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Experimental autoimmune encephalomyelitis evolution was not modified by multiple infections with Strongyloides venezuelensis

CHIUSO-MINICUCCI, F.; VAN, D. Bui; ZORZELLA-PEZAVENTO, S. F. G.; PERES, R. S.; ISHIKAWA, L. L. W.; ROSA, L. C.; FRANCA, T. G. D.; TURATO, W. M.; AMARANTE, A. F. T.; SARTORI, A.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.28%
P>According to the hygiene hypothesis, the increased incidence of allergic and autoimmune diseases in developed countries is mainly explained by the decreased contact between the human population and certain environmental agents as lactobacillus, mycobacteria and helminths. In this study, we evaluated the effect of multiple infections with Strongyloides venezuelensis on the development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Multiple infections before EAE induction were not able to change the evolution of the disease. No alterations were observed in weight loss, clinical score and inflammation intensity at the central nervous system. The presence of significant levels of parasite-specific IgG1 but not IgG2b suggested a Th2 polarization. However, the percentage and absolute number of CD4+CD25+Foxp3+ T cells were not changed, being their levels in the spleen and lymph nodes of infected rats comparable to the ones found in normal animals. These results suggest that a Th2-polarized response without concomitant expansion of Foxp3+ regulatory T cells was not able to modify EAE progression. Even though these results do not threaten the hygiene hypothesis, they suggest that this paradigm might be an oversimplification. They also emphasize the need of a study to compare the immunoregulatory ability associated with different helminth spp.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)

Enhancement of Th1 Lung Immunity Induced by Recombinant Mycobacterium bovis Bacillus Calmette-Guerin Attenuates Airway Allergic Disease

CHRIST, Ana P.; RODRIGUEZ, Dunia; BORTOLATTO, Juliana; BORDUCCHI, Erica; KELLER, Alexandre; MUCIDA, Daniel; SILVA, Joao S.; LEITE, Luciana C. C.; RUSSO, Momtchilo
Fonte: AMER THORACIC SOC Publicador: AMER THORACIC SOC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.24%
Mycobacterium bovis Bacillus Calmette-Guerin (BCG) has been shown to down-regulate experimental allergic asthma, a finding that reinforced the hygiene hypothesis. We have previously found that recombinant BCG (rBCG) strain that express the genetically detoxified Si subunit of pertussis toxin (rBCG-S1PT) exerts an adjuvant effect that enhances Th1 responses against BCG proteins. Here we investigated the effect of this rBCG-S1PT on the classical ovalbumin-induced mouse model of allergic lung disease. We found that rBCG-S1PT was more effective than wild-type BCG in preventing Th2-mediated allergic immune responses. The inhibition of allergic lung disease was not associated with increased concentration of suppressive cytokines or with an increased number of pulmonary regulatory T cells but was positively correlated with the increase in IFN-gamma-producing T cells and T-bet expression in the lung. In addition, an IL-12-dependent mechanism appeared to be important to the inhibition of lung allergic disease. The inhibition of allergic inflammation was found to be restricted to the lung because when allergen challenge was given by the intraperitoneal route, rBCG-S1PT administration failed to inhibit peritoneal allergic inflammation and type 2 cytokine production. Our work offers a nonclassical interpretation for the hygiene hypothesis indicating that attenuation of lung allergy by rBCG could be due to the enhancement of local lung Th1 immunity induced by rBCG-S1PT. Moreover...

Análise de anticorpos antiparasitários dosados em soro sanguíneo e sua relação com a presença de bandas oligoclonais em pacientes com esclerose múltipla; Analysis of antiparasitic antibodies measured In Blood serum and their selationship with the presence of oligoclonal bands in patients with multiple Sclerosis

