Difference in adhesion molecule expression (ICAM-1 and VCAM-1) in juvenile and adult dermatomyositis, polymyositis and inclusion body myositis

Differentiating idiopathic inflammatory myopathies by automated morphometric analysis of MHC-1, MHC-2 and ICAM-1 in muscle tissue

AIMS

Diagnosis of idiopathic inflammatory myopathies (IIM) is based on morphological characteristics and the evaluation of disease-related proteins. However, although broadly applied, substantial bias is imposed by the respective methods, observers and individual staining approaches. We aimed to quantify the protein levels of major histocompatibility complex (MHC)-1, (MHC)-2 and intercellular adhesion molecule (ICAM)-1 using an automated morphometric method to mitigate bias.

METHODS

Double immunofluorescence staining was performed on whole muscle sections to study differences in protein expression in myofibre and endomysial vessels. We analysed all IIM subtypes including dermatomyositis (DM), anti-synthetase syndrome (ASyS), inclusion body myositis (IBM), immune-mediated-necrotising myopathy (IMNM), dysferlinopathy (DYSF), SARS-CoV-2 infection and vaccination-associated myopathy. Biopsies with neurogenic atrophy (NA) and normal morphology served as controls. Bulk RNA-Sequencing (RNA-Seq) was performed on a subset of samples.

RESULTS

Our study highlights the significance of MHC-1, MHC-2 and ICAM-1 in diagnosing IIM subtypes and reveals distinct immunological profiles. RNASeq confirmed the precision of our method and identified specific gene pathways in the disease subtypes. Notably, ASyS, DM and SARS-CoV-2-associated myopathy showed increased ICAM-1 expression in the endomysial capillaries, indicating ICAM-1-associated vascular activation in these conditions. In addition, ICAM-1 showed high discrimination between different subgroups with high sensitivity and specificity.

CONCLUSIONS

Automated morphometric analysis provides precise quantitative data on immune-associated proteins that can be integrated into our pathophysiological understanding of IIM. Further, ICAM-1 holds diagnostic value for the detection of IIM pathology.

Multi-Modal Single-Cell Sequencing Identifies Cellular Immunophenotypes Associated With Juvenile Dermatomyositis Disease Activity

Juvenile dermatomyositis (JDM) is a rare autoimmune condition with insufficient biomarkers and treatments, in part, due to incomplete knowledge of the cell types mediating disease. We investigated immunophenotypes and cell-specific genes associated with disease activity using multiplexed RNA and protein single-cell sequencing applied to PBMCs from 4 treatment-naïve JDM (TN-JDM) subjects at baseline, 2, 4, and 6 months post-treatment and 4 subjects with inactive disease on treatment. Analysis of 55,564 cells revealed separate clustering of TN-JDM cells within monocyte, NK, CD8+ effector T and naïve B populations. The proportion of CD16+ monocytes was reduced in TN-JDM, and naïve B cells and CD4+ Tregs were expanded. Cell-type differential gene expression analysis and hierarchical clustering identified a pan-cell-type IFN gene signature over-expressed in TN-JDM in all cell types and correlated with disease activity most strongly in cytotoxic cell types. TN-JDM CD16+ monocytes expressed the highest IFN gene score and were highly skewed toward an inflammatory and antigen-presenting phenotype at both the transcriptomic and proteomic levels. A transitional B cell population with a distinct transcriptomic signature was expanded in TN-JDM and characterized by higher CD24 and CD5 proteins and less CD39, an immunoregulatory protein. This data provides new insights into JDM immune dysregulation at cellular resolution and serves as a novel resource for myositis investigators.

The risk of ischemic stroke in patients with idiopathic inflammatory myopathies: a systematic review and meta-analysis

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) are a group of chronic rheumatic diseases that can affect multiple systems; the risk of ischemic stroke in patients with IIM remains controversial. We aimed to systematically evaluate the risk of ischemic stroke in IIMs.

