Shanlei Qiao

Association of exposure to phenols and idiopathic male infertility.

Widespread human exposure to phenols has been documented recently, and some phenols which are potential endocrine disruptors have demonstrated adverse effects on male reproduction in animal and in vitro studies. However, implications about exposure to phenols and male infertility are scarce in humans. Case-control study of 877 idiopathic infertile men and 713 fertile controls was conducted. Urinary levels of bisphenol A, benzophenone-3, pentachlorophenol, triclosan, 4-tert-octylphenol (4-t-OP), 4-n-octylphenol (4-n-OP) and 4-n-nonylphenol (4-n-NP) and semen parameters were measured. After multivariate adjustment, we found 4-t-OP, 4-n-OP and 4-n-NP exposure was associated with idiopathic male infertility (p-value for trend: <0.0001, 0.014 and 0.001, respectively). Aside from these associations, 4-t-OP and 4-n-NP exposure was also associated with idiopathic male infertility with abnormal semen parameters. Moreover, we observed significant associations between sum alkylphenols (APs) exposure and idiopathic male infertility. There were no relationships between exposure to other phenols and idiopathic male infertility in the present study. Our study provides the first evidence that exposure to APs (4-t-OP, 4-n-OP and 4-n-NP) is associated with idiopathic male infertility.

Bisphenol A Alters n-6 Fatty Acid Composition and Decreases Antioxidant Enzyme Levels in Rat Testes: A LC-QTOF-Based Metabolomics Study

Background Male reproductive toxicity induced by exposure to bisphenol A (BPA) has been widely reported. The testes have proven to be a major target organ of BPA toxicity, so studying testicular metabolite variation holds promise for the discovery of mechanisms linked to the toxic effects of BPA on reproduction. Methodology/Principal Findings Male Sprague-Dawley rats were orally administered doses of BPA at the levels of 0, 50 mg/kg/d for 8 weeks. We used an unbiased liquid chromatography-quadrupole time-of-flight (LC-QTOF)-based metabolomics approach to discover, identify, and analyze the variation of testicular metabolites. Two n-6 fatty acids, linoleic acid (LA) and arachidonic acid (AA) were identified as potential testicular biomarkers. Decreased levels of LA and increased levels of AA as well as AA/LA ratio were observed in the testes of the exposed group. According to these suggestions, testicular antioxidant enzyme levels were detected. Testicular superoxide dismutase (SOD) declined significantly in the exposed group compared with that in the non-exposed group, and the glutathione peroxidase (GSH-Px) as well as catalase (CAT) also showed a decreasing trend in BPA treated group. Conclusions/Significance BPA caused testicular n-6 fatty acid composition variation and decreased antioxidant enzyme levels. This study emphasizes that metabolomics brings the promise of biomarkers identification for the discovery of mechanisms underlying reproductive toxicity.

Metabolomic Analysis Reveals Metabolic Changes Caused By Bisphenol A in Rats

Bisphenol A (BPA) is a widely used material known to cause adverse effects in humans and other mammals. To date, little is known about the global metabolomic alterations caused by BPA using urinalysis. Sprague-Dawley rats were orally administrated BPA at the levels of 0, 0.5 μg/kg/day and 50 mg/kg/day covering a low dose and a reference dose for 8 weeks. We conducted a capillary electrophoresis in tandem with electrospray ionization time-of-flight mass spectrometry based nontargeted metabolomic analysis using rat urine. To verify the metabolic alteration at both low and high doses, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were further conducted to analyze hepatic expression of methionine adenosyltransferase Iα (Mat1a) and methionine adenosyltransferase IIα (Mat2a). Hepatic S-adenosylmethionine (SAMe) was also analyzed. A total of 199 metabolites were profiled. Statistical analysis and pathway mapping indicated that the most significant metabolic perturbations induced by BPA were the increased biotin and riboflavin excretion, increased synthesis of methylated products, elevated purine nucleotide catabolism, and increased flux through the choline metabolism pathway. We found significantly higher mRNA and protein levels of Mat1a and Mat2a, and significantly higher SAMe levels in rat liver at both low and high doses. These two genes encode critical isoenzymes that catalyze the formation of SAMe, the principal biological methyl donor involved in the choline metabolism. In conclusion, an elevated choline metabolism is underlying the mechanism of highly methylated environment and related metabolic alterations caused by BPA. The data of BPA-elevated accepted biomarkers of injury indicate that BPA induces DNA methylation damage and broad protein degradation, and the increased deleterious metabolites in choline pathway may also be involved in the toxicity of BPA.

