Mixed Metal Components in PM2.5 Contribute to Chemokine Receptor CCR5-Mediated Neuroinflammation and Neuropathological Changes in the Mouse Olfactory Bulb.

Particulate matter, especially PM2.5, can invade the central nervous system (CNS) via the olfactory pathway to induce neurotoxicity. The olfactory bulb (OB) is the key component integrating immunoprotection and olfaction processing and is necessarily involved in the relevant CNS health outcomes. Here we show that a microglial chemokine receptor, CCR5, is the target of environmentally relevant PM2.5 in the OB to trigger neuroinflammation and then neuropathological injuries. Mechanistically, PM2.5-induced CCR5 upregulation results in the pro-inflammatory paradigm of microglial activation, which subsequently activates TLR4-NF-κB neuroinflammation signaling and induces neuropathological changes that are closely related to neurodegenerative disorders (e.g., Aß deposition and disruption of the blood-brain barrier). We specifically highlight that manganese and lead in PM2.5 are the main contributors to CCR5-mediated microglial activation and neuroinflammation in synergy with aluminum. Our results uncover a possible pathway of PM2.5-induced neuroinflammation and identify the principal neurotoxic components, which can provide new insight into efficiently diminishing the adverse health effects of PM2.5.

Neurotoxicity of tetramethylammonium ion on larval and juvenile zebrafish: Effects on neurobehaviors and multiple biomarkers.

Tetramethylammonium hydroxide (TMAH) is an important compound that utilized and released by the rapidly expanding semiconductor industry, which could hardly be removed by the conventional wastewater treatment techniques. As a cholinergic agonist, the tetramethylammonium ion (TMA+) has been reported to induce toxicity to muscular and respiratory systems of mammals and human, however the toxicity on aquatic biota remains poorly known. We investigated the neurotoxic effects of TMA+ exposure on zebrafish, based on neurobehavior tests and a series of biomarkers. Significant inhibitions on the swimming distance of zebrafish larvae were observed when the exposure level exceeded 50 mg/L, and significant alterations on swimming path angles (straight and deflective movements) occurred even at 10 mg/L. The tested neurobehavioral endpoints of zebrafish larvae were significantly positively correlated with reactive oxygen species (ROS) and malondialdehyde (MDA), significantly negatively related with the activities of antioxidant enzymes, but not significantly correlated with the level of acetylcholinesterase (AChE). Such relationship indicates that the observed neurotoxic effects on swimming behavior of zebrafish larvae is mainly driven by oxidative stress, rather than the alterations of neurotransmitter. At the highest exposure concentration (200 mg/L), TMA+ evoked more severe toxicity on zebrafish juveniles, showing significantly stronger elevation on the MDA activity, and greater inhibitions on the activities of antioxidant enzymes and AChE, suggesting juveniles were more susceptible to TMA+ exposure than larval zebrafish.

Effects of carbamazepine on gut microbiota, ARGs and intestinal health in zebrafish.

Carbamazepine (CBZ) in the aquatic environment is recognized as a potential threat to aquatic organisms and public health. However, the response of organism intestinal health, resistome, microbiota, and their relationship after CBZ exposure has been rarely reported. This study aimed to explore the impacts of CBZ on gut microbiota, antibiotic resistance genes (ARGs) and the expression of intestinal health related genes as well as their interaction using the zebrafish model. 16 S ribosomal RNA sequencing indicated CBZ altered the composition of gut microbiota. Using high-throughput quantitative polymerase chain reaction (HT-qPCR), we found the number and abundance of ARGs were impacted by CBZ levels and exposure duration. We also observed the upregulated expression of the pro-inflammatory gene IL6 and downregulated expression of toll-like receptor gene TLR2 and intestinal barrier gene TJP2a at different exposure times. Correlation analyses revealed that Geobacillus, Rhodococcus, Ralstonia, Delftia, Luteolibacter and Escherichia-Shigella might be the main bacterial genera carrying ARGs. Meanwhile, Cetobacterium and Aeromonas could be the dominant bacteria affecting intestinal health related genes. Our results could contribute to understanding the health risks of CBZ to the intestinal microecology of aquatic animals.

Influence of dietary status on the obesogenic effects of erythromycin antibiotic on Caenorhabditis elegans.

