Ly6G+ neutrophil-derived miR-223 inhibits the NLRP3 inflammasome in mitochondrial DAMP-induced acute lung injury

Inflammasome activation in acute lung injury

Inflammasomes are multiprotein complexes tasked with sensing endogenous or exogenous inflammatory signals and integrating this signal into a downstream response. Inflammasome activation has been implicated in a variety of pulmonary diseases, including pulmonary hypertension, bacterial pneumonia, COPD, and asthma. Of increasing interest is the contribution of inflammasome activation in the context of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Inflammasome activation in both the lung parenchyma and resident immune cells generates intereukin-1β (IL-1β) and IL-18, both of which drive the cascade of lung inflammation forward. Blockade of these responses has been shown to be beneficial in animal models and is a focus of translational research in the field. In this review, we will discuss the assembly and regulation of inflammasomes during lung inflammation, highlighting therapeutically viable effector steps. We will examine the importance of IL-1β and IL-18, two key products of inflammasome activation, in ALI, as well as the contribution of the pulmonary endothelial cell to this process. Finally, we will explore translational research moving toward anti-inflammasome therapies for ALI/ARDS and speculate toward future directions for the field.

Progressive Control of Streptococcus agalactiae-Induced Innate Inflammatory Response Is Associated with Time Course Expression of MicroRNA-223 by Neutrophils

Group B streptococcus (GBS) is a human-pathogenic bacterium inducing a strong inflammatory response that may be detrimental for host tissues if not finely regulated. The inflammatory response can be modulated by different molecular mechanisms, among which growing evidence points toward the crucial role of microRNAs (miRNAs). Regarding innate inflammatory response, studies have reported that miR-223 is essential for the control of granulocyte proliferation and activation. Moreover, a number of investigations on miRNA expression profiling performed in various inflammatory settings have revealed that miR-223 is among the top differentially expressed miRNAs. Yet the dynamic pattern of expression of miR-223 in vivo with respect to the evolution of the inflammatory process, especially in microbial infection, remains elusive. In this study, we analyzed the kinetic expression of miR-223 in an inflammatory model of GBS-induced murine pneumonia and looked for correlates with inflammatory markers, including innate cell infiltrates. We found that miR-223 expression is rapidly induced at very early time points (3 to 6 h postinfection [p.i.]) mainly by lung-infiltrating neutrophils. Interestingly, the level of miR-223 accumulating in the lungs remains higher at later stages of infection (24 h and 48 h p.i.), and this correlates with reduced expression of primary inflammatory cytokines and chemokines and with a shift in infiltrating monocyte and macrophage subtypes toward a regulatory phenotype. Transient inhibition of miR-223 by an antagomir resulted in significant increase of CXCL2 expression and partial enhancement of infiltrating neutrophils in GBS-infected lung tissues. This suggests the potential contribution of miR-223 to the resolution phase of GBS-induced acute inflammation.

The Role of MicroRNAs in Acute Respiratory Distress Syndrome and Sepsis, From Targets to Therapies: A Narrative Review

Acute respiratory distress syndrome (ARDS) is a significant cause of morbidity and mortality in the intensive care unit (ICU) and is characterized by lung epithelial and endothelial cell injury, with increased permeability of the alveolar-capillary membrane, leading to pulmonary edema, severe hypoxia, and difficulty with ventilation. The most common cause of ARDS is sepsis, and currently, treatment of ARDS and sepsis has consisted mostly of supportive care because targeted therapies have largely been unsuccessful. The molecular mechanisms behind ARDS remain elusive. Recently, a number of microRNAs (miRNAs) identified through high-throughput screening studies in ARDS patients and preclinical animal models have suggested a role for miRNA in the pathophysiology of ARDS. miRNAs are small noncoding RNAs ranging from 18 to 24 nucleotides that regulate gene expression via inhibition of the target mRNA translation or by targeting complementary mRNA for early degradation. Unsurprisingly, some miRNAs that are differentially expressed in ARDS overlap with those important in sepsis. In addition, circulatory miRNA may be useful as biomarkers or as targets for pharmacologic therapy. This can be revolutionary in a syndrome that has neither a measurable indicator of the disease nor a targeted therapy. While there are currently no miRNA-based therapies targeted for ARDS, therapies targeting miRNA have reached phase II clinical trials for the treatment of a wide range of diseases. Further studies may yield a unique miRNA profile pattern that serves as a biomarker or as targets for miRNA-based pharmacologic therapy. In this review, we discuss miRNAs that have been found to play a role in ARDS and sepsis, the potential mechanism of how particular miRNAs may contribute to the pathophysiology of ARDS, and strategies for pharmacologically targeting miRNA as therapy.