Papavero, Fabiana Cruz Gomes da Fonseca
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/06/2013 PT
Relevância na Pesquisa
46.09%
Introdução: A frequência de detecção de bandas oligoclonais (BOC) em doentes com esclerose múltipla (EM) na cidade de São Paulo é significativamente mais baixa do que em outras cidades do Brasil e de outros países, principalmente da Europa e da América do Norte. Não se conhece o motivo pelo qual isso ocorre. Uma das hipóteses mais interessantes relacionada à imunopatogenia da EM é a chamada Hipótese Higiênica, que postula uma relação inversamente proporcional entre a prevalência de infecções por parasitas e a frequência da EM. Objetivo: verificar se há relação entre a ocorrência de anticorpos contra parasitas no soro sanguíneo e a detecção de BOC em pacientes diagnosticados com EM na cidade de São Paulo. Métodos: Foram estudados 164 pacientes do Ambulatório de Doenças Desmielinizantes da Divisão de Neurologia Clínica e da Divisão de Anestesia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo dos quais foram obtidas as amostras de LCR e de soro em que foi realizado este estudo. Esses pacientes foram separados em 4 grupos (EM, CIS, Grupo Controle com Pacientes de DNI e Grupo Controle com Pacientes sem Queixas Neurológicas) nos quais foram identificadas as presenças de BOC e de anticorpos parasitários. Para a detecção de anticorpos parasitários...

Experimental autoimmune encephalomyelitis evolution was not modified by multiple infections with Strongyloides venezuelensis

Chiuso-Minicucci, F.; Bui Van, D.; Zorzella-Pezavento, S. F. G.; Peres, R. S.; Ishikawa, L. L. W.; Rosa, L. C.; Franca, T. G. D.; Turato, W. M.; Amarante, Alessandro Francisco Talamini do; Sartori, Alexandrina
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 303-308
ENG
Relevância na Pesquisa
46.24%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); P>According to the hygiene hypothesis, the increased incidence of allergic and autoimmune diseases in developed countries is mainly explained by the decreased contact between the human population and certain environmental agents as lactobacillus, mycobacteria and helminths. In this study, we evaluated the effect of multiple infections with Strongyloides venezuelensis on the development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Multiple infections before EAE induction were not able to change the evolution of the disease. No alterations were observed in weight loss, clinical score and inflammation intensity at the central nervous system. The presence of significant levels of parasite-specific IgG1 but not IgG2b suggested a Th2 polarization. However, the percentage and absolute number of CD4+CD25+Foxp3+ T cells were not changed, being their levels in the spleen and lymph nodes of infected rats comparable to the ones found in normal animals. These results suggest that a Th2-polarized response without concomitant expansion of Foxp3+ regulatory T cells was not able to modify EAE progression. Even though these results do not threaten the hygiene hypothesis...

Bactérias e aumento da prevalência das doenças atópicas e auto-imunes

Monteiro, T.
Fonte: Revista Nascer & Crescer Publicador: Revista Nascer & Crescer
Tipo: Artigo de Revista Científica
Publicado em //2005 POR
Relevância na Pesquisa
46.09%
RESUMO Nas últimas décadas assistimos a uma marcada redução da morbilidade e mortalidade infantil e da população em geral, particularmente pela redução das doenças infecciosas devido à sua prevenção e cura. Mas a redução das doenças infecciosas correlacionou – se inversamente com as doenças do foro imunológico, atópicas e auto – imunes. Este trabalho, de revisão da literatura, pretende levar aos leitores algumas razões desta constatação epidemiológica, particularmente as do aumento da prevalência das doenças atópicas. Abordamos resumidamente o mecanismo imunológico das doenças atópicas e auto – imunes, a influência das doenças infecciosa sobre estas, a conhecida hipótese da higiene, e a perspectiva que se abre para se controlar a ascensão das doenças do foro imunológico, nomeadamente, pela manipulação da flora intestinal, a nossa maior barreira imunológica, incluindo o tipo de parto. SUMMARY In the last decades we assist to an accentuated decrease of the morbility and mortality in children and in general population, namely due to progression in the control of infectious diseases. But as the infections decrease, autoimmune and allergic diseases increase. The present work intends a literature review about those epidemiologic facts...

Antiparasitic antibodies occur with similar frequency in patients with clinically established multiple sclerosis with or without oligoclonal bands in the cerebrospinal fluid

Fonseca-Papavero,Fabiana Cruz Gomes da; Callegaro,Dagoberto; Gama,Paulo Diniz da; Livramento,Jose Antonio; Vaz,Adelaide Jose; Machado,Luis dos Ramos
Fonte: Academia Brasileira de Neurologia - ABNEURO Publicador: Academia Brasileira de Neurologia - ABNEURO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2013 EN
Relevância na Pesquisa
46.09%
The "hygiene hypothesis" postulates an inverse relationship between the prevalence of parasitic infections and the frequency of multiple sclerosis (MS). Objective: It was to study whether antibodies against parasites could be demonstrated more frequently in blood serum from MS patients with oligoclonal bands (OCB) than from MS patients without OCB. Methods: We studied serum samples from 164 patients who had previously been analyzed to investigate OCB. Parasitic antibodies were studied through unidimensional electrophoresis of proteins on polyacrylamide gel against Taenia antigens, searching for antiparasitic specific low molecular weight antibodies and also for antiparasitic nonspecific high molecular weight antibodies. Results: Two of the 103 patients with no evidence of OCB had antibodies of low molecular weight and 59 of them had antibodies of high molecular weight. Of the 61 patients with evidence of OCB, one showed antibodies of low molecular weight and 16 showed antibodies of high molecular weight. Conclusion: Antiparasitic antibodies are detected with similar frequency in MS patients with OCB and in MS patients without OCB.

Too clean, or not too clean: the Hygiene Hypothesis and home hygiene

Bloomfield, SF; Stanwell-Smith, R; Crevel, RWR; Pickup, J
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em /04/2006 EN
Relevância na Pesquisa
36.47%
The ‘hygiene hypothesis’ as originally formulated by Strachan, proposes that a cause of the recent rapid rise in atopic disorders could be a lower incidence of infection in early childhood, transmitted by unhygienic contact with older siblings. Use of the term ‘hygiene hypothesis’ has led to several interpretations, some of which are not supported by a broader survey of the evidence. The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms. Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the ‘microbial exposure’ hypothesis, or ‘microbial deprivation’ hypothesis, as proposed for instance by Bjorksten. Avoiding the term ‘hygiene’ would help focus attention on determining the true impact of microbes on atopic diseases...

Autism, Asthma, Inflammation, and the Hygiene Hypothesis

Becker, Kevin G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.19%
Inflammation and the genes, molecules, and biological pathways that lead to inflammatory processes influence many important and disparate biological processes and disease states that are quite often not generally considered classical inflammatory or autoimmune disorders. These include development, reproduction, aging, tumor development and tumor rejection, cardiovascular pathologies, metabolic disorders, as well as neurological and psychiatric disorders. This paper compares parallel aspects of autism and inflammatory disorders with an emphasis on asthma. These comparisons include epidemiological, morphometric, molecular, and genetic aspects of both disease types, contributing to a hypothesis of autism in the context of the immune based hygiene hypothesis. This hypothesis is meant to address the apparent rise in the prevalence of autism in the population.

Review series on helminths, immune modulation and the hygiene hypothesis: The broader implications of the hygiene hypothesis

Rook, Graham A W
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /01/2009 EN
Relevância na Pesquisa
46.28%
Man has moved rapidly from the hunter–gatherer environment to the living conditions of the rich industrialized countries. The hygiene hypothesis suggests that the resulting changed and reduced pattern of exposure to microorganisms has led to disordered regulation of the immune system, and hence to increases in certain inflammatory disorders. The concept began with the allergic disorders, but there are now good reasons for extending it to autoimmunity, inflammatory bowel disease, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers. This review discusses these possibilities in the context of Darwinian medicine, which uses knowledge of evolution to cast light on human diseases. The Darwinian approach enables one to correctly identify some of the organisms that are important for the ‘Hygiene’ or ‘Old Friends’ hypothesis, and to point to the potential exploitation of these organisms or their components in novel types of prophylaxis with applications in several branches of medicine.

Is the Hygiene Hypothesis an Example of Hormesis?

