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Activating-mutations in NOD-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) cause neonatal-onset multisystem inflammatory disease. However, the ontogeny of skeletal anomalies in this disorder is poorly understood. Mice globally expressing the D301N mutation in Nlrp3 (D303N in human) model the human phenotype, including systemic inflammation and skeletal deformities. To gain insights into the skeletal manifestations, we generated mice in which the expression of D301N Nlrp3 (Nlrp3D301N) is restricted to myeloid cells. These mice exhibit systemic inflammation and severe osteopenia (~60% lower bone mass) similar to mice globally expressing the knock-in mutation, consistent with the paradigm of innate immune-driven cryopyrinopathies. Because systemic inflammation may indirectly affect bone homeostasis, we engineered mice in which Nlrp3D301N is expressed specifically in osteoclasts, the cells that resorb bone. These mice also develop ~50% lower bone mass due to increased osteolysis, but there is no systemic inflammation and no change in osteoclast number. Mechanistically, aside from its role in IL-1β maturation, Nlrp3D301N expression enhances osteoclast bone resorbing ability through reorganization of actin cytoskeleton while promoting the degradation of poly(ADP-ribose) polymerase 1, an inhibitor of osteoclastogenesis. Thus, NLRP3 inflammasome activation is not restricted to the production of proinflammatory mediators but also leads to cytokine-autonomous responses. [ABSTRACT FROM AUTHOR]

This study was designed to understand the contribution of the inflammasome and IL-1β activation in otitis media (OM). We examined the middle ear (ME) response to non-typeable Haemophilus influenzae (NTHi) in wild type (WT) mice using gene microarrays and a murine model of acute OM. Expression of members of the NOD domain-like receptor family of inflammasome genes was significantly up-regulated early in NTHi infection of the ME, potentially activating specific downstream regulatory cascades that contribute to the proliferative inflammatory response observed during OM. Expression of the pro-forms of the inflammasome targets IL-1β and IL-18 were also up-regulated. To evaluate the role of inflammasome-mediated cytokine maturation, NTHi-induced OM was examined in Asc−/−-deficient mice and compared with that seen in WT mice. Mice lacking the Asc gene showed near absence of IL-1β maturation in the ME and a reduction in leukocyte recruitment and infiltration to the cavity, and their macrophages exhibited reduced phagocytosis of NTHi. These inflammatory defects were linked to an increase in the degree and duration of mucosal epithelial hyperplasia in the ME of Asc−/− mice, as well as a delay in bacterial clearance from their MEs. These data demonstrate an important role for the inflammasome and cytokine processing in the course and resolution of OM. [ABSTRACT FROM AUTHOR]

Aims The NLRP3 inflammasome is activated in the ischaemic heart promoting caspase-1 activation, inflammation, and cell death. Ischaemic injury establishes both a priming signal (transcription of inflammasome components) and a trigger (NLRP3 activation). Whether NLRP3 activation, without priming, induces cardiac dysfunction and/or failure is unknown. The aim of this study was to assess the independent and complementary roles of the priming and the triggering signals in the heart, in the absence of ischaemia or myocardial injury. Methods and results We used mice with mutant NLRP3 (constitutively active), NLRP3-A350V, under the control of tamoxifen-driven expression of the Cre recombinase (Nlrp3-A350V/CreT mice). The mice were treated for 10 days with tamoxifen before measuring the activity of caspase-1, the effector enzyme in the inflammasome. Tamoxifen treatment induced the inflammasome in the spleen but not in the heart, despite expression of the mutant NLRP3-A350V. The components of the inflammasome were significantly less expressed in the heart compared with the spleen. Subclinical low-dose lipopolysaccharide (LPS; 2 mg/kg) in Nlrp3-A350V/CreT mice induced the expression of the components of the inflammasome (priming), measured using real-time PCR and western blot, leading to the formation of an active inflammasome (caspase-1 activation) in the heart and LV systolic dysfunction while low-dose LPS was insufficient to induce LV systolic dysfunction in wild-type mice (all P < 0.01 for mutant vs. wild-type mice). Conclusion The signalling pathway governing the inflammasome formation in the heart requires a priming signal in order for an active NLRP3 to induce caspase-1 activation and LV dysfunction. [ABSTRACT FROM AUTHOR]

