P12 The complex effects of a slow-releasing hydrogen sulifde donor (GYY4137) in a model of inflammatory arthritis and in primary human cartilage cells

Abstract

Synthesis of H 2 S is markedly increased in knee joint synovial fluid (SF) joints from patients with inflammatory joint disease (IJD) compared to paired plasma and SF from age-matched disease controls. SF levels also negatively correlated with disease activity, SF total white cell and neutrophil count suggesting a possible anti-inflammatory role for induced H 2 S synthesis in the joint. These observations also highlight the pharmacological potential for H 2 S donor molecules in (IJD). We have assessed the effect of GYY4137 (a slow-releasing H 2 S donor) on lipopolysaccharide (LPS)-evoked release of inflammatory mediators from human synoviocytes (HFLS) and articular chondrocytes (HAC) in vitro . We also examined the effects of GYY4137 on human recombinant iNOS, COX-1, COX-2 and tumour necrosis factor- α converting enzyme (TACE). We further examined the effect of GYY4137 in a complete Freund’s adjuvant (CFA) model of arthritis in the mouse. GYY4137 (0.1–0.5 mM) decreased LPS-induced production of nitrite ( NO 2 - ) , PGE 2 , TNF- α and IL-6 from HFLS and HAC, reduced the expression and catalytic activity of iNOS, COX-2, and reduced LPS-induced NF-kB activation in vitro . Using recombinant human enzymes, GYY4137 inhibited the activity of COX-1, COX-2, iNOS and TACE. In the CFA treated mouse, adjuvant induced a two fold increase in synovial H 2 S concentrations. GYY4137 (50 mg/kg, i.p.) injected 1 h prior to CFA increased knee joint swelling whilst an anti-inflammatory effect, as evidenced by reduced synovial fluid myeloperoxidase (MPO) and N -acetyl- β - d -glucosaminidase (NAG) activity and decreased TNF- α , IL-1 β , IL-6 and IL-8 concentration, was apparent when GYY4137 was injected 6 h after CFA. GYY4137 was also anti-inflammatory when given 18 h after CFA. The effects of H 2 S on the inflammatory process are highly complex. Not only is the anti-inflammatory effect determined by the donor used (’fast’ vs ’slow’ release donors) but also determined in vivo by the timing of the donor administration. Thus, whilst GYY4137 consistently reduced the generation of pro-inflammatory mediators from human joint cells in vitro , its effect on arthritis in vivo depended on the timing of administration.