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Early exposure to inflammatory signals may have a lasting impact on immune function. Present throughout embryogenesis, macrophages are key cells providing innate immune protection to the developing fetus and newborn. Here, we have used an established model of macrophage development to test how early inflammatory signals can impact cellular differentiation and function. Bone marrow-derived macrophages were treated with Escherichia colilipopolysaccharide (LPS) 2 days after initial isolation and culture. LPS treatment during this early stage of differentiation decreased the expression of CSF1R and increased that of the mature macrophage marker F4/80. These early changes in macrophage differentiation were also measured in cells from mice lacking IKKβ, but the change in CSF1R expression after LPS treatment was blocked with MAPK inhibition. LPS-induced changes in macrophage marker expression persisted following LPS removal, suggesting that early inflammatory activation could induce a lasting developmental impact. Early LPS exposure inhibited macrophage phagocytosis of labeled E. coliwhile LPS had no effect on fully differentiated macrophages. Our data demonstrate that early inflammatory exposure to a microbial stimulus induce lasting phenotypic changes in macrophages.

p38α activation of multiple effectors may underlie the failure of global p38α inhibitors in clinical trials. A unique inhibitor (CDD-450) was developed that selectively blocked p38α activation of the proinflammatory kinase MK2 while sparing p38α activation of PRAK and ATF2. Next, the hypothesis that the p38α–MK2 complex mediates inflammasome priming cues was tested. CDD-450 had no effect on NLRP3 expression, but it decreased IL-1β expression by promoting IL-1β mRNA degradation. Thus, IL-1β is regulated not only transcriptionally by NF-κB and posttranslationally by the inflammasomes but also posttranscriptionally by p38α–MK2. CDD-450 also accelerated TNF-α and IL-6 mRNA decay, inhibited inflammation in mice with cryopyrinopathy, and was as efficacious as global p38α inhibitors in attenuating arthritis in rats and cytokine expression by cells from patients with cryopyrinopathy and rheumatoid arthritis. These findings have clinical translation implications as CDD-450 offers the potential to avoid tachyphylaxis associated with global p38α inhibitors that may result from their inhibition of non-MK2 substrates involved in antiinflammatory and housekeeping responses.

BackgroundHereditary recurrent fevers (HRFs) are rare inflammatory diseases sharing similar clinical symptoms and effectively treated with anti-inflammatory biological drugs. Accurate diagnosis of HRF relies heavily on genetic testing.ObjectivesThis study aimed to obtain an experts’ consensus on the clinical significance of gene variants in four well-known HRF genes: MEFV, TNFRSF1A, NLRP3and MVK.MethodsWe configured a MOLGENIS web platform to share and analyse pathogenicity classifications of the variants and to manage a consensus-based classification process. Four experts in HRF genetics submitted independent classifications of 858 variants. Classifications were driven to consensus by recruiting four more expert opinions and by targeting discordant classifications in five iterative rounds.ResultsConsensus classification was reached for 804/858 variants (94%). None of the unsolved variants (6%) remained with opposite classifications (eg, pathogenic vs benign). New mutational hotspots were found in all genes. We noted a lower pathogenic variant load and a higher fraction of variants with unknown or unsolved clinical significance in the MEFVgene.ConclusionApplying a consensus-driven process on the pathogenicity assessment of experts yielded rapid classification of almost all variants of four HRF genes. The high-throughput database will profoundly assist clinicians and geneticists in the diagnosis of HRFs. The configured MOLGENIS platform and consensus evolution protocol are usable for assembly of other variant pathogenicity databases. The MOLGENIS software is available for reuse at http://github.com/molgenis/molgenis; the specific HRF configuration is available at http://molgenis.org/said/.The HRF pathogenicity classifications will be published on the INFEVERS database at https://fmf.igh.cnrs.fr/ISSAID/infevers/.

Dysregulation of the interleukin-1 (IL-1) pathway leads to immune diseases that can result in chronic tissue and organ inflammation. Although IL-1 blockade has shown promise in ameliorating these symptoms and improving patients’ quality of life, there is an urgent need for more effective, long-lasting treatments. We developed a lentivirus (LV)–mediated gene transfer strategy using transplanted autologous hematopoietic stem/progenitor cells (HSPCs) as a source of IL-1 receptor antagonist (IL-1RA) for systemic delivery to tissues and organs. Transplantation of mouse and human HSPCs transduced with an IL-1RA–encoding LV ensured stable IL-1RA production while maintaining the clonogenic and differentiation capacities of HSPCs in vivo. We examined the efficacy of cell-mediated IL-1RA delivery in three models of IL-1–dependent inflammation, for which treatment hindered neutrophil recruitment in an inducible model of gout, prevented systemic and multi-tissue inflammation in a genetic model of cryopyrin-associated periodic syndromes, and reduced disease severity in an experimental autoimmune encephalomyelitis model of multiple sclerosis. Our findings demonstrate HSPC-mediated IL-1RA delivery as a potential therapeutic modality that can be exploited to suppress tissue and organ inflammation in diverse immune-related diseases involving IL-1–driven inflammation.

