Alliin alleviates LPS-induced pyroptosis via promoting mitophagy in THP-1 macrophages and mice.

Pyroptosis is a new type of programmed cell death associated with inflammation. Excessive pyroptosis can cause body damage. Alliin is an organosulfur compound extracted from garlic, bearing anti-oxidation and anti-inflammatory properties. In this study, we revealed that alliin alleviated LPS-induced macrophage pyroptosis by detecting PI staining, IL-1ß and IL-18 release in vitro and in vivo. In the study of mechanism, we found that alliin might reduce the activation of NLRP3 inflammosome by decreasing intracellular ROS generation. Subsequently, we detected the effect of alliin on mitophagy which degraded damaged mitochondria. The results showed that alliin promoted PINK 1/Parkin-mediated mitophagy. After adding the mitophagy inhibitor CsA, the alleviating effect of alliin on mitochondrial damage and mitochondrial ROS were reversed and the relieving effect of alliin on LPS-induced pyroptosis was inhibited. These results suggested that alliin might reduce intracellular ROS production by promoting mitophagy, thus alleviating LPS-induced macrophages pyroptosis. Our study provides a new perspective and theoretical basis for alliin to alleviate pyroptosis which could further induce body damage.

Soy isoflavones ameliorate experimental colitis by targeting ERα/NLRP3 inflammasome pathways.

Soy isoflavones (SIFs) are selective estrogen receptor modulators (SERMs) that have anti-inflammatory activities. Our previous study found that estrogen receptor α (ERα) directly regulates the NLRP3 transcription and NLRP3 inflammasome assembly. Therefore, we hypothesized that SIFs alleviate colitis via an ERα-dependent mechanism by targeting the NLRP3 inflammasome. The influence of SIFs on colitis and the potential mechanisms were thoroughly determined in this study. The results suggested that SIFs ameliorated dextran sodium sulfate (DSS)-induced body weight loss, reduced disease activity index and promoted the recovery of colon pathological damage in mice. Moreover, expression of the NLRP3 inflammasome was significantly inhibited, and the release of IL-1ß and IL-18 was suppressed by SIFs. Furthermore, ERα blockade ameliorated DSS-induced inflammatory responses in the intestine, and SIFs markedly suppressed the expression of ERα in a dose-dependent manner. Our study demonstrated that the protective therapeutic action of SIFs on DSS-induced colitis depended on inhibition of ERα and subsequent NLRP3 inflammasome activation, and SIFs are promising therapeutic agents for the treatment of colitis.

[Molecular regulative mechanisms of NLRP3 inflammasome activation in diabetic nephropathy and interventional effects of Chinese herbal medicine].

The progression of renal damage in diabetic nephropathy(DN)is closely related to Nod-like receptor protein3(NLRP3)inflammasome activation. The characteristics of NLRP3 inflammasome activation include the changed expression and combination levels of NLRP3, apoptosis-associated speck-like protein(ASC)and pro-caspase-1, the increased expression levels of caspase-1, interleukin(IL)-1ß and IL-18 and the excessive release levels of the relative inflammatory mediators. Its molecular regulative mechanisms involve the activation of multiple signaling pathways including reactive oxygen species(ROS)/thioredoxin-interacting protein(TXNIP)pathway, nuclear factor(NF)-κB pathway, nuclear factor erythroid-related factor 2(Nrf2)pathway, long non-coding RNA(lncRNA)pathway and mitogen-activated protein kinases(MAPKs)pathway. In addition, more importantly, never in mitosis aspergillus-related kinase 7(Nek7), as a kinase regulator, could target-combine with NLRP3 at upstream to activate NLRP3 inflammasome. Some extracts of Chinese herbal medicines(CHMs)such as quercetin, curcumin, cepharanthine, piperine and salidroside, as well as Chinese herbal compound prescriptions such as Wumei Pills both could treat NLRP3 inflammasome to ameliorate inflammatory renal damage in DN. Therefore, accurately clarifying the targets of anti-inflammatory CHMs and Chinese herbal compound prescriptions delaying DN progression by targeting the molecular regulative mechanisms of NLRP3 inflammasome activation will be one of the development directions in the future.

Using high-throughput sequencing to explore the anti-inflammatory effects of α-mangostin.

