Expression deregulation of genes related to DNA repair and lead toxicity in occupationally exposed industrial workers

OBJECTIVE

Globally millions of people working in various industries and are exposed to different toxins which may affect their genetic stability and DNA integrity. Present study was designed to estimate the expression variation of genes related to DNA repair (XRCC1, PARP1) and lead toxicity (ALAD) in exposed industrial workers.

METHODS

About 200 blood samples were collected from workers of brick kiln, welding, furniture and paint industry (50/industry) along with age and gender matched controls. mRNA expression of genes was measured using RT-PCR. Serum levels of total ROS, POD, TBAR activity was calculated. Blood lead levels were estimated by atomic absorption spectrometer.

RESULTS

Relative expression of XRCC1 and PARP1 gene was significantly (P < 0.001) upregulated, while ALAD gene expression was downregulated in exposed group compared to control. Expression of XRCC1 and PARP1 was increased (P < 0.001) in exposed workers with > 30 year age compared to control with > 30 year age. Same was observed when < 30 year age group of control and exposed was compared. Likewise, XRCC1 and PARP1 expression was increased (P < 0.001) in exposed workers with > 30 year age compared to workers with < 30 year age. Whereas, ALAD gene showed significant (P < 0.01) decrease in > 30 year age workers compared to control of same age and exposed with < 30 year of age. Relative expression of XRCC1 and PARP1 was increased (P < 0.001) in exposed smokers compared to exposed non-smokers and control smokers. Whereas, ALAD gene expression reduced (P < 0.001) significantly in both groups. Blood lead content was higher (P < 0.001) in exposed group compared to control. Strong correlation was observed between XRCC1, PARP1 and ALAD gene versus age, total exposure duration, exposure per day and lead deposition. ROS, TBARS and POD activity was higher (P < 0.01) in exposed group compared to control group.

CONCLUSION

Present study suggested deregulation of genes related to DNA repair and lead intoxication in exposed group compared to controls. Strong correlation was observed between selected genes and demographic parameters. Present results revealed altered activity of oxidative stress markers which would induce oxidative damage to DNA integrity and limit the function of repair enzymes.

Telomere length in peripheral leukocytes is a sensitive marker for assessing genetic damage among workers exposed to isopropanol, lead and noise: the case of an electronics manufacturer

BACKGROUND

Workers in electronics manufacturers may be exposed to various occupational hazards such as isopropanol, lead, and noise. Telomeres are special segments of cap-like DNA protein complex at end of liner chromosomes in eukaryotic cells. Telomere length is a potential marker of genetic damage. The aim of this study is to evaluate the effect of occupational hazards on the relative telomere length (rTL) of peripheral blood cells of workers in an electronics manufacturer, and to explore whether relative telomere length could be a biomarker for assessing genetic damage in the electronics manufacturing industry.

METHODS

We investigated a large-scale electronics manufacturer in the Pearl River Delta Region. We ultimately collected 699 qualified workers (248 with isopropanol exposure, 182 with lead exposure, 157 with noise exposure, and 112 controls). During physical examination of the workers, we gave them questionnaires to understand their health statuses and living habits. We also collected peripheral blood samples from these workers to test exposure levels and rTL in the leucocytes.

RESULTS

The concentrations of air isopropanol in all monitored workshops was 25.3 mg/m³ and air lead smoke was 0.020 mg/m³. The maximum equivalent continuous A sound level noise exposure position was 82.2dB (A). All were lower than those in the Occupational Exposure Limits in Workplaces in China. Urinary acetone in the isopropanol exposed group was 1.04 (0, 1.50) mg/L, and cumulative urinary acetone was 1.48 (0, 5.09) mg-years/L. Blood lead levels (BLLs) were 28.57 (22.77, 37.06) µg/dL, and cumulative blood lead levels (CBLLs) were 92.75 (55.47, 165.13) µg-years/dL. rTL was different between occupational exposed workers and controls: rTL was 0.140 units (95 % CI: 0.022, 0.259) shorter in lead exposed workers and 0.467 units (95 % CI: 0.276-0.658) shorter in noise exposed workers compared to the controls. There is no statistical difference in rTL between isopropanol exposure workers and the controls. In order to elucidate the relationship between rTL and occupational hazards exposure, we divided the isopropanol exposure workers into three groups (0, ~1.43 mg/L, and >1.43 mg/L). None of the rTL difference was statistically significant among exposed workers at different uroacetone levels (P>0.05). The groups with ≥100 µg/dL blood lead had shorter rTL than the group with blood lead below 100 µg/dL (F=4.422, P=0.013). We incorporated age, gender, birthplace, race, education level, smoking, and alcohol consumption into the linear regression equation. Only blood lead concentration (X) was entered into the regression equation, yielding a multivariate linear regression equation of Y=0.397-0.124X (F=8.091, P=0.005). Workers with different hearing loss also had statistically significant differences in rTL (F=5.731, P=0.004). rTL was a protective factor for the occurrence of noise-induced hearing loss (NIHL). The longer the rTL, the lower the risk of NIHL [OR=0.64 (0.42, 0.98)].

