Repeated measures of prenatal thallium exposure and placental inflammatory cytokine mRNA expression: The Ma'anshan birth cohort (MABC) study

Thallium (TI), a ubiquitous environmental toxicant, can cross the placental barrier during pregnancy. However, the effects of prenatal TI exposure on placental function are currently unclear. Based on the Ma'anshan Birth Cohort study, we examined whether long-term prenatal TI exposure was associated with placental inflammation. TI concentrations were quantified in serum samples (n = 7050) from 2515 pregnancy during each trimester, placental inflammatory cytokine mRNA expression was assessed in 2519 placenta tissues. Geometric mean values of serum TI concentrations were 63.57, 63.63 and 48.71 ng/L for the first, second and third trimesters, respectively. After adjustment for potential confounders, serum TI concentration was positively associated with CD68 (beta: 0.30; 95% CI: 0.05, 0.56) in the first trimester and TNIF-alpha (beta: 0.12; 95% CI: 0.01, 0.23), IL-6 (beta: 0.15; 95% CI: 0.05, 0.25) and CD68 (beta: 0.25; 95% CI: 0.10, 0.39) in the third trimester, however was negatively associated with IL-4 (beta: -0.21; 95% CI: -0.41, -0.01) and CD206 (beta: -0.23; 95% CI: -0.45, -0.02) in the first trimester. Repeated measures analysis showed that TNF-alpha, IL-6 and CD68 increased by 0.11 (95% CI: 0.01, 0.21), 0.12 (0.15, 95% CI: 0.05, 0.25), 0.22 (95% CI: 0.10, 0.39), respectively, with each 1 In-transformed TI increase in total samples. Gender-specific analyses revealed that these associations were largely driven by male offspring. In addition, immunohistochemistry revealed that nuclear NF-kappa B p65 expression increased in placenta tissue. The results of this prospective cohort study provide longitudinal evidence that prenatal TI exposure induces a placental inflammatory response in the Chinese population. (C) 2019 Elsevier Ltd. All rights reserved.