Exosomal LGALS9 in the cerebrospinal fluid of glioblastoma patients suppressed dendritic cell antigen presentation and cytotoxic T-cell immunity

Glioblastoma multiforme (GBM) is highly invasive, with a high recurrence rate and limited treatment options, and is the deadliest glioma. Exosomes (Exos) have attracted much attention in the diagnosis and treatment of GBM and are expected to address the severe limitations of biopsy conditions. Exos in the cerebrospinal fluid (CSF) have great potential in GBM dynamic monitoring and intervention strategies. Here, we evaluated the difference in the proteome information of Exos from the CSF (CSF-Exos) between GBM patients and low-grade glioma patients, and the correlations between GBM-CSF-Exos and immunosuppressive properties. Our results indicates that GBM-CSF-Exos contained a unique protein, LGALS9 ligand, which bound to the TIM3 receptor of dendritic cells (DCs) in the CSF to inhibit antigen recognition, processing and presentation by DCs, leading to failure of the cytotoxic T-cell-mediated antitumor immune response. Blocking the secretion of exosomal LGALS9 from GBM tumors could cause mice to exhibit sustained DC tumor antigen-presenting activity and long-lasting antitumor immunity. We concluded that GBM cell-derived exosomal LGALS9 acts as a major regulator of tumor progression by inhibiting DC antigen presentation and cytotoxic T-cell activation in the CSF and that loss of this inhibitory effect can lead to durable systemic antitumor immunity.

Silencing of long non-coding RNA MEG3 alleviates lipopolysaccharide-induced acute lung injury by acting as a molecular sponge of microRNA-7b to modulate NLRP3

We aimed to elucidate the roles of the long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3)/microRNA-7b (miR-7b)/NLR pyrin domain containing 3 (NLRP3) axis in lipopolysaccharide (LPS)-induced acute lung injury (ALI). Mouse alveolar macrophage NR8383 and mice were administrated with LPS to establish ALI models in vitro and in vivo. NLRP3 was silenced while miR-7b was overexpressed in LPS-induced NR8383 cell model of ALI. The interleukin-18 (IL-18) and IL-1β, as well as caspase-1, tumor necrosis factor-α (TNF-α) and IL-6 protein levels were assayed. To further investigate the underlying mechanisms of NLRP3 in ALI, lncRNA MEG3 was silenced and miR-7b was overexpressed in LPS-induced NR8383 cell model of ALI, after which in vivo experiments were performed for further verification. NLRP3 was highly expressed in LPS-induced NR8383 cell model of ALI. Silencing NLRP3 or overexpressing miR-7b inhibited IL-18 and IL-1β, as well as caspase-1, TNF-α and IL-6. LncRNA MEG3 could sponge miR-7b, and lncRNA MEG3 silencing or miR-7b overexpression downregulates NLRP3 expression, thus reducing IL-18 and IL-1β, as well as caspase-1, TNF-α and IL-6 levels. The in vivo experiments further confirmed the aforementioned findings. Silencing lncRNA MEG3 augments miR-7b binding to NLRP3 and downregulates NLRP3 expression, which ultimately improves LPS-induced ALI.

Molecular Mechanisms of Action of Emodin: As an Anti-Cardiovascular Disease Drug

Emodin is a natural occurring anthraquinone derivative isolated from roots and barks of numerous plants, molds, and lichens. It is found to be an active ingredient in different Chinese herbs including Rheum palmatum and Polygonam multiflorum, and it is a pleiotropic molecule with diuretic, vasorelaxant, anti-bacterial, anti-viral, anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. Moreover, emodin has also been shown to have a wide activity of anti-cardiovascular diseases. It is mainly involved in multiple molecular targets such as inflammatory, anti-apoptosis, anti-hypertrophy, anti-fibrosis, anti-oxidative damage, abnormal, and excessive proliferation of smooth muscle cells in cardiovascular diseases. As a new type of cardiovascular disease treatment drug, emodin has broad application prospects. However, a large amount of evidences detailing the effect of emodin on many signaling pathways and cellular functions in cardiovascular disease, the overall understanding of its mechanisms of action remains elusive. In addition, by describing the evidence of the effects of emodin in detail, the toxicity and poor oral bioavailability of mice have been continuously discovered. This review aims to describe a timely overview of emodin related to the treatment of cardiovascular disease. The emphasis is to summarize the pharmacological effects of emodin as an anti-cardiovascular drug, as well as the targets and its potential mechanisms. Furthermore, the treatment of emodin compared with conventional cardiovascular drugs or target inhibitors, the toxicity, pharmacokinetics and derivatives of emodin were discussed.

Paeonol inhibits NLRP3 mediated inflammation in rat endothelial cells by elevating hyperlipidemic rats plasma exosomal miRNA-223

Atherosclerosis (AS) is a multifactorial chronic inflammatory disease, and hyperlipidemia is the important factors leading to AS, which can cause vascular endothelial dysfunction. Paeonol (Pae) is a potential therapeutic drug for AS, and we have previously shown that Pae regulated the expression of monocytes-derived exosomal microRNA-223 (miR-223). However, the mechanisms of the anti-AS effect of Pae are still not fully understood. In this study, we aim to investigate if Pae could inhibit NLRP3 inflammasome mediated inflammation via elevating hyperlipidemic rats plasma-derived exosomal miR-223. We used high-fat-diet induced hyperlipidemic rats as model for further investigation. Rats were treated with Pae (75, 150 or 300 mg/kg) orally, and then exosomes were isolated from hyperlipidemic rat plasma by ultracentrifugation. In vivo experiments confirmed that Pae markedly reduced serum TC, TG, IL-1β, and IL-6 levels. Both CCK-8 and trypan blue staining showed that the survival rate of rat aortic endothelial cells (RAECs) in the Pae-exo group was higher than that in the model group. Also, Pae-exo dose-dependently increased the survival rate of RAECs and reduced inflammatory cytokines level (IL-1β, and IL-6). Furthermore, Pae-exo successfully increased the expression of exosomal miR-223 and relieved inflammatory secretion. Finally, decreased expression of NLRP3, ASC, caspase-1 and ICAM-1 indicated that Pae-exo attenuated inflammatory reaction of RAECs by suppressing NLRP3 signaling pathway. Altogether, our results showed that Pae inhibited the downstream NLRP3 inflammasome pathway by increasing the level of miR-223 in plasma derived exosomes of hyperlipidemic rats, providing new insights in the treatment of AS with the use of Pae.

