Perfluorooctanoic acid impaired glucose homeostasis through affecting adipose AKT pathway

Correlation of perfluoroalkyl and polyfluoroalkyl substance levels during pregnancy with gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a major class of contaminants in recent years. Pregnant women are more susceptible to the influence of these compounds, which could heighten the risk of developing gestational diabetes mellitus (GDM). This study aims to conduct an updated systematic review and meta-analysis to determine the correlation between PFAS exposure during pregnancy and the risk of developing GDM and delve into their dose-response relationship.

METHODS

Pubmed, EMBASE, Web of Science, and Cochrane Library databases were searched. Data were statistically analyzed using Stata 15.0. Fixed-effects (FEM) or random-effects (REM) models were used to combine STD mean difference (SMD) or odds ratio (OR) and 95% confidence intervals (CIs) according to heterogeneity. Dose-response meta-analyses were performed when applicable.

RESULTS

A total of 12 papers were included in this study. Meta-analysis results indicated significantly higher levels of PFOA, PFBS, and PFUnDA in GDM patients compared to healthy pregnant women. Pregnant women exposed to high levels of PFOA and PFBS had a significantly increased risk of developing GDM, with ORs of 1.513 and 1.436, respectively. Dose-response analyses indicated that for each 1 ng/ml increase in PFOA and PFBS exposure, the risk of GDM increased by 0.3% and 11.7%, respectively. In contrast, no significant associations were observed between high exposure to other PFAS compounds, such as PFNA, PFHxS, and PFOS, and the development of GDM. Subgroup analyses suggested that PFOA, PFBS, and PFOS levels were higher in GDM patients from China compared to those from Western countries. The differences in PFOA and PFOS levels between GDM and normal pregnant women were more pronounced during late pregnancy.

CONCLUSION

Exposure to PFOA, PFBS, and PFUnDA during pregnancy is associated with an increased risk of GDM. Given the elevated risk, particularly in the Chinese population, it is crucial to reduce exposure to these substances, especially from the preconception period onward.

Relationship between per-fluoroalkyl and polyfluoroalkyl substance exposure and insulin resistance in nondiabetic adults: Evidence from NHANES 2003-2018

BACKGROUND

Studies have linked per- and polyfluoroalkyl substances (PFAS) to chronic metabolic diseases. However, the relationship between PFAS exposure and insulin resistance (IR), a key pathophysiological basis of these metabolic diseases, in nondiabetic individuals have yet to be determined.

METHODS

This study analyzed data from 3909 participants (aged ≥20) from the NHANES 2003-2018 to investigate the associations between serum levels of seven PFAS and and IR indicators, including including HOMA-IR, HOMA-β, fasting insulin, QUICKI, and TyG index. Linear and logistic regression models were used, along with a restricted cubic spline to assess dose-response. Weighted quantile sum (WQS) regression and quantile g-computation (qgcomp) models were used to assess the association between mixed PFAS exposure and IR.

RESULTS

Linear regression revealed that elevated exposure to PFOS [β (95 % CI): 0.04 (0.02, 0.06)], PFOA [0.04 (0.01, 0.06)], and Me_PFOSA_AcOH [0.04 (0.02, 0.06)] was associated with a higher TyG index in adults. Notably, Me_PFOSA_AcOH was negatively associated with IR when assessed by HOMA-IR >2.6 [OR (95 % CI): 0.88 (0.79, 0.98)], although this was not supported by linear regression findings. When IR was defined by a TyG index >8.6, exposure to the highest quartiles of PFOS, PFOA, and Me_PFOSA_AcOH was associated with an increased risk of IR by 63 %, 42 %, and 85 %, respectively [1.63 (1.21, 2.20); 1.42 (1.06, 1.92); 1.85 (1.37, 2.50)]. PFOS, PFOA, and Me_PFOSA_AcOH demonstrated a nonlinear dose-response relationship with IR risk. The WQS and qgcomp models revealed significant positive correlations with the TyG index.

CONCLUSION

Mixed PFAS exposure in US nondiabetic adults was positively associated with IR, as indicated by the TyG index, particularly for PFOS, PFOA, and Me_PFOSA_AcOH. Further research is needed to establish causality, and reinforcing environmental risk mitigation strategies to reduce PFAS exposure is recommended.

The Role of the PI3K/Akt/mTOR Axis in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies globally, representing a significant public health problem with a poor prognosis. The development of efficient therapeutic strategies for HNSCC prevention and treatment is urgently needed. The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved transduction network in eukaryotic cells that promotes cell survival, growth, and cycle progression. Dysfunction in components of this pathway, such as hyperactivity of PI3K, loss of PTEN function, and gain-of-function mutations in AKT, are well-known drivers of treatment resistance and disease progression in cancer. In this review, we discuss the major mutations and dysregulations in the PAM signaling pathway in HNSCC. We highlight the results of clinical trials involving inhibitors targeting the PAM signaling pathway as a strategy for treating HNSCC. Additionally, we examine the primary mechanisms of resistance to drugs targeting the PAM pathway and potential therapeutic strategies.