Reproductive hormones in relation to polycyclic aromatic hydrocarbon (PAH) metabolites among non-occupational exposure of males.

A limited number of studies have suggested that exposure to PAHs may affect reproductive hormones. Subjects (n=642) in this study were from the affiliated hospitals of Nanjing Medical University. Individual exposures to PAHs were measured as spot urinary concentrations of four PAH metabolites, including 1-naphthol (1-N), 2-naphthol (2-N), 2-hydroxyfluorene (2-OF) and 1-hydroxypyrene (1-OP), which were adjusted by urinary creatinine (CR). Blood samples were collected to measure serum levels of reproductive hormones, including follicle-stimulating hormone (FSH), luteotrophic hormone (LH), estradiol (E2), testosterone (T) and prolactin (PRL). All of the subjects had detectable levels of the four metabolites of PAHs in their urine samples. The median concentrations of 1-N, 2-N, 2-OF and 1-OP were 2.440, 4.176, 2.843 and 1.148 microg/g of CR. There were significant P-values between increased CR-adjusted 1-N tertiles and E2 concentration, 2-OF tertiles and LH, FSH level, 1-OP and E2 level. The multivariate linear regression results also showed significant correlation between the levels of serum LH and 1-OP (the adjusting P-value was 0.048), but no correlations were found between other hormones and the level of PAH metabolites. These observed correlations between levels of hydroxy-PAH and some altered hormones indicated slight endocrine effects on adult men with PAH exposure.

Relationship between urinary metabolites of polycyclic aromatic hydrocarbons and thyroid hormone levels in Chinese non-occupational exposure adult males.

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous global pollutants. Limited studies suggested that PAH may interfere with thyroid function in animals, but little is known about humans. A population of 480 Chinese males was recruited. Using LC-MS/MS, four urinary metabolites of PAH including 1-hydroxynaphthalene (1-N), 2-hydroxynaphthalene (2-N), 1-hydroxypyrene (1-P) and 2-hydroxyfluorene (2-F) were measured in spot urinary samples, which were adjusted by urinary creatinine (CR). Blood samples were collected for measuring serum levels of thyroid hormones including total thyroxine (TT4), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH). The median CR-adjusted urine PAH concentrations of 1-N, 2-N, 1-P, 2-F were 2.306, 4.047, 1.155 and 2.899 microg g(-1) of CR, respectively. Significant p-values for trend were found for men with higher 2-F tertiles and were more likely to possess high-reference TSH levels. In addition, the multivariate linear regression models showed significant positive correlations for TSH levels with increased CR-adjusted 2-F concentration. No significant associations were found between other thyroid hormones levels and PAH metabolite concentrations. These results indicated that PAH exposure might be related to altered male thyroid hormone levels, but further study is needed to confirm these observed findings.

Metabolomics reveals metabolic changes in male reproductive cells exposed to thirdhand smoke

Thirdhand smoke (THS) is a new term for the toxins in cigarette smoke that linger in the environment long after the cigarettes are extinguished. The effects of THS exposure on male reproduction have not yet been studied. In this study, metabolic changes in male germ cell lines (GC-2 and TM-4) were analyzed after THS treatment for 24 h. THS-loaded chromatography paper samples were generated in a laboratory chamber system and extracted in DMEM. At a paper: DMEM ratio of 50 μg/ml, cell viability in both cell lines was normal, as measured by the MTT assay and markers of cytotoxicity, cell cycle, apoptosis and ROS production were normal as measured by quantitative immunofluorescence. Metabolomic analysis was performed on methanol extracts of GC-2 and TM-4 cells. Glutathione metabolism in GC-2 cells, and nucleic acid and ammonia metabolism in TM-4 cells, was changed significantly by THS treatment. RT-PCR analyses of mRNA for enzyme genes Gss and Ggt in GC-2 cells, and TK, SMS and Glna in TM-4 cells reinforced these findings, showing changes in the levels of enzymes involved in the relevant pathways. In conclusion, exposure to THS at very low concentrations caused distinct metabolic changes in two different types of male reproductive cell lines.

