HMGB1 and Extracellular Histones Significantly Contribute to Systemic Inflammation and Multiple Organ Failure in Acute Liver Failure

The role and mechanisms of macrophage polarization and hepatocyte pyroptosis in acute liver failure

Acute liver failure (ALF) is a severe liver disease caused by disruptions in the body's immune microenvironment. In the early stages of ALF, Kupffer cells (KCs) become depleted and recruit monocytes derived from the bone marrow or abdomen to replace the depleted macrophages entering the liver. These monocytes differentiate into mature macrophages, which are activated in the immune microenvironment of the liver and polarized to perform various functions. Macrophage polarization can occur in two directions: pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages. Controlling the ratio and direction of M1 and M2 in ALF can help reduce liver injury. However, the liver damage caused by pyroptosis should not be underestimated, as it is a caspase-dependent form of cell death. Inhibiting pyroptosis has been shown to effectively reduce liver damage induced by ALF. Furthermore, macrophage polarization and pyroptosis share common binding sites, signaling pathways, and outcomes. In the review, we describe the role of macrophage polarization and pyroptosis in the pathogenesis of ALF. Additionally, we preliminarily explore the relationship between macrophage polarization and pyroptosis, as well as their effects on ALF.

Targeting circulating high mobility group box-1 and histones by extracorporeal blood purification as an immunomodulation strategy against critical illnesses

Both high mobility group box-1 (HMGB1) and histones are major damage-associated molecular patterns (DAPMs) that mediate lethal systemic inflammation, activation of the complement and coagulation system, endothelial injury and multiple organ dysfunction syndrome in critical illnesses. Although accumulating evidence collectively shows that targeting HMGB1 or histones by their specific antibodies or inhibitors could significantly mitigate aberrant immune responses in multiple critically ill animal models, routine clinical use of such agents is still not recommended by any guideline. In contrast, extracorporeal blood purification, which has been widely used to replace dysfunctional organs and remove exogenous or endogenous toxins in intensive care units, may also exert an immunomodulatory effect by eliminating inflammatory mediators such as cytokines, endotoxin, HMGB1 and histones in patients with critical illnesses. In this review, we summarize the multiple immunopathological roles of HMGB1 and histones in mediating inflammation, immune thrombosis and organ dysfunction and discuss the rationale for the removal of these DAMPs using various hemofilters. The latest preclinical and clinical evidence for the use of extracorporeal blood purification to improve the clinical outcome of critically ill patients by targeting circulating HMGB1 and histones is also gathered.

Protective effect of pinocembrin from Penthorum chinense Pursh on hepatic ischemia reperfusion injury via regulating HMGB1/TLR4 signal pathway

Hepatic ischemia-reperfusion injury (HIRI) is of common occurrence during liver surgery and transplantation. Pinocembrin (PIN) is a kind of flavonoid monomer extracted from the local traditional Chinese medicine Penthorum chinense Pursh (P. chinense). However, the effect of PIN on HIRI has not determined. We investigated the protective effect and potential mechanism of PIN against HIRI. Model mice were subjected to partial liver ischemia for 60 min, experimental mice were pretreated with PIN orally for 7 days, and H₂ O₂ -induced oxidative damage model in AML12 hepatic cells was established in vitro. Histopathologic analysis and serum biochemical levels revealed that PIN had hepatoprotective activities against HIRI. The variation of GSH, SOD, MDA, and ROS levels indicated that PIN treatments attenuated oxidative stress in tissue. PIN pretreatment obviously ameliorated apoptosis, and restrained the expression of HMGB1 and TLR4 in vivo. In vitro, compared with H₂ O₂ group, the contents of ROS, mitochondrial membrane potential, apoptotic cells, and Bcl-2 protein were decreased, while the Bax protein expression was increased. Moreover, HMGB-1 small interfering RNA test and western blotting showed that PIN pretreatment reduced HMGB1 and TLR4 protein levels. In conclusion, PIN pretreatment effectively protected hepatocytes from HIRI and inhibited the HMGB1/TLR4 signaling pathway.

Dietary puerarin supplementation improves immune function in the small intestines of oxidized oil-challenged broilers

Puerarin has possessed a wide range of pharmacological activities. However, little is known about the protective effects of puerarin on the oxidized oil-induced injury. Here, we describe the anti-inflammatory effects of puerarin in chickens. A total of 360 broilers were arranged in four treatments. Diets included two types of soybean oil (fresh or oxidized) and two levels of puerarin (0 or 750 mg/kg). Results showed that puerarin alleviated oxidized soybean oil-induced intestinal immune injury by decreasing the expressions of HSP and pro-inflammatory factor (P < 0.05) and enhancing the mRNA levels of anti-inflammatory factor and CATH-1 (P < 0.05) in broilers. Moreover, puerarin supplementation decreased the mRNA abundances of TLR4 and MyD88 (P < 0.05) and upregulated the expressions of A20 and SOCS-1 (P < 0.05) in the small intestine of oxidized soybean oil-challenged broilers. Collectively, this study demonstrates puerarin may be a potential nutrient supplement in the treatment of oxidized oil-induced damage in poultry.

NOD2-mediated HDAC6/NF-κb signalling pathway regulates ferroptosis induced by extracellular histone H3 in acute liver failure

Acute liver failure (ALF) is life-threatening and often associated with high mortality rates. The aim of the present study was to investigate whether extracellular histone H3 could induce ferroptosis in hepatic macrophages in ALF and explore its potential mechanism. RAW264.7 macrophages and C57BL/6 mice were used in this study. LPS, D-galactosamine (D-Gal), histone H3, histone H3 antibody, NOD2 agonist Muramyl Dipeptide (MDP) and HDAC6-siRNA were administered in this study. The key molecules of ferroptosis, NOD2, HDAC6 and the NF-κb pathway, were detected. In vitro, histone H3 was released into the extracellular environment from cell nucleus after LPS exposure. In addition, histone H3 could induce ferroptosis in RAW264.7 macrophages with increased level of Fe²⁺ and ROS and decreased levels of GPX4 and GSH. MDP further aggravated ferroptosis in RAW264.7 macrophages stimulated by histone H3, which was accompanied by elevated NOD2, HDAC6, p-P65 and IκBα. HDAC6-siRNA ameliorated ferroptosis in RAW264.7 macrophages induced by histone H3, which was accompanied by decreased levels of HDAC6, p-P65 and IκBα. However, HDAC6-siRNA did not alter NOD2 levels in RAW264.7 macrophages administered histone H3. In vivo, the levels of NOD2, HDAC6 the NF-κb pathway and ferroptosis were increased in ALF mice, which were downregulated by histone H3 antibody and upregulated by histone H3. Extracellular histone H3 could induce ferroptosis in hepatic macrophages in ALF by regulating theNOD2-mediated HDAC6/NF-κb signalling pathway.

Extracellular histones aggravate autoimmune arthritis by lytic cell death

Although recent studies have demonstrated a proinflammatory effect of extracellular histones in sepsis via endothelial cytotoxicity, little is known about their contribution to autoimmune arthritis. Therefore, we investigated the role of extracellular histones in autoimmune arthritis and their cytotoxic effect on synoviocytes and macrophages. We measured histones in the synovial fluid of patients with rheumatoid arthritis (RA) and evaluated arthritis severity in a serum-transfer arthritis (STA) mouse model with intraperitoneal histone injection. Histone-induced cytotoxicity was measured using SYTOX green staining in the synoviocyte cell line MH7A and macrophages differentiated from the monocytic cell line THP-1, and the production of damage-associated molecular patterns (DAMPs) was measured by HMGB1 and ATP. Furthermore, we performed RNA-seq analysis of THP-1 cells stimulated with H2B-α1 peptide or with its citrullinated form. The levels of histones were elevated in RA synovial fluid, and histones aggravated arthritis in the STA model. Histones induced cytotoxicity and DAMP production in synoviocytes and macrophages. Chondroitin sulfate reduced histone-induced cytotoxicity, while lipopolysaccharides aggravated cytotoxicity. Moreover, the cytotoxicity decreased when the arginines in H2B-α1 were replaced with citrullines, which demonstrated its electrostatic nature. In transcriptome analysis, H2B-α1 changed the gene expression pattern of THP-1 cells involving chemokines, interleukin-1, -4, -10, -13, and toll-like receptor (TLR) signaling pathways. Extracellular histones were increased in RA synovial fluid and aggravated synovitis in STA. They induced lytic cell death through electrostatic interaction with synoviocytes and macrophages, leading to the secretion of DAMPs. These findings suggest that histones play a central role in autoimmune arthritis.

