Inflammation and Insulin Resistance in Rheumatoid Arthritis

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Inflammation and Insulin Resistance in RA Rheumatoid arthritis (RA), affects approximately 1% of the population and is associated with an increased prevalence of ischemic heart disease. We have shown that the prevalence of coronary artery atherosclerosis is increased markedly in patients with RA, but the underlying mechanisms are not known. In preliminary studies we found that insulin concentrations are more than 2-fold higher in patients with RA than controls and are correlated with inflammatory markers such as IL6, TNF and CRP, and with coronary atherosclerosis. Thus, related processes, inflammation and hyperinsulinemia, contribute mechanistically to increased cardiovascular morbidity in RA. The relationship between hyperinsulinemia and inflammation is bi-directional - inflammation facilitates insulin resistance, and insulin resistance promotes chronic inflammation. Thiazolidinediones, selective PPARy agonists, are insulin sensitizers even in individuals without diabetes and are a powerful tool to understand the mechanisms underlying the realtionship between inflammation and insulin resistance. Thiazolidinediones, not only improve insulin sensitivity, but also decrease inflammation, including arthritis in animal models. Thus, in a proof-of-concept translational study, we will randomize patients with RA to receive pioglitazone or placebo for 6 months to test the hypotheses that treatment with a PPARy agonist will decrease inflammation (Specific Aim 1), improve insulin sensitivity (Specific Aim 2) and improve augmentation index (Specific Aim 3) in patients with RA. The proposed studies will provide mechanistic information regarding the relationship between inflammation and hyperinsulinemia, and will identify novel strategies for potentially reversing or preventing the long term damage to joints and the vasculature in RA, and perhaps other inflammatory diseases.