Autoimmune Myositis Research Articles

Exacerbation of Murine Experimental Autoimmune Myositis by Toll-Like Receptor 7/8.

Toll-like receptor 7 (TLR-7), TLR-8, and interferon (IFN)-induced genes are expressed in patients with idiopathic inflammatory myositis. This study was undertaken to investigate whether their activation influences the natural history of the disease. Experimental autoimmune myositis was induced in mice by injection of the amino-terminal portion of the murine histidyl-transfer RNA synthetase (HisRS). Disease was compared in the presence or the absence of the TLR-7/8 agonist R-848 in wild-type mice and in mice that fail to express the IFNα/β receptor (IFNα/βR-null mice). Experimental autoimmune myositis induced by a single intramuscular immunization with HisRS spontaneously abated after 7-8 weeks. In contrast, levels of anti-HisRS autoantibodies, endomysial/perimysial leukocyte infiltration, and myofiber regeneration persisted at the end of the follow-up period (22 weeks after immunization) in mice immunized with HisRS in the presence of R-848. Myofiber major histocompatibility complex (MHC) class I molecules were detectable only in mice immunized with both HisRS and R-848. MHC up-regulation occurred early and in muscles that were not directly injected with HisRS. Muscle MHC expression paralleled with leukocyte infiltration. MHC class I molecules were selectively up-regulated in myotubes challenged with R-848 in vitro. Type I IFN was necessary for the prolonged autoantibody response and for the spreading of the autoimmune response, as demonstrated using IFNα/βR-null mice. Muscle infiltration was maintained in the injected muscle up to the end of the follow-up period. TLR-7/8 activation is necessary to induce and maintain a systemic autoimmune response targeting the skeletal muscle. This experimental autoimmune myositis model reproduces many characteristics of human idiopathic inflammatory myopathies and may represent a tool for preclinical studies.

CD19+CD24hiCD38hi B Cells Are Expanded in Juvenile Dermatomyositis and Exhibit a Pro-Inflammatory Phenotype After Activation Through Toll-Like Receptor 7 and Interferon-α.

Juvenile dermatomyositis (JDM) is a rare form of childhood autoimmune myositis that presents with proximal muscle weakness and skin rash. B cells are strongly implicated in the pathogenesis of the disease, but the underlying mechanisms are unknown. Therefore, the main objective of our study was to investigate mechanisms driving B cell lymphocytosis and define pathological features of B cells in JDM patients. Patients were recruited through the UK JDM Cohort and Biomarker study. Peripheral blood B cell subpopulations were immunophenotyped by flow cytometry. The results identified that immature transitional B cells were significantly expanded in active JDM, actively dividing, and correlated positively with disease activity. Protein and RNAseq analysis revealed high interferon alpha (IFNα) and TLR7-pathway signatures pre-treatment. Stimulation of B cells through TLR7/8 promoted both IL-10 and IL-6 production in controls but failed to induce IL-10 in JDM patient cells. Interrogation of the CD40–CD40L pathway (known to induce B cell IL-10 and IL-6) revealed similar expression of IL-10 and IL-6 in B cells cultured with CD40L from both JDM patients and controls. In conclusion, JDM patients with active disease have a significantly expanded immature transitional B cell population which correlated with the type I IFN signature. Activation through TLR7 and IFNα may drive the expansion of immature transitional B cells in JDM and skew the cells toward a pro-inflammatory phenotype.

