Vitamin E Reversed Apoptosis of Cardiomyocytes Induced by Exposure to High Dose Formaldehyde During Mice Pregnancy

Dual effects of endogenous formaldehyde on the organism and drugs for its removal

Endogenous formaldehyde (FA) is produced in the human body via various mechanisms to preserve healthy energy metabolism and safeguard the organism. However, endogenous FA can have several negative effects on the body through epigenetic alterations, including cancer growth promotion; neuronal, hippocampal and endothelial damages; atherosclerosis acceleration; haemopoietic stem cell destruction and haemopoietic cell production reduction. Certain medications with antioxidant effects, such as glutathione, vitamin E, resveratrol, alpha lipoic acid and polyphenols, lessen the detrimental effects of endogenous FA by reducing oxidative stress, directly scavenging endogenous FA or promoting its degradation. This study offers fresh perspectives for managing illnesses associated with endogenous FA exposure.

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.

Formaldehyde induced the cardiac damage by regulating the NO/cGMP signaling pathway and L-Ca2+ channels

Background

Formaldehyde (FA) is a common environmental pollutant that has been found to cause negative cardiovascular effects, however, the toxicological mechanism is not well understood. In this study, we investigated the molecular effects of the Nitric Oxide (NO)/cyclic Guanosine Monophosphate (cGMP) signaling pathway and L-type calcium (L-Ca2+) channels in rat hearts.

Methods

We designed the short-term FA exposure on the rat heart in different concentrations (0, 0.5, 3, 18 mg/m3). After 7 days of exposure, the rats were sacrificed and the rat tissues were removed for various experiments.

Results

Our experimental data showed that FA resulted in the upregulation NO and cGMP, especially at 18 mg/m3. Further, when exposed to high concentrations of FA, Cav1.2 and Cav1.3 expression decreased. We conclude that the NO/cGMP signaling pathway and downstream related channels can be regulated by increasing the production of NO in the low concentration group of FA. High concentration FA directly regulates L-Ca22+ channels.

Conclusion

This study suggests that FA damages the function of the cardiovascular system by regulating the NO/cGMP signaling pathway and L-Ca2+ channels.

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.

Formaldehyde causes an increase in blood pressure by activating ACE/AT1R axis

Previous studies suggest some link between formaldehyde exposure and harmful cardiovascular effects. But whether exposure to formaldehyde can cause blood pressure to rise, and if so, what the underlying mechanism is, remains unclear. In this study, C57BL/6 male mice were exposed to 0.1, 0.5, 2.5 mg/m³ of gaseous formaldehyde for 4 h daily over a three-week period. The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) of the mice were measured by tail-cuff plethysmography, and any histopathological changes in the target organs of hypertension were investigated. The results showed that exposure to formaldehyde did cause a significant increase in blood pressure and heart rate, and resulted in varying degrees of damage to the heart, aortic vessels and kidneys. To explore the underlying mechanism, a specific inhibitor of angiotensin converting enzyme (ACE) was used to block the ACE/AT1R axis. We observed the levels of ACE and angiotensin II type 1 receptor (AT1R), as well as the bradykinin (BK) in cardiac cytoplasm. The data suggest that exposure to formaldehyde induced an increase in the expression of ACE and AT1R, and decreased the levels of BK. Strikingly, treatment with 5 mg/kg/d ACE inhibitor can attenuate the increase in blood pressure and the pathological changes caused by formaldehyde exposure. This result has improved our understanding of whether, and how, formaldehyde exposure affects the development of hypertension.

Comprehensive profile of circRNAs in formaldehyde induced heart development

Circular RNAs (circRNAs) are a novel type of long non-coding RNAs that can regulate gene expression in heart development and heart disease. However, the expression pattern of circRNAs in congenital heart disease (CHD) induced by formaldehyde exposure is still unknown. We detected circRNAs expression profiles in heart tissue taken from six neonatal rat pups with formaldehyde exposure group and normal group using RNA-sequencing. Results revealed that a total of 54 circRNAs were dysregulated in the formaldehyde exposure group compared to the normal group. Among them, 31 were upregulated and 23 were downregulated (fold change = 2.0, p < 0.0 5). The qRT-qPCR results showed that expressions of 12:628708|632694, 18:77477060|77520779, 5:167486001|167526275 were significantly upregulated, while that of 7:41167312|4116775 and 20:50659751|5068786 were notably downregulated; the expression pattern was consistent with the RNA sequencing data. Bioinformatics analysis shows that the pathogenesis of formaldehyde exposure-induced CHD may involve Hippo-YAP pathway、Notch signaling pathway and other pathways. A key miRNA (rno-miR-665) was identified by constructing a circRNA-miRNA-mRNA co-expression network. In summary, the study illustrated that circRNAs differentially expressed in fetal heart tissues during formaldehyde exposure has potential biological functions and may be a biomarker or therapeutic target for CHD.

