TLR4 and serum lipopolysaccharide activity: Endotoxemia activates a signaling cascade in which LPS binds to toll like receptor 4 (TLR4) complex, activating the Toll-like receptor 4 (TLR4) and stimulating NF-κB to produce inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) [72].