Evaluation of serum IL-33 levels in different asthma phenotypes

Background: Asthma is a chronic inflam- matory airway disease with the increasing prevalence worldwide. This is a heteroge- neous gene-by-environment disease with multifactor pathogenesis, which has not been well established yet. Heterogeneity of asthma requires a broader approach to pathogenesis of this disease. IL-33 is a recently discovered cytokine which through its receptor ST2 is a highly selective mar- ker of Th2 cells. In this way, it can start an inflammatory cascade in asthma patho- genesis. Aim: To evaluate serum IL-33 levels in patients with asthma and to analyze these results in relation to different asthma phenotypes. Method: Patients with asthma (n = 95; mean age 46.4  15.3 years) and healthy subjects (n = 48; mean age 41.0  14.4 years) were involved in the study. Asthma phenotypes were defined according to the patients’ anamnesis, aller- gic status (skin prick), total IgE level, num- ber of eosinophils in peripheral blood, BMI and severity of the disease (GINA criteria). IL-33 levels in serum were mea- sured with Human IL-33 ELISA Kit according to the manufacturer’s protocol. Results: Analysis of all studied subjects showed that IL-33 level is higher in asthma group when compared to healthy controls (809.06  142.38 pg/ml vs 366.10  42.23 pg/ml, P < 0.01). Asthmatic patients suffering from drug allergy had higher con- centration of IL-33 in comparison to asthma patients without drug allergy (1394.15  515.82 pg/ml vs 719.72  145.06 pg/ml, P < 0.05). Patients with so- called cough-variant asthma had lower level of IL-33 than those who did not expe- rienced cough as a main feature (752.25  187.63 pg/ml vs 871.51  211.32 pg/ml, P < 0.05). While investigating asthma patients with different treatment regimens we found that patient without inhaled ster- oid had higher level of IL-33 than other groups (with low, moderate or high doses of inhaled steroid) (1266.89  502.43 pg/ ....