Muscarinic 3 Receptor in Pancreatitis Pathogenesis and Therapy
Abstract
The proposed research project addresses the Fiscal Year 2018 Peer Reviewed Medical Research Program Topic Area of Pancreatitis. Pancreatitis is an inflammatory disease of the pancreas that is painful and often lethal in severe cases. Currently neither effective preventive nor targeted therapeutic intervention exists. For studying the disease, scientists often use caerulein, a polypeptide, to stimulate the cholecystokinin (CCK) receptor on pancreas cells in mice. However, in humans, pancreas cells do not have CCK receptors (CCKR). Therefore, the relevance of the CCKR stimulation model to human pancreatitis is questionable. Instead, muscarinic receptor 3 (M3R) is highly expressed on both mouse and human pancreas cells. Therefore, hyperstimulation of M3R on pancreas cells is expected to be more relevant to human pancreatitis. However, the potential role of M3R in the initiation of pancreatitis has never been directly assessed in vivo because muscarinic receptor subtypes are widely expressed in the body. Use of non-specific agonists will cause many side effects. To address this gap in knowledge, we developed a genetic mouse model with the expression of a mutant form of human M3 receptor (hM3R) in mice. This model allows us to specifically activate the M3R on pancreatic acinar cells without affecting other M receptors. In this proposal, we will test our central hypothesis that M3R hyperactivation induces pancreatitis through premature intra-acinar trypsinogen activation and increased proinflammatory NF-kappaB pathways and targeting M3R will be beneficial to pancreatitis therapy. Specific Aim 1: Characterize hM3R-induced acute pancreatitis and determine whether AP will progress to chronic pancreatitis. In this aim, we will examine and compare CCK, carbachol (a muscarinic receptor agonist) and CNO (activating transgenic hM3R)-induced amylase secretion and cell damage in isolated pancreatic acinar cells. We will also determine the minimum doses of CNO needed to cause AP, characterize the severity of AP, and examine whether the M3R-elicited AP will progress to CP and develop precancerous lesions. Specific Aim 2: Identify the signaling pathways of hM3R during the initiation of pancreatitis and validate these pathways in commercially available primary human pancreatic acinar cells. First, we will examine whether several AP-related common pathways are activated in M3R-initiated pancreatitis. Second, we will use differential phosphoproteomics and Next Generation RNA-seq to discover novel pathways that are common in CCK-, carbachol- and CNO-stimulated acinar cells and also that are unique to M3R. Third, we validate these pathways in commercially available primary human pancreatic acinar cells. Specific Aim 3: Test whether the M3R-specific antagonist Darifenacin (Enablex®) will ameliorate pancreatitis. Darifenacin works by blocking the M3 muscarinic acetylcholine receptor (M3R). It is a U.S. Food and Drug Administration (FDA)-approved drug for treating symptoms of overactive bladder, such as frequent or urgent urination, and incontinence. In this study, we will test its efficacy in reducing the severity of pancreatitis in several mouse models of pancreatitis including alcohol- and high-fat diet-induced pancreatitis. This study has high military relevance because military personnel experience greater risk of pancreatitis due to chemical warfare agents, scorpion sting, trauma, and increased exposure to alcohol and smoking. Completion of the proposed studies is expected to establish a novel animal model of pancreatitis that is more relevant to the human disease than the current “standard” model. This model can provide us a powerful tool for developing and testing new interventions. It is also hopeful that a novel targeted therapy will be identified for pancreatitis. If successful, we will run a clinical trial because the M3R antagonist (Enablex®) is already an FDA-approved drug for other conditions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 19, 2019
- Source ID
- W81XWH1910081
Entities
People
- Baoan Ji
Organizations
- Mayo Clinic Hospital – Jacksonville
- United States Army