Qingyu Huang

Perfluorooctanoic acid induces apoptosis through the p53-dependent mitochondrial pathway in human hepatic cells: A proteomic study

Perfluorooctanoic acid (PFOA) is one of the most commonly used perfluorinated compounds, and exposure to it has been associated with a number of adverse health effects. However, the molecular mechanisms involved in PFOA toxicity are still not well characterized. In the present study, flow cytometry analysis revealed that PFOA induced oxidative stress, cell cycle arrest and apoptosis in human non-tumor hepatic cells (L-02). Furthermore, we investigated the alterations in protein profile within L-02 cells exposed to PFOA, aiming to explore the mechanisms underlying PFOA hepatotoxicity on the proteome level. Of the 28 proteins showing significant differential expression in response to PFOA, 24 were down-regulated and 4 were up-regulated. This proteomic study proposed that the inhibition of some proteins, including GRP78, HSP27, CTSD and hnRNPC may be involved in the activation of p53, which consequently triggered the apoptotic process in L-02 cells. Induction of apoptosis via the p53-dependent mitochondrial pathway is further suggested as one of the key toxicological events occurring in L-02 cells under PFOA stress. We hope these data will shed new light on the molecular mechanisms responsible for PFOA-mediated toxicity in human liver cells, and from such studies useful biomarkers indicative of PFOA exposure could be developed.

Effects of water soluble PM2.5 extracts exposure on human lung epithelial cells (A549): A proteomic study

Exposure to airborne particulate matter (PM)2.5, a PM with aerodynamic diameter of less than 2.5 µm, is known to be associated with a variety of adverse health effects. However, the molecular mechanisms involved in fine PM toxicity are still not well characterized. The present study aims to provide new insights into the cytotoxicity of PM2.5 on human lung epithelial cells (A549) at the proteomic level. Two‐dimensional difference gel electrophoresis revealed a total of 27 protein spots, whose abundance were significantly altered in A549 cells exposed to water‐soluble PM2.5 extracts (WSPE). Among these, 12 spots were upregulated while 15 were downregulated. Twenty‐two proteins were further identified by matrix‐assisted laser desorption/ionization time‐of‐flight tandem mass/mass spectrometry and database search. The results revealed that oxidative stress, metabolic disturbance, dysregulation of signal transduction, aberrant protein synthesis and degradation, as well as cytoskeleton disorganization are major factors contributing to WSPE‐mediated toxicity in human lung cells. It is further proposed that induction of apoptosis through p53, c‐Myc and p21 pathways may be one of the key toxicological events occurred in A549 cells under WSPE stress. The data obtained here will aid our understanding of the toxic mechanisms related to PM2.5, and develop useful biomarkers indicative of inhalable PM2.5 exposure. Copyright

Urinary Metabolomics Revealed Arsenic Internal Dose-Related Metabolic Alterations: A Proof-of-Concept Study in a Chinese Male Cohort

Urinary biomonitoring provides the most accurate arsenic exposure assessment; however, to improve the risk assessment, arsenic-related metabolic biomarkers are required to understand the internal processes that may be perturbed, which may, in turn, link the exposure to a specific health outcome. This study aimed to investigate arsenic-related urinary metabolome changes and identify dose-dependent metabolic biomarkers as a proof-of-concept of the information that could be obtained by combining metabolomics and targeted analyses. Urinary arsenic species such as inorganic arsenic, methylarsonic acid, dimethylarsinic acid and arsenobetaine were quantified using high performance liquid chromatography (HPLC)-inductively coupled plasma-mass spectrometry in a Chinese adult male cohort. Urinary metabolomics was conducted using HPLC-quadrupole time-of-flight mass spectrometry. Arsenic-related metabolic biomarkers were investigated by comparing the samples of the first and fifth quintiles of arsenic exposure classifications using a partial least-squares discriminant model. After the adjustments for age, body mass index, smoking, and alcohol consumption, five potential biomarkers related to arsenic exposure (i.e., testosterone, guanine, hippurate, acetyl-N-formyl-5-methoxykynurenamine, and serine) were identified from 61 candidate metabolites; these biomarkers suggested that endocrine disruption and oxidative stress were associated with urinary arsenic levels. Testosterone, guanine, and hippurate showed a high or moderate ability to discriminate the first and fifth quintiles of arsenic exposure with area-under-curve (AUC) values of 0.89, 0.87, and 0.83, respectively; their combination pattern showed an AUC value of 0.91 with a sensitivity of 88% and a specificity of 80%. Arsenic dose-dependent AUC value changes were also observed. This study demonstrated that metabolomics can be used to investigate arsenic-related biomarkers of metabolic changes; the dose-dependent trends of arsenic exposure to these biomarkers may translate into the potential use of metabolic biomarkers in arsenic risk assessment. Since this was a proof-of-concept study, more research is needed to confirm the relationships we observed between arsenic exposure and biochemical changes.

