Fascioscapulohumeral muscular dystrophy: a progressive degenerative disease that responds to diltiazem

Treatment of Facioscapulohumeral Muscular Dystrophy (FSHD): A Systematic Review

Facioscapulohumeral muscular dystrophy (FSHD) is the third most common type of muscular dystrophy. This disease presents as a slowly progressive asymmetric muscle weakness that involves the facial, scapular, and upper arm muscles mainly. Currently, there is no established consensus on this disease treatment in terms of medications. We assessed the response to the treatment of the drugs utilized in clinical trials by performing a systematic literature review in English using the preferred reporting items for systematic reviews (PRISMA) and meta-analyses. We only used human clinical trials in patients diagnosed with FSHD that received consistent pharmacological treatment. We included 11 clinical trials that fulfilled our criteria. We concluded that albuterol had statistically significant results in three out of four clinical trials, with improved elbow flexors muscle strength. Vitamin C, vitamin E, zinc gluconate, and selenomethionine showed significant improvement in the maximal voluntary contraction and endurance limit time of quadriceps muscle. At the same time, diltiazem and MYO-029 demonstrate no improvement in function, strength, or muscle mass. Losmapimod, currently in phase I of the ReDUX4 trial, showed promising results. Peradventure, more clinical trials are still needed to address this subject. Nevertheless, this review provides a clear and concise update on the treatment for this disease.

Purification and Biological Function of Caldecrin

Blood calcium homeostasis is critical for biological function. Caldecrin, or chymotrypsin-like elastase, was originally identified in the pancreas as a serum calcium-decreasing factor. The serum calcium-decreasing activity of caldecrin requires the trypsin-mediated activation of the protein. Protease activity-deficient mature caldecrin can also reduce serum calcium concentration, indicating that structural processing is necessary for serum calcium-decreasing activity. Caldecrin suppresses the differentiation of bone-resorbing osteoclasts from bone marrow macrophages (BMMs) by inhibiting receptor activator of NF-κB ligand (RANKL)-induced nuclear factor of activated T-cell cytoplasmic 1 expression via the Syk-PLCγ-Ca²⁺ oscillation-calcineurin signaling pathway. It also suppresses mature osteoclastic bone resorption by RANKL-stimulated TRAF6-c-Src-Syk-calcium entry and actin ring formation. Caldecrin inhibits lipopolysaccharide (LPS)-induced osteoclast formation in RANKL-primed BMMs by inducing the NF-κB negative regulator A20. In addition, caldecrin suppresses LPS-mediated M1 macrophage polarization through the immunoreceptor triggering receptor expressed on myeloid cells (TREM) 2, suggesting that caldecrin may function as an anti-osteoclastogenic and anti-inflammatory factor via TREM2. The ectopic intramuscular expression of caldecrin cDNA prevents bone resorption in ovariectomized mice, and the administration of caldecrin protein also prevents skeletal muscle destruction in dystrophic mice. In vivo and in vitro studies have indicated that caldecrin is a unique multifunctional protease and a possible therapeutic target for skeletal and inflammatory diseases.

Bilateral scapulothoracic arthrodesis for facioscapulohumeral muscular dystrophy: function, fusion, and respiratory consequences

BACKGROUND

Scapulothoracic arthrodesis (STA) has been proposed for the treatment of painful scapular winging in patients with facioscapulohumeral muscular dystrophy (FSHD). However, the rate of osseous fusion is variable, and there is a theoretical risk of reduced respiratory function after bilateral STA.

METHODS

This was a retrospective study of 10 STAs, performed sequentially, in 5 FSHD patients. The surgical technique involved use of a semitubular plate and wire construct with autograft (iliac crest) interposed between the scapula and rib cage. Osseous fusion, respiratory function, and shoulder function were evaluated. The mean follow-up period was 141 ± 67 months (range, 24-225 months).

RESULTS

Early complications included 1 pneumothorax and 1 pleural effusion. No late complications occurred, and no patients underwent reoperation. On postoperative computed tomography images, complete bony union of the scapula to the ribs was observed in 90% of shoulders (9 of 10). Comparison of preoperative and postoperative pulmonary function test results showed no significant difference in vital capacity (from 87% ± 14% to 85% ± 12%) and forced vital capacity (from 86% ± 16% to 77% ± 15%). Patients gained on average 40° of active forward elevation (from 62° ± 20° to 102° ± 4°) and 22° of abduction (from 58° ± 21° to 89° ± 7°) (P < .001). The mean Subjective Shoulder Value increased from 25% ± 8% to 72% ± 18% (P < .001). All patients were pleased with the results and would recommend the procedure to other persons.

