Increased plasma thrombospondin-1 (TSP-1) levels are associated with the TNF alpha-308A allele in children with juvenile dermatomyositis

Update on Biomarkers of Vasculopathy in Juvenile and Adult Myositis

PURPOSE OF REVIEW

Although rare, idiopathic inflammatory myopathies (IIM) comprise a heterogeneous group of autoimmune conditions in adults and children. Increasingly, vasculopathy is recognised to be key in the underlying pathophysiology and plays a crucial role in some of the more challenging complications including calcinosis, gastrointestinal involvement and interstitial lung disease. The exciting prospect of development of biomarkers of vasculopathy would enable earlier detection and monitoring of these complications and possible prevention of their potentially devastating consequences. The purpose was to review the current literature on biomarkers of vasculopathy in IIM and offer insight as to the biomarkers most likely to have an impact on clinical care.

RECENT FINDINGS

Multiple candidate biomarkers have been studied including circulating endothelial cells (CEC), microparticles (MP), soluble adhesion markers (ICAM-1, ICAM-3, VCAM-1), selectin proteins (E-, L-, P-selectin), coagulation factors, angiogenic factors, cytokines (including (IL-6, IL-10, TNF-α, IL-18) and interferon (IFN)-related biomarkers (including IFNα, IFN-β, IFNγ, galectin-9, interferon signature and interferon-related chemokines (MCP-1, IP-10 and MIG). There is a growing body of evidence of the potential role of biomarkers in detecting and monitoring the vasculopathy in IIM, detecting disease activity and predicting disease flares and overall prognosis. Exciting progress has been made in the search for biomarkers of vasculopathy of IIM; however, none of the studies are validated and further research is required.

Biologics in refractory idiopathic inflammatory myositis (IIM): What experience in juvenile vs adult myositis tells us about the use of biologics in pediatric IIM

Juvenile dermatomyositis (JDM) is an extremely heterogeneous orphan disease with limited amount of dedicated research on the subject matter. Recent research suggests that JDM may not just be the classic antibody driven complements mediated microangiopathy as was thought to be in the past. The etiopathogenesis of JDM also involves inappropriate stimulation of innate immune system followed by dysregulation of the adaptive immune response through dendritic cells. Many variable immune factors such as genetics, major histocompatibility complex expressions, immunohistochemical variabilities, and diversity in specific and associated autoantibodies may make individual IIM and JDM cases unique. The diversity in IIM and JDM also explains individual variability in response to specific therapies. Classifying and matching the right patients to the right treatment is crucial to the successful treatment of these patients with better outcomes. Sub-type specific biologic therapy may be the best current treatment that can match the patient to the best treatment options. A PubMed search was performed to find all the available cases of refractory myositis patients treated with biologics up to July 2020. Using this search this article reviews all the current biologic treatment options and experiences for both adults and children in the context of recent basic science to assist pediatric rheumatologists in choosing the optimal biologic therapy for a child with recalcitrant JDM.

Endothelial and Inflammation Biomarker Profiles at Diagnosis Reflecting Clinical Heterogeneity and Serving as a Prognostic Tool for Treatment Response in Two Independent Cohorts of Patients With Juvenile Dermatomyositis

Objective

Juvenile dermatomyositis (DM) is a heterogeneous systemic immune‐mediated vasculopathy. This study was undertaken to 1) identify inflammation/endothelial dysfunction–related biomarker profiles reflecting disease severity at diagnosis, and 2) establish whether such biomarker profiles could be used for predicting the response to treatment in patients with juvenile DM.

Methods

In total, 39 biomarkers related to activation of endothelial cells, endothelial dysfunction, and inflammation were measured using multiplex technology in serum samples from treatment‐naive patients with juvenile DM from 2 independent cohorts (n = 30 and n = 29). Data were analyzed by unsupervised hierarchical clustering, nonparametric tests with correction for multiple comparisons, and Kaplan‐Meier tests with Cox proportional hazards models for analysis of treatment duration. Myositis‐specific antibodies (MSAs) were measured in the patients’ serum using line blot assays.

