Microbiome and Asthma: Microbial Dysbiosis and the Origins, Phenotypes, Persistence, and Severity of Asthma

Abstract

The importance of the microbiome, and of the gut-lung axis in the origin and persistence of asthma, is an ongoing field of investigation. The process of microbial colonisation in the first three years of life is fundamental for health, with the first hundred days of life being critical. Different factors are associated with early microbial dysbiosis, such as caesarean delivery, artificial lactation and antibiotic therapy, among others. Longitudinal cohort studies on gut and airway microbiome in children have found an association between microbial dysbiosis and asthma at later ages of life. A low a-diversity and relative abundance of certain commensal gut bacterial genera in the first year of life are associated with the development of asthma. Gut microbial dysbiosis, with a lower abundance of Phylum Firmicutes, could be related with increased risk of asthma. Upper airway microbial dysbiosis, especially early colonisation by Moraxella spp, is associated with recurrent viral infections and the development of asthma. Moreover, the bacteria in the respiratory system produce metabolites that may modify the inception of asthma and is progression. The role of the lung microbiome in asthma development has yet to be fully elucidated. Nevertheless, the most consistent finding in studies on lung microbiome is the increased bacterial load and the predominance of proteobacteria, especially Haemophilus spp. and Moraxella catarrhalis. In this review we shall update the knowledge on the association between microbial dysbiosis and the origins of asthma, as well as its persistence, phenotypes, and severity.

Nerolidol attenuates airway inflammation and airway remodeling and alters gut microbes in ovalbumin‐induced asthmatic mice

“…Exogenous factors influence the pathogenesis of asthma by affecting the microbiome. Gut microbial dysbiosis leads to low alpha diversity of gut bacteria and reduced the abundance of phylum Firmicutes, which increases the risk of asthma 42 . Studies have shown that Proteobacteria are abundant in the respiratory tract of asthmatic patients 43 .…”

“…41 Firmicutes, which increases the risk of asthma. 42 Studies have shown that Proteobacteria are abundant in the respiratory tract of asthmatic patients. 43 In the airway microbiota of asthmatic patients, the most dominant bacteria at the phylum level are Firmicutes, followed by Proteobacteria and Actinobacteriota.…”

Influence of the gut and airway microbiome on asthma development and disease

“…However, due to variations in sampling locations, techniques, and time points, generalizing outcomes from these studies has proven challenging. 58,59 Akin the studies of the gut microbiome, there are six studies of the upper airways with a longitudinal design that evaluate the microbiome in infants (0-2 years) and correlate this with an asthma diagnosis later in infancy (2-18 years) 39,40,[60][61][62][63] (Table 2). Three of the six studies in the airways, reported diversity.…”

Role of the ocular surface microbiome in allergic eye diseases

“…A study looking at participants with asthma alone, allergic rhinitis alone, asthma with allergic rhinitis, and healthy controls found significant differences in the dominant, alpha-diversity indices of microbial richness and beta-diversity indices when comparing the groups [23]. Additionally, a lower abundance of gut Firmicutes and an upper airway presence of Moraxella species have both been associated with an increased risk of development of asthma [24]. Given the relationship between allergic disease and the microbiome in other organ systems, it would follow that there is also a connection between allergic eye diseases and the ocular surface microbiome.…”