A nested case-control study indicating heavy metal residues in meconium associate with maternal gestational diabetes mellitus risk

BackgroundEnvironmental pollutant exposure may play certain roles in the pathogenesis and progression of diabetes mellitus including gestational diabetes mellitus (GDM). We hypothesize that heavy metal exposure may trigger GDM during pregnancy. The objective of this study was to investigate the possible associations between selected heavy metal exposure and GDM risk.MethodsThis investigation is a retrospective case–control study nested within a cohort of 1359 pregnant women. These participants were recruited in Xiamen Maternity and Child Care Hospital, China, during June to July, 2012. All their newborns’ meconium samples were collected. By reviewing the antenatal care records, 166 GDM mothers were screened out from the 1359 participants; 137 of 166 GDM mothers offered their newborns’ meconium samples for the metal analysis. Those 137 mothers were set as the case group. Similarly, 294 healthy mothers without any gestational complication were initially screened out from the rest 1193 non-GDM mothers. 190 of the 294 healthy mothers offered their newborns’ meconium samples for the metal analysis. Those 190 mothers were set as the control group. Arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), and chromium (Cr) levels in these case–control meconium samples were measured by inductively coupled plasma mass spectrometry. The possible association between the metal levels and maternal GDM risk of studied subjects was assessed by binary logistic regression.ResultsGDM prevalence of 12.21% was observed in the investigated 1359 participants. The concentrations of As, Hg, Cr and Cd in studied cases were significantly higher (p < 0.05) than those of controls. After adjustments for maternal age, pre-pregnant body mass index, gravidity, parity, hepatitis B virus infection, and newborn sex, As, Cd and Cr were found to be positively associated with GDM prevalence in dose-dependent manners. Among them, As was detected in all samples and its levels associated the maternal GDM with the adjusted odds ratios of 3.28 [95% CI 1.24, 8.71], 3.35 [95% CI 1.28, 8.75] and 5.25 [95% CI 1.99, 13.86] for the 2nd, 3rd and 4th quartiles, respectively.ConclusionsThe present work implies that exposure to some of the selected metals (noticeably As) may contribute to maternal GDM risk during pregnancy.

Alterations of protein profile in zebrafish liver cells exposed to methyl parathion: A membrane proteomics approach

Methyl parathion (MP) is an extensively used organophosphorus pesticide, which has been associated with a wide spectrum of toxic effects on environmental organisms. The aim of this study is to investigate the alterations of membrane protein profiles in zebrafish liver (ZFL) cell line exposed to MP for 24 h using proteomic approaches. Two-dimensional gel electrophoresis revealed a total of 13 protein spots, whose expression levels were significantly altered by MP. These differential proteins were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, and nine proteins were identified to be membrane proteins, among which seven were up-regulated, while two were down-regulated. In addition, the mRNA levels corresponding to these differential membrane proteins were further analyzed by quantitative real-time PCR. And the differential expression of arginase-2 was specially validated via Western blotting. Regarding the physiological functions, these proteins are involved in molecular chaperon, cytoskeleton system, cell metabolism, signal transduction, transport and hormone receptor respectively, suggesting the complexity of MP-mediated toxicity to ZFL cell. These data could provide useful insights for better understanding the hepatotoxic mechanisms of MP and develop novel protein biomarkers for effectively monitoring MP contamination level in aquatic environment.

