Using peripheral blood immune signatures to stratify patients with adult and juvenile inflammatory myopathies.

OBJECTIVE: The inflammatory idiopathic myopathies (IIM) are a group of rare autoimmune diseases defined by muscle weakness and characterized by pro-inflammatory infiltrates in muscle. Little is known about the immunological profile in peripheral blood of these patients and how this relates to IIM subtypes. This study aimed to stratify adult and juvenile-onset IIM patients according to immune cell profile. METHODS: Peripheral blood mononuclear cells from 44 patients with adult myositis (AM), 15 adolescent-onset juvenile dermatomyositis (a-JDM), and 40 age-matched healthy controls were analysed by flow cytometry to quantify 33 immune cell subsets. Adult myositis patients were grouped according to myositis subtype; DM and polymyositis; and also autoantibody specificity. Disease activity was determined by the myositis disease activity assessment tool and clinicians' decision on treatment. RESULTS: Unique immune signatures were identified for DM, polymyositis and a-JDM compared with healthy controls. DM patients had a T-cell signature comprising increased CD4+ and TH17 cell frequencies and increased immune cell expression of IL-6. Polymyositis patients had a B-cell signature with reduced memory B cells. A-JDM had decreased naïve B cells and increased CD4+T cells. All patient groups had decreased CD8+central memory T-cell frequencies. The distinct immune signatures were also seen when adult myositis patients were stratified according to auto-antibody expression; patients with anti-synthetase-antibodies had reduced memory B cells and patients with autoimmune rheumatic disease overlap had an elevated Th17 profile. CONCLUSION: Unique immune signatures were associated with adult vs juvenile disease. The Th17 signature in DM patients supports the potential use of IL-17 inhibitors in treatment of IIMs.

Normalization of Hepatic Homeostasis in the Npc1nmf164 Mouse Model of Niemann-Pick Type C Disease Treated with the Histone Deacetylase Inhibitor Vorinostat.

Niemann-Pick type C (NP-C) disease is a fatal genetic lipidosis for which there is no Food and Drug Administration (FDA)-approved therapy. Vorinostat, an FDA-approved inhibitor of histone deacetylases, ameliorates lysosomal lipid accumulation in cultured NP-C patient fibroblasts. To assess the therapeutic potential of histone deacetylase inhibition, we pursued these in vitro observations in two murine models of NP-C disease. Npc1nmf164 mice, which express a missense mutation in the Npc1 gene, were treated intraperitoneally, from weaning, with the maximum tolerated dose of vorinostat (150 mg/kg, 5 days/week). Disease progression was measured via gene expression, liver function and pathology, serum and tissue lipid levels, body weight, and life span. Transcriptome analyses of treated livers indicated multiple changes consistent with reversal of liver dysfunction that typifies NP-C disease. Significant improvements in liver pathology and function were achieved by this treatment regimen; however, NPC1 protein maturation and levels, disease progression, weight loss, and animal morbidity were not detectably altered. Vorinostat concentrations were >200 µm in the plasma compartment of treated animals but were almost 100-fold lower in brain tissue. Apolipoprotein B metabolism and the expression of key components of lipid homeostasis in primary hepatocytes from null (Npc1-/-) and missense (Npc1nmf164 ) mutant mice were altered by vorinostat treatment, consistent with a response by these cells independent of the status of the Npc1 locus. These results suggest that HDAC inhibitors have utility to treat visceral NP-C disease. However, it is clear that improved blood-brain barrier penetration will be required to alleviate the neurological symptoms of human NP-C disease.

Simultaneous Quantification of Bone Edema/Adiposity and Structure in Inflamed Bone Using Chemical Shift-Encoded MRI in Spondyloarthritis.