As emerging pollutants, antibiotics were widely detected in water bodies and dietary sources. Recently, their obesogenic effects raised serious concerns. So far, it remained unclear whether their obesogenic effects would be influenced by water- and diet-borne exposure routes. In present study, Caenorhabditis elegans, nematodes free-living in air-water interface and feeding on bacteria, were exposed to water- and diet-borne erythromycin antibiotic (ERY). The statuses of the bacterial food, inactivated or alive, were also considered to explore their influences on the effects. Results showed that both water- and diet-borne ERY significantly stimulated body width and triglyceride contents. Moreover, diet-borne ERY's stimulation on the triglyceride levels was greater with alive bacteria than with inactivated bacteria. Biochemical analysis showed that water-borne ERY inhibited the activities of enzymes like adipose triglyceride lipase (ATGL) in fatty acid ß-oxidation. Meanwhile, diet-borne ERY inhibited the activities of acyl-CoA synthetase (ACS) and carnitine palmitoyl transferase (CPT) in lipolysis, while it stimulated the activities of fatty acid synthase (FAS) in lipogenesis. Gene expression analysis demonstrated that water-borne ERY with alive bacteria significantly upregulated the expressions of daf-2, daf-16 and nhr-49, without significant influences in other settings. Further investigation demonstrated that ERY interfered with bacterial colonization in the intestine and the permeability of the intestinal barrier. Moreover, ERY decreased total long-chained fatty acids (LCFAs) in bacteria and nematodes, while it decreased total short-chained fatty acids (SCFAs) in bacteria but increased them in nematodes. Collectively, the present study demonstrated the differences between water- and diet-borne ERY's obesogenic effects, and highlighted the involvement of insulin and nhr-49 signaling pathways, SCFAs metabolism and also the interaction between intestinal bacteria and the host.

Obesogenic potentials of environmental artificial sweeteners with disturbances on both lipid metabolism and neural responses.

Artificial sweeteners (ASs) entered the environments after application and emissions. Recent studies showed that some ASs had obesogenic risks. However, it remained unclear whether such risks are common and how they provoke such effects. Presently, the effects of 8 widely used ASs on lipid accumulation were measured in Caenorhabditis elegans. Potential mechanisms were explored with feeding and locomotion behavior, lipid metabolism and neural regulation. Results showed that acesulfame (ACE), aspartame (ASP), saccharin sodium (SOD), sucralose (SUC) and cyclamate (CYC) stimulated lipid accumulation at µg/L levels, showing obesogenic potentials. Behavior investigation showed that ACE, ASP, SOD, SUC and CYC biased more feeding in the energy intake aspect against the locomotion in the energy consumption one. Neotame (NEO), saccharin (SAC) and alitame (ALT) reduced the lipid accumulation without significant obesogenic potentials in the present study. However, all 8 ASs commonly disturbed enzymes (e.g., acetyl-CoA carboxylase) in lipogenesis and those (e.g., carnitine palmitoyl transferase) in lipolysis. In addition, ASs disturbed PPARγ (via expressions of nhr-49), TGF-ß/DAF-7 (daf-7) and SREBP (sbp-1) pathways. Moreover, they also interfered neurotransmitters including serotonin (5-HT), dopamine (DA) and acetylcholine (ACh), with influences in Gsα (e.g., via expressions of gsα-1, ser-7), glutamate (e.g., mgl-1), and cGMP-dependent signaling pathways (e.g., egl-4). In summary, environmental ASs commonly disturbed neural regulation connecting behavior and lipid metabolism, and 5 out of 8 showed clear obesogenic potentials. ENVIRONMENTAL IMPLICATION: Artificial sweeteners (ASs) are become emerging pollutants after wide application and continuous emission. Recent studies showed that some environmental ASs had obesogenic risks. The present study employed Caenorhabditis elegans to explore the influences of 8 commonly used ASs on lipid metabolisms and also the underlying mechanisms. Five out of 8 ASs stimulated lipid accumulation at µg/L levels, and they biased energy intake against energy consumption. The other three ASs reduced the lipid accumulation. ASs commonly disturbed lipogenesis and lipolysis via PPARγ, TGF-ß and SREBP pathways, and also influenced neurotransmitters with Gsα, glutamate and cGMP-dependent signaling pathways.

Distribution and spatial variation of volatile methylsiloxanes in surface water and wastewater from the Yangtze River Basin, China.

