Studying the function of α7 nicotinic acetylcholine receptor in Drosophila humoral immunity

Acetylcholine (ACh) is one the major neurotransmitters, whose role in mediating synaptic interactions between neurons in the central nervous system in vertebrates and invertebrates is well characterized. It also plays largely unexplored regulatory functions in non-neuronal tissues. Here we demonstrate that ACh signaling is involved in the modulation of the innate immune response of Drosophila melanogaster. Knockdown of ACh synthesis or ACh vesicular transport in neurons reduced the activation of drosomycin (drs), a gene encoding an antimicrobial peptide, in adult flies infected with a Gram-positive bacterium. Our results indicate that the nicotinic acetylcholine receptor α7 (Dα7) is involved in the cholinergic pathway that modulates drs gene expression in both neuronal and non-neuronal tissues, demonstrating a cholinergic activity in hemocytes. In conclusion, our results allowed us to establish that the innate humoral immune response is modulated by neuronal and non-neuronal cholinergic signals.