A Gram-negative, obligate anaerobic genus within the Bacteroidetes phylum (family Odoribacteraceae). Despite its relatively recent characterization, Butyricimonas has gained significant attention as a member of the protective butyrate-producing consortium that is consistently depleted in inflammatory and autoimmune conditions. Key species include B. virosa and B. synergistica.
Role in Gut Ecosystem
- One of the few Bacteroidetes members that produces significant butyrate, placing it in an unusual metabolic niche -- most Bacteroidetes produce acetate, propionate, or succinate rather than butyrate.
- Butyrate production supports colonocyte energy metabolism, tight junction protein expression, and Treg differentiation via HDAC inhibition and GPR109A signaling.
- Contributes to colonization resistance as part of the diverse anaerobic community that prevents pathogen expansion.
- Name derives from "butyric acid" (butyrici-) and "unit" (monas), reflecting its defining metabolic feature.
Disease Associations
Multiple Sclerosis -- Key Depleted Taxon
- Decreased in MS patients in the landmark Jangi 2016 study, which established the foundational MS-microbiome connection [jangi 2016 gut microbiome alterations ms].
- Butyricimonas abundance showed negative correlations with pro-inflammatory gene expression in circulating T cells and monocytes, including genes involved in dendritic cell maturation, interferon signaling, and NF kappa B signaling.
- This is the inverse of the pattern seen with methanobrevibacter and akkermansia muciniphila, which were increased in MS and positively correlated with these inflammatory pathways.
- Higher baseline abundance in MS patients reported in the Troci 2022 study (as part of broader Bacteroidetes expansion), illustrating study-to-study variability [troci 2022 b cell depletion reverses dysbiosis ms].
Antidepressant Response
- Abundance altered by antidepressant medications (fluoxetine, amitriptyline), suggesting that drug-microbiome interactions modulate this genus [zhang 2021 antidepressants fluoxetine amitriptyline gut microbiome].
Endometriosis
- Identified among differentially abundant taxa in endometriosis-associated gut microbiome profiles [svensson 2021 endometriosis gut microbiota associations].
Thyroid Disease
- MR evidence links Butyricimonas to thyroid disease risk across multiple thyroid conditions [chen 2024 gut microbiota six thyroid diseases mr].
Key Metabolites
- Butyrate -- primary product; anti-inflammatory HDAC inhibitor, colonocyte energy source, Treg inducer
- Iso-butyrate -- branched-chain fatty acid from protein fermentation
Mechanistic Significance in MS
The Jangi 2016 findings position Butyricimonas as a key anti-inflammatory species in MS:
- Its negative correlation with interferon signaling genes suggests that butyrate from Butyricimonas may suppress the type I IFN response that drives MS pathology.
- The anti-inflammatory effect parallels that of faecalibacterium prausnitzii but from within the Bacteroidetes phylum, providing taxonomic diversity in the butyrate-producing consortium.
- Loss of Butyricimonas in MS may contribute to the reduced serum butyric acid levels and increased gut permeability documented in MS patients.
Connections
- multiple sclerosis -- depleted in MS; negative correlation with inflammatory gene expression
- faecalibacterium prausnitzii -- fellow butyrate producer; complementary anti-inflammatory role from Firmicutes
- coprococcus -- co-depleted butyrate producer in inflammatory disease
- methanobrevibacter -- shows opposite pattern in MS (increased); inflammatory correlations
- short chain fatty acids -- butyrate production is its defining metabolic feature
- NF kappa B -- butyrate suppresses NF-kB signaling in immune cells
- inflammation -- anti-inflammatory via butyrate-mediated HDAC inhibition and Treg induction
- endometriosis -- altered in endometriosis gut microbiome
- Graves' disease -- MR evidence links to thyroid disease risk
- dysbiosis -- depletion marks inflammatory dysbiosis across multiple conditions