Nailfold capillaroscopy findings of a multicentric multi-ethnic cohort of patients with idiopathic inflammatory myopathies.

OBJECTIVES: To assess nailfold video capillaroscopic (NVC) abnormalities and their association with clinical features, myositis-specific autoantibodies (MSA), and myositis-associated antibodies (MAA) in a large multi-ethnic cohort of patients with idiopathic inflammatory myopathies (IIM). METHODS: We recruited 155 IIM patients from three centres in Mexico, Spain, and the USA. We evaluated the clinical and laboratory features of the patients and performed semiquantitative and quantitative analyses of the NVC. Each NVC study was defined as having a normal, non-specific, early systemic sclerosis (SSc), active SSc, or late SSc pattern. Twenty-three patients had at least one follow-up NVC when disease control was achieved. Quantitative variables were expressed as medians and interquartile range (IQR) and were compared with the Kruskal-Wallis, the Mann-Whitney U-test, and the Wilcoxon test for paired medians. Associations between qualitative variables were assessed with the χ2 test. RESULTS: Most patients were women (68.3%), Hispanic (73.5%), and had dermatomyositis (DM) (61.2%). Fourteen patients (9%) had a normal NVC. A non-specific abnormality pattern was the most frequent (53.9%), and was associated with joint involvement, interstitial lung disease, Jo1 autoantibodies, anti-synthetase syndrome, and immune-mediated necrotising myopathy. The SSc pattern was observed mostly in DM and overlap myositis and was associated with cutaneous features and anti-TIF-1g autoantibodies. After treatment, there was a decrease in the capillaroscopic score, the capillary diameter, and the number of avascular areas, and an increase in capillary density and bushy capillary number. CONCLUSIONS: NVC abnormalities are related to the diagnosis, clinical features, disease activity, and autoantibodies of patients with IIM.

Pathogenic autoantibody internalization in myositis.

Objectives: Myositis is a heterogeneous family of autoimmune muscle diseases. As myositis autoantibodies recognize intracellular proteins, their role in disease pathogenesis has been unclear. This study aimed to determine whether myositis autoantibodies reach their autoantigen targets within muscle cells and disrupt the normal function of these proteins. Methods: Confocal immunofluorescence microscopy was used to localize antibodies and other proteins of interest in myositis muscle biopsies. Bulk RNA sequencing was used to study the transcriptomic profiles of 668 samples from patients with myositis, disease controls, and healthy controls. Antibodies from myositis patients were introduced into cultured myoblasts by electroporation and the transcriptomic profiles of the treated myoblasts were studied by bulk RNA sequencing. Results: In patients with myositis autoantibodies, antibodies accumulated inside myofibers in the same subcellular compartment as the autoantigen. Each autoantibody was associated with effects consistent with dysfunction of its autoantigen, such as the derepression of genes normally repressed by Mi2/NuRD in patients with anti-Mi2 autoantibodies, the accumulation of RNAs degraded by the nuclear RNA exosome complex in patients with anti-PM/Scl autoantibodies targeting this complex, and the accumulation of lipids within myofibers of anti-HMGCR-positive patients. Internalization of patient immunoglobulin into cultured myoblasts recapitulated the transcriptomic phenotypes observed in human disease, including the derepression of Mi2/NuRD-regulated genes in anti-Mi2-positive dermatomyositis and the increased expression of genes normally degraded by the nuclear RNA exosome complex in anti-PM/Scl-positive myositis. Conclusions: In myositis, autoantibodies are internalized into muscle fibers, disrupt the biological function of their autoantigen, and mediate the pathophysiology of the disease.

Preparing Enteral Formulas for Adult Patients with Phenylketonuria: A Minor Necessity but Major Challenge-A Case Report.

