Search

Objective: Deficiency of adenosine deaminase 2 (DADA2) is a monogenic form of vasculitis that can resemble polyarteritis nodosa (PAN). This study was undertaken to identify potential disease-causing sequence variants in ADA2 in patients with idiopathic PAN, granulomatosis with polyangiitis (GPA), or microscopic polyangiitis (MPA)., Methods: Patients with idiopathic PAN (n = 118) and patients with GPA or MPA (n = 1,107) were screened for rare nonsynonymous variants in ADA2 using DNA sequencing methods. ADA-2 enzyme activity was assessed in selected serum samples., Results: Nine of 118 patients with PAN (7.6%) were identified as having rare nonsynonymous variants in ADA2. Four patients (3.4%) were biallelic for pathogenic or likely pathogenic variants, and 5 patients (4.2%) were monoallelic carriers for 3 variants of uncertain significance and 2 likely pathogenic variants. Serum samples from 2 patients with PAN with biallelic variants were available and showed markedly reduced ADA-2 enzyme activity. ADA-2 enzyme testing of 86 additional patients revealed 1 individual with strongly reduced ADA-2 activity without detectable pathogenic variants. Patients with PAN and biallelic variants in ADA2 were younger at diagnosis than patients with 1 or no variant in ADA2, with no other clinical differences noted. None of the patients with GPA or MPA carried biallelic variants in ADA2., Conclusion: A subset of patients with idiopathic PAN meet genetic criteria for DADA2. Given that tumor necrosis factor inhibition is efficacious in DADA2 but is not conventional therapy for PAN, these findings suggest that ADA-2 testing should strongly be considered in patients with hepatitis B virus-negative idiopathic PAN., (© 2020 American College of Rheumatology. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)

Objective: To examine the association between macrophage migration inhibitory factor (MIF) promoter polymorphisms and granulomatosis with polyangiitis (GPA) in human subjects, and to assess the role of MIF in a murine model of granulomatous vasculitis., Methods: The human study involved 1,077 patients with GPA and healthy controls whose serum was genotyped by capillary electrophoresis for the MIF -794 CATT 5-8 promoter microsatellite (rs5844572). MIF promoter, CATT-length-dependent gene expression in response to β-glucan was assessed by gene reporter assays. In mouse studies, granulomatous disease was induced by injection of Candida albicans β-glucan into wild-type (WT) or Mif-knockout (Mif-KO) C57BL/6 mice and C57BL/6 mice transgenically overexpressing Mif in lung epithelium (Mif lung-Tg2.1). Mice were treated with a neutralizing anti-MIF antibody and analyzed for the density of pulmonary granulomas, expression of inflammatory chemokines, and frequency of mortality., Results: The percentage of human subjects carrying >5 CATT repeats in each MIF allele (high genotypic MIF expressers) was 60.2% among patients with GPA and 53.9% among healthy controls (adjusted P = 0.049). In response to granulomatous stimulation, human MIF gene expression increased proportionally with CATT length. Mif lung-Tg2.1 mice exhibited more pulmonary granulomas than WT mice, which in turn showed more granulomas than Mif-KO mice. A significantly higher percentage of Mif lung-Tg2.1 mice, compared to Mif-KO or WT mice, died when injected with Candida albicans β-glucan, and treatment of these mice with an anti-MIF monoclonal antibody protected against a lethal outcome. Levels of MIF-dependent neutrophil/macrophage chemokines were elevated in the bronchoalveolar lavage fluid or plasma of Mif lung-Tg2.1 mice., Conclusion: Patients with GPA have an increased frequency of high MIF expression CATT alleles. Higher Mif expression increases the incidence of mortality and pulmonary granulomas in Mif lung-Tg2.1 mice, while anti-MIF treatment protects these mice against death. Blockade of MIF in high genotypic MIF expressers may therefore offer a selective pharmacologic therapy for GPA., (© 2018, American College of Rheumatology.)

