Sex hormones and systemic inflammation are modulators of the obese‐asthma phenotype

H A Scott, P G Gibson, M L Garg, J W Upham, L G Wood

Both systemic inflammation and sex hormones have been proposed as potential mediators of the obese-asthma phenotype. The aim of this study was to examine the associations between sex hormones, oral contraceptive pill (OCP) use, systemic inflammation and airway inflammation in adults with asthma. Obese (n=39) and non-obese (n=42) females and obese (n=24) and non-obese (n=25) males with asthma were recruited. Females were further categorised as reproductive aged (<50 years old; n=36) or older (>50 years old; n=45). Thirteen (36.1%) reproductive aged females were using the OCP. Participants had induced sputum cell counts measured and blood analysed for sex hormones and inflammatory markers. Obese reproductive aged females had higher sputum %neutrophils than non-obese reproductive aged females (45.4±24.3% vs 27.5±17.5%, p=0.016); however, there was no difference in sputum neutrophils in obese compared with non-obese males (p=0.620) or older females (p=0.087). Multiple linear regression found testosterone and OCP use to be negative predictors of sputum %neutrophils, while CRP and IL-6 were positive predictors of sputum %neutrophils. BMI and age were not significant predictors in the multivariate model. Reproductive aged females using the OCP had significantly lower sputum %neutrophils than those not using the OCP (23.2±12.6% vs 42.1±23.8, p=0.015). This study suggests that sex hormones and systemic inflammation may be mediating the obese-asthma phenotype. The observation that OCP use was associated with lower sputum %neutrophils in reproductive aged females warrants further investigation. This article is protected by copyright. All rights reserved.