Phenylketonuria (PKU) is the most frequent of the congenital errors of amino acid (AA) metabolism worldwide. It leads to the accumulation of the essential AA phenylalanine (Phe) and it is associated with severe neurological defects. The early diagnosis and treatment of this rare disease, achieved through newborn screening and low-Phe diet, has profoundly changed its clinical spectrum, resulting in normal cognitive development. We face the first generation of PKU patients perinatally diagnosed and treated who have reached adulthood, whose special needs must be addressed, including feeding through enteral nutrition (EN). However, recommendations regarding EN in PKU constitute a gap in the literature. Although protein substitutes for patients with PKU are offered in multiple forms (Phe-free L-amino acid or casein glycomacropeptide supplements), none of these commercial formulas ensures the whole provision of daily total energy and protein requirements, including a safe amount of Phe. Consequently, the combination of different products becomes necessary when artificial nutrition via tube feeding is required. Importantly, the composition of these specific formulas may result in physicochemical interactions when they are mixed with standard EN products, leading to enteral feeding tubes clogging, and also gastrointestinal concerns due to hyperosmolality. Herein, we present the first reported case of EN use in an adult patient with PKU, where the separate administration of protein substitutes and the other EN products avoided physicochemical interactions.

Neurological adverse events related to immune-checkpoint inhibitors in Spain: a retrospective cohort study.

BACKGROUND: Neurological immune-related adverse events associated with immune checkpoint inhibitors can have several clinical manifestations, but the syndromes and prognostic factors are still not well known. We aimed to characterise and group the clinical features, with a special focus in patients presenting with encephalopathy, and to identify predictors of response to therapy and survival. METHODS: This retrospective observational study included patients with neurological immune-related adverse events from 20 hospitals in Spain whose clinical information, serum samples, and CSF samples were studied at Hospital Clinic de Barcelona, Barcelona, Spain. Patients with pre-existing paraneoplastic syndromes or evidence of alternative causes for their neurological symptoms were excluded. We reviewed the clinical information, classified their clinical features, and determined the presence of neural antibodies. Neurological status was assessed by the treating physician one month after adverse event onset (as improvement vs no improvement) and at the last evaluation (complete recovery or modified Rankin Scale score decrease of at least 2 points, indicating good outcome, vs all other modified Rankin Scale scores, indicating poor outcome); if the participant had died, the date and cause of death were recorded. We used Fisher's exact tests and Mann-Whitney U tests to analyse clinical features, and multivariable logistic regression to analyse prognostic factors. FINDINGS: From Jan 1, 2018, until Feb 1, 2023, 83 patients with suspected neurological immune-related adverse events after use of immune checkpoint inhibitors were identified, of whom 64 patients were included. These patients had a median age of 67 years (IQR 59-74); 42 (66%) were male and 22 (34%) were female. The predominant tumours were lung cancer (30 [47%] patients), melanoma (13 [21%] patients), and renal cell carcinoma (seven [11%] patients). Neural antibodies were detected in 14 (22%) patients; 52 (81%) patients had CNS involvement and 12 (19%) had peripheral nervous system involvement. Encephalopathy occurred in 45 (70%) patients, 12 (27%) of whom had antibodies or well defined syndromes consistent with definite paraneoplastic or autoimmune encephalitis, 24 (53%) of whom had encephalitis without antibodies or clinical features characteristic of a defined syndrome, and nine (20%) of whom had encephalopathy without antibodies or inflammatory changes in CSF or brain MRI. Nine (14%) of 64 patients had combined myasthenia and myositis, five of them with myocarditis. Even though 58 (91%) of 64 patients received steroids and 31 (48%) of 64 received additional therapies, 18 (28%) did not improve during the first month after adverse event onset, and 11 of these 18 people died. At the last follow-up for the 53 remaining patients (median 6 months, IQR 3-13), 20 (38%) had a poor outcome (16 deaths, one related to a neurological immune-related adverse event). Mortality risk was increased in patients with lung cancer (vs those with other cancers: HR 2·5, 95% CI 1·1-6·0) and in patients with encephalopathy without evidence of CNS inflammation or combined myocarditis, myasthenia, and myositis (vs those with the remaining syndromes: HR 5·0, 1·4-17·8 and HR 6·6, 1·4-31·0, respectively). INTERPRETATION: Most neurological immune-related adverse events involved the CNS and were antibody negative. The presence of myocarditis, myasthenia, and myositis, of encephalopathy without inflammatory changes, or of lung cancer were independent predictors of death. Most deaths occurred during the first month of symptom onset. If our findings are replicated in additional cohorts, they could confirm that these patients need early and intensive treatment. FUNDING: The Instituto de Salud Carlos III and the European Union.

Identification of Unique microRNA Profiles in Different Types of Idiopathic Inflammatory Myopathy.

Dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM) are four major types of idiopathic inflammatory myopathy (IIM). Muscle biopsies from each type of IIM have unique transcriptomic profiles. MicroRNAs (miRNAs) target messenger RNAs (mRNAs), thereby regulating their expression and modulating transcriptomic profiles. In this study, 18 DM, 12 IMNM, 6 AS, 6 IBM, and 6 histologically normal muscle biopsies underwent miRNA profiling using the NanoString nCounter system. Eleven miRNAs were exclusively differentially expressed in DM compared to controls, seven miRNAs were only differentially expressed in AS, and nine miRNAs were specifically upregulated in IBM. No differentially expressed miRNAs were identified in IMNM. We also analyzed miRNA-mRNA associations to identify putative targets of differentially expressed miRNAs. In DM and AS, these were predominantly related to inflammation and cell cycle progression. Moreover, our analysis showed an association between miR-30a-3p, miR-30e-3p, and miR-199b-5p downregulation in DM and the upregulation of target genes induced by type I interferon. In conclusion, we show that muscle biopsies from DM, AS, and IBM patients have unique miRNA signatures and that these miRNAs might play a role in regulating the expression of genes known to be involved in IIM pathogenesis.

Integrated Multi-Omics Analysis for Inferring Molecular Players in Inclusion Body Myositis.

Inclusion body myositis (IBM) is an acquired inflammatory myopathy affecting proximal and distal muscles that leads to weakness in patients over 50. It is diagnosed based on clinical and histological findings in muscle related to inflammation, degeneration, and mitochondria. In relation to IBM, a shortage of validated disease models and a lack of biomarkers and effective treatments constitute an unmet medical need. To overcome these hurdles, we performed an omics analysis of multiple samples from IBM patients (saliva, fibroblasts, urine, plasma, and muscle) to gain insight into the pathophysiology of IBM. Degeneration was evident due to the presence of amyloid ß peptide 1-42 (Aß1-42) in the saliva of the analyzed IBM patients. The presence of metabolic disarrangements in IBM was indicated by an imbalanced organic acid profile in fibroblasts and urine. Specifically, abnormal levels of L-pyroglutamic and orotic acid were supported by the abnormal expression of related metabolites in plasma and urine (glutathione and pyrimidines) and the aberrant expression of upstream gene regulators (L2HGDH, IDH2, OPLAH, and ASL) in muscle. Combined levels of L-pyroglutamic and orotic acid displayed an outstanding biomarker signature in urine with 100% sensitivity and specificity. The confirmation of systemic metabolic disarrangements in IBM and the identification of novel biomarkers reported herein unveil novel insights that require validation in larger cohorts.

Screening for late-onset Pompe disease in Internal Medicine departments in Spain.

BACKGROUND: The screening of high-risk populations using dried blood spots (DBS) has allowed the rapid identification of patients with Pompe disease, mostly in Neurology departments. The aim of the study was to determine the prevalence of late-onset Pompe disease (LOPD) among patients not previously diagnosed or tested for this entity despite presenting possible signs or symptoms of the disease in Internal Medicine departments in Spain. METHODS: This epidemiological, observational, cross-sectional, multicenter study included a single cohort of individuals with clinical suspicion of LOPD seen at Internal Medicine departments in Spain. The diagnosis of LOPD was initially established on the basis of the result of DBS. If decreased enzyme acid-alpha-1,4-glucosidase (GAA) activity was detected in DBS, additional confirmatory diagnostic measurements were conducted, including GAA activity in lymphocytes, fibroblasts, or muscle and/or genetic testing. RESULTS: The diagnosis of LOPD was confirmed in 2 out of 322 patients (0.6%). Reasons for suspecting LOPD diagnosis were polymyositis or any type of myopathy of unknown etiology (in one patient), and asymptomatic or pauci-symptomatic hyperCKemia (in the other). The time between symptom onset and LOPD diagnosis was 2.0 and 0.0 years. Both patients were asymptomatic, with no muscle weakness. Additionally, 19.7% of the non-LOPD cases received an alternative diagnosis. CONCLUSIONS: Our study highlights the existence of a hidden population of LOPD patients in Internal Medicine departments who might benefit from early diagnosis and early initiation of potential treatments.

