Clinical and Molecular Phenotypes of Low-Penetrance Variants of NLRP3: Diagnostic and Therapeutic Challenges.

OBJECTIVE: Cryopyrin-associated periodic syndromes (CAPS) result from gain-of-function mutations in the NLRP3 gene, which causes excessive release of interleukin-1ß (IL-1ß) and systemic inflammation. While pathogenetic NLRP3 variant phenotypes are well-characterized, low-penetrance NLRP3 variants represent a significant clinical challenge. The aims of this study were to determine the clinical phenotype, the in vitro biologic phenotype, and the effect of anti-IL-1 treatment in patients with low-penetrance NLRP3 variants. METHODS: A multicenter study of consecutive symptomatic patients with low-penetrance NLRP3 variants recruited from 7 centers between May 2012 and May 2013 was performed. The observed findings were transferred into a study database, from which they were extracted for analysis. Controls were patients with a known pathogenetic NLRP3 variant. Clinical presentation and CAPS markers of inflammation were captured. Functional assays of inflammasome activation, including caspase 1 activity, NF-κB release, cell death, and IL-1ß release, were performed. Treatment effects of IL-1 were determined. Comparisons between low-penetrance and pathogenetic NLRP3 variants were performed. RESULTS: The study included 45 patients, 21 of which were female (47%); 26 of the patients (58%) were children. NLRP3 low-penetrance variants identified in the patients were Q703K (n = 19), R488K (n = 6), and V198M (n = 20). In the controls, 28 had pathogenetic NLRP3 variants. Patients with low-penetrance NLRP3 variants had significantly more fever (76%) and gastrointestinal symptoms (73%); eye disease, hearing loss, and renal involvement were less common. Functional inflammasome testing identified an intermediate phenotype in low-penetrance NLRP3 variants as compared to wild-type and pathogenetic NLRP3 variants. All treated patients responded to IL-1 inhibition, with complete response documented in 50% of patients. CONCLUSION: Patients with low-penetrance NLRP3 variants display a distinct clinical phenotype and an intermediate biologic phenotype, including IL-1ß and non-IL-1ß-mediated inflammatory pathway activation.

Recurrent lipoatrophic panniculitis of children.

BACKGROUND: Recurrent panniculitis in children with lipoatrophy has been loosely described and reported under different names, but has never been systematically evaluated by immunohistochemical stains. OBJECTIVE: To depict the profile of children with recurrent idiopathic panniculitis. METHODS: Study of clinical, histopathological and immunohistochemical features in five cases with recurrent idiopathic panniculitis. RESULTS: Five children with repeated attacks of painful subcutaneous nodules in association with fever, malaise and abdominal pain or arthralgia, with subsequent lipoatrophy were reviewed. In two patients, extensive involvement led to loss of the cutaneous fatty tissue. Laboratory abnormalities included increased acute phase reactants, leukocytosis with mild neutrophilia, microcytic anaemia and elevated liver enzymes. Histopathology showed lobar panniculitis without vasculitis and with a mixed infiltrate, composed of neutrophils, mononuclear cells, lymphocytes, macrophages and myeloid cells. Neutrophils and myeloid cells were more prominent in early lesions, whereas macrophages predominated in late stages, leading to lipophagia and lipoatrophy. Immunohistochemistry showed positive staining for myeloperoxidase around the necrotic adipocytes in early stages and CD68/PGM1 macrophages in late stages. Intense STAT1 staining was observed in the inflammatory infiltrate. All patients improved with methotrexate and corticosteroids. CONCLUSION: We present five cases of lobar panniculitis and lipoatrophy in childhood. The clinico-pathologic presentation shares features with other autoinflammatory diseases.

Activated STING in a vascular and pulmonary syndrome.

BACKGROUND: The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation. METHODS: We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-ß, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls. RESULTS: We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors. CONCLUSIONS: STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

Organ-specific autoantibodies and autoimmune diseases in juvenile systemic lupus erythematosus and juvenile dermatomyositis patients.

