HBV inhibits LPS-induced NLRP3 inflammasome activation and IL-1β production via suppressing the NF-κB pathway and ROS production

A Polysaccharide From Eupolyphaga sinensis Walker With Anti-HBV Activities In Vitro and In Vivo

Hepatitis B virus (HBV) infection remains a major global threat to human health worldwide. Recently, the Chinese medicines with antiviral properties and low toxicity have been a concern. In our previous study, Eupolyphaga sinensis Walker polysaccharide (ESPS) has been isolated and characterized, while its antiviral effect on HBV remained unclear. The anti-HBV activity of ESPS and its regulatory pathway were investigated in vitro and in vivo. The results showed that ESPS significantly inhibited the production of HBsAg, HBeAg, and HBV DNA in the supernatants of HepG2.2.15 in a dose-dependent manner; HBV RNA and core protein expression were also decreased by ESPS. The in vivo studies using HBV transgenic mice further revealed that ESPS (20 and 40 mg/kg/2 days) significantly reduced the levels HBsAg, HBeAg, and HBV DNA in the serum, as well as HBV DNA and HBV RNA in mice liver. In addition, ESPS activated the Toll-like receptor 4 (TLR4) pathway; elevated levels of IFN-β, TNF-α, and IL-6 in the serum were observed, indicating that the anti-HBV effect of ESPS was achieved by potentiating innate immunity function. In conclusion, our study shows that ESPS is a potential anti-HBV ingredient and is of great value in the development of new anti-HBV drugs.

TSPO Deficiency Exacerbates GSDMD-Mediated Macrophage Pyroptosis in Inflammatory Bowel Disease

Background: the 18-kDa translocator protein (TSPO) is a mitochondrial outer membrane protein, and its expression tends to increase in response to inflammatory stimulation, rapidly. However, the role of TSPO in inflammation and pyroptosis is not yet clear. Here, we identified TSPO as a novel key regulator of pyroptosis. (2) Methods: TSPO knockout and DSS induced mouse inflammatory bowel disease (IBD) models were employed to assess the roles of TSPO in the pathogenesis of IBD. Primary peritoneal macrophages from TSPO knockout mice were applied to evaluate the mechanism of TSPO in cell pyroptosis. Conclusions: in response to inflammatory injury, TSPO expression is rapidly upregulated and provides a protective function against GSDMD-mediated pyroptosis, which helps us better understand the biological role of TSPO and a novel regulatory mechanism of the pyroptosis process.

Regulation of Pattern-Recognition Receptor Signaling by HBX During Hepatitis B Virus Infection

As a small DNA virus, hepatitis B virus (HBV) plays a pivotal role in the development of various liver diseases, including hepatitis, cirrhosis, and liver cancer. Among the molecules encoded by this virus, the HBV X protein (HBX) is a viral transactivator that plays a vital role in HBV replication and virus-associated diseases. Accumulating evidence so far indicates that pattern recognition receptors (PRRs) are at the front-line of the host defense responses to restrict the virus by inducing the expression of interferons and various inflammatory factors. However, depending on HBX, the virus can control PRR signaling by modulating the expression and activity of essential molecules involved in the toll-like receptor (TLR), retinoic acid inducible gene I (RIG-I)-like receptor (RLR), and NOD-like receptor (NLR) signaling pathways, to not only facilitate HBV replication, but also promote the development of viral diseases. In this review, we provide an overview of the mechanisms that are linked to the regulation of PRR signaling mediated by HBX to inhibit innate immunity, regulation of viral propagation, virus-induced inflammation, and hepatocarcinogenesis. Given the importance of PRRs in the control of HBV replication, we propose that a comprehensive understanding of the modulation of cellular factors involved in PRR signaling induced by the viral protein may open new avenues for the treatment of HBV infection.

Melatonin alleviates lipopolysaccharide (LPS) / adenosine triphosphate (ATP)-induced pyroptosis in rat alveolar Type II cells (RLE-6TN) through nuclear factor erythroid 2-related factor 2 (Nrf2)-driven reactive oxygen species (ROS) downregulation

Pyroptosis has pivotal parts within disease development, rendering this attractive mechanism for novel therapeutics. This investigation aimed at analyzing melatonin roles within pyroptosis together with related mechanistics. RLE-6TN cultures were exposed to varying LPS doses for 4.5 h followed by concomitant culturing in the presence of ATP (5 mM) for 0.5 h to induce injury, and the roles of melatonin, N-Acety-L-cysteine (NAC - a ROS scavenger), ML385 (specific Nrf2 inhibitor) were examined. Apoptosis analysis was performed through lactate dehydrogenase (LDH) activity assays, together with propidium iodide (PI) stain-assay. Intracellular ROS were quantified through 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA). Pyrolysis-associated proteins, such as nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), cysteine aspartate-specific protease-1 P20 (Caspase-1 P20), gasdermin D-N (GSDMD-N), and mature interleukin-1β (IL-1β), were identified through Western blotting. Dataset outcomes demonstrated LPS/ATP induce RLE-6TN cell pyroptosis, while melatonin alleviated this phenomenon, visualized through increased cell survival rate, reduction of LDH discharge and PI⁺ cellular count. Moreover, melatonin effectively reduced NLRP3 inflammasome triggering in RLE-6TN cells. Meanwhile, this study demonstrated melatonin thwarting over NLRP3 inflammasome triggering was depending on ROS. In addition, this study found that melatonin activated Nrf2/Heme Oxygenase-1 (HO-1) pathway, with pyroptotic-inhibiting function of melatonin was reverted through a bespoke Nrf2-inhibitor and siNrf2. In summary, this study concluded that melatonin prevents RLE-6TN cellular pyroptosis through Nrf2-triggered ROS downregulation.

Programmed cell death and liver diseases

Cell death represents the most critical pathologic entity in liver disease, which dictates pathologic consequences such as inflammation, fibrosis, and cell transformation. We analyzed the conclusions of studies on the involvement of different types of programmed cell death (PCD) in the pathogenesis of liver diseases. Three main forms of PCD (autophagy, apoptosis, necrosis) and five additional, still insufficiently studied PCD – necroptosis, ferroptosis, pyroptosis, partanatosis and entosis – observed in the liver in various acute and chronic diseases are considered. The involvement of several PCD at once in the development of any one pathology and one type of PCD in different pathologies was established. This indicates the existence of cross-regulation of metabolism in the liver cells with different levels of damage in the formation of the main dominant type of PCD. Available results indicate the possibility of attenuation (correction) of functional and morphological manifestations of PCD in the organ by controlled blocking of effector-mediated PCD pathways, as well as targeted induction of autophagy, anti-apoptotic and anti-necrotic mechanisms in liver cells.

Non-Alcoholic Fatty Liver Disease in HIV/HBV Patients - a Metabolic Imbalance Aggravated by Antiretroviral Therapy and Perpetuated by the Hepatokine/Adipokine Axis Breakdown

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome and is one of the most prevalent comorbidities in HIV and HBV infected patients. HIV plays an early and direct role in the development of metabolic syndrome by disrupting the mechanism of adipogenesis and synthesis of adipokines. Adipokines, molecules that regulate the lipid metabolism, also contribute to the progression of NAFLD either directly or via hepatic organokines (hepatokines). Most hepatokines play a direct role in lipid homeostasis and liver inflammation but their role in the evolution of NAFLD is not well defined. The role of HBV in the pathogenesis of NAFLD is controversial. HBV has been previously associated with a decreased level of triglycerides and with a protective role against the development of steatosis and metabolic syndrome. At the same time HBV displays a high fibrogenetic and oncogenetic potential. In the HIV/HBV co-infection, the metabolic changes are initiated by mitochondrial dysfunction as well as by the fatty overload of the liver, two interconnected mechanisms. The evolution of NAFLD is further perpetuated by the inflammatory response to these viral agents and by the variable toxicity of the antiretroviral therapy. The current article discusses the pathogenic changes and the contribution of the hepatokine/adipokine axis in the development of NAFLD as well as the implications of HIV and HBV infection in the breakdown of the hepatokine/adipokine axis and NAFLD progression.

STING signaling activation inhibits HBV replication and attenuates the severity of liver injury and HBV-induced fibrosis

The covalently closed circular DNA (cccDNA) of HBV plays a crucial role in viral persistence and is also a risk factor for developing HBV-induced diseases, including liver fibrosis. Stimulator of interferon genes (STING), a master regulator of DNA-mediated innate immune activation, is a potential therapeutic target for viral infection and virus-related diseases. In this study, agonist-induced STING signaling activation in macrophages was revealed to inhibit cccDNA-mediated transcription and HBV replication via epigenetic modification in hepatocytes. Notably, STING activation could efficiently attenuate the severity of liver injury and fibrosis in a chronic recombinant cccDNA (rcccDNA) mouse model, which is a proven suitable research platform for HBV-induced fibrosis. Mechanistically, STING-activated autophagic flux could suppress macrophage inflammasome activation, leading to the amelioration of liver injury and HBV-induced fibrosis. Overall, the activation of STING signaling could inhibit HBV replication through epigenetic suppression of cccDNA and alleviate HBV-induced liver fibrosis through the suppression of macrophage inflammasome activation by activating autophagic flux in a chronic HBV mouse model. This study suggests that targeting the STING signaling pathway may be an important therapeutic strategy to protect against persistent HBV replication and HBV-induced fibrosis.

