Clin Exp Rheumatol
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Rheumatoid arthritis (RA) patients with high body mass index (BMI) show lower mortality than thinner patients, indicating a paradoxical effect of body mass on mortality in RA. We considered that leptin might play some part in this mechanism. Leptin regulates not only body weight, but also inflammatory processes. Furthermore, hyperleptinemia decreases sensitivity to leptin (leptin resistance). This study examined whether high-fat diet-induced hyperleptinemic obese mice with acquired leptin resistance show reduced inflammation induced by collagen antibody-induced arthritis (CAIA). ⋯ High-fat diet-induced obese mice acquired peripheral leptin resistance reducing the development of CAIA. Leptin sensitivity was associated with severity of arthritis. These results suggest that RA patients with high BMI who acquire leptin resistance may show reduced inflammation. However, the real function of leptin in the immune system remains partly unclear.