Netea and colleagues provide a general guide to the cellular and humoral contributors to inflammation as well as the pathways that characterize inflammation in specific organs and tissues.

Cold urticaria is a chronic condition causing episodic symptoms of cold-induced wheals or angioedema in response to direct or indirect exposure to cold temperatures. While symptoms of cold urticaria are typically benign and self-limiting, severe systemic anaphylactic reactions are possible. Acquired, atypical, and hereditary forms have been described, each with variable triggers, symptoms and responses to therapy. Clinical testing, including response to cold stimulation, help define disease subtypes. More recently, monogenic disorders characterized by atypical forms of cold urticaria have been described. Here, we review the different forms of cold-induced urticaria and related syndromes, and propose a diagnostic algorithm to aid clinicians in making a timely diagnosis for appropriate management of these patients.

Supplemental Digital Content is available in the text.

Supplemental Digital Content is available in the text.

NAFLD has evolved as a serious public health problem in the USA and around the world. In fact, NASH—the most serious form of NAFLD—is predicted to become the leading cause of liver transplantation in the USA by the year 2020. The pathogenesis of NAFLD and NASH, in particular the mechanisms responsible for liver injury and fibrosis, is the result of a complex interplay between host and environmental factors, and is at the centre of intense investigation. In this Review, we focus on recently uncovered aspects of the genetic, biochemical, immunological and molecular events that are responsible for the development and progression of this highly prevalent and potentially serious disease. These studies bring new insight into this complex disorder and have led to the development of novel therapeutic and diagnostic strategies that might enable a personalized approach in the management of this disease.

Review discusses autoinflammatory diseases as a new classification of immune disorders due to dysregulated innate immunity yet sensitive to targeted cytokine therapy. Autoinflammatory syndromes are a clinically heterogeneous collection of diseases characterized by dysregulation of the innate immune system. The hereditary recurrent fever disorders were the first to be defined as autoinflammatory. Several of the responsible genes are now known to encode proteins forming multimeric complexes called inflammasomes, which are intracellular “danger sensors” that respond to a variety of different signals by activating caspase‐1, responsible for cleavage and subsequent release of bioactive IL‐1β. This discovery of the causative link between autoinflammation and IL‐1β maturation has led to a significantly improved understanding of the mechanisms of innate immunity, as well as life‐altering treatments for patients. Targeting IL‐1β for the treatment of autoinflammatory syndromes is an excellent example of the power of translational research. Given the central role of inflammation in many complex multigenic diseases, these treatments may benefit larger numbers of patients in the future. Here, we review current treatment strategies of autoinflammatory diseases with a focus on IL‐1 antagonism.

Rheumatologists are likely to be asked to evaluate patients with recurrent febrile syndromes, so it is important that they are familiar with the clinical and diagnostic features, pathophysiology and therapeutic options for these rare autoinflammatory disorders. These syndromes are all characterized by recurrent episodes of fever and systemic inflammation; however, some syndromes have unique historical and physical features that can help with making a diagnosis. The primary associated morbidity is systemic amyloidosis, usually with renal involvement. Diagnostic testing is mostly limited to genetic testing. NSAIDs, colchicine and corticosteroids have roles in the treatment of some of these disorders, but biologic drugs that target interleukin-1ß are emerging as consistently effective therapies.

Background: Cryopyrin-associated periodic syndromes (CAPS) encompass a group of rare inherited, autoinflammatory disorders that represent a spectrum of one disease with varying degrees of severity. Until recently, there was no effective treatment for CAPS, but identification of the genetic basis of CAPS highlighted the pathogenic role of IL-1β. Objectives: Rilonacept is a recently FDA approved biologic therapy for CAPS with high affinity for IL-1β. Limited pharmacological data has been reported to date. Methods: A review of the phamacokinetics and pharmacodynamics data as well as the results of a pilot study and Phase III placebo-controlled trials of rilonacept in CAPS. Unpublished data on an open-label extension study in adult and pediatric subjects is also reviewed. Results: Rilonacept produced rapid and profound improvements in symptoms and also reduced high-sesitivity C-reactive protein levels and normalized elevated serum amyloid A concentrations, an important risk factor for amyloidosis. The primary adverse events were injection- site reactions and upper respiratory tract infections. Conclusion: Rilonacept, the only IL-1 Trap, is the first of many novel IL-1-targeted therapies being developed. In a very short time it has changed the lives of CAPS patients.

Gain-of-function mutations in NLRP3 are responsible for a spectrum of autoinflammatory diseases collectively referred to as “cryopyrin-associated periodic syndromes” (CAPS). Treatment of CAPS patients with IL-1–targeted therapies is effective, confirming a central pathogenic role for IL-1β. However, the specific myeloid cell population(s) exhibiting inflammasome activity and sustained IL-1β production in CAPS remains elusive. Previous reports suggested an important role for mast cells (MCs) in this process. Here, we report that, in mice, gain-of-function mutations in Nlrp3 restricted to neutrophils, and to a lesser extent macrophages/dendritic cells, but not MCs, are sufficient to trigger severe CAPS. Furthermore, in patients with clinically established CAPS, we show that skin-infiltrating neutrophils represent a substantial biological source of IL-1β. Together, our data indicate that neutrophils, rather than MCs, can represent the main cellular drivers of CAPS pathology.

