Integrative network toxicology and single-cell analysis implicates a potential TGFBR1-centered fibroblast remodeling axis in Benzo[a]pyrene-related atrial fibrillation

BACKGROUND: Benzo[a]pyrene (BaP), an air pollution-related polycyclic aromatic hydrocarbon, may intersect with molecular pathways relevant to atrial fibrillation (AF), but this relationship remains unclear. OBJECTIVES: To examine whether predicted BaP targets overlap with molecular and cellular remodeling features in human AF-related atrial datasets. METHODS: Five AF microarray datasets and one single-cell RNA sequencing (scRNA-seq) dataset were analyzed. Differential expression and weighted gene co-expression network analysis (WGCNA) defined AF-associated key genes directly observed from human AF transcriptomic datasets. BaP predicted targets were computationally obtained using ChEMBL, Similarity Ensemble Approach (SEA), and PharmMapper; their overlap with AF-associated key genes defined inferred BaP-AF candidate targets for Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Machine learning (ML) with SHapley Additive exPlanations (SHAP) prioritized hub genes. Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT), docking, and single-cell analyses assessed immune patterns, structural plausibility, and cellular context. RESULTS: Eighteen inferred BaP-AF candidate targets were identified by overlapping AF-associated key genes with BaP predicted targets, and these candidates were enriched in oxidative stress/inflammation and transforming growth factor-beta (TGF-β)-related remodeling pathways. Elastic Net yielded a final hub-gene signature (PPP3CA, ERBB4, PSAP, LAMP1, PPARA, HSP90AB1, TGFBR1, KCNA5). AF exhibited increased neutrophils and reduced M2 macrophages/T follicular helper (Tfh) cells. Single-cell analyses of AF-related human atrial tissue localized the hub genes to major cell populations and revealed AF-associated immune expansion and fibroblast-centered TGF-β signaling, dominated by TGFB1-(TGFBR1 + TGFBR2), rather than directly measuring BaP-induced single-cell remodeling.scTenifoldKnk-based TGFBR1 virtual knockout highlighted perturbations (ABCA8, CD9, IFI44L, BGN). CONCLUSION: These findings nominate a testable hypothesis that BaP-related target perturbations may intersect with TGFBR1-associated fibroblast remodeling in AF. Future studies should evaluate this hypothesis in exposure-relevant atrial cell models through controlled BaP exposure and TGFBR1 gain- or loss-of-function experiments, followed by in vivo validation of fibroblast activation and atrial remodeling.