Urinary phthalate metabolite concentrations in relation to levels of circulating matrix metalloproteinases in pregnant women

Dietary exposure to di(2-ethylhexyl) phthalate for 6 months alters markers of female reproductive aging in mice†

The female reproductive system ages before any other physiological system, making it a sensitive indicator of aging. Early reproductive aging is associated with the early onset of infertility and an increased risk of several diseases. During aging, systemic and reproductive oxidative stress and inflammation levels increase through inflammasome activation, leading to ovarian follicle loss. Other markers of reproductive aging include increased fibrosis and shortening of telomeres in ovarian cells. The factors that accelerate reproductive aging are unclear, but likely involve exposure to endocrine-disrupting chemicals such as phthalates. Di(2-ethylhexyl) phthalate (DEHP) is a widely used phthalate and humans are exposed to it daily. Several studies show that DEHP induces reproductive toxicity by affecting estrous cyclicity, follicle numbers, and hormone levels. However, little is known about the mechanisms underlying DEHP-induced early onset of reproductive aging. Thus, this study tested the hypothesis that dietary exposure to DEHP induces early reproductive aging by affecting inflammation, fibrosis, and the expression of telomere regulators and antioxidant enzymes. Adult CD-1 female mice were exposed to vehicle (corn oil) or DEHP (0.5, 1.5, or 1500 ppm) via the chow for 6 months. Exposure to DEHP increased the expression of antioxidant enzymes and Caspase 3, increased expression of telomere-associated genes, and increased fibrosis levels in the ovary. In addition, DEHP exposure for 6 months altered ovarian and systemic inflammatory status. Collectively, our novel data suggest that 6-month dietary exposure to DEHP may accelerate reproductive aging by affecting several reproductive aging markers in female mice.

Urinary concentrations of phthalate metabolites in relation to preeclampsia and other hypertensive disorders of pregnancy in the environmental influences on child health outcomes (ECHO) program

BACKGROUND

Phthalate exposure may contribute to hypertensive disorders of pregnancy (HDP), including preeclampsia/eclampsia (PE/E), but epidemiologic studies are lacking.

OBJECTIVES

To evaluate associations of pregnancy phthalate exposure with development of PE/E and HDP.

METHODS

Using data from 3,430 participants in eight Environmental influences on Child Health Outcomes (ECHO) Program cohorts (enrolled from 1999 to 2019), we quantified concentrations of 13 phthalate metabolites (8 measured in all cohorts, 13 in a subset of four cohorts) in urine samples collected at least once during pregnancy. We operationalized outcomes as PE/E and composite HDP (PE/E and/or gestational hypertension). After correcting phthalate metabolite concentrations for urinary dilution, we evaluated covariate-adjusted associations of individual phthalates with odds of PE/E or composite HDP via generalized estimating equations, and the phthalate mixture via quantile-based g-computation. We also explored effect measure modification by fetal sex using stratified models. Effect estimates are reported as odds ratios (OR) with 95% confidence intervals (95% CIs).

RESULTS

In adjusted analyses, a doubling of mono-benzyl phthalate (MBzP) and of mono (3-carboxypropyl) phthalate (MCPP) concentrations was associated with higher odds of PE/E as well as composite HDP, with somewhat larger associations for PE/E. For example, a doubling of MCPP was associated with 1.12 times the odds of PE/E (95%CI 1.00, 1.24) and 1.02 times the odds of composite HDP (95%CI 1.00, 1.05). A quartile increase in the phthalate mixture was associated with 1.27 times the odds of PE/E (95%CI 0.94, 1.70). A doubling of mono-carboxy isononyl phthalate (MCiNP) and of mono-carboxy isooctyl phthalate (MCiOP) concentrations were associated with 1.08 (95%CI 1.00, 1.17) and 1.11 (95%CI 1.03, 1.19) times the odds of PE/E. Effect estimates for PE/E were generally larger among pregnancies carrying female fetuses.

