Thursday, April 3, 2025
4/3/2025
Mechanisms of Hereditary Pancreatitis - PROJECT ABSTRACT Hereditary pancreatitis (HP) is an autosomal-dominant disease that causes recurrent acute pancreatitis (AP) and eventually progresses to chronic pancreatitis (CP). Unfortunately, HP patients also have a 44% cumulative risk of pancreatic cancer by age 70. No targeted intervention is currently available. Lack of animal models poses a big challenge to study the disease pathogenesis. Since the discovery of the gain-of-function mutant PRSS1R122H as a major cause of human HP nearly 26 years ago, many attempts to develop HP animal models have not been so successful. Recently, we were able to generate a novel mouse HP model by expressing both human PRSS1R122H and PRSS2. Heterozygous PRSS1R122H-PRSS2 HP mice are more sensitive to various stimuli in developing more severe AP than wild-type mice, while homozygous HP mice develop AP spontaneously at ~20 days old after birth which gradually progress to CP. During the studies of our new HP models, we observed that, in addition to the gain-of-function mutations, PRSS1 expression levels may also control the initiation of HP. Furthermore, a lower dose of cerulein (7.5 ug/kg), which activates less trypsin than high doses (100 ug/kg), paradoxically induced hemorrhagic AP, a more severe and often lethal form of AP. In contrast, high doses of cerulein only cause edematous AP. With these new findings, we hypothesize that the expression levels of trypsinogens and the location of active enzymes determine the spontaneous initiation and severity of HP. In Specific Aim 1, we will elucidate the mechanisms that upregulate the expression of pancreatic trypsinogens during the spontaneous initiation of HP. Various diets, hormones, and neurotransmitters, and intracellular signaling pathways in the regulations of PRSS1 expression and the initiation of HP will be studied using both pharmacological and genetic approaches. In Specific Aim 2, we will determine the role of active trypsin location in the development of hemorrhagic AP. We will characterize the histopathologic features including damage of pancreatic ducts and vasculature in the hemorrhagic models, determine the dose- dependent effects of cerulein and bombesin on trypsin activation and localization, define the molecular mechanisms through which trypsin damages the pancreatic duct and vasculature, and evaluate the therapeutic effects of inhibiting extracellular trypsin on hemorrhagic AP. Impact: This study will provide novel insights into the spontaneous initiation of HP and the pathogenesis of hemorrhagic AP. Some of the pathway inhibitors tested in this study are FDA-approved drugs for other disease conditions. Therefore, they can be readily translated to these diseases. Our study will also pave the ways for developing other novel effective preventive and therapeutic interventions.
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