TLR4 and bacterial infectious disease: Bacterial infection induces the disease by activating toll-like receptors (TLR4, 7 and 9), high-affinity IgE receptor (FcεR1), and complement receptors to release pro-inflammatory mediators, cytokines, histamine, and other mediators resulting in leukocyte infiltration, sensory nerve activation, vasodilatation, and intradermal edema [17,18].