Milk fat globule-EGF factor 8/ATP-binding cassette subfamily E member 1 axis maintains mitophagy flux homeostasis to suppress ferroptosis in acute pancreatitis.

Abstract

BACKGROUND: Acute pancreatitis (AP) is a severe inflammatory disorder in which mitochondrial dysfunction and ferroptosis critically drive acinar cell injury. Our previous work suggested a protective role for exogenous milk fat globule-epidermal growth factor 8 (MFG-E8) in AP. This study aimed to elucidate the molecular mechanism by which endogenous MFG-E8 mitigates mitochondrial damage and ferroptosis during AP. METHODS: Two mouse models of AP were used for in vivo studies, while cerulein + lipopolysaccharide-induced mitophagy and ferroptosis in AR42J cells (cells of the rat exocrine pancreas) for in vitro studies. Mfge8 gene-defective mice and lentivirus were utilised to downregulate MFG-E8 expression in mice and overexpress MFG-E8 in cells, respectively. Dual gene modification was employed to overexpress MFG-E8 and simultaneously knockdown adenosine triphosphate (ATP)-binding cassette subfamily E member 1 (ABCE1) in vitro. One mitophagy agonist and two ferroptosis inhibitors were used in both in vitro and in vivo experiments. RESULTS: Endogenous MFG-E8 expression was downregulated in experimental AP. Genetic deletion of Mfge8 aggravated mitochondrial ultrastructural damage, impaired mitophagy flux and intensified ferroptosis, as evidenced by increased lipid peroxidation, Feaccumulation and depletion of glutathione peroxidase. Lentiviral overexpression of MFG-E8 in AR42J acinar cells restored mitophagy activity, preserved mitochondrial membrane potential and reduced oxidative stress. Mechanistically, co-immunoprecipitation confirmed that MFG-E8 directly interacts with ABCE1, a key mitophagy regulator. ABCE1 knockdown abolished the protective effects of MFG-E8 on mitochondrial function and ferroptosis suppression, indicating that the MFG-E8/ABCE1 axis is essential for maintaining mitophagy homeostasis. Pharmacological restoration of mitophagy or inhibition of ferroptosis rescued acinar cell injury caused by MFG-E8/ABCE1 dysregulation. In vivo, ferroptosis inhibition significantly improved pancreatic pathology and survival in Mfge8-deficient AP mice. CONCLUSION: Endogenous MFG-E8 protects against AP by binding ABCE1 to sustain mitophagy flux and inhibit ferroptosis. Targeting this axis offers a promising therapeutic strategy for mitigating pancreatic injury. KEY POINTS: Endogenous MFG-E8 is downregulated in acute pancreatitis (AP), disrupting MFG-E8/ABCE1 complex formation. MFG-E8/ABCE1 axis sustains Parkin-PINK1-mediated mitophagy to clear damaged mitochondria in pancreatic acinar cells. This axis suppresses ferroptosis by reducing Feaccumulation and lipid peroxidation, alleviating AP-related pancreatic injury.