Late adult-onset of X-linked myopathy with excessive autophagy

INTRODUCTION

X-linked myopathy with excessive autophagy (XMEA) is characterized by autophagic vacuoles with sarcolemmal features. Mutations in VMA21 result in insufficient lysosome acidification, causing progressive proximal weakness with onset before age 20 years and loss of ambulation by middle age.

METHODS

We describe a patient with onset of slowly progressive proximal weakness of the lower limbs after age 50, who maintains ambulation with the assistance of a cane at age 71.

RESULTS

Muscle biopsy at age 66 showed complex muscle fiber splitting, internalized capillaries, and vacuolar changes characteristic of autophagic vacuolar myopathy. Vacuoles stained positive for sarcolemmal proteins, LAMP2, and complement C5b-9. Ultrastructural evaluation further revealed basal lamina reduplication and extensive autophagosome extrusion. Sanger sequencing identified a known pathologic splice site mutation in VMA21 (c.164-7T>G).

CONCLUSIONS

This case expands the clinical phenotype of XMEA and suggests VMA21 sequencing be considered in evaluating men with LAMP2-positive autophagic vacuolar myopathy.

Increased laforin and laforin binding to glycogen underlie Lafora body formation in malin-deficient Lafora disease

The solubility of glycogen, essential to its metabolism, is a property of its shape, a sphere generated through extensive branching during synthesis. Lafora disease (LD) is a severe teenage-onset neurodegenerative epilepsy and results from multiorgan accumulations, termed Lafora bodies (LB), of abnormally structured aggregation-prone and digestion-resistant glycogen. LD is caused by loss-of-function mutations in the EPM2A or EPM2B gene, encoding the interacting laforin phosphatase and malin E3 ubiquitin ligase enzymes, respectively. The substrate and function of malin are unknown; an early counterintuitive observation in cell culture experiments that it targets laforin to proteasomal degradation was not pursued until now. The substrate and function of laforin have recently been elucidated. Laforin dephosphorylates glycogen during synthesis, without which phosphate ions interfere with and distort glycogen construction, leading to LB. We hypothesized that laforin in excess or not removed following its action on glycogen also interferes with glycogen formation. We show in malin-deficient mice that the absence of malin results in massively increased laforin preceding the appearance of LB and that laforin gradually accumulates in glycogen, which corresponds to progressive LB generation. We show that increasing the amounts of laforin in cell culture causes LB formation and that this occurs only with glycogen binding-competent laforin. In summary, malin deficiency causes increased laforin, increased laforin binding to glycogen, and LB formation. Furthermore, increased levels of laforin, when it can bind glycogen, causes LB. We conclude that malin functions to regulate laforin and that malin deficiency at least in part causes LB and LD through increased laforin binding to glycogen.

Novel POMGNT1 point mutations and intragenic rearrangements associated with muscle-eye-brain disease

Congenital muscular dystrophies due to defects in genes encoding proteins involved in α-dystroglycan (α-DG) glycosylation are a heterogeneous group of muscle disorders variably associated with central nervous system and eye abnormalities. One of the more severe is muscle-eye-brain disease (MEB). Mutations in genes coding for proven or putative glycosyltransferases (POMT1, POMT2, POMGnT1, fukutin, FKRP, and LARGE), the DPM3 gene encoding a DOL-P-Man synthase subunit, and the DAG1 gene encoding α-dystroglycan, have been associated with altered α-DG glycosylation.

We report new POMGnT1 mutations and evaluate protein expression in 3 patients and 2 foetuses with variably severe MEB features. We identify two new point mutations (c.643 C > T, c.1863delC), one new intragenic rearrangement (deletion of exons 2–8), and a new intron retention (between exons 21 and 22) resulting from a known point mutation c.1895 + 1 G > T. Our study provides further evidence that rearrangements of the POMGnT1 gene are relatively common. Importantly, if heterozygous, they can be missed on standard genomic DNA sequencing. POMGNT1 protein analysis in 3 patients showed that the severity of the phenotype does not correlate with protein expression. Cerebral MRI is important for identifying MEB and α-dystroglycanopathy phenotypes in children and foetuses, and hence for directing the genetic analysis.