Susceptibility to Infections During Acute Liver Injury Depends on Transient Disruption of Liver Macrophage Niche

Kupffer cells are the primary liver resident immune cell responsible for the liver firewall function, including clearance of bacterial infection from the circulation, as they are strategically positioned inside the liver sinusoid with intimate contact with the blood. Disruption in the tissue-resident macrophage niche, such as in Kupffer cells, can lead to a window of susceptibility to systemic infections, which represents a significant cause of mortality in patients with acetaminophen (APAP) overdose-induced acute liver injury (ALI). However, how Kupffer cell niche disruption increases susceptibility to systemic infections in ALI is not fully understood. Using a mouse model of ALI induced by APAP overdose, we found that Kupffer cells upregulated the apoptotic cell death program and were markedly reduced in the necrotic areas during the early stages of ALI, opening the niche for the infiltration of neutrophils and monocyte subsets. In addition, during the resolution phase of ALI, the remaining tissue macrophages with a Kupffer cell morphology were observed forming replicating cell clusters closer to necrotic areas devoid of Kupffer cells. Interestingly, mice with APAP-induced liver injury were still susceptible to infections despite the dual cellular input of circulating monocytes and proliferation of remaining Kupffer cells in the damaged liver. Therapy with bone marrow-derived macrophages (BMDM) was shown to be effective in occupying the niche devoid of Kupffer cells following APAP-induced ALI. The rapid BMDM migration to the liver and their positioning within necrotic areas enhanced the healing of the tissue and restored the liver firewall function after BMDM therapy. Therefore, we showed that disruption in the Kupffer cell niche and its impaired function during acute liver injury are key factors for the susceptibility to systemic bacterial infections. In addition, modulation of the liver macrophage niche was shown to be a promising therapeutic strategy for liver injuries that reduce the Kupffer cell number and compromise the organ function.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

HMGB1 is a critical molecule in the pathogenesis of Gram-negative sepsis

Gram-negative sepsis is a severe clinical syndrome associated with significant morbidity and mortality. Lipopolysaccharide (LPS), expressed on Gram-negative bacteria, is a potent pro-inflammatory toxin that induces inflammation and coagulation via two separate receptor systems. One is Toll-like receptor 4 (TLR4), expressed on cell surfaces and in endosomes, and the other is the cytosolic receptor caspase-11 (caspases-4 and -5 in humans). Extracellular LPS binds to high mobility group box 1 (HMGB1) protein, a cytokine-like molecule. The HMGB1-LPS complex is transported via receptor for advanced glycated end products (RAGE)-endocytosis to the endolysosomal system to reach the cytosolic LPS receptor caspase-11 to induce HMGB1 release, inflammation, and coagulation that may cause multi-organ failure. The insight that LPS needs HMGB1 assistance to generate severe inflammation has led to successful therapeutic results in preclinical Gram-negative sepsis studies targeting HMGB1. However, to date, no clinical studies have been performed based on this strategy. HMGB1 is also actively released by peripheral sensory nerves and this mechanism is fundamental for the initiation and propagation of inflammation during tissue injury. Homeostasis is achieved when other neurons actively restrict the inflammatory response via monitoring by the central nervous system and the vagus nerve through the cholinergic anti-inflammatory pathway. The neuronal control in Gram-negative sepsis needs further studies since a deeper understanding of the interplay between HMGB1 and acetylcholine may have beneficial therapeutic implications. Herein, we review the synergistic overlapping mechanisms of LPS and HMGB1 and discuss future treatment opportunities in Gram-negative sepsis.

Circulating cell free DNA and citrullinated histone H3 as useful biomarkers of NETosis in endometrial cancer

BACKGROUND

Cancer mortality is mainly caused by organ failure and thrombotic events. It has been demonstrated that NETosis, a chromatin release mechanism implemented by neutrophils, may contribute to these lethal systemic effects. Our aim was to investigate NETosis biomarkers in endometrial cancer (EC).

METHODS

The experiments were conducted on 21 healthy subjects (HS) with no gynecological conditions, and on 63 EC patients. To assess the presence of NETosis features, IHC and IF was performed using antibodies against citrullinated histone H3 (citH3), neutrophil elastase (NE) and histone 2B. Serum levels of cell free DNA (cfDNA), cell free mitochondrial DNA (cfmtDNA) and citH3 were measured by qPCR using one microliter of deactivated serum, and by ELISA assay respectively. Fragmentation pattern of serum cfDNA was analyzed using the Agilent 2100 Bioanalyzer and High Sensitivity DNA Chips. Receiver operating characteristic (ROC) analysis was used to identify a cut off for cfDNA and cfmtDNA values able to discriminate between ECs and HSs. Correlation analysis and multiple correspondence analysis (MCA) between cfDNA, mtcfDNA, citH3 and blood parameters were used to identify the potential association among serum parameters in EC grades.

RESULTS

We demonstrated the presence of NETosis features in tissues from all EC grades. Serum cfDNA and cfmtDNA levels discriminate ECs from HSs and a direct correlation between citH3 and cfDNA content and an inverse correlation between cfmtDNA and citH3 in EC sera was observed, not detectable in HSs. MCA indicates cfDNA, cfmtDNA and citH3 as features associated to G1 and G2 grades. A correlation between increased levels of cfDNA, citH3 and inflammation features was found. Finally, serum nucleosomal cfDNA fragmentation pattern varies in EC sera and correlates with increased levels of cfDNA, citH3, lymphocytes and fibrinogen.

CONCLUSION

Our data highlight the occurrence of NETosis in EC and indicate serum cfDNA and citH3 as noninvasive biomarkers of tumor-induced systemic effects in endometrial cancer.

Serum superoxide dismutase level is a potential biomarker of disease prognosis in patients with HEV-induced liver failure

Background

Viral hepatitis E clinically ranges from self-limiting hepatitis to lethal liver failure. Oxidative stress has been shown to mediate hepatic inflammation during HBV-induced liver failure. We investigated whether a biomarker of oxidative stress may be helpful in assessing severity and disease outcomes of patients with HEV-induced liver failure.

Methods

Clinical data were obtained from patients with HEV-induced acute viral hepatitis (AVH, n = 30), acute liver failure (ALF, n = 17), and acute-on-chronic liver failure (ACLF, n = 36), as well as from healthy controls (HC, n = 30). The SOD and HMGB1 levels were measured in serum by ELISA. HL-7702 cells were cultured and stimulated by serum from HEV-infected patients or by HMGB1; oxidative status was investigated by CellROX and apoptosis was investigated by flow cytometry.

Results

Patients with HEV-induced liver failure (including ALF and ACLF) showed increased SOD levels compared with HEV-AVH patients and healthy controls. SOD levels > 400 U/mL were associated with a significantly higher risk of mortality in HEV-ALF and HEV-ACLF patients. Serum from HEV-infected patients led to ROS accumulation, HMGB1 secretion, and apoptosis in HL-7702 cells. Antioxidant treatment successfully inhibited HEV-induced HMGB1 secretion, and HMGB1 promoted apoptosis in HL-7702 cells.

Conclusion

HEV increased oxidative stress in the pathogenesis of HEV-induced hepatic diseases. Early testing of serum SOD may serve as a predictor of both HEV-ALF and HEV-ACLF outcomes. Moreover, development of strategies for modulating oxidative stress might be a potential target for treating HEV-induced liver failure patients.

Hepatorenal syndrome in acute-on-chronic liver failure with acute kidney injury: more questions requiring discussion

In cirrhosis with ascites, hepatorenal syndrome (HRS) is a specific prerenal dysfunction unresponsive to fluid volume expansion. Acute-on-chronic liver failure (ACLF) comprises a group of clinical syndromes with multiple organ failure and early high mortality. There are differences in the characterization of ACLF between the Eastern and Western medical communities. Patients with ACLF and acute kidney injury (AKI) have more structural injuries, contributing to confusion in diagnosing HRS-AKI. In this review, we discuss progress in the pathogenesis, diagnosis, and management of HRS-AKI, especially in patients with ACLF. Controversy regarding HRS-AKI in ACLF and acute liver failure, hepatic carcinoma, shock, sepsis, and chronic kidney disease is also discussed. Research on the treatment of HRS-AKI with ACLF needs to be more actively pursued to improve disease prognosis.

Quercetin Reduces Oxidative Stress and Apoptosis by Inhibiting HMGB1 and Its Translocation, Thereby Alleviating Liver Injury in ACLF Rats

Background

Acute on chronic liver failure (ACLF) is a syndrome of acute liver failure that occurs on the basis of chronic liver disease, which is characterized by a rapid deterioration in a short period and high mortality. High mobility group box 1 (HMGB1) may be involved in the pathological process of ACLF; its specific role remains to be further elucidated. Our previous studies have shown that quercetin (Que) exerts anti-oxidant and anti-apoptotic effects by inhibiting HMGB1 in vitro. The present study aimed to investigate the effect of Que on liver injury in ACLF rats.

