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.

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.

Systemic light chain amyloidosis myopathy responsive to daratumumab monotherapy.

BACKGROUND AND PURPOSE: Amyloid myopathy is a rare and severe manifestation of systemic light chain (AL) amyloidosis. Early diagnosis and staging are mandatory for optimal therapy, given the rapid progression of muscle weakness. Despite the efficacy of bortezomib-based treatment regimens, there is a lack of therapeutic alternatives in non-responsive patients. METHOD: The case report of a patient with systemic AL amyloidosis myopathy treated with daratumumab is presented. RESULTS: A 70-year-old man displayed severe proximal muscle weakness which had developed over a 10-month period. Blood tests revealed an immunoglobulin A lambda monoclonal gammopathy, whilst muscle biopsy showed amyloid deposits within the arteriolar walls, confirming the diagnosis of amyloid myopathy associated with AL amyloidosis. Initial treatment with a bortezomib-based regimen showed no clinical or hematological improvement. After switching to daratumumab monotherapy, our patient achieved a favorable evolution with respect to functional muscle scoring and a complete hematological response. CONCLUSION: To our knowledge, this is the first case report of an amyloid myopathy showing a remarkable clinical improvement in response to daratumumab monotherapy. It thereby highlights the potential of daratumumab as a monotherapeutical approach to the treatment of amyloid myopathy complicating AL amyloidosis.

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 MTX and CS in patients with 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. The proportion of clinically inactive disease (CID) within 6 months of MTX initiation was evaluated using both Paediatric Rheumatology International Trials Organisation (PRINTO) criteria (evaluating muscle inactive disease) and DAS (evaluating skin inactive disease). We compared responders and non-responders using univariate analyses. RESULTS: Forty-five patients with JDM, out of which 30 (67%) severe JDM, were included. After 6 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 with a less favourable muscle response. MTX was stopped due to intolerance in six patients (13%) before month 6. CONCLUSIONS: 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.

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

OBJECTIVE: To evaluate the efficacy and safety of Janus kinase inhibitors (JAKis) in JDM. METHODS: We conducted a single-centre 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 6 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 (two/two anti-MDA5, three/four anti-NXP2, zero/three anti-TIF1γ-positive patients) within 6 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.

European Network on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (EUROMENE): Expert Consensus on the Diagnosis, Service Provision, and Care of People with ME/CFS in Europe.

Designed by a group of ME/CFS researchers and health professionals, the European Network on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (EUROMENE) has received funding from the European Cooperation in Science and Technology (COST)-COST action 15111-from 2016 to 2020. The main goal of the Cost Action was to assess the existing knowledge and experience on health care delivery for people with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in European countries, and to enhance coordinated research and health care provision in this field. We report our findings and make recommendations for clinical diagnosis, health services and care for people with ME/CFS in Europe, as prepared by the group of clinicians and researchers from 22 countries and 55 European health professionals and researchers, who have been informed by people with ME/CFS.

Anti-MDA5 juvenile idiopathic inflammatory myopathy: a specific subgroup defined by differentially enhanced interferon-α signalling.

OBJECTIVES: JDM and juvenile overlap myositis represent heterogeneous subtypes of juvenile idiopathic inflammatory myopathy (JIIM). Chronic evolution can occur in up to 60% of cases, and morbidity/mortality is substantial. We aimed to describe the clinical, biological, histological and type I IFN status in JIIM associated with anti-melanoma differentiation-associated protein 5 (anti-MDA5) autoantibodies at presentation (group 1) in comparison with other JIIM (group 2). METHODS: This was a retrospective and prospective study of patients with JIIM ascertained from three French paediatric rheumatology reference centres between 2013 and 2019. Muscle biopsies were reviewed. Type I interferon pathway activity was assessed by dosage of IFNα serum protein and the expression of IFN-stimulated genes. RESULTS: Sixty-four patients were included, 13 in group 1 (54% JDM and 46% juvenile overlap myositis) and 51 in group 2 (76% JDM and 24% juvenile overlap myositis). Group 1 patients demonstrated more arthritis, skin ulcerations, lupus features and interstitial lung disease, and a milder muscular involvement. Serum IFNα levels were higher in group 1 than 2, and decreased after treatment or improvement in both groups. Outcome was similar in both groups. Unconventional treatment (more than two lines) was required in order to achieve remission, especially when skin ulceration was reported. CONCLUSION: This study indicates a higher frequency of arthritis, skin ulcerations and interstitial lung disease, but milder muscular involvement, in JIIM with positive anti-MDA5 autoantibodies compared with other JIIM. Our data support an important role of systemic IFNα in disease pathology, particularly in the anti-MDA5 auto-antibody-positive subgroup. In severe and refractory forms of JIIM, IFNα may represent a therapeutic target.

