Intervention effects and related mechanisms of glycyrrhizic acid on zebrafish with Hirschsprung-associated enterocolitis

BACKGROUND

The prevention and treatment of Hirschsprung-associated enterocolitis (HAEC) is a serious challenge in pediatric surgery. Exploring the mechanism of HAEC is conducive to the prevention of this disease.

AIM

To explore the possible mechanism of glycyrrhizic acid (GA) and its therapeutic effect on HAEC.

METHODS

We developed a model of enteritis induced by trinitrobenzenesulfonic acid (TNBS) in zebrafish, and treated it with different concentrations of GA. We analyzed the effect of GA on the phenotype and inflammation of zebrafish.

RESULTS

After treatment with TNBS, the area of the intestinal lumen in zebrafish was significantly increased, but the number of goblet cells in the intestinal lumen was significantly reduced, but these did not increase the mortality of zebrafish, indicating that the zebrafish enteritis model was successfully developed. Different concentrations of GA protected zebrafish with enteritis. In particular, high concentrations of GA were important for the prevention and control of HAEC because it significantly reduced the intestinal luminal area, increased the number of goblet cells in the intestinal lumen, and reduced the levels of interleukin (IL)-1β and IL-8.

CONCLUSION

GA significantly reduced the intestinal luminal area, increased the number of intestinal goblet cells, and decreased IL-1β and IL-8 in zebrafish, and is important for prevention and control of HAEC.

Prognostic value of serum high mobility group box 1 protein and histone H3 levels in patients with disseminated intravascular coagulation: a multicenter prospective cohort study

Background

We compared the prognostic value of serum high mobility group box 1 protein (HMGB1) and histone H3 levels with the International Society on Thrombosis and Haemostasis (ISTH) disseminated intravascular coagulation (DIC) scores for 28-day in-hospital mortality in patients with DIC caused by various underlying diseases.

Methods

We conducted a multicenter prospective cohort study including two hematology departments, four emergency departments, and one general medicine department in Japan, between August 2017 and July 2021. We included patients diagnosed with DIC by the ISTH DIC scoring system.

Results

Overall, 104 patients were included: 50 with hematopoietic disorders, 41 with infections, and 13 with the other diseases. The 28-day in-hospital mortality rate was 21%. The receiver operator characteristic (ROC) curve showed that a DIC score of 6 points, serum HMGB1 level of 8 ng/mL, and serum histone H3 level of 2 ng/mL were the optimal cutoff points. The odds ratios of more than these optimal cutoff points of the DIC score, serum HMGB1, and histone H3 levels were 1.58 (95% confidence interval [CI]: 0.60 to 4.17, p = 0.36), 5.47 (95% CI: 1.70 to 17.6, p = 0.004), and 9.07 (95% CI: 2.00 to 41.3, p = 0.004), respectively. The area under the ROC curve of HMGB1 (0.74, 95% CI: 0.63 to 0.85) was better than that of the ISTH DIC scores (0.55, 95% CI: 0.43 to 0.67, p = 0.03), whereas that of histone H3 was not (0.71, 95% CI: 0.60 to 0.82, p = 0.07). Calibration and net reclassification plots of HMGB1 identified some high-risk patients, whereas the ISTH DIC scores and histone H3 did not. The category-free net reclassification improvement of HMGB1 was 0.45 (95% CI: 0.01 to 0.90, p = 0.04) and that of histone H3 was 0.37 (95% CI: − 0.05 to 0.78, p = 0.08).

Conclusions

Serum HMGB1 levels have a prognostic value for mortality in patients with DIC. This finding may help physicians develop treatment strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00390-2.

miR-141-3p inhibits the activation of astrocytes and the release of inflammatory cytokines in bacterial meningitis through down-regulating HMGB1

BACKGROUND

Bacterial meningitis (BM) is a serious infectious disease of the central nervous system that often occurs in children and adolescents. Many studies have suggested that microRNAs (miRNAs) are involved in BM. This study aimed to address the effects of miR-141-3p on astrocyte activation and inflammatory response in BM through HMGB1.

METHODS

The 3-week-old rats were injected with Streptococcus pneumoniae (SP) into the lateral ventricle to establish a BM model. Loeffler scoring method was used to evaluate the recovery of neurological function. Brain pathological damage was observed by hematoxylin and eosin (H&E) staining. Primary astrocytes were isolated from brain tissues of BM or non-infected SD rats. The levels of TNF-α, IL-1β, and IL-6 in brain tissues and astrocyte culture supernatant were measured by enzyme-linked immunosorbent assay (ELISA). The targeting relationship between miR-141-3p and HMGB1 was tested using dual-luciferase reporter assay. The expression of miR-141-3p, HMGB1, and the astrocytic marker glial fibrillary acidic protein (GFAP) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blotting. Methylation-specific PCR (MSP) analysis was performed to measure the methylation status of miR-141 promoter.

RESULTS

The results showed that lower Loeffler scores were exhibited in rats with BM. The subarachnoid space of brain tissues of BM rats was widened, and obvious inflammatory cells were observed. miR-141-3p expression was reduced in BM rats and SP-treated astrocytes. Additionally, we found that overexpression of miR-141-3p led to the downregulation of HMGB1, GFAP, and inflammatory cytokines (TNF-α, IL-1β, and IL-6) in astrocytes. Furthermore, the results of dual-luciferase reporter assay confirmed that miR-141-3p directly targeted HMGB1. Overexpression of miR-141-3p inhibited the levels of GFAP, TNF-α, IL-1β, and IL-6 in astrocytes, which was eliminated by the up-regulation of HMGB1. The results of MSP analysis indicated that miR-141 promoter was highly methylated in brain tissues and astrocytes. DNMT1 was involved in the methylation of miR-141 promoter in BM.

CONCLUSION

The present study verified that miR-141-3p affected inflammatory response by suppressing HMGB1 in SP-induced astrocytes and BM rat model.

miR-29a-3p transferred by mesenchymal stem cells-derived extracellular vesicles protects against myocardial injury after severe acute pancreatitis

AIMS

Acute pancreatitis (AP) is an inflammatory disease of the pancreas that may affect local tissues or remote organ systems, while severe acute pancreatitis (SAP) is a life-threatening disorder associated with multiple organ failure. In this investigation, we set about to determine whether microRNA-29a-3p (miR-29a-3p) carried by mesenchymal stem cell (MSCs)-derived extracellular vesicles (EVs) affects the myocardial injury during SAP.

MAIN METHODS

EVs were isolated from MSCs of rat bone marrow by differential centrifugation. An SAP rat model was developed and treated with MSCs-EVs and/or alteration of miR-29a-3p and HMGB1 expression, followed by assessment of the rats' cardiac function and inflammation. Next, cardiomyocytes H9C2 were co-cultured with MSC-EVs and internalization of EVs was evaluated, followed by evaluation of whether EVs could transmit miR-29a-3p cargos into H9C2 cells and affect their biological functions.

KEY FINDINGS

EVs derived from MSCs were observed to protect against SAP-induced myocardial injury. In SAP-induced rats, miR-29a-3p was under-expressed in myocardial tissues. In addition, we also confirmed that miR-29a-3p could be transferred into the H9C2 cardiomyocytes by MSC-derived EVs, which downregulated the expression of inflammatory markers and improve cardiac function to attenuate myocardial injury. Furthermore, miR-29a-3p inhibited the expression of HMGB1 to downregulate TLR4 expression and further inactivate the Akt signaling pathway.

SIGNIFICANCE

These findings support the cardioprotective action of miR-29a-3p transmitted by MSCs-derived EVs in SAP-induced myocardial injury via downregulation of the HMGB1/TLR4/Akt axis, highlighting a promising target for the EV-based therapy for SAP.

Cross-talk between fetal membranes and visceral adipose tissue involves HMGB1-RAGE and VIP-VPAC2 pathways in human gestational diabetes mellitus

AIMS

Gestational diabetes mellitus (GDM) is defined as glucose intolerance that is first diagnosed during pregnancy. Maternal adipose tissue and fetal membranes secrete various molecules that are relevant players in the pathogenesis of GDM. This pilot study aimed to examine whether the expression of the high mobility group box 1 protein (HMGB1) and its receptor for advanced glycation end products (RAGE), and the vasoactive intestinal peptide (VIP) and its receptors (VPAC-1,-2) were modified in pregnant women with GDM.

METHODS

Fetal membranes (FMs), omental adipose tissue (VAT) explants, and serum samples were obtained from 12 women with GDM and 12 with normal glucose tolerance (NGT) at delivery. The expression of HMGB1, RAGE and VIP, VPAC-1,-2 was detected by Western Blotting in explants; circulating levels and "in vitro" release of HMGB1 and VIP were measured by ELISA tests.

RESULTS

HMGB1 tissue expression was higher in FMs obtained from GDM women (p = 0.02) than in FMs from NGT women. VPAC2 (p = 0.03) and RAGE (p = 0.03) tissue expressions were significantly increased in VAT from GDM subjects. Only FMs of NGT released detectable levels of HMGB1, which was not observed in samples obtained from GDM. VAT of GDM released lower levels of VIP (p = 0.05) than NGT samples.

CONCLUSIONS

This study indicates that a fine tuned regulation exists between FMs and VAT throughout pregnancy to maintain immune metabolic homeostasis. In GDM a balance between inflammatory and anti-inflammatory mediators has been observed. Further studies are needed to establish their exact role on fetal and maternal outcomes in GDM.

[Effect of mesenchymal stem cells on expression of high mobility group box 1 protein in rats with ischemia reperfusion injury after lung transplantation]

Objective: To establish the ischemia reperfusion injury model in rat after lung transplantation(LT) and explore the expression of high mobility group box 1 protein(HMGB1) after intravenous injection with bone marrow mesenchymal stem cells(MSCs). Methods: Forty healthy 8-10 weeks male SD rats were randomly divided into four groups including the sham-operated group, ischemia-reperfusion (IR), Saline-IR and MSC-IR group. The sham-operated rats were only conducted thoracotomy without lung transplantation and the rest groups were respectively conducted with the left LT, left LT followed by 1 ml saline and left LT followed by 1 ml MSCs (1.0×10(7)/ml). Four groups of rats were killed at 24 h after reperfusion. The blood and left lung tissue were collected. Oxygenation index(OI) and the ratio of wet/dry in four groups were detected and histological sections stained with hematoxylin and eosin (HE) were made. HMGB1 levels in serum were detected with ELISA. Real-time PCR and Western blot were performed to detect the expression of HMGB1 in mRNA and protein levels. Results: The OI in four groups were respectively 383±15, 174±24, 170±30 and 217±21.OI in IR and Saline-IR group decreased compared with the sham-operated group , all P<0.01. The OI increased after injection with MSCs compared with IR group, P<0.01. The histological images showed the marked inflammatory infiltrates and interalveolar septal thickening in IR group. Treatment with MSCs reduced inflammatory injury.The ratio of wet/dry in IR group and Saline-IR group increased compared with the sham-operated group((5.38±0.19), (5.24±0.15) vs (4.16±0.12), all P<0.05). Ratio in MSC-IR group decreased compared with the IR group (4.47±0.14) vs (5.38±0.19), P<0.05. ELISA results showed that HMGB1 level increased significantly in IR group (287±37)ng/ml, Saline-IR group (260±24)ng/ml and MSC-IR group (101±14)ng/ml when compared with the sham-operated group (41±5) ng/ml. The serum HMGB1 level in IR group was positively correlated with the OI (r=0.759, P<0.05) and wet/dry ratio (r=0.725, P<0.05). RT-PCR showed that HMGB1 mRNA level in sham-operated group was the lowest and increased significantly in IR group, while decreased significantly in MSC-IR group compared with IR group and Saline-IR group(P<0.01). The results of HMGB1 expression at protein level by Western blot were consistent with the mRNA level. Conclusion: Lung transplantation can induce the expression of HMGB1 but HMGB1 level of lung tissue decreased significantly after the treatment with MSCs, which indicated that MSCs might play an important role in protecting transplanted lung via HMGB1.

Sterile Inflammatory Role of High Mobility Group Box 1 Protein: Biological Functions and Involvement in Disease

High mobility group box 1 protein (HMGB1), a sterile inflammatory molecule and damage-associated molecular pattern (DAMP) released from various cells during stress has been implicated in inflammation. Several reports show that there is a direct relationship between inflammation and cardiovascular diseases (CVDs) such as thrombosis, hypertension, insulin resistance, preeclampsia, etc. Here, we intend to summarize the concept of the emerging link between HMGB1 and CVDs. Furthermore, we will discuss the possible therapeutic strategies that target HMGB1 for the treatment of different CVDs.

Persistent Increase in Microglial RAGE Contributes to Chronic Stress-Induced Priming of Depressive-like Behavior

BACKGROUND

Chronic stress-induced inflammatory responses occur in part via danger-associated molecular pattern (DAMP) molecules, such as high mobility group box 1 protein (HMGB1), but the receptor(s) underlying DAMP signaling have not been identified.

METHODS

Microglia morphology and DAMP signaling in enriched rat hippocampal microglia were examined during the development and expression of chronic unpredictable stress (CUS)-induced behavioral deficits, including long-term, persistent changes after CUS.

