Tumor necrosis factor receptor I blockade shows that TNF-dependent and independent mechanisms synergise in TNF receptor associated periodic syndrome

TNF receptor associated periodic syndrome (TRAPS) is an autoinflammatory disease involving recurrent episodes of fever and inflammation. It is associated with autosomal dominant mutations in TNF receptor superfamily 1A gene localised to exons encoding the ectodomain of the p55 TNF receptor, TNF receptor-1 (TNFR1). The aim of this study was to investigate the role of cell surface TNFR1 in TRAPS, and the contribution of TNF-dependent and TNF-independent mechanisms to the production of cytokines. HEK-293 and SK-HEP-1 cell lines were stably transfected with WT or TRAPS-associated variants of human TNF receptor superfamily 1A gene. An anti-TNFR1 single domain antibody (dAb), and an anti-TNFR1 mAb, bound to cell surface WT and variant TNFR1s. In HEK-293 cells transfected with death domain-inactivated (R347A) TNFR1, and in SK-HEP-1 cells transfected with normal (full-length) TNFR1, cytokine production stimulated in the absence of exogenous TNF by the presence of certain TNFR1 variants was not inhibited by the anti-TNFR1 dAb. In SK-Hep-1 cells, specific TRAPS mutations increased the level of cytokine response to TNF, compared to WT, and this augmented cytokine production was suppressed by the anti-TNFR1 dAb. Thus, TRAPS-associated variants of TNFR1 enhance cytokine production by a TNF-independent mechanism and by sensitising cells to a TNF-dependent stimulation. The TNF-dependent mechanism requires cell surface expression of TNFR1, as this is blocked by TNFR1-specific dAb

Inositol-Requiring Enzyme 1-Mediated Downregulation of MicroRNA (miR)-146a and miR-155 in Primary Dermal Fibroblasts across Three TNFRSF1A Mutations Results in Hyperresponsiveness to Lipopolysaccharide

Tumor necrosis factor (TNF)-receptor-associated periodic fever syndrome (TRAPS) is a rare monogenic autoinflammatory disorder characterized by mutations in the TNFRSF1A gene, causing TNF-receptor 1 (TNFR1) misfolding, increased cellular stress, activation of the unfolded protein response (UPR), and hyperresponsiveness to lipopolysaccharide (LPS). Both microRNA (miR)-146a and miR-155 provide negative feedback for LPS-toll-like receptor 2/4 signaling and cytokine production, through regulation of nuclear factor kappa B (NF-κB). In this study, we hypothesized that proinflammatory cytokine signaling in TRAPS downregulates these two miRs, resulting in LPS-induced hyperresponsiveness in TRAPS dermal fibroblasts (DFs), irrespective of the underlying genetic mutation. Primary DF were isolated from skin biopsies of TRAPS patients and healthy controls (HC). TNFR1 cell surface expression was measured using immunofluorescence. DF were stimulated with LPS, interleukin (IL)-1β, thapsigargin, or TNF, with and without inositol-requiring enzyme 1 (IRE1) inhibitor (4u8C), following which miR-146a and miR-155 expression was measured by RT-qPCR. IL-1β, IL-6, and TNF secretion was measured by enzyme-linked immunosorbent assays, and baseline expression of 384 different miRs was assessed using microfluidics assays. TNFR1 was found to be expressed on the surface of HC DF but expression was deficient in all samples with TRAPS-associated mutations. HC DF showed significant dose-dependent increases in both miR-146a and miR-155 expression levels in response to LPS; however, TRAPS DF failed to upregulate either miR-146a or miR-155 under the same conditions. This lack of miR-146a and miR-155 upregulation was associated with increased proinflammatory cytokine production in TRAPS DF in response to LPS challenge, which was abrogated by 4u8C. Incubation of HC DF with IL-1β led to downregulation of miR-146a and miR-155 expression, which was dependent on IRE1 enzyme. We observed global dysregulation of hundreds of other miRs at baseline in the TRAPS DF. In summary, these data suggest a mechanism whereby IL-1β, produced in response to activation of the UPR in TRAPS DF, downregulates miR-146a and miR-155, by inducing IRE1-dependent cleavage of both these miRs, thereby impairing negative regulation of NF-κB and increasing proinflammatory cytokine production

Mitochondrial reactive oxygen species drive proinflammatory cytokine production

Recent work indicates that mitochondrial ROS act via several pathways to elicit proinflammatory cytokines in human and mouse cells

A pro-inflammatory signalome is constitutively activated by C33Y mutant TNF receptor 1 in TNF receptor-associated periodic syndrome (TRAPS)

