Correlation of TSLP, IL-33, and CD4+CD25+FOXP3+T regulatory (Treg) in pediatric asthma

Objective: Newly discovered cytokines TSLP and IL33 are being studied as important indicators of Th2 inflammation and their effect on Treg cells is likely to modulate immune response. We attempted to study TSLP and IL-33 and then correlated with Tregs in order to find possible biomarker in these patients. Methods: Sixty-five children (37 with asthma only and 28 with asthma and rhinitis) aged 6.4 +/- 3.2 years (patient group) and 15 healthy children aged 8.0 +/- 2.6 years (control group) were recruited in this study. In vitro analysis of TSLP and IL-33 was done in serum samples of 65 newly diagnosed children for allergic asthma and 15 healthy children using the sandwich ELISA method. The expression of Treg cells (CD4+CD25+FOXP3+) was analyzed by flow cytometry. Results: The mean TSLP in the patient group (592 +/- 68pg/ml) was significantly higher than controls (215 +/- 45pg/ml) (p<0.05). Alternatively, the expression of FOXP3+T reg cells was significantly lower in the patient group (52 +/- 36) compared with the controls (95.9 +/- 3.6) (p=0.003). IL-33 was also significantly higher (4044 +/- 413pg/ml) in the patient group compared with the controls (3282 +/- 331.5pg/ml) (p=0.0001). The expression of Treg cells was negatively correlated with the TSLP (r=-0.23, p=0.07). Asthma control test (ACT) was also negatively correlated with TSLP in the patient group (r=-0.14, p>0.05). Conclusion: Children with asthma show elevated serum levels of TSLP, which correlated negatively with asthma control test and Treg cells. TSLP may be used as a biomarker for inflammation in pediatric asthma patients.