Identification of a T cell immunomodulatory domain in histidyl-tRNA synthetase

Abstract Histidyl-tRNA synthetase (HARS) is the autoantigen target of Jo-1 antibodies, which occur in the major form of anti-synthetase syndrome. These patients are characterized by an autoimmune myositis and interstitial lung disease. Circulating extracellular HARS is detected in healthy individuals, but is reduced or undetectable in Jo-1-positive individuals. Administration of ATYR1940, a recombinant form of HARS, ameliorates lung fibrosis and reduces T cell cytokine production in the bleomycin-induced lung injury model. Similar effects were observed with the N-terminal domain of HARS (the iMod domain) conjugated to IgG Fc, suggesting that this domain confers the immunomodulatory activity of HARS. To confirm primary immune effects of ATYR1940 and ATYR1923 (iMod.Fc), human T cells were isolated from PBMC from healthy individuals and stimulated with anti-CD3/anti-CD28. Proteins containing the HARS iMod domain reduced in vitro activation of human CD4+ and CD8+ T cells, as evidenced by reduced secretion of IL-2, IFNγ, TNFα, IL-17, IL-13, and granzyme B, as well as decreased upregulation of activation markers such as CD69 and CD40L. ATYR1940 and ATYR1923 also inhibited cytokine release after ex vivo stimulation of human memory T cells in a NSG mouse xenogeneic GVHD model. T cell inhibition by ATYR1940 was dependent on its iMod domain, as demonstrated using an iMod-specific blocking monoclonal antibody. The ATYR1940-induced T cell gene signature reflected a general inhibitory effect on activation as well as on cell cycle protein expression. These results suggest that circulating levels of HARS may act to control the threshold stimulatory signal required to activate T cells. We propose circulating HARS as a soluble immune set-point modulator.

The association of solid-phase assays to immunofluorescence increases the diagnostic accuracy for ANA screening in patients with autoimmune rheumatic diseases

Abstract Aim This study aimed to investigate whether it is useful both for diagnostic purposes and for cost savings to associate a solid-phase monotest called CTD screen to the immunofluorescence (IIF) test, to detect anti-nuclear and anti-cytoplasmic antibodies (ANA). Methods Fifteen Italian laboratories participated in the study enrolling at least 250-each consecutive unselected samples from patients routinely referred for ANA testing. They all used the conventional IIF method on HEp-2 cells associated to a solid phase CTD screen method. Seven centers used the EliA FEIA CTD screen method on the Phadia 250 instrument (ThermoFisher), five centers used the QUANTAFlash CTD Screen method (Inova Diagnostics) on the BioFlash CLIA instrument, while three centers used both methods, albeit in two different series of patients. Results A total of 5043 samples were tested. We focused attention to the 1674 discrepant results: 106 (2%) were ANA-IIF negative/CTD screen positive and 1568 (31%) were ANA-IIF positive/CTD screen negative. Specific antibodies were detected in 87/106 (82%) of the ANA-IIF negative/CTD screen positive samples, mainly Ro52, Ro60, dsDNA, PM/Scl and Jo1. Thirty four of these patients were diagnosed with an ANA-associated autoimmune rheumatic disease (AARD) (seven SLE, 15 Sjӧgren's syndrome, nine autoimmune inflammatory myositis, three systemic sclerosis). Among 1568 ANA-IIF positive/CTD screen negative discrepant patients, a specific antibody was found in 94 (6%) samples (28 patients with AARD, 13 with undifferentiated connective tissue disease, two with undifferentiated arthritis, and 51 without a rheumatic disease). Conclusions This study is the first that compares the IIF method vs. solid-phase assays in the detection of ANA, on a very large sample size from the routine work-up (real-life approach). Results show that the association of solid-phase CTD screen tests to the ANA-IIF test increases the sensitivity (from 89.2% to 97.4%) and the specificity (from 64.6% to 98.4%) of serological tests for ANA screening. Analysis of costs demonstrated that combination of the two tests is also cost-effective, reducing global costs for the immunoserological diagnosis of AARD by 22%.

Interleukin-23 as a therapeutic target for inflammatory myopathy

Current treatments of polymyositis and dermatomyositis (PM/DM) depend on non-specific immunosuppressants. This study was performed to elucidate the role of interleukin (IL)-23, as their possible therapeutic target. As was reported earlier in PM/DM patients, serum IL-23 levels were elevated in mice with C protein induced-myositis (CIM), a murine model of PM. IL-23 was expressed by macrophages in the PM/DM and CIM muscles and by dendritic cells and macrophages in the lymph nodes from the CIM mice. It was also expressed by macrophages in the chemically injured muscles, but not those recruited into the muscles by footpad injection of Freund’s complete adjuvant, demonstrating that IL-23 production should be associated with muscle damage. Genetic deletion of IL-23 as well as preventive and therapeutic administration of blocking antibodies against IL-23p19 subunit suppressed CIM. When lymph node cells from the CIM mice were transferred adoptively into naive wild type or IL-23p19 deficient recipient mice, both recipients developed myositis equally. Thus, elevated IL-23 should promote dendritic cells and macrophages to activate the autoaggressive T cells. Our findings suggest that IL-23 should mediate positive feedback loop from the muscle damage to the T cell activation and be a promising therapeutic target for autoimmune myositis.