Results

Severe vasculopathy in patients with juvenile DM was associated with low serum levels of intercellular adhesion molecule 1 (Spearman's rho [r_s] = 0.465, P = 0.0111) and high serum levels of endoglin (r_s = −0.67, P < 0.0001). In the discovery cohort, unsupervised hierarchical clustering analysis of the biomarker profiles yielded 2 distinct patient clusters, of which the smaller cluster (cluster 1; n = 8) exhibited high serum levels of CXCL13, CCL19, galectin‐9, CXCL10, tumor necrosis factor receptor type II (TNFRII), and galectin‐1 (false discovery rate <0.0001), and this cluster had greater severity of muscle disease and global disease activity (each P < 0.05 versus cluster 2). In the validation cohort, correlations between the serum levels of galectin‐9, CXCL10, TNFRII, and galectin‐1 and the severity of global disease activity were confirmed (r_s = 0.40–0.52, P < 0.05). Stratification of patients according to the 4 confirmed biomarkers identified a cluster of patients with severe symptoms (comprising 64.7% of patients) who were considered at high risk of requiring more intensive treatment in the first 3 months after diagnosis (P = 0.0437 versus other cluster). Moreover, high serum levels of galectin‐9, CXCL10, and TNFRII were predictive of a longer total treatment duration (P < 0.05). The biomarker‐based clusters were not evidently correlated with patients’ MSA serotypes.

Conclusion

Results of this study confirm the heterogeneity of new‐onset juvenile DM based on serum biomarker profiles. Patients with high serum levels of galectin‐9, CXCL10, TNFRII, and galectin‐1 may respond suboptimally to conventional treatment, and may therefore benefit from more intensive monitoring and/or treatment.

Endothelial Activation Markers as Disease Activity and Damage Measures in Juvenile Dermatomyositis

OBJECTIVE

Circulating endothelial cells (CEC), von Willebrand factor (vWF) antigen, P-selectin, and thrombomodulin are released from damaged endothelium, while decreases in circulating endothelial progenitor cells (CEPC) have been associated with poor vascular outcomes. We examined these markers in the peripheral blood of patients with juvenile dermatomyositis (JDM) and their correlations with disease assessments.

METHODS

Peripheral blood endothelial cells and biomarkers were assessed in 20 patients with JDM and matched healthy controls. CEC and CEPC were measured by flow cytometry, while vWF antigen and activity, factor VIII, P-selectin, and thrombomodulin were measured in plate-based assays. Disease activity and damage, nailfold capillary density, and brachial artery flow dilation were assessed. Serum cytokines/chemokines were measured by Luminex.

RESULTS

CEC, vWF antigen, factor VIII, and thrombomodulin, but not vWF activity, CEPC, or P-selectin, were elevated in the peripheral blood of patients with JDM. CEC correlated with pulmonary activity (r_s = 0.56). The vWF antigen correlated with Patient's/Parent's Global, cutaneous, and extramuscular activity (r_s = 0.47-0.54). CEPC negatively correlated with muscle activity and physical function (r_s = -0.52 to -0.53). CEPC correlated inversely with endocrine damage. The vWF antigen and activity correlated with interleukin 10 and interferon-gamma inducible protein-10 (r_s = 0.64-0.82).

CONCLUSION

Markers of endothelial injury are increased in patients with JDM and correlate with extramuscular activity. CEPC correlate inversely with muscle activity, suggesting a functional disturbance in repair mechanisms.

Systemic and Tissue Inflammation in Juvenile Dermatomyositis: From Pathogenesis to the Quest for Monitoring Tools

Juvenile Dermatomyositis (JDM) is a systemic immune-mediated disease of childhood, characterized by muscle weakness, and a typical skin rash. Other organ systems and tissues such as the lungs, heart, and intestines can be involved, but may be under-evaluated. The inflammatory process in JDM is characterized by an interferon signature and infiltration of immune cells such as T cells and plasmacytoid dendritic cells into the affected tissues. Vasculopathy due to loss and dysfunction of endothelial cells as a result of the inflammation is thought to underlie the symptoms in most organs and tissues. JDM is a heterogeneous disease, and several disease phenotypes, each with a varying combination of affected tissues and organs, are linked to the presence of myositis autoantibodies. These autoantibodies have therefore been extensively studied as biomarkers for the disease phenotype and its associated prognosis. Next to identifying the JDM phenotype, monitoring of disease activity and disease-inflicted damage not only in muscle and skin, but also in other organs and tissues, is an important part of clinical follow-up, as these are key determinants for the long-term outcomes of patients. Various monitoring tools are currently available, among which clinical assessment, histopathological investigation of muscle and skin biopsies, and laboratory testing of blood for specific biomarkers. These investigations also give novel insights into the underlying immunological processes that drive inflammation in JDM and suggest a strong link between the interferon signature and vasculopathy. New tools are being developed in the quest for minimally invasive, but sensitive and specific diagnostic methods that correlate well with clinical symptoms or reflect local, low-grade inflammation. In this review we will discuss the types of (extra)muscular tissue inflammation in JDM and their relation to vasculopathic changes, critically assess the available diagnostic methods including myositis autoantibodies and newly identified biomarkers, and reflect on the immunopathogenic implications of identified markers.

