Extracutaneous involvement is common and associated with prolonged disease activity and greater impact in juvenile localized scleroderma.

OBJECTIVE: The aim of this study was to evaluate factors associated with extracutaneous involvement (ECI) in juvenile localized scleroderma (jLS). METHODS: A prospective, multicentre, 6-month observational study was performed. The data collected included disease features, global assessments, and subject symptoms. Bivariate and linear multilevel regression analyses were performed. RESULTS: A total of 86 jLS subjects (80% female, 80% Caucasian), median age of disease onset 7.7 years, were evaluated. Most had linear scleroderma or mixed morphea. Of the 86 subjects, 49 (57%) had 125 extracutaneous problems {median 2 [interquartile range (IQR) 1, 3] per subject} from nine organ systems. Most of these subjects had multiple musculoskeletal problems. ECI was associated with more extensive cutaneous involvement, higher number of symptoms, family history of autoimmunity, and ANA and RF positivity. Subjects with ECI had higher scores for physician global assessment of damage (PGA-D), and parental global assessment of disease impact, but not baseline physician global assessment of disease activity (PGA-A). Although subjects with ECI received more MTX and glucocorticoid treatment, they had a slower reduction in PGA-A scores and symptoms over time, suggesting a poorer response to treatment. In logistic regression modelling, female sex had the largest effect on parental impact scores. CONCLUSION: ECI occurred in the majority of subjects with jLS, and was associated with more medication use, longer treatment duration, higher PGA-D scores, and higher parental assessment of disease impact. Our findings suggest that jLS subjects with ECI have greater overall disease burden, both cutaneous and extracutaneous, and poorer response to treatment. More study of the treatment needs of this population is warranted.

Childhood Sjögren syndrome: features of an international cohort and application of the 2016 ACR/EULAR classification criteria.

OBJECTIVE: Sjögren syndrome in children is a poorly understood autoimmune disease. We aimed to describe the clinical and diagnostic features of children diagnosed with Sjögren syndrome and explore how the 2016 ACR/EULAR classification criteria apply to this population. METHODS: An international workgroup retrospectively collected cases of Sjögren syndrome diagnosed under 18 years of age from 23 centres across eight nations. We analysed patterns of symptoms, diagnostic workup, and applied the 2016 ACR/EULAR classification criteria. RESULTS: We identified 300 children with Sjögren syndrome. The majority of patients n = 232 (77%) did not meet 2016 ACR/EULAR classification criteria, but n = 110 (37%) did not have sufficient testing done to even possibly achieve the score necessary to meet criteria. Even among those children with all criteria items tested, only 36% met criteria. The most common non-sicca symptoms were arthralgia [n = 161 (54%)] and parotitis [n = 140 (47%)] with parotitis inversely correlating with age. CONCLUSION: Sjögren syndrome in children can present at any age. Recurrent or persistent parotitis and arthralgias are common symptoms that should prompt clinicians to consider the possibility of Sjögren syndrome. The majority of children diagnosed with Sjögren syndromes did not meet 2016 ACR/EULAR classification criteria. Comprehensive diagnostic testing from the 2016 ACR/EULAR criteria are not universally performed. This may lead to under-recognition and emphasizes a need for further research including creation of paediatric-specific classification criteria.

The catastrophic antiphospholipid syndrome in children.

PURPOSE OF REVIEW: To review the difficult syndrome of catastrophic antiphospholipid syndrome, emphasizing new developments in the diagnosis, pathogenesis and treatment. RECENT FINDINGS: Few recent publications directly address pediatric catastrophic antiphospholipid syndrome (CAPS). Most articles are case reports or are data from adult and pediatric registries. The major factors contributing to most pediatric catastrophic antiphospholipid syndrome include infection and the presence of antiphospholipid antibodies, but complement activation also is important in creating diffuse thrombosis in the microcirculation. Treatment of the acute emergency requires anticoagulation, suppression of the hyperinflammatory state and elimination of the triggering infection. Inhibition of complement activation appears to improve outcome in limited studies, and suppression of antiphospholipid antibody formation may be important in long-term management. SUMMARY: CAPS, an antibody-mediated diffuse thrombotic disease of microvasculature, is rare in childhood but has high mortality (33-50%). It requires prompt recognition and aggressive multimodality treatment, including anticoagulation, anti-inflammatory therapy and elimination of inciting infection and pathogenic autoantibodies.