Bukowski, John A.; Lewis, R. Jeffrey
Fonte: International Hormesis Society Publicador: International Hormesis Society
Tipo: Artigo de Revista Científica
Publicado em /04/2003 EN
Relevância na Pesquisa
46.24%
The “hygiene hypothesis” has been suggested to explain the rising incidence of allergic disorders in developed countries. The postulated mechanism is that infectious and/or microbial agents stimulate the immune system toward Th1 (allergy fighting) rather than Th2 (allergy promoting) response. This paper reviews the evidence related to early life infectious/microbial exposures and subsequent atopic disorders and evaluates whether these data suggest a hormetic effect. Our review indicates an insufficient and contradictory association for bacterial/viral infections, with protective effects being either absent or specific to certain infections and/or populations. Chronic, heavy parasitic burdens appear to confer protection against atopic disorders, but are associated with considerable pathology. Moreover, light parasitic burden may increase allergic responses (i.e., no “low dose” beneficial effect). In contrast, there is consistent evidence that general microbial exposures, particularly gut commensals, may be protective against allergy development, which is consistent with a hormetic effect (i.e., potentially beneficial effects at low doses and detrimental effects at high levels). Conclusion: General microbial exposures in relation to the “hygiene hypothesis” may represent a hormetic effect...

Dishing the dirt on asthma: What we can learn from poor hygiene

de Lara, Catherine; Noble, Alistair
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.24%
Allergic asthma continues to represent a huge health burden worldwide and is largely treated by non-selective immunosuppressive drugs, which often prove ineffective. The hygiene hypothesis proposes that the increased incidence of allergy and asthma in Western countries observed in the last 50 years is due to environmental changes that include improved hygiene and a lack of infections. The immunological mechanisms that must underpin such an environmental impact on immune regulation remain to be defined, making it difficult to identify specific ways of preventing development of allergy and asthma in early life. In this article we will seek to review some of the pathways that might underlie the hygiene hypothesis in an attempt to provide targets for future asthma prevention.

Autoimmunity and asthma: The dirt on the hygiene hypothesis

Mannie, Mark D
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.18%
Self peptides shape T-cell development through selectional processes in the thymus and secondary lymphoid organs to promote a diverse and balanced repertoire of conventional and regulatory T cells. Foreign proteins and their derivative peptides permeate our mucosal tissues to constitute another diverse array of peptides that may specify and diversify the mucosal T-cell repertoire. Indeed, the distinction between self peptides and environmental foreign peptides may be academic if both are present constantly within the body. The premise here is that the plethora of foreign peptides, present ubiquitously in our environment and body, form homeostatic niches to foster highly diversified repertoires of conventional and regulatory T cells that recognize persistent environmental peptides as self. Highly diversified repertoires that recognize myriads of self and environmental foreign peptides as homeostatic ligands may be critical for adaptive distinctions of friend or foe in mucosal tissues. The change from our agrarian past to the highly sterile environments of today may adversely impact the diversity and concentrations of foreign peptides that shape the mucosal T-cell repertoire. Various hygiene hypotheses postulate that the lack of factors such as infectious pathogens...

Unraveling the mystery of the hygiene hypothesis through Helicobacter pylori infection

Matsushima, Kouji; Nagai, Shigenori
Fonte: American Society for Clinical Investigation Publicador: American Society for Clinical Investigation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
Epidemiological studies have revealed an inverse association between Helicobacter pylori infection and the incidence of allergic asthma. This association is consistent with the hygiene hypothesis, which posits that exposure to microbes early in life prevents the later development of allergic diseases, and has been reproduced in mouse models of asthma. In this issue of the JCI, Oertli and colleagues report that H. pylori infection in neonates elicits tolerogenic DCs that produce IL-18, which drive the generation of Tregs that subsequently protect the mice from allergic asthma. This finding strengthens the intriguing link between pathogen exposure and allergic disease.

