Cutting edge: IL-6 is a marker of inflammation with no direct role in inflammasome-mediated mouse models

Exploring the role of granzyme B in subretinal fibrosis of age-related macular degeneration

Age-related macular degeneration (AMD), a prevalent and progressive degenerative disease of the macula, is the leading cause of blindness in elderly individuals in developed countries. The advanced stages include neovascular AMD (nAMD), characterized by choroidal neovascularization (CNV), leading to subretinal fibrosis and permanent vision loss. Despite the efficacy of anti-vascular endothelial growth factor (VEGF) therapy in stabilizing or improving vision in nAMD, the development of subretinal fibrosis following CNV remains a significant concern. In this review, we explore multifaceted aspects of subretinal fibrosis in nAMD, focusing on its clinical manifestations, risk factors, and underlying pathophysiology. We also outline the potential sources of myofibroblast precursors and inflammatory mechanisms underlying their recruitment and transdifferentiation. Special attention is given to the potential role of mast cells in CNV and subretinal fibrosis, with a focus on putative mast cell mediators, tryptase and granzyme B. We summarize our findings on the role of GzmB in CNV and speculate how GzmB may be involved in the pathological transition from CNV to subretinal fibrosis in nAMD. Finally, we discuss the advantages and drawbacks of animal models of subretinal fibrosis and pinpoint potential therapeutic targets for subretinal fibrosis.

Causal impact of human blood metabolites and metabolic pathways on serum uric acid and gout: a mendelian randomization study

Objective

Hyperuricaemia and gout are common metabolic disorders. However, the causal relationships between blood metabolites and serum urate levels, as well as gout, remain unclear. A systematic evaluation of the causal connections between blood metabolites, hyperuricemia, and gout could enhance early screening and prevention of hyperuricemia and gout in clinical settings, providing novel insights and approaches for clinical treatment.

Methods

In this study, we employed a bidirectional two-sample Mendelian randomization analysis utilizing data from a genome-wide association study involving 7,286 participants, encompassing 486 blood metabolites. Serum urate and gout data were sourced from the Chronic Kidney Disease Genetics consortium, including 288,649 participants for serum urate and 9,819 African American and 753,994 European individuals for gout. Initially, LDSC methodology was applied to identify blood metabolites with a genetic relationship to serum urate and gout. Subsequently, inverse-variance weighting was employed as the primary analysis method, with a series of sensitivity and pleiotropy analyses conducted to assess the robustness of the results.

Results

Following LDSC, 133 blood metabolites exhibited a potential genetic relationship with serum urate and gout. In the primary Mendelian randomization analysis using inverse-variance weighting, 19 blood metabolites were recognized as potentially influencing serum urate levels and gout. Subsequently, the IVW p-values of potential metabolites were corrected using the false discovery rate method. We find leucine (IVW P FDR = 0.00004), N-acetylornithine (IVW P FDR = 0.0295), N1-methyl-3-pyridone-4-carboxamide (IVW P FDR = 0.0295), and succinyl carnitine (IVW P FDR = 0.00004) were identified as significant risk factors for elevated serum urate levels. Additionally, 1-oleoylglycerol (IVW P FDR = 0.0007) may lead to a substantial increase in the risk of gout. Succinyl carnitine exhibited acceptable weak heterogeneity, and the results for other blood metabolites remained robust after sensitivity, heterogeneity, and pleiotropy testing. We conducted an enrichment analysis on potential blood metabolites, followed by a metabolic pathway analysis revealing four pathways associated with serum urate levels.

Conclusion

The identified causal relationships between these metabolites and serum urate and gout offer a novel perspective, providing new mechanistic insights into serum urate levels and gout.

E3 ubiquitin ligase RNF128 attenuates colitis and colorectal tumorigenesis by triggering the degradation of IL-6 receptors

INTRODUCTION

Intestinal immune dysregulation is strongly linked to the occurrence and formation of tumors. RING finger protein 128 (RNF128) has been identified to play distinct immunoregulatory functions in innate and adaptive systems. However, the physiological roles of RNF128 in intestinal inflammatory conditions such as colitis and colorectal cancer (CRC) remain controversial.

OBJECTIVES

To elucidate the function and mechanism of RNF128 in colitis and CRC.

METHODS

Animal models of dextran sodium sulfate (DSS)-induced colitis and azoxymethane (AOM)/DSS-induced CRC were established in WT and Rnf128-deficient mice and evaluated by histopathology. Co-immunoprecipitation and ubiquitination analyses were employed to investigate the role of RNF128 in IL-6-STAT3 signaling.

RESULTS

RNF128 was significantly downregulated in clinical CRC tissues compared with paired peritumoral tissues. Rnf128-deficient mice were hypersusceptible to both colitis induced by DSS and CRC induced by AOM/DSS or APC mutation. Loss of RNF128 promoted the proliferation of CRC cells and STAT3 activation during the early transformative stage of carcinogenesis in vivo and in vitro when stimulated by IL-6. Mechanistically, RNF128 interacted with the IL-6 receptor α subunit (IL-6Rα) and membrane glycoprotein gp130 and mediated their lysosomal degradation in ligase activity-dependent manner. Through a series of point mutations in the IL-6 receptor, we identified that RNF128 promoted K48-linked polyubiquitination of IL-6Rα at K398/K401 and gp130 at K718/K816/K866. Additionally, blocking STAT3 activation effectively eradicated the inflammatory damage of Rnf128-deficient mice during the transformative stage of carcinogenesis.

CONCLUSION

RNF128 attenuates colitis and colorectal tumorigenesis by inhibiting IL-6-STAT3 signaling, which sheds novel insights into the modulation of IL-6 receptors and the inflammation-to-cancer transition.

Role of pattern recognition receptors in the development of MASLD and potential therapeutic applications

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become one of the most prevalent liver diseases worldwide, and its occurrence is strongly associated with obesity, insulin resistance (IR), genetics, and metabolic stress. Ranging from simple fatty liver to metabolic dysfunction-associated steatohepatitis (MASH), even to severe complications such as liver fibrosis and advanced cirrhosis or hepatocellular carcinoma, the underlying mechanisms of MASLD progression are complex and involve multiple cellular mediators and related signaling pathways. Pattern recognition receptors (PRRs) from the innate immune system, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), RIG-like receptors (RLRs), and DNA receptors, have been demonstrated to potentially contribute to the pathogenesis for MASLD. Their signaling pathways can induce inflammation, mediate oxidative stress, and affect the gut microbiota balance, ultimately resulting in hepatic steatosis, inflammatory injury and fibrosis. Here we review the available literature regarding the involvement of PRR-associated signals in the pathogenic and clinical features of MASLD, in vitro and in animal models of MASLD. We also discuss the emerging targets from PRRs for drug developments that involved agent therapies intended to arrest or reverse disease progression, thus enabling the refinement of therapeutic targets that can accelerate drug development.

The discovery of NLRP3 and its function in cryopyrin-associated periodic syndromes and innate immunity

From studies of individual families to global collaborative efforts, the NLRP3 inflammasome is now recognized to be a key regulator of innate immunity. Activated by a panoply of pathogen-associated and endogenous triggers, NLRP3 serves as an intracellular sensor that drives carefully coordinated assembly of the inflammasome, and downstream inflammation mediated by IL-1 and IL-18. Initially discovered as the cause of the autoinflammatory spectrum of cryopyrin-associated periodic syndrome (CAPS), NLRP3 is now also known to play a role in more common diseases including cardiovascular disease, gout, and liver disease. We have seen cohesion in results from clinical studies in CAPS patients, ex vivo studies of human cells and murine cells, and in vivo murine models leading to our understanding of the downstream pathways, cytokine secretion, and cell death pathways that has solidified the role of autoinflammation in the pathogenesis of human disease. Recent advances in our understanding of the structure of the inflammasome have provided ways for us to visualize normal and mutant protein function and pharmacologic inhibition. The subsequent development of targeted therapies successfully used in the treatment of patients with CAPS completes the bench to bedside translational loop which has defined the study of this unique protein.

A novel Nlrp3 knock-in mouse model with hyperactive inflammasome in development of lethal inflammation

NOD-like receptor family, pyrin domain-containing 3 (NLRP3) is a central protein contributing to human inflammatory disorders, including cryopyrin-associated periodic syndrome and sepsis. However, the molecular mechanisms and functions of NLRP3 activation in various diseases remain unknown. Here, we generated gain-of-function knock-in mice associated with Muckle-Wells syndromes using the Cre-LoxP system allowing for the constitutive T346M mutation of NLRP3 to be globally expressed in all cells under the control of tamoxifen. The mice were treated with tamoxifen for 4 days before determining their genotype by PCR and sequence analysis. In vitro, we found that bone marrow-derived macrophage from homozygous T346M mutation mice displayed a robust ability to produce IL-1β in response to lipopolysaccharide exposure. Moreover, ASC specks and oligomerization were observed in the homozygous mutant bone marrow-derived macrophages in the presence of lipopolysaccharides alone. Mechanistically, K+ and Ca2+ depletion and mitochondrial depolarization contribute to the hyperactivation of mutant NLRP3. In vivo, homozygous mice carrying the T346M mutation exhibit weight loss and mild inflammation in the resting state. In the lipopolysaccharide-mediated sepsis model, homozygous mutant mice exhibited higher mortality and increased serum circulating cytokine levels, accompanied by serious liver injury. Furthermore, an increase in myeloid cells in the spleen has been suggested to be a risk factor for inducing sepsis sensitivity. Altogether, we describe a cryopyrin-associated syndrome animal model with the T346M mutation of NLRP3 and suggest that the hyperactivated inflammasome aggregated by the mutant NLRP3 lowers the inflammatory response threshold both in vitro and in vivo.

