Role of Thymus and Activation-Regulated Chemokine in Allergic Asthma

BACKGROUND: Asthma is a chronic inflammatory airway disease characterized by the predominant infiltration of inflammatory cells in the airways. Thymus and activation-regulated chemokine/C–C motif chemokine 17 (TARC/CCL17) is a chemokine responsible for trafficking T helper 2 cells into sites of allergic inflammation. OBJECTIVE: To validate the role of TARC in association with clinical and inflammatory parameters in adult asthmatics. METHODS: We enrolled 128 asthmatic patients and 70 healthy controls (HCs). Asthma-related clinical and laboratory parameters, including lung function and eosinophil counts, were measured. Serum levels of TARC, free immunoglobulin E (IgE), and eosinophil-derived neurotoxin (EDN) were determined by using enzyme-linked immunosorbent assay; serum total IgE level was measured using ImmunoCAP. The levels of inflammatory lipid mediators, such as leukotriene E4 (LTE4), 15-hydroxyeicosatetraenoic acid (15-HETE), thromboxane B2 (TXB2), and prostaglandin F2α (PGF2α), were measured by liquid chromatography-tandem mass spectrometry. RESULTS: Serum TARC levels are significantly higher in asthmatics than in HCs and in allergic asthmatics than in HCs (P < 0.010 for all), with significantly negative correlations between serum TARC levels and FEV(1)%/MMEF% values (r = −0.314, r = −0.268, P < 0.050 for both). The patients with higher serum TARC levels had higher levels of serum total and free IgE levels (P < 0.050 for both) with positive correlations to serum levels of EDN, TXB2, and 15-HETE (r = 0.233, r = 0.264, and r = 0.223, respectively, P < 0.050 for all). CONCLUSION: We suggest the role of TARC in allergic asthma via contributing to mast cell and eosinophilic inflammation.