Genetic polymorphism of GSTT1 and GSTM1 and susceptibility to chronic obstructive pulmonary disease (COPD)

Background

Chronic obstructive pulmonary disease (COPD) represents a major public health care problem worldwide due to its increasing prevalence, morbidity and mortality. Chronic obstructive pulmonary disease is known to be the fourth leading cause of death and the only cause of death, which is increasing. It is generally accepted that cigarette smoking is the most important risk factor for COPD. Nevertheless, only 10% to 20% of chronic smokers develop the severe impairment of pulmonary functions associated with COPD. This indicates the presence of genetic predisposing factors in its pathogenesis.

Objective

To test the hypothesis that genetic polymorphism of glutathione S-transferase θ 1 (GSTT1)and/or glutathione S-transferase μ 1 (GSTM1) is associated with COPD in smokers.

Materials and Methods

A case-control study was done on 34 patients with COPD and 34 matched controls. DNA was extracted from white blood cells by salting out method. GSTT1 and GSTM1 genotypes were amplified by polymerase chain reaction. The fragments were then analyzed by agarose gel electrophoresis. Statistical analysis was done using SPSS program.

Results

The frequency of carriers of null GSTT1 genotype was 50% among cases compared to 44.1% in the control group. Carriers of null GSTT1 were at minor risk of developing COPD when compared with carriers of the wild GSTT1 genotype (OR, 1.3; 95% CI, 0.5-3.3). In case of GSTM1, the frequency of carriers of null GSTM1 genotype was 52.9% among cases compared to 26.5% in controls. Carriers of null GSTM1 were at much higher risk of developing COPD (OR, 3.13; 95% CI, 1.1-8.6). Furthermore, the risk of developing COPD was increased among carrier of null GSTT1 &; GSTM1 haplotype (OR, 3.6; 95% CI, 1.1-11.6).

Conclusion

Carriers of null GSTM1 genotype were at high risk of developing COPD especially when they were null GSTT1 and GSTM1 haplotype.     

Telomere dysfunction implicates POT1 in patients with idiopathic pulmonary fibrosis

Exonic sequencing identified a family with idiopathic pulmonary fibrosis (IPF) containing a previously unreported heterozygous mutation in POT1 p.(L259S). The family displays short telomeres and genetic anticipation. We found that POT1(L259S) is defective in binding the telomeric overhang, nuclear accumulation, negative regulation of telomerase, and lagging strand maintenance. Patient cells containing the mutation display telomere loss, lagging strand defects, telomere-induced DNA damage, and premature senescence with G1 arrest. Our data suggest POT1(L259S) is a pathogenic driver of IPF and provide insights into gene therapy options.     

Erosion of telomeric single-stranded overhang in patients with aplastic anaemia carrying telomerase complex mutations

Background  Loss-of-function mutations in telomerase complex genes reduce telomerase activity and shorten overall telomere length in leucocytes, and they can clinically manifest as bone marrow failure (aplastic anaemia and dyskeratosis congenita) and familial pulmonary fibrosis. Telomeres are constituted of double-stranded tandem TTAGGG repeats followed by a 3' G-rich single-stranded overhang, a crucial telomeric structural component responsible for the t-loop formation.
Materials and methods  We investigated the length of telomeric overhangs in 25 healthy individuals from 0 to 76 years of age, 16 patients with aplastic anaemia, and 13 immediate relatives using a non-denaturing in-gel method and the telomere-oligonucleotide ligation assay.
Results  Telomeric overhang lengths were constant from birth to eighth decade of life in healthy subjects, in contrast to overall telomere length, which shortened with ageing. Most patients with marrow failure and a telomerase gene mutation showed marked erosion of telomeric overhang associated with critically short telomeres; in other aplastic patients with normal genotypes, normal overall telomere lengths and who responded to immunosuppressive therapy, telomeric overhangs were maintained.
Conclusions  Telomeric overhang erosion does not participate in physiological ageing but support a role for eroded telomeric overhangs and abnormal telomere structure in pathological shortening of telomeres, especially caused by loss-of-function telomerase mutations. Disrupted telomere structure caused by short telomeric overhangs may contribute to the mechanisms of abnormal haematopoietic compartment senescence and chromosomal instability in human bone marrow failure.     