Pathogenic NLRP3 mutants form constitutively active inflammasomes resulting in immune-metabolic limitation of IL-1β production

Cryopyrin-associated periodic syndrome (CAPS) is an autoinflammatory condition resulting from monoallelic NLRP3 variants that facilitate IL-1β production. Although these are gain-of-function variants characterized by hypersensitivity to cell priming, patients with CAPS and animal models of the disease may present inflammatory flares without identifiable external triggers. Here we find that CAPS-associated NLRP3 variants are forming constitutively active inflammasome, which induce increased basal cleavage of gasdermin D, IL-18 release and pyroptosis, with a concurrent basal pro-inflammatory gene expression signature, including the induction of nuclear receptors 4 A. The constitutively active NLRP3-inflammasome of CAPS is responsive to the selective NLRP3 inhibitor MCC950 and its activation is regulated by deubiquitination. Despite their preactivated state, the CAPS inflammasomes are responsive to activation of the NF-κB pathway. NLRP3-inflammasomes with CAPS-associated variants affect the immunometabolism of the myeloid compartment, leading to disruptions in lipids and amino acid pathways and impaired glycolysis, limiting IL-1β production. In summary, NLRP3 variants causing CAPS form a constitutively active inflammasome inducing pyroptosis and IL-18 release without cell priming, which enables the host's innate defence against pathogens while also limiting IL-1β-dependent inflammatory episodes through immunometabolism modulation.

Role of immune inflammation regulated by macrophage in the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) can lead to irreversible impairment of visual function, and the number of patients with AMD has been increasing globally. The immunoinflammatory theory is an important pathogenic mechanism of AMD, with macrophages serving as the primary inflammatory infiltrating cells in AMD lesions. Its powerful immunoinflammatory regulatory function has attracted considerable attention. Herein, we provide an overview of the involvement of macrophage-regulated immunoinflammation in different stages of AMD. Additionally, we summarize novel therapeutic approaches for AMD, focusing on targeting macrophages, such as macrophage/microglia modulators, reduction of macrophage aggregation in the subretinal space, modulation of macrophage effector function, macrophage phenotypic alterations, and novel biomimetic nanocomposites development based on macrophage-associated functional properties. We aimed to provide a basis and reference for the further exploration of AMD pathogenesis, developmental influences, and new therapeutic approaches.

A study integrated metabolomics and network pharmacology to investigate the effects of Shicao in alleviating acute liver injury

ETHNOPHARMACOLOGICAL RELEVANCE

Shicao is the aerial part of Achillea alpina L., a common herb found mainly in Europe, Asia, and North America. Traditional Chinese medicine has a history of thousands of years and is widely used to treat various diseases.

AIM OF STUDY

To explore the hepatoprotective effects of Shicao on CCl4-induced acute liver injury.

METHODS

A rat model of acute liver injury was established and liver function indices were assessed to evaluate the protective effect of Shicao on the liver. Untargeted metabolomics of the serum and liver tissues was conducted using UPLC-Q-TOF/MS to identify differential metabolites related to acute liver injury. A network of metabolite-reaction-enzyme-gene constituents was constructed using network pharmacology. Hub targets and key components of the effect of Shicao on acute liver injury were screened from the network.

RESULTS

Compared to the model group, Shicao improved the degree of liver damage through the assessment of the liver index, ALT and AST levels, and hepatic pathology slices, demonstrating its hepatoprotective effect against acute liver injury in rats. 10 and 38 differential metabolites involved in acute liver injury were identified in serum and liver tissues, respectively. Most of these were regulated or restored following treatment with Shicao, which mainly consisted of bile acids, lipids, and nucleotides such as taurocholic acid, LysoPC (17:0), and adenosine diphosphate ribose. Through the network of metabolite-reaction-enzyme-gene-constituents, 10 key components and 5 hub genes, along with 7 crucial differential metabolites, were mainly involved in glycerophospholipid metabolism, purine metabolism, biosynthesis of unsaturated fatty acids, and primary bile acid biosynthesis, which may play important roles in the prevention of acute liver injury by Shicao.

CONCLUSION

This study revealed that Shicao had protective effects against CCl4-induced liver injury in rats. It was speculated that the ingredients of Shicao might be closely related to the hub targets, thereby regulating the levels of key metabolites, affecting inflammatory response and oxidative stress and attenuate the liver injury consequently. This study provides a basis for further investigation of its therapeutic potential and the mechanism of action.

KCNN4 links PIEZO-dependent mechanotransduction to NLRP3 inflammasome activation

Immune cells sense the microenvironment to fine-tune their inflammatory responses. Patients with cryopyrin-associated periodic syndrome (CAPS), caused by mutations in the NLRP3 gene, develop autoinflammation triggered by nonantigenic cues such as from the environment. However, the underlying mechanisms are poorly understood. Here, we uncover that KCNN4, a calcium-activated potassium channel, links PIEZO-mediated mechanotransduction to NLRP3 inflammasome activation. Yoda1, a PIEZO1 agonist, lowered the threshold for NLRP3 inflammasome activation. PIEZO-mediated sensing of stiffness and shear stress increased NLRP3-dependent inflammation. Myeloid-specific deletion of PIEZO1/2 protected mice from gouty arthritis. Mechanistically, activation of PIEZO1 triggers calcium influx, which activates KCNN4 to evoke potassium efflux and promotes NLRP3 inflammasome activation. Activation of PIEZO signaling was sufficient to activate the inflammasome in cells expressing CAPS-causing NLRP3 mutants via KCNN4. Last, pharmacological inhibition of KCNN4 alleviated autoinflammation in cells of patients with CAPS and in mice bearing a CAPS mutation. Thus, PIEZO-dependent mechanical inputs boost inflammation in NLRP3-dependent diseases, including CAPS.

Impairing Gasdermin D-mediated pyroptosis is protective against retinal degeneration

BACKGROUND

Inflammasome activation and the subsequent release of pro-inflammatory cytokines including Interleukin 1β (IL-1β) have been widely reported to contribute to the progression of retinal degenerations, including age-related macular degeneration (AMD), the leading cause of blindness in the Western World. The role of Gasdermin D (GSDMD), a key executioner of pyroptosis following inflammasome activation, however, is less well-established. In this study we aimed to characterise the role of GSDMD in the healthy and degenerating retina, and uncover its role as a conduit for IL-1β release, including via extracellular vesicle (EV)-mediated release.

METHODS

GSDMD mutant and knockout mice, in vitro models of inflammation and a well-established in vivo model of retinal degeneration (photo-oxidative damage; PD) were utilised to explore the role and pathological contribution of GSDMD in regulating IL-1β release and propagating retinal inflammation. RNA sequencing of whole retinas was used to investigate GSDMD-mediated inflammation during degeneration. The role of EVs in GSDMD-mediated IL-1β release was investigated using nanoparticle tracking analysis, ELISA and EV inhibition paradigms. Finally, the therapeutic efficacy of targeting GSDMD was examined using GSDMD-specific siRNA.

RESULTS

We identified in this work that mice deficient in GSDMD had better-preserved retinal function, increased photoreceptor survivability and reduced inflammation. RNA-Seq analysis revealed that GSDMD may propagate inflammation in the retina via NF-κB signalling cascades and release of pro-inflammatory cytokines. We also showed that IL-1β was packaged and released via EV in a GSDMD-dependent manner. Finally, we demonstrated that impairing GSDMD function using RNAi or blocking EV release was able to reduce IL-1β content in cell-free supernatant and EV.

CONCLUSIONS

Taken together, these results suggest that pyroptotic pore-forming protein GSDMD plays a key role in the propagation of retinal inflammation, in particular via the release of EV-encapsulated IL-1β. Targeting GSDMD using genetic or pharmacological inhibitors may pose a therapeutic opportunity to dampen inflammatory cascades and delay the progression of retinal degeneration.

Molybdenum and/or cadmium induce NLRP3 inflammasome production by causing mitochondria-associated endoplasmic reticulum membrane dysfunction in sheep hepatocytes

Accumulation of the heavy metals molybdenum (Mo) and cadmium (Cd) in the liver can induce organelle damage and inflammation, resulting in hepatotoxicity. The effect of Mo and/or Cd on sheep hepatocytes was investigated by determining the relationship between the mitochondria-associated endoplasmic reticulum membrane (MAM) and NLRP3 inflammasome. Sheep hepatocytes were divided into four groups: the control group, Mo group (600 μM Mo), Cd group (4 μM Cd) and Mo + Cd group (600 μM Mo+4 μM Cd). The results showed that Mo and/or Cd exposure increased the levels of lactate dehydrogenase (LDH) and nitric oxide (NO) in the cell culture supernatant, elevated the levels of intracellular Ca2+ and mitochondrial Ca2+, downregulated the expression of MAM-related factors (IP3R, GRP75, VDAC1, PERK, ERO1-α, Mfn1, Mfn2, ERP44), shortened the length of the MAM and reduced the formation of the MAM structure, eventually causing MAM dysfunction. Moreover, the expression levels of NLRP3 inflammasome-related factors (NLRP3, Caspase1, IL-1β, IL-6, TNF-α) were also dramatically increased after Mo and Cd exposure, triggering NLRP3 inflammasome production. However, an IP3R inhibitor, 2-APB treatment significantly alleviated these changes. Overall, the data indicate that Mo and Cd coexposure leads to structural disruption and dysfunction of MAM, disrupts cellular Ca2+ homeostasis, and increases NLRP3 inflammasome production in sheep hepatocytes. However, the inhibition of IP3R alleviates NLRP3 inflammasome production induced by Mo and Cd.

