論文の公開元へCellular senescence in white matter microglia is induced during ageing in mice and exacerbates the neuroinflammatory phenotype
概要
Title
Cellular senescence in white matter microglia is
induced during ageing in mice and exacerbates
the neuroinflammatory phenotype
Author(s)
Matsudaira, Tatsuyuki; Nakano, Sosuke; Konishi,
Yusuke et al.
Citation
Communications Biology. 2023, 6(1), p. 665
Version Type VoR
URL
rights
https://hdl.handle.net/11094/92727
This article is licensed under a Creative
Commons Attribution 4.0 International License.
Note
Osaka University Knowledge Archive : OUKA
https://ir.library.osaka-u.ac.jp/
Osaka University
ARTICLE
https://doi.org/10.1038/s42003-023-05027-2
OPEN
Cellular senescence in white matter microglia is
induced during ageing in mice and exacerbates the
neuroinflammatory phenotype
1234567890():,;
Tatsuyuki Matsudaira 1,7 ✉, Sosuke Nakano1,7, Yusuke Konishi1, Shimpei Kawamoto 1, Ken Uemura1,
Tamae Kondo1, Koki Sakurai 2, Takaaki Ozawa 2, Takatoshi Hikida 2, Okiru Komine 3,
Koji Yamanaka 3, Yuki Fujita4, Toshihide Yamashita 4, Tomonori Matsumoto1 & Eiji Hara 1,5,6 ✉
Cellular senescence, a state of irreversible cell-cycle arrest caused by a variety of cellular
stresses, is critically involved in age-related tissue dysfunction in various organs. However,
the features of cells in the central nervous system that undergo senescence and their role in
neural impairment are not well understood as yet. Here, through comprehensive investigations utilising single-cell transcriptome analysis and various mouse models, we show that
microglia, particularly in the white matter, undergo cellular senescence in the brain and spinal
cord during ageing and in disease models involving demyelination. Microglial senescence is
predominantly detected in disease-associated microglia, which appear in ageing and neurodegenerative diseases. We also find that commensal bacteria promote the accumulation of
senescent microglia and disease-associated microglia during ageing. Furthermore, knockout
of p16INK4a, a key senescence inducer, ameliorates the neuroinflammatory phenotype in
damaged spinal cords in mice. These results advance our understanding of the role of cellular
senescence in the central nervous system and open up possibilities for the treatment of agerelated neural disorders.
1 Research Institute for Microbial Diseases (RIMD), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan. 2 Laboratory for Advanced Brain
Functions, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan. 3 Department of Neuroscience and
Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan. 4 Department of
Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. 5 Immunology Frontier
Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan. 6 Center for Infectious Diseases Education and Research
(CiDER), Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871, Japan. 7These authors contributed equally: Tatsuyuki Matsudaira and Sosuke
Nakano. ✉email: matsudaira@biken.osaka-u.ac.jp; ehara@biken.osaka-u.ac.jp
COMMUNICATIONS BIOLOGY | (2023)6:665 | https://doi.org/10.1038/s42003-023-05027-2 | www.nature.com/commsbio
1
ARTICLE
W
COMMUNICATIONS BIOLOGY | https://doi.org/10.1038/s42003-023-05027-2
hile recent medical advances have increased life
expectancy, many people suffer from age-related
neural dysfunction and neurodegenerative diseases.
Microglia, tissue-resident macrophages in the central nervous
system (CNS), play important roles in maintaining homoeostasis
by regulating neuronal activity and phagocytosing unwanted
substances1–4. Recently, disease-associated microglia (DAM) with
specific transcriptional signatures have been detected in the
brains of elderly individuals, patients with various neurodegenerative diseases and neurodegenerative disease mouse models5–9,
suggesting DAM’s involvement in age-related neural disease
pathogenesis1,3. Furthermore, a recent analysis of the enhancerpromoter interactome using human brain cells revealed that
variants related to sporadic Alzheimer’s disease (AD) were primarily restricted to microglia enhancers10. Therefore, microglial
abnormalities may be critically involved in degenerative CNS
diseases.
Accumulating evidence indicates that cellular senescence leads
to a decline in tissue function, associated with ageing and various
diseases11,12. Cellular senescence is defined as irreversible cellcycle arrest caused by a persistent DNA damage response, activated by various cellular stresses, such as telomere shortening,
oncogene activation, excessive oxidative stress and radiation13,14.