PURPOSE: To evaluate proton density fat fraction (PDFF) and R2* as markers of bone marrow composition and structure in inflamed bone in patients with spondyloarthritis. METHODS: Phantoms containing fat, water, and trabecular bone were constructed with proton density fat fraction (PDFF) and bone mineral density (BMD) values matching those expected in healthy bone marrow and disease states, and scanned using chemical shift-encoded MRI (CSE-MRI) at 3T. Measured PDFF and R2* values in phantoms were compared with reference FF and BMD values. Eight spondyloarthritis patients and 10 controls underwent CSE-MRI of the sacroiliac joints. PDFF and R2* in areas of inflamed bone and fat metaplasia in patients were compared with normal bone marrow in controls. RESULTS: In phantoms, PDFF measurements were accurate over the full range of PDFF and BMD values. R2* measurements were positively associated with BMD but also were influenced by variations in PDFF. In patients, PDFF was reduced in areas of inflammation and increased in fat metaplasia compared to normal marrow. R2* measurements were significantly reduced in areas of fat metaplasia. CONCLUSION: PDFF measurements reflect changes in marrow composition in areas of active inflammation and structural damage and could be used for disease monitoring in spondyloarthritis. R2* measurements may provide additional information bone mineral density but also are influenced by fat content. Magn Reson Med 79:1031-1042, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Depressive symptoms, pain and disability for adolescent patients with juvenile idiopathic arthritis: results from the Childhood Arthritis Prospective Study.

Objectives: To determine if depressive symptoms assessed near diagnosis associate with future measures of pain, disability and disease for adolescent patients diagnosed with JIA. Methods: Data were analysed from JIA patients aged 11-16 years recruited to the Childhood Arthritis Prospective Study, a UK-based inception cohort of childhood-onset arthritis. Depressive symptoms (using the Mood and Feelings Questionnaire; MFQ), active and limited joint count, disability score (Childhood Health Assessment Questionnaire), pain visual analogue scale and patient's general evaluation visual analogue scale were collected. Associations between baseline measures (first visit to paediatric rheumatologist) were analysed using multiple linear regression. Linear mixed-effect models for change in the clinical measures of disease over 48 months were estimated including MFQ as an explanatory variable. Results: Data from 102 patients were analysed. At baseline, median (IQR) age was 13.2 years (11.9-14.2 years) and 14.7% scored over the MFQ cut-off for major depressive disorder. At baseline, depressive symptoms significantly associated with all clinical measures of disease (P ⩽ 0.01). High baseline depressive symptoms scores predicted worse pain (P ⩽ 0.005) and disability (P ⩽ 0.001) 12 months later but not active and limited joint counts. Conclusions: Adolescent patients with JIA and depressive symptoms had more active joints, pain and disability at the time of their first specialist appointment. The associations between baseline depression and both pain and disability continued for at least one year, however, this was not the case for active joint count.

How common is clinically inactive disease in a prospective cohort of patients with juvenile idiopathic arthritis? The importance of definition.

OBJECTIVES: Many criteria for clinically inactive disease (CID) and minimal disease activity (MDA) have been proposed for juvenile idiopathic arthritis (JIA). It is not known to what degree each of these criteria overlap within a single patient cohort. This study aimed to compare the frequency of MDA and CID across different criteria in a cohort of children with JIA at 1 year following presentation. METHODS: The Childhood Arthritis Prospective Study recruits children at initial presentation to paediatric or adolescent rheumatology in seven UK centres. Children recruited between October 2001 and December 2013 were included. The proportions of children with CID and MDA at 1 year were calculated using four investigator-defined and eight published composite criteria. Missing data were accounted for using multiple imputation under different assumptions. RESULTS: In a cohort of 1415 children and adolescents, 67% patients had no active joints at 1 year. Between 48% and 61% achieved MDA and between 25% and 38% achieved CID using published criteria. Overlap between criteria varied. Of 922 patients in MDA by either the original composite criteria, Juvenile Arthritis Disease Activity Score (JADAS) or clinical JADAS cut-offs, 68% were classified as in MDA by all 3 criteria. Similarly, 44% of 633 children with CID defined by either Wallace's preliminary criteria or the JADAS cut-off were in CID according to both criteria. CONCLUSIONS: In a large JIA prospective inception cohort, a majority of patients have evidence of persistent disease activity after 1 year. Published criteria to capture MDA and CID do not always identify the same groups of patients. This has significant implications when defining and applying treat-to-target strategies.

Diffusion-weighted imaging is a sensitive biomarker of response to biologic therapy in enthesitis-related arthritis.

