title: A small molecule that inhibits the interaction of paxillin and alpha 4 integrin inhibits accumulation of mononuclear leukocytes at a site of inflammation.
abstract: Extracellular antagonists of alpha 4 integrin are an effective therapy for several autoimmune and inflammatory diseases; however, these agents that directly block ligand binding may exhibit mechanism-based toxicities. Inhibition of alpha 4 integrin signaling by mutations of alpha 4 that block paxillin binding inhibits inflammation while limiting mechanism-based toxicities. Here, we test a pharmacological approach by identifying small molecules that inhibit the alpha 4 integrin-paxillin interaction. By screening a large (approximately 40,000-compound) chemical library, we identified a noncytotoxic inhibitor of this interaction that impaired integrin alpha 4-mediated but not alpha L beta 2-mediated Jurkat T cell migration. The identified compound had no effect on alpha 4-mediated migration in cells bearing the alpha 4(Y991A) mutation that disrupts the alpha 4-paxillin interaction, establishing the specificity of its action. Administration of this compound to mice led to impaired recruitment of mononuclear leukocytes to a site of inflammation in vivo, whereas an isomer that does not inhibit the alpha 4-paxillin interaction had no effect on alpha 4-mediated cell migration, cell spreading, or recruitment of leukocytes to an inflammatory site. Thus, a small molecule inhibitor that interferes with alpha 4 integrin signaling reduces alpha 4-mediated T cell migration in vivo, thus providing proof of principle for inhibition of alpha 4 integrin signaling as a target for the pharmacological reduction of inflammation.
authors.affiliation: Department of Medicine, University of California at San Diego, La Jolla, California 92093.
authors.forename: Christiane
authors.initials: C
authors.lastname: Kummer
authors.affiliation: Department of Medicine, University of California at San Diego, La Jolla, California 92093.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Petrich
authors.affiliation: Department of Medicine, University of California at San Diego, La Jolla, California 92093.
authors.forename: David M
authors.initials: DM
authors.lastname: Rose
authors.affiliation: Department of Medicine, University of California at San Diego, La Jolla, California 92093. Electronic address: mhginsberg@ucsd.edu.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ginsberg
mesh_terms: D000818:Animals; D016466:CHO Cells; D002465:Cell Movement; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007249:Inflammation; D039441:Integrin alpha4 / Q000378:metabolism*; D019169:Jurkat Cells; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D051419:Paxillin / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D051419:Paxillin; D039441:Integrin alpha4