Extracellular HMGB1 as a therapeutic target in inflammatory diseases

HMGB1 Inhibition to Ameliorate Organ Failure and Increase Survival in Trauma

Several preclinical and clinical reports have demonstrated that levels of circulating high mobility group box 1 protein (HMGB1) are increased early after trauma and are associated with systemic inflammation and clinical outcomes. However, the mechanisms of the interaction between HMGB1 and inflammatory mediators that lead to the development of remote organ damage after trauma remain obscure. HMGB1 and inflammatory mediators were analyzed in plasma from 54 combat casualties, collected on admission to a military hospital in Iraq, and at 8 and 24 h after admission. In total, 45 (83%) of these patients had traumatic brain injury (TBI). Nine healthy volunteers were enrolled as controls. HMGB1 plasma levels were significantly increased in the first 8 h after admission, and were found to be associated with systemic inflammatory responses, injury severity score, and presence of TBI. These data provided the rationale for designing experiments in rats subjected to blast injury and hemorrhage, to explore the effect of HMGB1 inhibition by CX-01 (2-O, 3-O desulfated heparin). Animals were cannulated, then recovered for 5–7 days before blast injury in a shock tube and volume-controlled hemorrhage. Blast injury and hemorrhage induced an early increase in HMGB1 plasma levels along with severe tissue damage and high mortality. CX-01 inhibited systemic HMGB1 activity, decreased local and systemic inflammatory responses, significantly reduced tissue and organ damage, and tended to increase survival. These data suggest that CX-01 has potential as an adjuvant treatment for traumatic hemorrhage.

High Mobility Group Box-1 Protein and Interleukin 33 Expression in Allergic Rhinitis

BACKGROUND

Allergic rhinitis (AR) is characterized by an inflammatory reaction. High mobility group box 1 (HMGB1) protein and interleukin (IL)-33 are damage-associated molecular pattern molecules and have many characteristics similar to pro-inflammatory cytokines. However, the role of IL-33 and HMGB1 in AR remains unclear. The aim of this study is to explore the role of HMGB1 and IL-33 in AR.

METHODS

Twenty patients with AR (AR group) and 10 normal controls (normal group) were enrolled in this study. HMGB1 and IL-33 expression were analyzed by immunohistochemistry in epithelial cells of the inferior turbinate mucosa samples. Then, the human nasal mucosa epithelial cells (HNECs) were cultured in vitro, and the house dust mite allergen (Derp1) was used to stimulate the cells. Quantitative real-time PCR and ELISA assay were performed to detect HMGB1 and IL-33 expression in HNECs.

RESULTS

The expression of HMGB1 and IL-33 in the nasal mucosa was higher in the AR group than in the normal group, with a statistically significant difference (p < 0.05). In HNECs of AR, the expression of both HMGB1 and IL-33 in stimulated groups was higher than that in non-stimulated groups. The differences were statistically significant (p < 0.05). In addition, they increased gradually with the prolonging time and the concentration of the added Derp1.

CONCLUSIONS

The expression of HMGB1 and IL-33 were both increased in AR. HMGB1 and IL-33 may have a close relationship in AR.

RALY regulate the proliferation and expression of immune/inflammatory response genes via alternative splicing of FOS

RALY is a multifunctional RNA-binding protein involved in cancer metastasis, prognosis, and chemotherapy resistance in various cancers. However, the molecular mechanism of which is still unclear. We have established RALY overexpression cell lines and studied the effect of RALY on proliferation and apoptosis in HeLa cells. Then we used RNA-seq to analyze the transcriptomes data. Lastly, RT-qPCR experiments had performed to confirm the RNA-seq results. We found that the overexpression of RALY in HeLa cells inhibited proliferation. Moreover, the overexpression of RALY changed the gene expression profile, and the significant upregulation of genes involved immune/inflammatory response related biological process by NOD-like receptor signaling pathway cytokine-cytokine receptor interaction. The significant downregulation genes involved innate immune response by the Primary immunodeficiency pathway. Notably, IFIT1, IFIT2, IFTI3, IFI44, HERC4, and OASL expression had inhibited by the overexpression of RALY. Furthermore, RALY negatively regulates the expression of transcription factors FOS and FOSB. Notably, we found that 645 alternative splicing events had regulated by overexpression of RALY, which is highly enriched in transcription regulation, RNA splicing, and cell proliferation biological process by the metabolic pathway. We show that RALY regulates the expression of immune/inflammatory response-related genes via alternative splicing of FOS in HeLa cells. The novel role of RALY in regulating immune/inflammatory gene expression may explain its function in regulating chemotherapy resistance and provides novel insights into further exploring the molecular mechanism of RALY in regulating cancer immunity and chemo/immune therapies.

MicroRNA-200b-3p as a biomarker for diagnosis and survival prognosis of multiple organ dysfunction syndrome caused by acute paraquat poisoning

BACKGROUND

Acute paraquat poisoning-induced multiple organ dysfunction syndrome (MODS) leads to the high mortality. This study aimed to investigate the clinical significance of microRNA-200b-3p (miR-200b-3p), an upstream inhibitor of high-mobility group box 1 (HMGB1), in acute paraquat poisoning patients for the prediction of MODS and survival.

METHODS

This study enrolled 80 patients with MODS induced by paraquat and 94 healthy volunteers. The interaction between miR-200b-3p and HMGB1 was identified by luciferase reporter assay. miR-200b-3p levels were measured by quantitative real-time (QRT) PCR. High-mobility group box 1 levels were measured by enzyme-linked immune sorbent assay (ELISA). Receiver operating characteristic analysis was used to evaluate the diagnostic value of miR-200b-3p in screening MODS patients. The relationship between miR-200b-3p and the 28-day survival of MODS patients was evaluated by Kaplan-Meier curves and log-rank test. Cox regression analysis was used to assess the prognostic value of miR-200b-3p. Correlation between miR-200b-3p and HMGB1 was confirmed by Pearson's correlation analysis.

RESULTS

miR-200b-3p directly target HMGB1. miR-200b-3p, decreased in MODS patients, had high diagnostic value to screen MODS patients from healthy controls. Additionally, serum miR-200b-3p was decreased in non-survivors, and patients with low miR-200b-3p level had poor 28-day survival. Serum miR-200b-3p could independently predict the survival prognosis. Moreover, serum HMGB1 level was increased in MODS patients, and was negatively correlated with miR-200b-3p level.

CONCLUSION

Decreased miR-200b-3p may function as a biomarker for the diagnosis and survival prognosis of MODS patients, and miR-200b-3p may be involved in the progression of acute paraquat-induced MODS via regulating inflammatory responses by targeting HMGB1.

Detecting Critical Functional Ingredients Group and Mechanism of Xuebijing Injection in Treating Sepsis

Sepsis is a systemic inflammatory reaction caused by various infectious or noninfectious factors, which can lead to shock, multiple organ dysfunction syndrome, and death. It is one of the common complications and a main cause of death in critically ill patients. At present, the treatments of sepsis are mainly focused on the controlling of inflammatory response and reduction of various organ function damage, including anti-infection, hormones, mechanical ventilation, nutritional support, and traditional Chinese medicine (TCM). Among them, Xuebijing injection (XBJI) is an important derivative of TCM, which is widely used in clinical research. However, the molecular mechanism of XBJI on sepsis is still not clear. The mechanism of treatment of "bacteria, poison and inflammation" and the effects of multi-ingredient, multi-target, and multi-pathway have still not been clarified. For solving this issue, we designed a new systems pharmacology strategy which combines target genes of XBJI and the pathogenetic genes of sepsis to construct functional response space (FRS). The key response proteins in the FRS were determined by using a novel node importance calculation method and were condensed by a dynamic programming strategy to conduct the critical functional ingredients group (CFIG). The results showed that enriched pathways of key response proteins selected from FRS could cover 95.83% of the enriched pathways of reference targets, which were defined as the intersections of ingredient targets and pathogenetic genes. The targets of the optimized CFIG with 60 ingredients could be enriched into 182 pathways which covered 81.58% of 152 pathways of 1,606 pathogenetic genes. The prediction of CFIG targets showed that the CFIG of XBJI could affect sepsis synergistically through genes such as TAK1, TNF-α, IL-1β, and MEK1 in the pathways of MAPK, NF-κB, PI3K-AKT, Toll-like receptor, and tumor necrosis factor signaling. Finally, the effects of apigenin, baicalein, and luteolin were evaluated by in vitro experiments and were proved to be effective in reducing the production of intracellular reactive oxygen species in lipopolysaccharide-stimulated RAW264.7 cells, significantly. These results indicate that the novel integrative model can promote reliability and accuracy on depicting the CFIGs in XBJI and figure out a methodological coordinate for simplicity, mechanism analysis, and secondary development of formulas in TCM.

