Project Summary The main goal of this grant proposal titled “Using Fortilin Inhibitors to Block Atherosclerosis” is to generate small molecular weight inhibitors of fortilin (named FISCs: fortilin inhibiting small molecular weight compounds) and test the hypothesis that FISCs protect against atherosclerosis by silencing fortilin in macrophages (MΦ), inducing MΦ apoptosis, and polarizing MΦ to the anti-inflammatory M2 phenotype. By 2025, the worldwide death due to atherosclerosis and associated complications is projected to surpass that of every major disease, including cancer, infection, and trauma. The total cost of atherosclerosis- related diseases in the U.S. alone is estimated to be $286 billion annually. After statins, there is no break- through strategy in the pipeline to contain this deadly and global disease. Statins alone have not been able to eliminate atherosclerosis. There is an urgent need to identify other molecular targets of atherosclerosis and devise strategies to attack them. Successful strategies would be highly significant and advance the field of atherosclerosis therapeutics. Our laboratory has studied fortilin, a 172-amino acid multi-functional protein, for the last 15 years. Using fortilin-deficient mice placed on the hypercholesterolemia genetic background, we discovered that fortilin promotes atherosclerosis. Next, we screened 14,400 drug-like small molecular weight (SMW) compounds using biochemical and cellular methods. After primary, secondary, and tertiary screening, we identified the three most promising compounds (“hits”) and named them FISC11C09, FISC172E05, and FISC107B10. Preliminary studies revealed that these three compounds are safe and possess many positive drug- like attributes. The project is innovative because SMW inhibitors of fortilin have never been identified and we propose to use them to halt atherosclerosis. However, these compounds are not yet potent enough to be used in humans. Having assembled a team with expertise in fortilin, structural biology and computational drug design, medicinal chemistry, pharmacology and toxicology, and atherosclerosis, we here propose to first modify structures of the three FISC compounds to generate highly potent and safe lead compounds (FISCLEADs)(Aim 1). We will test the FISCLEADs for their pharmacokinetics and toxicology attributes and modify them further as needed to generate the final compounds (FISCBESTs) that are appropriate for use in whole animals (Aim 2). Having developed and validated the MΦ-specific compound delivery system, we will finally administer FISCBESTs to the hypercholesterolemic Ldlr-/-Apobec1-/- mice systemically as well as in a MΦ-specific fashion to test the hypothesis that fortilin inhibition ameliorates the development and progression of atherosclerosis (Aim 3). Upon completion of the project, we expect to have generated and validated SMW fortilin inhibitors that are ready for testing in clinical trials.