Synergistic Effects of Erythromycin and Budesonide on the Mitigation of Tracheal Stenosis Associated With Macrophage Phenotype Alteration and HDAC2 Upregulation

OBJECTIVE: We investigated the therapeutic effects of combined erythromycin and budesonide treatment on tracheal stenosis (TS) and the associated changes in macrophage-related markers and HDAC2 expression. METHODS: A rabbit model of TS was established by mechanical scraping of the tracheal inner wall, and the animals were then treated with erythromycin, budesonide, or their combination. Treatment effects were evaluated through histological analysis. We quantified the mRNA expression of M1 and M2 macrophage markers using quantitative PCR and assessed the protein expression of histone deacetylase 2 (HDAC2) by western blotting. RAW264.7 cells were stimulated with lipopolysaccharide or interleukin-4, and macrophage phenotypic changes after erythromycin and budesonide treatment were assessed by flow cytometry. M1/M2 macrophages were co-cultured with fibroblasts, and alpha smooth muscle actin (α-SMA) expression was detected by immunofluorescence. RESULTS: The rabbit TS model exhibited TS characterized by significant thickening of the tracheal mucosa and submucosa. These histological changes were ameliorated in the treatment groups, with the greatest improvement observed in the combination therapy group. The mRNA expression levels of iNOS, CD206, CD163, and Arg1, as well as the protein expression of HDAC2, were elevated in treated groups. In vitro, erythromycin combined with budesonide altered macrophage phenotypic distribution, with the M2/M1 ratio shifting toward 1.0. Additionally, fibroblast α-SMA expression varied according to macrophage phenotype in the co-culture system. CONCLUSION: Erythromycin combined with budesonide effectively ameliorated injury-induced TS and was associated with changes in macrophage-related markers and increased HDAC2 expression.