Epigenetic Mechanisms of Inflammasome Regulation

The innate immune system represents the host's first-line defense against pathogens, dead cells or environmental factors. One of the most important inflammatory pathways is represented by the activation of the NOD-like receptor (NLR) protein family. Some NLRs induce the assembly of large caspase-1-activating complexes called inflammasomes. Different types of inflammasomes have been identified that can respond to distinct bacterial, viral or fungal infections; sterile cell damage or other stressors, such as metabolic imbalances. Epigenetic regulation has been recently suggested to provide a complementary mechanism to control inflammasome activity. This regulation can be exerted through at least three main mechanisms, including CpG DNA methylation, histones post-translational modifications and noncoding RNA expression. The repression or promotion of expression of different inflammasomes (NLRP1, NLRP2, NLRP3, NLRP4, NLRP6, NLRP7, NLRP12 and AIM2) through epigenetic mechanisms determines the development of pathologies with variable severity. For example, our team recently explored the role of microRNAs (miRNAs) targeting and modulating the components of the inflammasome as potential biomarkers in bladder cancer and during therapy. This suggests that the epigenetic control of inflammasome-related genes could represent a potential target for further investigations of molecular mechanisms regulating inflammatory pathways.

miR-138-5p targets sirtuin1 to regulate acute lung injury by regulation of the NF-κB signaling pathway

Acute lung injury (ALI), a disease with a high mortality rate, is a noncardiogenic pulmonary inflammatory response and characterized by damage to the pulmonary system. In this study, we explored the mechanism of the occurrence and development of ALI. It was firstly found that miR-138-5p could inhibit the expression of sirtuin1 (SIRT1), and we further demonstrated that miR-138-5p targets directly SIRT1 through the luciferase assay, while the latter negatively regulated the expression of NF-κB. A549 cells were treated with lipopolysaccharide in vitro to simulate ALI cells and induce ALI in the model mice. The results showed that inhibiting the expression of miR-138-5p could effectively increase the viability of damaged cells, promote cell proliferation, reduce apoptosis, inhibit the inflammatory response, reduce oxidative stress, and then relieve ALI symptoms. Collectively, our results suggested that miR-138-5p can inhibit SIRT1 expression and indirectly activate the NF-κB signaling pathway, thus regulating the development of ALI.

Immediate and long-term consequences of COVID-19 infections for the development of neurological disease

Increasing evidence suggests that infection with Sars-CoV-2 causes neurological deficits in a substantial proportion of affected patients. While these symptoms arise acutely during the course of infection, less is known about the possible long-term consequences for the brain. Severely affected COVID-19 cases experience high levels of proinflammatory cytokines and acute respiratory dysfunction and often require assisted ventilation. All these factors have been suggested to cause cognitive decline. Pathogenetically, this may result from direct negative effects of the immune reaction, acceleration or aggravation of pre-existing cognitive deficits, or de novo induction of a neurodegenerative disease. This article summarizes the current understanding of neurological symptoms of COVID-19 and hypothesizes that affected patients may be at higher risk of developing cognitive decline after overcoming the primary COVID-19 infection. A structured prospective evaluation should analyze the likelihood, time course, and severity of cognitive impairment following the COVID-19 pandemic.

MicroRNA: Potential biomarker and target of therapy in acute lung injury

MicroRNAs (miRNAs) are small noncoding RNAs stretching over 18-22 nucleotides and considered to be modifiers of many respiratory diseases. They are highly evolutionary conserved and have been implicated in several biological processes, including cell proliferation, apoptosis, differentiation, among others. Acute lung injury (ALI) is a fatal disease commonly caused by direct or indirect injury factors and has a high mortality rate in intensive care unit. Changes in expression of several types of miRNAs have been reported in patients with ALI. Some miRNAs suppress cellular injury and accelerate the recovery of ALI by targeting specific molecules and decreasing excessive immune response. For this reason, miRNAs are proposed as potential biomarkers for ALI and as therapeutic targets for this disease. This review summarizes current evidence supporting the role of miRNAs in ALI.

