Mediating effect of telomere length in a hypertension population exposed to cadmium: a case-control study

Cadmium (Cd) is associated with telomere length and hypertension, respectively, but the mechanism behind its relationship is unclear. Our study aimed to clarify the role of telomere length in the relationship between Cd and hypertension. A 1:1 matched case-control study was conducted with 213 hypertensive patients and 213 normotensive controls in Taiyuan, Shanxi Province, China, from February and June 2016. General demographic characteristics information and lifestyle were collected using a structured questionnaire. Urine samples were collected to test urinary Cd (UCd) levels and corrected by urinary creatinine (UCr) levels. Peripheral leukocyte absolute telomere length (ATL) was measured using quantitative polymerase chain reaction. Logistic regression was used to screen the influencing factors of hypertension. A mediation effect analysis was used to explore the role of telomere length between Cd exposure and the risk of hypertension. We found that the hypertension group had a significantly higher UCd level compared to the control group (0.91 vs 0.80 μg/g Cr, P < 0.01), while ATL showed the opposite relationship (2.36 vs 2.65 kb, P < 0.01). The Regression analysis of hypertension identified these significant predictors: family history of hypertension (OR = 3.129, 95% confidence interval (95% CI): 1.767-5.540), Body mass index (BMI, OR = 1.088, 95% CI: 1.023-1.157), total cholesterol (TC, OR = 1.277, 95% CI: 1.024-1.592), UCd (OR = 2.092, 95% CI: 1.179-3.710), ATL (OR = 0.105, 95% CI: 0.025-0.453) and 8-hydroxy-2-deoxyguanosine (8-OHdG, OR = 7.864, 95% CI: 3.516-17.589). Mediating effect analysis revealed that ATL was a potential partial mediating factor between Cd and hypertension. Cd may induce hypertension by affecting telomere length, but this requires further exploration.