Volatile methylsiloxanes (VMSs) earned serious concerns due to their detection and toxicities after their release to the environments. They were also detected in rivers around the globe, but their distribution remained to be explored in larger rivers with longer length, higher water volume and wider watershed. In the present study, 8 cyclic VMSs (cVMSs) and 7 linear ones (lVMSs) were investigated in 42 water samples (27 surface water (including 7 drinking source water) and 15 wastewater) from the Yangtze River Basin, China. Results showed that VMSs were detected in all sampling sites. In surface water, the concentrations of total cVMSs ranged from 17.3 to 4.57 × 103 ng/L, while those of lVMSs ranged from 1.72 to 81.6 ng/L. In wastewater, the total concentrations of cVMSs and lVMSs showed ranges of 17.6-1.66 × 103 ng/L and 2.59-252 ng/L, respectively. Apparently, cVMSs showed significantly higher concentrations than lVMSs. The concentrations of cVMSs followed an order of lower > upper > middle reaches, while those of lVMSs did not show clear distribution patterns. Among cVMSs, those with less Si numbers were dominant, while those with more Si numbers were dominant in lVMSs. Notably, the VMSs were also detected in 7 surface waters that served as drinking source waters, which earned them further concerns. In addition, the VMSs in surface water showed positive correlation with those in wastewater, which led to necessity in management on industrial emissions in the future.

Combined effects of pH and dissolved organic matter on the availability of pharmaceuticals and personal care products in aqueous environment.

The interaction between pharmaceuticals and personal care products (PPCPs) with dissolved organic matter (DOM) can alter their bioavailability and toxicity. Nevertheless, little is known about how pH and DOM work together to affect the availability of PPCPs. This study investigated the impact of pH and DOM on the availability of seven PPCPs, namely Carbamazepine, Estrone, Bisphenol A, Testosterone Propionate, Triclocarban, 4-tert-Octylphenol and 4-n-Nonylphenol, using negligible depletion solid-phase microextraction (nd-SPME). The uptake kinetics of PPCPs by the nd-SPME fibers increased proportionally with DOM concentrations, likely due to enhanced diffusive conductivity in the unstirred water layer. At neutral pH, the partitioning coefficients of PPCPs for Humic Acid (log KDOC 3.87-5.25) were marginally higher than those for Fulvic Acid (log KDOC 3.64-5.11). Also, the log KDOC values correlated linearly with the log DOW (pH 7.0) values of PPCPs, indicating a predominant role for hydrophobic interactions in the binding of DOM and PPCPs. Additionally, specific interactions like hydrogen bonding, π-π, and electrostatic interactions occur for certain compounds, influenced by the polarity and spatial conformation of the compounds. For these ionizable PPCPs, the log DDOC values exhibit a strong dependence on pH due to the dual influence of pH on both DOM and PPCPs. The log DDOC values rose from pH 1.0 to 3.0, peaked at pH 5.0 to 9.0, and then (sharply) declined from 11.0 to 13.0. The reasons are that in strong acidic circumstances, the coiled and compressed shape of DOM inhibits the hydrophobic interaction, whereas in strong alkaline conditions, significant electrostatic repulsion reduces the sorption. This study reveals that the effects of DOM on the bioavailability of PPCPs are dependent on both pH and the specific compound involved.

Effect of nitrogen oxides and sulfur oxides to triphenyl phosphate degradation and cytotoxicity on surface of different transition metal salts.

Nitrogen oxides and sulfur oxides, as the dominant toxic gases in the atmosphere, can induce severe human health problems under the composite pollutant conditions. Currently the effect of nitrogen or sulfur oxides in atmospheric environment to the degradation and cytotoxicity of triphenyl phosphate (TPhP) on atmospheric particle surfaces still remain poorly understood. Hence, laboratory simulation methods were used in this study to investigate the effect and related mechanism. First, particle samples were prepared with the TPhP coated on MnSO4, CuSO4, FeSO4 and Fe2(SO4)3 surface. The results showed that, when nitrogen or sulfur oxides were present, more significant TPhP degradation on all samples can be observed under both light and dark conditions. The results proved nitrogen oxides and sulfur oxides were the vital influence factors to the degradation of TPhP, which mainly promoted the OH generation in the polluted atmosphere. The mechanism study indicated that diphenyl hydrogen phosphate (DPhP) and OH-DPhP were two main stable degradation products. These degradation products originated from the phenoxy bond cleavage and hydroxylation of TPhP caused by hydroxyl radicals. In addition, no TPhP related organosulfates (OSs) or organic nitrates (ON) formation were observed. Regarding the cytotoxicity, all the particles can induce more significant cellular injury and apoptosis of A549 cells, which may be relevant to the adsorbed nitrogen oxides or sulfur oxides on particles surfaces. The superfluous reactive oxygen species (ROS) generation was the possible reason of cytotoxicity. This research can supply a comprehensive understanding of the promoting effect of nitrogen and sulfur oxides to TPhP degradation and the composite cytotoxicity of atmospheric particles.

