PM2.5 induces autophagy-dependent ferroptosis by endoplasmic reticulum stress in SH-SY5Y cells.

Fine particulate matter (PM2.5 ) has been a global environmental problem threatening public health in recent years. PM2.5 exposure was associated with an increased risk of neurodegenerative diseases related to neuronal apoptosis. Ferroptosis is a nonapoptotic form of programmed the cell death, characterized by excess iron-dependent lipid peroxidation products. Whether PM2.5 could induce ferroptosis in cells and thus be involved in its neurotoxicity is unknown. In this study, we found that PM2.5 induced endoplasmic reticulum stress, apoptosis, autophagy, and ferroptosis in neuroblastoma human neuroblastoma cells (SH-SY5Y). Interestingly, ferroptosis was the predominant form of mortality in the presence of high doses of PM2.5 exposure. In addition, the endoplasmic reticulum stress inhibitor 4-phenylbutyric acid (4-PBA) inhibited PM2.5 -induced cellular autophagy, apoptosis, and ferroptosis. Autophagy inhibitors chloroquine (CQ) alleviated PM2.5 -induced ferroptosis but did not reverse apoptosis. We also found that inhibition of both endoplasmic reticulum stress and autophagy reversed the PM2.5 -induced increase in the expression level of cytophagy nuclear receptor coactivator 4 (NCOA4). Our results suggested that PM2.5 -induced ferroptosis in SH-SY5Y cells was autophagy-dependent ferroptosis due to endoplasmic reticulum stress, which might be associated with the elevation of iron content caused by NCOA4-mediated ferritin autophagy.

Nano-Calcium Carbonate Affect the Respiratory and Function Through Inducing Oxidative Stress: A Cross-sectional Study Among Occupational Exposure of Workers and a Further Research for Underlying Mechanisms.

OBJECTIVE: The aim of the study is to investigate whether nano-calcium carbonate (nano-CaCO 3 ) occupational exposure could induce adverse health effects in workers. METHODS: A cross-sectional study was conducted in a nano-CaCO 3 manufacturing plant in China. Then, we have studied the dynamic distribution of nano-CaCO 3 in nude mice and examined the oxidative damage biomarkers of subchronic administrated nano-CaCO 3 on Sprague-Dawley rats. RESULTS: The forced vital capacity (%) and the ratio of FEV1 to FVC is the rate of one second of workers were significantly decreased than unexposed individuals. Dynamic imaging in mice of fluorescence labeled nano-CaCO 3 showed relatively high uptake and slow washout in lung. Similar to population data, the decline in serum glutathione level and elevation in serum MDA were observed in nano-CaCO 3 -infected Sprague-Dawley rats. CONCLUSIONS: We found that nano-CaCO 3 exposure may result in the poor pulmonary function in workers and lead to the changes of oxidative stress indexes.

Mechanism of subchronic vinyl chloride exposure combined with a high-fat diet on hepatic steatosis.

Vinyl chloride (VC) is a common industrial organic chlorine and environmental pollutant. In recent years, the dietary structure of residents especially Chinese has gradually shifted to western dietary patterns. VC aggravates dietary fatty acid-induced hepatic steatosis, but its mechanism is still unclear. And if the risk factors for steatosis persist, more severe diseases such as fibrosis and cirrhosis will occur. Therefore, we studied the effects and mechanisms of VC (160 and 800 mg/m3 ) and its metabolite (chloroacetaldehyde, 2.25, 4.5, and 9 µM) on hepatic steatosis of high-fat diet (HFD)-fed mice and palmitic acid (PA, 100 µM) treated HepG2 cells. Liver and serum biochemical indicators and pathological staining of the liver showed that the hepatic steatosis of VC combined with HFD groups was more severe than that of single-exposure groups (HFD group, low-dose VC group, and high-dose VC group). Moreover, VC enhanced HFD-induced oxidative stress (OS) and endoplasmic reticulum stress (ERS) and further upregulated the expression of sterol regulatory element-binding protein 1 (SREBP-1) and FAS. Besides, antioxidants and ERS inhibitors reduced the steatosis of HepG2 cells induced by VC metabolites and PA. These results suggest that VC exposure can enhance the degree of hepatic steatosis in HFD-fed mice. VC combined with HFD led to OS and ERS and upregulated the expression of de novo lipogenesis-related proteins, which may be related to the occurrence of hepatic steatosis. And the increased expression of CYP2E1 induced by VC combined with HFD may be the cause of OS.

