Myositis Patients Research Articles

Deficiency of muscle-generated brain-derived neurotrophic factor causes inflammatory myopathy through reactive oxygen species-mediated necroptosis and pyroptosis

Idiopathic inflammatory myopathy (commonly known as myositis) is a group of immune-related diseases characterized by muscle damage, weakness, and fatigue with unknown causes. Although overactivated innate immunity is a widely believed cause of myositis onset, the mechanism that provokes and maintains a high immune response in myositis patients is still unclear. This study aims to test if brain-derived neurotrophic factor (BDNF) deficiency per se is sufficient to cause myositis and determine its underlying mechanism. We found that ablating BDNF production in skeletal muscle is sufficient to trigger myositis development in mice. Muscle-specific Bdnf knockout (MBKO) mice displayed extensive myocyte necrosis, mononuclear cell infiltration, and myophagocytosis. In association with these damages, elevated production of pro-inflammatory cytokines such as interleukin (IL) 23, IL-1β, IL-18, and tumor necrosis factor α (TNFα) was found in the muscle of MBKO mice. Disruption of sarcolemma integrity was also detected in MBKO mice, which is a result of necroptosis executioner Mixed lineage kinase domain-like protein (MLKL) and pyroptosis executioner Gasdermin D (GSDMD) activation. Mechanistically, diminishing BDNF synthesis in myotubes enhances the accumulation of mitochondrial reactive oxygen species (mtROS), which sensitizes the cells towards TNFα-induced receptor-interacting protein kinase (RIPs) activation and promotes the formation of NLR family pyrin domain containing 3 (NLRP3)-containing inflammasome. BDNF deficiency-induced cell death could be alleviated by scavenging mtROS, suppressing the activity of GSDMD, or inhibiting receptor-interacting kinase 3 (RIP3). Similarly, supplementation of BDNF mimetics, suppression of RIP3 activity, increasing the intramyocellular antioxidant, or enhancing mitophagy ameliorated the myopathies of MBKO mice and improved their muscle strength. Together, our study demonstrates that insufficient BDNF production in mouse muscle causes the development of pathological features of myositis via enhancing oxidative stress, necroptosis, and pyroptosis in myofibers.

Anti-Sp4 and Anti-CCAR1 autoantibodies in UK vs. US patients with adult and juvenile-onset anti-TIF1ƴ-positive myositis.

Anti-TIF1γ autoantibodies are associated with malignancy in adult-onset idiopathic inflammatory myopathy (IIM) and this risk is attenuated if patients are also positive for anti-specificity protein 4 (Sp4) or anti-cell division cycle apoptosis regulator protein 1 (CCAR1). In anti-TIF1γ positive US dermatomyositis (DM) patients, anti-Sp4 and anti-CCAR1 autoantibody frequencies are reported as 32% and 43% in adults and 9% and 19% in juveniles, respectively. This study aims to identify the frequency of anti-Sp4 and anti-CCAR1 in adult and juvenile UK anti-TIF1ƴ-positive myositis populations and report clinical associations. Serum samples from 51 UK participants with adult-onset IIM and 55 UK participants with JDM, all anti-TIF1γ autoantibody positive, and 24 healthy control samples were screened for anti-Sp4 and anti-CCAR1 autoantibodies by ELISA. In UK adult anti-TIF1γ positive IIM patients, anti-Sp4 and anti-CCAR1 frequencies were 4% (2/51) and 16% (8/51). Both adult patients with anti-Sp4 were also positive for anti-CCAR1. In UK juveniles, anti-Sp4 was not detected and 16% (7/55) had anti-CCAR1 autoantibodies. Nineteen (37%) anti-TIF1γ positive UK adult myositis patients had cancer; neither of the two patients with anti-Sp4 autoantibodies and 25% (2/8) of anti-CCAR1 autoantibody-positive patients had cancer. No anti-Sp4 or anti-CCAR1 clinical associations were identified. Anti-Sp4 and anti-CCAR1 autoantibodies are less common in the adult UK anti-TIF1ƴ-positive myositis population compared with published US data, limiting their use as biomarkers for cancer risk. In patients with juvenile onset disease, anti-Sp4 is less frequent in UK patients compared with the US, but the prevalence of anti-CCAR1 autoantibodies is similar.