Associação negativa entre atopia e toxoplasmose em seres humanos

Fernandes, Jorge Fernando Carísio
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
46.09%
Segundo a hipótese da higiene, a menor exposição a infecções está associada com o aumento na prevalência de doenças alérgicas. O objetivo deste estudo foi investigar a associação entre atopia e infecção por Toxoplasma gondii (Tg) em seres humanos pela análise da resposta imune humoral e celular em pacientes atópicos e não-atópicos, soropositivos e soronegativos a T. gondii. Um total de 275 indivíduos foram avaliados e distribuídos em grupos de atópicos (n=129) e não-atópicos (n=146) com base nos marcadores de alergia (positividade em teste cutâneo de puntura a alérgenos de ácaros e ELISA para IgE específica) ou em grupos soropositivos (n=116) e soronegativos (n=159) a T. gondii de acordo com marcadores sorológicos da infecção (positividade em ELISA para IgG anti-T. gondii). Indivíduos Tg-soropositivos apresentaram menor sensibilização alergênica (37%) aos ácaros Dermatophagoides pteronyssinus (Dp) e Dermatophagoides farinae (Df) em relação aos indivíduos Tg-soronegativos (54%). A razão de chances (odds ratio, OR) de pertencer a um grupo atópico com sorologia positiva para T. gondii foi 0,50 (95% IC: 0,31-0,81; p<0,05) enquanto a associação de sorologia negativa para T. gondii e atopia resultou em OR=2...

Enfermedades Autoinmunes, tratamiento con Trichuris suis y otros helmintos

Pallardo Fern??ndez, I??igo
Fonte: Universidad de Granada. Facultad de Farmacia Publicador: Universidad de Granada. Facultad de Farmacia
Tipo: Artigo de Revista Científica
SPA
Relevância na Pesquisa
46.31%
Al profesor Francisco Bol??s, catedr??tico del Departamento de Parasitolog??a de la Facultad de Farmacia de la Universidad Complutense de Madrid, bajo cuya direcci??n he realizado el presente trabajo y aprendido mucho sobre la materia.; Objetivos. La ???Hip??tesis de la Higiene??? postula sobre los efectos inmunomoduladores inducidos por agentes infecciosos en los seres humanos. El objetivo principal de este trabajo es indagar sobre las evidencias de esa hip??tesis y sobre sus aplicaciones en el campo del tratamiento de las enfermedades autoinmunes, haciendo especial hincapi?? tanto en los mecanismos de acci??n en los que se basan estas aplicaciones como en los resultados reales obtenidos. Adem??s analizar?? la posible evoluci??n de estas terapias, especialmente a la sombra de las controversias ??ticas que surgen de la aplicaci??n de estos tratamientos en relaci??n a si es l??cito causar una infecci??n para curar otra patolog??a, como es el caso que nos ocupa.; Resultados. Actualmente existen resultados prometedores de ensayos cl??nicos sobre terapias helm??nticas aplicadas al tratamiento de enfermedades autoinmunes como son la enfermedad de Crohn y la colitis ulcerosa, resumidos en el apartado de resultados de este art??culo. Igualmente prometedora es la gran variedad de ensayos cl??nicos que actualmente est??n en curso sobre la aplicaci??n de la terapia helm??ntica al tratamiento de diversas patolog??as en las que est?? involucrado el sistema inmunol??gico...

Role of dendritic cells: a step forward for the hygiene hypothesis

Yang, Xi; Gao, Xiaoling
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.24%
The hygiene hypothesis was proposed more than two decades ago, but its mechanism remains unclear. This review focuses on recent advances in the field, especially on the role played by dendritic cells (DCs) and their modulating effects on various infections and allergic diseases, including allergic asthma. DCs isolated from mice long after the resolution of an infection were reported to have a significant modulating effect on allergen-specific Th2 responses in both in vitro and in vivo systems. These DCs showed DC1-like and/or tolerogenic DC capacity, which allowed for the inhibition of allergic responses by immune deviation (enhancing Th1 response) and immune regulation (through regulatory T-cell and Th2 hyporesponsiveness) mechanisms. These findings represented a significant advance in the elucidation of the mechanisms underlying the hygiene hypothesis. Further investigation on the mechanisms by which DCs are ‘educated' by infectious agents and the influence of the type, time, and extent of infections on this ‘education' process will help us understand immune regulation in disease settings and in the rational design of preventive/therapeutic approaches to allergy/asthma and infections.

The coming-of-age of the hygiene hypothesis

Martinez, Fernando D
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.15%
The hygiene hypothesis, as originally proposed, postulated an inverse relation between the incidence of infectious diseases in early life and the subsequent development of allergies and asthma. New evidence from epidemiological, biological and genetic studies has significantly enlarged the scope of the hypothesis. It now appears probable that environmental 'danger' signals regulate the pattern of immune responses in early life. Microbial burden in general, and not any single acute infectious illness, is the main source of these signals. The latter interact with a sensitive and complex receptor system, and genetic variations in this receptor system may be an important determinant of inherited susceptibility to asthma and allergies.

