The Experts below are selected from a list of 5922 Experts worldwide ranked by ideXlab platform
Hamida Hammad - One of the best experts on this subject based on the ideXlab platform.
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the Hygiene Hypothesis immunological mechanisms of airway tolerance
Current Opinion in Immunology, 2018Co-Authors: Eline Haspeslagh, Ines Heyndrickx, Hamida Hammad, Bart N LambrechtAbstract:The Hygiene Hypothesis was initially proposed as an explanation for the alarming rise in allergy prevalence in the last century. The immunological idea behind this Hypothesis was a lack of infections associated with a Western lifestyle and a consequential reduction in type 1 immune responses. It is now understood that the development of tolerance to allergens depends on microbial colonization and immunostimulatory environmental signals during early-life or passed on by the mother. These environmental cues are sensed and integrated by barrier epithelial cells of the lungs and possibly skin, which in turn instruct dendritic cells to regulate or impede adaptive T cell responses. Recent reports also implicate immunoregulatory macrophages as powerful suppressors of allergy by the microbiome. We propose that loss of adequate microbial stimulation due to a Western lifestyle may result in hypersensitive barrier tissues and the observed rise in type 2 allergic disease.
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a gammaherpesvirus provides protection against allergic asthma by inducing the replacement of resident alveolar macrophages with regulatory monocytes
Nature Immunology, 2017Co-Authors: Benedicte Machiels, Mickael Dourcy, Xue Xiao, Justine Javaux, Claire Mesnil, Catherine Sabatel, Daniel Desmecht, Francois Lallemand, Philippe Martinive, Hamida HammadAbstract:The Hygiene Hypothesis postulates that the recent increase in allergic diseases such as asthma and hay fever observed in Western countries is linked to reduced exposure to childhood infections. Here we investigated how infection with a gammaherpesvirus affected the subsequent development of allergic asthma. We found that murid herpesvirus 4 (MuHV-4) inhibited the development of house dust mite (HDM)-induced experimental asthma by modulating lung innate immune cells. Specifically, infection with MuHV-4 caused the replacement of resident alveolar macrophages (AMs) by monocytes with regulatory functions. Monocyte-derived AMs blocked the ability of dendritic cells to trigger a HDM-specific response by the TH2 subset of helper T cells. Our results indicate that replacement of embryonic AMs by regulatory monocytes is a major mechanism underlying the long-term training of lung immunity after infection.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:Lambrecht and Hammad discuss how microbial diversity or dysbiosis influences epithelial barrier tissues and the impact of such interactions on the development of allergic disease.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:The immunology of the Hygiene Hypothesis of allergy is complex and involves the loss of cellular and humoral immunoregulatory pathways as a result of the adoption of a Western lifestyle and the disappearance of chronic infectious diseases. The influence of diet and reduced microbiome diversity now forms the foundation of scientific thinking on how the allergy epidemic occurred, although clear mechanistic insights into the process in humans are still lacking. Here we propose that barrier epithelial cells are heavily influenced by environmental factors and by microbiome-derived danger signals and metabolites, and thus act as important rheostats for immunoregulation, particularly during early postnatal development. Preventive strategies based on this new knowledge could exploit the diversity of the microbial world and the way humans react to it, and possibly restore old symbiotic relationships that have been lost in recent times, without causing disease or requiring a return to an unhygienic life style.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:Lambrecht and Hammad discuss how microbial diversity or dysbiosis influences epithelial barrier tissues and the impact of such interactions on the development of allergic disease. The immunology of the Hygiene Hypothesis of allergy is complex and involves the loss of cellular and humoral immunoregulatory pathways as a result of the adoption of a Western lifestyle and the disappearance of chronic infectious diseases. The influence of diet and reduced microbiome diversity now forms the foundation of scientific thinking on how the allergy epidemic occurred, although clear mechanistic insights into the process in humans are still lacking. Here we propose that barrier epithelial cells are heavily influenced by environmental factors and by microbiome-derived danger signals and metabolites, and thus act as important rheostats for immunoregulation, particularly during early postnatal development. Preventive strategies based on this new knowledge could exploit the diversity of the microbial world and the way humans react to it, and possibly restore old symbiotic relationships that have been lost in recent times, without causing disease or requiring a return to an unhygienic life style.
Jeanfrancois Bach - One of the best experts on this subject based on the ideXlab platform.
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the Hygiene Hypothesis in autoimmunity the role of pathogens and commensals
Nature Reviews Immunology, 2018Co-Authors: Jeanfrancois BachAbstract:The Hygiene Hypothesis postulates that an increased frequency of infections contributes to a decrease in autoimmune and allergic diseases. Here, Bach summarizes the epidemiological and experimental evidence supporting this Hypothesis and discusses the importance of innate immune receptors in mediating the protective effect of pathogens and commensals on autoimmunity.
