Sichen (SC) formula, a well-known Tibetan medicinal preparation, has been traditionally applied to treat respiratory ailments in Tibet due to its anti-inflammatory potential. This study aimed to systematically investigate its anti-inflammatory effects and the molecular mechanisms involved.The chemical profile of SC was analyzed using HPLC. An acute lung injury (ALI) model in mice was established by intratracheal administration of lipopolysaccharide (LPS), with subsequent collection of bronchoalveolar lavage fluid (BALF) and lung tissues for analysis. RAW264.7 macrophages were also exposed to LPS in vitro. Inflammatory cytokine levels were measured by ELISA, while protein expression and localization were evaluated using Western blot, immunohistochemistry, and immunofluorescence for NF-κB, AP-1, and IRF3.In LPS-induced ALI mice, SC significantly reduced BALF levels of TNF-α, IL-6, IL-1β, MCP-1, MIP-1α, and RANTES, and limited macrophage infiltration. SC treatment also decreased the expression of CD68, TLR4, and phosphorylated p65 in lung tissues. In RAW264.7 macrophages, SC up to 400 μg/mL did not affect viability but dose-dependently suppressed inflammatory mediators including nitric oxide, prostaglandin E2, and multiple cytokines. SC inhibited the activation of key signaling proteins, including iNOS, COX-2, p-p38, p-JNK, p-ERK, p-TBK1, p-IKKα/β, p-IκB, p-p65, p-c-Jun, and p-IRF3, and blocked nuclear translocation of NF-κB, AP-1, and IRF3.SC exerts potent anti-inflammatory effects in both LPS-induced ALI mice and LPS-stimulated macrophages, likely through modulation of the TLR4 signaling pathway. These findings provide experimental evidence supporting the therapeutic application of SC in respiratory inflammatory disorders.