RESULTS

The results show that CUS promotes significant morphological changes and causes robust upregulation of HMGB1 messenger RNA in enriched hippocampal microglia, an effect that persists for up to 6 weeks after CUS exposure. This coincides with robust and persistent upregulation of receptor for advanced glycation end products (RAGE) messenger RNA, but not toll-like receptor 4 in hippocampal microglia. CUS also increased surface expression of RAGE protein on hippocampal microglia as determined by flow cytometry and returned to basal levels 5 weeks after CUS. Importantly, exposure to short-term stress was sufficient to increase RAGE surface expression as well as anhedonic behavior, reflecting a primed state that results from a persistent increase in RAGE messenger RNA expression. Further evidence for DAMP signaling in behavioral responses is provided by evidence that HMGB1 infusion into the hippocampus was sufficient to cause anhedonic behavior and by evidence that RAGE knockout mice were resilient to stress-induced anhedonia.

CONCLUSIONS

Together, the results provide evidence of persistent microglial HMGB1-RAGE expression that increases vulnerability to depressive-like behaviors long after chronic stress exposure.

5-Lipoxygenase in monocytes emerges as a therapeutic target for intimal hyperplasia in a murine wire-injured femoral artery

Given the importance of leukotrienes in vascular inflammation induced by local tissue injury, this study investigated the role for 5-lipoxygenase (5-LO) in monocytes in the development of intimal hyperplasia. As a mechanistic study, the importance of monocyte 5-LO in monocyte-macrophage differentiation with subsequent infiltration in neointima was evaluated. In a mouse model of wire-injured femoral artery, intimal hyperplasia started as early as 2wks after injury, and luminal area and blood flow were reduced due to increased neointima formation. Time-dependent increases in macrophage infiltration were observed in neointima and showed a positive relationship with neointima volume. In 5-LO-deficient (KO) mice or wild-type (WT) mice treated with an inhibitor of 5-LO activating protein (MK886, 1 and 10mg/kg), intimal hyperplasia and macrophage infiltration into neointima were reduced, but monocyte adhesion to injured luminal surface was not inhibited, which suggested 5-LO participates in monocyte-macrophage differentiation. In an in vitro study, monocyte-macrophage differentiation was found to be increased by high mobility group box 1 protein (HMGB1), but this effect was attenuated in cells isolated from 5-LO-KO mice. Furthermore, macrophage infiltration and intimal hyperplasia were more prominent in 5-LO-KO mice transplanted with monocytes from WT mice than in 5-LO-KO mice transplanted with monocytes from 5-LO-KO mice. Taken together, it was suggested that 5-LO in monocytes played a pivotal role in monocyte-macrophage differentiation and subsequent infiltration of macrophage in neointima, leading to vascular remodeling after vascular injury.

Astragaloside IV attenuates inflammatory reaction via activating immune function of regulatory T-cells inhibited by HMGB1 in mice

CONTEXT

High-mobility group box 1 (HMGB1) protein is a highly abundant protein that can promote the pathogenesis of inflammatory. Some experiments have demonstrated a vital role for HMGB1 to modulate the immune function of regulatory T-cells (Tregs). Astragaloside IV (AST IV), an extract from Astragalus membranaceus Moench (Leguminosae), has been shown to exert potent cardioprotective and anti-inflammatory effects. It is still unclear whether AST IV has a latent effect on the proinflammatory ability of HMGB1 with subsequent activation of Tregs in vivo.

OBJECTIVE

This research explores the antagonism of different doses of AST IV on the immunologic function of Tregs mediated by HMGB1.

MATERIALS AND METHODS

Mouse models (BALB/c) were constructed by which normal saline or AST IV was administered i.p. at 2, 4 and 6 days after the administration i.p. of 20 μg recombinate HMGB1. Spleen was used to procure Treg and CD4 ⁺ CD25^- T-cells which were co-cultured with Treg. Cell phenotypes of Tregs(Foxp3) were examined, and the cytokine levels in supernatants and the proliferation of T-cells were assayed. Gene expression was measured by RT-PCR.

RESULTS

(1) The expression levels of Foxp3 in Treg on post-stimulus days (PSD) 1-7 were significantly decreased in the HMGB1 group in comparison to those in the control group mice (p < 0.01). The Foxp3 expression was markedly increased in a dose-dependent manner in the AST group as compared with those in the HMGB1 group (p < 0.0 1-0.05). The same results were found in the contents of cytokines (IL-10 and TGF-β) released into supernatants by Treg. (2) When CD4 ⁺ CD25^- T-cells were co-cultured with Treg stimulated by HMGB1, the cell proliferation and the levels of cytokines (IL-2 and IFN-γ) in supernatant were markedly increased as compared with those in the HMGB1 group. The level of IL-4 was markedly decreased as compared with that in the HMGB1 group. The same results were found when CD4 ⁺ CD25^- T-cells were co-cultured with Treg in the NS group. Compared with those in the NS group, the contrary results were shown in a dose-dependent manner in the AST group.

