Fen Wu

Lack of Association between Cytokine Gene Polymorphisms and Silicosis and Pulmonary Tuberculosis in Chinese Iron Miners

Lack of Association between Cytokine Gene Polymorphisms and Silicosis and Pulmonary Tuberculosis in Chinese Iron Miners: Fen Wu, et al. Department of Occupational Health and Toxicology, School of Public Health, Fudan University, China—Silicosis is a fibrotic lung disease produced by the inhalation and deposition of silica dust. The association between silicosis and pulmonary tuberculosis (PTB) has been well established. Cytokines participate in the development and progression of silicosis and PTB. Functional polymorphisms in cytokine genes have been identified that alter cytokine production. The aims of the current investigation were to determine whether functional polymorphisms in the tumor necrosis factoralpha (TNF‐α) gene at position –308; in the transforming growth factor‐beta 1 (TGF‐β1) gene at positions −509, +869 (codon 10), and +915 (codon 25); in the interleukin‐10 (IL‐10) gene at position −1,082, −819 and −592; and in the intron 1 of the interferon‐gamma (IFN‐γ) gene at position +874 are associated with silicosis and PTB. We conducted a case‐control study with 183 silicosis patients and 111 silica‐exposed miners, and a 1:2 matched case‐control study of 61 PTB cases and 122 PTB‐free miners. Genotype analysis was performed on genomic DNA, using a polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) assay. There was complete linkage disequilibrium (LD) between the –819C and –592C alleles of the IL‐10 gene. The genotype frequencies were similar between cases and control subjects for all investigated cytokine polymorphisms (p>0.05). We did not find an association between the different genotypes and severity of silicosis. We assume that these genetic variants do not play a dominant role in silicosis and PTB in our Chinese population.

Genetic polymorphisms in alveolar macrophage response-related genes, and risk of silicosis and pulmonary tuberculosis in Chinese iron miners.

Alveolar macrophages (AMs) play a prominent role in influencing the development of lung inflammation and injury. The aim of this study is to investigate the roles of AMs response-related genes TNF-alpha, iNOS, and NRAMP1 (SLC11A1) in susceptibility to silicosis and pulmonary tuberculosis (PTB), and to analyze the interaction of dust exposure and genetic susceptibility to silicosis, interactions of TNF-alpha-308 and Natural Resistance-associated Macrophage Protein 1 (NRAMP1) INT4, D543N polymorphisms to PTB. Several epidemiological designs were used: retrospective investigations on dust exposure, case-control studies of 184 silicosis cases and 111 miners occupationally exposed to silica dust, and 1:2 matched case-control studies of 61 PTB cases and 122 PTB-free miners. The miners and controls were recruited from an iron mining operation in Anhui province, China. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was applied to detect single nucleotide polymorphisms. Despite the recruitment of high dust exposure among the controls, silicosis patients still had significantly higher dust exposure than controls (242.6 +/- 98.8 vs. 217.6 +/- 100.7 mg a/m(3)). The mutation of iNOS Ser608Leu is associated with protection against silicosis and against severity of silicosis in the miners. There is a 0.47-fold (95% CI: 0.28-0.79) decrease in risk of silicosis for individuals with C/T, T/T genotype compared with the wild-type homozygous (C/C) individuals after adjustment for occupational exposure, smoking, and drinking. The protection effect of the iNOS polymorphism was particularly detected in the > or = 150 mg a/m(3) exposure group (OR: 0.44, 95% CI: 0.22-0.91). However, no interaction of dust exposure with the iNOS polymorphism was observed. Furthermore, the variant NRAMP1 INT4 genotype is significantly associated with PTB in miners. No association of other polymorphisms (NRAMP1 D543N, TNF-alpha-308) and susceptibility to silicosis or PTB in Chinese miners was found. Our data showed a 3.26-fold (95% CI: 1.47-7.23) increased risk of PTB for miners carrying both the NRAMP1 D543N G/G and NRAMP1 INT4 G/C+C/C genotypes. Additionally, in miners with TNF-alpha-308 G/G genotype, the risk of PTB increased 2.38-fold if they carry the NRAMP1 INT4 G/C+C/C genotype (95% CI: 1.14-4.98). In conclusion, the C>T mutation of iNOS Ser608Leu may be an important protective factor to miners. On the other hand, the variant NRAMP1 INT4 may play a role in the development of PTB in Chinese miners. Therefore, the novel information can be used as guideline for further mechanistic investigations and for strengthening specific protection protocols for workers.

