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-β, 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 mono-nuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibro-blasts 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.

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Inflammasomes are innate immune sensors that respond to pathogen and damage-associated signals with caspase-1 activation, IL-1β and IL-18 secretion, and macrophage pyroptosis. The discovery that dominant gain-of-function mutations in NLRP3 cause the Cryopyrin Associated Periodic Syndromes (CAPS) and trigger spontaneous inflammasome activation and IL-1β oversecretion, led to successful treatment with IL-1 blocking agents1. Herein, we report a de novo missense mutation, c.1009A>T, p.Thr337Ser, in the nucleotide-binding domain of inflammasome component NLRC4 (IPAF/CARD12) that causes early-onset recurrent fever flares and Macrophage Activation Syndrome (MAS). Functional analyses demonstrated spontaneous inflammasome formation and production of the inflammasome-dependent cytokines IL-1β and IL-18, the latter exceeding levels in CAPS. The NLRC4 mutation caused constitutive caspase-1 cleavage in transduced cells and increased production of IL-18 by both patient and NLRC4 mutant macrophages. Thus, we describe a novel monoallelic inflammasome defect that expands the monogenic autoinflammatory disease spectrum to include MAS and suggests novel targets for therapy.

A major goal of systems biology is the development of models that accurately predict responses to perturbation. Constructing such models requires collection of dense measurements of system states, yet transformation of data into predictive constructs remains a challenge. To begin to model human immunity, we analyzed immune parameters in depth both at baseline and in response to influenza vaccination. Peripheral blood mononuclear cell transcriptomes, serum titers, cell subpopulation frequencies, and B cell responses were assessed in 63 individuals before and after vaccination and used to develop a systematic framework to dissect inter- and intra-individual variation and build predictive models of post-vaccination antibody responses. Strikingly, independent of age and pre-existing antibody titers, accurate models could be constructed using pre-perturbation cell populations alone, which were validated using independent baseline time-points. Most of the parameters contributing to prediction delineated temporally-stable baseline differences across individuals, raising the prospect of immune monitoring before intervention.

Background In severe acquired aplastic anemia, hematopoietic failure is the result of immune mediated destruction of bone marrow stem and progenitor cells. Immunosuppressive therapy with antithymocyte globulin (ATG) plus cyclosporine is an effective alternative to stem cell transplantation and improves blood counts and survival. While horse ATG is standard, rabbit ATG is more potent at depleting peripheral blood lymphocytes and is preferred in other clinical circumstances. Methods From December 2005 to July 2010, we performed a randomized trial comparing these two different ATG formulations at conventional regimens. Patients were treated at a single government facility. Primary outcome was hematologic response at 6 months, as determined by blood counts. The study was designed to accrue 60 patients per arm and powered to detect a 25% difference in response rate. Results There was a large, unexpected difference in hematologic responses at 6 months in favor of horse ATG (68%; 95% confidence interval (CI), 56%–80%) compared to rabbit ATG (37%; 95% CI, 24%–49%; p<0.001). Overall survival at 3 years also differed, with 96% (95% CI, 90%–100%) surviving in the horse ATG group compared to 76% (95% CI, 61%–95%; p=0.04) in the rabbit ATG group when stem cell transplantation was censored, and 94% (95% CI, 88%–100%) for horse ATG and 70% (95% CI, 56%–86%; p=0.008) for rabbit ATG when stem cell transplantation events were not censored. Conclusions In a randomized study, rabbit ATG was markedly inferior to horse ATG as first treatment in severe aplastic anemia as measured by hematologic response and survival.