Dermatomyositis unleashed by immune checkpoint inhibitors. Three additional cases and a review of the literature.

OBJECTIVES: Immune checkpoint inhibitors (ICI) have revolutionized the treatment of several locally advanced and metastatic tumors. They enhance the effector function of the immune system, consequently leading to different immune-related adverse events. The aim of the present study was to describe three cases of dermatomyositis (DM) triggered by ICI diagnosed at our institution and to perform a review of the literature. METHODS: We performed a retrospective clinical, laboratory, and pathological evaluation of three cases of DM triggered by ICI belonging to a cohort of 187 DM patients from the Clinic Hospital Muscle Research Group of Barcelona from January 2009 to July 2022. Moreover, we undertook a narrative review of the literature from January 1990 to June 2022. RESULTS: Cases from our institution were triggered by avelumab, an anti-PD-1 ligand (PD-L1), nivolumab, and pembrolizumab, both anti-programmed death-1 (PD-1). One of these patients had locally advanced melanoma, and two had urothelial carcinoma. The severity and response to treatment were heterogeneous among the different cases. All were positive at high titers for anti-TIF1γ autoantibodies; in one of them, serum before the onset of ICI was available, and anti-TIF1γ autoantibodies were already present. RNA expression of IFNB1, IFNG and genes stimulated by these cytokines were markedly elevated in these patients. CONCLUSIONS: In conclusion, data from our patients and the narrative review suggest that early positivity to anti-TIF1γ unleashed by ICI may play a role in the development of full-blown DM, at least in some cases.

Transcriptional derepression of CHD4/NuRD-regulated genes in the muscle of patients with dermatomyositis and anti-Mi2 autoantibodies.

OBJECTIVES: Myositis is a heterogeneous family of diseases including dermatomyositis (DM), immune-mediated necrotising myopathy (IMNM), antisynthetase syndrome (AS) and inclusion body myositis (IBM). Myositis-specific autoantibodies define different subtypes of myositis. For example, patients with anti-Mi2 autoantibodies targeting the chromodomain helicase DNA-binding protein 4 (CHD4)/NuRD complex (a transcriptional repressor) have more severe muscle disease than other DM patients. This study aimed to define the transcriptional profile of muscle biopsies from anti-Mi2-positive DM patients. METHODS: RNA sequencing was performed on muscle biopsies (n=171) from patients with anti-Mi2-positive DM (n=18), DM without anti-Mi2 autoantibodies (n=32), AS (n=18), IMNM (n=54) and IBM (n=16) as well as 33 normal muscle biopsies. Genes specifically upregulated in anti-Mi2-positive DM were identified. Muscle biopsies were stained for human immunoglobulin and protein products corresponding to genes specifically upregulated in anti-Mi2-positive muscle biopsies. RESULTS: A set of 135 genes, including SCRT1 and MADCAM1, was specifically overexpressed in anti-Mi2-positive DM muscle. This set was enriched for CHD4/NuRD-regulated genes and included genes that are not otherwise expressed in skeletal muscle. The expression levels of these genes correlated with anti-Mi2 autoantibody titres, markers of disease activity and with the other members of the gene set. In anti-Mi2-positive muscle biopsies, immunoglobulin was localised to the myonuclei, MAdCAM-1 protein was present in the cytoplasm of perifascicular fibres, and SCRT1 protein was localised to myofibre nuclei. CONCLUSIONS: Based on these findings, we hypothesise that anti-Mi2 autoantibodies could exert a pathogenic effect by entering damaged myofibres, inhibiting the CHD4/NuRD complex, and subsequently derepressing the unique set of genes defined in this study.

Unravelling inclusion body myositis using a patient-derived fibroblast model.

