The therapeutic promises of Lianhuaqingke in the mice model of coronavirus pneumonia (HCoV-229E and SARS-CoV-2)

Background Lianhuaqingke (LHQK) has been approved for the treatment of acute tracheobronchitis and exerts a broad-spectrum antiviral effect in our previous study. Methods Acute pneumonia caused by HCoV-229E was modeled in BALB/c mice. The anti-viral effect of LHQK was assessed by measuring the lung index and virus titer of lung tissues. The expression levels of pro-inflammatory cytokines in lung tissues and peripheral blood were measured by ELISA. The morphological changes of lung tissues were observed by H&E staining. The subsets of Th cells were assayed by the flow cytometry, including Th0, Th1, Th2, Treg, and Th17. The expression level of MUC5AC in 16HBE cells treated with TNF[alpha] was measured by ELISA. Immunofluorescence staining for [beta]-IV tubulin was used to identify the airway epithelial ciliary in the condition-cultured RTE cells treated with TNF[alpha]. The direct antiviral effect of LHQK was assessed in vitro in Vero E6 infected by SARS-CoV-2, validated in vivo in the COVID-19 model of hACE2 transgenic mouse by detecting the lung index, the SARS-CoV-2 virus load, and the morphological changes of lung tissues. Results LHQK reduced the weight loss and the lung index by inhibiting the HCoV-229E replication and reducing the expression of pro-inflammatory cytokines in lung tissues. An assay for the Th cell subsets in peripheral blood revealed that LHQK could reduce the ratio of Th1/Th2 and increase the Treg/Th17 ratio in a dose-dependent way, which indicated that LHQK could coordinate the Th-mediated immune responses against the virus. In in vitro injury by TNF[alpha], LHQK inhibited MUC5AC expression in 16HBE cells and increased the number of [beta]-IV tubulin positive staining cells in the condition-cultured RTE cells. In the SARS-CoV-2-infected mice, LHQK could reduce weight loss, inhibit viral replication, and alleviate lung tissue damage. Conclusions Our results demonstrate that LHQK exerts therapeutic effects on pneumonia caused by HCoVs (HCoV-229E and SARS-CoV-2) in mice, and that the anti-HCoV effects might depend on its immunomodulatory capacities. All these results suggest that LHQK serves as a potential adjuvant for anti-HCoV therapies. Keywords: Lianhuaqingke (LHQK), Human coronaviruses (HCoVs), Immunomodulation, Anti-HCoVs therapy