Transcriptional profiles of JIA patient blood with subsequent poor response to methotrexate.

Objective: The mechanisms that determine the efficacy or inefficacy of MTX in JIA are ill-defined. The objective of this study was to identify a gene expression transcriptional signature associated with poor response to MTX in patients with JIA. Methods: RNA sequencing was used to measure gene expression in peripheral blood mononuclear cells collected from 47 patients with JIA prior to MTX treatment and 14 age-matched controls. Differentially expressed baseline genes between responders and non-responders were evaluated. Biological differences between all JIA patients and controls were explored by constructing a signature of differentially expressed genes. Unsupervised clustering and pathway analysis was performed. Results: A signature of 99 differentially expressed genes (Bonferroni-corrected P < 0.05) capturing the biological differences between all JIA patients and controls was identified. Unsupervised clustering of samples based on this list of 99 genes produced subgroups enriched for MTX response status. Comparing this gene signature with reference signatures from sorted cell populations revealed high concordance between the expression signatures of monocytes and of MTX non-responders. CXCL8 (IL-8) was the most significantly differentially expressed gene transcript comparing all JIA patients with controls (Bonferroni-corrected P = 4.12 × 10-10). Conclusion: Variability in clinical response to MTX in JIA patients is associated with differences in gene transcripts modulated in monocytes. These gene expression profiles may provide a basis for biomarkers predictive of treatment response.

National Institutes of Health Pathways to Prevention Workshop: Advancing the Research on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

The National Institutes of Health (NIH) Pathways to Prevention Workshop: Advancing the Research on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome was cosponsored by the NIH Office of Disease Prevention and the Trans-NIH Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Research Working Group. A multidisciplinary working group developed the agenda, and an Evidence-based Practice Center prepared an evidence report through a contract with the Agency for Healthcare Research and Quality to facilitate the discussion. During the 1.5-day workshop, invited experts discussed the body of evidence and attendees had the opportunity to comment during open discussions. After weighing evidence from the evidence report, expert presentations, and public comments, an unbiased, independent panel prepared a draft report that identified research gaps and future research priorities. The report was posted on the NIH Office of Disease Prevention Web site for 4 weeks for public comment.

Validation of the systemic lupus erythematosus responder index for use in juvenile-onset systemic lupus erythematosus.

OBJECTIVES: This study tested the concurrent validity of the systemic lupus erythematosus responder index (SRI) in assessing improvement in juvenile-onset systemic lupus erythematosus (jSLE). METHODS: The SRI considers changes in the SELENA-SLEDAI, BILAG and a 3-cm visual analogue scale of physician-rated disease activity (PGA) to determine patient improvement. Using prospectively collected data from 760 unique follow-up visit intervals of 274 jSLE patients, we assessed the sensitivity and specificity of the SRI using these external standards: physician-rated improvement (MD-change), patient/parent-rated major improvement of wellbeing (patient-change) and decrease in prescribed systemic corticosteroids (steroid-change). Modifications of the SRI that considered different thresholds for the SELENA-SLEDAI, BILAG and 10-cm PGA were explored and agreement with the American College of Rheumatology/PRINTO provisional criteria for improvement of jSLE (PCI) was examined. RESULTS: The sensitivity/specificity in capturing major improvement by the MD-change were 78%/76% for the SRI and 83%/78% for the PCI, respectively. There was fair agreement between the SRI and PCI (kappa=0.35, 95% CI 0.02 to 0.73) in capturing major improvement by the MD-change. Select modified versions of the SRI had improved accuracy overall. All improvement criteria tested had lower sensitivity when considering patient-change and steroid-change as external standards compared to MD-change. CONCLUSIONS: The SRI and its modified versions based on meaningful changes in jSLE have high specificity but at most modest sensitivity for capturing jSLE improvement. When used as an endpoint of clinical trials in jSLE, the SRI will provide a conservative estimate regarding the efficacy of the therapeutic agent under investigation.

Trial of early aggressive therapy in polyarticular juvenile idiopathic arthritis.