Cytokines and Chemokines in HBV Infection

Chronic hepatitis B virus (HBV) infection remains a leading cause of hepatic inflammation and damage. The pathogenesis of chronic hepatitis B (CHB) infection is predominantly mediated by persistent intrahepatic immunopathology. With the characterization of unique anatomical and immunological structure, the liver is also deemed an immunological organ, which gives rise to massive cytokines and chemokines under pathogenesis conditions, having significant implications for the progression of HBV infection. The intrahepatic innate immune system is responsible for the formidable source of cytokines and chemokines, with the latter also derived from hepatic parenchymal cells. In addition, systemic cytokines and chemokines are disturbed along with the disease course. Since HBV is a stealth virus, persistent exposure to HBV-related antigens confers to immune exhaustion, whereby regulatory cells are recruited by intrahepatic chemokines and cytokines, including interleukin-10 and transforming growth factor β, are involved in such series of causal events. Although the considerable value of two types of available approved treatment, interferons and nucleos(t)ide analogues, effectively suppress HBV replication, neither of them is sufficient for optimal restoration of the immunological attrition state to win the battle of the functional or virological cure of CHB infection. Notably, cytokines and chemokines play a crucial role in regulating the immune response. They exert effects by directly acting on HBV or indirectly manipulating target immune cells. As such, specific cytokines and chemokines, with a potential possibility to serve as novel immunological interventions, combined with those that target the virus itself, seem to be promising prospects in curative CHB infection. Here, we systematically review the recent literature that elucidates cytokine and chemokine-mediated pathogenesis and immune exhaustion of HBV infection and their dynamics triggered by current mainstream anti-HBV therapy. The predictive value of disease progression or control and the immunotherapies target of specific major cytokines and chemokines in CHB infection will also be delineated.

Prototheca spp. induce an inflammatory response via mtROS-mediated activation of NF-κB and NLRP3 inflammasome pathways in bovine mammary epithelial cell cultures

Emergence of bovine mastitis caused by Prototheca algae is the impetus to better understand these infections. Both P. bovis and P. ciferrii belong to Prototheca algae, but they differ in their pathogenicity to induce inflammatory responses. The objective was to characterize and compare pathogenesis of inflammatory responses in bMECs induced by P. bovis versus P. ciferrii. Mitochondrial ultrastructure, activity and mtROS in bMECs were assessed with transmission electron microscopy and laser scanning confocal microscopy. Cytokines, including TNF-α, IL-1β and IL-18, were measured by ELISA and real-time PCR, whereas expressions of various proteins in the NF-κB and NLRP3 inflammasome pathways were detected with immunofluorescence or Western blot. Infection with P. bovis or P. ciferrii damaged mitochondria, including dissolution and vacuolation of cristae, and decreased mitochondrial activity, with P. bovis being more pathogenic and causing greater destruction. There were increases in NADPH production and mtROS accumulation in infected bMECs, with P. bovis causing greater increases and also inducing higher cytokine concentrations. Expressions of NF-κB-p65, p-NF-κB-p65, IκBα and p-IκBα proteins in the NF-κB pathway, as well as NLRP3, Pro Caspase1, Caspase1 p20, ASC, Pro IL-1β, and IL-1β proteins in the NLRP3 inflammasome pathway, were significantly higher in P. bovis-infected bMECs. However, mito-TEMPO significantly inhibited production of cytokines and decreased expression of proteins in NF-κB and NLRP3 inflammasome pathways in bMECs infected with either P. bovis or P. ciferrii. In conclusion, P. bovis or P. ciferrii infections induced inflammatory responses in bMECs, with increased mtROS in damaged mitochondria and activated NF-κB and NLRP3 inflammasome pathways, with P. bovis causing a more severe reaction.

Sodium P-aminosalicylic Acid Attenuates Manganese-Induced Neuroinflammation in BV2 Microglia by Modulating NF-κB Pathway

Exposure to high levels of manganese (Mn) leads to brain Mn accumulation, and a disease referred to as manganism. Activation of microglia plays an important role in Mn-induced neuroinflammation. Sodium p-aminosalicylic acid (PAS-Na) is a non-steroidal anti-inflammatory drug that inhibits Mn-induced neuroinflammation. The aim of the current study was to explore the role of NF-κB in the protective mechanism of PAS-Na on Mn-induced neuroinflammation in BV2 microglial experimental model. We treated BV2 microglia with 200 μM Mn for 24 h followed by 48 h treatment with graded concentrations of PAS-Na, using an NF-kB inhibitor, JSH-23, as a positive control. MTT results established that 200 and 400 μM PAS-Na treatment increased the Mn-induced cell viability reduction. NF-κB (P65) mRNA expression and the phosphorylation of p65 were increased in Mn-treated BV2 cell, and suppressed by PAS-Na, analogous to the effect of JSH-23 pretreatment. Furthermore, PAS-Na significantly reduced the contents of the inflammatory cytokine TNF-α and IL-1β, both of which were increased by Mn treatment. The current results show that PAS-Na attenuated Mn-induced inflammation by abrogating the activation of the NF-κB signaling pathways and reduced the release of pro-inflammatory cytokines.

Host Innate Immunity Against Hepatitis Viruses and Viral Immune Evasion

Hepatitis viruses are primary causative agents of hepatitis and represent a major source of public health problems in the world. The host innate immune system forms the first line of defense against hepatitis viruses. Hepatitis viruses are sensed by specific pathogen recognition receptors (PRRs) that subsequently trigger the innate immune response and interferon (IFN) production. However, hepatitis viruses evade host immune surveillance via multiple strategies, which help compromise the innate immune response and create a favorable environment for viral replication. Therefore, this article reviews published findings regarding host innate immune sensing and response against hepatitis viruses. Furthermore, we also focus on how hepatitis viruses abrogate the antiviral effects of the host innate immune system.

Isoliquiritigenin alleviates P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting NF-κB/ NLRP3/GSDMD signals in human gingival fibroblasts

OBJECTIVE

To investigate whether pyroptosis is induced by Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS)/ adenosine triphosphate (ATP) through NF-κB/NLRP3/GSDMD signaling in human gingival fibroblasts (HGFs) and whether isoliquiritigenin (ISL) alleviates pyroptosis by inhibition of NF-κB/NLRP3/GSDMD signals.

DESIGN

Periodontitis was optimally simulated using a combination of P. gingivalis-LPS and ATP. The expression levels of genes and proteins of NF-κB, NLRP3 inflammasome, GSDMD, and IL-1β was characterized by qRT-PCR, western blotting and ELISA. The 2',7'‑dichlorodihydrofluorescein diacetate fluorescence probe was used to determine the intracellular ROS level. Hoechst 33342 and PI double staining, cytotoxicity assay, and caspase-1 activity assay were used to confirm the influence of ISL on pyroptosis in P. gingivalis-LPS/ATP-treated HGFs.

RESULTS

P. gingivalis-LPS/ATP stimulation significantly promoted expression of NF-κB, the NLRP3 inflammasome, GSDMD, and IL-1β at gene and protein levels. The proportion of membrane-damaged cells, caspase-1 activity, and the release of lactate dehydrogenase (LDH) were also elevated. However, pretreatment with ISL observably suppressed these effects.

CONCLUSIONS

P. gingivalis-LPS/ATP induced pyroptosis in HGFs by activating NF-κB/NLRP3/GSDMD signals and ISL attenuated P. gingivalis-LPS/ATP-induced pyroptosis by inhibiting these signals. This evidence may provide a new direction for the treatment of periodontitis.

Dihydrotanshinone I Specifically Inhibits NLRP3 Inflammasome Activation and Protects Against Septic Shock In Vivo

The abnormal activation of the NLRP3 inflammasome is closely related to the occurrence and development of many inflammatory diseases. Targeting the NLRP3 inflammasome has been considered an efficient therapy to treat infections. We found that dihydrotanshinone I (DHT) specifically blocked the canonical and non-canonical activation of the NLRP3 inflammasome. Nevertheless, DHT had no relation with the activation of AIM2 or the NLRC4 inflammasome. Further study demonstrated that DHT had no influences on potassium efflux, calcium flux, or the production of mitochondrial ROS. We also discovered that DHT suppressed ASC oligomerization induced by NLRP3 agonists, suggesting that DHT inhibited the assembly of the NLRP3 inflammasome. Importantly, DHT possessed a significant therapeutic effect on NLRP3 inflammasome–mediated sepsis in mice. Therefore, our results aimed to clarify DHT as a specific small-molecule inhibitor for the NLRP3 inflammasome and suggested that DHT can be used as a potential drug against NLRP3-mediated diseases.

