INITIATION AND SEVERITY OF EXPERIMENTAL PANCREATITIS ARE MODIFIED BY PHOSPHATE

Proper mitochondrial function and adequate cellular ATP are necessary for normal pancreatic protein synthesis and sorting, maintenance of intracellular organelles and enzyme secretion. Inorganic phosphate is required for generating ATP and its limited availability may lead to reduced ATP production causing impaired Ca2 thorn handling, defective autophagy, zymogen activation, and necrosis, which are all features of acute pancreatitis. We hypothesized that reduced dietary phosphate leads to hypophosphatemia and exacerbates pancreatitis severity of multiple causes. We observed that mice fed a low-phosphate diet before the induction of pancreatitis by either repeated caerulein administration or pancreatic duct injection as a model of pressure-induced pancreatitis developed hypophosphatemia and exhibited more severe pancreatitis than normophosphatemic mice. Pancreatitis severity was significantly reduced in mice treated with phosphate. In vitro modeling of secretagogue- and pressure-induced pancreatic injury was evaluated in isolated pancreatic acini using cholecystokinin and the mechanoreceptor Piezo1 agonist, Yoda1, under low and normal phosphate conditions. Isolated pancreatic acini were more sensitive to cholecystokinin- and Yoda1induced acinar cell damage and mitochondrial dysfunction under low-phosphate conditions and improved following phosphate supplementation. Importantly, even mice on a normal phosphate diet exhibited less severe pancreatitis when treated with supplemental phosphate. Thus, hypophosphatemia sensitizes animals to pancreatitis and phosphate supplementation reduces pancreatitis severity. These appear to be direct effects of phosphate on acinar cells through restoration of mitochondrial function. We propose that phosphate administration may be useful in the treatment of acute pancreatitis. NEW & NOTEWORTHY Impaired ATP synthesis disrupts acinar cell homeostasis and is an early step in pancreatitis. We report that reduced phosphate availability impairs mitochondrial function and worsens pancreatic injury. Phosphate supplementation improves mitochondrial function and protects against experimental pancreatitis, raising the possibility that phosphate supplementation may be useful in treating pancreatitis.