Telomere biology, especially tissue-specific ultra-short telomeres, might provide a strong contribution to our current knowledge in COPD development as well as a predictive marker for prognosis. To test this hypothesis, we investigated telomere lengths in lung tissue and leukocytes in patients diagnosed with COPD.
Thirty-two patients were included in the current study. All patients showed a post-bronchodilator ratio of less than 70% post-bronchodilator predicted value of forced expiratory volume in second (FEV1%), mean 56%; range [19% to 86%]. To be able to investigate ultra-short telomeres, universal single telomere length analysis (U-STELA) was used.
Our results showed a higher level of the ultra-short telomere presence in bronchoalveolar lavage (BAL) cells when compared to leukocytes with statistical significance t(62)=5.771, p<0.00001. The FEV1% was lower in subjects with ultra-short telomeres in BAL (50.6% vs 81.6%: p<0.001) and in ultra-short telomeres in blood leukocytes (37.3% vs 58.5%: p=0.051) when compared to subjects without ultra-short telomeres in leukocytes. Furthermore, the patients who had ultra-short telomeres in BAL samples were significantly older (p=0.014) than patients who did not have ultra-short telomeres. Ultra-short telomeres in BAL (p=0.05) but not in leukocytes (p=0.33) were associated with FEV1% in a regressions model adjusting for age (p<0.0001), ever smoking (p<0.0001) and sex (p=0.71). The patients with ultra-short telomeres were graded higher in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification (p=0.006).
This study emphasizes the need to investigate the correct tissue to get a representative evaluation of the stage or advancedness of COPD. To our knowledge, this is the first study to show that there is a correlation between the presence of ultra-short telomeres in lung tissue and COPD severity. Our results suggest that ultra-short telomeres are involved in the molecular pathogenesis of COPD and might be used as a tissue-specific predictive biomarker.