Histomorphological and ultrastructural changes of the placenta in mice exposed to formaldehyde

Impact of Fluoride Exposure on Rat Placenta: Foetal/Placental Morphometric Alterations and Decreased Placental Vascular Density

Inorganic fluoride is a geogenic and anthropogenic contaminant widely distributed in the environment and commonly identified in contaminated groundwater. There is limited information on the effect of fluoride exposure on pregnancy. The aim of this study was to evaluate possible placental alterations of fluoride exposure in a rat model simulating preconception and pregnancy exposure conditions in endemic areas. Fluoride exposure was administered orally to foetuses of dams exposed to 2.5 and 5 mg fluoride/kg/d. Foetal weight, height, foetal/placental weight ratio, placental zone thickness, levels of malondialdehyde (MDA) and vascular endothelial growth factor-A (VEGF-A) and vascular density in placental tissue were evaluated. The results showed a nonlinear relationship between these outcomes and the dose of fluoride exposure. In addition, a significant increase in the fluoride concentration in placental tissue was observed. The group that was exposed to 2.5 mg fluoride/kg/d had a greater increase in both MDA levels and VEGF-A levels than the higher dose group. A significant increase in the thickness of the placental zones and a decrease in the vascular density of the labyrinth zone area were also observed in the fluoride-exposed groups. In conclusion, the data obtained demonstrate that fluoride exposure results in morpho-structural alterations in the placenta and that non-monotonic changes in MDA, VEGF-A levels and placental foetal weight ratio were at environmentally relevant concentrations.

Role and mechanism of miR-871-3p/Megf8 in regulating formaldehyde-induced cardiomyocyte inflammation and congenital heart disease

OBJECTIVE AND DESIGN

We aimed to investigate the molecular mechanism underlying formaldehyde (FA)-induced congenital heart disease (CHD) using in vitro and in vivo models.

MATERIALS AND SUBJECTS

Neonatal rat heart tissues and H9C2 cells were used for in vitro studies, while FA-exposed new-born rats were used for in vivo studies.

TREATMENT

H9C2 cells were exposed to FA concentrations of 0, 50, 100 and 150 μM/mL for 24 h.

METHODS

Whole transcriptome gene sequencing identified differentially expressed miRNAs in neonatal rat heart tissues, while Real-time quantitative PCR (RT-qPCR) assessed miR-871-3p and Megf8 expression. RNA pull-down and dual-luciferase reporter assays determined miR-871-3p and Megf8 relationships. Inflammatory cytokine expression was assessed by western blotting. A FA-induced CHD model was used to validate miR-871-3p regulatory effects in vivo.

RESULTS

We identified 89 differentially expressed miRNAs, with 28 up-regulated and 61 down-regulated (fold change ≥ 2.0, P < 0.05). Inflammation (interleukin) and signalling pathways were found to control FA-induced cardiac dysplasia. miR-871-3p was upregulated in FA-exposed heart tissues, modulated inflammation, and directly targeted Megf8. In vivo experiments showed miR-871-3p knockdown inhibited FA-induced inflammation and CHD.

CONCLUSION

We demonstrated miR-871-3p's role in FA-induced CHD by targeting Megf8, providing potential targets for CHD intervention and improved diagnosis and treatment strategies.

Identification of long non-coding RNA in formaldehyde-induced cardiac dysplasia in rats

