Effect of influenza A virus and bacterial lipopolysaccharide on proliferation and expression of cytokines and other cellular factors in the endothelial cell line ECV-304

Viral infection and bacterial lipopolysaccharide (LPS) cause endothelial-cell dysfunction. The aim of the current study was to investigate the effect of influenza A virus and LPS from Escherichia coli on the proliferative activity and gene expression of cytokines and cellular factors (TNFα, TGFβ, IFN-γ, MMP-9, NF-κB, Rho A, eNOS, and iNOS) in human endothelial cells ECV-304. It was found that ECV-304 cells infected with very low infectious doses of influenza virus acquired the capacity for the long-term active proliferation (over eight passages). Addition of LPS from E. coli reduced the virus-stimulated cell proliferation. It was shown that influenza virus and LPS affected the gene expression of cytokine and other cellular factors. When endothelial cells were infected with influenza A virus in the presence of LPS, there was a significant increase in the expression of several genes and the expression pattern of certain genes was modified. Expression of MMP-9 gene inhibited by the virus and LPS separate exposure significantly increased during the first day after addition of the virus and LPS simultaneously. The same was true for the IFN-γ gene expression. TNFα gene was active only for 1–3 days whereas the expression of TGFβ, eNOS, iNOS, NF-κB and Rho A genes increased significantly on the fifth day, as it was observed with the cells treated with LPS only. Thus, the influenza A virus and LPS change the physiological state of endothelial cells. This occurred during various time periods (as well as at various degrees of viral infection) produced by different cellular factors and, possibly, involved different signaling pathways.