10例获得性骨髓衰竭综合征患者端粒长度的检测

目的 探讨端粒酶基因突变与端粒长度变化间的关系.方法 收集来自北京协和医院、河北廊坊市中医院诊断明确的10例骨髓衰竭综合征患者外周血标本,提取有核细胞DNA,筛查TERC基因及TERT基冈的突变,Southern blot法测定患者端粒长度,并与2例血液系统恶性疾病患者及45名同龄健康对照者的端粒长度进行比较.结果 经基凶突变筛查,10例患者中2例携带端粒酶基因突变患者(其中1例为重型再生障碍性贫血,1例最终证实为先天性角化不良)端粒长度严重缩短,小于同龄正常对照长度的50%,与部分恶性血液病如骨髓增生异常综合征伴原始细胞增多(MDSRAEB Ⅱ)患者的端粒长度重叠,提示有恶性转化的可能.部分无突变的骨髓衰竭综合征患者端粒也有缩短,只有同龄正常对照长度的50%～80%,但缩短程度不及有突变者.结论 端粒酶基因突变患者端粒长度较同龄正常对照严重缩短(＜正常对照长度50%),提示可能为基因突变的结果 .部分无突变患者也存在端粒长度的缩短,但不及有突变者.     

慢性阻塞性肺疾病合并肺间质纤维化的临床研究

目的研究慢性阻塞性肺疾病（COPD）合并肺间质纤维化的临床特点及意义,并探讨其临床诊断要点.方法对近8年来临床确诊的36例COPD合并肺间质纤维化病例进行临床与影像学的回顾性分析研究,其中肺气肿合并肺纤维化11例,肺心病合并肺纤维化25例.结果 COPD合并肺间质纤维化的临床表现多数界于上述两种病变之间,胸部X线及CT兼具二者特点,肺纤维化病变在肺心病组多见.结论 COPD合并肺间质纤维化具有其独特的临床与影像学特征,其中临床症状及胸片是诊断的重要线索,高分辨率CT是临床确诊的最佳方法.     

PPARγ in emphysema: blunts the damage and triggers repair?

Cigarette smoke is the most common cause of pulmonary emphysema, which results in an irreversible loss of lung structure and function. Th1 and Th17 immune responses have been implicated in emphysema pathogenesis; however, the drivers of emphysema-associated immune dysfunction are not fully understood. In this issue of the JCI, Shan and colleagues found that peroxisome proliferator–activated receptor γ (PPARγ) is downregulated in APCs isolated from the lungs of emphysematous chronic smokers and mice exposed to cigarette smoke. Furthermore, treatment with a PPARγ agonist prevented emphysema development and appeared to reduce emphysema-associated lung volume expansion in mice exposed to cigarette smoke. Further work will need to be done to evaluate the potential of PPARγ agonists to restore lung capacity in emphysematous patients. Pulmonary emphysema is a major component of chronic obstructive pulmonary disease (COPD) and involves the loss of alveolar units distal to the terminal bronchioles. Even though COPD holds an unenviable position as the world’s fourth-leading cause of death, current medical interventions have little to offer beyond symptomatic relief. Meanwhile, the prevalence of COPD is expected to continue to rise as low- and middle-income countries join in the developed world’s tobacco addiction. If we are to avoid this grim projection, we must expand our knowledge of the basic mechanisms behind lung injury and repair before translating these findings into novel therapeutic treatments.     

Somatic reversion impacts myelodysplastic syndromes and acute myeloid leukemia evolution in the short telomere disorders

BACKGROUNDGermline mutations in telomerase and other telomere maintenance genes manifest in the premature aging short telomere syndromes. Myelodysplastic syndromes and acute myeloid leukemia (MDS/AML) account for 75% of associated malignancies, but how these cancers overcome the inherited telomere defect is unknown.METHODSWe used ultra-deep targeted sequencing to detect somatic reversion mutations in 17 candidate telomere lengthening genes among controls and patients with short telomere syndromes with and without MDS/AML, and we tested the functional significance of these mutations.RESULTSWhile no controls carried somatic mutations in telomere maintenance genes, 29% (16 of 56) of adults with germline telomere maintenance defects carried at least 1 (P < 0.001), and 13% (7 of 56) had 2 or more. In addition to TERT promoter mutations, which were present in 19%, another 13% of patients carried a mutation in POT1 or TERF2IP. POT1 mutations impaired telomere binding in vitro and some mutations were identical to ones seen in familial melanoma associated with longer telomere length. Exclusively in patients with germline defects in telomerase RNA (TR), we identified somatic mutations in nuclear RNA exosome genes RBM7, SKIV2L2, and DIS3, where loss-of-function upregulates mature TR levels. Somatic reversion events in 6 telomere-related genes were more prevalent in patients who were MDS/AML-free (P = 0.02, RR 4.4, 95% CI 1.2–16.7), and no patient with MDS/AML had more than 1 reversion mutation.CONCLUSIONOur data indicate that diverse adaptive somatic mutations arise in the short telomere syndromes. Their presence may alleviate the telomere crisis that promotes transformation to MDS/AML.FUNDINGThis work was supported by the NIH, the Commonwealth Foundation, the S&R Foundation Kuno Award, the Williams Foundation, the Vera and Joseph Dresner Foundation, the MacMillan Pathway to Independence Award, the American Society of Hematology Scholar Award, the Johns Hopkins Research Program for Medical Students, and the Turock Scholars Fund.     

