This study included two independent study populations. The main study population was the Finnish Environment and Asthma Study (FEAS) led by Professor Maritta Jaakkola. FEAS, with 1453 participants, is one of the largest studies in the world focusing on determinants of adult-onset asthma. The other study population was Cold, Infections and Asthma in Soldiers study (CIAS), that included 892 military conscripts.
IL-6 is a cytokine that has been suggested to participate in the pathogenesis of asthma. Many types of cells produce IL-6 as a response to different stressors and damaging agents, including tobacco smoke. IL6 polymorphisms have previously been associated with the risk of asthma especially in adults, but so far the results have been conflicting. In addition, previous studies have reported interaction between IL6 gene and tobacco smoking on the risk of diseases other than asthma, for example on cardiovascular diseases.
In this study, the researchers observed a synergistic effect of IL6 gene and tobacco smoking on the risk of developing asthma. An association between the studied IL6 polymorphism and asthma was observed among those who were either current smokers or previous smokers, but not among the never-smokers. The results were similar also in another, independent study population that included military conscripts, as well as in the combined analysis of the two studies. In the combined analysis, a 1.8 fold increase in the risk of asthma due to smoking exposure was observed among the carriers of the genotype GG, when compared to the carriers of the other genotypes.
In this study an increased risk of asthma due to smoking was observed especially among carriers of the IL6 GG genotype, which implies that these individuals are especially susceptible to the adverse effects of tobacco smoking. However, smoking is never recommended, since previous studies have indicated joint effects of other IL6 genotypes and smoking on several chronic diseases.
The Finnish Environment and Asthma Study has been funded by the Academy of Finland and by the Ministry of Social Affairs and Health. The Cold, Infections and Asthma in Soldiers study was partly supported by the Scientific Advisory Board for Defense (MATINE) of the Ministry of Defense of Finland. The results were published at 5th October 2017 in The Journal of Allergy and Clinical Immunology that is the leading journal in the field of allergology and immunology.
Lajunen TK, Jaakkola JJK, Jaakkola MS. Interleukin 6 polymorphisms modify the effects of smoking on the risk of adult asthma. J Allergy Clin Immunol. 2017 Oct 5.
Taina Lajunen, Adjunct professor (Docent of public health), Center for Environmental and Respiratory Health Research (CERH), Faculty of Medicine, University of Oulu
email: email@example.com, tel. +358 40 6724 478
Jouni J. K. Jaakkola, Professor of public health, director, Center for Environmental and Respiratory Health Research (CERH), Faculty of Medicine, University of Oulu
email: firstname.lastname@example.org, tel. +358 40 6720 927, www.oulu.fi/cerh
Last updated: 8.11.2017