General differences of gut microbiome seem unlikely to play a role in the genesis of IBM, though increased abundances of specific genera including Bacteroides were detected in the IBM group, and gastrointestinal symptoms correlated with disease severity.
Key Findings
Results
No overall differences in alpha or beta diversity were found between IBM patients and controls.
Study included 21 IBM patients and 20 control probands (unaffected spouses/cohabitants)
16S rRNA V3V4 metagenomic analysis was performed on stool samples
Bioinformatic analyses used QIIME2 and MicrobiomeAnalyst software packages
The absence of overall diversity differences suggests general gut microbiome composition differences are unlikely to play a role in IBM genesis
Results
A reduction in alpha diversity was identified in older probands (≥72 years) when comparing IBM and control groups.
The age threshold used for subgroup analysis was 72 years
This difference was detected specifically in the older subgroup rather than the overall cohort
No impact of immune treatments on alpha or beta diversity was found
Results
Increased abundances of certain genera, particularly Bacteroides, were detected in the IBM group.
Bacteroides showed increased abundance in IBM patients compared to controls
LEfSe and Random Forest analysis were used to identify group-specific biomarkers
Bacteroides, Clostridium CAG 352, and Eggerthella were identified as IBM biomarkers at the genus level
Results
Gastrointestinal symptoms correlated with disease severity in IBM patients.
Gastrointestinal symptoms were measured using the modified Gastrointestinal Symptom Rating Scale (mGSRS)
Disease severity was measured using the IBM Functional Rating Scale (IBMFRS)
Questionnaire data including Bristol Stool Scale were collected alongside stool samples
Results
No impact of immune treatments on gut microbiome composition was detected in IBM patients.
Analysis specifically examined whether immune treatments influenced gut microbiome diversity
Neither alpha nor beta diversity metrics showed significant differences related to immune treatment status
IBM is characterized as a disorder with features of both inflammation and degeneration yet without effective treatment
Methods
PICRUSt pathway analysis was applied to infer functional differences in the gut microbiome between IBM patients and controls.
PICRUSt was used to perform pathway analysis based on 16S rRNA sequencing data
The study design recruited IBM patients and their unaffected spouses/cohabitants as controls to reduce environmental and dietary confounding
The authors note that whether detected differences are part of the disease course needs to be addressed by investigations of further biosamples
Winkler M, Seel W, Kornblum C, Simon M, Reimann J. (2026). The MicroIBioM study: the gut microbiome in inclusion body myositis.. Clinical and experimental rheumatology. https://doi.org/10.55563/clinexprheumatol/1b8sv1