LEP and obesity due to melanocortin 4 receptor deficiency: Consistent with the attributed pro-inflammatory properties, Ntn1 levels have been positively correlated with the expression of Mcp1, Tnf, Unc5b, and leptin (Lep) in adipocytes and macrophages treated with IL-20, a pro-inflammatory cytokine involved in adipogenesis as well as in macrophage dysregulation in obesity [15].