title: Protein kinase a mediated anti-inflammatory effects exerted by adenosine treatment in mouse chondrocytes stimulated with IL-1β.
abstract: Hyaluronan (HA) fragments produced by degradation of native highly polymerized HA during inflammation may exacerbate proinflammatory responses in different pathologies. In contrast, the nucleoside adenosine (ADO) interacting with cell surface adenosine receptors A(2A) R, A(2B) R, A(1,) and A(3) , acts as endogenous modulator of the inflammation. The engagement of high-affinity A(2A) R by ADO activates a pathway leading to increased cAMP production. Elevated levels of cAMP associate with the activation of protein kinase A (PKA) able to inhibit NF-kB, hence exerting anti-inflammatory activity. In this study the effect of ADO treatment in normal murine chondrocytes stimulated with interleukin-1beta (IL-1beta) was investigated. mRNA and related protein levels were measured for enzymes, receptors and pro-inflammatory cytokines TNF-alpha, IL-6 and Il-18. IL-1beta stimulation significantly up-regulated HA levels, its fragmentation, cAMP, PKA, cytokine levels, and activated NF-kB. ADO treatment increased cAMP and PKA levels, while reduced NF-kB activation and cytokine levels. HA inhibition by specific synthetic HA blocking peptide (Pep-1) reduced IL-1beta action but not ADO activity. While A(2A) R inhibition by specific small interference RNA (siRNA) increased inflammation and decreased cAMP and PKA levels. This study suggests that HA is partially responsible for the up-regulation of proinflammatory cytokines in chondrocytes and that endogenous/exogenous ADO may reduce inflammation via PKA.
authors.affiliation: Department of Biochemical, Physiological and Nutritional Sciences, Section of Medical Chemistry, School of Medicine, University of Messina, Policlinico Universitario, 98125 Messina, Italy. gcampo@unime.it
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Campo
authors.forename: Angela
authors.initials: A
authors.lastname: Avenoso
authors.forename: Angela
authors.initials: A
authors.lastname: D'Ascola
authors.forename: Vera
authors.initials: V
authors.lastname: Prestipino
authors.forename: Michele
authors.initials: M
authors.lastname: Scuruchi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Nastasi
authors.forename: Alberto
authors.initials: A
authors.lastname: Calatroni
authors.forename: Salvatore
authors.initials: S
authors.lastname: Campo
mesh_terms: D000241:Adenosine / Q000378:metabolism / Q000494:pharmacology*; D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D019902:Chondrocytes / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D006820:Hyaluronic Acid / Q000494:pharmacology; D007249:Inflammation / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism*; D008297:Male; D051379:Mice; D034741:RNA, Small Interfering / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000276:Adjuvants, Immunologic; D016207:Cytokines; D053583:Interleukin-1beta; D034741:RNA, Small Interfering; D018047:Receptors, Purinergic P1; D006820:Hyaluronic Acid; D017868:Cyclic AMP-Dependent Protein Kinases; D000241:Adenosine