Antisynthetase Syndrome Research Articles

Overlap between Sjogren's syndrome and anti-synthetase syndrome: association or coincidence?

Overlap between Sjogren's syndrome and anti-synthetase syndrome: association or coincidence?

Pathophysiological Mechanisms and Treatment of Dermatomyositis and Immune Mediated Necrotizing Myopathies: A Focused Review.

Idiopathic inflammatory myopathies (IIM), collectively known as myositis, are a composite group of rare autoimmune diseases affecting mostly skeletal muscle, although other organs or tissues may also be involved. The main clinical feature of myositis is subacute, progressive, symmetrical muscle weakness in the proximal arms and legs, whereas subtypes of myositis may also present with extramuscular features, such as skin involvement, arthritis or interstitial lung disease (ILD). Established subgroups of IIM include dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), overlap myositis (OM) and inclusion body myositis (IBM). Although these subgroups have overlapping clinical features, the widespread variation in the clinical manifestations of IIM suggests different pathophysiological mechanisms. Various components of the immune system are known to be important immunopathogenic pathways in IIM, although the exact pathophysiological mechanisms causing the muscle damage remain unknown. Current treatment, which consists of glucocorticoids and other immunosuppressive or immunomodulating agents, often fails to achieve a sustained beneficial response and is associated with various adverse effects. New therapeutic targets have been identified that may improve outcomes in patients with IIM. A better understanding of the overlapping and diverging pathophysiological mechanisms of the major subgroups of myositis is needed to optimize treatment. The aim of this review is to report on recent advancements regarding DM and IMNM.

Clinical Features of Anti-Synthetase Syndrome Associated with Prognosis in Patients with Dermatomyositis and Polymyositis.

We evaluated whether the clinical features of anti-synthetase syndrome (ASA)—myositis, fever, arthritis, mechanic’s hand, Raynaud’s phenomenon and interstitial lung disease—are relevant to prognosis in patients with dermatomyositis/polymyositis (DM/PM). A retrospective analysis was performed to identify patients diagnosed with DM/PM according to Bohan and Peter criteria. Clinical information, laboratory data and the presence of ASA clinical features at disease diagnosis were searched, and the outcomes of all-cause mortality, intensive care unit admission and disease remission at 1 year were assessed. Among the 86 patients included, fever (36.0%) and interstitial lung disease (26.7%) were the most common ASA clinical features. During the follow-up, 12 patients experienced death, and 7 of the 12 deaths (58.3%) occurred within 3 months of DM/PM diagnosis. Mortality was more frequently observed in those presenting with fever than in those without (25.8% versus 7.3%, p = 0.024). Multivariable Cox proportional analysis revealed that male sex (hazard ratio [HR] 5.53, 95% confidence interval [CI] 1.65, 18.49, p < 0.01) and fever (HR 4.20, 95% CI 1.26, 14.01, p = 0.02) independently predicted mortality. The clinical impact of fever was consistent in both sexes. Fever could be a warning signal heralding the poor outcome of mortality in patients with DM/PM, especially in early disease phases.

Overlapping rheumatoid arthritis and antisynthetase syndrome with secondary Sj\xf6gren\u2019s syndrome: a case report\xa0and review of the\xa0literature

BackgroundOverlap syndromes account for about 25% of autoimmune diseases. They are many possible combinations of known autoimmune diseases increasingly diagnosed with the identification of of a large number of autoantibodies. In this case report, we present a patient with rare overlapping rheumatoid arthritis–antisynthetase syndrome with associated secondary Sjögren’s syndrome atypically presenting without interstitial lung disease.Case presentationA 52-year-old Sinhalese female, a known patient with type 2 diabetes mellitus, presented with a history of symmetrical inflammatory-type polyarthritis with significant morning stiffness, proximal muscle weakness, pain, and roughening of the fingertips with associated sicca symptoms of 5 months duration. Examination revealed features of active joint inflammation, mechanic’s hand, xerostomia, and left-sided breast lump. Investigations confirmed the presence of rheumatoid arthritis with strongly positive rheumatoid factor (202 U/ml) and anti-cyclic citrullinated peptide antibody (717 U/ml). Antisynthetase syndrome was also diagnosed with borderline-positive anti-aminoacyl-tRNA antibodies but without interstitial lung disease. Sjögren’s syndrome was confirmed by the clinical history and histology and considered a secondary disorder. As her breast lump proved to be benign, no further interventions were done. She was started on sulfasalazine and methotrexate with steroid bridging therapy and achieved remission and had good control of the disease without any joint deformity or flare-up on 6-month clinic follow-up.DiscussionOverlapping rheumatoid arthritis–antisynthetase syndrome is a very rare disease with disabling complications. Early identification of the atypical presentations of the overlap syndromes, by thorough investigations, helps physicians to prescribe proper disease-modifying antirheumatoid drugs and biological drugs. It also helps predict the prognosis of the patients before they develop complications.