Development of novel microarray methodology for the study of mutations in the SERPINA1 and ADRB2 genes—Their association with Obstructive Pulmonary Disease and Disseminated Bronchiectasis in Greek patients

ObjectivesThe aim of our study was to determine the genetic risk conferred by SNPs in the SERPINA1 and ADRB2 for development of Chronic Obstructive Pulmonary Disease (COPD) and Disseminated Bronchiectasis (DB), while at the same time validating the NanoChip technology. This was a case–control study consisting of 112 COPD, 62 DB patients and 2 control groups (106 smokers without COPD: healthy smokers control group and 205 general population subjects).Design and methodsThe novel methodology of the Nanogen NanoChip® 400 (NC400 Nanogen www.nanogen.com) was employed for genotyping five mutations/SNPs in the SERPINA1 and 2 in the ADRB2 gene.ResultsFor the SERPINA1 gene a statistically significant difference in the frequency was found for heterozygotes for p.V213A between DB patients and healthy smokers (44.1% vs. 26.4% respectively; p = 0.035) and for heterozygotes for c.1237G>A between DB patients and general population subjects (10.2% vs. 25.4% respectively; p = 0.023). There was a clustering of ADRB2 p.Gly16 homozygotes in patients with severe COPD (24/44, 54.5% with FEV₁ values <35% of predicted).ConclusionsThe SERPINA1 p.V213A polymorphism was found associated with DB risk while the ADRB2 p.G16R is a risk factor for severe COPD in smokers.     

Association between smoking behavior patterns and chronic obstructive pulmonary disease: a long-term follow-up study among Finnish adults

Low-rate smoking patterns are common, but their pulmonary effects remain poorly known. The study hypothesis was that any level of daily smoking may cause chronic obstructive pulmonary disease (COPD). We investigated the association between longitudinal smoking patterns and COPD using logistic regressions and survival models adjusted for multiple covariates. Data from Finnish Twin Cohort surveys were used. Participants (n = 21,609) were grouped into categories describing 1981 smoking and change in smoking during 1975-1981. Light smoking was defined as < 5 cigarettes per day, moderate 5-19 cigarettes, and heavy ≥ 20 cigarettes per day. Finland's Social Insurance Institution provided data on inhaled anticholinergics purchases (1995-2008) and diagnoses entitling to special reimbursements (1981-2008). We defined COPD as regular anticholinergic use or special reimbursement eligibility for COPD, emphysema, or chronic bronchitis. COPD incidence was 2.5% (n = 528). Elevated disease risks were observed in former, moderate, and heavy smokers, in all who increased smoking, and in those who reduced from moderate to light smoking. Increased risk for anticholinergic use was found in former smokers, in constant light, moderate, and heavy smokers, and in increasers. Former, light, moderate, and heavy smoking in 1981 was associated with future development of disease. Our results demonstrate that all daily smoking patterns may impair pulmonary function.     

慢性阻塞性肺疾病患者与肺功能正常吸烟者CT肺实质灌注成像对照

目的 分析慢性阻塞性肺疾病（COPD）患者及肺功能正常吸烟者CT肺实质灌注图像的差异。方法 对63例COPD患者及20名肺功能正常吸烟者（对照组）行肺CTPI,将COPD患者分为轻度亚组（16例）、中度亚组（18例）、重度亚组（11例）和极重度亚组（18例）,在肺叶水平计算灌注缺损区与正常区CT值比值（R_HU）,比较各组体质量指数（BMI）、吸烟量及各肺叶R_HU的差异。结果 对照组BMI与重度、极重度COPD亚组比较,对照组吸烟量与极重度COPD亚组比较差异均有统计学意义（P=0.006、0.002、0.007）。同组各肺叶R_HU差异均无统计学意义（P均>0.05）。对照组右肺下叶R_HU与重度、极重度COPD亚组差异有统计学意义（P=0.03、0.02）,其他各肺叶R_HU各组差异均无统计学意义（P均>0.05）。对照组与各COPD亚组R_HU差异均有统计学意义（P均<0.05）;轻度与重度、与极重度COPD亚组,中度与极重度COPD亚组R_HU差异均有统计学意义（P=0.022、0.001、0.003）。结论 R_HU可区分COPD和肺功能正常吸烟者,有可能成为评估COPD严重程度的指标之一。     