Methods

The contents of ALT, AST, TBiL, and PT time of rats in each group were observed. HE staining was used to detect liver pathology. The levels of oxidative stress indicators such as MDA, GSH, and 4-HNE in the rat liver were detected. TUNEL assay was used to detect apoptosis in rat hepatocytes. Immunofluorescence and western blot analysis were performed to explore the protective effect of Que on ACLF rats and the underlying mechanism.

Results

The results showed that Que could reduce the increase of serum biochemical indices, improve liver pathology, and reduce liver damage in ACLF rats. Further results confirmed that Que reduced the occurrence of oxidative stress and apoptosis of hepatocytes, and these reactions may aggravate the progress of ACLF. Meanwhile, the results of immunofluorescence and western blotting also confirmed that the expression of HMGB1 and extranuclear translocation in ACLF rat hepatocytes were significantly increased, which was alleviated by the treatment of Que. In addition, when cotreated with glycyrrhizin (Gly), an inhibitor of HMGB1, the inhibition of Que on HMGB1 and its translocation, apoptosis and oxidative stress, and the related proteins of HMGB1-mediated cellular pathway have been significantly enhanced.

Conclusion

Thus, Que alleviates liver injury in ACLF rats, and its mechanism may be related to oxidative stress and apoptosis caused by HMGB1 and its translocation.

IGF-1 alleviates CCL4-induced hepatic cirrhosis and dysfunction of intestinal barrier through inhibition TLR4/NF-κB signaling mediated by down-regulation HMGB1

INTRODUCTION AND OBJECTIVES

Cirrhosis has gradually become a serious public health issue, especially the national prevalence of cirrhosis was 29.2% in northwest China. Recent evidence has revealed that intestinal barrier (IB) dysfunction results from and contributes to cirrhosis. Our previous results have indicated that insulin-like growth factors (IGF-1) improved the impaired IB function and downregulated high mobility group protein box-1 (HMGB-1). Nevertheless, the role of the IGF-1/HMGB1 axis in cirrhosis remains largely unknown.

MATERIALS AND METHODS

Western blotting and qRT-PCR were used to detect protein and mRNA levels of related genes. The levels of AST, ALT, IL-1β, and TNF-α were examined using commercial kits. Immunofluorescence was used to evaluate the expression of HMGB1 in tissues.

RESULTS

In carbon tetrachloride (CCl4)-treated rat, the levels of AST (380.12 vs. 183.97), ALT (148.12 vs. 53.56), IL-1β (155.94 vs. 55.60), and TNF-α (155.00 vs. 48.90) were significantly increased compared with the control group, while IGF-1 treatment significantly alleviated CCL4-induced inflammatory response and IB dysfunction by downregulating HMGB1-mediated the TLR4/MyD88/NF-κB signaling pathway. In vitro experiments, HMGB1 treatment promoted inflammatory cytokines secretion and reduced cell viability and tight junctions by activating the TLR4/MyD88/NF-κB signaling pathway in Caco-2 cells, but IGF-1 alleviated these effects.

CONCLUSION

Our findings suggest that IGF-1 might serve as a potential therapeutic target for cirrhosis and IB dysfunction via inactivation of the TLR4/MyD88/NF-κB pathway through down-regulation HMGB1.

A Novel Oxygen Carrier (M101) Attenuates Ischemia-Reperfusion Injuries during Static Cold Storage in Steatotic Livers

The combined impact of an increasing demand for liver transplantation and a growing incidence of nonalcoholic liver disease has provided the impetus for the development of innovative strategies to preserve steatotic livers. A natural oxygen carrier, HEMO2life^®, which contains M101 that is extracted from a marine invertebrate, has been used for static cold storage (SCS) and has shown superior results in organ preservation. A total of 36 livers were procured from obese Zucker rats and randomly divided into three groups, i.e., control, SCS-24H and SCS-24H + M101 (M101 at 1 g/L), mimicking the gold standard of organ preservation. Ex situ machine perfusion for 2 h was used to evaluate the quality of the livers. Perfusates were sampled for functional assessment, biochemical analysis and subsequent biopsies were performed for assessment of ischemia-reperfusion markers. Transaminases, GDH and lactate levels at the end of reperfusion were significantly lower in the group preserved with M101 (p < 0.05). Protection from reactive oxygen species (low MDA and higher production of NO2-NO3) and less inflammation (HMGB1) were also observed in this group (p < 0.05). Bcl-1 and caspase-3 were higher in the SCS-24H group (p < 0.05) and presented more histological damage than those preserved with HEMO2life^®. These data demonstrate, for the first time, that the addition of HEMO2life^® to the preservation solution significantly protects steatotic livers during SCS by decreasing reperfusion injury and improving graft function.

Intrabronchial application of extracellular histones shows no proinflammatory effects in swine in a translational pilot study

Objective

Extracellular histones have been identified as one molecular factor that can cause and sustain alveolar damage and were linked to high mortality rates in critically ill patients. In this pilot study, we wanted to validate the proinflammatory in vivo effects of local histone application in a prospective translational porcine model. This was combined with the evaluation of an experimental acute lung injury model using intrabronchial lipopolysaccharides, which has been published previously.

Results

The targeted application of histones was successful in all animals. Animals showed decreased oxygenation after instillation, but no differences could be detected between the sham and histone treatments. The histologic analyses and inflammatory responses indicated that there were no differences in tissue damage between the groups.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05704-7.

HMGB1: An overview of its roles in the pathogenesis of liver disease

High-mobility group box 1 (HMGB1) is an abundant architectural chromosomal protein that has multiple biologic functions: gene transcription, DNA replication, DNA-damage repair, and cell signaling for inflammation. HMGB1 can be released passively by necrotic cells or secreted actively by activated immune cells into the extracellular milieu after injury. Extracellular HMGB1 acts as a damage-associated molecular pattern to initiate the innate inflammatory response to infection and injury by communicating with neighboring cells through binding to specific cell-surface receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation end products (RAGE). Numerous studies have suggested HMGB1 to act as a key protein mediating the pathogenesis of chronic and acute liver diseases, including nonalcoholic fatty liver disease, hepatocellular carcinoma, and hepatic ischemia/reperfusion injury. Here, we provide a detailed review that focuses on the role of HMGB1 and HMGB1-mediated inflammatory signaling pathways in the pathogenesis of liver diseases.

Extracellular histones stimulate collagen expression in vitro and promote liver fibrogenesis in a mouse model via the TLR4-MyD88 signaling pathway

BACKGROUND

Liver fibrosis progressing to liver cirrhosis and hepatic carcinoma is very common and causes more than one million deaths annually. Fibrosis develops from recurrent liver injury but the molecular mechanisms are not fully understood. Recently, the TLR4-MyD88 signaling pathway has been reported to contribute to fibrosis. Extracellular histones are ligands of TLR4 but their roles in liver fibrosis have not been investigated.

AIM

To investigate the roles and potential mechanisms of extracellular histones in liver fibrosis.

METHODS

In vitro, LX2 human hepatic stellate cells (HSCs) were treated with histones in the presence or absence of non-anticoagulant heparin (NAHP) for neutralizing histones or TLR4-blocking antibody. The resultant cellular expression of collagen I was detected using western blotting and immunofluorescent staining. In vivo, the CCl4-induced liver fibrosis model was generated in male 6-week-old ICR mice and in TLR4 or MyD88 knockout and parental mice. Circulating histones were detected and the effect of NAHP was evaluated.

RESULTS

Extracellular histones strongly stimulated LX2 cells to produce collagen I. Histone-enhanced collagen expression was significantly reduced by NAHP and TLR4-blocking antibody. In CCl4-treated wild type mice, circulating histones were dramatically increased and maintained high levels during the duration of fibrosis-induction. Injection of NAHP not only reduced alanine aminotransferase and liver injury scores, but also significantly reduced fibrogenesis. Since the TLR4-blocking antibody reduced histone-enhanced collagen I production in HSC, the CCl4 model with TLR4 and MyD88 knockout mice was used to demonstrate the roles of the TLR4-MyD88 signaling pathway in CCl4-induced liver fibrosis. The levels of liver fibrosis were indeed significantly reduced in knockout mice compared to wild type parental mice.