Cellular stress responses and dysfunctional Mitochondrial-cellular senescence, and therapeutics in chronic respiratory diseases

The abnormal inflammatory responses due to the lung tissue damage and ineffective repair/resolution in response to the inhaled toxicants result in the pathological changes associated with chronic respiratory diseases. Investigation of such pathophysiological mechanisms provides the opportunity to develop the molecular phenotype-specific diagnostic assays and could help in designing the personalized medicine-based therapeutic approaches against these prevalent diseases. As the central hubs of cell metabolism and energetics, mitochondria integrate cellular responses and interorganellar signaling pathways to maintain cellular and extracellular redox status and the cellular senescence that dictate the lung tissue responses. Specifically, as observed in chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis, the mitochondria-endoplasmic reticulum (ER) crosstalk is disrupted by the inhaled toxicants such as the combustible and emerging electronic nicotine-delivery system (ENDS) tobacco products. Thus, the recent research efforts have focused on understanding how the mitochondria-ER dysfunctions and oxidative stress responses can be targeted to improve inflammatory and cellular dysfunctions associated with these pathologic illnesses that are exacerbated by viral infections. The present review assesses the importance of these redox signaling and cellular senescence pathways that describe the role of mitochondria and ER on the development and function of lung epithelial responses, highlighting the cause and effect associations that reflect the disease pathogenesis and possible intervention strategies.

miR-223: A Key Regulator in the Innate Immune Response in Asthma and COPD

Asthma and Chronic Obstructive Pulmonary Disease (COPD) are chronic obstructive respiratory diseases characterized by airway obstruction, inflammation, and remodeling. Recent findings indicate the importance of microRNAs (miRNAs) in the regulation of pathological processes involved in both diseases. MiRNAs have been implicated in a wide array of biological processes, such as inflammation, cell proliferation, differentiation, and death. MiR-223 is one of the miRNAs that is thought to play a role in obstructive lung disease as altered expression levels have been observed in both asthma and COPD. MiR-223 is a hematopoietic cell–derived miRNA that plays a role in regulation of monocyte-macrophage differentiation, neutrophil recruitment, and pro-inflammatory responses and that can be transferred to non-myeloid cells via extracellular vesicles or lipoproteins. In this translational review, we highlight the role of miR-223 in obstructive respiratory diseases, focusing on expression data in clinical samples of asthma and COPD, in vivo experiments in mouse models and in vitro functional studies. Furthermore, we provide an overview of the mechanisms by which miR-223 regulates gene expression. We specifically focus on immune cell development and activation and involvement in immune responses, which are important in asthma and COPD. Collectively, this review demonstrates the importance of miR-223 in obstructive respiratory diseases and explores its therapeutic potential in the pathogenesis of asthma and COPD.

MiR-223 plays a protecting role in neutrophilic asthmatic mice through the inhibition of NLRP3 inflammasome

Background

Neutrophilic subtype asthma occurs in approximately 15–25% of the asthma cases and is associated with severe airflow obstruction, corticosteroid resistance. MicroRNA plays a vital role in regulating many immune processes, but how miRNA circuits coordinate airway inflammation during neutrophilic asthma is unclear.

Methods

To investigate the molecular mechanism of miR-223 in regulation of neutrophilic airway inflammation, miR-223 knockout mice were used to the OVA/CFA-induced neutrophilic asthma or treated with NLRP3 inhibitor and IL-1β receptor antagonist. Based on the results obtained, wide-type mice were subsequently treated with miR-223 agomirs or negative control agomirs, and the effects on airway inflammation were assessed using morphometric techniques, quantitative RT-PCR, western blot, ELISA and other molecular approaches.

Results

The expression of miR-223 was upregulated in lung tissues of experimental mice model. Furthermore, miR-223^−/− mice led to aggravated neutrophilic airway inflammation with heightened histopathological, inflammatory cells and cytokines readouts. Moreover, miR-223^−/− mice also presented with enhanced NLRP3 inflammasome level with elevated IL-1β. Blocking NLRP3 or IL-1β diminished this phenotype. Finally, overexpression of miR-223 via treatment with miR-223 agomirs attenuated airway inflammation, NLRP3 levels and IL-1β release.

Conclusions

The findings of this study revealed a crucial role for miR-223 in regulating the immunoinflammatory responses by depressing the NLRP3/ IL-1β axis in neutrophilic asthma.

microRNA-223 promotes autophagy to aggravate lung ischemia-reperfusion injury by inhibiting the expression of transcription factor HIF2α

Lung ischemia-reperfusion (I/R) injury severely endangers human health, and recent studies have suggested that certain microRNAs (miRNAs) play important roles in this pathological phenomenon. The current study aimed to ascertain the ability of miR-223 to influence lung I/R injury by targeting hypoxia-inducible factor-2α (HIF2α). First, mouse models of lung I/R injury were established: during surgical procedures, pulmonary arteries and veins and unilateral pulmonary portal vessels were blocked and resuming bilateral pulmonary ventilation, followed by restoration of bipulmonary ventilation. In addition, a lung I/R injury cell model was constructed by exposure to hypoxic reoxygenation (H/R) in mouse pulmonary microvascular endothelial cells (PMVECs). Expression of miR-223, HIF2α and β-catenin in tissues or cells was determined by RT-qPCR and Western blot analysis. Correlation between miR-223 and HIF2α was analyzed by dual luciferase reporter gene assay. Further, lung tissue injury and mouse PMVEC apoptosis was evaluated by HE, TUNEL staining and flow cytometry. Autophagosomes in cells were detected by light chain3 immunofluorescence assay. miR-223 was expressed at a high level while HIF2α/β-catenin was downregulated in tissues and cells with lung I/R injury. Further, miR-223 targeted and repressed HIF2α expression to downregulate β-catenin expression. The miR-223/HIF2α/β-catenin axis aggravated H/R injury in mouse PMVECs and lung I/R injury in mice by enhancing autophagy. Taken together, miR-223 inhibits HIF2α to repress β-catenin, thus contributing to autophagy to complicate lung I/R injury. These findings provide a promising therapeutic target for treating lung I/R injury.