Objective: The aim was to evaluate diffusion-weighted imaging (DWI) as a tool for measuring treatment response in adolescents with enthesitis-related arthropathy (ERA). Methods: Twenty-two adolescents with ERA underwent routine MRI and DWI before and after TNF inhibitor therapy. Each patient's images were visually scored by two radiologists using the Spondyloarthritis Research Consortium of Canada system, and sacroiliac joint apparent diffusion coefficient (ADC) and normalized ADC (nADC) were measured for each patient. Therapeutic clinical response was defined as an improvement of ⩾ 30% physician global assessment and radiological response defined as ⩾ 2.5-point reduction in Spondyloarthritis Research Consortium of Canada score. We compared ADC and nADC changes in responders and non-responders using the Mann-Whitney-Wilcoxon test. Results: For both radiological and clinical definitions of response, reductions in ADC and nADC after treatment were greater in responders than in non-responders (for radiological response: ADC: P < 0.01; nADC: P = 0.055; for clinical response: ADC: P = 0.33; nADC: P = 0.089). ADC and nADC could predict radiological response with a high level of sensitivity and specificity and were moderately sensitive and specific predictors of clinical response (the area under the receiver operating characteristic curves were as follows: ADC: 0.97, nADC: 0.82 for radiological response; and ADC: 0.67, nADC: 0.78 for clinical response). Conclusion: DWI measurements reflect the response to TNF inhibitor treatment in ERA patients with sacroiliitis as defined using radiological criteria and may also reflect clinical response. DWI is more objective than visual scoring and has the potential to be automated. ADC/nADC could be used as biomarkers of sacroiliitis in the clinic and in clinical trials.

Trends in paediatric rheumatology referral times and disease activity indices over a ten-year period among children and young people with Juvenile Idiopathic Arthritis: results from the childhood arthritis prospective Study.

OBJECTIVES: The medical management of JIA has advanced significantly over the past 10 years. It is not known whether these changes have impacted on outcomes. The aim of this analysis was to identify and describe trends in referral times, treatment times and 1-year outcomes over a 10-year period among children with JIA enrolled in the Childhood Arthritis Prospective Study. METHODS: The Childhood Arthritis Prospective Study is a prospective inception cohort of children with new-onset inflammatory arthritis. Analysis included all children recruited in 2001-11 with at least 1 year of follow-up, divided into four groups by year of diagnosis. Median referral time, baseline disease pattern (oligoarticular, polyarticular or systemic onset) and time to first definitive treatment were compared between groups. Where possible, clinical juvenile arthritis disease activity score (cJADAS) cut-offs were applied at 1 year. RESULTS: One thousand and sixty-six children were included in the analysis. The median time from symptom onset and referral to first paediatric rheumatology appointment (22.7-24.7 and 3.4-4.7 weeks, respectively) did not vary significantly (∼20% seen within 10 weeks of onset and ∼50% within 4 weeks of referral). For oligoarticular and polyarticular disease, 33.8-47 and 25.4-34.9%, respectively, achieved inactive disease by 1 year, with ∼30% in high disease activity at 1 year. A positive trend towards earlier definitive treatment reached significance in oligoarticular and polyarticular pattern disease. CONCLUSION: Children with new-onset JIA have a persistent delay in access to paediatric rheumatology care, with one-third in high disease activity at 1 year and no significant improvement over the past 10 years. Contributing factors may include service pressures and poor awareness. Further research is necessary to gain a better understanding and improve important clinical outcomes.

Changes in regulation of human monocyte proteins in response to IgG from patients with antiphospholipid syndrome.

The effects of immunoglobulin G (IgG) from patients with the antiphospholipid syndrome (APS) upon monocyte activation have not been fully characterized. We carried out a comprehensive proteomic analysis of human monocytes treated with IgG from patients with different manifestations of the APS. Using 2-dimensional differential gel electrophoresis (2D DiGE), 4 of the most significantly regulated proteins (vimentin [VIM], zinc finger CCH domain-containing protein 18, CAP Gly domain-containing linker protein 2, and myeloperoxidase) were differentially regulated in monocytes treated with thrombotic or obstetric APS IgG, compared with healthy control (HC) IgG. These findings were confirmed by comparing monocytes isolated from APS patients and HC. Anti-VIM antibodies (AVAs) were significantly increased in 11 of 27 patients (40.7%) with APS. VIM expression on HC monocytes was stimulated more strongly by APS IgG from patients with higher-avidity serum AVA. We further characterized the proteome of thrombotic APS IgG-treated monocytes using a label-free proteomics technique. Of 12 proteins identified with the most confidence, 2 overlapped with 2D DiGE and many possessed immune response, cytoskeletal, coagulation, and signal transduction functions which are all relevant to APS and may therefore provide potential new therapeutic targets of this disease.