Bisdemethoxycurcumin attenuates lipopolysaccharide-induced intestinal damage through improving barrier integrity, suppressing inflammation, and modulating gut microbiota in broilers

Bisdemethoxycurcumin has good antioxidant and anti-inflammatory effects and has been widely used as food and feed supplements in the form of curcuminoids. However, the beneficial effect of individual bisdemethoxycurcumin on preventing lipopolysaccharide (LPS)-induced inflamed intestinal damage is unclear. The present study aimed to investigate whether dietary bisdemethoxycurcumin supplementation could attenuate LPS-induced intestinal damage and alteration of cecal microbiota in broiler chickens. In total, 320 one-day-old male Arbor Acres broiler chickens with a similar weight were randomly divided into four treatments. The treatments were designed as a 2 × 2 factorial arrangement: basal diet (CON); 150 mg/kg bisdemethoxycurcumin diet (BUR); LPS challenge + basal diet (LPS); LPS challenge + 150 mg/kg bisdemethoxycurcumin diet (L-BUR). Results showed that dietary bisdemethoxycurcumin supplementation attenuated the LPS-induced decrease of average daily feed intake. LPS challenge compromised the intestinal morphology and disrupted the intestinal tight junction barrier. Dietary bisdemethoxycurcumin supplementation significantly increased villus length:crypt depth ratio and upregulated the mRNA expression of intestinal tight junction proteins. Moreover, a remarkably reduced mRNA expression of inflammatory mediators was observed following bisdemethoxycurcumin supplementation. The cecal microbiota analysis showed that bisdemethoxycurcumin supplementation increased the relative abundance of the genus Faecalibacterium while decreased the relative abundance of the genera Bacteroides and Subdoligranulum. In conclusion, dietary bisdemethoxycurcumin supplementation could counteract LPS-induced inflamed intestinal damage in broiler chickens by improving intestinal morphology, maintaining intestinal tight junction, downregulating pro-inflammatory mediators, and restoring cecal microbiota.

Dietary fiber-derived short-chain fatty acids: A potential therapeutic target to alleviate obesity-related nonalcoholic fatty liver disease

Over the past several decades, increasing global prevalence of obesity-related nonalcoholic fatty liver disease (NAFLD) has been one of main challenges to human health. Recently, increasing evidence has validated connections among short chain fatty acids (SCFAs), a physiologically relevant concentration, the intestinal microbiota, and host metabolism. In this review, we summarized crosstalk between SCFAs and host metabolism in relation to NAFLD pathophysiology, focusing on recent advances. Firstly, how SCFAs are generated and absorbed under different nutritional conditions in the gut. Secondly, how SCFAs maintain gut barrier and alleviate hepatic inflammatory responses. Thirdly, how SCFAs maintain hepatic energy balance through controlling appetite and mediating the glucose homeostasis at the systemic level. Fourthly, G-protein-coupled receptors (GPRs) are widely involved in the above metabolic processes regulated by SCFAs. Overall, this review aimed to provide new insights into the prospects of SCFAs as a potential therapeutic target in management of liver diseases.

DNA Damage-Induced Inflammatory Microenvironment and Adult Stem Cell Response

Adult stem cells ensure tissue homeostasis and regeneration after injury. Due to their longevity and functional requirements, throughout their life stem cells are subject to a significant amount of DNA damage. Genotoxic stress has recently been shown to trigger a cascade of cell- and non-cell autonomous inflammatory signaling pathways, leading to the release of pro-inflammatory factors and an increase in the amount of infiltrating immune cells. In this review, we discuss recent evidence of how DNA damage by affecting the microenvironment of stem cells present in adult tissues and neoplasms can affect their maintenance and long-term function. We first focus on the importance of self-DNA sensing in immunity activation, inflammation and secretion of pro-inflammatory factors mediated by activation of the cGAS-STING pathway, the ZBP1 pathogen sensor, the AIM2 and NLRP3 inflammasomes. Alongside cytosolic DNA, the emerging roles of cytosolic double-stranded RNA and mitochondrial DNA are discussed. The DNA damage response can also initiate mechanisms to limit division of damaged stem/progenitor cells by inducing a permanent state of cell cycle arrest, known as senescence. Persistent DNA damage triggers senescent cells to secrete senescence-associated secretory phenotype (SASP) factors, which can act as strong immune modulators. Altogether these DNA damage-mediated immunomodulatory responses have been shown to affect the homeostasis of tissue-specific stem cells leading to degenerative conditions. Conversely, the release of specific cytokines can also positively impact tissue-specific stem cell plasticity and regeneration in addition to enhancing the activity of cancer stem cells thereby driving tumor progression. Further mechanistic understanding of the DNA damage-induced immunomodulatory response on the stem cell microenvironment might shed light on age-related diseases and cancer, and potentially inform novel treatment strategies.

Interplay Between Non-Canonical NF-κB Signaling and Hepatitis B Virus Infection

The non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway is an important component of NF-κB transcription complex. Activation of this pathway mediates the development and function of host immune system involved in inflammation and viral infection. During hepatitis B virus (HBV) infection, there is a complex interaction between infected hepatocytes and the immune cells, which can hinder antiviral immune responses and is associated with pathological changes in liver tissue. Consistently, the host immune system is closely related to the severity of liver damage and the level of viral replication. Previous studies indicated that the non-canonical NF-κB signaling pathway was affected by HBV and might play an important regulatory role in the antiviral immunity. Therefore, systematically elucidating the interplay between HBV and non-canonical NF-κB signaling will contribute the discovery of more potential therapeutic targets and novel drugs to treat HBV infection.

Heparin alleviates LPS-induced endothelial injury by regulating the TLR4/MyD88 signaling pathway

Heparin is a commonly used in the clinic, however, Heparin's effect on endothelial injury remains unclear. The aim of the present study was to evaluate the effects and possible mechanisms of action underlying heparin treatment in lipopolysaccharide (LPS)-induced endothelial injury in vitro. TNF-α, IL-1β, IL-6 and IFN-γ levels were measured using ELISA. Cell proliferation was measured using a 5-ethynyl-2'-deoxyuridine (EdU) assay. The number of apoptotic cells and apoptotic rate were evaluated using TUNEL assays and flow cytometry, respectively. Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88) and NF-κB (p65) gene expression was evaluated using reverse transcription-quantitative PCR, whilst TLR4, MyD88 and p-NF-κB (p65) protein expression was evaluated using western blot analysis. The levels of phosphorylated NF-κB in the nucleus were evaluated using cellular immunofluorescence. Compared with those in the normal control group, TNF-α, IL-1β, IL-6 and IFN-γ levels were significantly increased in the LPS group (P<0.001). In addition, 5-ethynyl-2'-deoxyuridine (EdU)-positive cells were significantly increased and apoptosis was significantly decreased (P<0.001). TLR4, MyD88 and NF-κB (p65) expression was also significantly increased (P<0.001). Compared with those in the LPS group, following heparin treatment, TNF-α, IL-1β, IL-6 and IFN-γ levels were significantly decreased (P<0.05), whilst the number of EdU-positive cells was significantly increased and the level of apoptosis was significantly decreased (P<0.05). TLR4, MyD88 and NF-κB (p65) expression was also significantly decreased by heparin in a dose-dependent manner (P<0.001). Small interfering RNA-TLR4 transfection exerted similar effects to those mediated by heparin in alleviating endothelial injury. In conclusion, heparin suppressed LPS-induced endothelial injury through the regulation of TLR4/MyD88/NF-κB (p65) signaling in vitro.

Synergistic Protective Effect of Konjac Mannan Oligosaccharides and Bacillus subtilis on Intestinal Epithelial Barrier Dysfunction in Caco-2 Cell Model and Mice Model of Lipopolysaccharide Stimulation

As the first line of defense against intestinal bacteria and toxins, intestinal epithelial cells are always exposed to bacteria or lipopolysaccharide (LPS), whereas pathogenic bacteria or LPS can cause intestinal epithelial cell damage. Previous studies have shown that konjac mannan oligosaccharides (KMOS) have a positive effect on maintaining intestinal integrity, and Bacillus subtilis (BS) can promote the barrier effect of the intestine. However, it is still unknown whether KMOS and BS have a synergistic protective effect on the intestines. In this study, we used the LPS-induced Caco-2 cell injury model and mouse intestinal injury model to study the synergistic effects of KMOS and BS. Compared with KMOS or BS alone, co-treatment with KMOS and BS significantly enhanced the activity and antioxidant capacity of Caco-2 cell, protected mouse liver and ileum from LPS-induced oxidative damage, and repaired tight junction and mucus barrier damage by up-regulating the expression of Claudin-1, ZO-1 and MUC-2. Our results demonstrate that the combination of KMOS and BS has a synergistic repair effect on inflammatory and oxidative damage of Caco-2 cells and aIIeviates LPS-induced acute intestinal injury in mice.

