Effects of oren on IL-6 production in cultured human airway epithelial cells stimulated with the SARS-CoV-2 envelope protein.

Abstract

Purpose: This study aimed to establish an in vitro model using Calu-3 human lung adenocarcinoma cells stimulated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope (E) protein to evaluate the anti-inflammatory effects of oren (Coptis rhizome), a traditional Kampo medicine.

Methods: Calu-3 cells were treated with the E protein in the presence or absence of oren extract. Interleukin (IL)-6 production was quantified using ELISA. Reporter gene assays were used to measure IL-6 promoter activity and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. The involvement of Toll-like receptor (TLR) signaling pathways was also investigated.

Results: The E protein increased IL-6 production in Calu-3 cells by approximately fourfold; however, co-treatment with oren significantly suppressed this effect (P < 0.001). In 293-TLR2/CD14 cells, the E protein enhanced IL-6 promoter activity by approximately 2.8-fold, but this activation was significantly inhibited by oren (P < 0.001). The E protein also increased NF-κB-dependent transcriptional activity by approximately fourfold in 293-TLR2/CD14 and 2.4-fold in Calu-3 cells, and these effects were significantly suppressed by oren (P < 0.001).

Conclusion: Oren significantly suppressed SARS-CoV-2 E protein-induced IL-6 production and NF-κB pathway activation, with effects extending to the transcriptional level through inhibition of IL-6 promoter activity.