CONCLUSION

Extracellular histones potentially enhance fibrogenesis via the TLR4-MyD88 signaling pathway and NAHP has therapeutic potential by detoxifying extracellular histones.

microRNA-103a-3p confers protection against lipopolysaccharide-induced sepsis and consequent multiple organ dysfunction syndrome by targeting HMGB1

BACKGROUND

Sepsis and subsequent multiple organ dysfunction syndrome (MODS) have high global incidence and mortality rate, imposing tremendous health burden. microRNAs (miRNAs or miRs) are implicated in the pathogenesis of sepsis and MODS. The aim of this study is to explore the potential mechanisms of miR-103a-3p targeted high mobility group box 1 (HMGB1) involvement in the pathogenesis of sepsis complicated with multiple organ dysfunction syndrome (MODS).

METHODS

A mouse sepsis model was induced by lipopolysaccharide (LPS). Bone marrow-derived macrophages were collected and LPS was used to establish a cellular inflammation model. Targeted binding between miR-103a-3p and HMGB1 was verified by a double luciferase assay and their roles in LPS-induced sepsis were further explored using gain-of-function experiments.

RESULTS

miR-103a-3p was decreased while HMGB1 was increased in sepsis. In LPS-induced mouse sepsis models, the downregulation of HMGB1 was found to result in reductions in NO, TNF-α, IL-1β, IL-6, lung myeloperoxidase activity, pulmonary microvascular albumin leakage, serum alanine aminotransferase, aspartate aminotransferase activity, and lung and liver tissue apoptosis. Additionally, decreased HMGB1 blunted the inflammatory response and increased survival rate of modeled mice. Importantly, HMGB1 was confirmed to a target gene of miR-103a-3p. In cellular inflammation models, miR-103a-3p was found to alleviate LPS-induced sepsis and MODS in vitro by decreasing HMGB1.

CONCLUSIONS

Taken together, our results demonstrated the inhibitory role of miR-103a-3p in sepsis via inhibiting HMGB1 expression.

Bile is a promising gut nutrient that inhibits intestinal bacterial translocation and promotes gut motility via an interleukin-6-related pathway in an animal model of endotoxemia

OBJECTIVES

People who are critically ill have high rates of endotoxemia that can significantly decrease bile flow and increase bile cytokines, the latter of which might worsen their condition. Bile acids are nutrient-signaling hormones that have a significant impact on gut barrier function and motility, and the gut is considered the origin of systemic inflammation. Therefore, healthy exogenous bile could be a promising gut nutrient for critical illness, so the biomedical role of bile in endotoxemia was investigated in this study.

METHODS

Twelve rats were injected with lipopolysaccharide (LPS) and randomized into a group with sham operation) and a group with bile external drainage (n = 6 for each group); six rats with sham operation served as the control group. In addition, interleukin-6 (IL-6) knockout mice and macrophages were treated with LPS.

RESULTS

Compared to the control animals, the group with LPS injection and sham operation had significantly increased levels of gut permeability, gut bacterial translocation, gut mucosal tumor necrosis factor α, IL-6 transcripts, and serum tumor necrosis factor α and IL-6. Compared to group with sham operation and LPS injection, bile external drainage (in LPS-challenged rats) increased gut bacterial translocation by 10 times, and this detrimental effect was associated with prolonged intestinal transit time, increased serum IL-6 concentration, and up-regulated gut mucosal IL-6 transcripts. Moreover, bile selectively inhibited LPS-stimulated macrophages in IL-6 release, which can activate gastrointestinal submucosal neurons to promote motility. Knocking out IL-6 significantly reduced gut bacterial translocation in endotoxemic mice.

CONCLUSIONS

Bile is a promising gut nutrient that inhibits gut bacterial translocation and promotes gut motility via an IL-6-related pathway in experimental endotoxemia.

Protective effect of Lactobacillus salivarius Li01 on thioacetamide-induced acute liver injury and hyperammonaemia

The gut microbiota plays pivotal roles in liver disease onset and progression. The protective effects of Lactobacillus salivarius Li01 on liver diseases have been reported. In this study, we aimed to detect the protective effect of L. salivarius Li01 on thioacetamide (TAA)-induced acute liver injury and hyperammonaemia. C57BL/6 mice were separated into three groups and given a gavage of L. salivarius Li01 or phosphate-buffered saline for 7 days. Acute liver injury and hyperammonaemia were induced with an intraperitoneal TAA injection. L. salivarius Li01 decreased mortality and serum transaminase levels and improved histological liver damage caused by TAA. Serum inflammatory cytokine and chemokine and lipopolysaccharide-binding protein (LBP) concentrations, nuclear factor κB (NFκB) pathway activation and macrophage and neutrophil infiltration into the liver were significantly alleviated by L. salivarius Li01. L. salivarius Li01 also reinforced gut barrier and reshaped the perturbed gut microbiota by upregulating Bacteroidetes and Akkermansia richness and downregulating Proteobacteria, Ruminococcaceae_UCG_014 and Helicobacter richness. Plasma and faecal ammonia levels declined noticeably in the Li01 group, accompanied by improvements in cognitive function, neuro-inflammation and relative brain-derived neurotrophic factor (BDNF) gene expression. Our results indicated that L. salivarius Li01 could be considered a potential probiotic in acute liver injury and hepatic encephalopathy (HE).

Evaluation of the Biomarkers HMGB1 and IL-6 as Predictors of Mortality in Cirrhotic Patients with Acute Kidney Injury

Background

Acute kidney injury (AKI) affects from 20% to 50% of cirrhotic patients, and the one-month mortality rate is 60%. The main cause of AKI is bacterial infection, which worsens circulatory dysfunction through the release of HMGB1 and IL-6.

Objectives

To evaluate HMGB1 and IL-6 as biomarkers of morbidity/mortality.

Methods

Prospective, observational study of 25 hospitalised cirrhotic patients with AKI. Clinical and laboratory data were collected at the time of diagnosis of AKI, including serum HMGB1 and IL-6.

Results

The mean age was 55 years; 70% were male. Infections accounted for 13 cases. The 30-day and three-month mortality rates were 17.4% and 30.4%, respectively. HMGB1 levels were lower in survivors than in nonsurvivors at 30 days (1174.2 pg/mL versus 3338.5 pg/mL, p = 0.035), but not at three months (1540 pg/mL versus 2352 pg/mL, p = 0.243). Serum IL-6 levels were 43.3 pg/mL versus 153.3 pg/mL (p = 0.061) at 30 days and 35.8 pg/mL versus 87.9 pg/mL (p = 0.071) at three months, respectively. The area under the ROC curve for HMGB1 was 0.842 and 0.657, and that for IL-6 was 0.803 and 0.743 for discriminating nonsurvivors at 30 days and three months, respectively. In multivariate analysis, no biomarker was independently associated with mortality.

Conclusion

HMGB1 levels were associated with decreased survival in cirrhotics. Larger studies are needed to confirm our results.

miR-381-3p inhibits high glucose-induced vascular smooth muscle cell proliferation and migration by targeting HMGB1

BACKGROUND

Hyperglycemia increases the risk of many cardiovascular diseases (CVD), and the dysregulation of proliferation and migration in vascular smooth muscle cells (VSMCs) also participates in the pathogenesis of CVD. miR-381-3p is known to suppress the proliferation and migration of multiple human cell types. Nevertheless, the function of miR-381-3p in VSMCs remains largely indistinct.

METHODS

A quantitative real-time polymerase chain reaction (qRT-PCR) was employed to investigate miR-381-3p expression in high-glucose-induced VSMCs. Inflammatory cytokines tumor necrosis factor-α, interleukin-1β and interleukin-6, as well as oxidative stress markers SOD and MDA, were determined by an enzyme-linked immunosorbent assay. Reactive oxygen species generation was examined using a 2,7'-dichlorofluorescein kit. The proliferation, migration and apoptosis of VSMCs were monitored by 3-(4,5-dimethylthiazl2-yl)-2,5-diphenyltetazolium bromide (MTT), transwell and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays. The TargetScan database (http://www.targetscan.org) was employed to seek the potential target gene of miR-381-3p. Interaction between miR-381-3p and HMGB1 was determined by a qRT-PCR, western blotting and a luciferase reporter assay.

RESULTS

miR-381-3p expression was significantly reduced in a VSMCs dysfunction model induced by high-glucose in a dose- and time-dependent manner. Transfection of miR-381-3p mimics suppressed the inflammation, oxidative stress, proliferation and migration of VSMCs, whereas apoptosis of VSMCs was promoted, and the transfection of miR-381-3p inhibitors had the opposite effect. Mechanistically, HMGB1, an important factor in inflammation response, was confirmed as a target gene of miR-381-3p.

CONCLUSIONS

miR-381-3p targets HMGB1 to suppress the inflammation, oxidative stress, proliferation and migration of high-glucose-induced VSMCs by targeting HMGB1.

