Hyaluronan (HA) fragments produced through the degradation of native highly polymerized HA during inflammation, may exacerbate pro-inflammatory responses in various pathologies. In contrast, the purine nucleoside adenosine (ADO) interacting with 4 cell surface adenosine receptor subtypes (ARs), named A2AR, A2BR, A1 and A3, acts as an endogenous modulator of the inflammatory process in different tissues. In particular, the engagement of high-affinity A2AR by ADO activates a pathway leading to increased cAMP production. Elevated levels of cAMP have been associated with the activation of protein kinase A (PKA) that is able to inhibit NF-kappaB, hence exerting anti-inflammatory activity. The aim of this study was to investigate the effect of ADO treatment in chondrocytes obtained from normal mice and stimulated with interleukin-1beta (IL-1beta). Messenger RNA and related protein levels were measured in chondrocytes stimulated with IL-1beta for PKA, tumor necrosis factor-alpha (TNF-alpha), interleukin- 6 (IL-6), and interleukin-18 (IL-18) with and without the addition of ADO. NF-kappaB activation, cAMP levels, and A2A, A2B, A1, and A3 receptor expression were also evaluated. The stimulation of chondrocytes with IL-1beta exhibited a significant up-regulation of cAMP PKA, and pro-inflammatory cytokine levels, and of NF-kappaB activation. ADO treatment also produced a significant increase in cAMP and PKA, although it reduced NF-kappaB activation and pro-inflammatory cytokine levels. The inhibition of HA action using specific HA-binding proteins (HABP) reduced IL-1beta action, but did not affect ADO activity. In contrast, the inhibition of A2AR using a specific A2AR small interference RNA (siRNA) increased inflammation further while cAMP and PKA levels were decreased. This study suggests that HA is in part responsible for the upregulation of pro-inflammatory cytokines in chondrocytes and that endogenous/exogenous ADO may reduce inflammation via PKA.

PROTEIN KINASE A MEDIATED ANTI-NFLAMMATORY EFFECTS EXERTED BY ADENOSINE TREATMENT IN MOUSE CHONDROCYTES STIMULATED WITH IL-1β

CAMPO, Giuseppe Maurizio;AVENOSO, Angela;D'ASCOLA, ANGELA;Scuruchi M.;CALATRONI, Alberto;CAMPO, Salvatore Giuseppe
2012

Abstract

Hyaluronan (HA) fragments produced through the degradation of native highly polymerized HA during inflammation, may exacerbate pro-inflammatory responses in various pathologies. In contrast, the purine nucleoside adenosine (ADO) interacting with 4 cell surface adenosine receptor subtypes (ARs), named A2AR, A2BR, A1 and A3, acts as an endogenous modulator of the inflammatory process in different tissues. In particular, the engagement of high-affinity A2AR by ADO activates a pathway leading to increased cAMP production. Elevated levels of cAMP have been associated with the activation of protein kinase A (PKA) that is able to inhibit NF-kappaB, hence exerting anti-inflammatory activity. The aim of this study was to investigate the effect of ADO treatment in chondrocytes obtained from normal mice and stimulated with interleukin-1beta (IL-1beta). Messenger RNA and related protein levels were measured in chondrocytes stimulated with IL-1beta for PKA, tumor necrosis factor-alpha (TNF-alpha), interleukin- 6 (IL-6), and interleukin-18 (IL-18) with and without the addition of ADO. NF-kappaB activation, cAMP levels, and A2A, A2B, A1, and A3 receptor expression were also evaluated. The stimulation of chondrocytes with IL-1beta exhibited a significant up-regulation of cAMP PKA, and pro-inflammatory cytokine levels, and of NF-kappaB activation. ADO treatment also produced a significant increase in cAMP and PKA, although it reduced NF-kappaB activation and pro-inflammatory cytokine levels. The inhibition of HA action using specific HA-binding proteins (HABP) reduced IL-1beta action, but did not affect ADO activity. In contrast, the inhibition of A2AR using a specific A2AR small interference RNA (siRNA) increased inflammation further while cAMP and PKA levels were decreased. This study suggests that HA is in part responsible for the upregulation of pro-inflammatory cytokines in chondrocytes and that endogenous/exogenous ADO may reduce inflammation via PKA.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/2471621
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact