Huaxian formula prevents the progression of radiation-induced pulmonary fibrosis by inhibiting the pro-fibrotic effects of macrophages

Ethnopharmacological relevance

The Huaxian formula (HXF), a traditional Chinese medicine (TCM) remedy, specifically targets the pathological factors of “heat toxicity” and “phlegm stasis” induced by radiation in radiation-induced pulmonary fibrosis (RIPF). It works by clearing heat and invigorating the blood, addressing these key factors in the development of RIPF.

Aim of the study

The HXF has demonstrated potential in preventing RIPF, although its underlying mechanisms remain unclear. This study aims to investigate the efficacy, molecular targets, and mechanisms of action of HXF.

Materials and methods

The major constituents of the HXF were identified by ultra performance liquid chromatography and tandem mass spectrometry (UPLC-MS). C57BL/6j mice were divided into four groups: control (Ctrl), HXF alone (HXF), 17Gy-irradiation alone (IR), and irradiation plus HXF (IR + HXF). Lung damage and fibrosis were assessed by histopathological staining, and the flow cytometry and immunohistochemistry (IHC) were used to detect the macrophages phenotype of lung tissues in vivo at 16 weeks post-irradiation. Transcriptomic sequencing and bioinformatics analyses identified key genes modulated by HXF. In vitro assays included flow cytometry, western bolt, and quantitative PCR (qPCR) explored the impact of HXF on macrophage polarization and fibrotic activity, while co-culture experiments of the macrophage conditional medium and mouse embryo fibroblast NIH/3T3 investigated macrophage-fibroblast interactions.

Results

20 major constituents of HXF were identified. And the in vivo results revealed significant lung damage and fibrosis in the IR group, which were notably mitigated in the IR + HXF group. And HXF has been shown to significantly inhibit the infiltration of M2-type macrophages in lung tissues. Transcriptomic analysis identified differentially expressed genes (DEGs) such as Arg1, Mmp10, and Fgf23. Bioinformatics enrichment analysis indicated that these DEGs are involved in pathways related to the inhibition of extracellular matrix formation and inflammation. In vitro, HXF-containing serum reduced M2-type macrophage polarization and decreased the secretion of Arginase1 and TGFβ1. Conditioned medium from HXF-treated macrophages suppressed fibroblast activation.

Conclusion

HXF's preventive effects on RIPF involve multiple targets and mechanisms, including the modulation of Arg1, Mmp10, and Fgf23 expression. By inhibiting the pro-fibrotic capacity of macrophages, HXF suppresses fibroblast activation and collagen production, thereby alleviating lung fibrosis. These findings underscore the potential of HXF as a preventive strategy in managing RIPF.