Inflammasomes are intracellular sensors that couple detection of pathogens and cellular stress to activation of Caspase-1, and consequent IL-1β and IL-18 maturation and pyroptotic cell death. Here, we show that the absent in melanoma 2 (AIM2) and nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes trigger Caspase-1–dependent mitochondrial damage. Caspase-1 activates multiple pathways to precipitate mitochondrial disassembly, resulting in mitochondrial reactive oxygen species (ROS) production, dissipation of mitochondrial membrane potential, mitochondrial permeabilization, and fragmentation of the mitochondrial network. Moreover, Caspase-1 inhibits mitophagy to amplify mitochondrial damage, mediated in part by cleavage of the key mitophagy regulator Parkin. In the absence of Parkin activity, increased mitochondrial damage augments pyroptosis, as indicated by enhanced plasma membrane permeabilization and release of danger-associated molecular patterns (DAMPs). Therefore, like other initiator caspases, Caspase-1 activation by inflammasomes results in mitochondrial damage. [ABSTRACT FROM AUTHOR]

Background: The Cryopyrin-Associated Periodic Syndromes (CAPS) are a group of rare hereditary autoinflammatory diseases and encompass Familial Cold Autoinflammatory Syndrome (FCAS), Muckle-Wells Syndrome (MWS), and Neonatal Onset Multisystem Inflammatory Disease (NOMID). Canakinumab is a monoclonal antibody directed against IL-1 beta and approved for CAPS patients but requires post-approval monitoring due to low and short exposures during the licensing process. Creative approaches to observational methodology are needed, harnessing novel registry strategies to ensure Health Care Provider reporting and patient monitoring. Methods: A web-based registry was set up to collect information on long-term safety and effectiveness of canakinumab for CAPS. Results: Starting in November 2009, this registry enrolled 241 patients in 43 centers and 13 countries by December 31, 2012. One-third of the enrolled population was aged < 18; the overall population is evenly divided by gender. Enrolment is ongoing for children. Conclusions: Innovative therapies in orphan diseases require post-approval structures to enable in depth understanding of safety and natural history of disease. The rarity and distribution of such diseases and unpredictability of treatment require innovative methods for enrolment and follow-up. Broad international practicebased recruitment and web-based data collection are practical. [ABSTRACT FROM AUTHOR]

Orosomucoid like 3 (ORMDL3) has been strongly linked with asthma in genetic association studies, but its function in asthma is unknown. We demonstrate that in mice ORMDL3 is an allergen and cytokine (IL-4 or IL-13) inducible endoplasmic reticulum (ER) gene expressed predominantly in airway epithelial cells. Allergen challenge induces a 127-fold increase in ORMDL3 mRNA in bronchial epithelium in WT mice, with lesser 15-fold increases in ORMDL-2 and no changes in ORMDL-1. Studies of STAT-6-deficient mice demonstrated that ORMDL3 mRNA induction highly depends on STAT-6. Transfection of ORMDL3 in human bronchial epithelial cells in vitro induced expression of metalloproteases (MMP-9, ADAM-8), CC chemokines (CCL-20), CXC chemokines (IL-8, CXCL-10, CXCL-11), oligoadenylate synthetases (OAS) genes, and selectively activated activating transcription factor 6 (ATF6), an unfolded protein response (UPR) pathway transcription factor. siRNA knockdown of ATF-6a in lung epithelial cells inhibited expression of SERCA2b, which has been implicated in airway remodeling in asthma. In addition, transfection of ORMDL3 in lung epithelial cells activated ATF6α and induced SER-CA2b. These studies provide evidence of the inducible nature of ORMDL3 ER expression in particular in bronchial epithelial cells and suggest an ER UPR pathway through which ORMDL3 may be linked to asthma [ABSTRACT FROM AUTHOR]