Crossed Pathways for Radiation-Induced and Immunotherapy-Related Lung Injury

Radiation-induced lung injury (RILI) is a form of radiation damage to normal lung tissue caused by radiotherapy (RT) for thoracic cancers, which is most commonly comprised of radiation pneumonitis (RP) and radiation pulmonary fibrosis (RPF). Moreover, with the widespread utilization of immunotherapies such as immune checkpoint inhibitors as first- and second-line treatments for various cancers, the incidence of immunotherapy-related lung injury (IRLI), a severe immune-related adverse event (irAE), has rapidly increased. To date, we know relatively little about the underlying mechanisms and signaling pathways of these complications. A better understanding of the signaling pathways may facilitate the prevention of lung injury and exploration of potential therapeutic targets. Therefore, this review provides an overview of the signaling pathways of RILI and IRLI and focuses on their crosstalk in diverse signaling pathways as well as on possible mechanisms of adverse events resulting from combined radiotherapy and immunotherapy. Furthermore, this review proposes potential therapeutic targets and avenues of further research based on signaling pathways. Many new studies on pyroptosis have renewed appreciation for the value and importance of pyroptosis in lung injury. Therefore, the authors posit that pyroptosis may be the common downstream pathway of RILI and IRLI; discussion is also conducted regarding further perspectives on pyroptosis as a crucial signaling pathway in lung injury treatment.

The danger molecule HMGB1 cooperates with the NLRP3 inflammasome to sustain expression of the EBV lytic switch protein in Burkitt lymphoma cells

High mobility group box 1 (HMGB1) is an important chromatin protein and a pro-inflammatory molecule. Though shown to enhance target DNA binding by the Epstein-Barr virus (EBV) lytic switch protein ZEBRA, whether HMGB1 actually contributes to gammaherpesvirus biology is not known. In investigating the contribution of HMGB1 to the lytic phase of EBV, important for development of EBV-mediated diseases, we find that compared to latently-infected cells, lytic phase Burkitt lymphoma-derived cells and peripheral blood lytic cells during primary EBV infection express high levels of HMGB1. Our experiments place HMGB1 upstream of ZEBRA and reveal that HMGB1, through the NLRP3 inflammasome, sustains the expression of ZEBRA. These findings indicate that in addition to the NLRP3 inflammasome's recently discovered role in turning the EBV lytic switch on, NLRP3 cooperates with the danger molecule HMGB1 to also maintain ZEBRA expression, thereby sustaining the lytic signal.

Indoprofen exerts a potent therapeutic effect against sepsis by alleviating high mobility group box 1-mediated inflammatory responses

Indoprofen is a non-steroidal anti-inflammatory drug, and has provided insights into treatment of spinal muscular atrophies; however, the treatment effect of indoprofen on sepsis and the precise underlying mechanism remain to be elucidated. This study was carried out to examine the inhibitory effect of indoprofen on high mobility group box 1 (HMGB1)-mediated inflammatory responses in vivo and in vitro. Intraperitoneal injection of indoprofen (20 or 40 mg/kg) at 8 h post-sepsis markedly improved the survival of BALB/c mice and ameliorated multiple-organ injury by blocking the inflammatory responses. In addition, indoprofen partially reduced the HMGB1 level in the serum and in the lung, as well as ameliorated pulmonary edema. Mechanistically, indoprofen potently inhibited the release of HMGB1 following stimulation by lipopolysaccharide (LPS) or polyinosinic:polycytidylic acid (poly I:C), and suppressed recombinant human HMGB1(rhHMGB1)-induced inflammatory responses. It was also found that indoprofen has both cyclooxygenase 2-dependent and -independent inhibitory effects on the proinflammatory effect of HMGB1 in THP-1 cells. Further, the drug reduced rhHMGB1-induced cell surface levels of toll-like receptor 2, toll-like receptor 4, and receptor of advanced glycation end-products in a concentration-dependent manner. Collectively, these data demonstrated that the anti-inflammatory effect of indoprofen in sepsis was associated with HMGB1-mediated inflammatory responses, thus offering a favorable mechanistic basis to support the therapeutic potential of indoprofen for the treatment of lethal sepsis or other inflammatory diseases.

Circular RNA Foxo3 Relieves Myocardial Ischemia/Reperfusion Injury by Suppressing Autophagy via Inhibiting HMGB1 by Repressing KAT7 in Myocardial Infarction

Introduction

Myocardial infarction is coronary artery-related heart disease, and the leading cause of mortality globally. Circular RNAs (circRNAs) are a new type of regulatory RNAs and participate in multiple pathological cardiac progression.

Methods

However, the function of circFoxo3 in MI-induced myocardial injury remains obscure.

Results

Significantly, we identified that circFoxo3 was downregulated in the MI rat model and the overexpression of circFoxo3 ameliorated MI-induced cardiac dysfunction and attenuated MI-induced autophagy in rat model. Meanwhile, the overexpression of circFoxo3 repressed oxygen–glucose deprivation (OGD)-induced autophagy, apoptosis, inflammation, and injury of cardiomyocyte in vitro. Mechanically, we identified that the expression of KAT7 was reduced by circFoxo3 overexpression in cardiomyocytes. Meanwhile, the expression of HMGB1 was repressed by the depletion of KAT7 in cardiomyocytes. The enrichment of histone H3 lysine 14 acetylation (H3K14ac) and RNA polymerase II (RNA pol II) on HMGB1 promoter was inhibited by the knockdown of KAT7. Moreover, the overexpression of circFoxo3 suppressed HMGB1 expression and KAT7 overexpression rescued the expression of HMGB1 in cardiomyocytes. The enrichment of KAT7, H3K14ac, and RNA poly II on HMGB1 promoter was decreased by circFoxo3 overexpression, while the overexpression of KAT7 could reverse the effect. The overexpression of KAT7 or HMGB1 could reverse circFoxo3-attenuated cardiomyocyte injury and autophagy in vitro. Thus, we conclude that circular RNA circFoxo3 relieved myocardial ischemia/reperfusion injury by suppressing autophagy via inhibiting HMGB1 by repressing KAT7 in MI.

Discussion

Our finding provides new insight into the mechanism by which circFoxo3 regulates MI-related cardiac dysfunction by targeting KAT7/HMGB1 axis.

Pharmacological Inhibition of HMGB1 Prevents Muscle Wasting

Background: Cachexia is a multifactorial disorder characterized by weight loss and muscle wasting, making up for about 20% of cancer-related death. However, there are no effective drugs to combat cachexia at present.

Methods: In this study, the effect of CT26 exosomes on C2C12 myotubes was observed. We compared serum HMGB1 level in cachexia and non-cachexia colon cancer patients. We further explored HMGB1 expression level in CT26 exosome. We added recombinant HMGB1 to C2C12 myotubes to observe the effects of HMGB1 on C2C12 myotubes and detected the expression level of the muscle atrophy-related proteins. Then, we used the HMGB1 inhibitor glycyrrhizin to reverse the effects of HMGB1 on C2C12 myotubes. Finally, HMGB1 inhibitor glycyrrhizin was utilized to relieve cachexia in CT26 cachexia mouse model.

Results: Exosomes containing HMGB1 led to muscle atrophy with significantly decreased myotube diameter and increased expression of muscle atrophy-related proteins Atrogin1 and MuRF1. Further, we detected that HMGB1 induced the muscle atrophy mainly via TLR4/NF-κB pathway. Administration of the HMGB1 inhibitor glycyrrhizin could relieve muscle wasting in vitro and attenuate the progression of cachexia in vivo.

Conclusion: These findings demonstrate the cachectic role of HMGB1, whether it is soluble form of HMGB1 or secreted from tumor cells as part of exosomes. HMGB1 inhibitor glycyrrhizin might be a promising drug in colon cancer cachexia.

Curcumin plays a local anti-inflammatory and antioxidant role via the HMGB1/TLR4/NF-ΚB pathway in rat masseter muscle under psychological stress

BACKGROUND AND OBJECTIVE

Psychological stress causes structural and metabolic dysfunction of masseter muscles. The anti-inflammatory and anti-oxidative polyphenol curcumin plays a local antioxidant role in rat masseter muscles under psychological stress by an as-yet-unknown mechanism. The present study aimed to assess curcumin anti-inflammatory and anti-oxidative effects on masseter muscle and its possible molecular mechanisms.

METHODS

We constructed a rat model of chronic unpredictable moderate stress (CUMS). Psychological stress was assessed by determining the levels of adrenocorticotropic hormone (ACTH) and cortisol in serum. Enzyme-linked immunosorbent assays measured inflammatory cytokines and markers of oxidative stress in masseter muscles. Levels of high-mobility group box 1 (HMGB1), interleukin (IL)-1β, IL-6 and tumour necrosis factor-alpha (TNF-α) were determined using quantitative PCR analyses and immunofluorescent staining. Toll-like receptor 4 (TLR4) and nuclear factor kappa B (NF-κB) activation were examined using western blotting.

RESULTS

The CUMS group showed increased serum cortisol and ACTH levels. Pathological changes in the ultrastructure, oxidative stress and inflammatory cytokines in the masseter muscles were also observed. Curcumin treatment (50, 100 mg/kg) ameliorated these changes significantly by varying degrees. Mechanistically, increased levels of phosphorylated NF-κB, toll-like receptor 4 and HMGB1 were observed, which were also ameliorated by curcumin treatment.

