Genes, environment are factors in smokers’ illness
Four in 10 Greek smokers are threatened with chronic obstructive pulmonary disease (COPD), which kills about 3 million people around the world every year. About 450 million people are estimated to suffer from this disease, also known as smokers’ cough. In Greece, it affects 8.5 percent of the adult population. Smoking is the main cause and quitting is the only way to prevent it, but not all smokers are at risk. Scientists, led by Greek researchers from the University of Crete, have been studying the genetic basis of the disease for the purpose of developing a test to find out which smokers are at risk. Professor Nikos Siafakas is head of the Greek Pulmonary Association, a professor at the University of Crete and the director of the Iraklion University Hospital’s pulmonary clinic, where important research has been carried out over the past few years into COPD. «One aspect of the research concerns exploring the disease’s pathogenic mechanism, since we know the cause and the result but we don’t know all the stages, that is, how smoking leads to COPD,» Siafakas said. According to Siafakas, research has shown that the disease is inflammatory in the sense that the lung is «burned» by the smoke. In its effort to react to the condition, the body activates its defense mechanism, which turns against the lungs. «Our clinic has traced certain lymph cells called CD-8, which are particularly toxic and are activated by smoking to destroy the lung itself,» he said. «In addition, we have shown that if a person suffering from COPD contracts an infection, these cells multiply considerably and become more toxic. That is why we advise all patients with COPD to be vaccinated against influenza.» Still, Siafakas says the question remains as to why not all smokers contract COPD. The answer, he said, lies in the genetic makeup of each person. About 20 percent of smokers are expected to contract the disease. «Exploring the genetic basis of the disease comprises the second aspect of our clinic’s research,» he said. «We have already found certain genetic indicators typical of the disease, which are found in smokers who developed COPD, but not among other smokers. Those indicators led us to specific genes that activate the disease, but also to genes that provide protection from it. The next stage is to examine genetic material from populations of other European countries to see whether the same mechanisms apply. Our eventual goal is to develop a test to determine which smokers are more at risk from COPD.» «Naturally that does not mean that we should lose sight of the goal of getting people to stop smoking,» Siafakas emphasized. The Greek Pulmonary Association recently carried out a major epidemiological study that showed 8.5 percent of Greek adults suffered from COPD, a figure that is considerably low on the international scale of 7-15 percent. «When we began the study, given that a major percentage of Greeks smoke (40 percent are smokers), we thought that the occurence of the disease would be over 15 percent,» said the professor. Some of the most likely explanations for this are either that Greeks are genetically «advantaged» compared to other populations, or because of the high consumption of fresh fruit and fruit juices – especially oranges – and vegetables. Also, Greeks tend to smoke outdoors a lot, since the weather can be mild during all seasons. That means smokers don’t keep breathing in the smoke, as is the case indoors, and those around them do not take in second-hand smoke. This appears to be supported by the fact that rural residents who spend several hours inside smoky cafes have a greater incidence of COPD. Siafakas says there is no safety limit for the amount of smoke a person can inhale, and, therefore, the number of cigarettes he or she can smoke, in order to avoid COPD. A smoker should quit the habit at the first sign of COPD symptoms – a chronic cough accompanied by phlegm. At this stage, the lung still has the capacity to regain its health.