When a Child Refuses to Play: A Rare Myopathy.

Idiopathic inflammatory myopathies (IIM) are a rare group of systemic diseases characterized by progressive proximal muscle weakness and skeletal muscle inflammation. We describe a clinical report of a seven-year-old boy presenting with myalgia and proximal muscle weakness beginning three weeks earlier, with laboratory, MRI, and muscle biopsy findings consistent with IIM. The patient was treated with corticosteroids, methotrexate, immunoglobulin, and intensive motor rehabilitation, with favorable evolution. Diagnosis of Juvenile Polymyositis was confirmed. Three years later, we assisted a relapse of muscle weakness and muscle cytolysis with the onset of bilateral eyelid skin microulcers compatible with dermatomyositis. This report intends to highlight the importance of early diagnosis and treatment in IIM due to the significant burden associated with this group of diseases. In this case, the late onset of the skin lesion contributed to the challenge in this diagnosis.

A combination of major histocompatibility complex (MHC) I overexpression and type I interferon induce mitochondrial dysfunction in human skeletal myoblasts.

The overexpression of major histocompatibility complex (MHC) I on the surface of muscle fibers is a characteristic hallmark of the idiopathic inflammatory myopathies (IIMs), collectively termed myositis. Alongside MHC-I overexpression, subtypes of myositis, display a distinct type I interferon (IFN) signature. This study examined the combinational effects of elevated MHC-I and type I IFNs (IFNα/ß) on mitochondrial function, as mitochondrial dysfunction is often seen in IIMs. Human skeletal muscle myoblasts were transfected with an MHC-I isoform using the mammalian HLA-A2/Kb vector. Mitochondrial respiration, mitochondrial membrane potential, and reactive oxygen/nitrogen species generation were assessed with or without IFNα and IFNß. We show that MHC-I overexpression in human skeletal muscle myoblasts led to decreased basal glycolysis and mitochondrial respiration, cellular spare respiratory capacity, adenosine triphosphate-linked respiration, and an increased proton leak, which were all exaggerated by type I IFNs. Mitochondrial membrane depolarization was induced by MHC-I overexpression both in absence and presence of type I IFNs. Human myoblasts overexpressing MHC-I showed elevated nitric oxide generation that was abolished when combined with IFN. MHC-I on its own did not result in an increased reactive oxygen species (ROS) production, but IFN on their own, or combined with MHC-I overexpression did induce elevated ROS generation. Surprisingly, we observed no gross changes in mitochondrial reticular structure or markers of mitochondrial dynamics. We present new evidence that MHC-I overexpression and type I IFNs aggravate the effects each has on mitochondrial function in human skeletal muscle cells, providing novel insights into their mechanisms of action and suggesting important implications in the further study of myositis pathogenesis.

Idiopathic Inflammatory Myopathies-associated Interstitial Lung Disease in Adults.

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of autoimmune diseases characterized by muscle involvement and various extramuscular manifestations. Interstitial lung disease (ILD) is one of the most common extramuscular manifestations of IIM and is associated with significant mortality and morbidity. The clinical phenotypes, treatment responses, and prognosis of IIM-ILD are significantly related to myositis-specific antibody (MSA) profiles, with some racial differences. The features associated with MSA in IIM-ILD could also be relevant to cases of ILD where MSA is present but does not meet the criteria for IIM. The anti-melanoma differentiation-associated gene 5 antibody is highly associated with rapidly progressive ILD (RP-ILD), especially in Asian populations, and with characteristic cutaneous manifestations, such as skin ulcers. Radiologically, ground-glass opacities, consolidations, and nonsegmental linear opacities were more predominant than reticular opacities and honeycombing. While the mortality rate is still around 30%, the prognosis can be improved with early intensive therapy with corticosteroids and multiple immunosuppressants. In contrast, anti-aminoacyl-tRNA synthetase (ARS) antibodies are associated with chronic ILD, although RP-ILD is also common. Patients with anti-ARS antibodies often show lung-predominant presentations, with subtle muscle and skin involvement. Radiologically, reticular opacities, with or without consolidation, are predominant and may progress to honeycombing over time. Combination therapy with corticosteroids and a single immunosuppressant is recommended to prevent relapses, which often lead to a decline in lung function and fatal long-term outcomes. Significant advances in immunology and genetics holds promise for fostering more personalized approaches to managing IIM-ILD.

