Effects of perfluorobutane sulfonate and perfluorooctane sulfonate on lipid homeostasis in mouse liver

Neurotoxic effects of chronic exposure to perfluorobutane sulfonate in adult zebrafish (Danio Rerio)

Per and polyfluoroalkyl substances (PFAS) are synthetic compounds extensively utilized in industrial applications and consumer products. Long-chain PFAS has been linked to negative health impacts, prompting the introduction of shorter-chain alternatives like perfluorobutane sulfonate (PFBS). While long-chain PFAS are known to induce oxidative stress, neuroinflammation, and neuronal apoptosis, the neurotoxic potential of short-chain PFAS like PFBS was not well studied. This study aims to evaluate the neurotoxic effect and bioaccumulation of PFBS on adult zebrafish. In this study, adult zebrafish were exposed to PFBS at concentrations of 0.14, 1.4, and 14 μM for 28 days. PFBS accumulation in zebrafish brain tissue was confirmed by specific mass spectrum peaks. Behavioral assays revealed significant anxiety-like behavior, with PFBS (14 μM) exposed zebrafish spending more time in the bottom zone of the novel tank diving test (179.33 ± 1.03 s) and in the light and dark preference results showed increased time spent in the dark zone (165.17 ± 10.89 s). Learning and memory deficits were evident in the T-maze test, where PFBS-exposed zebrafish spent less time in the favorable zone (0.67 ± 1.15 s). Biochemical analysis showed significant inhibition of acetylcholinesterase (AChE) activity in the male and female brains (0.06 μmol/min and 0.09 μmol/min). Antioxidant enzyme levels were reduced, with superoxide dismutase (SOD) 5.45 U/mg protein in the male brain and 4.06 U/mg protein in the female brain, leading to increased oxidative stress biomarkers like lipid peroxidation and nitric oxide levels in male (0.99 μmol/mg/ml and 8.85 μM) and female brain (1.83 μmol/mg/ml and 8.74 μM), respectively. Gene expression analysis demonstrated the downregulation of SOD, CAT, GSR, and GPx, indicating impaired antioxidant defense mechanisms. Histopathological analysis of PFBS exposure groups revealed vacuolation and increased pyknotic neurons in the optic tectum region of the brain. Our study suggests that PFBS exposure leads to bioaccumulation in the brain, causing histopathological changes and cognitive impairment. In conclusion, PFBS induces neurotoxicity which can be a potential risk as they are incorporated into a range of consumer products.

Reproductive toxicity of perfluorobutane sulfonate in zebrafish (Danio rerio): Impacts on oxidative stress, hormone disruption and HPGL axis dysregulation

Per and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals extensively used in consumer products. Perfluorobutane sulfonate (PFBS), a short-chain PFAS, has been introduced as an alternative to long-chain PFAS, but limited studies have investigated its reproductive toxicity in fish. In this study, adult zebrafish were exposed to PFBS at concentrations of 0.14, 1.4, and 14 μM for 28 days. PFBS accumulation in male and female gonads was confirmed by specific mass spectrum peaks detected in exposed samples. PFBS exposure at 14 μM significantly reduced egg production and hatching rates. The gonadosomatic index (GSI) was decreased by 73 % in males and 50 % in females compared to the control. PFBS impaired antioxidant enzyme activity, with superoxide dismutase (SOD) 4.73 U/mg protein in testes and 3.46 U/mg protein in ovaries, leading to elevated lipid peroxidation and nitric oxide levels in males (0.053 μmol/mg/ml and 5.65 μM) and females (0.047 μmol/mg/ml and 4.01 μM), respectively. PFBS exposure induced endocrine disruption through the hypothalamic-pituitary-gonadal-liver (HPGL) axis, showing increased estrogen (50 pg/g) in males and testosterone (181.6 pg/g) in females. Gene expression analysis revealed significant alteration in the HPGL axis, including cyp19b, er2b, fshb, lhb, 17βhsd, lhr, cyp19a, and vtg, indicating PFBS influence on sex hormone synthesis. Histopathological analysis of PFBS exposure groups revealed a reduction of spermatozoa in the testes and late vitellogenic oocytes in the ovaries. Overall, the result of the present study indicates that PFBS exposure induces oxidative stress, disrupts hormone synthesis, dysregulates HPGL axis gene expression, and causes reproductive toxicity in both male and female zebrafish.

