S1PR1 regulates NDV-induced IL-1β expression via NLRP3/caspase-1 inflammasome.

Newcastle disease (ND) is an acute, febrile, and highly contagious disease caused by the Newcastle disease virus (NDV), an important pathogen harmful to domestic poultry. Virulent NDV strain infection induces IL-1β expression and along with strong inflammatory response, ultimately results in death. Inhibition or overexpression of S1PR1, an important target for inflammatory disease treatment, regulates IL-1β expression, suggesting that S1PR1 may alter the degree of the inflammatory response induced by NDV infection by regulating pro-inflammatory cytokine expression. However, the molecular mechanism by which S1PR1 regulates IL-1β expression remains unclear. Here, we explore the expression and tissue distribution of S1PR1 after NDV infection and found that S1PR1 expression increased in the lungs, bursa of Fabricius, and DF-1. IL-1β expression induced by NDV was increased following treatment of cells with the S1PR1-specific agonist, SEW2871. In contrast, IL-1β expression induced by NDV was decreased after cells were treated with the S1PR1 inhibitor W146, suggesting that S1PR1 promotes NDV-induced IL-1β expression. Further investigation demonstrated that NDV induced IL-1β expression through p38, JNK/MAPK, and NLRP3/caspase-1 signaling molecules and S1PR1 affected the expression of IL-1β by activating the NLRP3/caspase-1 inflammasome but had no significant effect on p38 and JNK/MAPK. Our study shows that NDV infection promotes S1PR1 expression and induces IL-1β expression through p38, JNK/MAPK, and NLRP3/caspase-1 inflammasomes and that S1PR1 regulates IL-1β expression mainly through the NLRP3/caspase-1 inflammasome.