Intestinal microbiome and metabolome signatures in patients with chronic granulomatous diseaseOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study sought intestinal microbiome and metabolome signatures that distinguish patients with chronic granulomatous disease (CGD) and CGD-associated inflammatory bowel disease (CGD-IBD). CGD is caused by defects in the NOX2 enzyme complex. Researchers profiled the fecal microbiome by 16S rRNA amplicon sequencing and the stool metabolome by liquid chromatography-mass spectrometry. Diversity, LEfSe, random forest, and PICRUSt2 functional prediction were applied. Confounders such as antibiotics, steroids, and azathioprine were identified and controlled. Findings were validated in a second cohort.
Who was studied?
This cross-sectional study enrolled patients at the NIH Clinical Center (primary cohort) and through the Primary Immune Deficiency Treatment Consortium (validation cohort), recruited between 2012 and 2018. The primary cohort included 79 CGD patients, 8 pathogenic variant carriers, and 19 healthy controls. The validation cohort added 36 pre-transplant CGD patients from 11 centers across the USA and Canada. The validation cohort was mostly pediatric, with a median age of 2.1 years, versus 23 years in the primary cohort. Most CGD patients had X-linked gp91 defects and were male.
What were the most important findings?
CGD patients had significantly lower bacterial alpha diversity than healthy controls and their samples were enriched for Proteobacteria. Beta diversity separated CGD from healthy (p less than 0.003). Stool from CGD patients was enriched for Erysipelatoclostridium, Sellimonas, and Lachnoclostridium species, while butyrate-producing genera were depleted. Active or prior CGD-IBD clustered separately (p less than 0.009) with lower diversity. CGD-IBD showed severe reductions in the anti-inflammatory 1,4-DHNA pathway. Several taxa correlated significantly between the two cohorts, supporting reproducibility.
What are the greatest implications of this study?
As the largest microbiome-metabolome study in CGD to date, the findings point to candidate biomarkers and therapeutic targets. Restoring butyrate producers or bacteria that make aryl hydrocarbon receptor ligands may help treat CGD-IBD. The severe loss of 1,4-DHNA, an anti-inflammatory microbial metabolite, in CGD-IBD suggests a mechanism that could be therapeutically restored. Limitations include sex imbalance, an age gap between cohorts, and reliance on 16S sequencing. The observational design means associations do not establish causation.