Huashi baidu granule alleviates inflammation and lung edema by suppressing the NLRP3/caspase-1/GSDMD-N pathway and promoting fluid clearance in a porcine reproductive and respiratory syndrome (PRRS) model

Abstract

Ethnopharmacological relevance: Huashi Baidu Granule (HSBDG), a traditional Chinese medicine (TCM), is used for treating coronavirus disease 2019 (COVID-19). Porcine reproductive and respiratory syndrome (PRRS) is considered the "COVID-19" for swine. According to the TCM theory, "dampness" is the main pathogenic factor in COVID-19 and PRRS, and "Huashi" means that this formula is good at removing "dampness". Studies have demonstrated that HSBDG's effect in COVID-19; but the mechanism of removing "dampness" remains elusive.

Aim of the study: We aimed to assess the effect of HSBDG on PRRS, and elucidate its potential mechanism in removing "dampness".

Materials and methods: We established a PRRS-virus (PRRSV)-infected Marc-145 cells model, and performed qRT-PCR, Western blot analysis, and indirect immunofluorescence assay to examine the anti-PRRSV effects of HSBDG in vitro. PRRSV-infected pig model was established and used to investigate HSBDG's effect in PRRS and explore underlying mechanisms in removing "dampness" using ELISA and immunohistochemistry assay methods.

Results: HSBDG exhibited anti-PRRSV activity and suppressed the viral replication and release phases. HSBDG treatment alleviated PRRS, lowered rectal temperature, reduced histopathological changes and viral load in lung tissues, and ameliorated organ lesions. Moreover, IL-1β, IL-6, IL-8, and TNF-α expressions were decreased in lung tissues. Mechanistically, HSBDG inhibited the NLRP3/Caspase-1/GSDMD-N pathway to reduce the inflammatory response and upregulated AQP1, AQP5, α-ENaC, and Na-K-ATPase expressions to promote lung fluid clearance.

Conclusion: HSBDG exerted anti-PRRSV effects and could attenuate PRRS. HSBDG potentially removes "dampness" by attenuating inflammation by suppressing the NLRP3/Caspase-1/GSDMD-N pathway and inhibiting pulmonary edema by upregulating the expression of AQP1, AQP5, α-ENaC, and Na-K-ATPase.

Keywords: COVID-19; Dampness; Huashi baidu granule; NLRP3 inflammasome; Porcine reproductive and respiratory syndrome; Pulmonary fluid clearance.