Genetic loci influencing lung function: a genome-wide scan in the Framingham Study

Mannose-binding lectin gene polymorphism predicts hospital admissions for COPD infections

Infection frequently causes exacerbations of chronic obstructive pulmonary disease (COPD). Mannose-binding lectin (MBL) is a pattern-recognition receptor that assists in clearing microorganisms. Polymorphisms in the MBL2 gene reduce serum MBL levels and are associated with risk of infection. We studied whether the MBL2 codon 54 B allele affected serum MBL levels, admissions for infective exacerbation in COPD and disease susceptibility. Polymorphism frequency was determined by PCR-RFLP in 200 COPD patients and 104 smokers with normal lung function. Serum MBL was measured as mannan-binding activity in a subgroup of 82 stable COPD patients. Frequency of COPD admissions for infective exacerbation was ascertained for a 2-year period. The MBL2 codon 54 B allele reduced serum MBL in COPD patients. In keeping, patients carrying the low MBL-producing B allele had increased risk of admission for infective exacerbation (OR 4.9, P(corrected)=0.011). No association of MBL2 genotype with susceptibility to COPD was detected. In COPD, serum MBL is regulated by polymorphism at codon 54 in its encoding gene. Low MBL-producing genotypes were associated with more frequent admissions to hospital with respiratory infection, suggesting that the MBL2 gene is disease-modifying in COPD. MBL2 genotype should be explored prospectively as a prognostic marker for infection risk in COPD.

Approaches to slowing the progression of COPD

Chronic obstructive pulmonary disease (COPD) is a major health problem across the world and its medical, societal and economic impacts continue to grow. There are several hypotheses regarding the pathogenesis of COPD and important new information on airway inflammation, oxidative stress and proteolysis in the lungs that are important for the development of effective treatments. The differences in susceptibility to COPD among cigarette smokers and the common familial risk of developing disease point to important genetic influences. The identification of candidate gene loci and various gene polymorphisms have improved our understanding of the mechanisms by which genetic factors predispose for COPD. The beneficial effects of smoking cessation in slowing the decline in lung function and the progression of disease have been clearly established. Whether other factors such as mucus hypersecretion, respiratory infections and airway hyperreactivity contribute to disease progression independent of cigarette smoking is still being debated. There is new interest in dietary strategies to prevent or control COPD and preliminary information suggesting the usefulness of diets favoring antioxidant-rich foods. On the other hand several large, long-term, randomized, controlled clinical trials have failed to show a beneficial effect of either anticholinergics or corticosteroids in slowing the rate of decline in lung function in COPD. Corticosteroid treatment, however, appears to reduce the frequency of COPD exacerbations and there is some suggestion that it may also reduce the risk of death in patients with severe COPD.