Lipopolysaccharide (LPS) causes an inflammatory response, and α-mangostin (α-MG) is an ingredient of a Chinese herbal medicine with anti-inflammatory effects. We investigated the mechanism by which α-MG reduces LPS-stimulated IEC-6 cells inflammation. A genome-wide examination of control, LPS-stimulated, and α-MG-pretreated cells was performed with the Illumina Hiseq sequencing platform, and gene expression was verified with quantitative real-time PCR (qPCR). Among the 37,199 genes profiled, 2014 genes were regulated in the LPS group, and 475 genes were regulated in the α-MG group. GO enrichment and KEGG pathway analyses of the differentially expressed genes (DEGs) showed that they were mainly related to inflammation and oxidative stress. Based on the transcriptomic results, we constructed a rat model of inflammatory bowel disease (IBD) with LPS and investigated the effects of α-MG on NLRP3 inflammasomes. After LPS stimulation, the rat intestinal villi were significantly detached, with congestion and hemorrhage; the intestinal epithelial cell nuclei were deformed; and the mitochondria were swollen. However, after pretreatment with α-MG, the intestinal villus congestion and hemorrhage were reduced, the epithelial nuclei were rounded, and the mitochondrial morphology was intact. qPCR and western blotting were used to detect NLRP3, caspase 1, interleukin (IL)-18, and IL-1ß expression at the gene and protein levels. Their expression increased at both the transcript and protein levels after LPS stimulation, whereas it decreased after pretreatment with α-MG. This study provides new methods and ideas for the treatment of inflammation. α-MG may have utility as a drug for intestinal inflammation.

Effectiveness of Huai Qi Huang Granules on Juvenile Collagen-induced Arthritis and Its Influence on Pyroptosis Pathway in Synovial Tissue.

Huai Qi Huang (HQH) exerts great effects in clinic, such as anti-inflammation, immune-regulation, anti-cancer, and so on. However, the mechanism by which HQH protects juvenile idiopathic arthritis (JIA) is obscure. Thus, we explored deeply the protective mechanisms in juvenile collagen-induced arthritis (CIA) rat model. Pyroptosis is Gasdermin D (GSDMD)-dependent programmed cell death, involved in many diseases, such as sepsis. We investigated whether GSDMD-induced pyroptosis take part in mechanisms of juvenile CIA arthritis. Juvenile Wistar rats (3-4 weeks) were injected intradermally with fully emulsified bovine type II collagen and complete Freund's adjuvant to establish CIA rat models. Later, the CIA rats received oral administration of HQH (4.16 g/kg) once a day from the day 21 of modeling, with the treatment lasting for 28 days. Varieties of indicators were measured for evaluation of anti-inflammation effect of HQH, including hind paw swelling, arthritis scores, micro CT, and histopathological changes and the level of pro-inflammatory cytokines in the serum, including tumor necrosis factor alpha (TNF-±) and interleukin-18 (IL-18). The expression of GSDMD and caspase-1 in the joint synovial tissues was detected. The results demonstrated that the expression of the pyroptotic protein GSDMD and its upstream caspase-1 was significantly increased in the synovial tissues of CIA rats. The treatment of HQH ameliorated the symptoms in CIA rats, reduced levels of pro-inflammatory cytokines and hind paw swelling, down-regulated the expression of GDSMD and caspase-1. GSDMD-induced pyroptosis participated in the pathogenesis of CIA rats. The study supported that HQH can effectively improve joints inflammation of juvenile collagen-induced arthritis rats by inhibiting pyroptosis pathway in the joint synovial tissues.

Berberine inhibits NLRP3 Inflammasome pathway in human triple-negative breast cancer MDA-MB-231 cell.

BACKGROUND: Breast cancer is still the most common malignant tumor that threatens the female's life in the world, especially triple-negative breast cancer (TNBC), one of the most difficult subtypes. Lack of targeted therapies brings about urgent demand for novel treatments. In this study we aim to investigate the anti-tumor activity of Berberine (BBR), a Chinese plant-derived alkaloid, against the TNBC cell line MDA-MB-231 and elucidate its mechanism referring to anti-inflammation. METHODS: Cell inhibition rate was measured by Cell Proliferation Assay, the cytotoxic effects was detected by Lactate dehydrogenase (LDH) leakage assay, the colony formation and migration potential were evaluated by colony formation assay and wound healing assay, the release of inflammatory cytokines was detected by EMD multifactor detection, and alterations of proteins and genes related to the NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway were analyzed using western blotting and real-time Polymerase Chain Reaction (PCR). RESULTS: BBR reduce the viability of MDA-MB-231 cells and increased the release of LDH from the cells in a dose-dependent manner, with and inhibition of colony formation potential and migration of the cells. BBR also caused a marked reduction in the secretion of proinflammatory cytokines, Interleukin-1α (IL-1α), Interleukin-1ß (IL-1ß), Interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Besides, a down-regulated behavior was observed with the expression of P2X purinoceptor 7 (P2X7), NLRP3, pro-caspase-1, apoptosis-associated speck-like protein containing a caspase-activation and recruitment domain (ASC), caspase-1 p20, Interleukin-18 (IL-18), IL-1ß proteins and NLRP3, Caspase-1 and ASC mRNAs in the NLRP3 inflammasome cascade. CONCLUSIONS: Our results confirmed that BBR can effectively affect both tumor outgrowth and spontaneous metastasis in TNBC, and that we identified a new mechanism associated with inhibition the NLRP3 inflammasome pathway, suggesting its potential therapeutic relevance in clinical use.