Effectiveness of a psychoeducational intervention on myositis patients’ quality of life and well-being: a randomized controlled trial

BackgroundMyositis is a rare disease associated with impaired health-related quality of life. A study evaluating the effectiveness of an intervention to improve the quality of life and well-being of myositis patients is presented.MethodsAll myositis patients in a health district were contacted. Thirty-four eligible patients were randomly assigned to the experimental (n = 17) or control (n = 17) group. A psychoeducational intervention of 5 100-min sessions focusing on the disease as related to daily life was conducted only in experimental patients. Several reliable tools to measure quality of life and well-being were administered twice, before and after the intervention, to both groups.ResultsIn the experimental group, post-test scores were higher than pre-test in quality of life, well-being, and self-efficacy to manage the disease. Improvements were more evident in the experimental group than controls in 70% of the variables studied. Specifically, sedentariness decreased and satisfaction with social relationships increased in the post-test evaluation to a greater degree in the experimental group than in controls.ConclusionsThis randomized controlled trial on a representative sample of myositis patients in an extensive population provides evidence indicating the effectiveness of a psychoeducational intervention for improving HRQoL, well-being, and self-efficacy to manage the disease.Trial registration: NCT06300983.

Pathological autoantibody internalisation in myositis

ObjectivesAutoantibodies targeting intracellular proteins are common in various autoimmune diseases. In the context of myositis, the pathologic significance of these autoantibodies has been questioned due to the assumption that autoantibodies...

Increased Cytokine Levels in Seronegative Myositis: Potential Th17 Immune Response Implications

Th17 cells are known for producing IL-17 and their role in the pathogenesis of various autoimmune diseases, including myositis. Likewise, the participation of the IL-23/IL-17 pathway in autoimmunity has been confirmed. In this study, we aimed to evaluate the behavior of cytokines in myositis, focusing on the autoantibodies profile and the myositis core set measures. Twenty-five myositis patients were enrolled in this cross-sectional study. An expert rheumatologist evaluated the myositis core set measures. Serum levels of cytokines and chemokines were quantified using the LEGENDplex Multi-Analyte Flow Assay Kit from BioLegend. The autoantibodies detection was carried out using the line-blot assay kit Euroline: Autoimmune Inflammatory Myopathies from EUROIMMUN. We found higher serum levels of IL-33, CXCL8, IL-6, IL-23, and IL-12p70 in seronegative patients. A multiple linear regression analysis revealed that MYOACT scores could be predicted by the increment of IL-23 and the decrement of CCL2, IL-10, and CXCL8 serum levels. These findings suggest that the immune response in seronegative myositis patients exhibits an IL-23-driven Th17 immune response. The relevance of this discovery lies in its potential therapeutic implications. Insights into the IL-23-driven Th17 immune response in seronegative patients highlight the potential for targeted therapies aimed at modulating Th17 activity.

One-year survival benefit of plasma exchange in idiopathic inflammatory myositis patients with progressive interstitial lung disease-a systemic review and meta-analysis