Contribution of major histocompatibility complex class II immunostaining in distinguishing idiopathic inflammatory myopathy subgroups: A histopathological cohort study.

Idiopathic inflammatory myopathies (IIM) are rare, acquired muscle diseases; their diagnosis of is based on clinical, serological, and histological criteria. MHC-I-positive immunostaining, although non-specific, is used as a marker for IIM diagnosis; however, the significance of major histocompatibility complex (MHC)-II immunostaining in IIM remains debated. We investigated patterns of MHC-II immunostaining in myofibers and capillaries in muscle biopsies from 103 patients with dermatomyositis ([DM], n = 31), inclusion body myositis ([IBM], n = 24), anti-synthetase syndrome ([ASyS], n = 10), immune-mediated necrotizing myopathy ([IMNM], n = 18), or overlap myositis ([OM], n = 20). MHC-II immunostaining of myofibers was abnormal in 63/103 of patients (61%) but the patterns differed according to the IIM subgroup. They were diffuse in IBM (96%), negative in IMNM (83%), perifascicular in ASyS (70%), negative (61%) or perifascicular (32%) in DM, and either clustered (40%), perifascicular (30%), or diffuse heterogeneous (15%) in OM. Capillary MHC-II immunostaining also identified quantitative (capillary dropout, n = 47/88, 53%) and qualitative abnormalities, that is, architectural abnormalities, including dilated and leaky capillaries, (n = 79/98, 81%) in all IIM subgroups. Thus, MHC-II myofiber expression patterns allow distinguishing among IIM subgroups. We suggest the addition of MHC-II immunostaining to routine histological panels for IIM diagnosis.

Diagnostic Value of Whole-Body MRI in Pediatric Patients with Suspected Rheumatic Diseases.

Background and Objectives: The diagnosis of rheumatic diseases in children is challenging and requires the use of advanced imaging examinations such as whole-body magnetic resonance imaging (MRI). Whole-body MRI allows visualization of bone marrow edema (BME), muscle edema, joint effusion and changes in the soft tissues surrounding the joints. The aim of this study was to collect and compare whole-body MRI findings, laboratory results and clinical manifestations of pediatric patients with suspected rheumatic disease. Materials and methods: In this retrospective single-center study, 33 patients who underwent whole-body MRI were included. Their age ranged from 9 to 17 years, and 24 (72.73%) of the patients were female. Patients were diagnosed as follows: juvenile idiopathic arthritis (27.27%), juvenile idiopathic inflammatory myopathies (21.21%), chronic nonbacterial osteomyelitis (21.21%) and other medical conditions (30.30%), such as arthritis associated with infection, scleroderma, Takayasu arteritis, polyarteritis nodosa and joint damage. Results: The most common symptom reported by 26 (79.79%) patients was pain. On physical examination, the limitation of joint mobility was examined in 17 (51.51%), swelling of the joints was observed in 12 (36.36%) patients and decreased muscle strength was noticed in 11 (33.33%) patients. An increase in the C-reactive protein (12%), erythrocyte sedimentation rate (9%), leukocyte count (9%) and creatine kinase (CK) (18%) was observed. Whole-body MRI revealed myositis (30%), joint effusion (27%) and BME (24%). The statistical analysis showed a significant relationship between myositis and the elevated CK level (p < 0.05). Conclusions: The most common symptom in the studied population was pain, while the limitation of joint mobility was found in more than half of patients. Myositis was the most commonly imaged lesion on the whole-body MRI and it was related to an increase in the CK level.

Deciphering the Role of Maternal Microchimerism in Offspring Autoimmunity: A Narrative Review.

