Resolution of fibrosis in mdx dystrophic mouse after oral consumption of N-163 strain of Aureobasidium pullulans produced biological response modifier β-glucan (BRMG)

Abstract

Recent advances in the management of Duchenne Muscular Dystrophy (DMD), such as exon skipping therapy, have reached a clinical stage, and although gene therapy is in clinical trials, the outcome at its best is still considered suboptimal to yield clinically discernible progress. In this study, we evaluated a novel N-163 strain of Aureobasidium pullulans produced biological response modifier β-glucan (BRMG) for its potential as an adjuvant to slow down the progression of the disease by anti-inflammatory and anti-fibrotic effects. This N-163 β-glucan is a safe and orally consumable food supplement with similar effects that have been previously proven in pre-clinical studies of organ fibrosis, and their beneficial effects have been proven in DMD clinical studies through blood parameters as well. In this study, 45 mice in the three groups, 15 each in a group; Gr. 1 normal mice, Gr.2 mdx mice as vehicle, and Gr.3 mdx mice administered the N-163 strain produced β-glucan for 45 days. Blood biochemical parameters, body weight, muscle weight, inflammation score, and fibrosis score were evaluated using H&E and Masson’s trichrome staining. The N-163 β-glucan group showed a significant decrease in the plasma ALT, AST, and LDH levels (126 ± 69, 634 ± 371, 3335 ± 1258 U/l) compared with the vehicle group (177 ± 27 U/l, 912 ± 126 U/l, 4186 ± 398 U/l). Plasma TGF-β levels increased, and plasma IL-13 levels decreased in the N-163 group. The inflammation score of HE-stained muscle sections in the N-163 group (1.5 ± 0.8) was lower than that in the vehicle group (2.0 ± 0.8). The percentage of centrally nucleated fibres (CNF) evaluated by Masson’s trichrome staining was 0 in the normal group, while it increased to 80% in the vehicle group and 76.8% in the N-163 group. The N-163 β-glucan group (24.22 ± 4.80) showed a significant decrease in the fibrosis area (Masson’s trichrome-positive area). The N-163 β-glucan thus, demonstrated its anti-fibrotic effect in this study. Considering their safety and easy oral consumption, this BRMG could be worth large multicentre clinical studies as adjuvant in slowing down the progress of DMD.