miR-153-3p Targets βII Spectrin to Regulate Formaldehyde-Induced Cardiomyocyte Apoptosis

Background: Formaldehyde (FA) is ubiquitous in the environment and can be transferred to the fetus through placental circulation, causing miscarriage and congenital heart disease (CHD). Studies have shown that βII spectrin is necessary for cardiomyocyte survival and differentiation, and its loss leads to heart development defects and cardiomyocyte apoptosis. Additionally, previous studies have demonstrated that miRNA is essential in heart development and remodeling. However, whether miRNA regulates FA-induced CHD and cardiomyocyte apoptosis remains unclear. Methods: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Real-time quantitative PCR (RT-qPCR) and Western blot were performed to examine the level of miR-153-3p, βII spectrin, caspase 7, cleaved caspase7, Bax, Bcl-2 expression in embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Apoptotic cell populations were evaluated by flow cytometry and Tunel. Luciferase activity assay and RNA pull-down assay were used to detect the interaction between miR-153-3p and βII spectrin. Masson's trichrome staining detects the degree of tissue fibrosis. Fluorescence in situ hybridization (FISH) and Immunohistochemistry were used to detect the expression of miR-153-3p and βII spectrin in tissues. Results: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis, our studies indicate that miR-153-3p plays a regulatory role by directly targeting βII spectrin to promote cardiomyocyte apoptosis. miR-153-3p mainly regulates cardiomyocyte apoptosis by regulating the expression of caspase7, further elucidating the importance of apoptosis in heart development. Finally, the results with our animal model revealed that targeting the miR-153-3p/βII spectrin pathway effectively regulated FA-induced damage during heart development. Recovery experiments with miR-153-3p antagomir resulted in the reversal of FA-induced cardiomyocyte apoptosis and fetal cardiac fibrosis. Conclusion: This study investigated the molecular mechanism underpinning the role of βII spectrin in FA-induced CHD and the associated upstream miRNA pathway. The study findings suggest that miR-153-3p may provide a potential target for the clinical diagnosis and treatment of CHD.

Associations between prenatal exposure to volatile organic compounds and neurodevelopment in 12-month-old children: The Japan Environment and Children's Study (JECS)

In recent years, there has been an increase in the number of problems associated with neurodevelopmental disorders in children, and there has been a growing interest in the relationship between environmental chemicals and children's health. The objective of this study was to examine whether an association exists between occupational or environmental prenatal maternal exposure to volatile organic compounds and the risk of neurodevelopmental disorders in children using Japanese translations of the Ages & Stages Questionnaires, Third Edition (J-ASQ-3). An increase in the risk of neurodevelopmental delay in 12-month-old children associated with maternal exposure to formalin or formaldehyde was identified in terms of problem-solving (odds ratio (OR): 1.76, 95% confidence interval (CI): 0.99-3.12) and personal-social skills (OR: 3.32, 95% CI: 1.46-7.55). It is not clear whether or not this tendency is reversible, and whether it is observed past 12 months of age. Further research and a preventive approach are needed.

Iron-dependent apoptosis causes embryotoxicity in inflamed and obese pregnancy

Iron is essential for a healthy pregnancy, and iron supplementation is nearly universally recommended, regardless of maternal iron status. A signal of potential harm is the U-shaped association between maternal ferritin, a marker of iron stores, and risk of adverse pregnancy outcomes. However, ferritin is also induced by inflammation and may overestimate iron stores during inflammation or infection. In this study, we use mouse models to determine whether maternal iron loading, inflammation, or their interaction cause poor pregnancy outcomes. Only maternal exposure to both iron excess and inflammation, but not either condition alone, causes embryo malformations and demise. Maternal iron excess potentiates embryo injury during both LPS-induced acute inflammation and obesity-induced chronic mild inflammation. The adverse interaction depends on TNFα signaling, causes apoptosis of placental and embryo endothelium, and is prevented by anti-TNFα or antioxidant treatment. Our findings raise important questions about the safety of indiscriminate iron supplementation during pregnancy.