METHODS

The PubMed, Embase, and Cochrane library were searched for relevant studies. Pooled relative risk (RR) with a 95% confidence interval (CI) was calculated as effect size to evaluate the risk of ischemic stroke in patients with IIM. Random effects model was chosen when I² > 50%. We pooled all studies in a first total analysis to assess the risk of ischemic stroke in IIM. Subgroup analyses were conducted based on the subtypes of IIM (dermatomyositis) and country. Sensitivity analysis was performed to identify the heterogeneity sources.

RESULTS

A total of 6 studies with 5,114 IIM cases and 14,516,099 controls were included, and the results demonstrated that IIMs were associated with an increased risk of ischemic stroke (RR = 2.41, 95% CI: 1.31, 4.45). Subgroup analysis indicated that patients with dermatomyositis (DM) had a 49% excess risk of ischemic stroke than controls; Asian patients with IIM had an increased risk of ischemic stroke, although not for American patients.

CONCLUSION

IIMs, especially patients with DM, are associated with an increased risk of ischemic stroke. Appropriate intervention may be taken into account for patients with IIM, especially when accompanied by other traditional risk factors of ischemic stroke. Key Points • This study evaluated the risk of ischemic stroke in patients with IIMs. • Generally, IIMs are associated with an increased risk of ischemic stroke. • Patients with DM had a 49% excess risk of ischemic stroke than controls. • Subgroup analysis showed that Asian patients with IIMs were at increased risk of ischemic stroke, but not Americans.

Ocular microvascular damage in autoimmune rheumatic diseases: The pathophysiological role of the immune system

Pathological eye involvement represents a quite common finding in a broad spectrum of autoimmune rheumatic diseases (ARDs). Ocular signs, often occur as early manifestations in ARDs, ranging from symptoms related to the mild dry eye disease to sight-threatening pathologies, linked to the immune response against retinal and choroidal vessels. Retinovascular damage driven by markedly inflammatory reactivity need a prompt diagnosis and treatment. Immune-complexes formation, complement activation and antibody-mediated endothelial damage seem to play a key role, particularly, in microvascular damage and ocular symptoms, occurring in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and Sjögren's syndrome (SS). Conversely, early alterations of retinal and choroidal vessels in the asymptomatic patient, often detectable coincidentally, might be indicators of widespread vascular injury in other connective tissue diseases. Particularly, endothelin-induced hypoperfusion and pathological peri-choroidal extracellular matrix deposition, might be responsible for the micro-architectural alterations and loss of capillaries detected in systemic sclerosis (SSc). Instead, interferon alpha-mediated microvascular rarefaction, combined with endothelial lesions caused by specific autoantibodies and immune-complexes, appear to play a significant role in retinal vasculopathy associated to inflammatory idiopathic myopathies (IIM). The immuno-pathophysiological mechanisms of ocular microcirculatory damage associated with the major ARDs will be discussed under the light of the most recent achievements.

Biomarker profiles of endothelial activation and dysfunction in rare systemic autoimmune diseases: implications for cardiovascular risk

OBJECTIVES

Vasculopathy is an important hallmark of systemic chronic inflammatory connective tissue diseases (CICTD) and is associated with increased cardiovascular risk. We investigated disease-specific biomarker profiles associated with endothelial dysfunction, angiogenic homeostasis and (tissue) inflammation, and their relation to disease activity in rare CICTD.

METHODS

A total of 38 serum proteins associated with endothelial (dys)function and inflammation were measured by multiplex-immunoassay in treatment-naive patients with localized scleroderma (LoS, 30), eosinophilic fasciitis (EF, 8) or (juvenile) dermatomyositis (34), 119 (follow-up) samples during treatment, and 65 controls. Data were analysed by unsupervised clustering, Spearman correlations, non-parametric t test and ANOVA.

