JKB-122 is effective, alone or in combination with prednisolone in Con A-induced hepatitis.

Con A-induced hepatitis in mice is an established model of autoimmune hepatitis (AIH). JKB-122, a toll-like receptor 4 (TLR4) antagonist, was tested for hepatotprotectant activity. Within several hours of Con A challenge (15mg/kg iv), increased production of proinflammatory cytokines with inflammatory infiltrate occurred in the liver. The severity of tissue necrosis and the amount of circulating liver enzymes peak at 24h post Con A challenge. JKB-122 was given 24 and 16h before, then concurrently, and 4 and 8h (× 5 doses) after challenge with Con A. Serum and liver were harvested at 3, 9 and 24h post Con A challenge. JKB-122 at 20 and 50mg/kg po prevented the increase of serum liver enzymes by 47% and 95% respectively vs vehicle control 24h post Con A. JKB-122 significantly inhibited Con A-induced pathological lesions in the liver and the amount of IFN-γ IL-1ß, IL-4, IL-5, IL-6, IL-17A and TNF-α starting as early as 3h post Con A. Moreover, JKB-122 given concurrently (× 3 doses) with Con A showed similar effect. Finally, JKB-122 enhanced the therapeutic effects of submaximal dose of prednisolone with improved lesion score. It is concluded that JKB-122 at 20 and 50mg/kg po caused dose-dependent inhibition of elevated liver enzymes in Con A-induced hepatitis in mice, indicating hepatoprotectant activity. The results suggest that JKB-122 as monotherapy or in combination with prednisolone may offer a viable approach to the treatment of AIH.

Validation of a [3H]astemizole binding assay in HEK293 cells expressing HERG K+ channels.

A radioligand binding assay for the HERG (human ether-a-go-go-related gene) K(+) channel was developed to identify compounds which may have inhibitory activity and potential cardiotoxicity. Pharmacological characterization of the [(3)H]astemizole binding assay for HERG K(+) channels was performed using HERG-expressing HEK293 cells. The assay conditions employed yielded 90% specific binding using 10 microg/well of membrane protein with 1.5 nM of [(3)H]astemizole at 25 degrees C. The K(d) and B(max) values were 5.91 +/- 0.81 nM and 6.36 +/- 0.26 pmol/mg, respectively. The intraassay and interassay variations were 11.4% and 14.9%, respectively. Binding affinities for 32 reference compounds (including dofetilide, cisapride, and terfenadine) with diverse structures demonstrated a similar potency rank order for HERG inhibition to that reported in the literature. Moreover, the [(3)H]astemizole binding data demonstrated a rank order of affinity that was highly correlated to that of inhibitory potency in the electrophysiological studies for HERG in HEK293 (r(SP) = 0.91, P<0.05). In conclusion, the [(3)H]astemizole binding assay is rapid and capable of detecting HERG inhibitors.