Indoxyl Sulfate, a Uremic Endotheliotoxin.

Area of Science:

• Nephrology
• Cardiology
• Toxicology

Background:

• Chronic kidney disease (CKD) is linked to increased cardiovascular disease (CVD) risk.
• Uremic toxins, such as indoxyl sulfate (IS) from tryptophan metabolism, accumulate in CKD.
• IS is implicated in the pathophysiology of CKD-related cardiovascular complications.

Purpose of the Study:

• To review clinical and experimental evidence of IS-induced endothelial toxicity.
• To explore the molecular pathways involved in IS endothelial toxicity.
• To highlight the potential of IS reduction therapies for cardiovascular health in CKD.

Main Methods:

• Review of clinical studies correlating IS levels with cardiovascular events and markers.
• Analysis of experimental data on IS effects on endothelial cells and vascular function.
• Examination of molecular mechanisms, including receptor activation and signaling pathways.

Main Results:

• Elevated plasma IS levels in CKD patients correlate with cardiovascular events, mortality, vascular calcification, and atherosclerosis.
• IS induces endothelial dysfunction, a prothrombotic state, and impaired neovascularization.
• In vitro studies show IS activates the aryl hydrocarbon receptor (AhR), leading to inflammation, oxidative stress, and reduced nitric oxide bioavailability, while impairing endothelial cell function and vascular smooth muscle cell proliferation.

Conclusions:

• Indoxyl sulfate is an endotheliotoxin contributing to cardiovascular morbidity and mortality in CKD.
• Reducing IS levels, for example with AST-120, may reverse endothelial dysfunction and improve cardiovascular outcomes.
• Targeting IS endothelial toxicity is a potential strategy to enhance cardiovascular health in CKD patients.