Editorial: The Role of the Microbiome in Regulating T-Cell Response in Asthma and Food Allergy

Abstract

The role and importance of the microbiome for human health has been investigated in recent years (1, 2). A dysbiosis of the gut microbiome has been shown to cause drastic changes in the immune system (3, 4) Leading to disbalance of immune homeostasis and consequently to the emergence of different diseases (5, 6). In this editorial, we investigate the role of microbiome in regulating immune response in Asthma and Food Allergy. The interplay between gut and lung as two separate organs has been introduced previously (7– 10). In their review, Di Gangi et al. have explored this concept and investigated the importance of gut microbiota in protection or augmentation of allergic asthma. Click or tap here to enter text.The authors shed light on the importance of Lactobacillus spp as an important part of the human gut microflora (11). Data from clinical cohorts hint towards a link between microbial dysbiosis and asthma risk in children. They review the findings from e.g. the PASTURE, EFRAIM and WHEALS cohorts. These studies show a protective effect of farm-exposure on asthma risk in children early in life with higher Treg numbers in peripheral blood of children consuming farm-milk (12, 13). Key findings of the WHEALS study include a delayed diversification of the gut microbiota and a relative difference in the composition with fewer Lactobacillus, Bifidobacterium, Akkermisia and Faecalibacterium and more Candida spp (14). The protective effect, however, was not lasting. The reasons for this phenomenon are not understood. Collectively, there has been much research focusing on the role of microbiota in the development of asthma. The “Hygiene hypothesis” has put a lot of value on how bacterial species and bacterial metabolites are protective against asthma and allergy development. In that sense, Hagner and Harb et al. showed a protective effect of different microbial species, either isolated from cow shed or used as prebiotics, against the development of different hallmarks of allergic airway inflammation in mice (11, 15). These protective effects were transferred from mothers to offspring via TLR activation and signaling in the mothers exposed to these bacterial species (16). Mechanistically, these protective effects were related to epigenetic modification of the IFNG promoter in T-cells (17). Bacterial fermentation in the lower gastrointestinal tract degrades indigestible complex carbohydrates from fiber, amino acids or mucus and gives rise to a variety of microbial metabolites. These metabolites include hydrogen; organic acids, such as lactate and succinate; alcohols, such as 1,2 propanediol; and short-chain fatty acids (SCFAs), such as acetate, butyrate,