Sinomenine Attenuates Cartilage Degeneration by Regulating miR-223-3p/NLRP3 Inflammasome Signaling

Sinomenine (SIN) has been shown to protect against IL-1β-induced chondrocyte apoptosis in vitro. However, the role of SIN in the anterior cruciate ligament transection (ACLT)-induced osteoarthritis (OA) mouse model and its underlying molecular mechanisms remain unclear. In the present study, the protective effect of SIN on ACLT-induced articular cartilage degeneration and IL-1β-induced chondrocyte apoptosis miR-223-3p/NLRP3 signaling regulation was investigated. Safranin O staining was performed to evaluate the pathological changes of articular cartilage. Chondrocyte apoptosis was measured with Annexin V-fluorescein isothiocyanate/polyimide (annexin V-FITC/PI) staining using flow cytometry. Gene and protein expression were detected by RT-qPCR and Western blotting, respectively. SIN administration markedly improved articular cartilage degradation in mice undergoing ACLT surgery. In addition, SIN treatment downregulated the levels of inflammatory cytokines and the protein expression of NLRP3 inflammasome components and upregulated the expression of miR-223-3p in OA mice and IL-1β-stimulated chondrocytes. In vitro, we found that NLRP3 was a direct target of miR-223-3p, and overexpression of miR-223-3p blocked IL-1β-induced apoptosis and the inflammatory response in chondrocytes. These findings indicate that miR-223-3p/NLRP3 signaling could be used as a potential target of SIN for the treatment of OA.

The strategies of targeting the NLRP3 inflammasome to treat inflammatory diseases

The NLRP3 inflammasome is a cytoplasmic multiprotein complex, the assembly of which can be initiated in response to various exogenous or endogenous danger signals. Excessive activation of the NLRP3 inflammasome has been implicated in the pathogenesis of a wide variety of human inflammatory diseases, suggesting that the NLRP3 inflammasome is a potential target for the treatment of these diseases. However, clinical drugs targeting the NLRP3 inflammasome are still not available. Recent data have elucidated the different signaling pathways or events that can control NLRP3 inflammasome activation and have provided some potential compounds with anti-NLRP3 inflammasome activity. Here, we summarize the molecular mechanisms and diseases involved in NLRP3 inflammasome activation and discuss the potential strategies targeting different aspects of the NLRP3 inflammasome and its implications for the treatment of inflammatory diseases.

Scutellaria barbata D. Don (SBD) protects oxygen glucose deprivation/reperfusion-induced injuries of PC12 cells by up-regulating Nrf2

This study aimed to investigate the potential effect of Scutellaria barbata D. Don (SBD) on oxygen glucose deprivation/reperfusion (OGD/R)-injured PC12 cells. PC12 cells were pretreated with various concentrations of 0.1-0.8 mg/ml SBD for indicated times (12-48 h) and then subjected to OGD/R injury. Cell viability, apoptosis and proliferation were detected using MTT assay, flow cytometry, Ki67 staining and western blot. Oxidative damage was assessed by detecting MDA content, SOD activity and GSH levels. The mitochondrial membrane potential (Δψm) was measured by Rh123 staining. Western blot was performed to assess the expression levels of Nrf2 and PI3K/AKT pathway-related proteins. We found that SBD pretreatment promoted cell viability and proliferation but inhibited apoptosis of OGD/R-injured PC12 cells in dosage- and time-dependent manner. Meanwhile, SBD attenuated oxidative damage and restored mitochondria dysfunction, as evidenced by the reduced MDA content, the increased SOD and GSH levels, and the increased Δψm. Furthermore, SBD induced the expression of Nrf2 in a PI3K/AKT-dependent signalling. Knockdown of Nrf2 blocked the protective effects of SBD on PC12 cells. In conclusion, this study demonstrates that SBD pretreatment protects PC12 cells against OGD/R-induced injury. The potential mechanism may be through up-regulating the expression of Nrf2 in a PI3K/AKT-dependent pathway.

Insights into inflammasome and its research advances in cancer

Inflammation has long been proven to engage in tumor initiation and progression. Inflammasome, as a member of innate immunity-induced host defense inflammation, also plays critical roles in cancer. Inflammasome is a multiprotein complex responding to pathogen-associated molecular patterns and damage-associated molecular patterns. It is composed of receptors such as NOD-like receptors and AIM2-like receptors, adaptor protein ASC, and effector caspase-1, which can process proinflammatory cytokines interleukin (IL)-1β and IL-18. It has been reported that upregulated inflammasome activity is correlated to various types of cancers including breast cancer, gastric cancer, brain tumor, and malignant prostate, while inflammasomes also have a protective role in colitis-associated cancer. Autophagy, an intracellular recycling process for maintaining homeostasis, is deemed to contribute to the underlying mechanism of its dual roles in cancer. It has been found that distinct tumor stages and different isotypes of caspases involved in the inflammasome pathway can affect the roles of inflammasome in cancer. In this review, we update the latest evidence of inflammasome roles in cancer and novel inflammasome pathway-targeting agents for immunotherapy and discuss future research directions of inflammasome-based target therapy.