ObjectivesThis study aimed to systematically evaluate the efficacy of plasma exchange (PLEX) in patients with idiopathic inflammatory myositis (IIM) complicated by interstitial lung disease (ILD). MethodWe conducted a comprehensive literature search in Medline and EMBASE from their inception to August 2023, focusing on randomized controlled trials, cohort studies, and case-control studies involving IIM patients with ILD treated with PLEX compared to those treated with standard therapies. The primary outcome was the one-year survival rate. All the statistical analyses were performed using RevMan version 4.12.0. ResultsOut of 438 retrieved studies, 16 were selected for full-text review. Six cohort studies involving 148 patients with anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis or antisynthetase syndrome-related dermatomyositis with rapidly progressive ILD refractory to standard treatments (including glucocorticoids, immunosuppressive agents, or intravenous immunoglobulin) met the inclusion criteria. Patients receiving PLEX in addition to other therapies demonstrated a greater one-year survival rate (relative risk [RR] 1.59, 95 % CI 0.96–2.65, I2 52 %) than did patients in the non-PLEX group. Significance was reached in a sensitivity analysis after excluding one outlier (RR 1.71, 95 % confidence intervals [CI] 1.30–2.25; I2 0 %). Additionally, there was a trend suggesting that PLEX improved lung function, radiographic outcomes, and key serum biomarkers, such as Krebs von den Lungen-6 and ferritin. Funnel plot asymmetry suggested publication bias due to the lack of reporting of negative trials. All studies had a low risk of bias. ConclusionsAs an adjunctive therapy, PLEX improved one-year survival in IIM patients with rapidly progressive ILD who were unresponsive to standard treatments.

217P Comparing IBMFRS and sIFA as progression indicators in inclusion body myositis patients from the INSPIRE-IBM trial

217P Comparing IBMFRS and sIFA as progression indicators in inclusion body myositis patients from the INSPIRE-IBM trial

555P Assessment of IBM-FRS total score and specific domains in a large cohort of inclusion body myositis patients

555P Assessment of IBM-FRS total score and specific domains in a large cohort of inclusion body myositis patients

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

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. "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. 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). 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.

Prevalence of urinary and bowel incontinence among individuals with myositis: A cross-sectional study

Background:No evidenced link exists between myositis and incontinence, however myositis patients identify incontinence as an issue. This research was initiated in response to advocacy by consumers to investigate this topic. Objective:The aim of this research was to explore the prevalence of urinary incontinence and bowel incontinence in the Australian myositis population, compared to an age-matched general Australian population. Methods:An online survey with validated questionnaires measured urinary and bowel incontinence and physical function amongst individuals with myositis. Recruitment was via email in collaboration with the Myositis Association of Australia. Published Australian general population data was used as the comparison group. Results:Results revealed urinary incontinence and bowel incontinence prevalence was significantly higher in the myositis population compared to the Australian population. Conclusion:This is the first known study to explore the prevalence of urinary and bowel incontinence in a Myositis population. This consumer-driven study confirmed anecdotal reporting of increased prevalence of urinary and bowel incontinence within the myositis population. The study also evidences the critical role of consumers in better understanding complex conditions and their impact.

Inter-alpha-trypsin inhibitor heavy chain H3 is a potential biomarker for disease activity in myasthenia gravis

Myasthenia gravis is a chronic antibody-mediated autoimmune disease disrupting neuromuscular synaptic transmission. Informative biomarkers remain an unmet need to stratify patients with active disease requiring intensified monitoring and therapy; their identification is the primary objective of this study. We applied mass spectrometry-based proteomic serum profiling for biomarker discovery. We studied an exploration and a prospective validation cohort consisting of 114 and 140 anti-acetylcholine receptor antibody (AChR-Ab)-positive myasthenia gravis patients, respectively. For downstream analysis, we applied a machine learning approach. Protein expression levels were confirmed by ELISA and compared to other myasthenic cohorts, in addition to myositis and neuropathy patients. Anti-AChR-Ab levels were determined by a radio receptor assay. Immunohistochemistry and immunofluorescence of intercostal muscle biopsies were employed for validation in addition to interactome studies of inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3). Machine learning identified ITIH3 as potential serum biomarker reflective of disease activity. Serum levels correlated with disease activity scores in the exploration and validation cohort and were confirmed by ELISA. Lack of correlation between anti-AChR-Ab levels and clinical scores underlined the need for biomarkers. In a subgroup analysis, ITIH3 was indicative of treatment responses. Immunostaining of muscle specimens from these patients demonstrated ITIH3 localization at the neuromuscular endplates in myasthenia gravis but not in controls, thus providing a structural equivalent for our serological findings. Immunoprecipitation of ITIH3 and subsequent proteomics lead to identification of its interaction partners playing crucial roles in neuromuscular transmission. This study provides data on ITIH3 as a potential pathophysiological-relevant biomarker of disease activity in myasthenia gravis. Future studies are required to facilitate translation into clinical practice.