CONCLUSION

In patients with FSHD, bilateral STA provides satisfactory shoulder function with a high rate of scapulothoracic fusion and few or no significant respiratory repercussions.

Facioscapulohumeral dystrophy: activating an early embryonic transcriptional program in human skeletal muscle

Facioscapulohumeral dystrophy (FSHD) is the third most prevalent muscular dystrophy. A progressive disease, it presents clinically as weakness and wasting of the face, shoulder and upper arm muscles, with later involvement of the trunk and lower extremities. FSHD develops through complex genetic and epigenetic events that converge on a common mechanism of toxicity with mis-expression of the transcription factor double homeobox 4 (DUX4). There is currently no treatment available for FSHD. However, the consensus that ectopic DUX4 expression in skeletal muscle is the root cause of FSHD pathophysiology has allowed research efforts to turn toward cultivating a deeper understanding of DUX4 biology and the pathways that underlie FSHD muscle pathology, and to translational studies aimed at developing targeted therapeutics using ever more sophisticated cell and animal-based models of FSHD. This review summarizes recent advances in our understanding of FSHD, including the regulation and activity of DUX4 in its normal developmental roles as well as its pathological contexts. We highlight how these advances raise new questions and challenges for the field as it moves into the next decade of FSHD research.

Facioscapulohumeral Muscular Dystrophy

PURPOSE OF REVIEW

This article describes the clinical characteristics, diagnosis, molecular pathogenesis, and treatment of facioscapulohumeral muscular dystrophy (FSHD).

RECENT FINDINGS

FSHD comprises two genetically distinct types that converge on a common downstream pathway of the expression of the toxic protein DUX4. Approximately 95% of patients have FSHD type 1 (FSHD1), in which loss of DNA repetitive elements (D4Z4 repeats) in the subtelomeric region of chromosome 4q causes decreased methylation and epigenetic derepression of DUX4, a gene contained within each D4Z4 repeat. FSHD type 2 (FSHD2) occurs through a deletion-independent mechanism but, similar to FSHD1, leads to decreased methylation and epigenetic derepression in the same region of chromosome 4q. Whereas FSHD1 is dominantly inherited, FSHD2 shows digenic inheritance, and about 80% of patients will have a mutation in the SMCHD1 gene. DUX4 lacks a polyadenylation signal, so both FSHD1 and FSHD2 only occur in the presence of permissive 4q polymorphisms, which provide a stabilizing polyadenylation sequence. FSHD is an epigenetic disease, and penetrance and severity are related to both the number of residual D4Z4 units and D4Z4 methylation.

SUMMARY

Recent consensus guidelines outline standards for care for FSHD, and identification of potential therapeutic targets have shifted emphasis in the research community toward drug development and clinical trial planning.

β-Catenin is central to DUX4-driven network rewiring in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an incurable disease, characterized by skeletal muscle weakness and wasting. Genetically, FSHD is characterized by contraction or hypomethylation of repeat D4Z4 units on chromosome 4, which causes aberrant expression of the transcription factor DUX4 from the last repeat. Many genes have been implicated in FSHD pathophysiology, but an integrated molecular model is currently lacking. We developed a novel differential network methodology, Interactome Sparsification and Rewiring (InSpiRe), which detects network rewiring between phenotypes by integrating gene expression data with known protein interactions. Using InSpiRe, we performed a meta-analysis of multiple microarray datasets from FSHD muscle biopsies, then removed secondary rewiring using non-FSHD datasets, to construct a unified network of rewired interactions. Our analysis identified β-catenin as the main coordinator of FSHD-associated protein interaction signalling, with pathways including canonical Wnt, HIF1-α and TNF-α clearly perturbed. To detect transcriptional changes directly elicited by DUX4, gene expression profiling was performed using microarrays on murine myoblasts. This revealed that DUX4 significantly modified expression of the genes in our FSHD network. Furthermore, we experimentally confirmed that Wnt/β-catenin signalling is affected by DUX4 in murine myoblasts. Thus, we provide the first unified molecular map of FSHD signalling, capable of uncovering pathomechanisms and guiding therapeutic development.

Altered expression of cyclin A 1 in muscle of patients with facioscapulohumeral muscle dystrophy (FSHD-1)

Objectives

Cyclin A1 regulates cell cycle activity and proliferation in somatic and germ-line cells. Its expression increases in G1/S phase and reaches a maximum in G2 and M phases. Altered cyclin A1 expression might contribute to clinical symptoms in facioscapulohumeral muscular dystrophy (FSHD).

