Immunometabolism-modulation and immunotoxicity evaluation of perfluorooctanoic acid in macrophage

Per- and polyfluoroalkyl substances alter innate immune function: evidence and data gaps

Per- and polyfluoroalkyl substances (PFASs) are a large class of compounds used in a variety of processes and consumer products. Their unique chemical properties make them ubiquitous and persistent environmental contaminants while also making them economically viable and socially convenient. To date, several reviews have been published to synthesize information regarding the immunotoxic effects of PFASs on the adaptive immune system. However, these reviews often do not include data on the impact of these compounds on innate immunity. Here, current literature is reviewed to identify and incorporate data regarding the effects of PFASs on innate immunity in humans, experimental models, and wildlife. Known mechanisms by which PFASs modulate innate immune function are also reviewed, including disruption of cell signaling, metabolism, and tissue-level effects. For PFASs where innate immune data are available, results are equivocal, raising additional questions about common mechanisms or pathways of toxicity, but highlighting that the innate immune system within several species can be perturbed by exposure to PFASs. Recommendations are provided for future research to inform hazard identification, risk assessment, and risk management practices for PFASs to protect the immune systems of exposed organisms as well as environmental health.

Transcriptome and Metabolome analysis reveal HFPO-TA induced disorders of hepatic glucose and lipid metabolism in rat by interfering with PPAR signaling pathway

PFOA is one of the most representative compounds in the family of perfluorinated organic compounds. Due to its varying toxicity, alternatives to PFOA are beginning to emerge. HFPO-TA is an alternative for PFOA. It is currently unclear whether HFPO-TA affects glucose and lipid metabolism. In this study, rats were used as an animal model to investigate the effects of HFPO-TA on liver glucose and lipid metabolism. We found that HFPO-TA can affect glucose tolerance. Through omics analysis and molecular detection, it was found that HFPO-TA mainly affects the PPAR signaling pathway in the liver of rats, inhibiting liver glycolysis while promoting glucose production. HFPO-TA not only promotes the synthesis of fatty acids in the liver, but also promotes the breakdown of fatty acids, which ultimately leads to the disruption of hepatic glucose and lipid metabolism. The effects of HFPO-TA on metabolism are discussed in this paper to provide a reference for the risk assessment of this PFOA substitute.

Integrated evidence of transcriptional, metabolic, and intestinal microbiota changes in Ruditapes philippinarum due to perfluorooctanoic acid-induced immunotoxicity

Perfluorooctanoic acid (PFOA) is a toxic pollutant that bioaccumulates and is a significant public health concern due to its ubiquitous and persistent occurrence in global environments. Few studies have evaluated the adverse effects of PFOA on immune system, and this is particularly true for mollusks. Here, the PFOA-associated effects on immune system were evaluated in Ruditapes philippinarum using integrated analysis of metabolomes, microbiomes, and transcriptomes, providing evidence for possible mechanisms related to immunotoxicity. PFOA exposure caused clear variation in several important metabolites related to immune regulatory function within the haemolyph from R. philippinarum, while also altering key metabolic pathways, including those of lipids, unsaturated fatty acids (UFAs), and bile acids (BAs). After exposure to PFOAs, intestinal bacterial communities also clearly changed, with the predominant microflora becoming Mycoplasma and Bacteroidetes that are related to intestinal inflammation. Molecular analyses provided consistent results, wherein the expression of immune-related genes was significantly altered. Integration of the multi-'omics' analyses suggested that the TLR/MyD88/NF-kB pathway, along with PI3K-Akt-mTOR pathway, PPAR-mediated lipid metabolism and the autophagy signaling pathway, likely play important roles in initiating immunotoxic effects in R. philippinarum after PFOA exposure. These results provide further evidence that PFOA exposure can lead to immunologic dysfunction and also provide new insights into the mechanisms of PFAS alteration of bivalve immune function.

Perturbation of lipid metabolism in 3T3-L1 at different stages of preadipocyte differentiation and new insights into the association between changed metabolites and adipogenesis promoted by TBBPA or TBBPS

