Qingre-Huatan-Liqi formula attenuates FPM-induced lung injury via modulation of MAPK signaling and NETs formation.

BACKGROUND

Fine particulate matter (PM2.5, FPM) can induce and exacerbate chronic obstructive pulmonary disease (COPD) by triggering oxidative stress and multiple other pathogenic pathways. Our previous studies have demonstrated that Qingre-Huatan-Liqi formula (QRHTLQ) can improve the symptoms of patients with acute exacerbation of COPD (AECOPD), and animal experiments have suggested that QRHTLQ may prevent AECOPD via the EGFR-PI3K-AKT pathway. However, the protective effects and precise mechanisms by which QRHTLQ attenuates FPM-induced lung injury remain unclear.

METHODS

FPM-induced lung injury models were established by repeated intratracheal instillations of FPM every 3 days. Thirty rats were randomly divided into control, model, low-dose QRHTLQ, medium-dose QRHTLQ, high-dose QRHTLQ, and erythromycin groups. The therapeutic effects of QRHTLQ were evaluated by H&E staining and qPCR. LC-MS was used to identify blood-absorbed active constituents of QRHTLQ. Proteomics combined with network pharmacology was applied to identify key targets. The effects of QRHTLQ on these targets and related processes were validated by immunofluorescence, ELISA, and Western blot. Molecular docking and molecular dynamics simulations were performed to evaluate constituent-target binding and complex stability. In vitro, dHL-60 cells were stimulated with FPM to explore the intervention effects of QRHTLQ-containing serum and baicalin.

RESULTS

QRHTLQ alleviated FPM-triggered airway inflammation, downregulated pulmonary IL-6, IL-1β, TNF-α mRNA as well as ROS levels in bronchoalveolar lavage fluid (BALF). Six major blood-absorbed active constituents were identified using LC-MS. Integrated analyses suggested that QRHTLQ interferes with neutrophil extracellular traps (NETs) formation, with MAPK14 (P38α, the major isoform of P38 MAPK) identified as a core target. QRHTLQ decreased PAD4 in BALF and lung tissue, reduced NETs levels in lung tissue, and decreased the p-P38/P38 ratio. Baicalin exhibited the most favorable binding energy with MAPK14, and molecular dynamics simulations demonstrated that the baicalin-P38 MAPK14 complex was structurally stable. In vitro experiments confirmed that baicalin significantly reduced NETs release in dHL-60 cells and downregulated the p-P38/P38 ratio, thereby inhibiting MAPK14 activation.

CONCLUSION

QRHTLQ alleviates FPM-induced lung injury by modulating MAPK signaling and inhibiting NETs formation. Baicalin is likely a key blood-absorbed active component through which QRHTLQ exerts these protective effects.