Decryption of Active Constituents and Action Mechanism of the Traditional Uighur Prescription (BXXTR) Alleviating IMQ-Induced Psoriasis-Like Skin Inflammation in BALB/c Mice.

Bai Xuan Xia Ta Re Pian (BXXTR) is a traditional Uighur medicine ancient prescription in China widely used in the treatment of psoriasis, presenting a high curative rate and few side effects. Given that the active constituents and action mechanism still remain unclear, the aim of this study is to explore the potential active constituents and mechanism of antipsoriasis of BXXTR. Psoriasis-like lesions model in BALB/c mice was induced by Imiquimod (IMQ), including five treatment groups: control group, IMQ-treated group, IMQ-ACITRETIN group (Positive control group), IMQ-BXXTR low dose group, IMQ-BXXTR medium dose group and IMQ-BXXTR high dose group. The Psoriasis Area and Severity Index (PASI) score, skin and ear thickness, and histologic section were collected. The differentially expressed genes were determined by using RNAseq technology and the relevant pathways were analyzed by KEGG database. The ELISA kit and western blot assays were used to detect the related protein expression levels. In addition, the chemical constituents of BXXTR were determined by UPLC-TOF-MS analysis and the potential active constituents were predicted by SEA DOCK and Gene Ontology (GO). The data demonstrated that BXXTR significantly alleviated IMQ-induced psoriasis. RNA-seq analysis showed that BXXTR induced the expression levels of 31 genes; the KEGG analysis suggested that BXXTR could significantly change IL-17-related inflammatory pathways. The ELISA kit confirmed that the expression level of IL-17A protein was significantly reduced. 75 compounds of BXXTR were determined by UPLC-TOF-MS analysis, 11 of 75 compounds were identified as potential active compounds by similarity ensemble approach docking (SEA DOCK) and Gene Ontology (GO). BXXTR reduced the severity of skin lesions by inhibiting IL-17-related inflammatory pathways. The results indicated that BXXTR could suppress psoriasis inflammation by multiple-constituents-regulated multiple targets synergistically. Collectively, this study could provide important guidance for the elucidation of the active constituents and action mechanism of BXXTR for the treatment of psoriasis.

Interleukin-18 diagnostically distinguishes and pathogenically promotes human and murine macrophage activation syndrome.

Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337S mutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337S intestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ-induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3, and Mefv predominated in neutrophils, whereas Nlrc4 and Il18 were distinctly epithelial. Demonstrating the importance of free IL-18, Il18 transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337S mice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18-driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.

Anti-hyperuricemic and anti-inflammatory actions of vaticaffinol isolated from Dipterocarpus alatus in hyperuricemic mice.

The present study was designed to examine the anti-hyperuricemic and anti-inflammatory effects and possible mechanisms of vaticaffinol, a resveratrol tetramer isolated from ethanol extracts of Dipterocarpus alatus, in oxonate-induced hyperuricemic mice. At 1 h after 250 mg·kg-1 potassium oxonate was given, vaticaffinol at 20, 40, and 60 mg·kg-1 was intragastrically administered to hyperuricemic mice once daily for seven consecutive days. Vaticaffinol significantly decreased serum uric acid levels and improved kidney function in hyperuricemic mice. It inhibited hepatic activity of xanthine dehydrogenase (XDH) and xanthine oxidase (XOD), regulated renal mRNA and protein levels of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporter 1 (OAT1), organic cation transporter 1 (OCT1), OCT2, organic cation/carnitine transporter 1 (OCTN1), and OCTN2 in hyperuricemic mice. Moreover, vaticaffinol markedly down-regulated renal protein levels of NOD-like receptor 3 (NLRP3), apoptosis-associated speck-like (ASC), and Caspase-1, resulting in the reduction of interleukin (IL)-1ß, IL-18, IL-6 and tumor necrosis factor-α (TNF-α) levels in this animal model. Additionally, HPLC and LC-MS analyses clearly testified the presence of vaticaffinol in the crude extract. These results suggest that vaticaffinol may be useful for the prevention and treatment of hyperuricemia with kidney inflammation.