Tetrabromobisphenol A (TBBPA) and tetrabromobisphenol S (TBBPS) are widely distributed brominated flame retardants. While TBBPA has been demonstrated to stimulate adipogenesis, TBBPS is also under suspicion for potentially inducing comparable effects. In this study, we conducted a non-targeted metabolomics to examine the metabolic changes in 3T3-L1 cells exposed to an environmentally relevant dose of TBBPA or TBBPS. Our findings revealed that 0.1 µM of both TBBPA and TBBPS promoted the adipogenesis of 3T3-L1 preadipocytes. Multivariate analysis showed significant increases in glycerophospholipids, sphingolipids, and steroids relative levels in 3T3-L1 cells exposed to TBBPA or TBBPS at the final stage of preadipocyte differentiation. Metabolites set composed of glycerophospholipids was found to be highly effective predictors of adipogenesis in 3T3-L1 cells exposed to TBBPA or TBBPS (revealed from the receiver operating characteristic curve with an area under curve > 0.90). The results from metabolite set enrichment analysis suggested both TBBPA and TBBPS exposures significantly perturbed steroid biosynthesis in adipocytes. Moreover, TBBPS additionally disrupted the sphingolipid metabolism in the adipocytes. Our study presents new insights into the obesogenic effects of TBBPS and provides valuable information about the metabolites associated with adipogenesis induced by TBBPA or TBBPS.

Current state of knowledge of environmental occurrence, toxic effects, and advanced treatment of PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic synthetic compounds, with high chemical and thermal stability and a persistent, stable and bioaccumulative nature that renders them a potential hazard for the environment, its organisms, and humans alike. Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most well-known substances of this category and even though they are phased out from production they are still highly detectable in several environmental matrices. As a result, they have been spread globally in water sources, soil and biota exerting toxic and detrimental effects. Therefore, up and coming technologies, namely advanced oxidation processes (AOPs) and advanced reduction processes (ARPs) are being tested for their implementation in the degradation of these pollutants. Thus, the present review compiles the current knowledge on the occurrence of PFOS and PFOA in the environment, the various toxic effects they have induced in different organisms as well as the ability of AOPs and ARPs to diminish and/or eliminate them from the environment.

Studies on immunotoxicity induced by emamectin benzoate in zebrafish embryos based on metabolomics

Emamectin benzoate (EMB) is an insecticide for the control of agricultural lepidoptera pests, and also an anti-parasiticide for the control of exoparasites in aquaculture industry. Increased studies suggest that EMB could cause toxicity to non-targeted organisms, but its immunotoxicity to human remains unclear. In this study, zebrafish were used to investigate the immunotoxic effects induced by environmentally relevant doses of EMB. We observed that EMB exposure led to embryo mortality and delayed hatching, as well as increased malformations. Meanwhile, zebrafish exposed to EMB exhibited a significant decrease in the number of neutrophils and macrophages. In addition, untargeted metabolomics approach was developed to elucidate the mechanism of EMB-induced immunotoxicity. We found that a total of 10 shared biomarkers were identified in response to EMB exposure. Furthermore, pathway analysis identified glycerophospholipid metabolism was the most relevant pathway. Within this pathway, it was observed abnormal increases in glycerol 3-phosphate content, which could be attributed to the increased expression of GK5 and decreased expression of GPAT3. Our study provided novel and robust perspectives, which showed that EMB exposure to zebrafish embryos could cause metabolic disturbances that adversely affected development and immune system.

Inflammation and cardiometabolic diseases induced by persistent organic pollutants and nutritional interventions: Effects of multi-organ interactions

The development and outcome of inflammatory diseases are associated with genetic and lifestyle factors, which include chemical and nonchemical stressors. Persistent organic pollutants (POPs) are major groups of chemical stressors. For example, dioxin-like polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), and polybrominated diphenyl ethers (PBDEs) are closely associated with the incidence of inflammatory diseases. The pathology of environmental chemical-mediated inflammatory diseases is complex and may involve disturbances in multiple organs, including the gut, liver, brain, vascular tissues, and immune systems. Recent studies suggested that diet-derived nutrients (e.g., phytochemicals, vitamins, unsaturated fatty acids, dietary fibers) could modulate environmental insults and affect disease development, progression, and outcome. In this article, mechanisms of environmental pollutant-induced inflammation and cardiometabolic diseases are reviewed, focusing on multi-organ interplays and highlighting recent advances in nutritional strategies to improve the outcome of cardiometabolic diseases associated with environmental exposures. In addition, advanced system biology approaches are discussed, which present unique opportunities to unveil the complex interactions among multiple organs and to fuel the development of precision intervention strategies in exposed individuals.

