Does Uremia Cause Vascular Dysfunction

Abstract

Vascular dysfunction induced by uremia has 4 main aspects. (1) Atherosclerosis is increased. Intima-media thickness is increased, and animal studies have established that uremia accelerates atherosclerosis. Uremic toxins are involved in several steps of atherosclerosis. Leukocyte activation is stimulated by guanidines, advanced glycation end products (AGE), p-cresyl sulfate, platelet diadenosine polyphosphates, and indoxyl sulfate. Endothelial adhesion molecules are stimulated by indoxyl sulfate. Migration and proliferation of vascular smooth muscle cells (VSMC) are stimulated by local inflammation which could be triggered by indoxyl sulfate and AGE. Uremia is associated with an increase in von Willebrand factor, thrombomodulin, plasminogen activator inhibitor 1, and matrix metalloproteinases. These factors contribute to thrombosis and plaque destabilization. There is also a decrease in nitric oxide (NO) availability, due to asymmetric dimethylarginine (ADMA), AGE, and oxidative stress. Moreover, circulating endothelial microparticles (EMP) are increased in uremia, and inhibit the NO pathway. EMP are induced in vitro by indoxyl sulfate and p-cresyl sulfate. (2) Arterial stiffness occurs due to the loss of compliance of the vascular wall which induces an increase in pulse pressure leading to left ventricular hypertrophy and a decrease in coronary perfusion. Implicated uremic toxins are ADMA, AGE, and oxidative stress. (3) Vascular calcifications are increased in uremia. Their formation involves a transdifferentiation process of VSMC into osteoblast-like cells. Implicated uremic toxins are mainly inorganic phosphate, as well as reactive oxygen species, tumor necrosis factor and leptin. (4) Abnormalities of vascular repair and neointimal hyperplasia are due to VSMC proliferation and lead to severe reduction of vascular lumen. Restenosis after coronary angioplasty is higher in dialysis than in nondialysis patients. Arteriovenous fistula stenosis is the most common cause of thrombosis. Uremic toxins such as indoxyl sulfate and some guanidine compounds inhibit endothelial proliferation and wound repair. Endothelial progenitor cells which contribute to vessel repair are decreased and impaired in uremia, related to high serum levels of β₂-microglobulin and indole-3 acetic acid. Overall, there is a link between kidney function and cardiovascular risk, as emphasized by recent meta-analyses. Moreover, an association has been reported between cardiovascular mortality and uremic toxins such as indoxyl sulfate, p-cresol and p-cresyl sulfate.

Role of Uremic Compounds in Organ Injury

“…They make up a group whose numerous members differ in their water solubility, protein-binding capacity, molecular weight, pattern of removal by dialysis, biological properties and potential to produce clinical symptoms [2,3,11,19,20].…”

Flow-Mediated Dilatation and Asymmetric Dimethylarginine Do Not Predict Mortality in Peritoneal Dialysis Patients

“…In another study, PD patients were found to have higher ADMA levels than controls, but endothelial dysfunction in these patients could not be explained by this increased level (23). Many mechanisms are known to be effective on endothelial dysfunction in uremic patients, increased ADMA level being only one of them (24). There are concordant and discordant results in larger broadbased studies carried on HD patients (21)(22)(23)(24)(25).…”

“…Many mechanisms are known to be effective on endothelial dysfunction in uremic patients, increased ADMA level being only one of them (24). There are concordant and discordant results in larger broadbased studies carried on HD patients (21)(22)(23)(24)(25). The reason for lack of evidence for correlation in patients with ESRD having many comorbidities, while the evidence is stronger in non-uremic patients with lower cardiovascular risk, may be coexistence of many cardiovascular risk factors (26).…”

The Relationship of Kidney Function With Arterial Wall Condition in Individuals Without Chronic Kidney Disease and Cardiovascular Diseases

“…Субстратом для развития ССЗ с возрастом являются изменения в артериаль-ной стенке: эндотелиальная дисфункция, уси-ление жесткости артериальной стенки, атеро-склероз. На фоне ХБП, а в наибольшей степени при терминальной почечной недостаточности, наблюдается усиление изменений в артериаль-ной стенке [10].…”