Perfluoroalkyl sulfonate induces cardiomyocyte apoptosis via endoplasmic reticulum stress activation and autophagy flux inhibition

Exposure to PFOS, PFBS, PFOA and PFBA impairs cell cycle progression in bovine brain (Bos taurus) endothelial cells

Perfluoroalkylated substances (PFAS) are the large class of synthetic chemicals that persist in the environment and bioaccumulate in different tissues including the brain, inducing blood brain barrier (BBB) disruption. In this study, we assessed cytotoxicity of PFAS in a bovine brain endothelial cell line by exposing the cells to increasing concentrations (0.01, 0.1, 1, 10, and 100 μM) of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorobutane sulfonic acid (PFBS), perfluorobutanoic acid (PFBA) and perfluoro ([5-methoxy-1,3-dioxolan-4-yl]oxy) acetic acid (C6O4). Cell viability, cell cycle profiling and the apoptotic potential were then analyzed. Cells were categorized by grouping nuclei into G0 + G1, Synthesis (S) and Mitotic phases (M), nuclei showing characteristics of senescence and nuclear fragments. By combining high throughput screening with cell nuclei counting for group, we determined the relationship between the dose-response effect of PFAS and their proliferative potential. Our results showed that PFOS decreased the number of cells in S and M phase. PFBS reduced the number of cells in M phase, decreased the senescence phenotype and increased the number of fragment nuclei. PFOA enhanced the number of cells nuclei in S and M phase. The PFBA enhanced the number of nuclei in G0 + G1, S and M phase. C6O4 did not show significant variation under any of the experimental conditions tested. We did not find significant changes in terms of cell viability assay. This bovine endothelial cell line provides an alternative model for studying the mechanisms involved in the decrease of BBB integrity due to PFAS accumulation in a large mammal with large brain.

Icaritin Represses Autophagy to Promote Colorectal Cancer Cell Apoptosis and Sensitized Low-Temperature Photothermal Therapy via Targeting HSP90-TXNDC9 Interactions

Colorectal cancer (CRC) ranks among the leading causes of cancer-related dea ths worldwide, and the rising incidence and mortality of CRC underscores the urgent need for better understanding and management strategies. Icaritin (ICA) is the metabolites of icariin, a natural flavonoid glycoside compound derived from the stems and leaves of Epimedium. It has broad spectrum antitumor activity and inhibits the proliferation, migration, and invasion of CRC cells, and causes S phase cell cycle arrest. It exerts its antitumor effects against CRC through repressing autophagy to promote CRC cell apoptosis via interfering the HSP90-TXNDC9 interactions. The safety and efficacy of ICA are also affirmed in a mouse xenograft model. Additionally, to test whether ICA exerts synergistic effects with low-temperature photothermal therapy (LTPTT), a novel nanodrug delivery system, employing SiO2 nanocarriers, is designed aiming to load ICA with photothermal materials polydopamine (PDA), and folic acid (FA). This SiO2/Ica-PDA-FA multifunctional nanocomposite actively targets tumor tissues through the high affinity of FA for cancer cells. Once internalized, the acidic intracellular environment triggers the controlled release of ICA, inhibiting HSP90-TXNDC9 interactions. By LTPTT and ICA drug therapy under near-infrared illumination, a dual synergistic antitumor effect is achieved, holding promise for enhancing therapeutic outcomes in CRC treatment.

Perfluorooctane sulfonic acid: a possible risk factor of endothelial dysfunction based on in silico and in vitro studies

