Curcumin alleviates macrophage activation and lung inflammation induced by influenza virus infection through inhibiting the NF-κB signaling pathway

Background: Influenza A viruses (IAV) result in severe public health problems with worldwide each year. Overresponse of immune system to IAV infection leads to complications, and ultimately causing morbidity and mortality. Objective: Curcumin has been reported to have anti-inflammatory ability. However, its molecular mechanism in immune responses remains unclear. Methods: We detected the pro-inflammatory cytokine secretion and nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kappa B)-related protein expression in human macrophages or mice infected by IAV with or without curcumin treatment. Results: We found that the IAV infection caused a dramatic enhancement of pro-inflammatory cytokine productions of human macrophages and mice immune cells. However, curcumin treatment after IAV infection downregulated these cytokines production in a dose-dependent manner. Moreover, the NF-kappa B has been activated in human macrophages after IAV infection, while administration of curcumin inhibited NF-kappa B signaling pathway via promoting the expression of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (I kappa B alpha), and inhibiting the translocation of p65 from cytoplasm to nucleus. Conclusions: In summary, IAV infection could result in the inflammatory responses of immune cells, especially macrophages. Curcumin has the therapeutic potentials to relieve these inflammatory responses through inhibiting the NF-kappa B signaling pathway.