Eosinophilic granulomatosis with polyangiitis and its association with montelukast: a case-based review.

The association between the use of certain medications (including sulfonamides, hydralazine, and procainamide) and the occurrence of drug-induced lupus or hepatitis is well established. More recently, cases of immune-related adverse events ranging from inflammatory polyarthritis to necrotizing myositis in patients taking checkpoint inhibitors have been reported. However, data linking drugs to systemic vasculitis are scarce and at times debatable. Propylthiouracil, hydralazine, and minocycline have been associated with rare cases of ANCA-associated syndromes, including life-threatening pulmonary-renal syndromes and systemic polyarteritis nodosa-like diseases. Eosinophilic granulomatosis with polyangiitis (EGPA) has been reported in patients taking leukotriene inhibitors. Since the link between the use of leukotriene inhibitors and occurrence of EGPA remains highly controversial, we performed a literature review for cases of EGPA in patients taking montelukast without prior history of oral corticosteroid use. We found 24 cases, along with our own two cases described, making 26 cases in total. The mean age was 43 and a majority (18/26) were female. In majority of cases EGPA-like disease never relapsed after they were taken off leukotriene inhibitors suggesting a clear causal relationship between the use of these drugs and occurrence of eosinophil-rich systemic EGPA.

Polymyositis is a rare and favourable outcome subtype of idiopathic inflammatory myopathy in Chinese patients.

To investigate the prevalence and characteristics of typical polymyositis (PM) in Chinese patients with idiopathic inflammatory myopathy (IIM). Patients diagnosed with IIM according to the 2017 EULAR/ACR criteria were included. Serological aspects including myositis-specific antibodies (MSA) and pathological data were re-evaluated. The diagnosis of typical PM was strictly done using the pathological criteria, while excluding other IIM subtypes such as dermatomyositis (DM), immune-mediated necrotising myopathies (IMNM), anti-synthetase syndrome (ASS), and sporadic inclusion body myositis (sIBM), based on their respective diagnostic criteria. A total of 544 IIM patients with muscle biopsy were involved, and 129 of them were diagnosed with initial PM according to the 2017 EULAR/ACR criteria. Only 6 (1.1%, 6/544) patients met the strict definition of typical PM after re-evaluation. Patients with typical PM were MSA-negative (100% vs. 35.7%, p=0.003) and had CD8+ T cells surrounding or invading non-necrotic muscle fibres in muscle biopsies (100% vs. 7.8%, p<0.001) compared to the initially diagnosed PM patients. All typical PM patients achieved clinical remission at the second-year follow-up. Typical PM patients had a favourable prognosis compared to MSA-negative IMNM and unspecific myositis patients. Strictly defined typical PM is a rare clinical subtype in Chinese IIM patients. Typical PM patients with classical pathology were MSA-negative and responded well to treatment and had a favourable prognosis. It is crucial for clinicians to combine clinical, serological, and pathological features to properly distinguish PM from other IIM subtypes.

Neurological autoimmunity in melanoma patients: a comparison between those exposed and non-exposed to immune checkpoint inhibitors.