Novel splicing dysferlin mutation causing myopathy with intra-familial heterogeneity.

Dysferlinopathies belong to the heterogeneous group of autosomal recessive muscular disorders, caused by mutations in the dysferlin gene and characterized by a high degree of clinical variability even though within the same family. This study aims to describe three cases, belonging to a consanguineous Tunisian family, sharing a new splicing mutation in the dysferlin gene and presenting intra-familial variability of dysferlinopathies: Proximal-distal weakness and distal myopathy with anterior tibial onset. We performed the next generation sequencing for mutation screening and reverse transcriptase-PCR for gene expression analysis. Routine muscle histology was used for muscle biopsy processing. The clinical presentation demonstrated heterogeneous phenotypes between the three cases: Two presented intermediate phenotypes of dysferlinopathy with proximal-distal weakness and the third had a distal myopathy with anterior tibial onset. Genetic analysis yielded a homozygous splicing mutation (c.4597-2A>G) in the dysferlin gene, giving rise to the suppression of 28 bp of the exon 43. The splicing mutation found in our family (c.4597-2A>G) is responsible for the suppression of 28 bp of the exon 43 and a wide clinical intra-familial variability.

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.

Th2-M2 immunity in lesions of muscular sarcoidosis and macrophagic myofasciitis.

OBJECTIVE: To analyse the paradox of a lack of giant cell formation and fibrosis in chronic lesions of macrophagic myofasciitis (MMF) in comparison with muscular sarcoidosis (MuS). METHODS: Inflammatory lesions and contiguous muscle regions from biopsy samples of 10 patients with MuS and 10 patients with MMF were cut out by laser microdissection. Mediators of the T helper cell (Th)1 inducing classical macrophage activation (e.g. STAT1, IFNγ and CXCR3), and Th2 inducing alternative activation of macrophages (e.g. CD206/MRC1, STAT6, SOCS1), molecules involved in development of fibrosis (e.g. TGFß) and giant cells (e.g. TYROBP), were assessed by immunohistochemistry and real-time polymerase chain reaction (PCR). RESULTS: STAT6-induced Th2 immunity was associated with up-regulated gene expression of MRC1, SOCS1 and TGFB in inflammatory foci, in comparison with adjacent tissue. TYROBP and TREM2, genes regulating giant cell formation, were more strongly expressed in lesions of MuS patients than in those of MMF. TGFß co-localized with CD206(+) macrophages in MuS but not in MMF. Conversely, Th1 immunity was illustrated by STAT1 staining both in macrophages and myofibres in MuS, but not in MMF. Also, STAT1-induced IFNG and CXCR3 expression in lesions and the surrounding tissue was elevated compared with normal controls, but without statistically significant differences. CONCLUSION: Giant cell and typical granuloma formations, including fibrogenesis, is dependent on two main mechanisms, both involving specific macrophage activation: a strong Th2-M2 polarization and a significant expression of TYROBP and TGFß in macrophages. The low-grade alternative activation of macrophages in MMF lesions and poor TYROBP and TGFßco-expression are obviously insufficient to produce giant cells.

Dual effects of exercise in dysferlinopathy.

