Accelerated Recovery from Acute Hypoxia in Obese Mice Is Due to Obesity-Associated Up-Regulation of Interleukin-1 Receptor Antagonist

Abstract

The proinflammatory consequences of obesity are thought to be due, in part, to macrophage infiltration into adipose tissue. There are, however, potential antiinflammatory consequences of obesity that include obesity-associated up-regulation of IL-1 receptor antagonist (IL-1RA). Here we show that obesity-associated up-regulation of IL-1RA speeds recovery from hypoxia. We found that high-fat diet-fed (HFD) mice recovered from acute hypoxia 5 times faster than normal-diet-fed (ND) mice. HFD mice had a 10-fold increase in serum IL-1RA when compared with ND mice. White adipose tissue (WAT) was a significant source of IL-RA, generating 330 +/- 77 pg/mg protein in HFD mice as compared with 15 +/- 5 pg/mg protein in ND mice. Peritoneal macrophages isolated from HFD mice showed little difference in IL-1RA production when compared with ND mice, but WAT macrophages from HFD mice generated 11-fold more IL-1RA than those from ND mice. When ND mice were given an ip transfer of the stromal vascular fraction portion of WAT from HFD mice, serum IL-1RA increased 836% and recovery from acute hypoxia was faster than in mice that did not receive a stromal vascular fraction transfer. To determine whether IL-1RA was important to this accelerated recovery, ND mice were administered exogenous IL-1RA prior to hypoxia, and their recovery matched that of HFD mice. Inversely, when IL-1RA was immunoabsorbed in HFD mice with IL-1RA antiserum, recovery from acute hypoxia was attenuated. Taken together these data demonstrate that HFD-induced obesity speeds recovery from hypoxia due to obesity-associated up-regulation of IL-1RA.