Associations between serum perfluoroalkyl and polyfluoroalkyl concentrations and diabetes mellitus in the Korean general population: Insights from the Korean National Environmental Health Survey 2018-2020

AIMS

Recent epidemiologic research has examined the relationship between perfluoroalkyl and polyfluoroalkyl substances (PFAS) and diabetes mellitus with inconclusive findings. In this cross-sectional study, we aimed to explore the association between serum PFAS concentrations and the prevalence of prediabetes and pre-diagnostic diabetes in the general Korean population as well as the combined effects of exposure to mixed PFAS compounds.

METHODS

We analyzed data from participants aged ≥19 years enrolled in the Korean National Environmental Health Survey Cycle 4 (2018-2020). Individuals diagnosed with diabetes were excluded to minimize potential bias. We identified cases of pre-diagnostic diabetes based on the HbA1c level ≥6.5% and prediabetes as HbA1c levels of 5.7-6.49%. Serum concentrations of PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS), were quantified using high-performance liquid chromatography-tandem mass spectrometry. Survey-weighted logistic regression models were used to assess the relationships between PFAS levels and diabetes risk, adjusting for covariates. Additionally, Bayesian kernel machine regression (BKMR) was used to investigate the combined effects of exposure to mixed PFAS compounds.

RESULTS

In the study population excluding participants with diagnosed diabetes (n = 2709), the prevalence of pre-diagnostic diabetes and prediabetes was 4.8% and 30.1%, respectively. Significant positive associations were found between serum PFHxS and PFOS quartiles and pre-diagnostic diabetes risk. Likewise, among those without diagnosed or pre-diagnostic diabetes (n = 2579), the highest quartiles of PFDeA, PFHxS, and PFOS and the overall PFAS level were associated with an increased risk of prediabetes compared with the lowest quartiles. BKMR analysis revealed a significant positive association between overall serum PFAS level and prediabetes risk, which was most marked for PFOS.

CONCLUSIONS

These findings highlight the potential health implications of PFAS exposure and prediabetes risk. Further research is needed to validate these associations and identify potential mechanistic pathways.

Association of exposure to multiple perfluoroalkyl and polyfluoroalkyl substances and glucose metabolism in National Health and Nutrition Examination Survey 2017-2018

Objective

To investigate the relationships between perfluoroalkyl and polyfluoroalkyl substances (PFASs) exposure and glucose metabolism indices.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 waves were used. A total of 611 participants with information on serum PFASs (perfluorononanoic acid (PFNA); perfluorooctanoic acid (PFOA); perfluoroundecanoic acid (PFUA); perfluorohexane sulfonic acid (PFHxS); perfluorooctane sulfonates acid (PFOS); perfluorodecanoic acid (PFDeA)), glucose metabolism indices (fasting plasma glucose (FPG), homeostasis model assessment for insulin resistance (HOMA-IR) and insulin) as well as selected covariates were included. We used cluster analysis to categorize the participants into three exposure subgroups and compared glucose metabolism index levels between the subgroups. Least absolute shrinkage and selection operator (LASSO), multiple linear regression analysis and Bayesian kernel machine regression (BKMR) were used to assess the effects of single and mixed PFASs exposures and glucose metabolism.

Results

The cluster analysis results revealed overlapping exposure types among people with higher PFASs exposure. As the level of PFAS exposure increased, FPG level showed an upward linear trend (p < 0.001), whereas insulin levels demonstrated a downward linear trend (p = 0.012). LASSO and multiple linear regression analysis showed that PFNA and FPG had a positive relationship (>50 years-old group: β = 0.059, p < 0.001). PFOA, PFUA, and PFHxS (≤50 years-old group: insulin β = -0.194, p < 0.001, HOMA-IR β = -0.132, p = 0.020) showed negative correlation with HOMA-IR/insulin. PFNA (>50 years-old group: insulin β = 0.191, p = 0.018, HOMA-IR β = 0.220, p = 0.013) showed positive correlation with HOMA-IR/insulin, which was essentially the same as results that obtained for the univariate exposure-response map in the BKMR model. Association of exposure to PFASs on glucose metabolism indices showed positive interactions between PFOS and PFHxS and negative interactions between PFOA and PFNA/PFOS/PFHxS.

Conclusion

Our study provides evidence that positive and negative correlations between PFASs and FPG and HOMA-IR/insulin levels are observed, respectively. Combined effects and interactions between PFASs. Given the higher risk of glucose metabolism associated with elevated levels of PFAS, future studies are needed to explore the potential underlying mechanisms.

