Cited by 581T-cell and B-cell ImmunologyImmunotherapy and Immune ResponsesPsoriasis: Treatment and Pathogenesis

The DOI matches its Crossref record; 80 of the 81 references it cites were found in a registry or an index; none of the 11 sources its claims cite is checked for support yet.

MAIT cells are imprinted by the microbiota in early life and promote tissue repair

Open access

Abstract

Commensals rule the MAITrix: Mucosal-associated invariant T (MAIT) cells play an important role in mucosal homeostasis. MAIT cells recognize microbial small molecules presented by the major histocompatibility complex class Ib molecule MR1. MAIT cells are absent in germ-free mice, and the mechanisms by which microbiota control MAIT cell development are unknown (see the Perspective by Oh and Unutmaz). Legoux et al. show that, in mice, development of MAIT cells within the thymus is governed by the bacterial product 5-(2-oxopropylideneamino)-6- d -ribitylaminouracil, which rapidly traffics from the mucosa to the thymus, where it is captured by MR1 and presented to developing MAIT cells. Constantinides et al. report that MAIT cell induction only occurs during a limited, early-life window and requires exposure to defined microbes that produce riboflavin derivatives. Continual interactions between MAIT cells and commensals in the skin modulates tissue repair functions. Together, these papers highlight how the microbiota can direct immune cell development and subsequent function at mucosal sites by secreting compounds that act like self-antigens. Science , this issue p. 494 , p. eaax6624 ; see also p. 419

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

MAIT cells require a narrow early-life window of microbial exposure, especially riboflavin-synthesizing bacteria, to establish long-term tissue populations. In adult skin, these cells become a dominant IL-17A-producing, tissue-resident subset that responds to commensal antigens and cytokines and accelerates wound repair in mice.

Key findings

  • MAIT cells were enriched in mouse skin, reaching up to 40% of αβ T cells, and averaged about 2% of CD3+ lymphocytes in human skin; germ-free mice had reduced MAIT cells across thymus, spleen, gut, skin, lungs, and liver.
  • A defined five-species early-life community, or monocolonization with *Proteus mirabilis* alone, restored MAIT cell development in neonatal germ-free mice, whereas later-life exposure or adult conventionalization did not; topical 5-OP-RU also induced skin MAIT cells only when given early.
  • Cutaneous MAIT cells were mostly double-negative, produced IL-17A rather than IFNγ, expressed type-17 genes including *Rorc*, *Il22*, *Il1r1*, and *Il23r*, and showed a tissue-repair transcriptional signature; IL-23 receptor deficiency reduced MAIT cell numbers, IL-18 blockade limited their expansion after *S. epidermidis*, and IL-1 receptor deficiency reduced IL-17A production.
  • *S. epidermidis* lacking *ribD* failed to expand MAIT cells, while inducible MR1 deletion after development did not affect steady-state MAIT cells but prevented their response to *S. epidermidis*; in wounding experiments, MAIT-sufficient *Tcrd−/−* mice had longer epidermal tongues than MAIT-deficient *Mr1−/− Tcrd−/−* mice, and topical 5-OP-RU increased epidermal tongue length in wild-type mice.

Methods

  • Mouse immunology study using SPF, germ-free, gnotobiotic, knockout, transgenic, parabiosis, and wound-healing models; early-life colonization was performed by oral gavage or topical skin association, with 16S rRNA sequencing and bacterial whole-genome sequencing to characterize communities and riboflavin synthesis genes.
  • Immune populations were analyzed by flow cytometry, MR1 tetramer enrichment, confocal microscopy, RNA-sequencing, and single-cell RNA-sequencing; human skin specimens from elective surgery were digested and analyzed for MAIT cell frequency.
  • Statistical comparisons used two-tailed unpaired Student’s t-tests; RNA-seq differential expression used DESeq2 with GO enrichment via Metascape, and scRNA-seq used Cell Ranger, CITE-seq-Count, and Seurat.

Limitations

  • The paper states that how microbiota-derived riboflavin intermediates before and after birth contribute to human MAIT cell maturation and long-term tissue imprinting remains to be addressed.
  • The functional wound-healing evidence is from murine punch-biopsy experiments, and MAIT cell function was tested in *Tcrd−/−* mice to reduce competition from γδ T cells, a setting the authors note is more relevant to human skin because human skin has fewer γδ T cells than mouse skin.
  • Evident from the text: human data are limited mainly to skin MAIT cell frequency, and the study relies heavily on specific mouse models, defined bacterial strains, and early-life colonization conditions, so direct human causal tests of MAIT cell function are not provided.

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Integrity signals

Registry

Crossref · 10.1126/science.aax6624

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Claims the paper makes

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  • Probably not a substantial claim. 7
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  • The paper relies on this without support.

    Human T cells develop in utero.

    “In contrast to mice, human T cells develop in utero supporting the hypothesis that such early MAIT cell imprinting may occur prior to birth.”
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Metadata

Authors
Constantinides, M. G., Link, V. M., Tamoutounour, S., Wong, A. C., Perez-Chaparro, P. J., Han, S.-J., Chen, Y. E., Li, K., Farhat, S., Weckel, A., Krishnamurthy, S. R., Vujkovic-Cvijin, I., Linehan, J. L., Bouladoux, N., Merrill, E. D., Roy, S., Cua, D. J., Adams, E. J., Bhandoola, A., Scharschmidt, T. C., Aubé, J., Fischbach, M. A., & Belkaid, Y.
Affiliations
  • National Institutes of Health (US)
  • University of Pennsylvania (US)
  • NIAID Microbiome Program, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
  • Stanford University (US)
  • University of North Carolina at Chapel Hill (US)
  • University of California, San Francisco (US)
  • University of Chicago (US)
  • Merck & Co., Inc., Rahway, NJ, USA (United States) (US)
Corresponding author
Belkaid, Yasmine
Venue
Science
Published
2019-10-25
Volume
366
Issue
6464
ISSN
  • 0036-8075 (ISSN-L)
  • 1095-9203
OpenAlex
W2981494076
Cited by
567
References
81
Citations by year
2026: 57 · 2025: 93 · 2024: 82 · 2023: 81 · 2022: 92 · 2021: 76 · 2020: 80 · 2019: 4
FWCI
25.13
Type
journal article
Language
en
Open access
Locations
  • Science (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
  • National Institutes of Health (R01-DK110174, DP1-DK113598, U19-AI111143)
  • Howard Hughes Medical Institute
  • National Institute of General Medical Sciences
  • Chan Zuckerberg Biohub
  • Cancer Research Institute
  • European Molecular Biology Organization
  • Division of Intramural Research, National Institute of Allergy and Infectious Diseases (ZIA-AI001115, ZIA-AI001132)
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › T-cell and B-cell Immunology
  • Life Sciences › Immunology and Microbiology › Immunology › Immunotherapy and Immune Responses
  • Life Sciences › Immunology and Microbiology › Immunology › Psoriasis: Treatment and Pathogenesis
Keywords
mucosal-associated invariant T cells, gut microbiota, MR1, riboflavin derivatives, thymus development, commensal bacteria, tissue repair, skin, mucosal immunity, microbial metabolites, germ-free mice
MeSH terms
Mucosal-Associated Invariant T Cells, Animals, Bacteria, Germ-Free Life, Humans, Interleukin-1, Mice, Inbred BALB C, Mice, Inbred C57BL, Riboflavin, Skin, Specific Pathogen-Free Organisms, Wound Healing, Histocompatibility Antigens Class I, Minor Histocompatibility Antigens, Mice, Knockout, Interleukin-17, Interleukin-18, Mice, Interleukin-23, Microbiota

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