Sub-chronic administration of benzo[a]pyrene disrupts hippocampal long-term potentiation via inhibiting CaMK II/PKC/PKA-ERK-CREB signaling in rats.

Benzo[a]pyrene (B[a]P) is recognized as a neurotoxic pollutant to mammals, which could impair learning and memory function. Although there is some evidence to suggest that N-methyl-d-aspartate receptor (NMDAR), a glutamate receptor and ion channel protein in nerve cells, is involved into the B[a]P induced neurotoxicity, the exact molecular mechanisms remain to be elucidated, particularly the effects of B[a]P on the NMDAR downstream signaling transduction pathways. In the present study, we examined the neurotoxicity of sub-chronic administrated B[a]P on male Sprague-Dawley rats. Our data suggested that B[a]P exposure caused significant deficits in learning and memory function and the impairment of hippocampal LTP in rats. Further mechanistic studies indicate that B[a]P-induced learning and memory deficits are associated with the inhibition of NMDAR NR1 subunit transcription and protein phosphorylation. More importantly, the inactivation of CaMK II/PKC/PKA-ERK-CREB signaling pathways in hippocampus was detected at both the 2.5 and 6.25 mg/kg B[a]P-treated groups, indicating that multiple targets in NMDAR and downstream signaling pathways are involved in the B[a]P-induced neurotoxicity.

Heat-shock protein 70 (HSP70) polymorphisms affect the risk of coke-oven emission-induced neurobehavioral damage.

OBJECTIVES: Epidemiology studies indicated that coke-oven workers with long-term exposure to polycyclic aromatic hydrocarbons (PAHs) often have some neurobehavioral abnormalities especially impairment for cognitive function, while the underlying mechanisms are not fully understood. Numerous studies have indicated the antioxidant and anti-apoptosis roles of heat shock protein 70 (Hsp70). The genetic polymorphisms in HSP70 genes are associated with multiple diseases including neurotoxicity. However, it is unclear whether HSP70 polymorphisms are related to the neurotoxicity of PAH. We, therefore, investigate the possible association between HSP70 polymorphisms and neurobehavioral abnormalities. METHODS: 188 coke-oven workers and 137 control workers were recruited in this study. Emotional and cognitive function was assessed using the WHO/NCTB. HSP70 polymorphisms (HSP70-1 G190C, HSP70-2 G1267 A and HSP70-hom T2437C) were checked by PCR-RFLP. RESULTS: The results indicated that HSP70-1 CC genotypes in coke-oven workers were associated with poor neurobehavioral performance such as the attention /response speed and visual perception/memory, while the HSP70-2 AA genotypes were associated with lower short-term auditory memory. CONCLUSIONS: HSP70-1 CC and HSP70-2 AA genotypes in coke-oven workers may increase the risk for neurobehavioral damage, especially attention, learning and memory.

Role of endoplasmic reticulum stress and oxidative stress in vinyl chloride-induced hepatic steatosis in mice.