Pharmacology of a Potent and Novel Inhibitor of the NOD-Like Receptor Pyrin Domain-Containing Protein 3 (NLRP3) Inflammasome that Attenuates Development of Nonalcoholic Steatohepatitis and Liver Fibrosis

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein complex and component of the innate immune system that is activated by exogenous and endogenous danger signals to promote activation of caspase-1 and the maturation and release of the proinflammatory cytokines interleukin (IL)-1β and IL-18. Inappropriate activation of NLRP3 has been implicated in the pathophysiology of multiple inflammatory and autoimmune diseases, including cardiovascular disease, neurodegenerative diseases, and nonalcoholic steatohepatitis (NASH), thus increasing the clinical interest of this target. We describe in this study the preclinical pharmacologic, pharmacokinetic, and pharmacodynamic properties of a novel and highly specific NLRP3 inhibitor, JT001 (6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine-3-sulfonylurea). In cell-based assays, JT001 potently and selectively inhibited NLRP3 inflammasome assembly, resulting in the inhibition of cytokine release and the prevention of pyroptosis, a form of inflammatory cell death triggered by active caspase-1. Oral administration of JT001 to mice inhibited IL-1β production in peritoneal lavage fluid at plasma concentrations that correlated with mouse in vitro whole blood potency. Orally administered JT001 was effective in reducing hepatic inflammation in three different murine models, including the Nlrp3A350V /+CreT model of Muckle-Wells syndrome (MWS), a diet-induced obesity NASH model, and a choline-deficient diet-induced NASH model. Significant reductions in hepatic fibrosis and cell damage were also observed in the MWS and choline-deficient models. Our findings demonstrate that blockade of NLRP3 attenuates hepatic inflammation and fibrosis and support the use of JT001 to investigate the role of NLRP3 in other inflammatory disease models. SIGNIFICANCE STATEMENT: Persistent inflammasome activation is the consequence of inherited mutations of NLRP3 and results in the development of cryopyrin-associated periodic syndromes associated with severe systemic inflammation. NLRP3 is also upregulated in nonalcoholic steatohepatitis, a metabolic chronic liver disease currently missing a cure. Selective and potent inhibitors of NLRP3 hold great promise and have the potential to overcome an urgent unmet need.

NT-proBNP/urine hepcidin-25 ratio and cardiorenal syndrome type 1 in patients with severe symptomatic aortic stenosis

Background: This study aimed to determine whether novel and conventional cardiorenal biomarkers in patients before transcatheter aortic valve implantation may be associated with cardiorenal syndrome (CRS) type 1. Methods: Serum NT-proBNP and urine biomarkers (hepcidin-25, NGAL, IL-6) were measured before and 24 h after transcatheter aortic valve implantation. Results: 16/95 patients had CRS type 1. Those patients had longer length of stay in hospital (12.5 [9.0-16.0] vs 9.0 [8-12] days; p = 0.025) and were more frequently readmitted to hospital within 6 months after discharge (46.7 vs 15.6%; odds ratio: 4.7; 95% CI: 1.5-15.5; p = 0.007). The NT-proBNP/urine hepcidin-25 ratio (odds ratio: 2.89; 95% CI: 1.30-6.41; p = 0.009) was an independent modifier of CRS type 1. Conclusion: The NT-proBNP/urine hepcidin-25 ratio appears to be a modifier of risk of CRS type 1.

Mechanism Underlying the Action of Berberine in the Treatment of Gouty Arthritis Based on Network Pharmacology

Introduction: Gouty arthritis (GA) is induced by a purine metabolism disorder and monosodium urate (MSU) crystal-related inflammation. Berberine (BBR), extracted from Coptis chinensis, ameliorates MSU-induced GA. However, the mechanisms of BBR against GA remain to be fully elucidated. This study aimed to identify the key targets and pathways mediating the effects of BBR against GA using network pharmacology. Methods: BBR and GA targets were obtained from several databases, and the network of BBR-GA common targets was visualized using Cytoscape software. Protein–protein interaction (PPI), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed using the STRING and Database for Annotation, Visualization, and Integrated Discovery databases, respectively. Animal experiments were performed to determine the outcomes of the BBB intervention. The serum levels of IL-1β, IL-8, and IL-6 were detected using enzyme-linked immunosorbent assay. Results: Thirty-three common targets (including NF-κB, RelA, MAPK1, IL-6, and IL-1β) of BBR and GA were identified, and a network of common targets between BBR and GA was constructed. PPI analysis demonstrated that IL-1β, IL-6, TNF, MAPK, and RelA are key targets with high degree values. GO and KEGG pathway analyses revealed the involvement of inflammation-related biological processes and signaling pathways, such as the NF-κB, MAPK, and TNF signaling pathways. Animal experiments demonstrated that the uric acid, IL-1β, IL-6, and IL-8 serum levels were significantly lower in the BBR group compared with those in hyperuricemic rats. Conclusions: Using systematic network analysis, potential targets mediating the effects of BBR on GA were detected. The pathways and inflammatory factors involved were identified using in vivo experiments, thus providing a reference for further basic research and clinical applications of BBR in the treatment of GA.

Decreased Expression of Soluble Epoxide Hydrolase Suppresses Murine Choroidal Neovascularization

Neovascular or "wet" age-related macular degeneration (nAMD) is a leading cause of blindness among older adults. Choroidal neovascularization (CNV) is a major pathological feature of nAMD, in which abnormal new blood vessel growth from the choroid leads to irreversible vision loss. There is a critical need to develop novel therapeutic strategies to address limitations of the current anti-vascular endothelial growth factor biologics. Previously, we identified soluble epoxide hydrolase (sEH) as a possible therapeutic target for CNV through a forward chemical genetic approach. The purpose of this study was to validate sEH as a target by examining retinal expression of sEH protein and mRNA by immunohistochemistry and RNAscope in situ hybridization, respectively, and to assess the efficacy of an adeno-associated virus (AAV) vector designed to knock down the sEH gene, Ephx2, in the murine laser-induced (L-) CNV model. nAMD patient postmortem eye tissue and murine L-CNV showed overexpression of sEH in photoreceptors and retinal pigment epithelial cells. Ephx2 knockdown significantly reduced CNV and normalized mRNA expression levels of CNV-related inflammatory markers. Thus, this study further establishes sEH as a promising therapeutic target against CNV associated with nAMD.

Inflammasome genetic variants are associated with tuberculosis, HIV-1 infection, and TB/HIV-immune reconstitution inflammatory syndrome outcomes

Background

Tuberculosis (TB) and AIDS are the leading causes of infectious diseases death worldwide. Here, we investigated the relationship between from single nucleotide polymorphisms (SNPs) of the NLRP3, CARD8, AIM2, CASP-1, IFI16, and IL-1β inflammasome genes, as well as the profiles of secreted proinflammatory cytokines (e.g., IL-1β, IL-18, IL-33, and IL-6) with the TB clinical profiles, TB-HIV coinfection, and IRIS onset.

Methods

The individuals were divided into four groups: TB-HIV group (n=88; 11 of them with IRIS), HIV-1 group (n=20), TB group (n=24) and healthy volunteers (HC) group (n=10), and were followed up at INI/FIOCRUZ and HGNI (Rio de Janeiro/Brazil) from 2006 to 2016. Real-time PCR was used to determine the genotypes of the Single Nucleotide Polymorphism (SNPs), and ELISA was used to measure the plasma cytokine levels. Unconditional logistic regression models were used to perform risk estimations.

Results

A higher risk for extrapulmonary TB was associated with the TT genotype (aOR=6.76; P=0.026) in the NLRP3 rs4612666 Single Nucleotide Polymorphism (SNP) and the C-C-T-G-C haplotype (aOR=4.99; P= 0.017) in the NLRP3 variants. This same Single Nucleotide Polymorphism (SNP) was associated with lower risk against extrapulmonary TB when the carrier allele C (aOR=0.15; P=0.021) was present. Among those with HIV-1 infections, a higher risk for TB onset was associated with the GA genotype (aOR=5.5; P=0.044) in the IL1-β rs1143634 Single Nucleotide Polymorphism (SNP). In contrast, lower risk against TB onset was associated with the A-G haplotype (aOR=0.17; P= 0.026) in the CARD8 variants. Higher IL-6 and IL-33 levels were observed in individuals with TB. A higher risk for IRIS onset was associated with CD8 counts ≤ 500 cells/mm3 (aOR=12.32; P=0.010), the presence of extrapulmonary TB (aOR=6.6; P=0.038), and the CT genotype (aOR=61.06; P=0.026) or carrier allele T (aOR=61.06; P=0.026) in the AIM2 rs2276405 Single Nucleotide Polymorphism (SNP), whereas lower risk against IRIS onset was associated with the AT genotype (aOR=0.02; P=0.033) or carrier allele T (aOR=0.02; P=0.029) in the CARD8 rs2043211 Single Nucleotide Polymorphism (SNP) and the T-G haplotype (aOR=0.07; P= 0.033) in the CARD8 variants. No other significant associations were observed.

Conclusions

Our results depict the involvement of genetic polymorphisms of crucial innate immunity genes and proinflammatory cytokines in the clinical outcomes related to TB-HIV coinfection.

Anti-galectin-3 antibodies induce skin vascular inflammation via promoting local production of IL-1β in systemic lupus erythematosus

Vascular inflammation could occur in all organs and tissues in patients with systematic lupus erythematosus (SLE), of which skin is the most frequent one. Our previous research identified anti-galectin-3 (Gal3) antibodies (Abs) as an important mediator of lupus cutaneous vasculopathy. Herein, we showed that anti-Gal3 Abs dysregulated the function of vascular endothelial cells with higher transcript levels of IL-1β and increased expression of mature IL-1β. The enhanced production of IL-1β secreted by endothelial cells was dependent on NLRP3 inflammasome. Intradermal injection of anti-Gal3 Abs in mice induced local inflammation with perivascular infiltration of T cells and neutrophils, which was inhibited by IL-1β blockade. Induction of anti-Gal3 Abs in circulation by immunization of Gal3 antigen not only led to histopathologic changes in the skin, including focal keratinocytes vacuolization and thickening of blood vessels, but also a systemic autoimmune phenotype that involves autoantibody production and kidney damage. Intriguingly, local overexpression of IL-1β was primarily associated with skin lesions but not with other internal organs in mice. Finally, we showed that the serum levels of IL-1β were comparable between SLE patients and healthy donors. Whilst the expression of IL-1β was enriched in local area with perivascular inflammation in lupus skin lesion compared to healthy normal skin. The results strongly suggest that IL-1β plays an important role in mediating anti-Gal3 Ab-induced skin vascular inflammation and raised the prospect for using IL-1β blocking therapies to treat lupus cutaneous damage.

