Abstract

Tissue-resident macrophages represent a group of highly responsive innate immune cells that acquire diverse functions by polarizing towards distinct subpopulations. The subpopulations of macrophages that reside in skeletal muscle (SKM) and their changes during aging are poorly characterized. By single-cell transcriptomic analysis with unsupervised clustering, we found eleven distinct macrophage clusters in male mouse SKM with enriched gene expression programs linked to reparative, proinflammatory, phagocytotic, proliferative, and senescence-associated functions. Using a complementary classification, membrane markers LYVE1 and MHCII identified four macrophage subgroups: LYVE1-/MHCIIhi (M1-like, classically activated), LYVE1+/MHCIIlo (M2-like, alternatively activated), and two new subgroups, LYVE1+/MHCIIhi and LYVE1-/MHCIIlo. Notably, one new subgroup, LYVE1+/MHCIIhi, had traits of both M2 and M1 macrophages, while the other new subgroup, LYVE1-/MHCIIlo, displayed strong phagocytotic capacity. Flow cytometric analysis validated the presence of the four macrophage subgroups in SKM, and found that LYVE1- macrophages were more abundant than LYVE1+ macrophages in old SKM. A striking increase in proinflammatory markers (S100a8 and S100a9 mRNAs) and senescence-related markers (Gpnmb and Spp1 mRNAs) was evident in macrophage clusters from older mice. In sum, we have identified dynamically polarized SKM macrophages and propose that specific macrophage subpopulations contribute to the proinflammatory and senescent traits of old SKM.

Data availability

The single-cell RNA-seq analysis was uploaded to GEO with identifier GSE195507.

The following data sets were generated

Article and author information

Author details

  1. Linda K Krasniewski

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Papiya Chakraborty

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Chang-Yi Cui

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    For correspondence
    cuic@grc.nia.nih.gov
    Competing interests
    The authors declare that no competing interests exist.
  4. Krystyna Mazan-Mamczarz

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Christopher Dunn

    Flow Cytometry Core, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7899-0110
  6. Yulan Piao

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Jinshui Fan

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Changyou Shi

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  9. Tonya Wallace

    Flow Cytometry Unit, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  10. Cuong Nguyen

    Flow Cytometry Unit, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  11. Isabelle A Rathbun

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  12. Rachel Munk

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  13. Dimitrios Tsitsipatis

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  14. Supriyo De

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  15. Payel Sen

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2809-0901
  16. Luigi Ferrucci

    Translational Gerentology Branch, National Institute on Aging, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6273-1613
  17. Myriam M Gorospe

    Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, United States
    For correspondence
    myriam-gorospe@nih.gov
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5439-3434

Funding

National Institutes of Health (Z01-AG000511)

  • Linda K Krasniewski
  • Papiya Chakraborty
  • Chang-Yi Cui
  • Krystyna Mazan-Mamczarz
  • Christopher Dunn
  • Yulan Piao
  • Jinshui Fan
  • Changyou Shi
  • Tonya Wallace
  • Cuong Nguyen
  • Isabelle A Rathbun
  • Rachel Munk
  • Dimitrios Tsitsipatis
  • Supriyo De
  • Payel Sen
  • Luigi Ferrucci
  • Myriam M Gorospe

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All animal study protocols were approved by the NIA Institutional Review Board (Animal Care and Use Committee). (ASP #476-LGG-2023)

Reviewing Editor

  1. Bérénice A Benayoun, University of Southern California, United States

Version history

  1. Received: February 17, 2022
  2. Preprint posted: February 24, 2022 (view preprint)
  3. Accepted: October 10, 2022
  4. Accepted Manuscript published: October 19, 2022 (version 1)
  5. Version of Record published: November 2, 2022 (version 2)

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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  1. Linda K Krasniewski
  2. Papiya Chakraborty
  3. Chang-Yi Cui
  4. Krystyna Mazan-Mamczarz
  5. Christopher Dunn
  6. Yulan Piao
  7. Jinshui Fan
  8. Changyou Shi
  9. Tonya Wallace
  10. Cuong Nguyen
  11. Isabelle A Rathbun
  12. Rachel Munk
  13. Dimitrios Tsitsipatis
  14. Supriyo De
  15. Payel Sen
  16. Luigi Ferrucci
  17. Myriam M Gorospe
(2022)
Single-cell analysis of skeletal muscle macrophages reveals age-associated functional subpopulations
eLife 11:e77974.
https://doi.org/10.7554/eLife.77974

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