Diagnosis and Clinical Development of Sporadic Inclusion Body Myositis and Polymyositis With Mitochondrial Pathology: A Single-Center Retrospective Analysis.

To review our diagnostic and treatment approaches concerning sporadic inclusion body myositis (sIBM) and polymyositis with mitochondrial pathology (PM-Mito), we conducted a retrospective analysis of clinical and histological data of 32 patients diagnosed as sIBM and 7 patients diagnosed as PM-Mito by muscle biopsy. Of 32 patients identified histologically as sIBM, 19 fulfilled the 2011 European Neuromuscular Center (ENMC) diagnostic criteria for "clinico-pathologically defined sIBM" at the time of biopsy. Among these, 2 patients developed sIBM after years of immunosuppressive treatment for organ transplantation. Of 11 patients fulfilling the histological but not the clinical criteria, including 3 cases with duration <12 months, 8 later fulfilled the criteria for clinico-pathologically defined sIBM. Of 7 PM-Mito patients, 4 received immunosuppression with clinical improvement in 3. One of these later developed clinico-pathologically defined sIBM; 1 untreated patient progressed to clinically defined sIBM. Thus, muscle histology remains important for this differential diagnosis to identify sIBM patients not matching the ENMC criteria and the PM-Mito group. In the latter, we report at least 50% positive, if occasionally transient, response to immunosuppressive treatments and progression to sIBM in a minority. The mitochondrial abnormalities defining PM-Mito do not seem to define the threshold to immunosuppression unresponsiveness.

Early Changes in Skeletal Muscle of Young C22 Mice, A Model of Charcot-Marie-Tooth 1A.

BACKGROUND: The C22 mouse is a Charcot-Marie-Tooth 1A transgenic model with minimal axonal loss. OBJECTIVE: To analyse early skeletal muscle changes resulting from this dysmyelinating neuropathy. METHODS: Histology of tibialis anterior muscles of C22 mice and wild type litter mate controls for morphometric analysis and (immuno-)histochemistry for known denervation markers and candidate proteins identified by representational difference analysis (RDA) based on mRNA from the same muscles; quantitative PCR and Western blotting for confirmation of RDA findings. RESULTS: At age 10 days, morphometry was not different between groups, while at 21 days, C22 showed significantly more small diameter fibres, indicating the onset of atrophy at an age when weakness becomes detectable. Neither (immuno-)histochemistry nor RDA detected extrajunctional expression of acetylcholine receptors by age 10 and 21 days, respectively. RDA identified some mRNA up-regulated in C22 muscles, among them at 10 days, prior to detectable weakness or atrophy, integral membrane protein 2a (Itm2a), eukaryotic initiation factor 2, subunit 2 (Eif2s2) and cytoplasmic phosphatidylinositol transfer protein 1 (Pitpnc1). However, qPCR failed to measure significant differences. In contrast, Itm2a and Eif2s2 mRNA were significantly down-regulated comparing 21 versus 10 days of age in both groups, C22 and controls. Western blotting confirmed significant down-regulation of ITM2A protein in C22 only. CONCLUSION: Denervation-like changes in this model develop slowly with onset of atrophy and weakness at about three weeks of age, before detection of extrajunctional acetylcholine receptors. Altered Itm2a expression seems to begin early as an increase, but becomes distinct as a decrease later.

Endoplasmic Reticulum Stress Induces Myostatin High Molecular Weight Aggregates and Impairs Mature Myostatin Secretion.

Sporadic inclusion body myositis (sIBM) is the most prevalent acquired muscle disorder in the elderly with no defined etiology or effective therapy. Endoplasmic reticulum stress and deposition of myostatin, a secreted negative regulator of muscle growth, have been implicated in disease pathology. The myostatin signaling pathway has emerged as a major target for symptomatic treatment of muscle atrophy. Here, we systematically analyzed the maturation and secretion of myostatin precursor MstnPP and its metabolites in a human muscle cell line. We find that increased MsntPP protein levels induce ER stress. MstnPP metabolites were predominantly retained within the endoplasmic reticulum (ER), also evident in sIBM histology. MstnPP cleavage products formed insoluble high molecular weight aggregates, a process that was aggravated by experimental ER stress. Importantly, ER stress also impaired secretion of mature myostatin. Reduced secretion and aggregation of MstnPP metabolites were not simply caused by overexpression, as both events were also observed in wildtype cells under ER stress. It is tempting to speculate that reduced circulating myostatin growth factor could be one explanation for the poor clinical efficacy of drugs targeting the myostatin pathway in sIBM.