Hydrogen alleviates mitochondrial dysfunction and organ damage via autophagy‑mediated NLRP3 inflammasome inactivation in sepsis

Sepsis is a highly heterogeneous syndrome that is caused by a dysregulated host response to infection. The disproportionate inflammatory response to invasive infection is a triggering event inducing sepsis. The activation of inflammasomes in sepsis can amplify inflammatory responses. It has been reported that damaged mitochondria contribute to NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome-related sepsis. Our previous study revealed that hydrogen (H₂) exerts anti-inflammatory effects in sepsis but the detailed mechanism remains to be elucidated. In the present study, septic mice induced by cecal ligation and puncture (CLP) and macrophages induced by lipopolysaccha-ride (LPS) were used as models of sepsis in vivo and in vitro, respectively. An inducer and inhibitor of autophagy and the NLRP3 inflammasome were administered to investigate the detailed mechanism of action of H₂ treatment in sepsis. The results demonstrated that LPS and ATP led to NLRP3 inflammasome pathway activation, excessive cytokine release, mitochondrial dysfunction and the activation of autophagy. CLP induced organ injury and NLRP3 pathway activation. H₂ treatment ameliorated vital organ damage, the inflammatory response, mitochondrial dysfunction and NLRP3 pathway activation, and promoted autophagy in macrophages induced by LPS and in CLP mice. However, the inhibitor of autophagy and the inducer of NLRP3 reversed the protective effect of H₂ against organ damage, the inflammatory response and mitochondrial dysfunction in vivo and in vitro. Collectively, the results demonstrated that H₂ alleviated mitochondrial dysfunction and cytokine release via autophagy-mediated NLRP3 inflammasome inactivation.

MicroRNA Post-transcriptional Regulation of the NLRP3 Inflammasome in Immunopathologies

Inflammation has a crucial role in protection against various pathogens. The inflammasome is an intracellular multiprotein signaling complex that is linked to pathogen sensing and initiation of the inflammatory response in physiological and pathological conditions. The most characterized inflammasome is the NLRP3 inflammasome, which is a known sensor of cell stress and is tightly regulated in resting cells. However, altered regulation of the NLRP3 inflammasome is found in several pathological conditions, including autoimmune disease and cancer. NLRP3 expression was shown to be post-transcriptionally regulated and multiple miRNA have been implicated in post-transcriptional regulation of the inflammasome. Therefore, in recent years, miRNA based post-transcriptional control of NLRP3 has become a focus of much research, especially as a potential therapeutic approach. In this review, we provide a summary of the recent investigations on the role of miRNA in the post-transcriptional control of the NLRP3 inflammasome, a key regulator of pro-inflammatory IL-1β and IL-18 cytokine production. Current approaches to targeting the inflammasome product were shown to be an effective treatment for diseases linked to NLRP3 overexpression. Although utilizing NLRP3 targeting miRNAs was shown to be a successful therapeutic approach in several animal models, their therapeutic application in patients remains to be determined.

Blockade of HMGB1 signaling pathway by ethyl pyruvate inhibits tumor growth in diffuse large B-cell lymphoma

High mobility group box 1 (HMGB1) protein in the tumor microenvironment actively contributes to tumor progression but its role in diffuse large B-cell lymphoma (DLBCL) is unknown. The aim of this study was to determine the mechanism by which HMGB1 promotes tumor growth in DLBCL and whether blockade of HMGB1 signaling pathway could inhibit tumorigenesis. We report that HMGB1 promotes proliferation of DLBCL cells by activation of AKT, extracellular signal-regulated kinases 1/2 (ERK1/2), signal transducer and activator of transcription 3 (STAT3) and SRC Proto-Oncogene, Non-Receptor Tyrosine Kinase (Src). Ethyl pyruvate (EP), an anti-inflammatory agent, inhibits HMGB1 active release from DLBCL cells and significantly inhibited proliferation of DLBCL cells in vitro. Treatment with EP significantly prevented and inhibited tumor growth in vivo and prolonged DLBCL-bearing mice survival. EP significantly downregulated HMGB1 expression and phosphorylation of Src and ERK1/2 in mice lymphoma tissue. EP induced accumulation of the cell cycle inhibitor p27 but downregulated expression of cyclin-dependent kinase 2 (CDK2). Increased nuclear translocation of p27 interacted with CDK2 and cyclin A, which led to blockade of cell cycle progression at the G1 to S phase transition. In conclusion, we demonstrated for the first time that blockade of HMGB1-mediated signaling pathway by EP effectively inhibited DLBCL tumorigenesis and disease progression.

