TLR4 and bacterial infectious disease: Many studies have demonstrated that the Toll and IMD signaling pathways can inhibit viral and bacterial infections by regulating the expression of AMPs (such as crustin (93, 94), penaeidin (95, 96), anti-lipopolysaccharide (anti-LPS) factor (97–99), and lysozyme (100, 101), promoting apoptosis (102–104) and producing ROS (105).