Feto-maternal microchimerism is the bidirectional transfer of cells through the placenta during pregnancy that can affect the health of both the mother and the offspring, even in childhood or adulthood. However, microchimerism seems to have different consequences in the mother, who already has a developed immune system, than in the fetus, which is vulnerable with immature defense mechanisms. Studies have shown that the presence of fetal microchimeric cells in the mother can be associated with reduced fetal growth, pre-eclampsia, miscarriage, premature birth, and the risk of autoimmune disease development in the future. However, some studies report that they may also play a positive role in the healing of maternal tissue, in cancer and cardiovascular disease. There are few studies in the literature regarding the role of maternal microchimeric cells in fetal autoimmunity. Even fewer have examined their association with the potential triggering of autoimmune diseases later in the offspring's life. The objectives of this review were to elucidate the mechanisms underlying the potential association between maternal cells and autoimmune conditions in offspring. Based on our findings, several hypotheses have been proposed regarding possible mechanisms by which maternal cells may trigger autoimmunity. In Type 1 diabetes, maternal cells have been implicated in either attacking the offspring's pancreatic ß-cells, producing insulin, differentiating into endocrine and exocrine cells, or serving as markers of tissue damage. Additionally, several potential mechanisms have been suggested for the onset of neonatal lupus erythematosus. In this context, maternal cells may induce a graft-versus-host or host-versus-graft reaction in the offspring, function as effectors within tissues, or contribute to tissue healing. These cells have also been found to participate in inflammation and fibrosis processes, as well as differentiate into myocardial cells, potentially triggering an immune response. Moreover, the involvement of maternal microchimeric cells has been supported in conditions such as juvenile idiopathic inflammatory myopathies, Sjögren's syndrome, systemic sclerosis, biliary atresia, and rheumatoid arthritis. Conversely, no association has been found between maternal cells and celiac disease in offspring. These findings suggest that the role of maternal cells in autoimmunity remains a controversial topic that warrants further investigation.

Inflammatory myopathies in 2024: Better classify them to better treat them.

The discovery, over the last forty years or so, of specific myositis auto-antibodies (easily dosed in routine nowadays) and the fine clinically and pathologically phenotypic descriptions of affected patients have made it possible to review the classification of inflammatory myopathies. The arrival of "omic" techniques has also led to the discovery of different pathophysiological mechanisms among these different subgroups of myositis. Naturally, therapeutic approaches specifically targeting the representative abnormal pathways of each subgroup are being evaluated. This modern approach to myositis, which is clinical, pathophysiological, and therapeutic in the making, is presented in this review article.

Inclusion body myositis: Correcting impaired mitochondrial and lysosomal autophagy as a potential therapeutic strategy.

Inclusion body myositis (IBM) is a late onset sporadic myopathy with a characteristic clinical presentation, but as yet unknown aetiology or effective treatment. Typical clinical features are early predominant asymmetric weakness of finger flexor and knee extensor muscles. Muscle biopsy shows endomysial inflammatory infiltrate, mitochondrial changes, and protein aggregation. Proteostasis (protein turnover) appears to be impaired, linked to potentially dysregulated chaperone-mediated autophagy and mitophagy (a type of mitochondrial quality control). In this review, we bring together the most recent clinical and biological data describing IBM. We then address the question of diagnosing this pathology and the relevance of the current biological markers that characterize IBM. In these descriptions, we put a particular emphasis on data related to the deregulation of autophagic processes and to the mitochondrial-lysosomal crosstalk. Finally, after a short description of current treatments, an overview is provided pointing towards novel therapeutic targets and emerging regulatory molecules that are being explored for treating IBM. Special attention is paid to autophagy inhibitors that may offer innovative breakthrough therapies for patients with IBM.

Nailfold Capillaroscopy Changes in Patients with Idiopathic Inflammatory Myopathies.

Background/Objectives: Idiopathic inflammatory myopathies (IIMs) are rare autoimmune disorders characterized by progressive proximal muscle weakness and varying extra-muscular manifestations. The latest 2017 EULAR/ACR criteria classify them into subgroups. This study aims to evaluate the role of nailfold capillaroscopy (NFC) as a diagnostic and prognostic tool in IIMs by comparing capillaroscopic patterns across different IIM subtypes. Methods: We conducted an observational, cross-sectional study at the Institute of Rheumatology in Belgrade, analyzing 90 patients diagnosed with IIMs per the 2017 EULAR/ACR criteria. Patients were categorized into dermatomyositis (DM) (n = 37), polymyositis (PM) (n = 35), amyopathic dermatomyositis (ADM) (n = 13), and juvenile dermatomyositis (JDM) (n = 5). A control group of 35 patients with primary Raynaud's phenomenon was also included. NFC findings, clinical manifestations, and laboratory data were compared across the groups. Results: In DM, 81.9% exhibited a scleroderma capillaroscopic pattern, which was also present in 76.9% of ADM patients. In PM, the most common pattern was nonspecific changes (48.6%). JDM patients showed a high prevalence of scleroderma changes (n = 4 (80%)). Scleroderma patterns correlated with Gottron's papules, heliotrope rash, periungual erythema, Raynaud's phenomenon, and interstitial lung disease (ILD). No significant differences were found in laboratory parameters across capillaroscopic groups, except for a higher prevalence of anti-Jo1 antibodies in patients with nonspecific capillaroscopic changes. Conclusions: NFC is a valuable tool for differentiating IIM subtypes and correlating clinical manifestations with specific capillaroscopic patterns. The high prevalence of scleroderma changes in DM and ADM suggests their potential as a diagnostic and prognostic marker in IIMs. Further research with larger cohorts is warranted to validate these findings.