CONCLUSIONS

rTL was shorter in lead exposed workers and noise exposed workers, and it was a protective factor for the occurrence of the noise-induced hearing loss. Thus, rTL of peripheral blood may be a sensitive marker of genetic damage among workers in environments with lead and noise exposure.

Maternal Δ-aminolevulinic acid dehydratase 1-2 genotype enhances fetal lead exposure and increases the susceptibility to the development of cerebral palsy

Limited epidemiologic studies questioned the association between pre- and postnatal lead exposure and the development of cerebral palsy (CP). Moreover, the genotypes of δ-aminolevulinic acid dehydratase (δ-ALAD) in CP patients and their mothers and their association to the blood lead levels (BLLs) were not previously studied. This study aimed to evaluate the association between δ-ALAD gene polymorphism and BLL in cases of CP and their mothers. A case control study was carried out on 23 CP cases and equal number of healthy matched controls. The mothers of the included children were asked to answer a questionnaire involving the baseline clinical and demographic characteristics. Also, questionnaires were done to detect the sources of environmental lead exposure and screen lead exposure during the pregnancy period. BLL, δ-ALAD enzyme activity, and genetic analysis for ALAD G177C were done for each child and his mother. There was significant (p < 0.001) elevation of BLL in CP cases and their mothers that was positively correlated (r = 0.436, p < 0.05). There were progressive decreases in δ-ALAD activity with increasing BLL in both children and mothers (p < 0.05). There were non-significant (p > 0.05) differences between CP and the control group regarding frequency of ALAD G177C genotypes, while there was a significant (p = 0.04) increase in the frequency of ALAD 1-2 (GC) genotype in the mothers of the CP group associated with high BLL and significant decrease in δ-ALAD activity (p < 0.001). The study can indicate the significance of δ-ALAD gene polymorphism in the prenatal exposure to lead and the affection of the developing brain, pointing to the importance of controlling lead in pregnant women especially those with ALAD 1-2 genotype.

Effects of delta-Aminolevulinic Acid Dehydratase Gene Polymorphism on Hematological Parameters and Kidney Function of Lead-exposed Workers

Lead exposure is associated with several health hazards among workers with different individual responses. We conducted this study to determine the possible effects of lead exposure on hematological parameters and kidney function of a group of Egyptian ammunition workers and the interaction of aminolevulinic acid dehydratase (ALAD) G177C gene polymorphisms as an effect modifier. Significant differences were observed between exposed workers with ALAD1-1 and ALAD1-2 genotypes in terms of blood lead level, hematological parameters and kidney function. It seems that δ-ALAD gene polymorphism may be an effect modifier and a marker of genetic susceptibility to lead toxicity.

Oxidative stress in opium users after using lead-adulterated opium: The role of genetic polymorphism

Use of lead-adulterated opium has become one of the major sources of lead poisoning in Iran. This study was designed to assess clinical effects and oxidative stress and its association with GSTM1, GSTT1, NQO1, and ALAD genes polymorphisms and blood lead level (BLL) in lead-adulterated opium users. The oxidative stress status in 192 opium users with lead poisoning symptoms measured and compared with 102 healthy individuals. Gluthatione S-transferase (GST)-M1 and -T1 genes deletion, NQO1 rs1800566, and δ-aminolevulinic acid dehydratase (ALAD) rs1800435 polymorphisms were determined using PCR and PCR-RFLP. The relation between the polymorphisms, BLL, and oxidative stress parameters were analysed using multivariate linear regressions. The common symptoms of lead toxicity were gastrointestinal and neurologic complications. Oxidative stress was significantly higher in opium addicts and lipid peroxidation significantly correlated with BLL. There was significant association between ALAD rs1800435 and BLL, and the BLL was significantly lower in the patients with ALAD 1-2 genotype. Use of lead-adulterated opium causes high frequency of lead toxicity symptoms, hematological and biochemical abnormalities, and oxidative stress which are associated with BLL. Route of opioid use and the polymorphism of rs1800435 in ALAD gene are the major determinants of BLL in lead-adulterated opium users.