OBJECTIVES: To our knowledge, no study assessed simultaneously a variety of organ-specific autoantibodies and the prevalence of organ-specific autoimmune diseases in juvenile systemic lupus erythematosus (JSLE) and juvenile dermatomyositis (JDM). Therefore, the purpose of this study was to evaluate organ-specific autoantibodies and autoimmune diseases in JSLE and JDM patients. METHODS: Forty-one JSLE and 41 JDM patients were investigated for autoantibodies associated with autoimmune hepatitis, primary biliary cirrhosis, type 1 diabetes mellitus (T1DM), autoimmune thyroiditis (AT), autoimmune gastritis and coeliac disease (CD). Patients with positive antibodies were investigated for the respective organ-specific autoimmune diseases. RESULTS: Mean age at diagnosis was higher in JSLE compared to JDM patients (10.3±3.4 vs. 7.3±3.1years, p=0.0001). The frequencies of organ-specific autoantibodies were similar in JSLE and JDM patients (p>0.05). Of note, a high prevalence of T1DM and AT autoantibodies was observed in both groups (20% vs. 15%, p=0.77 and 24% vs. 15%, p=0.41; respectively). Higher frequencies of ANA (93% vs. 59%, p=0.0006), anti-dsDNA (61% vs. 2%, p<0.0001), anti-Ro, anti-Sm, anti-RNP, anti-La and IgG-aCL were observed in JSLE (p<0.05). Organ-specific autoimmune diseases were evidenced only in JSLE patients (24% vs. 0%, p=0.13). Two JSLE patients had T1DM associated with Hashimoto thyroiditis and another had subclinical thyroiditis. Another JSLE patient had CD diagnosis based on iron deficiency anaemia, anti-endomysial antibody, duodenal biopsy compatible to CD and response to a gluten-free diet. CONCLUSIONS: Organ-specific diseases were observed solely in JSLE patients and required specific therapy. The presence of these antibodies recommends the evaluation of organ-specific diseases and a rigorous follow-up.

Common variable immunodeficiency associated with hepatosplenic T-cell lymphoma mimicking juvenile systemic lupus erythematosus.

Common variable immunodeficiency (CVID) is a heterogeneous disorder with susceptibility to infections, autoimmune manifestations, and cancer. To our knowledge, CIVD with T-cell lymphoma mimicking juvenile systemic lupus erythematosus (JSLE) was not described in the literature, and one case was reported herein. An 8-year-old female was admitted in our Pediatric Immunology Unit with a clinical history of hypogammaglobulinemia, recurrent upper respiratory infections, and pneumonias. She had a marked decrease of three serum immunoglobulin isotypes, and the diagnosis of CVID was established. At the age of 17 years, she presented with oral ulceration, nonerosive arthritis, nephritis, serositis, cytopenia, positive antiphospholipid antibodies, and positive antinuclear antibody fulfilling the American College of Rheumatology (ACR) criteria for SLE. She was treated with intravenous methylprednisolone for three consecutive days, and intravenous immunoglobulin, and maintenance therapy of chloroquine, azathioprine and prednisone 40 mg/day. Two months later, she died of septic shock secondary to acute pneumonia. The necropsy showed hepatosplenic T-cell lymphoma with diffuse involvement of bone marrow, spleen, liver, and lungs. The lymphoma cells were positive for CD3 immunostaining and negative for CD20 and lysozyme. In conclusion, the association of CVID and hepatosplenic T-cell lymphoma may simulate JSLE diagnosis.

Acute pancreatitis in juvenile systemic lupus erythematosus: a manifestation of macrophage activation syndrome?

Acute pancreatitis (AP) is a rare and life-threatening manifestation of juvenile systemic lupus erythematosus (JSLE). The objective of this study was to evaluate the prevalence and clinical features of AP in our JSLE population. AP was defined according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Of note, in the last 26 years, 5367 patients were followed up at our Pediatric Rheumatology Unit and 263 (4.9%) of them had JSLE diagnosis (ACR criteria). AP was observed in 4.2% (11/263) of JSLE patients. The median of age of the JSLE patients at AP diagnosis was 12.4 years (8.8-17.9). All of them had lupus disease activity at AP onset. Three patients were receiving corticosteroids before AP diagnosis. Interestingly, 10/11 JSLE patients fulfilled preliminary guidelines for macrophage activation syndrome, three of them with macrophage hemophagocytosis in bone marrow aspirate and hyperferritinemia. The hallmark of this syndrome is excessive activation and proliferation of T lymphocytes and macrophages with massive hypersecretion of proinflammatory cytokines and clinically it is characterized by the occurrence of unexplained fever, cytopenia and hyperferritinemia. AP treatment was mainly based on intravenous methylprednisolone. Four JSLE patients with AP died and two developed diabetes mellitus. In conclusion, AP was a rare and severe manifestation in active pediatric lupus. The association between AP and macrophage activation syndrome suggests that the pancreas could be a target organ of this syndrome and that pancreatic enzyme evaluation should also be carried out in all patients.