Mutations in TNFRSF1A encoding TNF receptor 1 (TNFR1) cause the autosomal dominant TNF receptor-associated periodic syndrome (TRAPS): a systemic autoinflammatory disorder. Misfolding, intracellular aggregation, and ligand-independent signaling by mutant TNFR1 are central to disease pathophysiology. Our aim was to understand the extent of signaling pathway perturbation in TRAPS. A prototypic mutant TNFR1 (C33Y), and wild-type TNFR1 (WT), were expressed at near physiological levels in an SK-Hep-1 cell model. TNFR1-associated signaling pathway intermediates were examined in this model, and in PBMCs from C33Y TRAPS patients and healthy controls. In C33Y-TNFR1-expressing SK-Hep-1 cells and TRAPS patients' PBMCs, a subtle, constitutive upregulation of a wide spectrum of signaling intermediates and their phosphorylated forms was observed; these were associated with a proinflammatory/antiapoptotic phenotype. In TRAPS patients' PBMCs, this upregulation of proinflammatory signaling pathways was observed irrespective of concurrent treatment with glucocorticoids, anakinra or etanercept, and the absence of overt clinical symptoms at the time that the blood samples were taken. This study reveals the pleiotropic effect of a TRAPS-associated mutant form of TNFR1 on inflammatory signaling pathways (a proinflammatory signalome), which is consistent with the variable and limited efficacy of cytokine-blocking therapies in TRAPS. It highlights new potential target pathways for therapeutic intervention

Lack of cyclophilin D protects against the development of acute lung injury in endotoxemia.

Sepsis caused by LPS is characterized by an intense systemic inflammatory response affecting the lungs, causing acute lung injury (ALI). Dysfunction of mitochondria and the role of reactive oxygen (ROS) and nitrogen species produced by mitochondria have already been proposed in the pathogenesis of sepsis; however, the exact molecular mechanism is poorly understood. Oxidative stress induces cyclophilin D (CypD)-dependent mitochondrial permeability transition (mPT), leading to organ failure in sepsis. In previous studies mPT was inhibited by cyclosporine A which, beside CypD, inhibits cyclophilin A, B, C and calcineurin, regulating cell death and inflammatory pathways. The immunomodulatory side effects of cyclosporine A make it unfavorable in inflammatory model systems. To avoid these uncertainties in the molecular mechanism, we studied endotoxemia-induced ALI in CypD-/- mice providing unambiguous data for the pathological role of CypD-dependent mPT in ALI. Our key finding is that the loss of this essential protein improves survival rate and it can intensely ameliorate endotoxin-induced lung injury through attenuated proinflammatory cytokine release, down-regulation of redox sensitive cellular pathways such as MAPKs, Akt, and NF-kappaB and reducing the production of ROS. Functional inhibition of NF-kappaB was confirmed by decreased expression of NF-kappaB-mediated proinflammatory genes. We demonstrated that impaired mPT due to the lack of CypD reduces the severity of endotoxemia-induced lung injury suggesting that CypD specific inhibitors might have a great therapeutic potential in sepsis-induced organ failure. Our data highlight a previously unknown regulatory function of mitochondria during inflammatory response

Mitochondrial reactive oxygen species promote production of proinflammatory cytokines and are elevated in TNFR1-associated periodic syndrome (TRAPS)

ROS generated by mitochondrial respiration are needed for optimal proinflammatory cytokine production in healthy cells, and are elevated in cells from patients with an autoinflammatory disorder

Polyenylpyrrole Derivatives Inhibit NLRP3 Inflammasome Activation and Inflammatory Mediator Expression by Reducing Reactive Oxygen Species Production and Mitogen-Activated Protein Kinase Activation

10.1371/journal.pone.0076754PLoS ONE810-POLN

A signalome screening approach in the autoinflammatory disease TNF Receptor Associated Periodic Syndrome (TRAPS) highlights the anti-inflammatory properties of drugs for repurposing