OBJECTIVE: To determine whether aggressive treatment initiated early in the course of rheumatoid factor (RF)-positive or RF-negative polyarticular juvenile idiopathic arthritis (JIA) can induce clinical inactive disease within 6 months. METHODS: Between May 2007 and October 2010, a multicenter, prospective, randomized, double-blind, placebo-controlled trial of 2 aggressive treatments was conducted in 85 children ages 2-16 years with polyarticular JIA of <12 months' duration. Patients received either methotrexate (MTX) 0.5 mg/kg/week (maximum 40 mg) subcutaneously, etanercept 0.8 mg/kg/week (maximum 50 mg), and prednisolone 0.5 mg/kg/day (maximum 60 mg) tapered to 0 by 17 weeks (arm 1), or MTX (same dosage as arm 1), etanercept placebo, and prednisolone placebo (arm 2). The primary outcome measure was clinical inactive disease at 6 months. An exploratory phase determined the rate of clinical remission on medication (6 months of continuous clinical inactive disease) at 12 months. RESULTS: By 6 months, clinical inactive disease had been achieved in 17 (40%) of 42 patients in arm 1 and 10 (23%) of 43 patients in arm 2 (χ(2) = 2.91, P = 0.088). After 12 months, clinical remission on medication was achieved in 9 patients in arm 1 and 3 patients in arm 2 (P = 0.053). There were no significant interarm differences in adverse events. CONCLUSION: Although this study did not meet its primary end point, early aggressive therapy in this cohort of children with recent-onset polyarticular JIA resulted in clinical inactive disease by 6 months and clinical remission on medication within 12 months of treatment in substantial proportions of patients in both arms.

Examination of proposed DSM-5 changes to pathological gambling in a helpline sample.

OBJECTIVES: To examine the effect of proposed the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) changes to pathological gambling relative to DSM-IV criteria in a large gambling helpline sample (N = 2,750). Changes in prevalence rates, the diagnostic utility of the illegal acts criterion, and severity of alternative diagnostic formulation thresholds were examined. METHOD: Callers to the helpline completed a semistructured interview and DSM-IV criteria were assessed. RESULTS: Without lowering the diagnostic threshold, removal of the illegal acts criterion resulted in loss of diagnostic status in less than 2% of helpline callers. The DSM-IV prevalence rate in this sample was 81.2%, and DSM-5 formulations with lowered thresholds of 4, 3, and 2 symptoms increased prevalence rates by 9% to 17%. However, item-level symptom endorsement suggested that subclinical gamblers experience significant adverse consequences. CONCLUSIONS: Lowered thresholds may lead to earlier provision of treatment to gamblers and prevent escalation of the disorder, while being more consistent with diagnostic thresholds of other addiction disorders.

Examining supervised meals in patients with restrictive eating disorders.

OBJECTIVES: Anorexia nervosa is a chronic, life-threatening illness affecting adolescents with increasing incidence. Previous research has demonstrated that, although weight gain is a key to medical stabilization, there is wide and significant variability in treatment practices. Meal supervision in hospitalized patients involves the use of clinical staff as active and supportive observers during meal time. No studies to date have examined the effects of meal supervision in medically hospitalized patients with anorexia nervosa. The primary aim of this study was to examine the effect of meal supervision on outcomes during inpatient medical hospitalization. METHODS: A retrospective record review of 52 patients with restrictive eating disorders admitted to a tertiary pediatric hospital from July 2008 to July 2009 was conducted. RESULTS: The data revealed higher average weights and improved overnight heart rate trends for patients who received at least 1 supervised meal during hospitalization compared with those who received no supervised meals. CONCLUSIONS: The findings warrant further investigation of meal supervision as a possible treatment modality.

Urinary HER2, TWEAK and VCAM-1 levels are associated with new-onset proteinuria in paediatric lupus nephritis.

OBJECTIVE: Lupus nephritis is a key driver of morbidity and mortality in SLE. Detecting active nephritis on a background of pre-existing renal damage is difficult, leading to potential undertreatment and accumulating injury. An unmet need is a biomarker that distinguishes active lupus nephritis, particularly important in paediatrics where minimising invasive procedures is desirable. METHODS: This was a multicentre, prospective study of 113 paediatric patients with biopsy-proven lupus nephritis. Clinical data and urine were obtained every 3-4 months and patients averaged 2 years on study with seven time points. Urine was analysed for human epidermal growth factor receptor 2 (HER2), tumour necrosis factor-like weak inducer of apoptosis and vascular cell adhesion molecule-1 (VCAM-1) by ELISA. We defined active disease as either a rise in serum creatinine ≥0.3 mg/dL from baseline or a rise in renal Systemic Lupus Erythematosus Disease Activity Index score from the previous visit. These markers were also studied in patients with acute kidney injury, juvenile idiopathic arthritis (JIA), amplified pain syndrome and healthy controls. RESULTS: The rate of active disease was 56% over an average of 2 years of follow-up. HER2 and VCAM-1 were significantly elevated at time points with active disease defined by increased serum creatinine compared with time points with inactive disease or patients who never flared. All three biomarkers were associated with new-onset proteinuria and VCAM-1 was elevated at time points preceding new-onset proteinuria. These biomarkers were not increased in acute kidney injury or JIA. CONCLUSION: All three biomarkers were associated with new onset proteinuria and increased VCAM-1 may predict impending proteinuria. These biomarkers provide potential non-invasive measures for monitoring that may be more sensitive to impending flare than conventional measures.

