The inducible nitric oxide synthase (iNOS) of Eriocheir sinensis exerts antibacterial effects through apoptosis

Inducible nitric oxide synthase (iNOS) is a key molecule in the invertebrate innate immune system. However, its precise mechanism of action remains poorly understood. In this study, iNOS expression was significantly induced following challenge with Aeromonas hydrophila. After RNA interference and iNOS inhibitor treatment, the bacterial content in the hemolymph significantly increased, confirming the involvement of iNOS in antibacterial defense. Mechanistic studies revealed that iNOS activation is associated with nuclear translocation of p65, and that alterations in iNOS expression affect the expression levels of integrins, MAPK, and PI3K-Akt signaling pathways. Upon activation, iNOS not only elevates the levels of NO and ROS but also induces apoptosis, thereby exerting its antibacterial effects. Collectively, these findings indicate that iNOS plays a significant role in the antibacterial immunity of crustaceans and provide new insights into the host defense mechanisms of invertebrates.