Association of the apparent diffusion coefficient with maturity in adolescent sacroiliac joints.

PURPOSE: To determine the extent to which apparent diffusion coefficient (ADC) values vary with skeletal maturity in adolescent joints. MATERIALS AND METHODS: A retrospective study was performed with Institutional Review Board (IRB) approval. We used a picture archiving and communication system (PACS) search to identify and recruit all adolescents who had undergone 1.5T magnetic resonance imaging (MRI) of the sacroiliac joints (SIJs) between January 2010 and June 2015, and had no evidence of sacroiliitis and normal inflammatory markers. In all, 55 individuals were assessed. For each patient, coronal and sagittal images of the sacrum were visually analyzed to determine sacral maturity. Patients were divided into three groups depending on the degree of fusion of the sacral segmental apophyses: "Fused," "Partial," and "Unfused." For each group, SIJ ADC was measured using a linear region-of-interest technique. RESULTS: Mean ADC values were 690 × 10(-6) mm(2) /s in the fused group, 720 × 10(-6) mm(2) /s in the partial group, and 842 × 10(-6) mm(2) /s in the unfused group. ADC values were significantly higher in the unfused group than in the fused group (P = 0.046). ADC values were also higher in unfused subjects than partially fused subjects (P = 0.074). CONCLUSION: Joint ADC values are higher in skeletally immature (unfused) patients than in skeletally more mature (fused) patients. ADC values measured in the unfused group overlap with those previously reported in sacroiliitis. These results suggest that ADC measurements in adolescent joints must be interpreted in light of joint maturity. Joint immaturity may lead to misdiagnosis of sacroiliitis, since immature juxta-articular bone may appear similar to inflammation. J. Magn. Reson. Imaging 2016. J. Magn. Reson. Imaging 2016;44:556-564.

Development of a high yield expression and purification system for Domain I of Beta-2-glycoprotein I for the treatment of APS.

BACKGROUND: In this paper we describe a novel method to achieve high yield bacterial expression of a small protein domain with considerable therapeutic potential; Domain I of Beta-2-glycoprotein I (ß2GPI). ß2GPI is intrinsic to the pathological progression of the Antiphospholipid Syndrome (APS). Patients develop autoantibodies targeting an epitope located on the N-terminal Domain I of ß2GPI rendering this domain of interest as a possible therapeutic. RESULTS: This new method of production of Domain I of ß2GPI has increased the production yield by ~20 fold compared to previous methods in E.coli. This largely scalable, partially automated method produces 50-75 mg of pure, folded, active Domain I of ß2GPI per litre of expression media. CONCLUSION: The application of this method may enable production of Domain I on sufficient scale to allow its use as a therapeutic.

Examining the prevalence of non-criteria anti-phospholipid antibodies in patients with anti-phospholipid syndrome: a systematic review.

OBJECTIVE: To systematically review and establish the prevalence of antibody positivity in assays not currently included in the APS classification criteria to detect antibodies directed against other phospholipids (PLs), PL binding proteins, coagulation factors and a mechanistic test for resistance of Annexin A5 (AnxA5) anticoagulant activity in APS and control populations. METHODS: We searched PubMed and EMBASE using the key words APS, antiphospholipid antibodies, non-criteria, new assays, IgA anticardiolipin antibodies, lupus anticoagulant, anti-Domain I, IgA anti-ß2-glycoprotein I antibodies, antiphosphatidylserine, anti-phosphatidylethanolamine, anti-phosphatidic acid, antiprothrombin, antiphosphatidylserine-prothtombin, anti-vimentin/cardiolipin complex and Annexin A5 resistance. Studies that met inclusion criteria to describe prevalence of non-criteria aPLs in APS patients (n > 10), disease and healthy control subjects were systematically examined. RESULTS: We selected 16 retrospective studies of 1404 APS patients, 1839 disease control and 797 healthy controls. The highest prevalence of non-criteria aPLs in the largest number of patients with APS was found in IgA anti-ß2GPI studies (129/229, 56.3%), AnxA5R (87/163, 53.4%) and IgG anti-Domain I (241/548, 44.0%). CONCLUSION: Our finding of a significantly high prevalence of all non-criteria aPLs studied in patients with APS compared with controls was tempered by wide variation in sample size, retrospective collection, assay methodology and different determination of positivity. Therefore, prospective studies of sufficient size and appropriate methodology are required to evaluate the significance of these assays and their utility in the management of patients with APS.