RESULTS

The systemic CICTD, EF and dermatomyositis, had distinct biomarker profiles, with 'signature' markers galectin-9 (dermatomyositis) and CCL4, CCL18, CXCL9, fetuin, fibronectin, galectin-1 and TSP-1 (EF). In LoS, CCL18, CXCL9 and CXCL10 were subtly increased. Furthermore, dermatomyositis and EF shared upregulation of markers related to interferon (CCL2, CXCL10), endothelial activation (VCAM-1), inhibition of angiogenesis (angiopoietin-2, sVEGFR-1) and inflammation/leucocyte chemo-attraction (CCL19, CXCL13, IL-18, YKL-40), as well as disturbance of the Angiopoietin-Tie receptor system and VEGF-VEGFR system. These profiles were related to disease activity, and largely normalized during treatment. However, a subgroup of CICTD patients showed continued elevation of CXCL10, CXCL13, galectin-9, IL-18, TNFR2, VCAM-1, and/or YKL-40 during clinically inactive disease, possibly indicating subclinical interferon-driven inflammation and/or endothelial dysfunction.

CONCLUSION

CICTD-specific biomarker profiles revealed an anti-angiogenic, interferon-driven environment during active disease, with incomplete normalization under treatment. This warrants further investigation into monitoring of vascular biomarkers during clinical follow-up, or targeted interventions to minimize cardiovascular risk in the long term.

Increased Soluble Cytoplasmic Bcl-2 Protein Serum Levels and Expression and Decreased Fas Expression in Lymphocytes and Monocytes in Juvenile Dermatomyositis

OBJECTIVE

To evaluate soluble Fas antigen (sFas), sFas ligand (sFasL), soluble tumor necrosis factor-related apoptosis-inducing ligand, and soluble cytoplasmic Bcl-2 protein (sBcl-2) serum levels, Fas and Bcl-2 expressions in T and B lymphocytes and monocytes and relations with erythrocyte sedimentation rate, C-reactive protein (CRP), Childhood Myositis Assessment Scale, and manual muscle testing in juvenile dermatomyositis (JDM).

METHODS

Serum levels were determined by ELISA and peripheral cell expressions by flow cytometry for patients with JDM or juvenile idiopathic arthritis (JIA), and healthy controls.

RESULTS

Patients with JDM had increased sBcl-2, which correlated with CRP. Expression of Bcl-2 was increased and expression of Fas was decreased in CD3+, CD4+, and CD8+ T lymphocytes compared with JIA and/or healthy controls.

CONCLUSION

Patients with JDM presented a unique apoptosis-related proteins profile, which may contribute to disease development.

MicroRNA-381 reduces inflammation and infiltration of macrophages in polymyositis via downregulating HMGB1

The downregulation of microRNA (miR)-381 has been detected in various diseases. The present study aimed to investigate the effects, and underlying mechanisms of miR-381 on inflammation and macrophage infiltration in polymyositis (PM). A mouse model of experimental autoimmune myositis (EAM) was generated in this study. Hematoxylin and eosin staining was conducted to detect the inflammation of muscle tissues. In addition, ELISA and immunohistochemistry were performed to determine the expression levels of associated factors, and reverse transcription-quantitative polymerase chain reaction and western blotting were used to detect the expression levels of related mRNAs and proteins. A luciferase activity assay was used to confirm the binding of miR-381 and high mobility group box 1 (HMGB1) 3' untranslated region. Transwell assays were also performed to assess the migratory ability of macrophages. The results demonstrated that serum creatine kinase (s-CK), HMGB1 and cluster of differentiation (CD)163 expression in patients with PM were increased compared within healthy controls. Conversely, the expression levels of miR-381 were downregulated in patients with PM. Furthermore, high HMGB1 expression was associated with poor survival rate in patients with PM. In the mouse studies, muscle inflammation and CD163 expression were decreased in the anti-IL-17 and anti-HMGB1 groups, compared with in the EAM model group. The expression levels of s-CK, HMGB1, IL-17 and intercellular adhesion molecule (ICAM)-1 were also downregulated in response to anti-IL-17 and anti-HMGB1. These findings indicated that HMGB1 was closely associated with inflammatory responses. In addition, the present study indicated that transfection of macrophages with miR-381 mimics reduced the migration of inflammatory macrophages, and the expression levels of HMGB1, IL-17 and ICAM-1. Conversely, miR-381 inhibition exerted the opposite effects. The effects of miR-381 inhibitors were reversed by HMGB1 small interfering RNA. In conclusion, miR-381 may reduce inflammation and the infiltration of macrophages; these effects were closely associated with the downregulation of HMGB1.

Skeletal muscle cells actively shape (auto)immune responses

Histopathological analyses of muscle specimens from myositis patients indicate that skeletal muscle cells play an active role in the interaction with immune cells. Research over the last few decades has shown that skeletal muscle cells exhibit immunobiological properties that perfectly define them as non-professional antigen presenting cells. They are able to present antigens via major histocompatibility complex molecules, exhibit costimulatory molecules and secrete soluble molecules that actively shape the immune response in an either pro- or anti-inflammatory manner. Skeletal muscle cells regulate both innate and adaptive immune responses and are essentially involved in the pathophysiological processes of idiopathic inflammatory myopathies. Understanding the role of skeletal muscle cells might help to identify new therapeutic targets for these devastating diseases. This review summarizes the immunobiological features of skeletal muscle cells, especially in the context of idiopathic inflammatory myopathies, and discusses shortcomings and limitations in skeletal muscle related research providing potential perspectives to overcome them in the future.

Consensus-based recommendations for the management of juvenile dermatomyositis

Background

In 2012, a European initiative called Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) was launched to optimise and disseminate diagnostic and management regimens in Europe for children and young adults with rheumatic diseases. Juvenile dermatomyositis (JDM) is a rare disease within the group of paediatric rheumatic diseases (PRDs) and can lead to significant morbidity. Evidence-based guidelines are sparse and management is mostly based on physicians' experience. Consequently, treatment regimens differ throughout Europe.

Objectives

To provide recommendations for diagnosis and treatment of JDM.

Methods

Recommendations were developed by an evidence-informed consensus process using the European League Against Rheumatism standard operating procedures. A committee was constituted, consisting of 19 experienced paediatric rheumatologists and 2 experts in paediatric exercise physiology and physical therapy, mainly from Europe. Recommendations derived from a validated systematic literature review were evaluated by an online survey and subsequently discussed at two consensus meetings using nominal group technique. Recommendations were accepted if >80% agreement was reached.

Results

In total, 7 overarching principles, 33 recommendations on diagnosis and 19 recommendations on therapy were accepted with >80% agreement among experts. Topics covered include assessment of skin, muscle and major organ involvement and suggested treatment pathways.

Conclusions

The SHARE initiative aims to identify best practices for treatment of patients suffering from PRD. Within this remit, recommendations for the diagnosis and treatment of JDM have been formulated by an evidence-informed consensus process to produce a standard of care for patients with JDM throughout Europe.

Gene Expression Profile of Inflammatory Myopathy with Malignancy is Similar to that of Dermatomyositis rather than Polymyositis

Objective An association has been reported between inflammatory myopathies (IMs), which include polymyositis (PM) and dermatomyositis (DM), and malignancy, and the concept of cancer-associated myositis (CAM) was recently proposed. We herein attempted to determine the features and etiologies of these myopathies. Methods We analyzed the gene expression levels via microarray and real-time quantitative reverse transcription polymerase chain reaction analyses to identify genes that were specifically upregulated or downregulated with suspected inflammatory involvement and verified the microarray data via an immunohistochemical (IHC) analysis in additional cases. Patients We selected 14 patients with the following conditions: PM without malignancy (n=3), DM without malignancy (n=3), CAM (n=3), and Controls (no pathological changes or malignancy; n=5). Results PM was distinct from DM and CAM in a clustering analysis and exhibited the highest numbers of overexpressed genes and specific pathologies in a gene ontology analysis. The IHC analysis confirmed the gene expression results. Conclusion PM is associated with severe inflammatory pathological findings, primarily in the cell-mediated immune system. DM and CAM exhibit similarities in the gene expression and IHC results, which suggest that humoral immunity is the main etiology for both myopathies, indicating the importance of cancer screening in patients with IMs, particularly DM.