Patients with anti-Jo1 antibodies display a characteristic IgG Fc-glycan profile which is further enhanced in anti-Jo1 autoantibodies

IgG Fc-glycans affect IgG function and are altered in autoimmune diseases and autoantibodies. Anti-histidyl tRNA synthetase autoantibodies (anti-Jo1) are frequent in patients with idiopathic inflammatory myopathies (IIM) and anti-synthetase syndrome (ASS) with associated interstitial lung disease (ILD). Thus, we hypothesized that the total-IgG Fc-glycans from Jo1⁺ versus Jo1⁻ patients and anti-Jo1-IgG would show characteristic differences, and that particular Fc-glycan features would be associated with specific clinical manifestations. By proteomics based mass spectrometry we observed a high abundance of agalactosylated IgG₁ Fc-glycans in ASS/IIM patients (n = 44) compared to healthy age matched controls (n = 24). Using intra-individual normalization of the main agalactosylated glycan (FA2) of IgG₁ vs FA2-IgG₂, ASS/IIM and controls were distinguished with an area under the curve (AUC) of 79 ± 6%. For Jo1⁺ patients (n = 19) the AUCs went up to 88 ± 6%. Bisected and afucosylated Fc-glycans were significantly lower in Jo1⁺ compared to Jo1⁻ patients. Anti-Jo1-IgG enriched from eleven patients contained even significantly lower abundances of bisected, afucosylated and galactosylated forms compared to matched total-IgG. ASS and ILD diagnosis, as well as lysozyme and thrombospondin correlated with Jo1⁺ characteristic Fc-glycan features. These results suggest that the anti-Jo1⁺ patient Fc-glycan profile contains phenotype specific features which may underlie the pathogenic role of Jo1 autoantibodies.

The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer's Disease

The early diagnosis of Alzheimer’s disease (AD) has become important to the reversal and treatment of neurodegeneration, which may be relevant to premature brain aging that is associated with chronic disease progression. Clinical proteomics allows the detection of various proteins in fluids such as the urine, plasma, and cerebrospinal fluid for the diagnosis of AD. Interest in lipidomics has accelerated with plasma testing for various lipid biomarkers that may with clinical proteomics provide a more reproducible diagnosis for early brain aging that is connected to other chronic diseases. The combination of proteomics with lipidomics may decrease the biological variability between studies and provide reproducible results that detect a community’s susceptibility to AD. The diagnosis of chronic disease associated with AD that now involves genomics may provide increased sensitivity to avoid inadvertent errors related to plasma versus cerebrospinal fluid testing by proteomics and lipidomics that identify new disease biomarkers in body fluids, cells, and tissues. The diagnosis of AD by various plasma biomarkers with clinical proteomics may now require the involvement of lipidomics and genomics to provide interpretation of proteomic results from various laboratories around the world.

TNFα induces inflammatory stress response in microvascular endothelial cells via Akt- and P38 MAP kinase-mediated thrombospondin-1 expression

Tumor necrosis factor-α (TNFα) and thrombospondin-1 (TSP-1) are well-known mediators of inflammation. However, a causal relationship between TNFα stimuli and TSP-1 expression in endothelial cell stress, and the underlying mechanisms has not yet been investigated. In our study, human microvascular endothelial cells (hMEC) were treated with TNFα and analyzed for endothelial dysfunction, TSP-1 expression, and associated mechanisms. TNFα treatment induced a dose-dependent increase in TSP-1 expression in hMEC associated with increased endothelial permeability, apoptosis, and reduced proliferation. Whereas TNFα activated Akt, ERK, and P38 mitogen-activated protein kinase (P38 MAPK) simultaneously in hMEC, inhibitors of Akt and P38 MAPK, but not ERK blunted TNFα-induced TSP-1 expression. Silencing of NFκB gene had no significant effect on TNFα-induced TSP-1 expression. Our study demonstrates the novel role of TNFα in inducing inflammatory stress response in hMEC through Akt- and P38 MAPK-mediated expression of TSP-1, independent of NFκB signaling.

Associations between TNF-α-308A/G polymorphism and susceptibility with dermatomyositis: a meta-analysis

Background

Some surveys had inspected the effects of the tumor necrosis factor-α (TNF-α)-308A/G polymorphism on susceptibility to dermatomyositis (DM), and showed mixed results. To briefly review these consequences, a comprehensive meta-analysis was carried out to estimate the relationship between them much more accurately.

Methods

Relevant documents dated to February 2014 were acquired from the PUBMED, MEDLINE, and EMBASE databases. The number of the genotypes and/or alleles for the TNF-α-308A/G in the DM and control subjects was extracted and statistical analysis was conducted using STATA 11.2 software. Summary odds ratios (ORs) with their 95% confidence intervals (95% CIs) were used to calculate the risk of DM with TNF-α-308A/G. Stratified analysis based on ethnicity and control population source was also performed.

