Association of barium deficiency with Type 2 diabetes mellitus incident risk was mediated by mitochondrial DNA copy number (mtDNA-CN): A follow-up study.

Accumulating evidence indicates that plasma metals levels may associate with Type 2 diabetes mellitus (T2DM) incident risk. Mitochondrial function such as mitochondrial DNA copy number (mtDNA-CN) might be linked metal exposure and physiological metabolism. Mediation analysis was conducted to determine the mediating roles of mtDNA-CN in the associations of plasma metals with diabetes risk. In the present study, we investigated associations between plasma metals levels, mtDNA-CN and T2DM incident in elderly population with 6-year follow-up (2 times) study. Ten plasma metals (i.e. manganese (Mg), aluminium (Al), calcium (Ca), ferrum (Fe), barium (Ba), arsenic (As), copper (Cu), selenium (Se), titanium (Ti) and cesium (Sr) were measured by using inductively coupled plasma mass spectrometry (ICP-MS). Mitochondrial DNA copy number was measured by real-time PCR. Multivariable linear regression and logistic regression models were carried out to estimate the relationship between plasma metal concentrations, mtDNA-CN and T2DM incident risk in the current work. Plasma Ba deficiency and mtDNA-CN decline associated with T2DM incident risk during aging process. Meanwhile plasma Ba found to be positively associated with mtDNA-CN. Mitochondrial function mtDNA-CN demonstrated mediating effects in association between plasma Ba deficiency and T2DM incident risk, and 49.8% of the association was mediated by mtDNA-CN. These findings extend the knowledge of T2DM incident risk factors and highlight the point that mtDNA-CN may be linked metals element and T2DM incident risk.

Comparative steroidogenic effects of hexafluoropropylene oxide trimer acid (HFPO-TA) and perfluorooctanoic acid (PFOA): Regulation of histone modifications.

As a widely used alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been detected in the environment and humans; however, little is known regarding its male reproductive toxicity. To compare the effects of HFPO-TA on steroid hormone synthesis with PFOA, we exposed Leydig cells (MLTC-1) to non-lethal doses (0.1, 1, and 10 µM) of PFOA and HFPO-TA for 48 h. It was found that the levels of steroid hormones, 17α-hydroxyprogesterone (OHP), androstenedione (ASD), and testosterone (T) were significantly increased in 1 and 10 µM of PFOA and HFPO-TA groups, with greater elevation being observed in the HFPO-TA groups than in the PFOA groups at 10 µM. We further showed that the two rate-limiting steroidogenic genes (Star and Cyp11a1) were up-regulated, while Hsd3b, Cyp17a1, and Hsd17b were down-regulated or unchanged after PFOA/HFPO-TA exposure. Moreover, PFOA exposure significantly up-regulated histone H3K4me1/3 and H3K9me1, while down-regulated H3K4me2 and H3K9me2/3 levels. By contrast, H3K4me2/3 and H3K9me2/3 were enhanced, while H3K4me1 and H3K9me1 were repressed after HFPO-TA treatment. It was further confirmed that H3K4me1/3 were increased and H3K9me2 was decreased in Star and Cyp11a1 promoters by PFOA, while HFPO-TA increased H3K4me2/3 and decreased H3K9me1 in the two gene promoters. Therefore, we propose that low levels of PFOA/HFPO-TA enhance the expression of Star and Cyp11a1 by regulating H3K4 and H3K9 methylation, thus stimulating the production of steroid hormones in MLTC-1 cells. Collectively, HFPO-TA exhibits stronger effects on steroidogenesis compared to PFOA, which may be ascribed to the distinct regulation of histone modifications. These data suggest that HFPO-TA does not appear to be a safer alternative to PFOA on the aspect of male reproductive toxicity.

Transgenerational Effects of Arsenic Exposure on Learning and Memory in Rats: Crosstalk between Arsenic Methylation, Hippocampal Metabolism, and Histone Modifications.

