Extracellular High Mobility Group Box 1 Plays a Role in the Effect of Bone Marrow Mononuclear Cell Transplantation for Heart Failure

Transplantation of unfractionated bone marrow mononuclear cells (BMCs) repairs and/or regenerates the damaged myocardium allegedly due to secretion from surviving BMCs (paracrine effect). However, donor cell survival after transplantation is known to be markedly poor. This discrepancy led us to hypothesize that dead donor BMCs might also contribute to the therapeutic benefits from BMC transplantation. High mobility group box 1 (HMGB1) is a nuclear protein that stabilizes nucleosomes, and also acts as a multi-functional cytokine when released from damaged cells. We thus studied the role of extracellular HMGB1 in the effect of BMC transplantation for heart failure. Four weeks after coronary artery ligation in female rats, syngeneic male BMCs (or PBS only as control) were intramyocardially injected with/without anti-HMGB1 antibody or control IgG. One hour after injection, ELISA showed that circulating extracellular HMGB1 levels were elevated after BMC transplantation compared to the PBS injection. Quantitative donor cell survival assessed by PCR for male-specific sry gene at days 3 and 28 was similarly poor. Echocardiography and catheterization showed enhanced cardiac function after BMC transplantation compared to PBS injection at day 28, while this effect was abolished by antibody-neutralization of HMGB1. BMC transplantation reduced post-infarction fibrosis, improved neovascularization, and increased proliferation, while all these effects in repairing the failing myocardium were eliminated by HMGB1-inhibition. Furthermore, BMC transplantation drove the macrophage polarization towards alternatively-activated, anti-inflammatory M2 macrophages in the heart at day 3, while this was abolished by HMGB1-inhibition. Quantitative RT-PCR showed that BMC transplantation upregulated expression of an anti-inflammatory cytokine IL-10 in the heart at day 3 compared to PBS injection. In contrast, neutralizing HMGB1 by antibody-treatment suppressed this anti-inflammatory expression. These data suggest that extracellular HMGB1 contributes to the effect of BMC transplantation to recover the damaged myocardium by favorably modulating innate immunity in heart failure.     

Signaling of High Mobility Group Box 1 (HMGB1) through Toll-like Receptor 4 in Macrophages Requires CD14

High mobility group box 1 (HMGB1) is a DNA-binding protein that possesses cytokinelike, proinflammatory properties when released extracellularly in the C23–C45 disulfide form. HMGB1 also plays a key role as a mediator of acute and chronic inflammation in models of sterile injury. Although HMGB1 interacts with multiple pattern recognition receptors (PRRs), many of its effects in injury models occur through an interaction with toll-like receptor 4 (TLR4). HMGB1 interacts directly with the TLR4/myeloid differentiation protein 2 (MD2) complex, although the nature of this interaction remains unclear. We demonstrate that optimal HMGB1-dependent TLR4 activation in vitro requires the coreceptor CD14. TLR4 and MD2 are recruited into CD14-containing lipid rafts of RAW264.7 macrophages after stimulation with HMGB1, and TLR4 interacts closely with the lipid raft protein GM1. Furthermore, we show that HMGB1 stimulates tumor necrosis factor (TNF)-α release in WT but not in TLR4^−/−, CD14^−/−, TIR domain-containing adapter-inducing interferon-β (TRIF)^−/− or myeloid differentiation primary response protein 88 (MyD88)^−/− macrophages. HMGB1 induces the release of monocyte chemotactic protein 1 (MCP-1), interferon gamma–induced protein 10 (IP-10) and macrophage inflammatory protein 1α (MIP-1α) in a TLR4- and CD14-dependent manner. Thus, efficient recognition of HMGB1 by the TLR4/MD2 complex requires CD14.     

HMGB1对小鼠系膜细胞细胞周期及细胞周期相关蛋白表达的影响

该实验以小鼠系膜细胞MMC为研究对象,以重组HMGB1为刺激物,通过检测细胞周期的变化及细胞PCNA、CyclinD1、CDK4和p16的表达水平,初步探讨HMGB1对系膜细胞的细胞周期及其相关调控因子的影响。选取小鼠系膜细胞MMC为研究对象,随机分为对照组及0.05mg/LHMGB1刺激组,经流式细胞术检测发现HMGB1能够上调小鼠系膜细胞中S期细胞所占比例;免疫细胞化学检测显示,PCNA蛋白在小鼠系膜细胞中的表达上调;通过RT-PCR技术及Western blot技术检测到小鼠系膜细胞中CyclinD1 mRNA和蛋白以及CDK4蛋白的高表达情况,而p16蛋白的表达呈时间依赖性降低。由此可见,HMGB1可能是通过上调CyclinD1/CDK4的表达,并下调p16的表达,促进细胞从G_0/G_1期进入S期,介导了小鼠系膜细胞的异常增殖,可能是HMGB1参与狼疮性肾炎发病的可能机制之一。     