Dysferlinopathy refers to a group of autosomal recessive muscular dystrophies due to mutations in the dysferlin gene causing deficiency of a membrane-bound protein crucially involved in plasma membrane repair. The condition is characterized by marked clinical heterogeneity, the different phenotypes/modes of presentation being unrelated to the genotype. For unknown reasons, patients are often remarkably active before the onset of symptoms. Dysferlin deficiency-related persistence of mechanically induced sarcolemma disruptions causes myofiber damage and necrosis. We postulate that limited myodamage may initially remain hidden with well-preserved resistance to physical strains. By subjecting dysferlin-deficient B6.A/J-Dysf(prmd) mice to long-term swimming exercise, we observed that concentric/isometric strain improved muscle strength and alleviated muscular dystrophy by limiting the accumulation of membrane lesions. By contrast, eccentric strain induced by long-term running in a wheel worsened the dystrophic process. Myofiber damage induced by eccentric strain increased with age, reflecting the accumulation of non-necrotic membrane lesions up to a critical threshold. This phenomenon was modulated by daily spontaneous activity. Transposed to humans, our results may suggest that the past activity profile shapes the clinical phenotype of the myopathy and that patients with dysferlinopathy should likely benefit from concentric exercise-based physiotherapy.

Overexpression of MHC class I in muscle of lymphocyte-deficient mice causes a severe myopathy with induction of the unfolded protein response.

Muscle fibers do not normally express major histocompatibility complex class I (MHC-I) molecules, and their reexpression is a hallmark of inflammatory myopathies. It has been shown in mice that overexpression of MHC-I induces a poorly inflammatory myositis accompanied by the unfolded protein response (UPR), but it is unclear whether it is attributable to T-cell-mediated MHC-I-dependent immune responses or to MHC-I forced expression per se. Indeed, besides presenting antigenic peptides to CD8(+) T cells, MHC-I may also possibly exert nonimmunologic, yet poorly understood pathogenic effects. Thus, we investigated the pathogenicity of MHC-I expression in muscle independently of its immune functions. HT transgenic mice that conditionally overexpress H-2K(b) in muscle were bred to an immunodeficient Rag2(-/-) background. The muscle proteome was analyzed by label-free high-resolution protein quantitation and Western blot. Despite the absence of adaptive immunity, HT Rag2(-/-) mice developed a very severe myopathy associated with the cytoplasmic accumulation of H-2K(b) molecules. The UPR was manifest by up-regulation of characteristic proteins. In humans, we found that HLA class I molecules not only were expressed at the sarcolemma but also could accumulate intracellularly in some patients with inclusion body myositis. Accordingly, the UPR was triggered as a function of the degree of HLA accumulation in myofibers. Hence, reexpression of MHC-I in normally negative myofibers exerts pathogenic effects independently of its immune function.

[Biopersistence and systemic distribution of intramuscularly injected particles: what impact on long-term tolerability of alum adjuvants?]. / Bio-persistance et distribution systémique des particules injectées par voie intra-musculaire: quelle incidence sur la tolérance à long terme des adjuvants aluminiques?

Aluminium oxyhydroxide (alum), a nanocrystalline compound that forms agglomerates, has been widely used as a vaccine adjuvant since 1927, but the mechanisms by which it stimulates immune responses remain poorly understood. Although generally well tolerated, alum may occasionally cause chronic health problems in presumably susceptible individuals. Some individuals may rarely develop delayed-onset diffuse myalgia, chronic exhaustion and cognitive dysfunction, associated with long-term persistence (up to 12 years) of alum-loaded macrophages at site of i.m. immunization, defining so-called macrophagic myofasciitis (MMF). Symptoms are consistent with the chronic fatigue/myalgic encephalomyelitis (CFS/ME) syndrome, and have been used as a paradigm of the "autoimmune/inflammatory syndrome induced by adjuvants" (ASIA). Cognitive dysfunction is reminiscent of that described in workers exposed to inhaled Al particles. Individual susceptibility may influence both alum biopersistence and difusion away from injection sites. Biopersistent particles such as fluorescent alum-coated nanohybrids, when injected into mouse muscle, are captured by monocyte-lineage cells and then carried to distant organs, draining lymph nodes and blood, probably via the thoracic duct, with delayed and accumulative translocation to the brain (microglial cells). Brain penetration occurs at extremely low levels in normal conditions, possibly explaining the good tolerance of alum despite its high neurotoxic potential. However, systemic diffusion is considerably enhanced by the potentiating effect of MCP-1, the main monocyte chemoattractant factor, the production of which is subject to marked variations linked to age and to genetic and environmental factors. Selective MCP-1 elevation is the only known circulating biomarker of MMF.

