Association between ambient air pollution and blood sex hormones levels in men

The relationship between cooking fuel use and sex hormone levels: A cross-sectional study and Mendelian randomization study

PURPOSE

The aim of this study was to investigate the effect of solid fuel use on serum sex hormone levels. Furthermore, the effects of improved kitchen ventilation and duration of cooking time on the relationship between solid fuel use and serum sex hormone levels will be further explored.

METHODS

In this cross-sectional study, 5386 individuals were recruited. Gender and menopausal status modified associations between solid fuel type and serum sex hormone levels was investigated through generalized linear models and further analyzed by improving kitchen ventilation and length of cooking time on the relationship between solid fuel use and serum sex hormone levels. To identify the causal association, mendelian randomization of two-sample was performed.

RESULTS

In observational analyses, for ln-17-hydroxyprogesterone, ln-testosterone, and ln-androstenedione among premenopausal women, the estimated β and 95 % CI of sex hormone levels for the effect of solid fuel users was -0.337 (-0.657, -0.017), -0.233 (-0.47, 0.005), and - 0.240 (-0.452, -0.028) respectively, and - 0.150 (-0.296, -0.004) in ln-progesterone among postmenopausal women. It was found that combining solid fuels with long cooking periods or no ventilation more effectively reduced testosterone and androstenedione in premenopausal women. We further found the adverse effects of using solid fuel on progesterone, testosterone, and androstenedione levels were enhanced with the increases of PM1, PM2.5, PM10, and NO2. Corresponding genetic, the causal risk effect of solid fuel were - 0.056 (-0.513, 0.4) and 0.026 (-3.495, 3.547) for testosterone levels and sex hormone binding globulin, respectively.

CONCLUSION

Using gas or solid fuel was negatively related to sex hormone levels. A combination of using solid fuels, cooking for a long time, or cooking without ventilation had a stronger effect on sex hormone levels. However, genetic evidence did not support causality for the associations. WHAT IS ALREADY KNOWN ON THIS TOPIC?: The mechanisms underlying these associations household air pollution (HAP) from incomplete combustion of such fuels and occurrence of chronic diseases remained obscure. Recent years, extensive evidences from animal as well as human researches have suggested that progestogen and androgen hormones are involved in the development of diabetes, hypertension, and cardiovascular disease, which indicated that changes in serum progestogen and androgen hormones levels might play a role in these pathological mechanisms. However, limited evidence exists examining the effect of HAP from solid fuel use on serum sex hormone levels.

A comprehensive review on endocrine toxicity of gaseous components and particulate matter in smog

Smog is a form of extreme air pollution which comprises of gases such as ozone, sulfur dioxide, nitrogen and carbon oxides, and solid particles including particulate matter (PM2.5 and PM10). Different types of smog include acidic, photochemical, and Polish. Smog and its constituents are hazardaous to human, animals, and plants. Smog leads to plethora of morbidities such as cancer, endocrine disruption, and respiratory and cardiovascular disorders. Smog components alter the activity of various hormones including thyroid, pituitary, gonads and adrenal hormones by altering regulatory genes, oxidation status and the hypothalamus-pituitary axis. Furthermore, these toxicants are responsible for the development of metabolic disorders, teratogenicity, insulin resistance, infertility, and carcinogenicity of endocrine glands. Avoiding fossil fuel, using renewable sources of energy, and limiting gaseous discharge from industries can be helpful to avoid endocrine disruption and other toxicities of smog. This review focuses on the toxic implications of smog and its constituents on endocrine system, their toxicodynamics and preventive measures to avoid hazardous health effects.

Associations between exposure to air pollution and sex hormones during the menopausal transition