Is Physical Activity an Efficient Strategy to Control the Adverse Effects of Persistent Organic Pollutants in the Context of Obesity? A Narrative Review

Obesity affects nearly 660 million adults worldwide and is known for its many comorbidities. Although the phenomenon of obesity is not fully understood, science regularly reveals new determinants of this pathology. Among them, persistent organic pollutants (POPs) have been recently highlighted. Mainly lipophilic, POPs are normally stored in adipose tissue and can lead to adverse metabolic effects when released into the bloodstream. The main objective of this narrative review is to discuss the different pathways by which physical activity may counteract POPs' adverse effects. The research that we carried out seems to indicate that physical activity could positively influence several pathways negatively influenced by POPs, such as insulin resistance, inflammation, lipid accumulation, adipogenesis, and gut microbiota dysbiosis, that are associated with the development of obesity. This review also indicates how, through the controlled mobilization of POPs, physical activity could be a valuable approach to reduce the concentration of POPs in the bloodstream. These findings suggest that physical activity should be used to counteract the adverse effects of POPs. However, future studies should accurately assess its impact in specific situations such as bariatric surgery, where weight loss promotes POPs' blood release.

Concentrations and association between exposure to mixed perfluoroalkyl and polyfluoroalkyl substances and glycometabolism among adolescents

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used for industrial and commercial purposes and have received increasing attention due to their adverse effects on health.

OBJECTIVE

To examine the relationship of serum PFAS and glycometabolism among adolescents based on the US National Health and Nutrition Examination Survey.

METHODS

General linear regression models were applied to estimate the relationship between exposure to single PFAS and glycometabolism. Weighted quantile sum (WQS) regression models and Bayesian kernel machine regressions (BKMR) were used to assess the associations between multiple PFASs mixture exposure and glycometabolism.

RESULTS

A total of 757 adolescents were enrolled. Multivariable regression model showed that Me-PFOSA-AcOH exposure was negatively associated with fasting blood glucose. WQS index showed that there was marginal negative correlation between multiple PFASs joint exposure and the homeostasis model of assessment for insulin resistance index (HOMA-IR) (β = -0.26, p < .068), and PFHxS had the largest weight. BKMR models showed that PFASs mixture exposure were associated with decreased INS and HOMA-IR, and the exposure-response relationship had curvilinear shape.

CONCLUSIONS

The increase in serum PFASs were associated with a decrease in HOMA-IR among adolescents. Mixed exposure models could more accurately and effectively reveal true exposure.Key MessagesThe detection rates of different PFAS contents in adolescent serum remained diverse.Adolescent serum PFASs had negative curvilinear correlation with INS and HOMA-IR levels.PFHxS had the highest weight in the associations between multiple PFASs and adolescent glycometabolism.

PFOA exposure induces aberrant glucose and lipid metabolism in the rat liver through the AMPK/mTOR pathway

Perfluorooctanoic acid (PFOA) is the most prominent member of a widely utilized family of compounds named Perfluoroalkyl substances (PFASs). Initially produced for use in both industrial and consumer applications, it has since been recognized that PFASs are extremely persistent in the environment where they have been characterized as persistent organic pollutants (POPs). While previous studies have demonstrated that PFOA may induce disorders of lipid and carbohydrate metabolism, the precise mechanisms by which PFOA produces this phenotype and the involvement of downstream AMPK/mTOR pathways remains unclear. In this study, male rats were exposed to 1.25, 5 and 20mg PFOA/kg body weight/day for 28 days by oral gavage. After 28 days, blood was collected and tested for serum biochemical indicators and livers were removed and weighed. To investigate aberrant metabolism in rats exposed to PFOA, livers were analyzed by performing LC-MS/MS untargeted metabolomics, quantitative real-time PCR, western blotting, immunohistochemical staining was also performed on exposed tissues. Our results showed that exposure to PFOA induced liver damage, increased the expression of glucose and lipid related biochemical indexes in liver and serum, and altered the expression levels of AMPK/mTOR pathway related genes and proteins. In summary, this study clarifies the mechanisms responsible for PFOA toxicity in the liver of exposed animals.

Systemic toxicity induced by topical application of perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), and perfluoropentanoic acid (PFPeA) in a murine model

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic structurally diverse chemicals incorporated into industrial and consumer products. PFHpA, PFHxA, and PFPeA are carboxylic PFAS (C7, C6, C5, respectively) labeled as a safer alternative to legacy carboxylic PFAS due to their shorter half-life in animals. Although there is a high potential for dermal exposure, these studies are lacking. The present study conducted analyses of serum chemistries, immune phenotyping, gene expression, and histology to evaluate the systemic toxicity of a sub-chronic 28-day dermal exposure of alternative PFAS (1.25-5% or 31.25-125 mg/kg/dose) in a murine model. Liver weight (% body) significantly increased with PFHpA, PFHxA, and PFPeA exposure and histopathological changes were observed in both the liver and skin. Gene expression changes were observed with PPAR isoforms in the liver and skin along with changes in genes involved in steatosis, fatty acid metabolism, necrosis, and inflammation. These findings, along with significant detection levels in serum and urine, support PFAS-induced liver damage and PPARα, δ, and γ involvement in alternative PFAS systemic toxicity and immunological disruption. This demonstrates that these compounds can be absorbed through the skin and brings into question whether these PFAS are a suitable alternative to legacy PFAS.