Can we differentiate patients with dysferlinopathies and inflammatory myopathies by ultrasound? A discriminant analysis study.

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases that are characterized by inflammation and muscle weakness. Dysferlinopathies are autosomal recessive limb-girdle muscular dystrophies caused by mutations in DYSF, which share a similar clinical presentation and histopathological inflammatory changes. To determine the sonographic differences between dysferlinopathies and IIM and whether these differences allow their classification. This observational, cross-sectional, and analytical study evaluated 20 muscles from 11 patients with dysferlinopathies and 11 patients with IIM. The patients were matched for age, sex, and disease duration. Clinical and laboratory variables were analyzed. Semi-quantitative scales were used to weigh the gray scale and power Doppler muscle abnormalities. Descriptive statistics were computed and discriminant analysis was performed to determine the ultrasound variables that best predicted the final diagnosis. Forty muscles were evaluated. Atrophy and higher Heckmatt scale scores were observed in patients with dysferlinopathies. A set of three muscles (biceps/brachialis, quadriceps, and gastrocnemius) had a diagnostic accuracy of 100% (sensitivity, 100%; specificity, 100%; canonical coefficient, 0.733 p < 0.001). A set of two formulas was used to classify both diseases correctly. In the present study, scanning of three muscle groups showed high diagnostic accuracy in differentiating dysferlinopathies from MII. Ultrasound can be used as an initial test in patients with suspected muscle disease or as an additional tool to support diagnosis in controversial cases.

Pathogenic mechanisms of disease in idiopathic inflammatory myopathies: autoantibodies as clues.

Idiopathic inflammatory myopathies (IIMs) encompass a spectrum of autoimmune diseases characterized by muscle inflammation and systemic involvement. This review aimed to synthesize current evidence on the clinical significance and pathogenic mechanisms underlying autoantibodies associated with IIMs. Autoantibodies targeting aminoacyl-tRNA synthetases (ARS) play a pivotal role in antisynthetase syndrome (ASS), highlighting associations with interstitial lung disease (ILD) and distinctive clinical features. Anti-Mi-2 antibodies in dermatomyositis (DM) are hallmarked by characteristic cutaneous manifestations and favorable prognostic outcomes. Conversely, anti-TIF1 antibodies are correlated with DM and a higher risk of malignancies, implicating CD8+ T cells in its pathogenesis. Anti-MDA5 antibodies signify clinically amyopathic DM (CADM) with severe ILD, linked to dysregulated neutrophil extracellular trap (NET) formation. In immune-mediated necrotizing myopathies (IMNMs), anti-SRP and anti-HMGCR antibodies induce complement-mediated myopathy, typically following statin exposure. Additionally, anti-TRIM72 antibodies emerge as potential diagnostic markers in IIMs. Anti-cN1A autoantibodies are linked to inclusion body myositis (IBM) and play a decisive role in muscle protein degradation. Meanwhile, anti-FHL1 autoantibodies are associated with severe disease manifestations and muscle damage, as established in experimental models. Anti-eIF3 autoantibodies, recently identified in polymyositis (PM) patients, are rarely detected (<1%) and associated with a favorable prognosis. Elucidating these autoantibodies is anticipated to not only assist in early diagnosis and disease stratification but also inform targeted therapeutic interventions, emphasizing the intricate interplay between autoimmunity, cellular dysfunction, and clinical outcomes in IIMs.

Disease characteristics and medications use in idiopathic inflammatory myopathy: a multi-center prospective observational study of decentralized remote vs. traditional clinic enrollment.

