TLR4 and Insulin resistance: Increased plasma levels of palmitic acid can serve as the natural endogenous ligand of TLR4 that results in an abnormal TLR4 gene expression and TLR/NF-κB signal transduction and increases in the gene expression of the inflammatory cytokine IL-6 and SOD2 (mitochondrial superoxide dismutase), which could be one of the pathological mechanisms of insulin resistance [25].