Consensus Treatment Plans for Severe Pediatric Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: There is no standardized approach to the treatment of pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Because of the rarity of pediatric AAV, randomized trials have not been feasible. The present study of the Childhood Arthritis and Rheumatology Research Alliance (CARRA) was undertaken to establish consensus treatment plans (CTPs) for severe pediatric AAV to enable the future study of comparative effectiveness and safety. METHODS: A workgroup of CARRA members (rheumatologists and nephrologists) formed the AAV Workgroup. This group performed a literature review on existing evidence-based treatments and guidelines for the management of AAV. They determined that the target population for CTP development was patients <18 years of age with new-onset granulomatosis with polyangiitis (GPA), microscopic polyangiitis, or renal-limited AAV (eosinophilic GPA was excluded), with presentation confined to those with severe disease (i.e., organ- or life-threatening). Face-to-face consensus conferences employed nominal group techniques to identify treatment strategies for remission induction and remission maintenance, data elements to be systematically collected, and outcomes to be measured over time. RESULTS: The pediatric AAV Workgroup developed 2 CTPs for each of the remission induction and remission maintenance of severe AAV. A glucocorticoid-weaning regimen for induction and maintenance, a core data set, and outcome measures were also defined. A random sample of CARRA membership voted acceptance of the CTPs for remission induction and remission maintenance, with a 94% (75 of 80) and 98% (78 of 80) approval rate, respectively. CONCLUSION: Consensus methodology established standardized CTPs for treating severe pediatric AAV. These CTPs were in principle accepted by CARRA-wide membership for the evaluation of pragmatic comparative effectiveness in a long-term registry.

Identifying Candidate Biomarkers of Ionizing Radiation in Human Pulmonary Microvascular Lumens Using Microfluidics-A Pilot Study.

The microvasculature system is critical for the delivery and removal of key nutrients and waste products and is significantly damaged by ionizing radiation. Single-cell capillaries and microvasculature structures are the primary cause of circulatory dysfunction, one that results in morbidities leading to progressive tissue and organ failure and premature death. Identifying tissue-specific biomarkers that are predictive of the extent of tissue and organ damage will aid in developing medical countermeasures for treating individuals exposed to ionizing radiation. In this pilot study, we developed and tested a 17 µL human-derived microvascular microfluidic lumen for identifying candidate biomarkers of ionizing radiation exposure. Through mass-spectrometry-based proteomics, we detected 35 proteins that may be candidate early biomarkers of ionizing radiation exposure. This pilot study demonstrates the feasibility of using humanized microfluidic and organ-on-a-chip systems for biomarker discovery studies. A more elaborate study of sufficient statistical power is needed to identify candidate biomarkers and test medical countermeasures of ionizing radiation.

EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura, childhood polyarteritis nodosa, childhood Wegener granulomatosis and childhood Takayasu arteritis: Ankara 2008. Part I: Overall methodology and clinical characterisation.

OBJECTIVES: To report methodology and overall clinical, laboratory and radiographic characteristics for Henoch-Schönlein purpura (HSP), childhood polyarteritis nodosa (c-PAN), c-Wegener granulomatosis (c-WG) and c-Takayasu arteritis (c-TA) classification criteria. METHODS: The preliminary Vienna 2005 consensus conference, which proposed preliminary criteria for paediatric vasculitides, was followed by a EULAR/PRINTO/PRES - supported validation project divided into three main steps. Step 1: retrospective/prospective web-data collection for HSP, c-PAN, c-WG and c-TA, with age at diagnosis

Progress in pediatric vasculitis.

