Innate immune signalling in the adipocyte.

Innate immune receptors detect molecular features of pathogen presence and cellular damage, enabling cells to mount anti-microbial defences including the secretion of proinflammatory cytokines. Though classically studied in immunocytes, a remarkably broad range of innate immune receptor activity is now recognized in adipocytes, including that of Toll-like receptors, NOD-like receptors, inflammasomes and nucleic acid sensors such as cGAS-STING and RIG-I. These receptors influence adipocyte proinflammatory potential through control of secreted signalling factors that act in adipose tissue. Through less well-understood mechanisms, they also influence adipocyte insulin sensitivity, lipolysis, fatty acid oxidation and thermogenesis. Innate immune receptors are activated by a diverse array of stimuli, including circulating signalling factors and intracellular metabolic stresses, especially those related to mitochondrial function. The receptors are thus a potential means by which obesity-associated signals act through adipocytes to drive inflammation, adipose dysfunction and metabolic disease pathogenesis.