Joachim Schessl

Proteomic identification of FHL1 as the protein mutated in human reducing body myopathy

Reducing body myopathy (RBM) is a rare disorder causing progressive muscular weakness characterized by aggresome-like inclusions in the myofibrils. Identification of genes responsible for RBM by traditional genetic approaches has been impossible due to the frequently sporadic occurrence in affected patients and small family sizes. As an alternative approach to gene identification, we used laser microdissection of intracytoplasmic inclusions identified in patient muscle biopsies, followed by nanoflow liquid chromatography-tandem mass spectrometry and proteomic analysis. The most prominent component of the inclusions was the Xq26.3-encoded four and a half LIM domain 1 (FHL1) protein, expressed predominantly in skeletal but also in cardiac muscle. Mutational analysis identified 4 FHL1 mutations in 2 sporadic unrelated females and in 2 families with severely affected boys and less-affected mothers. Transfection of kidney COS-7 and skeletal muscle C2C12 cells with mutant FHL1 induced the formation of aggresome-like inclusions that incorporated both mutant and wild-type FHL1 and trapped other proteins in a dominant-negative manner. Thus, a novel laser microdissection/proteomics approach has helped identify both inherited and de novo mutations in FHL1, thereby defining a new X-linked protein aggregation disorder of muscle.

Intravenously Administered Immunoglobulin in the Treatment of Childhood Guillain-Barré Syndrome: A Randomized Trial

Objective. To determine the optimal treatment for childhood Guillain-Barré syndrome (GBS). Methods. We performed a randomized, multicenter study of GBS according to international diagnostic criteria. In study 1 (early treatment), children able to walk unaided for 5 meters were randomized for 1 g/kg intravenously administered immunoglobulin (IVIG) over 2 days or no treatment. The primary outcome measure was the degree of disability at nadir. In study 2 (treatment for severe GBS), children unable to walk 5 meters unaided were randomized for 1 g/kg IVIG over 2 days or 0.4 g/kg IVIG over 5 days. The primary outcome measure was the number of days needed to regain the ability to walk unaided. Children randomized for no treatment in study 1 could enter study 2 if loss of unaided walking occurred. Results. Ninety-five children with GBS were registered in 40 months. Twenty-one children were randomized in study 1 and 51 in study 2 (5 after deterioration in study 1). Twenty-eight children were not randomized for various reasons. Eleven of 21 patients in study 1 lost the ability to walk unassisted and 6 were bedridden, with no statistically significant difference between the children initially randomized for treatment versus no treatment. Recovery occurred faster in the group randomized for early treatment. In study 2, recovery did not differ significantly between the children treated for 2 days versus 5 days (median time to unaided walking: 19 days vs 13 days). Secondary transient deterioration in the disability score occurred more frequently in the group with the 2-day regimen than in the group treated for 5 days (5 of 23 patients vs 0 of 23 patients). Multivariate analysis with Cox regression showed that disease severity at the nadir was the only prognostic factor for recovery. Conclusions. Treatment with IVIG before loss of unaided walking did not give rise to a less severe course, but recovery occurred somewhat faster. However, given the small number of patients, the power of this conclusion is low. For treatment after loss of unaided walking, there was no significant difference in the effectiveness of 2 g/kg IVIG administered over 2 days versus 5 days. Early “relapses” occurred more frequently after the shorter treatment regimen.

Identification of FHL1 as a regulator of skeletal muscle mass: implications for human myopathy.

Regulators of skeletal muscle mass are of interest, given the morbidity and mortality of muscle atrophy and myopathy. Four-and-a-half LIM protein 1 (FHL1) is mutated in several human myopathies, including reducing-body myopathy (RBM). The normal function of FHL1 in muscle and how it causes myopathy remains unknown. We find that FHL1 transgenic expression in mouse skeletal muscle promotes hypertrophy and an oxidative fiber-type switch, leading to increased whole-body strength and fatigue resistance. Additionally, FHL1 overexpression enhances myoblast fusion, resulting in hypertrophic myotubes in C2C12 cells, (a phenotype rescued by calcineurin inhibition). In FHL1-RBM C2C12 cells, there are no hypertrophic myotubes. FHL1 binds with the calcineurin-regulated transcription factor NFATc1 (nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1), enhancing NFATc1 transcriptional activity. Mutant RBM-FHL1 forms aggregate bodies in C2C12 cells, sequestering NFATc1 and resulting in reduced NFAT nuclear translocation and transcriptional activity. NFATc1 also colocalizes with mutant FHL1 to reducing bodies in RBM-afflicted skeletal muscle. Therefore, via NFATc1 signaling regulation, FHL1 appears to modulate muscle mass and strength enhancement.