Results

555 patients with DM and 1005 controls from eight published investigations were finally involved in this meta-analysis. Combined analysis revealed that the overall ORs for the TNF-α-308A allele were 2.041 (95% CIs 1.528–2.725, P<0.0001) in DM. Stratification by ethnicity indicated the TNF-α-308A allele polymorphism was found to be significantly associated with DM in Europeans (OR = 1.977, 95% CI 1.413–2.765, P<0.0001). The only study conducted on TNF-α-308A/G polymorphism in Asians could not be used in ethnicity-stratified meta-analysis. Meta-analysis of the AA+AG vs. GG (dominant model) and AA vs. GG (additive model) of this polymorphism revealed a significant association with DM in overall populations and Europeans.

Conclusions

Our meta-analysis demonstrated that the TNF-α-308A/G polymorphism in the TNF gene might contribute to DM susceptibility, especially in European population. However, further studies with large sample sizes and among different ethnicity populations should be required to verify the association.

New onset of dermatomyositis/polymyositis during anti-TNF-α therapies: a systematic literature review

We performed a systematic search of databases from 1990 to 2013 to identify articles concerning the new onset of dermatomyositis/polymyositis (DM/PM) in patients treated with anti-TNF-α therapy. We retrieved 13 publications describing 20 patients where the new onset of DM/PM after anti-TNF-α therapy was recorded. 17 patients were affected by rheumatoid arthritis (RA), one by Crohn's disease, one by ankylosing spondilytis, and one by seronegative arthritis. In 91% of the cases antinuclear autoantibodies were detected after the introduction of anti-TNF-α therapy. In 6 patients antisynthetase antibodies were detected and other clinical findings as interstitial lung disease (ILD) were recorded. Improvement of DM/PM after anti-TNF suspension (with the concomitant use of other immunosuppressors) was recorded in 94% of cases. The emergence of DM/PM and antisynthetase syndrome seem to be associated with the use of anti-TNF-α agents, especially in patients with chronic inflammatory diseases (mainly RA) with positive autoantibodies before therapy initiation. In particular, physicians should pay attention to patients affected by RA with positive antisynthetase antibodies and/or history of ILD. In those cases, the use of the TNF-α blocking agents may trigger the onset of PM/DM or antisynthetase syndrome or may aggravate/trigger the lung disease.

Age-associated induction of cell membrane CD47 limits basal and temperature-induced changes in cutaneous blood flow

OBJECTIVE

We tested the hypothesis that the matricellular protein thrombospondin-1 (TSP1), through binding to and activation of the cell receptor CD47, inhibits basal and thermal-mediated cutaneous blood flow.

BACKGROUND

Abnormal and decreased cutaneous blood flow in response to temperature changes or vasoactive agents is a feature of cardiovascular disease and aging. The reasons for decreased cutaneous blood flow remain incompletely understood. Furthermore, a role for matricellular proteins in the regulation skin blood flow has never been proposed.

METHODS

C57BL/6 wild type, TSP1-null, and CD47-null 12- and 72-week-old male mice underwent analysis of skin blood flow (SkBF) via laser Doppler in response to thermal stress and vasoactive challenge.

RESULTS

Young and aged TSP1- and CD47-null mice displayed enhanced basal and thermal sensitive SkBF changes compared with age-matched wild type controls. Nitric oxide-mediated increases in SkBF were also greater in null mice. TSP1 and CD47 were expressed in skin from young wild type mice, and both were significantly upregulated in aged animals. Tissue 3',5'-cyclic guanosine monophosphate, a potent vasodilator, was greater in skin samples from null mice compared with wild type regardless of age. Finally, treating wild type animals with a CD47 monoclonal antibody that inhibits TSP1 activation of CD47 enhanced SkBF in both young and aged animals.

CONCLUSIONS

These results suggest that secreted TSP1, via its cognate receptor CD47, acutely modulates SkBF. These data further support therapeutically targeting CD47 to mitigate age-associated loss of SkBF and maximize wound healing.

Juvenile dermatomyositis: new insights and new treatment strategies

Juvenile dermatomyositis (JDM) is a rare but complex and potentially life-threatening autoimmune disease of childhood, primarily affecting proximal muscles and skin. Although the cause of JDM remains unknown it is clear that genetic and environmental influences play a role in the aetiology. In contrast to adults with dermatomyositis, children with JDM are more likely to have complications that are thought to indicate a vasculopathic process, such as severe skin disease, with ulceration or calcinosis, gut vasculopathy or central nervous system disease. New treatments are much needed and are becoming available and being tested through international multicentre trials. This review will focus on recent insights into pathogenesis, the assessment of the disease in children and the modern approach to its treatment.