Legacy and emerging per- and polyfluoroalkyl substances suppress the neutrophil respiratory burst

Per- and polyfluoroalkyl substances (PFASs) are used in a multitude of processes and products, including nonstick coatings, food wrappers, and fire-fighting foams. These chemicals are environmentally-persistent, ubiquitous, and can be detected in the serum of 98% of Americans. Despite evidence that PFASs alter adaptive immunity, few studies have investigated their effects on innate immunity. The report here presents results of studies that investigated the impact of nine environmentally-relevant PFASs [e.g. perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid potassium salt (PFOS-K), perfluorononanoic acid (PFNA), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 7H-perfluoro-4-methyl-3,6-dioxa-octane sulfonic acid (Nafion byproduct 2), and perfluoromethoxyacetic acid sodium salt (PFMOAA-Na)] on one component of the innate immune response, the neutrophil respiratory burst. The respiratory burst is a key innate immune process by which microbicidal reactive oxygen species (ROS) are rapidly induced by neutrophils in response to pathogens; defects in the respiratory burst can increase susceptibility to infection. The study here utilized larval zebrafish, a human neutrophil-like cell line, and primary human neutrophils to ascertain whether PFAS exposure inhibits ROS production in the respiratory burst. It was observed that exposure to PFHxA and GenX suppresses the respiratory burst in zebrafish larvae and a human neutrophil-like cell line. GenX also suppressed the respiratory burst in primary human neutrophils. This report is the first to demonstrate that these PFASs suppress neutrophil function and support the utility of employing zebrafish larvae and a human cell line as screening tools to identify chemicals that may suppress human immune function.

Association of Perfluoroalkyl and polyfluoroalkyl substances (PFASs) exposures and the risk of systemic lupus erythematosus: a case-control study in China

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) may have a role in impaired health. However, the data on the association between PFASs and Systemic lupus erythematosus (SLE) have been limited. We designed a population-based case-control study in China and evaluated the association. 100 normal persons (Control) and 100 SLE patients (Case) were obtained from 113 controls and 125 cases according to matching conditions. Serum samples were collected by venipuncture for UHPLC-MRM-MS Analysis to obtain the concentration of five PFASs in participants. Demographic characterization description was performed for the two groups of participants, the PFASs concentration distribution of the two groups was described and compared, then divided into three tiers (< 50th, 50th ~ 75th, > 75th) for subsequent analysis. Conditional logistic regression models were utilized to calculate the odds ratios (ORs) and 95% CIs for SLE. Relationship between changes in the concentration of PFASs and the risk of SLE assessed by restricted cubic spline. As the highest serum levels of the five PFASs tested in this study population, the highest perfluoroundecanoic acid (PFUnA) quartile had a 2.78-fold (95%CI: 1.270, 6.10) compared with the lowest quartile of PFUnA exposure, other types of PFASs also showed high association with SLE as well as PFASs mixture. Additionally, the exposure of PFASs exist a dose-response relationship (ptrend < 0.05). This risk association remained be found after adjusting the covariates in model 1 (adjustment of BMI) and in model 2(adjustment of BMI, smoking, drinking, hypertension and leukocyte). The restricted cubic spline illustrated a gradual increase in the possible risk of SLE with the increasing exposure of PFASs components levels. Our study firstly revealed that PFASs are risk factors for SLE and PFASs exposures are associated with SLE risk in a dose - response manner. Evidence from larger and more adequately powered cohort studies is needed to confirm our results.

U(VI) exposure induces apoptosis and pyroptosis in RAW264.7 cells

U(VI) pollution has already led to serious harm to the environment and human health with the increase of human activities. The viability of RAW264.7 cells was assessed under various U(VI) concentration stress for 24 and 48 h. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and superoxide dismutase (SOD) activities of RAW264.7 cells under U(VI) stress were measured. The results showed that U(VI) decreased cell activity, induced intracellular ROS production, abnormal MMP, and increased SOD activity. The flow cytometry with Annexin-V/PI double labeling demonstrated that the rate of late apoptosis increased with the increase of U(VI) concentration, resulting in decreased Bcl-2 expression and increased Bax expression. The morphology of RAW264.7 cells dramatically changed after 48 h U(VI) exposure, including the evident bubble phenomenon. Besides, U(VI) also increased the proportion of LDH releases and increased GSDMD, and Ras, p38, JNK, and ERK1/2 protein expression, which indicated that the MAPK pathway was also involved. Therefore, U(VI) ultimately led to apoptosis and pyroptosis in RAW264.7 cells. This study offered convincing proof of U(VI) immunotoxicity and established the theoretical framework for further fundamental studies on U(VI) toxicity.

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.