MiR-155 controls follicular Treg cell-mediated humoral autoimmune intestinal injury by inhibiting CTLA-4 expression

High expression levels of miR-155 are involved in the pathogenesis of inflammatory bowel disease (IBD). We observed an increase in miR-155 in peripheral regulatory T (Treg) cells from IBD patients. Mice that specifically overexpress miR-155 in Foxp3+ Treg cells exhibit spontaneous autoimmunity and more severe dextran sulfate sodium (DSS)-induced intestinal injury. MiR-155 overexpression can lead to a lack of follicular Treg (Tfr) cells and central Treg (cTreg), whereas DSS treatment further depletes the Tfr cells. Furthermore, miR-155 can target the expression of CTLA-4 in cTreg and Tfr, directly inhibiting Tfr cell production and promoting enhanced germinal center (GC) B cell activation and autoantibody overproduction. This outcome may be the cause of severe intestinal injury in patients with autoimmune IBD.

Emodin Attenuates Lipopolysaccharide-Induced Injury via Down-Regulation of miR-223 in H9c2 Cells

Emodin is a natural product extracted from Rheum palmatum. There are few recent studies on emodin in the treatment of myocarditis. This study aimed to investigate the effect of emodin on lipopolysaccharide (LPS)-induced inflammatory injury in cardiomyocytes. H9c2 cells were treated with 10 μM of LPS and different concentrations (0, 1, 5, 10, 15, and 20 μM) of emodin. The expression of miR-223 was changed by transient transfection. Thereafter, cell viability, apoptosis, the expression of CyclinD1 and Jnk-associated proteins, and the release of pro-inflammatory factors were assessed by cell Counting Kit-8, flow cytometry analysis, quantitative real-time polymerase chain reaction Western blot, and enzyme-linked immunosorbent assay respectively. The results showed that 20 μM of emodin significantly decreased H9c2 cells viability. LPS significantly damaged H9c2 cells, as cell viability was reduced, CyclinD1 was down-regulated, apoptosis was induced, the release of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-alpha were increased, and the phosphorylation of Jnk and c-Jun were promoted. Emodin protected H9c2 cells against LPS-induced inflammatory injury. miR-223 expression was significantly up-regulated by LPS exposure, while emodin lessened this up-regulation. LPS-injured H9c2 cells were attenuated by the overexpression of miR-223; emodin has protective actions on LPS-injured H9c2 cells and targets. Besides, SP600125 (an inhibitor of Jnk) eliminated miR-223-modulated inflammatory injury in H9c2 cells. These data demonstrated that emodin could attenuate LPS-induced inflammatory injury and deactivate Jnk signaling pathway through down-regulation of miR-223.

Intranasal Application of Budesonide Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Suppressing Nucleotide-Binding Oligomerization Domain-Like Receptor Family, Pyrin Domain-Containing 3 Inflammasome Activation in Mice

Aim

To investigate the protective effects of budesonide against lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in a murine model and its underlying mechanism.

Methods

Adult male C57BL/6 mice were divided into three groups: control, ALI, and ALI + budesonide groups. LPS (5 mg/kg) was intratracheally injected to induce ALI in mice. Budesonide (0.5 mg/kg) was intranasally given 1 h before LPS administration in the ALI + budesonide group. Twelve hours after LPS administration, all mice were sacrificed. Hematoxylin-eosin staining and pathological scores were used to evaluate pathological injury. Bronchoalveolar lavage was performed. The numbers of total cells, neutrophils, and macrophages in the bronchoalveolar lavage fluid (BALF) were counted. Enzyme-linked immunosorbent assay was employed to detect the proinflammatory cytokines in BALF and serum, including tumor necrosis factor- (TNF-) α, monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 1β. The expression of the nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome was detected by western blotting. A lethal dose of LPS (40 mg/kg, intraperitoneally) was injected to evaluate the effects of budesonide on survival rates.

Results

Budesonide pretreatment dramatically attenuated pathological injury and reduced pathological scores in mice with ALI. Budesonide pretreatment obviously reduced the numbers of total cells, neutrophils, and macrophages in the BALF of mice with ALI. Additionally, budesonide dramatically reduced TNF-α and MCP-1 expression in the BALF and serum of mice with ALI. Budesonide significantly suppressed NLRP3 and pro-caspase-1 expression in the lung and reduced IL-1β content in the BALF, indicating that budesonide inhibited the activation of the NLRP3 inflammasome. Furthermore, we found that budesonide improved the survival rates of mice with ALI receiving a lethal dose of LPS.

Conclusion

Suppression of NLRP3 inflammasome activation in mice via budesonide attenuated lung injury induced by LPS in mice with ALI.

MicroRNA‑223 attenuates LPS‑induced inflammation in an acute lung injury model via the NLRP3 inflammasome and TLR4/NF‑κB signaling pathway via RHOB

Acute lung injury (ALI) and the more severe acute respiratory distress syndrome are common and complex inflammatory lung diseases. MicroRNAs (miRs) have emerged as novel gene regulatory molecules, serving a crucial role in a variety of complex diseases, including ALI. In the present study, the anti‑inflammatory action of miR‑223 on inflammation in ALI was demonstrated and the possible mechanism was further examined. In lipopolysaccharide‑induced ALI, the expression of miR‑223 was reduced compared with that in the control normal group. An in vitro model was used to analyze the effect of miR‑223 downregulation on an ALI model, which increased inflammation, and induced the activation of the NACHT, LRR and PYD domains‑containing protein 3 (NLRP3) inflammasome and Toll‑like receptor 4 (TLR4)/nuclear factor (NF)‑κB signaling pathway via rho‑related GTP‑binding protein RhoB (RHOB). In addition, the overexpression of miR‑223 reduced inflammation and suppressed the NLRP3 inflammasome and TLR4/NF‑κB signaling pathway via RHOB in the in vitro model. Furthermore, TLR4 inhibitor or NLRP3 inhibitor reduced the pro‑inflammatory effect of miR‑223 downregulation in ALI. In conclusion, the results of the present study indicated that miR‑223 functioned as a biological indicator by regulating inflammation in ALI, and may represent a novel potential therapeutic target and prognostic marker of ALI.

