NLRP3 inflammasome is required in murine asthma in the absence of aluminum adjuvant.

Background: Inflammasome activation with the production of IL-1 beta received substantial attention recently in inflammatory diseases. However, the role of inflammasome in the pathogenesis of asthma is not clear. Using an adjuvant-free model of allergic lung inflammation induced by ovalbumin (OVA), we investigated the role of NLRP3 inflammasome and related it to IL-1R1 signaling pathway.Methods: Allergic lung inflammation induced by OVA was evaluated in vivo in mice deficient in NLRP3 inflammasome, IL-1R1, IL-1 beta or IL-1 alpha. Eosinophil recruitment, Th2 cytokine, and chemokine levels were determined in bronchoalveolar lavage fluid, lung homogenates, and mediastinal lymph node cells ex vivo.Results: Allergic airway inflammation depends on NLRP3 inflammasome activation. Dendritic cell recruitment into lymph nodes, Th2 lymphocyte activation in the lung and secretion of Th2 cytokines and chemokines are reduced in the absence of NLRP3. Absence of NLRP3 and IL-1 beta is associated with reduced expression of other proinflammatory cytokines such as IL-5, IL-13, IL-33, and thymic stromal lymphopoietin. Furthermore, the critical role of IL-1R1 signaling in allergic inflammation is confirmed in IL-1R1-, IL-1 beta-, and IL-1 alpha-deficient mice.Conclusion: NLRP3 inflammasome activation leading to IL-1 production is critical for the induction of a Th2 inflammatory allergic response.

The TRAF3-binding site of human molluscipox virus FLIP molecule MC159 is critical for its capacity to inhibit Fas-induced apoptosis.

Members of the viral Flice/caspase-8 inhibitory protein (v-FLIP) family prevent induction of apoptosis by death receptors through inhibition of the processing and activation of procaspase-8 and -10 at the level of the receptor-associated death-inducing signaling complex (DISC). Here, we have addressed the molecular function of the v-FLIP member MC159 of the human molluscum contagiosum virus. MC159 FLIP powerfully inhibited both caspase-dependent and caspase-independent cell death induced by Fas. The C-terminal region of MC159 bound TNF receptor-associated factor (TRAF)3, was necessary for optimal TRAF2 binding, and mediated the recruitment of both TRAFs into the Fas DISC. TRAF-binding-deficient mutants of MC159 showed impaired inhibition of FasL-induced caspase-8 processing and Fas internalization, and had reduced antiapoptotic activity. Our findings provide evidence that a MC159/TRAF2/TRAF3 complex regulates a new aspect of Fas signaling, and identify MC159 FLIP as a molecule that targets multiple features of Fas-induced cell death.

Molecular pathways: emerging pathways mediating growth, invasion, and metastasis of tumors progressing in an irradiated microenvironment.

Radiotherapy is a well-established therapeutic modality in oncology. It provides survival benefits in several different cancer types. However, cancers relapsing after radiotherapy often develop into more aggressive conditions that are difficult to treat and are associated with poor prognosis. Cumulative experimental evidence indicates that the irradiated tumor bed contributes to such aggressive behavior. The involved mechanisms have for long remained elusive. Recent progress in the field revealed previously unrecognized cellular and molecular events promoting growth, invasion, and metastasis of tumors progressing in an irradiated microenvironment. Cellular mechanisms include inhibition of sprouting angiogenesis, formation of hypoxia, activation and differentiation of stromal cells, and recruitment of bone marrow-derived cells with vasculogenic and prometastatic activities. Identified pathways include TGF-β/ALK5, CXCL12/CXCR4, KITL/KIT, and CYR61/αVβ5 integrin. The availability of pharmacologic inhibitors impinging on these pathways opens novel opportunities for translational and clinical studies. These experimental results and ongoing work highlight the importance of the irradiated microenvironment in modulating the tumor response to radiotherapy and open new opportunities for the development of novel therapeutic strategies for patients with cancer who relapse after radiotherapy. Here, we review and discuss recent advances in the field and their translational and therapeutic implications to human cancer treatment.

Bcl10 controls TCR- and FcgammaR-induced actin polymerization.