Reduced Birth Weight and Exposure to Per- and Polyfluoroalkyl Substances: A Review of Possible Underlying Mechanisms Using the AOP-HelpFinder

Prenatal exposure to per- and polyfluorinated substances (PFAS) may impair fetal growth. Our knowledge of the underlying mechanisms is incomplete. We used the Adverse Outcome Pathway (AOP)-helpFinder tool to search PubMed for studies published until March 2021 that examined PFAS exposure in relation to birth weight, oxidative stress, hormones/hormone receptors, or growth signaling pathways. Of these 1880 articles, 106 experimental studies remained after abstract screening. One clear finding is that PFAS are associated with oxidative stress in in vivo animal studies and in vitro studies. It appears that PFAS-induced reactive-oxygen species (ROS) generation triggers increased peroxisome proliferator-activated receptor (PPAR)γ expression and activation of growth signaling pathways, leading to hyperdifferentiation of pre-adipocytes. Fewer proliferating pre-adipocytes result in lower adipose tissue weight and in this way may reduce birth weight. PFAS may also impair fetal growth through endocrine effects. Estrogenic effects have been noted in in vivo and in vitro studies. Overall, data suggest thyroid-damaging effects of PFAS affecting thyroid hormones, thyroid hormone gene expression, and histology that are associated in animal studies with decreased body and organ weight. The effects of PFAS on the complex relationships between oxidative stress, endocrine system function, adipogenesis, and fetal growth should be further explored.

Perfluorooctanoic acid-induced developmental cardiotoxicity in chicken embryo: Roles of miR-490-5p

Perfluorooctanoic acid (PFOA) could induce developmental toxicities, affecting various organs, including the heart. Although peroxisome-proliferation activated receptor alpha (PPARα) had been identified as a major target of PFOA, PPARα-independent effects are frequently reported. To further elucidate the mechanism of toxicity in PFOA-induced developmental cardiotoxicity, RNA-seq analysis was performed in hatchling chicken hearts developmentally exposed to vehicle or 2 mg/kg (egg weight) PFOA. RT-PCR and western blotting were then performed to confirm the identified potential targets. Furthermore, lentivirus was designed to overexpress and silence identified target miRNA in developing chicken embryo, and the resulting phenotypes were investigated. 21 miRNAs and 1142 mRNAs were identified to be affected by developmental exposure to PFOA in chicken embryo hearts. Among the identified differentially expressed miRNAs, miR-490-5p was confirmed to be significantly affected by PFOA exposure, along with its downstream targets, Synaptosome associated protein 91 (SNAP91) and LY6/PLAUR domain containing 6 (LYPD6), as indicated by RT-PCR and western blotting results. Lentivirus overexpressing miR-490-5p mimicked the phenotype induced by PFOA exposure, while lentivirus silencing miR-490-5p alleviated PFOA-induced changes. Similar patterns were also observed in the expression of downstream target genes, SNAP91 and LYPD6. In summary, miR-490-5p and its downstream genes, SNAP91 and LYPD6 are associated with PFOA-induced developmental cardiotoxicity in chicken embryo, which might help to further elucidate the mechanism of PFOA-induced developmental cardiotoxicity.

Perfluorinated compounds in adults and their association with fasting glucose and incident diabetes: a prospective cohort study

BACKGROUND

The endocrine disruption of perfluorinated compounds is an emerging issue. We aimed to examine the association of serum perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) levels with incident diabetes and fasting serum glucose concentration.

METHODS

This prospective cohort study was based on an urban-based cohort subpopulation from the Korean Genome and Epidemiology Study. Serum samples (600 µL) were received from 100 participants in the normoglycemic baseline survey (2004-2013), and concentrations of PFOA and PFOS were measured using mass spectrometry. The incidence of diabetes was tracked in the follow-up survey (2012-2016).

RESULTS

The mean age was 56.4 years (men, 59%). The median serum PFOA and PFOS concentrations were 4.29 ng/mL and 9.44 ng/mL, respectively. PFOA and PFOS concentrations differed according to age, sex, and residential area. After 60 months, 23 patients had diabetes. Log-transformed PFOA (lnPFOA) and log-transformed PFOS (lnPFOS) were significantly higher in those who transitioned to diabetes than in those who did not (both p < 0.05). After multivariate adjustment, lnPFOA (coefficient = 6.98, 95% CI -0.04-14, p = 0.054) and lnPFOS (coefficient = 7.06, 95% CI -0.96-15.08, p = 0.088) predicted increased fasting glucose without statistical significance. In addition, lnPFOA, but not lnPFOS, significantly predicted incident diabetes (HR = 3.98, 95% CI 1.42-11.1, p < 0.01).