高迁移率族蛋白B1在炎症性疾病中的研究进展

高迁移率族蛋白B1(high mobility group box 1 protein,HMGB1)是广泛存在于真核细胞核内的非组蛋白染色体结合蛋白,因其在聚丙烯酰胺凝胶电泳(PAGE)中迁移速度快而得名。近年来的研究表明,HMGB1作为一种重要的晚期炎症介质,在多种急慢性炎症中均有表达。本文就高迁移率族蛋白B1的结构、释放、致炎作用、与炎症性疾病的关系以及炎症时对高迁移率族蛋白B1的干预措施等方面研究近况做一综述。     

急性肺损伤大鼠肺组织高迁移率族蛋白1的表达及其意义

目的动态观察高迁移率族蛋白1（HGMB1）在失血性休克复合内毒素注射致急性肺损伤（ALl）大鼠肺组织的表达情况,初步探讨HMGB1在ALI发病机制中的作用。方法采取失血性休克复合内毒素注射手段建立ALl大鼠动物模型,采用RT-PCR方法,检测肺组织HMGB1mRNA的表达情况。结果正常大鼠肺组织有少量HMGBlmRNA表达,遭受失血性休克复合内毒素注射打击后,HMGB1mRNA表达迅速升高,至ALI24h达最高峰,随后有所下降,ALl各组大鼠表达水平与正常对照组比较差异均有统计学意义（P〈0．01）。结论正常大鼠肺组织有一定水平HMGBlmRNA的表达,遭受失血性休克及内毒素注射打击后,HMGBlmRNA表达异常增高,可引起过度炎症反应,从而促进ALI的发生与发展。     

Activation of Plant Innate Immunity by Extracellular High Mobility Group Box 3 and Its Inhibition by Salicylic Acid

Damage-associated molecular pattern molecules (DAMPs) signal the presence of tissue damage to induce immune responses in plants and animals. Here, we report that High Mobility Group Box 3 (HMGB3) is a novel plant DAMP. Extracellular HMGB3, through receptor-like kinases BAK1 and BKK1, induced hallmark innate immune responses, including i) MAPK activation, ii) defense-related gene expression, iii) callose deposition, and iv) enhanced resistance to Botrytis cinerea. Infection by necrotrophic B. cinerea released HMGB3 into the extracellular space (apoplast). Silencing HMGBs enhanced susceptibility to B. cinerea, while HMGB3 injection into apoplast restored resistance. Like its human counterpart, HMGB3 binds salicylic acid (SA), which results in inhibition of its DAMP activity. An SA-binding site mutant of HMGB3 retained its DAMP activity, which was no longer inhibited by SA, consistent with its reduced SA-binding activity. These results provide cross-kingdom evidence that HMGB proteins function as DAMPs and that SA is their conserved inhibitor.     

Activated Platelets Interfere with Recruitment of Mesenchymal Stem Cells to Apoptotic Cardiac Cells via High Mobility Group Box 1/Toll-like Receptor 4-mediated Down-regulation of Hepatocyte Growth Factor Receptor MET

Recruitment of mesenchymal stem cells (MSC) following cardiac injury, such as myocardial infarction, plays a critical role in tissue repair and may contribute to myocardial recovery. However, the mechanisms that regulate migration of MSC to the site of tissue damage remain elusive. Here, we demonstrate in vitro that activated platelets substantially inhibit recruitment of MSC toward apoptotic cardiac myocytes and fibroblasts. The alarmin high mobility group box 1 (HMGB1) was released by platelets upon activation and mediated inhibition of the cell death-dependent migratory response through Toll-like receptor (TLR)-4 expressed on the MSC. Migration of MSC to apoptotic cardiac myocytes and fibroblasts was driven by hepatocyte growth factor (HGF), and platelet activation was followed by HMGB1/TLR-4-dependent down-regulation of HGF receptor MET on MSC, thereby impairing HGF-driven MSC recruitment. We identify a novel mechanism by which platelets, upon activation, interfere with MSC recruitment to apoptotic cardiac cells, a process that may be of particular relevance for myocardial repair and regeneration.     