The impact of BMI on sperm parameters and the metabolite changes of seminal plasma concomitantly

The development of male infertility increased rapidly worldwide, which coinciding with the epidemic of obesity. However, the impact of weight abnormalities on sperm quality is still contestable. To assess the correlation between BMI and sperm parameters, we searched relevant articles in PubMed, Embase, Web of science, and Wanfang database published until June 2015 without language restriction. Otherwise, we also recruited some participants who attended fertility clinic as well as some general populations in this report. We performed a systematic review and meta-analysis about BMI and sperm parameters containing total sperm count, concentration, semen volume and sperm motility (overall and progressive). Metabolomic analysis of seminal plasma was performed to explore the mechanism from a new perspective. This study found standardized weighted mean differences (SMD) in sperm parameters (total sperm count, sperm concentration, and semen volume) of abnormal weight groups decreased to different degree compared to normal weight. Dose-response analysis found SMD of sperm count, sperm concentration and semen volume respectively fell 2.4%, 1.3% and 2.0% compared with normal weight for every 5-unit increase in BMI. Metabolomic analysis of seminal plasma showed that spermidine and spermine were likely to play a vital role in the spermatogenesis progress. This systematic review with meta-analysis has confirmed there was a relationship between BMI and sperm quality, suggesting obesity may be a detrimental factor of male infertility.

Seminal plasma metabolomics approach for the diagnosis of unexplained male infertility

We used a gas chromatography-mass spectrometry (GC-MS) based metabolomics approach to obtain the metabolic profiling of unexplained male infertility (UMI), and identified seminal plasma biomarkers associated with UMI by a two-stage population study. A robust OPLS-DA model based on these identified metabolites was able to distinguish 82% of the UMI patients from health controls with a specificity of 92%. In this model, 44 metabolites were found differentially expressed in UMI subjects compared with health controls. By pathway enrichment analysis, we identified several major changed metabolic pathways related to UMI. Our findings provide new perspective for the diagnosis of UMI.

Erratum: Corrigendum: Metabolomics reveals metabolic changes in male reproductive cells exposed to thirdhand smoke

Author(s): Xu, B; Chen, M; Yao, M; Ji, X; Mao, Z; Tang, W; Qiao, S; Schick, SF; Mao, JH; Hang, B; Xia, YScientific Reports 5: Article number: 1551210.1038/srep15512; published online: October222015; updated: April132016 The Acknowledgements section in this Article is incomplete. “This study was supported by National 973 Program (2012CBA01305); National Science Fund for Outstanding Young Scholars (81322039); National Natural Science Foundation (31371524); Distinguished Young Scholars of Jiangsu Province (BK20130041); Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); New Century Excellent Talents in University (NCET-13-0870) and the California Tobacco-Related Disease Research Program (TRDRP) Grant 19XT-0070 (to B.H.) under U.S. Department of Energy (Contract no. DE-AC02-05CH11231).” should read: “This study was supported by National 973 Program (2012CBA01305); National Science Fund for Outstanding Young Scholars (81322039); National Natural Science Foundation (31371524); Distinguished Young Scholars of Jiangsu Province (BK20130041); Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); New Century Excellent Talents in University (NCET-13-0870) and the California Tobacco-Related Disease Research Program (TRDRP) Grant 19XT-0070 (to B.H.) under U.S. Department of Energy (Contract no. DE-AC02-05CH11231); The California Consortium on Thirdhand Smoke, California Tobacco-Related Disease Research Program (trdrp.org) grant 20PT-0184 and California Tobacco-Related Disease Research Program grant 21 ST-011).”

Corrigendum: Metabolomics reveals metabolic changes in male reproductive cells exposed to thirdhand smoke.

Author(s): Xu, B; Chen, M; Yao, M; Ji, X; Mao, Z; Tang, W; Qiao, S; Schick, SF; Mao, JH; Hang, B; Xia, YScientific Reports 5: Article number: 1551210.1038/srep15512; published online: October222015; updated: April132016 The Acknowledgements section in this Article is incomplete. “This study was supported by National 973 Program (2012CBA01305); National Science Fund for Outstanding Young Scholars (81322039); National Natural Science Foundation (31371524); Distinguished Young Scholars of Jiangsu Province (BK20130041); Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); New Century Excellent Talents in University (NCET-13-0870) and the California Tobacco-Related Disease Research Program (TRDRP) Grant 19XT-0070 (to B.H.) under U.S. Department of Energy (Contract no. DE-AC02-05CH11231).” should read: “This study was supported by National 973 Program (2012CBA01305); National Science Fund for Outstanding Young Scholars (81322039); National Natural Science Foundation (31371524); Distinguished Young Scholars of Jiangsu Province (BK20130041); Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); New Century Excellent Talents in University (NCET-13-0870) and the California Tobacco-Related Disease Research Program (TRDRP) Grant 19XT-0070 (to B.H.) under U.S. Department of Energy (Contract no. DE-AC02-05CH11231); The California Consortium on Thirdhand Smoke, California Tobacco-Related Disease Research Program (trdrp.org) grant 20PT-0184 and California Tobacco-Related Disease Research Program grant 21 ST-011).”