OR06-01 Pre-conceptional And Gestational Exposure To A Real-life Environmental Chemical Mixture Increases Maternal Oxidative Stress And Disrupts The Cytokine Milieu In Sheep

Abstract

Abstract Disclosure: S. Thangaraj: None. M. Bellingham: None. S. Pennathur: None. R. Lea: None. K. Sinclair: None. N. Evans: None. V. Padmanabhan: None. Due to potential effects on health, exposure to environmental chemicals (ECs) is of global concern, especially to pregnant women. As the maternal endocrine milieu can have critical effects on pregnancy outcomes and the programming of later onset diseases in offspring, it is important to study the impact of real-life EC exposure, i.e., chronic low levels of mixtures of ECs, in pregnant women. Biosolids, derived from human wastewater treatment, exemplify the array and concentrations of chemicals humans are exposed to and provides a novel model to probe the effects of real-life EC mixture exposure. Offspring of sheep grazed on biosolids-treated pasture are characterized by reproductive and metabolic disruptions. We hypothesized that biosolids exposure will disrupt the maternal cytokine and oxidative stress milieu, which are important in programming offspring health outcomes. EasyCare ewes (Ovis aries) were maintained from 1 month before mating and during gestation on pastures fertilized with either biosolids (BTP), or inorganic fertilizer supplying equivalent levels of nitrogen (Control). The levels of 14 cytokines (IFN-γ, ILs 1α, 1β, 4, 6, 10, 17A, 36RA, MIPs 1α, 1β, IP-10, TNF-α and VEGF-A) were quantified in maternal plasma (15 ewes/group) collected on day 90 of the 144-day gestation period, using Milliplex xMAP assay. Total antioxidant status, reactive oxygen metabolites (Rel Assay Diagnostics) and the lipid peroxidation product - malondialdehyde (Cayman Chemical) were assayed using kits. Chlorotyrosine, nitrotyrosine and dityrosine were quantified by tandem mass spectrometry. Statistical significance between control and BTP groups was assessed by t-test after replacing values below limit of detection (LOD) to LOD/sqrt(2). ANOVA was used to test for difference between groups based on fetal sex. P values < 0.05 were considered significant. Fetal sex-specific effects were not seen. Overall, reactive oxygen metabolites were 1.48-fold higher in the BTP group (P = 0.006). Total antioxidant status, malondialdehyde and all 3 tyrosine moieties did not differ between control and BTP groups. In contrast, there was a decrease in the proinflammatory cytokines IL-1β (1.6-fold) and IL-17A (1.9-fold) and anti-inflammatory IL-36RA (1.5-fold) in the BTP group compared to the controls. The increase in reactive oxygen metabolites in the face of decreased inflammatory markers suggests compensatory mechanisms may be operant. Contrary to the control group, a positive correlation was observed between chlorotyrosine and IL-1α and TNFα in the BTP group, suggestive of additional independent effects of biosolids exposure on the maternal cytokine milieu. These results suggest that exposure to ECs in biosolids disrupts the maternal cytokine and oxidative stress milieu likely contributing to the aberrant reproductive and metabolic effects in the offspring. Presentation: Thursday, June 15, 2023