Arsenic (As) is widely present in the natural environment, and exposure to it can lead to learning and memory impairment. However, the underlying epigenetic mechanisms are still largely unclear. This study aimed to reveal the role of histone modifications in environmental levels of arsenic (sodium arsenite) exposure-induced learning and memory dysfunction in male rats, and the inter/transgenerational effects of paternal arsenic exposure were also investigated. It was found that arsenic exposure impaired the learning and memory ability of F0 rats and down-regulated the expression of cognition-related genes Bdnf, c-Fos, mGlur1, Nmdar1, and Gria2 in the hippocampus. We also observed that inorganic arsenite was methylated to DMA and histone modification-related metabolites were altered, contributing to the dysregulation of H3K4me1/2/3, H3K9me1/2/3, and H3K4ac in rat hippocampus after exposure. Therefore, it is suggested that arsenic methylation and hippocampal metabolism changes attenuated H3K4me1/2/3 and H3K4ac while enhancing H3K9me1/2/3, which repressed the key gene expressions, leading to cognitive impairment in rats exposed to arsenic. In addition, paternal arsenic exposure induced transgenerational effects of learning and memory disorder in F2 male rats through the regulation of H3K4me2 and H3K9me1/2/3, which inhibited c-Fos, mGlur1, and Nmdar1 expression. These results provide novel insights into the molecular mechanism of arsenic-induced neurotoxicity and highlight the risk of neurological deficits in offspring with paternal exposure to arsenic.

Exposure to haloacetic acid disinfection by-products and male steroid hormones: An epidemiological and in vitro study.

Haloacetic acids (HAAs) are ubiquitous in drinking water and have been associated with impaired male reproductive health. However, epidemiological evidence exploring the associations between HAA exposure and reproductive hormones among males is scarce. In the current study, the urinary concentrations of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), the internal exposure markers of HAAs, as well as sex hormones (testosterone [T], progesterone [P], and estradiol [E2]) were measured among 449 Chinese men. Moreover, in vitro experiments, designed to simulate the real-world scenarios of human exposure, were conducted to assess testosterone synthesis in the Leydig cell line MLTC-1 and testosterone metabolism in the hepatic cell line HepG2 in response to low-dose HAA exposure. The DCAA and TCAA urinary concentrations were found to be positively associated with urinary T, P, and E2 levels (all p < 0.001), but negatively associated with the ratio of urinary T to E2 (p < 0.05). Combined with in vitro experiments, the results suggest that environmentally-relevant doses of HAA stimulate sex hormone synthesis and steroidogenesis pathway gene expression in MLTC-1 cells. In addition, the inhibition of the key gene CYP3A4 involved in the testosterone phase Ⅰ catabolism, and induction of the gene UGT2B15 involved in testosterone phase Ⅱ glucuronide conjugation metabolism along with the ATP-binding cassette (ABC) transport genes (ABCC4 and ABCG2) in HepG2 cells could play a role in elevation of urinary hormone excretion upon low-dose exposure to HAAs. Our novel findings highlight that exposure to HAAs at environmentally-relevant concentrations is associated with increased synthesis and excretion of sex hormones in males, which potentially provides an alternative approach involving urinary hormones for the noninvasive evaluation of male reproductive health following exposure to DBPs.

The size-dependence and reversibility of polystyrene nanoplastics-induced lipid accumulation in mice: Possible roles of lysosomes.