Chlorogenic Acid Attenuates High Mobility Group Box 1 (HMGB1) and Enhances Host Defense Mechanisms in Murine Sepsis

Sepsis is a complex, multifactorial, rapidly progressive disease characterized by an overwhelming activation of the immune system and the countervailing antiinflammatory response. In the current study in murine peritoneal macrophages, chlorogenic acid suppressed endotoxin-induced high mobility group box 1 (HMGB1) release in a concentration-dependent manner. Administration of chlorogenic acid also attenuated systemic HMGB1 accumulation in vivo and prevented mortality induced by endotoxemia and polymicrobial sepsis. The mechanisms of action of chlorogenic acid included attenuation of the increase in toll-like receptor (TLR)-4 expression and suppression of sepsis-induced signaling pathways, such as c-Jun NH₂-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB, which are critical for cytokine release. The protection conferred by chlorogenic acid was achieved through modulation of cytokine and chemokine release, suppression of immune cell apoptosis and augmentation of bacterial elimination. Chlorogenic acid warrants further evaluation as a potential therapeutic agent for the treatment of sepsis and other potentially fatal systemic inflammatory disorders.     

Brassica rapa Polysaccharides Ameliorate CCl4‐Induced Acute Liver Injury in Mice through Inhibiting Inflammatory Apoptotic Response and Oxidative Stress

Brassica rapa L., also called NIUMA, is used empirically in Tibetan medicine for its antioxidant, anti‐inflammatory and antiradiation activities. This study explored the hepatoprotective effects of B. rapa polysaccharides (BRPs) on acute liver injury induced by carbon tetrachloride (CCl₄) in mice and the underlying mechanisms. Mice were treated with CCl₄ after the oral administration of BRPs (55, 110 and 220 mg/kg) or bifendate (100 mg/kg) for 7 days. Blood and liver samples of mice were collected for analysis after 24 h. The ALP, ALT and AST levels and the biological activities of SOD, MDA and GSH?Px were measured. Histopathological changes in the liver were determined through hematoxylin and eosin staining. Moreover, TNF‐α, IL‐1β and IL‐6 expression levels were detected by commercial reagent kits. Finally, Western blot analysis was used to check the relative expression levels of caspase‐3, p‐JAK2 and p‐STAT3. The BRP pre‐treatment significantly decreased the enzymatic activities of ALT, ALP and AST in the serum, markedly increased the activities of SOD and GSH?Px in the liver and reduced the MDA concentration in the liver. BRPs alleviated hepatocyte injury and markedly inhibited the expression of TNF‐α, IL‐1β and IL‐6, also downregulating the CCl₄‐induced hepatic tissue expression of caspase‐3. Furthermore, BRPs inhibited the JAK2/STAT3 signaling pathway in a dose‐dependent manner in the liver. This study demonstrated that BRPs exert hepatoprotective effect against the CCl₄‐induced liver injury via modulating the apoptotic and inflammatory responses and downregulating the JAK2/STAT3 signaling pathway. Therefore, B. rapa could be considered a hepatoprotective medicine.     

Roflumilast N-Oxide Prevents Cytokine Secretion Induced by Cigarette Smoke Combined with LPS through JAK/STAT and ERK1/2 Inhibition in Airway Epithelial Cells

Cigarette smoke is a major cause of chronic obstructive pulmonary disease (COPD). Airway epithelial cells and macrophages are the first defense cells against cigarette smoke and these cells are an important source of pro-inflammatory cytokines. These cytokines play a role in progressive airflow limitation and chronic airways inflammation. Furthermore, the chronic colonization of airways by Gram-negative bacteria, contributes to the persistent airways inflammation and progression of COPD. The current study addressed the effects of cigarette smoke along with lipolysaccharide (LPS) in airway epithelial cells as a representative in vitro model of COPD exacerbations. Furthermore, we evaluated the effects of PDE4 inhibitor, the roflumilast N-oxide (RNO), in this experimental model. A549 cells were stimulated with cigarette smoke extract (CSE) alone (0.4% to 10%) or in combination with a low concentration of LPS (0.1 µg/ml) for 2 h or 24 h for measurement of chemokine protein and mRNAs and 5–120 min for protein phosphorylation. Cells were also pre-incubated with MAP kinases inhibitors and Prostaglandin E₂ alone or combined with RNO, before the addition of CSE+LPS. Production of cytokines was determined by ELISA and protein phosphorylation by western blotting and phospho-kinase array. CSE did not induce production of IL-8/CXCL8 and Gro-α/CXCL1 from A549 cells, but increase production of CCL2/MCP-1. However the combination of LPS 0.1 µg/ml with CSE 2% or 4% induced an important production of these chemokines, that appears to be dependent of ERK1/2 and JAK/STAT pathways but did not require JNK and p38 pathways. Moreover, RNO associated with PGE₂ reduced CSE+LPS-induced cytokine release, which can happen by occur through of ERK1/2 and JAK/STAT pathways. We report here an in vitro model that can reflect what happen in airway epithelial cells in COPD exacerbation. We also showed a new pathway where CSE+LPS can induce cytokine release from A549 cells, which is reduced by RNO.     

