Effects of Adenosine A2A and A2B Receptor Activation on Signaling Pathways and Cytokine Production in Human Uroepithelial Cells

Abstract

Aims: Adenosine A 2A and A 2B receptor subtypes have both been implicated in the modulation of inflammation. We examined adenosine A 2A and A 2B receptor expression, signaling pathways and the effect of adenosine A 2A and A 2B receptor activation on the uropathogenic Escherichia coli (UPEC)-stimulated IL-8 response in human uroepithelial cells (UROtsa). Methods: Receptor expression was examined by RT-PCR and Western blot, and IL-8 production, intracellular cAMP levels and phosphoproteins were measured by ELISA, EIA and multiplex immunoassay, respectively. Results: The adenosine A 1, A 2A and A 2B receptor subtypes were detected in UROtsa cells. The adenosine A 2A receptor agonist CGS 21680 did not stimulate cAMP production but CREB phosphorylation was slightly increased. The adenosine A 2 receptor agonist CPCA induced a pronounced cAMP and CREB response. Furthermore, CGS 21680 but not CPCA decreased ERK 1/2 and STAT3 phosphorylation. UPEC infection stimulated the host IL-8 production but CPCA or CGS 21680 did not affect UPEC-evoked IL-8 production. Conclusions: Our data identified differences in signaling pathways evoked by adenosine A 2A and A 2B receptor activation. Activation of the adenosine A 2A receptor inhibited STAT3 and ERK 1/2 phosphorylation, while the cAMP-CREB pathway was induced by adenosine A 2B receptor activation. No anti- or proinflammatory effects were found for uroepithelial adenosine A 2A or A 2B receptors.