Celiac disease prevalence in patients with idiopathic inflammatory myopathies, a cross-sectional study.

Up to 30% of patients with celiac disease (CD) suffer from concurrent autoimmune disease, compared to 3% of the general population. The association between CD and the current clinical phenotypes of inflammatory myopathies (IIM) patients has not been thoroughly addressed. Assess the CD features among patients with IIM and their relationship with the clinical phenotype and the myositis specific (MSA) and associated antibodies (MAA). For this cross-sectional study, we recruited 99 adult patients classified as IIM from a tertiary center in Mexico. We assessed serum MSA, MAA, and CD-associated autoantibodies (IgA anti-tissue transglutaminase (tTG) and both IgA and IgG anti-deaminated gliadin peptide (DGP)). Patients with highly suggestive serology for CD were then tested for IgG anti-endomysium antibodies, and a duodenal biopsy was performed. 70.7% of patients were positive for at least one antibody. Nine duodenal biopsies were taken, revealing findings compatible with celiac disease in two cases. Subjects with anti-MDA5 antibodies were more likely to have positive anti-tTG IgA antibodies (OR 6.76, 95% CI 1.85-24.62, P = 0.013) and suggestive CD serology (OR 6.41, 95% CI 1.62-25.29, P = 0.009). Patients with anti-Mi2 antibodies were more likely to have positive anti-DGP IgG antibodies (OR 3.35, 95% CI 1.12-9.96, P = 0.039), while positivity for these autoantibodies was less frequent in patients with anti-NXP2 antibodies (OR 0.22, 95% CI 0.06-0.80, P = 0.035). There is a higher prevalence of serologic and definite CD in patients with IIM compared to the general population. Identifying this subgroup of patients may have prognostic and therapeutic implications. Key points • The study estimated a serological celiac disease (CD) prevalence of 70.7% in patients with idiopathic inflammatory myopathies (IIM) and a biopsy-confirmed prevalence of 2%, suggesting that IIM patients should be considered a high-risk population for CD. • We identified a significant association between serological CD and the presence of anti-MDA5 and anti-Mi2 antibodies, suggesting a potential justification for celiac disease screening in this specific subgroup of patients. • The impact of gluten-free diets on IIM patients with serological markers of CD remains untested and warrants further investigation through prospective, randomized studies.

Immunohistochemical expression in idiopathic inflammatory myopathies at a single center in Vietnam.

Background: The identification of idiopathic inflammatory myopathies (IIMs) requires a comprehensive analysis involving clinical manifestations and histological findings. This study aims to provide insights into the histopathological and immunohistochemical aspects of IIMs. Methods: This retrospective case series involved 56 patients diagnosed with IIMs at the Department of Pathology, University of Medicine and Pharmacy at Ho Chi Minh City, from 2019 to 2023. The histology and immunohistochemical expression of HLA-ABC, HLA-DR, C5b-9, Mx1/2/3, and p62 were detected. Results: We examined six categories of inflammatory myopathy, including immunemediated necrotizing myopathy (58.9%), dermatomyositis (DM; 23.2%), overlap myositis (8.9%), antisynthetase syndrome (5.4%), inclusion body myositis (IBM; 1.8%), and polymyositis (1.8%). The average age of the patients was 49.7 ± 16.1 years, with a female-to-male ratio of 3:1. Inflammatory cell infiltration in the endomysium was present in 62.5% of cases, perifascicular atrophy was found in 17.8%, and fiber necrosis was observed in 42 cases (75.0%). Rimmed vacuoles were present in 100% of cases in the IBM group. Immunohistochemistry showed the following positivity rates: HLA-ABC (89.2%), HLA-DR (19.6%), C5b-9 (57.1%), and Mx1/2/3 (10.7%). Mx1/2/3 expression was high in DM cases. p62 vacuole deposits were noted in the IBM case. The combination of membrane attack complex and major histocompatibility complex I helped detect IIMs in 96% of cases. Conclusions: The diagnosis of IIMs and their subtypes should be based on clinical features and histopathological characteristics. Immunohistochemistry plays a crucial role in the diagnosis and differentiation of these subgroups.

