Fig. 2
From: Immune response in influenza virus infection and modulation of immune injury by viral neuraminidase
The relationship of virus, immunity response, cytokine and lung. (1) Factor: from virus (NA activity, NA stalk length and transmembrane), from host (age, obesity and host factor), and these factors can affect immune response; (2) Phospholipid and p21 locate in the pulmonary epithelium, S1PR1 locate in the pulmonary endothelium, SOCS3 as inhibitory cytokine, pulmonary endothelium is central orchestrator of cytokine amplification. When virus invade body, p21 expression reduced, SOCS3 and S1PR1 signaling improved, immune cells are activated, frequent the number of cytokines is reduced, lung injury was decreased; (3) When body is infected with influenza virus, phospholipid increased, then the number of cytokines is increased, immune cells are inhibited, lead to cytokine storm and finally cause lung injury; (4) When virus invaded, TGF-β is activated through virus NA, then upregulated expression of cellular adhesins, immune cells are inhibited, and lead to cytokine storm, cause bacterial pneumonia