Characterizing Acute-Onset Small Fiber Neuropathy

BACKGROUND AND OBJECTIVES

Immune-mediated small fiber neuropathy (SFN) is increasingly recognized. Acute-onset SFN (AOSFN) remains poorly described. Herein, we report a series of AOSFN cases in which immune origins are debatable.

METHODS

We included consecutive patients with probable or definite AOSFN. Diagnosis of SFN was based on the NEURODIAB criteria. Acute onset was considered when the maximum intensity and extension of both symptoms and signs were reached within 28 days. We performed the following investigations: clinical examination, neurophysiologic assessment encompassing a nerve conduction study to rule out large fiber neuropathy, laser-evoked potentials (LEPs), warm detection thresholds (WDTs), electrochemical skin conductance (ESC), epidermal nerve fiber density (ENF), and patient serum reactivity against mouse sciatic nerve teased fibers, mouse dorsal root ganglion (DRG) sections, and cultured DRG. The serum reactivity of healthy subjects (n = 10) and diseased controls (n = 12) was also analyzed. Data on baseline characteristics, biological investigations, and disease course were collected.

RESULTS

Twenty patients presenting AOSFN were identified (60% women; median age: 44.2 years [interquartile range: 35.7-56.2]). SFN was definite in 18 patients (90%) and probable in 2 patients. A precipitating event was present in 16 patients (80%). The median duration of the progression phase was 14 days [5-28]. Pain was present in 17 patients (85%). Twelve patients (60%) reported autonomic involvement. The clinical pattern was predominantly non-length-dependent (85%). Diagnosis was confirmed by abnormal LEPs (60%), ENF (55%), WDT (39%), or ESC (31%). CSF analysis was normal in 5 of 5 patients. Antifibroblast growth factor 3 antibodies were positive in 4 of 18 patients (22%) and anticontactin-associated protein-2 antibodies in one patient. In vitro studies showed IgG immunoreactivity against nerve tissue in 14 patients (70%), but not in healthy subjects or diseased controls. Patient serum antibodies bound to unmyelinated fibers, Schwann cells, juxtaparanodes, paranodes, or DRG. Patients' condition improved after a short course of oral corticosteroids (3/3). Thirteen patients (65%) showed partial or complete recovery. Others displayed relapses or a chronic course.

DISCUSSION

AOSFN primarily presents as an acute, non-length-dependent, symmetric painful neuropathy with a variable disease course. An immune-mediated origin has been suggested based on in vitro immunohistochemical studies.

Anti-SAE autoantibody in dermatomyositis: original comparative study and review of the literature

OBJECTIVE

Among specific autoantibodies in DM, the anti-small ubiquitin-like modifier activating enzyme (SAE) antibody is rare. We aim to describe the clinical characteristics, cancer prevalence, and muscle pathology of anti-SAE-positive DM.

METHODS

Patients with a diagnosis of DM and sera positive for the anti-SAE antibody were recruited from 19 centres in this retrospective observational study. The available muscular biopsies were reviewed. We conducted a comparison with anti-SAE-negative DM and a review of the literature.

RESULTS

Of the patients in the study (n = 49), 84% were women. Skin involvement was typical in 96% of patients, with 10% having calcinosis, 18% ulceration and 12% necrosis; 35% presented with a widespread skin rash. Muscular disease affected 84% of patients, with mild weakness [Medical Research Council (MRC) scale 4 (3, 5)], although 39% of patients had dysphagia. Muscular biopsies showed typical DM lesions. Interstitial lung disease was found in 21% of patients, mainly with organizing pneumonia pattern, and 26% of patients showed dyspnoea. Cancer-associated myositis was diagnosed in 16% of patients and was responsible for the majority of deaths, its prevalence being five times that of the general population. IVIG therapy was administered to 51% of the patients during the course of the disease. Comparison with anti-SAE-negative DM (n = 85) showed less and milder muscle weakness (P = 0.02 and P = 0.006, respectively), lower creatinine kinase levels (P < 0.0001) and less dyspnoea (P = 0.003).

CONCLUSION

Anti-SAE positive DM is a rare subgroup associated with typical skin features but a potentially diffuse rash, a mild myopathy. Interstitial lung disease defines an organizing pneumonia pattern. Cancer associated DM prevalence is five times that of the general population.

TRIAL REGISTRATION

ClinicalTrials.gov, http://clinicaltrials.gov, NCT04637672.

Hemifacial myohyperplasia is due to somatic muscular PIK3CA gain-of-function mutations and responds to pharmacological inhibition

Hemifacial myohyperplasia (HFMH) is a rare cause of facial asymmetry exclusively involving facial muscles. The underlying cause and the mechanism of disease progression are unknown. Here, we identified a somatic gain-of-function mutation of PIK3CA in five pediatric patients with HFMH. To understand the physiopathology of muscle hypertrophy in this context, we created a mouse model carrying specifically a PIK3CA mutation in skeletal muscles. PIK3CA gain-of-function mutation led to striated muscle cell hypertrophy, mitochondria dysfunction, and hypoglycemia with low circulating insulin levels. Alpelisib treatment, an approved PIK3CA inhibitor, was able to prevent and reduce muscle hypertrophy in the mouse model with correction of endocrine anomalies. Based on these findings, we treated the five HFMH patients. All patients demonstrated clinical, esthetical, and radiological improvement with proof of target engagement. In conclusion, we show that HFMH is due to somatic alteration of PIK3CA and is accessible to pharmacological intervention.

Loss of phospholipase PLAAT3 causes a mixed lipodystrophic and neurological syndrome due to impaired PPARγ signaling

Phospholipase A/acyltransferase 3 (PLAAT3) is a phospholipid-modifying enzyme predominantly expressed in neural and white adipose tissue (WAT). It is a potential drug target for metabolic syndrome, as Plaat3 deficiency in mice protects against diet-induced obesity. We identified seven patients from four unrelated consanguineous families, with homozygous loss-of-function variants in PLAAT3, who presented with a lipodystrophy syndrome with loss of fat varying from partial to generalized and associated with metabolic complications, as well as variable neurological features including demyelinating neuropathy and intellectual disability. Multi-omics analysis of mouse Plaat3-/- and patient-derived WAT showed enrichment of arachidonic acid-containing membrane phospholipids and a strong decrease in the signaling of peroxisome proliferator-activated receptor gamma (PPARγ), the master regulator of adipocyte differentiation. Accordingly, CRISPR-Cas9-mediated PLAAT3 inactivation in human adipose stem cells induced insulin resistance, altered adipocyte differentiation with decreased lipid droplet formation and reduced the expression of adipogenic and mature adipocyte markers, including PPARγ. These findings establish PLAAT3 deficiency as a hereditary lipodystrophy syndrome with neurological manifestations, caused by a PPARγ-dependent defect in WAT differentiation and function.

