Mediating role of peripheral blood telomere length in relationship between environmental lead exposure and glomerular filtration rate

Background  Exposure to environmental lead can cause kidney damage and telomere wear. However, the relationship among lead, peripheral blood telomere length, and glomerular filtration rate (eGFR) are unclear.

Objective  This study is conducted to investigate the relationships of urinary lead level with peripheral blood telomere length and renal function index eGFR, and further explore whether peripheral blood telomere length plays an intermediary role in the relationship between urinary lead level and eGFR.

Methods  A case-control study was conducted to select 497 residents from two communities in a city, including 230 in the control group (eGFR≥80 mL·min⁻¹) and 267 in the abnormal eGFR group (eGFR<80 mL·min⁻¹). Basic information and health information of the subjects were collected through a face-to-face questionnaire survey. Fasting morning urine was collected, and urinary lead and urinary creatinine (UCr) were detected. Fasting peripheral venous blood was collected to detect telomere length and serum creatinine (SCr) in peripheral blood leukocytes. eGFR was estimated by the Levey formula. After further adjusting for age, gender, education level, family per capita monthly income, smoking, and drinking the relationship among urinary lead level, peripheral blood telomere length, and renal function index eGFR was evaluated by mediating effect analysis.

Results  The overall level of creatinine-adjusted urinary lead M (P₂₅, P₇₅) in the abnormal eGFR group was 3.85 (1.56, 7.34) μg·g⁻¹ which was higher than that in the control group, 1.57 (0.60, 3.62) μg·g⁻¹(P<0.001). In addition, the overall level of peripheral blood telomere length in the abnormal eGFR group was 2.42 (1.89, 3.10) Kb, lower than that in the control group, 2.69 (2.09, 3.64) Kb (P<0.001). The results of mediating effect analysis showed that the magnitude of mediating effect by peripheral blood telomere length was −0.276 (95%CI: −0.708-−0.001) and it contributed 3.35% to the relationship between urinary lead level and eGFR. In women, the magnitude of mediating effect by peripheral blood telomere length was −0.484 (95%CI: −1.160-−0.023) between urinary lead level and eGFR, and the proportion of the mediating effect was 5.34%. In men, no mediating role of peripheral blood telomere length was found between urinary lead and eGFR.

Conclusion  Urinary lead level is closely related to renal function index eGFR and telomere length in peripheral blood. Peripheral blood telomere length plays a mediating role in the relationship between female urinary lead and eGFR in women.