Dystrophin and utrophin isoforms are expressed in glia, but not neurons, of the avian parasympathetic ciliary ganglion

Disrupted structural connectome and neurocognitive functions in Duchenne muscular dystrophy: classifying and subtyping based on Dp140 dystrophin isoform

OBJECTIVE

Neurocognitive disabilities in Duchenne muscular dystrophy (DMD) children beginning in early childhood and distal DMD gene deletions involving disruption of Dp140 isoform are more likely to manifest significant neurocognitive impairments. MRI data analysis techniques like brain-network metrics can provide information on microstructural integrity and underlying pathophysiology.

METHODS

A prospective study on 95 participants [DMD = 57, and healthy controls (HC) = 38]. The muscular dystrophy functional rating scale (MDFRS) scores, neuropsychology batteries, and multiplex ligand-dependent probe amplification (MLPA) testing were used for clinical assessment, IQ estimation, and genotypic classification. Diffusion MRI and network-based statistics were used to analyze structural connectomes at various levels and correlate with clinical markers.

RESULTS

Motor and executive sub-networks were extracted and analyzed. Out of 57 DMD children, 23 belong to Dp140 + and 34 to Dp140- subgroup. Motor disabilities are pronounced in Dp140- subgroup as reflected by lower MDFRS scores. IQ parameters are significantly low in all-DMD cases; however, the Dp140- has specifically lowest scores. Significant differences were observed in global efficiency, transitivity, and characteristic path length between HC and DMD. Subgroup analysis demonstrates that the significance is mainly driven by participants with Dp140- than Dp140 + isoform. Finally, a random forest classifier model illustrated an accuracy of 79% between HC and DMD and 90% between DMD- subgroups.

CONCLUSIONS

Current findings demonstrate structural network-based characterization of abnormalities in DMD, especially prominent in Dp140-. Our observations suggest that participants with Dp140 + have relatively intact connectivity while Dp140- show widespread connectivity alterations at global, nodal, and edge levels. This study provides valuable insights supporting the genotype-phenotype correlation of brain-behavior involvement in DMD children.

Dystrophin Dp116: A yet to Be Investigated Product of the Duchenne Muscular Dystrophy Gene

The Duchenne muscular dystrophy (DMD) gene is one of the largest genes in the human genome. The gene exhibits a complex arrangement of seven alternative promoters, which drive the expression of three full length and four shorter isoforms. Dp116, the second smallest product of the DMD gene, is a Schwann cell-specific isoform encoded by a transcript corresponding to DMD exons 56–79, starting from a promoter/exon S1 within intron 55. The physiological roles of Dp116 are poorly understood, because of its extensive homology with other isoforms and its expression in specific tissues. This review summarizes studies on Dp116, focusing on clinical findings and alternative activation of the upstream translation initiation codon that is predicted to produce Dp118.

Myelination is delayed during postnatal brain development in the mdx mouse model of Duchenne muscular dystrophy

BACKGROUND

In Duchenne muscular dystrophy (DMD), the loss of the dystrophin component of the dystrophin-glycoprotein complex (DGC) compromises plasma membrane integrity in skeletal muscle, resulting in extensive muscle degeneration. In addition, many DMD patients exhibit brain deficits in which the cellular etiology remains poorly understood. We recently found that dystroglycan, a receptor component of the DGC that binds intracellularly to dystrophin, regulates the development of oligodendrocytes, the myelinating glial cells of the brain.

RESULTS

We investigated whether dystrophin contributes to oligodendroglial function and brain myelination. We found that oligodendrocytes express up to three dystrophin isoforms, in conjunction with classic DGC components, which are developmentally regulated during differentiation and in response to extracellular matrix engagement. We found that mdx mice, a model of DMD lacking expression of the largest dystrophin isoform, have delayed myelination and inappropriate oligodendrocyte progenitor proliferation in the cerebral cortex. When we prevented the expression of all oligodendroglial dystrophin isoforms in cultured oligodendrocytes using RNA interference, we found that later stages of oligodendrocyte maturation were significantly delayed, similar to mdx phenotypes in the developing brain.

CONCLUSIONS

We find that dystrophin is expressed in oligodendrocytes and influences developmental myelination, which provides new insight into potential cellular contributors to brain dysfunction associated with DMD.