EGFR and Hippo signaling pathways are involved in organophosphate esters-induced proliferation and migration of triple-negative breast cancer cells.

The widespread application of organophosphate flame retardants has led to pervasive exposure to organophosphate esters (OPEs), prompting considerable concerns regarding their potential health risk to humans. Despite hints from previous research about OPEs' association with breast cancer, their specific effects and underlying mechanisms of triple-negative breast cancer (TNBC) remain unclear. In this study, we investigated the effects of four representative OPEs on cell proliferation, cell cycle regulation, migration, and the expression of genes and proteins associated with the epidermal growth factor receptor (EGFR) and Hippo signaling pathways in TNBC (MDA-MB-231) cells. Our findings revealed that treatment with 1-25 µM triphenyl phosphate (TPHP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) induced TNBC cell proliferation and accelerated cell cycle progression, with upregulation in MYC, CCND1, and BRCA1 mRNA. Moreover, exposure to 1-25 µM TPHP, 10-25 µM TDCIPP, and 1-10 µM tris (2-chloroethyl) phosphate (TCEP) induced MMP2/9 mRNA expression and enhanced migratory capacity, except for 2-ethylhexyl diphenyl phosphate (EHDPP). Mechanistically, four OPEs treatments activated the EGFR-ERK1/2 and EGFR-PI3K/AKT signaling pathways by increasing the transcript of EGFR, ERK1/2, PI3K, and AKT mRNA. OPEs treatment also suppressed the Hippo signaling pathway by inhibiting the expression of MST1 mRNA and phosphorylation of LATS1, leading to the overactivation of YAP1 protein, thereby promoting TNBC cell proliferation and migration. In summary, our study elucidated that activation of the EGFR signaling pathway and suppression of the Hippo signaling pathway contributed to the proliferation, cell cycle dysregulation, and migration of TNBC cells following exposure to OPEs.

Metastatic effects of perfluorooctanoic acid (PFOA) on Drosophila melanogaster with metabolic reprogramming and dysrhythmia in a multigenerational exposure scenario.

Perfluorooctanoic acid (PFOA) exposure correlated with various cancers and their mortality. Its persistence in the environment made its long-term multigenerational influences of significant concerns. However, it remained unanswered whether its multigenerational exposure could influence metastasis which contributes ~90 % to cancer mortality. In the present study, long-term effects of PFOA were measured in Drosophila melanogaster over 3 consecutive generations. In the morning-eclosed (AM) adult flies, PFOA significantly promoted tumor invasion rates and distances which increased over generations. Regarding metabolic reprogramming, PFOA disturbed the expressions of Glut1 and Pdk1, activities and contents of FASN1 (fatty acid synthase), ACC (acetyl-CoA carboxylase) and SREBP1 (sterol regulatory element binding protein). Regarding antioxidant responses, PFOA exposure generated provoked oxidative stress via H2O2 and stimulated antioxidants including glutathione (GSH), catalase (CAT), melatonin, serotonin and cortisol, with downregulations on PI3K/AKT pathways and upregulations on MAPK ones. The biochemical and molecular effects altered over generations. In the afternoon-eclosed (PM) adult flies, the metastasis of PFOA was more deteriorated than in AM adults. The significant influences of dysrhythmia were also observed in the multigenerational effects of PFOA on the metabolism reprogramming and antioxidant responses. The effects on rhythm-regulating gene expressions and protein levels explained the dysrhythmia and also indicated close interactions among metabolism reprogramming, antioxidant responses and rhythm regulation. ENVIRONMENTAL IMPLICATION: Numerous emerging per- and polyfluoroalkyl substances (PFASs) are being detected. Meanwhile, the toxicities of the emerging PFASs still depend on the progress of legacy PFASs for the continuity of scientific studies. As one legacy PFAS, perfluorooctanoic acid (PFOA) exposure correlated with various cancers and their mortality. Its persistence in the environment made its long-term multigenerational influences of significant concerns. However, it remained unanswered whether its multigenerational exposure could influence metastasis which contributes ~90 % to cancer mortality. The present study performed PFOA exposure for 3 consecutive generations. Results showed that the metastasis by PFOA increased over generations, and it was further deteriorated by dysrhythmia. Further analysis demonstrated the interactive involvement of metabolism reprogramming, antioxidant responses and rhythm regulation. The findings of the present study would highlight considerate points for studying the toxicities of emerging PFASs.