Increased expression of vascular cell adhesion molecule 1 in muscle biopsy samples from juvenile dermatomyositis patients with short duration of untreated disease is regulated by miR-126

OBJECTIVE

To evaluate the effect of duration of untreated disease on vascular cell adhesion molecule 1 (VCAM-1) and microRNA (miRNA) expression in muscle biopsy samples from children with juvenile dermatomyositis (DM) as well as its effect on soluble VCAM-1 (sVCAM-1) and tumor necrosis factor α (TNFα) concentrations in sera from these children.

METHODS

We enrolled 28 untreated children with juvenile DM and 8 pediatric controls. Eleven children with juvenile DM had short duration of untreated disease (symptoms for ≤2 months before muscle biopsy), and 17 had long duration of untreated disease (symptoms for >2 months before muscle biopsy). Vascular structures, characterized by immunofluorescence using antibodies against von Willebrand factor, VCAM-1, and α-smooth muscle actin, were measured for total area and intensity. Circulating sVCAM-1 and TNFα levels were determined in patients with short duration of untreated disease, patients with long duration of untreated disease, and controls. Differential expression of microRNA-126 (miR-126) in muscle biopsy samples from the 2 patient groups and the control group was detected by miRNA expression profiling and confirmed by quantitative reverse transcription-polymerase chain reaction in muscle biopsy samples from the 3 groups.

RESULTS

Juvenile DM patients with short duration of untreated disease had significantly higher total positive area and intensity/high power field of VCAM-1 expression than did juvenile DM patients with long duration of untreated disease (P = 0.043 and P = 0.015, respectively) or controls (P = 0.004 and P = 0.001, respectively). Von Willebrand factor antigen-positive vasculature displayed greater VCAM-1 intensity in patients with short duration of untreated disease than in patients with long duration of untreated disease (P = 0.001). Circulating levels of sVCAM-1 and TNFα were significantly higher in patients with short duration of untreated disease than in controls (P = 0.013 and P = 0.048, respectively). The miRNA miR-126, a negative regulator of VCAM-1 expression, was significantly decreased (3.39-fold; P < 0.006) in patients with short duration of untreated disease compared to controls, while miR-126 expression in patients with long duration of untreated disease did not differ significantly compared to controls.

CONCLUSION

In patients with short duration of untreated disease, miR-126 down-regulation is associated with increased VCAM-1 in both muscle and blood, suggesting that VCAM-1 plays a critical role early in juvenile DM disease pathophysiology, augmented by TNFα.

Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE

To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis.

METHOD

In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X).

RESULTS

The mean ages at disease onset were 42.0±15.9 and 7.3±3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (p<0.050). Moreover, a significantly higher frequency of major histocompatibility complex I (96.4% vs. 50.0%, p<0.001) compared with major histocompatibility complex II expression (14.3% vs. 53.6%, p=0.004) was observed in juvenile dermatomyositis. Fiber damage (p=0.006) and increased connective tissue (p<0.001) were significantly higher in adult dermatomyositis compared with the presence of perifascicular atrophy (p<0.001). The results of the histochemical and histological data did not correlate with the demographic data or with the clinical and laboratory features.

CONCLUSION

The overexpression of major histocompatibility complex I was an important finding for the diagnosis of both groups, particularly for juvenile dermatomyositis, whereas there was lower levels of expression of major histocompatibility complex II than major histocompatibility complex I. This finding was particularly apparent in juvenile dermatomyositis.