CONCLUSION

Curcumin can reduce local pathological changes, levels of oxidative stress and inflammatory factors in masseter muscles. Psychological stress activates HMGB1 expression and increases the expression of downstream TLR4 and p-NF-κB, which could be reduced by curcumin. Thus, curcumin might exert anti-inflammatory and antioxidant effects in masseter muscles via the HMGB1/TLR4/NF-κB pathway.

Fully Reduced HMGB1-Containing Peptide-Based Polyurethane Scaffold with Minimal Functional Unit of Skin (MFUS) Enhances Large and Deep Wounded Skin Healing

A novel peptide-based polymer is developed by lysine-diisocyanate (LDI), glycerol (Gly), and fully reduced HMGB1 (frHMGB1). This frHMGB1-LDI-Gly polymer either forms sponge-like foam (scaffold) or a hydrogel or a film under different reaction conditions. It degrades into nontoxic lysine, glycerol, and frHMGB1. The hydrogel glues tissues together and the glued tissues have strong mechanical properties. The film and scaffold provide the suitable environment for enhancing cell proliferation by releasing frHMGB1. The scaffold carries 1 mm diameter of full-thickness rat skin-island as a minimal functional unit of skin (MFUS) to treat large full thickness skin wounds, and the hydrogel glues the MFUS and scaffold with skin edges together (MFUS+Scaffold group). The scaffold treated wounds (Scaffold group) heal much faster than the wounds either treated with MFUS (MFUS group) or without treatment (Wound group). The MFUS+Scaffold treated wound regenerates more functional full-thickness skin with more hair follicles and sweat glands, higher CD146 and α-smooth muscle actin levels, more blood vessels and collagen productions, and less scar tissues when compared to the other three groups. The results demonstrate that the combination of frHMGB1-LDI-Gly polymer with MFUS provides a new tissue engineering approach for large full-thickness skin wound healing.

Pathogen-induced inflammation is attenuated by the iminosugar MON-DNJ via modulation of the unfolded protein response

Sepsis is a life-threatening condition involving a dysregulated immune response to infectious agents that cause injury to host tissues and organs. Current treatments are limited to early administration of antibiotics and supportive care. While appealing, the strategy of targeted inhibition of individual molecules in the inflammatory cascade has not proved beneficial. Non-targeted, systemic immunosuppression with steroids has shown limited efficacy and raises concern for secondary infection. Iminosugars are a class of small molecule glycomimetics with distinct inhibition profiles for glycan processing enzymes based on stereochemistry. Inhibition of host endoplasmic reticulum resident glycoprotein processing enzymes has demonstrated efficacy as a broad-spectrum antiviral strategy, but limited consideration has been given to the effects on host glycoprotein production and consequent disruption of signalling cascades. This work demonstrates that iminosugars inhibit dengue virus, bacterial lipopolysaccharide and fungal antigen-stimulated cytokine responses in human macrophages. In spite of decreased inflammatory mediator production, viral replication is suppressed in the presence of iminosugar. Transcriptome analysis reveals the key interaction of pathogen-induced endoplasmic reticulum stress, the resulting unfolded protein response and inflammation. Our work shows that iminosugars modulate these interactions. Based on these findings, we propose a new therapeutic role for iminosugars as treatment for sepsis-related inflammatory disorders associated with excess cytokine secretion.

Liraglutide protects against lethal renal ischemia-reperfusion injury by inhibiting high-mobility group box 1 nuclear-cytoplasmic translocation and release

Liraglutide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been reported to exert protective effects against myocardial, hepatic, and gastric ischemia-reperfusion injury (IRI), but whether it can protect against renal IRI remains unknown. Here, a lethal renal IRI model was established with a 100% mortality rate in untreated mice. Treatment with liraglutide involving a regimen of multiple doses resulted in 100% survival, remarkable preservation of renal function, a significant reduction in pathological damage, and blunted upregulation of TNF-α, IL-1β, IL-6, MCP-1, TLR-2, TLR-4, and RAGE mRNA. We found that liraglutide treatment dramatically inhibited ischemia-induced nucleocytoplasmic translocation and release of HMGB1. This inhibition was associated with a marked decrease (~ 60%) in nuclear histone acetyltransferase activity. In addition, the protective effects of liraglutide on renal IRI were largely abolished by the administration of exogenous HMGB1. When the GLP-1R antagonist exendin (9-39) was given to mice before each liraglutide administration, or GLP-1R-/- mice were used for the renal IRI experiments, the protective effect of liraglutide on renal IRI was partially reversed. Moreover, liraglutide pretreatment significantly inhibited HMGB1 nucleocytoplasmic translocation during hypoxic culture of HK-2 cells in vitro, but the addition of exendin (9-39) significantly eliminated this inhibition. We demonstrate here that liraglutide can exert a strong protective effect on lethal renal IRI in mice. This protection appears to be related to the inhibition of HMGB1 nuclear-cytoplasmic translocation and release and partially depends on GLP-1R. Thus, liraglutide may be therapeutically useful for the clinical prevention and treatment of organ IRI.

Sodium Butyrate Alleviates Intestinal Inflammation in Mice with Necrotizing Enterocolitis

Objective

To determine the role of sodium butyrate in intestinal inflammation via regulation of high-mobility group box-1 (HMGB1), we analyzed the potential mechanism in necrotizing enterocolitis (NEC) in a neonatal mouse model.

Methods

A NEC model was created with hypoxia and cold exposure and artificial overfeeding. C57BL/6 neonatal mice were randomized into three groups: the control, untreated NEC, and sodium butyrate (150 mM)-pretreated NEC groups. Pathological variations in ileocecal intestinal tissue were observed by HE staining and scored in a double-blind manner. The mRNA expression levels of HMGB1, Toll-like receptor 4 (TLR4), nuclear factor-κB (NF-κB), and inflammatory cytokines in intestinal tissues were determined by quantitative real-time PCR. The protein levels of HMGB1 and associated cytokines in intestinal tissues were evaluated using ELISA. The relative protein expression levels of TLR4 and NF-κB in intestinal tissues were quantified by western blot.

Results

Sodium butyrate administration improved the body weight and survival rate of NEC mice; relieved intestinal pathological injury; reduced the intestinal expression of HMGB1, TLR4, NF-κB, interleukin- (IL-) 1β, IL-6, IL-8, and TNF-α; and increased the intestinal expression of IL-10 (P < 0.05). Treatment with butyrate decreased the proportion of opportunistic Clostridium_sensu_stricto_1 and Enterococcus and increased the proportion of beneficial Firmicutes and Lactobacillus in the NEC model.

Conclusions

Sodium butyrate intervention relieves intestinal inflammation and partially corrects the disrupted intestinal flora in mice with NEC.

Neurons Are a Primary Driver of Inflammation via Release of HMGB1

Recent data show that activation of nociceptive (sensory) nerves turns on localized inflammation within the innervated area in a retrograde manner (antidromically), even in the absence of tissue injury or molecular markers of foreign invaders. This neuroinflammatory process is activated and sustained by the release of neuronal products, such as neuropeptides, with the subsequent amplification via recruitment of immunocompetent cells, including macrophages and lymphocytes. High mobility group box 1 protein (HMGB1) is a highly conserved, well characterized damage-associated molecular pattern molecule expressed by many cells, including nociceptors and is a marker of inflammatory diseases. In this review, we summarize recent evidence showing that neuronal HMGB1 is required for the development of neuroinflammation, as knock out limited to neurons or its neutralization via antibodies ameliorate injury in models of nerve injury and of arthritis. Further, the results of study show that HMGB1 is actively released during neuronal depolarization and thus plays a previously unrecognized key etiologic role in the initiation and amplification of neuroinflammation. Direct targeting of HMGB1 is a promising approach for novel anti-inflammatory therapy.

Identification of circular RNA circVPS33A as a modulator in house dust mite-induced injury in human bronchial epithelial cells

BACKGROUND

House dust mite has been well documented as a major source of allergen in asthma. Circular RNAs (circRNAs) vacuolar protein sorting 33A (circVPS33A, circ_0000455) is overexpressed in a murine asthma model. Herein, we sought to identify its critical action in Dermatophagoides pteronyssinus peptidase 1 (Der p1)-induced dysfunction of BEAS-2B cells.

METHODS

The levels of circVPS33A, microRNA (miR)-192-5p, and high-mobility group box 1 (HMGB1) were assessed by quantitative real-time PCR (qRT-PCR) or western blot. Actinomycin D treatment and Ribonuclease R (RNase R) assay were used to characterize circVPS33A. Cell viability, proliferation, apoptosis, migration, and invasion were evaluated by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, and transwell assays, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to quantify interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Direct relationship between miR-192-5p and circVPS33A or HMGB1 was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assay.

