PTGS2 and obesity due to melanocortin 4 receptor deficiency: Obesity resulted in a marked increase in the expression of cyclooxygenase-2 (COX-2) and IL-6 in the adipose tissue of HFD animals, with concurrent moderate increases in TNF-α, IL-17A, and IL-18, while IL-1β changes were minor and inducible nitric oxide synthase (iNOS) expression was reduced (Figure 4a).