title: Experimental immunization with anti-rheumatic bacterial extract OM-89 induces T cell responses to heat shock protein (hsp)60 and hsp70; modulation of peripheral immunological tolerance as its possible mode of action in the treatment of rheumatoid arthritis (RA).
abstract: OM-89 is a bacterial (Escherichia coli) extract used for oral administration in the treatment of RA. Given the evidence that immunity to bacterial heat shock antigens plays a critical role in the immunomodulation of arthritis and possibly inflammation in general, the purpose of the present studies was to evaluate the presence and immunogenicity of hsp in OM-89. Furthermore, we studied the effects of OM-89 in an experimental arthritis, where hsp are known to have a critical significance in disease development. In rats immunization with OM-89 was found to lead to proliferative T cell responses to hsp60 and hsp70 of both E. coli and mycobacterial origin. Conversely, immunization with hsp antigens was also found to induce T cell reactivity specific for OM-89. Based on this and the antigen specificity analysis of specific T cell lines, hsp70(DnaK) turned out to be one of the major immunogenic constituents of OM-89. Parenteral immunization with OM-89 was found to reduce resistance to adjuvant arthritis (AA), whereas oral administration was found to protect against AA. Given the arthritis-inhibitory effect of oral OM-89 in AA, it is possible that peripheral tolerance is induced at the level of regulatory T cells with specificity for hsp. This may also constitute a mode of action for OM-89 as an arthritis-suppressive oral drug.
authors.affiliation: Institute of Infectious Diseases and Immunology, Utrecht University, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Bloemendal
authors.forename: R
authors.initials: R
authors.lastname: Van der Zee
authors.forename: V P
authors.initials: VP
authors.lastname: Rutten
authors.forename: P J
authors.initials: PJ
authors.lastname: van Kooten
authors.forename: J C
authors.initials: JC
authors.lastname: Farine
authors.forename: W
authors.initials: W
authors.lastname: van Eden
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000008:administration & dosage* / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology*; D018834:Chaperonin 60 / Q000276:immunology*; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology*; D007108:Immune Tolerance; D007114:Immunization; D007166:Immunosuppressive Agents / Q000008:administration & dosage* / Q000276:immunology; D008297:Male; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D007166:Immunosuppressive Agents; C050501:OM 89