The downregulation of expression of both adiponectin receptors by peptidoglycan parallels the reduction of soluble adiponectin receptor expression after the administration of LPS to human subjects [37] and suggests that TLR2 activation in obesity may partly be responsible for the downregulation of adiponectin receptor expression in adipose tissue in obesity [22]. Here, TLR2 is linked to obesity due to melanocortin 4 receptor deficiency.