Evaluation of the long-term efficacy of K-Othrine® PolyZone on three surfaces against laboratory reared Anopheles gambiae in semi-field conditions.

BACKGROUND: In this semi-field study, a new polymer-enhanced deltamethrin formulation, K-Othrine® PolyZone, was compared to a standard deltamethrin product for residual activity against a susceptible strain of laboratory-reared Anopheles gambiae using standard WHO cone bioassays. METHODS: Residual insecticide efficacy was recorded after exposure to metal, cement and wood panels maintained in experimental huts in sub-tropical environmental conditions in north central Florida, USA, and panels stored in a climate controlled chamber located at the Centers for Disease Control and Prevention, Georgia, USA. CONCLUSIONS: K-Othrine® PolyZone demonstrated 100% control on metal and cement panels 1 year post application and > 80% control on wood panels up to 6 mo. The new formulation should be considered for use in indoor residual spray programmes requiring long-term control of malaria vectors.

Cycling exercise-induced myofiber transitions in skeletal muscle depend on basal fiber type distribution.

The link between specific changes in myofiber type proportions and modulation of training in human skeletal muscle has yet to be unraveled. We investigated whether a defined increase in training volume induces a corresponding change of myofiber shifting in human skeletal muscle with distinct basal myofiber distribution. Twenty-one male cyclists (Age 26 ± 4 years) with different performance levels were exposed to increased cycling training volume with reduced power output for 3 months. Biopsies were taken from vastus lateralis muscle PRE-POST and the proportions of type I, IIa, IIx and IIc myofibers were determined. Total training time did not correlate to the degree of fiber type shifting of any type. In the entire sample of subjects, the proportion of type I myofibers tended to increase (P = 0.14) while IIa fibers decreased significantly (P < 0.05). Subgroups of subjects possessing higher (HPS) and lower proportions (LPS) of type I myofibers at baseline showed a distinct pattern in changing myofiber distribution. Subjects in HPS offered no change in myofiber proportions of any type. In contrast, subjects in LPS showed marked increases in type I (P = 0.06) and a significant reduction in IIa myofibers (P = 0.01). An inverse correlation between baseline proportion of type I and IIa myofibers and its change was observed. We conclude that individual myofiber composition constitutes a modulating factor for exercise-induced changes in its distribution. This might be influenced by altered demands of myofiber recruitment in relation to the intensity of muscle contraction but also by its relative abundance in contracting muscle.

Neurocognitive performance in children and adolescents with bipolar disorder: a review.

A number of studies have reported the evidence of cognitive deficits in adult bipolar patients. Recently, there has been a shift in research on neurocognitive performance in bipolar disorder (BD) towards examining younger age groups. A review of the literature on neurocognitive impairments in BD in childhood and adolescence was conducted. We searched systematically for studies in samples of age groups younger than 18 years of age in average that included either a healthy control group or normative data for the cognitive tests used. Twenty-one original articles were found and reviewed. Children and adolescents with BD show deficits in a variety of cognitive areas. The most consistent results were found for impairments in verbal memory. A majority of studies also indicated impairments in working memory. Similar pattern of neurocognitive impairment was found in children and adolescents as compared to adults suffering from BD. The neurocognitive deficits need to be recognized and incorporated into individual treatment programs.

Macrophage migration inhibitory factor in normal human skeletal muscle and inflammatory myopathies.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine secreted by activated T cells and macrophages that has antiapoptotic, proproliferative, and chemotactic effects. Because these cells are major components of many muscle disorders with different etiologies, we investigated the amount and distribution of MIF in inflammatory myopathies. Concentrations of MIF in protein lysates from dermatomyositis (n = 6), polymyositis (n = 7), sporadic inclusion body myositis (n = 9) muscle samples and control biopsies without specific changes (n = 10) were determined by ELISA. In polymyositis, MIF concentrations were higher than in controls (p<0.05), whereas they were not significantly different in other inflammatory myopathies. By immunohistochemistry, MIF was detected not only in inflammatory cells, but also at muscle fiber membranes where they were invaded or bordered infiltrates or necrotic fibers; focal sarcoplasmic reactivity was also observed. A similar distribution was found in areas of infiltration, necrosis, myophagocytosis, degeneration, and regeneration in 8 muscular dystrophy samples. The expression of MIF was verified in human myogenic tissue cultures; MIF immunoreactivity decreased with progressive differentiation, and its distribution changed. These data suggest that MIF is a skeletal muscle cytokine with probable functions beyond inflammatory pathology in the complex regenerative response to muscle fiber damage.