CONCLUSION

Exposure to PFOA and PFOS may have a potential dysglycemic effect. In particular, exposure to PFOA increased the risk of diabetes. Further research with larger sample size is warranted.

Early-life exposure to perfluoroalkyl substances in relation to serum adipokines in a longitudinal birth cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exposure has been linked to metabolic health outcomes such as obesity, and changes in adipokine hormones may be one of the underlying biological mechanisms. We prospectively evaluated the associations between prenatal and early childhood exposures to PFASs and adipokines in children.

MATERIAL AND METHODS

PFAS concentrations were measured in serum samples collected at birth, 18 months, and 5 and 9 years, and adiponectin, leptin, leptin receptor, and resistin were measured in serum samples collected at birth and 9 years. We used multivariable linear regression models to estimate the percent change in serum-adipokine concentrations for a doubling in serum-PFAS concentrations. The potential sex-specific effect of PFAS was assessed by including an interaction term between PFAS and sex in each model. Bayesian kernel machine regression (BKMR) was implemented to evaluate the overall effect of PFAS mixtures.

RESULTS

Significant associations with leptin, leptin receptor, and resistin at age 9 years were observed for serum-PFAS concentrations at 18 months and 5 and 9 years, whereas associations for PFAS concentrations at birth were mostly null. However, we observed a positive association between serum-PFHxS at birth and leptin receptor at birth. We found limited evidence regarding modification effect of sex on serum-PFAS concentrations. BKMR findings were consistent and suggested some significant effects of the overall PFAS mixtures at 18 months and 5 and 9 years on adipokine concentrations at 9 years.

CONCLUSIONS

Given the associations of PFAS exposure with both adipokine hormones and metabolic functions, future studies should include assessment of adipokine hormones when examining PFAS-associated metabolic alterations.

The Role of Persistent Organic Pollutants in Obesity: A Review of Laboratory and Epidemiological Studies

Persistent organic pollutants (POPs) are considered as potential obesogens that may affect adipose tissue development and functioning, thus promoting obesity. However, various POPs may have different mechanisms of action. The objective of the present review is to discuss the key mechanisms linking exposure to POPs to adipose tissue dysfunction and obesity. Laboratory data clearly demonstrate that the mechanisms associated with the interference of exposure to POPs with obesity include: (a) dysregulation of adipogenesis regulators (PPARγ and C/EBPα); (b) affinity and binding to nuclear receptors; (c) epigenetic effects; and/or (d) proinflammatory activity. Although in vivo data are generally corroborative of the in vitro results, studies in living organisms have shown that the impact of POPs on adipogenesis is affected by biological factors such as sex, age, and period of exposure. Epidemiological data demonstrate a significant association between exposure to POPs and obesity and obesity-associated metabolic disturbances (e.g., type 2 diabetes mellitus and metabolic syndrome), although the existing data are considered insufficient. In conclusion, both laboratory and epidemiological data underline the significant role of POPs as environmental obesogens. However, further studies are required to better characterize both the mechanisms and the dose/concentration-response effects of exposure to POPs in the development of obesity and other metabolic diseases.

Associations between both legacy and alternative per- and polyfluoroalkyl substances and glucose-homeostasis: The Isomers of C8 health project in China

BACKGROUND

Epidemiological studies on the associations of legacy per- and polyfluoroalkyl substances (PFASs) and glucose homeostasis remain discordant. Understanding of PFAS alternatives is limited, and few studies have reported joint associations of PFASs and PFAS alternatives.

OBJECTIVES

To investigate associations of novel PFAS alternatives (chlorinated perfluoroalkyl ether sulfonic acids, Cl-PFESAs and perfluorobutanoic acid, PFBA) and two legacy PFASs (Perfluorooctanoic acid, PFOA and perfluorooctane sulfonate, PFOS) with glucose-homeostasis markers and explore joint associations of 13 legacy and alternative PFASs with the selected outcomes.

METHODS

We used cross-sectional data of 1,038 adults from the Isomers of C8 Health Project in China. Associations of PFASs and PFAS alternatives with glucose-homeostasis were explored in single-pollutant models using generalized linear models with natural cubic splines for PFASs. Bayesian Kernel Machine Regression (BKMR) models were applied to assess joint associations of exposures and outcomes. Sex-specific analyses were also conducted to evaluate effect modification.

RESULTS

After adjusting for confounders, both legacy (PFOA, PFOS) and alternative (Cl-PFESAs and PFBA) PFASs were positively associated with glucose-homeostasis markers in single-pollutant models. For example, in the total study population, estimated changes with 95% confidence intervals (CI) of fasting glucose at the 95th percentile of 6:2Cl-PFESA and PFOS against the thresholds were 0.90 (95% CI: 0.59, 1.21) and 0.44 (95% CI: 0.26, 0.62). Positive joint associations were found in BKMR models with 6:2Cl-PFESA contributing most. Sex-specific associations existed in both single- and multi-pollutant models.