DISCUSSION

In this study, multiple phthalates were associated with higher odds of PE/E and HDP. Estimates were precise and some were low in magnitude. Interventions to reduce phthalate exposures during pregnancy may help mitigate risk of these conditions.

Adverse birth outcomes are associated with circulating matrix metalloproteinases among pregnant women in Puerto Rico

Matrix metalloproteinases (MMPs) are major extracellular matrix (ECM) remodeling proteinases and regulate uterine remodeling, which is a critical process for healthy pregnancies. The goal of this study was to investigate associations between maternal blood MMPs during pregnancy and birth outcomes among 898 pregnant women in the Puerto Rico PROTECT birth cohort. MMPs (MMP1, MMP2, and MMP9) were quantified using a customized Luminex assay in blood samples collected at two gestational study visits (around 18 and 26 weeks gestation). Linear and logistic regression models were used to regress continuous and binary birth outcomes, respectively, on MMPs at each study visit separately. Sensitivity analyses were conducted to test for effect modification by fetal sex on associations between MMPs and birth outcomes. We observed significant associations between MMP2 at visit 1 and newborn length that were in the opposite direction from the associations between MMP9 at visit 3 and newborn length. MMPs were associated with increased odds of preeclampsia and gestational diabetes mellitus, though case numbers were low. We also observed significant inverse associations with gestational age for MMP9 and MMP2 at visit 1 and visit 3, respectively, and these associations were observed only in mothers carrying male fetuses. Further, MMP2 was associated with heavier female fetuses, whereas MMP9 was associated with lighter female fetuses. We observed significant associations between birth outcomes and MMPs, and the majority of these associations differed by fetal sex. This study highlighted significant MMPs-birth outcomes associations that may provide a basis to explore the impact of MMPs on endometrium health and physiology.

Associations of urinary phthalate metabolites and inflammatory biomarkers among pregnant women in Puerto Rico

Phthalates are ubiquitous environmental exposures that may be implicated in inflammatory processes, as demonstrated by previous in vivo and in vitro studies. Few human studies have substantiated these observations. This study sought to examine whether maternal phthalate exposures impact inflammatory processes, as measured by circulating inflammatory biomarkers, in the PROTECT cohort in northern Puerto Rico. Inflammatory biomarkers included matrix metalloproteinases 1, 2, and 9 (MMPs), C-reactive protein (CRP), vascular cell adhesion molecule-1 (VCAM), and intercellular cell adhesion molecule-1 (ICAM). Biomarkers were measured in maternal serum samples collected during pregnancy. 19 phthalate metabolites were assessed in urinary samples collected at three study visits across pregnancy. Phthalates with <50 % of measurements above the limit of detection were excluded from analysis. We utilized linear mixed effect models to estimate associations between interquartile range increases in phthalate metabolite concentrations and percent changes in inflammatory biomarkers. Our results revealed significant associations between mono-n-butyl phthalate (MBP) and higher MMP1 by 7.86 % (95 % CI: 0.49, 15.76) and between mono oxononyl phthalate (MONP) and higher MMP2 by 8.30 % (95 % CI: 2.22, 14.75). We observed negative or null associations between phthalate metabolites and MMP2, MMP9, ICAM, VCAM, and CRP. Many results were significantly modified by fetal sex, particularly those between di-2-ethylhexyl phthalate (DEHP) metabolites and MMP1 (p-interaction: MEHHP = 0.01, MEOHP = 0.04, MECPP = 0.01) and MMP2 (p-interaction: MEHHP = 0.03, MEOHP = 0.01, MECPP = 0.01), for which associations were positive among only women carrying female fetuses. MMPs have been previously associated with preeclampsia and hypertensive pregnancy disorders as mediators of artery remodeling. Hence, our findings suggest a potential role for phthalates in mediating the maternal inflammatory response, as well as significant sexual dimorphism in these relationships, which has implications for several adverse pregnancy outcomes.