OBJECTIVES: Idiopathic Inflammatory Myopathies (IIM) are rare and characterized by heterogeneous manifestations and clinical trajectories. Utilizing tele-research methods has the potential to improve participant recruitment and advance the understanding of the disease. We aimed to evaluate disease characteristics in IIM patients throughout the U.S. and compare these parameters between patients recruited remotely through mobile application or website vs those recruited locally in myositis clinics. METHODS: "Myositis Patient Centered Tele-Research" (My PACER) is a multicentre prospective observational study of U.S. IIM subjects, competitively recruited through traditional in-person clinic visits (Center-Based Cohort [CBC]), and remotely using mobile application or website and social media (Tele-Research Cohort [TRC]). Data collection comprised baseline demographic and clinical variables, encompassing symptoms, organ involvement, diagnostic tests results and medication use. RESULTS: The study included 120 IIM patients, 82 in the TRC and 38 in the CBC. The average age was 55 ± 13.4, 75% females and 81% Caucasians. Both cohorts exhibited similar demographic characteristics. Overall, 41% dermatomyositis, 27% polymyositis, 23% anti-synthetase syndrome, and 9% necrotizing myositis patients were enrolled, with comparable subtypes prevalence among cohorts (p= 0.85). The groups demonstrated similarities in multiple clinical factors, including muscle enzymes, diagnostic delay, employment status, various patient and physician-reported outcomes, functional tests, and the frequency of abnormal findings in chest CT, pulmonary function tests, and electromyography. TRC patients received biologics and csDMARDs more frequently (p< 0.001 and p= 0.013, respectively). CONCLUSION: Tele-research recruitment yielded a patient cohort resembling traditionally recruited patients demographically and clinically, indicating its effectiveness for robust and diverse patient recruitment in clinical studies.

Clinical characteristics of idiopathic inflammatory myopathies patients with anti-PM/Scl antibodies.

OBJECTIVES: To analyze the clinical features of idiopathic inflammatory myopathies (IIMs) patients with anti-PM/Scl antibodies. METHODS: In this retrospective cohort study, we compared the clinical manifestations between patients who were solely positive for anti-PM/Scl antibodies (isolated anti-PM/Scl group) and those with a coexistence of anti-PM/Scl antibodies and myositis-specific antibodies (MSAs) (double-positive group). RESULTS: Sixty-five IIMs patients positive for anti-PM/Scl antibodies were included, among whom 51 (78.5 %) were females, with a mean age of 49.1 years. Thirty-four (52.3 %) patients coexisted with MSAs. Compared to the double-positive group, the isolated anti-PM/Scl group demonstrated a higher proportion of women (90.3 % vs 67.6 %, p = 0.026) and a higher incidence of sclerodactyly (16.1 % vs 0, p = 0.021). Although there were no differences in the incidence of muscular weakness, dysphagia, or creatine kinase levels, thigh magnetic resonance imaging (MRI) revealed less muscle edema, atrophy, and fatty replacement in the isolated anti-PM/Scl group (p < 0.05). Interstitial lung disease (ILD) occurred in 80 % of patients, more frequently in the double-positive group (90.6 % vs 67.9 %, p = 0.028). According to HRCT, non-specific interstitial pneumonia (NSIP) was the most common pattern among anti-PM/Scl antibodies positive IIMs patients. The double-positive group exhibited higher ferritin levels, and a lower peripheral lymphocyte count (p < 0.05). The mortality rate in the double-positive group was higher than that in the isolated anti-PM/Scl group (20.6 % vs 0, p = 0.034). CONCLUSION: Among IIMs patients who tested positive for anti-PM/Scl antibodies, ILD emerged as the predominant clinical feature, particularly when combined with MSA. Notably, patients with isolated anti-PM/Scl antibodies exhibited a favorable prognosis following immunotherapy.

Clinical characteristics of primary biliary cirrhosis - idiopathic inflammatory myopathy overlap syndrome: A single center study.

