Background: The new emerging Influenza A/H7N9 virus causes sever illness and significant mortality in adult humans., but the mechanism of pathogenesis is not clear. To this aims, we explored the possible role of immune response associated with the severity of H7N9 virus infection.
Material: Influenza A/H7N9 infected patients admitted to Shanghai Public Health Clinical Center in April of 2013 were recruited in this study. Serum and throat swab samples were collected at multiple timepoints during the antiviral therapy. Clinical samples from pandemic influenza A/H1N1/2009 sever cases with corresponding age were also enrolled as control. The cytokines level in serum was measured by multiplex assay. Viral load in serum and throat swab samples were quantitated by RT-PCR .
Results: H7N9 patients showed elevated cytokines (IL-6, IL-10, IFN-gamma) and chemokines (MCP-1, IP-10) comparing with healthy donors when they were admitted in hospital. Among these cytokines, MCP-1 and IP-10 in H7N9 patients on admission were even higher than those in H1N1 patients. Notably, the serum levels of IP-10 and IL-6 were associated with the severity of H7N9 infection and the levels of IL-6, IL-10, IFN-gamma, IP-10 and MCP-1 were correlated with the viral load in serum and throat swab samples. Surprisingly, the upregulated cytokines companied with the reduced peripheral lymphocytes.
Conclusion: The disease severity of H7N9 infection was strongly associated with levels of inflammatory cytokines and chemokines in circulation which suggested the systematic features of this disease.