The mechanism of airway obstruction in the development of COPD

Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD) and it is generally accepted that proteinases released from neutrophils and/or macrophages are involved in the development of emphysema. It remained unknown why only a small portion of smokers develops clinically apparent emphysema and which cells and/or proteinases play a key role in the pathogenesis of COPD. Structural cells in the lungs such as epithelial cells and endothelial cells may also be involved in cell death and repair. Individual genetic background may regulate the function of these cells in response to cigarette smoke and is related to the susceptibility to pulmonary emphysema.     

Genetic risk factors for chronic obstructive pulmonary disease (COPD)]

Cigarette smoking has been shown to be a major environmental risk factor predisposing to the development of chronic obstructive pulmonary disease (COPD). However, only 10-20% of cigarette smokers develop COPD, implying undue susceptibility compared with the remainder of the population at large. Studies of families and twins suggest that genetic factors also contribute to development of COPD. We review the genes which have been investigated as potential risk factors for COPD. The fully established genetic risk factor is only alpha 1-antitrypsin deficiency. Polymorphisms for the genes including alpha 1-antichymotrypsin, vitamin D-binding protein, microsomal epoxide hydrolase, cytochrome P450 1A1, Glutathione S-transferase and immunoglobulin A, have also been associated with the development of COPD. Other genetic factors are likely involved but have not yet been identified. Elucidation of additional genetic risk factors may provide useful insights into the pathogenesis of COPD. Potential interactions between the various environmental and genetic risk factors may be important determinants in development of COPD.     

Definition of chronic obstructive pulmonary disease]

COPD is a disease manifested by a combination of chronic bronchitis and pulmonary emphysema. The main risk factors of COPD are chronic smoking and genetic dispositions. The current definition of COPD was established in Western countries in the late 1960s and 1970s, but in Japan COPD has long been used as a term for a physiological syndrome showing chronic obstructive airway symptoms including not only chronic bronchitis and pulmonary emphysema, but also asthma, diffuse panbronchiolitis, and even lymphangioleiomyomatosis. This difference in understanding between the West and Japan is probably due to the markedly lower incidence of COPD in Japan. However, increases in the number of patients with pulmonary emphysema from the late 1980s in Japan have been gathering new concern about COPD. In the governmental statistics for 1995, the term COPD was used for the same entity it is used in the West. Also, the Japanese COPD guideline, the definition of COPD is the same as that in the West.     

Impaired colony-forming capacity of circulating endothelial progenitor cells in patients with emphysema

Chronic obstructive pulmonary disease (COPD) is classified into emphysema and chronic bronchitis, which are thought to result from different pathophysiological pathways. Smoking-induced lung parenchymal destruction and inadequate repair are involved in the pathogenesis of emphysema. In addition, decreased expression of vascular endothelial growth factor and increased endothelial cell apoptosis in the lung may participate in emphysema pathogenesis. As stem cells, circulating endothelial progenitor cells (EPCs) may play a key role in the maintenance of vascular integrity by replacing and repairing the damaged endothelial cells in the tissues. To determine whether the lack of appropriate repair by circulating EPCs in cases of smoking-induced endothelial cell injury participates in emphysema pathogenesis, we determined the association between the colony-forming or migratory capacity of circulating EPCs and the presence of emphysema in 51 patients with COPD. The patients were divided into emphysema (n = 23) and non-emphysema groups (n = 28) based on high-resolution computed tomography. Twenty-two smokers with normal lung function and 14 normal non-smokers served as controls. Circulating EPCs isolated from patients with emphysema showed significantly lower colony-forming units (CFUs) than those from patients with non-emphysema group, smokers with normal lung function, and normal non-smokers. EPCs from patients with emphysema showed significantly lower migratory capacity than those from normal non-smoking controls (p < 0.05). On multivariate analysis, the EPC-CFU was independently associated with emphysema (OR 0.944, 95% CI = 0.903-0.987, p = 0.011). Thus, impaired functions of circulating EPCs may contribute to the development of emphysema.     

