Changes in miR-222 expression, DNA repair capacity, and MDM2-p53 axis in association with low-dose benzene genotoxicity and hematotoxicity.

Mechanisms for hematotoxicity and health effects from exposure to low doses of benzene (BZ) remain to be identified. To address the information gap, our investigation was focused onto using appropriate populations and cell cultures to investigate novel BZ-induced effects such as disruption of DNA repair capacity (DRC). From our study, abnormal miRNAs were identified and validated using lymphocytes from 56 BZ-poisoned workers and 53 controls. In addition, 173 current BZ-exposed workers and 58 controls were investigated for key miRNA expression using RT-PCR and for cellular DRC using a challenge assay. Subsequently, the observed activities in lymphocytes were verified using human HL-60 (p53 null) and TK6 (p53 wild-type) cells via 1,4-benzoquinone (1,4-BQ) treatment and miR-222 interferences. The targeting of MDM2 by miR-222 was validated using a luciferase reporter. Our results indicate induction of genotoxicity in lymphocytes from workers with low exposure doses to BZ. In addition, miR-222 expression was up-regulated among both BZ-poisoned and BZ-exposed workers together with inverse association with DRC. Our in vitro validation studies using both cell lines indicate that 1,4-BQ exposure increased expression of miR-222 and Comet tail length but decreased DRC. Loss of miR-222 reduced DNA damage, but induced S-phase arrest and apoptosis. However, silencing of MDM2 failed to activate p53 in TK6 cells. In conclusion, our in vivo observations were confirmed by in vitro studies showing that BZ/1,4-BQ exposures caused genotoxicity and high expression of miR-222 which obstructed expression of the MDM2-p53 axis that led to failed activation of p53, abnormal DRC and serious biological consequences.

Aberrant lncRNA Profiles Are Associated With Chronic Benzene Poisoning and Acute Myelocytic Leukemia.

OBJECTIVE: This study investigates the mechanisms of benzene hematotoxicity. METHODS: We used microarray to detect expression profiles of long non-coding RNAs (lncRNAs) and mRNAs in peripheral lymphocytes from chronic benzene poisoning, acute myelocytic leukemia, and healthy controls. The lncRNAs and mRNAs were validated using real-time quantitative PCR (RT-qPCR). Cytokinesis-block micronucleus assay was used to analyze chromosomal aberration. RESULTS: We found 173 upregulated and 258 downregulated lncRNAs, and 695 upregulated and 804 downregulated mRNAs. The lncRNA CUST_40243 and mRNA PDGFC and CDKN1A associated with chronic benzene poisoning. Relevant inflammatory response, hematopoietic cell lineage, and cell cycle may be important pathways for the sifted lncRNAs and mRNAs. Furthermore, micronuclei frequency was significantly higher in off-post chronic benzene poisoning patients. CONCLUSIONS: Chromosomal aberration induced by benzene exposure is irreversible. The lncRNA CUST_40243 and mRNA PDGFC and CDKN1A are related to chronic benzene poisoning.

[Pathology and neurophysiology analysis for peripheral neuropathy of four patients with chemicals poisoning].

OBJECTIVE: To study the nerve electromyogram results by analysing the pathological characters of 4 cases diagnosed as peripheral neuropathy caused by n-hexane and arsenic. METHODS: The nerve electromyogram examination and pathology data of 4 patients, who had been diagnosed as toxic chemicals peripheral neuropathy, were studied retrospectively. RESULTS: Two patients in this group were exposed to n-hexane, their nerve electromyogram examinations and biopsy pathology of superficial peroneal nerve indicated the peripheral neuropathy was mainly manifests the lesion of medullary sheath. Another two patients were exposed to arsenic, their nerve electromyogram examinations showed axonal degeneration associated with demyelination, and their biopsy pathology showed the peripheral neuropathy was mainly axonal degeneration. CONCLUSION: Axonal degeneration and demyelination always coexist in peripheral neuropathy caused by chemicals.

Case of interstitial lung disease possibly induced by exposure to iron dust.

Interstitial lung diseases are primarily attributable to occupational or environmental exposures to dusts and irritants. We report on a case of interstitial lung disease, possibly secondary to iron exposure. Our male patient presented with cough and shortness of breath of more than 20 years' duration after his occupational exposure had ended. A chest radiograph showed patchy shadows throughout both lower fields, and computed tomography showed ground-glass-like opacification, with fibrosis in the lower lobes. A lung biopsy revealed foamy cells in the alveolar spaces, with bronchiolitis obliterans. Microelemental analysis showed an increased level of iron in the lung tissue. After treatment with N-acetyl cysteine effervescent tablets, the patient's symptoms gradually improved. This probable case of iron-induced interstitial lung disease suggests the importance of obtaining a patient's history of occupational and environmental exposures for the sake of an accurate diagnosis.

[Establishment of acute pulmonary edema model induced by high concentrations of nitrogen dioxide in rats].