Clinical status and cardiovascular risk profile of adults with a history of juvenile dermatomyositis

OBJECTIVE

A pilot study of adults who had onset of juvenile dermatomyositis (JDM) in childhood, before current therapeutic approaches, to characterize JDM symptoms and subclinical cardiovascular disease.

STUDY DESIGN

Eight adults who had JDM assessed for disease activity and 8 healthy adults (cardiovascular disease controls) were tested for carotid intima media thickness and brachial arterial reactivity. Adults who had JDM and 16 age-, sex-, and body mass index-matched healthy metabolic controls were evaluated for body composition, blood pressure, fasting glucose, lipids, insulin resistance, leptin, adiponectin, proinflammatory oxidized high-density lipoprotein (HDL), and nail-fold capillary end row loops.

RESULTS

Adults with a history of JDM, median age 38 years (24-44 years) enrolled a median 29 years (9-38 years) after disease onset, had elevated disease activity scores, skin (7/8), muscle (4/8), and creatine phosphokinase (2/8). Compared with cardiovascular disease controls, adults who had JDM were younger, had lower body mass index and HDL cholesterol (P = .002), and increased intima media thickness (P = .015) and their brachial arterial reactivity suggested impairment of endothelial cell function. Compared with metabolic controls, adults who had JDM had higher systolic and diastolic blood pressure, P = .048, P = .002, respectively; lower adiponectin (P = .03); less upper arm fat (P = .008); HDL associated with end row loops loss (r = -0.838, P = .009); and increased proinflammatory oxidized HDL (P = .0037).

CONCLUSION

Adults who had JDM, 29 years after disease onset, had progressive disease and increased cardiovascular risk factors.

Thrombospondin-1, endothelium and systemic vascular tone

Evaluation of: Bauer EM, Qin Y, Miller TW et al.: Thrombospondin-1 supports blood pressure by limiting eNOS activation and endothelial dependent vasorelaxation. Cardiovasc. Res. 88, 471–481 (2010). Several lines of evidence, both in vivo and ex vivo, suggest that thrombospondin-1 (TSP-1) is important in maintaining systemic vascular tone. Recently published papers demonstrate that TSP-1 can inhibit vascular smooth muscle relaxation by interfering with the interaction between nitric oxide (NO) and soluble guanylyl cyclase, providing a possible mechanism of action to explain this observation. While these in vitro experiments in vascular smooth muscle cells were provocative, it is not clear how such a large protein circulating in the plasma could cross the intact endothelial basal membrane and regulate NO/cGMP signaling in smooth muscle in vivo. This raised the question of whether TSP-1 could modulate NO/cGMP signaling through another mechanism. Herein, we evaluate a recently published paper by Bauer and colleagues that examined whether TSP-1 could exert vasoactive effects without directly accessing the vascular smooth muscle. In their studies they found that TSP-1 could inhibit the NO/cGMP signaling pathway through an alternate mechanism: inhibiting the activation of endothelial NO synthase (eNOS), and therefore NO production in endothelial cells. These findings, combined with previous results from these investigators, suggest that TSP-1 can blunt NO/cGMP signaling through two different mechanisms: inhibiting NO production in endothelial cells by preventing the agonist-induced influx of Ca2+ required to activate endothelial NO synthase and blunting the ability of endothelial-derived NO to activate soluble guanylyl cyclase in vascular smooth muscle cells. The importance of these two pathways in supporting systemic and pulmonary vascular tone in health and disease is unclear.

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.

Thrombospondin-1 supports blood pressure by limiting eNOS activation and endothelial-dependent vasorelaxation

AIMS

Thrombospondin-1 (TSP1), via its necessary receptor CD47, inhibits nitric oxide (NO)-stimulated soluble guanylate cyclase activation in vascular smooth muscle cells, and TSP1-null mice have increased shear-dependent blood flow compared with wild-type mice. Yet, the endothelial basement membrane should in theory function as a barrier to diffusion of soluble TSP1 into the arterial smooth muscle cell layer. These findings suggested that endothelial-dependent differences in blood flow in TSP1-null mice may be the result of direct modulation of endothelial NO synthase (eNOS) activation by circulating TSP1. Here we tested the hypothesis that TSP1 inhibits eNOS activation and endothelial-dependent arterial relaxation.

METHODS AND RESULTS

Acetylcholine (ACh)-stimulated activation of eNOS and agonist-driven calcium transients in endothelial cells were inhibited by TSP1. TSP1 also inhibited eNOS phosphorylation at serine(1177). TSP1 treatment of the endothelium of wild-type and TSP1-null but not CD47-null arteries inhibited ACh-stimulated relaxation. TSP1-null vessels demonstrated greater endothelial-dependent vasorelaxation compared with the wild type. Conversely, TSP1-null arteries demonstrated less vasoconstriction to phenylephrine compared with the wild type, which was corrected upon inhibition of eNOS. In TSP1-null mice, intravenous TSP1 blocked ACh-stimulated decreases in blood pressure, and both intravenous TSP1 and a CD47 agonist antibody acutely elevated blood pressure in mice.

