Airway eosinophilia, epithelial desquamation, and hyperresponsiveness are characteristics of the airway inflammation underlying bronchial asthma. The contribution of intercellular adhesion molecule-1 (ICAM-1) to eosinophil migration and airway responsiveness was studied. ICAM-1 partially mediated eosinophil adhesion to to endothelium in vitro and was upregulated on inflamed bronchial endothelium in vivo. ICAM-1 expression was also upregulated on inflamed airway epithelium in vitro and in vivo. In a primate model of asthma, a monoclonal antibody to ICAM-1 attenuated airway eosinophilia and hyperresponsiveness. Thus, antagonism of ICAM-1 may provide a therapeutic approach to reducing airway inflammation, hyperresponsiveness, and asthma symptoms.

In mammalian cells, eicosanoid biosynthesis is usually initiated by the activation of phospholipase A2 and the release of arachidonic acid (AA) from membrane phospholipids. The AA is subsequently transformed by cyclooxygenase (COX) and lipoxygenase (LO) pathways to prostaglandins, thromboxane and leukotrienes collectively termed eicosanoids. Eicosanoid production is considerably increased during inflammation. Both COX and LO pathways are of particular clinical relevance. The COX pathway is the major target for non-steroidal anti-inflammatory drugs (NSAIDs), the most popular medications used to treat pain, fever and inflammation. Although their anti-inflammatory effects are well known, their long-term use is associated with gastrointestinal (GI) complications such as ulceration. In 1991, it was discovered that COX exists in two distinct isozymes, COX-1 and COX-2, of which COX-2 is primarily expressed at sites of inflammation and produces pro-inflammatory eicosanoids. For this reason, COX-2 selective inhibitors (COXIBs) have been developed recently as anti-inflammatory agents to minimize the risk of GI toxicity. Recently, some COX-2 selective inhibitors have shown adverse cardiovascular side effects, resulting in the withdrawal of rofecoxib and valdecoxib from the market. Selective inhibition of COX-2 without reducing COX-1-mediated thromboxane production could alter the balance between prostacyclin and thromboxane and promote a prothrombotic state, thereby explaining the observed COX-2 cardiovascular risk. In this review, we describe mechanisms for the production of pro-inflammatory eicosanoid mediators contributing to inflammation and summarize promising options for the prevention of inflammatory mediator formation and the therapeutic inhibition of pain and inflammation.

We have examined the effects of direct intratracheal instillation of purified eosinophil granule proteins on pulmonary function and airway responsiveness in primates. The results of this study show for the first time that installation of major basic protein (MBP) directly into the trachea of primates results in a significant and dose-related increase in airway responsiveness to inhaled methacholine. Furthermore, MBP and eosinophil peroxidase (EPO) induce a transient bronchoconstriction immediately after instillation that resolves by 1 h postinstillation. In constrast, instillation of other eosinophil granule proteins had no effect on airway responsiveness or pulmonary function. These data indicate a direct role of the eosinophil in the pathogenesis of airway hyperresponsiveness.We suggest that the MBP of human eosinophils has an effector role in the pathogenesis ofairway hyperresponsiveness which may involve active interaction with resident airway tissue cells. MBP may also mediate altered lung function in various inflammatory lung diseases associated with pulmonary eosinophilia. (J. Clin.

This study examines the role of endothelial leukocyte adhesion molecule-i in the development of the acute airway inflammation (cell influx) and late-phase airway obstruction in a primate model of extrinsic asthma. In animals sensitive to antigen, a single inhalation exposure induced the rapid expression of ELAM-1 (6 h) exclusively on vascular endothelium that correlated with the influx of neutrophils into the lungs and the onset of late-phase airway obstruction. In contrast, basal levels of ICAM-1 was constitutively expressed on vascular endothelium and airway epithelium before antigen challenge. After the single antigen exposure, changes in ICAM-1 expression did not correlate with neutrophil influx or the change in airway caliber. This was confirmed by showing that pretreatment with a monoclonal antibody to ICAM-1 did not inhibit the acute influx of neutrophils associated with late-phase airway obstruction, whereas a monoclonal antibody to ELAM-1 blocked both the influx of neutrophils and the late-phase airway obstruction. This study demonstrates a functional role for ELAM-1 in the development of acute airway inflammation in vivo. We conclude that, in primates, the late-phase response is the result of an ELAM-1 dependent influx of neutrophils. Therefore, the regulation of ELAM-1 expression may provide a novel approach to controlling the acute inflammatory response, and thereby, affecting airway function associated with inflammatory disorders, including asthma. (J. Clin. Invest.

Despite its widespread use, diclofenac has gastrointestinal liabilities common to nonsteroidal antiinflammatory drugs (NSAIDs) that might be reduced by concomitant administration of a gastrointestinal cytoprotectant such as nitric oxide (NO). A series of novel diclofenac esters containing a nitrosothiol (-S-NO) moiety as a NO donor functionality has been synthesized and evaluated in vivo for bioavailability, pharmacological activity, and gastric irritation. All S-NO-diclofenac derivatives acted as orally bioavailable prodrugs, producing significant levels of diclofenac in plasma within 15 min after oral administration to mice. At equimolar oral doses, S-NO-diclofenac derivatives (20a-21b) displayed rat antiinflammatory and analgesic activities comparable to those of diclofenac in the carrageenan-induced paw edema test and the mouse phenylbenzoquinone-induced writhing test, respectively. All tested S-NO-diclofenac derivatives (20a-21b) were gastric-sparing in that they elicited markedly fewer stomach lesions as compared to the stomach lesions caused by a high equimolar dose of diclofenac in the rat. Nitrosothiol esters of diclofenac comprise a novel class of NO-donating compounds having therapeutic potential as nonsteroidal antiinflammatory agents with an enhanced gastric safety profile.