LEP and obesity due to melanocortin 4 receptor deficiency: Leptin is also closely associated with IL-6, and leptin can upregulate the expression of IL-6 through the activation of the NF-κB signaling pathway leading to LF inflammation.[55,56] It is worth noting that leptin was originally a hormone secreted by adipose tissue, and leptin levels in human serum rise with increasing body fat,[57] suggesting that obesity is one of the factors in LFH, which shows that the inhibition of leptin expression and weight loss are important for alleviating LF inflammation.