Microorganisms and autoimmunity: making the barren field fertile?
Microorganisms induce strong immune responses, most of which are specific for their encoded antigens. However, microbial infections can also trigger responses against self antigens (autoimmunity), and it has been proposed that this phenomenon could underlie several chronic human diseases, such as type 1 diabetes and multiple sclerosis. Nevertheless, despite intensive efforts, it has proven difficult to identify any single microorganism as the cause of a human autoimmune disease, indicating that the 'one organism-one disease' paradigm that is central to Koch's postulates might not invariably apply to microbially induced autoimmune disease. Here, we review the mechanisms by which microorganisms might induce autoimmunity, and we outline a hypothesis that we call the fertile-field hypothesis to explain how a single autoimmune disease could be induced and exacerbated by many different microbial infections.
von Herrath
Matthias G
MG
Division of Developmental Immunology, Immune Regulation Laboratory, La Jolla Institute for Allergy and Immunology, 10355 Science Centre Drive, San Diego, California 92121, USA. matthias@liai.org
Fujinami
Robert S
RS
Whitton
J Lindsay
JL
D000818:Animals; D001327:Autoimmune Diseases / Q000209:etiology*; D015551:Autoimmunity; D024201:Bystander Effect; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D013601:T-Lymphocytes / Q000276:immunology; D014777:Virus Diseases / Q000150:complications* / Q000276:immunology*