Inflammasomes Coordinate Pyroptosis and Natural Killer Cell Cytotoxicity to Clear Infection by a Ubiquitous Environmental Bacterium.

Defective neutrophils in patients with chronic granulomatous disease (CGD) cause susceptibility to extracellular and intracellular infections. Microbes must first be ejected from intracellular niches to expose them to neutrophil attack, so we hypothesized that inflammasomes detect certain CGD pathogens upstream of neutrophil killing. Here, we identified one such ubiquitous environmental bacterium, Chromobacterium violaceum, whose extreme virulence was fully counteracted by the NLRC4 inflammasome. Caspase-1 protected via two parallel pathways that eliminated intracellular replication niches. Pyroptosis was the primary bacterial clearance mechanism in the spleen, but both pyroptosis and interleukin-18 (IL-18)-driven natural killer (NK) cell responses were required for liver defense. NK cells cleared hepatocyte replication niches via perforin-dependent cytotoxicity, whereas interferon-γ was not required. These insights suggested a therapeutic approach: exogenous IL-18 restored perforin-dependent cytotoxicity during infection by the inflammasome-evasive bacterium Listeria monocytogenes. Therefore, inflammasomes can trigger complementary programmed cell death mechanisms, directing sterilizing immunity against intracellular bacterial pathogens.

Interleukin-18 Down-Regulates Multidrug Resistance-Associated Protein 2 Expression through Farnesoid X Receptor Associated with Nuclear Factor Kappa B and Yin Yang 1 in Human Hepatoma HepG2 Cells.

Multidrug resistance-associated protein 2 (MRP2) plays an important role in bile acid metabolism by transporting toxic organic anion conjugates, including conjugated bilirubin, glutathione, sulfate, and multifarious drugs. MRP2 expression is reduced in cholestatic patients and rodents. However, the molecular mechanism of MRP2 down-regulation remains elusive. In this report, we treated human hepatoma HepG2 cells with interleukin-18 (IL-18) and measured the expression of MRP2, nuclear factor kappa B (NF-κB), farnesoid X receptor (FXR), and the transcription factor Yin Yang 1 (YY1) by quantitative real-time quantitative polymerase chain reaction (PCR) and western blotting. We found that expression of MRP2 was repressed by IL-18 at both the mRNA and protein levels in a dose- and time-dependent manner. Furthermore, the activated NF-κB pathway increased YY1 and reduced FXR. These changes were all attenuated in HepG2 cells with knockdown of the NF-κB subunit, p65. The reduced expression of FXR and MRP2 in HepG2 cells that had been caused by IL-18 treatment was also attenuated by YY1 knockdown. We further observed significantly elevated IL-18, NF-κB, and YY1 expression and decreased FXR and MRP2 expression in bile duct-ligated Sprague Dawley rat livers. Chromatin immunoprecipitation assays also showed that FXR bound to the promoter region in MRP2 was less abundant in liver extracts from bile duct-ligated rats than sham-operated rats. Our findings indicate that IL-18 down-regulates MRP2 expression through the nuclear receptor FXR in HepG2 cells, and may be mediated by NF-κB and YY1.

Inflammasome-dependent and -independent IL-18 production mediates immunity to the ISCOMATRIX adjuvant.