Immune Checkpoint Inhibitors and Neuromuscular Adverse Events

Neuromuscular adverse events (AEs) in cancer patients treated with immune checkpoint inhibitors (ICIs) are characterized by diverse clinical subsets. The general features of neuromuscular AEs have remained elusive due to its low frequency, ranging from 1-2% of cancer patients undergoing ICIs therapy. The diseases affect the central nervous system, peripheral nerves, neuromuscular junction, and muscle. Disease onset and progression may be rapid with a critical clinical course. The clinical presentation may differ from that of patients whose symptoms are unrelated to drugs. Headache, dizziness, and dysgeusia are relatively common and mild treatment-related AEs. In contrast, immune-related AEs, such as autoimmune encephalitis, demyelinating polyneuropathy, myasthenia, and myositis are more serious conditions. There is a strong correlation between ICIs and myasthenia, myositis, and myocarditis. Immune-modulating medication is generally effective for neuromuscular AEs. However, there are guidelines for treatment, and checkpoint inhibitor therapy should be withheld until the pathophysiology of the AEs is defined. Both CD8⁺ cytotoxic T cells and autoantibodies are involved in the pathogenesis of neuromuscular AEs. Therefore, understanding the mechanisms of neuromuscular AEs is necessary to alleviate the symptoms associated with ICIs therapy in cancer patients.

Histogram analysis derived from apparent diffusion coefficient (ADC) is more sensitive to reflect serological parameters in myositis than conventional ADC analysis.

Diffusion-weighted imaging (DWI) has the potential of being able to reflect histopathology architecture. A novel imaging approach, namely histogram analysis, is used to further characterize tissues on MRI. The aim of this study was to correlate histogram parameters derived from apparent diffusion coefficient (ADC) maps with serological parameters in myositis. 16 patients with autoimmune myositis were included in this retrospective study. DWI was obtained on a 1.5 T scanner by using the b-values of 0 and 1000 s mm-2. Histogram analysis was performed as a whole muscle measurement by using a custom-made Matlab-based application. The following ADC histogram parameters were estimated: ADCmean, ADCmax, ADCmin, ADCmedian, ADCmode, and the following percentiles ADCp10, ADCp25, ADCp75, ADCp90, as well histogram parameters kurtosis, skewness, and entropy. In all patients, the blood sample was acquired within 3 days to the MRI. The following serological parameters were estimated: alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, C-reactive protein (CRP) and myoglobin. All patients were screened for Jo1-autobodies. Kurtosis correlated inversely with CRP (p = -0.55 and 0.03). Furthermore, ADCp10 and ADCp90 values tended to correlate with creatine kinase (p = -0.43, 0.11, and p = -0.42, = 0.12 respectively). In addition, ADCmean, p10, p25, median, mode, and entropy were different between Jo1-positive and Jo1-negative patients. ADC histogram parameters are sensitive for detection of muscle alterations in myositis patients. Advances in knowledge: This study identified that kurtosis derived from ADC maps is associated with CRP in myositis patients. Furthermore, several ADC histogram parameters are statistically different between Jo1-positive and Jo1-negative patients.

MR Imaging of Atraumatic Muscle Disorders.

Atraumatic disorders of skeletal muscles include congenital variants; inherited myopathies; acquired inflammatory, infectious, or ischemic disorders; neoplastic diseases; and conditions leading to muscle atrophy. These have overlapping appearances at magnetic resonance (MR) imaging and are challenging for the radiologist to differentiate. The authors organize muscle disorders into four MR imaging patterns: (a) abnormal anatomy with normal signal intensity, (b) edema/inflammation, (c) mass, and (d) atrophy, highlighting each of their key clinical and imaging findings. Anatomic muscle variants, while common, do not produce signal intensity alterations and therefore are easily overlooked. Muscle edema is the most common pattern but is nonspecific, with a broad differential diagnosis. Autoimmune, paraneoplastic, and drug-induced myositis tend to be symmetric, whereas infection, radiation-induced injury, and myonecrosis are focal asymmetric processes. Architectural distortion in the setting of muscle edema suggests one of these latter processes. Intramuscular masses include primary neoplasms, metastases, and several benign masslike lesions that simulate malignancy. Some lesions, such as lipomas, low-flow vascular malformations, fibromatoses, and subacute hematomas, are distinctive, but many intramuscular masses ultimately require a biopsy for definitive diagnosis. Atrophy is the irreversible end result of any muscle disease of sufficient severity and is the dominant finding in disorders such as the muscular dystrophies, denervation myopathy, and sarcopenia. This imaging-based classification, in correlation with clinical and laboratory data, will aid the radiologist in interpreting MR imaging findings in patients with atraumatic muscle disorders. ©RSNA, 2018.