The Role of Exercise to Improve Physiological, Physical and Psychological Health Outcome in Idiopathic Inflammatory Myopathies (IIM).

Idiopathic inflammatory myopathies (IIM) impact all aspects of health, physiological, physical, and psychological. Hallmark symptoms of IIM are muscle weakness, reduced muscle endurance and aerobic capacity. Recently, pain and fatigue as well as anxiety and depression have emerged as common and debilitating symptoms in patients with IIM. The aim of this scoping review is to, in a holistic way, describe how IIM impact patients' physiological, physical, and psychological health and how exercise has a role to treat as well as potentially counteract the effects of the disease. Inflammation induces non-immune response and organ damage. These changes with additional impact of physical inactivity lead to muscle impairment and reduced aerobic capacity. Pain, fatigue and low psychological well-being and overall quality of life are also common health aspects of IIM. Medical treatment can reduce inflammation but has in turn serious side effects such as muscle atrophy, type-II diabetes, and hypertension, which exercise has the potential to treat, and perhaps also counteract. In addition, exercise improves muscle function, aerobic capacity and might also reduce fatigue and pain. New evidence shows that reducing systemic inflammation may also improve patient-reported subjective health, quality of life and psychological well-being. Exercise in combination with medical treatment is becoming an important part of the treatment for patients with IIM as exercise has the potential to promote health aspects of various dimensions in patients with IIM.

HRCT findings predict 1-year mortality in patients with acute exacerbation of idiopathic inflammatory myopathies-associated interstitial lung disease.

Background: Acute exacerbation of idiopathic inflammatory myopathies-associated interstitial lung disease (AE-IIM-ILD) is a significant event associated with increased morbidity and mortality. However, few studies investigated the potential prognostic factors contributing to mortality in patients who experience AE-IIM-ILD. Objectives: The purpose of our study was to comprehensively investigate whether high-resolution computed tomography (HRCT) findings predict the 1-year mortality in patients who experience AE-IIM-ILD. Methods: A cohort of 69 patients with AE-IIM-ILD was retrospectively created. The cohort was 79.7 % female, with a mean age of 50.7. Several HRCT features, including total interstitial lung disease extent (TIDE), distribution patterns, and radiologic ILD patterns, were assessed. A directed acyclic graph (DAG) was used to evaluate the statistical relationship between variables. The Cox regression method was performed to identify potential prognostic factors associated with mortality. Results: The HRCT findings significantly associated with AE-IIM-ILD mortality include TIDE (HR per 10%-increase, 1.64; 95%CI, 1.29-2.1, p < 0.001; model 1: C-index, 0.785), diffuse distribution pattern (HR, 3.75, 95%CI, 1.5-9.38, p = 0.005; model 2: C-index, 0.737), and radiologic diffuse alveolar damage (DAD) pattern (HR, 6.37, 95 % CI, 0.81-50.21, p = 0.079; model 3: C-index, 0.735). TIDE greater than 58.33 %, diffuse distribution pattern, and radiologic DAD pattern correlate with poor prognosis. The 90-day, 180-day, and 1-year survival rates of patients who experience AE-IIM-ILD were 75.3 %, 66.3 %, and 63.3 %, respectively. Conclusion: HRCT findings, including TIDE, distribution pattern, and radiological pattern, are predictive of 1-year mortality in patients who experience AE-IIM-ILD.

Spirituality, Religiosity, and Mental Health in Patients with Idiopathic Inflammatory Myopathies: A Brazilian Multicentric Case-Control Study.