CONCLUSION

TSP1, via CD47, inhibits eNOS activation and endothelial-dependent arterial relaxation and limits ACh-driven decreases in blood pressure. Conversely, intravenous TSP1 and a CD47 antibody increase blood pressure. These findings suggest that circulating TSP1, by limiting endogenous NO production, functions as a pressor agent supporting blood pressure.

Association of normal nailfold end row loop numbers with a shorter duration of untreated disease in children with juvenile dermatomyositis

OBJECTIVE

To determine the association of normal numbers of end row loops (ERLs) in nailfold capillaries at the time of diagnosis of juvenile dermatomyositis (DM) with clinical findings in untreated children with the disease and to identify predictors of the development of decreased numbers of ERLs.

METHODS

Clinical and laboratory data from 80 untreated children with juvenile DM were collected. ERL numbers were recorded at the time of diagnosis and at 24 months and 36 months thereafter. The 12 children who had normal ERLs at diagnosis were compared with the remaining 68 children. Outcomes included the duration of untreated disease, the duration of treatment with immunosuppressive medications, family medical history, Disease Activity Score (DAS) for juvenile DM, creatinine phosphokinase level, aldolase level, absolute number of CD3-CD56+/16+ natural killer cells, and von Willebrand factor antigen level. Cross-sectional and longitudinal analyses were performed.

RESULTS

At diagnosis, children with normal ERLs had a shorter duration of untreated disease (P = 0.03) and a lower skin DAS (P = 0.045). Over time, an increased likelihood of having decreased numbers of ERLs was associated with a longer duration of untreated disease and with a higher skin DAS.

CONCLUSION

The presence of a normal number of ERLs in juvenile DM appears to be associated with a shorter duration of symptoms and may be a useful indicator of disease chronicity in the newly diagnosed child. Normal ERLs is also associated with a lower skin DAS. The lack of association between normal ERLs and other variables indicates that normal findings on nailfold capillaroscopy should not be used as justification to delay immunosuppressive therapy in children with typical symptoms of juvenile DM.

Immunopathogenesis of juvenile dermatomyositis

There is increasing evidence for involvement of the mechanisms of the innate immune system in the pathogenesis of idiopathic inflammatory myopathies (IIMs), especially in the adult and juvenile forms of dermatomyositis. Juvenile dermatomyositis (JDM) is the most common form of childhood IIM, and this review focuses on recent advances in understanding the actions of the innate immune system in this condition. Over the last few years, great strides have been made in understanding immune dysregulation in IIM, including JDM. Novel autoantibodies have been identified, and new genetic contributions have been described. Among the most striking findings is type I interferon activity in JDM tissue and peripheral blood. This is in conjunction with the description of dysregulation of the major histocompatibility complex (MHC) class I gene and identification of plasmacytoid dendritic infiltrates as the possible cellular source of type I interferons. These findings also point toward the potential prognostic value of muscle biopsies and have helped expand our understanding of the etiopathogenesis of IIM.

Dermatomyositis and polymyositis: Clinical presentation, autoantibodies, and pathogenesis

Dermatomyositis (DM) and polymyositis (PM) are autoimmune myopathies characterized clinically by proximal muscle weakness, muscle inflammation, extramuscular manifestations, and frequently, the presence of autoantibodies. Although there is some overlap, DM and PM are separate diseases with different pathophysiological mechanisms. Furthermore, unique clinical phenotypes are associated with each of the myositis-specific autoantibodies (MSAs) associated with these disorders. This review will focus on the clinical features, pathology, and immunogenetics of PM and DM with an emphasis on the importance of autoantibodies in defining unique phenotypes and, perhaps, as clues to help elucidate the mechanisms of disease.