The clinical spectrum of melanoma-associated neurological autoimmunity, whether melanoma-associated paraneoplastic neurological syndromes (PNS) or induced by immune checkpoint inhibitors (ICI), is not well characterized. We aim to describe the clinical spectrum of melanoma-associated neurological autoimmunity. A systematic review of the literature combined with patients from French databases of paraneoplastic neurological syndromes was conducted. All melanoma patients with a possible immune-mediated neurologic syndrome were included and classified according to whether they had previously been exposed to ICI (ICI-neurotoxicity) or not (ICI-naïve) at first neurological symptoms. Seventy ICI-naïve (literature: n = 61) and 241 ICI-neurotoxicity patients (literature: n = 180) were identified. Neuromuscular manifestations predominated in both groups, but peripheral neuropathies were more frequent in ICI-neurotoxicity patients (39.4% vs 21.4%, p = 0.005) whereas myositis was more frequent in ICI-naïve patients (42.9% vs 18.7%, p < 0.001). ICI-naïve patients had also more frequent central nervous system (CNS) involvement (35.7% vs 23.7%, p = 0.045), classical paraneoplastic syndrome (25.7% vs 5.8%, p < 0.001), and more frequently positive for anti-neuron antibodies (24/32, 75.0% vs 38/90, 42.2%, p = 0.001). Although more ICI-neurotoxicity patients died during the acute phase (22/202, 10.9% vs 1/51, 2.0%, p = 0.047), mostly myositis patients (14/22, 63.6%), mortality during follow-up was higher in ICI-naïve patients (58.5% vs 29.8%, p < 0.001). There was no significant difference in the frequency of life independence (mRS ≤ 2) in the surviving patients in both groups (95.5% vs 91.0%, p = 0.437). Melanoma-associated PNS appear remarkably rare. The clinical similarities observed in neurological autoimmunity between ICI-treated and ICI-naïve patients, characterized predominantly by demyelinating polyradiculoneuropathy and myositis, suggest a potential prior immunization against melanoma antigens contributing to ICI-related neurotoxicity.

A patient centered assessment of the 2016 ACR-EULAR Myositis Response Criteria: evaluating the meaningfulness of response.

The ACR-EULAR Myositis Response Criteria (Total Improvement Score [TIS]) is a composite measure calculated using changes in myositis core set measures. It is unclear if achieving improvement per TIS reflects improvement in any symptoms of myositis patients. In this study, we examined the association between achieving TIS improvement and patient-centered outcome measures (PCOMs). Adults with myositis were enrolled in a prospective study with baseline and 6-month visits. Six core set measures were collected at each visit along with the following PCOMs: Fatigue (visual analogue scale [VAS] and short form 36 [SF36]), pain (VAS, SF36), health-related quality of life (SF-36), physical function (PROMIS-physical function, SF36, sit-to-stand, timed up-and-go, and six-min walk) and physical activity (actigraphy). Mann-Whitney U was used to compare PCOMs between improvement groups. Spearman correlation and regression models were used for correlation and association between TIS and PCOMs, respectively. Of 50 patients (six polymyositis, 24 dermatomyositis, 9 necrotizing myopathy, 11 anti-synthetase syndrome) enrolled (mean age: 52, 60% female), 21 patients satisfied the TIS improvement criteria at 6-months. PCOMs including fatigue, pain, quality of life, physical activity and physical function demonstrated significantly greater improvement in patients who had minimal TIS improvement compared with those with no improvement. Greater PCOM improvements were seen with moderate-major TIS improvement. TIS correlated moderately-strongly with most PCOMs. Achieving improvement criteria was accompanied by significant clinical improvements in fatigue, pain, health-related quality of life, physical function, and physical activity. These results support the use of TIS as a clinically meaningful metric of improvement.

Pain is Common in Myositis and Associated with Disease Activity.

Understanding pain in myositis remains challenging. This study aimed to assess patient-reported pain and its correlation with myositis core set measures (CSMs), patient-reported outcomes (PROs), and functional measures. Fifty subjects underwent baseline, 3-month, and 6-month assessments, evaluating myositis CSMs, functional measures, and patient-reported outcomes. Pain was measured using three methods: (1) a 10-cm Visual Analogue Scale (VAS), (2) pain score from the HAQ-DI, and (3) SF-36 (Short Form survey) pain questions. Correlations between disease activity measures and pain were examined at baseline, and changes in both were assessed at 6 months, along with longitudinal change of pain. The change in pain was also correlated with the published 2016 ACR/EULAR myositis response criteria, physician/patient's assessment of change. Nearly half of patients (45%) reported moderate to severe pain in all 3 pain scales, with higher severity of pain in PM/NM subset. At baseline, pain severity showed a strong correlation with most CSMs, PROs and functional outcomes in all the 3 pain scales and similar trends were noted for change in pain at the 6 months. On longitudinal analysis, the physical function scores and fatigue showed strong correlation with pain. Pain improved in myositis patients with improvement in disease activity over time. Pain is common in myositis and is associated with multiple measures of disease activity, PROs, and functional outcomes in myositis. Most importantly pain improves with improvement in disease activity. SF-36 pain questions have good psychometric properties.

