99th Dahlem Conference on Infection, Inflammation and Chronic Inflammatory Disorders: Darwinian medicine and the 'hygiene' or 'old friends' hypothesis

• Published in: Clinical and experimental immunology Vol. 160; no. 1; pp. 70 - 79
• Main Author: Rook, G.A.W
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-04-2010; Blackwell Publishing Ltd; Blackwell; Oxford University Press; Blackwell Science Inc
• Subjects: 'old friends' hypothesis; Analytical, structural and metabolic biochemistry; Animals; Atherosclerosis - immunology; Atherosclerosis - microbiology; Bacteria - immunology; Biological and medical sciences; Biological Evolution; Chronic Disease; Communicable Diseases - epidemiology; Communicable Diseases - immunology; Communicable Diseases - microbiology; Darwinian medicine; dendritic cells; Depression - immunology; Depression - microbiology; Diabetes Mellitus, Type 2 - immunology; Diabetes Mellitus, Type 2 - microbiology; Epidemiology. Vaccinations; Fundamental and applied biological sciences. Psychology; Gastrointestinal Tract - immunology; Gastrointestinal Tract - microbiology; General aspects; Humans; Hygiene; hygiene hypothesis; Hypotheses; Immune system; Infectious diseases; Inflammation - epidemiology; Inflammation - immunology; Inflammation - microbiology; Life Style; Lung - immunology; Lung - microbiology; Medical research; Medical sciences; Milk, Human - immunology; Milk, Human - microbiology; Neoplasms - immunology; Neoplasms - microbiology; Neurodegenerative Diseases - immunology; Neurodegenerative Diseases - microbiology; Part III: Nutrition and Microbiome as Determinants of Chronic Inflammation; Skin - immunology; Skin - microbiology; Treg; Vitamin D; Dendritic cell; hygiene hypothesis; 'old friends' hypothesis; Biochemistry; Inflammation; Darwinian medicine; Hypothesis; Inflammatory disease; Infection; Medicine; Chronic; dendritic cells; T; Antigen presenting cell; Hygiene
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.2010.04133.x

The current synthesis of the 'hygiene hypothesis' suggests that the recent increase in chronic inflammatory disorders is at least partly attributable to immunodysregulation resulting from lack of exposure to microorganisms that have evolved an essential role in the establishment of the immune system. This document provides a background for discussion of the following propositions. 1. The essential role of these organisms is an example of 'evolved dependence'. 2. The most relevant organisms are those that co-evolved with mammals, and already accompanied early hominids in the Paleolithic. 3. More recently evolved 'childhood infections' are not likely to have evolved this role, and recent epidemiology supports this contention. 4. This mechanism is interacting with other modern environmental changes that also lead to enhanced inflammatory responses [inappropriate diet, obesity, psychological stress, vitamin D deficiency, pollution (dioxins), etc.]. 5. The range of chronic inflammatory disorders that is affected is potentially larger than usually assumed [allergies, autoimmunity, inflammatory bowel disease, but also vascular disease, some cancers, depression/anxiety (when accompanied by raised inflammatory cytokines), and perhaps neurodegenerative disorders and type 2 diabetes].