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Open Access Research article

A2B adenosine receptor activity is reduced in neutrophils from patients with systemic sclerosis

Laura Bazzichi1*, Letizia Trincavelli2, Alessandra Rossi2, Francesca De Feo2, Antonio Lucacchini2, Stefano Bombardieri1 and Claudia Martini2

Author Affiliations

1 Department of Internal Medicine, Division of Rheumatology, University of Pisa, Pisa, Italy

2 Departments of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy

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Arthritis Res Ther 2004, 7:R189-R195  doi:10.1186/ar1468

Published: 10 December 2004

Abstract

We conducted the present study to investigate protein expression and functioning of A2A and A2B adenosine receptors (ARs) in neutrophils of patients affected by systemic sclerosis (SSc). The presence of A2A and A2B ARs was assessed by immunoblotting using specific antibodies. Equilibrium A2A and A2B ARs binding parameters were evaluated by radioligand binding assay. Functional studies were conducted to investigate coupling of the A2B AR to the adenylyl cyclase pathway. This is the first report of the use of Western blot analysis to confirm the presence of A2A and A2B ARs in human neutrophils. No significant changes in A2A AR binding parameters or expression levels were detected between SSc patients and healthy control individuals. A significant decrease (65%) in the maximum density of A2B AR binding sites occurred in SSc neutrophils, whereas no changes in the affinity constant values were found. Moreover, a decrease in A2B AR mediated adenylyl cyclase activity was observed in patients with SSc. Our findings demonstrate the occurrence of selective alterations in A2B AR density and signalling in SSc.

Keywords:
adenosine; A2 adenosine receptors; neutrophils; receptor binding; systemic sclerosis