Low-Level Environmental Phthalate Exposure Associates with Urine Metabolome Alteration in a Chinese Male Cohort

The general population is exposed to phthalates through various sources and routes. Integration of omics data and epidemiological data is a key step toward directly linking phthalate biomonitoring data with biological response. Urine metabolomics is a powerful tool to identify exposure biomarkers and delineate the modes of action of environmental stressors. The objectives of this study are to investigate the association between low-level environmental phthalate exposure and urine metabolome alteration in male population, and to unveil the metabolic pathways involved in the mechanisms of phthalate toxicity. In this retrospective cross-sectional study, we studied the urine metabolomic profiles of 364 male subjects exposed to low-level environmental phthalates. Di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) are the most widely used phthalates. ∑DEHP and MBP (the major metabolite of DBP) were associated with significant alteration of global urine metabolome in the male population. We observed significant increase in the levels of acetylneuraminic acid, carnitine C8:1, carnitine C18:0, cystine, phenylglycine, phenylpyruvic acid and glutamylphenylalanine; and meanwhile, decrease in the levels of carnitine C16:2, diacetylspermine, alanine, taurine, tryptophan, ornithine, methylglutaconic acid, hydroxyl-PEG2 and keto-PGE2 in high exposure group. The observations indicated that low-level environmental phthalate exposure associated with increased oxidative stress and fatty acid oxidation and decreased prostaglandin metabolism. Urea cycle, tryptophan and phenylalanine metabolism disruption was also observed. The urine metabolome disruption effects associated with ∑DEHP and MBP were similar, but not identical. The multibiomarker models presented AUC values of 0.845 and 0.834 for ∑DEHP and MBP, respectively. The predictive accuracy rates of established models were 81% for ΣDEHP and 73% for MBP. Our results suggest that low-level environmental phthalate exposure associates with urine metabolome disruption in male population, providing new insight into the early molecular events of phthalate exposure.

Metabolomic Analysis Reveals a Unique Urinary Pattern in Normozoospermic Infertile Men

Normozoospermic infertility has become a common and important health problem worldwide. We designed this metabolomic case-control study to investigate the possible mechanism and urinary biomarkers of normozoospermic infertility. Normozoospermic infertile cases (n = 71) and fertile controls (n = 47) were recruited. A urinary metabolome pattern could discriminate normozoospermic infertile cases from fertile controls. A total of 37 potential biomarkers were identified; these have functionally important roles in energy production, antioxidation, and hormone regulation in spermatogenesis. This gave rise to a combined biomarker pattern of leukotriene E4, 3-hydroxypalmitoylcarnitine, aspartate, xanthosine, and methoxytryptophan pointing to a diagnostic capability (AUC = 0.901, sensitivity = 85.7%, and specificity = 86.8%) in a ROC model; these markers may highlight keynote events of normozoospermic infertility. Stalled medium- and long-chain fatty acid metabolism with improved ketone body metabolism, plus decreased levels of malate and aspartate could result in citrate cycle alterations via a malate-aspartate shuttle in ATP generation in spermatogenesis. Inhibitory alterations in the normal hormone-secreting activity in spermatogenesis were suggested in normozoospermic infertility. Folate deficiency and oxidative stress may jointly impact infertile patients. The disruption of eicosanoid metabolism and xanthine oxidase system, which were tightly associated with energy metabolism and oxidative stress, was also a potential underlying mechanism. In addition, depression might be associated with normozoospermic infertility via neural activity-related metabolites. This study suggests that the urinary metabolome can be used to differentiate normozoospermic infertile men from fertile individuals. Potential metabolic biomarkers derived from these analyses might be used to diagnose what remains a somewhat idiopathic condition and provide functional insights into its pathogenesis.