Patient reported outcome for physical function in idiopathic inflammatory myopathy.

There is an unmet need to develop patient-reported outcomes (PRO) measures for Idiopathic Inflammatory Myopathies (IIM). To investigate the feasibility, compliance, and psychometric properties of NIH's Patient-Reported Outcomes Measurement Information System (PROMIS) physical function-20 (PF-20) in a large U.S. IIM population. "Myositis Patient Centered Tele-Research" (My PACER) is a multicentre prospective observational study of IIM patients, competitively recruited through traditional in-person clinic visits (Center-Based Cohort [CBC]), and remotely using smartphone and web-based technology (Tele-Research Cohort [TRC]). The CBC was further randomly divided (1:1 ratio) into a traditional local sub-cohort, and a remote sub-cohort. Data collected included PRO and other patient self-assessments monthly for 6 months. Clinician-reported outcomes were obtained at baseline and 6 months. 120 IIM patients were enrolled (82 TRC/38 CBC, mean age 55 ± 13.4, 75% females, 81% Caucasians), with similar demographics and mean PROMIS PF-20 score between cohorts. The PROMIS PF-20 score was not associated with age, sex or race. The compliance and completion rates were similar between TRC and CBC as well as sub-cohorts. PROMIS PF-20 showed strong test-retest reliability at 1 month. PROMIS PF-20 was significantly associated with all core set measures except extra-muscular global and CK, as well as with most of symptoms, function and physical activity measures. PROMIS PF-20 illustrated concordant change with myositis response criteria and patient assessment, with a large effect size. PROMIS PF-20 demonstrates favorable psychometric properties including reliability, validity and responsiveness in a large cohort of myositis patients, with similar adherence in local or remotely enrolled patients.

Predictors of myositis in mixed connective tissue disease: A multicentre retrospective study.

We aimed to identify clinical and serological predictors of myositis in mixed connective tissue disease (MCTD). We performed a nationwide, retrospective, multicentre study including adult-onset MCTD patients fulfilling at least one of the following diagnostic criteria: Sharp's, Kasukawa, Alarcón-Segovia, or Kahn's. Univariate analysis was performed using Chi-square, Fisher exact, Student's t or Mann-Whitney U tests, as appropriate. Multivariate analysis was performed using binary logistic regression. Ninety-eight patients were included. Myositis was observed in 43.9% of patients, of whom 60.5% had myositis at disease onset. Proximal muscle weakness was described in 30 patients with muscle involvement (70%). Gastrointestinal involvement was identified in 28% and respiratory involvement in 29% of myositis patients. In the same subgroup of patients, 41.7% had a myopathic pattern on electromyography, and 47.1% had histological myositis features in the muscle biopsy. Fever (OR=6.96, p=0.022) was an independent predictor of myositis, regardless of sex, age at diagnosis, ancestry, and respiratory involvement. African ancestry (OR=8.39, p=0.019), leukopenia at the disease onset (OR 6.24, p=0.021), and younger age at diagnosis (OR=1.07/year, p=0.035) were identified as independent predictors of myositis at disease onset, regardless of sex and scleroderma pattern in capillaroscopy. Myositis is a common manifestation of MCTD, even at the disease onset. African ancestry, leukopenia at the disease onset, younger age at diagnosis, and fever should prompt a thorough evaluation for myositis.

Predictors of myositis in mixed connective tissue disease: A multicentre retrospective study.

