Comparison of airway cellular and mediator profiles between tobacco smoke-induced COPD and biomass fuel exposure-induced COPD in an Indian population

Exposure to biomass fuel smoke is as an important risk factor for COPD (BS-COPD), but it is not known whether this phenotype is different from tobacco-smoke induced TS-COPD with reference to airway cellular and mediator profiles. Aim: To compare cellular and mediator inflammatory profiles in induced sputum between BS-COPD, TS-COPD and healthy controls. Methods: 15 subjects with BS-COPD (mean exposure 43 yrs), 30 subjects with TS-COPD (mean 43 pack yrs) and 13 healthy subjects underwent sputum induction with 3% saline. Sputum was processed with 0.1% DTT. Cytospin slides were prepared and stained with diff-quick satins, and inflammatory cells were identified and counted under light-microscope. IL8, IL6, MMP-9, 8-isoprostane and LTB4 in the induced sputum were measured using ELISA. Mann-Whitney and Kruskal-Wallis tests were used for inter-group comparisons of medians (inter-quartile range). Results: Compared with healthy subjects, both BS-COPD and TS-COPD subjects showed increased sputum neutrophil counts (p=0.05 & p=0.01 respectively) and eosinophil counts (p<0.0001 and p<0.0001 respectively). Both BS-COPD and TS-COPD showed increased levels of IL-8 (p<0.001 and p<0.0001 respectively), MMP-9 (p=0.004 and p=0.001) and 8-isoprostane (p=0.002 and p=0.007) levels compared to healthy subjects. There were no differences in the cellular and mediator inflammatory profiles between BS-COPD and TS-COPD. Conclusion: BS-COPD showed increased numbers of neutrophils and eosinophils in the induced sputum, which was accompanied by increased levels of IL8, 8-isoprostane and MMP-9 levels, and these levels did not differ with TS-COPD.