Il6 blockade confers on dystrophic mdx muscle resistance to degeneration and ameliorate dystrophic phenotype.
(A) Schematic representation of moAb-Il6r treatment protocol in 15-week-old mdx mice. MoAb-Il6r was administered at an initial dose of 100 μg/g of body weight and then mdx mice were treated twice a week with 20 μg/g (for a total of 5 doses) in PBS. Mice were sacrificed at day 30 of age. (B) Representative images of whole diaphragm, stained with Evans blue dye (EBD), from moAb-Il6r treated and untreated mdx mice of 4 weeks of age. Necrotic region is blue in visible microscopy (top panels) and red in fluorescence microscopy (bottom panel). Scale bar, 500 μm. (C) Confocal microscopy: representative images of one spatial series (from 0 to 80 μm) composed of 8 optical sections with a step size of 10 μm, from whole diaphragms of 4-week-old mdx and moAb-Il6r-treated mdx mice. EBD is more diffuse in the diaphragm of mdx mice (a–h) than the diaphragm of moAb-Il6r-treated mdx mice (i–r). Scale bar, 150 μm. Graphs showing quantification of EBD uptake. Values represent mean ± SEM; n = 5 to 9 per group. p values, using one way ANOVA. ND, no detected. (D) Exhaustion treadmill tests carried on wild-type (WT), untreated, and moAb-Il6r-treated mdx mice. Note that moAb-Il6r-treated mdx showed increased running performance compared to untreated mdx mice. Muscle strength of treated and control animals was measured as time (top histogram) or distance to exhaustion (bottom histogram). Values represent mean ± SEM; n = 4 per group. *p < 0.05, ***p < 0.0005, #p < 0.05, and ###p < 0.0005 using one way ANOVA. (E) Representative images of confocal analysis (top panels) and quantification of EBD uptake (bottom panels) performed on 240 optical sections from whole diaphragm muscles of indicated genotypes. Scale bar, 150 μm. Necrotic fibers evaluated by total intensity and mean amplitude of fluorescence (bottom) are significantly reduced in moAb-Il6r exercised mdx mice compared to mdx exercised mice. Values represent mean ± SEM; n = 5 to 9 per group. **p < 0.005, *p < 0.05, ###p < 0.0005, and ##p < 0.005 using one way ANOVA.