RESULTS

CircVPS33A was highly expressed in asthma plasma and Der p1-treated BEAS-2B cells. Knocking down circVPS33A suppressed Der p1-induced injury in BEAS-2B cells. CircVPS33A targeted miR-192-5p. MiR-192-5p directly targeted HMGB1, and miR-192-5p-mediated repression of HMGB1 alleviated Der p1-driven cell injury. Furthermore, circVPS33A modulated HMGB1 expression through miR-192-5p.

CONCLUSION

Our findings demonstrated that circVPS33A regulated house dust mite-induced injury in human bronchial epithelial cells at least partially depending on the modulation of the miR-192-5p/HMGB1 axis.

Minimizing Ischemia Reperfusion Injury in Xenotransplantation

The recent dramatic advances in preventing "initial xenograft dysfunction" in pig-to-non-human primate heart transplantation achieved by minimizing ischemia suggests that ischemia reperfusion injury (IRI) plays an important role in cardiac xenotransplantation. Here we review the molecular, cellular, and immune mechanisms that characterize IRI and associated "primary graft dysfunction" in allotransplantation and consider how they correspond with "xeno-associated" injury mechanisms. Based on this analysis, we describe potential genetic modifications as well as novel technical strategies that may minimize IRI for heart and other organ xenografts and which could facilitate safe and effective clinical xenotransplantation.

Akt-independent effects of triciribine on ACE2 expression in human lung epithelial cells: Potential benefits in restricting SARS-CoV2 infection

The severe acute respiratory syndrome coronavirus 2 that causes coronavirus disease 2019 (COVID-19) binds to the angiotensin-converting enzyme 2 (ACE2) to gain cellular entry. Akt inhibitor triciribine (TCBN) has demonstrated promising results in promoting recovery from advanced-stage acute lung injury in preclinical studies. In the current study, we tested the direct effect of TCBN on ACE2 expression in human bronchial (H441) and lung alveolar (A549) epithelial cells. Treatment with TCBN resulted in the downregulation of both messenger RNA and protein levels of ACE2 in A549 cells. Since HMGB1 plays a vital role in the inflammatory response in COVID-19, and because hyperglycemia has been linked to increased COVID-19 infections, we determined if HMGB1 and hyperglycemia have any effect on ACE2 expression in lung epithelial cells and whether TCBN has any effect on reversing HMGB1- and hyperglycemia-induced ACE2 expression. We observed increased ACE2 expression with both HMGB1 and hyperglycemia treatment in A549 as well as H441 cells, which were blunted by TCBN treatment. Our findings from this study, combined with our previous reports on the potential benefits of TCBN in the treatment of acute lung injury, generate reasonable optimism on the potential utility of TCBN in the therapeutic management of patients with COVID-19.

Potential effects of HMGB1 on viral replication and virus infection-induced inflammatory responses: A promising therapeutic target for virus infection-induced inflammatory diseases

Inflammatory responses, characterized by the overproduction of numerous proinflammatory mediators by immune cells, is essential to protect the host against invading pathogens. Excessive production of proinflammatory cytokines is a key pathogenic factor accounting for severe tissue injury and disease progression during the infection of multiple viruses, which are therefore termed as "cytokine storm". High mobility group box 1 (HMGB1), a ubiquitous DNA-binding protein released either over virus-infected cells or activated immune cells, may act as a proinflammatory cytokine with a robust capacity to potentiate inflammatory response and disease severity. Moreover, HMGB1 is a host factor that potentially participates in the regulation of viral replication cycles with complicated mechanisms. Currently, HMGB1 is regarded as a promising therapeutic target against virus infection. Here, we provide an overview of the updated studies on how HMGB1 is differentially manipulated by distinct viruses to regulate viral diseases.

Microbiota-gut-brain axis and Alzheimer's disease: Implications of the blood-brain barrier as an intervention target

The microbiota-gut-brain axis has emerged as a focal point of biomedical research. Alterations of gut microbiota are involved in not only various immune/inflammatory disorders but also neurological disorders including Alzheimer's disease (AD). The initial stage of the involvement of gut microbiota in the pathogenesis of AD may be the dysfunction of the blood-brain barrier (BBB). Gut microbiota-derived products in the circulation can worsen the BBB integrity, easily cross the disrupted BBB and enter the brain to promote pathological changes in AD. In this review, we first summarize the current evidence of the associations among gut microbiota, AD, and BBB integrity. We then discuss the mechanism of gut microbiota on BBB dysfunction with a focus on bacteria-derived lipopolysaccharide and exosomal high-mobility group box 1. Novel insights into the modification of the BBB as an intervention approach for AD are highlighted as well.

HMGB1 released from nociceptors mediates inflammation

Inflammation, the body's primary defensive response system to injury and infection, is triggered by molecular signatures of microbes and tissue injury. These molecules also stimulate specialized sensory neurons, termed nociceptors. Activation of nociceptors mediates inflammation through antidromic release of neuropeptides into infected or injured tissue, producing neurogenic inflammation. Because HMGB1 is an important inflammatory mediator that is synthesized by neurons, we reasoned nociceptor release of HMGB1 might be a component of the neuroinflammatory response. In support of this possibility, we show here that transgenic nociceptors expressing channelrhodopsin-2 (ChR2) directly release HMGB1 in response to light stimulation. Additionally, HMGB1 expression in neurons was silenced by crossing synapsin-Cre (Syn-Cre) mice with floxed HMGB1 mice (HMGB1f/f). When these mice undergo sciatic nerve injury to activate neurogenic inflammation, they are protected from the development of cutaneous inflammation and allodynia as compared to wild-type controls. Syn-Cre/HMGB1fl/fl mice subjected to experimental collagen antibody-induced arthritis, a disease model in which nociceptor-dependent inflammation plays a significant pathological role, are protected from the development of allodynia and joint inflammation. Thus, nociceptor HMGB1 is required to mediate pain and inflammation during sciatic nerve injury and collagen antibody-induced arthritis.

HMGB1-TIM3-HO1: A New Pathway of Inflammation in Skin of SARS-CoV-2 Patients? A Retrospective Pilot Study

The SARS-CoV-2 pandemic has completely disrupted the health systems of the entire planet. From the earliest months, it became increasingly clear that in addition to affecting the upper airways and lungs, there were other organs that could be affected. Among these, the skin became a real "sentinel signal" to be able to even suspect COVID-19. Background: this study deals with a little-explored issue for now: the study of skin immunopathology in SARS-CoV-2 positive subjects ascertained using the most reliable methods available. Methods: we used skin biopsy samples from SARS-CoV-2 positive and negative patients, studying morphology (Hematoxylin-Eosin), T lymphocyte population (CD4 and CD8), three markers such as HMGB-1, TIM-3 and HO-1 by immunohistochemistry. Results: although the presence of the CD4 and CD8 T population did not differ statistically significantly, we found greater activation and release of HMGB-1 in skin samples from SARS-CoV-2 positive patients, greater immunolabeling for TIM-3 at the level of CD4 and CD8 and a reduced expression of Heme oxygenase 1. Conclusions: these results support the possibility that there is immune deregulation in SARS-CoV-2 positive patients who develop skin manifestations of various kinds.

Plasma HMGB1 levels and physical performance in ICU survivors

PURPOSE

Physical impairment after critical illness is recognized as a part of the post-intensive care syndrome (PICS). About one third of intensive care unit (ICU) survivors suffer from long-term physical disability, yet the underlying pathophysiological mechanisms remain poorly understood. The pro-inflammatory alarmin, high mobility group box 1 (HMGB1), promotes muscle dysfunction in experimental models, and HMGB1 stays elevated in some patients after ICU discharge. Accordingly, we investigated the relationship between HMGB1 plasma levels and physical performance in ICU survivors.

METHODS

Prospective cohort study of 100 ICU survivors from the general ICU at the Karolinska University Hospital, Sweden. Patients returned for follow up at 3 (58 patients) and 6 months (51 patients) after ICU discharge. Blood samples were collected, and a 6-minute walk test (6-MWT), a handgrip-strength test (HST), and a timed-stands test (TST) were performed.

RESULTS

Compared to reference values of the different physical tests, 16% of patients underperformed at all tests at 3 months and 12% at 6 months. All test results, except hand-grip strength left, improved significantly over the follow-up period (P < .05). There was no significant association between plasma HMGB1 levels at 3 and 6 months and scores on the three tests (6-MWT, TST, and HST) (P = .50-0.69).

CONCLUSION

In this follow-up study of ICU survivors, we found no significant association between plasma HMGB1 levels and physical performance. Additional follow-up studies of HMGB1 plasma levels and muscle function in ICU survivors are still warranted.

EDITORIAL COMMENT

HMGB-1, a marker of cell damage and activation, is known to increase in ICU patients. In study participants at 3- to 6-month post-ICU stay, HMGB-1 levels were still elevated, although no association to the primary outcome, physical performance, was found. Mechanisms for failure to recover physical performance post-ICU remain unclear, and investigations into cause of post-intensive care syndrome need to continue.

TRIAL REGISTRATIONS

ClinicalTrials.gov identifier NCT02914756.