Clinical features, pathogenesis and treatment of juvenile and adult dermatomyositis

Juvenile and adult dermatomyositis (DM) have multiple commonalities, yet display differing prevalence of features, outcomes and comorbidities. In general, compared with the disease in adults, children with DM have more vasculopathy and a greater likelihood of calcinosis, periungual and gingival telangiectasias, and ulceration, but have a better long-term prognosis with improved survival. Adults with DM are more likely to have myositis-specific antibodies, develop interstitial lung disease, have amyopathic disease, and have a marked association with malignancy and other comorbidities. Both diseases have similar features on muscle biopsy and interferon gene signature, although subtle differences can exist in pathogenesis and pathology, such as more capillary loss and a greater degree of C5b-9 complement deposition in affected muscle of juvenile patients. Initiatives are underway to improve classification, markers of disease activity and ability to predict outcome of juvenile and adult DM. The purpose of this Review is to compare and contrast the unique features between juvenile and adult disease and to outline new initiatives in the field.

Actuality of juvenile dermatomyositis

Juvenile dermatomyositis is a rare disorder, but remains the most commonly occurring chronic inflammatory myopathy among children. Other than the proximal muscles and skin, which are routinely affected, vasculopathy may affect other viscera and can be multisystemic. A redefinition of the diagnostic criteria is currently underway and is likely to lead to other clinical signs and to sensitive and non-invasive examinations such as MRI. The impact of juvenile dermatomyositis on health and quality of life remains significant despite systemic corticosteroid therapy and immunosuppressor treatment, which have considerably improved the prognosis. Numerous predictors for favourable and pejorative evolution have been identified. The standardisation and the generalisation of clinical assessment tools will make it possible to carry out the clinical trials required to determine the relevance of the new therapeutic options available for children.

Evidence for prescribing exercise as treatment in pediatric rheumatic diseases

There has been an increasing recognition of adverse short-, mid-, or long-term effects associated with the treatment as well as the disease itself that impair the health-related quality of life and functional capacity of children and adolescents with rheumatic diseases. Interestingly, cumulative evidence has suggested that exercise training may benefit patients with juvenile idiopathic arthritis, juvenile systemic lupus erythematosus, juvenile dermatomyositis and juvenile fibromyalgia, attenuating several clinical symptoms related to physical disability. Remarkably, recent evidence also suggests that exercise may have direct effects on the pathogenesis of autoimmune diseases by attenuating chronic low-grade systemic inflammation. It is also important to emphasize that no exercise-related adverse effects have been reported. This short review provides the evidence for physical training as a treatment of pediatric rheumatic diseases, introducing a novel concept that exercise is a treatment for these populations.

Idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies are a group of systemic autoimmune syndromes characterized by striated muscle inflammation. Here, we discuss the clinical features of this group of conditions and review the recent developments in the understanding of the pathogenesis and immunogenetics of the idiopathic inflammatory myopathies. The role of myositis-specific autoantibodies and their clinical significance and an overview of management are also provided.

Measurement of platelet-derived microparticle levels using an enzyme-linked immunosorbent assay in polymyositis and dermatomyositis patients

Platelet-derived microparticle (PDMP) levels were measured using an enzyme-linked immunosorbent assay (ELISA) to elucidate the role of platelet activation in patients with polymyositis or dermatomyositis (PM/DM). PDMP levels in active PM/DM patients (median 13.3 U/ml, interquartile range 9.9-20.7 U/ml, n = 16) and those in patients undergoing treatment (12.1 U/ml, 7.4-16.7 U/ml, n = 12) were significantly higher than in controls (6.5 U/ml, 5.0-8.4 U/ml, n = 26, vs. active, P = 0.0001; vs. treatment, P = 0.004). In a paired sampling study, PDMP decreased significantly after glucocorticoid treatment (P = 0.04). PDMP in the active PM/DM patients correlated significantly with serum C-reactive protein levels (r(s) = 0.67, P = 0.01). These results suggest that platelets may play an important role in the inflammatory process, and that PDMP level could be a useful marker of inflammatory activity in PM/DM patients. Muscle Nerve 39: 586-590, 2009.

