Thrombotic complication of uremia: role of prothrombotic uremic solutes

Boston Medical Center, Boston MA

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Abstract

? DESCRIPTION (provided by applicant): Of several cardiovascular manifestations in chronic kidney disease (CKD), thrombosis represents a potentially life threatening complication. CKD environment (uremia) is a profoundly thrombogenic. For example, next to medication noncompliance, CKD is both the second highest risk factor (increasing the risk for stent thrombosis by 6-10 folds) and an independent risk factor, which strongly suggests the presence of CKD-specific mediators. Despite its magnitude (more than 20 million people, 10% of US population with CKD) and adverse repercussions on the national public health system, mediators of uremic thrombosis have remained elusive, hampering the progress in the fields of predictive biomarkers. Furthermore, anti-thrombotic therapeutics in CKD also poses challenges. Antiplatelet and antithrombotic agents exhibit suboptimal efficacy in CKD patients, underscoring a need for a CKD-specific therapeutic target. Therefore, thrombosis in CKD is an area of high unmet clinical need both from pathogenic and therapeutic perspectives. CKD is characterized by retention of several solutes/metabolites called `uremic solutes/toxins'. Highly protein-bound nature of some of them precludes their effective clearance with dialysis. Thus, perturbing their intracellular signaling represents the most practical approach to abate the induced thrombogenicity. We were the first to identify the prothrombotic property of indolic solutes such as indoxyl sulfate (IS), which induce tissue factor (TF, a potent procoagulant) to enhance thrombosis. Our very recent work uncovered Aryl Hydrocarbon Receptor (AHR) as a key mediator of this regulation and supported IS-AHR-TF, a CKD- specific thrombosis axis. A novel panel of AHR blockers (AHRBs) showed anti-thrombotic activities. The present proposal examines this uremic thrombosis axis mechanistically and translationally leveraging animal models and samples from a large cohort of human patients. Aim 1 performs a mechanistic deconvolution of TF regulation by AHR, Aim 2 examines the in vivo relevance of AHR-TF-thrombosis in animal models of CKD, and Aim 3 correlates the serum IS, IA levels, AHR and TF activities with post-angioplasty thrombosis in Thrombosis in Myocardial Infarction-II (TIMI)-II cohort. This will be first study to analyze the uremic metabolites and validate IS-AHR-TF-thrombosis axis in a large US cohort. The present study will also support IS as a potential biomarker and AHR as a therapeutic target for uremic thrombosis. This interdisciplinary application will be facilitated by expertise of Drs. Vipul Chitalia, PI; a nephrologist and a junio physician-scientist focused on thrombosis in CKD patients), Katya Ravid, in platelet and vascular biology (co-investigator), David Sherr (co-investigator), in AHR biology, and Janice Weinberg, expert in Biostatistics and analysis of clinical studies; and consultants - David Salant, an experienced investigator in CKD animal models, Elazer Edelman, an experienced investigator in stent thrombosis and Naomi Hamburg, a clinical epidemiologist and cardiologist experienced in various translational cardiovascular studies such as Framingham Heart Study.