Nanoplastics (NPs) continue to accumulate in global aquatic and terrestrial systems, posing a potential threat to human health through the food chain and/or other pathways. Both in vivo and in vitro studies have confirmed that the liver is one of the main organs targeted for the accumulation of NPs in living organisms. However, whether exposure to NPs induces size-dependent disorders of liver lipid metabolism remains controversial, and the reversibility of NPs-induced hepatotoxicity is largely unknown. In this study, the effects of long-term exposure to environmentally relevant doses of polystyrene nanoplastics (PS-NPs) on lipid accumulation were investigated in terms of autophagy and lysosomal mechanisms. The findings indicated that hepatic lipid accumulation was more pronounced in mice exposed to 100 nm PS-NPs compared to 500 nm PS-NPs. This effect was effectively alleviated after 50 days of self-recovery for 100 nm and 500 nm PS-NPs exposure. Mechanistically, although PS-NPs exposure activated autophagosome formation through ERK (mitogen-activated protein kinase 1)/mTOR (mechanistic target of rapamycin kinase) signaling pathway, the inhibition of Rab7 (RAB7, member RAS oncogene family), CTSB (cathepsin B), and CTSD (cathepsin D) expression impaired lysosomal function, thereby blocking autophagic flux and contributing to hepatic lipid accumulation. After termination of PS-NPs exposure, lysosomal exocytosis was responsible for the clearance of PS-NPs accumulated in lysosomes. Furthermore, impaired lysosomal function and autophagic flux inhibition were effectively alleviated. This might be the main reason for the alleviation of PS-NPs-induced lipid accumulation after recovery. Collectively, we demonstrate for the first time that lysosomes play a dual role in the persistence and reversibility of hepatotoxicity induced by environmental relevant doses of NPs, which provide novel evidence for the prevention and intervention of liver injury associated with nanoplastics exposure.

Profiles and transplacental transfer of per- and polyfluoroalkyl substances in maternal and umbilical cord blood: A birth cohort study in Zhoushan, Zhejiang Province, China.

Per- and polyfluoroalkyl substances (PFAS) can pass through the placental barrier and pose health risks to fetuses. However, exposure and transplacental transfer patterns of emerging PFAS remain unclear. Here, 24 PFAS were measured in paired maternal whole blood (n = 228), umbilical cord whole blood (n = 119) and serum (n = 120). Orthogonal partial least-squares discriminant analysis (OPLS-DA) was used to differentiate PFAS between different matrices. The transplacental transfer (TPT) of PFAS was calculated using cord to maternal whole blood concentration ratios. PFOS and PFOA were still the dominant PFAS in maternal samples. The emerging PFAS had higher TPT than PFOS and PFOA. Moreover, PFAS with the same chain length but different functional groups and C-F bonds showed different TPT, such as PFOS and PFOSA (C8, median: 0.090 vs. 0.305, p < 0.05) and PFHxS and 4:2 FTS (C6, median: 0.220 vs. 1.190, p < 0.05). A significant sex difference in 4:2 FTS (median: boys 1.250, girls 1.010, p < 0.05) were found. Furthermore, we observed a significant U-shaped trend for the TPT of carboxylates with increasing carbon chain length. PFAS showed a compound-specific transfer through placental barrier and a compound-specific distribution between different matrices in this study.

Metabolic biomarkers linking urinary arsenic species to gestational diabetes mellitus: A cross-sectional study in Chinese pregnant women.

Environmental arsenic (As) exposure has been associated with gestational diabetes mellitus (GDM) risk. Our recent study found that GDM was positively associated with urinary As3+ level while negatively correlated to As5+. However, the mechanisms underlying the association between arsenic species and GDM remain largely unknown. In the present study, through the measurement of urinary arsenic species and metabolome analysis in 399 pregnant women, we aimed to identify the metabolic biomarkers that may link arsenic exposure to GDM based on a novel systems epidemiology strategy termed meet-in-metabolite-analysis (MIMA). The metabolomics analysis revealed that 20 and 16 urinary metabolites were relevant to arsenic exposure and GDM, respectively. Among them, 12 metabolites were identified to be both arsenic- and GDM-related, which are mainly involved in purine metabolism, one­carbon metabolism (OCM) and glycometabolism. Moreover, it was further showed that the regulation of thiosulfate (AOR: 2.52; 95 % CI: 1.33, 4.77) and phosphoroselenoic acid (AOR: 2.35; 95 % CI: 1.31, 4.22) could significantly contribute to the negative association between As5+ and GDM. Considering the biological functions of these metabolites, it is suggested that As5+ may reduce GDM risk by disturbing OCM in the pregnant women. These data will provide novel insights into the mechanism of action of environmental arsenic exposure on GDM incidence from the aspect of metabolism disorder.