Echocardiographic characteristics of patients with antisynthetase syndrome.

Right ventricular (RV) dysfunction and pulmonary hypertension (PH) occurs in approximately one‐third of patients with interstitial lung disease (ILD) and is associated with reduced 6‐minute walk distance (6MWD), and increased hospitalizations and mortality. Although the impact of RV dysfunction and PH has been well described in several types of ILD, data is scarce on antisynthetase syndrome. Therefore, we sought to examine the presence of RV dysfunction and PH in patients with antisynthetase syndrome and the impact on clinical outcomes. We conducted a retrospective study of patients with antisynthetase syndrome. Seventy‐five subjects were identified. Fifty‐one (68%) subjects had echocardiographic data. Patients were grouped into those with normal fractional area change (FAC) ≥ 35% and reduced FAC < 35%. Clinical, echocardiographic, and right heart catheterization data were compared between the two groups. Subjects with FAC < 35% had lower diffusion capacity of the lung for carbon monoxide (29% vs. 47%, p = 0.004), fibrotic features on computed tomography of the chest (79% vs. 33%, p = 0.005), larger RV diameter (5.4 vs. 3.9 cm, p < 0.001), higher right atrial pressures (8 vs. 5 mmHg, p = 0.02), and required supplemental oxygen more frequently (100% vs. 44%, p < 0.001) compared to those with FAC ≥ 35%. We found no difference in 6MWD and hospitalizations between the two groups. The presence of RV dysfunction in antisynthetase syndrome may identify patients at risk of poor outcomes.

Anti‐Jo1 autoantibodies, from clinic to the bench

AbstractIntroductionIdiopathic inflammatory myopathies (IIM) also known as myositis, is a chronic autoimmune disease which affects muscles, skin, joints and lung. One of the most common autoantibodies with a prevalence of 25‐35%, is the anti‐Jo‐1 autoantibodies, targeting the histidyl‐transfer RNA synthetase (HisRS). These autoantibodies are strongly associated with a distinct clinical phenotype called anti‐synthetase syndrome (ASyS) that includes interstitial lung disease (ILD), myositis, arthritis and Raynaud's phenomenon. The mechanism of how autoantibodies are produced and how they contribute to disease pathogenesis is unclear.Areas CoveredIn this review we will discuss the clinical manifestations associated with Jo‐1 autoantibodies, and the association with clinical features. Moreover, we will also review the molecular characteristics of the antibodies and how they affect the cells of the immune system in order to understand possible disease mechanisms.

Clinical characteristics of anti-isoleucyl-tRNA synthetase antibody associated syndrome and comparison with different patient cohorts.

This study aimed to analyse the clinical features of anti-isoleucyl-tRNA synthetase (OJ) antibodies in Chinese patients and to compare with previously published cohorts. We reviewed the clinical data of anti-OJ antibody positive patients, including their long-term follow-up. Anti-OJ antibodies were present in 10 of 1269 (0.8%) patients with idiopathic inflammatory myopathies (IIMs), and 10/320 (3.1%) patients with anti-synthetase syndrome (ASS). Of the anti-OJ antibody-positive patients, 90% had interstitial lung disease (ILD), of whom three (30%) developed rapidly progressive ILD (RP-ILD). Half (50%) of the patients were febrile and developed myocardial involvement; 40% of patients experienced myositis, mechanic's hands and arthritis. Compared to the anti-Jo-1 group, the levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in the anti-OJ antibody-positive group were higher (p<0.05). From a review of the literature regarding the clinical features of anti-OJ, fever was more common in the eastern cohort (41.7% vs. 8.3%, p=0.002), whereas patients in western countries were more likely to develop arthritis (20.9% vs. 58.1%, p=0.001). With complete follow-up of the present cohort, 80% improved with treatment, including one patient who underwent lung transplant. The anti-OJ antibody occurred infrequently in Chinese patients, ILD was the major clinical feature, but myocardial injury was also a prominent associated complication. Anti-OJ positive patients were responsive to treatment.