Juvenile dermatomyositis and other idiopathic inflammatory myopathies of childhood

Juvenile dermatomyositis, the most common inflammatory myopathy of childhood, is a rare systemic autoimmune vasculopathy that is characterised by weakness in proximal muscles and pathognomonic skin rashes. The length of time before the initiation of treatment affects presenting symptoms, laboratory measures, and pathophysiology. It also affects disease outcomes, including the development of pathological calcifications, which are associated with increased morbidity. Both genetic and environmental risk factors seem to have a role in the cause of juvenile dermatomyositis; HLA B8-DRB1*0301 ancestral haplotype is a strong immunogenetic risk factor, and antecedent infections and birth seasonality suggest that environmental stimuli might increase risk. Activation of dendritic cells with upregulation of genes induced by type-1 interferon (alpha) in muscle and peripheral blood seems to be central to disease pathogenesis. Treatment often includes combinations of corticosteroids, methotrexate, and other immunosuppressive agents. Disease outcome, if treatment is initiated early, is generally good. Randomised controlled trials are needed to define the most effective treatments.

Multiplex immunoassay analysis of cytokines in idiopathic inflammatory myopathy

CONTEXT

Idiopathic inflammatory myopathies (IIMs), including dermatomyositis, polymyositis, and inclusion-body myositis, can be difficult to diagnose.

OBJECTIVE

To determine if a multiplex immunoassay for markers of inflammation in muscle homogenates correlates with a diagnosis of IIM.

DESIGN

Frozen archived muscle biopsy specimens from 30 patients with IIM and 34 patients without IIM were homogenized and analyzed for cytokine content with a multiplex microbead-based immunoassay system. Analyte concentrations were normalized to total lysate protein concentration prior to comparison.

RESULTS

Two cytokines, interleukin 1ra and monocyte chemoattractant protein 1, and 1 soluble adhesion molecule, intracellular adhesion molecule 1, were found at significantly greater concentrations in muscle samples from patients with IIM. Intracellular adhesion molecule 1 levels alone were 83% sensitive and 91% specific for IIM at a cutoff of 1240 pg/mg muscle protein.

CONCLUSIONS

Immunoassays for selected inflammatory markers can serve in conjunction with histopathologic analysis as sensitive and specific tools for the diagnosis of IIM.

Dermatomyositis

Dermatomyositis (DM) is a chronic inflammatory disorder of the skin and muscles. Although thought to be autoimmune in origin, many questions remain as to the etiopathogenesis of this disease. DM has classically been considered a humorally mediated disease. Current evidence, however, seems to increasingly support alternative (though not mutually exclusive) mechanisms of pathogenesis, including cell-mediated and innate immune system dysfunction. Pathologic findings of DM in muscle include infarcts, perifascicular atrophy, endothelial cell swelling and necrosis, vessel wall membrane attack complex deposition, and myocyte-specific MHC I upregulation. As for the skin, histopathologic findings include hyperkeratosis, epidermal basal cell vacuolar degeneration and apoptosis, increased dermal mucin deposition, and a cell-poor interface dermatitis. Autoantibodies, particularly those that bind nuclear or cytoplasmic ribonucleoprotein antigens, are also commonly found in DM, although their importance in pathogenesis remains unclear. Defective cellular clearance, genetic predilection and environmental exposures, such as viral infection, may also play an important role in the pathogenesis of DM. The seminal work regarding the pathogenesis of DM is reviewed and an update on the recent basic and molecular advances in the field is provided.

Nuclear translocation of p65 NF-kappaB is sufficient for VCAM-1, but not ICAM-1, expression in TNF-stimulated smooth muscle cells: Differential requirement for PARP-1 expression and interaction