DISCUSSION AND CONCLUSION

These results showed that AST IV has a therapeutic effect on inflammation promoted by HMGB1, and it should be studied as a new drug for the treatment of sepsis.

Expression Levels of Proinflammatory Cytokines and NLRP3 Inflammasome in an Experimental Model of Oxazolone-induced Colitis

IL-1β and IL-17A are two cytokines with strong proinflammatory activities and are now known to be involved in a number of chronic inflammatory disorders. High-mobility group box 1 (HMGB1) is a nuclear protein regulating the expression of these proinflammatory cytokines. The NLRP3 inflammasome promotes the maturation of the IL-1β and its activation has been shown as a critical mechanism in the pathogenesis of inflammatory bowel disease (IBD). However, underlying mechanisms to modulate their production in IBD are still unclear. The aim of this study was to investigate the expression levels of mRNA for the NLRP3 inflammasome, HMGB1 and proinflammatory cytokines, IL-1β, IL-17A in the inflamed colon of rats with experimental oxazolone-induced colitis. Experiments were carried out on male wistar rats. IL-1β, IL-17A, HMGB1 and NLRP3 inflammasome mRNA expression were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our results indicated that the expression levels of IL-1β, IL-17A, NLRP3 and HMGB1 were elevated in the inflamed colon of rats with oxazolone-induced colitis.

High-mobility group box 1 protein and its role in severe acute pancreatitis

The high mobility group box 1 (HMGB1), which belongs to the subfamily of HMG-1/-2, is a highly conserved single peptide chain consisting of 215 amino acid residues with a molecular weight of approximately 24894 Da. HMGB1 is a ubiquitous nuclear protein in mammals and plays a vital role in inflammatory diseases. Acute pancreatitis is one of the most common causes of acute abdominal pain with a poor prognosis. Acute pancreatitis is an acute inflammatory process of the pancreas (duration of less than six months), for which the severe form is called severe acute pancreatitis (SAP). More and more studies have shown that HMGB1 has a bidirectional effect in the pathogenesis of SAP. Extracellular HMGB1 can aggravate the pancreatic inflammatory process, whereas intracellular HMGB1 has a protective effect against pancreatitis. The mechanism of HMGB1 is multiple, mainly through the nuclear factor-κB pathway. Receptors for advanced glycation end-products and toll-like receptors (TLR), especially TLR-2 and TLR-4, are two major types of receptors mediating the inflammatory process triggered by HMGB1 and may be also the main mediators in the pathogenesis of SAP. HMGB1 inhibitors, such as ethyl pyruvate, pyrrolidine dithiocarbamate and Scolopendra subspinipes mutilans, can decrease the level of extracellular HMGB1 and are the promising targets in the treatment of SAP.

Heparin inhibits the inflammatory response induced by LPS and HMGB1 by blocking the binding of HMGB1 to the surface of macrophages

High mobility group box 1 protein (HMGB1), a nuclear non-histone DNA-binding protein, is secreted extracellularly during inflammation and is a late mediator of inflammatory responses. The pro-inflammatory activity of recombinant HMGB1 proteins is dependent upon the formation of complexes with other mediators, such as lipopolysaccharide (LPS). This study investigated the influence of heparin on LPS+HMGB1-mediated inflammatory responses in cultured macrophages and a murine sepsis model. HMGB1 promoted the phosphorylation of p38 and ERK1/2. HMGB1 enhanced the induction of the pro-inflammatory cytokine, TNF-α, by LPS in macrophages. Heparin blocked the binding of HMGB1 to the surface of macrophages, and suppressed the phosphorylation of p38 and ERK1/2, but not JNK; TNF-α secretion was also decreased. However, heparin alone did not affect LPS-induced production of TNF-α. Heparin reduced lethality in mice exposed to LPS+HMGB1. To conclude, heparin inhibited LPS-induced HMGB1-amplified inflammatory responses by blocking HMGB1 binding to macrophage surfaces. Heparin could be used therapeutically as an effective inhibitor of HMGB1-associated inflammation.

Relationship between high mobility group box 1 protein and inflammatory bowel disease

High mobility group box 1 protein (HMGB1) is a DNA binding protein that can promote the maintenance of nucleosomal structures and regulate gene transcription in mammalian cells. HMGB1 is a ubiquitous nuclear protein that is widely distributed among mammalian cells, passively released from necrotic cells and actively released from stimulated inflammatory cells. HMGB1 might function as an endogenous immune adjuvant and play a crucial role in the development of various inflammatory diseases, and blockade of HMGB1 expression attenuates the intestinal inflammation and damage in animal models. This article reviews recent progress in understanding the relationship between HMGB1 and inflammatory bowel disease.

