Nitric Oxide Mediates Insect Cellular Immunity via Phospholipase A(2) Activation

作者：Sadekuzzaman Md; Stanley David; Kim Yonggyun^*

来源：Journal of Innate Immunity, 2018, 10(1): 70-81.

DOI：10.1159/000481524

• Nitric oxide
• Nitric oxide synthase
• Eicosanoid
• Immune response
• Spodoptera exigua

After infection or invasion is recognized, biochemical mediators act in signaling insect immune functions. These include biogenic amines, insect cytokines, eicosanoids, and nitric oxide (NO). Treating insects or isolated hemocyte populations with different mediators often leads to similar results. Separate treatments with an insect cytokine, 2 biogenic amines, and an eicosanoid lead to a single result, hemocyte spreading, understood in terms of intracellular cross-talk among these signaling systems. This study focuses on the cross-talk between NO and eicosanoid signaling in our model insect, Spodoptera exigua. Bacterial injection increased NO concentrations in the larval hemocytes and fat body, and RNA interference (RNAi) of the S. exigua NO synthase (NOS) gene suppressed NO concentrations. RNAi treatment also led to a significant reduction in hemocyte nodulation following bacterial injection. Similar RNAi treatments led to significantly reduced PLA(2) activities in the hemocytes and fat body compared to control larvae. Injection of L-NAME also prevented the induction of PLA(2) activity following bacterial challenge. An injected NO donor, S-nitroso-N-acetyl-DL-penicillamine, increased PLA(2) activity in a dose-dependent manner. However, eicosanoids did not influence NO concentrations in immune-challenged larvae. We infer that NO and eicosanoid signaling operate via cross-talk mechanisms in which the elevated NO concentrations activate PLA(2) and eicosanoid biosynthesis, which finally mediates various immune responses.

• 出版日期2018