Revisiting idiopathic eosinophilic myositis: towards a clinical-pathological continuum from the muscle to the fascia and skin

OBJECTIVES

Idiopathic inflammatory myopathies are mainly defined by inflammatory infiltrates within the muscle (lymphocytes and macrophages). Eosinophil muscle infiltration has been described in idiopathic eosinophilic myositis (IEM) and rarely in EF. This study aimed to further delineate the nosological frame of idiopathic eosinophil muscle infiltration through the exhaustive analysis of IEM and EF patients.

METHODS

This multicentre retrospective case series included IEM patients diagnosed between 2000 and 2022. IEM inclusion criteria were eosinophilic muscle infiltration with myositis pathological features, after the exclusion of differential diagnoses. An additional group of EF patients diagnosed between 2016 and 2022 was constituted. Inclusion criteria were an EF diagnosis and fascia thickening with inflammatory infiltrate.

RESULTS

A total of 20 IEM cases and 10 EF cases were included. The median (interquartile range) age at diagnosis was 65 (49-70) years; there were 18 males. Data analysis delineated four subgroups: focal EM (FEM, n = 3), diffuse EM (DEM, n = 6), eosinophilic myofasciitis (EMF, n = 11) and EF (n = 10). FEM represented a limited and benign form of myositis. DEM cases presented objective muscle impairment with eosinophilic muscle infiltration. EMF patients presented subjective muscle impairment (myalgia, 55%), fasciitis (on histology and/or imaging), eosinophilic muscle infiltration and frequent hypereosinophilia (55%). EF patients presented myalgia (50%), muscle lesions on histology with fascia-restricted inflammatory infiltrates with (60%) or without (40%) eosinophils.

CONCLUSIONS

The analysis of IEM and EF patient characteristics delineates four subgroups (FEM, DEM, EMF and EF) in terms of clinical, laboratory, imaging, pathological and outcome specificities, and proposes an adapted diagnostic and care management approach.

Thyroid-stimulating hormone receptor signaling restores skeletal muscle stem cell regeneration in rats with muscular dystrophy

Duchenne muscular dystrophy (DMD) is a severe and progressive myopathy leading to motor and cardiorespiratory impairment. We analyzed samples from patients with DMD and a preclinical rat model of severe DMD and determined that compromised repair capacity of muscle stem cells in DMD is associated with early and progressive muscle stem cell senescence. We also found that extraocular muscles (EOMs), which are spared by the disease in patients, contain muscle stem cells with long-lasting regenerative potential. Using single-cell transcriptomics analysis of muscles from a rat model of DMD, we identified the gene encoding thyroid-stimulating hormone receptor (Tshr) as highly expressed in EOM stem cells. Further, TSHR activity was involved in preventing senescence. Forskolin, which activates signaling downstream of TSHR, was found to reduce senescence of skeletal muscle stem cells, increase stem cell regenerative potential, and promote myogenesis, thereby improving muscle function in DMD rats. These findings indicate that stimulation of adenylyl cyclase leads to muscle repair in DMD, potentially providing a therapeutic approach for patients with the disease.

Duchenne muscular dystrophy trajectory in R-DMDdel52 preclinical rat model identifies COMP as biomarker of fibrosis

Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disorder caused by mutations in the Dystrophin gene and for which there is currently no cure. To bridge the gap between preclinical and therapeutic evaluation studies, we have generated a rat model for DMD that carries an exon 52 deletion (R-DMDdel52) causing a complete lack of dystrophin protein. Here we show that R-DMDdel52 animals recapitulated human DMD pathophysiological trajectory more faithfully than the mdx mouse model. We report that R-DMDdel52 rats displayed progressive and severe skeletal muscle loss associated with fibrotic deposition, fat infiltration and fibre type switch. Early fibrosis was also apparent in the cardiac muscle. These histological modifications led to severe muscle, respiratory and cardiac functional impairments leading to premature death around 1 year. Moreover, DMD muscle exhibited systemic inflammation with a mixed M1/M2 phenotype. A comparative single cell RNAseq analysis of the diaphragm muscle was performed, revealing cellular populations alteration and molecular modifications in all muscle cell types. We show that DMD fibroadipogenic progenitors produced elevated levels of cartilage oligomeric matrix protein, a glycoprotein responsible for modulating homeostasis of extracellular matrix, and whose increased concentration correlated with muscle fibrosis both in R-DMDdel52 rats and human patients. Fibrosis is a component of tissue remodelling impacting the whole musculature of DMD patients, at the tissue level but most importantly at the functional level. We therefore propose that this specific biomarker can optimize the prognostic monitoring of functional improvement of patients included in clinical trials.

Efficacy and tolerance of corticosteroids and methotrexate in patients with juvenile dermatomyositis: a retrospective cohort study

OBJECTIVES

To assess the efficacy and tolerance of the conventional first-line treatment by methotrexate (MTX) and corticosteroids (CS) in patients with juvenile dermatomyositis (JDM) regardless of severity.

METHODS

We conducted a monocentric retrospective study of patients with newly-diagnosed JDM treated with MTX and CS from 2012 to 2020. Proportion of clinically inactive disease (CID) within six months of MTX initiation was evaluated using both PRINTO criteria (evaluating muscle inactive disease) and Disease Activity Score (evaluating skin inactive disease). We compared responders and non-responders using univariate analyses.

RESULTS

Forty-five patients with JDM, out of which thirty (67%) severe JDM, were included. After six months of treatment with MTX and CS, complete CID, muscle CID and skin CID were achieved in 14/45 (31%), 19/45 (42%) and 15/45 (33%) patients respectively. The absence of myositis-specific (MSA) or myositis-associated autoantibodies (MAA) at diagnosis was associated with a better overall, cutaneous and muscular therapeutic response, compared with antibody-positive forms (p< 0.01). Requirement for ICU (p= 0.029) and cutaneous ulcerations (p= 0.018) were associated to a less favorable muscle response. MTX was stopped due to intolerance in six patients (13%) before month 6.

CONCLUSION

Conventional first-line treatment with MTX was not efficient in a large subset of JDM patients, especially in patients with MSA-positive forms, and in patients with severe JDM. Larger multicentre cohorts are required to confirm these data and to identify new predictive biomarkers of MTX response, in order to treat patients with JDM as early as possible with appropriate targeted drugs.

Idiopathic eosinophilic myositis: a systematic literature review

Eosinophilic myositis belong to the idiopathic inflammatory myopathies and are defined by an inflammatory infiltrate composed of eosinophils within the muscle. To date, no consensus exists for diagnosis and care of such patients. The aim of this review was to describe clinical and histological presentation, treatment, and outcome of eosinophilic myositis based on a systematic review of all published histologically proven cases of eosinophilic myositis. A total of 453 records were identified in MEDLINE until November 2020. A total of 69 published cases were identified. The analysis of these allowed the distinction of the 3 previously described pathological subtypes: focal eosinophilic myositis (n = 17); diffuse eosinophilic myositis (n = 36); and eosinophilic perimyositis (n = 16). We propose a simple algorithm for diagnosis and treatment strategy for the care of patient with muscular symptoms and blood eosinophilia. This work also highlights eosinophilic myositis pathogenesis and the need for careful investigations in order to rule out differential diagnoses.