Long noncoding RNA NEAT 1 and its target microRNA-125a in sepsis: Correlation with acute respiratory distress syndrome risk, biochemical indexes, disease severity, and 28-day mortality

Background

Sepsis is one of the main contributors to in‐hospital deaths. This study aimed to evaluate the clinical roles of long noncoding RNA (lncRNA) nuclear‐enriched abundant transcript 1 (NEAT1) and microRNA (miR)‐125a in sepsis.

Methods

LncRNA NEAT1 and miR‐125a in plasma samples from 102 sepsis patients and 100 healthy controls (HCs) were detected by reverse transcription‐quantitative polymerase chain reaction. In sepsis patients, general disease severity was assessed by acute physiology and chronic health evaluation (APACHE) II score and sequential organ failure assessment (SOFA) score. Meanwhile, acute respiratory distress syndrome (ARDS) occurrence and mortality during 28 days were recorded.

Results

LncRNA NEAT1 was increased, but miR‐125a was decreased in sepsis patients compared to HCs, and in ARDS sepsis patients compared to non‐ARDS sepsis patients. The receiver's operative characteristic (ROC) curves revealed that higher lncRNA NEAT1 or lower miR‐125a had certain predictive value for ARDS risk. Further multivariate logistic regression revealed miR‐125a but not lncRNA NEAT1 was correlated with ARDS risk independently in sepsis patients. Additionally, lncRNA NEAT1 was positively, but miR‐125a was negatively correlated with APACHE II score and SOFA score in sepsis patients. Moreover, higher lncRNA NEAT1 and lower miR‐125a were observed in 28‐day deaths compared to 28‐day survivors and were correlated with increased accumulating mortality in sepsis patients.

Conclusion

LncRNA NEAT1 high expression and miR‐125a low expression correlate with increased ARDS risk, enhanced disease severity, higher 28‐day mortality, and negatively associate with each other in sepsis patients.

An overview of high-mobility group box 1, a potent pro-inflammatory cytokine in asthma

High-mobility group box 1 (HMGB1), also called amphoterin, HMG1 and p30, is a highly conserved protein between different species that has various functions in nucleus such as stabilization of nucleosome formation, facilitation of deoxyribonucleic acid (DNA) bending and increasing the DNA transcription, replication and repair. It has also been indicated that HMGB1 acts as a potent pro-inflammatory cytokine with increasing concentrations in acute and chronic inflammatory diseases. Asthma is a common chronic respiratory disease associated with high morbidity and mortality rates. One central characteristic in its pathogenesis is airway inflammation. Considering the inflammatory role of HMGB1 and importance of inflammation in asthma pathogenesis, a better understanding of this protein is vital. This review describes the structure, cell surface receptors, signaling pathways and intracellular and extracellular functions of HMGB1, but also focuses on its inflammatory role in asthma. Moreover, this manuscript reviews experimental and clinical studies that investigated the pathologic role of HMGB1.

Kidney injury induced by elevated histones in community-acquired pneumonia

Previous studies showed that extracellular histones could damage organs, but the role of extracellular histones in pneumonia patients with acute kidney injury (AKI) is unknown. This study aims to investigate the impact of extracellular histones on patients with community-acquired pneumonia (CAP) developed AKI. Blood samples were obtained within 24 h after admission to hospital from patients who were diagnosed with CAP. According to the discharge diagnosis, the patients were divided into 2 groups (Non-AKI and AKI). In vitro, A549 cells were treated with lipopolysaccharides (LPS) and conditioned media were collected. HK2 cells were exposed to the conditioned media or not. Cells proliferation and apoptosis of HK2 were determined. Clinically, Log₂ Histones (OR 3.068; 95% CI 1.544-6.097, P = 0.001) and estimated glomerular filtration rate (eGFR) (OR 0.945; 95% CI 0.914-0.978, P = 0.001) were predictors of AKI in CAP patients. Compared to the lower histones group, patients in the higher histones group were more likely to be admitted to ICU, receive mechanical ventilation, and have a longer length of in-hospital stay. In vitro, A549 cells injured by LPS released extracellular histones, in conditioned media which significantly promoted HK2 cells apoptosis. Extracellular histones was a high risk factor for developing AKI in CAP patients and a predictor of worse short-term outcomes. We also showed that extracellular histones in conditioned media damaged HK2 cells.Trial registration number: KY20181102-03; Date of registration: 20181102.

Quercetin Attenuates d-GaLN-Induced L02 Cell Damage by Suppressing Oxidative Stress and Mitochondrial Apoptosis via Inhibition of HMGB1

High mobility group box-1 (HMGB1) plays an important role in various liver injuries. In the case of acute liver injury, it leads to aseptic inflammation and other reactions, and also regulates specific cell death responses in chronic liver injury. HMGB1 has been demonstrated to be a good therapeutic target for treating liver failure. Quercetin (Que), as an antioxidant, is a potential phytochemical with hepatocyte protection and is also considered to be an inhibitor of HMGB1. However, the mechanism of its hepatoprotective effects remains to be characterized. The present study explored whether the hepatoprotective effect of Que antagonizes HMGB1, and subsequent molecular signaling events. Our results indicated that Que protects L02 cells from d-galactosamine (d-GaLN)-induced cellular damage by reducing intracellular reactive oxygen species (ROS) production and apoptotic responses in the mitochondrial pathway. Immunofluorescence and Western blot assays showed that HMGB1 was involved in d-GaLN-induced L02 cell damage. Further research showed that after transfection with HMGB1 short hairpin RNA (shRNA), cell viability was improved, and intracellular ROS production and apoptosis were suppressed. When co-treated with Que, the expression of HMGB1 was decreased significantly, the expression of proteins in the corresponding signal pathway were further reduced, and the production of ROS and apoptosis were further suppressed. Molecular docking also indicated the binding of Que and HMGB1. Taken together, these results indicate that Que significantly improves d-GaLN-induced cellular damage by inhibiting oxidative stress and mitochondrial apoptosis via inhibiting HMGB1.

Biological Activities of Rhamnan Sulfate Extract from the Green Algae Monostroma nitidum (Hitoegusa)

Monostroma nitidum is a green single-cell layered algae that grows on the southwest coast of Japan. It is often used for salad ingredients, boiled tsukudani, soups, etc., due to its health benefits. M. nitidum is composed of many cell aggregates, and the various substances that fill the intercellular space are dietary fibers, vitamins, and minerals. Rhamnan sulfate (RS), a sulfated polysaccharide, is main the component of the fiber extracted from M. nitidum. Recently, some biological properties of RS have been demonstrated by in vitro and in vivo studies that probably protect human subjects from viruses and ameliorate vascular dysfunction caused by metabolic disorders, especially lifestyle-related diseases. In this review, we focus on the antithrombotic effects of RS and introduce its antiviral and other biological activities.

Extracellular histones play a pathogenic role in primary graft dysfunction after human lung transplantation

Primary graft dysfunction (PGD) causes early mortality and late graft failure after lung transplantation. The mechanisms of PGD are not fully understood but ischemia/reperfusion (I/R) injury may be involved. Extracellular histones have recently been identified as major contributors to I/R injury. Hence, we investigated whether extracellular histones are associated with PGD after lung transplantation. In total, 65 lung transplant patients were enrolled into this study. Blood samples were collected from patients before and serially after transplantation (24 h, 48 h, and 72 h) and measured for extracellular histones, myeloperoxidase (MPO), lactate dehydrogenase (LDH), and multiple cytokines. Besides, the patients' sera were cultured with human pulmonary artery endothelial cells (HPAEC) and human monocyte cell line (THP1) cells, respectively, and cellular viability and cytokine production were determined. Heparin or anti-histone antibody were used to study the effects of histone-neutralized interventions. The results showed that extracellular histones increased markedly after lung transplantation, peaked by 24 h and tended to decrease thereafter, but still retained high levels up to 72 h. Extracellular histones were more abundant in patients with PGD (n = 8) than patients without PGD (n = 57) and linearly correlated with MPO, LDH, and most detected cytokines. Ex vivo studies showed that the patients' sera collected within 24 h after transplantation were very damaging to HPAEC cells and promoted cytokine production in cultured THP1 cells, which could be largely prevented by heparin or anti-histone antibodies. These data suggested a pathogenic role for extracellular histones in PGD after lung transplantation. Targeting extracellular histones may serve as a preventive and therapeutic strategy for PGD following lung transplantation.