BACKGROUND: Inclusion body myositis (IBM) is an inflammatory myopathy clinically characterized by proximal and distal muscle weakness, with inflammatory infiltrates, rimmed vacuoles and mitochondrial changes in muscle histopathology. There is scarce knowledge on IBM aetiology, and non-established biomarkers or effective treatments are available, partly due to the lack of validated disease models. METHODS: We have performed transcriptomics and functional validation of IBM muscle pathological hallmarks in fibroblasts from IBM patients (n = 14) and healthy controls (n = 12), paired by age and sex. The results comprise an mRNA-seq, together with functional inflammatory, autophagy, mitochondrial and metabolic changes between patients and controls. RESULTS: Gene expression profile of IBM vs control fibroblasts revealed 778 differentially expressed genes (P-value adj < 0.05) related to inflammation, mitochondria, cell cycle regulation and metabolism. Functionally, an increased inflammatory profile was observed in IBM fibroblasts with higher supernatant cytokine secretion (three-fold increase). Autophagy was reduced considering basal protein mediators (18.4% reduced), time-course autophagosome formation (LC3BII 39% reduced, P-value < 0.05), and autophagosome microscopic evaluation. Mitochondria displayed reduced genetic content (by 33.9%, P-value < 0.05) and function (30.2%-decrease in respiration, 45.6%-decline in enzymatic activity (P-value < 0.001), 14.3%-higher oxidative stress, 135.2%-increased antioxidant defence (P-value < 0.05), 11.6%-reduced mitochondrial membrane potential (P-value < 0.05) and 42.8%-reduced mitochondrial elongation (P-value < 0.05)). In accordance, at the metabolite level, organic acid showed a 1.8-fold change increase, with conserved amino acid profile. Correlating to disease evolution, oxidative stress and inflammation emerge as potential markers of prognosis. CONCLUSIONS: These findings confirm the presence of molecular disturbances in peripheral tissues from IBM patients and prompt patients' derived fibroblasts as a promising disease model, which may eventually be exported to other neuromuscular disorders. We additionally identify new molecular players in IBM associated with disease progression, setting the path to deepen in disease aetiology, in the identification of novel biomarkers or in the standardization of biomimetic platforms to assay new therapeutic strategies for preclinical studies.

Coordinated local RNA overexpression of complement induced by interferon gamma in myositis.

Complement proteins are deposited in the muscles of patients with myositis. However, the local expression and regulation of complement genes within myositis muscle have not been well characterized. In this study, bulk RNA sequencing (RNAseq) analyses of muscle biopsy specimens revealed that complement genes are locally overexpressed and correlate with markers of myositis disease activity, including the expression of interferon-gamma (IFNγ)-induced genes. Single cell and single nuclei RNAseq analyses showed that most local expression of complement genes occurs in macrophages, fibroblasts, and satellite cells, with each cell type expressing different sets of complement genes. Biopsies from immune-mediated necrotizing myopathy patients, who have the lowest levels of IFNγ-induced genes, also had the lowest complement gene expression levels. Furthermore, data from cultured human cells showed that IFNγ upregulates complement expression in macrophages, fibroblasts, and muscle cells. Taken together, our results suggest that in myositis muscle, IFNγ coordinates the local overexpression of complement genes that occurs in several cell types.

Variants in DTNA cause a mild, dominantly inherited muscular dystrophy.

DTNA encodes α-dystrobrevin, a component of the macromolecular dystrophin-glycoprotein complex (DGC) that binds to dystrophin/utrophin and α-syntrophin. Mice lacking α-dystrobrevin have a muscular dystrophy phenotype, but variants in DTNA have not previously been associated with human skeletal muscle disease. We present 12 individuals from four unrelated families with two different monoallelic DTNA variants affecting the coiled-coil domain of α-dystrobrevin. The five affected individuals from family A harbor a c.1585G > A; p.Glu529Lys variant, while the recurrent c.1567_1587del; p.Gln523_Glu529del DTNA variant was identified in the other three families (family B: four affected individuals, family C: one affected individual, and family D: two affected individuals). Myalgia and exercise intolerance, with variable ages of onset, were reported in 10 of 12 affected individuals. Proximal lower limb weakness with onset in the first decade of life was noted in three individuals. Persistent elevations of serum creatine kinase (CK) levels were detected in 11 of 12 affected individuals, 1 of whom had an episode of rhabdomyolysis at 20 years of age. Autism spectrum disorder or learning disabilities were reported in four individuals with the c.1567_1587 deletion. Muscle biopsies in eight affected individuals showed mixed myopathic and dystrophic findings, characterized by fiber size variability, internalized nuclei, and slightly increased extracellular connective tissue and inflammation. Immunofluorescence analysis of biopsies from five affected individuals showed reduced α-dystrobrevin immunoreactivity and variably reduced immunoreactivity of other DGC proteins: dystrophin, α, ß, δ and γ-sarcoglycans, and α and ß-dystroglycans. The DTNA deletion disrupted an interaction between α-dystrobrevin and syntrophin. Specific variants in the coiled-coil domain of DTNA cause skeletal muscle disease with variable penetrance. Affected individuals show a spectrum of clinical manifestations, with severity ranging from hyperCKemia, myalgias, and exercise intolerance to childhood-onset proximal muscle weakness. Our findings expand the molecular etiologies of both muscular dystrophy and paucisymptomatic hyperCKemia, to now include monoallelic DTNA variants as a novel cause of skeletal muscle disease in humans.