MiR-24 inhibits inflammatory responses in LPS-induced acute lung injury of neonatal rats through targeting NLRP3

Inflammation plays an important role in the development of acute lung injury (ALI) in preterm infants. Despite the critical role of microRNA in inflammatory response, little is known about its function in ALI. In this study, we investigate the role of MicroRNA-24 (miR-24) in lipopolysaccharide (LPS) induced neonatal rats ALI and its potential mechanism. LPS was used to induce ALI neonatal animal model. miR-24 expression in the lung tissues of LPS-challenged neonatal rats was detected by qPCR. Proinflammatory factors, including tumor necrosis factor-alpha (TNF-α), IL-1β, IL-18 in the bronchoalveolar lavage fluid and lung tissues of LPS-challenged neonatal rats were measured by qRT-PCR and western blot, respectively. The mRNA levels of surfactant protein A (SP-A) and D (SP-D) was measured by qRT-PCR. Direct binding of miR-24 and pyrin domain-containing 3(NLRP3) were determined by dual luciferase assay. The levels of NLRP3, apoptosis-associated speck-like protein containing a C‑terminal caspase recruitment domain (ASC) and caspase-1 protein expression were detected by immunohistochemistry (IHC) staining and western blot, respectively. Our data indicated that LPS-induced lung injury in neonatal rats and resulted in significant downregulated of miR-24 expression. Overexpression of miR-24 significantly reduced LPS-induced lung damage and decreased the release of proinflammatory cytokine TNF-α, IL-6, IL-1β and SP-A, SP-D expression induced by LPS. In addition, miR-24 inhibited the expression of NLRP3 by directly targeting to the CDS region of NLRP3 mRNA. Furthermore, miR-24 overexpression attenuated lung inflammation and deactivated the NLRP3/caspase-1/IL-1β pathway in LPS-challenged neonatal rats. These data show that miR-24 alleviated inflammatory responses in LPS-induced ALI via targeting NLRP3.

MicroRNA miR-223 as regulator of innate immunity

MicroRNAs were discovered more than 2 decades ago and have profound impact on diverse biological processes. Specific microRNAs have important roles in modulating the innate immune response and their dysregulation has been demonstrated to contribute to inflammatory diseases. MiR-223 in particular, is very highly expressed and tightly regulated in hematopoietic cells. It functions as key modulator for the differentiation and activation of myeloid cells. The central role of miR-223 in myeloid cells, especially neutrophil and macrophage differentiation and activation has been studied extensively. MiR-223 contributes to myeloid differentiation by enhancing granulopoiesis while inhibiting macrophage differentiation. Uncontrolled myeloid activation has detrimental consequences in inflammatory disease. MiR-223 serves as a negative feedback mechanism controlling excessive innate immune responses in the maintenance of myeloid cell homeostasis. This review summarizes several topics covering the function of miR-223 in myeloid differentiation, neutrophil and macrophage functions, as well as in inflammatory diseases including acute respiratory distress syndrome and inflammatory bowel disease. In addition, nonmyeloid functions of miR-223 are also discussed in this review. Therapeutic enhancement of miR-223 to dampen inflammatory targets is also highlighted as potential treatment to control excessive innate immune responses during mucosal inflammation.

MiR-223-3p overexpression inhibits cell proliferation and migration by regulating inflammation-associated cytokines in glioblastomas

Glioblastoma(GBM) is most common brain tumor in adults. Currently standard treatments have limited effect to increase the survival, because there are still largely unclear mechanisms in glioblastoma development. miR-223 was involved in various types of cancer, however, the function of miR-223-3p in GBM was still unclear. In our study, real-time PCR was performed to exam the expression level of miR-223-3p and NLRP3 (Nucleotide-binding oligomerization domain(NOD)-like receptor family PYRIN domain containing-3) in GBM tissues. Following that, mimic or inhibitor of miR-223-3p were used to modulate miR-223-3p expression in GBM cell lines respectively. Then, we analyzed cell proliferation and migration by cell counting kit and transwell assay. Further, western blot was performed to detect several inflammation-associated cytokines level in GBM cell lines. We found that miR-223-3p was decreased but NLRP3 was increased in GBM tissues. Treatment with miR-223-3p mimic inhibits cell proliferation and migration via decreasing several inflammation-associated cytokines, including interleukin-1β (IL-1β), monocyte chemoattractant protein-1 (MCP-1), IL-8 and IL-18. Importantly, these effects induced by miR-223-3p could be attenuated by NLRP3 overexpression, which was considered as one of target genes of miR-223-3p. In conclusion, these results indicated that miR-223-3p might act as a suppressor and a potential therapy target of GBM.