Effects of flunixin, tolfenamic acid, R(-) and S(+) ketoprofen on the response of equine synoviocytes to lipopolysaccharide stimulation.

The objective of this study was to analyse the effects of 4 nonsteroidal anti-inflammatory drugs (NSAIDs) on the production of beta-glucuronidase (beta-glu), tumour necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), interleukin-1 (IL-1) and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-stimulated equine synoviocytes. The agents studied were flunixin, tolfenamic acid, S(+)ketoprofen (KTP) and R(-)ketoprofen. LPS-induced release of beta-glu from synoviocytes was inhibited in a concentration dependent manner by all 4 compounds, tolfenamic acid being the most potent. Of the 2 KTP enantiomers, S(+)KTP exerted the greatest inhibitory effect. Tolfenamic acid and flunixin increased the production of IL-6-like activity by LPS-stimulated synoviocytes only at the highest concentration studied (1000 mumol/l). Lower concentrations produced no effect on IL-6. Flunixin, tolfenamic acid and S(+)KTP produced statistically significant and concentration related increases in the release of IL-1-like activity by LPS-stimulated synoviocytes. Prostaglandin E2 synthesis was markedly inhibited in a concentration dependent manner by the 4 NSAIDs. However, R(-)KTP was effective only at the highest concentrations investigated (1000 and 100 mumol/l). The present findings are compatible with the possibility that longterm use of NSAIDs in arthropathies, by removing the regulator role of PGE2 on IL-1 synthesis, might enhance the pathological process of cartilage degeneration.