Adipose tissue is involved in the production and release of hormones as well as cytokines, which may both contribute to obesity-related insulin resistance, cardiovascular morbidities, hypertension, and metabolic disorders, as well as asthma [
51,
52]. Obesity is associated with increased adipocyte-driven pro-inflammatory activity resulting in chronic local and systemic inflammation [
53,
54]. One of the adipokines released by adipocytes is leptin, and serum leptin concentrations are increased in obesity. In children, increased serum leptin is associated with severity of exercise-induced bronchoconstriction [
50], low-peak expiratory flow rate [
55], and higher asthma prevalence in prepubertal boys [
56], as well as peri- and postpubertal girls [
57]. In contrast, adiponectin, which is also secreted from adipose tissue, is thought to inhibit the production and effects of pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin (IL)-6 and induces the expression of the anti-inflammatory cytokines IL-1 receptor antagonist and IL-10 [
52]. Serum adiponectin levels have been reported to be associated with asthma severity [
33], and adverse clinical outcomes of asthma [
58], as well as exercise-induced bronchoconstriction in children [
50,
52].
Adipokines may change the T helper cell balance in favor of a T helper cell type 1 (Th1) response, as it is seen in asthma associated with obesity [
59,
60]. Inflammation in allergic disease is usually dominated by Th2. However, airway disease in obese asthmatics is not typically characterized by eosinophilic/TH2 inflammation. In fact, obese children with asthma were found to have significantly higher Th1 and lower Th2 responses to specific stimuli compared with non-obese asthmatic children [
61]. In support of this, studies in asthmatics have shown that increased BMI was inversely related to sputum eosinophils and FeNO [
25,
62,
63]. Interestingly, neutrophil-predominant airway inflammation has also been described in obese women with asthma [
64,
65], and weight loss by exercise or dietary changes results in a decrease in airway neutrophils [
66].