Toll-Like Receptor Response to Hepatitis B Virus Infection and Potential of TLR Agonists as Immunomodulators for Treating Chronic Hepatitis B: An Overview

Chronic hepatitis B virus (HBV) infection remains a major global health problem. The immunopathology of the disease, especially the interplay between HBV and host innate immunity, is poorly understood. Moreover, inconsistent literature on HBV and host innate immunity has led to controversies. However, recently, there has been an increase in the number of studies that have highlighted the link between innate immune responses, including Toll-like receptors (TLRs), and chronic HBV infection. TLRs are the key sensing molecules that detect pathogen-associated molecular patterns and regulate the induction of pro- and anti-inflammatory cytokines, thereby shaping the adaptive immunity. The suppression of TLR response has been reported in patients with chronic hepatitis B (CHB), as well as in other models, including tree shrews, suggesting an association of TLR response in HBV chronicity. Additionally, TLR agonists have been reported to improve the host innate immune response against HBV infection, highlighting the potential of these agonists as immunomodulators for enhancing CHB treatment. In this study, we discuss the current understanding of host innate immune responses during HBV infection, particularly focusing on the TLR response and TLR agonists as immunomodulators.

Pyroptosis in Steatohepatitis and Liver Diseases

Pyroptosis is an inflammatory form of regulated cell death, which functions in the clearance of intracellularly replicating pathogens by cell lysis in order to induce further immune response. Since the discovery of the gasdermin (GSDM) family, pyroptosis has attracted attention in a wide range of inflammatory diseases such as nonalcoholic steatohepatitis and other liver diseases. Due to the cleavage of GSDMs by different caspases, the amino-terminal GSDM fragments form membrane pores essential for pyroptosis that facilitate the release of inflammatory cytokines by loss of ionic gradient and membrane rupture. In this review, we address the key molecular and cellular processes that induce pyroptosis in the liver and its significance in the pathogenesis of common liver diseases in different human and experimental mice studies.

Ginsenoside Rg1 ameliorates aging‑induced liver fibrosis by inhibiting the NOX4/NLRP3 inflammasome in SAMP8 mice

Aging is often accompanied by liver injury and fibrosis, eventually leading to the decline in liver function. However, the mechanism of aging‑induced liver injury and fibrosis is still not fully understood, to the best of our knowledge, and there are currently no effective treatment options available for liver aging. Ginsenoside Rg1 (Rg1) has been reported to exert potent anti‑aging effects due to its potential antioxidant and anti‑inflammatory activity. The present study aimed to investigate the protective effect and underlying mechanism of action of Rg1 in aging‑induced liver injury and fibrosis in senescence‑accelerated mouse prone 8 (SAMP8) mice treated for 9 weeks. The histopathological results showed that the arrangement of hepatocytes was disordered, vacuole‑like degeneration occurred in the majority of cells, and collagen IV and TGF‑β1 expression levels, that were detected via immunohistochemistry, were also significantly upregulated in the SAMP8 group. Rg1 treatment markedly improved aging‑induced liver injury and fibrosis, and significantly downregulated the expression levels of collagen IV and TGF‑β1. In addition, the dihydroethylene staining and western blotting results showed that Rg1 treatment significantly reduced the levels of reactive oxygen species (ROS) and IL‑1β, and downregulated the expression levels of NADPH oxidase 4 (NOX4), p47phox, p22phox, phosphorylated‑NF‑κB, caspase‑1, apoptosis‑associated speck‑like protein containing a C‑terminal caspase recruitment domain and the NLR family pyrin domain containing 3 (NLRP3) inflammasome, which were significantly upregulated in the liver tissues of elderly SAMP8 mice. In conclusion, the findings of the present study suggested that Rg1 may attenuate aging‑induced liver injury and fibrosis by reducing NOX4‑mediated ROS oxidative stress and inhibiting NLRP3 inflammasome activation.

Therapeutic Targeting of Inflammatory Pathways with Emphasis on NLRP3 Inflammasomes by Natural Products: A Novel Approach for the Treatment of Inflammatory Eye Diseases

There is an increase in the incidence of inflammatory eye diseases worldwide. Several dysregulated inflammatory pathways, including the NOD-like receptor protein 3 (NLRP3) inflammasome, have been reported to contribute significantly to the pathogenesis and progression of ophthalmic diseases. Although the available allopathic/conventional medicine has demonstrated effectiveness in managing eye diseases, there is an ongoing global demand for alternative therapeutics with minimal adverse drug reactions, easy availability, increase in patient-compliance, and better disease outcome. Therefore, several studies are investigating the utilization of natural products and herbal formulations in impeding inflammatory pathways, including the NLRP3 inflammasome, in order to prevent or manage eye diseases. In the present review, we highlight the recently reported inflammatory pathways with special emphasis on NLRP3 Inflammasomes involved in the development of eye diseases. Furthermore, we present a variety of natural products and phytochemicals that were reported to interfere with these pathways and their underlying mechanisms of action. These natural products represent potential therapeutic applications for the treatment of several inflammatory eye diseases.

Chronic liver disease and oxidative stress - a narrative review

Introduction: Oxidative stress underlies the pathophysiology of various etiologies of chronic liver disease and contributes to the development of hepatocarcinogenesis.Areas covered: This review focuses on the impact of oxidative stress in various etiologies of chronic liver disease such as alcoholic liver disease (ALD), nonalcoholic steatohepatitis (NASH), hepatitis B virus (HBV), and hepatitis C virus (HCV) infection. The efficacy of antioxidants in laboratory, animal, and clinical studies in chronic liver disease is also reviewed.Expert opinion: Currently, there are limited targeted pharmacotherapeutics for NASH and no pharmacotherapeutics for ALD and antioxidant supplementation may be useful in these conditions to improve liver function and reverse fibrosis. Antioxidants may also be used in patients with HBV or HCV infection to supplement antiviral therapies. Specific genotypes of antioxidant and prooxidant genes render patients more susceptible to liver cirrhosis and hepatocellular carcinoma while other individual characteristics like age, genotype, and metabolomic profiling can influence the efficacy of antioxidants on CLD. More research needs to be done to establish the safety, efficacy, and dosage of antioxidants and to establish the ideal patient profile that will benefit the most from antioxidant treatment.

The Functions of Hepatitis B Virus Encoding Proteins: Viral Persistence and Liver Pathogenesis

About 250 million people worldwide are chronically infected with Hepatitis B virus (HBV), contributing to a large burden on public health. Despite the existence of vaccines and antiviral drugs to prevent infection and suppress viral replication respectively, chronic hepatitis B (CHB) cure remains a remote treatment goal. The viral persistence caused by HBV is account for the chronic infection which increases the risk for developing liver cirrhosis and hepatocellular carcinoma (HCC). HBV virion utilizes various strategies to escape surveillance of host immune system therefore enhancing its replication, while the precise mechanisms involved remain elusive. Accumulating evidence suggests that the proteins encoded by HBV (hepatitis B surface antigen, hepatitis B core antigen, hepatitis B envelope antigen, HBx and polymerase) play an important role in viral persistence and liver pathogenesis. This review summarizes the major findings in functions of HBV encoding proteins, illustrating how these proteins affect hepatocytes and the immune system, which may open new venues for CHB therapies.

Gut microbiota in the innate immunity against hepatitis B virus - implication in age-dependent HBV clearance

Hepatitis B virus (HBV) chronically infects 257 million people and is one of the most important liver diseases worldwide. A unique feature of HBV infection in humans is that viral clearance heavily depends on the age at exposure. Recent studies demonstrated that the virus takes advantage of immature innate immunity, especially hepatic macrophages, and not-yet-stabilized gut microbiota in early life to establish a chronic infection. The liver contains resident and infiltrating myeloid cells involved in immune responses to pathogens. They influence both innate and adaptive sectors of the immune system and their interplay with HBV has only been noticed recently. Here, we discuss how interactions between gut microbiota and hepatic macrophages influence the outcomes of HBV infection. Understanding the underlying mechanism would pave the way for the treatment of chronic HBV infection.

Medioresinol as a novel PGC-1α activator prevents pyroptosis of endothelial cells in ischemic stroke through PPARα-GOT1 axis

AIM

Brain microvascular endothelial cells (BMVECs), as the important structure of blood-brain barrier (BBB), play a vital role in ischemic stroke. Pyroptosis of different cells in the brain may aggravate cerebral ischemic injury, and PGC-1α plays a major role in pyroptosis. However, it is not known whether BMVECs undergo pyroptosis after ischemic stroke and whether PGC-1α activator Medioresinol (MDN) we discovered may be useful against pyroptosis of endothelial cells and ischemic brain injury.

