Natural disease history of mouse models for limb girdle muscular dystrophy types 2D and 2F

Abstract

Limb-girdle muscular dystrophy types 2D and 2F (LGMD 2D and 2F) are autosomal recessive disorders caused by mutations in the alpha- and delta sarcoglycan genes, respectively, leading to severe muscle weakness and degeneration. The cause of the disease has been well characterized and a number of animal models are available for pre-clinical studies to test potential therapeutic interventions. To facilitate transition from drug discovery to clinical trials, standardized procedures and natural disease history data were collected for these mouse models. Implementing the TREAD-NMD standardized operating procedures, we here subjected LGMD2D (SGCA-null), LGMD2F (SGCD-null) and wild type (C57BL/6J) mice to five functional tests from the age of 4 to 32 weeks. To assess whether the functional test regime interfered with disease pathology, sedentary groups were taken along. Muscle physiology testing of tibialis anterior muscle was performed at the age of 34 weeks. Muscle histopathology and gene expression was analysed in skeletal muscles and heart.Muscle histopathology and gene expression was analysed in skeletal muscles and heart. Mice successfully accomplished the functional tests, which did not interfere with disease pathology. Muscle function of SGCA- and SGCD-null mice was impaired and declined over time. Interestingly, female SGCD-null mice outperformed males in the two and four limb hanging tests, which proved the most suitable non-invasive tests to assess muscle function. Muscle physiology testing of tibialis anterior muscle revealed lower specific force and higher susceptibility to eccentric-induced damage in LGMD mice. Analyzing muscle histopathology and gene expression, we identified the diaphragm as the most affected muscle in LGMD strains. Cardiac fibrosis was found in SGCD-null mice, being more severe in males than in females. Our study offers a comprehensive natural history dataset which will be useful to design standardized tests and future pre-clinical studies in LGMD2D and 2F mice.

High‐throughput data‐driven analysis of myofiber composition reveals muscle‐specific disease and age‐associated patterns

“…Enhanced alterations in myofiber composition were found in SGCD-null mice compared with SGCA-null mice. This is consistent with a more severe muscle phenotype in SGCD-null mice compared with SGCA-null mice (13,14,18). In addition, we show differential muscle involvement between SGCA-null and SGCD-null mouse models, concomitant with differential muscle involvement in muscular dystrophies (31)(32)(33)(34).…”

“…To assess alterations in myofiber composition, we studied 2 muscles, the diaphragm and gastrocnemius, and 3 genotypes [C57BL/6J wild-type and 2 mouse models for LGMD type-2D and -2F, having mutations in a-sarcoglycan (SGCA-null) and d-sarcoglycan (SGCD-null), respectively (13,14)]. We first investigated muscles from 8-wk-old mice because at that age dramatic differences in muscle physiology were previously reported in both mouse models as compared with wild-type mice (13,14,18). We confirmed muscle pathology in SGCA-null and SGCD-null diaphragm and gastrocnemius using hematoxylin and eosin staining and observed regions with degeneration, regeneration, inflammation, and fibrosis ( Fig.…”

“…To capture additional myofiber subgroups, more molecular features should be included. For example, future studies can include MyHC-2x because it plays a role in muscle atrophy and aging (17) or neonatal and embryonic MyHC isoforms, which are highly expressed in muscular dystrophy models (18,35). In this study we did not address interindividual variations because n = 5 has a limited power for 2D analyses.…”

High-throughput data-driven analysis of myofiber composition reveals muscle-specific disease and age-associated patterns

“…Enhanced alterations in myofiber composition were found in the SGCD-null mice compared with SGCA-null mice. This is consistent with a more severe muscle phenotype in SGCDnull mice compared with SGCA-null mice (13,14,18). In addition, we show differential muscle involvement between SGCA-null and SGCD-null mouse models, concomitant with differential muscle involvement in muscular dystrophies (30)(31)(32)(33).…”

“…To assess alterations in myofiber composition we studied two muscles, the diaphragm and gastrocnemius, and three genotypes C57BL/6J wild type and two mouse models for LGMD type-2D and -2F, having mutations in α-sarcoglycan (SGCA-null) and δ-sarcoglycan (SGCD-null), respectively (13,14). We first investigated muscles from 8-week-old mice, as at that age dramatic differences in muscle physiology were found in both mouse models as compared with wild type mice (13,14,18). We confirmed muscle pathology in SGCA-null and SGCD-null diaphragm and gastrocnemius, using H&E staining, and observed regions with degeneration, regeneration, inflammation and fibrosis ( Fig.…”