CONCLUSIONS

Legacy and alternative PFASs were positively associated with glucose-homeostasis markers. 6:2Cl-PFESA was the primary contributor. Sex-specific associations were also identified. These results indicate that joint associations and effect modification should be considered in risk assessment. However, further studies are recommended to strengthen our findings and to elucidate the mechanisms of action of legacy and alternative PFASs.

Systemic toxicity induced by topical application of heptafluorobutyric acid (PFBA) in a murine model

Heptafluorobutyric acid (PFBA) is a synthetic chemical belonging to the per- and polyfluoroalkyl substances (PFAS) group that includes over 5000 chemicals incorporated into numerous products. PFBA is a short-chain PFAS (C4) labeled as a safer alternative to legacy PFAS which have been linked to numerous health effects. Despite the high potential for dermal exposure, occupationally and environmentally, dermal exposure studies are lacking. Using a murine model, this study analyzed serum chemistries, histology, immune phenotyping, and gene expression to evaluate the systemic toxicity of sub-chronic dermal PFBA 15-day (15% v/v or 375 mg/kg/dose) or 28-day (3.75-7.5% v/v or 93.8-187.5 mg/kg/dose) exposures. PFBA exposure produced significant increases in liver and kidney weights and altered serum chemistries (all exposure levels). Immune-cell phenotyping identified significant increases in draining lymph node B-cells (15%) and CD11b + cells (3.75-15%) and skin T-cells (3.75-15%) and neutrophils (7.5-15%). Histopathological and gene expression changes were observed in both the liver and skin after dermal PFBA exposure. The findings indicate PFBA induces liver toxicity and alterations of PPAR target genes, suggesting a role of a PPAR pathway. These results demonstrate that sustained dermal exposure to PFBA induces systemic effects and raise concerns of short-chain PFAS being promoted as safer alternatives.

A mixture of persistent organic pollutants detected in human follicular fluid increases progesterone secretion and mitochondrial activity in human granulosa HGrC1 cells

Disruption of granulosa cells (GCs), the main functional cells in the ovary, is associated with impaired female fertility. Epidemiological studies demonstrated that women have detectable levels of organic pollutants (e.g., perfluorooctanoate, perfluorooctane sulfonate, 2,2-dichlorodiphenyldichloroethylene, polychlorinated biphenyl 153, and hexachlorobenzene) in their follicular fluid (FF), and thus these compounds may directly affect the function of GCs in the ovary. Considering that humans are exposed to multiple pollutants simultaneously, we elucidated the effects of a mixture of endocrine-disrupting chemicals (EDCs) on human granulosa HGrC1 cells. The EDC mixture directly increased progesterone secretion by upregulating 3β-hydroxysteroid dehydrogenase (3βHSD) expression. Furthermore, the EDC mixture increased activity of mitochondria, which are the central sites for steroid hormone biosynthesis, and the ATP content. Unexpectedly, the EDC mixture reduced glucose transporter 4 (GLUT4) expression and perturbed glucose uptake; however, this did not affect the glycolytic rate. Moreover, inhibition of GLUT1 by STF-31 did not alter the effects of the EDC mixture on steroid secretion but decreased basal estradiol secretion. Taken together, our results demonstrate that the mixture of EDCs present in FF can alter the functions of human GCs by disrupting steroidogenesis and may thus adversely affect female reproductive health. This study highlights that the EDC mixture elicits its effects by targeting mitochondria and increases mitochondrial network formation, mitochondrial activity, and expression of 3βHSD, which is associated with the inner mitochondrial membrane.

Life-course Exposure to Perfluoroalkyl Substances in Relation to Markers of Glucose Homeostasis in Early Adulthood

OBJECTIVE

To investigate the prospective associations of life-course perfluoroalkyl substances (PFASs) exposure with glucose homeostasis at adulthood.

METHODS

We calculated insulin sensitivity and beta-cell function indices based on 2-h oral glucose tolerance tests at age 28 in 699 Faroese born in 1986-1987. Five major PFASs were measured in cord whole blood and in serum from ages 7, 14, 22, and 28 years. We evaluated the associations with glucose homeostasis measures by PFAS exposures at different ages using multiple informant models fitting generalized estimating equations and by life-course PFAS exposures using structural equation models.

RESULTS

Associations were stronger for perfluorooctane sulfonate (PFOS) and suggested decreased insulin sensitivity and increased beta-cell function-for example, β (95% CI) for log-insulinogenic index per PFOS doubling = 0.12 (0.02, 0.22) for prenatal exposures, 0.04 (-0.10, 0.19) at age 7, 0.07 (-0.07, 0.21) at age 14, 0.05 (-0.04, 0.15) at age 22, and 0.04 (-0.03, 0.11) at age 28. Associations were consistent across ages (P for age interaction > 0.10 for all PFASs) and sex (P for sex interaction > 0.10 for all PFASs, except perfluorodecanoic acid). The overall life-course PFOS exposure was also associated with altered glucose homeostasis (P = 0.04). Associations for other life-course PFAS exposures were nonsignificant.