Vinyl chloride (VC) is a common industrial organochlorine, shown to cause hepatic angiosarcoma and hepatic steatosis. However, the role of endoplasmic reticulum stress (ERS) and oxidative stress (OS) in hepatic steatosis after subchronic exposure to VC in mice, is unclear. Based on body weight, forty healthy SPF male C57BL/6 J mice were randomly divided into a control group and three VC exposure groups (57.3, 286.7, and 1433.6 ppm) (n = 10 each). VC was administered by static inhalation in a 50 L sealed plexiglass inhalation chamber for 2 h per day, five days per week for 16 weeks. Serum and liver tissues were analyzed for liver enzymes and lipids. Hepatic cytochrome P450 2E1 (CYP2E1) and OS related indicators malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were measured. The mRNA expressions of ERS downstream genes, including glycoregulatory protein-78 (GRP-78), sterol regulatory element binding protein-1 (SREBP-1), Acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) were detected by real-time PCR (RT-PCR) and their protein levels examined by western blotting. The CYP2E1 levels increased after VC administration in a dose-dependent manner. MDA levels increased (P < .05) and SOD and GSH levels decreased (P < .05) in the liver of each group with the increase in the dose of VC. ERS and expressions of downstream genes (GRP-78, SREBP-1, ACC, and FAS) were enhanced after VC administration. These results suggested that OS and ERS could be induced by VC, which may lead to an increase in fatty acid synthesis in the liver, further aggravating hepatic steatosis.

Interaction of heat shock protein 70 (HSP70) polymorphisms and occupational hazards increases the risk of hypertension in coke oven workers.

OBJECTIVES: The interaction between genetic, epigenetic inheritance and environmental factors determines susceptibility to hypertension. Previous epidemiology studies have shown that coke oven workers who are frequently exposed to various occupational hazards have remarkable increase in the risk for hypertension. Among many genetic variants identified in hypertension, heat shock protein 70 (HSP70) was found to play important roles in the pathogenesis of hypertension and associated diseases. We therefore explore the possible role of HSP70 polymorphisms and their interaction with occupational environment in hypertension risk. METHODS: We carried out a case-control study among 367 coke oven workers in northwest China, focused on three common HSP70 polymorphisms (HSP70-1 G190C, HSP70-2 A1267G and HSP70-hom T2437C), and evaluated the association of HSP70 gene polymorphisms with work sites for high risk of hypertension. RESULTS: The results indicated that HSP70-1 GC and CC genotype had 2.73-fold and 4.26-fold increased relative risk (95% CI 1.33 to 5.55 and 1.17 to 15.53), respectively, comparing with HSP70-1 GG genotype. HSP70-2 AG and GG conferred a 47% and 36% reduced risk (95% CI 0.23 to 0.99 and 0.14 to 0.92) comparing with HSP70-2 AA genotype. Further analysis of the interaction of HSP70 polymorphisms with occupational environment indicated a strong positive interaction between HSP70 genotype (HSP70-1 GC+CC, HSP70-2 AA and HSP70-hom TC+CC) and oven top workplace. CONCLUSIONS: Collectively, these data indicate that HSP70 polymorphisms interact with occupational hazards might increase the risk of hypertension in coke oven workers.

[The modification of apoptosis correlated gene, protein and protein activity in rat hippocampus induced by benzo[a] pyrene sub-chronic exposure].