Bcl10 plays an essential role in the adaptive immune response, because Bcl10-deficient lymphocytes show impaired Ag receptor-induced NF-kappaB activation and cytokine production. Bcl10 is a phosphoprotein, but the physiological relevance of this posttranslational modification remains poorly defined. In this study, we report that Bcl10 is rapidly phosphorylated upon activation of human T cells by PMA/ionomycin- or anti-CD3 treatment, and identify Ser(138) as a key residue necessary for Bcl10 phosphorylation. We also show that a phosphorylation-deficient Ser(138)/Ala mutant specifically inhibits TCR-induced actin polymerization yet does not affect NF-kappaB activation. Moreover, silencing of Bcl10, but not of caspase recruitment domain-containing MAGUK protein-1 (Carma1) induces a clear defect in TCR-induced F-actin formation, cell spreading, and conjugate formation. Remarkably, Bcl10 silencing also impairs FcgammaR-induced actin polymerization and phagocytosis in human monocytes. These results point to a key role of Bcl10 in F-actin-dependent immune responses of T cells and monocytes/macrophages.

Differential inhibition of TRAIL-mediated DR5-DISC formation by decoy receptors 1 and 2.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family that induces cancer cell death by apoptosis with some selectivity. TRAIL-induced apoptosis is mediated by the transmembrane receptors death receptor 4 (DR4) (also known as TRAIL-R1) and DR5 (TRAIL-R2). TRAIL can also bind decoy receptor 1 (DcR1) (TRAIL-R3) and DcR2 (TRAIL-R4) that fail to induce apoptosis since they lack and have a truncated cytoplasmic death domain, respectively. In addition, DcR1 and DcR2 inhibit DR4- and DR5-mediated, TRAIL-induced apoptosis and we demonstrate here that this occurs through distinct mechanisms. While DcR1 prevents the assembly of the death-inducing signaling complex (DISC) by titrating TRAIL within lipid rafts, DcR2 is corecruited with DR5 within the DISC, where it inhibits initiator caspase activation. In addition, DcR2 prevents DR4 recruitment within the DR5 DISC. The specificity of DcR1- and DcR2-mediated TRAIL inhibition reveals an additional level of complexity for the regulation of TRAIL signaling.

Crosstalk between neutrophils and dendritic cells: a context-dependent process.

Neutrophils are massively and rapidly recruited following infection. They migrate to the site of acute infection and also transiently to dLNs. In addition to their well-established role as microbial killers, accumulating evidence shows that neutrophils can play an immunoregulatory role. Neutrophils were recently shown to influence the activation of different leukocyte types including NK cells, B cells, and DCs. DCs are professional APCs playing a key role to the launching and regulation of the immune response; thus, crosstalk between neutrophils and resident or newly recruited DCs may have a direct impact on the development of the antigen-specific immune response and thereby, on the outcome of infection. Neutrophils may regulate DC recruitment and/or activation. We will review here recent progress in the field, including those presented during the first international symposium on "Neutrophil in Immunity", held in Québec, Canada, in June 2012, and discuss how neutrophil regulatory action on DCs may differ depending on the type of invading microorganism and local host factors.

LRIG1 inhibits STAT3-dependent inflammation to maintain corneal homeostasis.

Corneal integrity and transparency are indispensable for good vision. Cornea homeostasis is entirely dependent upon corneal stem cells, which are required for complex wound-healing processes that restore corneal integrity following epithelial damage. Here, we found that leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is highly expressed in the human holoclone-type corneal epithelial stem cell population and sporadically expressed in the basal cells of ocular-surface epithelium. In murine models, LRIG1 regulated corneal epithelial cell fate during wound repair. Deletion of Lrig1 resulted in impaired stem cell recruitment following injury and promoted a cell-fate switch from transparent epithelium to keratinized skin-like epidermis, which led to corneal blindness. In addition, we determined that LRIG1 is a negative regulator of the STAT3-dependent inflammatory pathway. Inhibition of STAT3 in corneas of Lrig1-/- mice rescued pathological phenotypes and prevented corneal opacity. Additionally, transgenic mice that expressed a constitutively active form of STAT3 in the corneal epithelium had abnormal features, including corneal plaques and neovascularization similar to that found in Lrig1-/- mice. Bone marrow chimera experiments indicated that LRIG1 also coordinates the function of bone marrow-derived inflammatory cells. Together, our data indicate that LRIG1 orchestrates corneal-tissue transparency and cell fate during repair, and identify LRIG1 as a key regulator of tissue homeostasis.

Disrupting the EMMPRIN (CD147)-cyclophilin A interaction reduces infarct size and preserves systolic function after myocardial ischemia and reperfusion.