Single-cell analysis of somatic mutation burden in mammary epithelial cells of pathogenic BRCA1/2 mutation carriers

Inherited germline mutations in the breast cancer gene 1 (BRCA1) or BRCA2 genes (herein BRCA1/2) greatly increase the risk of breast and ovarian cancer, presumably by elevating somatic mutational errors as a consequence of deficient DNA repair. However, this has never been directly demonstrated by a comprehensive analysis of the somatic mutational landscape of primary, noncancer, mammary epithelial cells of women diagnosed with pathogenic BRCA1/2 germline mutations. Here, we used an accurate, single-cell whole-genome sequencing approach to first show that telomerized primary mammary epithelial cells heterozygous for a highly penetrant BRCA1 variant displayed a robustly elevated mutation frequency as compared with their isogenic control cells. We then demonstrated a small but statistically significant increase in mutation frequency in mammary epithelial cells isolated from the breast of BRCA1/2 mutation carriers as compared with those obtained from age-matched controls with no genetically increased risk for breast cancer.     

Oxidative stress in pathogenesis of COPD

Cigarette smoke and aging are major risk factors of chronic obstructive pulmonary disease(COPD). It remains unsolved how long -term smoking with age affects the molecular responses in the lung. Respiratory tract is the major interface to the environment and is rich in glutathione, which protects lung from oxidative stress. We performed bronchoalveolar lavage for nonsmokers and smokers of various ages, who were further categorized according to the presence of emphysema on high-resolution computed tomography. We thus evaluated glutathione antioxidant system in BAL fluid. Characterization of older smokers with long-term smoking histories, contrasted with young recent smokers, may in part explain the predisposition of the lungs to destructive lung diseases. On the other hands, oxidative stress results from an imbalance in aerobic metabolism and poses a serious threat to cellular apoptosis, leading to emphysematous lung destruction. The therapeutic interference with targeted up-regulation of protective mechanisms might be critical for the success of future COPD therapies.     

Clinical characteristics of COPD syndrome: A 6-year follow-up study of adult smokers

Abstract

Background. There is little quantitative information about the development of chronic obstructive pulmonary disease (COPD) among adult smokers and of what happens to patients who have already developed COPD.

Objectives. To examine the development and performance of COPD status over time, and the clinical characteristics of new COPD cases according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2007 and 2011 classifications.

Methods. Healthy asymptomatic smokers were recruited through newspaper announcements. They filled in questionnaires and had an individualized assessment of their health history during all three visits (visit 1, visit 2 after three years, visit 3 after six years).

Results. Of the eligible 621 heavy smokers, 572 attended visit 2. A total of 513 subjects completed the 6-year follow-up examination. According to GOLD 2007, COPD was present in 22.8% (n = 117) of these smokers. The severity of COPD changed during the years of follow-up. Furthermore, health status and prevalence of chronic respiratory symptoms both in the smokers with normal lung function and in the COPD groups varied over the time period.

Conclusions. GOLD 2011 recognized the complex patient subgroups better than GOLD 2007. Variability in chronic symptoms or in health status correlated poorly with the severity of airway limitation.     

Increased expression of vascular endothelial growth factor and hypoxia inducible factor-1α in lung tissue of patients with chronic bronchitis

ObjectivesVascular endothelial growth factor (VEGF) seems to be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD), but its site-specific expression in lung tissue and the relationship with hypoxia inducible factor-1 alpha (HIF-1α) expression in chronic bronchitis (CB) type COPD have not been studied.Design and methodsWe evaluated the expression of VEGF and its receptors in various compartments of lung tissue in three groups: non-smokers with normal lung function (non-smokers, n = 10), smokers without COPD (healthy smokers, n = 10) and smokers with CB (CB, n = 10), using immunohistochemical staining and Western blotting. The expression of HIF-1α was assessed by enzyme-linked immunosorbent assay.ResultsCompared with healthy smokers, VEGF expression in CB was significantly increased in bronchiolar epithelium, vascular endothelium and vascular smooth muscle (p < 0.05). VEGF receptor (VEGFR)-2 expression in CB was also increased in bronchiolar smooth muscle, vascular endothelium and vascular smooth muscle compared with healthy smokers (p < 0.05). The level of HIF-1α was increased in CB compared with healthy smokers and positively correlated with those of VEGF (r = 0.64, p < 0.05).ConclusionVEGF and VEGFR-2 expressions were up-regulated in CB and increased expression of VEGF was related with HIF-1α. HIF-1α-regulated VEGF overexpression may be a characteristic of chronic bronchitis.