Glucocorticoid inhibits the human pro-interleukin lbeta gene (ILIB) by decreasing DNA binding of transactivators to the signal-responsive enhancer.

Elucidating the role of glucocorticoid in regulating gene expression is crucial to developing effective strategies against inflammatory diseases such as arthritis. In this report we demonstrate that glucocorticoid inhibits transcription directed by the IL-lbeta gene (IL1B) upstream induction sequence (UIS) enhancer, and to a much lesser extent by the tissue-specific basal promoter. Within the enhancer, three transcription factor binding sites, previously demonstrated by us to be important for the induction of IL1B by lipopolysaccharide, are now shown to be directly inhibited by the synthetic glucocorticoid, dexamethasone. We also previously showed that one of these sites could bind a novel STAT-like factor, while the other two bound heterodimers containing NF-IL6(C/EBPbeta). Although it has been reported by others that NF-IL6 homodimers can interact with glucocorticoid receptor (GR) to enhance transcription of the alpha1-acid glycoprotein gene, it now appears that glucocorticoid represses DNA binding of NF-IL6 heterodimers as well as the novel STAT-like factor to the critical sites within the IL1B UIS. Thus, GR likely disrupts the DNA binding capability of critical IL1B factors via transrepression.

MPO and SOD2 polymorphisms, gender, and the risk of non-small cell lung carcinoma.

Manganese superoxide dismutase (SOD2) and myeloperoxidase (MPO) are polymorphic enzymes involved in reactive oxidative species metabolism. In this case-control study (830 non-small cell lung carcinoma (NSCLC) patients; 1119 controls) we evaluated whether the MPO -G463A polymorphism (associated with a novel estrogen receptor binding site) modifies the association between the SOD2 Ala16Val polymorphism and NSCLC risk differently by gender. For women carrying the MPO variant genotypes, the adjusted odds ratio of the SOD2 polymorphism (Val/Val vs. Ala/Ala) was 3.26 (95% CI, 1.55-6.83). No associations were found in men or in women carrying the MPO GG wildtype genotype.

Polymorphism in the surfactant protein-B gene, gender, and the risk of direct pulmonary injury and ARDS.

STUDY OBJECTIVE: Major risk factors for ARDS have been identified. However, only a minority of patients with such risks develops ARDS. It is likely that, given the same type and degree of insult, there are heritable determinants of susceptibility to ARDS. To investigate the possibility of variable genetic susceptibility to ARDS, we examined the association between ARDS and a polymorphism in intron 4 of the surfactant protein-B (SP-B) gene. DESIGN: Nested case-control study conducted from September 1999 to March 2001. SETTING: Four adult medical and surgical ICUs at a tertiary academic center. PATIENTS: One hundred eighty-nine patients meeting study criteria for a defined risk factor for ARDS were enrolled and prospectively followed. MEASUREMENTS AND RESULTS: Seventy-two patients (38%) developed ARDS. After stratification by gender and adjustment for potential confounders, there was a significantly increased odds for women with the variant SP-B gene to develop ARDS compared to women homozygous for the wild-type allele (odds ratio [OR], 4.5; 95% confidence interval [CI], 1.1 to 18.8; p = 0.03). Women with the variant SP-B polymorphism also had significantly increased odds of having a direct pulmonary injury such as aspiration or pneumonia as a risk factor for ARDS as opposed to an indirect pulmonary risk for ARDS (OR, 4.6; 95% CI, 1.1 to 19.9; p = 0.04). No such association with ARDS or direct pulmonary injury was found for men. CONCLUSION: The variant polymorphism of the SP-B gene is associated with ARDS and with direct pulmonary injury in women, but not in men. Further study is needed to confirm the association between the variant SP-B gene, and gender, ARDS, and direct pulmonary injury.

Genotyping patients with recent blood transfusions.