Novel insights for high mobility group box 1 protein-mediated cellular immune response in sepsis: A systemic review

BACKGROUND

High mobility group box 1 protein (HMGB1) is a highly conserved, ubiquitous protein in the nuclei and cytoplasm of nearly all cell types. HMGB1 is secreted into the extracellular milieu and acts as a proinfl ammatory cytokine. In this article we reviewed briefl y the cellular immune response mediated by HMGB1 in infl ammation and sepsis.

METHODS

This systemic review is mainly based on our own work and other related reports.

RESULTS

HMGB1 can actively affect the immune functions of many types of cells including T lymphocytes, regulatory T cells (Tregs), dendritic cells (DCs), macrophages, and natural killer cells (NK cells). Various cellular responses can be mediated by HMGB1 which binds to cell-surface receptors [e.g., the receptor for advanced glycation end products (RAGE), Toll-like receptor (TLR)2, and TLR4]. Anti-HMGB1 treatment, such as anti-HMGB1 polyclonal or monoclonal antibodies, inhibitors (e.g., ethyl pyruvate) and antagonists (e.g., A box), can protect against sepsis lethality and give a wider window for the treatment opportunity.

CONCLUSION

HMGB1 is an attractive target for the development of new therapeutic strategies in the treatment of patients with septic complications.

Screening HMGB1 promoter binding proteins in rat hepatic injury secondary to severe acute pancreatitis using biotin-streptavidin system

AIM: To screen proteins that interact with high mobility group protein B1 (HMGB1) promoter in rat hepatic injury secondary to severe acute pancreatitis (SAP).

METHODS: A rat model of SAP was generated by retrograde injection of 5% sodium taurocholate into the bilio-pancreatic duct. The SAP group and control group were executed simultaneously, and the liver nuclear extracts were prepared. PCR was used to amplify the biotin labeled tail probes of the HMGB1 promoter. The probes were incubated with cell nuclear extracts, and HMGB1 promoter-protein complexes were then separated using streptavidin conjugated magnetic beads. The proteins were eluted from probes with 0.25 mol/L and 1 mol/L NaCl, resolved using SDS-PAGE electrophoresis, and visualized by silver staining, and the differential bands were identified by mass spectrometry (MS).

RESULTS: A total of 14 differential protein bands between the SAP and control groups were screened, 5 of which were identified as transcription related proteins by MS.

CONCLUSION: Proteins that interact with HMGB1 promoter in SAP-associated hepatic injury were acquired and identified, which have important value for the further study of regulatory mechanism of HMGB1.

The first cyclomegastigmane rhododendroside A from Rhododendron brachycarpum alleviates HMGB1-induced sepsis

BACKGROUND

Endangered plant species are a vital resource for exploring novel drug prototypes. A Korean endangered plant Rhododendron brachycarpum G. Don is a broad-leaved shrub native to northern Korea and central Japan. The high mobility group box 1 protein (HMGB1) could be a specific target for the discovery of novel antiseptic agents.

METHODS

Gauge-invariant atomic orbital (GIAO) NMR chemical shift calculations were applied for investigation of stereochemical details with accuracy improved by application of DP4 analysis. In vitro antiseptic mechanisms were investigated utilizing immunofluorescence staining, ELISA and cell-cell adhesion assay. Cecal ligation and puncture (CLP) operation was employed to evaluate in vivo potential alleviating severe sepsis and septic shock.

RESULTS

The first bicyclic megastigmane glucoside rhododendroside A (1) along with known megastigmane glucosides (2-5) were isolated from the leaves of R. brachycarpum. The structure of 1 was established by NMR analysis as well as comparison of the experimental chemical shifts with those of computed values employing DP4 application. In the CLP operation model that simulates severe sepsis, rhododendroside A (1) improved the survival rate up to 60%.

CONCLUSIONS

Our results exhibit that R. brachycarpum may produce a unique scaffold that is developed into a drug lead mitigating HMGB1-induced vascular pro-inflammatory stimuli and thus alleviating severe sepsis and related manifestations.

GENERAL SIGNIFICANCE

Discovery of new drug leads would warrant conservation efforts of endangered species.