Correction to: Increased incidence of anti-synthetase syndrome during COVID-19 pandemic.

Correction to: Increased incidence of anti-synthetase syndrome during COVID-19 pandemic.

Identification of Similarities Between Skin Lesions in Patients With Antisynthetase Syndrome and Skin Lesions in Patients With Dermatomyositis by Highly Multiplexed Imaging Mass Cytometry.

Antisynthetase syndrome (ASyS) and dermatomyositis (DM) are autoimmune disorders that overlap clinically. Given the presence of DM-like skin lesions in ASyS patients, there is debate about whether ASyS is a distinct disease or a subclassification of DM. Recent studies identified differences in type I interferon (IFN) expression between ASyS and DM muscle and finger eruptions. This study was undertaken to elucidate similarities and differences in the pathogenesis of cutaneous disease in ASyS and DM at the single-cell level. Five ASyS patients and 7 DM patients were recruited from a prospectively collected database of well-characterized DM patients. ASyS patients were clinically confirmed as having ASyS according to the Connors et al criteria and the Solomon et al criteria and the presence of aminoacyl-transfer RNA synthetase antibodies. Immunophenotyping was conducted using immunofluorescence (IF) and imaging mass cytometry (IMC). IF staining for MxA and IFNβ expression revealed up-regulation of type I IFN in ASyS and DM samples compared to healthy control samples (P < 0.05). IMC showed similar numbers of macrophages, T cells, B cells, and dendritic cells in ASyS and DM samples, with no differences in counts (P > 0.05), but an increase in myeloid dendritic cell percentage in DM samples (P < 0.05). Key type I IFN, cytokine, and JAK/STAT pathways were similarly expressed in both ASyS and DM (P > 0.05). At the single-cell level, macrophages positive for phosphorylated stimulator of IFN genes in ASyS samples expressed increased levels of tumor necrosis factor, interluekin-17 (IL-17), and IFNβ (P < 0.001). IMC is a powerful tool that identifies a role for the type I IFN system in DM-like skin lesions in ASyS and DM with some differences at the cellular level, but overall significant overlap, supporting similar therapeutic decision making.

Different Multivariable Risk Factors for Rapid Progressive Interstitial Lung Disease in Anti-MDA5 Positive Dermatomyositis and Anti-Synthetase Syndrome.

BackgroundInterstitial lung disease (ILD) is frequently observed in anti-melanoma differentiation-associated protein 5 (MDA5) antibody positive dermatomyositis (DM) and anti-synthetase syndrome (ASS), where they often develop a rapidly progressive ILD (RP-ILD) leading to poor prognosis.ObjectiveThe aim of this study was to construct multivariable prediction risk factors for rapid progressive ILD (RP-ILD) in anti-MDA5 positive DM (MDA5+DM) and ASS.Methods333 idiopathic inflammatory myopathy (IIM) associated ILD patients were studied retrospectively. Risk factors for RP-ILD in MDA5+DM and ASS patients were identified by univariate and multivariable logistic regression analysis. The mortality was assessed using Kaplan-Meier analysis.ResultsRP-ILD was more prevalent in MDA5+DM patients than ASS patients. MDA5+DM patients with RP-ILD had significantly lower survival rates than those in ASS patients. The independent risk factors for RP-ILD in MDA5+DM patients were fever (OR 3.67, 95% CI:1.79-7.52), lymphopenia (OR 2.14, 95% CI:1.01-4.53), especially decreased levels of CD3+T cells (OR 2.56, 95% CI:1.17-5.61), decreased levels of CD3+CD4+ T cells (OR 2.80, 95% CI:1.37-5.73), CD3+CD8+T cells (OR 2.18, 95% CI:1.05-4.50), elevated CD5-CD19+ B cells (OR 3.17, 95% CI:1.41-7.13), elevated ALT (OR 2.36, 95% CI:1.15-4.81), high lactate dehydrogenase (LDH) (OR 3.08, 95% CI:1.52-6.27), hyper-ferritin (OR 4.97, 95% CI:1.97-12.50), elevated CEA (OR 2.28, 95% CI:1.13-4.59), and elevated CA153 (OR 3.31, 95% CI:1.50-7.27). While the independent risk factors for RP-ILD in ASS patients were elevated CEA (OR 5.25, 95% CI: 1.73-15.93), CA125 (OR 2.79, 95% CI: 1.10-7.11) and NSE (OR 4.86, 95% CI: 1.44-16.37). Importantly, serum ferritin>2200ng/ml predicted patient’s death within half a year in MDA5+DM patients with RP-ILD, but not in ASS patients.ConclusionsThere were significant different mortality and multivariable risk factors for RP-ILD in MDA5+DM patients and ASS patients. Potential clinical benefits of using these different risk factors deserve assessment of severity and prognosis in IIM patients.

