Pancreatitis is an inflammatory disease with significant health and economic burdens that lacks an established therapy to prevent recurrent episodes or progression to chronic disease. Our long-term goal is to develop therapies for these diseases. The absence of effective therapies stems in part from our limited understanding about the pathophysiology of pancreatitis. The prevailing trypsin-dependent model holds that intracellular trypsinogen activation and failure of protective mechanisms responsible for trypsin inactivation are central to pathogenesis. Despite great effort the role of trypsin in pancreatitis remains speculative and incompletely defined. Recent studies suggest another mechanism for disease in patients with mutations in exocrine proteins, disruption of normal protein homeostasis and activation of ER overload pathways. As a result, expression of the mutant proteins is toxic to acinar cells and increases the risk for pancreatitis. With this model, the approach to developing new therapeutics would differ significantly from approaches based on the trypsin-dependent model. Herein, we address the hypothesis that carboxyl ester lipase (CEL) mutants associated with chronic pancreatitis activate adaptive cell signaling pathways and cell death pathways, initiate an inflammatory response and increase susceptibility of cells to injury by metabolic stress. The CEL mutations occur in the region containing a variable number of proline-rich tandem repeats (VNTR). Our preliminary data show that the DEL variants accumulate within the cells as aggregates and activate adaptive cell signaling pathways. We propose the following Specific Aims: 1) Determine the cellular pathways for the disposal of insoluble aggregates of CEL VNTR variants;2) Identify the adaptive cell signaling pathways activated by expression of CEL VNTR variants;3) Confirm our ex vivo results in mouse models that express CEL VNTR variants in the pancreas. The knowledge gained by the proposed studies will improve the overall understanding of pancreatic injury and provide insight into potential pharmacological interventions directed at a new therapeutic target, protein homeostasis.

Public Health Relevance

Pancreatitis is a common illness with significant health and economic burdens that lacks an effective therapy. This application investigates a novel mechanism by which mutations in a pancreatic digestive enzyme carboxyl ester lipase causes chronic pancreatitis. Knowledge about the mechanism of disease in this patient population has potential to open new avenues for the development of novel therapies.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Clinical, Integrative and Molecular Gastroenterology Study Section (CIMG)
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Serrano, Jose
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University of Pittsburgh
Schools of Medicine
United States
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El Jellas, Khadija; Johansson, Bente B; Fjeld, Karianne et al. (2018) The mucinous domain of pancreatic carboxyl-ester lipase (CEL) contains core 1/core 2 O-glycans that can be modified by ABO blood group determinants. J Biol Chem :
Xiao, Xunjun; Jones, Gabrielle; Sevilla, Wednesday A et al. (2016) A Carboxyl Ester Lipase (CEL) Mutant Causes Chronic Pancreatitis by Forming Intracellular Aggregates That Activate Apoptosis. J Biol Chem 291:23224-23236
Szabó, András; Xiao, Xunjun; Haughney, Margaret et al. (2015) A novel mutation in PNLIP causes pancreatic triglyceride lipase deficiency through protein misfolding. Biochim Biophys Acta 1852:1372-9
Singhi, Aatur D; Pai, Reetesh K; Kant, Jeffrey A et al. (2014) The histopathology of PRSS1 hereditary pancreatitis. Am J Surg Pathol 38:346-53