PAT conditioned media, an effect explained almost completely by PAT from men and not women. Islets treated with PAT showed selective changes in lipid metabolism pathways while SAT altered cellular signaling and growth. RNA sequencing analysis showed changes in islet gene transcription impacted by PAT compared to SAT, with the biggest changes found between PAT based on sex. The PAT secretome is metabolically negative compared to SAT, and impacts islet insulin secretion, blood flow, and gene transcription in a sex-dependent manner.