Perfluorooctanoic acid (PFOA) and hexafluoropropylene oxide-dimer acid (GenX): Hepatic stress and bile acid metabolism with different pathways

Per- and polyfluoroalkyl substances (PFASs) and perfluoroalkyl ether carboxylic acids (PFECAs) are organic chemicals that are widely used in the manufacture of a wide range of human-made products. Many monitoring findings revealed the presence of PFASs and PFECAs in numerous environmental sources, including water, soil, and air, which drew more attention to both chemicals. Because of their unknown toxicity, the discovery of PFASs and PFECAs in a variety of environmental sources was viewed as a cause for concern. In the present study, male mice were given orally one of the typical PFASs, perfluorooctanoic acid (PFOA), and one of the representative PFECAs, hexafluoropropylene oxide-dimer acid (HFPO-DA). The liver index showing hepatomegaly rose significantly after 90 d of exposure to PFOA and HFPO-DA, respectively. While sharing similar suppressor genes, both chemicals demonstrated unique hepatotoxic mechanisms. In different ways, these two substances altered the expression of hepatic stress-sensing genes as well as the regulation of nuclear receptors. Not only are bile acid metabolism-related genes in the liver altered, but cholesterol metabolism-related genes as well. These results indicate that PFOA and HFPO-DA both cause hepatotoxicity and bile acid metabolism impairment with distinct mechanisms.

Chlorinated Polycyclic Aromatic Hydrocarbons Induce Immunosuppression in THP-1 Macrophages Characterized by Disrupted Amino Acid Metabolism

Frequent chlorinated polycyclic aromatic hydrocarbon (Cl-PAH) occurrence in environmental samples and emerging detection in human serum have warned of their underestimated risks. Studies showed that some Cl-PAHs exhibit dioxin-like properties, implying immunotoxic potential but lacking direct evidence and specific mechanisms. Here, we integrated a high-content screening (HCS) system and high-resolution mass spectrometry to investigate the immune dysfunction and metabolic disruption induced by Cl-PAHs and their parent PAHs (PPAHs) in THP-1 macrophages. Both 9-chloroanthracene and 2,7-dichlorofluorene exerted clear immunosuppression on THP-1 mφs, while their PPAHs exhibited different immune disturbances. Interestingly, Cl-PAH/PPAHs induced complex alterations in the multicytokine/chemokine network, including biphasic alterations with initial inhibition and later enhancement. Furthermore, the protein-protein interaction results revealed that inflammatory cytokines are the core of this complicated network regulation. Connecting immune phenotypes and metabolomics, amino acid metabolism reprogramming was identified as a potential cause of Cl-PAH/PAH-induced immunotoxicity. Phytosphingosine and l-kynurenine were proposed as candidate immunosuppression biomarkers upon Cl-PAH exposure. This article provides direct immunotoxicity evidence of Cl-PAHs without activating AhR for the first time and discusses the contribution of metabolites to Cl-PAH/PPAH-induced immune responses in macrophages, highlighting the potential of developing new methods based on immunometabolism mechanisms for toxic risk evaluation of environmental chemicals.

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.

Evaluated serum perfluoroalkyl acids and their relationships with the incidence of rheumatoid arthritis in the general population in Hangzhou, China

Perfluoroalkyl acids (PFAAs) are widely present in human blood, and have many toxic effects on humans. However, effects of PFAA exposure on the risk of rheumatic immune diseases are limited. In the present study, occurrence of 7 PFAAs, including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnA), perfluorododecanoate (PFDoA), and perfluorotrdecanoate (PFTrA), were measured in serum samples from 156 healthy people (controls) and 156 rheumatoid arthritis (RA) cases living in Hangzhou, China. We also investigated the relationships among cumulative PFAA levels in serum, some immune markers, and the incidence of RA. The results showed that PFOA (6.1 and 11.8 ng/mL) had the highest mean serum concentrations, followed by PFOS (3.2 and 3.4 ng/mL) and PFDA (0.86 and 2.6 ng/mL), in both controls and RA cases. Cumulative exposure to PFOA in the study population were positively correlated with the levels of rheumatoid factors (r_s = 0.69, p < 0.01) and anti-cyclic citrullinated peptide antibody (r_s = 0.56, p < 0.05). Moreover, significant associations of PFOA concentrations with odds ratios (OR) of RA (OR = 1.998, confidence interval (CI): 1.623, 2.361, p = 0.01) were found by adjusting for various covariates. The crude and adjusted OR for RA was respective 1.385 (95% CI: 1.270, 1.510, p = 0.04) and 1.381 (95% CI: 0.972, 1.658, p = 0.06) for a unit increase in serum PFOS levels, but the adjusted results were not significant. Overall, this case-control study found that human serum PFOA concentrations were positively correlated with RF and ACPA levels.

