Fuzheng Jiedu decoction alleviates H1N1 virus-induced acute lung injury in mice by suppressing the NLRP3 inflammasome activation.

Ethnopharmacological Relevance: Severe influenza, marked by excessive cytokine production, is a major contributor to death in hospitalized individuals. Fuzheng Jiedu decoction (FZJDD), an effective traditional Chinese herbal recipe, has demonstrated promising results in combating the COVID-19 pandemic by reducing mortality and improving Symptoms, and has exhibited anti-inflammatory properties in both clinical trials and laboratory research. Given that pneumonia is a common outcome of SARS-CoV-2 and H1N1 virus infections, we hypothesized that FZJDD may also have therapeutic effects on influenza-related pneumonia and acute lung injury (ALI).

Aim Of The Study: This research sought to explore the impact and underlying mechanisms of FZJDD on ALI caused by the H1N1 virus in mice.

Materials And Methods: FZJDD was characterized using UHPLC-MS/MS. A mouse model infected with H1N1 virus was used to examine the therapeutic and protective benefits of FZJDD in a living organism, by monitoring body weight fluctuations, lung index, histopathological changes, lung injury scores, and survival rates. Lung tissues underwent hematoxylin-eosin staining, western blotting, qRT-PCR and plaque reduction assay. Blood serum was gathered to assess levels of IL-1β, IL-6, TNF-α through ELISA testing. The impact of FZJDD on the NLRP3 inflammasome was further evaluated in macrophages.

Results: FZJDD treatment significantly mitigated weight loss, reduced lung index, alleviated histopathological injury, and improved the survival rates in mice with H1N1 virus-induced ALI, demonstrating a protective effect against influenza virus infection. qRT-PCR and western blot assays revealed that FZJDD treatment ameliorated the hyperinflammatory response caused by the H1N1 virus in lung tissue by suppressing NLRP3 inflammasome activation, without impacting viral replication. In vitro experiments additionally verified that FZJDD treatment can suppress the activation of the NLRP3 inflammasome triggered by the H1N1 virus.

Conclusion: Our findings demonstrate that FZJDD treatment can mitigate ALI caused by H1N1 virus and enhance the survival rate in mice, while it doesn't lower viral titers in the lungs. FZJDD achieves these outcomes by curbing excessive inflammation and blocking the activation of NLRP3 inflammasome.