The cellular function and molecular mechanism of formaldehyde in cardiovascular disease and heart development

As a common air pollutant, formaldehyde is widely present in nature, industrial production and consumer products. Endogenous formaldehyde is mainly produced through the oxidative deamination of methylamine catalysed by semicarbazide-sensitive amine oxidase (SSAO) and is ubiquitous in human body fluids, tissues and cells. Vascular endothelial cells and smooth muscle cells are rich in this formaldehyde-producing enzyme and are easily damaged owing to consequent cytotoxicity. Consistent with this, increasing evidence suggests that the cardiovascular system and stages of heart development are also susceptible to the harmful effects of formaldehyde. Exposure to formaldehyde from different sources can induce heart disease such as arrhythmia, myocardial infarction (MI), heart failure (HF) and atherosclerosis (AS). In particular, long-term exposure to high concentrations of formaldehyde in pregnant women is more likely to affect embryonic development and cause heart malformations than long-term exposure to low concentrations of formaldehyde. Specifically, the ability of mouse embryos to effect formaldehyde clearance is far lower than that of the rat embryos, more readily allowing its accumulation. Formaldehyde may also exert toxic effects on heart development by inducing oxidative stress and cardiomyocyte apoptosis. This review focuses on the current progress in understanding the influence and underlying mechanisms of formaldehyde on cardiovascular disease and heart development.

Protective effect of hypothermia and vitamin E on spermatogenic function after reduction of testicular torsion in rats

This study was designed to investigate the protective effect of hypothermia and vitamin E on spermatogenic function after reduction of testicular torsion in rats. Ninety-six pure inbred male SD rats were divided into group A, B, C and D according to the principle of body weight and birth similarity, with 24 rats in each group. Four groups of rats were respectively twisted on the left testis to establish unilateral testicular torsion rats. Rats in groups A, B, C, D were respectively given normal saline, hypothermia therapy, vitamin E therapy, and hypothermia and vitamin E therapy. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of the four groups were detected, and the correlation levels of inflammatory factors IL-1β, hs-CRP and related sex hormones luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T) were detected by ELISA. Apoptosis of spermatogenic cells of testis in the four groups was detected by flow cytometry. SOD activity and MDA content in groups B, C and D were significantly higher than those in group A, MDA content was significantly lower than that in group A (P<0.05), SOD activity in group D was higher than that in groups B and C, while MDA content was lower than that in groups B and C (P<0.05). The levels of IL-1β and hs-CRP in group A were much higher than those in groups B, C and D (P<0.05). LH and FSH levels in group A were significantly higher than those in groups B, C and D (P<0.05), and in group D were significantly lower than those in groups B and C (P<0.05). Apoptosis rate of spermatogenic cells in group A was significantly higher than that in groups B, C and D (P<0.05). Hypothermia combined with vitamin E can reverse testicular injury in rats and reduce the apoptosis rate of spermatogenic cells.

Formaldehyde toxicity reports from in vitro and in vivo studies: a review and updated data

Formaldehyde (FA) is a xenobiotic air pollutant and its universal distribution causes a widespread exposure to humans. This review aimed to bring updated information concerning FA toxicity in humans and animals based on in vitro and in vivo studies from 2013 to 2019. Researches were carried out in Pubmed, Scopus, and Science Direct databases to determine the effects of FA exposure on inflammation, oxidative stress and genotoxicity in experimental studies with animals (rats and mice) and humans. Besides, in vitro studies assessing FA cytotoxicity focusing on cell viability and apoptosis in different cell line cultures were reviewed. Studies with humans gave evidence regarding significant deleterious effects on health associated to chronic FA occupational exposure. Evaluations carried out in experimental studies showed toxic effects on different organs as lung, upper respiratory tract, bone marrow and brain as well as in cells. In summary, this study demonstrates that knowing the mechanisms underlying FA toxicity is essential to understand the deleterious effects that this xenobiotic causes on biological systems.