Atmospheric PM2.5 induce autophagy and autophagic flux blockage in HUVEC cells via ROS/TXNIP signaling: Important role of metal components.

Autophagy was involved in vascular endothelial injury caused by PM2.5, which aggravated the pathogenesis of cardiovascular diseases. However, major toxic components and underlying mechanism responsible for PM2.5-induced autophagy remain unclear. In this study, the effects of water-extracted PM2.5 (WE-PM2.5) on autophagy in human umbilical vein endothelial cells (HUVEC) were studied. Our results showed WE-PM2.5 promoted autophagosome initiation and formation, meanwhile, lysosomal function was impaired, which further caused autophagic flux blockage in HUVEC cells. Furthermore, removal of metals alleviated WE-PM2.5-induced autophagic flux blockage, while the artificial metal mixture reproduced the WE-PM2.5 response. Mechanistically, ROS regulated autophagy-related proteins evidenced by BECN1, LC3B and p62 expression reversed by NAC pretreatment in WE-PM2.5-exposed cells. WE-PM2.5 also increased TXNIP expression mediated by ROS; moreover, knockdown of TXNIP in WE-PM2.5-exposed cells decreased BECN1 and LC3B expression, but had little effects on the expression of p62, CTSB, and CTSD, indicating WE-PM2.5-induced TXNIP was involved in autophagosome initiation and formation rather than autophagic degradation. Collectively, WE-PM2.5-induced ROS not only promoted autophagosome initiation and formation, but also inhibited autophagic degradation. However, as the downstream molecule of ROS, TXNIP was only involved in autophagosome initiation and formation. Importantly, WE-PM2.5-bound metals were largely responsible for autophagic flux blockage in HUVEC cells.

Internalization and cytotoxicity of polystyrene microplastics in human umbilical vein endothelial cells.

Ubiquitous micro(nano)plastics (MNPs) are emerging environmental pollutants, which pose a potential threat to human health. When MNPs enter the blood circulatory system, vascular endothelium is one of the most important target organs that directly interact with the MNPs. However, little is known about the cytotoxicity of MNPs to vascular endothelial cells. In this study, we investigated the uptake and cytotoxic effects of polystyrene MNPs with a particle size of 1 µm (1-µm PS-MNPs) on human umbilical vein endothelial cells (HUVECs) in vitro. Our study found that interaction between HUVECs and 1-µm PS-MNPs was at a very low level. Even at the high exposure concentration of 25 µg/mL, the percentage of HUVECs combined with fluorescent 1-µm PS-MNPs was only 3.80% using flow cytometry analysis. Moreover, there were no significant differences in inflammation, autophagy, reactive oxygen species (ROS) level, lactate dehydrogenase (LDH) release, and adhesion molecule expression following exposure to 1-µm PS-MNPs (5, 10, and 25 µg/mL) for 48 h, except for a remarkable decrease in cell viability at the extremely high concentration of 100 µg/mL. Herein, 1-µm PS-MNPs showed a low level of acute toxicity to HUVECs in vitro, and we expect these results contribute to the further risk assessment of MNPs on human health.

Associations of environmental phthalate exposure with male steroid hormone synthesis and metabolism: An integrated epidemiology and toxicology study.