CONCLUSIONS

Life-course PFAS exposure is associated with decreased insulin sensitivity and increased pancreatic beta-cell function in young adults.

Plasma lipid metabolites associate with diabetic polyneuropathy in a cohort with type 2 diabetes

OBJECTIVE

The global rise in type 2 diabetes is associated with a concomitant increase in diabetic complications. Diabetic polyneuropathy is the most frequent type 2 diabetes complication and is associated with poor outcomes. The metabolic syndrome has emerged as a major risk factor for diabetic polyneuropathy; however, the metabolites associated with the metabolic syndrome that correlate with diabetic polyneuropathy are unknown.

METHODS

We conducted a global metabolomics analysis on plasma samples from a subcohort of participants from the Danish arm of Anglo-Danish-Dutch study of Intensive Treatment of Diabetes in Primary Care (ADDITION-Denmark) with and without diabetic polyneuropathy versus lean control participants.

RESULTS

Compared to lean controls, type 2 diabetes participants had significantly higher HbA1c (p = 0.0028), BMI (p = 0.0004), and waist circumference (p = 0.0001), but lower total cholesterol (p = 0.0001). Out of 991 total metabolites, we identified 15 plasma metabolites that differed in type 2 diabetes participants by diabetic polyneuropathy status, including metabolites belonging to energy, lipid, and xenobiotic pathways, among others. Additionally, these metabolites correlated with alterations in plasma lipid metabolites in type 2 diabetes participants based on neuropathy status. Further evaluating all plasma lipid metabolites identified a shift in abundance, chain length, and saturation of free fatty acids in type 2 diabetes participants. Importantly, the presence of diabetic polyneuropathy impacted the abundance of plasma complex lipids, including acylcarnitines and sphingolipids.

INTERPRETATION

Our explorative study suggests that diabetic polyneuropathy in type 2 diabetes is associated with novel alterations in plasma metabolites related to lipid metabolism.

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances and birth outcomes: A longitudinal cohort with repeated measurements

BACKGROUND

Previous studies on perfluoroalkyl and polyfluoroalkyl substances (PFAS) showed inconsistent results when biological samples were collected in different time of pregnancy.

OBJECTIVES

To describe the change of PFAS concentration during pregnancy and to identify a sensitive window for adverse effects of PFAS on the fetus.

METHODS

A total of 255 pregnant women were selected from the Shanghai Birth Cohort (SBC). We quantified 10 PFAS with high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) in maternal plasma at three trimesters and cord blood at delivery. Multiple linear regression analyses were used to analyze the association between PFAS and birth outcomes, including birth weight, birth length, and head circumference.

RESULTS

The concentrations of most PFAS declined substantially during pregnancy. PFOS, PFNA, PFDA, PFUA and PFDoA were negatively related to birth length only in the first trimester. The coefficients and 95% confidence intervals (CI) of birth length change with a log-unit increase in PFOS, PFNA, PFDA, PFUS and PFDoA concentrations were -0.27 cm (-0.51, -0.02), -0.34 cm (-0.65, -0.03), -0.27 cm (-0.53, -0.01), -0.29 cm (-0.58, -0.01), and -0.54 cm (-1.00, -0.08), respectively. The effects were only observed for female fetuses. No association between PFAS and birth weight or head circumference was observed.

CONCLUSION

The concentrations of most PFAS in the maternal circulation declined during pregnancy. There were negative associations between several PFAS and birth length. The sensitive window of exposure appeared to be the first trimester. The association was stronger for female fetuses.

Early Life Exposures to Perfluoroalkyl Substances in Relation to Adipokine Hormone Levels at Birth and During Childhood

BACKGROUND

Birth cohort studies have linked exposure to perfluoroalkyl substances (PFASs) with child anthropometry. Metabolic hormone dysregulation needs to be considered as a potential adverse outcome pathway. We examined the associations between PFAS exposures and concentrations of adipokine hormones from birth to adolescence.

METHODS

We studied 80 mother-child pairs from a Faroese cohort born in 1997 to 2000. Five PFASs were measured in maternal pregnancy serum and in child serum at ages 5, 7, and 13 years. Leptin, adiponectin, and resistin were analyzed in cord serum and child serum at the same ages. We fitted multivariable-adjusted generalized estimating equations to assess the associations of PFASs at each age with repeated adipokine concentrations at concurrent and subsequent ages.

