Incorporating the airway microbiome into asthma phenotyping: Moving toward personalized medicine for noneosinophilic asthma

Overall, these results are in agreement with those of prior studies that have found collectively that members of the Gammaproteobacteria (the taxonomic class to which Haemophilus and Moraxella species and many other potential respiratory pathogens belong) become more dominant in the lower airways with increasing disease severity. [...]immune responses related to neutrophilic inflammation (eg, TH17-associated epithelial gene expression4) have been associated with Gammaproteobacteria abundance. [...]the opposite was observed. [...]paucigranulocytic inflammation was the second most common phenotype (36%) observed, and the absence of relationships to the bacterial microbiome implies that other mechanisms are involved in this subgroup. [...]the assertion that neutrophilic asthma was characterized by “a greater frequency of taxa at high relative abundance” (namely, Haemophilus and Moraxella species) is weakened by the fact that less than 50% (6/14) of the subjects actually displayed this pattern and comprised only 4% of the total study cohort. Compositional profiling needs to be complemented with function-oriented analyses of both the host and microbial sides because interactions between the host and microbiome are almost certainly bidirectional, with species- and strain-specific behaviors shaped by the microenvironment in which they exist. [...]the surrounding physiologic, biochemical, and microbial milieu shapes both the composition and function of a microbial community.