Perfluorooctanoic acid-associated complement factor B upregulation and atrial fibrillation-related molecular alterations: integrated network toxicology, Mendelian randomization, molecular dynamics, and HL-1 cell analyses.

BACKGROUND: Perfluorooctanoic acid (PFOA) is a persistent environmental pollutant associated with cardiovascular dysfunction, but the molecular links between PFOA exposure and atrial fibrillation (AF) remain unclear. We aimed to prioritize a candidate mediator connecting PFOA with AF and examine its associated molecular effects in atrial cardiomyocytes. METHODS: PFOA-associated or computationally predicted genes from CTD, STITCH, and SwissTargetPrediction were integrated with AF-associated genes. Complement factor B (CFB) was evaluated using exploratory Mendelian randomization, public single-cell analysis, protein-interaction and enrichment analyses, molecular docking, a single 100-ns molecular dynamics trajectory, and HL-1 cell experiments. Cells were exposed to 25 μM PFOA for 48 h with or without CFB silencing, followed by qRT-PCR, Western blotting, immunofluorescence, and CCK-8 assays. RESULTS: CFB was the only shared candidate between the integrated PFOA-related target set and the filtered AF-associated gene set. Genetically predicted plasma CFB levels were positively associated with AF risk (odds ratio = 1.109, 95% confidence interval: 1.021-1.205; FDR-adjusted P = 0.015). Public single-cell data showed preferential basal CFB expression in cardiac fibroblast and stromal populations, with lower expression in cardiomyocytes. The predicted PFOA-CFB pose remained within the selected pocket during the sampled trajectory. In HL-1 cells, PFOA increased CFB mRNA and protein abundance, decreased CACNA1C transcript levels without significantly changing CACNA1C protein abundance, and increased KCNJ2 and NPPA expression. CFB silencing attenuated the PFOA-associated increases in KCNJ2 and NPPA, whereas CACNA1C showed no corresponding rescue pattern. CFB immunoreactivity was detected within cTnT-positive, PFOA-exposed HL-1 cells. CONCLUSION: These findings prioritize CFB as a candidate molecule potentially associated with PFOA exposure and AF-related molecular alterations. They do not establish direct PFOA-CFB binding, functional complement activation, causality, electrical remodeling, or a functional AF phenotype.