Adjuvants are an essential component of modern vaccines and used for their ability to elicit immunity to coadministered Ags. Many adjuvants in clinical development are particulates, but how they drive innate and adaptive immune responses remains poorly understood. Studies have shown that a number of vaccine adjuvants activate inflammasome pathways in isolated APCs. However, the contribution of inflammasome activation to vaccine-mediated immunity in vivo remains controversial. In this study, we evaluated immune cell responses to the ISCOMATRIX adjuvant (IMX) in mice. Like other particulate vaccine adjuvants, IMX potently activated the NALP-3-ASC-Caspase-1 inflammasome in APCs, leading to IL-1ß and IL-18 production. The IL-18R pathway, but not IL-1R, was required for early innate and subsequent cellular immune responses to a model IMX vaccine. APCs directly exposed to IMX underwent an endosome-mediated cell-death response, which we propose initiates inflammatory events locally at the injection site. Importantly, both inflammasome-related and -unrelated pathways contributed to IL-18 dependence in vivo following IMX administration. TNF-α provided a physiological priming signal for inflammasome-dependent IL-18 production by APCs, which correlated with reduced vaccine-mediated immune cell responses in TNF-α- or TNFR-deficient mice. Taken together, our findings highlight an important disconnect between the mechanisms of vaccine adjuvant action in vitro versus in vivo.

Bronchial hyperresponsiveness in seasonal allergic rhinitis patients is associated with increased IL-18 during natural pollen exposure.

BACKGROUND: The mechanism of bronchial hyperresponsiveness (BHR) is not certain in seasonal allergic rhinitis (SAR) patients. OBJECTIVE: We aimed to investigate the effects of natural pollen exposure on IL-18 and its relationship with BHR. METHODS: Thirty-two SAR patients with grass pollen sensitivity, 14 nonallergic rhinitis (NAR) patients and 17 normal-controls were included. Sixteen SAR patients had BHR during pollen season and off-season. Serum IL-18 levels were measured in SAR patients during pollen season between May-August and off-season between November-February. IL-18 levels were measured in NAR patients and normal controls once. RESULTS: During pollen season, SAR patients with BHR had significantly increased levels of IL-18 than those without BHR (279.2 ± 161.1 versus 145.3 ± 101.0 pg/ml, p=0.012). Serum IL-18 levels were not different between SAR patients with and without BHR during off-season (233.8 ± 139.7 versus 183.2 ± 162.9 pg/ml, p=0.16). Serum IL-18 levels in SAR patients during pollen season (212.3 ± 148.8 pg/ml) and off-season (208.5 ± 151.5 pg/ml) were not different than those NAR patients (224.8 ± 180.1 pg/ml, p=0.98 and p=1.0, respectively) and normal controls (174.8 ± 76.0 pg/ml, p=0.60 and p=0.76, respectively). CONCLUSION: The results suggested us that BHR in SAR patients is associated with increased IL-18 during natural pollen exposure.

Amorphous silica nanoparticles size-dependently aggravate atopic dermatitis-like skin lesions following an intradermal injection.

BACKGROUND: Due to the rising use of nanomaterials (NMs), there is concern that NMs induce undesirable biological effects because of their unique physicochemical properties. Recently, we reported that amorphous silica nanoparticles (nSPs), which are one of the most widely used NMs, can penetrate the skin barrier and induce various biological effects, including an immune-modulating effect. Thus, it should be clarified whether nSPs can be a risk factor for the aggravation of skin immune diseases. Thus, in this study, we investigated the relationship between the size of SPs and adjuvant activity using a model for atopic dermatitis. RESULTS: We investigated the effects of nSPs on the AD induced by intradermaly injected-mite antigen Dermatophagoides pteronyssinus (Dp) in NC/Nga mice. Ear thickness measurements and histopathological analysis revealed that a combined injection of amorphous silica particles (SPs) and Dp induced aggravation of AD in an SP size-dependent manner compared to that of Dp alone. In particular, aggravation was observed remarkably in nSP-injected groups. Furthermore, these effects were correlated with the excessive induction of total IgE and a stronger systemic Th2 response. We demonstrated that these results are associated with the induction of IL-18 and thymic stromal lymphopoietin (TSLP) in the skin lesions. CONCLUSIONS: A particle size reduction in silica particles enhanced IL-18 and TSLP production, which leads to systemic Th2 response and aggravation of AD-like skin lesions as induced by Dp antigen treatment. We believe that appropriate regulation of nanoparticle physicochemical properties, including sizes, is a critical determinant for the design of safer forms of NMs.

Nucleotide-binding oligomerization domain-like receptors and inflammasomes in the pathogenesis of non-microbial inflammation and diseases.