Combined toxicity of polystyrene microplastics and perfluorobutane sulfonate on mouse liver: Impact on lipid metabolism and gut-liver axis disruption

Microplastics (MPs) in the environment can adsorb perfluoroalkyl substance (PFAS), leading to combined toxicity in various organisms. Most researches have focused on single-exposure effects on mouse liver, with limited studies on the mechanisms behind the combined effects of polystyrene microplastics (PS-MPs) and perfluorobutane sulfonate (PFBS). This study analyzed the single and combined toxic effects of PS-MPs (10 mg/kg) and PFBS (30 mg/kg PFBSL or 300 mg/kg PFBSH) on mouse liver. Results indicated that PFBS was adsorbed by PS-MPs, affecting PFBS accumulation. Co-exposure significantly increased liver injury biomarkers in serum, associated with heightened oxidative stress, inflammation, and lipid accumulation. Metabolomics analyses revealed that the co-exposure had the most pronounced impact on lipid metabolism disorders, followed by PFBS and PS-MPs. Additionally, exposure to PS-MPs and PFBS induced gut microbiota dysbiosis and gut barrier disruption, disturbing lipid metabolism - particularly bile acids and short-chain fatty acids - along the gut-liver axis, thereby causing liver injury. Notably, co-exposure, particularly with high-concentration PFBS, significantly aggravated these effects. This study highlights the combined effects of PS-MPs and PFBS on liver function though lipid metabolism disorders and gut-liver axis imbalance, providing valuable insights into the health risks associated with these pollutants.

Insights into toxicological mechanisms of per-/polyfluoroalkyl substances by using omics-centered approaches

The extensive presence of per-/polyfluoroalkyl substances (PFASs) in the environment and their adverse effects on organisms have garnered increasing concern. With the shift of industrial development from legacy to emerging PFASs, expanding the understanding of molecular responses to legacy and emerging PFASs is essential to accurately assess their risks to organisms. Compared with traditional toxicological approaches, omics technologies including transcriptomics, proteomics, metabolomics/lipidomics, and microbiomics allow comprehensive analysis of the molecular changes that occur in organisms after PFAS exposure. This paper comprehensively reviews the insights of omics approaches, especially the multi-omics approach, on the toxic mechanisms of both legacy and emerging PFASs in recent five years, focusing on hepatotoxicity, developmental toxicity, immunotoxicity, reproductive toxicity, neurotoxicity, and the endocrine-disrupting effect. PFASs exert various toxic effects via lipid and amino acid metabolism disruption, perturbations in several cell signal pathways, and binding to nuclear receptors. Notably, integrating multi-omics offers a thorough insight into the mechanisms of toxicity associated with PFASs. The gut microbiota plays an essential regulatory role in the toxic mechanisms of PFAS-induced hepatotoxicity. Finally, further research directions for PFAS toxicology based on omics technologies are prospected.

Mass Spectrometry-Based Spatial Multiomics Revealed Bioaccumulation Preference and Region-Specific Responses of PFOS in Mice Cardiac Tissue

The distribution and bioaccumulation of environmental pollutants are essential to understanding their toxicological mechanism. However, achieving spatial resolution at the subtissue level is still challenging. Perfluorooctanesulfonate (PFOS) is a persistent environmental pollutant with widespread occurrence. The bioaccumulation behavior of PFOS is complicated by its dual affinity for phospholipids and protein albumin. It is intriguing to visualize the distribution preference of PFOS and investigate the differential microenvironment responses at a subtissue level. Herein, we developed a mass-spectrometry (MS)-based spatial multiomics workflow, integrating matrix-assisted laser desorption/ionization MS imaging, laser microdissection, and liquid chromatography MS analysis. This integrated workflow elucidates the spatial distribution of PFOS in mouse cardiac tissue, highlighting its preferential accumulation in the pericardium over the myocardium. This distribution pattern results in greater toxicity to the pericardium, significantly altering cardiolipin levels and disrupting energy metabolism and lipid transport pathways. Our integrated approach provides novel insights into the bioaccumulation behavior of PFOS and demonstrates significant potential for revealing complex molecular mechanisms underlying the health impacts of environmental pollutants.