NOD-like receptor protein 3 activation causes spontaneous inflammation and fibrosis that mimics human NASH

BACKGROUND AND AIMS

The NOD-like receptor protein 3 (NLRP3) inflammasome is a central contributor to human acute and chronic liver disease, yet the molecular and cellular mechanisms by which its activation precipitates injury remain incompletely understood. Here, we present single cell transcriptomic profiling of livers from a global transgenic tamoxifen-inducible constitutively activated Nlrp3A350V mutant mouse, and we investigate the changes in parenchymal and nonparenchymal liver cell gene expression that accompany inflammation and fibrosis.

APPROACH AND RESULTS

Our results demonstrate that NLRP3 activation causes chronic extramedullary myelopoiesis marked by myeloid progenitors that differentiate into proinflammatory neutrophils, monocytes, and monocyte-derived macrophages. We observed prominent neutrophil infiltrates with increased Ly6gHI and Ly6gINT cells exhibiting transcriptomic signatures of granulopoiesis typically found in the bone marrow. This was accompanied by a marked increase in Ly6cHI monocytes differentiating into monocyte-derived macrophages that express transcriptional programs similar to macrophages of NASH models. NLRP3 activation also down-regulated metabolic pathways in hepatocytes and shifted hepatic stellate cells toward an activated profibrotic state based on expression of collagen and extracellular matrix regulatory genes.

CONCLUSIONS

These results define the single cell transcriptomes underlying hepatic inflammation and fibrosis precipitated by NLRP3 activation. Clinically, our data support the notion that NLRP3-induced mechanisms should be explored as therapeutic target in NASH-like inflammation.

The transcription factor Cdx2 regulates inflammasome activity through expression of the NLRP3 suppressor TRIM31 to maintain intestinal homeostasis

The intestine-specific transcription factor Cdx2 is essential for intestinal homeostasis and has been implicated in the pathogenesis of disorders including inflammatory bowel disease. However, the mechanism by which Cdx2 influences intestinal disease is not clear. Here, we present evidence supporting a novel Cdx2–TRIM31–NLRP3 (NLR family, pyrin domain containing 3) signaling pathway, which may represent a mechanistic means by which Cdx2 impacts intestinal inflammation. We found that conditional loss of Cdx function resulted in an increase in proinflammatory cytokines, including tumor necrosis factor alpha, interleukin (IL)-1β, and IL-6, in the mouse colon. We further show that TRIM31, which encodes a suppressor of NLRP3 (a central component of the NLRP3 inflammasome complex) is a novel Cdx2 target gene and is attenuated in the colon of Cdx conditional mutants. Consistent with this, we found that attenuation of TRIM31 in Cdx mutant intestine occurs concomitant with elevated levels of NLRP3 and an increase in inflammasome products. We demonstrate that specific inhibition of NLRP3 activity significantly reduced IL-1β and IL-6 levels and extended the life span of Cdx conditional mutants, reflecting the therapeutic potential of targeting NLRP3. Tumor necrosis factor-alpha levels were also induced independent of NLRP3, potentially via elevated activity of the proinflammatory NF-κB signaling pathway in Cdx mutants. Finally, in silico analysis of ulcerative colitis patients revealed attenuation of CDX2 and TRIM31 expression coincident with enhanced expression of proinflammatory cytokines. We conclude that the novel Cdx2–TRIM31–NLRP3 signaling pathway promotes proinflammatory cytokine expression, and its inhibition may have therapeutic potential in human intestinal diseases.

Nlrp3 inflammasome activation in macrophages suffices for inducing autoinflammation in mice

Cryopyrin-associated periodic syndromes (CAPS) are a spectrum of autoinflammatory disorders caused by gain-of-function NLRP3 mutant proteins that form hyperactive inflammasomes leading to overproduction of the pro-inflammatory cytokines IL-1β and IL-18. Expressing the murine gain-of-function Nlrp3^A350V mutant selectively in neutrophils recapitulates several autoinflammatory features of human CAPS, but the potential contribution of macrophage inflammasome hyperactivation to CAPS development is poorly defined. Here, we show that expressing Nlrp3^A350V in macrophages is sufficient for driving severe multi-organ autoinflammation leading to perinatal lethality in mice. In addition, we show that macrophages contribute to autoinflammation also in adult mice, as depleting macrophages in mice ubiquitously expressing Nlrp3^A350V significantly diminishes splenic and hepatic IL-1β production. Interestingly, inflammation induced by macrophage-selective Nlrp3^A350V expression does not provoke an influx of mature neutrophils, while neutrophil influx is still occurring in macrophage-depleted mice with body-wide Nlrp3^A350V expression. These observations identify macrophages as important cellular drivers of CAPS in mice and support a cooperative cellular model of CAPS development in which macrophages and neutrophils act independently of each other in propagating severe autoinflammation.

microRNA-126 inhibits vascular cell adhesion molecule-1 and interleukin-1beta in human dental pulp cells

BACKGROUND

Vascular cell adhesion molecule (VCAM-1) mediates pulpitis via regulating interleukin (IL)-1β. microRNA (miR)-126 was reported to regulate the VCAM-1 under many different pathophysiological circumstances. We investigated variations of miR-126 and VCAM-1 in inflamed patient pulp tissues and determined potential roles of miR-126 in pulpitis using human dental pulp cells (hDPCs) in vitro.

METHODS

We quantitatively measured the transcripts of miR-126 and VCAM-1 in inflamed human pulp tissues using qRT-PCR and compared with those from healthy human pulp tissues. In addition, we transfected miR-126 in hDPCs using plasmid DNA (pDNA)-encoding miR-126 delivered by polyethylenimine (PEI) nanoparticles.

RESULTS

The irreversible pulpitis significantly reduced miR-126 and increased the transcript of VCAM-1 in pulp tissues (p < 0.05). pDNA-encoding miR-126 delivered PEI nanoparticles and effectively upregulated the expression of miR-126 in hDPCs (p < 0.05). The overexpression of miR-126 could effectively suppress the transcripts and protein levels of VCAM-1 and IL-1β induced by Pg-LPS at 100ng/mL in DPCs (p < 0.05).

CONCLUSIONS

miR-126 is involved in pulpitis and downregulated the VCAM-1 and IL-1β in DPCs. miR-126 may be a potential target to attenuate the inflammation of pulpitis.

Harnessing self-assembling peptide nanofibers toprime robust tumor-specific CD8 T cell responses in mice

Induction of tumor-specific CD8 + T cell responses is known as a major challenge for cancer vaccine development; here we presented a strategy to improve peptide nanofibers-mounted antitumor immune responses. To this end, peptide nanofibers bearing class I (Kb)-restricted epitope (Epi-Nano) were formulated with polyethylene imine backbone (Epi-Nano-PEI), and characterized using morphological and physicochemicalcharacterizationtechniques. Nanofibers were studied in terms of their uptake by antigen-presenting cells (APCs), antigen cross-presentation capacity, and cytotoxic activity. Furthermore, nanofibers were assessed by their potency to induce NLRP3 inflammasome-related cytokines and factors. Finally, the ability of nanofibers to induce tumor-specific CD8 T cells and tumor protection were investigated in tumor-bearing mice. The formulation of Epi-Nano with PEI led to the formation of short strand nanofibers with a positive surface charge, a low critical aggregation concentration (CAC), and an increased resistancetoproteolytic degradation. Epi-Nano-PEI was significantly taken up more efficiently by antigen-presenting cells (APCs), and was more potent in cross-presentation when compared to Epi-Nano. Moreover, Epi-Nano-PEI, in comparison to Epi-Nano, efficiently up-regulated the expression of NLRP3, caspase-1, IL-1b, IL18 and IL-6. Cell viability analysis showed that formulation of PEI with Epi-Nano not only abolished its cytotoxic activity, but surprisingly induced macrophage proliferation. Furthermore, it demonstrated that Epi-Nano-PEI triggered robust antigen-specific CD8+ T cell responses, and induced maximum antitumor response (tumor growth inhibition and prolonged survival) in tumor-bearing mice that were significantly higher compared to Epi-Nano. Taken together, the formulation of Epi-Nano with PEI is suggested as a promising strategy to improve nanofibers-mounted antitumor immune response.

Lp-PLA2 inhibition prevents Ang II-induced cardiac inflammation and fibrosis by blocking macrophage NLRP3 inflammasome activation

Macrophage-mediated inflammation plays an important role in hypertensive cardiac remodeling, whereas effective pharmacological treatments targeting cardiac inflammation remain unclear. Lipoprotein-associated phospholipase A2 (Lp-PLA2) contributes to vascular inflammation-related diseases by mediating macrophage migration and activation. Darapladib, the most advanced Lp-PLA2 inhibitor, has been evaluated in phase III trials in atherosclerosis patients. However, the role of darapladib in inhibiting hypertensive cardiac fibrosis remains unknown. Using a murine angiotensin II (Ang II) infusion-induced hypertension model, we found that Pla2g7 (the gene of Lp-PLA2) was the only upregulated PLA2 gene detected in hypertensive cardiac tissue, and it was primarily localized in heart-infiltrating macrophages. As expected, darapladib significantly prevented Ang II-induced cardiac fibrosis, ventricular hypertrophy, and cardiac dysfunction, with potent abatement of macrophage infiltration and inflammatory response. RNA sequencing revealed that darapladib strongly downregulated the expression of genes and signaling pathways related to inflammation, extracellular matrix, and proliferation. Moreover, darapladib substantially reduced the Ang II infusion-induced expression of nucleotide-binding oligomerization domain-like receptor with pyrin domain 3 (NLRP3) and interleukin (IL)-1β and markedly attenuated caspase-1 activation in cardiac tissues. Furthermore, darapladib ameliorated Ang II-stimulated macrophage migration and IL-1β secretion in macrophages by blocking NLRP3 inflammasome activation. Darapladib also effectively blocked macrophage-mediated transformation of fibroblasts into myofibroblasts by inhibiting the activation of the NLRP3 inflammasome in macrophages. Overall, our study identifies a novel anti-inflammatory and anti-cardiac fibrosis role of darapladib in Lp-PLA2 inhibition, elucidating the protective effects of suppressing NLRP3 inflammasome activation. Lp-PLA2 inhibition by darapladib represents a novel therapeutic strategy for hypertensive cardiac damage treatment.

