Shufeng Jiedu capsule alleviates influenza A (H1N1) virus induced acute lung injury by regulating the lung inflammatory microenvironment.

Background: Death caused by respiratory tract infection is one of the leading causes of death in the world today. Shufeng Jiedu Capsule (SFJDC) is a traditional Chinese medicine that has been widely used clinically for coronavirus disease 2019 (COVID-19), H1N1 influenza virus pneumonia and other diseases. Its pharmacological effect is to inhibit inflammation and improve the body's ability to clear viruses. However, the mechanism of SFJDC in the treatment of viral pneumonia, especially its effect on the inflammatory-immune microenvironment of lung tissue remains unclear.

Methods: Mice with H1N1 influenza virus pneumonia were used as a model to verify the efficacy of SFJDC through death protection, lung index, viral load, and HE staining of lung tissue. The levels of inflammatory cytokines and chemokines in lung tissue were investigated by multi-analyte immunoassay. The number and proportion of cells in peripheral blood were detected by blood routine. The percentage of infiltrating immune cells in lung tissue was detected by flow cytometry and immunofluorescence.

Results: SFJDC (2.2 g/kg·d and 1.1 g/kg·d) increased survival rate (＜0.01, ＜0.05), prolonged the survival period of mice, and alleviated the histopathological damage in lung (＜0.01). SFJDC (2.2 g/kg·d, 1.1 g/kg·d and 0.055 g/kg·d) increased body weight(＜0.01, ＜0.05), improved activity status, reduced the lung index (＜0.01, ＜0.05) and viral load (＜0.01). SFJDC (2.2 g/kg·d and 1.1 g/kg·d) reduced interleukin-1β (IL-1β), interleukin-18(IL-18), tumour necrosis factor α (TNF-α), monocyte chemoattractant protein (MCP), chemokine (C-X-C motif) ligand 1 (CXCL1) (＜0.01, ＜0.05), and SFJDC (2.2 g/kg·d) increased IL-10 levels (＜0.05) to regulate inflammation. SFJDC (2.2 g/kg·d) increased the percentages of CD4 T cells (＜0.01), CD8 T cells (＜0.05), and B cells(＜0.05), and decreased F4/80 macrophages (＜0.05).

Conclusion: Our findings indicated that SFJDC could inhibit inflammation and lung injury while maintaining the function of the adaptive immune response mediated by T and B cells, and promote the clearance of the virus, thereby treating influenza A (H1N1) virus-induced pneumonia.