Menopause is a significant milestone in a woman's life, characterized by decreasing estradiol (E2) and increasing follicle-stimulating hormone (FSH) levels. Growing evidence suggests that air pollution may affect reproductive health and disrupt hormone profiles, yet the associations in women undergoing menopausal transition (MT) remains underexplored. We examined the associations between annual air pollutant exposures and repeated measures of E2 and FSH in 1365 women with known final menstrual period (FMP) date from the Study of Women's Health Across the Nation. Air pollution was calculated as the annual averages of 24-h average PM2.5 levels, daily one-hour maximum NO2 levels, and daily 8-h maximum O3 levels. Linear mixed models with piece-wise linear splines were used to model non-linear trajectories of E2 and FSH in three distinct time periods: up to 2 years before the FMP (early MT), within 2 years before and 2 years after FMP (transmenopause), and >2 years post-FMP (postmenopause). In the transmenopausal period, an interquartile (5 μg/m3) increase in PM2.5 was associated with a significant decrease in E2 levels (-15.7 %, 95 % CI: -23.7, -6.8), and a 10 ppb increase in NO2 was associated with a significant decrease in E2 levels (-9.2 %, 95 % CI: -16.2, -1.7). A higher PM2.5 was also associated with an accelerated rate of decline in E2. Regarding FSH, a 10 ppb increase in NO2 was associated with decline in FSH levels (-11.7 %, 95 % CI: -21.8, -0.1) in the early MT and accelerated rates of decline in the postmenopause (-1.1 % per year, 95 % CI: -2.1, -0.1). Additionally, inverse associations between O3 and FSH were observed in the transmenopause and postmenopause. Our study suggests that increases in PM2.5, NO2, and O3 exposures are linked to significant declines in E2 and FSH levels across menopausal stages, suggesting the detrimental impact of air pollutants on women's reproductive hormones.

Adverse effects of exposure to petrol-generator exhaust fumes on the reproductive hormones, testis and spermatozoa in male dogs

There is evidence that sperm count has progressively declined in men over the recent decades. Exposure to air pollutants including petrol and diesel exhaust have been reported to impair male reproduction although there is little experimental evidence. This study investigated the effects of petrol-generator exhaust fumes (PGEF) on semen, sperm, gonadal structure and hormonal status in the dog. Sixteen adult male Basenji dogs were randomly assigned four to each of 4 groups as follows: an unexposed (Control) group and three groups exposed to graded levels of PGEF for 1, 2 or 3 h per day (hpd), respectively, for 90 days. Serum concentrations of testosterone (T), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured on days 0 (baseline), 30, 60 and 90 of the study. At day 90, semen samples were collected for semen and sperm analysis. Testicular and epididymal tissues were subjected to gross, histopathological and histomorphometric evaluation. Graded exposure to PGEF resulted in increased serum concentration of T and decreased concentrations of FSH and LH, increased seminal plasma lipid peroxidation, seminiferous and epididymal tubular degeneration, germ cell depletion, lowered sperm concentration, decreased sperm motility and vitality, and increased sperm abnormal morphology. The close proximity between dogs and humans in exposed environments underscores the importance of these findings to human reproductive health and fertility. The findings suggest that with prolonged exposure, the impairment of reproductive functions will likely play significant roles in the decline in male fertility.

Implications of Exposure to Air Pollution on Male Reproduction: The Role of Oxidative Stress

Air pollution, either from indoor (household) or outdoor (ambient) sources, occurs when there is presence of respirable particles in the form of chemical, physical, or biological agents that modify the natural features of the atmosphere or environment. Today, almost 2.4 billion people are exposed to hazardous levels of indoor pollution, while 99% of the global population breathes air pollutants that exceed the World Health Organization guideline limits. It is not surprising that air pollution is the world's leading environmental cause of diseases and contributes greatly to the global burden of diseases. Upon entry, air pollutants can cause an increase in reactive oxygen species (ROS) production by undergoing oxidation to generate quinones, which further act as oxidizing agents to yield more ROS. Excessive production of ROS can cause oxidative stress, induce lipid peroxidation, enhance the binding of polycyclic aromatic hydrocarbons (PAHs) to their receptors, or bind to PAH to cause DNA strand breaks. The continuous and prolonged exposure to air pollutants is associated with the development or exacerbation of pathologies such as acute or chronic respiratory and cardiovascular diseases, neurodegenerative and skin diseases, and even reduced fertility potential. Males and females contribute to infertility equally, and exposure to air pollutants can negatively affect reproduction. In this review, emphasis will be placed on the implications of exposure to air pollutants on male fertility potential, bringing to light its effects on semen parameters (basic and advanced) and male sexual health. This study will also touch on the clinical implications of air pollution on male reproduction while highlighting the role of oxidative stress.

Endocrine-disrupting chemicals and male reproductive health

Modifiable factors, such as environmental exposures, can impact human fertility. The objective of this review is to summarize the potential effects of exposure to important endocrine-disrupting chemicals on male reproductive health. Most experimental and animal data demonstrate strong evidence for the negative effects of exposure to phenols, phthalates, pesticides, and perfluoroalkyl and polyfluoroalkyl substances on male reproductive health. Although evidence of negative associations in humans was overall strong for phthalates and pesticides, limited and inconclusive relationships were found for the other examined chemical biomarkers. Reasons for the discrepancies in results include but are not limited to, differences in study populations, exposure concentrations, number of samples collected, sample sizes, study design, and residual confounding. Additional studies are needed, particularly for newer phenols and perfluoroalkyl and polyfluoroalkyl substances, given the scarce literature on the topic and increasing exposures over time.