No published studies have investigated the correlation between religiosity, spirituality, mental health, and idiopathic inflammatory myopathy (IIM) or systemic autoimmune myopathy. Therefore, we aimed to evaluate the association between religiosity/spirituality, sociodemographic factors, and the mental health of IIM patients. This is a multicenter case-control study that included 151 patients with IIMs and 95 individuals without autoimmune diseases (controls), held between August 2022 and April 2023. This study used a semi-structured questionnaire that included sociodemographic information and the juxtaposition of the following questionnaires: the Attitudes Related to Spirituality Scale (ARES); the Duke University Religion Index (DUKE), which is composed of the organizational religious affiliation (ORA), non-organizational religious affiliation (NORA), and intrinsic religiosity (IR) domains; and the General Health Questionnaire-12 (GHQ-12). Data were analyzed using Epi Info software 7.2.5 (Centers for Disease Control and Prevention, Atlanta, GA, USA). A comparison between the mean values of the ARES, DUKE, and GHQ-12 scales was made using the Wilcoxon-Mann-Whitney and Kruskal-Wallis tests. A logistic regression test was used with the variables whose difference was statistically significant in the univariate analysis. Correlation analysis was performed using the Spearman rho coefficient. A higher prevalence of evangelicals and a lower prevalence of Catholics (p < 0.050) were seen in the IIM group compared to controls. Positive association was demonstrated between IIMs and the pardo ethnicity (OR = 2.26, 95% CI = 1.20-4.25, p = 0.011), highest ORA (OR = 2.81, 95% CI = 1.53-5.15, p < 0.001), NORA (OR = 3.99, 95% CI = 1.94-8·18, p < 0.001), IR (OR = 5.27, 95% CI = 2.32-11.97, p < 0.001), and ARES values (OR = 1.08, 95% CI = 1.04-1.13, p < 0.001). Mental health levels were compared between the groups (p > 0.999). Therefore, higher levels of religiosity and spirituality were observed in the IIM group than in the control group, but there was a similar distribution of mental health levels. The following can be cited as advantages of the present study: (i) the large sample for a rare disease with the presence of a control group; (ii) the multicenter characteristic with participation from three regions of Brazil; (iii) being the first study to map aspects of religiosity, spirituality, and mental health in IIMs.

Tacrolimus Personalized Therapy based on CYP3A5 Genotype in Chinese Patients with Idiopathic Inflammatory Myopathies.

OBJECTIVE: Idiopathic inflammatory myopathies (IIM) are a heterogeneous and life-threatening group of diseases, especially anti-melanoma differentiation-associated gene 5 antibody positive dermatomyositis (MDA5+ DM) is reportedly strongly associated with high mortality rate. Tacrolimus (TAC) provides an excellent therapeutic option, but the trough concentration (Cmin) -outcome relationship remains unexplored. This study was undertaken to identify optimal Cmin and individualized dose based on CYP3A5 genotype for IIM patients. METHODS: 134 IIM patients with 467 Cmin were enrolled. We examined the relationship between TAC Cmin and relapses. The receiver operating characteristic analysis was used to confirm the optimal Cmin. Analyses of factors influencing Cmin were conducted. The dose requirement based on CYP3A5 genotype was confirmed. RESULTS: TAC Cmin is strongly associated with relapses. The optimal cutoff values were 5.30, 5.85, 4.85 and 5.35 ng/ml for acute, subacute, chronic and all phase IIM patients (p = 0.001, 0.013, 0.002, and < 0.001, respectively), as well as 5.35, 5.85, 5.55 and 5.85 ng/ml for acute, subacute, chronic and all phase MDA5+ DM patients (p = 0.007, 0.001, 0.036, and < 0.001, respectively). CYP3A5 genotype was one of the significant factors influencing TAC Cmin. CYP3A5 expressers required 0.059 mg/kg/d to attain the target Cmin, while nonexpressers required 0.046 mg/kg/d (p = 0.019). CONCLUSION: TAC treatment may elicit favorable outcome in patients with IIM and MDA5+ DM when Cmin exceeded 5.35 and 5.85 ng/ml, which is crucial to lower relapse rate. The individualized dose based on the CYP3A5 genotype provides a reference for TAC personalized therapy in IIM.

Circulating extracellular vesicles and small non-coding RNAs cargo in idiopathic inflammatory myopathies reveal differences across myositis subsets.