Leukocyte-Derived High-Mobility Group Box 1 Governs Hepatic Immune Responses to Listeria monocytogenes

High-mobility group box 1 (HMGB1) is a nucleoprotein with proinflammatory functions following cellular release during tissue damage. Moreover, antibody-mediated HMGB1 neutralization alleviates lipopolysaccharide (LPS)-induced shock, suggesting a role for HMGB1 as a superordinate therapeutic target for inflammatory and infectious diseases. Recent genetic studies have indicated cell-intrinsic functions of HMGB1 in phagocytes as critical elements of immune responses to infections, yet the role of extracellular HMGB1 signaling in this context remains elusive. We performed antibody-mediated and genetic HMGB1 deletion studies accompanied by in vitro experiments to discern context-dependent cellular sources and functions of extracellular HMGB1 during murine bloodstream infection with Listeria monocytogenes. Antibody-mediated neutralization of extracellular HMGB1 favors bacterial dissemination and hepatic inflammation in mice. Hepatocyte HMGB1, a key driver of postnecrotic inflammation in the liver, does not affect Listeria-induced inflammation or mortality. While we confirm that leukocyte HMGB1 deficiency effectuates disseminated listeriosis, we observed no evidence of dysfunctional autophagy, xenophagy, intracellular bacterial degradation, or inflammatory gene induction in primary HMGB1-deficient phagocytes or altered immune responses to LPS administration. Instead, we demonstrate that mice devoid of leukocyte HMGB1 exhibit impaired hepatic recruitment of inflammatory monocytes early during listeriosis, resulting in alterations of the transcriptional hepatic immune response and insufficient control of bacterial dissemination. Bone marrow chimera indicate that HMGB1 from both liver-resident and circulating immune cells contributes to effective pathogen control. Conclusion: Leukocyte-derived extracellular HMGB1 is a critical cofactor in the immunologic control of bloodstream listeriosis. HMGB1 neutralization strategies preclude an efficient host immune response against Listeria.

Magnoflorine Alleviates "M1" Polarized Macrophage-Induced Intervertebral Disc Degeneration Through Repressing the HMGB1/Myd88/NF-κB Pathway and NLRP3 Inflammasome

Intervertebral disc degeneration (IDD) is related to the deterioration of nucleus pulposus (NP) cells due to hypertrophic differentiation and calcification. The imbalance of pro-inflammatory (M1 type) and anti-inflammatory (M2 type) macrophages contributes to maintaining tissue integrity. Here, we aimed to probe the effect of Magnoflorine (MAG) on NP cell apoptosis mediated by “M1” polarized macrophages. THP-1 cells were treated with lipopolysaccharide (LPS) to induce “M1” polarized macrophages. Under the treatment with increasing concentrations of MAG, the expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-18), high mobility group box protein 1 (HMGB1), as well as myeloid differentiation factor 88 (MyD88), nuclear factor kappa B (NF-κB) and NOD-like receptor 3 (NLRP3) inflammasomes in THP-1 cells were determined. What’s more, human NP cells were treated with the conditioned medium (CM) from THP-1 cells. The NP cell viability and apoptosis were evaluated. Western blot (WB) was adopted to monitor the expression of apoptosis-related proteins (Bax, Caspase3, and Caspase9), catabolic enzymes (MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5), and extracellular matrix (ECM) compositions (collagen II and aggrecan) in NP cells. As a result, LPS evidently promoted the expression of pro-inflammatory cytokines and HMGB1, the MyD88-NF-κB activation, and the NLRP3 inflammasome profile in THP-1 cells, while MAG obviously inhibited the "M1″ polarization of THP-1 cells. After treatment with “M1” polarized THP-1 cell CM, NP cell viability was decreased, while cell apoptosis, the pro-inflammatory cytokines, apoptosis-related proteins, and catabolic enzymes were distinctly up-regulated, and ECM compositions were reduced. After treatment with MAG, NP cell damages were dramatically eased. Furthermore, MAG dampened the HMGB1 expression and inactivated the MyD88/NF-κB pathway and NLRP3 inflammasome in NP cells. In conclusion, this study confirmed that MAG alleviates “M1” polarized macrophage-mediated NP cell damage by inactivating the HMGB1-MyD88-NF-κB pathway and NLRP3 inflammasome, which provides a new reference for IDD treatment.

Tuning Monocytes and Macrophages for Personalized Therapy and Diagnostic Challenge in Rheumatoid Arthritis

Monocytes/macrophages play a central role in chronic inflammatory disorders, including rheumatoid arthritis (RA). Activation of these cells results in the production of various mediators responsible for inflammation and RA pathogenesis. On the other hand, the depletion of macrophages using specific antibodies or chemical agents can prevent their synovial tissue infiltration and subsequently attenuates inflammation. Their plasticity is a major feature that helps the switch from a pro-inflammatory phenotype (M1) to an anti-inflammatory state (M2). Therefore, understanding the precise strategy targeting pro-inflammatory monocytes/macrophages should be a powerful way of inhibiting chronic inflammation and bone erosion. In this review, we demonstrate potential consequences of different epigenetic regulations on inflammatory cytokines production by monocytes. In addition, we present unique profiles of monocytes/macrophages contributing to identification of new biomarkers of disease activity or predicting treatment response in RA. We also outline novel approaches of tuning monocytes/macrophages by biologic drugs, small molecules or by other therapeutic modalities to reduce arthritis. Finally, the importance of cellular heterogeneity of monocytes/macrophages is highlighted by single-cell technologies, which leads to the design of cell-specific therapeutic protocols for personalized medicine in RA in the future.

Identification of High-Mobility Group Box 1 (HMGB1) Expression as a Potential Predictor of Rejection and Poor Prognosis After Liver Transplantation

BACKGROUND Acute cellular rejection (ACR) frequently occurs after liver transplantation (LT) and can result in permanent damage of the liver allograft. Specific and sensitive biomarkers for predicting and monitoring ACR are vital for guiding post-transplantation care. In the present study, we aimed to investigate the function of high-mobility group box 1 (HMGB1) in predicting ACR and prognosis after LT. MATERIAL AND METHODS A total of 113 LT recipients were enrolled in the study, including 62 patients in an ACR group and 51 patients in a non-rejection group. Using tissues from the 113 patients, HMGB1 expression was examined by immunohistochemistry, and the total score for HMGB1 expression was calculated by multiplying the percentage of immunoreactive cells score and the staining intensity score. We then analyzed the association between HMGB1 expression and clinical features. Finally, the function of HMGB1 in predicting the prognosis of LT was determined using Kaplan-Meier (K-M) survival and Cox multivariate analyses. RESULTS Immunohistochemical staining results demonstrated that the expression of HMGB1 was significantly increased in the ACR group, compared with that in the non-rejection group (P<0.05). Clinical characteristic analysis revealed that high HMGB1 levels were related to ACR (P<0.05). Moreover, K-M survival analysis showed that patients with high HMGB1 expression displayed poorer prognosis (P<0.05). Cox multivariate analysis demonstrated that HMGB1 was an independent prognostic predictor for post-LT survival (odds ratio, 3.283; P=0.008). CONCLUSIONS LT recipients' HMGB1 levels may be a useful and noninvasive biomarker for the prediction of ACR and prognosis after LT.

NF-κB signalling pathways in nucleus pulposus cell function and intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common clinical degenerative disease of the spine. A series of factors, such as inflammation, oxidative stress and mechanical stress, promote degradation of the extracellular matrix (ECM) of the intervertebral discs (IVD), leading to dysfunction and structural destruction of the IVD. Nuclear factor-κB (NF-κB) transcription factor has long been regarded as a pathogenic factor of IDD. Therefore, NF-κB may be an ideal therapeutic target for IDD. As NF-κB is a multifunctional functional transcription factor with roles in a variety of biological processes, a comprehensive understanding of the function and regulatory mechanism of NF-κB in IDD pathology will be useful for the development of targeted therapeutic strategies for IDD, which can prevent the progression of IDD and reduce potential risks. This review discusses the role of the NF-κB signalling pathway in the nucleus pulposus (NP) in the process of IDD to understand pathological NP degeneration further and provide potential therapeutic targets that may interfere with NF-κB signalling for IDD therapy.

HMGB1, neuronal excitability and epilepsy

Epilepsy is a common neurological disease caused by synchronous firing of hyperexcitable neurons. Currently, anti-epileptic drugs remain the main choice to control seizure, but 30% of patients are resistant to the drugs, which calls for more research on new promising targets. Neuroinflammation is closely associated with the development of epilepsy. As an important inflammatory factor, high mobility group protein B1 (HMGB1) has shown elevated expression and an increased proportion of translocation from the nucleus to the cytoplasm in patients with epilepsy and in multiple animal models of epilepsy. HMGB1 can act on downstream receptors such as Toll-like receptor 4 and receptor for advanced glycation end products, thereby activating interleukin (IL)-1β and nuclear factor kappa-B (NF-κB), which in turn act with glutamate receptors such as the N-methyl-D-aspartate (NMDA) receptors to aggravate hyperexcitability and epilepsy. The hyperexcitability can in turn stimulate the expression and translocation of HMGB1. Blocking HMGB1 and its downstream signaling pathways may be a direction for antiepileptic drug therapy. Here, we review the changes of HMGB1-related pathway in epileptic brains and its role in the modulation of neuronal excitability and epileptic seizure. Furthermore, we discuss the potentials of HMGB1 as a therapeutic target for epilepsy and provide perspective on future research on the role of HMGB1 signaling in epilepsy.