Perfluorooctane sulfonic acid (PFOS) is a fluorinated chemical utilized in a variety of industrial and household products. PFOS has been detected in human serum and is associated with multiple human adverse health effects. Epidemiological evidence has linked PFOS exposure to endothelial dysfunction, which is a key contributor to atherosclerosis. However, the underlying mechanisms of PFOS-induced endothelial dysfunction associated atherosclerosis has not been investigated. In the present study, human microvascular endothelial cells (HMEC-1) exposed to PFOS (15 μM) for 72 h, mimicking long-term exposure. We further employed integrated RNA-sequencing (RNA-seq) and transcriptomic analysis to identify differentially expressed genes (DEGs) for biological alterations: gene ontology (GO), pathway enrichment analysis (KEGG), protein-protein interaction network and modular clustering analysis. Furthermore, the Metascape database was used for disease association, tissue specificity, and transcription factor analysis. Hub genes were verified using atherosclerosis patient data sets from the GEO dataset. Alteration of hub genes in patients was then validated using immunoblotting and ELISA. Our results revealed that PFOS altered amino acid biosynthesis, lipid metabolism and induced the ER-stress response through the HRI/eIF2α/ATF4 pathway, leading to endothelial dysfunction. Interestingly, we found that PFOS induced inflammation by increasing COX-2, ICAM-1 and IL-6 expression through NF-κB and JAK2/STAT3 pathway in endothelial cells. Moreover, up-regulated C/EBPβ and ATF4 were observed in both patients and PFOS-exposed endothelium, which may use as an early biomarker and may have a potential role in PFOS-induced endothelial dysfunction. These findings provide novel insight into the underlying molecular mechanisms of PFOS-induced endothelial dysfunction associated with atherosclerosis.

Dissection of the potential mechanism of polystyrene microplastic exposure on cardiomyocytes

Microplastics (MPs) are ubiquitous in the global biosphere, have widespread contact with humans, and increase exposure risks. Increasing evidence indicates that MPs exposure increases the risks of cardiovascular disease, however, a comprehensive exploration of the fundamental cellular mechanisms has yet to be undertaken. In this study, we used AC16 cells as a model and exposed them to 10 to 50 μg/mL of polystyrene MPs (PS-MPs), chosen based on the average daily intake and absorption of MPs by humans, to investigate their roles and mechanisms in cell injury. Proteomic analysis reveals that PS-MP-induced differentially expressed genes were enriched on endoplasmic reticulum (ER) stress and autophagy-related entries. The findings from immunofluorescence and western blotting provided further verification of the activation of ER stress by PS-MPs. Although the expression of LC3-II, a canonical autophagy marker was increased, PS-MPs inhibited autophagic flux instead of inducing autophagy. Importantly, ER stress not only contributes to PS-MPs-induced cell injury but also involved in PS-MPs-induced autophagic flux inhibition. Furthermore, the inhibition of autophagy, and the partial restoration of cell injury induced by PS-MPs was achieved through the activation of autophagy. Overall, the results reveal that activation of ER stress and inhibition of autophagic flux plays a significant role in the cell injury caused by PS-MPs in human cardiomyocytes, offering a novel perspective on the mechanism behind MPs-induced cardiomyocyte toxicity.

Exploring the neurodegenerative potential of per- and polyfluoroalkyl substances through an adverse outcome pathway network

While emerging evidence links per- and polyfluoroalkyl substances (PFAS) to neurotoxicity, their potential role in neurodegeneration remains poorly understood. Moreover, existing neurodegeneration-related adverse outcome pathways (AOPs) available on AOP-Wiki have not yet been integrated into a unified network. To address these gaps, this study aims to develop the first neurodegeneration-related AOP network and utilize it to explore the possible contributions of long-chain legacy PFAS to neurodegeneration, specifically concerning Alzheimer's and Parkinson's diseases. A total of 74 AOPs were screened from AOP-Wiki, of which 13 neurodegeneration-related AOPs met the eligibility criteria and were incorporated into a network. We analyzed the resulting AOP network using topological parameters such as in-degree, out-degree, eccentricity, and betweenness centrality. To elucidate the mechanistic contributions of PFAS exposure to neurodegenerative pathways, we integrated evidence linking PFAS exposure to key events (KEs) within the network. The results highlighted increased intracellular calcium as the network hub with the highest connectivity followed by critical KEs such as neurodegeneration, neuronal apoptosis, oxidative stress, N-methyl-d-aspartate receptor (NMDA-R) overactivation, and mitochondrial dysfunction. Consistent with toxicological evidence, the pathways highlighted by the AOP network indicate that PFAS may adversely affect neurotransmitter systems, particularly through NMDA-R overactivation, leading to excitotoxicity. This may result in calcium dyshomeostasis, mitochondrial dysfunction, inflammatory-oxidative cascades, neuroinflammation, and neuronal cell death. By providing a mechanistic basis for understanding the neurodegenerative potential of PFAS, this study offers a crucial framework for assessing the risks associated with these chemicals which may inform future regulatory measures and public health strategies. Further experimental validation is needed to confirm the mechanistic contributions of PFAS exposure in neurodegeneration, particularly in animal models or human populations.

