Cited by 835Gut microbiota and healthGastrointestinal motility and disordersAnimal Nutrition and Physiology

The DOI matches its Crossref record; 210 of the 210 references it cites were found in a registry or an index; none of the 187 sources its claims cite is checked for support yet.

Regulation of Intestinal Barrier Function by Microbial Metabolites

Open access
Ghosh, Sweta, Whitley, Caleb Samuel, Haribabu, Bodduluri, Jala, Venkatakrishna Rao·2021·Cellular and Molecular Gastroenterology and Hepatology

Abstract

The human gastrointestinal tract (GI) harbors a diverse population of microbial life that continually shapes host pathophysiological responses. Despite readily available abundant metagenomic data, the functional dynamics of gut microbiota remain to be explored in various health and disease conditions. Microbiota generate a variety of metabolites from dietary products that influence host health and pathophysiological functions. Since gut microbial metabolites are produced in close proximity to gut epithelium, presumably they have significant impact on gut barrier function and immune responses. The goal of this review is to discuss recent advances on gut microbial metabolites in the regulation of intestinal barrier function. While the mechanisms of action of these metabolites are only beginning to emerge, they mainly point to a small group of shared pathways that control gut barrier functions. Amidst expanding technology and broadening knowledge, exploitation of beneficial microbiota and their metabolites to restore pathophysiological balance will likely prove to be an extremely useful remedial tool.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This review summarizes how gut microbial metabolites regulate intestinal barrier function through shared pathways and discusses potential therapeutic strategies. It highlights metabolites such as SCFAs, indole derivatives, bile acids, conjugated fatty acids, polyamines, and polyphenolic derivatives, while noting that mechanisms and clinical translation remain early.

Key findings

  • The gut barrier comprises mucus, epithelial, and mucosal immune layers; junctional complexes (tight junctions, adherens junctions, desmosomes, gap junctions) regulate paracellular permeability via the pore pathway (excludes molecules ≤8 Å), the leak pathway (exclusion limit ∼100 Å), and an unrestricted pathway from IEC death.
  • Microbial metabolites influence barrier function: butyrate at 1–10 mM improved epithelial barrier function and increased MUC2 in E12 human colon cells, whereas 50–100 mM showed no beneficial effect; indole levels in fecal samples of germ-free mice were 27-fold lower than conventionally raised mice, and indole supplementation restored junctional protein expression; UroA enhanced TJ proteins via an AhR-Nrf2–dependent pathway and mitigated DSS- or TNBS-induced colitis; DCA increased gut permeability >1.5-fold, while UDCA blocked DCA-induced permeability.
  • Bacterial structural components signal through TLRs and NLRs: TLR2 activation increases TEER and TJ sealing; LPS/TLR4 disrupts junctional complexes and increases permeability; TLR5/flagellin and NOD1/NOD2 also modulate barrier integrity, with Nod1−/− and Nod2−/− mice showing increased paracellular permeability and DSS colitis susceptibility.
  • Treatment strategies include FMT, probiotics, UroA/UAS03, divertin, hormone treatment, and dietary supplements, but the review states that no microbial metabolites or their analogues are in clinical use.

Methods

  • Narrative review; no primary experimental data. It synthesizes recent advances on gut microbial metabolites and intestinal barrier function, with tables of intestinal cell types, junctional components, and microbial metabolites, plus figures of pathways and treatment strategies.
  • Cites preclinical and human studies, including cell lines (Caco-2, T84, E12), mouse models (germ-free, DSS/TNBS colitis, AhR−/−, Nrf2−/−, etc.), piglet models, and human trials/observations.
  • Main analysis is qualitative synthesis of the literature; no systematic search strategy or meta-analysis is described.

Limitations

  • The paper states that mechanisms of action of these metabolites are only beginning to emerge and that detailed mechanisms are yet to be elucidated.
  • The paper states that no microbial metabolites or their analogues are in clinical use, that UroA production and function in vivo have yet to be directly determined using gnotobiotic animals, and that extensive longitudinal studies are needed.
  • Evident from the text: as a narrative review, it does not provide systematic search criteria, risk-of-bias assessment, or quantitative synthesis; conclusions rely on cited studies with varying models, doses, and species.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.jcmgh.2021.02.007