PURPOSE: Primary biliary cirrhosis-idiopathic inflammatory myopathy (PBC-IIM) overlap syndrome (OS) is a rare condition in which cardiac involvement is observed. We aimed to characterize the clinical features and associated factors of PBC-IIM OS patients with cardiac involvement. METHODS: Patients with PBC-IIM OS that visited our hospital from January 1983 to December 2021 were enrolled. Clinical presentations and laboratory and imaging data were recorded. The clinical data of patients with and without cardiac involvement were compared. According to the first instance of a disease flare, prognostic factors were also studied. RESULTS: Thirty-four patients with PBC-IIM OS were enrolled. A total of 58.8% of patients presented with muscle weakness at disease onset, which primarily involved skeletal muscle (85.3%). Slight liver dysfunction was discovered in this OS cohort. In patients with cardiac involvement, palpitation (63.6%) and dyspnea (36.4%) were the most common onset symptoms. Arrhythmia was a vital manifestation in OS patients, in which half of OS patients had nonsustained ventricular tachycardia (50.0%, 11/22). Compared with noncardiac involvement, myalgia (4.5%, P = 0.004) and fever (0.0%, P = 0.011) were reported relatively rarely at disease onset in the group with cardiac involvement. The prognosis analysis showed that positivity for anti-Ro52 (HR=0.00, P = 0.034) negatively correlated with relapse in OS patients. CONCLUSION: PBC-IIM OS has unique features. Typical clinical manifestations and early worsening cardiac indicators can be used to identify cardiac involvement and predict prognosis. Anti-Ro52 may have prognostic value for PBC-IIM OS.

Exposome: Epigenetics and autoimmune diseases.

Systemic autoimmune diseases are complex conditions characterized by an immune system dysregulation and an aberrant activation against self-antigens, leading to tissue and organ damage. Even though genetic predisposition plays a role, it cannot fully explain the onset of these diseases, highlighting the significant impact of non-heritable influences such as environment, hormones and infections. The exposome represents all those factors, ranging from chemical pollutants and dietary components to psychological stressors and infectious agents. Epigenetics, which studies changes in gene expression without altering the DNA sequence, is a crucial link between exposome and the development of autoimmune diseases. Key epigenetic mechanisms include DNA methylation, histone modifications, and non-coding RNAs. These epigenetic modifications could provide a potential piece of the puzzle in understanding systemic autoimmune diseases and their connection with the exposome. In this work we have collected the most important and recent evidence in epigenetic changes linked to systemic autoimmune diseases (systemic lupus erythematosus, idiopathic inflammatory myopathies, ANCA-associated vasculitis, and rheumatoid arthritis), emphasizing the roles these changes may play in disease pathogenesis, their potential as diagnostic biomarkers and their prospective in the development of targeted therapies.

Activity Prediction Modeling Based on a Combination of Growth Differentiation Factor 15 and Serum Biomarker Levels in Dermatomyositis and Polymyositis.

AIMS: Growth differentiation factor 15 (GDF15) plays an important role in multiple inflammatory disorders. We aimed to analyze serum GDF15 levels in adult patients with idiopathic inflammatory myopathies (IIMs). METHODS: Serum GDF15 levels were measured in 179 adult patients with IIMs and 76 healthy controls (HCs). The association between GDF15 levels and disease variables was analyzed using Spearman's rank correlation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory ability of GDF15 and the GDF15-to-lymphocyte ratio (GLR). Machine learning methods were applied to build predictive models. RESULTS: GDF15 levels and GLR were significantly elevated in patients with adult IIMs than in HCs. Compared with patients in remission, both GDF15 and GLR were significantly higher in myositis patients in an active phase. GDF15 levels correlated positively with myositis disease activity indices and negatively correlated with lymphocyte and platelet counts. ROC curve analysis revealed that GDF15 levels and GLR outperformed muscle enzymes and distinguished well between patients with active disease and those in remission. Furthermore, even in the normal muscle enzyme group, GDF15 levels and GLR were also well-distinguished between patients with active disease and those in remission. Using machine learning, a logistic regression model of GDF15 combined with creatine kinase and lymphocyte count was constructed and had a reliable predictive value for disease activity. CONCLUSIONS: GDF15, particularly GLR, was significantly correlated with disease activity in adult patients with IIMs. They could serve as useful biochemical markers for evaluating disease activity, monitoring disease progression, and guiding treatment in adult patients with IIMs.

Secondary mitochondrial dysfunction across the spectrum of hereditary and acquired muscle disorders.

Mitochondria form a dynamic network within skeletal muscle. This network is not only responsible for producing adenosine triphosphate (ATP) through oxidative phosphorylation, but also responds through fission, fusion and mitophagy to various factors, such as increased energy demands, oxidative stress, inflammation, and calcium dysregulation. Mitochondrial dysfunction in skeletal muscle not only occurs in primary mitochondrial myopathies, but also other hereditary and acquired myopathies. As such, this review attempts to highlight the clinical and histopathologic aspects of mitochondrial dysfunction seen in hereditary and acquired myopathies, as well as discuss potential mechanisms leading to mitochondrial dysfunction and therapies to restore mitochondrial function.