OBJECTIVE: To investigate the epigenetic footprint of idiopathic inflammatory myopathies (IIM) through characterization of circulating extracellular vesicles (EVs) and the expression of EV-derived small non-coding RNAs (sncRNAs). METHODS: In this cross-sectional study, EVs were isolated by size-exclusion chromatography from plasma of patients with IIM and age- and sex-matched healthy donors (HD). EV-derived sncRNAs were sequenced and quantified using Next-Generation Sequencing (NGS). Following quality control and normalization, filtered count reads were used for differential microRNA (miRNA) and piwi-interacting RNA (piRNA) expression analyses. Putative gene targets enriched for pathways implicated in IIM were analyzed. Patients' clinical and laboratory characteristics at the time of sampling were recorded. RESULTS: Forty-seven IIM patients and 45 HD were enrolled. MiR-486-5p (p < 0.01), miR-122-5p, miR-192-5p, and miR-32-5p were significantly upregulated (p < 0.05 for all), while miR-142-3p (p < 0.001), miR-141-3p (p < 0.01), let-7a-5p (p < 0.05) and miR-3613-5p (p < 0.05) downregulated in EVs from IIM patients versus HD. MiR-486-5p was associated with raised muscle enzymes levels. Several target genes of up/downregulated miRNAs in IIM participate in inflammation, necroptosis, interferon and immune signaling. Six piRNAs were significantly dysregulated in IIM EVs versus HD (p < 0.05). Within IIM, miR-335-5p was selectively upregulated and miR-27a-5p downregulated in dermatomyositis (n = 21, p < 0.01). Finally, plasma EV levels were significantly increased in cancer-associated myositis (CAM, n = 12) versus non-CAM IIM (n = 35, p = 0.02) and HD (p < 0.01). EVs cargo in CAM was significantly enriched of let-7f-5p and depleted of miR-143-3p. CONCLUSION: Through an unbiased screening of EV-derived sncRNAs, we characterize miRNAs and piRNAs in the EVs cargo as potential biomarkers and modifiers of diverse IIM phenotypes.

Presenting clinical and imaging features of patients with clinically amyopathic interstitial lung disease associated with myositis-specific autoantibodies.

Background: Lung involvement in the context of idiopathic inflammatory myopathies has significant impact on outcome; early and accurate diagnosis is important but can be difficult to achieve. In particular, patients without clinically evident muscle involvement pose a significant diagnostic challenge. Methods: A computer-assisted search was conducted to identify patients with amyopathic interstitial lung disease associated with the presence of myositis-specific autoantibodies. Medical records and chest imaging studies were reviewed to identify clinical and radiologic features at presentation. Results: Of the 35 patients with amyopathic interstitial lung disease associated with myositis-specific autoantibodies, the median age was 65 years (range 43-78) and 20 were women (57%). Of the patients, 34% had previously visited the rheumatology department. Presenting symptoms consisted of dyspnea (94%), cough (43%), and arthritis (23%). Raynaud phenomenon, "mechanic hands," Gottron papules, and inspiratory crackles were present in 23, 31, 9, and 74% of patients, respectively. After a detailed history, none of the patients reported muscle weakness, while four (11%) exhibited increased CK levels; of these four, two had a concomitant increase in aldolase levels. Median FVC was 79% predicted (range: 49-135) and median DLco was 50% predicted (range: 17-103). HRCT pattern was suggestive of an alternative to UIP pattern in 31/33 (94%) patients; the most common imaging patterns were NSIP (49%) and NSIP/OP (39%). Conclusion: In patients with NSIP and NSIP/OP pattern, the presence of amyopathic interstitial lung disease associated with myositis-specific autoantibodies should be considered even in the absence of clinical evident myositis.

Association Between Wearable Device Use and Quality of Life in Patients With Idiopathic Inflammatory Myopathies and Primary Systemic Vasculitis.

