Abstract Vasculo-thrombosis and altered hemostasis are associated with several organ pathologies, the disease- specific mediators of which remain poorly understood. This aspect is particularly relevant in chronic kidney disease (CKD), which affects 30 million Americans. Patients with CKD suffer from high cardiovascular disease burden, making CKD patients in need of frequent vascular interventions, such as endovascular procedures or vascular surgery. A CKD milieu (uremia) is a strong and independent risk factor for thrombosis after such procedures. Given the upward trend of CKD in general, and high frequency of interventional procedures in them, investigating such post-interventional complications and means to control them is a worthy pursuit. CKD is characterized by retention of a host of uremic solutes. Although studies in humans and animal models implicate the uremic solutes indoxyl sulfate and kynurenine as CKD-specific risk factors and are, therefore, perceived as tantalizing therapeutic targets for cardiovascular disease, their exact mechanism of actions remains poorly understood. This underpinning will be addressed in the current proposal. Our work in recent years elucidated prothrombotic propensities of indolic uremic toxins, partially mediating their toxicity through upregulation of tissue factor in vSMCs. Here, building on new data, we propose an integrative approach to study newly identified converging pathways that augment thrombosis in CKD, consisting of Indoleamine 2,3- dioxygenase-1 (IDO1), a key enzyme in kynurenine production, and lysyl oxidase (LOX), a key enzyme regulator of extracellular matrix remodeling and thrombosis. Aim 1 examines a novel regulation of IDO1 level and activity by indoxyl sulfate and/or kynurenine, and its contribution to uremic thrombosis, using genetic and pharmacological manipulation of IDO1 in a CKD mouse model. Aim 2 builds on our new findings suggesting LOX expression as a target of indoxyl sulfate and kynurenine, thereby contributing to uremia-induced vasculo- thrombosis. This aim employs molecular and gene knockout approaches to understand the control of LOX biogenesis in VSMCs in a uremic milieu, and its contribution to thrombosis in context of CKD. Both aims of research will utilize arterial and venous thrombosis models in CKD mice. Successful completion of this proposal will define CKD-associated common mediators of thrombosis. Along with mechanistic advances, our proposed investigations might pave ways to repurposing advanced clinical compounds for the management of vascular occlusion in CKD patients.

Project Narrative Patients with chronic kidney disease (CKD) are at a higher risk for thrombosis and vascular complications after any vascular procedure, which can be potentially devastating. Over the last decade, our work identified uremic solutes (compounds that accumulate in the blood under compromised kidney function) as potent thrombogenic solutes. The current proposal delineates new mediators of this complication, and successful completion of this project may yield new biomarkers for thrombosis in CKD patients at risk, and may uncover new therapeutic targets.