Demographic, clinical, laboratory data, prognostic, and treatment features of patients with antisynthetase syndrome: An international, two-center cohort study.

To compare clinical, demographic, laboratory data, prognostic and treatment characteristics of patients with antisynthetase syndrome (ASSD) treated in two different centers of India and Brazil. This international, two-center, retro-prospective cohort study which was conducted at two tertiary rheumatology centers (one in Brazil and one in India) between January 2000 to January 2020 included a total of 115 patients with ASSD (21 males, 94 females; mean age; at disease diagnosis at 40.3; range, 18 to 80 years). Demographic, clinical and laboratory data of the patients were recorded. Clinical involvement was evaluated. Of the patients, 81 were Brazilians and 34 were of Indian origin. The Indian group exhibited a greater delay in diagnosis after the onset of symptoms compared to Brazilian patients (12 vs. 6 months, respectively; p=0.026). Brazilian patients exhibited a significantly higher prevalence of joint and lung involvement, mechanic's hands, and Raynaud's phenomenon. Anti-Jo-1 was the most common autoantibodies in both groups. Systemic arterial hypertension, followed by diabetes mellitus were the most prevalent comorbidities. Concerning previously used drugs, the Indian patients had a larger group of patients treated with antimalarials, whereas the Brazilian group used more azathioprine and intravenous immunoglobulin. A higher proportion of Indian patients was treated with one immunosuppressive drug (70.6%), while the Brazilian group were often treated using two immunosuppressive drugs (33%). Comparison between the severity and prognosis showed that Brazilian group had a higher number of relapses, and during follow-up, the global mortality rates were similar in both groups (6.2% for Brazilian vs. 8.8% for Indian). Brazilian and Indian patients with ASSD have comparable epidemiological characteristics such as age at the time of disease diagnosis, and sex distribution, and autoantibodies. Diagnostic delay is seen in Indian patients, and Brazilians exhibit a higher prevalence of joint and lung involvement, mechanic's hands, Raynaud's phenomenon with a higher number of relapses, although the mortality rate seems to be similar in both groups.

Longitudinal assessment of reactivity and affinity profile of anti-Jo1 autoantibodies to distinct HisRS domains and a splice variant in a cohort of patients with myositis and anti-synthetase syndrome