Glycogen hyperphosphorylation underlies lafora body formation

OBJECTIVE

Glycogen, the largest cytosolic macromolecule, acquires solubility, essential to its function, through extreme branching. Lafora bodies are aggregates of polyglucosan, a long, linear, poorly branched, and insoluble form of glycogen. Lafora bodies occupy vast numbers of neuronal dendrites and perikarya in Lafora disease in time-dependent fashion, leading to intractable and fatal progressive myoclonus epilepsy. Lafora disease is caused by deficiency of either the laforin glycogen phosphatase or the malin E3 ubiquitin ligase. The 2 leading hypotheses of Lafora body formation are: (1) increased glycogen synthase activity extends glycogen strands too rapidly to allow adequate branching, resulting in polyglucosans; and (2) increased glycogen phosphate leads to glycogen conformational change, unfolding, precipitation, and conversion to polyglucosan. Recently, it was shown that in the laforin phosphatase-deficient form of Lafora disease, there is no increase in glycogen synthase, but there is a dramatic increase in glycogen phosphate, with subsequent conversion of glycogen to polyglucosan. Here, we determine whether Lafora bodies in the malin ubiquitin ligase-deficient form of the disease are due to increased glycogen synthase or increased glycogen phosphate.

METHODS

We generated malin-deficient mice and tested the 2 hypotheses.

RESULTS

Malin-deficient mice precisely replicate the pathology of Lafora disease with Lafora body formation in skeletal muscle, liver, and brain, and in the latter in the pathognomonic perikaryal and dendritic locations. Glycogen synthase quantity and activity are unchanged. There is a highly significant increase in glycogen phosphate.

INTERPRETATION

We identify a single common modification, glycogen hyperphosphorylation, as the root cause of Lafora body pathogenesis.

The effect of acupuncture on oral microcirculation in healthy volunteers: an exploratory study

BACKGROUND

acupuncture is a therapeutic technique currently used in the treatment of many pathologies. The aim of this study is to evaluate the potential effect of acupuncture on "in vivo" variations in oral microcirculation in healthy subjects.

METHODS

an exploratory study was conducted on 40 healthy subjects: 20 cases (mean 55.90, SD 16.04) and 20 controls (mean 51, SD 11.91). Videocapillaroscopy was used to detect variations in oral microcirculation. This method permits an accurate and non-invasive in vivo study of the capillaries of the oral mucous. The site selected for this pilot study is the lower lip since it is the simplest to investigate and is more readily accessible. Assessments were carried out in three phases: t(0) before the application of the needles; t(1) one minute after the application; t(2) five minutes after the application; similar time points were used for the control group. Data were compared using the Mann-Whitney test.

RESULTS

the study showed characteristic changes in oral microcirculation induced by acupuncture. The tortuousness of capillary loops and in the diameter of the afferent loop changed significantly (p<0.05) over time in the acupuncture group but not in the controls.

CONCLUSIONS

the findings lend support to our expectation that acupuncture may generate significant variations in oral microcirculation in healthy adults. Further research is needed to confirm these findings and evaluate the therapeutic role of acupuncture in oral pathologies.

Congenital muscular dystrophies with defective glycosylation of dystroglycan: a population study

BACKGROUND

Congenital muscular dystrophies (CMD) with reduced glycosylation of alpha-dystroglycan (alpha-DG) are a heterogeneous group of conditions associated with mutations in six genes encoding proven or putative glycosyltransferases.

OBJECTIVES

The aim of the study was to establish the prevalence of mutations in the six genes in the Italian population and the spectrum of clinical and brain MRI findings.

METHODS

As part of a multicentric study involving all the tertiary neuromuscular centers in Italy, FKRP, POMT1, POMT2, POMGnT1, fukutin, and LARGE were screened in 81 patients with CMD and alpha-DG reduction on muscle biopsy (n = 76) or with a phenotype suggestive of alpha-dystroglycanopathy but in whom a muscle biopsy was not available for alpha-DG immunostaining (n = 5).

RESULTS

Homozygous and compound heterozygous mutations were detected in a total of 43/81 patients (53%), and included seven novel variants. Mutations in POMT1 were the most prevalent in our cohort (21%), followed by POMT2 (11%), POMGnT1 (10%), and FKRP (9%). One patient carried two heterozygous mutations in fukutin and one case harbored a new homozygous variant in LARGE. No clear-cut genotype-phenotype correlation could be observed with each gene, resulting in a wide spectrum of clinical phenotypes. The more severe phenotypes, however, appeared to be consistently associated with mutations predicted to result in a severe disruption of the respective genes.

CONCLUSIONS

Our data broaden the clinical spectrum associated with mutations in glycosyltransferases and provide data on their prevalence in the Italian population.

Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients

Limb girdle muscular dystrophies (LGMD) are characterized by genetic and clinical heterogeneity: seven autosomal dominant and 12 autosomal recessive loci have so far been identified. Aims of this study were to evaluate the relative proportion of the different types of LGMD in 181 predominantly Italian LGMD patients (representing 155 independent families), to describe the clinical pattern of the different forms, and to identify possible correlations between genotype, phenotype, and protein expression levels, as prognostic factors. Based on protein data, the majority of probands (n=72) presented calpain-3 deficiency; other defects were as follows: dysferlin (n=31), sarcoglycans (n=32), alpha-dystroglycan (n=4), and caveolin-3 (n=2). Genetic analysis identified 111 different mutations, including 47 novel ones. LGMD relative frequency was as follows: LGMD1C (caveolin-3) 1.3%; LGMD2A (calpain-3) 28.4%; LGMD2B (dysferlin) 18.7%; LGMD2C (gamma-sarcoglycan) 4.5%; LGMD2D (alpha-sarcoglycan) 8.4%; LGMD2E (beta-sarcoglycan) 4.5%; LGMD2F (delta-sarcoglycan) 0.7%; LGMD2I (Fukutin-related protein) 6.4%; and undetermined 27.1%. Compared to Northern European populations, Italian patients are less likely to be affected with LGMD2I. The order of decreasing clinical severity was: sarcoglycanopathy, calpainopathy, dysferlinopathy, and caveolinopathy. LGMD2I patients showed both infantile noncongenital and mild late-onset presentations. Age at disease onset correlated with variability of genotype and protein levels in LGMD2B. Truncating mutations determined earlier onset than missense substitutions (20+/-5.1 years vs. 36.7+/-11.1 years; P=0.0037). Similarly, dysferlin absence was associated with an earlier onset when compared to partial deficiency (20.2+/-standard deviation [SD] 5.2 years vs. 28.4+/-SD 11.2 years; P=0.014).

[Electromagnetic interference of electronic devices in workers with AICD]

The Implantable Cardioverter Defibrillators and the Pacemakers are devices that produce electric signals and consequently they are touchy to the electromagnetic interferences. This touchiness may cause a temporary or permanent device's malfunction both for short, but of high intensity, and prolonged exposures. Considered the wide diffusion in the job's environments of the technologies based on the electromagnetic waves, the aim of the study is identify the presence of electronic equipment's electromagnetic interferences in AICD bearing workers. The last aim is give to the AICD bearing workers more detailed information about the prevention of inappropriate AICD shocks.

Altered extracellular matrix transcript expression and protein modulation in primary Duchenne muscular dystrophy myotubes

Extent of muscle fibrosis contributes to disease severity in muscular dystrophies. To investigate whether extracellular matrix (ECM) components contribute to the severe fibrosis observed in Duchenne muscular dystrophy (DMD) skeletal muscle, we quantitated several ECM components (transcripts and proteins) in primary DMD and control myotube cultures. We evaluated the fibrogenic transforming growth factor- beta1 (TGF-beta1); the small pleiotropic proteoglycan decorin, involved in collagen fibrillogenesis and TGF-beta1 modulation; metalloproteinases MMP-2 and MMP-9; tissue inhibitors of metalloproteinase (TIMP) 1, 2 and 3; collagens I and VI; and the tissue factor myostatin that inhibits muscle growth. Dystrophic myotube cultures had significantly lower levels of decorin mRNA, as also observed in DMD muscle biopsies, and significantly higher levels of TGF-beta1, myostatin, and collagens I and VI. MMP-2, TIMP-1 and TIMP-2 transcript levels were also significantly increased in DMD, but MMP-9 and TIMP-3 transcripts were unchanged. By zymography, MMP-2 activity was significantly higher in DMD than control. Protein levels were similar in DMD and controls but myostatin protein was significantly increased in DMD. We have found that transcript expression and protein modulation of several ECM components is altered in DMD muscle cells in vitro, indicating that these cells contribute fundamentally to the pathological process, since the inflammation and degeneration characterizing DMD muscle in vivo are presumably absent in culture. Our findings that myostatin-potent inhibitor of satellite cell activation and muscle renewal--is increased, and that decorin-binder and downregulator of TGFbeta1 and myostatin--is decreased, may have implications for DMD therapy to reduce muscle fibrosis.

Canine coronavirus induces apoptosis in cultured cells

Canine coronavirus (CCoV) is widespread in dogs in several countries and causes mild enteric illness evolving to severe enteritis in young pups.

In in vitro cultures canine coronaviruses generally induce extensive cell death, however nature of the events leading to cell death remains largely unknown.

