Azithromycin alleviates post-inflammatory wheezing in children by inhibiting SETD1B-mediated histone H3K4me3 methylation and macrophage polarization.

Abstract

Post-inflammatory wheezing (PIW) is a highly prevalent recurrent respiratory disease in children after acute pulmonary infection, characterized by persistent airway inflammatory imbalance. Azithromycin (AZM) exerts independent immunomodulatory functions beyond its antibacterial activity and can effectively improve pediatric PIW. However, it remains unclear whether AZM participates in the repair of PIW by regulating SET domain containing 1B (SETD1B)-mediated histone H3K4me3 methylation and modulating alveolar macrophage polarization. A total of 239 children with severe pneumonia were enrolled and divided into non-wheeze and PIW groups. Children with PIW received either routine symptomatic treatment or AZM intervention at a dose of 10 mg/kg/day for 5 consecutive days. Clinical prognoses, BALF cellular composition, inflammatory cytokine levels, and the expression of SETD1B and H3K4me3 were compared between groups. A lipopolysaccharide (LPS)-induced inflammatory model of rat alveolar macrophages, treated with the SETD1B-specific inhibitor WDR5-0103, was constructed to validate the core regulatory pathway. Children with PIW exhibited abnormal BALF cellular composition, upregulated pro-inflammatory factor IL-6, downregulated anti-inflammatory factor IL-10, and significantly increased expression of SETD1B and H3K4me3. AZM treatment effectively shortened wheezing duration and hospital stay and reduced medical costs. Furthermore, no significant differences in clinical efficacy were observed between mycoplasma-positive and mycoplasma-negative children treated with AZM, confirming that the therapeutic effect of AZM is independent of its anti-mycoplasma activity. In vitro, LPS induced SETD1B/H3K4me3 hypermethylation, inflammatory cytokine disturbance, and M1-type macrophage polarization. Either AZM or WDR5-0103 alone significantly reversed these LPS-induced abnormalities, and no additional synergistic efficacy was observed in the combined intervention group. AZM ameliorates PIW in children mainly through immunomodulation rather than antibacterial effects. It inhibits SETD1B-mediated H3K4me3 hypermethylation, corrects the imbalance of alveolar M1/M2 macrophage polarization, restores IL-6/IL-10 inflammatory homeostasis, and ultimately alleviates airway inflammatory injury and wheezing symptoms in children. Azithromycin (AZM) alleviates the release of inflammatory factors by regulating the H3K4me3 modification, thereby reducing post-inflammatory wheezing; The addition of new indications to the clinical application of AZM; Currently, there is no effective treatment for post-inflammatory wheezing. Although AZM is a common antimicrobial agent, this study demonstrates that it can alleviate non-specific inflammation in alveolar macrophages. Thus, AZM represents a promising therapeutic strategy.