METHODS

For in vitro experiments, the bEnd.3 cells and BMVECs under oxygen and glucose-deprivation (OGD) were treated with or without MDN, and the LDH release, tight junction protein degradation, GSDMD-NT membrane location and pyroptosis-associated proteins were evaluated. For in vivo experiments, mice underwent transient middle cerebral artery occlusion (tMCAO) for ischemia model, and the neuroprotective effects of MDN were measured by infarct volume, the permeability of BBB and pyroptosis of BMVECs. For mechanistic study, effects of MDN on the accumulation of phenylalanine, mitochondrial reactive oxygen species (mtROS) were tested by untargeted metabolomics and MitoSOX Red probe, respectively.

RESULTS

BMVECs underwent pyroptosis after ischemia. MDN dose-dependently activated PGC-1α, significantly reduced pyroptosis, mtROS and the expressions of pyroptosis-associated proteins (NLRP3, ASC, cleaved caspase-1, IL-1β, GSDMD-NT), and increased ZO-1 and Occludin protein expressions in BMVECs. In tMCAO mice, MDN remarkably reduced brain infarct volume and the permeability of BBB, inhibited pyroptosis of BMVECs, and promoted long-term neurobehavioral functional recovery. Mechanistically, MDN promoted the interaction of PGC-1α with PPARα to increase PPARα nuclear translocation and transcription activity, further increased the expression of GOT1 and PAH, resulting in enhanced phenylalanine metabolism to reduce the ischemia-caused phenylalanine accumulation and mtROS and further ameliorate pyroptosis of BMVECs.

CONCLUSION

In this study, we for the first time discovered that pyroptosis of BMVECs was involved in the pathogenesis of ischemic stroke and MDN as a novel PGC-1α activator could ameliorate the pyroptosis of endothelial cells and ischemic brain injury, which might attribute to reduction of mtROS through PPARα/GOT1 axis in BMVECs. Taken together, targeting endothelial pyroptosis by MDN may provide alternative therapeutics for brain ischemic stroke.

The Mechanisms of HBV-Induced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy, and the hepatitis B virus (HBV) is its major pathogenic factor. Over the past decades, it has been confirmed that HBV infection could promote disease progression through a variety of mechanisms, ultimately leading to the malignant transformation of liver cells. Many factors have been identified in the pathogenesis of HBV-associated HCC (HBV-HCC), including HBV gene integration, genomic instability caused by mutation, and activation of cancer-promoting signaling pathways. As research in the progression of HBV-HCC progresses, the role of many new mechanisms, such as epigenetics, exosomes, autophagy, metabolic regulation, and immune suppression, is also being continuously explored. The occurrence of HBV-HCC is a complex process caused by interactions across multiple genes and multiple steps, where the synergistic effects of various cancer-promoting mechanisms accelerate the process of disease evolution from inflammation to tumorigenesis. In this review, we aim to provide a brief overview of the mechanisms involved in the occurrence and development of HBV-HCC, which may contribute to a better understanding of the role of HBV in the occurrence and development of HCC.

Tripartite-motif protein 21 knockdown extenuates LPS-triggered neurotoxicity by inhibiting microglial M1 polarization via suppressing NF-κB-mediated NLRP3 inflammasome activation

Tripartite motif-containing 21 (TRIM21) has been confirmed to mediate the production of inflammatory mediators via NF-κB signaling. However, the function of TRIM21 in microglia-mediated neuroinflammation remains unclear. This study aimed to explore the effect of TRIM21 on LPS-activated BV2 microglia and its underlying mechanism. BV2 cells exposed to lipopolysaccharide (LPS) were used to simulated neuroinflammation in vitro. Loss-of-function and gain-of-function of TRIM21 in BV2 cells were used to assess the effect of TRIM21 on LPS-induced neuroinflammation. BV2 microglia and HT22 cells co-culture system were used to investigate whether TRIM21 regulated neuronal inflammation-mediated neuronal death. TRIM21 knockdown triggered the polarization of BV2 cells from M1 to M2 phenotype. Knockdown of TRIM21 reduced the secretion of TNF-α, IL-6, and IL-1β, while increased the content of IL-4 in LPS-treated cells. Knockdown of TRIM21 inhibited the expression of p65 and the binding activity of NF-κB-DNA. Additionally, TRIM21 siRNA eliminated the increase in NLRP3 and cleaved caspase-1 proteins expression and caspase-1 activity induced by LPS. TRIM21 knockdown could resist cytotoxicity induced by activated microglia, including increasing the viability of co-cultured HT22 cells and reducing the emancipation of LDH. Moreover, the increased apoptosis and caspase-3 activity of HT22 neurons induced by activated BV2 cells were blocked by TRIM21 siRNA. Blocking of NF-κB abolished the effect of TRIM21 in promoting the expression of M1 phenotype marker genes. Similarly, the blockade of NF-κB pathway eliminated the promotion of TRIM21 on neurotoxicity induced by neuroinflammation. TRIM21 knockdown suppressed the M1 phenotype polarization of microglia and neuroinflammation-mediated neuronal damage via NF-κB/NLRP3 inflammasome pathway, which suggested that TRIM21 might be a potential therapeutic target for the therapy of central nervous system diseases.

Emodin Alleviates Severe Acute Pancreatitis-Associated Acute Lung Injury by Inhibiting the Cold-Inducible RNA-Binding Protein (CIRP)-Mediated Activation of the NLRP3/IL-1β/CXCL1 Signaling

Objective: Severe acute pancreatitis (SAP) can lead to acute lung injury (ALI). This study investigated the therapeutic effect of emodin and its molecular mechanisms in a rat model of SAP-ALI.

Methods: Forty male Sprague-Dawley rats were randomly divided into the groups: Control (CON), SAP (SAP), emodin (EMO), and C23 (C23). The latter three groups of rats were induced for SAP-ALI by retrograde injection of 5% sodium taurocholate into the biliary-pancreatic duct and were treated with vehicle, emodin or C23, respectively. One day post induction, their pancreatic and lung injury was assessed by histology and arterial blood gas analysis. In vitro, rat alveolar macrophages (NR8383 cells) were treated with recombinant rat CIRP in the presence or absence of TAK242 (a TLR4 inhibitor), C23 or emodin. The CIRP-mediated activation of the NLRP3/IL-1β/CXCL1 signaling in rat lungs and NR8383 cells was determined. Similarly, the role of IL-1β in the CIRP-induced CXCL1 expression was investigated.

Results: Emodin treatment significantly reduced inflammation and tissue damages in the pancreatic and lung tissues in rats with SAP-ALI, accompanied by decreasing serum amylase, CIRP and IL-1β levels and improving lung function. Furthermore, emodin significantly mitigated the SAP-up-regulated CIRP expression in the pancreatic islets and lung tissues, and attenuated the SAP-activated NF-κB signaling, NLRP3 inflammasome formation and CXCL1 expression in lung resident macrophages as well as neutrophil infiltration in the lungs of rats. In addition, treatment with CIRP significantly activated the NF-κB signaling and NLRP3 inflammasome formation and induced IL-1β and CXCL1 expression and pyroptosis in NR8383 cells, which were abrogated by TAK242 and significantly mitigated by C23 or emodin. Moreover, CIRP only induced very lower levels of CXCL1 expression in IL-1β-silencing NR8383 cells and treatment with IL-1β induced CXCL1 expression in NR8383 cells in a dose and time-dependent manner.

Conclusion: Emodin may inhibit the CIRP-activated NLRP3/IL-1β/CXCL1signaling to decrease neutrophil infiltration and ameliorate the SAP-ALI in rats.

Isomer-Specific Effects of cis-9,trans-11- and trans-10,cis-12-CLA on Immune Regulation in Ruminal Epithelial Cells

Simple Summary

The significant contribution of rumen microbiota to the balance of the innate immunity of rumen epithelium has been extensively verified. As the natural rumen microbial metabolites, information regarding the immunoprotective effects of different conjugated linoleic acid (CLA) isomers on ruminal epithelial cells (RECs) is limited. In this study, the 100 μM trans-10,cis-12-CLA exerted better anti-inflammatory effects than the cis-9,trans-11-CLA by significantly downregulating the expression of genes related to inflammation, cell proliferation and migration in RECs upon lipopolysaccharide (LPS) stimulation. The trans-10,cis-12-CLA, but not cis-9,trans-11-CLA, significantly suppressed the biological signals of gene ontology (GO) terms’ response to lipopolysaccharide, the regulation of signal transduction and cytokine production and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways NF-κB, chemokine, NOD-like receptor, Hippo, PI3K-Akt, TGF-β and Rap1 signaling in RECs upon LPS stimulation. Furthermore, pretreatment with trans-10,cis-12-CLA significantly reduced the expression of lipogenic genes and the biosynthesis of the unsaturated fatty acid pathway in RECs compared with the LPS group, however, cis-9,trans-11-CLA exhibited the opposite results. These results suggest the distinct isomer differences of CLA in the regulation of inflammatory responses and adipocytokine signaling in RECs and will provide important references for determining their target use in the future.

