Tumor necrosis factor-alpha gene polymorphism in chronic bronchitis

Contributing factors to the pathobiology. The genetics of asthma

Markers in 19 chromosomal regions have shown some evidence of linkage to asthma, atopy, or related phenotypes in multiple independent genome-wide searches. Linkages to five of these regions (5q, 6p, 11q, 12q, and 13q) have also been reported in non-genome-wide screens. In addition, at least two independent studies have reported linkages to markers on 16p. Numerous candidate genes in these regions have shown varying levels of association to asthma or atopic phenotypes, potentially implicating them as disease susceptibility loci. These include the IL4, CD14, and B2ADR genes on 5q, the HLA-DRB1 and TNF genes on 6p, the FCERB1 and CC16 genes on 11q, and the IL4RA gene on 16p. It still remains to be determined whether polymorphisms in these genes account for the reported linkages in these regions. Studies are underway in laboratories around the world to identify the disease-causing variations in these genes that account for the linkages just discussed. Identifying specific genetic polymorphisms that influence asthma and atopic phenotypes will shed light on the molecular pathways involved in these complex disorders and provide a better understanding of the pathophysiology of asthma and atopy.

Tumor necrosis factor gene complex in COPD and disseminated bronchiectasis

BACKGROUND

Tumor necrosis factor (TNF) is a potent proinflammatory cytokine with increased levels in the sputum of COPD subjects. Two biallelic TNF gene complex polymorphisms have been described: LtalphaNcoI, in the first intron of the lymphotoxin alpha (previously referred to as TNF-beta) gene, and TNF-308, in the promoter region of the TNF-alpha gene. Higher levels of TNF production are associated with allele 1 of LtalphaNcoI (LtalphaNcoI*1) and with allele 2 of TNF-308 (TNF-308*2).

STUDY OBJECTIVES

To study the frequencies of the two TNF gene complex polymorphisms in patients with COPD and bronchiectasis.

DESIGN

Association study.

SUBJECTS AND METHODS

We studied the frequencies of these polymorphisms in 66 subjects with COPD and in 23 subjects with disseminated bronchiectasis and compared them to the frequencies in 98 healthy control subjects and 45 subjects with nonobstructive pulmonary disease. Genomic DNA samples were extracted, and TNF-alpha and LtalphaNcoI polymorphisms were detected after polymerase chain reaction by restriction digestion.

RESULTS

We found the following frequencies: the TNF-308*2 allele was detected in 11% of COPD individuals, 15% of bronchiectasis patients, 10% of healthy control subjects, and 18% of subjects with nonobstructive pulmonary disease. The LtalphaNcoI*1 allele was detected in 28% of COPD individuals, 30% of bronchiectasis patients, 29% of healthy control subjects, and 29% of subjects with nonobstructive pulmonary disease. We found evidence of linkage disequilibrium between the two loci (Delta = 0.068).

CONCLUSIONS

We conclude that the TNF gene complex, at least in Caucasoid individuals and for the considered polymorphisms, does not seem to play a major role as genetic risk factor in COPD and bronchiectasis.

Oxidants/antioxidants and COPD

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants and/or a depletion of antioxidants. Oxidative stress is thought to play an important role in the pathogenesis of a number of lung diseases, not only through direct injurious effects, but by involvement in the molecular mechanisms that control lung inflammation. A number of studies have shown an increased oxidant burden and consequently increased markers of oxidative stress in the airspaces, breath, blood, and urine in smokers and in patients with COPD. The presence of oxidative stress has important consequences for the pathogenesis of COPD. These include oxidative inactivation of antiproteinases, airspace epithelial injury, increased sequestration of neutrophils in the pulmonary microvasculature, and gene expression of proinflammatory mediators. With regard to the latter, oxidative stress has a role in enhancing the inflammation that occurs in smokers and patients with COPD, through the activation of redox-sensitive transcriptions factors such as nuclear factor-kappaB and activator protein-1, which regulate the genes for proinflammatory mediators and protective antioxidant gene expression. The sources of the increased oxidative stress in patients with COPD are derived from the increased burden of oxidants present in cigarette smoke, or from the increased amounts of reactive oxygen species released from leukocytes, both in the airspaces and in the blood. Antioxidant depletion or deficiency in antioxidants may contribute to oxidative stress. The development of airflow limitation is related to dietary deficiency of antioxidants, and hence dietary supplementation may be a beneficial therapeutic intervention in this condition. Antioxidants that have good bioavailability or molecules that have antioxidant enzyme activity may be therapies that not only protect against the direct injurious effects of oxidants, but may fundamentally alter the inflammatory events that play an important part in the pathogenesis of COPD.

