Peripheral sgp130-mediated trans-signaling blockade induces obesity and insulin resistance in mice via PPARα suppression
IL-6 signaling via its receptor (IL-6R) and co-receptor (gp130) performs multiple roles in regulating metabolic homeostasis. However, gp130 is also expressed systemically in a soluble form (sgp130), which limits soluble IL-6 receptor (sIL-6R)-mediated signaling - also called trans-signaling. Here we find that transgenic peripheral sgp130-mediated trans-signaling blockade induces mature-onset obesity, while differentially affecting age-dependent behavioral determinants of energy expenditure. In youth, trans-signaling blockade increases feeding associated with reduced leptin sensitivity but increases energy expenditure to maintain metabolic balance. In aging, reduced physical activity predisposes mice to adiposity, adipose tissue macrophage recruitment, hepatosteatosis, hyperglycemia, and insulin resistance. Mechanistically, trans-signaling blockade reduces hepatic Stat3 phosphorylation and suppresses PPAR, associated with miR-21 upregulation, while pharmacological activation of PPAR prevents obesity and hepatosteatosis, and rescues insulin sensitivity. Together these experiments reveal a role for peripheral IL-6 trans-signaling in metabolic homeostasis and provide clinical significance to elevated sgp130 levels found in some obese and diabetic patients.