Inflammation, It's Regulation and Antiphlogistic Effect of the Cyanogenic Glycoside Amygdalin

The inflammatory reaction accompanies in part or in full any disease process in the vascularized metazoan. This complicated reaction is controlled by regulatory mechanisms, some of which produce unpleasant symptomatic manifestations of inflammation. Therefore, there has been an effort to develop selective drugs aimed at removing pain, fever, or swelling. Gradually, however, serious adverse side effects of such inhibitors became apparent. Scientific research has therefore continued to explore new possibilities, including naturally available substances. Amygdalin is a cyanogenic glycoside present, e.g., in bitter almonds. This glycoside has already sparked many discussions among scientists, especially about its anticancer potential and related toxic cyanides. However, toxicity at different doses made it generally unacceptable. Although amygdalin given at the correct oral dose may not lead to poisoning, it has not yet been accurately quantified, as its action is often affected by different intestinal microbial consortia. Its pharmacological activities have been studied, but its effects on the body's inflammatory response are lacking. This review discusses the chemical structure, toxicity, and current knowledge of the molecular mechanism of amygdalin activity on immune functions, including the anti-inflammatory effect, but also discusses inflammation as such, its mediators with diverse functions, which are usually targeted by drugs.

Effect of Cannabidiol (CBD) on Canine Inflammatory Response: An Ex Vivo Study on LPS Stimulated Whole Blood

The use of cannabidiol (CBD) for animal species is an area of growing interest, for example for its anti-inflammatory and immuno-modulating properties, even though all of its biological effects are still not fully understood, especially in veterinary medicine. Therefore, the aim of this study was to investigate the anti-inflammatory and immuno-modulating properties of CBD for the first time directly in canine inflammatory response. We used an ex vivo model of LPS-stimulated whole dog blood. We stimulated the whole blood from healthy dogs with LPS 100 ng/mL for 24 h in the presence or not of CBD 50 and 100 μg/mL. We observed a reduction in IL-6 and TNF-α production from the group treated with CBD, but non-altered IL-10 levels. Moreover, we also observed from the CBD-treated group a reduction in Nf-κB and COX-2 expression. In conclusion, we demonstrated for the first time the anti-inflammatory and immuno-modulating properties of CBD directly in dogs' immune cells, using a canine ex vivo inflammatory model. The results obtained from these studies encourage further studies to better understand the possible therapeutic role of CBD in veterinary medicine.

Gut Microbiota and Development of Vibrio cholerae-Specific Long-Term Memory B Cells in Adults after Whole-Cell Killed Oral Cholera Vaccine

Cholera is a diarrheal disease caused by Vibrio cholerae that continues to be a major public health concern in populations without access to safe water. IgG- and IgA-secreting memory B cells (MBC) targeting the V. cholerae O-specific polysaccharide (OSP) correlate with protection from infection in persons exposed to V. cholerae and may be a major determinant of long-term protection against cholera. Shanchol, a widely used oral cholera vaccine (OCV), stimulates OSP MBC responses in only some people after vaccination, and the gut microbiota is a possible determinant of variable immune responses observed after OCV. Using 16S rRNA sequencing of feces from the time of vaccination, we compared the gut microbiota among adults with and without MBC responses to OCV. Gut microbial diversity measures were not associated with MBC isotype or OSP-specific responses, but individuals with a higher abundance of Clostridiales and lower abundance of Enterobacterales were more likely to develop an MBC response. We applied protein-normalized fecal supernatants of high and low MBC responders to THP-1-derived human macrophages to investigate the effect of microbial factors at the time of vaccination. Feces from individuals with higher MBC responses induced significantly different IL-1β and IL-6 levels than individuals with lower responses, indicating that the gut microbiota at the time of vaccination may "prime" the mucosal immune response to vaccine antigens. Our results suggest the gut microbiota could impact immune responses to OCVs, and further study of microbial metabolites as potential vaccine adjuvants is warranted.

Inflammasome can Affect Adult Neurogenesis: A Review Article

Adult neurogenesis is the process of producing new neurons in the adult brain and is limited to two major areas: the hippocampal dentate gyrus and the Subventricular Zone (SVZ). Adult neurogenesis is affected by some physiological, pharmacological, and pathological factors. The inflammasome is a major signalling platform that regulates caspase-1 and induces proinflammatory cytokines production such as interleukin-1β (IL1-β) and IL-18.

Inflammasomes may be stimulated through multiple signals, and some of these signaling factors can affect neurogenesis. In the current review, “adult neurogenesis and inflammasome” were searched in PubMed, Scopus, and Google Scholar. Reviewing various research works showed correlations between inflammasome and neurogenesis by different intermediate factors, such as interferons (IFN), interleukins (IL), α-synuclein, microRNAs, and natural compounds. Concerning the significant role of neurogenesis in the health of the nervous system and memory, understanding factors inducing neurogenesis is crucial for identifying new therapeutic aims. Hence in this review, we will discuss the different mechanisms by which inflammasome influences adult neurogenesis.

Formulated Chinese medicine Shaoyao Gancao Tang reduces NLRP1 and NLRP3 in Alzheimer's disease cell and mouse models for neuroprotection and cognitive improvement

Amyloid β (Aβ) plays a major role in the neurodegeneration of Alzheimer’s disease (AD). The accumulation of misfolded Aβ causes oxidative stress and inflammatory damage leading to apoptotic cell death. Traditional Chinese herbal medicine (CHM) has been widely used in treating neurodegenerative diseases by reducing oxidative stress and neuroinflammation. We examined the neuroprotective effect of formulated CHM Shaoyao Gancao Tang (SG-Tang, made of Paeonia lactiflora and Glycyrrhiza uralensis at 1:1 ratio) in AD cell and mouse models. In Aβ-GFP SH-SY5Y cells, SG-Tang reduced Aβ aggregation and reactive oxygen species (ROS) production, as well as improved neurite outgrowth. When the Aβ-GFP-expressing cells were stimulated with conditioned medium from interferon (IFN)-γ-activated HMC3 microglia, SG-Tang suppressed expressions of inducible nitric oxide synthase (iNOS), NLR family pyrin domain containing 1 (NLRP1) and 3 (NLRP3), tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, attenuated caspase-1 activity and ROS production, and promoted neurite outgrowth. In streptozocin-induced hyperglycemic APP/PS1/Tau triple transgenic (3×Tg-AD) mice, SG-Tang also reduced expressions of NLRP1, NLRP3, Aβ and Tau in hippocampus and cortex, as well as improved working and spatial memories in Y maze and Morris water maze. Collectively, our results demonstrate the potential of SG-Tang in treating AD by moderating neuroinflammation.

Non-canonical Caspase-1 Signaling Drives RIP2-Dependent and TNF-α-Mediated Inflammation In Vivo

Pro-inflammatory caspase-1 is a key player in innate immunity. Caspase-1 processes interleukin (IL)-1β and IL-18 to their mature forms and triggers pyroptosis. These caspase-1 functions are linked to its enzymatic activity. However, loss-of-function missense mutations in CASP1 do not prevent autoinflammation in patients, despite decreased IL-1β production. In vitro data suggest that enzymatically inactive caspase-1 drives inflammation via enhanced nuclear factor κB (NF-κB) activation, independent of IL-1β processing. Here, we report two mouse models of enzymatically inactive caspase-1-C284A, demonstrating the relevance of this pathway in vivo. In contrast to Casp1^-/- mice, caspase-1-C284A mice show pronounced hypothermia and increased levels of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and IL-6 when challenged with lipopolysaccharide (LPS). Caspase-1-C284A signaling is RIP2 dependent and mediated by TNF-α but independent of the NLRP3 inflammasome. LPS-stimulated whole blood from patients carrying loss-of-function missense mutations in CASP1 secretes higher amounts of TNF-α. Taken together, these results reveal non-canonical caspase-1 signaling in vivo.

Fucoxanthin from microalgae Phaeodactylum tricornutum inhibits pro-inflammatory cytokines by regulating both NF-κB and NLRP3 inflammasome activation

Pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α are mediated by the activation of various kinds of signaling pathways in the innate immune system. Particularly, NF-κB and NLRP3 inflammasome signaling are involved in the production and secretion of these cytokines. Each signaling is participated in the two steps necessary for IL-1β, a representative pro-inflammatory cytokine, to be processed into a form secreted by cells. In the priming step stimulated by LPS, pro-IL-1β is synthesized through NF-κB activation. Pro-IL-1β cleavages into mature IL-1β by formed NLRP3 inflammasome in the activation step induced by ATP. The mature form of IL-1β is subsequently secreted out of the cell, causing inflammation. Moreover, IL-6 and TNF-α are known to increase in NLRP3 inflammasome-mediated conditions. Here, we found that fucoxanthin, one of the major components of Phaeodactylum tricornutum, has an inhibitory effect on NF-κB and NLRP3 inflammasome activation induced by the combination of LPS and ATP in bone marrow-derived immune cells as well as astrocytes. Fucoxanthin, which is abundant in the EtOH fraction of Phaeodactylum tricornutum extracts, has shown to have less cell toxicity and found to decrease the production of major pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α. Fucoxanthin has also shown to suppress the expression of cleaved caspase-1 and the oligomerization of ASC, which are the main components of the NLRP3 inflammasome. Furthermore, phosphorylated IκBα and pro-IL-1β expression decreased in the presence of fucoxanthin, suggesting that fucoxanthin can negatively regulate the priming step of inflammasome signaling. Thus, our results provide reliable evidence that fucoxanthin may serve as a key candidate in the development of potential therapeutic agents for inflammatory diseases as well as neurodegenerative diseases caused by NF-κB and NLRP3 inflammasome activation.

