With mortality rates of both men and women increasing considerably over the last decade from liver disease, along with the number of patients on the active liver transplant list in the UK on the increase, new diagnostic tools would be welcomed by hepatologists. This trend is possibly mirroring the increase in patient numbers with alcoholic liver disease (ALD), and non-alcoholic fatty liver disease (NALFD). The aim of this project was to find a suitable biomarker for the early detection of liver disease. One such biomarker that was proposed was insulin-like growth factor-binding protein-5 (IGFBP-5). IGFBP-5 is known to be involved in the wound healing response in epithelial tissues, and its expression is switched on in fibrosis of the lung. IGFBP-5 induces epithelial cell senescence, an important component in the failure to resolve healing which results in a compensatory fibrotic response. IGFBP-5 has also been identified as a tumour marker gene of interhepatic cholangiocarcinoma, a type of cancer of the bile ducts in the liver. This project aims to determine whether IGFBP-5 could be used as a biomarker for detecting liver damage and fibrosis. Several models of liver disease were developed to determine if IGFBP-5 could potentially be a suitable biomarker using monolayers of primary rat hepatocytes cultured on collagen I coated tissue culture plastic dishes. Firstly, IGFBP-5 release into the culture medium from primary rat hepatocytes cultured over time was investigated along with models of oxidative stress, alcoholic liver disease (ALD), and non-alcoholic liver disease (NALFD). It was determined that the expression of IGFBP-5 over time in culture was increased, suggesting that it may have potential as a biomarker of dedifferentiation. Treatments with menadione, hydrogen peroxide, or ethanol and its primary metabolite acetaldehyde were used to unravel the story on oxidative stress.However, IGFBP-5 was undetectable in the culture medium after chronic treatment with each of the compounds listed. An in vitro model of NALFD was developed at the University of Edinburgh. The model was developed with the ability to induce either enhanced or minimal ROS formation. The in vitro study showed promising results, demonstrating that, with time in culture, in both models, an increase in IGFBP-5 expression was detected. Following on from the in vitro study, a patient study was undertaken to determine if patients with various types of liver disease had any changes in their circulating IGFBP-5 levels. After extensive work, IGFBP-5 could not be detected in human serum using a commercially available kit. This was thought to be due to the human serum interfering with the assay kits ability to detect IGFBP-5. IGFBP-5 does have potential as a biomarker of early liver disease, showing promising results from two models; de-differentiation and NAFLD. Further work into its involvement in liver injury or recovery mechanisms could determine it as useful biomaker in the hep atology clinic.
|Date of Award||13 Jun 2015|
- University Of Strathclyde
|Supervisor||David Flint (Supervisor) & Mary Grant (Supervisor)|