Formaldehyde exposure during pregnancy can cause fetal congenital heart disease (CHD). However, the regulatory mechanism remains unclear. Studies on the biology of long non-coding RNAs (lncRNAs) show that lncRNAs can influence cardiac development and disease. However, expression patterns and regulatory mechanisms of action of lncRNAs in formaldehyde-induced CHD remain unclear. We used high-throughput sequencing strategies as a means of identifying lncRNA expression profiles in heart tissues of normal and formaldehyde-exposed newborn rats. Overall, 763 differentially expressed lncRNAs were identified, including 325 and 438 that were respectively up-regulated and down-regulated. GO and KEGG analyses indicated that the Ras and hedgehog signaling pathways may be important regulatory pathways in CHD caused by exposure to formaldehyde. A lncRNA-miRNA-mRNA co-expression network was constructed and a key miRNA, rno-miR-665, was identified. Furthermore, qRT-PCR analysis verified that the novel lncRNAs: MSTRG.27313.2, MSTRG.30629.2, MSTRG.36520.33, MSTRG.91234.1, and MSTRG.91233.9, were upregulated in the formaldehyde-exposed group. These differentially expressed lncRNAs identified during formaldehyde-induced CHD in newborn rats help explain CHD pathogenesis and provide an effective reference for diagnosing and treating CHD.

E-cigarette vapor exposure in utero causes long-term pulmonary effects in offspring

The in utero environment is sensitive to toxicant exposure, altering the health and growth of the fetus, and thus sensitive to contaminant exposure. Though recent clinical data suggest that e-cigarette use does no further harm to birth outcomes than a nicotine patch, this does not account for the effects of vaping during pregnancy on the long-term health of offspring. Pregnant mice were exposed to: 1) e-cigarette vapor with nicotine (PV + Nic; 2% Nic in 50:50 propylene glycol: vegetable glycerin), 2) e-cigarette vapor without nicotine [PV; (50:50 propylene glycol:vegetable glycerin)], or 3) HEPA filtered air (FA). Dams were removed from exposure upon giving birth. At 5 mo of age, pulmonary function tests on the offspring revealed female and male mice from the PV group had greater lung stiffness (Ers) and alveolar stiffness (H) compared with the FA group. Furthermore, baseline compliance (Crs) was reduced in female mice from the PV group and in male mice from the PV and PV + Nic groups. Lastly, female mice had decreased forced expiratory volume (FEV0.1) in the PV group, but not in the male groups, compared with the FA group. Lung histology revealed increased collagen deposition around the vessels/airways and in alveolar tissue in PV and PV + Nic groups. Furthermore, goblet hyperplasia was observed in PV male and PV/PV + Nic female mice. Our work shows that in utero exposure to e-cigarette vapor, regardless of nicotine presence, causes lung dysfunction and structural impairments that persist in the offspring to adulthood.

Maternal occupational exposure to chemicals in the textile factory during pregnancy is associated with a higher risk of polydactyly in the offspring

Background: The number of children with polydactyly seen in our clinic is increasing. In addition to genetic factors, an influence of environmental effects during pregnancy is becoming increasingly apparent; however, epidemiological data on these effects are lacking.Methods: This hospital-based, case-control study enrolled 143 patients with polydactyly and 286 control patients with no genetic diseases, to evaluate the association between maternal exposure to a textile factory environment during pregnancy and the likelihood of giving birth to a child with polydactyly.Results: Maternal exposure to a textile factory environment during pregnancy was associated with an increased risk of giving birth to a child with polydactyly (exposure to textile factory environment: unadjusted odds ratio (OR) = 3.31, 95% confidence interval (CI) = 1.75-6.27, p = .0002; work seniority of exposed occupation: unadjusted OR 1.28, 95% CI = 1.13-1.47, p = .0002). Covariate screening indicated that certain risk factors (family monthly income per capita, mother's emotional state during pregnancy, colporrhagia, passive smoking, smoking, and history of consanguineous marriage) were potential confounding factors. After adjusting for these variables, the OR of exposure to a textile factory environment remained significant (exposure to textile factory environment: adjusted OR = 3.08, 95% CI = 1.32-7.19, p = .0094; work seniority of exposed occupation: adjusted OR = 1.58, 95% CI = 1.20-2.08, p = .0010). The risk of polydactyly increased with the number of years of employment.Conclusions: Maternal exposure to a textile factory environment appears to be a risk factor for polydactyly in newborns.