Humans are simultaneously and constantly exposed to various lipophilic chain phthalate acid esters. The association of urinary phthalate metabolites with altered male steroid hormone synthesis and metabolism was examined using epidemiology and toxicology studies. We measured 8 phthalate metabolites [monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-n-octylphthalate (MOP), mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP)] and two sex hormones [testosterone (T) and estradiol (E2)] in single serum and repeated spot urine samples among 451 reproductive-age males. Moreover, in vitro experiments with Leydig cell MLTC-1 steroidogenesis and liver cell HepG2 efflux in response to mixed and individual phthalates were designed to simulate real-world scenarios of human exposure. As a joint mixture, the phthalate metabolite was inversely associated with serum T and E2 concentrations but positively associated with urinary T and E2 concentrations. Combined with in vitro experiments, DEHP metabolites were identified as the predominant contributor to the decline in hormone synthesis, and ATP-binding cassette (ABC) gene activation might be involved in hormone excretion. Exposure to environmentally relevant phthalates was associated with both altered steroid synthesis and excretion, which provides additional insights into the endocrine-disrupting potential of phthalates.

Low Levels of Perfluorooctanoic Acid Exposure Activates Steroid Hormone Biosynthesis through Repressing Histone Methylation in Rats.

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant, which has endocrine-disrupting properties and can interfere with the synthesis and secretion of testicular steroid hormones, but the underlying molecular mechanisms are still not fully understood. In this study, we investigated the effects of low doses of PFOA exposure on testicular steroidogenesis in rats and revealed the role of histone modifications. It was found that the serum levels of progesterone, testosterone, and estradiol were significantly increased after 0.015 and 0.15 mg/kg of PFOA exposure, and the expression of Star, a key rate-limiting gene, was up-regulated, while other steroidogenic genes Cyp11a1, Hsd3b, Cyp17a1, and Hsd17b were down-regulated. In addition, the levels of multiple histone modifications (H3K9me1/2/3 and H3K9/18/23ac) were all significantly reduced by PFOA in rat testis. Histone H3K9 methylation is associated with gene silencing, while histone acetylation leads to gene activation. ChIP analysis further showed that H3K9me1/3 was significantly decreased in the promoter region of Star, while H3K18ac levels were down-regulated in other gene promoters. Accordingly, we suggest that low-level PFOA enhances StAR expression through the repression of H3K9me1/3, which stimulates steroid hormone production in rat testis. These results are expected to shed new light on the molecular mechanisms by which low-dose PFOA disturbs male reproductive endocrine from an epigenetic aspect and may be useful for human health risk assessment regarding environmental PFOA exposure.

Direct identification and visualisation of real-world contaminating microplastics using Raman spectral mapping with multivariate curve resolution-alternating least squares.

Microplastics (MPs) contamination is ubiquitous in environmental matrices worldwide. Moreover these pollutants can be ingested by organisms and transported to organs via the circulatory system. Although efficient methods for the analysis of MPs derived from environment matrices and organisms' tissue samples have been developed after special sample pre-treatment, there remains a need for an optimised approach allowing direct identification and visualisation these MPs in real environmental matrices and organismal samples. Herein, we firstly used a multivariate curve resolution-alternating least squares (MCR-ALS) analysis of Raman hyperspectral imaging data to direct identification and visualisation of MPs in a complex serum background. Four common MPs types including polyethylene (PE), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET) were identified and visualised either individually or in mixtures within spiked samples at an 8-µm spatial resolution. Moreover, Raman imaging based on MCR-ALS was successfully applied in fish faeces biological samples and environmental sand samples for in situ MPs identification directly without washing or removal of organic matter. The current results demonstrate Raman imaging based on MCR-ALS as a novel imaging approach for direct identification and visualisation of MPs, through extraction of MPs' chemical spectra within a complicated biological or environmental background whilst eliminating overlapping Raman bands and fluorescence interference.

Low-dose perfluorooctanoic acid stimulates steroid hormone synthesis in Leydig cells: Integrated proteomics and metabolomics evidence.

