RETN and obesity due to melanocortin 4 receptor deficiency: Thus, these findings provide evidence for a causal link between LPS and the up-regulated production of adipokines such as leptin, resistin, IL-6, MCP-1 and PAI-1 involved in obesity-associated inflammation, insulin resistance and vascular dysfunction, and the down-regulated production of adiponectin in favor of insulin sensitivity and vascular protection.