Development of a liver-based epigenetic silencing strategy to treat familiar hypercholesterolemia

Familial Hypercholesterolemia (IF) is an inherited genetic disease caused by mutations in genes involved in the metabolism of cholesterol. Commonly referred to as "bad cholesterol", cholesterol associated with low-density lipoproteins (also known as LDL-C) circulates in the blood in the form of large particles. If not properly captured and degraded by the liver cells, cholesterol accumulates in the inner wall of blood vessels, resulting in cardiovascular diseases, including atherosclerosis, a disease closely related to the onset of heart attack or stroke. Among the genes responsible for IF, the one that codes for the PCSK9 protein has recently attracted particular attention. In fact, PCSK9 regulates the absorption of LDL-C by liver cells, and mutations that increase its function determine an accumulation of LDL-C in the blood of patients, accelerating the processes of atherosclerosis and increasing the onset of cardiovascular diseases. On the other hand, subjects with mutations in PCSK9 that inactivate its function show a decrease in circulating levels of cholesterol and, consequently, a reduction in the onset of cardiovascular diseases. Based on this latest discovery, numerous drugs have been developed that can inactivate PCSK9, currently in clinical trials. Despite the promising data, these drugs must be administered frequently to patients and throughout their lives, resulting in low adherence to treatment. The aim of the project is to develop a gene therapy approach that allows to inactivate PCSK9 after a single drug treatment. To this end, we will use Engineered Transcriptional Repressors (ETRs), artificial proteins able to specifically recognize the gene of interest and stably inactivate its function through epigenetics, the process that physiologically regulates the expression of genes. The project will be pursued first by evaluating the efficacy and specificity of RTAs against PCSK9 in hepatic cell lines. Subsequently, a method for delivering the ETRs to the liver will be developed, and the efficacy, long-term stability and biosecurity of PCSK9 inactivation in animal models, including one affected by IF, will be evaluated.