Although nuclear translocation of NF-kappaB and subsequent binding to promoters of ICAM-1 and VCAM-1 have been shown to be decisive for their expression, a number of discrepancies in the expression patterns of these adhesion molecules have been reported in both cell culture systems and disease settings, including atherosclerosis, asthma, and autoimmune diseases. Here we show that while p65 NF-kappaB nuclear translocation in TNF-treated smooth muscle cells (SMCs) was sufficient for the expression of VCAM-1, expression of ICAM-1 showed a critical requirement for PARP-1. I-kappaBalpha phosphorylation and subsequent degradation were virtually identical in both TNF-treated wild-type and PARP-1-/- SMCs. VCAM-1 expression in TNF-treated PARP-1-/- SMCs was completely inhibited by the NF-kappaB inhibitor, pyrrolidine dithiocarbamate, confirming that VCAM-1 expression was indeed NF-kappaB-dependent. The expression of both VCAM-1 and ICAM-1 was associated with a transient interaction between PARP-1 and p65 NF-kappaB when examined in the fibroblastic cell line, COS-7, and in the airway epithelial cell line, A549. Such interactions were confirmed using florescence resonance energy transfer analysis. Protein acetylation activity, mediated by p300/CBP, was required for both VCAM-1 and ICAM-1 expression in TNF-treated SMCs; however, the interaction of PARP-1 with p300/CBP was dispensable for VCAM-1 expression. These findings indicate that p65 NF-kappaB nuclear translocation may be sufficient for certain genes (e.g., VCAM-1) while insufficient for others (e.g., ICAM-1), thus providing a novel insight into the role of NF-kappaB in driving target gene expression. Furthermore, the data suggest a differential requirement for PARP-1 expression in inflammatory processes.

Microvascular responses following digital thermal hyperaemia and iontophoresis measured by laser Doppler imaging in idiopathic inflammatory myopathy

OBJECTIVE

To measure microvascular function using laser Doppler imaging following digital hyperaemia and iontophoresis of vasoactive substances in patients with idiopathic inflammatory myopathy (IIM).

METHODS

Fifteen patients with IIM including eight patients with dermatomyositis (DM) and seven patients with polymyositis (PM) were studied. Fifteen age-matched normal controls were also recruited. Scanning red laser Doppler imaging (LDI) was performed after resting the subject in a temperature controlled room at 23 degrees C for 20 min. An initial LDI scan was performed to assess baseline blood flow. Digital microvascular responses were quantified following a maximum hyperaemic response (MHR) and iontophoresis with endothelial dependent acetylcholine (Ach) and endothelial independent sodium nitroprusside (SNP). Maximum vasodilation following iontophoresis was expressed as a percentage of the MHR.

RESULTS

All subjects were age matched, and the duration of disease was similar between the IIM patients. There was no significant difference in baseline blood flow when comparing the three study groups. There was no significant difference in MHR or SNP/MHR when comparing DM or PM with controls. However, Ach/MHR was significantly lower in both the DM and PM group compared with controls (both P < 0.01). There was no significant difference in any of the microvascular responses when comparing patients with DM directly with PM.

CONCLUSION

This is the first study to evaluate microvascular responses using LDI in patients with IIM. We have demonstrated that patients with DM have abnormal endothelial dependent mediated vasodilation and the same abnormality is present in patients with PM.

The heterogeneity of juvenile myositis

Juvenile myositis is a heterogeneous group of systemic autoimmune diseases, in which clinical and serologic subgroups result in subsets of patients with distinct clinical manifestations, disease courses, immunogenetic associations, responses to therapy, and prognoses. A newly identified autoantibody of unknown specificity, anti-p155, is myositis-associated and seen in up to 20-30% of juvenile and adult DM patients. HLA DRB1*0301 and its linked allele DQA1*0501 have been identified as the major immunogenetic risk factor for juvenile and adult DM in both European- and African-American patients, and DQA1*0301 is an additional risk factor in European-American patients. Several DQA1 alleles also are protective for juvenile DM. Environmental risk factors are poorly understood, but growing evidence suggests a role for infectious agents and ultraviolet radiation. The current therapy of juvenile DM consists of corticosteroids and other immunosuppressive agents, with the adjunctive treatment of cutaneous manifestations and rehabilitation. Therapeutic trials of biologic agents, including anti-TNFalpha and anti-CD20, may aid in developing promising new therapies for these disorders.