We analysed the induction of cytopathic effect by CCoV in a canine fibrosarcoma cell line (A-72) in order to characterize the apoptotic effect in homologous cell system.

Following CCoV infection A-72 cell line, which is permissive to CCoV, showed reduced growth rate, as detected by MTT assay, a standard colorimetric assay for measuring cellular proliferation, and underwent to apoptotic death. Starting from 24 h after CCoV infection, cells morphology appeared dramatically changed, with cells rounding and detachment from culture surface. Morphologic and biochemical features of apoptosis, such as blebbing of the plasma membrane, translocation of phosphatidilserine to cell surface and annexin V positive staining, nuclear fragmentation, apoptotic bodies formation and DNA laddering, were detected in CCoV-infected cells. Propidium iodide staining of infected culture indicated the appearance of hypodiploid DNA peak corresponding to apoptotic cell population. Commonly to other animal coronavirus infection caspase-3 is likely to contribute to the execution phase of apoptosis induced by CCoV in A-72 cells since we found activation of enzymatic activity as well as procaspase-3 activating cleavage. Apoptotic death of infected cells is detrimental as it causes cell and tissue destruction as well as inflammatory responses. Therefore in the case of CCoV associated gastroenteritis, apoptosis of epithelial mucosa cells may be responsible for pathology induced by CCoV infection.

Evolution of HVR-1 Quasispecies after 1-Year Treatment in HIV/HCV-Coinfected Patients According to the Pattern of Response to Highly Active Antiretroviral Therapy

Hepatitis C virus (HCV) variability is mainly attributed to the ability of the virus to respond to host immune pressure, acting as a driving force for the evolution of quasispecies. This study was aimed at studying the changes in HVR-1 heterogeneity and the evolution of HCV quasispecies in HIV/HCV-coinfected patients according to the pattern of response to highly active antiretroviral therapy (HAART).

Sixteen HIV/HCV-coinfected patients harbouring HCV genotype 1 and who had been on HAART for at least 1 year, 8 showing increasing CD4+T-cell counts (immunological responders) and 8 showing a stable or decreasing CD4+ T-cell counts (immunological non-responders), were selected from a prospective cohort study.

After 1 year of HAART, 11 patients showed HIV viral load <2.6 log10 cp/ml (virological responders), and 5 showed HIV viral load above this value (virological non-responders). Plasma samples, collected before starting therapy and after 1 year of HAART, underwent clonal sequence analysis for HVR-1 region of HCV. Non-synonymous/synonymous substitutions ratio (Ka/Ks), aminoacidic complexity (normalized Shannon entropy) and diversity (p-distance), were considered as parameters of quasispecies heterogeneity. After 1 year of HAART, heterogeneity of HVR-1 quasispecies significantly decreased in virological non-responders, whereas the heterogeneity tended to increase in virological responders. The differences in the evolution were less stringent, when considering immunological response. On the other hand, profound qualitative modifications of HVR-1 quasispecies were observed only in patients with both immunological and virological HAART response.

On the whole, these findings suggest that, in patients undergoing HAART, the extent of HCV variability and the evolution of HVR-1 quasispecies is influenced by the pattern of response to antiretroviral therapy.

LAMA2 gene analysis in congenital muscular dystrophy: new mutations, prenatal diagnosis, and founder effect

OBJECTIVE

To determine if laminin-alpha2 deficiency is due to mutations in the LAMA2 gene or secondary to mutations in other congenital muscular dystrophy genes.

METHODS

We performed molecular analysis of LAMA2, by single-strand conformation polymorphism and sequencing, in 15 patients with undetectable or greatly reduced laminin-alpha2 expression. We also performed 4 prenatal diagnoses and investigated a founder effect.

RESULTS

We found 1 known and 9 previously undescribed LAMA2 mutations spanning all protein domains. These were nonsense or frameshifts causing laminin-alpha2 absence or, in 1 case, a homozygous missense mutation producing partial protein expression and milder phenotype. LAMA2 mutations were undetected in 5 patients, in 2 of whom FKRP mutations explained the phenotype. In 3 prenatal cases, the fetus was heterozygous for the mutation of interest and pregnancy continued; in 1 case, the fetus was affected and aborted. In 2 patients, the Cys967Stop mutation and identical haplotypes flanking the LAMA2 gene indicated a founder effect.