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.

An up-to-date myopathologic characterisation of facioscapulohumeral muscular dystrophy type 1 muscle biopsies shows sarcolemmal complement membrane attack complex deposits and increased skeletal muscle regeneration.

The aim of this study was to identify key routinely used myopathologic biomarkers of FSHD1. Needle muscle biopsies were taken in 34 affected muscles (m. quadriceps femoris (QF), n = 20, m. tibialis anterior (TA), n = 13, m. biceps brachii, n = 1) from 22 patients (age, 53.5 (10) years; M = 12, F = 10). Eleven patients had more than one biopsy (2xQF, n = 1; QF+TA, n = 9; 2xQF+TA, n = 1). Histochemistry, immunoperoxidase, and immunofluorescence stainings were performed and compared to age and muscle type matched muscle specimens of 11 healthy controls. Myopathologic features observed in our FSHD1 cohort were internalized nuclei, type 1 fibre hypertrophy and NADH central clearances/cores. We observed a prominent inflammatory response with MAC deposits, MHC I expression, and muscle regeneration that correlated with the inflammatory score. Our up-to-date characterization of FSHD1 points towards MHC I, MAC, and embryonic Myosin Heavy Chain/muscle regeneration as useful myopathologic readouts of FSHD1.

Slow CCL2-dependent translocation of biopersistent particles from muscle to brain.

BACKGROUND: Long-term biodistribution of nanomaterials used in medicine is largely unknown. This is the case for alum, the most widely used vaccine adjuvant, which is a nanocrystalline compound spontaneously forming micron/submicron-sized agglomerates. Although generally well tolerated, alum is occasionally detected within monocyte-lineage cells long after immunization in presumably susceptible individuals with systemic/neurologic manifestations or autoimmune (inflammatory) syndrome induced by adjuvants (ASIA). METHODS: On the grounds of preliminary investigations in 252 patients with alum-associated ASIA showing both a selective increase of circulating CCL2, the major monocyte chemoattractant, and a variation in the CCL2 gene, we designed mouse experiments to assess biodistribution of vaccine-derived aluminum and of alum-particle fluorescent surrogates injected in muscle. Aluminum was detected in tissues by Morin stain and particle induced X-ray emission) (PIXE) Both 500 nm fluorescent latex beads and vaccine alum agglomerates-sized nanohybrids (Al-Rho) were used. RESULTS: Intramuscular injection of alum-containing vaccine was associated with the appearance of aluminum deposits in distant organs, such as spleen and brain where they were still detected one year after injection. Both fluorescent materials injected into muscle translocated to draining lymph nodes (DLNs) and thereafter were detected associated with phagocytes in blood and spleen. Particles linearly accumulated in the brain up to the six-month endpoint; they were first found in perivascular CD11b+ cells and then in microglia and other neural cells. DLN ablation dramatically reduced the biodistribution. Cerebral translocation was not observed after direct intravenous injection, but significantly increased in mice with chronically altered blood-brain-barrier. Loss/gain-of-function experiments consistently implicated CCL2 in systemic diffusion of Al-Rho particles captured by monocyte-lineage cells and in their subsequent neurodelivery. Stereotactic particle injection pointed out brain retention as a factor of progressive particle accumulation. CONCLUSION: Nanomaterials can be transported by monocyte-lineage cells to DLNs, blood and spleen, and, similarly to HIV, may use CCL2-dependent mechanisms to penetrate the brain. This occurs at a very low rate in normal conditions explaining good overall tolerance of alum despite its strong neurotoxic potential. However, continuously escalating doses of this poorly biodegradable adjuvant in the population may become insidiously unsafe, especially in the case of overimmunization or immature/altered blood brain barrier or high constitutive CCL-2 production.