OBJECTIVE: To observe the effects of subchronic exposure to benzo[a]pyrene (B[a]P) on the mRNA and protein expression levels of apoptosis-related genes (bax, bcl-2, caspase-3, caspase-6, and caspase-9) and the activities of Caspase-3, Caspase-6, and Caspase-9 in the hippocampal neurons of rats and to investigate the neurotoxic mechanism by which B[a]P induces the apoptosis of neurons. METHODS: Fifty-two healthy SD rat were randomly divided into five groups according to preliminary neurobehavioral test results: blank control group, solvent control group, and 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups; the rats in exposure groups were intraperitoneally injected with B[a]P every other day for 90 days. The Morris water maze was used to test the learning and memory ability of rats; flow cytometry was used to measure the apoptosis ratio of hippocampal neurons; real-time quantitative PCR and Western blot were used to measure the mRNA and protein expression levels of apoptosis-related genes; spectrophotometry was used to measure the activities of their en-coded proteins. RESULTS: Compared with the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group, the 2.5 and 6.25 mg/kg B[a]P exposure groups hada significantly longer mean escape latency period (P < 0.05) and a significantly increased number of times of platform crossing (P < 0.05), and the 6.25 mg/kg B[a]P exposure group had significantly lower length and percentage of time spent in the platform quadrant (P < 0.05). The early apoptosis ratio rose as the dose of B[a]P increased (P trend < 0.05); the early apoptosis ratios of 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups were significantly higher than those of blank control group and solvent control group (P < 0.05). Compared with the blank control group, solvent control group, and 1.0 and 2.5 mg/kg B[a]P exposure groups, the 6.25 mg/kg B[a]P exposure group had significantly increased Bax expression (P < 0.05) and significantly decreased Bcl-2 expression and Bcl-2/Bax ratio (P < 0.05). The 2.5 and 6.25 mg/kg B[a]P exposure groups had significantly higher expression levels of Caspase-3 and Caspase-6 than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The activities of Caspase-3, Caspase-6, and Caspase-9 were significantly higher in the 2.5 and 6.25 mg/kg B[a]P exposure groups than in the blank control group and solvent control group (P < 0.05). There was a positive correlation between the activities of Caspase-3, Caspase-6, and Caspase-9 and early apoptosis ratio of hippocampal neurons in rats (r = 0.793, P = 0.019; r = 0.886, P = 0.006; r = 0.773, P = 0.025). There were no significant differences in the mRNA expression of Bax, Bcl-2, Caspase-3, Caspase-6, and Caspase-9 among these groups (P > 0.05). CONCLUSION: Subchronic exposure to B[a]P can induce apoptosis of hippocampal neurons; its mechanism may be related to the fact that B[a]P can induce upregulated expression of Bax, inhibit expression of Bcl-2, lead to decrease in Bcl-2/Bax ratio, induce upregulated expression of Caspase-3 and Caspase-6, and cause increase in the activities of Caspase-3, Caspase-6, and Caspase-9.

[Influences of excision repair cross complementation group 4 genetic variations on DNA damage in lymphocytes among coke oven workers].

OBJECTIVE: To investigate the relationship between excision repair cross complementation group 4 ERCC4 gene polymorphisms and DNA damage in lymphocytes of coke oven workers and controls. METHODS: Two hundred and forty-six coke oven workers and one hundred and twenty-seven controls were recruited in the study, and peripheral vein blood was drawn after over night fasting. Comet assay was used to evaluate DNA damage, and TaqMan-MGB probes were used to analyze ERCC4 genetic variations including the three Tagged-single nucleotide polymorphisms (Tag SNPs), referred to rs744154, rs3136079 and rs31870 which were picked out from Hapmap database. Then haplotypes were reconstructed by PHASE2.0.2 software. RESULTS: The lymphocytes Olive TM value of coke oven workers was significantly higher than that of controls (1.26+/-1.12 vs 0.52+/-0.97, P<0.01). Among coke oven workers, no significant difference was found between the Olive TM of those with different genotypes or haplotype pairs at ERCC4 gene (P>0.05). However, in the control group, the TG genotype carriers had higher Olive TM than the TT and GG genotype carriers (0.26+/-0.96 vs 0.66+/-0.98 and 0.66+/-0.51, P<0.05), and the CTG/CTG haplotype pairs carriers had the highest Olive TM (0.69+/-1.01), and no CTG haplotype carriers had the lowest Olive TM (0.25+/-0.80), and the difference was borderline (P=0.08). CONCLUSION: The gene polymorphism at ERCC4 gene has no effects on the DNA damage of lymphocytes in coke oven workers, but the TG genotype carriers has lower DNA damage in the control. DNA damage is influenced by the interaction of genetic and environmental factors.

[Relationship between heat shock protein 72 and DNA genetic damage in peripheral blood lymphocytes of coke oven workers].