From Diagnosis to Prognosis: Revisiting the Meaning of Muscle ISG15 Overexpression in Juvenile Inflammatory Myopathies

OBJECTIVE

Juvenile idiopathic inflammatory/immune myopathies (IIMs) constitute a highly heterogeneous group of disorders with diagnostic difficulties and prognostic uncertainties. Circulating myositis-specific autoantibodies (MSAs) have been recognized as reliable tools for patient substratification. Considering the key role of type I interferon (IFN) up-regulation in juvenile IIM, we undertook the present study to investigate whether IFN-induced 15-kd protein (ISG-15) could be a reliable biomarker for stratification and diagnosis and to better elucidate its role in juvenile IIM pathophysiology.

METHODS

The study included 56 patients: 24 with juvenile dermatomyositis (DM), 12 with juvenile overlap myositis (OM), 10 with Duchenne muscular dystrophy, and 10 with congenital myopathies. Muscle biopsy samples were assessed by immunohistochemistry, immunoblotting, and real-time quantitative polymerase chain reaction. Negative regulators of type I IFN (ISG15 and USP18) and positive regulators of type I IFN (DDX58 and IFIH1) were analyzed.

RESULTS

ISG15 expression discriminated patients with juvenile IIM from those with nonimmune myopathies and, among patients with juvenile IIM, discriminated those with DM from those with OM. Among patients with juvenile DM, up-regulation of the type I IFN positive regulators DDX58 and IFIH1 was similar regardless of MSA status. In contrast, the highest levels of the type I IFN negative regulator ISG15 were observed in patients who were positive for melanoma differentiation-associated gene 5 (MDA-5). Finally, ISG15 levels were inversely correlated with the severity of muscle histologic abnormalities and positively correlated with motor performance as evaluated by the Childhood Myositis Assessment Scale and by manual muscle strength testing.

CONCLUSION

Muscle ISG15 expression is strongly associated with juvenile DM, with patients exhibiting a different ISG-15 muscle signature according to their MSA class. Patients with juvenile DM who are positive for MDA-5 have higher expression of ISG15 in both gene form and protein form compared to the other subgroups. Moreover, our data show that negative regulation of type I IFN correlates with milder muscle involvement.

JAK inhibitors are effective in a subset of patients with juvenile dermatomyositis: a monocentric retrospective study

OBJECTIVE

To evaluate the efficacy and safety of JAK inhibitors (JAKi) in juvenile dermatomyositis (JDM).

METHODS

We conducted a single-center retrospective study of patients with JDM treated by JAKi with a follow-up of at least 6 months. Proportion of clinically inactive disease (CID) within six months of JAKi initiation was evaluated using PRINTO criteria and skin Disease Activity Score. Serum IFN-α concentration was measured by SIMOA assay.

RESULTS

Nine refractory and one new-onset patients with JDM treated with ruxolitinib (n = 7) or baricitinib (n = 3) were included. The main indications for treatment were refractory muscle involvement (n = 8) and ulcerative skin disease (n = 2). CID was achieved in 5/10 patients (2/2 anti-MDA5, 3/4 anti-NXP2, 0/3 anti-TIF1γ positive patients) within six months of JAKi introduction. All responders could withdraw plasmatic exchange, immunoadsorption and other immunosuppressive drugs. The mean daily steroid dose decreased from 1.1 mg/Kg (range 0.35-2 mg/Kg/d) to 0.1 (range, 0-0.3, p= 0.008) in patients achieving CID, and was stopped in two. Serum IFN-α concentrations were elevated in all patients at the time of treatment initiation and normalized in both responder and non-responder. A muscle biopsy repeated in one patient 26 months after the initiation of JAKi, showed a complete restoration of muscle endomysial microvascular bed. Herpes zoster and skin abscesses developed in three and two patients, respectively.

CONCLUSION

JAKis resulted in a CID in a subset of new-onset or refractory patients with JDM and may dramatically reverse severe muscle vasculopathy. Overall tolerance was good except for a high rate of herpes zoster infection.

Clinical impact of dual-tracer FDOPA and FDG PET/CT for the evaluation of patients with parkinsonian syndromes

Parkinsonian syndromes include typical cases of idiopathic Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) associated with cognitive and vegetative disorders, which are more challenging to diagnose. The aim of this study was to assess -the value of dual-tracer imaging 6-fluoro-(18F)-L-DOPA (FDOPA) and fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), performed in routine patients demonstrating extrapyramidal signs and cognitive complains, for the diagnosis and management of parkinsonian syndromes.We retrospectively included 143 consecutive patients who underwent both FDOPA PET/CT (for the evaluation of parkinsonism) and FDG PET/CT (for the evaluation of cognitive complaints) in the same institution. The suspected clinical diagnosis before imaging and the final post-imaging diagnosis were collected by a dedicated questionnaire.FDOPA was pathological in 90.2% of cases, including 74.1% of PD, 3.5% of parkinsonian dementia and 7% of APS. FDG was normal or near normal in 58.7% of patients. A pattern of diffuse cortical hypometabolism was observed in the remaining patients, more frequently in APS than in PD patients (P = .001). Importantly, in 7.7% of cases dual-tracer PET/CT allowed to decide between several diagnostic hypotheses and led to a new diagnosis in 14.0%. Therefore, the management of these patients was modified, with clinical re-evaluation in a specialized unit and a control of neuropsychological tests and imaging.Dual-tracer PET/CT imaging may be a precious help in the diagnosis and management of parkinsonian syndromes.

Muscle ischaemia associated with NXP2 autoantibodies: a severe subtype of juvenile dermatomyositis

Objectives

Myositis-specific autoantibodies (MSAs) are increasingly used to delineate distinct subgroups of JDM. The aim of our study was to explore without a priori hypotheses whether MSAs are associated with distinct clinical-pathological changes and severity in a monocentric JDM cohort.

Methods

Clinical, biological and histological findings from 23 JDM patients were assessed. Twenty-six histopathological parameters were subjected to multivariate analysis.

Results

Autoantibodies included anti-NXP2 (9/23), anti-TIF1γ (4/23), anti-MDA5 (2/23), no MSAs (8/23). Multivariate analysis yielded two histopathological clusters. Cluster 1 (n = 11) showed a more severe and ischaemic pattern than cluster 2 (n = 12) assessed by: total score severity ⩾ 20 (100.0% vs 25.0%); visual analogic score ⩾6 (100.0% vs 25.0%); the vascular domain score >1 (100.0% vs 41.7%); microinfarcts (100% vs 58.3%); ischaemic myofibrillary loss (focal punched-out vacuoles) (90.9 vs 25%); and obvious capillary loss (81.8% vs 16.7). Compared with cluster 2, patients in cluster 1 had strikingly more often anti-NXP2 antibodies (7/11 vs 2/12), more pronounced muscle weakness, more gastrointestinal involvement and required more aggressive treatment. Furthermore, patients with anti-NXP2 antibodies, mostly assigned in the first cluster, also displayed more severe muscular disease, requiring more aggressive treatment and having a lower remission rate during the follow-up period.