Compositional dynamics and codon usage pattern of BRCA1 gene across nine mammalian species

The BRCA1 gene is located on the human chromosome 17q21.31 and plays important role in biological processes. The aminoacyl-tRNA synthetases (AARS) are a family of heterogenous enzymes responsible protein synthesis and whose secondary functions include a role in autoimmune myositis. Our findings reveal that the compositional constraint and the preference of more A/T –ending codons determine the codon usage patterns in BRCA1 gene while more G/C-ending codons influence the codon usage pattern of AARS gene among mammals. The codon usage bias in BRCA1 and AARS genes is low. The codon CGC encoding arginine amino acid and the codon TTA encoding leucine were uniformly distributed in BRCA1 and AARS genes, respectively in mammals including human. Natural selection might have played a major role while mutation pressure might have played a minor role in shaping the codon usage pattern of BRCA1 and AARS genes.

Role of myositis-specific autoantibodies in personalized therapy

In a landmark breakthrough in 1976, Reichlin and Mattioli discovered the first myositis-specific antibody (MSA) called anti-Mi2 antibody that identified a specific clinical phenotype characterized by pathognomonic skin rash of dermatomyositis, typical proximal muscle weakness, good response to treatment, and the absence of interstitial lung disease and cancer. The discovery firmly placed inflammatory muscle diseases among the group of systemic rheumatic autoimmune diseases. Over the next four decades, a large number of additional MSAs have been discovered in this group of patients called “idiopathic inflammatory myopathy” (IIM). It is becoming clear that the increasing numbers of autoantibodies being discovered may necessitate a name change to “autoimmune myositis” (AIM), as recently suggested by a French-Canadian group. In the light of these discoveries, it was evident that a new classification system based on the combination of clinical phenotypes and the associated autoantibodies would soon be propounded. Preliminary report on such a classification was published in 2016 by the Swedish Group from Karolinska Institute led by Prof. Ingrid Lundberg. In October 2017, the European League Against Rheumatism and the American College of Rheumatology published the provisional classification criteria for IIM with the aim to categorize patients in uniform subgroups of clinical phenotype for meaningful drug trials. These are exciting times for clinicians, for research scientists, and for the patients with inflammatory myositis with reasons to be optimistic about a bright future. This short review provides a summary of the present knowledge with emphasis on its clinical implications.

C4d as a marker of complement activation in dermatomyositis muscle tissue.

To study C4d expression as a marker of complement activation in the diagnosis of dermatomyositis. Muscle biopsies from patients diagnosed as definite dermatomyositis (10), nonspecific myositis associated with connective tissue disease (9), necrotizing autoimmune myositis (1), inclusion body myositis (1), and normal muscle (1) according to European Neuromuscular criteria 2004 were studied for C4d expression and capillary loss on CD 34 immunohistochemistry. C4d was expressed in all biopsies of definite dermatomyositis in the perimysial vessels and in 3/10 endomysial capillaries corresponding to capillary loss on CD 34.C4d expression was seen in 2/3 perimysial and endomysial vessels in nonspecific myositis (2/3 overlap myositis), and 1/1 of nectrotizing autoimmune myositis.Necrotic muscle fibers in all biopsies showed positivity irrespective of the diagnosis. C4d can be used as a marker of complement activation for the diagnosis of dermatomyositis.

Malignancy screening in autoimmune myositis among Australian rheumatologists.

