PFO5DoDA disrupts hepatic homeostasis primarily through glucocorticoid signaling inhibition

Single-cell RNA sequencing reveals the heterogeneity of hepatic non-parenchymal cell responses to chronic PFO5DoDA exposure in male mice

Perfluoroalkyl ether carboxylic acids (PFECA) have emerged as novel alternatives to legacy per- and polyfluoroalkyl substances (PFAS). Existing research has revealed hepatoxicity induced by various PFAS, including PFECA. However, these studies have primarily focused on overall changes in whole liver tissue, particularly in hepatocytes, with the impact of PFAS on diverse liver non-parenchymal cells (NPCs) still inadequately understood. In the present study, we examined the heterogeneous responses of hepatic NPCs following exposure to perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoDA), a type of PFECA, by administering PFO5DoDA (5 μg/L)-contaminated water to male mice for one year. Single-cell RNA sequencing (scRNA-seq) of 15 008 cells from the liver identified 10 distinct NPC populations. Notably, although relative liver weight remained largely unchanged following exposure to 5 μg/L PFO5DoDA, there was an observed increase in proliferating cells, indicating that proliferating NPCs may contribute to the hepatomegaly frequently noted in PFAS-exposed livers. There was also a considerable alteration in the composition of hepatic NPCs. Specifically, the total number of B cells decreased substantially, while many other cells, such as monocytes and macrophages, increased after PFO5DoDA exposure. In addition, interactions among the hepatic NPC populations changed variously after PFO5DoDA exposure. The findings emphasize the heterogeneity in the responses of hepatic NPCs to PFO5DoDA exposure. Taken together, the changes in immune cell populations and their intercellular interactions suggest that PFO5DoDA disrupts immune homeostasis in the liver. These findings offer new insights into the cellular mechanisms of PFAS-induced liver damage.

Dietary exposure to per- and polyfluoroalkyl substances: Potential health impacts on human liver

Per- and polyfluoroalkyl substances (PFAS), dubbed "forever chemicals", are widely present in the environment. Environmental contamination and food contact substances are the main sources of PFAS in food, increasing the risk of human dietary exposure. Numerous epidemiological studies have established the link between dietary exposure to PFAS and liver disease. Correspondingly, PFAS induced-hepatotoxicity (e.g., hepatomegaly, cell viability, inflammation, oxidative stress, bile acid metabolism dysregulation and glycolipid metabolism disorder) observed from in vitro models and in vivo rodent studies have been extensively reported. In this review, the pertinent literature of the last 5 years from the Web of Science database was researched. This study summarized the source and fate of PFAS, and reviewed the occurrence of PFAS in food system (natural and processed food). Subsequently, the characteristics of human dietary exposure PFAS (population characteristics, distribution trend, absorption and distribution) were mentioned. Additionally, epidemiologic evidence linking PFAS exposure and liver disease was alluded, and the PFAS-induced hepatotoxicity observed from in vitro models and in vivo rodent studies was comprehensively reviewed. Lastly, we highlighted several critical knowledge gaps and proposed future research directions. This review aims to raise public awareness about food PFAS contamination and its potential risks to human liver health.

Accumulation and glucocorticoid signaling suppression by four emerging perfluoroethercarboxylic acids based on animal exposure and cell testing

Various perfluoroethercarboxylic acids (PFECA) have emerged as next-generation replacements of legacy per- and polyfluoroalkyl substances (PFAS). However, there is a paucity of information regarding their bioaccumulation ability and hazard characterization. Here, we explored the accumulation and hepatotoxicity of four PFECA compounds (HFPO-DA, HFPO-TA, PFO4DA, and PFO5DoDA) in comparison to perfluorooctanoic acid (PFOA) after chronic low-dose exposure in mice. Except for HFPO-DA, the levels of all tested PFAS in the liver exceeded that in serum. High molecular weight PFECA compounds (PFO5DoDA and HFPO-TA) showed stronger accumulation capacity and longer half-lives (t1/2) than low molecular weight PFECA compounds (HFPO-DA and PFO4DA) and even legacy PFOA. Although hepatomegaly is a common apical end point of PFAS exposure, the differentially expressed gene (DEG) profiles in the liver suggested significant differences between PFOA and the four PFECA compounds. Gene enrichment analysis supported a considerable inhibitory effect of PFECA, but not PFOA, on the glucocorticoid receptor (GR) signaling pathway. Both HFPO-TA and PFO5DoDA demonstrated a more pronounced ability to perturb RNA expression profiles in vivo and to suppress GR signaling in vitro compared to HFPO-DA and PFO4DA. Calculated reference doses (RfDs) emphasized the potential hazard of PFECA to human health. Overall, our findings indicate that PFECA alternatives do not ease the concerns raised from legacy PFAS pollution.

Perfluoroalkyl Substances (PFAS) Affect Inflammation in Lung Cells and Tissues

Adverse lung outcomes from exposure to per-and polyfluoroalkyl substances (PFAS) are known; however, the mechanism of action is poorly understood. To explore this, human bronchial epithelial cells were grown and exposed to varied concentrations of short-chain (perfluorobutanoic acid, perflurobutane sulfonic acid and GenX) or long-chain (PFOA and perfluorooctane sulfonic acid (PFOS)) PFAS, alone or in a mixture to identify cytotoxic concentrations. Non-cytotoxic concentrations of PFAS from this experiment were selected to assess NLRP3 inflammasome activation and priming. We found that PFOA and PFOS alone or in a mixture primed and activated the inflammasome compared with vehicle control. Atomic force microscopy showed that PFOA but not PFOS significantly altered the membrane properties of cells. RNA sequencing was performed on the lungs of mice that had consumed PFOA in drinking water for 14 weeks. Wild type (WT), PPARα knock-out (KO) and humanized PPARα (KI) were exposed to PFOA. We found that multiple inflammation- and immune-related genes were affected. Taken together, our study demonstrated that PFAS exposure could alter lung biology in a significant manner and may contribute to asthma/airway hyper-responsiveness.