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the Hygiene Hypothesis for autoimmune and allergic diseases an update
Clinical and Experimental Immunology, 2010Co-Authors: H Okada, C Kuhn, H Feillet, Jeanfrancois BachAbstract:According to the ‘Hygiene Hypothesis’, the decreasing incidence of infections in western countries and more recently in developing countries is at the origin of the increasing incidence of both autoimmune and allergic diseases. The Hygiene Hypothesis is based upon epidemiological data, particularly migration studies, showing that subjects migrating from a low-incidence to a high-incidence country acquire the immune disorders with a high incidence at the first generation. However, these data and others showing a correlation between high disease incidence and high socio-economic level do not prove a causal link between infections and immune disorders. Proof of principle of the Hygiene Hypothesis is brought by animal models and to a lesser degree by intervention trials in humans. Underlying mechanisms are multiple and complex. They include decreased consumption of homeostatic factors and immunoregulation, involving various regulatory T cell subsets and Toll-like receptor stimulation. These mechanisms could originate, to some extent, from changes in microbiota caused by changes in lifestyle, particularly in inflammatory bowel diseases. Taken together, these data open new therapeutic perspectives in the prevention of autoimmune and allergic diseases.
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the effect of infections on susceptibility to autoimmune and allergic diseases
The New England Journal of Medicine, 2002Co-Authors: Jeanfrancois BachAbstract:The Hygiene Hypothesis postulates that an environment with a high incidence of infectious diseases protects against allergic and autoimmune diseases, whereas hygienic surroundings increase the incidence of these disorders. This review examines the evidence in support of the Hygiene Hypothesis and offers a number of mechanisms that could explain the relation between sanitary conditions and susceptibility to allergic and autoimmune diseases.
Bart N Lambrecht - One of the best experts on this subject based on the ideXlab platform.
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the Hygiene Hypothesis immunological mechanisms of airway tolerance
Current Opinion in Immunology, 2018Co-Authors: Eline Haspeslagh, Ines Heyndrickx, Hamida Hammad, Bart N LambrechtAbstract:The Hygiene Hypothesis was initially proposed as an explanation for the alarming rise in allergy prevalence in the last century. The immunological idea behind this Hypothesis was a lack of infections associated with a Western lifestyle and a consequential reduction in type 1 immune responses. It is now understood that the development of tolerance to allergens depends on microbial colonization and immunostimulatory environmental signals during early-life or passed on by the mother. These environmental cues are sensed and integrated by barrier epithelial cells of the lungs and possibly skin, which in turn instruct dendritic cells to regulate or impede adaptive T cell responses. Recent reports also implicate immunoregulatory macrophages as powerful suppressors of allergy by the microbiome. We propose that loss of adequate microbial stimulation due to a Western lifestyle may result in hypersensitive barrier tissues and the observed rise in type 2 allergic disease.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:Lambrecht and Hammad discuss how microbial diversity or dysbiosis influences epithelial barrier tissues and the impact of such interactions on the development of allergic disease.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:The immunology of the Hygiene Hypothesis of allergy is complex and involves the loss of cellular and humoral immunoregulatory pathways as a result of the adoption of a Western lifestyle and the disappearance of chronic infectious diseases. The influence of diet and reduced microbiome diversity now forms the foundation of scientific thinking on how the allergy epidemic occurred, although clear mechanistic insights into the process in humans are still lacking. Here we propose that barrier epithelial cells are heavily influenced by environmental factors and by microbiome-derived danger signals and metabolites, and thus act as important rheostats for immunoregulation, particularly during early postnatal development. Preventive strategies based on this new knowledge could exploit the diversity of the microbial world and the way humans react to it, and possibly restore old symbiotic relationships that have been lost in recent times, without causing disease or requiring a return to an unhygienic life style.
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the immunology of the allergy epidemic and the Hygiene Hypothesis
Nature Immunology, 2017Co-Authors: Bart N Lambrecht, Hamida HammadAbstract:Lambrecht and Hammad discuss how microbial diversity or dysbiosis influences epithelial barrier tissues and the impact of such interactions on the development of allergic disease. The immunology of the Hygiene Hypothesis of allergy is complex and involves the loss of cellular and humoral immunoregulatory pathways as a result of the adoption of a Western lifestyle and the disappearance of chronic infectious diseases. The influence of diet and reduced microbiome diversity now forms the foundation of scientific thinking on how the allergy epidemic occurred, although clear mechanistic insights into the process in humans are still lacking. Here we propose that barrier epithelial cells are heavily influenced by environmental factors and by microbiome-derived danger signals and metabolites, and thus act as important rheostats for immunoregulation, particularly during early postnatal development. Preventive strategies based on this new knowledge could exploit the diversity of the microbial world and the way humans react to it, and possibly restore old symbiotic relationships that have been lost in recent times, without causing disease or requiring a return to an unhygienic life style.
Anita L Kozyrskyj - One of the best experts on this subject based on the ideXlab platform.
