Background: Influenza A virus infection and its complications effect a large population worldwide. Endothelial cells are an important component in lung inflammation caused by influenza A virus infection. The roles of endothelial sphingosine 1-phophate receptor 1 (S1PR1) in the regulation of molecules involved in leukocyte recruitment during influenza A virus infection still remain unknown. In this report, we tested our hypothesis that S1PR1 agonist CYM5442 inhibits expression of intracellular adhesion molecules 1 (ICAM1) in endothelial cells infected with influenza A virus.
Methods: Human pulmonary microvascular endothelial cells (HPMEC) were infected with influenza A virus H1N1. Expression of cytokines, chemokines, interferons, and cellular adhesion molecules was measured by q-PCR. Expression of ICAM1 was further tested by Western Blotting. A S1PR1 agonist CYM5442 was added to the culture media to assess CYM5442's inhibitory effects during virus infection.
Results: HPMEC could be infected with H1N1 and responded to produce pro-inflammatory cytokines, chemokines, type I interferons, and cellular adhesion molecules. Addition of CYM5442 in culture media reduced the production of ICAM1 via a dosage- and time-dependent manner. CYM5442 inhibited the activation of nuclear factor (NF)-κB. The regulatory effects of CYM5442 were β-arrestin2-dependent.
Conclusion: Activated S1PR1 signaling regulates the production of cellular adhesion molecules by inhibiting NF- κB activation via a β-arrestin2-dependent manner.