Alistipes

Classification and Habitat#

Alistipes belongs to the family Rikenellaceae within the phylum Bacteroidota (formerly Bacteroidetes). It is a strict anaerobe that colonizes the human colon and cecum, where it thrives in the oxygen-depleted zones favored by bile-acid-tolerant commensals.

The genus was formally described relatively recently and remains incompletely characterized at the species level, contributing to inconsistencies in genus-level microbiome studies.

Disease Associations#

Colorectal Cancer—Enrichment#

Enriched in CRC and contributes to cancer progression. A. indistinctus is positively correlated with mast cell infiltration, IL-6, and IL-6R in advanced-stage (III–IV) CRC.^{[5]Identification of colorectal cancer progression-associated intestinal microbiome and predictive signature constructionJungang Liu, Xiaoliang Huang, Chuanbin Chen et al. · 2023Open reference 5 ↓} Part of the progression-associated microbiome signature distinguishing early from advanced CRC, alongside Proteus and Parabacteroides.

Enrichment in CRC may reflect altered bile acid profiles in the tumor microenvironment, where secondary bile acids promote epithelial proliferation and DNA Damage in Metal Carcinogenesis.

Autoimmune Disease—Depletion#

Significantly depleted in Graves' Disease alongside Bacteroides fragilis and Parabacteroides, contributing to the loss of anti-inflammatory commensals that characterizes thyroid autoimmunity.^{[8]Alteration in gut microbiota is associated with immune imbalance in Graves' diseaseSu X, Yin X, Liu Y et al. · 2020Open reference 8 ↓} The depletion correlates with reduced Treg activity and elevated Th17/Treg ratios, consistent with the loss of AhR-ligand production.

Multiple Sclerosis—Enrichment (Bacteroidetes Expansion)#

Elevated baseline abundance in MS patients as part of a broader Bacteroidetes expansion (higher Prevotella, Butyricimonas, Coprobacter, Parabacteroides, Alistipes), though this is driven by Firmicutes reduction rather than selective Alistipes proliferation.^{[9]B-cell-depletion reverses dysbiosis of the microbiome in multiple sclerosis patientsAlba Troci, Olga Zimmermann, Daniela Esser et al. · 2022Open reference 9 ↓}

The context-dependent direction of change (enriched in MS, depleted in Graves') reflects different immune environments.

Crohn's Disease—A. shahii Protective#

A. shahii abundance is negatively correlated with CD severity—higher levels predict less severe disease in WMS-based machine learning analysis.^{[7]Diagnosis of Crohn's Disease and Ulcerative Colitis Using the MicrobiomeKang DY, Park JL, Yeo MK et al. · 2023Open reference 7 ↓} This is a counter-intuitive finding given genus-level CRC enrichment and underscores the species-level dependence of disease associations.

Cardiovascular Disease#

Hypertension causally decreases Alistipes abundance in reverse Mendelian randomization analysis, indicating that cardiovascular disease states alter this genus—alongside Bilophila, Butyricomonas, and Phascolarctobacterium.^{[10]Causality of gut microbiome and hypertension: A bidirectional mendelian randomization studyYihui Li, Ru Fu, Ruixuan Li et al. · 2023Open reference 10 ↓} Additionally, ischemic stroke causally affects Alistipes in reverse MR analysis.^{[11]Assessment of the causal relationship between gut microbiota and cardiovascular diseases: a bidirectional Mendelian randomization analysisXiao-Ce Dai, Yi Yu, Si-Yu Zhou et al. · 2024Open reference 11 ↓}

Autism Spectrum Disorder#

A. indistinctus is negatively correlated with dopamine levels in schizophrenia microbiome profiling (enriched in patients alongside other succinate-pathway bacteria).^{[6]Functional Associations of the Gut Microbiome with Dopamine, Serotonin, and BDNF in Schizophrenia: A Pilot StudyGhorbani M, Joseph GBS, Tew MM et al. · 2024Open reference 6 ↓} Altered abundance has also been reported in ASD,^{[12]Strati 2017 — New Evidences on the Altered Gut Microbiota in Autism Spectrum DisordersFrancesco Strati, Duccio Cavalieri, Davide Albanese et al. · 2017Open reference 12 ↓} though the direction varies across studies.

What Wikipedia Doesn't Cover#

Wikipedia describes Alistipes briefly as a Rikenellaceae commensal. This page adds: species-level disease association mapping, prenatal lead exposure as an environmental depletion driver with quantitative cohort data, the paradox of Western diet enrichment despite anti-inflammatory metabolites, and the mechanistic role of indole production in AhR-mediated mucosal immunity.

Cross-References#

• Colorectal Cancer—enriched; A. indistinctus linked to immune activation in advanced tumors
• Graves' Disease—depleted alongside other Bacteroidetes commensals
• Crohn's Disease—A. shahii negatively correlated with disease severity
• Multiple Sclerosis—enriched as part of Bacteroidetes expansion
• Cardiovascular Disease—abundance decreased by hypertension (reverse MR)
• Parabacteroides—co-depleted in autoimmunity; shared bile acid metabolic niche
• Bacteroides fragilis—co-depleted in Graves' disease; fellow Bacteroidetes commensal
• Short-Chain Fatty Acids (SCFAs)—acetate and propionate producer
• Lead—prenatal exposure depletes A. indistinctus and A. putredinis persistently into childhood
• Dysbiosis—context-dependent marker; depletion in autoimmunity, enrichment in cancer
• Metal-Driven Inflammation—species-dependent: anti-inflammatory (A. finegoldii) vs. pro-inflammatory (A. indistinctus in CRC)