Asthma and metabolic syndrome: Current knowledge and future perspectives

Abstract

Asthma and obesity are epidemiologically linked; however, similar relationships are also observed with other markers of the metabolic syndrome, such as insulin resistance and dyslipidemia, which cannot be accounted for by increased body mass alone. Obesity appears to be a predisposing factor for the asthma onset, both in adults and in children. In addition, obesity could make asthma more difficult to control and to treat. Although obesity may predispose to increased Th2 inflammation or tendency to atopy, other mechanisms need to be considered, such as those mediated by hyperglycaemia, hyperinsulinemia and dyslipidemia in the context of metabolic syndrome. The mechanisms underlying the association between asthma and metabolic syndrome are yet to be determined. In the past, these two conditions were believed to occur in the same individual without any pathogenetic link. However, the improvement in asthma symptoms following weight reduction indicates a causal relationship. The interplay between these two diseases is probably due to a bidirectional interaction. The purpose of this review is to describe the current knowledge about the possible link between metabolic syndrome and asthma, and explore potential application for future studies and strategic approaches.

Impaired glucose metabolism and bronchial hyperresponsiveness in obese prepubertal asthmatic children

“…Normality in distributions was either confirmed or rejected using the Kolmogorov-Smirnov or the Shapiro-Wilk tests, appropriately. A linear logistic regression model was used for the assessment of the impact of independent variables on PD 15 . Data are presented as mean values AE standard deviations unless otherwise stated.…”

“…The test was performed through inhalation of gradually increasing quantity of dry powder mannitol and FEV 1 was measured after each inhalation. The PD 15 index was used for the quantitative measurement of BHR, expressing the amount of inhaled dry powder mannitol, necessary to achieve a 15% decrease of FEV 1, compared to the baseline, or a 10% decrease between two consecutive measurements. 23 The value of PD 15 was automatically calculated, using appropriate software provided by the manufacturer (PD 15 Calculator for Aridol Bronchial Challenge test kit, Pharmaxis, Frenchs Forest, Australia).…”

“…In this aspect, the improvement of asthma symptoms after weight reduction indicates a causal relationship, suggesting a possible bidirectional interaction. 15 Nevertheless, there are only few studies relating obesity to bronchial hyperresponsiveness in children, with the use of a bronchial provocation test, such as methacholine or dry powder mannitol test. 7,16,17 Nowadays, there is sufficient data to consider that adult asthmatics present impaired glucose metabolism and insulin resistant patients are prone to develop wheezing.…”

The role of airway hyperresponsiveness measured by methacholine challenge test in defining asthma severity in asthma–obesity syndrome

“…Other medical therapies also require further attention for obese asthmatic adults. Serafino-Agrusa et al [31] reviewed the literature on medical therapies such as statins and bisphosphonates and concluded that diet and physical activity could achieve similar gains. Alternatively, pharmacotherapies could be selectively used in patients who are unwilling or unfit to undergo intensive weight loss programs or surgery.…”

“…Specific proposed pathways include endocrine mediation through adipocytokines [29], increased oxidative stress [30], and alteration of eosinophil function [31].…”