Depression of lncRNA NEAT1 Antagonizes LPS-Evoked Acute Injury and Inflammatory Response in Alveolar Epithelial Cells via HMGB1-RAGE Signaling

Sepsis-evoked acute lung injury (ALI) and its extreme manifestation, acute respiratory distress syndrome (ARDS), constitute a major cause of mortality in intensive care units. High levels of the long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) have been positively correlated with increased severity and unfavorable prognoses in patients with sepsis. Nevertheless, the function and molecular mechanism of NEAT1 in ALI remain elusive. In the current study, high levels of NEAT1 were confirmed in lipopolysaccharide- (LPS-) induced ALI mice models and in LPS-stimulated cells from the alveolar epithelial A549 cell line. Intriguingly, cessation of NEAT1 led to increased cell viability and decreased lactate dehydrogenase release, apoptosis, and caspase-3/9 activity, which conferred protection against LPS-induced injury in these cells. NEAT1 inhibition also restrained LPS-evoked transcripts and production of inflammatory cytokines IL-6, IL-1β, and TNF-α. A mechanism analysis corroborated the activation of high-mobility group box1 (HMGB1)/receptors for advanced glycation end products (RAGE) and NF-κB signaling in LPS-treated A549 cells. NEAT1 suppression reversed the activation of this pathway. Notably, reactivating HMGB1/RAGE signaling via HMGB1 overexpression blunted the anti-injury and anti-inflammation effects of NEAT1 knockdown. These findings suggest that NEAT1 may aggravate the progression of ALI and ARDS by inducing alveolar epithelial cell injury and inflammation via HMGB1/RAGE signaling, implying a promising treatment target for these conditions.

Extracellular Histone Promotes Prostate Cancer Migration and Epithelial-Mesenchymal Transition through NF-κB-Mediated Inflammatory Responses

INTRODUCTION

This study aims to explore the relationship betweenextracellular histone and prostate cancer and its mechanism.

METHODS

Migration of prostate cancer cells was detected by Transwell. Inflammatory factor expression was investigated by ELISA. Epithelial-mesenchymal transition and expression of NF-κB pathway-related proteins were investigated using Western blotting.

RESULTS

Under the induction of extracellular histones, the migration rate of prostate cancer cells and the levels of IL-1β, TNF-α, and IL-6 were notably enhanced. Then, expression of E-cadherin was significantly down-regulated, while levels of N-cadherin, vimentin, β-catenin, Snail, p-p65 and p-IκBα were significantly up-regulated, which was reversed by PDTC (pyrrolidine dithiocarbamate).

CONCLUSION

Extracellular histone significantly promotes the progression of prostate cancer cells via NF-κB pathway-mediated inflammatory responses, which may serve as a novel target for treating prostate cancer.

HMGB1-induced endothelial cell pyroptosis is involved in systemic inflammatory response syndrome following radiofrequency ablation of hepatic hemangiomas

The goal of this study was to assess the role of high-mobility group box 1 (HMGB1)-induced endothelial cell (EC) pyroptosis in systemic inflammatory response syndrome (SIRS) following radiofrequency (RF) ablation of hepatic hemangiomas. We enrolled 76 patients with hepatic hemangioma who underwent RF ablation. Serum concentrations of HMGB1, interleukin (IL)-1β, IL-18 and lactate dehydrogenase (LDH) were determined at different time points. Immunohistochemistry staining (IHC) was performed to evaluate the expressions of HMGB1, NLRP3, caspase-1, GSDMD, IL-18 and IL-1β in hepatic hemangioma and sub-ablated hemangioma tissues. In vitro experiments used human umbilical vein endothelial cells (HUVECs) treated with sub-ablative hyperthermia to mimic insufficient RF ablation of hepatic hemangiomas. ELISA and western blotting were performed to quantify HMGB1, NLRP3, caspase-1, GSDMD, IL-18, IL-1β and LDH levels with or without the addition of ethyl pyruvate (EP), a HMGB1 inhibitor, in the medium. Flow cytometry and fluorescent staining were performed to assess pyroptosis of HUVECs. Twenty-nine patients experienced SIRS after RF ablation (29/76, 38.2%). HMGB1, IL-1β and IL-18 levels were significantly correlated with SIRS. IHC staining revealed an obvious increase in HMGB1, NLRP3, caspase-1, GSDMD, IL-18, and IL-1β in the ECs of sub-ablated hemangioma but not in hepatic hemangioma. In vitro experiments showed that subablative hyperthermia led to HMGB1-induced pyroptosis of HUVECs and EP attenuated the pyroptosis of HUVECs. Taken together, these data demonstrate HMGB1-induced ECs pyroptosis may occur during SIRS following RF ablation of hepatic hemangiomas.

Damage-associated molecular patterns in trauma

In 1994, the “danger model” argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of “strange” molecules. Thus, an alternative to the “self versus non-self recognition model” has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their “friend or foe” role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.

The Role of ALDH2 in Sepsis and the To-Be-Discovered Mechanisms

Sepsis, defined as life-threatening tissue damage and organ dysfunction caused by a dysregulated host response to infection, is a critical disease which imposes global health burden. Sepsis-induced organ dysfunction, including circulatory and cardiac dysfunction, hepatic dysfunction, renal dysfunction, etc., contributes to high mortality and long-term disability of sepsis patients. Altered inflammatory response, ROS and reactive aldehyde stress, mitochondrial dysfunction, and programmed cell death pathways (necrosis, apoptosis, and autophagy) have been demonstrated to play crucial roles in septic organ dysfunction. Unfortunately, except for infection control and supportive therapies, no specific therapy exists for sepsis. New specific therapeutic targets are highly warranted. Emerging studies suggested a role of potential therapeutic target of ALDH2, a tetrameric enzyme located in mitochondria to detoxify aldehydes, in septic organ dysfunction. In this article, we will review the presentations and pathophysiology of septic organ dysfunction, as well as summarize and discuss the recent insights regarding ALDH2 in sepsis.

Mechanism of glycyrrhizin on ferroptosis during acute liver failure by inhibiting oxidative stress

The present study aimed to investigate the anti‑ferroptosis effects of the HMGB1 inhibitor glycyrrhizin (GLY). The present study used a cell and animal model of acute liver failure (ALF), induced using tumor necrosis factor‑α, lipopolysaccharide and D‑galactosamine, to investigate the effects of GLY. The expression of glutathione peroxidase 4 (GPX4) and high mobility group protein B1 (HMGB1), heme oxygenase‑1 (HO‑1) and nuclear factor erythroid 2‑related factor 2 (Nrf2) were detected were detected by western blotting in L02 hepatocytes and mouse liver. The expression of GPX4 and HMGB1 in L02 hepatocytes and mouse liver was detected by immunofluorescence. The pathological changes to liver tissues were determined by hematoxylin and eosin staining. The levels of lactate dehydrogenase (LDH), Fe2+, reactive oxygen species (ROS) and glutathione (GSH) were tested using kits. Compared with the normal group, the degree of liver damage and liver function in the model animal group was severe. The protein levels of HMGB1 in L02 cells and liver tissues were significantly increased. The expression of NRF2, HO‑1 and GPX4 was significantly decreased. The levels of LDH, Fe2+, malondialdehyde (MDA) and ROS were increased, whereas the level of GSH was decreased. Treatment with GLY reduced the degree of liver damage, the expression of HMGB1 was decreased, and the levels of Nrf2, HO‑1 and GPX4 were increased. The levels of LDH, Fe2+, MDA, ROS were decreased, while the level of GSH was increased by GLY treatment. The results of the present study indicated that HMGB1 is involved in the process of ferroptosis. The HMGB1 inhibitor GLY significantly reduced the degree of ferroptosis during ALF by inhibiting oxidative stress.

Krüppel-like factor 6 mediates pulmonary angiogenesis in rat experimental hepatopulmonary syndrome and is aggravated by bone morphogenetic protein 9

Hepatopulmonary syndrome (HPS) is a serious pulmonary vascular disease derived from chronic liver disease, and its key pathogenesis is angiogenesis. Krüppel-like factor 6 (KLF6) mediates physiological repair and remodeling during vascular injury. However, the role of KLF6 in pulmonary microvascular endothelial cells (PMVECs) during angiogenesis of HPS and its underlying mechanism in HPS have not been investigated. Common bile duct ligation (CBDL) in rats can replicate pulmonary vascular abnormalities of human HPS. Here, we found that advanced pulmonary angiogenesis and pulmonary injury score coincided with the increase of KLF6 level in PMVECs of CBDL rat; KLF6 in PMVECs was also induced while cultured with CBDL rat serum in vitro. Inhibition of KLF6 dramatically suppressed PMVEC-mediated proliferation, migration and tube formation in vivo; this may be related to the downregulation of activin receptor-like kinase-1 (ALK1) and endoglin (ENG), which are transacted by KLF6. Bone morphogenetic protein 9 (BMP9) enhanced the expression of KLF6 in PMVECs and was involved in the angiogenesis of HPS. These results suggest that KLF6 triggers PMVEC-mediated angiogenesis of HPS and is aggravated by BMP9, and the inhibition of the BMP9/KLF6 axis may be an effective strategy for HPS treatment.