Objective-Inflammation and proteolysis crucially contribute to myocardial ischemia and reperfusion injury. The extracellular matrix metalloproteinase inducer EMMPRIN (CD147) and its ligand cyclophilin A (CyPA) may be involved in both processes. The aim of the study was to characterize the role of the CD147 and CyPA interplay in myocardial ischemia/reperfusion (I/R) injury.Methods and Results-Immunohistochemistry showed enhanced expression of CD147 and CyPA in myocardial sections from human autopsies of patients who had died from acute myocardial infarction and from mice at 24 hours after I/R. At 24 hours and 7 days after I/R, the infarct size was reduced in CD147(+/-) mice vs CD147(+/+) mice (C57Bl/6), in mice (C57Bl/6) treated with monoclonal antibody anti-CD147 vs control monoclonal antibody, and in CyPA(-/-) mice vs CyPA(+/+) mice (129S6/SvEv), all of which are associated with reduced monocyte and neutrophil recruitment at 24 hours and with a preserved systolic function at 7 days. The combination of CyPA(-/-) mice with anti-CD147 treatment did not yield further protection compared with either inhibition strategy alone. In vitro, treatment with CyPA induced monocyte chemotaxis in a CD147-and phosphatidylinositol 3-kinase-dependent manner and induced monocyte rolling and adhesion to endothelium (human umbilical vein endothelial cells) under flow in a CD147-dependent manner.Conclusion-CD147 and its ligand CyPA are inflammatory mediators after myocardial ischemia and reperfusion and represent potential targets to prevent myocardial I/R injury.

A concerted kinase interplay identifies PPARgamma as a molecular target of ghrelin signaling in macrophages.

The peroxisome proliferator-activator receptor PPARgamma plays an essential role in vascular biology, modulating macrophage function and atherosclerosis progression. Recently, we have described the beneficial effect of combined activation of the ghrelin/GHS-R1a receptor and the scavenger receptor CD36 to induce macrophage cholesterol release through transcriptional activation of PPARgamma. Although the interplay between CD36 and PPARgamma in atherogenesis is well recognized, the contribution of the ghrelin receptor to regulate PPARgamma remains unknown. Here, we demonstrate that ghrelin triggers PPARgamma activation through a concerted signaling cascade involving Erk1/2 and Akt kinases, resulting in enhanced expression of downstream effectors LXRalpha and ABC sterol transporters in human macrophages. These effects were associated with enhanced PPARgamma phosphorylation independently of the inhibitory conserved serine-84. Src tyrosine kinase Fyn was identified as being recruited to GHS-R1a in response to ghrelin, but failure of activated Fyn to enhance PPARgamma Ser-84 specific phosphorylation relied on the concomitant recruitment of docking protein Dok-1, which prevented optimal activation of the Erk1/2 pathway. Also, substitution of Ser-84 preserved the ghrelin-induced PPARgamma activity and responsiveness to Src inhibition, supporting a mechanism independent of Ser-84 in PPARgamma response to ghrelin. Consistent with this, we found that ghrelin promoted the PI3-K/Akt pathway in a Galphaq-dependent manner, resulting in Akt recruitment to PPARgamma, enhanced PPARgamma phosphorylation and activation independently of Ser-84, and increased expression of LXRalpha and ABCA1/G1. Collectively, these results illustrate a complex interplay involving Fyn/Dok-1/Erk and Galphaq/PI3-K/Akt pathways to transduce in a concerted manner responsiveness of PPARgamma to ghrelin in macrophages.

Designing pheromone communication in swarm robotics: Group foraging behavior mediated by chemical substance

In swarm robotics, communication among the robots is essential. Inspired by biological swarms using pheromones, we propose the use of chemical compounds to realize group foraging behavior in robot swarms. We designed a fully autonomous robot, and then created a swarm using ethanol as the trail pheromone allowing the robots to communicate with one another indirectly via pheromone trails. Our group recruitment and cooperative transport algorithms provide the robots with the required swarm behavior. We conducted both simulations and experiments with real robot swarms, and analyzed the data statistically to investigate any changes caused by pheromone communication in the performance of the swarm in solving foraging recruitment and cooperative transport tasks. The results show that the robots can communicate using pheromone trails, and that the improvement due to pheromone communication may be non-linear, depending on the size of the robot swarm.