Interleukin-1 regulates hematopoietic progenitor and stem cells in the midgestation mouse fetal liver.

BACKGROUND: Hematopoietic progenitors are generated in the yolk sac and aorta-gonad-mesonephros region during early mouse development. At embryonic day 10.5 the first hematopoietic stem cells emerge in the aorta-gonad-mesonephros. Subsequently, hematopoietic stem cells and progenitors are found in the fetal liver. The fetal liver is a potent hematopoietic site, playing an important role in the expansion and differentiation of hematopoietic progenitors and hematopoietic stem cells. However, little is known concerning the regulation of fetal liver hematopoietic stem cells. In particular, the role of cytokines such as interleukin-1 in the regulation of hematopoietic stem cells in the embryo has been largely unexplored. Recently, we observed that the adult pro-inflammatory cytokine interleukin-1 is involved in regulating aorta-gonad-mesonephros hematopoietic progenitor and hematopoietic stem cell activity. Therefore, we set out to investigate whether interleukin-1 also plays a role in regulating fetal liver progenitor cells and hematopoietic stem cells. DESIGN AND METHODS: We examined the interleukin-1 ligand and receptor expression pattern in the fetal liver. The effects of interleukin-1 on hematopoietic progenitor cells and hematopoietic stem cells were studied by FACS and transplantation analyses of fetal liver explants, and in vivo effects on hematopoietic stem cell and progenitors were studied in Il1r1(-/-) embryos. RESULTS: We show that fetal liver hematopoietic progenitor cells express the IL-1RI and that interleukin-1 increases fetal liver hematopoiesis, progenitor cell activity and promotes hematopoietic cell survival. Moreover, we show that in Il1r1(-/-) embryos, hematopoietic stem cell activity is impaired and myeloid progenitor activity is increased. CONCLUSIONS: The IL-1 ligand and receptor are expressed in the midgestation liver and act in the physiological regulation of fetal liver hematopoietic progenitor cells and hematopoietic stem cells.

The oral antidiabetic pioglitazone protects from neurodegeneration and amyotrophic lateral sclerosis-like symptoms in superoxide dismutase-G93A transgenic mice.

Amyotrophic lateral sclerosis (ALS) represents a fatal neurodegenerative disorder characterized by progressive death of the upper and lower motor neurons. Because accompanying inflammation may interact with and promote neurodegeneration, anti-inflammatory treatment strategies are being evaluated. Because peroxisome proliferator-activated receptor gamma (PPARgamma) agonists act as potent anti-inflammatory drugs, we tested whether superoxide dismutase (SOD1)-G93A transgenic mice, a mouse model of ALS, benefit from oral treatment with the PPARgamma agonist pioglitazone (Pio). Pio-treated transgenic mice revealed improved muscle strength and body weight, exhibited a delayed disease onset, and survived significantly longer than nontreated SOD1-G93A mice. Quantification of motor neurons of the spinal cord at day 90 revealed complete neuroprotection by Pio, whereas nontreated SOD1-G93A mice had lost 30% of motor neurons. This was paralleled by preservation of the median fiber diameter of the quadriceps muscle, indicating not only morphological but also functional protection of motor neurons by Pio. Activated microglia were significantly reduced at sites of neurodegeneration in Pio-treated SOD1-G93A mice, as were the protein levels of cyclooxygenase 2 and inducible nitric oxide synthase. Interestingly, mRNA levels of the suppressor of cytokine signaling 1 and 3 genes were increased by Pio, whereas both the mRNA and protein levels of endogenous mouse SOD1 and of transgenic human SOD1 remained unaffected.

The role of apoptosis in the development of AGM hematopoietic stem cells revealed by Bcl-2 overexpression.

