Environmentally relevant concentrations of antimony pose potential risks to human health: An evaluation on human umbilical vein endothelial cells

Antimony (Sb) ore exploitation and the use of Sb-containing drugs pose known health risks. This study investigated the toxicity of environmentally relevant concentrations of Sb (0.12–12 mg L⁻¹) on human umbilical vein endothelial cells (HUVECs). The 50 % lethal concentration (LC₅₀) of Sb to HUVECs was 11.4 mg L⁻¹. Exposing to high level of Sb induced cell cycle arrest by altering the expression of cell cycle regulators, inhibiting the transitions of G₀/G₁ to S and S to G₂/M. At 1.2 mg L⁻¹ Sb, CKD6 and p21 expressions in HUVECs changed to 0.75 and 1.32 folds that of no-Sb control, respectively (p < 0.01). At 12 mg L⁻¹ Sb, CDK2, CKD6, and p27 expressions decreased by 1.54, 4.41, and 1.54 folds (p < 0.001), while p21 expression increased by 3.03 folds (p < 0.001) as compared to control. Sb also led to cell apoptosis, evidenced by Annexin V-FITC/PI staining and changes in the expressions of Bax (1.21–1.30 folds, p < 0.01) and Bcl-2 (0.65–0.83 folds). Oxidative damage was a pivotal factor driving cell apoptosis, probably through down-regulating antioxidant genes (CAT, GPX1, and GSTP1) and up-regulating stress response genes (HO-1, SOD1, and TrxR1). The elevated H₂O₂ generated in mitochondria likely contributed to cell apoptosis due to the imbalance in H₂O₂ metabolism. These findings suggest that environmentally relevant concentrations of Sb can exert cytotoxicity to HUVECs, which should be of potential concern for human cardiovascular disease.