Influenza A virus inhibits influenza virus replication by inducing IL-37.

ABSTRACT

BACKGROUNDS The influenza virus is one of the major pathogens that seriously affect human health. It can cause a strong immune response and trigger a series of complications. Interleukin 37 (IL-37) is a newly discovered cytokine that plays an important regulatory role in infection and immunity. To date, there have been few studies on the correlation between influenza virus infection and IL-37. METHODS: Serum levels of IL-37 in 115 patients with influenza A virus (IAV) infection and 102 healthy subjects were measured by an enzyme-linked immunosorbent assay (ELISA). Real-time quantitative PCR (RT-qPCR) was used to detect differences in IL-37 expression in peripheral blood mononuclear cells (PBMCs) between IAV patients and healthy subjects. IL-37 expression was measured in A549 cells and PBMCs infected with IAV H3N2 using ELISA and RT-qPCR. After the H3N2-infected A549 cells were treated with human IL-37, the concentration of viral RNA was determined using RT-qPCR, and the titer of influenza virus was determined by a hemagglutination test. RESULTS: The IL-37 levels in the sera and PBMCs of patients infected with IAV were higher than those of healthy subjects. The expression of IL-37 mRNA and protein in IAV-infected A549 cells and PBMCs was upregulated, and IL-37 protein was able to inhibit the replication of IAV RNA. CONCLUSION: IAV-induced IL-37 expression inhibits IAV replication.