Dataset Information

Radiation induces long-term muscle fibrosis and promotes a fibrotic phenotype in fibro-adipogenic progenitors.

ABSTRACT:

Background

Radiation-induced muscle pathology, characterized by muscle atrophy and fibrotic tissue accumulation, is the most common debilitating late effect of therapeutic radiation exposure particularly in juvenile cancer survivors. In healthy muscle, fibro/adipogenic progenitors (FAPs) are required for muscle maintenance and regeneration, while in muscle pathology FAPs are precursors for exacerbated extracellular matrix deposition. However, the role of FAPs in radiation-induced muscle pathology has not previously been explored.

Methods

Four-week-old Male CBA or C57Bl/6J mice received a single dose (16 Gy) of irradiation (IR) to a single hindlimb with the shielded contralateral limb (CLTR) serving as a non-IR control. Mice were sacrificed 3, 7, 14 (acute IR response), and 56 days post-IR (long-term IR response). Changes in skeletal muscle morphology, myofibre composition, muscle niche cellular dynamics, DNA damage, proliferation, mitochondrial respiration, and metabolism and changes in progenitor cell fate where assessed.

Results

Juvenile radiation exposure resulted in smaller myofibre cross-sectional area, particularly in type I and IIA myofibres (P < 0.05) and reduced the proportion of type I myofibres (P < 0.05). Skeletal muscle fibrosis (P < 0.05) was evident at 56 days post-IR. The IR-limb had fewer endothelial cells (P < 0.05) and fibro-adipogenic progenitors (FAPs) (P < 0.05) at 56 days post-IR. Fewer muscle satellite (stem) cells were detected at 3 and 56 days in the IR-limb (P < 0.05). IR induced FAP senescence (P < 0.05), increased their fibrogenic differentiation (P < 0.01), and promoted their glycolytic metabolism. Further, IR altered the FAP secretome in a manner that impaired muscle satellite (stem) cell differentiation (P < 0.05) and fusion (P < 0.05).

Conclusions

Our study suggests that following juvenile radiation exposure, FAPs contribute to long-term skeletal muscle atrophy and fibrosis. These findings provide rationale for investigating FAP-targeted therapies to ameliorate the negative late effects of radiation exposure in skeletal muscle.

SUBMITTER: Collao N

PROVIDER: S-EPMC10570115 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Publications

Radiation induces long-term muscle fibrosis and promotes a fibrotic phenotype in fibro-adipogenic progenitors.

Collao Nicolas N D'Souza Donna D Messeiller Laura L Pilon Evan E Lloyd Jessica J Larkin Jillian J Ngu Matthew M Cuillerier Alexanne A Green Alexander E AE Menzies Keir J KJ Burelle Yan Y De Lisio Michael M

Journal of cachexia, sarcopenia and muscle 20230906 5

<h4>Background</h4>Radiation-induced muscle pathology, characterized by muscle atrophy and fibrotic tissue accumulation, is the most common debilitating late effect of therapeutic radiation exposure particularly in juvenile cancer survivors. In healthy muscle, fibro/adipogenic progenitors (FAPs) are required for muscle maintenance and regeneration, while in muscle pathology FAPs are precursors for exacerbated extracellular matrix deposition. However, the role of FAPs in radiation-induced muscle ...[more]

PMID: 37671686

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Project description:Muscle resident fibro-adipogenic progenitors (FAPs), support muscle regeneration by releasing cytokines that stimulate the differentiation of myogenic stem cells. However, in non-physiological contexts (myopathies, atrophy, aging) FAPs cause fibrotic and fat infiltrations that impair muscle function. We set out to perform a fluorescence microscopy-based screening to identify compounds that perturb the differentiation trajectories of these multipotent stem cells. From a primary screen of 1,120 FDA/EMA approved drugs, we identified 34 compounds as potential inhibitors of adipogenic differentiation of FAPs isolated from the murine model (mdx) of Duchenne muscular dystrophy (DMD). The hit list from this screen was surprisingly enriched with compounds from the glucocorticoid (GCs) chemical class, drugs that are known to promote adipogenesis in vitro and in vivo. To shed light on these data, three GCs identified in our screening efforts were characterized by different approaches. We found that like dexamethasone, budesonide inhibits adipogenesis induced by insulin in sub-confluent FAPs. However, both drugs have a pro-adipogenic impact when the adipogenic mix contains factors that increase the concentration of cAMP. Gene expression analysis demonstrated that treatment with glucocorticoids induces the transcription of Gilz/Tsc22d3, an inhibitor of the adipogenic master regulator PPARγ, only in anti-adipogenic conditions. Additionally, alongside their anti-adipogenic effect, GCs are shown to promote terminal differentiation of satellite cells. Both the anti-adipogenic and pro-myogenic effects are mediated by the glucocorticoid receptor and are not observed in the presence of receptor inhibitors. Steroid administration currently represents the standard treatment for DMD patients, the rationale being based on their anti-inflammatory effects. The findings presented here offer new insights on additional glucocorticoid effects on muscle stem cells that may affect muscle homeostasis and physiology.

Dataset Information

Radiation induces long-term muscle fibrosis and promotes a fibrotic phenotype in fibro-adipogenic progenitors.

Background

Methods

Results

Conclusions

Publications

Radiation induces long-term muscle fibrosis and promotes a fibrotic phenotype in fibro-adipogenic progenitors.

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