Identification of Flap Endonuclease 1 With Diagnostic and Prognostic Value in Breast Cancer

Objective

This study aims to identify the potential value of flap endonuclease 1 (FEN1) as a diagnostic and prognostic marker for breast cancer (BC).

Methods

ELISA was used to measure serum FEN1 levels and ECLIA for CA153 and CEA levels. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic value. Oncomine and UALCAN databases were used to analyze the differences in FEN1 mRNA and protein expressions. Kaplan-Meier Plotter database was then used to assess the prognostic value.

Results

Bioinformatics analysis showed that the FEN1 mRNA and protein levels were significantly higher in BC tissues than in normal tissues. FEN1 was detected in culture medium of BC cell lines and serum FEN1 concentrations were significantly increased in BC patients than in cancer-free individuals. Besides, FEN1 exhibited higher diagnostic accuracy (AUC values>0.800) than CA153 and CEA for distinguishing BC patients, especially early BC, from the healthy and benign groups, or individually. Additionally, serum FEN1 levels were significantly associated with the stage (P=0.001) and lymph invasion (P=0.016), and serum FEN1 levels were increased with the development of BC. Furthermore, serum FEN1 levels were significantly decreased in post-operative patients than in pre-operative patients (P=0.016). Based on the Kaplan-Meier Plotter database, the survival analysis indicated that FEN1 overexpression was associated with poor prognoses for overall survival (OS), relapse-free survival (RFS), and distant metastasis-free survival (DMFS) in BC patients.

Conclusion

FEN1 might be a novel diagnostic and prognostic marker for BC.

Potential neurotoxic activity of diverse molecules released by microglia

Microglia are the professional immune cells of the brain, which support numerous physiological processes. One of the defensive functions provided by microglia involves secretion of cytotoxins aimed at destroying invading pathogens. It is also recognized that the adverse activation of microglia in diseased brains may lead to secretion of cytotoxic molecules, which could be damaging to the surrounding cells, including neurons. Several of these toxins, such as reactive oxygen and nitrogen species, L-glutamate, and quinolinic acid, are widely recognized and well-studied. This review is focused on a structurally diverse group of less-established microglia neurotoxins, which were selected by applying the two criteria that these molecules 1) can be released by microglia, and 2) have the potential to be directly harmful to neurons. The following 11 molecules are discussed in detail: amyloid beta peptides (Aβ); cathepsin (Cat)B and CatD; C-X-C motif chemokine ligand (CXCL)10 and CXCL12 (5-67); high mobility group box (HMGB)1; lymphotoxin (LT)-α; matrix metalloproteinase (MMP)-2 and MMP-9; platelet-activating factor (PAF); and prolyl endopeptidase (PEP). Molecular mechanisms of their release by microglia and neurotoxicity, as well as available evidence implicating their involvement in human neuropathologies are summarized. Further studies on several of the above molecules are warranted to confirm either their microglial origin in the brain or direct neurotoxic effects. In addition, investigations into the differential secretion patterns of neurotoxins by microglia in response to diverse stimuli are required. This research could identify novel therapeutic targets for neurological disorders involving adverse microglial activation.

The role of HMGB1 on TDI-induced NLPR3 inflammasome activation via ROS/NF-κB pathway in HBE cells

To explore the potential role of HMGB1 on TDI-induced NLRP3 inflammasome activation, HBE cells were treated with TDI-HSA conjugate to observe the changes of HMGB1, TLR4, NF-κB, Nrf2 and NLRP3 inflammasome related proteins expressions, ROS release and MMP. NAC, TPCA-1 and Resatorvid pre-treatments were applied to explore the effects of ROS, NF-κB and TLR4 on TDI-induced NLRP3 inflammasome activation. The CRISPR/Cas9 system was used to construct HMGB1 gene knockout HBE cell line and then to explore the role of HMGB1 on TDI-HSA induced NLRP3 inflammasome activation. GL pre-treatment was applied to further confirm the role of HMGB1. Results showed that TDI increased HMGB1, TLR4, P-p65, Nrf2 proteins expressions and ROS release, decreased MMP level and activated NLRP3 inflammasome in HBE cells in a dose dependent manner. NAC, TPCA-1 and Resatorvid pre-treatments decreased the expression of P-p65 and inhibited NLRP3 inflammasome activation. Inhibition of HMGB1 decreased Nrf2 expression and ROS release, improved MMP level and reduced NLRP3 inflammasome activation. GL ameliorated NLRP3 inflammasome activation via inhibiting HMGB1 regulated ROS/NF-κB pathway. These results indicated that HMGB1 was involved in TDI-induced NLRP3 inflammasome activation as a positive regulatory mechanism. The study provided a potential target for early prevention and treatment of TDI-OA.

miR-1287-5p upregulation inhibits the EMT and pro-inflammatory cytokines in LPS-induced human nasal epithelial cells (HNECs)

BACKGROUND

Chronic rhinosinusitis is an intractable symptom that influences daily lives of patients. miR-1287-5p was discovered to play a suppressive role in cervical cancer and HBV-related infection.

PURPOSE

This study investigated the potential role of miR-1287-5p in the in-vitro model of chronic rhinosinusitis.

METHODS

GSE169376 dataset was analyzed and differential miRNAs in nasal mucosa tissues in the chronic rhinosinusitis group were screened out. LPS was used to treat HNECs for 12h, 24h and 48h. Cells underwent LPS treatment after SNAI1 downregulation, miR-1287-5p upregulation or pretreatment of the HMGB1 inhibitor, Glycyrrhizin. RT-PCR was used to measure the RNA expression of miR-1287-5p, SNAI1 and HMGB1. ELISA was used for the detection of IL-6, IL-8, TNF-α changes. Targetscan and starBase were used to predict the targets (SNAI1 and HMGB1) of miR-1287-5p. Dual-luciferase reporter assays were applied to validate this. Western blot was used to analyze the protein changes of Snai1, Vimentin, E-cadherin and HMGB1.

RESULTS

miR-1287-5p was downregulated in the chronic rhinosinusitis group and decreased after LPS treatment in HNECs. The upregulation of miR-1287-5p inhibited IL-6, IL-8, TNF-α and EMT. miR-1287-5p targeted and inhibited SNAI1 and HMGB1. SNAI1 downregulation led to inhibition in EMT while loss of HMGB1 contributed to the decrease in pro-inflammatory cytokines. Knockdown of SNAI1 decreased HMGB1, resulting in the reduction of pro-inflammatory cytokines while HMGB1 inhibitor reduced SNAI1 and thus suppressed the EMT process.

CONCLUSION

miR-1287-5p downregulation was associated with chronic rhinosinusitis and its upregulation inhibited the EMT and inflammation in LPS-induced HNECs through Snai1/HMGB1 pathway.

Reducing Lung ATP Levels and Alleviating Asthmatic Airway Inflammation through Adeno-Associated Viral Vector-Mediated CD39 Expression

Asthma is a chronic respiratory inflammatory disease. Patients usually suffer long-term symptoms and high medical expenses. Extracellular ATP (eATP) has been identified as a danger signal in innate immunity and serves as a potent inflammatory mediator for asthma. Hydrolyzing eATP in lungs might be a potential approach to alleviate asthmatic inflammation. Recombinant adeno-associated virus (rAAV) vectors that contain tissue-specific cap protein have been demonstrated to efficiently transfer exogenous genes into the lung tissues. To test anti-inflammation efficacy of rAAV-mediated CD39 gene transfer, rAAV-CD39 was generated and applied to OVA-mediated asthmatic mice. BALB/c mice were sensitized intraperitoneally and challenged intratracheally with OVA and treated with rAAV-CD39. At the end of procedure, some inflammatory features were examined. rAAV-CD39 treatment downregulated the levels of pulmonary eATP by the rescued expression of CD39. Several asthmatic features, such as airway hyperresponsiveness, eosinophilia, mucin deposition, and IL-5/IL-13 production in the lungs were decreased in the rAAV-CD39-treated mice. Reduced IL-5/IL-13 production and increased frequency of CD4⁺FoxP3⁺ regulatory T cells were detected in draining lymph nodes of rAAV-CD39 treated mice. This evidence suggested that rAAV-mediated CD39 gene transfer attenuated the asthmatic airway inflammation locally. The results suggest that rAAV-CD39 might have therapeutic potential for asthma.

