Abstract 256: AMP-activated Protein Kinase Activator AICAR Attenuates TNFα-induced Inflammation In Murine Adipocytes.

Abstract

Adipose tissue, a metabolically active tissue and important regulator of vascular function, contributes to obesity-related cardiovascular diseases such as hypertension. Molecular mechanisms are still elusive, but inflammation and activation of a local renin-angiotensin-aldosterone system (RAAS) seem to play an important role in adipocyte dysfunction leading to vascular damage. AMP-activated protein kinase (AMPK), a key regulator of cell metabolism, may play an important role in adipose tissue biology/inflammation. In this study, we evaluated whether AMPK activation regulates TNFα-induced inflammation and RAAS status in adipocytes. Murine adipocytes (3T3-L1) were used and treated with 10ng/ml TNFα in the absence/presence of AICAR (1mM - AMPK activator). Pro-inflammatory markers were assessed by qPCR or ELISA and protein expression by immunoblotting. TNFα stimulation increased IL-6 (113.4 fold) and MCP-1 (449.6 fold) mRNA levels, as well as IL-6 release (17.67 fold) into culture medium (p<0.05, vs vehicle); an effect abrogated by AICAR (75% reduction MCP-1 mRNA, 60% reduction IL-6 mRNA and 30% reduction IL-6 release). Adiponectin mRNA levels were decreased by TNFα (60%, p<0.05 vs vehicle), yet preincubation with AICAR had no effect. The effects of TNFα were also evaluated on components of the RAAS. TNFα induced a decrease in angiotensinogen (60%), mineralocorticoid receptor (70%) and AT2R (90%) mRNA levels in adipocytes (p<0.05), which was unaffected by AICAR. Activation of AMPK also suppressed TNFα-stimulated phosphorylation of MAP kinases and NFκB assessed by immunoblotting. In conclusion, AMPK activation seems to play a role in the control of inflammation and RAAS in adipocytes. Our data highlights the importance of AMPK as an important anti-inflammatory signaling protein in adipose tissue and may be an interesting target for treatment of obesity-related vascular injury leading to hypertension. This is especially significant given that the commonly used drug metformin is an AMPK inhibitor.