CONCLUSIONS

The clinical phenotype was severe in most patients with LAMA2 mutations and associated with undetectable protein expression. One case with no protein and another with partial expression had milder phenotypes. Typical white matter alterations on magnetic resonance imaging were found in all patients with LAMA2 mutations, supporting the utility of magnetic resonance imaging in differential diagnosis. The founder mutation (Cys967Stop) probably originated in Albania. Genetic characterization of affected families is mainly of use for prenatal diagnosis.

Synthesis, assembly, and processing of the Env ERVWE1/syncytin human endogenous retroviral envelope

Syncytin is a fusogenic protein involved in the formation of the placental syncytiotrophoblast layer. This protein is encoded by the envelope gene of the ERVWE1 proviral locus belonging to the human endogenous retrovirus W (HERV-W) family. The HERV-W infectious ancestor entered the primate lineage 25 to 40 million years ago. Although the syncytin fusion property has been clearly demonstrated, little is known about this cellular protein maturation process with respect to classical infectious retrovirus envelope proteins. Here we show that the cellular syncytin protein is synthesized as a glycosylated gPr73 precursor cleaved into two mature proteins, a gp50 surface subunit (SU) and a gp24 transmembrane subunit (TM). These SU and TM subunits are found associated as homotrimers. The intracytoplasmic tail is critical to the fusogenic phenotype, although its cleavage requirements seem to have diverged from those of classical retroviral maturation.

Response to Haart and Gb Virus Type C Coinfection in a Cohort of Antiretroviral-Naive HIV-Infected Individuals

The prognostic role of GB virus type C (GBV-C) viraemia in HIV-infected subjects treated with highly active antiretroviral therapy (HAART) is still undefined, The aim of this analysis is to assess the relationship between GBV-C infection and response to antiretroviral therapy among HIV-infected subjects initiating HAART when antiretroviral-naive.

A prospective, observational study of 400 HIV-infected patients with measurements of GBV-C RNA, hepatitis C virus (HCV) antibodies and HCV RNA determined from plasma stored prior to HAART initiation, Time to virological (achieving HIV RNA ≤500 copies/ml) and immunological success (a CD4+ count increase of ≥200cells/μl), and the time to virological relapse (confirmed HIV RNA >500 copies/ml) were assessed by Kaplan-Meier methods and Cox proportional hazard regression model.

Of the subjects, 117 (29.3%) were GBV-C positive and, overall, 351 (87.8%) patients achieved virological success, After controlling for a number of confounders including HCV RNA, GBV-C viraemic patients experienced a significantly lower risk of HIV rebound than those who were GBV-C negative [relative hazard (RH)=0.56, 95% CI: 0.34–0.93, P=0.03], Conversely, the probability of achieving initial virological success or CD4+ count response after HAART did not differ between GBV-C-negative and -positive subjects, These results suggest that GBV-C coinfection may play a role in determining the rate of HIV rebound possibly by competing with HIV replication after HIV load has been successfully suppressed by HAART.

Variability in the Interpretation of Transmitted Genotypic HIV-1 Drug Resistance and Prediction of Virological Outcomes of the Initial Haart by Distinct Systems

High level HIV-1 drug resistance in recently infected treatment-naive individuals correlates with sub-optimal virological responses to highly active antiretroviral therapy (HAART). To determine whether genotypic HIV-1 drug resistance in chronic naive patients, as interpreted by various systems, could predict the virological outcomes of HAART, isolates from patients enrolled in a prospective observational cohort (ICoNA) prior to treatment start were genotyped. Genotypic susceptibility scores (GSS) assigned to the initial HAART regimens using the interpretations of pre-therapy resistance mutations by 13 systems were related to virological outcomes. Of 415 patients, 42 (10%) had at least one major resistance mutation. According to the different interpretations, 1.9–20.5% of patients had some level of resistance to at least one drug in the initial regimen. In multivariable analysis, GSS from two systems significantly predicted the time to virological success: Rega 5.5, for each unit increase in GSS adjusted relative hazard (RH) 1.86 [95% confidence intervals (95% CI): 1.15–3.02] and hivresistanceWeb v3, RH 1.87 (95% CI: 1.00–3.48). With three other systems, GSS showed a trend towards a significant prediction of success: Retrogram 1.6, RH 2.33 (95% CI: 0.98–5.53), Menéndez 2002, RH 2.36 (95% CI: 0.97–5.72) and Stanford hivdb, RH 2.06 (95% CI: 0.94–4.49). Genotypic resistance testing coupled with adequate interpretation in chronic naive patients can usefully identify those at risk of sub-optimal virological response to HAART.