Background Despite the increasing use of wearable devices worldwide, concise data on these instruments in patients with systemic autoimmune rheumatic diseases, including idiopathic inflammatory myopathies (IIM) and primary systemic vasculitis (PSV), are lacking. Objectives The aim of this study is to investigate the knowledge and use of wearable devices and to assess their impact on the general quality of life of patients with IIM and PSV. Moreover, we compared these characteristics between patients with IIM and PSV users and non-users of wearable devices. Methods This single-center, cross-sectional study was conducted between January 2023 and June 2023. We included adult patients with IIM and PSV and a control group (CTR) and evaluated their use of cell phones and wearables, level of physical activity, and quality of life. Results A total of 132 patients with IIM, 82 with PSV, and 178 in the CTR were evaluated. Overall, 169 patients and 144 in the CTR were aware of wearable devices, of whom 50 (29.6%) and 47 (32.6%), respectively, had already used this technology. In addition, the IPAQ-Mets and EQ-5D scores were lower in the IIM and PSV groups than in the CTR, and the fatigue severity scale (FSS) scores were higher in the IIM and PSV groups than in the CTR. Patients who used the devices showed FSS scores of 29 (18-40) points, with higher levels of IPAQ-Mets among device users, indicating greater physical activity than among nonusers. Conclusion Based on the results, the use of wearable devices is associated with better fatigue and IPAQ scores. Possibly, the use of such devices can have an impact on better lifestyle habits among these patients.

Characteristics of emerging new autoimmune diseases after COVID-19 vaccination: A sub-study by the COVAD group.

BACKGROUND: Despite the overall safety and efficacy of COVID-19 vaccinations, rare cases of systemic autoimmune diseases (SAIDs) have been reported post-vaccination. This study used a global survey to analyze SAIDs in susceptible individuals' post-vaccination. METHODS: A cross-sectional study was conducted among participants with self-reported new-onset SAIDs using the COVID-19 Vaccination in Autoimmune Diseases (COVAD) 2 study dataset-a validated, patient-reported e-survey-to analyze the long-term safety of COVID-19 vaccines. Baseline characteristics of patients with new-onset SAIDs and vaccinated healthy controls (HCs) were compared after propensity score matching based on age and sex in a 1:4 ratio. RESULTS: Of 16 750 individuals, 74 (median age 52 years, 79.9% females, and 76.7% Caucasians) had new-onset SAID post-vaccination, mainly idiopathic inflammatory myopathies (IIMs) (n = 23, 31.51%), arthritis (n = 15; 20.53%), and polymyalgia rheumatica (PMR) (n = 12, 16.40%). Higher odds of new-onset SAIDs were noted among Caucasians (OR = 5.3; 95% CI = 2.9-9.7; p < .001) and Moderna vaccine recipients (OR = 2.7; 95% CI = 1.3-5.3; p = .004). New-onset SAIDs were associated with AID multimorbidity (OR = 1.4; 95% CI = 1.1-1.7; p < .001), mental health disorders (OR = 1.6; 95% CI = 1.3-1.9; p < .001), and mixed race (OR = 2.2; 95% CI = 1.2-4.2; p = .010), where those aged >60 years (OR = 0.6; 95% CI = 0.4-0.8; p = .007) and from high/medium human development index (HDI) countries (compared to very high HDI) reported fewer events than HCs. CONCLUSION: This study reports a low occurrence of new-onset SAIDs following COVID-19 vaccination, primarily IIMs, PMR, and inflammatory arthritis. Identified risk factors included pre-existing AID multimorbidity, mental health diseases, and mixed race. Revaccination was well tolerated by most patients; therefore, we recommend continuing COVID-19 vaccination in the general population. However, long-term studies are needed to understand the autoimmune phenomena arising post-vaccination.

Imatinib-induced dermatomyositis sine dermatitis - a rare case report.

Idiopathic Inflammatory Myopathies are rare conditions with several heterogeneous disease subtypes. They can range from limited muscle or skin involvement to severe, systemic, life-threatening disease. Although the etiology is unknown, some evidence suggests a role for external agents, particularly drugs. Herein, we present a case of a 71-year-old woman with chronic myeloid leukemia who developed imatinib-induced dermatomyositis sine dermatitis. The presentation was predominantly muscular, characterized by proximal muscle weakness and myalgia of the lower limbs, with positive anti-Mi2a antibodies. Spontaneous recovery was observed after drug discontinuation, without the need for immunosuppressive therapy. This is the first confirmed description of an imatinib-induced dermatomyositis sine dermatitis. It reflects the importance of a high awareness from rheumatologists and hematologists to accurately anticipate and identify similar situations.