Proof-of-concept study demonstrating the pathogenicity of affinity-purified IgG antibodies directed to domain I of ß2-glycoprotein I in a mouse model of anti-phospholipid antibody-induced thrombosis.

OBJECTIVE: IgG aPL against domain I of ß2-glycoprotein I (ß2GPI) [anti-DI (aDI)] is associated with the pathogenesis of APS, an autoimmune disease defined by thrombosis and pregnancy morbidity. To date, however, no study has demonstrated direct pathogenicity of IgG aDI in vivo. In this proof-of-concept study, we designed a novel system to affinity purify polyclonal aDI aPL in order to assess its prothrombotic ability in a well-characterized mouse microcirculation model for APS. METHODS: Two polyclonal IgG fractions were isolated from serum of a patient with APS, both with high aPL activity but differing in aDI activity (aDI-rich and aDI-poor). These IgG fractions were tested for their pathogenic ability in an in vivo mouse model of thrombosis. Male CD1 mice were injected intraperitoneally with either aDI-rich or aDI-poor IgG; as a control, IgG isolated from healthy serum was used. A pinch injury was applied to the right femoral vein and thrombus dynamics and tissue factor activity in isolated tissue were evaluated. RESULTS: Both aDI-rich and aDI-poor IgG retained aCL and anti-ß2GPI activity, while only aDI-rich IgG displayed high aDI activity, as defined by our in-house cut-offs for positivity in each assay. aDI-rich IgG induced significantly larger thrombi in vivo compared with aDI-poor IgG (P < 0.0001). Similarly, aDI-rich IgG significantly enhanced the procoagulant activity of carotid artery endothelium and peritoneal macrophages isolated from experimental animals (P < 0.01). CONCLUSION: These data directly demonstrate that the ability to cause thrombosis in vivo is concentrated in the aDI fraction of aPL.

PEGylated drugs in rheumatology--why develop them and do they work?

Lack of efficacy and drug-related adverse effects are important reasons for the discontinuation of treatment in patients with rheumatic diseases. The development of new biologic therapies seeks to address these problems by specifically targeting the pathogenic mechanisms of disease. Most current biologics are proteins (particularly antibodies and enzymes) administered parenterally. It is important to optimize properties such as serum half-life, immunogenicity and solubility. Companies have thus begun to modify the drugs by conjugate chemistry, binding inert molecules such as polyethylene glycol (PEG) to biologic molecules to improve their pharmacodynamic properties. The use of PEG to alter these properties has to be weighed against the negative aspects of PEGylation, such as decreased activity and heterogeneity. This review focuses on the currently available PEGylated drugs used in rheumatological diseases, their efficacy, drawbacks and the current clinical trial evidence supporting their use.

A comparison of the outcome of adolescent and adult-onset systemic lupus erythematosus.

OBJECTIVE: Previous reports have suggested that juvenile-onset SLE is associated with a worse prognosis than adult-onset disease. There have been limited studies in adolescents. We sought to assess the effect of adolescent-onset SLE on the clinical course of a large multi-ethnic cohort. METHODS: Patients consisted of individuals diagnosed with SLE between 11 and 18 years of age in a tertiary referral centre. All patients with adult-onset disease were used as controls. Data were analysed by univariable and multivariable analysis for demographic, clinical and serological data. RESULTS: One hundred and twenty-four patients with adolescent-onset and 484 patients with adult-onset disease were identified. There was a higher percentage of males (12.9% vs 7.2%; P = 0.036) and patients of Asian ethnicity within the adolescent group (P < 0.01). By univariable analysis, adolescent-onset SLE was associated with more frequent LN and haemolytic anaemia and less serositis and SS. Ischaemic vascular events occurred in 32 adult-onset patients (6.6%) and 3 adolescent-onset patients (2.4%; P = 0.08). Thirty-five adult-onset patients developed cancer (6.8%) compared with five of the adolescent-onset group (4.8%; P = 0.54). The standardized mortality rate was significantly increased in females with adolescent-onset SLE (14.4; 95% CI 4.44, 24.4) compared with patients with adult-onset SLE. By multivariable analysis, adolescent-onset SLE retained a significant association with LN. CONCLUSION: Adolescent-onset SLE is associated with a significantly increased risk of LN and, importantly, with a marked increase in mortality. These data suggest a more aggressive phenotype of disease in patients with onset of SLE in adolescence and supports the need for intensive follow-up and intensive therapy in this population.