In addition to irreversible cell-cycle arrest, mainly coordinated by
p16INK4a and p21Waf1/Cip1, senescent cells exhibit a secretory
phenotype that releases various inflammatory cytokines, chemokines and growth factors into their extracellular fluid15–18. This
phenotype, now called senescence-associated secretory phenotype
(SASP), plays beneficial and detrimental roles, depending on the
biological context14,19. The accumulation of senescent cells can
cause localised inflammation in the surrounding tissues, leading
to cancer promotion and tissue dysfunction20–22. Furthermore,
senescent-like signatures in the context of neurodegenerative
diseases, including AD, multiple sclerosis (MS), Parkinson’s disease, and amyotrophic lateral sclerosis, have been detected in
various cell types in the CNS, including neural cells23–25, cerebrovascular cells26, and glial cells23,27–32. Importantly, removing
senescent cells or inhibiting their accumulation reduces neuroinflammation and ameliorates cognitive functions27–30,33,34,
demonstrating that cellular senescence may contribute to CNS
tissue dysfunction. In contrast, a comprehensive study by singlecell analysis of the hippocampus of aged mice revealed that p16positive senescent cells primarily accumulated in oligodendrocyte
progenitor cells (OPCs) and microglia during the natural ageing
process35. Moreover, single-cell analysis in mice that can detect
and remove p16-expressing cells36 showed that microglia is one
of the main populations expressing p16 in the aged brain37,
suggesting that glial cells, including microglia, are major cell types
that experience senescence during the natural aging process.
However, little is known about the regional specificity of senescent cell accumulation, mechanism of accumulation, or the outcome of the cell type-specific inhibition of senescent cells in
the CNS.
In this study, we began by confirming senescent cells in the
CNS during natural aging processes in detail and investigate their
role in neural pathogenesis. We demonstrated that senescent cells
accumulate in both the brain and spinal cord with age using p16
reporter (p16-luc) mice38, which can help visualise senescent cells
in vivo. Subsequent single-cell RNA sequencing (scRNA-seq) and
detailed histological analysis revealed that senescent cells were
primarily detected in microglia in the CNS white matter regions.
Microglial senescence was prominently identified in DAM and
further increased during ageing and in pathological conditions
involving demyelination and neurodegeneration. Furthermore,
we found that microglial senescence suppression attenuated the
neuroinflammatory phenotype, and commensal bacteria partially
2
promoted microglial senescence. These findings provide further
insights into CNS cellular senescence and shed light on the role of
microglial senescence in age-related and neurodegenerative CNS
impairment progression.
Results
Senescent microglia expressing p16INK4a accumulate in the
white matter of the brains of old mice. To determine whether
senescent cells accumulate in the ageing brain, we first analysed
young (2–3 months old) and old (over 18 months old) p16-luc
mouse brains, in which the expression of p16INK4a, a key cellular
senescence inducer, can be visualised as a bioluminescence
signal38. Old p16-luc mice exhibited a marked increase in bioluminescence signal, especially in the pons and medulla oblongata
regions, compared to young mice (Fig. 1a, b, Supplementary
Fig. 1a). Further evaluation by immunoblotting and RT-qPCR
revealed that p16INK4a mRNA and protein were highly expressed
in the brain’s white matter regions, such as the corpus callosum
and medulla oblongata in old mice (Fig. 1c, d). Furthermore, the
expression of SASP factor genes, including Il1b and Cxcl10, was
also increased, especially in the old mice’s brain regions where
p16INK4a was highly expressed (Supplementary Fig. 1b, c).
p16INK4a immunohistochemical staining using a specific antibody
(Supplementary Fig. 1d, e) confirmed that the p16INK4a-expressing cells were predominantly accumulated in the white matter of
old mice but not in that of young mice (Fig. 1e, Supplementary
Fig. 1f, g).
To characterise p16INK4a-expressing cells, the corpus callosum
was collected from young and old mice and subjected to scRNAseq analysis (Fig. 2a). Cell-type classification based on their
specific markers39 and their uniform manifold approximation
and projection (UMAP) plots (young, 4,657 cells; old, 6,789 cells)
revealed that cells expressing Cdkn2a, encoding p16INK4a, were
abundant in the white matter of old mice, mainly in the microglia
(Fig. 2b–e, Supplementary Fig. 2a–h), which is consistent with
previous scRNA-seq analyses showing high p16 expression in
microglia from the hippocampus or the whole brain of old
mice35,37. Consistent with this data, microglia sorted from the old
mice’s brains showed higher p16INK4a mRNA and protein
expression than those of young mice (Fig. 2f, g, Supplementary
Fig. 3a–c). Moreover, immunostaining analysis confirmed that
the p16INK4a-expressing cells were positive for Iba1, a microglial
marker (Fig. 2h, i). These results, together with the observation
that the γH2AX levels (another cellular senescence marker)
increased in the old mice’s microglia (Supplementary Fig. ...
この論文で使われている画像