Polymorphisms in phase I and phase II metabolism genes and risk of chronic benzene poisoning in a Chinese occupational population

It is widely accepted that the cytotoxicity and genotoxicity of benzene results from the action of reactive metabolites. Therefore, genetic variation in metabolic enzyme genes may contribute to susceptibility to chronic benzene poisoning (CBP) in the exposed population. Using a case-control study that included 268 benzene-poisoned patients and 268 workers occupationally exposed to benzene in South China, we aimed to investigate the association between single-nucleotide polymorphisms in genes with phase I and II of metabolism and risk of CBP. The TaqMan technique was used to detect polymorphisms of CYP1A1, CYP1A2, CYP1B1, ADH1B, EPHX1, EPHX2, NQO1, MPO, GSTP1 and UGT1A6 genes. We also explored potential interactions of these polymorphisms with lifestyle factors such as cigarette smoking and alcohol consumption. A weak positive association was found between glutathione S-transferase pi-1 (GSTP1) rs1695 polymorphism and the risk of CBP (P = 0.046), but this association was not statistically significant (P = 0.117) after adjustment for potential confounders. Further analysis showed that the risk of CBP increased in the subjects with EPHX1 GGAC/GAGT diplotype (P = 0.00057) or AGAC/GAGT diplotype (P = 0.00086). In addition, we found that alcohol drinkers with the EPHX1 rs3738047 GA + AA genotypes and non-alcohol drinkers with the GSTP1 rs1695 AA genotype tended to be more susceptible to benzene toxicity. Our results suggest that genetic polymorphisms in EPHX1 may contribute to risk of CBP in a Chinese occupational population.

Genetic polymorphisms of XRCC1, HOGG1 and MGMT and micronucleus occurrence in Chinese vinyl chloride-exposed workers

In this study, a group of 313 workers occupationally exposed to vinyl chloride monomer (VCM) and 141 normal unexposed referents were examined for chromosomal damage using the cytokinesis-blocked micronucleus (CBMN) assay in peripheral lymphocytes. We explored the relationship between genetic polymorphisms of XRCC1 (Arg194Trp, Arg280His and Arg399Gln), MGMT(Leu84Phe) and hOGG1 (Ser326Cys) and susceptibility of chromosomal damage induced by VCM. Polymerase chain reaction-restriction fragment length polymorphism techniques were used to detect polymorphisms in XRCC1, hOGG1 and MGMT. It was found that the micronuclei (MN) frequency of exposed workers (4.86 +/- 2.80) per thousand was higher than that of the control group (1.22 +/- 1.24) per thousand (P < 0.01). Increased susceptibility to chromosomal damage as evidenced by higher MN frequency was found in workers with hOGG1 326 Ser/Cys genotype [frequency ratio (FR) = 1.21, 95% confidence interval (CI): 1.02-1.46; P < 0.05], XRCC1 194 Arg/Trp (FR = 1.12, 95% CI: 1.00-1.25; P < 0.05) and XRCC1 280 Arg/His and His/His genotypes (FR = 1.12, 95% CI 1.00-1.26, P < 0.05). Moreover, among susceptibility diplotypes, CGA/CAG carriers had more risk of MN frequency compared with individuals with wild-type CGG/CGG (FR = 1.67, 95% CI: 1.19-2.23; P < 0.05). MN frequency also increased significantly with age in the exposed group (FR = 1.13, 95% CI: 1.00-1.28; P < 0.05). Thus, CB-MN was a sensitive index of early damage among VCM-exposed workers. Genotype XRCC1 Arg194Trp, Arg280His, hOGG1 Ser326Cys, diplotype CGA/CAG and higher age may have an impact on the chromosome damage induced by VCM.