Perfluorooctanoic acid (PFOA), one of the well-known perfluoroalkyl substances (PFASs), has been widespread in the environment and associated with male reproductive toxicity. However, the molecular mechanism involved in low-level PFOA-induced male endocrine disruption remains to be elucidated. In this study, we performed a combined proteomics and metabolomics analysis to investigate the proteomic and metabolic alterations in MLTC-1 Leydig cells responsive to low levels of PFOA exposure. The results showed that PFOA significantly regulated the expressions of 67 proteins and 17 metabolites, among which 18 proteins and 7 metabolites were specifically tied to lipid and fatty acid metabolism as well as testicular steroidogenesis. It is further suggested that low-dose PFOA stimulates steroid hormone synthesis by accelerating fatty acid metabolism and steroidogenic process, which is involved in the repression of p38 and cAMP-dependent ERK signaling pathway. The animal studies also revealed that environmentally relevant levels of PFOA increased serum steroid hormone levels accompanied by the activated cAMP and inhibited p38/ERK pathway in testis, which confirmed our in vitro findings. Overall, the present study will provide novel insights into the toxicological mechanisms of low-level PFOA-mediated steroidogenic disturbance, and may implicate the reproductive health risk of humans with environmental PFOA exposure.

Real-world particulate matters induce lung toxicity in rats fed with a high-fat diet: Evidence of histone modifications.

Exposure to ambient particulate matters (PMs) has been associated with a variety of lung diseases, and high-fat diet (HFD) was reported to exacerbate PM-induced lung dysfunction. However, the underlying mechanisms for the combined effects of HFD and PM on lung functions remain poorly unraveled. By performing a comparative proteomic analysis, the current study investigated the global changes of histone post-translational modifications (PTMs) in rat lung exposed to long-term, real-world PMs. In result, after PM exposure the abundance of four individual histone PTMs (1 down-regulated and 3 up-regulated) and six combinatorial PTMs (1 down-regulated and 5 up-regulated) were significantly altered in HFD-fed rats while only one individual PTM was changed in rats with normal diet (ND) feeding. Histones H3K18ac, H4K8ac and H4K12ac were reported to be associated with DNA damage response, and we found that these PTMs were enhanced by PM in HFD-fed rats. Together with the elevated DNA damage levels in rat lungs following PM and HFD co-exposure, we demonstrate that PM exposure combined with HFD could induce lung injury through altering more histone modifications accompanied by DNA damage. Overall, these findings will augment our knowledge of the epigenetic mechanisms for pulmonary toxicity caused by ambient PM and HFD exposure.

Chronic low-level perfluorooctane sulfonate (PFOS) exposure promotes testicular steroidogenesis through enhanced histone acetylation.

Perfluorooctane sulfonate (PFOS), an artificial perfluorinated compound, has been associated with male reproductive disorders. Histone modifications are important epigenetic mediators; however, the impact of PFOS exposure on testicular steroidogenesis through histone modification regulations remains to be elucidated. In this study, we examined the roles of histone modifications in regulating steroid hormone production in male rats chronically exposed to low-level PFOS. The results indicate that PFOS exposure significantly up-regulated the expressions of StAR, CYP11A1 and 3ß-HSD, while CYP17A1 and 17ß-HSD were down-regulated, thus contributing to the elevated progesterone and testosterone levels. Furthermore, PFOS significantly increased the histones H3K9me2, H3K9ac and H3K18ac while reduced H3K9me3 in rat testis. It is known that histone modifications are closely involved in gene transcription. Therefore, to investigate the association between histone modifications and steroidogenic gene regulation, the levels of these histone marks were further measured in steroidogenic gene promoter regions by ChIP. It was found that H3K18ac was augmented in Cyp11a1 promoter, and H3K9ac was increased in Hsd3b after PFOS exposure, which is proposed to result in the activation of CYP11A1 and 3ß-HSD, respectively. To sum up, chronic low-level PFOS exposure activated key steroidogenic gene expression through enhancing histone acetylation (H3K9ac and H3K18ac), ultimately stimulating steroid hormone biosynthesis in rat testis.