Mucocutaneous manifestations in a UK national cohort of juvenile-onset systemic lupus erythematosus patients.

OBJECTIVE: To determine whether mucocutaneous manifestations are associated with major organ involvement in a UK national cohort of juvenile-onset SLE (JSLE) patients. METHODS: JSLE patients (n = 241) from 15 different centres whose diagnosis fulfilled four or more of the ACR criteria were divided into two groups: those with at least one ACR mucocutaneous criterion (ACR skin feature positive) and those without (ACR skin feature negative) at diagnosis. The relative frequency of skin involvement was described by the paediatric adaptation of the 2004 British Isles Lupus Assessment Group (pBILAG-2004) index. RESULTS: One hundred and seventy-nine patients (74%) had ACR-defined skin involvement with no significant demographic differences compared with those without. ACR skin feature negative patients showed greater haematological (84% vs 67%), renal (43% vs 26%) (P < 0.05) and neurological (16% vs 4%) involvement (P = 0.001). Forty-two per cent of ACR skin feature negative patients had skin involvement using pBILAG-2004, which included maculopapular rash (17%), non-scaring alopecia (15%), cutaneous vasculitis (12%) and RP (12%). ACR skin feature negative patients with moderate to severe skin involvement by pBILAG-2004 showed greater renal and haematological involvement at diagnosis and over the follow-up period (P < 0.05). Higher immunosuppressive drug use in the skin feature negative group was demonstrated. CONCLUSION: Patients who fulfil the ACR criteria but without any of the mucocutaneous criteria at diagnosis have an increased risk of major organ involvement. The pBILAG-2004 index has shown that other skin lesions may go undetected using the ACR criteria alone, and these lesions show a strong correlation with disease severity and major organ involvement.

Disease activity, severity, and damage in the UK Juvenile-Onset Systemic Lupus Erythematosus Cohort.

OBJECTIVE: The UK Juvenile-Onset Systemic Lupus Erythematosus (JSLE) Cohort Study is a multicenter collaborative network established with the aim of improving the understanding of juvenile SLE. The present study was undertaken to describe the clinical manifestations and disease course in patients with juvenile SLE from this large, national inception cohort. METHODS: Detailed data on clinical phenotype were collected at baseline and at regular clinic reviews and annual followup assessments in 232 patients from 14 centers across the UK over 4.5 years. Patients with SLE were identified according to the American College of Rheumatology (ACR) SLE classification criteria. The present cohort comprised children with juvenile SLE (n=198) whose diagnosis fulfilled ≥4 of the ACR criteria for SLE. RESULTS: Among patients with juvenile SLE, the female:male sex distribution was 5.6:1 and the median age at diagnosis was 12.6 years (interquartile range 10.4-14.5 years). Male patients were younger than female patients (P<0.01). Standardized ethnicity data demonstrated a greater risk of juvenile SLE in non-Caucasian UK patients (P<0.05). Scores on the pediatric adaptation of the 2004 British Isles Lupus Assessment Group disease activity index demonstrated significantly increased frequencies of musculoskeletal (82%), renal (80%), hematologic (91%), immunologic (54%), and neurologic (26%) involvement among the patients over time. A large proportion of the patients (93%) were taking steroids and 24% of the patients required treatment with cyclophosphamide. Disease damage was common, with 28% of the patients having a Systemic Lupus International Collaborating Clinics/ACR damage score of ≥1. CONCLUSION: The data on these patients from the UK JSLE Cohort Study, comprising one of the largest national inception cohorts of patients with juvenile SLE to date, indicate that severe organ involvement and significant disease activity are primary characteristics in children with juvenile SLE. In addition, accumulation of disease-associated damage could be seen.

Incidence of Antiphospholipid Syndrome: Is Estimation Currently Possible?

