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P-cresol, but not p-cresylsulphate, disrupts endothelial progenitor cell function in vitro
Jin-zhou Zhu1, Jing Zhang, Ke Yang
1Department of Cardiology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Insights
The uremic toxin p-cresol (pC) impairs endothelial progenitor cell (EPC) function and proliferation, while its metabolite p-cresylsulphate (pCS) does not. Further research is needed to understand pCS's cardiovascular toxicity.
Area of Science:
- Nephrology
- Cardiovascular Biology
- Toxicology
Background:
- Chronic kidney disease (CKD) patients often develop cardiovascular disease (CVD), a leading cause of mortality.
- High levels of protein-bound uremic toxins and aberrant endothelial progenitor cells (EPCs) contribute to CVD in CKD.
- The uremic toxin p-cresol (pC) inhibits EPC proliferation and function; its metabolite is p-cresylsulphate (pCS).
Purpose of the Study:
- To investigate the in vitro effects of p-cresol (pC) and p-cresylsulphate (pCS) on human EPCs.
- To compare the distinct impacts of pC and pCS on EPC proliferation, migration, and tube formation.
Main Methods:
- Human late-outgrowth EPCs were treated with varying concentrations of pC or pCS for up to 72 hours.
- EPC proliferation was assessed using WST-1 assay.
- EPC function was evaluated through migration and tube formation assays, alongside cell cycle analysis.
Main Results:
- pC significantly inhibited EPC proliferation with an IC50 of 80.1 µg/mL (in presence of HSA).
- pC impaired EPC migration and tube formation, causing G2/M cell cycle arrest.
- pCS did not affect EPC proliferation, migration, tube formation, or cell cycle parameters.
Conclusions:
- pC and its metabolite pCS exhibit differential effects on human EPC function.
- pC demonstrates significant toxicity to EPCs, whereas pCS appears to be non-toxic in vitro.
- Further investigation into the specific cardiovascular toxicity of pCS is warranted.
Background:
Patients afflicted with chronic kidney disease (CKD) typically suffer from cardiovascular disease (CVD) which is a leading cause of patient mortality. It has been demonstrated that two distinct physiological events contribute to this disease state. These include the abundance of abnormally high levels of protein-bound uraemic toxins as well as functionally aberrant endothelial progenitor cells (EPCs). Specifically, it has been demonstrated that the uraemic toxin p-cresol (pC; 4-methylphenol) inhibits EPC proliferation and tube formation in previous in vitro studies. More recently, however, it has been demonstrated that circulating pC is actually conjugated and that p-cresylsulphate (pCS) is its main metabolite. Therefore, within the context of this study, we examined the in vitro effects of pC and pCS treatment on cultured human EPCs.
Methods:
Late-outgrowth EPCs were treated with physiological concentrations of pC or pCS (10, 40, 80, and 160 or 10, 40, 80, 160 and 320 µg/mL for up to 72 h, respectively) in the presence of 4% human serum albumin (HSA). Cell proliferation was determined using WST-1 assay, while migration and tube formation assays were used to evaluate EPC function in vitro. Cell cycle analyses were also performed to determine the effects of pC and pCS on cell cycle status.
Results:
With regard to EPC proliferation, data demonstrate that pC in the presence or absence of HSA had an IC50 of 80.1 and 100.8 µg/mL 72 h post-treatment, respectively, while pCS-treated groups did not impair EPC proliferation. Similarly, pC-treated groups showed limited vessel formation and migration compared with controls and no detrimental effects were seen with pCS treatment. Lastly, pC treatment of EPCs caused cells to accumulate in the G2/M phase of the cell cycle with accompanied down-regulation of cyclin B1 and phosphorylated CDK1. pCS had no effect on cell cycle parameters.
Conclusions:
Our data demonstrate that pC and pCS have different effects on EPC function. Since there is a dearth of data that have focused on the toxicity of pCS, further research should be performed to determine the exact biological toxicity of pCS on the cardiovascular system.