Increased Serum Concentrations of High Mobility Group Box 1 (HMGB1) Protein in Children with Autism Spectrum Disorder

High mobility group box 1 protein (HMGB1) has been suggested to be involved in the immune dysfunction and inflammation reported in autism spectrum disorder (ASD). We aimed to assess HMGB1 serum concentrations (SCs) in high-functioning ASD children compared to typically developing (TD) controls and to explore their associations with the autism spectrum quotient (AQ), the empathy quotient (EQ), and the systemizing quotient (SQ). The study involved 42 ASD children and 38 TD children, all-male, aged between 6.1 and 13.3 years old. HMGB1 SCs were measured by enzyme-linked immunosorbent assay (ELISA). Groups were comparable regarding age, general IQ, birth weight, and maternal age at birth. ASD children showed significantly higher HMGB1 SCs compared to TD children (1.25 ± 0.84 ng/mL versus 1.13 ± 0.79 ng/mL, respectively, p = 0.039). The Spearman’s rho revealed that HMGB1 SCs were positively correlated with the AQ attention to detail subscale (rs = 0.46, p = 0.045) and with the SQ total score (rs = 0.42, p = 0.04) in the ASD group. These results show that HMGB1 serum concentrations are altered in ASD children, and suggest that inflammatory processes mediated by HMGB1 may be associated with specific cognitive features observed in ASD.

Role of Atypical Chemokines and Chemokine Receptors Pathways in the Pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) represents a heightened inflammatory response in the lung generally resulting from tobacco smoking-induced recruitment and activation of inflammatory cells and/or activation of lower airway structural cells. Several mediators can modulate activation and recruitment of these cells, particularly those belonging to the chemokines (conventional and atypical) family. There is emerging evidence for complex roles of atypical chemokines and their receptors (such as high mobility group box 1 (HMGB1), antimicrobial peptides, receptor for advanced glycosylation end products (RAGE) or toll-like receptors (TLRs)) in the pathogenesis of COPD, both in the stable disease and during exacerbations. Modulators of these pathways represent potential novel therapies for COPD and many are now in preclinical development. Inhibition of only a single atypical chemokine or receptor may not block inflammatory processes because there is redundancy in this network. However, there are many animal studies that encourage studies for modulating the atypical chemokine network in COPD. Thus, few pharmaceutical companies maintain a significant interest in developing agents that target these molecules as potential antiinflammatory drugs. Antibody-based (biological) and small molecule drug (SMD)-based therapies targeting atypical chemokines and/or their receptors are mostly at the preclinical stage and their progression to clinical trials is eagerly awaited. These agents will most likely enhance our knowledge about the role of atypical chemokines in COPD pathophysiology and thereby improve COPD management.

Class IIa HDAC Downregulation Contributes to Surgery-Induced Cognitive Impairment Through HMGB1-Mediated Inflammatory Response in the Hippocampi of Aged Mice

Objective

Perioperative neurocognitive disorders (PND) are a common complication in the elderly. Histone deacetylases (HDACs) are a class of enzymes that control the acetylation status of intracellular proteins. Thus, we explored whether HDACs trigger the release of high mobility group box 1 (HMGB1) through altering the acetylation status in the hippocampi of aged mice.

Materials and Methods

The effect of the Class IIa HDAC in PND was explored using an in vivo form of splenectomy. Sixteen-month-old healthy male C57BL/6J mice were randomly divided into five groups: control, anesthesia plus sham surgery, anesthesia plus splenectomy, LMK235 treatment, and PBS treatment. The hippocampi were harvested on either first, third, or seventh postoperative day. Cognitive function was assessed via a Morris water maze (MWM) test. Quantitative RT-PCR, Western blots and ELISAs were carried out to assess the targeted gene expression at transcriptional and translational levels.

Results

Splenectomy led to a significant deficiency in spatial memory acquisition, marked decreases in mRNA and protein levels of HDAC4 and HDAC5 in the hippocampus, and increases in the levels of total HMGB1 and acetylated HMGB1. In a similar fashion to splenectomy, treatment with the HDAC4/5 inhibitor LMK235 produced impaired spatial memory and an increase in the expression of HMGB1 and its acetylated counterpart in the hippocampus.

Conclusion

These results suggest that surgery leads to PND through class IIa HDAC downregulation-triggered HMGB1 release in hippocampus of aged mice. HDACs may be a potential therapeutic target for postoperative cognitive dysfunction.

Pretreatment with Propofol Reduces Pulmonary Injury in a Pig Model of Intestinal Ischemia-Reperfusion via Suppressing the High-Mobility Group Box 1 Protein (HMGB1)/Toll-Like Receptor 4 (TLR4)/Protein Kinase R (PKR) Signaling Pathway

BACKGROUND Propofol improves rodent pulmonary injury after intestinal ischemia-reperfusion (IIR). However, its effect and underlying mechanisms in large animals remain unclear. Here, we examined whether pretreatment with propofol could relieve lung injury during IIR in pigs, then investigated the underlying mechanism. MATERIAL AND METHODS A porcine model of IIR-induced lung injury was built by clamping the super mesenteric artery for 2 h and loosening the clamp for 4 h. Randomized grouping was used, and pigs were assigned to a sham-operated group, an IIR with saline pretreatment group, and an IIR with propofol pretreatment group. Pulmonary histopathologic changes, permeability, and oxygenation were assessed to evaluate the effect of propofol. We assessed levels of methane dicarboxylic aldehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO), high-mobility group box 1 protein (HMGB1), Toll-like receptor 4 (TLR4), and double-stranded RNA activated protein kinase R (PKR) to investigate the underlying mechanism. RESULTS IIR caused severe lung damage, including morphological changes, high permeability, airway resistance, low static compliance, hypoxemia, and acidemia. Pulmonary and plasma MDA content and MPO activity increased, whereas SOD activity decreased. The HMGB1/TLR4/PKR signaling pathway was activated following IIR. Pretreatment with propofol markedly attenuated lung injury (such as reducing the lung edema and permeability), increased MDA content and MPO activity, and restored SOD activity induced by IIR, accompanied by inhibiting the effect of the HMGB1/TLR4/PKR signaling pathway. CONCLUSIONS IIR caused acute lung injury in pigs. Pretreatment with propofol alleviated the lung injury, which was related to its suppression of the HMGB1/TLR4/PKR signaling pathway.

The Role of Autophagy in Hypoxia-Induced Neuroinflammation

Autophagy is a critical cytoprotective mechanism that takes a hand in innate or adaptive immune responses. Hypoxia is a common pathophysiological mechanism that can lead to systemic pathological reactions. In recent years, the impact of hypoxia on the central nervous system has attracted more attention. In the past, autophagy was thought to be directly involved in the apoptosis of nerve cells under hypoxia. An increasing amount of evidence shows that the neuroinflammatory response plays an indispensable role in the neural damage caused by hypoxia. There are many mechanisms related to the neuroinflammatory response induced by hypoxia, among which autophagy is an important aspect, but the role of autophagy is still unclear. This article focuses on how autophagy flux of central immune cells is modified under hypoxic conditions, and how this autophagy affects neuroinflammatory response.

Value of HMGB1 expression for assessing gastric cancer severity: a systematic meta-analysis

OBJECTIVE

To evaluate the clinical value of high mobility group box-1 (HMGB1) expression levels in patients with gastric cancer.

METHODS

Articles published from January 2000 to August 2022 were searched using PubMed, Google Scholar and Science Direct, Springer, Wiley and NIH to evaluate the clinicopathological significance of HMGB1 expression in gastric cancer.

RESULTS

A total of 156 publications were selected, of which six studies, comprising 846 patients, met the criteria for inclusion in this study. Forest plots of clinicopathological characteristics indicated that HMGB1 expression was not associated with age (odds ratio (OR) = 1.07, 95% confidence interval (CI): 0.89-1.28), sex (OR = 0.90, 95% CI: 0.81-1.00), TNM (OR = 1.39, 95% CI: 0.82-2.37), N stage (OR = 1.42, 95% CI: 0.97-2.07), or tumor differentiation (OR = 0.96, 95% CI: 0.71-1.29), but was highly correlated with pT stage (OR = 1.56, 95% CI: 1.17-2.07). Funnel plots showed no significant publication bias in the included studies in terms of age, sex, TNM, pT stage, N stage, or tumor differentiation.

CONCLUSION

HMGB1 expression was significantly correlated with tumor pT stage, but not with age, sex, TNM stage, tumor N stage, tumor differentiation, or lymphatic metastasis in patients with GC.

Upregulated HMGB1 levels in maternal-fetal interface of patients with unexplained recurrent spontaneous abortion from different sources

OBJECTIVE

To investigate the expression and sources of high mobility group box 1 (HMGB1) protein in the maternal-fetal interface of patients with unexplained recurrent spontaneous abortion (URSA), and further to verify the role of HMGB1 in the etiology of URSA.

METHODS

55 women at early pregnancy with URSA and 55 women undergoing selective termination of normal early pregnancy as control were included. The abortion tissues including villi and decidua were collected. The expression of HMGB1, CD45, CK7, and vimentin in abortion tissues was detected, and the localization and sources of HMGB1 were analyzed.