The Immune System Fails to Mount a Protective Response to Gram-Positive or Gram-Negative Bacterial Prostatitis

Bacterial prostatitis affects 1% of men, with increased incidence in the elderly. Acute bacterial prostatitis frequently progresses to chronicity, marked by recurrent episodes interspersed with asymptomatic periods of variable duration. Antibiotic treatment is standard of care; however, dissemination of antimicrobially resistant uropathogens threatens therapy efficacy. Thus, development of nonantibiotic-based approaches to treat chronic disease is a priority. Currently, why chronic prostatitis arises is unclear, as the immune response to prostate infection is incompletely understood. As 80% of prostatitis cases are caused by Gram-negative uropathogenic Escherichia coli (UPEC) or Gram-positive Enterococcus faecalis, we used a mouse transurethral instillation model to address the hypothesis that an innate immune response fails to develop following prostate infection with these uropathogens, leading to chronic disease. Surprisingly, infection induced robust proinflammatory cytokine expression and myeloid cell infiltration. Following a second infection, cytokine responses and innate cell infiltration were largely comparable to primary infection. Characteristic of memory responses, more lymphoid cells infiltrated the prostate in a second infection compared with a first, suggesting that adaptive immunity develops to eliminate the pathogens. Unexpectedly, bacterial burden in prostates challenged with either UPEC or E. faecalis was equal or greater than primary infection despite that a protective adaptive response to UPEC infection was evident in the bladder of the same animals. Our findings support that chronic or recurrent prostatitis develops despite strong innate immune responses and may be the result of a failure to develop immune memory to infection, pointing to actionable targets for immunotherapy.

The Inhibition of NLRP3 Inflammasome and IL-6 Production by Hibiscus noldeae Baker f. Derived Constituents Provides a Link to Its Anti-Inflammatory Therapeutic Potentials

The activation of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome and/or its components is associated with the physio-pathogenesis of many respiratory diseases including asthma, COPD (chronic obstructive pulmonary disease), SARS Cov-2 (severe acute respiratory syndrome coronavirus 2), and in several autoimmune diseases. Hibiscus noldeae Baker f. has been widely reported to be traditionally used in the treatment of different ailments, some of which are of inflammatory background such as asthma, wounds, headache, etc. However, the claims have not been supported by evidence at the molecular and functional levels. Here, we report on the bio-guided fractionation of H. noldeae and assessment of the inhibitory properties of some fractions and purified compounds on NLRP3 inflammasome and Interleukin 6 (IL-6). The activation of the NLRP3 inflammasome was determined by detecting the activity of caspase-1 and the production of Interleukin 1β (IL-1β) in Lipopolysaccharide (LPS) and ATP-stimulated Tamm-Horsfall Protein 1 (THP-1) macrophages, while the production of IL-6 was studied in LPS-stimulated RAW264.7 mouse macrophages. It was observed that hexane and ethyl acetate fractions of the crude extract of the aerial parts of H. noldeae, as well as caffeic acid, isoquercetin, and ER2.4 and ER2.7 fractions revealed significant inhibitory effects on Caspase-1 activities, and on IL-1β and IL-6 production. The ER2.4 and ER2.7 fractions downregulated the production of IL-1β and IL-6, in a similar range as the caspase-1 inhibitor AC-YVAD-CHO and the drug Dexamethasone, both used as controls, respectively. Overall, our work does provide the very first scientific based evidence for Hibiscus noldeae anti-inflammatory effects and widespread use by traditional healers in Rwanda for a variety of ailments.

The Association of Circulatory Cytokines (IL-6 and IL-10) Level with Spontaneous Abortion-a Preliminary Observation

Successful pregnancy or its outcome depends upon various endogenous and exogenous determinants including immune status, and cytokines are one of the regulators which might play a vital role in the maintenance of pregnancy. The study was carried out to determine the role of cytokines, i.e., interleukin-6 (IL-6) and interleukin-10 (IL-10), in spontaneous abortion (SAb) cases with reference to control (women without SAb). One hundred twenty-six subjects (63 women with SAb cases and 63 control women without SAb and bearing at least one child) were enrolled. Out of the 63 SAb cases, 31 women from Outpatient Department (with history of SAb cases, i.e., one, two, or more) and 32 from the Gynecology ward (current SAb cases) were enrolled. The cytokines (IL-6 and IL-10) were measured by ELISA method using commercially available kit. The mean IL-6 level was higher among women with SAb cases, recent SAb and recurrent SAb cases versus controls, history of SAb and less than 2 SAb cases respectively, while an inverse pattern of variations was observed for IL-10 level. The Spearman's correlation revealed that the IL-6 was positively correlated while IL-10 was negatively correlated with number of incidences of SAbs. The data of women with recent SAb and childbirth were categorized into four IL quartiles and found that the highest % of control and lowest % of SAb subjects were in second quartile of IL-6 while highest % of control and lowest % of SAb subjects were in the fourth (high) quartile of IL-10 level group. A multiple regression model showed that with elevation in IL-6, there was an elevation in number of SAb cases and an inverse relationship was observed with regard to IL-10. The results indicate positive role of IL-10 and undesirable role of IL-6 on pregnancy outcomes. Further, quartiles' distribution suggests that high levels of IL-10 might be necessary for the effective pregnancy outcome, but more data are needed to substantiate the present findings.

ASK1 inhibition reduces cell death and hepatic fibrosis in an Nlrp3 mutant liver injury model

Hepatic inflammasome activation is considered a major contributor to liver fibrosis in NASH. Apoptosis signal-regulating kinase 1 (ASK1) is an apical mitogen-activated protein kinase that activates hepatic JNK and p38 to promote apoptosis, inflammation, and fibrosis. The aim of the current study was to investigate whether pharmacologic inhibition of ASK1 could attenuate hepatic fibrosis driven by inflammasome activation using gain-of-function NOD-like receptor protein 3 (Nlrp3) mutant mice. Tamoxifen-inducible Nlrp3 knock-in (Nlrp3A350V/+CreT-KI) mice and WT mice were administered either control chow diet or diet containing the selective ASK1 inhibitor GS-444217 for 6 weeks. Livers of Nlrp3-KI mice had increased inflammation, cell death, and fibrosis and increased phosphorylation of ASK1, p38, and c-Jun. GS-444217 reduced ASK1 pathway activation, liver cell death, and liver fibrosis. ASK1 inhibition resulted in a significant downregulation of genes involved in collagen production and extracellular matrix deposition, as well as in a reduced hepatic TNF-α expression. ASK1 inhibition also directly reduced LPS-induced gene expression of Collagen 1A1 (Col1a1) in hepatic stellate cells isolated from Nlrp3-KI mice. In conclusion, ASK1 inhibition reduced liver cell death and fibrosis downstream of inflammatory signaling induced by NLRP3. These data provide mechanistic insight into the antifibrotic mechanisms of ASK1 inhibition.

Persistent Systemic Microbial Translocation, Inflammation, and Intestinal Damage During Clostridioides difficile Infection

BACKGROUND

Clostridioides difficile infection (CDI) might be complicated by the development of nosocomial bloodstream infection (n-BSI). Based on the hypothesis that alteration of the normal gut integrity is present during CDI, we evaluated markers of microbial translocation, inflammation, and intestinal damage in patients with CDI.

METHODS

Patients with documented CDI were enrolled in the study. For each subject, plasma samples were collected at T0 and T1 (before and after CDI therapy, respectively), and the following markers were evaluated: lipopolysaccharide-binding protein (LPB), EndoCab IgM, interleukin-6, intestinal fatty acid binding protein (I-FABP). Samples from nonhospitalized healthy controls were also included. The study population was divided into BSI+/BSI- and fecal microbiota transplantation (FMT) +/FMT- groups, according to the development of n-BSI and the receipt of FMT, respectively.

RESULTS

Overall, 45 subjects were included; 8 (17.7%) developed primary n-BSI. Markers of microbial translocation and intestinal damage significantly decreased between T0 and T1, however, without reaching values similar to controls (P < .0001). Compared with BSI-, a persistent high level of microbial translocation in the BSI+ group was observed. In the FMT+ group, markers of microbial translocation and inflammation at T1 tended to reach control values.

CONCLUSIONS

CDI is associated with high levels of microbial translocation, inflammation, and intestinal damage, which are still present at clinical resolution of CDI. The role of residual mucosal perturbation and persistence of intestinal cell damage in the development of n-BSI following CDI, as well as the possible effect of FMT in the restoration of mucosal integrity, should be further investigated.

Inhibition of Pro-Inflammatory Cytokine Secretion by Select Antioxidants in Human Coronary Artery Endothelial Cells

Abstract. Inflammatory and oxidative stress in endothelial cells are implicated in the pathogenesis of premature atherosclerosis in diabetes. To determine whether high-dextrose concentrations induce the expression of pro-inflammatory cytokines, human coronary artery endothelial cells (HCAEC) were exposed to either 5.5 or 27.5 mM dextrose for 24-hours and interleukin-1β (IL-1β), interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor α (TNF α) levels were measured by enzyme immunoassays. To determine the effect of antioxidants on inflammatory cytokine secretion, cells were also treated with α-tocopherol, ascorbic acid, and the glutathione peroxidase mimetic ebselen. Only the concentration of IL-1β in culture media from cells exposed to 27.5 mM dextrose increased relative to cells maintained in 5.5 mM dextrose. Treatment with α-tocopherol (10, 100, and 1,000 μM) and ascorbic acid (15, 150, and 1,500 μM) at the same time that the dextrose was added reduced IL-1β, IL-6, and IL-8 levels in culture media from cells maintained at 5.5 mM dextrose but had no effect on IL-1β, IL-6, and IL-8 levels in cells exposed to 27.5 mM dextrose. However, ebselen treatment reduced IL-1β, IL-6, and IL-8 levels in cells maintained in either 5.5 or 27.5 mM dextrose. IL-2 and TNF α concentrations in culture media were below the limit of detection under all experimental conditions studied suggesting that these cells may not synthesize detectable quantities of these cytokines. These results suggest that dextrose at certain concentrations may increase IL-1β levels and that antioxidants have differential effects on suppressing the secretion of pro-inflammatory cytokines in HCAEC.

