Mechanisms of Paneth cell's driven mediators in the development of advanced chronic liver disease

The present application includes a project to develop a scientific collaboration between the host research laboratory (Laboratori di Ricerca Traslazionale, Ente Ospedaliero Cantonale, Bellinzona) and the laboratory from the visiting researcher (Hepatic and Intestinal Immunobiology Group, Miguel Hernandez University, Alicante, Spain). The visiting researcher (Oriol Juanola PhD) will carry out a project focused on the study of advanced chronic liver disease (ACLD) supervised by the applicant (Prof. Dr. med. Andrea De Gottardi) at the host research Institution.Background and rationale:Bacterial infections are a frequent complication and a leading cause of death in patients with advanced chronic liver disease (ACLD). Bacterial infections are mainly caused by Gram negative bacteria of enteric origin due to bacterial translocation (BT) i.e. the passage of viable bacteria or their derived products from the intestinal lumen to mesenteric lymph nodes and extraintestinal sites, such as bloodstream, liver and other organs. The inflammation induced by BT contributes to the progression of ACLD.Paneth cells (PCs) are intestinal epithelial cells belonging to the innate immune system that protect intestinal mucosa from colonization by pathogenic bacteria by secreting antimicrobial peptides. The direct role of PCs in controlling BT and hence the progression of ACLD and its complications remains unknown.Hypothesis: Paneth cells attenuate the progression of advanced chronic liver disease by preventing episodes of bacterial translocation.Objectives and specific aims:To examine the progression of advanced chronic liver disease and its complications in a mouse model in the presence or absence of PCs.Methods:We will study ACLD in mice devoid of Paneth cells (tamoxifen-treated Math1lox/lox VilCreERT2 transgenic mice) and in their respective control groups. Two different models of experimental liver disease will be used: 1) Ligation of the common bile duct (BDL) and sham surgery as control 2) Injection of carbon tetrachloride intraperitoneally (CCl4) or olive oil as control.Liver disease will be evaluated by histological, molecular and biochemical parameters related to liver fibrosis, hepatic damage and inflammation. Hemodynamic measurements will also be performed to assess the evolution of portal pressure and bacterial translocation will be evaluated in serum from portal vein, mesenteric lymph nodes, spleen and liver homogenized samples. Laparotomies will be performed under anesthesia with isoflurane and whole blood from the portal vein, liver, spleen, mesenteric lymph nodes, small intestine, colon and fecal content from cecum will be collected.Expected results:In the absence of PCs, we expect increased intestinal bacterial overgrowth and translocation of bacteria and their products to the liver and extraintestinal sites that will stimulate local and systemic inflammatory responses and favor the progression of hepatic damage and fibrosis. Impact:This scientific exchange will allow to start a collaboration between our research groups. We intend to present the findings of experiments at gastroenterology/hepatology meetings, to publish the results of this work in peer-reviewed scientific journals and to inform a broader audience about this project. The impact of this work will not be limited to chronic liver disease, because the role of PCs in the digestive system is well characterized particularly in inflammatory bowel disease (IBD). Therefore, findings of this project will be of interest for a number of investigators in other disciplines.