Toll and Imd Signaling Pathway

1. Toll and Imd Signaling Pathway The immune response of insects includes humoral immunity and cellular immunity. Humoral immunity mainly produces antibacterial peptides from fat bodies to resist the reaction of invading pathogenic microorganisms; cellular immunity mainly kills invasive pathogenic microorganisms through the activity of immune cells, including phagocytosis, nodule and cyst. Whether it is humoral immunity or cellular immunity, the immune response includes three phases: 1) recognition of invading pathogens; 2) cascade amplification of immunostimulatory signals; 3) production of effectors or activation of cellular immune activity. Pathogenic microorganisms have special pathogen-associated ligands on the surface, which can be recognized on the surface of insect cells or secreted receptors; interactions between ligands and receptors, cascade amplification of transduction signals, and finally the generation of antimicrobial peptides, which in turn triggers phagocytosis, nodule and cyst activity. For example, an important feature of the Drosophila immune response is that fat cells can rapidly synthesize some antimicrobial peptide molecules when infected or damaged by pathogenic microorganisms. These molecules secreting into the hemolymph can kill the invading pathogenic microorganisms. In addition, weasand and epithelial cells of Drosophila can also produce antibacterial peptides, and intestinal cells and salivary gland cells can produce antibacterial proteins such as lysozyme and insect defensins. So far, thirty genes encoding antibacterial proteins have been identified in the Drosophila genome, of which eight have been identified. https://www.creative-diagnostics.com/toll-and-imd-signaling-pathway.htm