We aimed to identify clinical and serological predictors of myositis in mixed connective tissue disease (MCTD). We performed a nationwide, retrospective, multicentre study including adult-onset MCTD patients fulfilling at least one of the following diagnostic criteria: Sharp's, Kasukawa, Alarcón-Segovia, or Kahn's. Univariate analysis was performed using Chi-square, Fisher exact, Student's t or Mann-Whitney U tests, as appropriate. Multivariate analysis was performed using binary logistic regression. Ninety-eight patients were included. Myositis was observed in 43.9% of patients, of whom 60.5% had myositis at disease onset. Proximal muscle weakness was described in 30 patients with muscle involvement (70%). Gastrointestinal involvement was identified in 28% and respiratory involvement in 29% of myositis patients. In the same subgroup of patients, 41.7% had a myopathic pattern on electromyography, and 47.1% had histological myositis features in the muscle biopsy. Fever (OR=6.96, p=0.022) was an independent predictor of myositis, regardless of sex, age at diagnosis, ancestry, and respiratory involvement. African ancestry (OR=8.39, p=0.019), leukopenia at the disease onset (OR 6.24, p=0.021), and younger age at diagnosis (OR=1.07/year, p=0.035) were identified as independent predictors of myositis at disease onset, regardless of sex and scleroderma pattern in capillaroscopy. Myositis is a common manifestation of MCTD, even at the disease onset. African ancestry, leukopenia at the disease onset, younger age at diagnosis, and fever should prompt a thorough evaluation for myositis.

Comparing the Efficacy of Conventional Immunosuppression and Rituximab in Anti-SRP Myositis: Insights from a Tertiary Care Centre Experience

Background Consensus on anti-SRP myositis shows that early rituximab (RTX) is favoured over conventional immunosuppression (cIS), but the data is derived from case series without comparative studies. This study aims to a) explore poor prognostic features, and b) assess and compare the efficacy and safety of RTX with cIS in individuals with anti-SRP myositis. Methods This is an observational study in a tertiary care centre in India. Data was obtained from a prospectively maintained database comprising consecutive adult (&gt; 16 years) patients diagnosed myositis. A total of 1033 myositis patients were screened from January 2019 to January 2024. Fourty IIM patients with confirmed anti-SRP positivity fulfilling inclusion criteria with more than 3 months of follow-up were selected for the study and response analysis. Details were obtained at baseline, 3 months, and 6 months, as well as subsequent follow-up. Treatment response was categorised as improved, worsening, or stable disease. The characteristics of patients between “RTX” and “cIS” groups were compared using t-test and Chi-square test as appropriate. Survival analysis curves were plotted for improvement and death between the two groups. Results The mean age of onset of anti-SRP myositis was 44.2 (SD13.14) years; 71.4% of patients were female. Baseline characteristics are described in Table 1. For response analysis, 35 patients into two groups: RTX and cIS. Fifteen (42.85%) patients were given RTX. While 20 received cIS (57.14%, 12/20 (60%) received mycophenolate mofetil, 8/20 (40%) received methotrexate, and 5/20 (25%) received cyclophosphamide). The median follow-up was 12 (IQR 6-24) months. There was no significant difference in improvement between RTX and cIS groups (11/15 (73.3%) RTX group and 9/20(45%) cIS group (p-value -0.465)). Time to improvement was also not significantly different (Figure 1). However, the Mean change in MMT8 from baseline to 6 months was more in the RTX group (p-value 0.001). The average monthly steroid dose significantly decreased six months after RTX with a p-value of 0.001(1600.13mg (SD 271.53) in RTX versus 826.6 mg (SD 370.35) in cIS). Mortality rates stood at 1/15 (6.67%) for RTX and 4/20 (20%) for cIS. Unravelling predictors of mortality revealed significant associations with cardiac involvement (p-value - 0.02) and severe non-ambulant muscle weakness (p-value - 0.03). Conclusions Both cIS and RTX are effective and safe in anti-SRP myositis for muscle affection and time for response. Cardiac involvement and severe muscle weakness are associated with mortality. RTX use decreases steroid requirement in anti-SRP myositis.