Abstract

In this study, we used transcriptomics and qPCR to investigate the potential immunoprotective effects of different conjugated linoleic acid (CLA) isomers, the natural rumen microbial metabolites, on lipopolysaccharide (LPS)-induced inflammation of ruminal epithelial cells (RECs) in vitro. The results showed that 100 μM trans-10,cis-12-CLA exerted higher anti-inflammatory effects than cis-9,trans-11-CLA by significantly downregulating the expression of genes related to inflammation, cell proliferation and migration in RECs upon LPS stimulation. Transcriptomic analyses further indicated that pretreatment with trans-10,cis-12-CLA, but not cis-9,trans-11-CLA, significantly suppressed the biological signals of GO terms’ response to LPS, the regulation of signal transduction and cytokine production and KEGG pathways NF-κB, chemokine, NOD-like receptor, Hippo, PI3K-Akt, TGF-β and Rap1 signaling in RECs upon LPS stimulation. Furthermore, pretreatment with trans-10,cis-12-CLA significantly reduced the expression of lipogenic genes and the biosynthesis of the unsaturated fatty acid pathway in RECs compared with the LPS group, however, cis-9,trans-11-CLA exhibited the opposite results. These results suggest the distinct isomer differences of CLA in the regulation of inflammatory responses and adipocytokine signaling in RECs and will provide important references for determining their target use in the future.

MiR-520b inhibits endothelial activation by targeting NF-κB p65-VCAM1 axis

MiR-520b belongs to the miR-373/520 family, is expressed only in human and nonhuman primates. Previous reports indicated that the expression of miR-520b was repressed in human atherosclerotic plaque tissue compared with healthy vessels. However, the role of miR-520b in coronary artery disease still remains to be uncovered. In this study, we demonstrated that endothelial cells (ECs) in human atherosclerotic plaques expressed miR-520b and aimed to elucidate the impact of miR-520b on EC activation and inflammatory response. To determine the potential targets of miR-520b, we performed RNA-seq analysis by transfecting miR-520b mimics in ECs. The quantitative real-time PCR (qPCR) validation suggested that miR-520b over-expression reduced pro-inflammatory gene expression (e.g. ICAM1, VCAM1, SELE) while the inhibition of miR-520b induced their expression. By combining bioinformatics prediction and functional assays, we identified that RELA (Nuclear Factor-κB (NF-κB) Transcription Factor P65) was a direct target of miR-520b. Moreover, miR-520b mimics attenuated monocyte adhesion and monocyte trans-endothelial migration (the initial steps of atherosclerotic formation) in response to lipopolysaccharides (LPS) stimulation. Re-expression of a non-miR-targetable version of p65 could rescue the reduced monocyte cell attachment, suggesting that this process is NF-κB p65 dependent. MiR-520b reduced the abundance of NF-κB p65 in cytoplasmic fractions without corresponding increase in nuclear fractions, indicating that this regulation is independent of p65 translocation process. MiR-520b mimics attenuated the activity of VCAM-1 promoter, whereas miR-520b inhibitor activated its activity. However, miR-520b inhibitor had no effect on promoter activity containing the mutated NF-κB p65 binding sites, strongly demonstrating that the impact of miR-520b on VCAM1 gene is mediated by NF-κB p65. Thus, we concluded that miR-520b suppressed EC inflammation and the cross-talk between monocytes and ECs by down-regulating NF-κB p65-ICAM1/VCAM1 axis and might serve as a potential therapeutic target for EC dysfunction and atherosclerosis.

Baeckein E suppressed NLRP3 inflammasome activation through inhibiting both the priming and assembly procedure: Implications for gout therapy

BACKGROUND

Baeckein E (BF-2) was isolated from the aerial parts of Baeckea frutescens L., which has a long history of use in traditional medicine in Southeast Asia to treat inflammatory disease.

PURPOSE

BF-2 was identified to have inhibitory activity on nucleotide oligomerization domain (NOD)-like receptor protein-3 inflammasome (NLRP3) activation. This study aimed to investigate the related signaling cascade of BF-2 in both lipopolysaccharides (LPS)/ATP induced pyroptosis in J774A.1 macrophages and its application in a mouse model of gout induced by monosodium urate crystal (MSU).

METHODS

The effect of BF-2 on NLRP3 inflammasome activation and gouty arthritis was studied in J774A.1 macrophages and male C57BL/6 mice. The J774A.1 macrophages were primed with LPS and stained by propidium iodide (PI) for cell pyroptosis detection. A gout mouse model was established by subcutaneous injection of MSU crystals into the hind paw of C57BL/6 mice. Mice were then randomly divided into different groups. The concentrations of IL-1β and IL-18 in both J774A.1 macrophage and gout mouse model were analyzed by ELISA. The NLRP3 inflammasome related protein expression was detected by western blot analysis. The inhibitory effects of BF-2 on NLRP3 inflammasome assembly were analyzed by immunoprecipitation assay. The roles of BF-2 in mitochondrial damage were imaged by Mito Tracker Green and Mito Tracker Red probes. The inhibitory effects of BF-2 on ROS production were imaged by DCF (2',7'-dichlorofluorescein diacetate) probe.

RESULTS

The results demonstrated BF-2 could significantly suppress the cell pyroptosis and IL-1β secretion in macrophages. Furthermore, BF-2 significantly inhibited NLRP3 inflammasome activation and reduced ankle swelling in the gout mouse model. In detail, it alleviated mitochondrial damage mediated oxidative stress and inhibited the assembly of NLRP3 inflammasome by affecting the binding of pro-Caspase 1 and ASC. Moreover, BF-2 blocked NLRP3 activation by inhibiting the MAPK/NF-κB signaling pathways.

CONCLUSIONS

Results demonstrated BF-2 inhibited NLRP3 inflammasome activation in both LPS primed macrophages and mouse model of gout through blocking MAPK/NF-κB signaling pathway and mitochondrial damage mediated oxidative stress. This study strongly suggests BF-2 could be a promising drug candidate against inflammatory diseases associated with NLRP3 inflammasome activation.

Biological functions of NLRP3 inflammasome: A therapeutic target in inflammatory bowel disease

Cases of inflammatory bowel disease (IBD), a debilitating intestinal disorder with complex pathological mechanisms, have been increasing in recent years, straining the capacity of healthcare systems. Thus, novel therapeutic targets and innovative agents must be developed. Notably, the NLRP3 inflammasome is upregulated in patients with IBD and/or in animal experimental models. As an innate immune supramolecular assembly, the NLRP3 inflammasome is persistently activated during the pathogenesis of IBD by multiple stimuli. Moreover, this protein complex regulates pro-inflammatory cytokines. Thus, targeting this multiprotein oligomer may offer a feasible way to relieve IBD symptoms and improve clinical outcomes. The mechanisms by which the NLRP3 inflammasome is activated, its role in IBD pathogenesis, and the drugs administered to target this protein complex are reviewed herein. This review establishes that the use of inflammasome-targeting drugs are effective for IBD treatment. Moreover, this review suggests that the value and potential of naturally sourced or derived medicines for IBD treatment must be recognized and appreciated.

Relationships between IL-1β, TNF-α genetic polymorphisms and HBV infection: A meta-analytical study

BACKGROUND

IL-1β and TNF-α have been demonstrated as pro-inflammatory cytokines to participate in the innate immune response and suppression of HBV infection. However, the exact relationship between IL-1β, TNF-α gene polymorphisms and HBV infection remains unknown. Our study aims to assess the associations between IL-1β, TNF-α gene polymorphisms and HBV infection.

METHODS

A systematic literature search of PubMed and Embase databases was conducted through February 2020, and studies that were included in the present meta-analysis should fulfil the following conditions: (1) case-control studies focusing on the associations between IL-1β, TNF-α polymorphisms and HBV infection; (2) patients in the case group should be tested positive for the HBsAg and/or HBV-DNA without liver cirrhosis or hepatocellular carcinoma; (3) the control group including healthy population or HBV spontaneous clearance population; (4) odds ratios (ORs) and their 95% confidence intervals (CIs) could be calculated based on the allele and genotype frequencies provided in articles. The quality of included studies was assessed according to the Newcastle-Ottawa scale (NOS) assessment system. Pooled ORs and 95% CIs were used to analyze the strength of associations. Subgroup analysis was performed according to ethnicity and control type.