Abstract: Background: Cryopyrin-associated periodic syndromes (CAPS) are rare, inherited autoinflammatory disorders associated with considerable hardship to patients. The interleukin-1 inhibitor rilonacept has been shown to be well-tolerated and effective in preventing CAPS symptoms in 2 pivotal studies. Objective: In this study, the long-term effects of rilonacept for improvement in CAPS symptoms and its safety and tolerability were evaluated during extended treatment. Methods: Patients with CAPS entered a 72-week open-label extension (OLE) following 2 sequential placebo-controlled Phase III studies (n = 44), or entered directly into the OLE (n = 57). Adults received weekly subcutaneous rilonacept 160 mg, and pediatric patients received subcutaneous rilonacept 2.2 mg/kg, up to 160 mg/week. Safety was evaluated in all patients, and efficacy was evaluated using a validated composite key symptom score in 56 patients. Results: After rilonacept treatment for 72 to 96 weeks mean key symptom score at OLE Week 72 was reduced from 2.6 to 0, and the mean number of multisymptom flare days was reduced from 7.3 (34.8% of days) at baseline to 0.6 (2.9% of days) at end point. Elevated levels of inflammatory markers (eg, high sensitivity-C reactive protein and serum amyloid A, were normalized. Adverse events were generally mild to moderate, the most common being injection site reactions and upper respiratory tract infections. The incidence of these events was similar to or lower than the rate reported in the pivotal studies. Conclusions: Long-term treatment with rilonacept of up to 96 weeks resulted in improvements in clinical signs and symptoms of CAPS and normalized biomarkers of inflammation. Rilonacept exhibited a generally favorable safety and tolerability profile in adult and pediatric patients with CAPS throughout the extended treatment period. ClinicalTrials.gov identifier: NCT 00288704. [Copyright &y& Elsevier]

Two letters to the editor are presented in response the article "A Severe Case of Chronic Infantile Neurologic, Cutaneous, Articular Syndrome Treated With Biologic Agents," published in a 2006 issue of "Arthritis Rheumatology."

Familial cold autoinflammatory syndrome (FCAS, MIM 120100), commonly known as familial cold urticaria (FCU), is an autosomal-dominant systemic inflammatory disease characterized by intermittent episodes of rash, arthralgia, fever and conjunctivitis after generalized exposure to cold. FCAS was previously mapped to a 10-cM region on chromosome 1q44 (refs. 5,6). Muckle-Wells syndrome (MWS; MIM 191900), which also maps to chromosome 1q44, is an autosomal-dominant periodic fever syndrome with a similar phenotype except that symptoms are not precipitated by cold exposure and that sensorineural hearing loss is frequently also present. To identify the genes for FCAS and MWS, we screened exons in the 1q44 region for mutations by direct sequencing of genomic DNA from affected individuals and controls. This resulted in the identification of four distinct mutations in a gene that segregated with the disorder in three families with FCAS and one family with MWS. This gene, called CIAS1, is expressed in peripheral blood leukocytes and encodes a protein with a pyrin domain, a nucleotide-binding site (NBS, NACHT subfamily) domain and a leucine-rich repeat (LRR) motif region, suggesting a role in the regulation of inflammation and apoptosis. [ABSTRACT FROM AUTHOR]