PURPOSE OF REVIEW: To examine recent advances in the pathophysiology and therapy of pediatric vasculitis. RECENT FINDINGS: The past 2 years have been marked by significant progress in extending novel techniques to the investigation of the two most common pediatric vasculitis syndromes, Henoch-Schonlein purpura and Kawasaki disease. Study of other vasculitides, such as Wegener granulomatosis, Churg-Strauss syndrome, and microscopic polyangiitis, is impeded by the small number of pediatric patients. Nonetheless, national and international registries are beginning to provide the foundation for generation of testable hypotheses regarding pathogenesis and optimal treatment. Thus, recent data from the study of children suggest that disorders in the control of inflammation, such as those that underlie familial Mediterranean fever and other autoinflammatory diseases, may predispose to vasculitis. Improved knowledge of mechanisms of disease, in turn, should pave the way for more targeted, effective, and tolerable therapies for children with systemic vasculitis. SUMMARY: International collaboration to study rare disorders such as pediatric vasculitis are demonstrating disorders of inflammatory regulation that predispose to these diseases and may point toward new treatment approaches.

Neonatal-onset multisystem inflammatory disease responsive to interleukin-1beta inhibition.

BACKGROUND: Neonatal-onset multisystem inflammatory disease is characterized by fever, urticarial rash, aseptic meningitis, deforming arthropathy, hearing loss, and mental retardation. Many patients have mutations in the cold-induced autoinflammatory syndrome 1 (CIAS1) gene, encoding cryopyrin, a protein that regulates inflammation. METHODS: We selected 18 patients with neonatal-onset multisystem inflammatory disease (12 with identifiable CIAS1 mutations) to receive anakinra, an interleukin-1-receptor antagonist (1 to 2 mg per kilogram of body weight per day subcutaneously). In 11 patients, anakinra was withdrawn at three months until a flare occurred. The primary end points included changes in scores in a daily diary of symptoms, serum levels of amyloid A and C-reactive protein, and the erythrocyte sedimentation rate from baseline to month 3 and from month 3 until a disease flare. RESULTS: All 18 patients had a rapid response to anakinra, with disappearance of rash. Diary scores improved (P<0.001) and serum amyloid A (from a median of 174 mg to 8 mg per liter), C-reactive protein (from a median of 5.29 mg to 0.34 mg per deciliter), and the erythrocyte sedimentation rate decreased at month 3 (all P<0.001), and remained low at month 6. Magnetic resonance imaging showed improvement in cochlear and leptomeningeal lesions as compared with baseline. Withdrawal of anakinra uniformly resulted in relapse within days; retreatment led to rapid improvement. There were no drug-related serious adverse events. CONCLUSIONS: Daily injections of anakinra markedly improved clinical and laboratory manifestations in patients with neonatal-onset multisystem inflammatory disease, with or without CIAS1 mutations. (ClinicalTrials.gov number, NCT00069329 [ClinicalTrials.gov].).

Initial validation of a novel protein biomarker panel for active pediatric lupus nephritis.

Lupus nephritis (LN) is among the main determinants of poor prognosis in systemic lupus erythematosus (SLE). The objective of this study was to 1) isolate and identify proteins contained in the LN urinary protein signature (PS) of children with SLE; 2) assess the usefulness of the PS proteins for detecting activity of LN over time. Using surface-enhanced or matrix-assisted laser desorption/ionization time of flight mass spectrometry, the proteins contained in the LN urinary PS were identified. They were transferrin (Tf), ceruloplasmin (Cp), alpha1-acid-glycoprotein (AGP), lipocalin-type prostaglandin-D synthetase (L-PGDS), albumin, and albumin-related fragments. Serial plasma and urine samples were analyzed using immunonephelometry or ELISA in 98 children with SLE (78% African American) and 30 controls with juvenile idiopathic arthritis. All urinary PS proteins were significantly higher with active vs. inactive LN or in patients without LN (all p < 0.005), and their combined area under the receiver operating characteristic curve was 0.85. As early as 3 mo before a clinical diagnosis of worsening LN, significant increases of urinary Tf, AGP (both p < 0.0001), and L-PGDS (p < 0.01) occurred, indicating that these PS proteins are biomarkers of LN activity and may help anticipate the future course of LN.

Plasma exosomes from children with juvenile dermatomyositis are taken up by human aortic endothelial cells and are associated with altered gene expression in those cells.