Genetic polymorphisms in hMTH1, hOGG1 and hMYH and risk of chronic benzene poisoning in a Chinese occupational population.

Oxidative damage to DNA induced by benzene is an important mechanism of its genotoxicity, which leads to chronic benzene poisoning (CBP). Therefore, genetic variation in DNA repair genes may contribute to susceptibility to CBP in the exposed population. We hypothesized that single nucleotide polymorphisms (SNPs) in hMTH1, hOGG1 and hMYH genes are associated with risk of CBP. We genotyped SNPs at codon 83 of hMTH1, codon 326 of hOGG1, and codon 324 of hMYH in 152 CBP patients and 152 healthy workers occupationally exposed to benzene without poisoning manifestations. The genotypes were determined by polymerase chain reaction-restrained fragment length polymorphism (PCR-RFLP) technique. There were 2.51-fold [adjusted odds ratio (OR(adj)), 2.51; 95% CI, 1.14-5.49; P=0.02] and 2.49-fold (OR(adj), 2.49; 95% CI: 1.52-4.07; P<0.01) increased risk of CBP for individuals carrying genotypes of hMTH1 83Val/Met+Met/Met and hOGG1 326Cys/Cys, respectively. Compared with individuals carrying genotypes of hOGG1 326Cys/Cys and hMYH 324His/His at the same time, there was a 0.33-fold (OR(adj), 0.33; 95% CI: 0.15-0.72; P<0.05) decreased risk of CBP for those with genotypes of hOGG1 326Ser/Cys+Ser/Ser and hMYH 324His/Gln+Gln/Gln. In the smoking group, there was a 0.15-fold (OR(adj), 0.15; 95% CI, 0.03-0.68; P=0.01) decreased risk of CBP for subjects carrying genotypes of hMYH 324His/Gln+Gln/Gln compared with those of genotype of hMYH 324His/His. Therefore, our results suggested that polymorphisms at codons 83 of hMTH1 and codon 326 of hOGG1 might contribute to CBP in a Chinese occupational population.

Genetic polymorphisms in metabolizing enzymes and susceptibility of chromosomal damage induced by vinyl chloride monomer in a Chinese worker population.

Objective: To evaluate whether polymorphisms in metabolizing enzymes contributed to susceptibility of chromosomal damage induced by vinyl chloride monomer (VCM). Methods: Cytokinesis block micronucleus test was performed on 185 VCM-exposed workers and 41 control subjects to detect chromosomal damage in peripheral lymphocytes. The polymerase chain reaction and restriction fragment length polymorphism technique was applied to detect polymorphisms of GSTT1, GSTM1, GSTP1G/A, CYP2E1G/C, and CYP2D6G/C. Poisson regression analysis was performed. Results: Sex, age, VCM exposure, GSTP1, and CYP2E1 genotype can influence chromosomal damage. There was a 1.51-fold increased micronucleus frequency for GSTP1GG genotypes individuals compared with those GSTP1AA/GA genotype individuals (P < 0.05), the effect of polymorphism in CYP2E1 gene was more pronounced for allele C compared with allele G (P < 0.05). Conclusions: Polymorphisms of GSTP1G/A and CYP2E1G/C, which are potential susceptibility biomarkers of chromosomal damage in VCM-exposed worker.

Genetic polymorphisms of IL-1A, IL-1B, IL-1RN, NFKB1, FAS, and FASL, and risk of silicosis in a Chinese occupational population.