Degradation, transformation and cytotoxicity of triphenyl phosphate on surface of different transition metal salts in atmospheric environment.

Triphenyl phosphate (TPhP) and transition metal elements have been ubiquitously detected in the atmosphere, which can participate in atmospheric chemical reactions and induce damage to human health. Currently the understanding of TPhP degradation, transformation and cytotoxicity on atmospheric particles surface are still limited. Therefore, this study used laboratory simulation methods to investigate the influence of irradiation time, transition metal salts, relative humidity (RH) to TPhP degradation, transformation and relative cytotoxicity. TPhP was coated on particle surfaces of four transition metal salts (MnSO4, CuSO4, FeSO4 and Fe2(SO4)3) in the experiment. Within 12 h irradiation, the significant TPhP photodegradation can be observed on all particles surface. Among these influence factors, the irradiation and RH were the crucial aspects to TPhP degradation, which primarily affect the OH concentration in the atmosphere. The transition metal elements only exhibited slightly catalytic effect to TPhP degradation. The mechanism study indicated that the major degradation products of TPhP are diphenyl hydrogen phosphate (DPhP) and OH-DPhP, which originated from the phenoxy bond cleavage and hydroxylation of TPhP induced by OH. As for the cytotoxicity to A549 cells, all the transition metal particles coated with TPhP can cause cellular injury, which was chiefly induced by the transition metal salt. The possible cytotoxicity mechanism of these particles to A549 cells can be attributed to the excessive reactive oxygen species (ROS) production. This study may provide a further understanding of TPhP degradation and related cytotoxicity with the coexistent transition metal salts in the atmosphere.

Aspirin altered antibiotic resistance genes response to sulfonamide in the gut microbiome of zebrafish.

Pharmaceuticals are widespread in aquatic environments and might contribute to the prevalence of antibiotic resistance. However, the co-effect of antibiotics and non-antibiotic pharmaceuticals on the gut microbiome of fish is poorly understood. In this study, we characterized the variation of the zebrafish gut microbiome and resistome after exposure to sulfamethoxazole (SMX) and aspirin under different treatments. SMX contributed to the significant increase in the antibiotic resistance genes (ARGs) richness and abundance with 46 unique ARGs and five mobile genetic elements (MGEs) detected. Combined exposure to SMX and aspirin enriched total ARGs abundance and rearranged microbiota under short-term exposure. Exposure time was more responsible for resistome and the gut microbiome than exposure concentrations. Perturbation of the gut microbiome contributed to the functional variation related to RNA processing and modification, cell motility, signal transduction mechanisms, and defense mechanisms. A strong significant positive correlation (R = 0.8955, p < 0.001) was observed between total ARGs and MGEs regardless of different treatments revealing the key role of MGEs in ARGs transmission. Network analysis indicated most of the potential ARGs host bacteria belonged to Proteobacteria. Our study suggested that co-occurrence of non-antibiotics and antibiotics could accelerate the spread of ARGs in gut microbial communities and MGEs played a key role.

Insight into the differential toxicity of PFOA and PFBA based on a 3D-cultured MDA-MB-231 cell model.

Perfluoroalkyl substances (PFASs) are a category of high-concerned emerging contaminants which are suspected to correlate with various human adverse health outcomes including tumors. It is also a question whether short-chain PFASs are qualified alternatives under the regulation of long-chain PFASs. In this study, a three-dimensional (3D) culture system based on Gelatin methacrylate (GelMA) hydrogel matrix was used to investigate the impacts of 120-h perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) exposure of MDA-MB-231 cells. The results showed that PFOA exposure promoted the proliferation, migration, and invasion of MDA-MB-231 cells in an environmentally relevant concentration range (0.1 to 10 µM), exhibiting a clear malignant-promoting risk. In contrast, PFBA only showed a trend to induce non-invasive cell migration. Hippo/YAP signaling pathway was identified as the contributor to the differences between the two PFASs. PFOA but PFBA reduced YAP phosphorylation and increased the nuclear content of YAP, which further facilitated abundant key factors of epithelial-mesenchymal transition (EMT) process. Our results provided a new idea for the carcinogenicity of PFOA using a 3D-based paradigm. Although the effects by PFBA were much milder than PFOA in the current test duration, the cell model suitable for longer exposure is still necessary to better assess the safety of alternative short-chain PFASs.