RESULTS

Infiltrating immune cells and expression of HMGB1 were significantly increased in villi and decidua in URSA group compared with those in the control group. In the URSA group, HMGB1 was colocalized with the CD45-labeled immune cells, and it was more obvious in decidua than in villi; in addition, HMGB1 was colocalized with the vimentin-labeled decidual stromal cells, but not with the CK7- labeled villous epithelial cells.

CONCLUSION

High expression of HMGB1 in the maternal-fetal interface in URSA patients was actively secreted by the infiltrating immune cells, and decidual stromal cells may passively release HMGB1 during necrosis.

HMGB1-TLR4-IL-23-IL-17A axis accelerates renal ischemia-reperfusion injury via the recruitment and migration of neutrophils

Renal ischemia-reperfusion injury (IRI) is an important cause of setting off acute kidney injury. Neutrophil-mediated immunomodulation has a pivotal role in the evolving of IRI. The HMGB1-TLR4-IL-23-IL-17A axis gives rise to neutrophil activation. Therefore, in the study, the role of the HMGB1-TLR4-IL-23-IL-17A axis in IRI was evaluated. Cell viability, inflammation, apoptosis, oxidative stress, survival, renal function and pathology, and the activation of macrophages and neutrophils were measured. Moreover, we evaluated the acetylation, translocation, and secretion of HMGB1 as well as levels of TLR-4, IL-23, IL-17A, and neutrophil chemokines (KC, LIX, and MIP-2). In vivo, anti-HMGB1 antibody decreased the acetylation, translocation, and secretion of HMGB1, reduced the expression of TLR-4, IL-23, IL-17A, KC, LIX, and MIP-2, alleviated the activation of macrophages and neutrophils, improved the survival rate and renal dysfunction, and decreased inflammation, apoptosis, oxidative stress, and pathological injury of the kidney. However, the intervention with recombinant HMGB1(R-HMGB1) significantly abolish the above effect of anti-HMGB1 in IRI. Neutralization IL-23 or IL-17A can alleviated the neutrophils mediated renal dysfunction by suppressing inflammation, apoptosis, and oxidative stress in IRI. In vitro, we confirmed that hypoxic/deoxygenation (H/R) induces the secretion of HMGB1 though acetylation on HK-2 and HMGB1 promotes the secretion of IL-23 in a HMGB1/TLR-4-dependent manner on macrophages. Together, these results implied that the HMGB1-TLR4-IL-23-IL-17A axis regulates inflammation, oxidative stress, apoptosis, and renal injury in IRI by promoting the recruitment and migration of neutrophils.

Diabetes, inflammation, and the adiponectin paradox: Therapeutic targets in SARS-CoV-2

Aging and pre-existing conditions in older patients increase severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) severity and its complications, although the causes remain unclear. Apart from acute pulmonary syndrome, Coronavirus 2019 (COVID-19) can increasingly induce chronic conditions. Importantly, SARS-CoV-2 triggers de novo type 2 diabetes mellitus (T2DM) linked to age-associated cardiovascular disease (CVD), cancers, and neurodegeneration. Mechanistically, SARS-CoV-2 induces inflammation, possibly through damage-associated molecular pattern (DAMP) signaling and ‘cytokine storm,’ causing insulin resistance and the adiponectin (APN) paradox, a phenomenon linking metabolic dysfunction to chronic disease. Accordingly, preventing the APN paradox by suppressing APN-related inflammatory signaling might prove beneficial. A better understanding could uncover novel therapies for SARS-CoV-2 and its chronic disorders.

Targeting HMGB1 inhibits T-2 toxin-induced neurotoxicity via regulation of oxidative stress, neuroinflammation and neuronal apoptosis

T-2 toxin, a food-derived mycotoxin, has been identified as a neurotoxin. Nonetheless, T-2 toxin-induced neuroinflammation has never been revealed. As an important therapeutic target for inflammatory diseases and cancers, the role of high mobility group B1 (HMGB1) in mycotoxin-mediated neurotoxicity remains a mystery. In current study, we found that PC12 cells were sensitive to trace amounts of T-2 toxin less than 12 ng/mL, distinguished by decreased cell viability and increased release of lactate dehydrogenase (LDH). Oxidative stress and mitochondrial damage were observed in PC12 cells, manifested as accumulation of oxidative stress products, up-regulation of Nrf2/HO-1 pathway and decrease of mitochondrial membrane potential (MMP), leading to mitochondria-dependent apoptosis. Meanwhile, we first discovered that tiny amounts of T-2 toxin triggered neuroinflammation directly, including raising the expression and translocation of NF-κB and promoting secretion of proinflammatory cytokines such as TNF-α, IL-6, IL-8 and IL-1β. Most interestingly, the increased of HMGB1 was detected both inside and outside the cells. Conversely, HMGB1 siRNA reduced T-2 toxin-mediated oxidative stress, apoptosis and neuroinflammatory outbreak, accompanied by lessened caspase-3 and caspase-9, and decreased secretion of pro-inflammatory cytokines. Taken together, T-2 toxin-stimulated PC12 cells simultaneously displayed apoptosis and inflammation, whereas HMGB1 played a critical role in these neurotoxic processes.

LincRNA-EPS alleviates severe acute pancreatitis by suppressing HMGB1-triggered inflammation in pancreatic macrophages

Acute pancreatitis (AP), an inflammatory disorder of the pancreas with a high hospitalization rate, frequently leads to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). However, therapeutic targets for effective treatment and early intervention of AP are still urgently required to be identified. Here, we have observed that the expression of pancreatic lincRNA-EPS, a long intergenic non-coding RNA, is dynamically changed during both caerulein-induced AP (Cer-AP) and sodium taurocholate-induced severe AP (NaTc-SAP). The expression pattern of lincRNA-EPS is negatively correlated with the typical inflammatory genes such as IL-6, IL-1β, CXCL1, and CXCL2. Further studies indicate that knockout of lincRNA-EPS aggravates the pathological symptoms of AP including more induction of serum amylase and lipase, severe edema, inflammatory cells infiltration and acinar necrosis in both experimental AP mouse models. Besides these intrapancreatic effects, lincRNA-EPS also protects against tissue damages in the extra-pancreatic organs such as lung, liver, and gut in the NaTc-SAP mouse model. In addition, we have observed more serum pro-inflammatory cytokines TNF-α and IL-6 in the lincRNA-EPS^-/- NaTc-SAP mice and more extracellular HMGB1 around injured acinar cells in the pancreas from lincRNA-EPS^-/- NaTc-SAP mice, compared with their respective controls. Pharmacological inhibition of NF- κ B activity by BAY11-7082 significantly abolishes the suppressive effect of lincRNA-EPS on TLR4 ligand-induced inflammatory genes in macrophages. Our study has described a protective role of lincRNA-EPS in alleviating AP and SAP, outlined a novel pathway that lincRNA-EPS suppresses HMGB1-NF- κ B-dependent inflammatory response in pancreatic macrophages and provided a potential therapeutic target for SAP.

Anti-High Mobility Group Box-1 Monoclonal Antibody Attenuates Seizure-Induced Cognitive Decline by Suppressing Neuroinflammation in an Adult Zebrafish Model

Epilepsy is a chronic brain disease afflicting around 70 million global population and is characterized by persisting predisposition to generate epileptic seizures. The precise understanding of the etiopathology of seizure generation is still elusive, however, brain inflammation is considered as a major contributor to epileptogenesis. HMGB1 protein being an initiator and crucial contributor of inflammation is known to contribute significantly to seizure generation via activating its principal receptors namely RAGE and TLR4 reflecting a potential therapeutic target. Herein, we evaluated an anti-seizure and memory ameliorating potential of an anti-HMGB1 monoclonal antibody (mAb) (1, 2.5 and 5 mg/kg, I.P.) in a second hit Pentylenetetrazol (PTZ) (80 mg/kg, I.P.) induced seizure model earlier stimulated with Pilocarpine (400 mg/kg, I.P.) in adult zebrafish. Pre-treatment with anti-HMGB1 mAb dose-dependently lowered the second hit PTZ-induced seizure but does not alter the disease progression. Moreover, anti-HMGB1 mAb also attenuated the second hit Pentylenetetrazol induced memory impairment in adult zebrafish as evidenced by an increased inflection ration at 3 and 24 h trail in T-maze test. Besides, decreased level of GABA and an upregulated Glutamate level was observed in the second hit PTZ induced group, which was modulated by pre-treatment with anti-HMGB1 mAb. Inflammatory responses occurred during the progression of seizures as evidenced by upregulated mRNA expression of HMGB1, TLR4, NF-κB, and TNF-α, in a second hit PTZ group, which was in-turn downregulated upon pre-treatment with anti-HMGB1 mAb reflecting its anti-inflammatory potential. Anti-HMGB1 mAb modulates second hit PTZ induced changes in mRNA expression of CREB-1 and NPY. Our findings indicates anti-HMGB1 mAb attenuates second hit PTZ-induced seizures, ameliorates related memory impairment, and downregulates the seizure induced upregulation of inflammatory markers to possibly protect the zebrafish from the incidence of further seizures through via modulation of neuroinflammatory pathway.