Conclusion

Marked muscle ischaemic involvement and the presence of anti-NXP2 autoantibodies are associated with more severe forms of JDM.

Critical analysis of reference studies on the toxicokinetics of aluminum-based adjuvants

We reviewed the three toxicokinetic reference studies commonly used to suggest that aluminum (Al)-based adjuvants are innocuous. A single experimental study was carried out using isotopic 26Al (Flarend et al., Vaccine, 1997). This study used aluminum salts resembling those used in vaccines but ignored adjuvant uptake by cells that was not fully documented at the time. It was conducted over a short period of time (28days) and used only two rabbits per adjuvant. At the endpoint, Al elimination in the urine accounted for 6% for Al hydroxide and 22% for Al phosphate, both results being incompatible with rapid elimination of vaccine-derived Al in urine. Two theoretical studies have evaluated the potential risk of vaccine Al in infants, by reference to an oral "minimal risk level" (MRL) extrapolated from animal studies. Keith et al. (Vaccine, 2002) used a high MRL (2mg/kg/d), an erroneous model of 100% immediate absorption of vaccine Al, and did not consider renal and blood-brain barrier immaturity. Mitkus et al. (Vaccine, 2011) only considered solubilized Al, with erroneous calculations of absorption duration. Systemic Al particle diffusion and neuro-inflammatory potential were omitted. The MRL they used was both inappropriate (oral Al vs. injected adjuvant) and still too high (1mg/kg/d) regarding recent animal studies. Both paucity and serious weaknesses of reference studies strongly suggest that novel experimental studies of Al adjuvants toxicokinetics should be performed on the long-term, including both neonatal and adult exposures, to ensure their safety and restore population confidence in Al-containing vaccines.

Predictive value of brain 18F-FDG PET/CT in macrophagic myofasciitis?: A case report

RATIONALE

Although several functional studies have demonstrated that positron emission tomography/computed tomography with F-fluorodeoxyglucose (F-FDG PET/CT) appears to be efficient to identify a cerebral substrate in patients with known macrophagic myofasciitis (MMF), the predictive value of this imaging technique for MMF remains unclear.

PATIENT CONCERNS

We presented data and images of a 46-year-old woman.

DIAGNOSES

The patient was referred to our center for suspected MMF due to diffuse arthromyalgias and cognitive disorder (involving an impairment of visual selective attention and a weakness in executive functions revealed by neuropsychological assessment) which occurred few years after last vaccine injections.

INTERVENTIONS

After a first negative deltoid muscle biopsy, a brain F-FDG PET/CT was performed and revealed the known spatial pattern of a cerebral glucose hypometabolism involving occipital cortex, medial temporal areas, and cerebellum.

OUTCOMES

Given the clinical suspicion of MMF and brain F-FDG PET/CT findings, a 2nd deltoid muscle biopsy was performed and confirmed the diagnosis of MMF with typical histopathological features.

LESSONS

This case highlights the predictive value of brain F-FDG PET/CT as a noninvasive imaging tool for MMF diagnosis, even when muscle biopsy result comes back negative.

Cerebral 18F-FDG PET in macrophagic myofasciitis: An individual SVM-based approach

INTRODUCTION

Macrophagic myofasciitis (MMF) is an emerging condition with highly specific myopathological alterations. A peculiar spatial pattern of a cerebral glucose hypometabolism involving occipito-temporal cortex and cerebellum have been reported in patients with MMF; however, the full pattern is not systematically present in routine interpretation of scans, and with varying degrees of severity depending on the cognitive profile of patients. Aim was to generate and evaluate a support vector machine (SVM) procedure to classify patients between healthy or MMF 18F-FDG brain profiles.

METHODS

18F-FDG PET brain images of 119 patients with MMF and 64 healthy subjects were retrospectively analyzed. The whole-population was divided into two groups; a training set (100 MMF, 44 healthy subjects) and a testing set (19 MMF, 20 healthy subjects). Dimensionality reduction was performed using a t-map from statistical parametric mapping (SPM) and a SVM with a linear kernel was trained on the training set. To evaluate the performance of the SVM classifier, values of sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy (Acc) were calculated.

RESULTS

The SPM12 analysis on the training set exhibited the already reported hypometabolism pattern involving occipito-temporal and fronto-parietal cortices, limbic system and cerebellum. The SVM procedure, based on the t-test mask generated from the training set, correctly classified MMF patients of the testing set with following Se, Sp, PPV, NPV and Acc: 89%, 85%, 85%, 89%, and 87%.

CONCLUSION

We developed an original and individual approach including a SVM to classify patients between healthy or MMF metabolic brain profiles using 18F-FDG-PET. Machine learning algorithms are promising for computer-aided diagnosis but will need further validation in prospective cohorts.

Non-linear dose-response of aluminium hydroxide adjuvant particles: Selective low dose neurotoxicity

Aluminium (Al) oxyhydroxide (Alhydrogel^®), the main adjuvant licensed for human and animal vaccines, consists of primary nanoparticles that spontaneously agglomerate. Concerns about its safety emerged following recognition of its unexpectedly long-lasting biopersistence within immune cells in some individuals, and reports of chronic fatigue syndrome, cognitive dysfunction, myalgia, dysautonomia and autoimmune/inflammatory features temporally linked to multiple Al-containing vaccine administrations. Mouse experiments have documented its capture and slow transportation by monocyte-lineage cells from the injected muscle to lymphoid organs and eventually the brain. The present study aimed at evaluating mouse brain function and Al concentration 180days after injection of various doses of Alhydrogel^® (200, 400 and 800μg Al/kg of body weight) in the tibialis anterior muscle in adult female CD1 mice. Cognitive and motor performances were assessed by 8 validated tests, microglial activation by Iba-1 immunohistochemistry, and Al level by graphite furnace atomic absorption spectroscopy. An unusual neuro-toxicological pattern limited to a low dose of Alhydrogel^® was observed. Neurobehavioural changes, including decreased activity levels and altered anxiety-like behaviour, were observed compared to controls in animals exposed to 200μg Al/kg but not at 400 and 800μg Al/kg. Consistently, microglial number appeared increased in the ventral forebrain of the 200μg Al/kg group. Cerebral Al levels were selectively increased in animals exposed to the lowest dose, while muscle granulomas had almost completely disappeared at 6 months in these animals. We conclude that Alhydrogel^® injected at low dose in mouse muscle may selectively induce long-term Al cerebral accumulation and neurotoxic effects. To explain this unexpected result, an avenue that could be explored in the future relates to the adjuvant size since the injected suspensions corresponding to the lowest dose, but not to the highest doses, exclusively contained small agglomerates in the bacteria-size range known to favour capture and, presumably, transportation by monocyte-lineage cells. In any event, the view that Alhydrogel^® neurotoxicity obeys "the dose makes the poison" rule of classical chemical toxicity appears overly simplistic.