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infant gut microbiota and the Hygiene Hypothesis of allergic disease impact of household pets and siblings on microbiota composition and diversity
Allergy Asthma & Clinical Immunology, 2013Co-Authors: Meghan B Azad, Theodore Konya, Heather Maughan, David S Guttman, Catherine J Field, Malcolm R Sears, Allan B Becker, James A Scott, Anita L KozyrskyjAbstract:Multiple studies have demonstrated that early-life exposure to pets or siblings affords protection against allergic disease; these associations are commonly attributed to the “Hygiene Hypothesis”. Recently, low diversity of the infant gut microbiota has also been linked to allergic disease. In this study, we characterize the infant gut microbiota in relation to pets and siblings. The study population comprised a small sub-sample of 24 healthy, full term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort. Mothers reported on household pets and siblings. Fecal samples were collected at 4 months of age, and microbiota composition was characterized by high-throughput signature gene sequencing. Microbiota richness and diversity tended to be increased in infants living with pets, whereas these measures were decreased in infants with older siblings. Infants living with pets exhibited under-representation of Bifidobacteriaceae and over-representation of Peptostreptococcaceae; infants with older siblings exhibited under-representation of Peptostreptococcaceae. This study provides new evidence that exposure to pets and siblings may influence the early development of the gut microbiota, with potential implications for allergic disease. These two traditionally protective “Hygiene Hypothesis” factors appear to differentially impact gut microbiota composition and diversity, calling into question the clinical significance of these measures. Further research is required to confirm and expand these findings.
Meghan B Azad - One of the best experts on this subject based on the ideXlab platform.
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erratum the Hygiene Hypothesis the covid pandemic and consequences for the human microbiome proceedings of the national academy of sciences of the united states of america 2021 118 e2010217118 doi 10 1073 pnas 2010217118
Proceedings of the National Academy of Sciences of the United States of America, 2021Co-Authors: Brett B Finlay, Meghan B Azad, Martin J Blaser, Katherine R Amato, Thomas C G Bosch, Hiutung Chu, Maria Gloria Dominguezbello, Stanislav Dusko Ehrlich, Eran Elinav, Naama GevazatorskyAbstract:MICROBIOLOGY: Correction for "The Hygiene Hypothesis, the COVID pandemic, and consequences for the human microbiome," by B Brett Finlay, Katherine R Amato, Meghan Azad, Martin J Blaser, Thomas C G Bosch, Hiutung Chu,Maria Gloria Dominguez-Bello, Stanislav Dusko Ehrlich, Eran Elinav, Naama Geva-Zatorsky, Philippe Gros, Karen Guillemin, Frederic Keck, Tal Korem, Margaret J McFall-Ngai, Melissa K Melby, Mark Nichter, Sven Pettersson, Hendrik Poinar, Tobias Rees, Carolina Tropini, Liping Zhao, and Tamara Giles-Vernick, which was first published January 20, 2021;10 1073/ pnas 2010217118 (Proc Natl Acad Sci U S A 118, e2010217118) The authors note that reference 77 appeared incorrectly It should instead appear as: 77 S E Sullivan, L A Thompson, Best practices for COVID-19-positive or exposed mothers-Breastfeeding and pumping milk JAMA Pediatr 174, 1228 (2020) The online version has been corrected © 2021 National Academy of Sciences All rights reserved
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infant gut microbiota and the Hygiene Hypothesis of allergic disease impact of household pets and siblings on microbiota composition and diversity
Allergy Asthma & Clinical Immunology, 2013Co-Authors: Meghan B Azad, Theodore Konya, Heather Maughan, David S Guttman, Catherine J Field, Malcolm R Sears, Allan B Becker, James A Scott, Anita L KozyrskyjAbstract:Multiple studies have demonstrated that early-life exposure to pets or siblings affords protection against allergic disease; these associations are commonly attributed to the “Hygiene Hypothesis”. Recently, low diversity of the infant gut microbiota has also been linked to allergic disease. In this study, we characterize the infant gut microbiota in relation to pets and siblings. The study population comprised a small sub-sample of 24 healthy, full term infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort. Mothers reported on household pets and siblings. Fecal samples were collected at 4 months of age, and microbiota composition was characterized by high-throughput signature gene sequencing. Microbiota richness and diversity tended to be increased in infants living with pets, whereas these measures were decreased in infants with older siblings. Infants living with pets exhibited under-representation of Bifidobacteriaceae and over-representation of Peptostreptococcaceae; infants with older siblings exhibited under-representation of Peptostreptococcaceae. This study provides new evidence that exposure to pets and siblings may influence the early development of the gut microbiota, with potential implications for allergic disease. These two traditionally protective “Hygiene Hypothesis” factors appear to differentially impact gut microbiota composition and diversity, calling into question the clinical significance of these measures. Further research is required to confirm and expand these findings.