Lead induces DNA damage and alteration of ALAD and antioxidant genes mRNA expression in construction site workers

Oxidative stress and DNA damage are considered as possible mechanisms involved in lead toxicity. To test this hypothesis, DNA damage and expression variations of aminolevulinic acid dehydratase (ALAD), superoxide dismutase 2 (SOD2), and 8-oxoguanine DNA glycosylase 2a (OGG1-2a) genes was studied in a cohort of 100 exposed workers and 100 controls with comet assay and real-time polymerse chain reaction (PCR). Results indicated that increased number of comets was observed in exposed workers versus controls (p < 0.001). After qPCR analysis, significant down-regulation in ALAD (p < 0.0001), SOD2 (p < 0.0001), and OGG1-2a (p < 0.0001) level was observed in exposed workers versus controls. Additionally, a positive spearmen correlation was observed between ALAD versus SOD2 (r = 0.402**, p < 0.001), ALAD versus OGG1-2a (r = 0.235*, p < 0.05), and SOD2 versus OGG1-2a (r = 0.292*, p < 0.05). This study showed that lead exposure induces DNA damage, which is accompanied by an elevated intensity of oxidative stress and expression variation of lead-related gene.

Lead adsorption, anticoagulation and in vivo toxicity studies on the new magnetic nanomaterial Fe3O4@SiO2@DMSA as a hemoperfusion adsorbent

This project aimed to develop and characterize a new nanoadsorbent for hemoperfusion. Fe₃O₄ nanoparticles synthesized by a facile solvothermal method were coated with S_iO₂ and further modified by DMSA. TEM, XRD, FTIR, XPS and SEM were performed before and after lead adsorption to reveal the general performance and adsorption mechanism. Rabbit lead poisoning models were established to study the adsorption rate; then, a pig hemoperfusion experiment was used for further validation. In addition, coagulation, liver, kidney and heart function, blood lipids, electrolytes and the immune inflammatory system were studied before and after hemoperfusion. The results indicated that the materials had a high adsorption rate and chemisorbed lead mainly in the plasma. No obvious coagulation-fibrinolysis, organ toxicity, electrolyte disturbances, inflammatory reactions or immunosuppression was observed. The excellent blood compatibility and high biosafety of this material demonstrate its potential as a new type of hemoperfusion adsorbent.

The Antagonistic Effect of Selenium on Lead-Induced Inflammatory Factors and Heat Shock Proteins mRNA Expression in Chicken Livers

The aim of this study was to investigate the effect of lead (Pb) poisoning on nitric oxide (NO) content, inducible nitric oxide synthase (iNOS) activity, the messenger RNA (mRNA) levels of inflammatory factors (nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), prostaglandin E synthases (PTGEs), and iNOS), heat shock proteins (HSPs) (HSP27, HSP40, HSP60, HSP70, and HSP90), and the antagonistic effect of selenium (Se) on Pb in chicken livers. One hundred eighty 7-day-old male chickens were randomly divided into four groups and were fed commercial diet and drinking water, Na2SeO3-added commercial diet and drinking water, commercial diet and (CH3OO)2Pb-added drinking water, and Na2SeO3-added commercial diet and (CH3OO)2Pb-added drinking water, respectively, for 30, 60, and 90 days. Then, NO content, iNOS activity, and the mRNA levels of NF-κB, TNF-α, COX-2, PTGEs, iNOS, HSP27, HSP40, HSP60, HSP70, and HSP90 were examined in chicken livers. The results showed that Pb poisoning induced NO content, iNOS activity, and mRNA expression of inflammation factors and HSPs in chicken livers. In addition, Se alleviated Pb-induced increase of inflammation factor and HSP expression in chicken livers.

The relationship between selected VDR, HFE and ALAD gene polymorphisms and several basic toxicological parameters among persons occupationally exposed to lead

The aim of this study was to find a relationship between polymorphisms of ALAD rs1805313, rs222808, rs1139488, VDR FokI and HFE C282Y and H63D and basic toxicological parameters (lead and ZnPP blood concentration) in people occupationally exposed to lead. We collected data of 101 workers (age 25-63 years) directly exposed to lead. The toxicological lab tests included blood lead, cadmium and ZnPP concentration measurement and arsenic urine concentration measurement. Workers were genotyped for ALAD (rs1805313, rs222808, rs1139488), HFE (C282Y, H63D) and VDR (FokI). Individuals with the lead exposure and coexisting F allel in the locus Fok-I of VDR gene are suspected of higher zinc protoporphyrins concentrations. Workers exposed to the lead with the Y allel in the locus C282Y of the HFE gene are predisposed to lower ZnPP levels and individuals with coexisting H allel in the locus H63D HFE gene are predisposed to lower Pb-B levels. The T allel in the locus rs1805313 of the ALAD gene determines lower Pb-B and ZnPP levels in lead-exposed individuals. The heterozigosity of the locus rs2228083 of the ALAD gene has a strong predilection to higher Pb-B levels. The carriage of the C allel in the locus rs1139488 of the ALAD gene might determine higher Pb-B levels and the heterozigosity of the locus rs1139488 of the ALAD gene might result in higher ZnPP levels.

CONCLUSION

The study revealed relationship between VDR, HFE and ALAD genes polymorphism and basic toxicological parameters in occupationally exposed workers.