Aluminum adjuvants of vaccines injected into the muscle: Normal fate, pathology and associated disease

Aluminum oxyhydroxide (Alhydrogel(®)) is a nano-crystalline compound forming aggregates that has been introduced in vaccine for its immunologic adjuvant effect in 1926. It is the most commonly used adjuvant in human and veterinary vaccines but mechanisms by which it stimulates immune responses remain ill-defined. Although generally well tolerated on the short term, it has been suspected to occasionally cause delayed neurologic problems in susceptible individuals. In particular, the long-term persistence of aluminic granuloma also termed macrophagic myofasciitis is associated with chronic arthromyalgias and fatigue and cognitive dysfunction. Safety concerns largely depend on the long biopersistence time inherent to this adjuvant, which may be related to its quick withdrawal from the interstitial fluid by avid cellular uptake; and the capacity of adjuvant particles to migrate and slowly accumulate in lymphoid organs and the brain, a phenomenon documented in animal models and resulting from MCP1/CCL2-dependant translocation of adjuvant-loaded monocyte-lineage cells (Trojan horse phenomenon). These novel insights strongly suggest that serious re-evaluation of long-term aluminum adjuvant phamacokinetics and safety should be carried out.

Human Endogenous Retrovirus and Neuroinflammation in Chronic Inflammatory Demyelinating Polyradiculoneuropathy

BACKGROUND

Human endogenous retroviruses HERV-W encode a pro-inflammatory protein, named MSRV-Env from its original identification in Multiple Sclerosis. Though not detected in various neurological controls, MSRV-Env was found in patients with chronic inflammatory demyelinating polyradiculoneuropathies (CIDPs). This study investigated the expression of MSRV in CIDP and evaluated relevant MSRV-Env pathogenic effects.

METHODS

50 CIDP patients, 19 other neurological controls (ONDs) and 65 healthy blood donors (HBDs) were recruited from two different countries. MSRV-env and -pol transcripts, IL6 and CXCL10 levels were quantified from blood samples. MSRV-Env immunohistology was performed in distal sensory nerves from CIDP and neurological controls biopsies. MSRV-Env pathogenic effects and mode of action were assayed in cultured primary human Schwann cells (HSCs).

FINDINGS

In both cohorts, MSRV-env and -pol transcripts, IL6 positivity prevalence and CXCL10 levels were significantly elevated in CIDP patients when compared to HBDs and ONDs (statistically significant in all comparisons). MSRV-Env protein was detected in Schwann cells in 5/7 CIDP biopsies. HSC exposed to or transfected with MSRV-env presented a strong increase of IL6 and CXCL10 transcripts and protein secretion. These pathogenic effects on HSC were inhibited by GNbAC1, a highly specific and neutralizing humanized monoclonal antibody targeting MSRV-Env.

INTERPRETATION

The present study showed that MSRV-Env may trigger the release of critical immune mediators proposed as instrumental factors involved in the pathophysiology of CIDP. Significant MSRV-Env expression was detected in a significant proportion of patients with CIDP, in which it may play a role according to its presently observed effects on Schwann cells along with previously known effects on immune cells. Experimental results also suggest that a biomarker-driven therapeutic strategy targeting this protein with a neutralizing antibody such as GNbAC1 may offer new perspectives for treating CIDP patients with positive detection of MSRV-Env expression.

FUNDING

Geneuro-Innovation, France.

Dermatomyositis: factors predicting relapse

BACKGROUND

The course of dermatomyositis (DM) can be chronic with relapses, which are associated with major morbidity.

OBJECTIVE

The aim of this study was to identify presentation features that predict DM relapses.

METHODS

We retrospectively reviewed data of patients with DM recorded from 1990 to 2011, including muscle biopsy results. Characteristics of patients with and without relapses were compared. Hazard ratios (HRs) were estimated using a Cox model.

RESULTS

We identified 34 patients, with a mean age of 46 ± 17 years (range, 18-77) and 24 (71%) women. The muscle and skin abnormalities relapsed in 21 (61%) patients. By univariate analysis, two presentation features were significantly associated with a subsequently relapsing course, namely, dysphonia [HR = 3.2 (1.2-8.5)] and greater skin lesion severity defined as a Cutaneous Disease Area Severity Index [CDASI] > 20 [HR = 3.5 (1.2-7.9)].

CONCLUSION

Dysphonia and skin lesion severity at disease onset must be recorded, as they significantly predict a relapsing disease course.

FDG-PET/CT Brain Findings in a Patient With Macrophagic Myofasciitis

Brain Positron Emission Tomography/Computed Tomography with (18)F-fluorodeoxyglucose (FDG PET/CT) was performed in a 44-year-old woman with marked cognitive impairment, diffuse myalgias, sensory, memory and visual disorders, and chronic fatigue, presenting with histopathological features of macrophagic myofasciitis (MMF) at deltoid muscle biopsy. Cerebromedullary Magnetic Resonance Imaging (MRI), electromyography, ophthalmic examination, and cerebrospinal fluid analysis were normal. Visual analysis of FDG PET/CT images showed an atypical pattern of hypometabolism, involving symmetrically the occipital cortex, temporal lobes, and limbic system (including in particular amygdalo-hippocampal complexes), and the cerebellum. Posterior cingulate cortex and parietal areas were preserved. This pattern was confirmed by a voxel-based procedure using Statistical Parametric Mapping (SPM12) that compared a patient's images to normal reference samples from six healthy subjects with adjustment to age obtained using the same PET/CT camera. These results provide a glucose metabolism substrate for cognitive complaints in patients with long-lasting aluminium hydroxide-induced MMF.

Sjögren Syndrome-Associated Small Fiber Neuropathy: Characterization From a Prospective Series of 40 Cases

We conducted the current study to analyze the clinical, immunologic, and neurophysiologic features of primary Sjögren syndrome (pSS)-associated sensory small fiber neuropathies (SFNs). Forty consecutive pSS patients with SFN were included. SFN was defined by the presence of suggestive sensory painful symptoms with normal nerve conduction studies and abnormal neurophysiologic tests for small nerve fibers or a low intraepidermal nerve fiber density at skin biopsy. Included patients were compared to 100 pSS patients without peripheral neuropathy.SFN patients were mainly female (92.5%). Age at pSS diagnosis was 55.3 ± 13.1 years, and at SFN diagnosis, 58.9 ± 11.8 years, with a median time to SFN diagnosis after symptom onset of 3.4 years. Clinical symptoms included burning pains (90%), numbness (87.5%), tingling (82.5%), pins and needles (72.5%), electric discharges (70%), and allodynia (55%). Dysautonomia included vasomotor symptoms (66%) and hyperhidrosis (47%). Abnormal neurophysiologic tests included laser evoked potentials (97.5%), thermal quantitative sensory testing (67.5%), and sympathetic skin reflex (40%). A skin biopsy revealed low intraepidermal nerve fiber density in 76% of the 17 tested patients.Compared to the 100 pSS patients without peripheral neuropathy, the 40 pSS-SFN patients were older at pSS diagnosis (55.3 ± 13.1 vs. 49.5 ± 14.9 yr; p = 0.03), and more often had xerostomia (97.5% vs. 81%; p = 0.01) and arthralgia (82.5% vs. 65.0%; p = 0.04). Immunologically, they were characterized by a lower prevalence of serum B-cell activation markers, that is, antinuclear antibodies (65% vs. 85%; p = 0.01), anti-SSA (42.5% vs. 71%; p = 0.002), and anti-SSB (17.5% vs. 39%; p = 0.017); rheumatoid factor (32.5% vs. 66%; p = 0.0005); and hypergammaglobulinemia (35% vs. 62%; p = 0.005).In conclusion, we report the main features of SFN in patients with pSS, the first such study to our knowledge. Our results show that patients with pSS-associated SFN are characterized by an older age at pSS diagnosis and a distinctive immunologic profile hallmarked by a lower frequency of serum B-cell activation markers.

