Pathogen induced regulatory cell populations preventing allergy through the Th1/Th2 paradigm point of view
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Pathogen induced regulatory cell populations preventing allergy through the Th1/Th2 paradigm point of view Thomas Roumier Æ Monique Capron Æ David Dombrowicz Æ Christelle Faveeuw
Published online: 15 May 2007 Ó Humana Press Inc. 2007
Abstract Epidemiological studies have demonstrated an inverse correlation between prevalence of helminth infections and allergic diseases both associated to Th2 immune responses. On the other hand, such an inverse correlation has also been evidenced between allergies and bacterial infections, associated to Th1 responses. In this review, we will examine and compare the various mechanisms by which Th1- or Th2-inducing infectious agents regulate the development of atopic diseases. We will emphasize the key role of various regulatory cell populations associated to the immune responses toward pathogen. Keywords Regulatory cell Allergy Parasite Th1/Th2 paradigm Hygiene hypothesis Abbreviations Foxp3 Forkhead box P3, member of the forkhead/winged-helix family of transcriptional regulators
Introduction High and increasing incidence of allergic pathologies in industrialized countries strikingly contrasts with the relative paucity of these diseases in developing countries. This fact was correlated to the high prevalence of parasite infections, in particular due to helminths, among other belonging to Schistosoma genus, the causal agent of schistosomiasis. These
D.D. and C.F. contributed equally to this work T. Roumier M. Capron D. Dombrowicz (&) C. Faveeuw Inserm U547 – Univ. Lille 2 – Institut Pasteur de Lille, 1, rue du Professeur Calmette, Lille 59019, France e-mail: [email protected]
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Immunol Res (2008) 40:1–17
two pathologies are generally associated to a Th2 type cytokine profile, high IgE concentrations and eosinophilia [1]. Based on these similarities, it was for a long time considered, without providing with a convincing explanatory mechanism, that in the virtual absence of parasite infections as it is the case in most western countries, the anti-helminth immune responses, involving Th2 responses have been diverted, due to the lack of use, towards deleterious responses against harmless environment of food antigens. On another hand, in a groundbreaking study performed on Japanese children, Shirakawa et al. demonstrated an inverse correlation between the intensity of tuberculin reaction, reflecting a Th1 response, and the likelihood to later develop an atopic disease and high IgE concentrations [2]. This observation led to the conclusion that development of significant Th1 responses toward more or less virulent pathogens, such as mycobacteria, was preventing the later onset of allergic diseases. Due to the systematic vaccination against infectious agents, such as Mycobacterium tuberculosis [2], as well as the use of antibiotics in early childhood [3], this protective effect would have disappeared in industrialized countries. Exposure to pro-Th1 infectious agents in the early childhood, when immune responses are naturally Th2-biaised [4] would prevent th
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