Clinical, histological and genetic characterization of reducing body myopathy caused by mutations in FHL1

We recently identified the X-chromosomal four and a half LIM domain gene FHL1 as the causative gene for reducing body myopathy, a disorder characterized by progressive weakness and intracytoplasmic aggregates in muscle that exert reducing activity on menadione nitro-blue-tetrazolium (NBT). The mutations detected in FHL1 affected highly conserved zinc coordinating residues within the second LIM domain and lead to the formation of aggregates when transfected into cells. Our aim was to define the clinical and morphological phenotype of this myopathy and to assess the mutational spectrum of FHL1 mutations in reducing body myopathy in a larger cohort of patients. Patients were ascertained via the detection of reducing bodies in muscle biopsy sections stained with menadione-NBT followed by clinical, histological, ultrastructural and molecular genetic analysis. A total of 11 patients from nine families were included in this study, including seven sporadic patients with early childhood onset disease and four familial cases with later onset. Weakness in all patients was progressive, sometimes rapidly so. Respiratory failure was common and scoliosis and spinal rigidity were significant in some of the patients. Analysis of muscle biopsies confirmed the presence of aggregates of FHL1 positive material in all biopsies. In two patients in whom sequential biopsies were available the aggregate load in muscle sections appeared to increase over time. Ultrastructural analysis revealed that cytoplasmic bodies were regularly seen in conjunction with the reducing bodies. The mutations detected were exclusive to the second LIM domain of FHL1 and were found in both sporadic as well as familial cases of reducing body myopathy. Six of the nine mutations affected the crucial zinc coordinating residue histidine 123. All mutations in this residue were de novo and were associated with a severe clinical course, in particular in one male patient (H123Q). Mutations in the zinc coordinating residue cysteine 153 were associated with a milder phenotype and were seen in the familial cases in which the boys were still more severely affected compared to their mothers. We expect the mild end of the spectrum to significantly expand in the future. On the severe end of the spectrum we define reducing body myopathy as a progressive disease with early, but not necessarily congenital onset, distinguishing this condition from the classic essentially non-progressive congenital myopathies.

MRI in DNM2-related centronuclear myopathy: Evidence for highly selective muscle involvement

Dynamin 2 has recently been recognized as a causative gene for the autosomal dominant form of centronuclear myopathy (dominant centronuclear myopathy). Here we report an affected father and daughter with dynamin 2 related AD CNM with predominantly distal onset of weakness. In addition to the diagnostic central location of myonuclei the muscle biopsy also showed core-like structures. Muscle MRI in the lower leg revealed prominent involvement of the soleus, but also of the gastrocnemius and the tibialis anterior whereas in the thigh there was a consistent pattern of selective involvement of adductor longus, semimembranosus, biceps femoris, rectus femoris, and vastus intermedius with relative sparing of vastus lateralis and medialis, sartorius, gracilis, and partly of the semitendinosus. These characteristic findings on muscle MRI confirm similar findings reported for CT imaging in dynamin 2 related dominant centronuclear myopathy and may help to differentiate this disorder from central core disease and other myopathies.

The p.G154S mutation of the alpha-B crystallin gene (CRYAB) causes late-onset distal myopathy.

Mutations in alpha-B crystallin gene (CRYAB) have been described to cause congenital cataracts, dilated cardiomyopathy and myofibrillar myopathy. For skeletal myopathy, only three different mutations have been reported within the last decade. Here we describe for the first time the missense mutation p.Gly154Ser to be associated with a late-onset distal vacuolar myopathy with protein aggregates without respiratory or cardiac dysfunction, and without significant cataracts. The mutation affects a residue in a highly preserved domain of alpha-B crystallin and has been identified earlier in patients with isolated cardiomyopathy.

Treatment of Duchenne muscular dystrophy with ciclosporin A: a randomised, double-blind, placebo-controlled multicentre trial

BACKGROUND Duchenne muscular dystrophy is a rare X-linked progressive disease characterised by loss of ambulation at about age 10 years, with death in early adulthood due to respiratory and cardiac insufficiency. Steroids are effective at slowing the progression of muscle weakness; however, their use is limited by side-effects, prompting the search for alternatives. We assessed the effect of ciclosporin A as monotherapy and in combination with intermittent prednisone for the treatment of ambulant patients with this disorder. METHODS Our study was a parallel-group, placebo-controlled, double-blind, multicentre trial at trial sites of the German muscular dystrophy network, MD-NET, over 36 months. Ambulant patients with Duchenne muscular dystrophy who were aged 5 years or older were randomly assigned to receive either ciclosporin A (3·5-4·0 mg/kg per day) or matching placebo. Allocation was done centrally with computer-generated random numbers. Patients and investigators were masked to the allocated treatment. After 3 months of treatment, both groups were also given intermittent prednisone for a further 12 months (0·75 mg/kg, alternating 10 days on with 10 days off). All patients who received at least one dose of study drug or placebo were included in the primary analysis. The primary outcome measure was manual muscle strength measured on the Medical Research Council (MRC) scale. This trial is registered with the German clinical trial register DRKS, number DRKS00000445. FINDINGS 77 patients were randomly assigned to the ciclosporin A group and 76 to the placebo group; 73 patients on ciclosporin A and 73 on placebo received at least one dose and were available for efficacy analyses. 3 months of treatment with ciclosporin A alone did not show any significant improvement in primary outcome measures (mean change in the proportion of a possible total MRC score [%MRC] was -2·6 [SD 6·0] for patients on ciclosporin A and -0·8 [4·9] for patients on placebo; adjusted group difference estimate -0·88, 97·5% CI -2·6 to 0·9; p=0·26). The combination of ciclosporin A with intermittent steroids was not better than intermittent steroids alone over 12 months (mean change in %MRC was 0·7 [7·1] for patients on ciclosporin A and -0·3 [7·9] for patients on placebo; adjusted group difference estimate -0·85, -3·6 to 1·9; p=0·48). Numbers of adverse events (75 in patients on ciclosporin A and 74 on placebo) and serious adverse events (four with ciclosporin A and four with placebo) did not differ significantly between groups. INTERPRETATION Ciclosporin A alone or in combination with intermittent prednisone does not improve muscle strength or functional abilities in ambulant boys with Duchenne muscular dystrophy, but is safe and well tolerated. FUNDING German Federal Ministry of Education and Research, Action Benni and co eV, Novartis Pharma AG, and Deutsche Gesellschaft für Muskelkranke eV.

