Differential expression of hepatic genes with embryonic exposure to an environmentally relevant PCB mixture in Japanese quail (Coturnix japonica)

Which factors influence the frequency of participation in longitudinal cohort studies? - An analysis of demographics, social factors, and medical preconditions in participants of the health effects in high level exposure to polychlorinated biphenyls (HELPcB) cohort

The continuous drop out of participants in longitudinal studies is a trend that may be observed in nearly all fields of medical research. A reduced participation rate might compromise the power of statistical analysis as well as lead to an attrition bias of the study. The aim of this analysis was to identify influencing factors on participation frequency in the monitoring program Health Effects in High Level Exposure to polychlorinated biphenyls (HELPcB) study, a cohort investigation of occupationally polychlorinated biphenyls (PCB) exposed individuals. The HELPcB study was initiated in 2010 and consisted of 7 study visits. At the last cross-section in 2019, less than one third of the included patients still actively participated. As possible influencing factors on study participation frequency, demographic, social, and medical characteristics of the participants were examined. In addition, a logistic regression model to predict study participation behavior was calculated. An overall higher frequency of participation was observed, if participants joined the program together with relatives or friends and had a higher age. For PCB plasma levels, an exceedance of the biological reference value (BAR) and further factors, such as (1) professional qualification, (2) later inclusion, (3) type of participant and (4) occupational-related disease notification, significant differences in the participation frequency were observed in the univariate analysis. Only age and joined study participation remained significant in the multivariate logistic regression. In conclusion, it was possible to identify several social and occupational-related factors that influence the frequency of participation of study attendees.

Using Transcriptomics and Metabolomics to Understand Species Differences in Sensitivity to Chlorpyrifos in Japanese Quail and Double-Crested Cormorant Embryos

Modern 21st-century toxicity testing makes use of omics technologies to address critical questions in toxicology and chemical management. Of interest are questions relating to chemical mechanisms of toxicity, differences in species sensitivity, and translation of molecular effects to observable apical endpoints. Our study addressed these questions by comparing apical outcomes and multiple omics responses in early-life stage exposure studies with Japanese quail (Coturnix japonica) and double-crested cormorant (Phalacrocorax auritus), representing a model and ecological species, respectively. Specifically, we investigated the dose-dependent response of apical outcomes as well as transcriptomics and metabolomics in the liver of each species exposed to chlorpyrifos, a widely used organophosphate pesticide. Our results revealed a clear pattern of dose-dependent disruption of gene expression and metabolic profiles in Japanese quail but not double-crested cormorant at similar chlorpyrifos exposure concentrations. The difference in sensitivity between species was likely due to higher metabolic transformation of chlorpyrifos in Japanese quail compared to double-crested cormorant. The most impacted biological pathways after chlorpyrifos exposure in Japanese quail included hepatic metabolism, oxidative stress, endocrine disruption (steroid and nonsteroid hormones), and metabolic disease (lipid and fatty acid metabolism). Importantly, we show consistent responses across biological scales, suggesting that significant disruption at the level of gene expression and metabolite profiles leads to observable apical responses at the organism level. Our study demonstrates the utility of evaluating effects at multiple biological levels of organization to understand how modern toxicity testing relates to outcomes of regulatory relevance, while also highlighting important, yet poorly understood, species differences in sensitivity to chemical exposure. Environ Toxicol Chem 2021;40:3019-3033. © 2021 SETAC.

Association of Polychlorinated Biphenyls and Organochlorine Pesticides with Autism Spectrum Disorder in Jamaican Children

BACKGROUND

Polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides are suspected to play a role in autism spectrum disorder (ASD).

OBJECTIVES

To investigate associations of PCBs and OC pesticides with ASD in Jamaican children and explore possible interaction between PCBs or OC pesticides with glutathione S-transferase (GST) genes (GSTT1, GSTM1, GSTP1) in relation to ASD.

METHODS

Participants included n=169 age- and sex-matched case-control pairs of Jamaican children 2-8 years old. Socioeconomic status and food frequency data were self-reported by the parents/guardians. Blood from each participant was analyzed for 100 PCB congeners and 17 OC pesticides and genotyped for three GST genes. PCBs and OC pesticides concentrations below the limit of detection (LoD) were replaced with (LoD/√2). We used conditional logistic regression (CLR) models to assess associations of PCBs and OC pesticides with ASD, individually or interactively with GST genes (GSTT1, GSTM1, GSTP1).

RESULTS

We found inverse associations of PCB-153 [adjusted MOR (95% CI) = 0.44 (0.23-0.86)] and PCB-180 [adjusted MOR (95% CI) = 0.52 (0.28-0.95)] with ASD. When adjusted for covariates in a CLR the interaction between GSTM1 and PCB-153 became significant (P < 0.01).

DISCUSSION

Differences in diet between ASD and typically developing control groups may play a role in the observed findings of lower concentrations of PCB-153 and PCB-180 in individuals with ASD than in controls. Considering the limited sample size and high proportion of concentrations below the LoD, these results should be interpreted with caution but warrant further investigation into associations of PCBs and OC pesticides with ASD.

Transcriptome analysis in normal human liver cells exposed to 2, 3, 3', 4, 4', 5 - Hexachlorobiphenyl (PCB 156)

BACKGROUNDS

Polychlorinated biphenyls are persistent environmental pollutants associated with the onset of non-alcoholic fatty liver disease in humans, but there is limited information on the underlying mechanism. In the present study, we investigated the alterations in gene expression profiles in normal human liver cells L-02 following exposure to 2, 3, 3', 4, 4', 5 - hexachlorobiphenyl (PCB 156), a potent compound that may induce non-alcoholic fatty liver disease.

METHODS

The L-02 cells were exposed to PCB 156 for 72 h and the contents of intracellular triacylglyceride and total cholesterol were subsequently measured. Microarray analysis of mRNAs and long non-coding RNAs (lncRNAs) in the cells was also performed after 3.4 μM PCB 156 treatment.

RESULTS

Exposure to PCB 156 (3.4 μM, 72 h) resulted in significant increases of triacylglyceride and total cholesterol concentrations in L-02 cells. Microarray analysis identified 222 differentially expressed mRNAs and 628 differentially expressed lncRNAs. Gene Ontology and pathway analyses associated the differentially expressed mRNAs with metabolic and inflammatory processes. Moreover, lncRNA-mRNA co-expression network revealed 36 network pairs comprising 10 differentially expressed mRNAs and 34 dysregulated lncRNAs. The results of bioinformatics analysis further indicated that dysregulated lncRNA NONHSAT174696, lncRNA NONHSAT179219, and lncRNA NONHSAT161887, as the regulators of EDAR, CYP1B1, and ALDH3A1 respectively, played an important role in the PCB 156-induced lipid metabolism disorder.

CONCLUSION

Our findings provide an overview of differentially expressed mRNAs and lncRNAs in L-02 cells exposed to PCB 156, and contribute to the field of polychlorinated biphenyl-induced non-alcoholic fatty liver disease.