Autoinflammatory diseases are monogenic and polygenic disorders due to dysregulation of the innate immune system. The inherited conditions have been clustered with primary immunodeficiencies in the latest practice parameters; however, these diseases have unique clinical presentations, genetics, and available therapies. Given the presentation of fevers, rashes, and mucosal symptoms observed in many of these syndromes, patients are likely to present to an allergist/immunologist. Although there has been attention in the literature to diagnosis and treatment of rare, genetically defined autoinflammatory disorders, physicians are challenged by increasing numbers of patients with intermittent or periodic fevers who face unnecessary morbidities due to a lack of a diagnosis. The broad differential of diseases presenting with fever includes autoinflammatory syndromes, infections associated with immunodeficiency and/or allergies complicated by infection, and less commonly, autoimmune disorders or malignancy. To address this challenge, we review the history of the medical approach to fever, current diagnostic paradigms, and controversies in management. We describe the spectrum of disorders referred to a recurrent fever disorders clinic established in an Allergy/Immunology division at a tertiary pediatric care center. Finally, we provide practical recommendations including historical features and initial laboratory investigations that can help clinicians appropriately manage these patients. [ABSTRACT FROM AUTHOR]

Patients with chronic kidney disease (CKD) are often 25(OH)D3 and 1,25(OH)2D3 insufficient. We studied whether vitamin D repletion could correct aberrant adipose tissue and muscle metabolism in a mouse model of CKD-associated cachexia. Intraperitoneal administration of 25(OH)D3 and 1,25(OH)2D3 (75 μg/kg/day and 60 ng/kg/day respectively for 6 weeks) normalized serum concentrations of 25(OH)D3 and 1,25(OH)2D3 in CKD mice. Vitamin D repletion stimulated appetite, normalized weight gain, and improved fat and lean mass content in CKD mice. Vitamin D supplementation attenuated expression of key molecules involved in adipose tissue browning and ameliorated expression of thermogenic genes in adipose tissue and skeletal muscle in CKD mice. Furthermore, repletion of vitamin D improved skeletal muscle fiber size and in vivo muscle function, normalized muscle collagen content and attenuated muscle fat infiltration as well as pathogenetic molecular pathways related to muscle mass regulation in CKD mice. RNAseq analysis was performed on the gastrocnemius muscle. Ingenuity Pathway Analysis revealed that the top 12 differentially expressed genes in CKD were correlated with impaired muscle and neuron regeneration, enhanced muscle thermogenesis and fibrosis. Importantly, vitamin D repletion normalized the expression of those 12 genes in CKD mice. Vitamin D repletion may be an effective therapeutic strategy for adipose tissue browning and muscle wasting in CKD patients. [ABSTRACT FROM AUTHOR]

Choline is a vitamin-like nutrient that is taken up via specific transporters and metabolized by choline kinase, which converts it to phosphocholine needed for de novo synthesis of phosphatidylcholine (PC), the main phospholipid of cellular membranes. We found that Toll-like receptor (TLR) activation enhances choline uptake by macrophages and microglia through induction of the choline transporter CTL1. Inhibition of CTL1 expression or choline phosphorylation attenuated NLRP3 inflammasome activation and IL-1β and IL-18 production in stimulated macrophages. Mechanistically, reduced choline uptake altered mitochondrial lipid profile, attenuated mitochondrial ATP synthesis, and activated the energy sensor AMP-activated protein kinase (AMPK). By potentiating mitochondrial recruitment of DRP1, AMPK stimulates mitophagy, which contributes to termination of NLRP3 inflammasome activation. Correspondingly, choline kinase inhibitors ameliorated acute and chronic models of IL-1β-dependent inflammation. • LPS stimulates choline uptake and phosphorylation via CTL1 induction • Impaired choline uptake or phosphorylation reduces mitochondrial ATP synthesis • Reduced ATP synthesis leads to AMPK activation and induction of mitophagy • By causing mitophagy, ChoKα inhibition prevents NLRP3-dependent inflammation Sanchez-Lopez et al. have found that inhibition of choline uptake and phosphorylation in activated macrophages prevent NLRP3 inflammasome activation and IL-1β and IL-18 production. Inhibition of choline incorporation into phosphatidylcholine in the mitochondrial membranes and decreased ATP synthase activity lead to enhanced AMPK-dependent mitophagy that prevents acute and chronic inflammation. [ABSTRACT FROM AUTHOR]