Accordingly high cholesterol and HFD would lead to low-grade pulmonary inflammation through activating TLR4/NFκB signaling [45] while significant lower methylation of CpGs in the first exon of the TLR4 were observed in obese individuals, indicating epigenetic regulation of TLR4 expression in obesity [48]. Here, TLR4 is linked to obesity due to melanocortin 4 receptor deficiency.