Summary: Krüppel-like factor 6, which is triggered by pulmonary injury and promoted by bone morphogenetic protein 9, mediates pulmonary angiogenesis in rat experimental hepatopulmonary syndrome and then aggravates lung dysfunction.

ROR alpha protects against LPS-induced inflammation by down-regulating SIRT1/NF-kappa B pathway

Systemic inflammatory response syndrome (SIRS) is associated with excessive inflammatory response, however, the pathophysiology of inflammation is poorly understood. The retinoid-related orphan receptor α (RORα) is a key inflammatory regulator, but the mechanisms underlying its role remain unclear. The aim of this study was to investigate how RORα was involved in the regulation of inflammatory response. Here we put forward a hypothesis that RORα might negatively regulate inflammatory response by controlling silent information regulator Sirtuin 1 (SIRT1) expression. Stimulation of macrophages in vitro with LPS and LPS administration in vivo were used to explore the function of RORα and the relationship between RORα and SIRT1. We found that the level of RORα was suppressed in macrophages stimulated with LPS and overexpression or knockdown of RORα by transfection with lentivirus or siRNAs significantly decreased or increased, respectively, the pro-inflammatory cytokines IL-1β, TNF, IL-6 and MCP-1. Importantly, overexpression of RORα suppressed inflammation and alleviated LPS-induced organ injury in vivo. Further study showed that RORα could regulate SIRT1 expression and, consequently, affect deacetyation and nuclear translocation of nuclear factor-kappa B (NF-κB) subunit p65. Moreover, the activation of SIRT1 by its specific agonist, SR1720, could reduce the expression of proinflammatory cytokines in RORα knockdown macrophages stimulated with LPS. In conclusion, we demonstrated that RORα could alleviate LPS-induced inflammation and organ injury both in vivo and in vitro by blocking NF-κB p65 nuclear translocation and restricting acetylation of NF-κB p65 at lysine 310 via the regulation of SIRT1 expression. Targeting RORα might be a promising therapeutic strategy to regulate inflammatory disorders.

Updated developments on molecular imaging and therapeutic strategies directed against necrosis

Cell death plays important roles in living organisms and is a hallmark of numerous disorders such as cardiovascular diseases, sepsis and acute pancreatitis. Moreover, cell death also plays a pivotal role in the treatment of certain diseases, for example, cancer. Noninvasive visualization of cell death contributes to gained insight into diseases, development of individualized treatment plans, evaluation of treatment responses, and prediction of patient prognosis. On the other hand, cell death can also be targeted for the treatment of diseases. Although there are many ways for a cell to die, only apoptosis and necrosis have been extensively studied in terms of cell death related theranostics. This review mainly focuses on molecular imaging and therapeutic strategies directed against necrosis. Necrosis shares common morphological characteristics including the rupture of cell membrane integrity and release of cellular contents, which provide potential biomarkers for visualization of necrosis and necrosis targeted therapy. In the present review, we summarize the updated joint efforts to develop molecular imaging probes and therapeutic strategies targeting the biomarkers exposed by necrotic cells. Moreover, we also discuss the challenges in developing necrosis imaging probes and propose several biomarkers of necrosis that deserve to be explored in future imaging and therapy research.

Subcutaneous Inoculation of Echinococcus multilocularis Induces Delayed Regeneration after Partial Hepatectomy

Alveolar echinococcosis (AE) is caused by the larval stage of echinococcus multilocularis (E. multilocularis), and hepatectomy is the main modality in hepatic AE patients. Liver regeneration after partial hepatectomy (PHx) in such patients is challenging, and further investigation is needed. Thus far, knowledge regarding the possible impact of E. multilocularis on liver regeneration after PHx is limited. Herein, a subcutaneous infection model of E. multilocularis was developed in C57 BL/6 mice, and after 3 months, PHx was performed. Plasma and liver samples were harvested under inhalational isofluorane (2%) anaesthesia at designated post-PHx time points (0, 24, 48, 96 and 168 h). The parameters included the future remnant liver/body weight ratio (FLR/BW), liver function tests (AST and ALT) and related cytokines (TNF-α, IL-6, Factor V, HMGB1, TGF-β, TSP-1, and TLR4) and proteins (MyD88 and STAT3). To assess the proliferation intensity of hepatocytes, BrdU, Ki67 and PAS staining were carried out in regenerated liver tissue. The FLR/BW in the infected group from 48 h after surgery was lower than that in the control group. The BrdU positive hepatocyte proportions reached their peak at 48 h in the control group and 96 h in the infected group and then gradually decreased. During the first 48 h after surgery, both the AST and ALT levels in the infected group were lower; however, these levels were altered from 96 h after surgery. In the infected group, the concentrations and mRNA expression levels of the pre-inflammatory cytokines TNF-α and IL-6 demonstrated a delayed peak. Moreover, post-operatively, the TGF-β and TSP-1 levels showed high levels in the infected group at each different time-point compared to those in the control group; however, high levels of TGF-β were observed at 96 h in the control group. The MyD88 and STAT3 protein expression levels in the infected group were markedly higher than those in the control group 96 h after surgery. Delayed liver regeneration after PHx was observed in the C57 BL/6 mice with the subcutaneous infection of E. multilocularis in the current study. This phenomenon could be partially explained by the alteration in the pro-inflammatory cytokines in the immunotolerant milieu induced by chronic E. multilocularis infection.

Isoliquiritigenin attenuates LPS-induced AKI by suppression of inflammation involving NF-κB pathway

Septic acute kidney injury (AKI) characterized as acute infection and renal inflammation, still lacks of effective therapies. Isoliquiritigenin (ISL) as a small molecular from licorice, is able to inhibit the expression of HMGB1. However, the role and mechanism of ISL in septic AKI has not been investigated. In this study, we used LPS injection to induce murine septic AKI. One hour before LPS injection, 50 mg/kg ISL was once orally given to the mice. For the in vitro study, HK₂ human tubular cells were respectively treated with 50 μM and 100 μM ISL 5 hrs before 2 μg/ml LPS stimulation. Then we observed that ISL ameliorated renal dysfunction and attenuated renal tubular injury. ISL inhibited the phosphorylation of IκB-α and NF-κB p65 after LPS induction both in vivo and in vitro. ISL also inhibited NF-κB p65 translocation from cytoplasm to the nucleus upon LPS stimulation. Further, NF-κB p65 translocation could trigger macrophage polarization, neutrophil activation and pro-inflammatory cytokines secretion in LPS-induced inflammation. These results showed that ISL could alleviate LPS-induced AKI by suppressing NF-κB p65 translocation and inhibiting inflammatory responses, indicating protective effects of ISL in LPS-induced acute renal inflammation. This study might be useful for designing potential clinical trials to prevent and treat sepsis induced AKI in patients with serious illness.

DAMPs and sterile inflammation in drug hepatotoxicity

Drug hepatotoxicity is the leading cause of acute liver failure (ALF) in the developed countries. The early diagnosis and treatment are still problematic, and one important reason is the lack of reliable mechanistic biomarkers and therapeutic targets; therefore, searching for new biomarkers and therapeutic targets is urgent. Drug hepatotoxicity induces severe liver cells damage and death. Dead and damaged cells release endogenous damage-associated molecular patterns (DAMPs). Increased circulating levels of DAMPs (HMGB1, histones and DNA) can reflect the severity of drug hepatotoxicity. Elevated plasma HMGB1 concentrations can serve as early and sensitive mechanistic biomarker for clinical acetaminophen hepatotoxicity. DAMPS significantly contribute to liver injury and inhibiting the release of DAMPs ameliorates experimental hepatotoxicity. In addition, HMGB1 mediates 80% of gut bacterial translocation (BT) during acetaminophen toxicity. Gut BT triggers systemic inflammation, leading to multiple organ injury and mortality. Moreover, DAMPs can trigger and extend sterile inflammation, which contributes to early phase liver injury but improves liver regeneration at the late phase of acetaminophen overdose, because anti-inflammatory treatment reduces liver injury at early phase but impairs liver regeneration at late phase of acetaminophen toxicity, whereas pro-inflammatory therapy improves late phase liver regeneration. DAMPs are promising mechanistic biomarkers and could also be the potential therapeutic targets for drug hepatotoxicity. DAMPs-triggered sterile inflammation contributes to liver injury at early phase but improves liver regeneration at later phase of acetaminophen hepatotoxicity; therefore, anti-inflammatory therapy would be beneficial at early phase but should be avoided at the late phase of acetaminophen overdose.

