TLR4 and infection: Humoral immunity pathways, such as Toll and Imd, are generally activated upon infection by Gram-positive and Gram-negative bacteria, respectively, and lead to the production of distinct sets of AMPs, such as drosomycin, defensin and metchnikowin (Toll pathway) and attacin, cecropin and diptericin (Imd pathway) [85–89].