Antiphospholipid syndrome is a systemic autoimmune disorder characterized by vascular thrombosis and/or obstetric events in association with persistently elevated antiphospholipid antibodies. Antiphospholipid syndrome is typically considered a rare disease, but the true incidence is uncertain owing to the diverse antiphospholipid antibody-related clinical manifestations, inconsistent definitions of antiphospholipid antibody positivity, under-recognition of the disease, and limited population-based studies. Published estimates of the incidence of antiphospholipid syndrome range from approximately 2 to 80 per 100 000 person-years. A targeted literature review and applied methodology were performed to derive a best available estimate. Significant limitations of the published literature were observed, some of which have been previously reported. The incidence of antiphospholipid syndrome in the United States was estimated to be approximately 7.1 to 13.7 per 100 000 person-years in the general population. Although this estimate is likely more accurate than previously reported estimates, large, contemporary, population-based studies that reasonably adhere to the antiphospholipid syndrome classification criteria are needed to further refine estimates of the incidence of antiphospholipid syndrome.

An "exacerbate-reverse" strategy in yeast identifies histone deacetylase inhibition as a correction for cholesterol and sphingolipid transport defects in human Niemann-Pick type C disease.

Niemann-Pick type C (NP-C) disease is a fatal lysosomal lipid storage disorder for which no effective therapy exists. A genome-wide, conditional synthetic lethality screen was performed using the yeast model of NP-C disease during anaerobiosis, an auxotrophic condition that requires yeast to utilize exogenous sterol. We identified 12 pathways and 13 genes as modifiers of the absence of the yeast NPC1 ortholog (NCR1) and quantified the impact of loss of these genes on sterol metabolism in ncr1Δ strains grown under viable aerobic conditions. Deletion of components of the yeast NuA4 histone acetyltransferase complex in ncr1Δ strains conferred anaerobic inviability and accumulation of multiple sterol intermediates. Thus, we hypothesize an imbalance in histone acetylation in human NP-C disease. Accordingly, we show that the majority of the 11 histone deacetylase (HDAC) genes are transcriptionally up-regulated in three genetically distinct fibroblast lines derived from patients with NP-C disease. A clinically approved HDAC inhibitor (suberoylanilide hydroxamic acid) reverses the dysregulation of the majority of the HDAC genes. Consequently, three key cellular diagnostic criteria of NP-C disease are dramatically ameliorated as follows: lysosomal accumulation of both cholesterol and sphingolipids and defective esterification of LDL-derived cholesterol. These data suggest HDAC inhibition as a candidate therapy for NP-C disease. We conclude that pathways that exacerbate lethality in a model organism can be reversed in human cells as a novel therapeutic strategy. This "exacerbate-reverse" approach can potentially be utilized in any model organism for any disease.

Niemann-Pick C proteins in sterol transport and absorption: flies in the ointment.

The Niemann-Pick C proteins have slowly emerged as regulators of subcellular lipid transport and sterol absorption at the small intestine. A recent article in Cell Metabolism suggests that in addition to their significant structural and sequence homology, these proteins may orchestrate their functions in a previously unappreciated fashion (Voght et al., 2007).

The Michael Mason Prize: Pathogenic antiphospholipid antibodies, stressed out antigens and the deployment of decoys.

The antiphospholipid syndrome is a common autoimmune cause of vascular thrombosis and recurrent miscarriages. aPLs that target the N-terminal domain [Domain I (DI)] of the phospholipid binding protein ß2-glycoprotein I (ß2GPI) represent the key sub-population of aPLs that promote thrombosis. This review describes two research arms relating to the study of this autoantigen. The first arm describes recent novel biochemical and functional insights into the molecular structure of ß2GPI in vivo and how this may be altered in APS. These findings support the emerging hypothesis that redox modification of ß2GPI may be relevant to the pathogenesis of APS and the development of pathogenic anti-ß2GPI antibodies. The second arm describes how a recombinant DI peptide engineered using a bacterial expression system was used to delineate the fine immunodominant epitopes on DI that pathogenic anti-ß2GPI antibodies target. The epitope was found to be conformational and revolve around arginine (R) 39 within DI. Thus, whole recombinant DI was used in an in vivo mouse model as a novel decoy peptide inhibitor of anti-ß2GPI antibodies. DI and a high binding mutant completely abrogated the pathogenic effects of aPL in this murine model, with loss of inhibition of pathogenicity observed upon mutating the residue R39 to serine. This proof-of-principle study supports the ongoing development of recombinant DI as a novel therapeutic inhibitory peptide for patients with APS.