RESULTS

We observed tendencies of inverse associations between PFASs and adipokine hormones specific to particular ages and sex. Significant associations with all adipokines were observed for maternal and child 5-year serum PFAS concentrations, whereas associations for PFASs measured at ages 7 to 13 years were mostly null. The inverse associations with leptin and adiponectin were seen mainly in females, whereas the inverse PFAS associations with resistin levels were seen mainly in males. Estimates for significant associations (P value <0.05) suggested mean decreases in hormone levels (range) by 38% to 89% for leptin, 16% to 70% for adiponectin, and 33% to 62% for resistin for each twofold increase in serum PFAS concentration.

CONCLUSIONS

These findings suggest adipokine hormone dysregulation in early life as a potential pathway underlying PFAS-related health outcomes and underscore the need to further account for susceptibility windows and sex-dimorphic effects in future investigations.

Perfluoroalkyl acids serum concentrations and their relationship to biomarkers of renal failure: Serum and urine albumin, creatinine, and albumin creatinine ratios across the spectrum of glomerular function among US adults

Associations between selected perfluoroalkyl acids (PFAAs) and biomarkers of renal function were evaluated for US adult aged ≥ 20 years (N = 8220) in the National Health and Nutrition Examination Survey for 2005-2014. Glomerular filtration (GF) stage-stratified regression models were classified by estimated glomerular filtration rate (eGFR) with GF-1 (eGFR > 90 mL/min/1.73 m2), GF-2 (eGFR 60-89 mL/min/1.73 m2), GF-3A (45-59 mL/min/1.73 m2), and GF-3B/4 (15-44 mL/min/1.73 m2). For GF-1, PFOA, PFOS, and PFHxS were positively and significantly associated with serum creatinine. Serum albumin levels were positively associated with the PFAA considered at all stages and most associations were significant. Further, PFAS serum concentration associations to serum albumin were about 2-3 times stronger at GF-3B/4 than at GF-1. In contrast, urine albumin was negatively and significantly associated with PFOA and PFHxS serum concentrations at all stages of renal function, while, PFOS and PFNA were negatively and significantly associated to urine albumin at GF-3A and GF-3B/4. Urine albumin/creatinine ratios were negatively and significantly associated with PFOA, PFOS, and, and PFHxS serum concentrations at all stages of renal function, as well as with PFNA and PFDA at GF-3A and GF-3B/4. Recent work revealed that serum PFAAs have an inverted U-shaped association to the calculated stages of renal failure based on eGFR; this work adds that albuminuria makes additional negative contributions to already existing negative associations of PFAA to eGFR in advancing stages of renal failure. We hypothesize that both progressive renal failure per se and especially renal failure with albuminuria cause the kidneys to reabsorb less and to excrete more of the PFAAs studied. We suspect this finding may generalize to some other perfluoroalkyl substances (PFAS). The findings also imply study design considerations for evaluating associations to diseases and biomarkers associated with renal failure, such as diabetes.

Environmental perfluoroalkyl acid exposures are associated with liver disease characterized by apoptosis and altered serum adipocytokines

Exposures to perfluoroalkyl substances (PFAS) including perfluoroalkyl acids (PFAAs) are associated with increased liver enzymes in cohort studies including the C8 Health Study. In animal models, PFAAs disrupt hepatic lipid metabolism and induce apoptosis to cause nonalcoholic fatty liver disease (NAFLD). PFAAs are immunotoxic and inhibit pro-inflammatory cytokine release from stimulated leukocytes in vitro. This cross-sectional study tests the hypothesis that environmental PFAAs are associated with increased hepatocyte apoptosis and decreased pro-inflammatory cytokines in serum. Biomarkers previously associated with PFAS exposures and/or NAFLD were evaluated as secondary endpoints. Two hundred adult C8 Health Study participants were included. Measured serum biomarkers included: perfluorohexane sulfonate (PFHxS); perfluorooctanoic acid (PFOA); perfluorooctane sulfonate (PFOS); perfluorononanoic acid (PFNA); cytokeratin 18 M30 (CK18 M30, hepatocyte apoptosis); adipocytokines; insulin; and cleaved complement 3 (C3a). Confounder-adjusted linear regression models determined associations between PFAS and disease biomarkers with cut-offs determined by classification and regression tree analysis. CK18 M30 was positively associated with PFHxS (β = 0.889, p = 0.042); PFOA (β = 2.1, p = 0.005); and PFNA (β = 0.567, p = 0.03). Tumor necrosis factor α (TNFα) was inversely associated with PFHxS (β = -0.799, p = 0.001); PFOA (β = - 1.242, p = 0.001); and PFOS (β = -0.704, p < 0.001). Interleukin 8 was inversely associated with PFOS and PFNA. PFAAs were also associated with sexually dimorphic adipocytokine and C3a responses. Overall, PFAA exposures were associated with the novel combination of increased biomarkers of hepatocyte apoptosis and decreased serum TNFα. These data support previous findings from cohorts and experimental systems that PFAAs may cause liver injury while downregulated some aspects of the immune response. Further studies of PFAAs in NAFLD are warranted and should evaluate sex differences.