The international literature advocates for cancer screening in newly diagnosed patients with autoimmune myositis; however, there is no widely accepted consensus or guideline to outline the optimal cancer screening strategy and the evidence is currently insufficient to support any recommendation. Our study aimed to establish the current trends in practice in malignancy screening in autoimmune myositis among Australian rheumatologists. All rheumatologists who were full members of the Australian Rheumatology Association in 2016 (386) were invited to complete an online questionnaire. Respondent demographics and information on screening approach and concerns were collected using multiple choice and open-response questions. There were 60 respondents (16% response rate). All available quantitative data were analysed and reported using statistical software. Qualitative data were analysed and grouped according to themes. Most respondents (93%) performed cancer screening. Significant variation was found in terms of approach to patient selection, choice of screening test, delegation of screening and repeat screening. A lack of clinical practice consensus and guideline (77%), test selection knowledge (37%), knowledge on repeated screening (53%) and the potential for harm (62%) were identified challenges in this area. Malignancy screening in autoimmune myositis was variable among this small cohort of Australian rheumatologists. The observed differences were driven by patient factors and clinician preferences. The group identified several challenges in the cancer screening process. Further research is warranted to address these challenges, close the evidence gap and develop workable guidelines.

Effect of butylphthalide intervention on experimental autoimmune myositis in guinea pigs.

Idiopathic inflammatory myopathies are a group of rare muscular diseases that are characterized by acute, subacute or chronic proximal and symmetric muscle weakness, muscle fiber necrosis and infiltration of inflammatory cells, particularly activated CD8+ cytotoxic T cells and phagocytes. 3-n-butylphthalide (NBP) protects mitochondria and reduces the inflammatory response in multiple disease models. In myositis, it has remained elusive whether NBP can protect muscle cells from muscle fiber injury. Experimental autoimmune myositis (EAM) was induced in a total of 40 guinea pigs by myosin immunization. After 4 weeks, low- or high-dose NBP solution was intraperitoneally injected. Saline solution was used as a negative control. After 10 days, the clinical manifestations were assessed by determining rodent grasping power, histopathological changes, Ca2+-adenosinetriphosphatase (ATPase) activity by an ATPase kit, and mRNA expression of interferon (IFN)-γ, retinoic acid receptor-related orphan nuclear receptor (ROR)γt and forkhead box (Fox) p3 in muscle tissue by reverse-transcription quantitative polymerase chain reaction analysis. It was demonstrated that NBP improved the myodynamia of guinea pigs with EAM and reduced the pathological inflammatory cell infiltration in a dose-dependent manner. NBP improved the Ca2+-ATPase activity of the muscle mitochondrial membrane and muscle plasma membrane in animals with EAM. It also reduced the mRNA expression of IFN-γ and RORγt, and significantly increased the mRNA expression of Foxp3 in muscle tissue. These results provided a basis for the consideration of NBP as a novel agent for the treatment of myositis and other muscular diseases associated with autoimmunity and inflammation.

Les scores d’activité des maladies auto-immunes ont-ils une place en pratique quotidienne de médecine interne ?

IntroductionAssessing disease activity in patients suffering from autoimmune diseases is complex. Symptoms are multiple, often subjective and there are no reliable biomarkers. Many activity scores have been implemented to compare treatment efficacy in clinical trials. Their use in clinical practice is largely unknown. We performed a practical survey to analyze the use of activity scores in clinical practice to consider treatment response and to assess the determinants of their use. MethodsA sample of French internists answered a questionnaire about activity scores of systemic lupus erythematosus, Sjögren's syndrome, autoimmune myositis and necrotizing vasculitis of small vessels. The frequency of use of these tools, the causes of their non-use, and the general opinion of practitioners about the place of theses scores in current practice were described. ResultsThe form was completed by 92 internists. Seventy percent of them supported the use of activity scores in consultations, but actually used them in less than 25% of patient visits. The reasons for the low use of these scores are mainly the ignorance of their existence (42%) and their length or complexity (28%). ConclusionThe discrepancy between the ratio of practitioners who believe that scores have a place in daily practice and their actual use shows that the current scores do not meet the needs. The implementation of easily usable activity scores in inflammatory diseases remains a challenge for the internists.

