RWJ 67657, a potent, orally active inhibitor of p38 mitogen-activated protein kinase.

Tumor necrosis factor-alpha (TNF-alpha), a cytokine secreted by activated monocytes/macrophages and T lymphocytes, has been implicated in several disease states, including rheumatoid arthritis, inflammatory bowel disease, septic shock, and osteoporosis. Monocyte/macrophage production of TNF-alpha is dependent on the mitogen-activated protein kinase p38. RWJ 67657 (4-[4-(4-fluorophenyl)-1-(3-phenylpropyl)-5-(4-pyridinyl)-1H-imidazol -2-yl]-3-butyn-1-ol) inhibited the release of TNF-alpha by lipopolysaccharide (a monocyte stimulus)-treated human peripheral blood mononuclear cells with an IC(50) of 3 nM, as well as the release of TNF-alpha from peripheral blood mononuclear cells treated with the superantigen staphylococcal enterotoxin B (a T cell stimulus), with an IC(50) value of 13 nM. This compound was approximately 10-fold more potent than the literature standard p38 kinase inhibitor SB 203580 in all p38 dependent in vitro systems tested. RWJ 67657 inhibited the enzymatic activity of recombinant p38alpha and beta, but not gamma or delta, in vitro and had no significant activity against a variety of other enzymes. In contrast, SB 203580 significantly inhibited the tyrosine kinases p56 lck and c-src (IC(50) = 5 microM). RWJ 67657 did not inhibit T cell production of interleukin-2 or interferon-gamma and did not inhibit T cell proliferation in response to mitogens. RWJ 67657 inhibited TNF-alpha production in lipopolysaccharide-injected mice (87% inhibition at 50 mg/kg) and in rats (91% inhibition at 25 mg/kg) after oral administration. Based on these favorable biological properties, RWJ 67657 may have use as a treatment for inflammatory diseases.

The development of novel and selective p56lck tyrosine kinase inhibitors.

Early T-cell receptor mediated signal transduction involves the activation of several tyrosine protein kinases. One of these tyrosine kinases, p56lck, is expressed primarily in T-cells and Natural Killer (NK) cells and has been shown to be critical for their proliferative and effector functions. Indandiones have been identified as a potent and selective chemical class that inhibits p56lck.

Nitroarylhydroxymethylphosphonic acids as inhibitors of CD45.

A series of nitroarylhydroxymethylphosphonic acids was synthesized and evaluated as inhibitors of CD45. It was discovered that both the alpha hydroxy and nitro groups are essential for activity. Potency is enhanced by the addition of a large lipophilic group on the aryl ring adjacent to the phosphonic acid moiety. Kinetics studies have shown that these compounds are competitive inhibitors and thus bind at the active site of this enzyme.

Effect of carbohydrate modification on the localization of human polyclonal IgG at focal sites of bacterial infection.

Radiolabeled human polyclonal IgG localizes at focal sites of infection/inflammation. Previous studies have sought to identify the mechanism of localization, but the relative importance of specific antigen recognition by individual antibody molecules, binding to Fc receptors on inflammatory cells and nonspecific processes such as increased tissue permeability remains uncertain. This study was performed to evaluate the specific role of Fc receptor binding as a mechanism of localization. The Fc region of IgG was modified by endoglycosidase-F digestion and periodate oxidation to reduce the binding of IgG to Fc receptors. In-vitro binding was tested in an Fc receptor binding assay using the human monocyte-like cell line, U937. The in-vivo ability of the modified antibodies to localize at focal sites of E. coli infection was tested by biodistribution studied with the 111In-labeled proteins. Modification of the carbohydrate moiety of the Fc region of IgG resulted in a marked decrease in Fc receptor binding in vitro; with antibody concentrations of 1 micrograms/ml (which is presumed to exist at infected sites) showing no binding for endoglycosidase modified IgG and 50% binding for periodate modified IgG. In contrast, in-vivo infection localization as measured by level of accumulation or target-to-background ratio was not significantly effected by carbohydrate modification. These studies suggest that the contribution of Fc receptor binding to IgG localization at sites of infection is minimal.