Effects of external environment on promoter methylation of PIK3R5 and related pathway regulation in steroid-induced femoral head necrosis

BACKGROUND

Steroid-induced Avascular Necrosis of the Femoral Head (SANFH) is a condition characterized by the necrosis of the femoral head caused by long-term or high-dose hormone usage. Studies have shown that the PI3K/AKT pathway plays a crucial regulatory role in the development of SANFH. The aim of this study is to determine how external environmental factors induce changes in endogenous hormone levels, how these changes lead to steroid-induced femoral head necrosis, and the interrelationship between the changes in PIK3R5 promoter methylation levels and the regulation of the associated signaling pathways.

METHODS

Femoral head samples underwent molecular sequencing analysis. Candidate genes were screened by differential gene analysis and functional enrichment analysis.Methylation level of candidate gene PIK3R5 was verified by methylation-specific PCR(MS-PCR). SANFH model was constructed in New Zealand white rabbits, and the model results were verified by magnetic resonance imaging (MRI) and haematoxylin-eosin (HE) staining.The expression of PIK3R5, PI3K and AKT in rabbit models and human specimens was verified by real-time fluorescence quantitative PCR(RT-qPCR) and Western Blot(WB), respectively.

RESULTS

Human femoral head sequencing results indicate distinct differences in the methylation level and mRNA expression of PIK3R5 in SANFH. MS-PCR results showed the methylation level of SANFH patients was significantly higher than that of the control group (P < 0.01). The RT-qPCR results showed that PIK3R5 and PI3K expression levels in the SANFH group were lower than those in the control group (P < 0.05), and the WB experiment results were consistent with the RT-qPCR results. The MRI and HE staining results showed that the rabbit model of SANFH was successfully constructed, and the results of RT-qPCR and WB were consistent with the results of human tissues.

CONCLUSION

During the occurrence and development of SANFH, PIK3R5 gene regulates the PI3K/AKT pathway through methylation modification, promotes the oxidative stress response of cells, and accelerates the disease process.

The association between newborn cord blood steroids and ambient prenatal exposure to air pollution: findings from the ENVIRONAGE birth cohort

Knowledge of whether prenatal exposure to ambient air pollution disrupts steroidogenesis is currently lacking. We investigated the association between prenatal ambient air pollution and highly accurate measurements of cord blood steroid hormones from the androgenic pathway.This study included 397 newborns born between the years 2010 and 2015 from the ENVIRONAGE cohort in Belgium of whom six cord blood steroid levels were measured: 17α-hydroxypregnenolone, 17α-hydroxyprogesterone, dehydroepiandrosterone, pregnenolone, androstenedione, and testosterone. Maternal ambient exposure to PM2.5 (particles with aerodynamic diameter ≤ 2.5 μm), NO2, and black carbon (BC) were estimated daily during the entire pregnancy using a high-resolution spatiotemporal model. The associations between the cord blood steroids and the air pollutants were tested and estimated by first fitting linear regression models and followed by fitting weekly prenatal exposures to distributed lag models (DLM). These analyses accounted for possible confounders, coexposures, and an interaction effect between sex and the exposure. We examined mixture effects and critical exposure windows of PM2.5, NO2 and BC on cord blood steroids via the Bayesian kernel machine regression distributed lag model (BKMR-DLM).An interquartile range (IQR) increment of 7.96 µg/m3 in PM2.5 exposure during pregnancy trimester 3 was associated with an increase of 23.01% (99% confidence interval: 3.26-46.54%) in cord blood levels of 17α-hydroxypregnenolone, and an IQR increment of 0.58 µg/m³ in BC exposure during trimester 1 was associated with a decrease of 11.00% (99% CI: -19.86 to -0.012%) in cord blood levels of androstenedione. For these two models, the DLM statistics identified sensitive gestational time windows for cord blood steroids and ambient air pollution exposures, in particular for 17α-hydroxypregnenolone and PM2.5 exposure during trimester 3 (weeks 28-36) and for androsterone and BC exposure during early pregnancy (weeks 2-13) as well as during mid-pregnancy (weeks 18-26). We identified interaction effects between pollutants, which has been suggested especially for NO2.Our results suggest that prenatal exposure to ambient air pollutants during pregnancy interferes with steroid levels in cord blood. Further studies should investigate potential early-life action mechanisms and possible later-in-life adverse effects of hormonal disturbances due to air pollution exposure.