Methods

Muscle biopsies were taken from the Vastus lateralis muscle for cDNA microarray, RT-PCR, immunohistochemistry and Western blot analyses to assess RNA and protein expression of cyclin A1 in human muscle cell lines and muscle tissue. Muscle fibers diameter was calculated on cryosections to test for hypertrophy.

Results

cDNA microarray data showed specifically elevated cyclin A1 levels in FSHD vs. other muscular disorders such as caveolinopathy, dysferlinopathy, four and a half LIM domains protein 1 deficiency and healthy controls. Data could be confirmed with RT-PCR and Western blot analysis showing up-regulated cyclin A1 levels also at protein level. We found also clear signs of hypertrophy within the Vastus lateralis muscle in FSHD-1 patients.

Conclusions

In most somatic human cell lines, cyclin A1 levels are low. Overexpression of cyclin A1 in FSHD indicates cell cycle dysregulation in FSHD and might contribute to clinical symptoms of this disease.

The outcome of scapulothoracic fusion for painful winging of the scapula in dystrophic and non-dystrophic conditions

Scapulothoracic fusion (STF) for painful winging of the scapula in neuromuscular disorders can provide effective pain relief and functional improvement, but there is little information comparing outcomes between patients with dystrophic and non-dystrophic conditions. We performed a retrospective review of 42 STFs in 34 patients with dystrophic and non-dystrophic conditions using a multifilament trans-scapular, subcostal cable technique supported by a dorsal one-third semi-tubular plate. There were 16 males and 18 females with a mean age of 30 years (15 to 75) and a mean follow-up of 5.0 years (2.0 to 10.6). The mean Oxford shoulder score improved from 20 (4 to 39) to 31 (4 to 48). Patients with non-dystrophic conditions had lower overall functional scores but achieved greater improvements following STF. The mean active forward elevation increased from 59° (20° to 90°) to 97° (30° to 150°), and abduction from 51° (10° to 90°) to 83° (30° to 130°) with a greater range of movement achieved in the dystrophic group. Revision fusion for nonunion was undertaken in five patients at a mean time of 17 months (7 to 31) and two required revision for fracture. There were three pneumothoraces, two rib fractures, three pleural effusions and six nonunions. The main risk factors for nonunion were smoking, age and previous shoulder girdle surgery.

STF is a salvage procedure that can provide good patient satisfaction in 82% of patients with both dystrophic and non-dystrophic pathologies, but there was a relatively high failure rate (26%) when poor outcomes were analysed. Overall function was better in patients with dystrophic conditions which correlated with better range of movement; however, patients with non-dystrophic conditions achieved greater functional improvement.

Treatment of facioscapulohumeral muscular dystrophy with Denosumab

BACKGROUND

Facioscapulohumeral muscular dystrophy (FSHD) is the 3(rd) most common form of muscular dystrophy. Effective treatments for any of the muscular dystrophies have yet to be realized. This report describes such a treatment.

CASE REPORT

A 66 year old female was diagnosed with osteoporosis. She had been diagnosed with FSHD muscular dystrophy a number of years previously by both genetic and clinical studies. Following a 2 year course with Forteo for osteoporosis, she was given an injection of Denosumab (Prolia) to maintain her bone density. By 24 hours, she exhibited increased strength and a dramatic reduction of her dystrophic symptoms e.g. she could walk unassisted in high heels. She was able to accomplish other things that had not been possible for a number of years. After approximately 5 weeks she gradually lost the newfound strength with a complete loss by about 6 weeks. A second injection of Denosumab resulted in the same effect, i.e. reversal of symptoms and increased functionality. A number of measurements and videos were taken to establish the beneficial effects of Prolia for future studies. This was repeated with a 3(rd) and 4(th) injection in order to establish the unequivocal beneficial effects on muscular dystrophy.

CONCLUSIONS

Further studies will be required to establish Denosumab as a major "front line" treatment for this disease and possibly other muscular dystrophies.

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is caused by a cascade of epigenetic events following contraction of the polymorphic macrosatellite repeat D4Z4 in the subtelomere of chromosome 4q. Currently, the central issue is whether immediate downstream effects are local (i.e., at chromosome 4q) or global (genome-wide) and there is evidence for both scenarios. Currently, there is no therapy for FSHD, mostly because of our lack of understanding of the primary pathogenic process in FSHD muscle. Clinical trials based on suppression of inflammatory reactions or increasing muscle mass by drugs or training have been disappointing. A recent, probably the first evidence-based pilot trial to revert epigenetic changes did also not provide grounds for a larger clinical study. Clearly, better disease models need to be developed to identify and test novel intervention strategies to eventually improve the quality of life for patients with FSHD.