Xuelian injection ameliorates complete Freund's adjuvant-induced acute arthritis in rats via inhibiting TLR4 signaling

Background

Xuelian injection (XI), a classic preparation extracted from Saussureae Involucratae Herba, has been clinically used to manage rheumatoid arthritis (RA) for nearly twenty years in China. However, the underlying anti-RA mechanism of XI remains unclear. In this study, complete Freund's adjuvant (CFA)-induced acute arthritic model was used to examine the anti-RA effects of XI in vivo. The molecular mechanisms of this action were further investigated using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

Methods

XI and XI freeze dried powder were characterized by UPLC analysis. CD68 and TLR4 expression in the ankle joints was measured by immunohistochemistry. The secretion of inflammatory mediators was detected by ELISA. The expression levels of TLR4 involved components were measured by Western blotting. The localization of transcription factors was measured by immunofluorescence assay.

Results

XI treatment ameliorated arthritic symptoms induced by CFA in the ankle joints of rats. The serum levels of inflammatory mediators, including TNF-α, MCP-1, and Rantes were decreased by XI treatment. The elevation of CD68 and TLR4 levels in ankle joints caused by CFA was suppressed by XI treatment. Moreover, XI treatment inhibited the secretion of nitric oxide and prostaglandin E2 in LPS-treated RAW264.7 macrophages. The expression of their enzymes iNOS and COX-2 was also decreased after XI treatment. The production of inflammatory mediators, including TNF-α, IL-6, IL-1β, MCP-1, MIP-1α, and Rantes was reduced by XI treatment in LPS-stimulated RAW264.7 cells. The phosphorylation of p38, JNK, ERK, TBK1, IKKα/β, IκB, p65, c-Jun, and IRF3 was reduced after XI treatment. Additionally, the expression levels of nuclear proteins of p65, c-Jun, and IRF3 were inhibited by XI treatment.

Conclusions

Taken together, XI possesses potential anti-RA effect and the underlying mechanism may be closely associated with the inhibition of TLR4 signaling. Our findings provide further pharmacological justifications for the clinical use of XI in RA treatment.

Sichen Formula Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Blocking the TLR4 Signaling Pathways

Purpose

Sichen (SC) formula is a classic prescription of Tibetan medicine. Due to its potential anti-inflammatory effect, the SC formula has been clinically used to treat respiratory diseases for many years in the Chinese Tibet region. The present study aimed to investigate the anti-inflammatory effect of SC and explore the underlying mechanisms.

Methods

SC formula was characterized by HPLC analysis. The acute lung injury (ALI) mouse model was induced by direct intratracheal lipopolysaccharide (LPS) instillation, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. Meanwhile, RAW264.7 macrophages were stimulated by LPS. The contents of inflammatory mediators in the culture medium were determined by ELISA. Protein levels were determined by immunohistochemical staining or Western blotting. Nuclear localization of NF-κB, AP-1, and IRF3 was performed using immunofluorescence and Western blotting.

Results

In the LPS-induced ALI mouse model, SC treatment suppressed the secretion of inflammatory mediators (TNF-α, IL-6, IL-1β, MCP-1, MIP-1α, and RANTES) in BALF. SC treatment hindered the recruitment of macrophages. SC treatment also inhibited the expression of CD68, p-p65, and TLR4 in the lung tissue. In the LPS-exposed RAW264.7 cells, the cell viability was not changed up to 400 μg/mL of SC. SC concentration-dependently suppressed the production of nitric oxide, prostaglandin E2, TNF-α, IL-6, MCP-1, MIP-1α, and RANTES in LPS-challenged RAW264.7 cells. The expression levels of iNOS, COX-2, p-p38, p-JNK, p-ERK, p-TBK1, p-IKKα/β, p-IκB, p-p65, p-c-Jun, and p-IRF3 were decreased after SC treatment. Moreover, the nuclear translocation of p65, c-Jun, and IRF3 was also blocked by SC treatment.

Conclusion

SC treatment inhibited the inflammatory responses in LPS-induced ALI mouse model/RAW264.7 macrophages. The underlying mechanism of this action may be closely associated with the suppression of TLR4 signaling pathways. These research findings provide further pharmacological justifications for the medicinal use of SC in the management of respiratory diseases.