The role of cell transplantation in modifying the course of limb girdle muscular dystrophy: a longitudinal 5-year study

Limb girdle muscular dystrophy (LGMD), a group of progressive degenerative disorders, causes functional limitation affecting the quality of life. Cell therapy is being widely explored and preliminary studies have shown beneficial effects. Cell therapy induces trophic-factors release, angiogenesis, anti-inflammation, and protein synthesis, which helps in the reparative process at the microcellular level. In this 5-year longitudinal study, the effect of autologous bone marrow mononuclear cells is studied on the natural course of 65 patients with LGMD. Functional Independence Measure and manual muscle testing showed statistically significant improvement, post-cell transplantation. The key finding of this study was demonstration of a plateau phase in the disease progression of the patients. No adverse events were noted. Autologous bone marrow mononuclear cells may be a novel, safe, and effective treatment approach to control the rate of progression of LGMD, thus improving the functional outcomes. Further randomized controlled trials are required.

Autologous bone marrow mononuclear cell transplantation in Duchenne muscular dystrophy - a case report

PATIENT

Male, 9 FINAL DIAGNOSIS: Duchenne muscular dystrophy Symptoms: Hyporeflexia • hypotonia • weaknes of lower limbs

MEDICATION

- Clinical Procedure: - Specialty: Neurology.

OBJECTIVE

Congenital defects/diseases.

BACKGROUND

Duchenne muscular dystrophy (DMD) is a fatal, genetic, progressive, degenerating muscle disorder. Current treatment options are palliative. Newer options of cellular therapy promise to alter the disease process. Preclinical studies have successfully tested myogenic, neurogenic potential and dystrophin expression of bone marrow mononuclear cells.

CASE REPORT

We treated a 9-year-old boy suffering from DMD with serial autologous bone marrow mononuclear cell transplantations followed by multidisciplinary rehabilitation. Brooke-Vignos score was 10 and he was wheelchair-bound. Over 36 months, gradual progressive improvement was noticed in muscle strength, ambulation with assistive devices, fine motor movements, Brooke-Vignos score, and functional independence measure score. Nine months after the transplantation, electromyography findings showed development of new normal motor unit potentials of the vastus medialis muscle.

CONCLUSIONS

Magnetic resonance imaging scan of musculoskeletal systems showed no increase in fatty infiltration. This case report provides early investigative findings or the restorative effects of cellular therapy in DMD.

Cellular Transplantation Alters the Disease Progression in Becker's Muscular Dystrophy

Becker's Muscular Dystrophy (BMD) is a dystrophinopathy manifested as progressive muscle degeneration. Autologous Bone Marrow Mononuclear Cells (BMMNCs) have shown some myogenic potential. The paracrine effects of the BMMNCs reduce the inflammation and are thought to reduce muscle degeneration. We treated a 39 year old dental surgeon suffering from BMD. Muscle strength was reduced when measured using modified Medical Research Council's Manual Muscle Testing (mMRC-MMT). Static sitting balance was poor. He was wheelchair dependent for ambulation and moderately independent in Activities of Daily Living (ADL). Functional Independence Measure (FIM) score was 93. Musculoskeletal Magnetic Resonance Imaging (MRI-MSK) showed moderate fatty infiltration in the muscles. Three cellular transplantations were carried out. Clinical assessment and the investigations were repeated. Progressive increase in the muscle strength was noted. Ambulation was independent using push-knee splints and minimal assistance when weary. Static and dynamic balance in sitting and standing improved. FIM score increased from 93 to 105. There was no increase in the degree of fatty infiltration, as seen on the MRI-MSK. The case study provides evidence for the putative benefits of cellular therapy in altering the disease progression in BMD. It also suggests augmented clinical benefits of combination of cellular therapy and rehabilitation.

Satellite glial cells in sympathetic and parasympathetic ganglia: in search of function

Glial cells are established as essential for many functions of the central nervous system, and this seems to hold also for glial cells in the peripheral nervous system. The main type of glial cells in most types of peripheral ganglia - sensory, sympathetic, and parasympathetic - is satellite glial cells (SGCs). These cells usually form envelopes around single neurons, which create a distinct functional unit consisting of a neuron and its attending SGCs. This review presents the knowledge on the morphology of SGCs in sympathetic and parasympathetic ganglia, and the (limited) available information on their physiology and pharmacology. It appears that SGCs carry receptors for ATP and can thus respond to the release of this neurotransmitter by the neurons. There is evidence that SGCs have an uptake mechanism for GABA, and possibly other neurotransmitters, which enables them to control the neuronal microenvironment. Damage to post- or preganglionic nerve fibers influences both the ganglionic neurons and the SGCs. One major consequence of postganglionic nerve section is the detachment of preganglionic nerve terminals, resulting in decline of synaptic transmission. It appears that, at least in sympathetic ganglia, SGCs participate in the detachment process, and possibly in the subsequent recovery of the synaptic connections. Unlike sensory neurons, neurons in autonomic ganglia receive synaptic inputs, and SGCs are in very close contact with synaptic boutons. This places the SGCs in a position to influence synaptic transmission and information processing in autonomic ganglia, but this topic requires much further work.