SC-53228

This article reviews the mechanisms and potential therapeutic uses of compounds with inhibitory effects on leukotriene B4 (LTB4) production or its activity, and focuses on compounds that have been shown in animal and/or human studies to have potential efficacy in treating dermatological disorders. These compounds, many of which are not familiar to many dermatologists, include inhibitors of 5-lipoxygenase such as ETH615, 15-hydroxyeicosatetraenoic acid, leflunomide, linetastine, lonapalene, MK886, R-68151 and zileuton, and antagonists of LTB4 such as SC53228, SC50605, SC51146 and VML295. The purpose of this paper is to introduce our colleagues to these potentially useful compounds currently in preclinical or early clinical testing.

The importance of the potent neutrophil chemoattractant leukotriene (LT)B4 in causing ozone-induced bronchoconstriction, airway inflammation, and airway hyperresponsiveness in dogs was studied using the LTB4-receptor antagonist SC-53228. Seven dogs from random sources were studied three times, at least 2 wk apart. On each occasion, acetylcholine (Ach) airway responsiveness was measured before and 1 h after ozone (3 ppm, 30 min) or dry air inhalation, followed by a bronchoalveolar lavage (BAL). On the first day, dogs were treated with SC-53228 (0.4 mg/kg intravenously) followed by a continuous intravenous infusion of 1.2 mg/kg/h before ozone inhalation. On the other two days, diluent was infused followed by ozone or dry air inhalation. Cell counts were measured in BAL and cell activation was measured by spontaneous and by phorbol myristate acetate-stimulated (PMA) (2.4 mumol/L) oxygen radical release, measured from washed BAL cells (4 x 10(6) cells) by lucigenin-enhanced chemiluminescence. Ozone inhalation caused bronchoconstriction and airway hyperresponsiveness. SC-53228 inhibited the ozone-induced airway hyperresponsiveness (p = 0.006), but not the bronchoconstriction. Spontaneous (p = 0.004) and PMA-stimulated (p = 0.04) lucigenin-enhanced chemiluminescence were increased after ozone inhalation. The ozone-induced increases in PMA-stimulated chemiluminescence were significantly attenuated by treatment with SC-53228 (p = 0.04). These results suggest that LTB4 is involved in the pathogenesis of ozone-induced airway hyperresponsiveness, possibly through activation of airway inflammatory cell.