title: Potentiation of immunological tolerance induction in adult mice by co-administration of pooled normal IgG and oral tolerogens: a potential therapeutic approach for autoimmune diseases.
abstract: Oral tolerance can be defined as the inability of an adult animal to produce specific antibodies or cellular immune responses upon conventional immunization, after oral antigenic administration. Recently, the oral administration of antigens has gained renewed interest because of the possibility of inducing tolerance in nonimmunized adult animals and, consequently, opening up the theoretical possibility of preventing or treating diseases caused by malfunction of the immune system. This strategy has been proven to be useful in the prevention of allergic and autoimmune diseases in rodents, as well as in the amelioration of certain autoimmune diseases in humans. Although there is experimental and clinical evidence for the usefulness of oral tolerance in medical practice, the mechanisms responsible for this phenomenon are still poorly understood, and the results obtained are not always satisfactory. Herein, we show that the thymus is required for the induction and maintenance of oral tolerance, providing evidence that it is not a pure form of clonal deletion-based peripheral tolerance. Oral tolerance could therefore depend on the formation and release to the periphery of regulatory T cells, such as gammadelta or alphabeta T cells, by the thymus. This finding may have profound implications for the treatment of autoimmune diseases, since most of them are associated with thymic hypofunction. On the other hand, due to so far unknown mechanisms, the intraperitoneal co-administration of normal IgG to mice orally treated with tolerogen leads to a sustained and intense immunological tolerance, both in euthymic and thymectomized mice, including those of the lupus erythematosus-prone NZB x NZW lineage. This approach for inducing and maintaining tolerance in thymus-deficient conditions is discussed and put forth herein as a new evidence-based proposition for the therapy of autoimmune diseases.
authors.affiliation: Department of Immunology, Institute for Biomedical Sciences IV, University of São Paulo, Av. Prof. Lineu Prestes 1730, CEP 05508-900, São Paulo. jomengel@cpqgm.fiocruz.br
authors.forename: José
authors.initials: J
authors.lastname: Mengel
authors.forename: Patrícia
authors.initials: P
authors.lastname: Fávaro
authors.forename: André
authors.initials: A
authors.lastname: Meyer
authors.forename: Vinícius
authors.initials: V
authors.lastname: Motta
authors.forename: Raquel
authors.initials: R
authors.lastname: de Alencar
authors.forename: Edilberto
authors.initials: E
authors.lastname: Postól
authors.forename: Fabíola
authors.initials: F
authors.lastname: Cardillo
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology / Q000628:therapy*; D007108:Immune Tolerance; D007074:Immunoglobulin G / Q000008:administration & dosage*; D008212:Lymphocyte Depletion; D008231:Lymphopenia / Q000276:immunology / Q000628:therapy; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology
chemical_list: D007074:Immunoglobulin G