Distinctive clinical features in arthro-myalgic patients with and without aluminum hydroxyde-induced macrophagic myofasciitis: an exploratory study

Macrophagic myofasciitis (MMF) is a specific histological lesion assessing the persistence of vaccine-derived aluminum oxyhydroxide in muscle tissue, at a site of previous immunization. Long-lasting MMF is usually detected in patients with arthromyalgias, chronic fatigue, and stereotyped cognitive dysfunction. MMF diagnosis requires muscle biopsy, an invasive procedure not suitable for the routine investigation of all patients with musculoskeletal pain. To help decision making in routine practice, we designed a retrospective analysis of 130 consecutive arthro-myalgic patients, previously immunized with aluminum-containing vaccines, in whom deltoid muscle biopsy was performed for diagnostic purposes. According to biopsy results, the patients were ascribed to either the MMF or the non-MMF group. MMF was diagnosed in 32.3% of the patients. MMF and non-MMF groups were similar according to both the injected vaccines and the delay between vaccination and biopsy. MMF patients had less frequent fibromyalgia than non-MMF patients (≥11 fibromyalgic tender points in 16.6 vs 55.5%, p < 0.04), and more often abnormal evoked potentials suggestive of CNS demyelination (38.5 vs 5.7%, p < 0.01). Predictive bioclinical scores based on simple variables such as the number of fibromyalgic tender points, arthralgias, and spinal pain, had sensitivity ranging from 50 to 88.1% and specificity from 36.4 to 76.1%.

IN CONCLUSION

(i) most aluminum-containing vaccine receivers do not have long-lasting MMF in their muscle, but the prevalence of MMF among patients with arthromyalgia following immunization is substantial; (ii) patients with MMF have more CNS dysfunction and less fibromyalgic tender points than non-MMF patients; (iii) predictive scores may help to identify patients at high vs low risk of MMF.

Macrophagic myofasciitis: characterization and pathophysiology

Aluminium oxyhydroxide (alum), a nanocrystalline compound forming agglomerates, has been used in vaccines for its immunological adjuvant effect since 1927. Alum is the most commonly used adjuvant in human and veterinary vaccines, but the mechanisms by which it stimulates immune responses remain incompletely understood. Although generally well tolerated, alum may occasionally cause disabling health problems in presumably susceptible individuals. A small proportion of vaccinated people present with delayed onset of diffuse myalgia, chronic fatigue and cognitive dysfunction, and exhibit very long-term persistence of alum-loaded macrophages at the site of previous intramuscular (i.m.) immunization, forming a granulomatous lesion called macrophagic myofasciitis (MMF). Clinical symptoms associated with MMF are paradigmatic of the recently delineated 'autoimmune/inflammatory syndrome induced by adjuvants' (ASIA). The stereotyped cognitive dysfunction is reminiscent of cognitive deficits described in foundry workers exposed to inhaled Al particles. Alum safety concerns will largely depend on whether the compound remains localized at the site of injection or diffuses and accumulates in distant organs. Animal experiments indicate that biopersistent nanomaterials taken up by monocyte-lineage cells in tissues, such as fluorescent alum surrogates, can first translocate to draining lymph nodes, and thereafter circulate in blood within phagocytes and reach the spleen, and, eventually, slowly accumulate in the brain.

A reappraisal of long-latency abdominal muscle reflexes in patients with propriospinal myoclonus

BACKGROUND

We report 3 patients with typical clinical and electrophysiological characteristics of propriospinal myoclonus propagating from a thoracic spine generator.

METHODS

In these patients, the pattern of recruitment of long-latency electromyographic reflexes in abdominal muscles was studied in response to various stimuli.

RESULTS

Abdominal reflex latency varied from 60 to 140 ms depending on stimulus location. Latency increased from magnetic stimulation of the thoracic spine to electrical stimulation of the supraorbital nerve, electrical stimulation of the median nerve, and magnetic stimulation of the motor cortex.

CONCLUSIONS

Long-latency abdominal reflex jerks are probably controlled by the brain stem to propriospinal system projections in patients with propriospinal myoclonus. The stereotyped pattern of recruitment of these reflexes could be of clinical utility to differentiate organic propriospinal myoclonus from psychogenic or mimicked jerks.

Autocrine and paracrine angiopoietin 1/Tie-2 signaling promotes muscle satellite cell self-renewal

Mechanisms governing muscle satellite cell withdrawal from cell cycle to enter into quiescence remain poorly understood. We studied the role of angiopoietin 1 (Ang1) and its receptor Tie-2 in the regulation of myogenic precursor cell (mpc) fate. In human and mouse, Tie-2 was preferentially expressed by quiescent satellite cells in vivo and reserve cells (RCs) in vitro. Ang1/Tie-2 signaling, through ERK1/2 pathway, decreased mpc proliferation and differentiation, increased the number of cells in G0, increased expression of RC-associated markers (p130, Pax7, Myf-5, M-cadherin), and downregulated expression of differentiation-associated markers. Silencing Tie-2 had opposite effects. Cells located in the satellite cell neighborhood (smooth muscle cells, fibroblasts) upregulated RC-associated markers by secreting Ang1 in vitro. In vivo, Tie-2 blockade and Ang1 overexpression increased the number of cycling and quiescent satellite cells, respectively. We propose that Ang1/Tie-2 signaling regulates mpc self-renewal by controlling the return to quiescence of a subset of satellite cells.

[Dysimmune and inflammatory myopathies]

Dysimmunes and inflammatory myopathies (DIM) are divided in four groups, on the grounds of clinical and histopathological criteria: dermatomyositis, polymyositis, inclusion body myositis and autoimmune necrotizing myopathy. They may present as unique condition (primary DIM), or in association with cancer (paraneoplastic DIM) or connective tissue disease (overlap syndrome). All of them but inclusion body myositis usually respond to immunomodulatory therapy, including steroids, immunosuppressive drugs, and intravenous immunglobulins. However, most often they are chronic diseases with relapses and therapeutic failure.