Reducing Body Myopathy and Other FHL1-Related Muscular Disorders

During the past 2 years, considerable progress in the field of four and a half LIM domain protein 1 (FHL1)-related myopathies has led to the identification of a growing number of FHL1 mutations. This genetic progress has uncovered crucial pathophysiological concepts, thus redefining clinical phenotypes. Important new characterizations include 4 distinct human myopathies: reducing body myopathy, X-linked myopathy with postural muscle atrophy, Emery-Dreifuss muscular dystrophy, and scapuloperoneal myopathy. Additionally, FHL1 mutations have been discovered in rigid spine syndrome and in a single family with contractures, rigid spine, and cardiomyopathy. In this review, we focus on the clinical phenotypes, which we correlate with the novel genetic and histological findings encountered within FHL1-related myopathies. This correlation will frequently lead to a considerably expanded clinical spectrum associated with a given FHL1 mutation.

Prospective study on anti-ganglioside antibodies in childhood Guillain-Barré syndrome

Background: Antiganglioside antibodies have been reported to play a part in the pathophysiology of Guillain–Barré syndrome (GBS). Aims: To investigate the prevalence and correlation of anti-ganglioside antibodies with clinical data in children with GBS in a multicentre clinical trial. Methods: Immunoglobin (Ig)G and IgM to GM1, GM1b, GD1a, GalNAc–GD1a, GD1b, GT1a, and GQ1b were measured by ELISA in sera obtained before treatment. In addition, serological testing for Campylobacter jejuni was carried out. In parallel, a group of adults with GBS and a control group of children without GBS or other inflammatory diseases were evaluated. Results: Sera from 63 children with GBS, 36 adults with GBS and 41 children without GBS were evaluated. Four of the children with GBS showed positive IgG to GM1, in one case combined with anti-GalNAc–GD1a and in one with anti-GD1b. Two others showed isolated positive IgG to GD1b and GT1a. One showed increased anti-GalNAc–GD1a IgM. In 5 of the 63 children, serological evidence of a recent infection with C jejuni was found, and this correlated significantly with the raised antibodies (p = 0.001). In the control group without GBS, no child showed positive IgG, but one showed anti-GalNAc–GD1a IgM. Compared with the adults with GBS, the frequency of antibodies in children was insignificantly lower. In our study, patients with positive antibodies did not show a more severe GBS course or worse outcome than those who were seronegative, and we could not show an increased incidence of axonal dysfunction. Conclusions: In some children with GBS, one can detect raised IgG against various gangliosides, similar to that in adults. A recent infection with C jejuni is markedly associated with the presence of these antibodies. However, in contrast with what has been reported in adults, in this study we were unable to show a negative effect of these findings on the clinical course.

Predominant fiber atrophy and fiber type disproportion in early ullrich disease.

Ullrich disease (congenital muscular dystrophy type Ullrich, UCMD) is a severe congenital disorder of muscle caused by recessive and dominant mutations in the three genes that encode the α‐chains of collagen type VI. Little is known about the early pathogenesis of this myopathy. The aim of this study was to investigate early histological changes in muscle of patients with molecularly confirmed UCMD. Muscle biopsies were analyzed from 8 UCMD patients ranging in age from 6 to 30 months. Type I fiber atrophy and predominance were seen early, together with a widening of the fiber diameter spectrum, whereas no dystrophic features were apparent. A subpopulation of more severely atrophic type I fibers was apparent subsequently, including one biopsy that fulfilled the formal diagnostic criteria of histopathological fiber type disproportion (FTD). Thus, early in the disease, UCMD presents as a non‐dystrophic myopathy with predominant fiber atrophy. Collagen VI mutations also qualify as a cause of fiber type disproportion. Muscle Nerve 38: 1184–1191, 2008