scRNA-sequencing Reveals Bu-Shen-Yi-Qi formula (BSYQF) ameliorates airway remodeling via regulating imbalanced M1/M2 macrophage subtypes in chronic asthmatic mice.

ETHNOPHARMALOGICAL RELEVENCE: Airway remodeling is an end result of excessive tissue repair in chronic asthma, a heterogeneous disease with complex pathogenic features. Traditional Chinese Medicine (TCM) is known for its substantial history for asthma treatment and Bu-Shen-Yi-Qi Formula (BSYQF) has strong clinically and laboratory proven evidences as effective asthma controller. However, its underlying therapeutic mechanism remains unknown.

AIM OF THE STUDY: In present study, we aim to investigate how BSYQF exerts its therapeutic function in chronic asthmatic mice using single-cell RNA-sequencing.

MATERIALS AND

METHODS

We established a chronic asthma mouse model to evaluate the therapeutic effects of BSYQF, assessing airway inflammation, hyperresponsiveness, and remodeling through functional, histological, and molecular analyses. Single-cell RNA sequencing (scRNA-seq) and bulk transcriptomics were employed to investigate immune cell dynamics, significant modulation of macrophage polarization and key inflammatory pathways. Immunohistochemistry was applied to assess the transforming growth factor-β1 (TGF-β1) expression in lung tissues. Immunofluorescence analyses were conducted to assess airway remodeling, particularly myofibroblast expansion and the expression of key fibrosis-related markers, including Col1a1+α-SMA+ co-expression and osteopontin (OPN) protein.

RESULTS

Our result showed that BSYQF treatment, particularly 2.6 g/kg group, significantly improve airway hyperresponsiveness (AHR), mirrored by significantly reduced lung resistance and increased dynamic lung compliance in asthmatic mice (P < 0.05). Histopathological assessment reveals that BSYQF mitigated the airway inflammation and airway remodeling, reflected by markedly reduced goblet cell metaplasia and collagen deposition on subepithelial layer of the airway(P < 0.05). By single cell RNA sequencing technique on eight samples, we profiled over 60 000 mouse lung tissue cells, 21 distinct cell clusters and discovered a unique pattern of BSYQF-targeted M1 and M2 macrophage subtypes in chronic asthmatic mice. Significantly disturbed M1/M2 macrophage ratio was restored by BSYQF treatment and highly resemble to healthy mice status, compared to asthmatic condition (P < 0.05). Our qRT-PCR analysis validated the total of 23 asthmatic genes significantly regulated by BSYQF treatment in M1 and M2 macrophages (P < 0.05), which were highly associated with M2 Mediated airway remodeling. Immunofluorescence analyses showed BSYQF treatment markedly reduced the OPN protein expression on the airway and significantly suppressed the Col1a1+α-SMA+ co-expressed myofibroblast expansion on subepithelial airway layer, compared to asthmatic group (P < 0.05).

CONCLUSIONS

BSYQF significantly improved airway hyperresponsiveness, reduced airway inflammation and remodeling, and restored the disturbed M1/M2 macrophage balance in asthmatic mice. Mechanistically, BSYQF treatment regulated 23 asthma-related genes, suppressed OPN expression, and inhibited Col1a1+α-SMA+ myofibroblast expansion, highlighting its potential as a therapeutic intervention for chronic asthma.