Juvenile dermatomyositis: advances in pathogenesis, evaluation, and treatment

Juvenile dermatomyositis (JDM) is a rare, presumably autoimmune illness that causes proximal muscle weakness and a variety of typical cutaneous features. The study of this illness has been hampered by its rarity but, in recent years, important developments have increased our understanding of JDM. Genetic factors are likely important in the pathogenesis of JDM. These include several Human Leukocyte Antigen alleles, in particular those associated with the 8.1 ancestral haplotype and the tumor necrosis factor-alpha gene 308 polymorphism. Microchimerism, activation of plasmacytoid dendritic cells, and upregulation of type-1 interferon inducible genes also appear to play an important role in the pathogenesis of JDM. The study of JDM has also been limited by a lack of validated assessment tools. Recent work has validated the Childhood Myositis Assessment Scale and the Childhood Health Assessment Questionnaire as measures of muscle strength and function, and the Cutaneous Assessment Tool as a measure of skin disease activity and damage. Development of core sets of tools that should be used in all JDM studies has also been an important step. The use of magnetic resonance imaging and novel laboratory assessments (such as type-1 interferon inducible gene products, peripheral blood B cell and natural killer cell numbers, and myositis-associated and myositis-specific autoantibodies) are also playing an increasing role in the diagnosis and assessment of JDM. Current treatment is with corticosteroids, frequently in combination with other medications such as methotrexate or intravenous gammaglobulin. Newer therapies, such as anti-tumor necrosis factor agents and rituximab are currently being evaluated; it is not clear what role these medications will have in the future.

High serum levels of thrombospondin-1 in patients with idiopathic interstitial pneumonia

Thrombospondin-1 (TSP-1), a multifunctional matricellular glycoprotein, can activate transforming growth factor-beta, an important profibrotic cytokine involved in various fibrotic diseases. TSP-1 is expressed in the lung tissue of animal models of bleomycin-induced pulmonary fibrosis and in patients with some interstitial lung diseases. The present study investigated the serum and bronchoalveolar lavage fluid (BALF) levels of TSP-1 in the idiopathic interstitial pneumonias (IIPs) and the relationship between these levels and other clinical factors. The TSP-1 in the serum and BALF were measured in 45 patients with pathologically diagnosed IIPs [22 with usual interstitial pneumonia (UIP), 23 patients with non-specific interstitial pneumonia (NSIP)], as well as in 28 patients with pulmonary sarcoidosis and 15 healthy volunteers using a competitive enzyme immunoassay. The expression and localization of TSP-1 in the lungs were analyzed by immunohistochemical staining. The serum TSP-1 levels were significantly higher in patients with IIPs than in either those with sarcoidosis or the controls. These levels correlated well with those of an angiogenic cytokine vascular endothelial growth factor while correlating inversely with the %VC. Positive immunostaining of TSP-1 was predominantly observed in the regenerated alveolar epithelium and alveolar macrophages in the lung. Our findings suggest that the circulating TSP-1 levels are associated with the presence of interstitial pneumonia, but further studies are required before we can definitively conclude that TSP-1 plays a role in the pathogenesis of these diseases.

Persistent association of nailfold capillaroscopy changes and skin involvement over thirty-six months with duration of untreated disease in patients with juvenile dermatomyositis

OBJECTIVE

To determine the association of changes on nailfold capillaroscopy with clinical findings and genotype in children with juvenile dermatomyositis (DM), in order to identify potential differences in disease course over 36 months.

METHODS

At diagnosis of juvenile DM in 61 children prior to the initiation of treatment, tumor necrosis factor alpha (TNFalpha) -308 allele and DQA1*0501 status was determined, juvenile DM Disease Activity Scores (DAS) were obtained, and nailfold capillaroscopy was performed. The disease course was monitored for 36 months. Variations within and between patients were assessed by regression analysis.

RESULTS

At diagnosis, shorter duration of untreated disease (P = 0.05) and a lower juvenile DM skin DAS (P = 0.035) were associated with a unicyclic disease course. Over 36 months, end-row loop (ERL) regeneration was associated with lower skin DAS (P < 0.001) but not muscle DAS (P = 0.98); ERL regeneration and decreased bushy loops were associated with a shorter duration of untreated disease (P = 0.04 for both). At 36 months, increased ERL regeneration (P = 0.007) and improvement of skin DAS (P < 0.001) and muscle DAS (P = 0.025) were associated with a unicyclic disease course.

CONCLUSION

Early treatment of juvenile DM may lead to a unicyclic disease course. The non-unicyclic disease course usually involves continuing skin manifestations with persistent nailfold capillaroscopy changes. The correlation of nailfold capillaroscopy results with cutaneous but not with musculoskeletal signs of juvenile DM over a 36-month period suggests that the cutaneous and muscle vasculopathies have different pathophysiologic mechanisms. These findings indicate that efforts to identify the optimal treatment of cutaneous features in juvenile DM require greater attention.

Upregulation of thrombospondin-1(TSP-1) and its binding partners, CD36 and CD47, in sporadic inclusion body myositis

The TSP1/CD36/CD47-complex is involved in T cell expansion and inflammatory responses to beta-amyloid, both relevant to IBM. We report on the mRNA and protein expression of TSP1/ CD36 /CD47-complex in IBM muscles and in human myoblasts after cytokine stimulation. The TSP1/CD36 /CD47 was upregulated in IBM. TSP1 immunolocalized to the connective tissue contiguous to inflammation and CD36/CD47 on the myofibers and CD8+ cells. Further, TNF-alpha upregulated the production of TSP1 and CD47 by myoblasts. The TSP-complex is another inflammatory mediator associated with chronic inflammation in IBM that may perpetuate the immune responses to local antigens in response to TNF-alpha.