OBJECTIVE: To investigate the relationship between heat shock protein 72 (Hsp72) and DNA genetic damage in peripheral blood lymphocytes of coke oven workers and the role of Hsp72 in protection of cells from genetic damage induced by coke oven emissions. METHODS: Two hundred and sixty-seven coke oven workers and thirty controls without occupational PAHs exposure were investigated. Benzo[a]pyrene concentrations in the ambient air individually collected were assayed by high performance liquid chromatography (HPLC). Western Blot was used to measure Hsp72 levels and Comet assay was used to evaluate DNA damage degree. Personal information was collected by questionnaire. RESULTS: The Hsp72 level (G+/-S(G)) and olive comet tail moment (G+/-S(G) of peripheral blood lymphocytes in high-exposure workers (1.24 +/- 0.42 and 4.49 +/- 1.24) were significantly higher than those in low-exposure workers (1.01 +/- 0.35 and 2.99 +/- 1.10, P < 0.05) and control (0.85 +/- 0.34 and 2.40 +/- 1.00, P < 0.05) respectively. The Hsp72 median level of all subjects was used as the limit to divide subjects into high Hsp72 level group and low Hsp72 level group. The rate with high Hsp72 level was 36.7%, 43.1% and 58.3% in control, low exposure and high exposure workers respectively and had a rising tendency following exposure level (P = 0.003). In high Hsp72 level group Hsp72 level in high exposure workers was significantly higher than that in control (P < 0.05), and there was a rising tendency along with the increase of exposed levels. But the olive comet tail moment had no significant difference among three exposed groups (P > 0.05). In low Hsp72 level group there no difference among three exposed groups about Hsp72 levels. The olive comet tail moment in high exposure workers was significantly higher than that in low exposure workers and control (P < 0.01) and high exposure workers in Hsp72 positive group and there was a rising tendency along with the increase of exposed levels. Hsp72 levels had strong negative correlation with the olive comet tail moment (r = -0.503, P < 0.01) in high exposure workers. CONCLUSION: The coke oven emissions can induce hsp72 expression. Hsp72 play a role of protecting cells from DNA damage induced by coke oven emissions.

[Effects of MRP2-GSH cotransport system on hepatic arsenic metabolism in rats].

OBJECTIVE: To investigate the role of multidrug resistant protein 2 (MRP2) and glutathione (GSH) cotransport system in hepatic arsenic metabolism in rats. METHODS: Thirty healthy Wistar rats were divided randomizedly into five groups. The first group was the control group and the rats in this group were administered with normal saline. In the second, third and fourth group the rats were administered with 4, 10 and 20 mg As(+)3/kg BW of sodium arsenite respectively every other day for two weeks. The fifth group was the benzene-soluble organics (BSO) intervention group and in this group the rats were administered with 2 mmol/kg BW BSO intraperitoneally every day three days before the end of the experiment. The other treatment was the same as in other groups. All rats were sacrificed two weeks after the treatments. Arsenic contents in bile, liver and blood were detected by atomic absorption spectroscopy (AAS), and the expression of MRP2 in the membrane of hepatocyte was determined by Western-blot analysis. RESULTS: The level of total arsenic (including organic arsenic and inorganic arsenic) in bile, liver and blood in all three different dose groups was higher than those in the control groups (P < 0.05). Arsenic levels of bile and liver were increased with intragastric arsenic dose. Blood arsenic levels were not significantly different in three different dose groups. Expression of hepatic MRP2 was increased with intragastric arsenic concentration. A positive correlation between biliary arsenic concentration and MRP2 levels was found in liver (r = 0.986, P < 0.05). For the rats pretreated with BSO, the biliary arsenic was significantly higher than that in the control group but lower than that in the high dose group; the liver and blood arsenic was higher than that in the control group and in the high dose group. Expression of MRP2 pretreated with BSO was decreased. CONCLUSION: Sodium arsenite can induce expression of MRP2 and the up-regulation of MRP2 may play an important role in the bile secretion of arsenite and its metabolites. The function of MRP2 for transportation of arsenic and its metabolites is associated with the intracellular GSH level. BSO inhibits the synthesis of GSH, which weakens the function of the MRP2-GSH cotransport system and makes the liver arsenic increased.