A high mobility group box 1 (HMGB1) gene from Chlamys farreri and the DNA-binding ability and pro-inflammatory activity of its recombinant protein

High-mobility group box 1 (HMGB1) protein, a highly conserved DNA binding protein, plays an important role in maintaining nucleosome structures, transcription, and inflammation. In the present research, a cDNA of 1268 bp for the Zhikong scallop Chlamys farreri HMGB1 (designed as CfHMGB1) was cloned via rapid amplification of cDNA ends (RACE) technique and expression sequence tag (EST) analysis. The complete cDNA sequence of CfHMGB1 contained an open reading frame (ORF) of 648 bp, which encoded a protein of 215 amino acids. The amino acid sequence of CfHMGB1 shared 53-57% similarity with other identified HMGB1s. There were two HMG domains, two low complexity regions and a conserved acidic tail in the amino acid sequence of CfHMGB1. The mRNA transcripts of CfHMGB1 were constitutively expressed in all the tested tissues, including haemocytes, muscle, mantle, gill, hepatopancreas, kidney and gonad, with the highest expression level in hepatopancreas. The mRNA expression profiles of CfHMGB1 in haemocytes after the stimulation with different pathogen-associated molecular patterns (PAMPs), including lipopolysaccharide (LPS), peptidoglycan (PGN) and glucan (Glu), were similar with an up-regulation in the early stage and then recovered to the original level. The recombinant CfHMGB1 protein could bind double-stranded DNA and induce the release of TNF-α activity in mixed primary culture of scallop haemocytes. These results collectively indicated that CfHMGB1, with DNA-binding ability and pro-inflammatory activity, could play an important role in the immune response of scallops.

Role of HMGB1/TLR signaling pathway in Helicobacter pylori infection

High mobility group box 1 protein (HMGB1), as a mediator of late inflammation, provides a wide therapeutic window. Extracellular HMGB1 as an endogenous injury-related molecule promotes the development of inflammation and damage by binding to its receptors. Studies have discovered that lipopolysaccharide and vacuolating cytotoxin A (VacA) of Helicobacter pylori (H. pylori) are strong stimulating factors of HMGB1 expression, and its extracellular receptors Toll-like receptors (TLRs) are closely associated with H. pylori infection and pathogenicity. Therefore, the HMGB1/TLR signaling pathway may play an important role in inflammatory response and immune abnormalities caused by H. pylori infection. This article will discuss the role of the HMGB1/TLR signaling pathway in H. pylori infection.

Dobutamine-mediated heme oxygenase-1 induction via PI3K and p38 MAPK inhibits high mobility group box 1 protein release and attenuates rat myocardial ischemia/reperfusion injury in vivo

BACKGROUND

It has been reported that the induction of heme oxygenase-1 (HO-1) mediated by β1-adrenergic receptor inhibits high mobility group box 1 protein (HMGB1) release and increases the survival rate in cecal ligation and puncture-induced septic mice. The present study aimed to investigate whether dobutamine, a selective β1-adrenergic receptor agonist, could inhibit HMGB1 release via β1-adrenergic receptor-mediated HO-1 induction and attenuate myocardial ischemia/reperfusion (I/R) injury in rats.

MATERIALS AND METHODS

Anesthetized male rats were pretreated with dobutamine (5 or 10 μg. Kg-1. min-1, intravenous) before ischemia in the absence and/or presence of LY294002 (0.3 mg/Kg), a phosphatidylinositol 3-kinase (PI3K)< inhibitor; SB203580 (1 mg/Kg), a p38 mitogen-activated-protein kinase (P38 mitogen-activated-protein kinase [p38 MAPK]) inhibitor, and zinc protoporphyrin IX ([ZnPPIX], 10 mg/Kg), a HO-1 inhibitor, respectively, and then subjected to ischemia for 30 min followed by reperfusion for 4 h. The myocardial I/R injury and oxidative stress were assessed. Likewise, the expressions of HO-1 protein, nuclear factor kappa B (NF-κB) p65, and HMGB1 were measured by Western blot analysis.

RESULTS

Dobutamine significantly and dose-dependently attenuated myocardial I/R injury, reduced oxidative stress, and caused the induction of HO-1, the reduction of NF-κB activation and HMGB1 over expression. However, all the effects caused by dobutamine were significantly reversed by the presence of LY294002, SB203580, and ZnPPIX, respectively.

CONCLUSIONS

The present study demonstrated that dobutamine mediated the induction of HO-1 by selectively stimulating β1-adrenergic receptor via PI3K and p38 MAPK, which inhibited HMGB1 release and attenuated rat myocardial I/R injury in vivo.

Effect of ethyl pyruvate on high mobility group box 1 protein expression and serum cytokine levels in rats with experimental colitis

AIM: To evaluate the effect of ethyl pyruvate (EP) on the expression of high mobility group box 1 protein (HMGB1) and cytokine levels in rats with experimental colitis.