Evidence for a dynorphin-mediated inner ear immune/inflammatory response and glutamate-induced neural excitotoxicity: an updated analysis

Acoustic overstimulation (AOS) is defined as the stressful overexposure to high-intensity sounds. AOS is a precipitating factor that leads to a glutamate (GLU)-induced Type I auditory neural excitotoxicity and an activation of an immune/inflammatory/oxidative stress response within the inner ear, often resulting in cochlear hearing loss. The dendrites of the Type I auditory neural neurons that innervate the inner hair cells (IHCs), and respond to the IHC release of the excitatory neurotransmitter GLU, are themselves directly innervated by the dynorphin (DYN)-bearing axon terminals of the descending brain stem lateral olivocochlear (LOC) system. DYNs are known to increase GLU availability, potentiate GLU excitotoxicity, and induce superoxide production. DYNs also increase the production of proinflammatory cytokines by modulating immune/inflammatory signal transduction pathways. Evidence is provided supporting the possibility that the GLU-mediated Type I auditory neural dendritic swelling, inflammation, excitotoxicity, and cochlear hearing loss that follow AOS may be part of a brain stem-activated, DYN-mediated cascade of inflammatory events subsequent to a LOC release of DYNs into the cochlea. In support of a DYN-mediated cascade of events are established investigations linking DYNs to the immune/inflammatory/excitotoxic response in other neural systems.

MCC950/CRID3 potently targets the NACHT domain of wild-type NLRP3 but not disease-associated mutants for inflammasome inhibition

The nucleotide-binding-domain (NBD)–and leucine-rich repeat (LRR)–containing (NLR) family, pyrin-domain–containing 3 (NLRP3) inflammasome drives pathological inflammation in a suite of autoimmune, metabolic, malignant, and neurodegenerative diseases. Additionally, NLRP3 gain-of-function point mutations cause systemic periodic fever syndromes that are collectively known as cryopyrin-associated periodic syndrome (CAPS). There is significant interest in the discovery and development of diarylsulfonylurea Cytokine Release Inhibitory Drugs (CRIDs) such as MCC950/CRID3, a potent and selective inhibitor of the NLRP3 inflammasome pathway, for the treatment of CAPS and other diseases. However, drug discovery efforts have been constrained by the lack of insight into the molecular target and mechanism by which these CRIDs inhibit the NLRP3 inflammasome pathway. Here, we show that the NAIP, CIITA, HET-E, and TP1 (NACHT) domain of NLRP3 is the molecular target of diarylsulfonylurea inhibitors. Interestingly, we find photoaffinity labeling (PAL) of the NACHT domain requires an intact (d)ATP-binding pocket and is substantially reduced for most CAPS-associated NLRP3 mutants. In concordance with this finding, MCC950/CRID3 failed to inhibit NLRP3-driven inflammatory pathology in two mouse models of CAPS. Moreover, it abolished circulating levels of interleukin (IL)-1β and IL-18 in lipopolysaccharide (LPS)-challenged wild-type mice but not in Nlrp3^L351P knock-in mice and ex vivo-stimulated mutant macrophages. These results identify wild-type NLRP3 as the molecular target of MCC950/CRID3 and show that CAPS-related NLRP3 mutants escape efficient MCC950/CRID3 inhibition. Collectively, this work suggests that MCC950/CRID3-based therapies may effectively treat inflammation driven by wild-type NLRP3 but not CAPS-associated mutants.

The diarylsulfonylurea-based Cytokine Release Inhibitory Drugs (CRIDs) potently and selectively inhibit the NLRP3 inflammasome pathway, but their molecular target is unknown. This study identifies the NACHT domain of NLRP3 itself as the molecular target of the CRID MCC950/CRID3 and evaluates the functional impact of disease mutations on inflammasome blockade.

Posttranslational Regulation of IL-23 Production Distinguishes the Innate Immune Responses to Live Toxigenic versus Heat-Inactivated Vibrio cholerae

Vibrio cholerae infection provides long-lasting protective immunity, while oral, inactivated cholera vaccines (OCV) result in more-limited protection. To identify characteristics of the innate immune response that may distinguish natural V. cholerae infection from OCV, we stimulated differentiated, macrophage-like THP-1 cells with live versus heat-inactivated V. cholerae with and without endogenous or exogenous cholera holotoxin (CT). Interleukin 23A gene (IL23A) expression was higher in cells exposed to live V. cholerae than in cells exposed to inactivated organisms (mean change, 38-fold; 95% confidence interval [95% CI], 4.0 to 42; P < 0.01). IL-23 secretion was also higher in cells exposed to live V. cholerae than in cells exposed to inactivated V. cholerae (mean change, 5.6-fold; 95% CI, 4.4 to 11; P < 0.001). This increase in IL-23 secretion was more marked than for other key innate immune cytokines (e.g., IL-1β and IL-6) and dependent on exposure to the combination of both live V. cholerae and CT. While IL-23 secretion was reduced following stimulation with either heat-inactivated wild-type V. cholerae or a live isogenic ctxAB mutant of V. cholerae, the addition of exogenous CT restored IL-23 secretion in combination with the live isogenic ctxAB mutant V. cholerae, but not when it was paired with stimulation by heat-inactivated V. cholerae The posttranslational regulation of IL-23 under these conditions was dependent on the activity of the cysteine protease cathepsin B. In humans, IL-23 promotes the differentiation of Th17 cells to T follicular helper cells, which maintain and support long-term memory B cell generation after infection. Based on these findings, the stimulation of IL-23 production may be a determinant of protective immunity following V. cholerae infection.IMPORTANCE An episode of cholera provides better protection against reinfection than oral cholera vaccines, and the reasons for this are still under study. To better understand this, we compared the immune responses of human cells exposed to live Vibrio cholerae with those of cells exposed to heat-killed V. cholerae (similar to the contents of oral cholera vaccines). We also compared the effects of active cholera toxin and the inactive cholera toxin B subunit (which is included in some cholera vaccines). One key immune signaling molecule, IL-23, was uniquely produced in response to the combination of live bacteria and active cholera holotoxin. Stimulation with V. cholerae that did not produce the active toxin or was killed did not produce an IL-23 response. The stimulation of IL-23 production by cholera toxin-producing V. cholerae may be important in conferring long-term immunity after cholera.

High-Density Lipoproteins Decrease Proinflammatory Activity and Modulate the Innate Immune Response

Atherosclerosis, a chronic inflammatory disease of the arterial wall, is the leading cause of cardiac disorders and stroke. The onset and progression of these diseases are linked with the inflammatory response, especially NLRP3 inflammasome activation, inducing the production of proinflammatory cytokines, such as interleukin 1β (IL-1β). Because high-density lipoproteins (HDLs) have shown significant antiatherogenic and anti-inflammatory properties, we evaluated their immunomodulatory activity in response to cholesterol crystals and other innate immune activators. Human primary monocyte-derived macrophages, THP-1 cells, and murine macrophages were stimulated to activate NLRP3 inflammasome and other pattern recognition receptors, in the presence or absence of HDL. Then, HDL immunomodulatory effects were evaluated through IL-1β and IL-6 production by enzyme-linked immunosorbent assay. Furthermore, in vivo HDL anti-inflammatory effects were evaluated in a murine model of peritoneal inflammatory infiltration. HDLs have an immunomodulatory effect on different cellular models, including peripheral blood mononuclear cells, THP-1 cells, and murine macrophages, by affecting the activity of innate immunity sensors, such as Toll-like receptors (TLRs), dectin-1, and inflammasomes. HDL reduces the proinflammatory role of cholesterol crystals, nigericin, and other NLRP3 and AIM2 inflammasome agonists, and several TLR agonists, leading to a decreased production of IL-1β and IL-6. The results suggest that HDLs are highly important in the regulation of the innate immune response and may have a beneficial role in controlling diseases associated with the inflammatory response.

IL-1 Family Members Mediate Cell Death, Inflammation and Angiogenesis in Retinal Degenerative Diseases

Inflammation underpins and contributes to the pathogenesis of many retinal degenerative diseases. The recruitment and activation of both resident microglia and recruited macrophages, as well as the production of cytokines, are key contributing factors for progressive cell death in these diseases. In particular, the interleukin 1 (IL-1) family consisting of both pro- and anti-inflammatory cytokines has been shown to be pivotal in the mediation of innate immunity and contribute directly to a number of retinal degenerations, including Age-Related Macular Degeneration (AMD), diabetic retinopathy, retinitis pigmentosa, glaucoma, and retinopathy of prematurity (ROP). In this review, we will discuss the role of IL-1 family members and inflammasome signaling in retinal degenerative diseases, piecing together their contribution to retinal disease pathology, and identifying areas of research expansion required to further elucidate their function in the retina.

Parkin Impairs Antiviral Immunity by Suppressing the Mitochondrial Reactive Oxygen Species-Nlrp3 Axis and Antiviral Inflammation

Although mitochondria are known to be involved in host defense against viral infection, the physiological role of mitophagy, a crucial mechanism for maintaining mitochondrial homeostasis, in antiviral immunity remains poorly defined. Here, we show that Parkin, a central player in mitophagy, has a vital function in regulating host antiviral responses. Parkin-knockout mice exhibit improved viral clearance and survival after viral infection. However, Parkin deficiency does not affect antiviral signaling and interferon production. Instead, Parkin deficiency augments innate antiviral inflammation by enhancing mitochondrial ROS (mtROS)-mediated NLRP3 inflammasome activation and promoting viral clearance. Loss of NLRP3 can reverse the enhanced antiviral responses in Parkin knockout mice. Furthermore, we find that Parkin expression is downregulated in peripheral blood mononuclear cells of patients infected with virus. Collectively, our results suggest that Parkin plays an important role in antiviral immunity by controlling mtROS-NLRP3 axis-mediated inflammation. These findings provide physiological insight of the importance of mitophagy in regulating host antiviral response.