Effects of hesperidin on formaldehyde-induced toxicity in pregnant rats

This experimental study aimed to investigate the protective effect of a bioflavonoid, hesperidin (HP), on formaldehyde (FA)-related pathophysiological and behavioral outcomes in pregnant rats and developmental aspects in their offspring. Female Wistar rats were subjected to perigestational exposure to FA (2 mg/kg/day per os) with a concomitant treatment with HP (50 mg/kg/day per os). Pregnant rats were weighed throughout gestation and tested in two behavioral paradigms (elevated plus-maze and open field) at gestational days (GD) 1, 10 and 19 to evaluate the anxiety-like behavior and locomotive alterations. Another subset of rats was decapitated at GD19 to determine the hematological profile along with cortisol, 17β-estradiol, and progesterone plasma levels. Reproductive and fetal measures and observations were also performed to check for developmental deformities. Significant body weight loss, hemato-immune decline, hormonal changes, anxiety and lethargy signs, locomotor disabilities, reproductive failure and fetal weight decrease were observed in FA-exposed rats. Treatment with HP alleviated the reproductive and fetal weight defects. Its behavioral benefits were only seen at GD1 and 10. This flavanone ameliorated some hematological parameters, decreased cortisol levels and increased 17β-estradiol rates. A potential preventive impact of HP was found against FA toxicity in pregnant rats.

Effects of Sildenafil Citrate and Heparin Treatments on Placental Cell Morphology in a Murine Model of Pregnancy Loss

Lipopolysaccharide (LPS) injections during pregnancy are well established as models for pregnancy complications, including fetal growth restriction (FGR), thrombophilia, preterm labor and abortion. Indeed, inflammation, as induced by LPS injection has been described as a pivotal factor in cases of miscarriage related to placental tissue damage. The phosphodiesterase-5 inhibitor sildenafil (Viagra®) is currently used to treat FGR cases in women, while low-molecular weight heparin (Fragmin®) is a standard treatment for recurrent miscarriage (RM). However, the pathways and cellular dynamics involved in RM are not completely understood. The aim of this study was to evaluate the protective effect of sildenafil and dalteparin in a mouse model of LPS-induced abortion. Histopathology, ultrastructural analysis and immunofluorescence for P-selectin were studied in two different placental cell types: trophoblast cells and labyrinth endothelial cells. Treatment with sildenafil either alone or in combination with heparin showed the best response against LPS-induced injury during pregnancy. In conclusion, our results support the use of these drugs as future therapeutic agents that may protect the placenta against inflammatory injury in RM events. Analyses of the ultrastructure and placental immunophysiology are important to understand the mechanism underlying RM. These findings may spark future studies and aid in the development of new therapies in cases of RM.

Formaldehyde Crosses the Human Placenta and Affects Human Trophoblast Differentiation and Hormonal Functions

The chorionic villus of the human placenta is the source of specific endocrine functions and nutrient exchanges. These activities are ensured by the syncytiotrophobast (ST), which bathes in maternal blood. The ST arises and regenerates throughout pregnancy by fusion of underlying cytotrophoblasts (CT). Any anomaly of ST formation or regeneration can affect pregnancy outcome and fetal growth. Because of its direct interaction with maternal blood, the ST is sensitive to drugs, pollutants and xenohormones. Ex vivo assays of perfused cotyledon show that formaldehyde, a common pollutant present in furniture, paint and plastics, can accumulate in the human placenta and cross to the fetal compartment. By means of RT-qPCR, immunoblot and immunocytochemistry experiments, we demonstrate in vitro that formaldehyde exerts endocrine toxicity on human trophoblasts, including a decrease in the production of protein hormones of pregnancy. In addition, formaldehyde exposure triggered human trophoblast fusion by upregulating syncitin-1 receptor expression (ASC-type amino-acid transporter 2: ASCT2). Moreover, we show that formaldehyde-exposed trophoblasts present an altered redox status associated with oxidative stress, and an increase in ASCT2 expression intended to compensate for this stress. Finally, we demonstrate that the adverse effects of formaldehyde on trophoblast differentiation and fusion are reversed by N-acetyl-L-cysteine (Nac), an antioxidant.