Two polymorphisms of the tumour necrosis factor gene do not influence survival in pancreatic cancer

Polymorphisms of the tumour necrosis factor (TNF) gene have been related to TNF production and outcome in a variety of inflammatory and malignant diseases. Proinflammatory cytokines and the inflammatory state appear to affect outcome in pancreatic cancer. Thus, the present study examined the TNFB and TNF-308 polymorphisms for their relationship to the inflammatory state and survival in pancreatic cancer. Sixty-four patients with advanced pancreatic cancer and 101 healthy subjects were genotyped for each polymorphism. Serum concentrations of the two TNF receptors and C-reactive protein (CRP) were measured in 45 of the cancer patients with no evidence of infection or jaundice, 1 month after surgical intervention. There was no difference in distribution of genotypes between the patient and control groups. There was no association between any genotype and concentrations of any of the measured inflammatory mediators. While those with an elevated CRP concentration had significantly poorer survival, there was no association between either TNF genotype and survival. This study found no association between TNF genotype and the inflammatory state or survival in advanced pancreatic cancer. Other cytokines may be more important than TNF in determining the inflammatory state and disease progress in pancreatic cancer.

Glutathione S-transferase P1 (GSTP1) polymorphism in patients with chronic obstructive pulmonary disease

BACKGROUND

Enzymes that contribute to the local detoxification in alveoli and bronchioles have an important role in the defence mechanism against tobacco smoke. It has been suggested that genetic susceptibility to smoking injury may confer a risk for the development of chronic obstructive pulmonary disease (COPD). The polymorphisms in glutathione S-transferase P1 (GSTP1), a xenobiotic metabolising enzyme, were investigated in patients with COPD.

METHODS

Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were performed to genotype GSTP1 polymorphisms in exon 5 (Ile105Val) and exon 6 (Ala114Val). Blood samples were taken from 53 patients with COPD and 50 control subjects at the Tokyo University Hospital, the Juntendo University Hospital, and the Tokyo Kenbikyoin Clinic for use in the study.

RESULTS

The proportion of GSTP1/Ile105 homozygotes was significantly higher in the patients with COPD than in the control subjects (79% vs 52%). The odds ratio for GSTP1/Ile105 homozygotes versus all other genotypes was 3.5 (95% CI 2.7 to 4.6) for COPD. Polymorphism at residue 114 of GSTP1 was not found in either group.

CONCLUSIONS

Genetic polymorphism of exon 5 of GSTP1 may be associated with COPD because the GSTP1/Ile105 genotype is predominantly found in COPD. It is suggested that the GSTP1/Ile105 genotype may be less protective against xenobiotics in tobacco smoke.

The tumor necrosis factor-alpha promoter correlates with progression of primary biliary cirrhosis

BACKGROUND/AIMS

There have been many studies attempting to identify genes that determine susceptibility to primary biliary cirrhosis (PBC), but few studies have attempted to define the genes that modulate the natural history of the disease. There is a biallelic polymorphism, coined TNF1 and TNF2, in the TNFalpha promoter region at -308. We investigated the relative frequency of the TNF1 and TNF2 alleles in patients with PBC, based on the hypothesis that a polymorphism of the TNFalpha promoter region may be associated with the rate of progression and prognosis of PBC.

METHODS

Seventy-one Caucasoid patients with PBC and 133 healthy and unrelated Caucasoid individuals were studied. Genomic DNA was extracted from blood, and the mutation at position -308 of the TNFalpha gene analyzed by PCR and NcoI digestion.

RESULTS

In 71 patients with PBC, 56/71 (78.9%) patients were TNF1/TNF1 homozygotes, 14/71 (19.7%) were TNF1/TNF2 heterozygotes and 1/71 (1.4%) were TNF2/TNF2 homozygotes. In 133 healthy individuals, 109/133 (80.5%) patients were TNF1/TNF1 homozygotes, 24/133 (18%) were TNF1/TNF2 heterozygotes. No control individuals were TNF2/TNF2 homozygotes. The difference between the two groups was not statistically significant (p = 0.3684). However, in patients with TNF1/TNF1 the Mayo score for disease severity was 4.596+/-0.157 (mean +/- SEM), compared to 5.637+/-0.420 for patients with TNF1/TNF2. This Mayo score was significantly higher in patients with the TNF1/TNF2 genotype than those with TNF1/TNF1 (p = 0.0140), with an odds ratio of 4.9.

CONCLUSIONS

Our data demonstrate that the presence of the TNF2 allele may be associated with a higher Mayo score, and thus with patients in a more advanced clinical stage. These data have both theoretical and clinical implications.

