Arteriovenous (AV) access complications remain a major cause of morbidity in hemodialysis patients, influenced by multiple factors, including endothelial inflammation induced by uremia. In this study, we investigated the mechanisms underlying the upregulation of endothelial chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) by indolic uremic toxins, as well as their association with AV access complications in hemodialysis patients. In cultured human endothelial cells, IL-8 and MCP-1 were upregulated by indolic uremic toxins through activation of their receptor, the aryl hydrocarbon receptor (AHR), and non-canonical TGF-β pathway involving TAK1/p38 MAPK/AP-1 signaling. In a retrospective observational study of 204 hemodialysis patients, baseline serum IL-8 or MCP-1 were positively correlated with indolic uremic toxins and TGFβ1. Additionally, serum IL-8 ≥ 40.26 pg/mL and serum MCP-1 were independently associated with an increased risk of AV access complications over a 2-year period. In conclusion, we demonstrated that indolic uremic toxins promote endothelial inflammation by inducing IL-8 and MCP-1 expression via AHR activation and non-canonical TGF-β signaling. Clinically, elevated serum IL-8 and MCP-1 were independently associated with an increased risk of AV access complications in hemodialysis patients.

Hemodialysis patients exhibit endothelial dysfunction, contributing to elevated cardiovascular risk and complications of the arteriovenous access. These patients have elevated serum levels of myostatin, a member of the transforming growth factor-β (TGFβ) superfamily, and of the uremic toxin indoxyl sulfate, both of which are pro-inflammatory towards endothelial cells. We hypothesized that myostatin and indoxyl sulfate may synergistically induce endothelial dysfunction by impairing endothelial proliferation and promoting a pro-inflammatory phenotype. We first investigated the effect of myostatin on cultured endothelial cells in the presence of indoxyl sulfate. We then examined the association between serum myostatin concentrations and the occurrence of cardiovascular and arteriovenous access complications in hemodialysis patients. In vitro, myostatin exhibited endotheliotoxic effects in the presence of a uremic concentration of indoxyl sulfate, enhanced its antiproliferative effect, and amplified MCP-1 and IL-8 chemokine upregulation. In patients, high myostatin concentrations correlated with indoxyl sulfate concentrations and were associated with an increased risk of arteriovenous access complications. These findings suggest that myostatin amplifies endothelial injury mediated by indolic uremic toxins and might contribute to AV access complications.