title: Immunosuppressive effects of the heat shock protein 90-binding antibiotic geldanamycin.
abstract: Ansamycin antibiotic, geldanamycin has a unique pharmacological effect to bind to heat shock protein 90 (hsp90) and deplete hsp90 substrates. We investigated the immunopharmacological effects of geldanamycin. Geldanamycin depleted cellular Raf-1 of rat splenic cells without affecting the steady state levels of hsp90 and downstream mitogen activated protein (MAP) kinases, ERK1 and ERK2. In parallel, it inhibited mitogen-induced nuclear factor-kappa B (NF-kappa B) activation in these cells. Geldanamycin also had a potent suppressive effect on recall antigen-induced T cell proliferation, with an IC50 value of 1 nM. In vivo, geldanamycin suppressed the progression of adjuvant-induced arthritis dose-dependently. These results suggest that geldanamycin exerts an immunosuppressive effect partly through destabilizing Raf-1, and raise a new strategy for the prevention of inflammatory diseases.
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D001169:Arthritis, Experimental / Q000188:drug therapy / Q000276:immunology; D016227:Benzoquinones; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004195:Disease Models, Animal; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D007166:Immunosuppressive Agents / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D047029:Lactams, Macrocyclic; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D011809:Quinones / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*