Cites

210 of 210 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Figure 1 Potential treatment strategies against gut barrier dysfunction. Host-microbiota interactions and external stimuli drive changes in gut barrier integrity and lead to gut barrier dysfunction. Impaired junctional proteins and increased intestinal permeability lead to pathogen-mediated mucosal inflammation and subsequent uncontrolled immune responses mediated by macrophages, T cells, B cells, mast cells, neutrophils, and dendritic cells. Potential preventive/therapeutic interventions are shown. Inhibition of disease induced regulatory factors, hormone treatment, dietary supplementation, and healthy diets and habits can potentially restore intestinal epithelial barrier function. GJ, gap junction protein; NSAID, nonsteroidal anti-inflammatory drugs.
Figure 1 Potential treatment strategies against gut barrier dysfunction. Host-microbiota interactions and external stimuli drive changes in gut barrier integrity and lead to gut barrier dysfunction. Impaired junctional proteins and increased intestinal permeability lead to pathogen-mediated mucosal inflammation and subsequent uncontrolled immune responses mediated by macrophages, T cells, B cells, mast cells, neutrophils, and dendritic cells. Potential preventive/therapeutic interventions are shown. Inhibition of disease induced regulatory factors, hormone treatment, dietary supplementation, and healthy diets and habits can potentially restore intestinal epithelial barrier function. GJ, gap junction protein; NSAID, nonsteroidal anti-inflammatory drugs.CC BY-NC-ND · PubMed Central
Figure 2 Potential pathways responsible for microbial mediated enhancement of gut barrier function. Healthy diets get metabolized by beneficial gut commensal microbiota in the human gut to produce various types of microbial metabolites such as SCFAs, indole derivatives, bile acid metabolites, conjugated fatty acids, polyamines, and phenolic derivatives. Each microbial metabolite activates various pathways responsible for modulation of gut barrier and inflammation through the activation of membrane or nuclear receptors as shown.
Figure 2 Potential pathways responsible for microbial mediated enhancement of gut barrier function. Healthy diets get metabolized by beneficial gut commensal microbiota in the human gut to produce various types of microbial metabolites such as SCFAs, indole derivatives, bile acid metabolites, conjugated fatty acids, polyamines, and phenolic derivatives. Each microbial metabolite activates various pathways responsible for modulation of gut barrier and inflammation through the activation of membrane or nuclear receptors as shown.CC BY-NC-ND · PubMed Central

Verification

Claims the paper makes

150 Not checked yet · 15 No basis given · 12 Own interpretation

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Show all 91 claims

  • Probably not a substantial claim. 18
  • It may state two separate claims as one. 73
  • The quote only partly states this claim. 1
86 of 86
  • The authors state this as an assumption.

    Gut microbial metabolites, produced in close proximity to gut epithelium, have significant impact on gut barrier function and immune responses.

    “Since gut microbial metabolites are produced in close proximity to gut epithelium, presumably they have significant impact on gut barrier function and immune responses.”
  • The paper relies on this without support.

    Intestinal microbial homeostasis is required for maintenance of good health and disease prevention.

    “Intestinal microbial homeostasis is required for maintenance of good health and disease prevention.”
  • The paper relies on this without support.

    Reversal of gut dysbiosis is the key factor for any treatment utilizing gut microbiota.

    “Reversal of gut dysbiosis is the key factor for any treatment utilizing gut microbiota.”
  • The paper relies on this without support.

    A healthy life without stress, obesity, and diabetes and accompanied by an alcohol-free diet can reverse gut barrier dysfunction over time.

    “A healthy life without stress, obesity, and diabetes and accompanied by an alcohol-free diet can reverse gut barrier dysfunction over time.”
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Metadata

Authors
Ghosh, S., Whitley, C. S., Haribabu, B., & Jala, V. R.
Affiliations
University of Louisville (US)
Corresponding author
Jala, Venkatakrishna Rao
Venue
Cellular and Molecular Gastroenterology and Hepatology
Publisher
Elsevier BV
Published
2021
Volume
11
Issue
5
Pages
1463-1482
ISSN
2352-345X (ISSN-L)
OpenAlex
W3129925389
Cited by
835
References
210
Citations by year
2026: 168 · 2025: 229 · 2024: 192 · 2023: 130 · 2022: 89 · 2021: 27
FWCI
11.47
Type
journal article
Language
en
Open access
Locations
  • Cellular and Molecular Gastroenterology and Hepatology (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
National Institutes of Health
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gut microbiota and health
  • Health Sciences › Medicine › Gastroenterology › Gastrointestinal motility and disorders
  • Life Sciences › Agricultural and Biological Sciences › Animal Science and Zoology › Animal Nutrition and Physiology
Keywords
intestinal barrier function, gut microbiota, microbial metabolites, intestinal epithelium, host-microbe interactions, immune regulation, dietary metabolites, dysbiosis, probiotics
MeSH terms
Gastrointestinal Microbiome, Animals, Cell Membrane Permeability, Humans, Intestinal Mucosa, Metabolome

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