Transcriptomic profiling reveals distinct subsets of immune checkpoint inhibitor induced myositis.

OBJECTIVES: Inflammatory myopathy or myositis is a heterogeneous family of immune-mediated diseases including dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated necrotising myopathy (IMNM) and inclusion body myositis (IBM). Immune checkpoint inhibitors (ICIs) can also cause myositis (ICI-myositis). This study was designed to define gene expression patterns in muscle biopsies from patients with ICI-myositis. METHODS: Bulk RNA sequencing was performed on 200 muscle biopsies (35 ICI-myositis, 44 DM, 18 AS, 54 IMNM, 16 IBM and 33 normal muscle biopsies) and single nuclei RNA sequencing was performed on 22 muscle biopsies (seven ICI-myositis, four DM, three AS, six IMNM and two IBM). RESULTS: Unsupervised clustering defined three distinct transcriptomic subsets of ICI-myositis: ICI-DM, ICI-MYO1 and ICI-MYO2. ICI-DM included patients with DM and anti-TIF1γ autoantibodies who, like DM patients, overexpressed type 1 interferon-inducible genes. ICI-MYO1 patients had highly inflammatory muscle biopsies and included all patients that developed coexisting myocarditis. ICI-MYO2 was composed of patients with predominant necrotising pathology and low levels of muscle inflammation. The type 2 interferon pathway was activated both in ICI-DM and ICI-MYO1. Unlike the other types of myositis, all three subsets of ICI-myositis patients overexpressed genes involved in the IL6 pathway. CONCLUSIONS: We identified three distinct types of ICI-myositis based on transcriptomic analyses. The IL6 pathway was overexpressed in all groups, the type I interferon pathway activation was specific for ICI-DM, the type 2 IFN pathway was overexpressed in both ICI-DM and ICI-MYO1 and only ICI-MYO1 patients developed myocarditis.

The pattern of MHC class I expression in muscle biopsies from patients with myositis and other neuromuscular disorders.

OBJECTIVE: Diagnostic muscle biopsies are routinely immunostained for major histocompatibility complex class I (MHC-I) protein. In this study we analysed the prevalence and patterns of MHC-I immunostaining in biopsies from patients with different types of myopathies and neurogenic disorders. METHODS: All 357 diagnostic muscle biopsies processed at the Johns Hopkins Neuromuscular Pathology Laboratory from August 2013 to January 2017 were immunostained for MHC-I. The prevalence and patterns of MHC-I immunostaining were compared between patients with histologically normal muscle biopsies (n = 31), idiopathic inflammatory myopathies (IIMs; n = 170), non-inflammatory myopathies (n = 60) and neurogenic disorders (n = 96). RESULTS: MHC-I immunostaining was abnormal in most patients with DM (98%), sporadic IBM (sIBM; 100%), immune-mediated necrotizing myopathy (IMNM; 100%) and polymyositis (77%). In contrast, MHC-I immunostaining was less frequently present in non-inflammatory myopathies (32%) or neurogenic disorders (30%). Overall, abnormal MHC-I immunostaining had a sensitivity of 0.95 and a specificity of 0.82 for diagnosing IIMs. A focal MHC-I staining pattern was associated with IMNM, whereas a global pattern was more prevalent in sIBM and a perifascicular pattern was significantly more common in dermatomyositis. Among 18 DM biopsies without perifascicular atrophy, 50% had a perifascicular MHC-I staining pattern. Sarcoplasmic upregulation staining was more common than sarcolemmal staining across all groups. CONCLUSION: MHC-I immunostaining was useful to distinguish IIMs from non-inflammatory myopathies or neurogenic disorders. Of note, a perifascicular MHC-I staining pattern was present only in those with DM, including half of those without perifascicular atrophy; many of these biopsies may not otherwise have been diagnostic for DM.