Systemic sclerosis-associated myopathy

Skeletal muscle involvement is a common feature in systemic sclerosis (SSc) because muscle weakness is found in up to 90% SSc patients when systematically assessed. Muscle clinical, biological, and electromyographic features are similar to those of polymyositis or dermatomyositis, except for a higher proportion of mild symptoms. SSc-associated myopathy is more prevalent in diffuse SSc and is also associated with cardiomyopathy. The pathophysiological process leading to SSc-associated myopathy is likely to be complex, given the heterogeneity of pathological muscle findings, including stigma of microangiopathy, and also inflammatory infiltrate in about half of the cases and interstitial fibrosis. Conflicting results have been reported regarding the correlation between clinicobiological presentation and pathological muscle features, nevertheless there is a general agreement that histologically proven inflammatory myopathies usually regress under high-dose corticosteroid therapy, or even low dose in case of positive anti-PM/Scl antibody. In contrast, noninflammatory myopathies often result in milder clinical expression but do not respond to immunosuppressive treatment.

Myopathy associated with anti-signal recognition peptide antibodies: clinical heterogeneity contrasts with stereotyped histopathology

We report three patients with anti-signal recognition particle antibodies who had different presenting clinical pictures, mimicking acute polymyositis, limb-girdle muscular dystrophy, and acute rhabdomyolysis. Muscle biopsies typically showed necrotizing myopathy with little or no inflammation and deposits of membrane attack complex (C5b-9) in endomysial capillaries. The clinical course was severe in two patients and mild in one. The combination of corticosteroid with either an immunosuppressive agent or intravenous immunoglobulins was required to improve the condition of these patients.

Muscle satellite cells and endothelial cells: close neighbors and privileged partners

Genetically engineered mice (Myf5nLacZ/+, Myf5GFP-P/+) allowing direct muscle satellite cell (SC) visualization indicate that, in addition to being located beneath myofiber basal laminae, SCs are strikingly close to capillaries. After GFP(+) bone marrow transplantation, blood-borne cells occupying SC niches previously depleted by irradiation were similarly detected near vessels, thereby corroborating the anatomical stability of juxtavascular SC niches. Bromodeoxyuridine pulse-chase experiments also localize quiescent and less quiescent SCs near vessels. SCs, and to a lesser extent myonuclei, were nonrandomly associated with capillaries in humans. Significantly, they were correlated with capillarization of myofibers, regardless to their type, in normal muscle. They also varied in paradigmatic physiological and pathological situations associated with variations of capillary density, including amyopathic dermatomyositis, a unique condition in which muscle capillary loss occurs without myofiber damage, and in athletes in whom capillaries increase in number. Endothelial cell (EC) cultures specifically enhanced SC growth, through IGF-1, HGF, bFGF, PDGF-BB, and VEGF, and, accordingly, cycling SCs remained mainly juxtavascular. Conversely, differentiating myogenic cells were both proangiogenic in vitro and spatiotemporally associated with neoangiogenesis in muscular dystrophy. Thus, SCs are largely juxtavascular and reciprocally interact with ECs during differentiation to support angio-myogenesis.

Al(OH)3-adjuvanted vaccine-induced macrophagic myofasciitis in rats is influenced by the genetic background

Macrophagic myofasciitis (MMF) is a specific histopathologic lesion involved in the persistence for years of aluminum hydroxide [Al(OH)(3)] at the site of previous intramuscular (i.m.) injection. In order to study mechanisms involved persistence of MMF lesions, we set up an experimental model of MMF-lesion in Sprague-Dawley and Lewis rat, by i.m. injections of 10 microL of an Al(OH)(3)-adjuvanted vaccine. An evaluation carried out over a 12-month period disclosed significant shrinkage of MMF lesions with time. A radioisotopic study did not show significant aluminium uptake by Al(OH)(3)-loaded macrophages. A morphometric approach showed that Lewis rats with Th1-biased immunity had significantly smaller lesions than Sprague-Dawley rats with balanced Th1/Th2 immunity. Concluding, our results indicate that genetic determinatives of cytotoxic T-cell responses could interfere with the clearance process and condition the persistence of vaccine-induced MMF-lesions.

Complications musculaires de l’infection par le virus de l’immunodéficience humaine (VIH) à l’ère des trithérapies

Introduction of highly active antiretroviral therapy (HAART) has dramatically modified the natural history of HIV disease, but lengthening the survival of HIV-infected individuals has been associated with an increasing prevalence of iatrogenic conditions. Muscular complications of HIV infection are classified as follows: (1) HIV-associated myopathies and related conditions including polymyositis, inclusion-body myositis, nemaline myopathy, diffuse infiltrative lymphocytosis syndrome (DILS), HIV-wasting syndrome, vasculitis, myasthenic syndromes, and chronic fatigue; (2) iatrogenic conditions including mitochondrial myopathies, HIV-associated lipodystrophy syndrome, and immune restoration syndrome; (3) opportunistic infections and tumor infiltrations of skeletal muscle; and (4) rhabdomyolysis. These features are described in the present review.

Skeletal muscle involvement in human immunodeficiency virus (HIV)-infected patients in the era of highly active antiretroviral therapy (HAART)

Skeletal muscle involvement can occur at all stages of human immunodeficiency virus (HIV) infection, and may represent the first manifestation of the disease. Myopathies in HIV-infected patients are classified as follows: (1) HIV-associated myopathies and related conditions, including HIV polymyositis, inclusion-body myositis, nemaline myopathy, diffuse infiltrative lymphocytosis syndrome (DILS), HIV-wasting syndrome, vasculitic processes, myasthenic syndromes, and chronic fatigue; (2) muscle complications of antiretroviral therapy, including zidovudine and toxic mitochondrial myopathies related to other nucleoside-analogue reverse-transcriptase inhibitors (NRTIs), HIV-associated lipodystrophy syndrome, and immune restoration syndrome related to highly active antiretroviral therapy (HAART); (3) opportunistic infections and tumor infiltrations of skeletal muscle; and (4) rhabdomyolysis. Introduction of HAART has dramatically modified the natural history of HIV disease by controlling viral replication, but, in turn, lengthening of the survival of HIV-infected individuals has been associated with an increasing prevalence of iatrogenic conditions.

Vaccination-induced cutaneous pseudolymphoma

BACKGROUND

Although mild early cutaneous transient reactions to vaccinations are common, late-onset chronic lesions have been scarcely reported. We report herein a series of 9 patients presenting with cutaneous and subcutaneous pseudolymphoma.

OBSERVATIONS

Nine patients presenting with late-onset, chronic skin lesions occurring at the site of antihepatitis B (8 cases) and antihepatitis A (one case) vaccination were reported. Histopathologic and immunohistochemic studies, and molecular analysis of clonality of skin biopsy specimens, were performed. Furthermore, the presence of vaccine products was investigated in skin lesions by using histochemical, microanalytic, and electronic microscopy techniques.

RESULTS

Histopathologic studies showed dermal and hypodermal lymphocytic follicular infiltrates with germinal center formation. The center of follicles was mostly composed of B cells without atypia, whereas CD4+ T cells were predominant at the periphery. Molecular analysis of clonality revealed a polyclonal pattern of B-cell and T-cell subsets. Aluminium deposits were evidenced in all cases by using histochemical staining in all cases, and by microanalysis and ultrastructural studies in one case. Associated manifestations were vitiligo (one case) and chronic fatigue with myalgia (two cases).