RESULTS

In the present meta-analysis, 49 articles including 10,218 cases and 9,557 controls were enrolled and seven polymorphisms (IL-1β rs16944, rs1143634, TNF-α rs1799724, rs1799964, rs1800629, rs1800630, rs361525) were studied. In overall meta-analysis, significant associations were found in IL-1β rs1143634, TNF-α rs1799724 and TNF-α rs1799964. For subgroup analysis under ethnicity, TNF-α rs1799724 and rs1800630 were markedly related to HBV infection in both Asian and Caucasian populations. In terms of control type subgroup, TNF-α rs1799724, rs1799964, rs1800630 were significantly associated with HBV persistence in HBV spontaneous clearance group.

CONCLUSION

In the present study, we identified that three polymorphisms (IL-1β rs1143634, TNF-α rs1799724, rs1799964) might serve as potential genetic biomarkers in HBV infection.

Melatonin alleviates lipopolysaccharide-induced myocardial injury by inhibiting inflammation and pyroptosis in cardiomyocytes

Background

Melatonin (MT) has been shown to protect against various cardiovascular diseases. However, the effect of MT on lipopolysaccharide (LPS)-induced myocardial injury is poorly understood. This study aims to evaluate the effects of MT on LPS-induced myocardial injury in vitro.

Methods

H9C2 cells were divided into a control group, MT group, LPS group, and MT + LPS group. The control group was treated with sterile saline solution, the LPS group received 8 µg/mL LPS for 24 h, MT + LPS cells were pretreated with 200 µmol/L MT for 2 h then with 8 µg/mL LPS for 24 h, and the MT group received only 200 µmol/L MT for 2 h. The CCK-8 assay and lactate dehydrogenase (LDH) activity assay were used to analyze cell viability and LDH release, respectively. Intracellular reactive oxygen species (ROS) and the rate of pyroptosis were measured using the fluorescent probe dichloro-dihydro-fluorescein diacetate (DCFH-DA) and propidium iodide (PI) staining, respectively. The cell supernatants were used to measure the levels of inflammatory cytokines, including IL-6, TNF-α, and IL-1β by enzyme-linked immunosorbent assay (ELISA). The protein levels of iNOS, COX-2, NF-κB, p-NF-κB, NLRP3, caspase-1, and GSDMD were detected by western blot.

Results

MT pretreatment significantly improved LPS-induced myocardial injury by inhibiting inflammation and pyroptosis in H9C2 cells. Moreover, MT inhibited the activation of the NF-κB pathway, and reduced the expression of inflammation-related proteins (iNOS and COX-2), and pyroptosis-related proteins (NLRP3, caspase-1, and GSDMD).

Conclusions

Our data suggests that MT can alleviate LPS-induced myocardial injury, providing novel insights into the treatment of sepsis-induced myocardial dysfunction.

Hepatitis B Surface Antigen Suppresses the Activation of Nuclear Factor Kappa B Pathway via Interaction With the TAK1-TAB2 Complex

Chronic hepatitis B is a major health problem worldwide, with more than 250 million chronic carriers. Hepatitis B virus interferes with the host innate immune system so as to evade elimination via almost all of its constituent proteins; nevertheless, the function of HBsAg with respect to immune escape remains unclear. This study aimed to determine the role HBsAg plays in assisting HBV to escape from immune responses. We found that HBsAg suppressed the activation of the nuclear factor kappa B (NF-кB) pathway, leading to downregulation of innate immune responses. HBsAg interacted with TAK1 and TAB2 specifically, inhibiting the phosphorylation and polyubiquitination of TAK1 and the K63-linked polyubiquitination of TAB2. Autophagy is a major catabolic process participating in many cellular processes, including the life cycle of HBV. We found that HBsAg promoted the autophagic degradation of TAK1 and TAB2 via the formation of complexes with TAK1 and TAB2, resulting in suppression of the NF-κB pathway. The expression of TAK1, TAB2, and the translocation of NF-κB inversely correlated with HBsAg levels in clinical liver tissues. Taken together, our findings suggest a novel mechanism by which HBsAg interacts with TAK1-TAB2 complex and suppresses the activation of NF-κB signaling pathway via reduction of the post-translational modifications and autophagic degradation.

Carthamin yellow improves cerebral ischemia‑reperfusion injury by attenuating inflammation and ferroptosis in rats

Carthamin yellow (CY), a flavonoid compound extracted from safflower, has been reported to attenuate cardiac ischemia and reperfusion injury. However, whether CY could ameliorate ischemic stroke is not completely understood. In the present study, the preventive effects of CY on experimental ischemic stroke were investigated using middle cerebral artery occlusion (MCAO) model rats. Neurological scores, brain edema, infarct area and microtubule‑associated protein 2 (MAP‑2) immunoreactivity were assessed to evaluate the effects of CY on ischemic brain injury. The involvement of inflammation and ferroptosis were examined to investigate the mechanism underlying the effects of CY. The results demonstrated that 2‑week CY treatment attenuated the neurological deficit score, brain water content and infarct area, and increased MAP‑2 immunoreactivity in the cortex in MCAO model rats. CY administration also deactivated the cortex NF‑κB/NLR family pyrin domain containing 3 inflammasome signaling pathway, and decreased serum TNF‑α, IL‑1β and IL‑6 concentrations. Moreover, CY treatment inhibited Fe²⁺ and reactive oxygen species accumulation, and reversed acyl‑CoA synthetase long‑chain family member 4, transferrin receptor 1, glutathione peroxidase 4 and ferritin heavy chain 1 protein expression levels in the brain. The levels of glutathione, superoxide dismutase and malondialdehyde in the serum were also reversed by CY treatment. Collectively, the results of the present study demonstrated that CY protected rats against ischemic stroke, which was associated with mitigation of inflammation and ferroptosis.

Limonin Attenuates LPS-Induced Hepatotoxicity by Inhibiting Pyroptosis via NLRP3/Gasdermin D Signaling Pathway

Lipopolysaccharide (LPS)-induced liver injury is the main factor in acute liver failure. The current study aims to investigate the protection of limonin, an antioxidant compound from citrus fruit, against LPS-induced liver toxicity and elucidate the potential mechanisms. We found that limonin elevated cell viability and reduced LDH release in LPS-treated HepG2 cells. Limonin also inhibited LPS-induced pyroptosis by inhibiting membrane rupture, reducing ROS generation, and decreasing gasdermin D activation. Moreover, limonin inhibited the formation of a NOD-like receptor protein 3 (NLRP3)/Apoptosis-associated speck-like protein containing a CARD (ASC) complex by reducing the related protein expression and the colocalization cytosolic of NLRP3 and caspase-1 and then suppressed IL-1β maturation. Ultimately, we established LPS-induced hepatotoxicity in vivo by using C57BL/6 mice administrated LPS (10 mg/kg) intraperitoneally and limonin (50 and 100 mg/kg) orally. We found that limonin dereased the serum ALT and AST activity and LDH release and increased the hepatic GSH amount in LPS-treated mice. Additionally, the liver histological evaluation revealed that limonin protects against LPS-induced liver damage. We further demonstrated that limonin ameliorated LPS-induced hepatotoxicity by inhibiting pyroptosis via the NLRP3/gasdermin D signaling pathway. In summary, this study uncovered the mechanism whereby limonin mitigated LPS-induced hepatotoxicity and documented that limonin might be a promising candidate drug for LPS-induced hepatotoxicity.

Amelioration of Juglanin against LPS-Induced Activation of NLRP3 Inflammasome in Chondrocytes Mediated by SIRT1

Arthritis is characterized by irreversible joint destruction and presents a global health burden. Natural alternatives to synthetic drugs have been gaining popularity for their safety and effectiveness. Juglanin has demonstrated a range of anti-inflammatory effects in various tissues and cell types. However, the pharmacological function of Juglanin in arthritis and chondrocytes has been little studied. ATDC5 cells were treated with 1 μg/mL lipopolysaccharide (LPS) in the presence or absence of juglanin (2.5, 5 μM) for 24 h. The effects of juglanin on cellular nucleotide-binding domain leucin-rich repeat receptor 3 (NLRP3) inflammasome complex and endproduct interleukin 1β (IL-1β) and interleukin (IL-18) were assessed by reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and Western blot experiments. The oxidative stress was measured by super oxide dismutase (SOD) activity and NADPH oxidase 4 (NOX4) expression. The dependent effect of juglanin on silent information regulator 2 homolog 1 (SIRT1) was evaluated by siRNA knockdown approach. Juglanin significantly reduced cellular oxidative stress by downregulating NOX4 expression production and rescuing the decreased activity of total SOD induced by LPS. Juglanin inhibited the activation of the TxNIP/NLRP3/ASC/caspase-1 axis, and decreased production of IL-1β and IL-18. Moreover, juglanin rescued the LPS-induced decrease in SIRT1 expression. SIRT1 silencing abolished the anti-NLRP3 inflammasome effect of juglanin, indicating that the effects of juglanin are dependent on its amelioration on SIRT1 expression. Juglanin possesses an anti-inflammatory and anti-ROS capacity in chondrocytes, and this study provides available evidence that juglanin may be of use in the treatment of arthritis.