BACKGROUND: The pathology of juvenile dermatomyositis (JDM) is characterized by prominent vessel wall and perivascular inflammation. This feature of the disease has remained unexplained and under-investigated. We have hypothesized that plasma exosomes, which play an important role in inter-cellular communication, may play a role in the vascular injury associated with JDM. OBJECTIVE: To characterize the circulating exosomes of children with JDM and determine whether the small RNA cargoes within those exosomes are capable of altering transcriptional programs within endothelial cells. DESIGN/METHODS: We purified exosomes from plasma samples of children with active, untreated JDM (n = 6) and healthy controls (n = 9). We characterized the small RNA cargoes in JDM and control exosomes by RNA sequencing using the Illumina HiSeq 2500 platform. We then incubated isolated exosomes from healthy controls and children with JDM with cultured human aortic endothelial cells (HAEC) for 24 h. Fluorescence microscopy was used to confirm that both control and JDM exosomes were taken up by HAEC. RNA was then purified from HAEC that had been incubated with either control or JDM exosomes and sequenced on the Illumina platform. Differential expression of mRNAs from HAEC incubated with control or JDM exosomes was ascertained using standard computational methods. Finally, we assessed the degree to which differential gene expression in HAEC could be attributed to the different small RNA cargoes in JDM vs control exosomes using conventional and novel analytic methods. RESULTS: We identified 10 small RNA molecules that showed differential abundance when we compared JDM and healthy control exosomes. Fluorescence microscopy of labeled exosomes confirmed that both JDM and control exosomes were taken up by HAEC. Differential gene expression analysis revealed 59 genes that showed differential expression between HAEC incubated with JDM exosomes vs HAEC incubated with exosomes from controls. Statistical analysis of gene expression data demonstrated that multiple miRNAs exerted transcriptional control on multiple genes with HAEC. CONCLUSIONS: Plasma exosomes from children with active, untreated JDM are taken up by HAEC and are associated with alterations in gene expression in those cells. These findings provide new insight into potential mechanisms leading to the targeting of vascular tissue by the immune system in JDM.

Systemic Lupus Erythematosus, Sjögren Syndrome, and Mixed Connective Tissue Disease in Children and Adolescents.

Juvenile systemic lupus erythematosus (jSLE), mixed connective tissue disease (jMCTD), and Sjögren syndrome (jSS) are systemic autoimmune and inflammatory disorders with distinct patterns of organ involvement. All are characterized by autoantibody formation, with antinuclear (ANA) and anti-double-stranded DNA common in jSLE, ANA with high-titer ribonucleoprotein antibody in jMCTD, and Sjögren syndrome A and Sjögren syndrome B antibodies + ANA in jSS. Recognition, monitoring, and management for primary care providers are discussed, focusing on the role of primary physicians in recognizing and helping maintain optimal health in children with these potentially life-threatening diseases.

Mycophenolic acid induces senescence of vascular precursor cells.

OBJECTIVE: Endothelial dysfunction is central to the pathogenesis of many rheumatic diseases, typified by vascular inflammation and damage. Immunosuppressive drugs induce disease remission and lead to improved patient survival. However, there remains a higher incidence of cardiovascular disease in these patients even after adequate disease control. The purpose of this study was to determine the effect of mycophenolic acid (MPA), a commonly used immunosuppressive drug in rheumatology, on blood vessel or circulating endothelial colony forming cell number and function. METHODS: We tested whether mycophenolic acid exerts an inhibitory effect on proliferation, clonogenic potential and vasculogenic function of endothelial colony forming cell. We also studied potential mechanisms involved in the observed effects. RESULTS: Treatment with MPA decreased endothelial colony forming cell proliferation, clonogenic potential and vasculogenic function in a dose-dependent fashion. MPA increased senescence-associated ß-galactosidase expression, p21 gene expression and p53 phosphorylation, indicative of activation of cellular senescence. Exogenous guanosine supplementation rescued diminished endothelial colony forming cell proliferation and indices of senescence, consistent with the known mechanism of action of MPA. CONCLUSION: Our findings show that clinically relevant doses of MPA have potent anti-angiogenic and pro-senescent effects on vascular precursor cells in vitro, thus indicating that treatment with MPA can potentially affect vascular repair and regeneration. This warrants further studies in vivo to determine how MPA therapy contributes to vascular dysfunction and increased cardiovascular disease seen in patients with inflammatory rheumatic disease.