Mussel-inspired adhesive and polypeptide-based antibacterial thermo-sensitive hydroxybutyl chitosan hydrogel as BMSCs 3D culture matrix for wound healing.

Hydrogels have gained great attentions as wound dressing. Binding to the tissue and preventing wound infection were the basic requirements for an "ideal dressing". We employed l-DOPA and ε-Poly-l-lysine to modify thermo-sensitive hydroxybutyl chitosan (HBC) to obtain (l-DOPA) - (ε-Poly-l-lysine)-HBC hydrogels (eLHBC). The eLHBC exhibited an almost 1.5 fold (P < 0.01) increase in wet adhesion strength compared to HBC. Upon the introduction of ε-Poly-l-lysine, eLHBC presented inherent antimicrobial property and prevented wound infection and inflammation response. Bone marrow mesenchymal stem cells (BMSCs) encapsulated in the eLHBC (BMSCs ⊂ eLHBC) could secret cytokins and growth factors via paracrine and promote the migration of fibroblast cells. BMSCs ⊂ eLHBC enhanced the complete skin-thickness wound healing via promoting collagen deposition and inhibiting infection and inflammation in vivo with wound closure rate being above 99 % after 15 days. The bioinspired, tissue-adhesive eLHBC could serve as advanced wound dressings for facilitating tissue repair and regeneration.

Dynamic recovery after acute single fine particulate matter exposure in male mice: Effect on lipid deregulation and cardiovascular alterations.

Many studies have linked airborne fine particulate matter (PM2.5) exposure to cardiovascular diseases. We performed a time-series analysis to investigate whether the disruption of lipid metabolism recovered or lasted after acute PM2.5 exposure in mice. Targeted lipidomic analysis showed that four major plasma membrane phospholipids along with cholesterol esters (CE) were significantly altered on 7th post-exposure day (PED7), and the alteration reached a peak on PED14. On PED21, the phosphatidylcholine (PC) decrease was more marked than on PED14, and its resurgence was indirectly linked to triglyceride (TG) increase. Homocysteine (HCY), lactate dehydrogenase (LDH), and α-hydroxybutyrate dehydrogenase (α-HBDH) levels increased but glucose levels decreased markedly in a dose- and time-dependent manner throughout the experimental period. Network analysis showed that the lasting lipid deregulation on PED21 correlated to myocardial markers and glucose interruption, during which high-density lipoprotein cholesterol (HDL-C) decreased. The present data implied that the constructional membrane lipids were initially interrupted by PM2.5, and the subsequent rehabilitation resulted in the deregulation of storage lipids; the parallel myocardial and glucose effects may be enhanced by the lasting HDL-C lipid deregulation on PED21. These myocardial and lipidomic events were early indicators of cardiovascular risk, resulting from subsequent exposure to and accumulation of PM2.5.

Persistence and reversibility of arsenic-induced gut microbiome and metabolome shifts in male rats after 30-days recovery duration.

The metabolites of gut microbiome are important host-health regulating factors and can be interrupted when the host is exposed to environmental pollutant via ingestion route. Arsenic contaminated drinking water is one of the most serious environmental health problems worldwide. Therefore, the arsenic-induced alterations of gut microbiome and metabolome, especially the persistence and reversibility of the alterations after the long-term arsenic exposure will be interesting to know. In this study, we investigated the relationship between gut microbiota and metabolites in male rats both after the 30-days arsenic treatment and 30-days recovery duration. The composition and diversity of gut microbiota were affected significantly by the treatment, but they presented partial improvement in recovery duration. Moreover, arsenic exposure induced the significant changes of 73 metabolites, which involved in the metabolism of glycerophospholipid, linoleic acid, as well as the biosynthesis of phenylalanine, tyrosine and tryptophan. Although it had a persistent effect, the restoration of glycerophospholipid metabolism was observed in the 30-days recovery. Integration analysis further correlated the arsenic impacting microbes with some important differential metabolites. Lactobacillus associated with the decreases of phosphatidylethanolamine(34:1), 16alpha-hydroxydehydroepiandrosterone 3-sulfate, seryltryptophan and alanyltyrosine in recovery duration. Lactobacillus strains have potential to work as protective agents against arsenic toxicity by restoring perturbed glycerophospholipid metabolism. In summary, arsenic significantly disrupted gut microbiome and metabolome, but the disruptions are reversible to some extent after a 30-days recovery.