BackgroundTo address the reactivity and affinity against histidyl-transfer RNA synthetase (HisRS) autoantigen of anti-Jo1 autoantibodies from serum and bronchoalveolar lavage fluid (BALF) in patients with idiopathic inflammatory myopathies/anti-synthetase syndrome (IIM/ASSD). To investigate the associations between the reactivity profile and clinical data over time.MethodsSamples and clinical data were obtained from (i) 25 anti-Jo1+ patients (19 sera with 16 longitudinal samples and 6 BALF/matching sera at diagnosis), (ii) 29 anti-Jo1− patients (25 sera and 4 BALF/matching sera at diagnosis), and (iii) 27 age/gender-matched healthy controls (24 sera and 3 BALF/matching sera). Reactivity towards HisRS full-length (HisRS-FL), three HisRS domains (WHEP, antigen binding domain (ABD), and catalytic domain (CD)), and the HisRS splice variant (SV) was tested. Anti-Jo1 IgG reactivity was evaluated by ELISA and western blot using IgG purified from serum by affinity chromatography. In paired serum-BALF, anti-Jo1 IgG and IgA reactivity was analyzed by ELISA. Autoantibody affinity was measured by surface plasmon resonance using IgG purified from sera. Correlations between autoantibody reactivity and clinical data were evaluated at diagnosis and longitudinally.ResultsAnti-Jo1 IgG from serum and BALF bound HisRS-FL, WHEP, and SV with high reactivity at the time of diagnosis and recognized both conformation-dependent and conformation-independent HisRS epitopes. Anti-HisRS-FL IgG displayed high affinity early in the disease. At the time of IIM/ASSD diagnosis, the highest autoantibody levels against HisRS-FL were found in patients ever developing interstitial lung disease (ILD) and arthritis, but with less skin involvement. Moreover, the reactivity of anti-WHEP IgG in BALF correlated with poor pulmonary function.Levels of autoantibodies against HisRS-FL, HisRS domains, and HisRS splice variant generally decreased over time. With some exceptions, longitudinal anti-HisRS-FL antibody levels changed in line with ILD activity.ConclusionHigh levels and high-affinity anti-Jo1 autoantibodies towards HisRS-FL were found early in disease in sera and BALF. In combination with the correlation of anti-HisRS-FL antibody levels with ILD and ILD activity in longitudinal samples as well as of anti-WHEP IgG in BALF with poor pulmonary function, this supports the previously raised hypothesis that the lung might have a role in the immune reaction in anti-Jo1-positive patients.

Defining anti-synthetase syndrome: a systematic literature review.

Anti-synthetase syndrome (ASSD) is a heterogeneous autoimmune disease characterised by multi-system involvement with a wide variety of manifestations. Validated classification criteria are necessary to improve recognition and prevent misclassification, especially given the lack of reliable and standardised autoantibody testing. We systematically reviewed the literature to analyse proposed ASSD criteria, characteristics, and diagnostic performance. We searched PubMed and Embase databases (01/01/1984 to 06/11/2018) and the ACR and EULAR meeting abstracts (2017-2018). Sensitivities, specificities, positive, negative likelihood ratios and risk of bias were calculated for ASSD criteria and key variables reported in the literature. We performed meta-analysis when appropriate. We retrieved 4,358 studies. We found 85 proposed ASSD criteria from a total of 82 studies. All but one study included anti-synthetase autoantibody (ARS) positivity in the ASSD criteria. Most studies required only one ASSD feature plus anti-ARS to define ASSD (n=64, 78%), whereas 16 studies required more than one ASSD variable plus anti-ARS. The only criteria not including anti-ARS positivity required 5 ASSD clinical features. We found limited data and wide variability in the diagnostic performance of each variable and definition proposed in the literature. Given these limitations we only meta-analysed the performance of individual muscle biopsy and clinical variables in diagnosing ASSD, which performed poorly. The current ASSD criteria include a variety of serological, clinical, and histological features with wide variability amongst proposed definitions and the performance of these definitions has not been tested. This systematic literature review suggests the need for additional data and consensus-driven classification criteria for ASSD.

Single-Cell Transcriptomics Reveals Peripheral Immune Responses in Anti-Synthetase Syndrome-Associated Interstitial Lung Disease.

ObjectiveInterstitial lung diseases (ILDs) secondary to anti-synthetase syndrome (ASS) greatly influence the prognoses of patients with ASS. Here we aimed to investigate the peripheral immune responses to understand the pathogenesis of this condition.MethodsWe performed single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) from 5 patients with ASS-ILD and 3 healthy donors (HDs). Flow cytometry of PBMCs was performed to replenish the results of scRNA-seq.ResultsWe used scRNA-seq to depict a high-resolution visualization of cellular landscape in PBMCs from patients with ASS-ILD. Patients showed upregulated interferon responses among NK cells, monocytes, T cells, and B cells. And the ratio of effector memory CD8 T cells to naïve CD8 T cells was significantly higher in patients than that in HDs. Additionally, Th1, Th2, and Th17 cell differentiation signaling pathways were enriched in T cells. Flow cytometry analyses showed increased proportions of Th17 cells and Th2 cells, and decreased proportion of Th1 cells in patients with ASS-ILD when compared with HDs, evaluated by the expression patterns of chemokine receptors.ConclusionsThe scRNA-seq data analyses reveal that ASS-ILD is characterized by upregulated interferon responses, altered CD8 T cell homeostasis, and involvement of differentiation signaling pathways of CD4 T cells. The flow cytometry analyses show that the proportions of Th17 cells and Th2 cells are increased and the proportion of Th1 cells is decreased in patients with ASS-ILD. These findings may provide foundations of novel therapeutic targets for patients with this condition.