METHODS: Thirty-six rats were randomly and equally divided into three groups: blank control group, model control group, and EP treatment group. Experimental colitis was induced in mice by giving dextran sodium sulfate (DSS). The impact of EP on disease activity index (DAI) and histopathological score (HPS) in experimental colitis was evaluated. The expression of HMGB1 mRNA and protein was measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively. Serum levels of TNF-a and IL-6 were determined by ELISA.

RESULTS: DAI and HPS were higher in the model control group than in the blank control group (7.20 ± 2.28 vs 0.45 ± 0.16, 13.60 ± 0.72 vs 6.4 ± 0.85, both P < 0.01). The expression levels of HMGB1 mRNA and protein were significantly higher in the model control group than in the blank control group (both P < 0.01). The levels of TNF-a and IL-6 in serum were also significantly higher in the model control group than in the blank control group (190.40 ± 24.55 vs 43.65 ± 8.79, 238.75 ± 26.58 vs 74.3 ± 7.92, both P < 0.01). Compared to the model control group, EP inhibited the body weight loss and occurrence of diarrhea as well as rectal bleeding in rats. DAI, HPS, TNF-a, IL-6 as well as the expression levels of HMGB1 mRNA and protein in the EP treatment group were significantly lower than those in the model control group (all P < 0.05).

CONCLUSION: The expression of HMGB1 is up-regulated in experimental colitis, which is closely related with the development and progression of experimental colitis. EP exerts significant therapeutic effects on DSS-induced experimental colitis in rats possibly by down-regulating the expression of HMGB1 and ameliorating the levels of inflammatory factors.

Inflammatory response and immune regulation of high mobility group box-1 protein in treatment of sepsis

Sepsis is an infection induced systemic inflammatory response syndrome and is a major cause of morbidity as well as mortality in intensive care units. A growing body of evidence suggests that the activation of a proinflammatory cascade is responsible for the development of immune dysfunction, susceptibility to severe sepsis and septic shock. The present theories of sepsis as a dysregulated inflammatory response and immune function, as manifested by excessive release of inflammatory mediators such as high mobility group box 1 protein (HMGB1), are supported by increasing studies employing animal models and clinical observations of sepsis. HMGB1, originally described as a DNA-binding protein and released passively by necrotic cells and actively by macrophages/monocytes, has been discovered to be one of essential cytokines that mediates the response to infection, injury and inflammation. A growing number of studies still focus on the inflammation-regulatory function and its contribution to infectious and inflammatory disorders, recent data suggest that HMGB1 formation can also markedly influence the host cell-mediated immunity, including T lymphocytes and macrophages. Here we review emerging evidence that support extracellular HMGB1 as a late mediator of septic complications, and discuss the therapeutic potential of several HMGB1-targeting agents in experimental sepsis. In addition, with the development of traditional Chinese medicine in recent years, it has been proven that traditional Chinese herbal materials and their extracts have remarkable effective in treating severe sepsis. In this review, we therefore provide some new concepts of HMGB1-targeted Chinese herbal therapies in sepsis.

Effect and mechanism of high mobility group box 1 protein on adhesion to pulmonary capillary endothelial cells and transendothelial migration of polymorphonuclear leucocytes

AIM: To observe the effect of high mobility group box 1 protein (HMGB1) on adhesion to pulmonary capillary endothelial cells (PCECs) and transendothelial migration of polymorphonuclear leucocytes (PMNs), and to investigate the mechanism involved.

METHODS: PMNs and PCECs of rats were isolated and cultured. PCEC monolayers were cultured with different concentrations of rHMGB, 10, 10, 100, 1000 or 10 000 μg/L. The adhesion rate of PMNs was then detected. A migration model of a boyden chamber was used to evaluate chemotaxis of HMGB1 to PMNs. Transendothelial migration was also investigated. PMNs were cultured with 100 μg/L rHMGB1 and the expression of CD11a/CD18 and CD11b/CD18 was detected by flow cytometry.

RESULTS: With increasing rHMGB1 concentration, adhesion and transendothelial migration rates of PMNs gradually increased (adhesion rate, 2.5 ± 0.5%, 5.1 ± 0.9%, 10.7 ± 1.7%, 14.6 ± 2.6%, and 25.4 ± 4.3%; transendothelial migration rate, 0%, 1.1% ± 0.3%, 6.3 ± 1.2%, 12.4 ± 2.7%, and 14.2 ± 3.1%). rHMGB1 could increase CD11a/CD18 and CD11b/CD18 expression of PMNs (both P < 0.05).

CONCLUSION: HMGB1 is not a chemotactic factor for PMNs but it can promote their adhesion and transendothelial migration by increasing expression of CD11a/CD18 and CD11b/CD18 on the surface of PMNs.