Pathogenic role and clinical significance of neutrophils and neutrophil extracellular traps in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of chronic autoimmune diseases characterized by muscle damage and extramuscular symptoms, including specific skin rash, arthritis, interstitial lung disease, and cardiac involvement. While the etiology and pathogenesis of IIM are not yet fully understood, emerging evidence suggests that neutrophils and neutrophil extracellular traps (NETs) have a role in the pathogenesis. Recent research has identified increased levels of circulating and tissue neutrophils as well as NETs in patients with IIM; these contribute to the activation of the type I and type II interferons pathway. During active IIM disease, myositis-specific antibodies are associated with the formation and incomplete degradation of NETs, leading to damage in the lungs, muscles, and blood vessels of patients. This review focuses on the pathogenic role and clinical significance of neutrophils and NETs in IIM, and it includes a discussion of potential targeted treatment strategies.

Therapeutic efficacy and safety of JAK inhibitors in treating polymyositis/dermatomyositis: a single-arm systemic meta-analysis.

Introduction: We performed a single-arm meta-analysis to evaluate the efficacy and safety of JAK inhibitors in the treatment of dermatomyositis (DM)/ polymyositis (PM). Methods: Relevant studies from four databases were systematically searched until April 25, 2023. The primary endpoint was Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) and other outcomes were Manual Muscle Testing (MMT) and Creatine Kinase (CK). According to the type of JAK and medication regimen, we conducted subgroup analyses. The registration number in PROSPERO was CRD42023416493. Results: According to the selection criteria, we identified 7 publications with a total of 91 patients. Regarding skin lesions, the CDASI decreased by 17.67 (95% CI: -20.94 ~ -14.41). The CK increased by 8.64 U (95% CI: -28.25 ~ 45.53). About muscle lesions, MMT increased by 10.31 (95% CI: -2.83 ~ 23.46). Subgroup analysis revealed that different types of JAK inhibitors had various degrees of reduction. CDASI in patients treated with RUX had the lowest one [-20.00 (95% CI: -34.9 ~ -5.1)], followed by TOF [-18.29 (95% CI: -21.8 ~ -14.78)] and BAR [-11.2 (95% CI: -21.51 ~ -0.89)]. Additionally, the mean reduction in CDASI in patients treated with TOF alone was 16.16 (95% CI: -21.21 ~ -11.11), in combination with other immunosuppressants was 18.59 (95% CI: -22.74 ~ -14.45). For safety evaluation, one patient developed Orolabial HSV, and two patients developed thromboembolism events. Discussion: In summary, this meta-analysis demonstrated that JAK inhibitors can potentially treat DM/PM without severe adverse reactions. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42023416493, identifier CRD42023416493.

[A unicenter real-world study of the correlation factors for complete clinical response in idiopathic inflammatory myopathies].

OBJECTIVE: To investigate the correlation factors of complete clinical response in idiopathic inflammatory myopathies (IIMs) patients receiving conventional treatment. METHODS: Patients diagnosed with IIMs hospitalized in Peking University People's Hospital from January 2000 to June 2023 were included. The correlation factors of complete clinical response to conventional treatment were identified by analyzing the clinical characteristics, laboratory features, peripheral blood lymphocytes, immunological indicators, and therapeutic drugs. RESULTS: Among the 635 patients included, 518 patients finished the follow-up, with an average time of 36.8 months. The total complete clinical response rate of IIMs was 50.0% (259/518). The complete clinical response rate of dermatomyositis (DM), anti-synthetase syndrome (ASS) and immune-mediated necrotizing myopathy (IMNM) were 53.5%, 48.9% and 39.0%, respectively. Fever (P=0.002) and rapid progressive interstitial lung disease (RP-ILD) (P=0.014) were observed much more frequently in non-complete clinical response group than in complete clinical response group. The aspartate transaminase (AST), lactate dehydrogenase (LDH), D-dimer, erythrocyte sedimentation rate (ESR), C-reaction protein (CRP) and serum ferritin were significantly higher in non-complete clinical response group as compared with complete clinical response group. As for the treatment, the percentage of glucocorticoid received and intravenous immunoglobin (IVIG) were significantly higher in non-complete clinical response group than in complete clinical response group. Risk factor analysis showed that IMNM subtype (P=0.007), interstitial lung disease (ILD) (P=0.001), eleva-ted AST (P=0.012), elevated serum ferritin (P=0.016) and decreased count of CD4+T cells in peripheral blood (P=0.004) might be the risk factors for IIMs non-complete clinical response. CONCLUSION: The total complete clinical response rate of IIMs is low, especially for IMNM subtype. More effective intervention should be administered to patients with ILD, elevated AST, elevated serum ferritin or decreased count of CD4+T cells at disease onset.

