G.P.5.12 Glutathione depletion in Emery–Dreifuss muscular dystrophy. Treatment of KI- LmnaH222P mice with the glutathione precursor N-Acetyl-L-Cysteine

Abstract

Autosomal dominant Emery–Dreifuss muscular dystrophy (AD-EDMD), affecting heart and skeletal muscles is caused by mutations in LMNA gene, which encodes lamins A/C. The severity of several cardiopathies has been correlated to a high level of serum soluble tumor necrosis factor alpha (sTNF) in both patients and animal models. The present study aims to investigate, in an AD-EDMD mouse model and in patients, the contribution of sTNF, as well as of oxidative stress and glutathione depletion that have been shown to be associated to sTNF increase. The 6-month old female KI LmnaH222P/H222P mice present left ventricle dilation and dysfunction evidenced at echocardiography. Histological analysis of the cardiac tissue reveals an extended fibrosis. A high level of sTNF associated with oxidative stress (evidenced by an increased malondialdehyde level) and glutathione depletion is found in the serum and heart of mutant mice. One-month oral treatment with the glutathione precursor N-acetyl-l-cysteine (NAC, 1.4 mg/10 g/day) prevents the worsening of the left ventricle remodelling (end-diastolic diameter: 0.134 ± 0.005; 0.165 ± 0.009; 0.151 ± 0.005 mm/g body weight in untreated WT, mutants and treated mutants, respectively. P < 0.001, n = 20) and dysfunction (fractional shortening: 39 ± 2; 25 ± 2; 30 ± 1%. P < 0.001, n = 20), limits fibrosis development (1.9 ± 0.1; 22.6 ± 0.3; 14.5 ± 1.2%. P = 0.002, n = 5) and normalizes glutathione (18.6 ± 1.0; 12.5 ± 1.4; 17.0 ± 0.5 nmol/mg prot. P = 0.002, n = 4–6), oxidative stress (1.6 ± 0.1; 3.8 ± 0.7; 1.7 ± 0.1 nmol/mg prot. P = 0.002, n = 4–6) and sTNF levels (63 ± 3; 74 ± 3; 54 ± 6%. P < 0.5, n = 4-6) in serum and heart. Survival of mutant mice treated with NAC at 1.4 or 0.3 mg/10 g/day over time-lives from the age of 6-months for females and 4-months for males is investigated. In human, blood dosage indicates glutathione depletion in 6 AD-EDMD patients and 5 transplanted patients compared to 6 control subjects, justifying further preclinical and possibly clinical studies with the NAC treatment.