Perfluorooctane sulfonate mediates GSH degradation leading to oral keratinocytes ferroptosis and mucositis through activation of the ER stress-ATF4-CHAC1 axis

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that induces inflammatory response and oxidative stress in oral mucosa. Ferroptosis, a form of cell death characterized by iron-dependent lipid peroxidation (the oxidative degradation of lipids), was believed to play a crucial role in pathogenesis of oral mucositis; however, the involvement of PFOS-induced ferroptosis remained unclear. Our findings demonstrated that PFOS inhibited proliferation and induced pro-apoptotic effects in oral cells, with the most pronounced effects observed in human oral keratinocytes (HOK). PFOS significantly increased reactive oxygen species (ROS) and lipid peroxidation, and depleted glutathione (GSH) in HOK cells. Notably, PFOS decreased glutathione peroxidase 4 (GPX4) expression and elevated Fe2 + levels, suggesting a potential induction of ferroptosis. Ferroptosis inhibitors mitigated PFOS-induced lipid peroxidation and GSH depletion, subsequently enhancing cell viability. Mechanistically, PFOS-induced endoplasmic reticulum (ER) stress contributed to the increased expression and nuclear translocation (from the cytoplasm into the nucleus) of activating transcription factor 4 (ATF4) and up-regulated its downstream target gene Chac1. Glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1) catalyzed the conversion of GSH into cysteinylglycine and 5-oxoproline, resulting in GSH depletion-a critical factor in PFOS-induced ferroptosis. Knocking down CHAC1 attenuated PFOS-induced ferroptosis. Tauroursodeoxycholic acid (TUDCA), the classical ER stress inhibitor, attenuated PFOS-induced oral keratinocytes ferroptosis and mucositis by inhibiting ATF4/CHAC1 pathway activation. These findings elucidated the toxicological mechanisms of PFOS and proposed potential therapeutic strategies to counteract PFOS exposure induced oral mucositis.

Perfluorooctane sulfonate causes DNA damage and apoptosis via oxidative stress in umbilical cord fibroblast cells of Yangtze finless porpoise

Yangtze finless porpoise (YFP) is a critically endangered species in China. It has been found that YFP is constantly exposed to perfluorooctane sulfonate (PFOS) in aquatic environments, leading to significant bioaccumulation. However, the impacts of PFOS on YFP health and survival are still unknown. To circumvent the limitations in YFP research, this study used YFP umbilical cord fibroblast cell line and exposed the cells to PFOS for 48 h, with objectives to uncover the cytotoxicity and mechanisms of PFOS in YFP. A high-throughput proteomics assay showed that PFOS exposure at 50 μM for 48 h perturbed the proteome structure in YFP umbilical cord fibroblast cells. Functional annotation found the high relevance of oxidative stress, mitochondrial oxidative phosphorylation, and DNA damage to PFOS cytotoxic mechanisms. Concordantly, PFOS exposure significantly increased the deposition of reactive oxygen species (ROS) in YFP cells. The potential of mitochondria to produce ATP was also compromised by PFOS, which was accompanied by the higher permeability of mitochondrial membrane. In addition, exposure of YFP umbilical cord fibroblast cells to 50 μM PFOS damaged the DNA assembly as evidenced by the increase in the percentage of DNA fragmentation. Gene transcription and enzymatic activity of caspases were up-regulated by PFOS, subsequently favoring the occurrence of early and late apoptosis. It was notable that ROS scavenger could successfully mitigate the cytotoxicity of PFOS on oxidative stress and apoptosis, thus pinpointing ROS as the molecular initiating event in apoptosis endpoints. To our knowledge, this is the first study that investigates the detrimental effects of PFOS using YFP umbilical cord fibroblast cells. The data will support an accurate assessment of ecological risks imposed by environmental pollutants on the health and sustainability of YFP, which is especially important under the context of sharp decline in YFP population and national initiative in YFP conservation.