Identification of distinct immune signatures in inclusion body myositis by peripheral blood immunophenotyping using machine learning models.

Objective: Inclusion body myositis (IBM) is a progressive late-onset muscle disease characterised by preferential weakness of quadriceps femoris and finger flexors, with elusive causes involving immune, degenerative, genetic and age-related factors. Overlapping with normal muscle ageing makes diagnosis and prognosis problematic. Methods: We characterised peripheral blood leucocytes in 81 IBM patients and 45 healthy controls using flow cytometry. Using a random forest classifier, we identified immune changes in IBM compared to HC. K-means clustering and the random forest one-versus-rest model classified patients into three immunophenotypic clusters. Functional outcome measures including mTUG, 2MWT, IBM-FRS, EAT-10, knee extension and grip strength were assessed across clusters. Results: The random forest model achieved a 94% AUC ROC with 82.76% specificity and 100% sensitivity. Significant differences were found in IBM patients, including increased CD8+ T-bet+ cells, CD4+ T cells skewed towards a Th1 phenotype and altered γδ T cell repertoire with a reduced proportion of Vγ9+Vδ2+ cells. IBM patients formed three clusters: (i) activated and inflammatory CD8+ and CD4+ T-cell profile and the highest proportion of anti-cN1A-positive patients in cluster 1; (ii) limited inflammation in cluster 2; (iii) highly differentiated, pro-inflammatory T-cell profile in cluster 3. Additionally, no significant differences in patients' age and gender were detected between immunophenotype clusters; however, worsening trends were detected with several functional outcomes. Conclusion: These findings unveil distinct immune profiles in IBM, shedding light on underlying pathological mechanisms for potential immunoregulatory therapeutic development.

Novel B-cell subsets as potential biomarkers in idiopathic inflammatory myopathies: insights into disease pathogenesis and disease activity.

Idiopathic inflammatory myopathies are a heterogeneous group of rare autoimmune disorders characterized by progressive muscle weakness and the histopathologic findings of inflammatory infiltrates in muscle tissue. Although their pathogenesis remains indefinite, the association of autoantibodies with clinical manifestations and the evidence of high effectiveness of depleting therapies suggest that B cells could be implicated. Therefore, we explored the landscape of peripheral B cells in this disease by multiparametric flow cytometry, finding significant numerical decreases in memory and double-negative subsets, as well as an expansion of the naive compartment relative to healthy controls, that contribute to defining disease-associated B-cell subset signatures and correlating with different clinical features of patients. Additionally, we determined the potential value of these subsets as diagnostic biomarkers, thus positioning B cells as neglected key elements possibly participating in idiopathic inflammatory myopathy onset or development.

Machine learning-driven immunophenotypic stratification of mixed connective tissue disease corroborating the clinical heterogeneity.

