title: A2B adenosine receptor activity is reduced in neutrophils from patients with systemic sclerosis.
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.
authors.affiliation: Department of Internal Medicine, Division of Rheumatology, University of Pisa, Pisa, Italy. l.bazzichi@int.med.unipi.it
authors.forename: Laura
authors.initials: L
authors.lastname: Bazzichi
authors.forename: Letizia
authors.initials: L
authors.lastname: Trincavelli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Rossi
authors.forename: Francesca
authors.initials: F
authors.lastname: De Feo
authors.forename: Antonio
authors.initials: A
authors.lastname: Lucacchini
authors.forename: Stefano
authors.initials: S
authors.lastname: Bombardieri
authors.forename: Claudia
authors.initials: C
authors.lastname: Martini
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000502:physiology; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000097:blood; D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000097:blood* / Q000276:immunology / Q000473:pathology; D015153:Blotting, Western; D000242:Cyclic AMP / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000737:chemistry* / Q000473:pathology; D010627:Phenethylamines / Q000378:metabolism; D011869:Radioligand Assay; D043705:Receptor, Adenosine A2A / Q000097:blood; D043704:Receptor, Adenosine A2B / Q000097:blood* / Q000172:deficiency / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000502:physiology; D012595:Scleroderma, Systemic / Q000097:blood* / Q000276:immunology / Q000473:pathology; D015398:Signal Transduction
chemical_list: D010627:Phenethylamines; D043705:Receptor, Adenosine A2A; D043704:Receptor, Adenosine A2B; D043562:Receptors, G-Protein-Coupled; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D000241:Adenosine
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