# Respiratory Microbiota Associations with Asthma Across American and Emirati Adults: A Comparative Analysis

## TL;DR

This study compares the respiratory microbiota of asthmatic adults in the U.S. and UAE, finding that asthma-related differences in microbiome composition are consistent across regions.

## Contribution

The study reveals that asthma-related microbiome differences are consistent across geographically distinct populations.

## Key findings

- Asthma-related differences in sputum microbiota were observed in both U.S. and UAE cohorts.
- ICS-treated asthmatic patients showed reduced bacterial phylogenetic diversity (p = 0.006).
- Obesity status influenced sputum bacterial composition, with specific genera like Rothia and Veillonella associated with obesity.

## Abstract

Clinical features of asthma are associated with differences in the lower airway microbiome. However, knowledge is limited on whether airway microbiota composition differs between individuals residing in different geographic regions and if asthma-associated differences in lower airway microbiota are similar between distinct populations.

Existing 16S rRNA gene sequence data, generated from sputum collected from adults with or without asthma (n = 74) from two single-center cohort studies in the U.S. and United Arab Emirates, were re-processed for merged computational analysis using standard available tools. Potential differences between study sites, asthma status and specific clinical factors (inhaled corticosteroid use, ICS; obesity) were examined.

Differences in sputum bacterial composition, assessed by alpha- and beta-diversity measures, were associated with study site. Despite this, asthma-related differences were discerned in both cohorts. Specifically, sputum microbiota of asthmatic patients on ICS treatment displayed reduced bacterial phylogenetic diversity, compared to those not on ICS treatment (p = 0.006). Sputum bacterial composition also differed by obesity status (unweighted Unifrac distance PERMANOVA, p = 0.004). Specific genera were identified in both cohorts that were differentially enriched between obese vs. non-obese subjects, including Rothia and Veillonella (obesity-associated) and Campylobacter (non-obesity-associated).

Our findings suggest clinical factors associated with differences in the lower airway microbiome in asthma may transcend variation related to geographic area of residence.