[Low-intensity pulsed ultrasound pretreatment inhibits HMGB1 expression and attenuates lung ischemia-reperfusion injury in rats via the cholinergic anti-inflammatory pathway]

OBJECTIVE

To observe the effects of low-intensity pulsed ultrasound (LIPUS) pretreatment on pulmonary expression of high mobility group box-1 (HMGB1) in a rat model of lung ischemia-reperfusion (IR).

METHODS

Thirty-two male SpragueDawley rats weighing 250-300 g were randomly divided (n=8) into sham-operated group, lung IR group, LIPUS pretreatment group and pretreatment with α7-nicotinic cholinergic receptor (α7nAChR) antagonist group. In the sham-operated group, the left pulmonary hilum was dissociated without occlusion; in the other 3 groups, the left pulmonary hilum was occluded for 45 min followed by reperfusion for 180 min; LIPUS pretreatment for 30 min and intraperitoneal injection of methyllycaconitine (2 mg/kg), an α7nAChR antagonist, were administered before the operation. The wet/dry weight ratio (W/D) and pulmonary permeability index (LPI) of the lung tissue were measured, and the lung histopathology was observed and scored. The contents of interleukin-1 (IL-1) and IL-6 in the lung tissues were measured using ELISA, and the pulmonary expression of HMGB1 protein was detected using immunofluorescence assay and Western blotting.

RESULTS

Compared with those in the sham-operated group, the W/D of the lung tissue, LPI, pathological scores, IL-1 and IL-6 contents in the lung tissue, and pulmonary HMGB1 expression all significantly increased in the other 3 groups (P < 0.05). LIPUS preconditioning significantly lowered the W/D values, LPI, pathological score, IL-1 and IL-6 contents and HMGB1 expression in the lung tissues following lung IR, and these effects were significantly inhibited by administration of methyllycaconitine.

CONCLUSIONS

LIPUS preconditioning can reduce lung IR injury possibly by activating α7nAChR-dependent cholinergic anti-inflammatory pathway to reduce lung tissue HMGB1 expression.

Increased Concentrations of Extracellular Histones in Patients with Tuberculous Pleural Effusion

Background

Extracellular histones have recently been suggested as critical mediators in many inflammatory diseases. However, the role of extracellular histones in tuberculous pleural effusion (TPE) is unclear. The goal of this study was to explore the potential involvement of extracellular histones in patients with TPE.

Material/Methods

Samples of pleural effusion and peripheral blood were obtained from 58 patients with tuberculosis. Extracellular histones were determined in both TPE and serum samples. Moreover, the biomarkers for cellular damage, inflammatory cell activation, and systemic inflammation including lactate dehydrogenase (LDH), myeloperoxidase (MPO), S100A8/A9, as well as multiple inflammatory cytokines were measured.

Results

Extracellular histone levels were significantly elevated in TPE (4.762 mg/mL [3.336, 7.307]) and serum samples (1.502 mg/mL [1.084, 2.478]) from tuberculosis patients as compared with the serum (0.585 mg/mL [0.285, 0.949]) from healthy controls. Notably, extracellular histones in TPE were also much higher than in serum of patients (P=0.002). LDH, MPO, and S100A8/A9 levels were all increased in TPE, along with a remarkable elevation of various cytokines. A correlation analysis showed that extracellular histones were positively associated with LDH, MPO, and S100A8/A9, and a panel of inflammatory cytokines in TPE.

Conclusions

These results suggest that high concentrations of extracellular histones are markedly present in TPE, which may play an inflammatory role towards the progression of tuberculosis.

The Protective Mechanism of CAY10683 on Intestinal Mucosal Barrier in Acute Liver Failure through LPS/TLR4/MyD88 Pathway

The purpose of this study was to investigate the protective mechanism of HDAC2 inhibitor CAY10683 on intestinal mucosal barrier in acute liver failure (ALF). In order to establish ALF-induced intestinal epithelial barrier disruption models, D-galactosamine/LPS and LPS were, respectively, used with rats and NCM460 cell and then administrated with CAY10683. Transepithelial electrical resistance (TEER) was measured to detect the permeability of cells. Real-time PCR and Western blotting were employed to detect the key mRNA and protein levels. The intestinal epithelial tissue pathology was detected. After interfering with CAY10683, the mRNA and protein levels of TLR4, MyD88, TRIF, and TRAF6 were decreased compared with model group (P < 0.05), whereas the levels of ZO-1 and occluding were elevated (P < 0.05). The permeability was elevated in CAY10683-interfered groups, when compared with model group (P < 0.05). And the degree of intestinal epithelial tissue pathological damage in CAY10683 group was significantly reduced. Moreover, CAY10683 significantly decreased the TLR4 staining in animal tissue. The HDAC2 inhibitor CAY10683 could promote the damage of intestinal mucosal barrier in ALF through inhibiting LPS/TLR4/MyD88 pathway.

Janus-Faced Myeloid-Derived Suppressor Cell Exosomes for the Good and the Bad in Cancer and Autoimmune Disease

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells originally described to hamper immune responses in chronic infections. Meanwhile, they are known to be a major obstacle in cancer immunotherapy. On the other hand, MDSC can interfere with allogeneic transplant rejection and may dampen autoreactive T cell activity. Whether MDSC-Exosomes (Exo) can cope with the dangerous and potentially therapeutic activities of MDSC is not yet fully explored. After introducing MDSC and Exo, it will be discussed, whether a blockade of MDSC-Exo could foster the efficacy of immunotherapy in cancer and mitigate tumor progression supporting activities of MDSC. It also will be outlined, whether application of native or tailored MDSC-Exo might prohibit autoimmune disease progression. These considerations are based on the steadily increasing knowledge on Exo composition, their capacity to distribute throughout the organism combined with selectivity of targeting, and the ease to tailor Exo and includes open questions that answers will facilitate optimizing protocols for a MDSC-Exo blockade in cancer as well as for strengthening their therapeutic efficacy in autoimmune disease.

Recent advances in pathophysiology of disseminated intravascular coagulation: the role of circulating histones and neutrophil extracellular traps

Disseminated intravascular coagulation (DIC) is an acquired condition that develops as a complication of systemic and sustained cell injury in conditions such as sepsis and trauma. It represents major dysregulation and increased thrombin generation in vivo. A poor understanding and recognition of the complex interactions in the coagulation, fibrinolytic, inflammatory, and innate immune pathways have resulted in continued poor management and high mortality rates in DIC. This review focuses attention on significant recent advances in our understanding of DIC pathophysiology. In particular, circulating histones and neutrophil extracellular traps fulfil established criteria in DIC pathogenesis. Both are damaging to the vasculature and highly relevant to the cross talk between coagulation and inflammation processes, which can culminate in adverse clinical outcomes. These molecules have a strong potential to be novel biomarkers and therapeutic targets in DIC, which is still considered synonymous with 'death is coming'.

Propofol inhibits the release of interleukin-6, 8 and tumor necrosis factor-α correlating with high-mobility group box 1 expression in lipopolysaccharides-stimulated RAW 264.7 cells

Background

Studies have found that propofol can inhibit endotoxin-induced monocyte-macrophages to produce various inflammatory factors. This study is to disclose whether the propofol affects the expression of high-mobility group box 1 (HMGB1) in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells and the release of interleukin-6 (IL-6), 8 (IL-8) and tumor necrosis factor-α (TNF-α).

Methods

RAW 264.7 cells were divided into four groups for intervention. After culturing for 16 h, the cells and culture supernatants were collected. The expression of HMGB1 in RAW 264.7 cells was detected by Western blot. The levels of IL-6, IL-8 and TNF-α in supernatants of cells were determined by enzyme-linked immunosorbent assay (ELISA).

Results

Stimulation of LPS increased the expression of HMGB1 and promoted the release of IL-6, IL-8 and TNF-α in supernatants of RAW 264.7 cells (p < 0.05); however, propofol down-regulated the expression of LPS-stimulated HMGB1 and reduced the LPS-stimulated releases of IL-6, IL-8 and TNF-α in supernatants of RAW 264.7 cells (p < 0.05). Moreover, the releases of IL-6, IL-8 and TNF-α intimately correlated with the expression of HMGB1 in this process (p < 0.05).

Conclusion

Propofol inhibited the releases of IL-6, IL-8 and TNF-α in LPS-stimulated RAW 264.7 cells, and the levels of IL-6, IL-8 and TNF-α intimately correlated with the expression of HMGB1, which indicating that propofol may prevent inflammatory responses through reducing the releases of these cytokines and inflammatory mediators.