Long-chain mono and polyunsaturated acylcarnitines and free fatty acids cause acinar cell ferroptosis and the development of pancreatitis

Background: Mitochondrial dysfunction, impaired energy metabolism, and oxidative damage play a significant role in the development of pancreatitis. Patients with elevated plasma triglycerides are at increased risk for development of severe acute pancreatitis. Consistent with this, acinar cells are uniquely sensitive to mono- and polyunsaturated non-esterified long-chain fatty acids (LCFAs) which cause oxidative damage. Carnitine palmitoyltransferase II (CPT2) is required for importing and thus metabolizing LCFA in mitochondria. Previously, we utilized acinar specific tamoxifen-inducible CPT2 acinarKO mice to probe the consequences of impaired LCFA metabolism revealing the development of spontaneous pancreatitis by 12 weeks post-tamoxifen. Hypothesis: As seen with LCFA toxicity, accumulation of long-chain acylcarnitines in CPT2 acinarKO mice triggers mitochondrial dysfunction and oxidative damage leading to the development of pancreatitis. Methods: Acinar cells were isolated from CPT2 floxed and CPT2 acinarKO mice to assess secretory function, ATP levels, and necrosis via lactate dehydrogenase release. Acinar cells from wild type (WT) mice were treated with mono and polyunsaturated BSA-conjugated LCFA and acylcarnitines to assess their toxic effects on acinar cells. Results: As anticipated, long-chain acylcarnitines were significantly elevated in CPT2 acinarKO pancreas whereas LCFAs were not. CCK-stimulated amylase secretion in isolated acini from CPT2 acinarKO mice was significantly reduced at 2 weeks post-tamoxifen and was severely impaired by 4 weeks accompanied by widespread necrosis. Treatment of WT acini with mono and polyunsaturated BSA-conjugated LCFAs and acylcarnitines at concentrations as low as 100 µM caused significant necrosis. However, saturated LCFAs did not induce necrosis. In WT acini, mono and polyunsaturated LCFAs and acylcarnitines caused necrosis as early as 5 and 30 min after treatment respectively and effects were blocked by the ferroptosis inhibitor, liproxstatin-1. Development of ferroptosis was dependent on elevated cellular Ca 2+ mediated by plasma membrane channels, Piezo1 and TRPV4, as inhibition of these channels with specific antagonists blocked ferroptosis. Human and rodent pancreas are known to contain unusually high levels of vitamin K form menaquinone-4 compared to other tissues. Treatment of acini with free radical trapping antioxidants including vitamin K forms, menaquinone-4 and phylloquinone, and vitamin E fully inhibited ferroptosis in the presence of monounsaturated BSA-conjugated LCFAs. Conclusion: These data indicate that non-esterified long-chain mono and polyunsaturated acylcarnitines and fatty acids rapidly trigger ferroptosis in acinar cells and the development of pancreatitis in vivo. Moreover, the uniquely high concentrations of pancreatic menaquinone-4 likely play a protective role in preventing ferroptosis and pancreatitis. Source of research funding: UW-Madison Comprehensive Diabetes Center Pilot Grant This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.