The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) or nucleotide-binding domain leucine-rich repeat-containing family of genes plays an important role in the development of innate immune responses. Some family members are known to form multiprotein complexes known as inflammasomes that regulate the processing and secretion of proinflammatory mediators, such as interleukin-1ß and interleukin-18. Activity of the inflammasome is triggered not only by microbial infection, but also by a wide range of both exogenous and endogenous noninfectious stimuli. Consequently, the dysregulation of inflammasome activity is associated with numerous proinflammatory, non-microbial human diseases. The discovery of NLRP3 gene mutations in autoinflammatory diseases such as Muckle-Wells syndrome has led to the association of NLRs in the pathogenesis of many non-microbial diseases that include arthritis, neurodegenerative disorders, metabolic disorders (obesity and diabetes), cardiovascular disease (atherosclerosis, myocardial infarction), inflammatory bowel disease, kidney disease and hypersensitivity dermatitis. A number of NLRs are also associated with human disease in the absence of inflammasome activity, suggesting additional roles for NLRs in the regulation of inflammation and disease. This review serves to provide a summary of NLR-associated diseases and, where possible, the mechanisms behind the associations.

Uric acid-driven Th17 differentiation requires inflammasome-derived IL-1 and IL-18.

Uric acid is released from damaged cells and serves as a danger signal that alerts the immune system to potential threats, even in the absence of microbial infection. Uric acid modulation of innate immune responses has been extensively studied, but the impact of this damage-associated molecular pattern on adaptive responses remains largely unknown. In this study, we report that, in the presence of NF-κB signaling, uric acid crystals were capable of stimulating dendritic cells to promote the release of cytokines associated with Th17 polarization. Accordingly, naive CD4(+) T cells cocultured with uric acid-treated dendritic cells differentiated toward the Th17 lineage. Th17 differentiation required the inflammasome-dependent cytokines IL-1α/ß and IL-18 in both in vitro and in vivo models, and the inflammasome adaptor protein ASC and caspase-1 were essential for Th17 responses. Collectively, our findings indicate a novel role for the danger signal uric acid, in cooperation with NF-κB activation, in driving proinflammatory Th17 differentiation. Our data indicate that sterile inflammation shapes adaptive immunity, in addition to influencing early innate responses.

Inflammatory signatures for eosinophilic vs. neutrophilic allergic pulmonary inflammation reveal critical regulatory checkpoints.

Contrary to the T-helper (Th)-2 bias and eosinophil-dominated bronchial inflammation encountered in most asthmatic subjects, other patients may exhibit neutrophil-predominant asthma subphenotypes, along with Th-1 and Th-17 cells. However, the etiology of many neutrophil-dominated asthma subphenotypes remains ill-understood, in part due to a lack of appropriate experimental models. To better understand the distinct immune-pathological features of eosinophilic vs. neutrophilic asthma types, we developed an ovalbumin (OVA)-based mouse model of neutrophil-dominated allergic pulmonary inflammation. Consequently, we probed for particular inflammatory signatures and checkpoints underlying the immune pathology in this new model, as well as in a conventional, eosinophil-dominated asthma model. Briefly, mice were OVA sensitized using either aluminum hydroxide (alum) or complete Freund's adjuvants, followed by OVA aerosol challenge. T-cell, granulocyte, and inflammatory mediator profiles were determined, along with alveolar macrophage genomewide transcriptome profiling. In contrast to the Th-2-dominated phenotype provoked by alum, OVA/ complete Freund's adjuvants adjuvant-based sensitization, followed by allergen challenge, elicited a pulmonary inflammation that was poorly controlled by dexamethasone, and in which Th-1 and Th-17 cells additionally participated. Analysis of the overall pulmonary and alveolar macrophage inflammatory mediator profiles revealed remarkable similarities between both models. Nevertheless, we observed pronounced differences in the IL-12/IFN-γ axis and its control by IL-18 and IL-18 binding protein, but also in macrophage arachidonic acid metabolism and expression of T-cell instructive ligands. These differential signatures, superimposed onto a generic inflammatory signature, denote distinctive inflammatory checkpoints potentially involved in orchestrating neutrophil-dominated asthma.

Mapping of the full length and the truncated interleukin-18 receptor alpha in the mouse brain.

The cytokine IL-18 acts on the CNS both in physiological and pathological conditions. Its action occurs through the heterodimeric receptor IL-18Ralpha\beta. To better understand IL-18 central effects, we investigated in the mouse brain the distribution of two IL-18Ralpha transcripts, a full length and an isoform lacking the intracellular domain hypothesized to be a decoy receptor. Both isoforms were expressed in neurons throughout the brain primarily with overlapping distribution but also with some unique pattern. These data suggest that IL-18 may modulate neuronal functions and that its action may be regulated through expression of a decoy receptor.

The inflammasomes: guardians of the body.

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1beta and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.