OBJECTIVES: To stratify patients with mixed connective tissue disease (MCTD) based on their immunophenotype. METHODS: We analyzed the immunophenotype and transcriptome of 24 immune cell subsets from patients with MCTD, systemic lupus erythematosus (SLE), idiopathic inflammatory myopathy (IIM), and systemic sclerosis (SSc) from our functional genome database, ImmuNexUT (https://www.immunexut.org/). MCTD patients were stratified by employing machine learning models including Random Forest, trained by immunophenotyping data from SLE, IIM, and SSc patients. Transcriptomes were analyzed with gene set variation analysis (GSVA) and clinical features of MCTD subgroups were compared. RESULTS: This study included 215 patients, including 22 patients with MCTD. Machine learning models, constructed to classify SLE, IIM, and SSc patients based on immunophenotyping, were applied to MCTD patients, resulting in 16 classified as SLE-immunophenotype and 6 as non-SLE-immunophenotype. Among MCTD patients, patients with the SLE-immunophenotype had higher proportions of Th1 cells [2.85% (interquartile range (IQR) 1.54-3.91) vs 1.33% (IQR 0.99-1.74) p= 0.027] and plasmablasts [6.35% (IQR 4.17-17.49) vs 2.00% (IQR 1.20-2.80) p= 0.010]. Notably, the number of SLE-related symptoms was higher in patients with the SLE-immunophenotype [2.0 (IQR 1.0-2.0) vs 1.0 (IQR1.0-1.0) p= 0.038]. Moreover, GSVA scores of interferon-α and -γ responses were significantly higher in patients with the SLE-immunophenotype in central memory CD8+ T cells, while hedgehog signalling was higher in non-SLE-immunophenotype patients in 5 cell subsets. CONCLUSION: This study describes the stratification of MCTD patients based on immunophenotyping, suggesting the presence of distinct immunological processes behind the clinical subtypes of MCTD.

Title: Sarcopenia assessed by DXA and hand-grip dynamometer: a potential marker of damage, disability and myokines imbalance in inflammatory myopathies.

OBJECTIVES: To assess the ability of dual-energy X-ray absorptiometry (DXA) and hand-grip dynamometer to measure damage in inflammatory myopathies (IM). METHODS: . Forty adult IM patients with a disease duration ≥12 months, low or no disease activity for ≥6 months, were prospectively enrolled. Thirty healthy age and sex-matched volunteers were enrolled as controls. Whole-body DXA and hand-grip dynamometer were used to measure muscle mass, grip strength and diagnose sarcopenia (EWGSOP2 criteria). Relationships between the results of strength in 12 muscles, functional tests, patient-reported disability, IMACS damage score, and history of the disease were assessed. The serum levels of potential molecular actors of the damage were measured. RESULTS: DXA and grip strength measurements took ≤20 min. Both muscle mass and grip strength were decreased in IM patients vs volunteers (-10% and -30% respectively) with a dispersion that varied widely (IQR -24.3% to + 7.8% and -51.3% to -18.9% respectively). Muscle mass and grip strength were non-redundantly correlated (r up to 0.6, p= 0.0001) with strength in 14 muscles (manual muscle test and hand-held dynamometer), functions (of limbs, respiratory and deglutition muscles), patient-reported disability, damage (extension and severity in muscular and extra-muscular domains), and blood-levels of several myokines. Seven IM patients (17.5%) were sarcopenic. They had the worst damage, functions impairment, disability and history of severe myopathy. Decreased irisin and osteonectin levels were associated with sarcopenia (AUC 0.71 and 0.80, respectively). CONCLUSION: DXA and hand-grip dynamometer are useful tools to assess damage in IM. Irisin and osteonectin may play a role in IM damage pathogenesis.

Inflammatory Myopathy: When Electromyography and Autoantibodies Don't Help the Diagnosis.

Inflammatory myopathies (IM) are the most treatable myopathies. Necrotizing autoimmune myositis is a distinct clinicopathologic entity that starts either acutely or subacutely. Autoimmunity is essencial in the pathogenesis of myositis and autoantibodies may be present in more than 50% of patients. We present the case of a 73-year-old man with elevated levels of CK and aldolase, and proximal symmetric muscle weakness and weight loss. The etiological investigation revealed, via muscle biopsy, a necrotizing autoimmune myositis, even though the majority of usual autoantibodies and electromyography were negative. The case demonstrates the importance of combining the patient's symptoms, neurological examination, and analytical changes to corroborate the suspicion of myopathy.