99th Dahlem Conference on Infection, Inflammation and Chronic Inflammatory Disorders: Farm lifestyles and the hygiene hypothesis

von Mutius, E
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /04/2010 EN
Relevância na Pesquisa
46.18%
About 15 years have gone by since Strachan first proposed the idea that infections and unhygienic contact may confer protection from the development of allergic illnesses. The so-called ‘hygiene hypothesis’ has since undergone numerous modifications in the field of epidemiology, clinical science and immunology. Three main areas of research have been brought forward: to explore the role of overt viral and bacterial infections for the inception of allergic diseases; to investigate the significance of environmental exposure to microbial compounds on the development of allergies; and to study the effect of both exposures on underlying innate and adaptive immune responses. A concept unifying these various aspects has not been found, but various pieces of a complex interplay between immune responses of the host, characteristics of the invading microorganism, the level and variety of the environmental exposure and the interactions between an exposed subject's genetic background and the environmental exposures becomes apparent. A natural experiment relating to the hygiene hypothesis is the recurrent observation of a protective effect of growing up on a farm for asthma and allergies. This has been shown in a large number of epidemiological studies across the world among children and adults. The timing and duration of exposure are likely to play a critical role. The largest reduction in risk has been demonstrated for those exposed prenatally and continuously thereafter until adulthood. The protective factors in these farming environments have not been unravelled completely. Findings from various studies suggest that the contact with farm animals...

Hygiene hypothesis in inflammatory bowel disease: A critical review of the literature

Koloski, Natasha A; Bret, Laurel; Radford-Smith, Graham
Fonte: The WJG Press and Baishideng Publicador: The WJG Press and Baishideng
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.43%
The hygiene hypothesis is thought to be a significant contributor to the growing incidence of inflammatory bowel disease (IBD) around the world, although the evidence for specific factors that underlie the hygiene hypothesis in IBD is unclear. We aimed to systematically review the literature to determine which hygiene-related factors are associated with the development of IBD. Publications identified from a broad based MEDLINE and Current Contents search between 1966 and 2007 on key terms relevant to the 'hygiene hypothesis' and IBD including H pylori exposure, helminths, cold chain hypothesis, measles infection and vaccination, antibiotic use, breastfeeding, family size, sibship, urban upbringing, day care attendance and domestic hygiene were reviewed. The literature suggests that the hygiene hypothesis and its association with decreased microbial exposure in childhood probably plays an important role in the development of IBD, although the strength of the supporting data for each of the factors varies considerably. The most promising factors that may potentially be associated with development of IBD include H pylori exposure, helminths, breastfeeding and sibship. However, the vast majority of studies in this area are plagued by serious methodological shortcomings...

Revisiting the hygiene hypothesis in gastrointestinal allergy

Chin, James
Fonte: Lippincott Williams & Wilkins Publicador: Lippincott Williams & Wilkins
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
66.36%
The "hygiene hypothesis" in its original form hypothesized that infection in early childhood acquired through unhygienic contact with siblings or the mother may prevent the development of allergic disease. Several recent epidemiologic surveys showing an inverse relationship between the frequency of infectious disease and the incidence of allergic diseases lend support to this hypothesis. Allergen sensitization of the immune system can occur early in utero against a background of neonatal commitment to a Th2 immune response involving the production of Th2 cytokines (eg, interleukin (IL)-4, IL-5, IL-13) that are the principal mediators of allergic inflammation. Continued allergen exposure is associated with predominantly CD4+ Th2 cell proliferation but does not exclude a minor Th1 allergen-specific subpopulation that can be further expanded nonspecifically and polyclonally by microbial superantigens or as bystanders, by interferon-gamma (IFN-γ) and IL-2 released from Th1 effectors responding to antigens associated with infectious pathogens. Th1 cytokines can also subvert allergen-specific Th2 lymphocytes to become allergen-specific Th1 cells - a process reminiscent of the increased tendency of the maturing immune system of growing adults to mount a Th1 response to some environmental and dietary antigens. Unlike Th2 cytokines...