Potential obesogenic effects of TBBPA and its alternatives TBBPS and TCBPA revealed by metabolic perturbations in human hepatoma cells

To date, increasing numbers of studies have shown the obesogenic effects of tetrabromobisphenol A (TBBPA). Tetrabromobisphenol S (TBBPS) and tetrachlorobisphenol A (TCBPA) are two common alternatives to TBBPA, and their environmental distributions are frequently reported. However, their toxicity and the associated potential health risks are poorly documented. Herein, we performed untargeted metabolomics to study the metabolic perturbations in HepG2 cells exposed to TBBPA and its alternatives. Consequently, no loss of cellular viability was observed in HepG2 cells exposed to 0.1 μmol/L and 1 μmol/L TBBPA, TBBPS and TCBPA. However, multivariate analysis and metabolic profiles revealed significant perturbations in glycerophospholipid and fatty acyl levels in HepG2 cells exposure to TBBPS and TCBPA. The evident increases in the glucose 1-phosphate and fructose 6-phosphate levels in HepG2 cells were proposed to be induced by the promotion of PGM1/PGM2 and GPI gene expression and the suppression of UPG2 and GFPT1/GFPT2 gene expression. Our results suggest that TBBPS and TCBPA are more likely to disrupt liver metabolic homeostasis and potentially drive liver dysfunction than TBBPA. Our study is significant for the re-evaluation of the health risks associated with TBBPA and its alternatives TBBPS and TCBPA.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

Per-/polyfluoroalkyl substance concentrations in human serum and their associations with immune markers of rheumatoid arthritis

Per-/polyfluoroalkyl substances (PFASs) are ubiquitous in the environment and have been proved to be immunotoxic to humans. However, it remains unclear whether exposure to PFASs affects the risk of rheumatoid arthritis (RA). In this study, nine PFASs were determined in human serum collected from 280 health populations and 294 RA patients in a cohort enrolled between 2018 and 2020 in Hangzhou, China, and were examined their correlations with immune marker levels. Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) were the predominant PFASs in human serum, with median (mean) concentrations of 5.4 (7.6), 2.8 (3.5), and 1.9 (2.5) ng/mL, respectively. Serum PFOA and 6:2 Cl-PFESA concentrations were positively correlated with anti-cyclic citrullinated peptide antibody (ACPA) (β_PFOA = 0.59, 95% confidence interval (CI): 0.37, 0.81; β_{6:2 Cl-PFESA} = 0.48, 95% CI: 0.29, 0.66), immunoglobulin G (β_PFOA = 0.25, 95% CI: 0.21, 0.29; β_{6:2 Cl-PFESA} = 0.16, 95% CI: 0.12, 0.19) as well as rheumatoid factors (RF) (β_PFOA = 0.57, 95% CI: 0.34, 0.80; β_{6:2 Cl-PFESA} = 0.54, 95% CI: 0.36, 0.72). The correlations between serum PFOS levels and RF (β = 0.52, 95% CI: 0.28, 0.77), ACPA (β = 0.48, 95% CI: 0.23, 0.73), as well as immunoglobulin M (β = -0.24, 95% CI: 0.64, 0.15) respectively were statistically stronger. We also found PFOA concentrations in serum were associated with the level of C-reactive protein (β = 0.52, 95% CI: 0.40, 0.65). To our knowledge, this is the first study reporting significant associations between several PFASs and change of specific immune marker levels, suggesting that PFAS exposure may increase the risk of RA in adults.

The toxicity of perfluorodecanoic acid is mainly manifested as a deflected immune function

BACKGROUND

Perfluorodecanoic acid (PFDA) is a type of perfluoroalkyl acid (PFAA). PFDA has toxicity similar to dioxin; its effect on the body is not through a single target or a single pathway. However, the mechanism at the global level is still unclear.

METHODS AND RESULTS

We treated mice with PFDA and characterized the global changes in gene expression in the liver using microarray analyses. The enriched KEGG pathways and GO analyses revealed that PFDA greatly affected the immune response, which was different from the response of gastric cells previously studied. As a proof of principle, the expressions of IL-1β and IL-18 were both decreased after PFDA treatment, and qRT-PCR and ELISAs verified the reduction of IL-1β and IL-18 in liver tissues. Mechanistic investigations indicated that PFDA inhibited caspase-1 activation, and decreased the mRNA levels of NLRP1, NLRP3, and NLRC4; thus, suggesting that inflammasome assemblies were suppressed. Further microarray data revealed that cIAP2 and its binding proteins, which are critical for regulating inflammasome assembly, were also repressed by PFDA. In addition, flow cytometry results revealed a significant inhibition of Th1 cell differentiation in the livers of PFDA-treated mice.

CONCLUSIONS

The results of this study suggested that one of the main toxic effects of PFDA on livers was the inhibition of immune response.