A Chinese herb prescription "Fang-gan Decoction" protects against damage to lung and colon epithelial cells caused by the SARS-CoV-2 spike protein by regulating the TGF-β/Smad2/3 and NF-κB pathways.

Objective This study aimed to explore the effects and mechanisms of a traditional Chinese medicine (TCM) prescription, "Fang-gan Decoction" (FGD), in protecting against SARS-CoV-2 spike protein-induced lung and intestinal injuries in vitro and in vivo. Methods Female BALB/c mice and three cell lines pretreated with FGD were stimulated with recombinant SARS-CoV-2 spike protein (spike protein). Hematoxylin-eosin (HE) staining and pathologic scoring of tissues, cell permeability and viability, and ACE2 expression in the lung and colon were detected. ELISA was performed to detect the levels of inflammatory factors in serum and cell supernatant. The expression of NF-κB p65, p-NF-κB p65, p-IκBα, p-Smad2/3, TGF-β1, Caspase3, and Bcl-2 was evaluated by western blotting. Results FGD protected against the damage to the lung and colon caused by the spike protein in vivo and in vitro according to the pathologic score and cell permeability and viability (P<0.05). FGD up-regulated ACE2 expression, which was reduced by the spike protein in the lung and colon, significantly improved the deregulation of inflammatory markers caused by the spike protein, and regulated the activity of TGF-β/Smads and NF-κB signaling. Conclusion Traditional Chinese medicine has a certain protective effect on lung and intestinal tissue injury stimulated by the spike protein through possible regulatory functions of the NF-κB and TGF-β1/Smad pathways with tissue type specificity.