Targeting DRP1Ser637 Phosphorylation Alleviates Acidic Bile Salt‐Induced NF‐κB Activation via Mitochondrial Protection

ABSTRACT Background and Aims The role of mitochondrial dynamics in gastroesophageal reflux disease (GERD) remains unclear. We investigated how bile acid‐induced mitochondrial dysfunction triggers mucosal inflammation and explored therapeutic targets. Methods Esophageal mucosal biopsies from 12 GERD patients and 12 controls underwent RNA‐seq. Human esophageal epithelial cells (HEEC) were treated with acidic bile salts (ABS, pH 5.5). Mitochondrial morphology (TOMM20 immunofluorescence), function (TMRM/MitoSOX staining), and DRP1 post‐translational modifications (non‐reducing Western blot) were analyzed. DRP1 knockdown (shRNA) and pharmacological inhibition (H‐89) were used to validate mechanisms. Results RNA‐seq revealed enrichment of mitochondrial fission and NF‐κB pathways in GERD patients. ABS exposure in HEEC increased DRP1 Ser637 phosphorylation, inducing mitochondrial fragmentation, membrane potential loss, and mtROS overproduction. Paradoxically, DRP1 knockdown exacerbated mitochondrial damage and amplified NF‐κB activation. H‐89 suppressed DRP1 Ser637 phosphorylation, restored mitochondrial function, and attenuated IL‐6/IL‐8 secretion. This effect was abolished in DRP1‐knockdown cells. Conclusions ABS‐induced DRP1 Ser637 phosphorylation drives mitochondrial fragmentation and mtROS‐dependent NF‐κB activation in GERD. DRP1‐mediated fission paradoxically limits mucosal damage by enabling quality control. Targeting DRP1 phosphorylation may offer a novel therapeutic strategy to break the mitochondrial‐inflammation vicious cycle in GERD.