COPD, or chronic obstructive pulmonary disease, results in severe breathing difficulty and is the fourth leading killer worldwide, according to World Health Organization (WHO). Yet the progression of the disease in smoking induced COPD, is not the same in all smokers, a new study has found.
However, the mechanisms responsible for some smokers developing COPD and others evading the disease have not been well understood.
Scientists say that an autoimmune mechanism, compounded by genetic predisposition in COPD, would explain the progression of the disease in some smokers and the evasion in others.
COPD has a family connection and next of kin of patients with COPD have a much higher chance of developing the disease, a characteristic of autoimmune diseases.
Although smoking is the primary risk factor for COPD in the western world, open fire pollutant cooking and heating fuels in the home is an important risk factor for the development of COPD in women in developing nations.
"Smoke can play an important role in autoimmune diseases such as COPD, and other diseases like rheumatoid arthritis, because it accentuates genetic predispositions to the disease," said Dr.Manuel Cosio from the McGill University Health Centre, who conducted the study in collabration with Italian and Spanish scientists.
Yet contrary to previous scientific beliefs, COPD does not progress in the same way in all smokers.
The authors describe three steps in the potential progression to COPD in smokers: "COPD does not go from stage one, two and three in all people. Depending on their personal balance between immune response and immune control some people would stop at stage one, others at stage two, and some will progress to stage three, full autoimmunity and lung destruction."
"Hopefully investigators will now see the disease in a totally different way. Our hope is that our research will open the door for a different investigation on COPD, where scientists learn more about the immunological processes and how these processes could be controlled and modulated to eventually provide the right treatment," Dr Cosio added.
The study is published in the New England Journal of Medicine.