The immunology of the allergy epidemic and the hygiene hypothesis


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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Figure 1: Protective and risk factors for allergy development in early life.
Figure 2: The epithelium as the rheostat of the allergic response.


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B.N.L. and H.H. are supported by Ghent University (Concerted Research Initiative (GOA) grant) and by the Scientific Research Foundation Flanders (FWO).

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Correspondence to Bart N Lambrecht or Hamida Hammad.

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Lambrecht, B., Hammad, H. The immunology of the allergy epidemic and the hygiene hypothesis. Nat Immunol 18, 1076–1083 (2017).

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