Collinsella

Bile Acid Deconjugation#

C. aerofaciens possesses potent bile salt hydrolase (BSH) activity, deconjugating primary bile acids. Altered bile acid profiles disrupt FXR signaling in the liver and intestine, reducing cholesterol excretion and promoting lipid accumulation.

Deconjugated bile acids are more readily converted to secondary bile acids (DCA, LCA) by other bacteria, compounds that are pro-inflammatory and potentially genotoxic in the colon.

Gut Barrier Disruption#

Collinsella increases intestinal permeability by downregulating tight junction proteins in colonocytes. Promotes a "leaky gut" state that enables LPS translocation and systemic Metal-Driven Inflammation—a direct pathway to atherosclerosis. Produces hydrogen and CO2 gas, contributing to bloating and GI discomfort.

Lipid and Cholesterol Metabolism#

Alters host cholesterol metabolism by reducing hepatic bile acid synthesis via disrupted FXR signaling. Associated with increased serum LDL-cholesterol and triglycerides. Reduces cholesterol excretion via altered bile acid cycling, contributing to hyperlipidemia.

Disease Associations#

Cardiovascular disease/atherosclerosis: one of the most consistently enriched taxa in CVD. Linked to arterial stiffness and carotid intima-media thickness.^{[1]Network of Interactions Between Gut Microbiome, Host Biomarkers, and Urine Metabolome in Carotid AtherosclerosisRui-Jun Li, Zhu-Ye Jie, Qiang Feng et al. · 2021Open reference 1 ↓} Part of the pro-atherogenic microbiome signature.^{[2]Gut macrobiotic and its metabolic pathways modulate cardiovascular diseaseJunwen Zhu, Jin Lyu, Ruochi Zhao et al. · 2023Open reference 2 ↓}

Rheumatoid arthritis: enriched in RA patients; C. aerofaciens promotes Th17 polarization and increases gut permeability, potentially enabling molecular mimicry and autoimmune activation. Type 2 diabetes: enriched in T2D; associated with insulin resistance and altered glucose metabolism.

Autism spectrum disorder: enriched in ASD children alongside Lactobacillus and Corynebacterium; associated with altered bile acid metabolism.^{[3]Strati 2017 — New Evidences on the Altered Gut Microbiota in Autism Spectrum DisordersFrancesco Strati, Duccio Cavalieri, Davide Albanese et al. · 2017Open reference 3 ↓}

Symptomatic atherosclerosis: enriched in patients with symptomatic vs asymptomatic carotid plaques.

Heavy Metal Enrichment#

Collinsella is a shared pathobiont across multiple metal exposures—enriched by Arsenic, Lead, and Mercury in human studies.^{[4]Rezazadegan et al. 2025 — Heavy Metals and Gut Microbiota: A Systematic ReviewFatemeh Rezazadegan, Maryam Mahmoudi, Seyed Mohammad Mousavi · 2025Open reference 4 ↓}

This cross-metal enrichment pattern is unusual and suggests that Collinsella possesses inherent metal tolerance mechanisms or benefits from the ecological vacuum created when metal-sensitive commensals are depleted.

Metal-driven Collinsella expansion may represent a direct mechanistic link between environmental metal exposure and Cardiovascular Disease via bile acid dysregulation and barrier disruption. Depleted by Mediterranean diet interventions, which also reduce heavy metal bioavailability through chelation by polyphenols and fiber.

Key Metabolites#

Deconjugated bile acids—BSH-mediated deconjugation alters enterohepatic circulation. Hydrogen and CO2—gas production from carbohydrate fermentation. Lactate—minor fermentation product.