Multicenter Registry on Inflammatory Myositis From the Rheumatology Society in Madrid, Spain: Descriptive Analysis

ObjectiveTo analyze clinical characteristics, survival and causes of death of patients diagnosed with autoimmune inflammatory myositis in the REMICAM registry from the Society of Rheumatology in the Community of Madrid (SORCOM). MethodsMulticenter cohort of patients diagnosed with autoimmune inflammatory myopathy with follow-up between January 1980 and December 2014. A total of 313 variables concerning demographic, clinical and morbidity data were collected, and a comparison was performed between clinical subgroups. ResultsA total of 479 patients were recruited from 12 centers with 14% of patients lost to follow-up. Seventy-four percent of cases were women, age at diagnosis of 44±23 years and a mean follow-up period of 10±8 years. The most frequent clinical subgroups were primary myositis (PM 29%, DM 22%), followed by overlap myositis (20.5%), juvenile myositis (18%), myositis associated with cancer (8%), immune-mediated necrotizing myositis (1%) and inclusion body myositis (1%). During the follow-up period, a total of 114 deaths (28%) were registered, the main causes being cancer (24%), infections (23%) and cardiovascular events (21%). ConclusionsA total of 479 patients were recruited in the REMICAM registry of inflammatory myopathies. Including sociodemographic, clinical and prognostic information, it represents the largest Spanish multicenter registry to date in rheumatology, and constitutes an important source for conducting further substudies.

IL-21 Exacerbates Autoimmune Myositis by Enhancing the Accumulation of GM-CSF–Producing γδ T Cells in the Muscle

Abstract IL-21 is suggested to be involved in the development of some autoimmune diseases; however, the role of IL-21 in autoimmune inflammatory myopathies (IMs) remains unknown. In this study, we found that serum levels of IL-21 were significantly elevated in a subset of IM patients. Upon the induction of experimental autoimmune myositis (EAM), IL-21 was produced by CD4+ T cells in the muscle, and muscle weakness and muscle inflammation were less obvious in IL-21–deficient (IL-21−/−) mice compared with those in wild-type (WT) mice. Analysis of inflammatory cytokine production from draining lymph node cells of EAM-induced mice revealed that GM-CSF production was significantly decreased in IL-21−/− mice. Importantly, GM-CSF production from γδT cells, but not CD4+ T cells, was significantly reduced in EAM-induced IL-21−/− mice. In addition, the severity of EAM was attenuated by GM-CSF neutralization in WT mice or γδT cell deficiency. The majority of muscle-infiltrating GM-CSF–producing γδT cells expressed Vγ4+Vδ4+ TCR, and the number of Vγ4+Vδ4+ cells in the muscle was significantly decreased in EAM-induced IL-21−/− mice as compared with that in EAM-induced WT mice. Moreover, muscle-infiltrating Vγ4+Vδ4+ cells exhibited CX3CR1high phenotype, and the induction of Cx3cl1, a ligand for CX3CR1, in the muscle was reduced in EAM-induced IL-21−/− mice. Furthermore, reporter assays revealed that IL-21 activated the promoter of Cx3cl1. Consistent with these findings, serum levels of CX3CL1 were correlated with the levels of IL-21 in IM patients. Taken together, these results suggest that IL-21 facilitates autoimmune myositis through the accumulation of GM-CSF–producing Vγ4+Vδ4+ cells in the muscle possibly via CX3CR1-CX3CL1 pathways.

EC.O.8 - Epigenetic regulation of a mitochondrial apoptosis mediator, harakiri in maintaining muscle membrane stability in autoimmune myositis

EC.O.8 - Epigenetic regulation of a mitochondrial apoptosis mediator, harakiri in maintaining muscle membrane stability in autoimmune myositis

3-n-Butylphthalide reduces the oxidative damage of muscles in an experimental autoimmune myositis animal model.

3-n-Butylphthalide (NBP) protects the mitochondria and reduces apoptosis in multiple disease models. However, it remains to be determined whether NBP can protect muscle cells from oxidative stress, lipid peroxidation and apoptosis in myositis. In the present study, a myosin immunization protocol was applied to induce experimental autoimmune myositis (EAM) in guinea pigs. After 4 weeks, a low- or high-dose NBP solution was injected intraperitoneally into the guinea pigs, with saline solution serving as the negative control. After 10 days, the guinea pigs were sacrificed and muscle cells were isolated for analysis. The results revealed that NBP increased the superoxide dismutase and catalase activity, and reduced malondialdehyde activity in the EAM model. Furthermore, NBP enhanced ATPase activity in muscle mitochondrial membranes and muscle fiber membranes, reduced the number of apoptotic cells, and differentially regulated the Bcl-2, Bax and BAD mRNA and protein expression levels in muscle tissues and sera. NBP directly protects muscle mitochondria and muscle cells from oxidative damage. Notably, NBP reduced muscle cell apoptosis. Thus, it is speculated that, as an antioxidant treatment, NBP may benefit individuals with myopathy.

