Alterations of gut microbiome accelerate multiple myeloma progression by increasing the relative abundances of nitrogen-recycling bacteriaOriginal 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?
The study asked how the gut microbiome relates to multiple myeloma (MM) progression. Researchers ran shotgun metagenomic sequencing of feces and untargeted serum metabolomics. They compared MM patients with healthy controls, then tested causality in mice. Experiments included fecal microbiota transplantation, single-bacterium gavage, a glutamine-synthetase mutant, and glutamine-deficient diets.
Who was studied?
The human cohort was 19 newly diagnosed, untreated MM patients and 18 age- and gender-matched healthy controls in China. Patient mean age was 60.4 years with no gastrointestinal disease. An expanded validation cohort added 17 MM patients and 21 controls for qPCR. Mechanistic work used 5TGM1 myeloma mice given patient or control fecal transplants, specific bacteria, or altered diets.
What were the most important findings?
MM patients had significantly higher gut bacterial diversity than controls. Nitrogen-recycling genera such as Klebsiella and Streptococcus were enriched, alongside 20 MM-enriched species; short-chain-fatty-acid producers were depleted. MM serum held more urea and less ammonia than controls. In mice, transplanting MM microbiota accelerated tumor progression. Klebsiella pneumoniae sped progression via de novo glutamine synthesis, its glutamine-synthetase mutant did not, and a glutamine-deficient diet slowed disease.
What are the greatest implications of this study?
The findings suggest the altered gut microbiome actively accelerates multiple myeloma, not just accompanies it. Accumulated urea appears to favor nitrogen-recycling bacteria that feed the tumor glutamine. That points to possible strategies targeting these bacteria or dietary glutamine as adjuncts to MM treatment. Some MM-enriched bacteria are opportunistic pathogens, raising infection concerns. The human cohort was small, and mouse mechanisms need confirmation in patients.