Analgesic effect of S (+)-flurbiprofen plaster in a rat model of knee arthritis: analysis of gait and synovial fluid prostaglandin E2 levels.

OBJECTIVES: We developed S (+)-flurbiprofen plaster (SFPP), a novel NSAID patch containing S (+)-flurbiprofen (SFP), a potent cyclooxygenase (COX) inhibitor. The purpose of this study was to assess efficacy of SFPP by analysing its effect on the gait disturbance and measuring the prostaglandin E2 (PGE2 ) production in synovial fluid in a rat model of knee arthritis. METHODS: Knee inflammation was induced in rats by intra-articular injection of a yeast suspension. Subsequently, an NSAID patch containing SFP, ketoprofen or loxoprofen was applied over the affected knee. Gait was assessed at 2, 4 and 6 h after application of the patch. The PGE2 concentration in the synovial fluid was measured after the gait assessment. KEY FINDINGS: Application of SFPP (0.125, 0.25, 0.5 or 1 mg/sheet) was followed by a decrease in the visual gait score at all the doses examined. In the case of the other two NSAID patches, only the ketoprofen patch (1 or 2 mg/sheet) and loxoprofen patch (5 mg/sheet) produced a decrease in the visual gait score. All of the NSAID patches decreased the PGE2 production in the synovial fluid. CONCLUSIONS: These results suggest the potential usefulness of SFPP as an analgesic patch in patients with inflammatory joint pain.

Modulating the actions of NK cell-mediated cytotoxicity using lipid-PEG (n) and inhibitory receptor-specific antagonistic peptide conjugates.

Regulating the cell surface modulates the actions of the biological cell response, derives practical applications, and is of scientific interest. On the basis of our previous study using dioleylphosphatidylethanolamine poly(ethylene glycol) with multiple units of ethyleneoxide (DOPE-PEG (n)), we demonstrated the potency of DOPE-PEG (80) as a cell surface modulator. We prepared conjugates of DOPE-PEG (80) and two antagonistic peptides (C1, SGGGCLFNLPWLCG; C26, SGGGCPFSFLPWCG), specifically designed for the inhibitory receptor of natural killer (NK) cells. We confirmed that NK cells exhibited cytotoxicity against DOPE-PEG (80)-peptides-incorporated target cells. We further investigated whether the DOPE-PEG (80)-peptides could affect the cytotoxicity of NK cells in a concentration-dependent manner. C1 peptide showed down-regulation of cytotoxicity at higher concentration, whereas C26 peptide exhibited the saturated cytotoxicity of NK cells at the same concentration. These results suggest that DOPE-PEG (80) can achieve the role of a cell surface modulator without inhibiting the action of conjugated molecules, despite their relatively small size.

Augmentation of NK cell-mediated cytotoxicity to tumor cells by inhibitory NK cell receptor blockers.

NK cells monitor expression of MHC class I by inhibitory receptors and preferentially kill cells that lose or down-regulate MHC class I expression. One possible mechanism by which tumor cells evade NK cell killing is continued expression of appropriate MHC class I ligands to engage inhibitory receptors on NK cells. We show here that small-mol.-wt blockers against the mouse inhibitory NK cell receptor Ly49A enhance NK cell killing of such tumor cells. We identified Ly49A-binding peptides by selecting phages with the capacity to bind recombinant Ly49A expressed in Escherichia coli from a phage display random peptide library. The Ly49A-binding peptides could also bind Ly49A expressed on mammalian cells. Importantly, the Ly49A-binding peptides blocked Ly49A recognition of its MHC class I ligands H-2Dd and H-2Dk. Moreover, blockade of Ly49A by the peptides enhanced cytotoxicity of Ly49A+ NK cells towards H-2Dd-expressing tumor cells. These results clearly indicate effectiveness of small-mol.-wt blockers of inhibitory NK cell receptors in enhancing NK cell-mediated killing of tumor cells that are otherwise resistant because of MHC class I expression.