Macrophage Phenotypes and Hepatitis B Virus Infection

Globally, hepatitis B virus (HBV) infection and its related liver diseases account for 780,000 deaths every year. Outcomes of HBV infection depend on the interaction between the virus and host immune system. It is becoming increasingly apparent that Kupffer cells (KCs), the largest population of resident and monocyte-derived macrophages in the liver, contribute to HBV infection in various aspects. These cells play an important role not only in the anti-HBV immunity including virus recognition, cytokine production to directly inhibit viral replication and recruitment and activation of other immune cells involved in virus clearance but also in HBV outcome and progression, such as persistent infection and development of end-stage liver diseases. Since liver macrophages play multiple roles in HBV infection, they are directly targeted by HBV to benefit its life cycle. In the present review, we briefly outline the current advances of research of macrophages, especially the studies of their phenotypes, in chronic HBV infection.

MicroRNAome: Potential and Veritable Immunomolecular Therapeutic and Diagnostic Baseline for Lingering Bovine Endometritis

The bovine endometrium is a natural pathogen invasion barrier of the uterine tissues' endometrial epithelial cells that can resist foreign pathogen invasion by controlling the inflammatory immune response. Some pathogens suppress the innate immune system of the endometrium, leading to prolonged systemic inflammatory response through the blood circulation or cellular degradation resulting in bovine endometritis by bacterial endotoxins. The microRNA (miRNA) typically involves gene expression in multicellular organisms in post-transcription regulation by affecting both the stability and the translation of messenger RNA. Accumulated evidence suggests that miRNAs are important regulators of genes in several cellular processes. They are a class of endogenous non-coding RNAs, which play pivotal roles in the inflammatory response of reproductive diseases. Studies confirmed that miRNAs play a key regulatory role in various inflammatory diseases by mediating the molecular mechanism of inflammatory cytokines via signal pathways. It implicates some miRNAs in the occurrence of bovine endometritis, resorting to regulating the activities of some inflammatory cytokines, chemokine, differentially expressed genes, and protein through modulating of specific cellular signal pathways functions. This review dwells on improving the knowledge of the role of miRNAs involvement in inflammatory response as to early diagnosis, control, and prevention of bovine endometritis and consequently enlighten on the molecular improvement of the genes coded by various differentially expressed miRNA through the need to adopt recent genetic technologies and the development of new pharmaceutical preparations.

Vinpocetine Attenuates Ischemic Stroke Through Inhibiting NLRP3 Inflammasome Expression in Mice

ABSTRACT

Ischemic stroke is the leading cause of globe death and permanent disability, but its therapeutic strategies are limited. Over the past decades, multiprotein complexes called inflammasomes have been shown as promising targets in ischemic stroke. Here, we examined vinpocetine (Vinp), a synthetic drug, playing a neuroprotective role against ischemic stroke in mice through regulating NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation. Middle cerebral artery occlusion/reperfusion (MCAO/R) was applied to mimic ischemic stroke in vivo. Vinp was administrated by intraperitoneal injection with different dose (5 or 10 mg/kg) 1 hour after reperfusion. Then, neurological assessment and infarct size were performed, and interleukin-1β (IL-1β) and IL-18 levels were evaluated using ELISA. The levels of NLRP3 inflammasome components and its upstream nuclear factor-κB (NF-κB) were determined using real-time PCR or Western blot. The experimental results indicated that posttreatment with Vinp decreased cerebral infarct size, improved behavior recover, reduced NLRP3 inflammasome expression, and suppressed the transfer of NF-κB to nucleus and proinflammatory cytokine release in middle cerebral artery occlusion/reperfusion mice. In conclusion, this study demonstrates that Vinp alleviates ischemic stroke by regulating levels of NLRP3 inflammasome, NF-κB, and proinflammatory cytokines in vivo, offering an alternative medication for ischemic stroke associated with inflammation.

Cell Death in Liver Diseases: A Review

Regulated cell death (RCD) is pivotal in directing the severity and outcome of liver injury. Hepatocyte cell death is a critical event in the progression of liver disease due to resultant inflammation leading to fibrosis. Apoptosis, necrosis, necroptosis, autophagy, and recently, pyroptosis and ferroptosis, have all been investigated in the pathogenesis of various liver diseases. These cell death subroutines display distinct features, while sharing many similar characteristics with considerable overlap and crosstalk. Multiple types of cell death modes can likely coexist, and the death of different liver cell populations may contribute to liver injury in each type of disease. This review addresses the known signaling cascades in each cell death pathway and its implications in liver disease. In this review, we describe the common findings in each disease model, as well as the controversies and the limitations of current data with a particular focus on cell death-related research in humans and in rodent models of alcoholic liver disease, non-alcoholic fatty liver disease and steatohepatitis (NASH/NAFLD), acetaminophen (APAP)-induced hepatotoxicity, autoimmune hepatitis, cholestatic liver disease, and viral hepatitis.

HBV upregulated triggering receptor expressed on myeloid cells-1 (TREM-1) expression on monocytes participated in disease progression through NF-Kb pathway

The triggering receptor expressed on myeloid cells-1 (TREM-1) signal is related to the continuous amplification of inflammatory pathway. However, it is not clear whether and how HBV can regulated the expression of TREM-1 on monocyte participated in the progression of liver disease. Here, we showed that the expression of TREM-1 on monocyte subsets were increased significantly in HBV related liver cirrhosis group compared with chronic infected group and healthy control group. HBsAg and HBeAg could up-regulated TREM-1 on monocyte by NF-KB pathway, and at least last for 72 h. Increased TREM-1 on monocyte might associated with high level of inflammatory cytokine (TNF-a, IL-1β and IL-6) and the activation of LX-2 cells. Bioinformatics analysis showed that the high expression of TREM-1 was related to the poor prognosis of hepatocellular carcinoma (HCC). The level of TREM-1 might help to predict the progression of HBV infected liver disease and treat target to prevent fibrosis progression.

MCPIP1 reduces HBV-RNA by targeting its epsilon structure

Hepatitis B virus (HBV) is the major causative factor of chronic viral hepatitis, liver cirrhosis, and hepatocellular carcinoma. We previously demonstrated that a proinflammatory cytokine IL-1β reduced the level of HBV RNA. However, the mechanism underlying IL-1β-mediated viral RNA reduction remains incompletely understood. In this study, we report that immune regulator Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) can reduce HBV RNA in hepatocytes. MCPIP1 expression level was higher in the liver tissue of HBV-infected patients and mice. Overexpression of MCPIP1 decreased HBV RNA, whereas ablating MCPIP1 in vitro enhanced HBV production. The domains responsible for RNase activity or oligomerization, were required for MCPIP1-mediated viral RNA reduction. The epsilon structure of HBV RNA was important for its antiviral activity and cleaved by MCPIP1 in the cell-free system. Lastly, knocking out MCPIP1 attenuated the anti-HBV effect of IL-1β, suggesting that MCPIP1 is required for IL-1β-mediated HBV RNA reduction. Overall, these results suggest that MCPIP1 may be involved in the antiviral effect downstream of IL-1β.

Ginsenoside Rg1 Alleviates Podocyte Injury Induced by Hyperlipidemia via Targeting the mTOR/NF-κB/NLRP3 Axis

Background

Podocyte injury plays an important role in diabetic nephropathy (DN). The aim of this study was to determine the potential therapeutic effects of the ginsenoside Rg1 on hyperlipidemia-stressed podocytes and elucidate the underlying mechanisms.

Methods

In vitro and in vivo models of DN were established as previously described, and the expression levels of relevant markers were analyzed by Western blotting, real-time Polymerase Chain Reaction (PCR), immunofluorescence, and immunohistochemistry.

Results

Ginsenoside Rg1 alleviated pyroptosis in podocytes cultured under hyperlipidemic conditions, as well as in the renal tissues of diabetic rats, and downregulated the mammalian target of rapamycin (mTOR)/NF-κB pathway. In addition, Rg1 also inhibited hyperlipidemia-induced NLRP3 inflammasome in the podocytes, which was abrogated by the mTOR activator L-leucine (LEU). The antipyroptotic effects of Rg1 manifested as improved renal function in the DN rats.

Conclusion

Ginsenoside Rg1 protects podocytes from hyperlipidemia-induced damage by inhibiting pyroptosis through the mTOR/NF-κB/NLRP3 axis, indicating a potential therapeutic function in DN.