BACKGROUND: Many studies have used polymerase chain reaction amplification (PCR) to genotype for common polymorphisms in intensive-care units (ICUs) where blood transfusions are common. Evidence that donor leukocytes in transfused blood can be detected by PCR of the recipient blood suggests that this minor population of donor white cells (microchimerism) can interfere with genotyping of allelic polymorphisms in critically ill transfused patients. To investigate this possibility, we assayed DNA extracted from the blood and buccal cells of ICU patients for 2 common polymorphisms in the TNF-beta gene and the surfactant protein-B (SP-B) gene. METHODS: Study subjects were ICU patients from the Massachusetts General Hospital (Boston, MA) enrolled into a study on the molecular epidemiology of acute respiratory distress syndrome between January 1999 and October 2000. Blood and buccal cells were collected and DNA was extracted from 145 patients. Genotyping was performed by enzyme digestion and pyrosequencing. RESULTS: The Kappa statistics comparing the genotype results from blood and buccal cells were 0.98 (95% confidence interval [CI] = 0.94-1.01) for TNFB and 0.95 (CI = 0.87-1.02) for SP-B. When the analysis was restricted only to the 107 patients who were transfused, the Kappa statistic remained high at 0.97 (CI = 0.93-1.01) for TNFB and 0.93 (CI = 0.84-1.03) for SP-B. CONCLUSION: We conclude that microchimerism from allogeneic blood transfusion is unlikely to have major effects on the genotype results of common polymorphisms in large molecular epidemiology studies conducted in the critical care setting if DNA is collected within a day after transfusions.

Polymorphisms in the DNA repair genes XRCC1 and ERCC2, smoking, and lung cancer risk.

XRCC1 (X-ray cross-complementing group 1) and ERCC2 (excision repair cross-complementing group 2) are two major DNA repair proteins. Polymorphisms of these two genes have been associated with altered DNA repair capacity and cancer risk. We have described statistically significant interactions between the ERCC2 polymorphisms (Asp312Asn and Lys751Gln) and smoking in lung cancer risk. In this case-control study of 1091 Caucasian lung cancer patients and 1240 controls, we explored the gene-environment interactions between the XRCC1 Arg399Gln polymorphism, alone or in combination with the two ERCC2 polymorphisms, and cumulative smoking exposure in the development of lung cancer. The results were analyzed using logistic regression models, adjusting for relevant covariates. Overall, the adjusted odds ratio (OR) of XRCC1 Arg399Gln polymorphism (Gln/Gln versus Arg/Arg) was 1.3 [95% confidence interval (CI), 1.0-1.8]. Stratified analyses revealed that the ORs decreased as pack-years increased. For nonsmokers, the adjusted OR was 2.4 (95% CI, 1.2-5.0), whereas for heavy smokers (>/=55 pack-years), the OR decreased to 0.5 (95% CI, 0.3-1.0). When the three polymorphisms were evaluated together, the adjusted ORs of the extreme genotype combinations of variant alleles (individuals with 5 or 6 variant alleles) versus wild genotype (individuals with 0 variant alleles) were 5.2 (95% CI, 1.7-16.6) for nonsmokers and 0.3 (95% CI, 0.1-0.8) for heavy smokers, respectively. Similar gene-smoking interaction associations were found when pack-years of smoking (or smoking duration and smoking intensity) was fitted as a continuous variable. In conclusion, cumulative cigarette smoking plays an important role in altering the direction and magnitude of the associations between the XRCC1 and ERCC2 polymorphisms and lung cancer risk.

Counterpoint: the myeloperoxidase -463G-->a polymorphism does not decrease lung cancer susceptibility in Caucasians.

The myeloperoxidase (MPO) G-to-A substitution polymorphism in the promoter region of the MPO gene has been associated with a 40-70% reduction in lung cancer risk in several studies, although a recent nested case-control study disputes these findings. MPO is involved in the activation of a number of procarcinogens, including benzo(a)pyrene. The variant A allele has been shown to reduce MPO mRNA expression, thus potentially decreasing carcinogen activation. To confirm results from smaller studies, we evaluated this MPO polymorphism in 988 incident Caucasian lung cancer cases and 1128 controls. Logistic regression evaluated the association between MPO genotype and lung cancer risk, adjusting for age, gender, smoking status, time since quitting smoking, and pack-years of smoking. In the controls, the A allele frequency was 21%, and genotype distribution was in the Hardy-Weinberg equilibrium. Compared with the wild-type G/G genotype, the adjusted odds ratios for the A/A and A/G genotypes were 1.15 (95% confidence interval 0.7-1.9, P > 0.2) and 1.03 (95% confidence interval 0.8-1.3, P > 0.20), respectively. A similar lack of association was seen in analyses stratified by smoking status, median age, a number of smoking variables, disease stage, tumor grade, and histological subtype. These findings are in contrast with earlier studies suggesting a protective effect of carrying the variant A allele.

