DISTINCT gut bacteria may play a role in driving lung damage among people with systemic sclerosis (SSc). This is according to an international study investigating the gut-lung axis in systemic sclerosis-associated interstitial lung disease (SSc-ILD). The findings highlight how intestinal microbiota could contribute to disease mechanisms and offer potential new therapeutic targets.
Researchers analyzed stool samples from patients with and without SSc-ILD across seven specialist centers on five continents, making this one of the largest and most geographically diverse studies of its kind. Using shotgun metagenomic sequencing on the Illumina NovaSeq 6000 platform, the team identified microbial composition at the species level and compared it against quantitative imaging measures of lung involvement.
Among the 285 participants, who had a mean disease duration of nearly 10 years, 62.5% were diagnosed with ILD. Multivariate statistical analysis revealed that patients with ILD had a distinct microbial signature compared with those without. This signature was marked by an increased presence of bacterial species thought to act as pathobionts—organisms that may become harmful under certain conditions.
Within the subgroup of 103 participants who had SSc-ILD, further analysis showed that specific bacterial species and their functional metabolic pathways were significantly associated with the radiological extent of lung disease, as quantified through high-resolution computed tomography. These findings suggest that the gut microbiome could influence not only the development but also the severity of lung fibrosis in systemic sclerosis.
By establishing a clear link between gut dysbiosis and lung pathology, the study strengthens the emerging understanding of the gut-lung axis in autoimmune disease. The authors note that certain bacterial species or their metabolites may represent future biomarkers or even modifiable targets for interventions aimed at reducing fibrosis and improving outcomes in patients with SSc-ILD.
Reference: Andréasson K et al. International Investigation of the Gut-Lung Axis in Systemic Sclerosis-Interstitial Lung Disease. Arthritis Care & Research. 2025;doi:10.1002/acr.25623