Apoptosis is an essential process in embryonic tissue remodeling and adult tissue homeostasis. Within the adult hematopoietic system, it allows for tight regulation of hematopoietic cell subsets. Previously, it was shown that B-cell leukemia 2 (Bcl-2) overexpression in the adult increases the viability and activity of hematopoietic cells under normal and/or stressful conditions. However, a role for apoptosis in the embryonic hematopoietic system has not yet been established. Since the first hematopoietic stem cells (HSCs) are generated within the aortagonad-mesonephros (AGM; an actively remodeling tissue) region beginning at embryonic day 10.5, we examined this tissue for expression of apoptosis-related genes and ongoing apoptosis. Here, we show expression of several proapoptotic and antiapoptotic genes in the AGM. We also generated transgenic mice overexpressing Bcl-2 under the control of the transcriptional regulatory elements of the HSC marker stem cell antigen-1 (Sca-1), to test for the role of cell survival in the regulation of AGM HSCs. We provide evidence for increased numbers and viability of Sca-1(+) cells in the AGM and subdissected midgestation aortas, the site where HSCs are localized. Most important, our in vivo transplantation data show that Bcl-2 overexpression increases AGM and fetal liver HSC activity, strongly suggesting that apoptosis plays a role in HSC development.

Mitochondrial dysfunction in myofibrillar myopathy.

'Myofibrillar myopathy' defines a myopathic condition with focal myofibrillar destruction and accumulation of degraded myofibrillar elements. Despite the fact that a number of mutations in different genes as well as cytotoxic agents lead to the disease, abnormal accumulation of desmin is a typical, common feature. Pathological changes of mitochondrial morphology and function have been observed in animal models with intermediate filament pathology. Therefore, in the present study we tested for mitochondrial pathology in skeletal muscle of five patients with the pathohistological diagnosis of myofibrillar myopathy. Screening for large-scale mtDNA deletions and the frequent MERRF (myoclonic epilepsy; ragged red fibres) and MELAS (mitochondrial encephalomyopathy; lactic acidosis; stroke) point mutations was negative in all patients. Histologically, all muscle biopsies showed nonspecific abnormalities of the oxidative/mitochondrial enzyme stainings (histochemistry for reduced nicotinamide adenine dinucleotide, succinic dehydrogenase, cytochrome c oxidase), only one of them had ragged red fibres and a significant number of cytochrome c oxidase-negative fibres. Upon biochemical investigation, four of our patients showed pathologically low respiratory chain complex I activities. Only one of our patients had a pathologically low complex IV activity, while the measurements of the others were within low normal range. The single patient with pathological values for both complex I and IV was the one with the clear histological hallmarks (ragged red and cytochrome c oxidase-negative fibres) of mitochondrial pathology. She also was the only patient with clinical signs hinting at a mitochondrial disorder. Together with data from observations in desmin- and plectin-deficient mice, our results support the view that desmin intermediate filament pathology in these cases is closely linked to mitochondrial dysfunction in skeletal muscle.

The beta-catenin/TCF-4 complex imposes a crypt progenitor phenotype on colorectal cancer cells.

The transactivation of TCF target genes induced by Wnt pathway mutations constitutes the primary transforming event in colorectal cancer (CRC). We show that disruption of beta-catenin/TCF-4 activity in CRC cells induces a rapid G1 arrest and blocks a genetic program that is physiologically active in the proliferative compartment of colon crypts. Coincidently, an intestinal differentiation program is induced. The TCF-4 target gene c-MYC plays a central role in this switch by direct repression of the p21(CIP1/WAF1) promoter. Following disruption of beta-catenin/TCF-4 activity, the decreased expression of c-MYC releases p21(CIP1/WAF1) transcription, which in turn mediates G1 arrest and differentiation. Thus, the beta-catenin/TCF-4 complex constitutes the master switch that controls proliferation versus differentiation in healthy and malignant intestinal epithelial cells.

Disorganization of the desmin cytoskeleton and mitochondrial dysfunction in plectin-related epidermolysis bullosa simplex with muscular dystrophy.

Mutations of the human plectin gene (Plec1) cause autosomal recessive epidermolysis bullosa simplex with muscular dystrophy (EBS-MD). Here, we report on molecular mechanisms leading to severe dystrophic muscle alterations in EBS-MD. Analysis of a 25-yr-old EBS-MD patient carrying a novel homozygous 16-bp insertion mutation (13803ins16/13803ins16) close to the intermediate filament (IF) binding site of plectin showed severe disorganization of the myogenic IF cytoskeleton. Intermyofibrillar and subsarcolemmal accumulations of assembled but highly unordered desmin filaments may be attributed to impaired desmin binding capability of the mutant plectin. This IF pathology was also associated with severe mitochondrial dysfunction, suggesting that the muscle pathology of EBS-MD caused by IF disorganization leads not only to defects in mechanical force transduction but also to metabolic dysfunction. Beyond EBS-MD, our data may contribute to the understanding of other myopathies characterized by sarcoplasmic IF accumulations such as desminopathies or alpha-B-crystallinopathies.