Whole microvascular unit deletions in dermatomyositis.

OBJECTIVES: The pathophysiology of dermatomyositis (DM) remains unclear, combining immunopathological mechanisms with ischaemic changes regarded as a consequence of membranolytic attack complex (MAC)-induced capillary destruction. The study is a reappraisal of the microvascular involvement in light of the microvascular organisation in normal human muscle. METHODS: Muscle microvasculature organisation was analysed using 3D reconstructions of serial sections immunostained for CD31, and histoenzymatic detection of endogenous alkaline phosphatase activity of microvessels. An unbiased point pattern analysis-based method was used to evaluate focal capillary loss. Double immunostainings identified cell types showing MAC deposits. RESULTS: The normal arterial tree includes perimysial arcade arteries, transverse arteries penetrating perpendicularly into the endomysium and terminal arterioles feeding a microvascular unit (MVU) of six to eight capillaries contacting an average of five myofibres. Amyopathic DM cases (n=3) and non-necrotic fascicles of early DM cases (n=27), showed patchy capillary loss in the form of 6-by-6 capillary drop-out, corresponding to depletion of one or multiple MVUs. MAC deposits were also clustered (5-8 immunostained structures, including endothelial cells, but also pericytes, mesenchymal cells and myosatellite cells). CONCLUSIONS: Capillary loss may not be the primary cause of muscle ischaemia in DM. The primary event rather stands upstream, probably at the level of perimysial arcade arteries around which inflammatory infiltrates predominate and which lumen may show narrowing in chronic DM. Ischaemia-reperfusion injury, which is favoured by autoimmune backgrounds in experimental models and which activates the complement cascade in capillaries, could represent an hitherto unsuspected (and potentially preventable) mechanism of muscle damage in DM.

Periurethral skeletal myofibre implantation in patients with urinary incontinence and intrinsic sphincter deficiency: a phase I clinical trial.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Cell therapy using muscle precursor cell (MPC) injections has shown promise for urinary incontinence due to intrinsic sphincter deficiency (ISD), but the cell-preparation process is complex and costly. Implantation of freshly isolated myofibres carrying MPCs, mainly satellite cells, was very efficient in repairing muscle damage in recent animal experiments. In a phase I clinical trial, we investigated whether periurethral myofibre implantation generated local myogenesis and improved continence in 10 patients (five men and five women) with ISD. We found that myofibre implantation increased intraurethral pressure and periurethral electromyographic activity in patients with ISD. There were no serious side-effects. OBJECTIVES: To assess the safety of periurethral myofibre implantation in patients with urinary incontinence due to intrinsic sphincter deficiency (ISD) To assess the resulting myogenic process and effects on urinary continence. PATIENTS AND METHODS: An open-label non-randomised phase I clinical trial was conducted in five men and five women with ISD (mean age, 62.5 years). A free muscle strip from the patient's gracilis muscle was implanted around the urethra as a means to deliver locally myofibres and muscle precursor cells (MPCs). Patients were assessed for collection formation and incomplete bladder emptying. The maximum urethral closure pressure (MUCP) and concomitant periurethral electromyographic (EMG) activity were recorded before surgery and 1 and 3 months after surgery. Continence was assessed using the 24-h pad test and self-completed questionnaires, for 12 months. RESULTS: There were no serious side-effects. Continence improved significantly during the 12-month follow-up in four of the five women, including two who recovered normal continence. In the women, MUCP increased two-fold and de novo EMG periurethral activity was recorded. In the men, MUCP and EMG recordings showed similar improvements but the effect on continence was moderate. The few patients enrolled could affect these results. CONCLUSIONS: This is the first report of a one-step procedure for transferring autologous MPCs via myofibre implantation in patients with ISD. EMG and urodynamic assessments showed improvement of periurethral muscle activity. Further work is needed to confirm and improve the therapeutic efficiency of this procedure.