OBJECTIVE: To establish the rats model of acute pulmonary edema induced by inhalation of high concentrations of nitrogen dioxide (NO2). METHODS: 38 SD rats were divided into the experimental group (n = 30) and the control group (n = 8). 30 rats in the experimental group were exposed to (6747.47 ± 25.24) mg/m(3) NO2 in the exposure system. At the time point of 6, 12, 18, 24 h, chest X-ray examination was taken for the experimental group. And at each time point, 6 rats were sacrificed after taking blood samples. After sacrificing, the lung of rats was taken for pathological examination and calculated lung wet/dry weight ratio. Erythrocyte superoxide dismutase (SOD) activity and plasma atrial natriuretic peptide (ANP) concentration of blood samples were detected. RESULTS: Acute pulmonary edema was successfully induced by exposure to NO2 in 30 rats within 24 hours. There were some cloudy shadows without clear edge on the chest X-ray. To the time point of 12 hours, shadows combined with each other, and to the time point of 18 hours, the whole lung became "white" on the X-ray. The situation stabilized but not improved at the time point of 24 hours. HE staining of the lung tissue showed that to the time point of 6 hours, the alveolar gap increased and small amount of eosinophilic liquid leaked into alveolar. To the time point of 12 hours, alveolar combined with each other and eosinophilic liquid increased in amount. To the time point of 18 hours, the whole alveolar was filled with eosinophilic liquid and the situation stabilized till the time point of 24 hours. Wet/dry weight ratio of the experimental group at each time point were 5.6 ± 0.20, 6.89 ± 0.25, 8.03 ± 0.47, 7.81 ± 0.45. There was significant difference compared with the control group which was 4.72 ± 0.06 (P < 0.01). There was statistical difference between 12, 18, 24 h and 6 h time points (P < 0.01). Moreover, statistical difference was observed between 18, 24 h and 12 h time points for wet/dry weight ratio (P < 0.01). The erythrocyte SOD activity reduced significantly. Compared with the control group, there was a statistical difference (P < 0.01) at each time point. After exposure of 18 and 24 hours, plasma ANP concentration (136.66 ± 35.37) and (134.10 ± 60.41) ng/ml respectively, which were higher than (31.31 ± 13.06) ng/ml of control group and (34.71 ± 13.42) ng/ml of 6 hours time point and (47.98 ± 7.86) ng/ml. The differences were significant (P < 0.01). CONCLUSION: High concentrations of NO2 can induce acute pulmonary edema model successfully in SD rats.

[Preliminary experimental research on glucocorticoid for treatment of nitrogen dioxide induced acute pulmonary edema in rats].

OBJECTIVE: To investigate the therapeutic effect of glucocorticoids on the acute pulmonary edema in rats induced by nitrogen dioxide (NO2). METHODS: Thirty SD female rats were randomly equally divided into 5 groups: normal control group, NO2 exposed group, high-, middle- and low-dose of glucocorticoids treated group (6 rats per group). 6 rats in the normal control group were exposed to room air for 30 min, and the other rats to NO2. 18 rats in the glucocorticoids group were treated with different doses of dexamethasone (6.0, 3.0, 1.0 mg/kg), while the rats in the NO2 poisoning group were treated with normal saline (2.5 mg/kg). The lung wet/dry (W/D) weight ratio was calculated, and plasma atrial natriuretic peptide (ANP) levels, superoxide dismutase (SOD) activity from whole blood, plasma interleukin 6 (IL-6), interleukin 10 (IL-10), tumor necrosis factor-α (TNF-α) and Interferon-γ (IFN-γ) were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: The lung W/D ratios were increased significantly in glucocorticoids treated group and NO2-exposed group compared with normal control group (P < 0.05), while they were significantly reduced in glucocorticoids treated group as compared with NO2-exposed group (P < 0.05). SOD activity in whole blood in glucocorticoids treated group and NO2-exposed group was significantly lower than that of normal control group (P < 0.05), while it was no significant difference between that of glucocorticoids treated group and NO2-exposed group (P > 0.05). Plasma ANP was significantly increased in NO2-exposed group compared with normal control group (P < 0.05), while it was significantly decreased in glucocorticoids treated group compared with NO2-exposed group (P > 0.05). Plasma TNF-α of high-, middle- and low-dose of glucocorticoids treated group [(27.04 ± 8.19), (40.10 ± 9.09), (39.76 ± 9.60) pg/ml] was decreased significantly as compared with NO2-exposed group (68.55 ± 27.84 pg/ml) (P < 0.05). Plasma IL-6 in high- and middle-dose of glucocorticoids treated group [(15.97 ± 6.18), (19.69 ± 5.52) pg/ml] was significantly decreased as compared to NO2-exposed group [(29.29 ± 9.31) pg/ml] (P < 0.05). Plasma IL-10 in high-, middle- and low-dose of glucocorticoids treated group [(23.24 ± 5.14), (27.78 ± 8.17), (33.29 ± 10.42) pg/ml] was significantly reduced compared with NO2-exposed group [(44.38 ± 9.19) pg/ml] (P < 0.05). Plasma IFN-γ in high- and middle-dose of glucocorticoids treated group [(7.21 ± 4.55), (19.23 ± 4.35) pg/ml] was reduced compared with NO2-exposed group [(30.83 ± 6.82) pg/ml] (P < 0.05). CONCLUSION: High-, middle-, low-dose glucocorticoids all can improve the permeability of alveolar wall and capillary, and have nonspecific anti-inflammatory effects. The therapeutic effects on pulmonary edema are significant. High and middle dose of glucocorticoids treated group are more useful for decreased inflammatory factors.