A comprehensive multiplatform metabolomic analysis reveals alterations of 2-hydroxybutyric acid among women with deep endometriosis related to the pesticide trans-nonachlor

BACKGROUND

Exposure to persistent organic pollutants (POPs) has been related to the risk of endometriosis however the mechanisms remain unclear. The objective of the present study was to characterize the metabolic profiles underpinning the associations between POPs and endometriosis risk.

METHODOLOGY

A hospital-based case-control study was conducted in France to recruit women with and without surgically confirmed deep endometriosis. Women's serum was analyzed using gas and liquid chromatography coupled to high-resolution mass spectrometry (HRMS) to measure the levels of polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and per-/polyfluoroalkyl substances (PFAS). A comprehensive metabolomic profiling was conducted using targeted HRMS and 1H nuclear magnetic resonance (1H NMR) to cover polar and non-polar fractions. A "meet-in-the-middle" statistical framework was applied to identify the metabolites related to endometriosis and POP levels, using multivariate linear and logistic regressions adjusting for confounding variables.

RESULTS

Fourteen PCBs, six OCPs and six PFAS were widely found in almost all serum samples. The pesticide trans-nonachlor was the POP most strongly and positively associated with deep endometriosis risk, with odds ratio (95 % confidence interval) of 2.42 (1.49; 4.12), followed by PCB180 and 167. Women with endometriosis exhibited a distinctive metabolic profile, with elevated serum levels of lactate, ketone bodies and multiple amino acids and lower levels of bile acids, phosphatidylcholines (PCs), cortisol and hippuric acid. The metabolite 2-hydroxybutyrate was simultaneously associated to endometriosis risk and exposure to trans-nonachlor.

CONCLUSIONS

To the best of our knowledge, this is the first comprehensive metabolome-wide association study of endometriosis, integrating ultra-trace profiling of POPs. The results confirmed a metabolic alteration among women with deep endometriosis that could be also associated to the exposure to POPs. Further observational and experimental studies will be required to delineate the causal ordering of those associations and gain insight on the underlying mechanisms.

Toxicity Assessment of Mixed Exposure of Nine Perfluoroalkyl Substances at Concentrations Relevant to Daily Intake

Per- and poly-fluoroalkyl substances (PFAS) exhibit high persistence in the environment and accumulate within the human body, warranting a thorough assessment of their toxicity. In this study, we exposed mice (male C57BL/6J mice aged 8 weeks) to a composite of nine PFAS, encompassing both long-chain PFAS (e.g., perfluorooctanoic acid and perfluorooctanesulfonic acid) and short-chain PFAS (e.g., perfluorobutanoic acid and perfluorobutanesulfonic acid). The exposure concentrations of PFAS were equivalent to the estimated daily human intake in the composition reported (1 µg/L (sum of the nine compounds), representing the maximum reported exposure concentration). Histological examination revealed hepatocyte vacuolization and irregular hepatocyte cord arrangement, indicating that exposure to low levels of the PFAS mixture causes morphological changes in liver tissues. Transcriptome analysis revealed that PFAS exposure mainly altered a group of genes related to metabolism and chemical carcinogenesis. Machine learning analysis of the liver metabolome showed a typical concentration-independent alteration upon PFAS exposure, with the annotation of substances such as glutathione and 5-aminovaleric acid. This study demonstrates that daily exposure to PFAS leads to morphological changes in liver tissues and alters the expression of metabolism- and cancer-related genes as well as phospholipid metabolism.