Objective: To identify risk alleles relevant to the causal and biologic mechanisms of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV)., Methods: A genome-wide association study and subsequent replication study were conducted in a total cohort of 1,986 cases of AAV (patients with granulomatosis with polyangiitis [Wegener's] [GPA] or microscopic polyangiitis [MPA]) and 4,723 healthy controls. Meta-analysis of these data sets and functional annotation of identified risk loci were performed, and candidate disease variants with unknown functional effects were investigated for their impact on gene expression and/or protein function., Results: Among the genome-wide significant associations identified, the largest effect on risk of AAV came from the single-nucleotide polymorphism variants rs141530233 and rs1042169 at the HLA-DPB1 locus (odds ratio [OR] 2.99 and OR 2.82, respectively) which, together with a third variant, rs386699872, constitute a triallelic risk haplotype associated with reduced expression of the HLA-DPB1 gene and HLA-DP protein in B cells and monocytes and with increased frequency of complementary proteinase 3 (PR3)-reactive T cells relative to that in carriers of the protective haplotype. Significant associations were also observed at the SERPINA1 and PTPN22 loci, the peak signals arising from functionally relevant missense variants, and at PRTN3, in which the top-scoring variant correlated with increased PRTN3 expression in neutrophils. Effects of individual loci on AAV risk differed between patients with GPA and those with MPA or between patients with PR3-ANCAs and those with myeloperoxidase-ANCAs, but the collective population attributable fraction for these variants was substantive, at 77%., Conclusion: This study reveals the association of susceptibility to GPA and MPA with functional gene variants that explain much of the genetic etiology of AAV, could influence and possibly be predictors of the clinical presentation, and appear to alter immune cell proteins and responses likely to be key factors in the pathogenesis of AAV., (© 2016 The Authors. Arthritis & Rheumatology published by Wiley Periodicals, Inc. on behalf of American College of Rheumatology.)

Objective: To compare the efficacy of abatacept to that of placebo for the treatment of giant cell arteritis (GCA)., Methods: In this multicenter trial, patients with newly diagnosed or relapsing GCA were treated with abatacept 10 mg/kg intravenously on days 1, 15, and 29 and week 8, together with prednisone administered daily. At week 12, patients in remission underwent a double-blinded randomization to continue to receive abatacept monthly or switch to placebo. Patients in both study arms received a standardized prednisone taper, with discontinuation of prednisone at week 28. All patients remained on their randomized assignment until meeting criteria for early termination or until 12 months after enrollment of the last patient. The primary end point was duration of remission (relapse-free survival rate)., Results: Forty-nine eligible patients with GCA were enrolled and treated with prednisone and abatacept; of these, 41 reached the week 12 randomization and underwent a blinded randomization to receive abatacept or placebo. Prednisone was tapered using a standardized schedule, reaching a daily dosage of 20 mg at week 12 with discontinuation in all patients at week 28. The relapse-free survival rate at 12 months was 48% for those receiving abatacept and 31% for those receiving placebo (P = 0.049). A longer median duration of remission was seen in those receiving abatacept compared to those receiving placebo (median duration 9.9 months versus 3.9 months; P = 0.023). There was no difference in the frequency or severity of adverse events, including infection, between the treatment arms., Conclusion: In patients with GCA, the addition of abatacept to a treatment regimen with prednisone reduced the risk of relapse and was not associated with a higher rate of toxicity compared to prednisone alone., (© 2017, American College of Rheumatology.)