CONCLUSION

Cutaneous lymphoid hyperplasia is a potential adverse effect of vaccinations including aluminium hydroxide as an adjuvant. Further prospective studies are warranted to evaluate the incidence of this complication in the immunized population.

ADAM12 and alpha9beta1 integrin are instrumental in human myogenic cell differentiation

Knowledge on molecular systems involved in myogenic precursor cell (mpc) fusion into myotubes is fragmentary. Previous studies have implicated the a disintegrin and metalloproteinase (ADAM) family in most mammalian cell fusion processes. ADAM12 is likely involved in fusion of murine mpc and human rhabdomyosarcoma cells, but it requires yet unknown molecular partners to launch myogenic cell fusion. ADAM12 was shown able to mediate cell-to-cell attachment through binding alpha9beta1 integrin. We report that normal human mpc express both ADAM12 and alpha9beta1 integrin during their differentiation. Expression of alpha9 parallels that of ADAM12 and culminates at time of fusion. alpha9 and ADAM12 coimmunoprecipitate and participate to mpc adhesion. Inhibition of ADAM12/alpha9beta1 integrin interplay, by either ADAM12 antisense oligonucleotides or blocking antibody to alpha9beta1, inhibited overall mpc fusion by 47-48%, with combination of both strategies increasing inhibition up to 62%. By contrast with blockade of vascular cell adhesion molecule-1/alpha4beta1, which also reduced fusion, exposure to ADAM12 antisense oligonucleotides or anti-alpha9beta1 antibody did not induce detachment of mpc from extracellular matrix, suggesting specific involvement of ADAM12-alpha9beta1 interaction in the fusion process. Evaluation of the fusion rate with regard to the size of myotubes showed that both ADAM12 antisense oligonucleotides and alpha9beta1 blockade inhibited more importantly formation of large (> or =5 nuclei) myotubes than that of small (2-4 nuclei) myotubes. We conclude that both ADAM12 and alpha9beta1 integrin are expressed during postnatal human myogenic differentiation and that their interaction is mainly operative in nascent myotube growth.

Aluminum inclusion macrophagic myofasciitis: a recently identified condition

The authors conclude that the persistence of aluminum hydroxide at the site of intramuscular injection is a novel finding which has an exact significance that remains to be established fully. It seems mandatory to evaluate possible long-term adverse effects induced by this compound, because this issue has not been addressed (in the past, aluminum hydroxide was believed to be cleared quickly from the body). If safety concerns about the long-term effects of aluminum hydroxide are confirmed, novel and alternative vaccine adjuvants to rescue vaccine-based strategies should be proposed to ensure the enormous benefit for public health that these vaccines provide worldwide.

Toxoplasmic myositis as a presenting manifestation of idiopathic CD4 lymphocytopenia

Toxoplasma gondii encysts in skeletal muscle. Although only rarely found at muscle biopsy, this parasite has previously been regarded as a possible cause of polymyositis. We report a case of biopsy-proven toxoplasmic myositis in a non-HIV-infected patient that led to recognition of idiopathic CD4 lymphocytopenia (ICL), a rare condition typically associated with opportunistic infections. Interestingly, the CD25(+) subset that corresponds to the CD4(+) regulatory T cells controlling autoimmune processes was lacking. Steroid and antiprotozoal therapy led to recovery.

[Intravascular large cell lymphoma revealed by diffuse telangiectasia and cauda equina syndrome]

BACKGROUND

Intravascular lymphoma is a rare disease with usually fatal outcome, characterized by the proliferation within the lumen of small blood vessels of neoplastic large lymphoid cells of B-cell origin. We report a case of intravascular lymphoma revealed by diffuse telangiectasia and cauda equina syndrome.

CASE REPORT

A 64-year-old Vietnamese woman presented with unexpected fever and weight loss. Three months after the onset of the first symptoms, an oedema appeared on the lower limbs and the trunk, followed by the eruption of diffuse superficial telangiectasia. Neurologic examination revealed a cauda equina syndrome. The diagnosis of intravascular B cell lymphoma was established on cutaneous and muscular biopsy specimen. A moderate hemophagocytic syndrome was observed, confirmed by bone marrow biopsy. Corticosteroid therapy was started, followed by combination chemotherapy yielding complete response. Six months later death occurred, without evidence of relapse of intravascular lymphoma.

DISCUSSION

Clinical presentation of intravascular lymphoma is often confusing, mimicking systemic disease, with a predilection for skin and nervous system involvement. Diagnosis is difficult and often an autopsy finding. Prognosis is generally poor, but favourable responses to chemotherapy have been observed after early diagnosis and treatment. The pathogenesis of intravascular lymphoma remains unknown. Dysfunction of cell-endothelial interaction affecting adhesion molecules has been suspected. The implication of Epstein-Barr virus in intravascular lymphoma remains controversial.

Oligoclonal T-cells in blood and target tissues of patients with anti-Hu syndrome

T-cell clones of unknown significance (TCUS), assessed by monoclonal or oligoclonal T-cell patterns in PCR-DGGE, were detected in blood of 7/9 patients with anti-Hu syndrome. Clonal patterns were also detected in 2/2 neoplastic lymph nodes, and in 2/2 inflamed dorsal root ganglia from three patients. Only some T-cell clones found in target tissues were also detected in blood or non-target tissues, and likely corresponded to TCUS. In one patient, an identical T-cell clone was found in both neoplastic lymph node tissue and dorsal root ganglia, but not in blood. Dorsal root-infiltrating lymphocytes were cytotoxic CD8(+) TIA-1(+) T-cells. They were often found in close contact to sensory neurons, most of which expressed MHC-1. Taken together, these data support a direct effector role of cytotoxic CD8(+) T-cells, the same clones being likely operative in sensory neuron damage and immune-mediated tumor growth control.

Impaired redox status and cytochrome c oxidase deficiency in patients with polymyalgia rheumatica

OBJECTIVE

To evaluate redox status and muscular mitochondrial abnormalities in patients with polymyalgia rheumatica (PMR).

METHODS

Prospective evaluation of deltoid muscle biopsy in 15 patients with PMR. Fifteen subjects matched for age and sex, with histologically normal muscle and without clinical evidence of myopathy, were used as controls. Cryostat sections of muscle were processed for conventional dyes, cytochrome c oxidase (COX), usual histochemical reactions, and Sudan black. A total of 300-800 fibres was examined in each case. Blood lactate, pyruvate, and lactate/pyruvate ratio were determined in all patients.

RESULTS

Ragged red fibres were found in eight patients with PMR and accounted for 0-0.5% of fibres. Focal COX deficiency was found in 14 (93%) of 15 patients and in nine (60%) of 15 controls. COX deficient fibres were more common in patients with PMR (range 0-2.5%; mean 0.9%) than in controls (range 0-1.2%; mean 0.3%) (paired t test, p=0.001). Seven (47%) of 15 patients had high blood lactate levels (1.50-2.60 mmol/l) or high blood lactate/pyruvate ratios (22-25).

CONCLUSIONS

PMR is associated with mitochondrial abnormalities not solely related to the aging process.