Trop d'hygiène : négatif pour l'immunité?

[Nutrimuscle-Conseils]

Microbial exposures that establish immunoregulation are compatible with targeted hygiene
Graham A.W. Rook, The Journal of Allergy and Clinical Immunology 148, ISSUE 1, P33-39, JULY 01, 2021

It is often suggested that hygiene is not compatible with the microbial exposures that are necessary for establishment of the immune system in early life. However, when we analyze the microbial exposures of modern humans in the context of human evolution and history, it becomes evident that whereas children need exposure to the microbiotas of their mothers, other family members, and the natural environment, exposure to the unnatural microbiota of the modern home is less relevant. In addition, any benefits of exposure to the infections of childhood within their household setting are at least partly replaced by the recently revealed nonspecific effects of vaccines.

This article shows how targeting hygiene practices at key risk moments and sites can maximize protection against infection while minimizing any impact on essential microbial exposures. Moreover, this targeting must aim to reduce direct exposure of children to cleaning agents because those agents probably exert TH2-adjuvant effects that trigger allergic responses to normally innocuous antigens. Finally, we need to halt the flow of publications in the scientific literature and the media that blame hygiene for the increases in immunoregulatory disorders. Appropriately targeted hygiene behavior is compatible with a healthy lifestyle that promotes exposure to essential microorganisms.

[Nutrimuscle-Diététique]

Traduction de l'étude

Les expositions microbiennes qui établissent l'immunorégulation sont compatibles avec une hygiène ciblée
Graham A.W. Rook, The Journal of Allergy and Clinical Immunology 148, NUMÉRO 1, P33-39, 01 JUILLET 2021

Il est souvent suggéré que l'hygiène n'est pas compatible avec les expositions microbiennes qui sont nécessaires à l'établissement du système immunitaire au début de la vie. Cependant, lorsque nous analysons les expositions microbiennes de l'homme moderne dans le contexte de l'évolution et de l'histoire humaines, il devient évident que, tandis que les enfants ont besoin d'être exposés au microbiote de leur mère, d'autres membres de la famille et de l'environnement naturel, l'exposition au microbiote non naturel de la maison moderne est moins pertinente. De plus, tous les avantages de l'exposition aux infections de l'enfance au sein de leur foyer sont au moins en partie remplacés par les effets non spécifiques récemment révélés des vaccins.

Cet article montre comment le ciblage des pratiques d'hygiène à des moments et des sites à risque peut maximiser la protection contre les infections tout en minimisant tout impact sur les expositions microbiennes essentielles. De plus, ce ciblage doit viser à réduire l'exposition directe des enfants aux agents nettoyants car ces agents exercent probablement des effets adjuvants TH2 qui déclenchent des réponses allergiques à des antigènes normalement inoffensifs. Enfin, il faut arrêter le flot de publications dans la littérature scientifique et les médias qui accusent l'hygiène d'être à l'origine de l'augmentation des troubles immunorégulateurs. Un comportement d'hygiène bien ciblé est compatible avec un mode de vie sain qui favorise l'exposition aux micro-organismes essentiels.

[Nutrimuscle-Conseils]

Impact of the environment on gut microbiome and allergy
BMJ Nutrition, Prevention & Health Christina E West;

Rapid urbanisation and global biodiversity loss are changing human microbial ecology, which is accelerated by the progressive loss of protective factors for example, contact with natural environments and animals, and less consumption of traditional foods. Early life represents a critical window both for optimal colonisation and immune system development. The frequency of caesarean section (CS) delivery is high and increasing in many parts of the world, and there is strong evidence that CS delivery has a marked influence on early colonisation, with depletion of strains of commensal bacteria. Colonisation of human ecological niches, particularly the gastrointestinal tract, parallels normal local and systemic immune development. CS delivery has been associated with increased risk of allergic diseases and there is emerging evidence that this is mediated by alterations of the microbiome. Small proof-of-concept studies have demonstrated that transfer of maternal vaginal microbes directly after elective CS delivery partially restores the offspring microbiome but transfer of maternal faecal microbes is needed for restoration of the offspring gut microbiome. Randomised clinical trials (RCTs) using microbiome seeding after CS delivery are underway and are anticipated to unravel if this procedure will impact microbial, immunological and metabolic programming, and decrease allergy risk. RCTs using prebiotics and probiotics for primary prevention of allergic diseases (primarily eczema) have been conducted, but large heterogeneity between studies have hampered meta-analysis and the development of specific practice guidelines.

In the first RCT to test the biodiversity hypothesis, exposure to playground sand with added microbially diverse soil, led to shifts in the skin and gut bacterial communities and increases in immunoregulatory biomarkers compared with exposure to microbially poor sand (placebo). Collectively, appropriate health-supporting microbial exposures by optimised nutrition and a microbially diverse environment in early life may curb the epidemic rise in allergic diseases, however, considerably more research is needed before this can be translated into specific practice guidelines.