PhD Scientific Days 2025

Molecular Medicine V.

Loss of adenosine A3 receptors accelerates skeletal muscle regeneration in mice following cardiotoxin-induced injury

Name of the presenter

Papp Albert Bálint

Institute/workplace of the presenter

Doctoral School of Dental Sciences, Department of Biochemistry and Molecular Biology, University of Debrecen

Authors

Albert Bálint Papp^1,2, Nastaran Tarban³, Zsolt Sarang², Zsuzsanna Szondy^2,4

1: Doctoral School of Dental Sciences, University of Debrecen
2: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen
3: Doctoral School of Molecular Cell and Immune Biology, University of Debrecen
4: Division of Dental Biochemistry, Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen

Text of the abstract

Introduction: Skeletal muscle is essential for movement, posture, and metabolism. When damaged, it undergoes a multi-step regeneration process, starting with an inflammatory phase marked by muscle cell necrosis and leukocyte infiltration. Both of these cells release factors that activate muscle stem cells and the regeneration. Adenosine, an anti-inflammatory molecule produced during tissue injury, exerts effects through four receptor types. Among them, A3 adenosine receptors (A3Rs) are not found on muscle cells but are present on inflammatory cells, where they play a key role in regeneration.

Aims: In this project we aim to investigate the effect of the loss of A3Rs on the regeneration of the tibialis anterior (TA) muscle in mice following cardiotoxin-induced muscle injury. In addition, our goal is to determine which cell type is mainly affected by the lack of A3R during altered skeletal muscle regeneration.

Methods: We used a cardiotoxin-induced muscle injury model in A3R wild-type (WT) and knock-out (KO) mice. At various time points post-injury, muscle tissues were collected to analyse mRNA levels of myogenic markers, inflammatory factors, and growth factors by RT-qPCR. Muscle cross-sectional area (CSA) and necrosis were assessed via laminin B and H&E staining, while muscle stem cells and inflammatory cell populations were quantified by flow cytometry.

Results: Larger CSA was observed in both non-injected and regenerating A3R KO muscles compared to WT muscles. The absence of A3R led to significantly increased leukocyte infiltration at the injury site and a smaller necrotic area. Furthermore, macrophage phenotype switching was delayed, resulting in a prolonged pro-inflammatory phase. Muscles lacking A3R showed enhanced expression of myogenic differentiation markers, pro-inflammatory cytokines, and growth factors. Additionally, the number of muscle stem cells was also elevated.

Conclusion: Our data indicate that A3Rs are negative regulators of the injury-related regenerative inflammation, and consequently of the muscle fiber growth in the TA muscle. Thus, inhibiting A3Rs might have a therapeutic value during skeletal muscle regeneration following injury.

Funding: This study was supported by the National Research, Development, and Innovation Office-NKFI, Hungary (138162).