Body mass index is associated with reduced exhaled nitric oxide and higher exhaled 8-isoprostanes in asthmatics

BACKGROUND: Recently, it has been shown that increasing body mass index (BMI) in asthma is associated with reduced exhaled NO. Our objective in this study was to determine if the BMI-related changes in exhaled NO differ across asthmatics and controls, and to determine if these changes are related to increased airway oxidative stress and systemic levels of leptin and adiponectin. METHODS: Observational study of the association of BMI, leptin, and adiponectin with exhaled nitric oxide (NO) and exhaled 8-isoprostanes in 67 non-smoking patients with moderate to severe persistent asthma during baseline conditions and 47 controls. Measurements included plasma levels of leptin, adiponectin, exhaled breath condensates for 8-isoprostanes, exhaled NO, pulmonary function tests, and questionnaires regarding asthma severity and control. RESULTS: In asthmatics, BMI and the ratio of leptin to adiponectin were respectively associated with reduced levels of exhaled NO (β = -0.04 [95% C.I. -0.07, -0.1], p < 0.003) and (β = -0.0018 [95% C.I. -0.003, -0.00034], p = 0.01) after adjusting for confounders. Also, BMI was associated with increased levels of exhaled 8-isoprostanes (β = 0.30 [95% C.I. 0.003, 0.6], p = 0.03) after adjusting for confounders. In contrast, we did not observe these associations in the control group of healthy non-asthmatics with a similar weight distribution. CONCLUSION: In adults with stable moderate to severe persistent asthma, but not in controls, BMI and the plasma ratio of leptin/adiponectin is associated with reduced exhaled NO. Also, BMI is associated with increased exhaled 8-isoprostanes. These results suggest that BMI in asthmatics may increase airway oxidative stress and could explain the BMI-related reductions in exhaled NO

Broncoespasmo induzido pelo exercício em adolescentes asmáticos obesos e não-obesos Exercise-induced bronchospasm in obese and non-obese asthmatic adolescents

OBJETIVO: Avaliar e comparar a frequência e intensidade do broncoespasmo induzido pelo exercício (BIE) em adolescentes asmáticos obesos e não-obesos. MÉTODOS: Estudo transversal e descritivo realizado com 39 adolescentes de ambos os sexos, com idade entre dez e 16 anos, divididos em dois grupos conforme o histórico clínico de asma e/ou rinite alérgica e o índice de massa corporal: asmáticos obesos (n=18); asmáticos não-obesos (n=21). Utilizou-se o teste de broncoprovocação com exercício para a avaliação do BIE, considerando-se positiva uma diminuição do volume expiratório forçado no primeiro segundo (VEF1) >15% do valor pré-exercício. Para avaliar a intensidade e a recuperação do BIE, foram calculadas a queda percentual máxima do VEF1 (QM%VEF1) e a área acima da curva (AAC0-30). A análise estatística utilizou o teste exato de Fischer para comparar a frequência de BIE e o teste de Mann-Whitney para a intensidade e recuperação. Rejeitou-se a hipótese de nulidade se p<0,05. RESULTADOS: Não houve diferença significativa na frequência de BIE entre os grupos de asmáticos obesos (50%) e não-obesos (38%). Entretanto, a queda máxima do VEF1 e a AAC0-30 foram maiores nos asmáticos obesos em comparação aos não-obesos (respectivamente 37,7% e 455 versus 24,5% e 214, p<0,03). CONCLUSÕES: A obesidade não contribuiu para o aumento da frequência do BIE em asmáticos e não-asmáticos, entretanto, a obesidade contribuiu para o aumento da intensidade e do tempo de recuperação da crise de BIE em asmáticos<br>OBJECTIVE: To assess and compare the frequency and severity of exercise-induced bronchospasm (EIB) in obese and non-obese asthmatic adolescents. METHODS: Cross-sectional and descriptive study with 39 subjects aged ten to 16 years of both genders divided into two groups according to clinical history of asthma and/or allergic rhinitis and body mass index, as follows: asthmatic obese (n=18) and asthmatic non-obese (n=21). An exercise bronchoprovocation test was applied to diagnose EIB and was considered positive if the forced expiratory volume in one second (FEV1) decreased >15% in relation to pre-exercise FEV1. Maximum percent of fall in FEV1 (MF%FEV1) and the area above the curve (AAC0-30) were calculated to evaluate the intensity and recovery of EIB. Fisher exact test was used to compare the frequency of EIB and Mann-Whitney test to compare the severity and recovery of EIB. Null hypothesis was rejected when p<0.05. RESULTS: No significant difference was found in the frequency of EIB between the asthmatic obese (50%) and non-obese (38%) adolescents. However, the MF%FEV1 and AAC0-30 were significantly higher in the asthmatic obese as compared to the asthmatic non-obese patients (respectively, 37.7% and 455 versus 24.5% e 214, p<0.03). CONCLUSIONS: Obesity did not contribute to the increase of the frequency of EIB in asthmatic and non-asthmatic patients. However, obesity contributed to the increase of severity and recovery time of EIB in asthmatic