Clinico-pathological phenotypes of systemic sclerosis-associated myopathy: analysis of a large multicentre cohort.

OBJECTIVE: The objective of this study was to analyse the clinico-serological and histological phenotypes of patients with SSc with associated myopathy. METHODS: From November 2002 to September 2020, 52 patients with SSc underwent a muscle biopsy for suspected myopathy. We established two subgroups according to the histological findings based on the presence of isolated fibrosis or fibrosis together with significant inflammation. These patterns were designated as fibrosing and inflammatory, respectively. Clinical data, antibody profile, electrophysiologic studies, muscle biopsy findings and data regarding treatment, mortality and survival were compared between the two groups. RESULTS: Fourteen biopsies had a fibrosing pattern, whereas 26 showed an inflammatory pattern that could be classified (according to the predominant pattern) into DM (n = 7), necrotizing myopathy (n = 4) and non-specific myositis (n = 15). Additionally, 12 muscle biopsies were reported as neurogenic atrophy (n = 2), or normal muscle or minimal changes (n = 10). Compared with the inflammatory group, SSc patients with the fibrosing pattern presented a higher prevalence of ischaemic heart disease (38.5% vs 3.8%, P = 0.011), conduction abnormalities or arrhythmias (61.5% vs 26.9%, P = 0.036), anti-topo I antibodies (42.9% vs 11.5%, P = 0.044), greater median ESR (53.5 mm/h vs 32.5 mm/h, P = 0.013), with poor response to treatment and a higher mortality (42.9% vs 3.8%, P = 0.004) and lower cumulative survival (P = 0.035). CONCLUSIONS: Patients with SSc-associated myopathy require a comprehensive approach that encompasses clinical, serological and histopathological aspects, given their outcome predictive capacity. At least two different phenotypes can be drawn, considering clinico-pathological features. Significant differences are delineated between both a fibrotic and an inflammatory phenotype.

Coexisting autoantibodies against transcription factor Sp4 are associated with decreased cancer risk in patients with dermatomyositis with anti-TIF1γ autoantibodies.

OBJECTIVES: In dermatomyositis (DM), autoantibodies are associated with unique clinical phenotypes. For example, anti-TIF1γ autoantibodies are associated with an increased risk of cancer. The purpose of this study was to discover novel DM autoantibodies. METHODS: Phage ImmunoPrecipitation Sequencing using sera from 43 patients with DM suggested that transcription factor Sp4 is a novel autoantigen; this was confirmed by showing that patient sera immunoprecipitated full-length Sp4 protein. Sera from 371 Johns Hopkins patients with myositis (255 with DM, 28 with antisynthetase syndrome, 40 with immune-mediated necrotising myopathy, 29 with inclusion body myositis and 19 with polymyositis), 80 rheumatological disease controls (25 with Sjogren's syndrome, 25 with systemic lupus erythematosus and 30 with rheumatoid arthritis (RA)) and 200 healthy comparators were screened for anti-SP4 autoantibodies by ELISA. A validation cohort of 46 anti-TIF1γ-positive patient sera from the University of Pittsburgh was also screened for anti-Sp4 autoantibodies. RESULTS: Anti-Sp4 autoantibodies were present in 27 (10.5%) patients with DM and 1 (3.3%) patient with RA but not in other clinical groups. In patients with DM, 96.3% of anti-Sp4 autoantibodies were detected in those with anti-TIF1γ autoantibodies. Among 26 TIF1γ-positive patients with anti-Sp4 autoantibodies, none (0%) had cancer. In contrast, among 35 TIF1γ-positive patients without anti-Sp4 autoantibodies, 5 (14%, p=0.04) had cancer. In the validation cohort, among 15 TIF1γ-positive patients with anti-Sp4 autoantibodies, 2 (13.3%) had cancer. By comparison, among 31 TIF1γ-positive patients without anti-Sp4 autoantibodies, 21 (67.7%, p<0.001) had cancer. CONCLUSIONS: Anti-Sp4 autoantibodies appear to identify a subgroup of anti-TIF1γ-positive DM patients with lower cancer risk.