Role of Thymus and Activation-Regulated Chemokine in Allergic Asthma

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.

To validate the role of TARC in association with clinical and inflammatory parameters in adult asthmatics.

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.

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 FEV₁%/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).

We suggest the role of TARC in allergic asthma via contributing to mast cell and eosinophilic inflammation.