Objective: To compare the efficacy of abatacept to that of placebo for the treatment of Takayasu arteritis (TAK)., Methods: In this multicenter trial, patients with newly diagnosed or relapsing TAK were treated with abatacept 10 mg/kg intravenously on days 1, 15, and 29 and week 8, together with prednisone administered daily. At week 12, patients in remission underwent a double-blinded randomization to continue to receive abatacept monthly or switch to placebo. Patients in both study arms received a standardized prednisone taper, reaching a dosage of 20 mg daily at week 12, with discontinuation of prednisone at week 28. All patients remained on their randomized assignment until meeting criteria for early termination or until 12 months after enrollment of the last patient. The primary end point was duration of remission (relapse-free survival)., Results: Thirty-four eligible patients with TAK were enrolled and treated with prednisone and abatacept; of these, 26 reached the week 12 randomization and underwent a blinded randomization to receive either abatacept or placebo. The relapse-free survival rate at 12 months was 22% for those receiving abatacept and 40% for those receiving placebo (P = 0.853). Treatment with abatacept in patients with TAK enrolled in this study was not associated with a longer median duration of remission (median duration 5.5 months for abatacept versus 5.7 months for placebo). There was no difference in the frequency or severity of adverse events, including infection, between the treatment arms., Conclusion: In patients with TAK, the addition of abatacept to a treatment regimen with prednisone did not reduce the risk of relapse., (© 2017, American College of Rheumatology.)

Objective: To examine the concordance between high-resolution magnetic resonance imaging (MRI) of the scalp arteries and temporal artery biopsy for the diagnosis of giant cell arteritis (GCA)., Methods: We conducted a prospective cohort study of patients with suspected GCA. Participants underwent high-field 3T MRI of the scalp arteries followed by temporal artery biopsy. Arterial wall thickness and enhancement on multiplanar postcontrast T1-weighted spin-echo images were graded according to a published severity scale (range 0-3). MRI findings were compared with temporal artery biopsy results and the American College of Rheumatology (ACR) criteria for GCA., Results: One hundred seventy-one patients were included in the study. Temporal artery biopsy findings were positive in 31 patients (18.1%), and MRI findings were abnormal in 60 patients (35.1%). ACR criteria were met in 137 patients (80.1%). With temporal artery biopsy as the reference test, MRI had a sensitivity of 93.6% (95% confidence interval [95% CI] 78.6-99.2) and a specificity of 77.9% (95% CI 70.1-84.4). The corresponding negative predictive value of MRI was 98.2% (95% CI 93.6-99.8) and positive predictive value was 48.3% (95% CI 35.2-61.6)., Conclusion: In patients with suspected GCA, normal findings on scalp artery MRI are very strongly associated with negative temporal artery biopsy findings. This suggests that MRI could be used as the initial diagnostic procedure in GCA, with temporal artery biopsy being reserved for patients with abnormal MRI findings., (© 2016, American College of Rheumatology.)

Objective: Takayasu arteritis is a rare large vessel vasculitis with incompletely understood etiology. This study was undertaken to perform the first unbiased genome-wide association analysis of Takayasu arteritis., Methods: Two independent cohorts of patients with Takayasu arteritis from Turkey and North America were included in our study. The Turkish cohort consisted of 559 patients and 489 controls, and the North American cohort consisted of 134 patients and 1,047 controls of European ancestry. Genotyping was performed using the Omni1-Quad and Omni2.5 genotyping arrays. Genotyping data were subjected to rigorous quality control measures and subsequently analyzed to discover genetic susceptibility loci for Takayasu arteritis., Results: We identified genetic susceptibility loci for Takayasu arteritis with a genome-wide level of significance in IL6 (rs2069837) (odds ratio [OR] 2.07, P = 6.70 × 10(-9)), RPS9/LILRB3 (rs11666543) (OR 1.65, P = 2.34 × 10(-8)), and an intergenic locus on chromosome 21q22 (rs2836878) (OR 1.79, P = 3.62 × 10(-10)). The genetic susceptibility locus in RPS9/LILRB3 lies within the leukocyte receptor complex gene cluster on chromosome 19q13.4, and the disease risk variant in this locus correlates with reduced expression of multiple genes including the inhibitory leukocyte immunoglobulin-like receptor gene LILRB3 (P = 2.29 × 10(-8)). In addition, we identified candidate susceptibility genes with suggestive levels of association (P < 1 × 10(-5)) with Takayasu arteritis, including PCSK5, LILRA3, PPM1G/NRBP1, and PTK2B., Conclusion: Our findings indicate novel genetic susceptibility loci for Takayasu arteritis and uncover potentially important aspects of the pathophysiology of this form of vasculitis., (© 2015, American College of Rheumatology.)