TY - JOUR T1 - Down-regulation of the P2Y<sub>12</sub> purinergic receptor expression on human bronchial epithelial cells by transforming growth factor-β JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P4737 AU - Siiri Altraja AU - Alan Altraja Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P4737.abstract N2 - We have demonstrated presence of the P2Y12 purinergic receptor on human bronchial epithelial cells (HBEC). Apart from acting as an alternative receptor for leukotriene E4, neither its function nor regulation on HBEC is known, not to mention its role in airway remodelling. In this context, we hypothesized that transforming growth factor-β (TGF-β) could affect expression of the P2Y12 receptor on HBEC.To test the hypothesis, cultured HBEC were exposed to TGF-β1 (0-10 ng/mL) for 1-24 h. The expression of P2Y12 mRNA was evaluated with use of RT-qPCR.A slight decrease in the expression of P2Y12 not reaching significance was observed at 1-3 h. TGF-β1 significantly suppressed the expression of P2Y12 in HBEC at 12 h (3.5–5.9-fold decrease from control; p=0.001 and p=0.001 at 2 ng/mL and 10 ng/mL, respectively). This decrease persisted by 24 h (3.2–4.0-fold decrease from baseline; p=0.013 and p&lt;0.001 with concentrations of 2 ng/mL and 10 ng/mL, respectively). The decrease was clearly concentration-dependent (p=0.001 and p&lt;0.001 at 12 and 24 h, respectively). The time-dependence in down-regulation of the expression of P2Y12 in HBEC was observed only at higher concentrations of TGF-β1 (p=0.01 at 10 ng/mL).Our results indicate that TGF-β1 down-regulate the P2Y12 in HBEC providing a novel insight into mechanisms by which TGF-β1 may execute its anti-inflammatory properties. However, the impact of this mechanism both independently and in the light of the summary effects of TGF-β1, known as a pro-remodelling factor, remains to be tested.Supported by the Estonian Science Foundation grants No. 9103 and 9043. ER -