TNF Receptor Associated Periodic Syndrome (TRAPS) is an autoinflammatory disease caused by mutations in TNF Receptor 1 (TNFR1). Current therapies for TRAPS are limited and do not target the pro-inflammatory signalling pathways that are central to the disease mechanism. Our aim was to identify drugs for repurposing as anti-inflammatories based on their ability to down-regulate molecules associated with inflammatory signalling pathways that are activated in TRAPS. This was achieved using rigorously optimised, high through- put cell culture and reverse phase protein microarray systems to screen compounds for their effects on the TRAPS-associated inflammatory signalome. 1360 approved, publically available, pharmacologically active substances were investigated for their effects on 40 signalling molecules associated with pro-inflammatory signalling pathways that are constitutively upregulated in TRAPS. The drugs were screened at four ten-fold concentrations on cell lines expressing both wild-type (WT) TNFR1 and TRAPS-associated C33Y mutant TNFR1, or WT TNFR1 alone; signalling molecule levels were then determined in cell lysates by the reverse phase protein microarray. A novel mathematical methodology was developed to rank the compounds for their ability to reduce the expression of signalling molecules in the C33Y-TNFR1 transfectants towards the level seen in the WT-TNFR1 transfectants. Seven high-ranking drugs were selected and tested by RPPA for effects on the same 40 signalling molecules in lysates of peripheral blood mononuclear cells (PBMCs) from C33Y-TRAPS patients compared to PBMCs from normal controls. The fluoroquinolone antibiotic lomefloxacin, as well as others from this class of compounds, showed the most significant effects on multiple pro-inflammatory signalling pathways that are constitutively activated in TRAPS; lomefloxacin dose-dependently significantly reduced expression of 7/40 signalling molecules across the Jak/Stat, MAPK, NF-kB and PI3K/AKT pathways. This study demonstrates the power of signalome screening for identifying candidates for drug repurposing

First Report of Circulating MicroRNAs in Tumour Necrosis Factor Receptor-Associated Periodic Syndrome (TRAPS)

Tumor necrosis factor-receptor associated periodic syndrome (TRAPS) is a rare autosomal dominant autoinflammatory disorder characterized by recurrent episodes of long-lasting fever and inflammation in different regions of the body, such as the musculo-skeletal system, skin, gastrointestinal tract, serosal membranes and eye. Our aims were to evaluate circulating microRNAs (miRNAs) levels in patients with TRAPS, in comparison to controls without inflammatory diseases, and to correlate their levels with parameters of disease activity and/or disease severity. Expression levels of circulating miRNAs were measured by Agilent microarrays in 29 serum samples from 15 TRAPS patients carrying mutations known to be associated with high disease penetrance and from 8 controls without inflammatory diseases. Differentially expressed and clinically relevant miRNAs were detected using GeneSpring GX software. We identified a 6 miRNAs signature able to discriminate TRAPS from controls. Moreover, 4 miRNAs were differentially expressed between patients treated with the interleukin (IL)-1 receptor antagonist, anakinra, and untreated patients. Of these, miR-92a-3p and miR-150-3p expression was found to be significantly reduced in untreated patients, while their expression levels were similar to controls in samples obtained during anakinra treatment. MiR-92b levels were inversely correlated with the number of fever attacks/year during the 1st year from the index attack of TRAPS, while miR-377-5p levels were positively correlated with serum amyloid A (SAA) circulating levels. Our data suggest that serum miRNA levels show a baseline pattern in TRAPS, and may serve as potential markers of response to therapeutic intervention

CEACAM1 Negatively Regulates IL-1β Production in LPS Activated Neutrophils by Recruiting SHP-1 to a SYK-TLR4-CEACAM1 Complex

LPS-activated neutrophils secrete IL-1β by activation of TLR-4. Based on studies in macrophages, it is likely that ROS and lysosomal destabilization regulated by Syk activation may also be involved. Since neutrophils have abundant expression of the ITIM-containing co-receptor CEACAM1 and Gram-negative bacteria such as Neisseria utilize CEACAM1 as a receptor that inhibits inflammation, we hypothesized that the overall production of IL-1β in LPS treated neutrophils may be negatively regulated by CEACAM1. We found that LPS treated neutrophils induced phosphorylation of Syk resulting in the formation of a complex including TLR4, p-Syk, and p-CEACAM1, which in turn, recruited the inhibitory phosphatase SHP-1. LPS treatment leads to ROS production, lysosomal damage, caspase-1 activation and IL-1β secretion in neutrophils. The absence of this regulation in Ceacam1−/− neutrophils led to hyper production of IL-1β in response to LPS. The hyper production of IL-1β was abrogated by in vivo reconstitution of wild type but not ITIM-mutated CEACAM1 bone marrow stem cells. Blocking Syk activation by kinase inhibitors or RNAi reduced Syk phosphorylation, lysosomal destabilization, ROS production, and caspase-1 activation in Ceacam1−/− neutrophils. We conclude that LPS treatment of neutrophils triggers formation of a complex of TLR4 with pSyk and pCEACAM1, which upon recruitment of SHP-1 to the ITIMs of pCEACAM1, inhibits IL-1β production by the inflammasome. Thus, CEACAM1 fine-tunes IL-1β production in LPS treated neutrophils, explaining why the additional utilization of CEACAM1 as a pathogen receptor would further inhibit inflammation