The genetic basis for the association of the 8.1 ancestral haplotype (A1, B8, DR3) with multiple immunopathological diseases

An individual's major histocompatibility complex (MHC) ancestral haplotype (AH) is the clearest single determinant of susceptibility to MHC associated immunopathological disease, as it defines the alleles carried at all loci in the MHC. However, the direct effects of any of the 150-200 genes that constitute the MHC are difficult to determine since recombination only occurs at defined hotspots. This review concerns the 8.1 AH (HLA-A1, C7, B8, C4AQ0, C4B1, DR3, DQ2), which is carried by most Caucasians with HLA-B8. It is associated with accelerated human immunodeficiency virus (HIV) disease, and susceptibility to insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, dermatitis herpetiformis, common variable immunodeficiency and IgA deficiency, myasthenia gravis and several other conditions. We have mapped susceptibility genes for HIV, IDDM and myasthenia gravis to the central MHC between HLA-B and the tumour necrosis factor or complement genes. Here we consider which of the remaining 8.1-associated diseases are more closely associated with HLA-DR3 and/or DQ2. Several candidate genes in the central MHC have the potential to modulate immune or inflammatory responses in an antigen-independent manner, as is seen in studies of cultured cells from healthy carriers of the 8.1 AH. Hence these genes may act as a common co-factor in the diverse immunopathological conditions associated with the 8.1 AH.

Contribution of genetic factors other than CFTR to disease severity in cystic fibrosis

BACKGROUND

Disease severity in patients with cystic fibrosis shows marked variability. Attempts to explain this phenotypic heterogeneity on the basis of CFTR genotype have had limited success. A study was undertaken to test the hypothesis that naturally occurring variants of the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha) and the detoxifying enzyme glutathione S-transferase M1 (GSTM1) could influence disease severity in cystic fibrosis.

METHODS

Fifty-three children with cystic fibrosis were studied. To allow for the effect of age, all clinical details were collected during the eighth year of age. The subjects were divided into groups, both according to the presence or absence of the TNF2 TNF-alpha -308 promoter polymorphism (n = 20), and by homozygosity for the null allele of GSTM1 (n = 26).

RESULTS

Percentage predicted forced expiratory volume in one second (FEV1) and weight z scores were significantly lower in the TNF2 group (mean difference (95% confidence intervals) for FEV1 11.6% (1.7 to 21.5) and 0.59 (0.06 to 1.12) for weight z score). The Chrispin-Norman chest radiographic score was significantly higher and the Shwachman score was significantly lower in patients homozygous for the GSTM1 null allele.

CONCLUSIONS

Two independent genetic factors have been identified which appear to influence disease severity in cystic fibrosis. These results support the contention that inflammation in cystic fibrosis contributes to tissue damage. Isolation of further such factors may lead to identification of patients at risk of more severe disease and allow targeted aggressive therapy in this group.

Pharmacologic adjuncts to mechanical ventilation in acute respiratory distress syndrome

This article reviews pharmacologic approaches to treating acute respiratory distress syndrome (ARDS). The authors discuss the therapeutic effects of ketoconazole, antioxidants, corticosteroids, surfactant, ketanserin, pentoxifylline, bronchodilators, and almitrine in ARDS. Current animal data and proposed mechanics which may foster future pharmacologic therapies are also examined.

Genes, oxidative stress, and the risk of chronic obstructive pulmonary disease

BACKGROUND

The first-pass metabolism of foreign compounds in the lung is an important protective mechanism against oxidative stress. We investigated whether polymorphisms in the gene for microsomal epoxide hydrolase (mEPHX), an enzyme involved in this protective process, had any bearing on individual susceptibility to the development of chronic obstructive pulmonary disease (COPD) and emphysema.

METHODS

We designed PCR-based genotyping assays to detect variant forms of mEPHX that confer slow and fast activity. We used these assays to screen 203 blood-donor controls and groups of patients with asthma (n = 57), lung cancer (n = 50), COPD (n = 68), and emphysema (n = 94), who were attending specialised clinics in Edinburgh, UK.

FINDINGS

The proportion of individuals with innate slow mEPHX activity (homozygotes) was significantly higher in both the COPD group and the emphysema group than in the control group (COPD 13 [19%] vs control 13 [6%]; emphysema 21 [22%] vs 13 [6%]). The odds ratios for homozygous slow activity versus all other phenotypes were 4.1 (95% CI 1.8-9.7) for COPD and 5.0 (2.3-10.9) for emphysema.

INTERPRETATION

Genetic polymorphisms in xenobiotic enzymes may have a role in individual susceptibility to oxidant-related lung disease. Epoxide derivatives of cigarette-smoke components may be the cause of some of the lung damage characteristics of these diseases.