Human Arsenic exposure via dust across the different ecological zones of Pakistan.

The present study aims to assess the arsenic (As) levels into dust samples and its implications for human health, of four ecological zones of Pakistan, which included northern frozen mountains (FMZ), lower Himalyian wet mountains (WMZ), alluvial riverine plains (ARZ), and low lying agricultural areas (LLZ). Human nail samples (N=180) of general population were also collected from the similar areas and all the samples were analysed by using ICP-MS. In general the higher levels (p<0.05) in paired dust and human nail samples were observed from ARZ and LLZ than those of other mountainous areas (i.e., WMZ and FMZ), respectively. Current results suggested that elevated As concentrations were associated to both natural, (e.g. geogenic influences) and anthropogenic sources. Linear regression model values indicated that As levels into dust samples were associated with altitude (r(2)=0.23), soil carbonate carbon density (SCC; r(2)=0.33), and population density (PD; r(2)=0.25). The relationship of paired dust and nail samples was also investigated and associations were found for As-nail and soil organic carbon density (SOC; r(2)=0.49) and SCC (r(2)=0.19) in each studied zone, evidencing the dust exposure as an important source of arsenic contamination in Pakistan. Risk estimation reflected higher hazard index (HI) values of non-carcinogenic risk (HI>1) for children populations in all areas (except FMZ), and for adults in LLZ (0.74) and ARZ (0.55), suggesting that caution should be paid about the dust exposure. Similarly, carcinogenic risk assessment also highlighted potential threats to the residents of LLZ and ARZ, as in few cases (5-10%) the values exceeded the range of US-EPA threshold limits (10(-6)-10(-4)).

Proteomic analysis of methyl parathion-responsive proteins in zebrafish (Danio rerio) brain.

Methyl parathion (MP), an organophosphorus pesticide used worldwide, has been associated with a wide spectrum of toxic effects on organisms in the environment. This study set out to analyze the alteration of protein profiles in MP-exposed zebrafish (Danio rerio) brain and find the proteins responsive to MP toxicity. Zebrafish were subjected to 1, 3 and 5mg/L MP and the proteomic changes in their brains were revealed using two-dimensional gel electrophoresis. Six protein spots were observed to be significantly changed by MP exposure. Among these, 4 spots were down-regulated, while 2 spots were up-regulated. These altered spots were excised from the gels and identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry and database searching. The results indicate that these proteins were involved in binding, catalysis, regulation of energy metabolism and cell structure. These data may provide novel biomarkers for the evaluation of MP contamination and useful insights for understanding the mechanisms of MP toxicity.

Metabolomics reveals disturbed metabolic pathways in human lung epithelial cells exposed to airborne fine particulate matter

Exposure to airborne fine particulate matter (PM2.5) has been associated with a variety of adverse health effects; however, the molecular mechanisms involved in PM2.5-elicited pulmonary toxicity are still not well elucidated. By conducting an ultra-high performance liquid chromatography/mass spectrometry-based metabolomics analysis, the present study investigated alterations of metabolome in human lung epithelial cells (A549) exposed to PM2.5 extracts. Distinct metabolomic profiles were found to be associated with PM2.5 treatment. PM2.5 significantly changed the abundance of 16 intracellular metabolites in a dose-dependent manner, of which 13 were decreased and three were increased. By pathway analysis, it was shown that the citrate cycle, amino acid biosynthesis and metabolism, and glutathione metabolism were the major metabolic pathways disturbed by PM2.5 in A549 cells. In addition, changes in expression of several key genes involved in these pathways further validated the metabolic alterations observed by metabolomics herein. It is suggested that PM2.5-induced oxidative stress may contribute to perturbation of metabolic processes occurring in cell mitochondria. Overall, these results aid in improving understanding of the toxicological mechanisms related to PM2.5, and identifying potential biomarkers indicative of inhalable PM2.5 exposure.