Fu Tu Sheng Jin Rehabilitation Formula Mitigate Airway Inflammation, Mucus Secretion and Immune Dysfunction Induced by SARS-CoV-2 Spike Protein.

OBJECTIVE

To evaluate the effects of Fu Tu Sheng Jin Rehabilitation Formula (FTSJRF) on airway inflammation, mucus secretion, and immunoreaction in a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein-induced mouse model.

METHODS

Forty-two mice were randomly divided into seven groups: normal, D1, D3, D10, D10H, D10M and D10L, according to the days of modeling and different dosages of FTSJRF. D1, D3, D10, D10H, D10M and D10L group mice were intratracheally administered with 15 µg SARS-CoV-2 spike protein; mice in the D10H, D10M, and D10L groups were intragastrically administered FTSJRF (46, 23 and 11.5 g/kg, respectively). Observe the pathological changes in lung tissues, expression of inflammatory factors, and mucins in different groups of mice using HE and PAS staining methods, as well as ELISA and RT-qPCR. Flow cytometry was used to detect T helper 17 (Th17)/regulatory T (Treg) cells and T helper 1(Th1)/T helper 2 (Th2) lymphocyte ratios and the proportions of conventional myeloid dendritic cells (cDCs), plasma cell-like DCs, CD80 and CD86 cells in mouse spleens.

RESULTS

HE and PAS staining showed that, compared to that in the normal group, the lung tissue of the D1 group mice showed a significant inflammatory damage response, whereas the D3 and D10 groups showed a gradual recovery trend. Groups D1 and D3 showed mild mucus secretion, whereas the D10 group had excessive mucus secretion. The D10 group of mice displayed increased levels of IL-4, TNF-α, IL-33 and mucin genes such as MUC1, MUC4, etc, and FTSJRF inhibited the expression of these molecules, mucus secretion and lung damage in SARS-CoV-2 spike protein-induced mouse model. Flow cytometry results showed a decrease in the number of cDCs and an abnormal recovery of DC mature cells in the D10 group. FTSJRF increased the number of cDCs and promoted DC maturation. A higher Th17/Treg ratio was observed in the D3 and D10 groups than in the normal group, whereas this ratio decreases under the effect of FTSJRF. D10 had significantly lower Th1/Th2 ratio than normal, D1 and D3 groups, and high doses of FTSJRF increased it.

CONCLUSION

FTSJRF mitigates airway inflammation and mucus secretion induced by SARS-CoV-2 spike protein. Additionally, FTSJRF regulates immune functions by promoting DC maturation and Th17/Treg and Th1/Th2 cell homeostasis.