Effectiveness and safety of low dose Rituximab as remission-maintenance treatment for patients with refractory idiopathic inflammatory myopathies: results of a retrospective study from a monocentric cohort.

OBJECTIVE: Our aim was to assess efficacy and safety of Rituximab (RTX) in patients with refractory Idiopathic inflammatory myopathies (IIM) from a monocentric cohort. Thereafter, we evaluated the efficacy of a low-dose RTX regimen as a remission-maintenance therapy. METHODS: We retrospectively evaluated a cohort of patients affected with IIM treated with RTX. All patients were refractory to glucocorticoids (GC) and at least one immunosuppressant. Two infusions of 1 g two weeks apart were considered as standard cycle of RTX, a single dose of 1 g every six months was deemed as a low-dose RTX regimen. Complete and partial response were defined according to physician's judgment, laboratory and radiological features. RESULTS: Thirty-six patients affected with IIM were enrolled. Eighteen patients (50%) required the use of RTX for muscular involvement, 6 (16.7%) for interstitial lung disease (ILD), 12 (33.3%) for both myositis and ILD. We observed complete response to RTX in 25 patients (69.4%), partial response in 7 (19.4%) and no response in 4 (11.1%), with an overall response of 88.8% (partial and complete response). From the subgroup of twenty-five patients that achieved a complete response, six were treated with a low dose maintenance therapy maintaining a complete response to RTX. Twenty-six patients who achieved a complete or partial response were able to decrease the mean daily GC dose. Infections were the major adverse events detected in our study. CONCLUSIONS: RTX shows favorable outcomes in refractory patients with IIM. A low-dose regimen of RTX appears to be effective in maintaining remission after induction with standard dose. Key Points • The precise pathogenic mechanism of idiopathic inflammatory myopathies (IIM) remains elusive; however, a growing body of data support the autoimmune hypothesis. In this context, rituximab, a B cell-depleting agent, has emerged as a second-line therapeutic option in IIM. • Several studies have assessed It its effectiveness in refractory IIM patients. • Limited information exists on the use of Rituximab as maintenance therapy in patients who have achieved remission following induction therapy with Rituximab.

The association of cardiovascular disease risk with coronary artery calcification and thoracic aortic dilation: a study in idiopathic inflammatory myopathies and systemic lupus erythematosus.

OBJECTIVES: We aim to explore the prevalence of coronary artery calcification (CAC) and ascending/descending thoracic aorta (AA/DA) dilation in idiopathic inflammatory myopathies (IIM) and systemic lupus erythematosus (SLE) patients, and to assess associations between cardiovascular disease (CVD) risk factors and these imaging signatures. METHODS: This study recruited 151 IIM patients, 140 SLE patients, and 195 controls. The CAC and AA/DA diameters were quantified using non-gated chest CT images. The independent samples t-test or Mann-Whitney test was chosen for comparisons of continuous variables between patients and healthy controls. For categorical data, comparisons were made using the chi-square test or Fisher's exact test. Multivariate regression or Spearman's correlation analysis was employed to probe the associations between CVD risk factors and Framingham risk score (FRS) with imaging signatures. RESULTS: The IIM and SLE patients showed significantly higher prevalence of CAC and AA/DA dilatation (P < 0.01). Age was a risk factor for both CAC and AA/DA dilatation in all cohorts (P < 0.01). In IIM patients, the AA/DA dilatation was associated with BMI (P = 0.05). In SLE patients, CAC was associated with the elevated CRP level (P = 0.05). Without CAC, both IIM and SLE patients showed significant correlations between AA/DA diameters and FRS (P < 0.01, P < 0.01). Only in SLE patients, the interleukin-6 (IL-6) level correlated with AA/DA diameters. CONCLUSION: The IIM and SLE patients more commonly exhibit CAC and AA/DA dilation. These subclinical atherosclerosis signs are associated with traditional CVD risk factors. For AID patients without CAC, AA/DA diameters could serve as a potential biomarker for early CVD risk. Key Points • The study characterized the manifestation of subclinical atherosclerosis imaging biomarkers (CAC, AA/DA dilation) in IIM and SLE patients. • AA/DA diameters could serve as an early imaging biomarker in clinical management for IIM and SLE patients with early-onset and no CAC present.