Environmental doses of arsenic exposure are associated with increased reproductive-age male urinary hormone excretion and in vitro Leydig cell steroidogenesis.

Humans are ubiquitously exposed to arsenic from multiple sources, and chronic arsenic exposure may be associated with male reproductive health. Although association regarding arsenic exposure and sex hormone secretion in blood has been reported, sex hormone excretion in urine studies is lacking. Urinary sex hormone excretion has emerged as a complementary strategy to evaluate gonadal function. Herein, we determined the associations between environmental exposure to arsenic and urinary sex hormone elimination and in vitro Leydig cell steroidogenesis. Concentrations of arsenic and testosterone (T), estradiol (E2) and progesterone (P) in repeated urine samples were determined among 451 reproductive-age males. Moreover, an in vitro Leydig cell MLTC-1 steroidogenesis experiment was designed to simulate real-world scenarios of low human exposure. Multivariable linear regression models were used to assess the associations of urinary arsenic levels with urinary hormones. Urinary arsenic concentrations were positively associated with urinary sex hormone (T, E2, and P) levels. An in vitro test further demonstrated that a population-based environmental exposure range (0.01-5 µM) of arsenic induced Leydig cell steroidogenesis potency. Our results indicate that low-dose arsenic exposure exhibits an endocrine disrupting effect by stimulating Leydig cell steroidogenesis and accelerating urinary steroid excretion, which extends previous knowledge of the inverse association of high-dose arsenic exposure with sexual steroid production that is assumed to be anti-androgen.

Infantile phthalate metabolism and toxico/pharmacokinetic implications within the first year of life.

BACKGROUND: Infantile development of phthalate metabolism is crucial for risk assessment of endocrine disruption and has important toxico/pharmacokinetic implications. OBJECTIVES: To characterize temporal variability in urinary phthalate metabolites in infants and to examine their growth-dependent detoxification. METHODS: In this cohort study, urine samples (n = 876) from 155 healthy Chinese infants were collected serially at eight time points from birth to one year old. Free and total (i.e., free plus glucuronide conjugated) phthalate metabolites (PMEs) were measured by LC/MS/MS. Time variability in PMEs and PME metabolism capacity was characterized using intraclass correlation coefficients (ICCs) and linear mixed regression models. RESULTS: Concentrations of most PMEs changed significantly, with ICCs ranging from 0.213 to 0.318, and trends increased significantly over time (p < 0.001), while MEHP showed fair reproducibility (ICC = 0.480). Glucuronidation increased considerably (ICC ≤ 0.250; p < 0.001) for most PMEs but not for MMP or MEHP. Ester-chain ω-/ω-1-oxidation and α-/ß-oxidation patterns of MEHP steeply increased from 3 months to 8 months, where they peaked, resulting in a molar percentage of MEHP in ΣDEHP showing the inversion pattern. MEHP detoxification through oxidation of the hydrophobic ester-chain is apparently a priority for carboxyl glucuronidation in infants. CONCLUSIONS: Infant phthalate exposure is prevalent, but they cannot metabolize or eliminate these compounds as efficiently as adults, especially during the first 6 months of life. From an environmental biomonitoring view, age-dependent phthalate metabolism provides crucial implications for infantile ontogeny and health risk assessment within the first year of life.