Gene-environment interaction for the ERCC2 polymorphisms and cumulative cigarette smoking exposure in lung cancer.

Excision repair cross-complementing group 2 (ERCC2), a major DNA repair protein, is involved in nucleotide excision repair and basal transcription. The ERCC2 polymorphisms have been associated with altered DNA repair capacity. We investigated two ERCC2 polymorphisms, Asp312Asn and Lys751Gln, in 1092 Caucasian lung cancer patients and 1240 spouse and friend controls. The results were analyzed using generalized additive models and logistic regression, adjusting for relevant covariates. The overall adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were 1.47 (95% CI, 1.1-2.0) for the Asp312Asn polymorphism (Asn/Asn versus Asp/Asp) and 1.06 (95% CI, 0.8-1.4) for the Lys751Gln polymorphism (Gln/Gln versus Lys/Lys). Gene-smoking interaction analyses revealed that the adjusted ORs for each of the two polymorphisms decreased significantly as pack-years increased. When comparing individuals with Asn/Asn + Gln/Gln versus individuals with Asp/Asp + Lys/Lys, the fitted ORs (95% CIs) were 2.56 (95% CI, 1.3-5.0) in nonsmokers and 0.69 (95% CI, 0.4-1.2) in heavy smokers (80 pack-years; P < 0.01 for the interaction term). Consistent and robust results were found when models incorporated different definitions of cumulative cigarette smoking. A stronger gene-smoking interaction was observed for the Asp312Asn polymorphism than for the Lys751Gln polymorphism. In conclusion, cumulative cigarette smoking modifies the associations between ERCC2 polymorphisms and lung cancer risk.

Genetic polymorphisms in N-acetyltransferase-2 and microsomal epoxide hydrolase, cumulative cigarette smoking, and lung cancer.

N-acetyltrasferase-2 (NAT2) and microsomal epoxide hydrolase (mEH) are polymorphic genes that metabolize different tobacco carcinogens. Smaller studies found inconsistent relationships between NAT2 or mEH polymorphisms and lung cancer risk. To determine whether there is gene-environment interaction between NAT2 polymorphisms, alone or in combination with mEH polymorphisms, and cumulative smoking exposure in the development of lung cancer, we conducted a case control study of 1115 Caucasian lung cancer patients and 1250 spouse and friend controls. The results were analyzed using generalized additive models and logistic regression, adjusting for relevant covariates. There was no overall relationship between NAT2 genotype and lung cancer risk; the adjusted odds ratio (OR) of the rapid versus slow acetylator genotypes was 0.96 [95% confidence interval (CI), 0.79-1.16]. However, gene-environment interaction analyses revealed that the adjusted ORs increased significantly as pack-years increased. For nonsmokers, the fitted OR was 0.66 (95% CI, 0.44-0.99), whereas for heavy smokers (80 pack-years), the OR increased to 1.22 (95% CI, 0.89-1.67). When comparing the extreme genotype combinations of the NAT2 rapid acetylator, higher mEH activity genotype to the NAT2 slow acetylator, and very low mEH activity genotype, the corresponding ORs at 0 and 80 pack-years were 0.30 (95% CI, 0.14-0.62) and 2.19 (95% CI, 1.26-3.81), respectively. Results were similar with ORs derived from stratified models. In conclusion, NAT2 rapid acetylator genotypes are protective against lung cancer in nonsmokers but are risk factors in heavy smokers. The joint effects of NAT2 and mEH polymorphisms are consistent with an independent, additive effect of these two genes, modified by smoking history.