Myoinjury transiently activates muscle antigen-specific CD8+ T cells in lymph nodes in a mouse model.

OBJECTIVE: To investigate the influence of myoinjury on antigen presentation to T cells in draining lymph nodes (LNs). METHODS: Muscle crush was performed in mice injected with exogenous ovalbumin (OVA) and in transgenic SM-OVA mice expressing OVA as a muscle-specific self antigen. Antigen exposure and the resulting stimulation of T cell proliferation in draining LNs was assessed by transferring carboxyfluorescein succinimidyl ester (CFSE)-labeled OVA-specific CD8+ and CD4+ T cells from OT-I and OT-II mice and by measuring the dilution of CFSE, which directly reflects their proliferation. The role of monocyte-derived dendritic cells (DCs) in T cell priming was assessed using pharmacologic blockade of DC migration. Immunofluorescence was used to detect CD8+ T cells, inflammatory monocyte-derived DCs, and type I major histocompatibility complex (MHC)-expressing myofibers in crushed muscle, and to assess expression of perforin, interferon-γ (IFNγ), interleukin-2 (IL-2), IL-10, and transforming growth factor ß1 (TGFß1). RESULTS: OVA injection into intact muscle induced strong proliferation of CD4+ and CD8+ T cells, indicating efficient exposure of soluble antigens in draining LNs. OVA-specific CD8+ T cell proliferation in draining LNs of SM-OVA mice required myoinjury and was unaffected by pharmacologic inhibition of monocyte-derived DC migration. On day 7 postinjury, activated CD8+ T cells expressing perforin, IFNγ and IL-2 were transiently detected in crushed muscle, and these cells were in close contact with class I MHC-positive regenerating myofibers. Beginning on day 7, the immunosuppressive cytokines IL-10 and TGFß1 were conspicuously expressed by CD11b+ cells, and CD8+ T cells rapidly disappeared from the healing muscle. CONCLUSION: Myofiber damage induces an episode of muscle antigen-specific CD8+ T cell proliferation in draining LNs. Activated CD8+ T cells transiently infiltrate the injured muscle, with prompt control by immunosuppressive cues. Inadequate control might favor sustained autoimmune myositis.

Dysferlinopathy in Tunisia: clinical spectrum, genetic background and prognostic profile.

Dysferlinopathy is a rare group of hereditary muscular dystrophy with an autosomal recessive mode of inheritance caused by a mutation in the DYSF gene. It encodes for the dysferlin protein, which has a crucial role in multiple cellular processes, including muscle fiber membrane repair. This deficit has heterogeneous clinical presentations. In this study, we collected 20 Tunisian patients with a sex ratio of 1 and a median age of 50.5 years old (Interquartile range (IQR) = [36,5-54,75]). They were followed for periods ranging from 5 to 48 years. The median age at onset was 17 years old (IQR = [16,8-28,4]). Five major phenotypes were identified: Limb-girdle muscular dystrophy (LGMDR2) (35%), a proximodistal phenotype (35%), Miyoshi myopathy (10%),  Distal myopathy with anterior tibial onset (DMAT) (10%), and asymptomatic HyperCKemia (10%). At the last evaluation, more than half of patients (55%) were on wheelchair. Loss of ambulation occurred generally during the fourth decade. After 20 years of disease progression, two patients with a proximodistal phenotype (10%) developed dilated cardiomyopathy and mitral valve regurgitation. Restrictive respiratory syndrome was observed in three patients (DMAT: 1 patient, proximodistal phenotype: 1 patient, LGMDR2: 1 patient). Genetic study disclosed five mutations. We observed clinical heterogeneity between families and even within the same family. Disease progression was mainly slow to intermediate regardless of the phenotype.