Innate immunity in obese asthmatic allergic and nonallergic adults

Obesity is characterized by activation of the innate immune responses and low grade systemic inflammation with increased levels of inflammatory cytokines. In the past two decades, the prevalence of both asthma and obesity has increased dramatically. The aim of the present study is to examine the relationship between innate immunity, obesity and asthma in allergic and non allergic obese persons by estimating interleukin-6 (IL-6) and C-reactive protein (CRP) levels as markers of innate immunity. The study included 2 groups of asthmatic patients; 50 obese asthmatic and 50 lean asthmatic patients. The obese asthmatic group included 25 allergic obese and 25 non-allergic obese asthmatics. Similarly the lean asthmatic group included 25 allergic and 25 non-allergic lean asthmatics. Body mass index (BMI), skin prick test, serum total IgE, peak expiratory flow rate (PEFR), interleukin-6 (IL-6) and C-reactive protein (CRP) levels were all assessed. A significant difference was found between allergic and non-allergic obese asthmatics and between allergic and non-allergic lean asthmatics as regards IgE, IL-6 and CRP (P=0.000). Comparison between allergic obese asthmatics and allergic lean asthmatics as regards BMI, IL-6 and CRP revealed high significant differences (P=0.000). In contrast no significant differences existed between them as regards IgE, PEFR (P=0.621, P=0.321 respectively). Comparison between non-allergic obese asthmatics and non-allergic lean asthmatics as regards BMI, IL-6 and CRP levels revealed highly significant differences (P=0.000). While no significant difference existed between them as regards IgE and PEFR (P=0.14, P=0.336 respectively). A significant negative correlation was found between PEFR and IgE in all groups (P=0.000) and negative correlation between PEFR and IL-6, CRP in all groups (P=0.000) except for allergic obese asthmatics group. Meanwhile, there was a significant positive correlation between BMI and IL-6 and CRP in both allergic and non-allergic obese asthmatics (P=0.000). In conclusion, obesity is associated with activation of the innate immune system leading to release of inflammatory cytokines more in non-allergic obese than allergic obese asthmatics. Control of obesity in such patients may lead to control of asthma.