Isolated interstitial lung disease associated with anti-synthetase syndrome.

Isolated interstitial lung disease associated with anti-synthetase syndrome.

HP42: EMG is a potential biomarker for myositis in patients with antisynthetase syndrome without muscle symptoms

Anti-aminoacyl-tRNA synthetase (ARS) antibodies positive patients sometimes present interstitial lung disease (ILD) without muscle symptoms. We investigated needle electromyography (nEMG) to explore whether there are some myogenic changes or not in patients with antisynthetase syndrome without muscle symptoms. Method: We enrolled three patients who fulfilled anti ARS antibodies positive and ILD of the Connor's criteria for antisynthetase syndrome, and not fulfill the PM/DM criteria. We investigated the nEMG, and magnetic resonance imaging (MRI) of muscles to explore whether there are some myogenic changes or not. Serum creatine kinase (CK), manual muscle testing of 8 muscle groups (MMT8), Inclusion Body Myositis-Functional Rating Scale (IBM-FRS) were measured. This study was approved by the ethics committee of the Nara Medical University School of Medicine. Results: All subjects were females and their ages at the examination were 54 years old (P1), 44(P2) and 69(P3). P1 and P2 had already initiated oral steroid therapy. Although all three patients had no high serum CK level nor decline in IBM-FRS, nEMG revealed that abnormally short durations of the motor unit potential (MUP) patterns in the deltoid and biceps. P3 presented the same MUP pattern in vastus lateralis. MRI revealed inflammatory changes in P2 at left triceps and P3 at anterolateral femurs and posterolateral lower legs. Conclusion: nEMG is usually performed when patients exhibit muscle weakness, but this examination tool can be applicated to detect muscle damage in patients with anti-ARS antibody-associated ILD, prior to muscle weakness, myalgia, and declines in ADLs.

Endoplasmic Reticulum Stress Is Involved in Muscular Pathogenesis in Idiopathic Inflammatory Myopathies.

Objectives: Endoplasmic reticulum (ER) stress plays pivotal roles in the regulation of skeletal muscle damage and dysfunction in multiple disease conditions. We postulate the activation of ER stress in idiopathic inflammatory myopathies (IIM). Methods: Thirty-seven patients with immune-mediated necrotizing myopathy (IMNM), 21 patients with dermatomyositis (DM), 6 patients with anti-synthetase syndrome (ASS), and 10 controls were enrolled. The expression of ER stress-induced autophagy pathway was detected using histological sections, Western blot, and real-time quantitative Polymerase Chain Reaction. Results: ER stress-induced autophagy pathway was activated in biopsied muscle of patients with IMNM, DM, and ASS. The ER chaperone protein, glucose-regulated protein 78 (GRP78)/BiP expression in skeletal muscle correlated with autophagy, myofiber atrophy, myonecrosis, myoregeneration, and disease activity in IMNM. Conclusion: ER stress was involved in patients with IIM and correlates with disease activity in IMNM. ER stress response may be responsible for skeletal muscle damage and repair in IIM.

Muscle Transcriptomics Shows Overexpression of Cadherin 1 in Inclusion Body Myositis.

ObjectiveThis study aimed to elucidate the molecular features of inclusion body myositis (IBM).MethodsWe performed RNA sequencing analysis of muscle biopsy samples from 67 participants, consisting of 58 myositis patients with the pathological finding of CD8‐positive T cells invading non‐necrotic muscle fibers expressing major histocompatibility complex class I (43 IBM, 6 polymyositis, and 9 unclassifiable myositis), and 9 controls.ResultsCluster analysis, principal component analysis, and pathway analysis showed that differentially expressed genes and pathways identified in IBM and polymyositis were mostly comparable. However, pathways related to cell adhesion molecules were upregulated in IBM as compared with polymyositis and controls (p < 0.01). Notably, CDH1, which encodes the epidermal cell junction protein cadherin 1, was overexpressed in the muscles of IBM, which was validated by another RNA sequencing dataset from previous publications. Western blotting confirmed the presence of mature cadherin 1 protein in the muscles of IBM. Immunohistochemical staining confirmed the positivity for anti‐cadherin 1 antibody in the muscles of IBM, whereas there was no muscle fiber positive for anti‐cadherin 1 antibody in immune‐mediated necrotizing myopathy, antisynthetase syndrome, and controls. The fibers stained with anti‐cadherin 1 antibody did not have rimmed vacuoles or abnormal protein accumulation. Experimental skeletal muscle regeneration and differentiation systems showed that CDH1 is expressed during skeletal muscle regeneration and differentiation.Interpretation CDH1 was detected as a differentially expressed gene, and immunohistochemistry showed that cadherin 1 exists in the muscles of IBM, whereas it was rarely seen in those of other idiopathic inflammatory myopathies. Cadherin 1 upregulation in muscle could provide a valuable clue to the pathological mechanisms of IBM. ANN NEUROL 2022;91:317–328

