Daijiworld Media Network - Mumbai
Mumbai, Feb 10: A new international study has highlighted that while asthma-related airway bacteria and inflammation vary significantly across regions, certain microbiome–inflammation links remain consistent worldwide, offering fresh insights into the chronic respiratory condition.
The research analysed induced sputum samples from nearly 500 young individuals with and without asthma across five countries — Brazil, Ecuador, Uganda, New Zealand and the United Kingdom. Scientists examined inflammatory cell profiles alongside detailed airway microbiota, including bacterial load and the presence of specific respiratory pathogens.
The study revealed marked geographic differences in asthma characteristics. Participants from Uganda showed higher levels of neutrophilic inflammation, greater bacterial abundance and increased microbial diversity compared to those from other regions. In contrast, asthma cases in high-income countries more closely matched inflammatory patterns commonly described in current clinical guidelines.
These findings underscore how asthma manifests differently across global settings, shaped by environmental and microbial exposures.
Despite regional variation, researchers identified conserved associations between airway inflammation and the asthma microbiome. Across all study centres, higher neutrophil levels were strongly linked to changes in overall microbiota composition.
Neutrophilic inflammation consistently correlated with increased bacterial burden, particularly higher levels of Haemophilus influenzae and Moraxella catarrhalis — bacteria often associated with more severe or treatment-resistant asthma. These patterns were observed irrespective of geography, pointing to a shared biological signature of neutrophilic asthma.
Eosinophilic inflammation, another common asthma phenotype and a major focus of current therapies, showed comparatively weaker links with the microbiome. Higher eosinophil levels were mainly associated with increased Streptococcus abundance and accounted for less variation in microbial composition.
Researchers noted that this distinction reinforces the view that neutrophilic asthma represents a microbiologically distinct endotype, which may explain its limited response to standard anti-inflammatory treatments.
The findings suggest a mismatch between existing asthma treatment models and disease patterns prevalent in many low- and middle-income countries. While local factors influence asthma expression, the conserved relationship between neutrophilic inflammation and airway bacteria points to shared mechanisms that could guide future treatment strategies.
Though the study’s cross-sectional design limits conclusions on causality, experts say it strengthens the case for incorporating microbiome-based approaches into asthma research and clinical care, particularly for patients with neutrophilic asthma who continue to have limited treatment options.