Trends and Patterns of Phthalates and Phthalate Alternatives Exposure in Pregnant Women from Mexico City during 2007-2010

Phthalates are associated with several adverse health outcomes, but few studies have evaluated phthalate exposures in Mexican populations, particularly pregnant women. Between 2007 and 2011, 948 pregnant women from Mexico City were recruited as part of the PROGRESS cohort. We quantified 17 metabolites of phthalates and phthalate alternatives in urine samples collected during the second and third trimesters and examined temporal trends of metabolite concentrations, within-person reproducibility, and relations of individual metabolites with sociodemographic, lifestyle, and occupational factors. Concentrations of mono-2-ethyl-5-carboxypentyl terephthalate, a metabolite of the alternative phthalate di-2-ethylhexyl terephthalate, increased monotonically from 2007 to 2010 (31% per year; 95% confidence interval = 23 and 39%). We observed moderate to high correlations among metabolites collected at the same visit, but there was high variability between second and third trimester phthalate metabolite concentrations (intraclass correlation coefficients = 0.17-0.35). In general, higher socioeconomic status was associated with higher phthalate concentrations. Some metabolites were associated with maternal age and education, but no consistent patterns were observed. Women working in the home and those who worked in administration had higher concentrations of several phthalate metabolites relative to students, professionals, and those in customer service. Biomonitoring efforts are warranted to investigate present and future exposure trends and patterns.

The extent and predictors of phthalate exposure among couples undergoing in vitro fertilization treatment

Phthalates are chemicals used as plasticizers and solvents in many consumer products but are suspected of disrupting the endocrine system and are known for their reproductive/developmental health risks. This study examined the extent and predictors of phthalate exposure among 599 couples undergoing in vitro fertilization. A questionnaire was administered to obtain sociodemographic, health, and lifestyle data, and two spot urine samples were collected from the couples to analyze eight phthalate metabolites, cotinine (COT) as a smoking index, and creatinine to adjust for urine dilution. Seven phthalate metabolites were detected in > 94% of the urine samples, and monobenzyl phthalate (MBzP) was found in 24% of the women and 26% of their male partners. Median phthalate levels were highest for monoethyl phthalate (MEP), at 333.26 μg/l in women and 290 μg/l in male partners, and lowest for MBzP, at 1.17 μg/l in women and 1.14 μg/l in male partners. Correlation coefficients of ≥ 0.4 between the women and their male partners for the eight urinary phthalate metabolites may indicate a shared source of exposure. A multivariate regression model was used to assess the association between predictors and each urinary phthalate metabolite. Several potential predictors for the variations in specific urinary phthalate metabolites were identified, including the body mass index, age, socioeconomic status, and regional distribution for both women and their male partners but with slightly different patterns. Women with a history of breastfeeding, using bottled water for cooking and storing food in plastic bags had lower MEP (8.7%), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) (9.2%), and both mono-iso-butyl phthalate and MECPP (8.2 and 8.1%). A history of contraceptive use was associated with an increase in MECPP (8.7%), mono-(2-ethyl-5-hydroxyhexyl) phthalate (11.4%), mono-(2-ethyl-5-oxohexyl) phthalate (7.6%), and the molar sum of bis (2-ethylhexyl) phthalate metabolites (8.9%). Urinary COT levels were associated with an increase of 10-16% in all urinary metabolites in women but of only 10.5% in mono-(2-ethylhexyl) phthalate in male partners. More than 95% of the couples reported the use of cosmetics, perfumes, and personal-care products, but we were not able to find associations with urinary phthalate metabolites, perhaps due to their short half-lives. MEP levels associated with the use of household cleaning products were 11.2% higher in male partners. Our levels were generally higher than those reported elsewhere, perhaps due to different lifestyles, cultural practices, dietary habits, use of personal-care products, and governmental legislation.