Inflammatory myopathies in children

Juvenile idiopathic inflammatory myopathies are rare conditions that are probably autoimmune in nature. Juvenile dermatomyositis (JDM) is the most common inflammatory myopathy. This article describes a recent patient who presented with typical JDM and uses her case to discuss aspects of the childhood inflammatory myopathies.

Have recent immunogenetic investigations increased our understanding of disease mechanisms in the idiopathic inflammatory myopathies?

PURPOSE OF REVIEW

The idiopathic inflammatory myopathies (IIM) continue to provide a challenge given the variable effectiveness of the available treatments, and immunogenetic studies are ongoing to further elucidate IIM disease mechanisms. This review examines how recent research has improved our understanding of the mechanisms that lead to IIM.

RECENT FINDINGS

HLA-DRB1 studies in a large homogenous cohort of UK Caucasian patients have confirmed that polymyositis (PM) and dermatomyositis (DM) are not genetically identical diseases while other studies have shown that tumor necrosis factor alpha is genetically implicated in disease susceptibility. Some remarkable results from an international collaboration, correlating gene-environment interactions, clearly suggest that ultraviolet light is capable of modulating both clinical and immunologic features of IIMs. Studies on microchimerism are unraveling interesting associations in juvenile DM patients, and bolstering the hypothesis that myositis may be an 'allo-immune' disease. mRNA gene expression profiling is helping to increase our understanding of myositis pathogenesis, whilst animal models have provided new information on the roles of Th1 responses and nitric oxide synthase in muscle disease. New candidate genes have been examined in inclusion body myositis (IBM), and a novel gene transfer experiment has been conducted, which led to significant changes in expression of the IBM phenotype.

SUMMARY

Improving the understanding of the immunogenetics and immunopathogenesis of the IIMs may in the future provide novel therapeutic targets, and thus improve outcomes in these difficult diseases.

Skin involvement in dermatomyositis

PURPOSE OF REVIEW

Dermatomyositis (DM) is a rare multisystem autoimmune disorder of adults and children that primarily affects skin and skeletal muscle. Classification systems of dermatomyositis, polymyositis, and the other idiopathic inflammatory myopathies focus primarily on features of muscle involvement. However, cutaneous disease does not always parallel muscle disease in its onset, activity, or response to therapy. This review will describe the distinct cutaneous clinical and histopathologic presentation of DM and the relation between these cutaneous findings, pathogenesis of DM, and serological subsets of DM.

RECENT FINDINGS

This review discusses recent findings that have begun to elucidate the pathogenesis of DM, including polymorphism of tumor necrosis factor-alpha 308A allele and maternal fetal microchimerism. The recent description of other systemic diseases and drugs causing DM-like eruptions and the recognition that DM can resemble other common dermatoses highlights the need for a cutaneous biopsy to diagnose and distinguish the cutaneous features of DM. Once diagnosed, a number of noninvasive imaging modalities and new cutaneous assessment instruments can be used to follow and evaluate patients with DM.

SUMMARY

Recognition of cutaneous and histopathologic findings in DM is essential for prompt and accurate diagnosis and treatment of DM.

Update on juvenile dermatomyositis: new advances in understanding its etiopathogenesis

PURPOSE OF REVIEW

Juvenile dermatomyositis is the most common of the idiopathic inflammatory myopathies in children. It is considered an autoimmune disease of relatively unknown etiology, although environmental exposures and infectious agents are thought to play a role in disease pathogenesis. More recently, data has become available regarding the molecular genetics of children affected with juvenile dermatomyositis and the impact these genes have on disease expression and clinical course. Additionally, features of the immune response, including specific pathways of the humoral and cellular immune systems, have been further described. This article summarizes the most recent advances in understanding the etiopathogenesis of juvenile dermatomyositis.

RECENT FINDINGS

This article focuses on advances made in understanding the role that complement, soluble adhesion molecules, thrombospondin-1 levels, and genetics play in the evolution of juvenile dermatomyositis. It also describes microarray technology and gene expression profiling as means of identifying those genes overexpressed in affected children and thus likely involved in disease pathogenesis; microarray technology may also be used to distinguish dermatomyositis from the other inflammatory myopathies, as well as from other myopathies.

SUMMARY

In better understanding the pathogenetic mechanisms whereby disease evolves and the means by which genetic profiles influence susceptibility to and expression of disease, immunotherapies to better treat juvenile dermatomyositis may become available in the future.