IFN-β-induced reactive oxygen species and mitochondrial damage contribute to muscle impairment and inflammation maintenance in dermatomyositis

Dermatomyositis (DM) is an autoimmune disease associated with enhanced type I interferon (IFN) signalling in skeletal muscle, but the mechanisms underlying muscle dysfunction and inflammation perpetuation remain unknown. Transcriptomic analysis of early untreated DM muscles revealed that the main cluster of down-regulated genes was mitochondria-related. Histochemical, electron microscopy, and in situ oxygraphy analysis showed mitochondrial abnormalities, including increased reactive oxygen species (ROS) production and decreased respiration, which was correlated with low exercise capacities and a type I IFN signature. Moreover, IFN-β induced ROS production in human myotubes was found to contribute to mitochondrial malfunctions. Importantly, the ROS scavenger N-acetyl cysteine (NAC) prevented mitochondrial dysfunctions, type I IFN-stimulated transcript levels, inflammatory cell infiltrate, and muscle weakness in an experimental autoimmune myositis mouse model. Thus, these data highlight a central role of mitochondria and ROS in DM. Mitochondrial dysfunctions, mediated by IFN-β induced-ROS, contribute to poor exercise capacity. In addition, mitochondrial dysfunctions increase ROS production that drive type I IFN-inducible gene expression and muscle inflammation, and may thus self-sustain the disease. Given that current DM treatments only induce partial recovery and expose to serious adverse events (including muscular toxicity), protecting mitochondria from dysfunctions may open new therapeutic avenues for DM.

Safety and efficacy of off-label use of biologic therapies in patients with inflammatory rheumatic diseases refractory to standard of care therapy : Data from anationwide German registry (GRAID2)

The German Registry of Autoimmune Diseases2 (GRAID2) is aretrospective, non-interventional, multicenter registry study collecting data from patients with inflammatory, mainly rheumatic diseases refractory to standard of care therapy and treated with an off-label biologic therapy. The retrospective documentation comprised case history, diagnosis, course of disease (including safety and global efficacy). The objective was to evaluate the global clinical outcome and safety of off-label biologic therapy in clinical practice. Data from 311 patients with an overall observation period of 338.5 patient-years were collected. The mean patients age was 47.8 years with 56.9% females. The most frequently documented diagnoses comprised rejection prophylaxis/therapy after renal transplantation (NTX, 18.3%), ANCA-vasculitides (17.4%), systemic lupus erythematosus (SLE, 10.3%), autoinflammatory fever syndromes (8.4%), autoimmune myositis (7.4%) and pemphigus (5.8%). Documented biologic therapies included rituximab (RTX, 70.1%), tocilizumab (TCZ, 9.3%), infliximab (IFX, 7.1%), anakinra (ANK, 5.5%), adalimumab (ADA, 3.5%), etanercept (ETA, 2.3%) and certolizumab (CTZ, 0.6%). After initiation of off-label biologic treatment, tolerability was assessed by the physicians as "very good"/"good" in 95.5%. Altogether, 275 adverse events were documented and of these, 104 were classified as serious adverse events and occurred in 62patients. In 19of these patients severe infections (30.6%) were documented, resulting in arate of 5.6 severe infections per 100 patient years. A total of six deaths were documented, while five of these cases were rated as not related to the biologics treatment. Notably, the use of RTX in patients with small vessel vasculitides and of TCZ in patients with large vessel vasculitides prior to their approval support their relevance in clinical management of patients with severe diseases. The results of this registry together with data of GRAID1 provide evidence that use of off-label biologic therapies in patients with inflammatory rheumatic diseases refractory to conventional treatment did not result in any new safety signal already known for these compounds or subsequently shown by clinical trials in certain entities.