Nucleotide‐binding oligomerization domain (Nod)2 is a sensor of muramyl dipeptides (MDP) derived from bacterial peptidoglycan. Nod2 also plays a role in some autoinflammatory diseases. Cold‐induced autoinflammatory syndrome 1 (CIAS1)/NACHT domain, leucine‐rich repeat, and pyrin domain‐containing protein 3 (NALP3) has been suggested to be sufficient for MDP‐dependent release of mature IL‐1β, but the role of Nod2 in this process is unclear. Using mice bearing selective gene deletions, we provide in vitro and in vivo data showing that MDP‐induced IL‐1β release requires Nod2 and CIAS1/NALP3 as well as receptor‐interacting protein‐2 (Rip2), apoptosis‐associated speck‐like protein containing a caspase activation and recruitment domain (ASC), and caspase‐1. In contrast, MDP‐dependent IL‐6 production only requires Nod2 and Rip2. Together, our data provide a new understanding of this important pathway of IL‐1β production and allow for further studies of the role of these proteins within the broader context of inflammatory disease.

Familial cold autoinflammatory syndrome (FCAS), formerly known as familial cold urticaria, is a rare condition characterized by fever, rash, and arthralgias elicited by exposure to cold. Recently, mutations responsible for FCAS were identified in a novel gene (CIAS1), making it possible to confirm the diagnosis in most patients.

Background:Familial cold autoinflammatory syndrome (FCAS), commonly known as familial cold urticaria, is a rare autosomal dominant inflammatory disorder with episodic symptoms precipitated by exposure to cold. Objective:The goal of this study was to formulate clinical diagnostic criteria for FCAS in a large cohort in whom the diagnosis of FCAS was supported by genetic linkage to chromosome 1q44. Methods:We assessed 45 affected and 68 unaffected members from 6 American families. DNA analysis was performed to confirm linkage to chromosome 1q44. Clinical characteristics were determined by means of analysis of detailed questionnaires and medical histories. Results:Pedigree and genetic analyses confirmed autosomal dominant transmission and linkage to chromosome 1q44 in all families. The most consistent symptoms during attacks were rash (100%), fever (93%), arthralgia (96%), and conjunctivitis (84%). Age of onset was within the first 6 months of life in 95% of affected subjects. The average delay between cold exposure and onset of symptoms was 2.5 hours, and the average duration of an episode was 12 hours. Renal disease with amyloidosis occurs infrequently in FCAS (2%). Conclusion:The most consistent clinical characteristics of FCAS that discriminate it from other periodic fevers are association with cold exposure, conjunctivitis, age of onset, duration of episodes, and an autosomal dominant inheritance pattern. On the basis of the analysis of genotype and phenotype of FCAS, we formulated clinical diagnostic criteria that can be used to distinguish FCAS from other hereditary periodic fever syndromes. (J Allergy Clin Immunol 2001;108:615-20.)

A Correction to this paper has been published: https://doi.org/10.1038/ni.3790

ABSTRACTThe M1T1 clone of group A Streptococcus (GAS) is associated with severe invasive infections, including necrotizing fasciitis and septicemia. During invasive M1T1 GAS disease, mutations in the covRSregulatory system led to upregulation of an ADP-ribosyltransferase, SpyA. Surprisingly, a GAS ΔspyAmutant was resistant to killing by macrophages and caused higher mortality with impaired bacterial clearance in a mouse intravenous challenge model. GAS expression of SpyA triggered macrophage cell death in association with caspase-1-dependent interleukin 1β (IL-1β) production, and differences between wild-type (WT) and ΔspyAGAS macrophage survival levels were lost in cells lacking caspase-1, NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), or pro-IL-1β. Similar in vitrofindings were identified in macrophage studies performed with pseudomonal exotoxin A, another ADP-ribosylating toxin. Thus, SpyA triggers caspase-1-dependent inflammatory cell death in macrophages, revealing a toxin-triggered IL-1β-dependent innate immune response pathway critical in defense against invasive bacterial infection.IMPORTANCEGroup A Streptococcus (GAS) is a leading human pathogen capable of producing invasive infections even in healthy individuals. GAS bacteria produce a toxin called SpyA that modifies host proteins through a process called ADP ribosylation. We describe how macrophages, frontline defenders of the host innate immune system, respond to SpyA by undergoing a specialized form of cell death in which they are activated to release the proinflammatory cytokine molecule interleukin 1β (IL-1β). Release of IL-1β activates host immune cell clearance of GAS, as we demonstrated in tissue culture models of macrophage bacterial killing and in vivomouse infectious-challenge experiments. Similar macrophage responses to a related toxin of Pseudomonasbacteria were also shown. Thus, macrophages recognize certain bacterial toxins to activate a protective immune response in the host.