Trypsin activity governs increased susceptibility to pancreatitis in mice expressing human [PRSS1.sup.R122H]

Currently, an effective targeted therapy for pancreatitis is lacking. Hereditary pancreatitis (HP) is a heritable, autosomal-dominant disorder with recurrent acute pancreatitis (AP) progressing to chronic pancreatitis (CP) and a markedly increased risk of pancreatic cancer. In 1996, mutations in PRSS1 were linked to the development of HP. Here, we developed a mouse model by inserting a full-length human [PRSS1.sup.R122H] gene, the most commonly mutated gene in human HP, into mice. Expression of [PRSS1.sup.R122H] protein in the pancreas markedly increased stress signaling pathways and exacerbated AP. After the attack of AP, all [PRSS1.sup.R122H] mice had disease progression to CP, with similar histologic features as those observed in human HP. By comparing [PRSS1.sup.R122H] mice with [PRSS1.sup.WT] mice, as well as enzymatically inactivated Dead-[PRSS1.sup.R122H] mice, we unraveled that increased trypsin activity is the mechanism for R122H mutation to sensitize mice to the development of pancreatitis. We further discovered that trypsin inhibition, in combination with anticoagulation therapy, synergistically prevented progression to CP in [PRSS1.sup.R122H] mice. These animal models help us better understand the complex nature of this disease and provide powerful tools for developing and testing novel therapeutics for human pancreatitis.