Adult-onset asthma (AOA) is associated with metabolic syndrome as well as with higher median serum interleukin 6 (IL-6) and a higher leptin-adiponectin (LA) ratio compared with healthy controls, suggesting inflammatory markers in adipose tissue may be involved in AOA pathophysiology, according to research findings published in Respiratory Medicine.
The cross-sectional study included 27 patients (mean age, 57 years) with AOA, 25 patients with childhood-onset asthma (COA; mean age, 42 years), and 29 age- and sex-matched controls (mean age, 41 years) without asthma from outpatient clinics of 2 teaching hospitals in Rotterdam, the Netherlands. Researchers compared these groups in terms of the incidence of metabolic syndrome as well as levels of lipid-derived inflammatory markers.
International joint interim statement criteria were used to define metabolic syndrome. These criteria involved sex-based measures of waist circumference, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol, and type 2 diabetes mellitus. Study participants underwent lung function tests, blood tests, as well as physical activity tracking during outpatient clinic visits.
There was no difference between the patients with AOA vs COA in terms of asthma severity based on asthma control questionnaire, exacerbation frequency, and GINA treatment level. Asthma onset after the age of 18 years was significantly associated with metabolic syndrome (odds ratio [OR], 3.64; 95% CI, 1.16–11.42; P =.03) in a regression analysis adjusted for age, sex, body mass index, and smoking status.
Compared with controls, patients with AOA had significantly higher median serum IL-6 (1.13 pg/mL vs 3.10 pg/mL, respectively; P =.002) and LA ratio (2.24 pg/mL vs 6.21 pg/mL; P =.0390). No difference in IL-6 and LA ratio was found in comparing the COA group vs the control group.
The researchers noted that the study participants were selected from a tertiary asthma center, suggesting the findings may not be generalizable across a less severe asthma patient population.
Based on their findings, the researchers concluded that adipose tissue-derived inflammatory markers contribute to the immunopathology of AOA and that along with obesity, metabolic syndrome should be considered as an important, treatable trait in AOA.
de Boer GM, Tramper-Stranders GA, Houweling L, et al. Adult but not childhood onset asthma is associated with the metabolic syndrome, independent from body mass index. Respir Med. Published online September 10, 2021. doi:10.1016/j.rmed.2021.106603