Cytokine Storm in Acute Viral Respiratory Injury: Role of Qing-Fei-Pai-Du Decoction in Inhibiting the Infiltration of Neutrophils and Macrophages through TAK1/IKK/NF-[Formula: see text]B Pathway.

COVID-19 has posed unprecedented challenges to global public health since its outbreak. The Qing-Fei-Pai-Du decoction (QFPDD), a Chinese herbal formula, is widely used in China to treat COVID-19. It exerts an impressive therapeutic effect by inhibiting the progression from mild to critical disease in the clinic. However, the underlying mechanisms remain obscure. Both SARS-CoV-2 and influenza viruses elicit similar pathological processes. Their severe manifestations, such as acute respiratory distress syndrome (ARDS), multiple organ failure (MOF), and viral sepsis, are correlated with the cytokine storm. During flu infection, QFPDD reduced the lung indexes and downregulated the expressions of MCP-1, TNF-[Formula: see text], IL-6, and IL-1[Formula: see text] in broncho-alveolar lavage fluid (BALF), lungs, or serum samples. The infiltration of neutrophils and inflammatory monocytes in lungs was decreased dramatically, and lung injury was ameliorated in QFPDD-treated flu mice. In addition, QFPDD also inhibited the polarization of M1 macrophages and downregulated the expressions of IL-6, TNF-[Formula: see text], MIP-2, MCP-1, and IP-10, while also upregulating the IL-10 expression. The phosphorylated TAK1, IKK[Formula: see text]/[Formula: see text], and I[Formula: see text]B[Formula: see text] and the subsequent translocation of phosphorylated p65 into the nuclei were decreased by QFPDD. These findings indicated that QFPDD reduces the intensity of the cytokine storm by inhibiting the NF-[Formula: see text]B signaling pathway during severe viral infections, thereby providing theoretical and experimental support for its clinical application in respiratory viral infections.

[Reduning Injection protects flu-infected mice by inhibiting infiltration of inflammatory cells in lung and down-regulating cytokine storm].

This study aimed to explore the protective effect of Reduning Injection(RDN) on mice infected by influenza virus A/PR/8(PR8) and its immune regulatory roles during viral infection. In in vivo experiments, female C57 BL/6 mice were randomly divided into phosphate buffered saline(PBS) group, PR8-infected group, oseltamivir treatment group(OSV) and RDN treatment group. After 2 h of PR8 infection, mice in the oseltamivir group were gavaged with oseltamivir 30 mg·kg~(-1), and those in the RDN treatment group were injected intraperitoneally with RDN 1.5 mL·kg~(-1)once per day for seven consecutive days. The body weight of mice in each group was recorded at the same time every morning for 16 consecutive days. The line chart of body weight change was created to analyze the protective effect of RDN on flu-infected mice. The relative mRNA expression of different cytokines(IL-6, TNF-α, MCP-1, IL-1ß, MIP-2, IP-10 and IL-10) in lung samples of flu-infected mice was detected by PCR. Flow cytometry was utilized to analyze the composition of immune cells of mouse BALF samples on day 5 after infection. Mouse macrophage cell line RAW264.7 was planted and treated by different concentrations of RDN(150, 300, 600 µg·mL~(-1)) for 24 h or 48 h, and cell proliferation was detected by CCK-8 assay. RAW264.7 cells and mouse primary peritoneal macrophages were stimulated with synthetic single stranded RNA(R837), which elicited the inflammatory response by mimicking the infection of single-stranded RNA viruses. The expression of cytokines and chemokines in the supernatants of above culture system was detected by ELISA and qPCR. On days 4, 5, 6, 7 and 15 after infection, the body weight loss of mice in the RDN treatment group was alleviated compared with that of PR8-infected mice(P<0.05). RDN treatment obviously reduced lung index and the production of IL-6, TNF-α, MCP-1 and MIP-2 in lung tissues of flu-infected mice(P<0.05). The proportions of macrophages, neutrophils and T cells in mouse BALF samples were analyzed by flow cytometry, and compared with PR8-infected mice, RDN decreased the proportion of macrophages in BALF of flu-infected mice(P<0.05), and the proportion of T cells was recovered dramatically(P<0.001). In CCK-8 assay, the concentrations of RDN(150, 300, 600 µg·mL~(-1)) failed to cause cytotoxicity to RAW264.7 cells. In addition, RDN lowered the expression of inflammatory cytokines such as IL-6, TNF-α,MCP-1, IL-1ß, RANTES, and IP-10 and even anti-inflammatory cytokine IL-10 in R837-induced macrophages. RDN reduced the infiltration of inflammatory macrophages and the production of excessive inflammatory cytokines, alleviated the body weight loss of flu-infected mice. What's more, RDN restored the depletion of T cells, which might prevent secondary infection and deteriorative progression of the disease. Taken together, RDN may inhibit cytokine production and therefore down-regulate cytokine storm during the infection of influenza virus.