Clinical characteristics of patients with antisynthetase syndrome and positive anti-Ro52 antibody

To analyze the clinical characteristics of patients with antisynthetase syndrome (ASS) and positive anti-Ro52 antibody. The clinical data of 203 ASS patients admitted to the First Affiliated Hospital of Zhengzhou University from 2017 to 2020 were analyzed retrospectively. Demographics, clinical manifestations, laboratory results, treatment and outcome were collected including data of 18 patients with rapidly progressive interstitial lung disease (RP-ILD). In total, the majority were women (148,72.9%). The average onset age was (51.9±13.3) years. There were 163 (80.3%) patients with positive anti-Ro52 antibody. The positivity in women (77.3% vs. 55.0%, P=0.004) was higher, and the median time from disease onset to diagnosis [4.5 (2.0, 24.0) months vs. 2.0 (1.0, 12.0) months, P=0.024] was longer in patients with positive anti-Ro52 antibody than those negative. Compared with negative patients, patients with positive anti-Ro52 antibody had a higher incidence of interstitial lung disease (ILD) (96.9% vs. 65.0%, P<0.001), arthritis (33.7% vs. 17.5%, P=0.046), and arthralgia (39.3% vs. 20.0%, P=0.022). Higher rate of positve antinuclear antibody (ANA) (85.3% vs. 55.0%, P<0.001), lower rate of positive anti-Jo-1 antibody (32.5% vs. 50.0%, P=0.039), lower albumin level [(34.6±5.2) g/L vs. (37.3±4.7) g/L,P=0.004] and lower lymphocyte counts [(1.4±0.8) ×109/L vs. (1.8±0.8) ×109/L, P=0.014] were more common in patients with positive anti-Ro52 antibody. The presence of anti-Ro52 antibody is associated with a particular phenotype of ASS, leading to common ILD, involvement of joints, high ANA positivity, low albumin and low lymphocyte counts.

A Comparison of Line Blots, Enzyme-linked Immunosorbent, and RNA-immunoprecipitation Assays of Antisynthetase Antibodies in Serum Samples from 44 Patients.

Objective To determine the differences between anti-aminoacyl tRNA synthetase (ARS) antibodies among line blots, enzyme-linked immunosorbent assay (ELISA) anti-ARS tests, and RNA-immunoprecipitation (IP) assays. Methods Sera from patients with confirmed or suspected antisynthetase syndrome (ASS) that were positive for either the anti-ARS test or the line-blot assay were used to perform an RNA-IP assay and ELISA to detect individual anti-ARS antibodies. Results Among the 44 patients, 10 were positive only in line-blot assays, 6 were positive only in the anti-ARS test, and 28 were positive in both assays. We compared the accuracy of these assays against the gold standard RNA-IP assay. The κ coefficient was 0.23 in the line-blot assay, but this increased to 0.75 when the cut-off was increased from 1+ to 2+. The κ coefficient was 0.73 in the anti-ARS test. The κ coefficient was 0.85 for positivity in both assays. Patients with ASS that was positive in an RNA-IP assay more frequently had mechanic's hand (62.1% vs. 20%: p=0.031), myositis (51.7 vs. 10%: p=0.028) and more ASS symptoms than those who were positive only in line-blot assays (3.48 vs. 2.2: p=0.019). Conclusions Clinicians need to understand the features of each assay and determine diagnoses by also considering clinical presentations. Diagnoses should not be judged based only on the results of line-blot assays due to the risk of a misdiagnosis from false positives.