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Loss of Parkin enhances viral clearance but does not affect type I IFN production

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Parkin deletion promotes antiviral inflammation in vivo

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Parkin deficiency enhances antiviral inflammation via the mtROS-NLRP3 axis

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The expression of Parkin is downregulated following viral infection

Human metapneumovirus activates NOD-like receptor protein 3 inflammasome via its small hydrophobic protein which plays a detrimental role during infection in mice

NOD-like receptor protein 3 (NLRP3) inflammasome activation triggers caspase-1 activation-induced maturation of interleukin (IL)-1β and IL-18 and therefore is important for the development of the host defense against various RNA viral diseases. However, the implication of this protein complex in human metapneumovirus (HMPV) disease has not been fully studied. Herein, we report that NLRP3 inflammasome plays a detrimental role during HMPV infection because NLRP3 inflammasome inhibition protected mice from mortality and reduced weight loss and inflammation without impacting viral replication. We also demonstrate that NLRP3 inflammasome exerts its deleterious effect via IL-1β production since we observed reduced mortality, weight loss and inflammation in IL-1β-deficient (IL-1β^-/-) mice, as compared to wild-type animals during HMPV infection. Moreover, the effect on these evaluated parameters was not different in IL-1β^-/- and wild-type mice treated with an NLRP3 inflammasome inhibitor. The production of IL-1β was also abrogated in bone marrow derived macrophages deficient for NLRP3. Finally, we show that small hydrophobic protein-deleted recombinant HMPV (HMPV ΔSH) failed to activate caspase-1, which is responsible for IL-1β cleavage and maturation. Furthermore, HMPV ΔSH-infected mice had less weight loss, showed no mortality and reduced inflammation, as compared to wild-type HMPV-infected mice. Thus, NLRP3 inflammasome activation seems to be triggered by HMPV SH protein in HMPV disease. In summary, once activated by the HMPV SH protein, NLRP3 inflammasome promotes the maturation of IL-1β, which exacerbates HMPV-induced inflammation. Therefore, the blockade of IL-1β production by using NLRP3 inflammasome inhibitors might be a novel potential strategy for the therapy and prevention of HMPV infection.

Human metapneumovirus (HMPV), a negative-stranded, enveloped RNA virus, is recognized as one of the leading causes of acute respiratory disease in children since its discovery in 2001. Nevertheless, there is currently no licensed vaccine for the prevention of HMPV infection and treatment modalities are limited to the use of ribavirin, a weak antiviral agent or immunoglobulins. NOD-like receptor protein 3 (NLRP3) inflammasome has been shown to be involved in the pathogenesis of several RNA viral diseases but its role during HMPV infection has not been fully studied. Here, we report for the first time that NLRP3 inflammasome is activated by the small hydrophobic protein of HMPV, leading to the release of IL-1β, which has the potential to exacerbate inflammation. However, NLRP3 inflammasome has no direct influence on viral replication. Thus, IL-1β-mediated inflammatory process plays an important role during HMPV infection and, therefore, anti-IL-1β strategies such as the use of NLRP3 inhibitors may be a novel potential approach for the prevention and therapy of HMPV disease.

CAPS and NLRP3

Cryopyrin-associated periodic syndrome (CAPS) is a rare inherited autoinflammatory disorder characterized by systemic, cutaneous, musculoskeletal, and central nervous system inflammation. Gain-of-function mutations in NLRP3 in CAPS patients lead to activation of the cryopyrin inflammasome, resulting in the inappropriate release of inflammatory cytokines including IL-1β and CAPS-related inflammatory symptoms. Several mechanisms have been identified that are important for the normal regulation of the cryopyrin inflammasome in order to prevent uncontrolled inflammation. Investigators have taken advantage of some of these pathways to develop and apply novel targeted therapies, which have resulted in improved quality of life for patients with this orphan disease.

Physicochemical Properties Can Be Key Determinants of Mesoporous Silica Nanoparticle Potency in Vitro

Nanoforms of mesoporous silica (mSiNPs) are increasingly applied in medicine, imaging, energy storage, catalysis, biosensors, and bioremediation. The impact of their physicochemical properties on health and the environment remain to be elucidated. In this work, newly synthesized mesoporous silica (sizes: 25, 70, 100, 170, and 600 nm; surface functionalization: pristine, C3-, and C11-COOH moieties) were assessed for cytotoxicity and induction of inflammatory responses in vitro (A549, THP-1, J774A.1 cells). All toxicity end points were integrated to obtain simple descriptors of biological potencies of these mSiNPs. The findings indicate that mSiNPs are less bioactive than the nonporous reference SiNP used in this study. The C3-COOH-modified mSiNPs were generally less cytotoxic than their pristine and C11-modified counterparts in the nanorange (≤100 nm). Carboxyl-modified mSiNPs affected inflammatory marker release across all sizes with cell-type specificity, suggesting a potential for immunomodulatory effects. Surface area, size, extent of agglomeration, ζ-potential, and surface modification appeared to be important determinants of cytotoxicity of mSiNPs based on association tests. Pathway analysis identified particle and cell-type-specific alteration of cellular pathways and functions by mSiNPs. The integration of exposure-related biological responses of multiple cell lines to mSiNPs allowed for a comprehensive evaluation of the impact of physicochemical factors on their toxicity characteristics. The integrated multilevel toxicity assessment approach can be valuable as a hazard screening tool for safety evaluations of emerging nanomaterials for regulatory purpose.

Novel elucidation and treatment of pancreatic chronic graft-versus-host disease in mice

Chronic graft-versus-host disease (cGVHD) is a severe complication of allogeneic haematopoietic stem cell transplantation. There is a growing understanding of cGVHD, and several effective therapies for cGVHD have been reported. However, pancreatic cGVHD is a potentially untapped study field. Our thought-provoking study using a mouse model of cGVHD suggested that the pancreas could be impaired by cGVHD-induced inflammation and fibrosis and that endoplasmic reticulum (ER) stress was augmented in the pancreas affected by cGVHD. These findings urged us to treat pancreatic cGVHD through reduction of ER stress, and we used 4-phenylbutyric acid (PBA) as an ER stress reducer. A series of experiments has indicated that PBA can suppress cGVHD-elicited ER stress in the pancreas and accordingly alleviate pancreatic cGVHD. Furthermore, we focused on a correlation between epithelial to mesenchymal transition (EMT) and fibrosis in the cGVHD-affected pancreas, because EMT was conceivably implicated in various fibrosis-associated diseases. Our investigation has suggested that the expression of EMT markers was increased in the cGVHD-disordered pancreas and that it could be reduced by PBA. Taken together, we have provided a clue to elucidate the pathogenic process of pancreatic cGVHD and created a potentially effective treatment of this disease using the ER stress alleviator PBA.

Apoptosis Signal-regulating Kinase 1 Silencing on Astroglial Inflammasomes in an Experimental Model of Ischemic Stroke

Activation of the inflammasome complex contributes to the inflammatory response and cell death under pathologic conditions. The nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 2 (NLRP2) inflammasome is activated in astrocytes after cerebral ischemia, which can aggravate ischemic damage. Apoptosis signal-regulating kinase 1 (ASK1) is an early activator and immune-regulator after ischemic injury, that can lead to cell death. The objective of the present study was to evaluate the role of ASK1 in controlling NLRP2 inflammasomes in astrocytes after cerebral ischemia. In a mouse model of ischemic stroke, the levels of NLRP2 inflammasome components, and interleukin (IL)-1β and IL-18, were quantified in different brain regions. In addition, an astrocyte cell line was subjected to oxygen-glucose deprivation and reperfusion (OGD/R) injury, and the levels of NLRP2 inflammasome factors, IL-1β and IL-18 were evaluated. Ischemic brain injury activated astrocytes. The levels of NLRP2 inflammasome components, IL-1β and IL-18 productions, and cell death increased in the cortex and striatum after ischemic injury. In cultured astrocytes, NLRP2 inflammasome components, IL-1β and IL-18 levels were upregulated after OGD/R. ASK1 silencing or inhibition efficiently reduced NLRP2 inflammasome components and pro-inflammatory cytokine levels in mice and cultured astrocytes. Our findings identify a key role for ASK1 in regulating astroglial inflammasomes after cerebral ischemia. We suggest ASK1 as one of the main targets for astroglial inflammasomes in ischemic stroke.

NLRP3 inflammasome inhibitor OLT1177 suppresses joint inflammation in murine models of acute arthritis

BACKGROUND

Activation of the NLRP3 inflammasome in gout amplifies the inflammatory response and mediates further damage. In the current study, we assessed the therapeutic effect of OLT1177, an orally active NLRP3 inflammasome inhibitor that is safe in humans, in murine acute arthritis models.

METHODS

Zymosan or monosodium urate (MSU) crystals were injected intra-articularly (i.a.) into mouse knee joints to induce reactive or gouty arthritis. Joint swelling, articular cell infiltration, and synovial cytokines were evaluated 25 hours and 4 hours following zymosan or MSU challenge, respectively. OLT1177 was administrated intraperitoneally by oral gavage or in the food by an OLT1177-enriched diet.

RESULTS

OLT1177 reduced zymosan-induced joint swelling (p < 0.001), cell influx (p < 0.01), and synovial levels of interleukin (IL)-1β, IL-6, and chemokine (C-X-C motif) ligand 1 (CXCL1) (p < 0.05), respectively, when compared with vehicle-treated mice. Plasma OLT1177 levels correlated (p < 0.001) dose-dependently with reduction in joint inflammation. Treatment of mice with OLT1177 limited MSU crystal articular inflammation (p > 0.0001), which was associated with decreased synovial IL-1β, IL-6, myeloperoxidase, and CXCL1 levels (p < 0.01) compared with vehicle-treated mice. When administrated orally 1 hour after MSU challenge, OLT1177 reduced joint inflammation, processing of IL-1β, and synovial phosphorylated c-Jun N-terminal kinase compared with the vehicle group. Mice were fed an OLT1177-enriched diet for 3 weeks and then challenged i.a. with MSU crystals. Joint swelling, synovial IL-1β, and expression of Nlrp3 and Il1b were significantly reduced in synovial tissues in mice fed an OLT1177-enriched diet when compared with the standard diet group.

CONCLUSIONS

Oral OLT1177 is highly effective in ameliorating reactive as well as gouty arthritis.