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Updated: Sep 13, 2025
Assessing Functional Performance in the Mdx Mouse Model
Published on: March 27, 2014
APE1/Ref-1 inhibition via APX3330 lowers monocyte/macrophage infiltration without ameliorating the structure and
Hannah Lalunio1,2, Craig A Goodman2,3,4, Nicole Stupka1,2
1Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, Victoria, Australia.
Abstract:
Chronic inflammation and oxidative stress exacerbate muscle wasting and weakness in Duchenne muscular dystrophy (DMD). Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) regulates transcription factors involved in inflammatory and oxidative stress pathways. APE1/Ref-1 is an emerging therapeutic target in inflammatory conditions. This study aimed to investigate the effects of APX3330, a small molecule inhibitor of APE1's Ref-1 on mdx mouse pathology, a model of DMD. Six-week-old mdx mice and wild type (WT) C57Bl/10 mice were treated with APX3330 (25 mg·kg-1) or vehicle for 6 weeks. Ex vivo contractile function, histological and biochemical analysis were performed in extensor digitorum longus (EDL) and soleus muscles. APE1/Ref-1 protein was greater in mdx hindlimb muscles compared to WT (p < 0.0001) and APE1/Ref-1 protein abundance was not altered by treatment with APX3330. In dystrophic EDL muscles, APX3330 treated mice had fewer (47%) infiltrating CD68-positive monocytes/macrophages (p < 0.05) compared to vehicle-treated mdx mice. Markers of oxidative stress, NRF2/KEAP-1, were unchanged, yet phospho-NF-κB abundance was higher with treatment (p < 0.01). APX3330 treatment neither improve force output and fatiguability of isolated hindlimb muscles, nor affect muscle pathology. As APE1/Ref-1 inhibition modestly lowered inflammation, with no improved contractile function, targeting solely inflammation and oxidative stress in 6-week-old mdx mice appears insufficient.
Insights
A small molecule inhibitor targeting Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) did not improve muscle function in Duchenne muscular dystrophy (DMD) mice. While it reduced inflammation, targeting only this pathway was insufficient for therapeutic benefit.
Area of Science:
- Biochemistry
- Molecular Biology
- Muscle Physiology
- Pharmacology
Background:
- Duchenne muscular dystrophy (DMD) is characterized by chronic inflammation and oxidative stress, leading to muscle wasting and weakness.
- Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a key regulator of inflammatory and oxidative stress pathways and an emerging therapeutic target.
- APE1/Ref-1 protein levels are elevated in DMD muscles, suggesting its potential role in disease pathology.
Purpose of the Study:
- To investigate the therapeutic effects of APX3330, a small molecule inhibitor of APE1/Ref-1, on the pathology of Duchenne muscular dystrophy (DMD) in mdx mice.
- To assess the impact of APX3330 on muscle function, inflammation, and oxidative stress markers in a mouse model of DMD.
Main Methods:
- Six-week-old mdx mice (DMD model) and wild-type (WT) littermates were treated with APX3330 (25 mg·kg⁻¹) or vehicle for six weeks.
- Ex vivo contractile function, histological analysis (including CD68 staining for macrophages), and biochemical analysis (NRF2/KEAP-1, phospho-NF-κB) were performed on extensor digitorum longus (EDL) and soleus muscles.
- APE1/Ref-1 protein abundance was quantified in hindlimb muscles.
Main Results:
- APE1/Ref-1 protein was significantly higher in mdx mouse hindlimb muscles compared to WT mice, but APX3330 treatment did not alter its abundance.
- APX3330 treatment led to a modest reduction (47%) in infiltrating CD68-positive monocytes/macrophages in dystrophic EDL muscles.
- No significant improvements were observed in ex vivo muscle force output or fatiguability, nor were muscle pathology markers affected by APX3330 treatment. Oxidative stress markers remained unchanged, while phospho-NF-κB levels increased.
Conclusions:
- Inhibition of APE1/Ref-1 by APX3330 showed a modest anti-inflammatory effect but failed to improve muscle contractile function or overall pathology in 6-week-old mdx mice.
- Targeting solely inflammation and oxidative stress pathways through APE1/Ref-1 inhibition appears insufficient to counteract the complex pathology of Duchenne muscular dystrophy at this disease stage.
- Further research is needed to explore alternative or combination therapeutic strategies for DMD.
