Nonsteroidal antiinflammatory agents inhibit stimulated neutrophil adhesion to endothelium: Adenosine dependent and independent mechanisms

Abstract

All nonsteroidal antiinflammatory drugs (NSAIDs) inhibit neutrophil aggregation (homotypic cell-cell adhesion) and do so without affecting expression of CD11b/CD18. Since the first step in acute inflammation is a critical interaction between neutrophils and the vascular endothelium (heterotypic cell-cell adhesion), we determined whether NSAIDs diminish the adherence of neutrophils to the endothelium. At antiinflammatory concentrations (0.5-5 mM) sodium salicylate, an NSAID that does not inhibit prostaglandin synthesis, inhibited stimulated but not unstimulated neutrophil adherence to endothelial cells (IC50 < 1 mM, P < 0.00001). Salicylates have previously been shown to inhibit oxidative phosphorylation and, predictably, sodium salicylate inhibited oxidative phosphorylation, as evidenced by depletion of ATP stores (875 +/- 75 pmol/10(6) PMN, [2.92 +/- 0.25 mM]) in stimulated (FMLP, 0.1 microM) but not resting neutrophils treated with antiinflammatory doses of sodium salicylate (EC50 = 1 mM, P < 0.00001). Indomethacin and piroxicam (10 and 30 microM) only minimally decreased ATP concentrations in stimulated and resting neutrophils. ATP is metabolized to adenosine, and we have previously demonstrated that both endogenously released (180-200 nM) and exogenous adenosine (IC50 = 250 nM) inhibit stimulated neutrophil adherence to endothelial cells. To determine whether the increased metabolism of ATP and the resultant increase in adenosine release were responsible for inhibition of neutrophil adhesion to endothelium, we determined whether addition of adenosine deaminase (ADA, 0.125 IU/ml), an enzyme that converts extracellular adenosine to its inactive metabolite, inosine, affected inhibition of neutrophil adhesion to endothelium by stimulated neutrophils. ADA significantly reversed inhibition of neutrophil adherence to endothelium by sodium salicylate (0.5-5 mM, P < 0.00001). This suggests that sodium salicylate inhibits neutrophil adherence by increasing adenosine release. Whereas indomethacin and piroxicam (10-50 microM) also inhibited stimulated neutrophil adherence to endothelial cells, ADA did not affect their inhibition of adherence. These studies demonstrate a heretofore unexpected antiinflammatory mechanism for salicylates: salicylates increase ATP hydrolysis and thereby enhance release of adenosine. Moreover, these data are consistent with the hypothesis that NSAIDs differ from one another with respect to their mechanisms of action.

The antiinflammatory effects of an adenosine kinase inhibitor are mediated by adenosine

“…Gruber (H Gruber: US patent 5,030,623; 1991) and Baggott and colleagues (10,ll) have proposed that sulfasalazine, another potent second-line antirheumatic agent, also inhibits AICAR transformylase, thereby promoting adenosine release and diminishing inflammation. We have reported that sodium salicylate, which does not inhibit prostaglandin synthesis, diminishes stimulated leukocyte adhesion to endothelial cells by increasing adenosine release from endothelial cells (16). Indeed, others have reported that 6-methylmercaptopurine riboside, a potential metabolite of azathioprine, inhibits adenosine kinase; the effect of this metabolite (if it accumulates to substantial levels) on adenosine metabolism may contribute to the antiinflammatory effects of azathioprine and its utility in the therapy of inflammatory diseases (17).…”

Nonsteroidal Anti-Inflammatory Drug Reduces Neutrophil and Macrophage Accumulation but Does Not Improve Tendon Regeneration

“…NSAIDs inhibit tissue inflammation by repressing cyclooxygenase (COX) activity, thereby leading to a reduction in proinflammatory prostaglandin synthesis (Vane, 1996). NSAIDs can also repress inflammation by inducing apoptosis (Shiff et al, 1995), activating peroxisome proliferator-activated receptors-␣ and -␥ (Lehmann et al, 1997) and inhibiting neutrophil (PMN) aggregation (Cronstein et al, 1994) and degranulation (Kaplan et al, 1984). Diclofenac can induce shedding of adhesion molecules located on PMNs, thereby inhibiting their locomotion and ability to invade inflamed tissues (Diaz-Gonzalez et al, 1995;Perianin et al, 1985).…”

Aspirin Inhibits In Vitro Maturation and In Vivo Immunostimulatory Function of Murine Myeloid Dendritic Cells

“…Several groups have shown that aspirin, or its metabolite salicylate, acts on key steps in granulocyte-mediated inflammation (9,(11)(12)(13). With respect to lymphocytes, a suppressive effect on ex vivo lymphocyte transformation (14) and a cytotoxic effect on B cell chronic lymphocytic leukemia cells at very high aspirin concentrations (50% inhibitory concentration, Ͼ5-10 mM) have been reported (15).…”