OBJECTIVE To test whether polymorphisms in IL-1, NF-KB, FAS, and FASL genes are associated with risk of silicosis. METHODS A case-control study was conducted with 183 silicosis patients and 111 silica-exposed miners who were frequency-matched by age, dust exposure duration, work location, and type of work. Genotype analysis was performed on genomic DNA, using a PCR-RFLP assay. RESULTS Individuals carrying the NFKB1 ins/del genotype had a decreased risk of silicosis (adjusted OR = 0.57, 95% CI = 0.32-0.998, P = 0.049) compared with subjects carrying the ins/ins genotype and individuals with the FAS-1377AA homozygote had a decreased risk of silicosis compared with those with the -1377GG genotype (adjusted OR = 0.42, 95% CI = 0.19-0.93, P = 0.03). The analysis of haplotypes of polymorphisms in FAS showed that there was a 2.71-fold (OR = 2.71, 95% CI = 1.22-6.03, P = 0.011) increased risk of silicosis for subjects with alleles of FAS-1377G and FAS-670G, compared with those carrying alleles of FAS-1377G and FAS-670A. CONCLUSION Although the polymorphisms at NFKB1, FAS-1377, and extended haplotype FAS-1377G/-670G may play a role in the development of silicosis in the Chinese population, our findings should be verified by larger studies with >1 case/control ratio.

Correlation of chromosome damage and promoter methylation status of the DNA repair genes MGMT and hMLH1 in Chinese vinyl chloride monomer (VCM)-exposed workers

ObjectiveTo explore the association of the methylation status of MGMT and hMLH1 with chromosome damage induced by vinyl chloride monomer (VCM).Materials and MethodsMethylation of MGMT and hMLH1 was measured in 101 VCM-exposed workers by methylation-specific PCR. Chromosome damage in peripheral blood lymphocytes was measured by the cytokinesis-block micronucleus assay. The subjects were divided into chromosome damaged and non-damaged groups based on the normal reference value of micronuclei frequencies determined for two control groups.ResultsMGMT promoter methylation was detectable in 5 out of 49 chromosome damaged subjects, but not in the chromosome non-damaged subjects; there was a significant difference in MGMT methylation between the two groups (p < 0.05).ConclusionsWe detected aberrant promoter methylation of MGMT in a small number of chromosome damaged VCM-exposed workers, but not in the chromosome non-damaged subjects. This preliminary observation warrants further investigation in a larger study.

Association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning.

The aim of this study was to explore the association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning (CBP). A case-control study of 268 patients with CBP and 268 healthy workers matched by age and sex, all of whom were occupationally exposed to benzene, was conducted. The single nucleotide polymorphisms (SNPs, rs2854451, rs3738047, rs2234922 and rs1051741) of EPHX1 gene and the SNP (rs751141) of EPHX2 gene were tested by the TaqMan PCR method. In the subjects carrying the genotype of EPHX1 rs3738047 GG, the risk of CBP was decreased in the individuals simultaneously carrying EPHX1 rs2234922 G (P = 0.02). Alternatively, in the subjects carrying the genotype of EPHX1 rs2234922 AA, the risk of CBP was increased in the individuals simultaneously carrying the allele of EPHX2 rs751141A (P = 0.03). It was also found that there were potential interactions between alcohol consumption and the polymorphism of EPHX1 rs1051741 (χH2 = 5.28, P = 0.02) or rs2234922 (χH2 = 6.71, P = 0.01). Compared to individuals with EPHX1 rs1051741 CC or rs2234922 AA genotype in the drinkers, the risk of CBP in those carrying genotypes of EPHX1 rs1051741 CT+TT or rs2234922 AG+GG was decreased, respectively (P = 0.04, P < 0.01). Haplotype analysis of polymorphisms in EPHX1 showed that the risk of CBP was increased in the subjects with haplotype 2 (rs2854451-A, rs3738047-G, rs2234922-A, rs1051741-C) or haplotype 4 (rs2854451-G, rs3738047-A, rs2234922-G, rs1051741-T), but decreased in those with haplotype 6 (rs2854451-G, rs3738047-G, rs2234922-G, rs1051741-T) or haplotype 10 (rs2854451-A, rs3738047-A, rs2234922-G, rs1051741-T), respectively. Logistic regression analysis revealed that smoking might play a role in modifying the risk of CBP (OR = 0.313, 95% CI: 0.123–0.794, P = 0.015). The genetic polymorphism in EPHX1 may be associated with the risk of CBP in the Chinese occupational population and further research is needed for the association between the genetic polymorphism in EPHX2 and the susceptibility to CBP.