Background: CD68 macrophages play a vital role in skeletal muscle regeneration by phagocytosing debris, after injury. As these pro-inflammatory M1 macrophages that clear the necrotic tissue migrate to injury sites via the bloodstream, an optimal blood supply is crucial for their mobilization. Having documented an increase in plasma dystrophin, considered of vascular smooth muscle origin, after Neu-REFIX Beta 1,3-1,6 glucans consumption clinically, which is an indirect indicator of increased blood flow in Duchenne muscular dystrophy (DMD) – affected muscles, herein, we evaluated infiltrating CD68 macrophages and myofiber size in the skeletal muscles of mdx mice after oral administration of Neu-REFIX.
Methods: mdx mice divided into three groups: Gr.1 (Wild Type- WT), Gr.2 (mdx control- mdx-C), and Gr.3 (mdx orally fed with Neu-REFIX- mdx-REFIX) were evaluated in a 45-day study. Quadriceps muscles (n=6 per group) were subjected to immunohistochemistry staining for CD68+ macrophages, and Sirius red-stained images were analysed to assess myofiber size.
Results: CD68 staining was 0.08 ± 0.06 in WT which increased to 0.92 ± 0.79 in mdx-C, which had a further increase of 33.69 % in the mdx-REFIX (1.23 ± 0.67). Myofiber cross sectional area (CSA) increased from 791.1 ± 159.3 µm2 in WT to 1178 ± 385 µm2 in mdx-C, decreasing to 1037 ± 249.1 µm2 in mdx-REFIX.
Conclusion: The increase in CD68 in the group fed with Neu-REFIX is considered probably due to an enhanced phagocytosis of necrotic tissue in the affected muscles; requires further validation. The decrease in myofiber size after Neu-REFIX is an indicator of a reduction in muscle hypertrophy. Having previously demonstrated a reduction in inflammation, fibrosis, muscle fatigue index and an enhanced muscle regeneration with Neu-REFIX, additional investigations are warranted to clarify the mechanisms by which this biological response modifier glucan (BRMG) could help halt the progression of DMD