Impacts and potential mechanisms of fine particulate matter (PM2.5) on male testosterone biosynthesis disruption

Exposure to PM2.5 is the most significant air pollutant for health risk. The testosterone level in male is vulnerable to environmental toxicants. In the past, researchers focused more attention on the impacts of PM2.5 on respiratory system, cardiovascular system, and nervous system, and few researchers focused attention on the reproductive system. Recent studies have reported that PM2.5 involved in male testosterone biosynthesis disruption, which is closely associated with male reproductive health. However, the underlying mechanisms by which PM2.5 causes testosterone biosynthesis disruption are still not clear. To better understand its potential mechanisms, we based on the existing scientific publications to critically and comprehensively reviewed the role and potential mechanisms of PM2.5 that are participated in testosterone biosynthesis in male. In this review, we summarized the potential mechanisms of PM2.5 triggering the change of testosterone level in male, which involve in oxidative stress, inflammatory response, ferroptosis, pyroptosis, autophagy and mitophagy, microRNAs (miRNAs), endoplasmic reticulum (ER) stress, and N6-methyladenosine (m6A) modification. It will provide new suggestions and ideas for prevention and treatment of testosterone biosynthesis disruption caused by PM2.5 for future research.

1-Nitropyrene disrupts testicular steroidogenesis via oxidative stress-evoked PERK-eIF2α pathway

Our previous study showed 1-Nitropyrene (1-NP) exposure disrupted testicular testosterone synthesis in mouse, but the exact mechanism needs further investigation. The present research found 4-phenylbutyric acid (4-PBA), an endoplasmic reticulum (ER) stress inhibitor, recovered 1-NP-induced ER stress and testosterone synthases reduction in TM3 cells. GSK2606414, a protein kinase-like ER kinase (PERK) kinase inhibitor, attenuated 1-NP-induced PERK-eukaryotic translation initiation factor 2α (eIF2α) signaling activation and downregulation of steroidogenic proteins in TM3 cells. Both 4-PBA and GSK2606414 attenuated 1-NP-induced steroidogenesis disruption in TM3 cells. Further studies used N-Acetyl-L-cysteine (NAC) as a classical antioxidant to explore whether oxidative stress-activated ER stress mediated 1-NP-induced testosterone synthases reduction and steroidogenesis disruption in TM3 cells and mouse testes. The results showed NAC pretreatment mitigated oxidative stress, and subsequently attenuated ER stress, particularly PERK-eIF2α signaling activation, and downregulation of testosterone synthases in 1-NP-treated TM3 cells. More importantly, NAC extenuated 1-NP-induced testosterone synthesis in vitro and in vivo. The current work indicated that oxidative stress-caused ER stress, particularly PERK-eIF2α pathway activation, mediates 1-NP-downregulated steroidogenic proteins and steroidogenesis disruption in TM3 cells and mouse testes. Significantly, the current study provides a theoretical basis and demonstrates the experimental evidence for the potential application of antioxidant, such as NAC, in public health prevention, particularly in 1-NP-induced endocrine disorder.

Association of PM2.5 Components with Acceleration of Aging: Moderating Role of Sex Hormones

Fine particulate matter (PM_2.5) has been linked to aging risk, and a lack of knowledge about the relationships between PM_2.5 components and aging risk impeded the development of healthy aging. Participants were recruited through a multicenter cross-sectional study in the Beijing-Tianjin-Hebei region in China. Middle-age and older males and menopausal women completed the collection of basic information, blood samples, and clinical examinations. The biological age was estimated by Klemera-Doubal method (KDM) algorithms based on clinical biomarkers. Multiple linear regression models were applied to quantify the associations and interactions while controlling for confounders, and a restricted cubic spline function estimated the corresponding dose-response curves of the relationships. Overall, KDM-biological age acceleration was associated with PM_2.5 component exposure over the preceding year in both males and females, with calcium [females: 0.795 (95% CI: 0.451, 1.138); males: 0.712 (95% CI: 0.389, 1.034)], arsenic [females: 0.770 (95% CI: 0.641, 0.899); males: 0.661 (95% CI: 0.532, 0.791)], and copper [females: 0.401 (95% CI: 0.158, 0.644); males: 0.379 (95% CI: 0.122, 0.636)] having greater estimates of the effect than total PM_2.5 mass. Additionally, we observed that the associations of specific PM_2.5 components with aging were lower in the higher sex hormone scenario. Maintaining high levels of sex hormones may be a crucial barrier against PM_2.5 component-related aging in the middle and older age groups.