PH797804对小鼠急性肝衰竭的保护作用及机制研究

目的:研究PH797804对脂多糖/D-氨基半乳糖氨(Lipopolysaccharide/D-galactosamine, LPS/D-Gal)诱导的急性肝衰竭(Acute liver failure, ALF)小鼠的保护作用及机制。方法:将64只小鼠随机分成四组,每组16只。腹腔注射LPS/D-Gal诱导建立小鼠ALF模型,设立生理盐水对照组(a)、LPS/D-Gal诱导模型组(b)、LPS/D-Gal诱导和PH797804干预组(c)及PH797804处理对照组(d)。观察小鼠48 h内的存活率,检测血清中谷丙转氨酶(ALT)和谷草转氨酶(AST)的含量,HE染色组织切片观察肝脏病理变化,Elisa检测血清中TNF-α和IL-6的表达水平,并对各组小鼠肝组织进行高通量转录组测序以探寻作用机制,采用Real-time PCR法验证测序结果。结果:相比于ALF模型组小鼠,PH797804处理后c组小鼠48 h存活率从20%提高至80%,小鼠肝脏组织病理学异常显著改善,血清中ALT、AST含量较ALF模型组相比显著降低(P0.01),血清中TNF-α和IL-6等促炎细胞因子含量较ALF模型组相比显著降低(P0.01)。RNA测序结果提示PH797804对LPS/D-Gal诱导小鼠ALF的保护作用主要与抑制炎症反应相关。Real-time PCR验证了测序结果的可靠性。结论:PH797804对LPS/D-Gal诱导的小鼠ALF具有保护作用,其作用机制可能与抑制炎症反应有关。     

胶质瘤来源外泌体通过高迁移率族蛋白B1促进胶质瘤干细胞形成

摘要 目的：研究胶质瘤来源外泌体中高迁移率族蛋白B1（HMGB1）对胶质瘤干细胞形成的影响及其意义。方法：使用外泌体提取试剂盒提取原代胶质母细胞瘤来源外泌体,通过透射电子显微镜、纳米粒度电位仪和Western blotting对外泌体进行鉴定;采用Western blotting检测外泌体中HMGB1的表达量;通过qRT-PCR、Western blotting、克隆球计数检测外泌体对胶质瘤干细胞形成的影响;siRNA敲低HMGB1的表达水平,并通过qRT-PCR、Western blotting、克隆球计数检测外泌体中HMGB1对胶质瘤干细胞形成的影响。结果：原代胶质瘤细胞可以分泌外泌体到肿瘤微环境并且外泌体中存在HMGB1;原代胶质瘤细胞来源外泌体可以上调邻近胶质瘤细胞干性相关分子CD133、OCT4、NANOG、SOX2的表达并促进干细胞克隆球的形成;通过siRNA敲低原代胶质瘤细胞HMGB1的表达后,外泌体中HMGB1的含量降低并且外泌体促进胶质瘤干细胞形成的作用减弱。结论：胶质瘤细胞来源外泌体可以通过HMGB1促进胶质瘤干细胞的形成。     

Nephrocystin-1 Forms a Complex with Polycystin-1 via a Polyproline Motif/SH3 Domain Interaction and Regulates the Apoptotic Response in Mammals

Mutations in PKD1, the gene encoding for the receptor Polycystin-1 (PC-1), cause autosomal dominant polycystic kidney disease (ADPKD). The cytoplasmic C-terminus of PC-1 contains a coiled-coil domain that mediates an interaction with the PKD2 gene product, Polycystin-2 (PC-2). Here we identify a novel domain in the PC-1 C-terminal tail, a polyproline motif mediating an interaction with Src homology domain 3 (SH3). A screen for interactions using the PC-1 C-terminal tail identified the SH3 domain of nephrocystin-1 (NPHP1) as a potential binding partner of PC-1. NPHP1 is the product of a gene that is mutated in a different form of renal cystic disease, nephronophthisis (NPHP). We show that in vitro pull-down assays and NMR structural studies confirmed the interaction between the PC-1 polyproline motif and the NPHP1 SH3 domain. Furthermore, the two full-length proteins interact through these domains; using a recently generated model system allowing us to track endogenous PC-1, we confirm the interaction between the endogenous proteins. Finally, we show that NPHP1 trafficking to cilia does not require PC-1 and that PC-1 may require NPHP1 to regulate resistance to apoptosis, but not to regulate cell cycle progression. In line with this, we find high levels of apoptosis in renal specimens of NPHP patients. Our data uncover a link between two different ciliopathies, ADPKD and NPHP, supporting the notion that common pathogenetic defects, possibly involving de-regulated apoptosis, underlie renal cyst formation.     

Carbenoxolone Blocks Endotoxin-Induced Protein Kinase R (PKR) Activation and High Mobility Group Box 1 (HMGB1) Release

The pathogen- and damage-associated molecular patterns (for example, bacterial endotoxin and adenosine 5′-triphosphate [ATP]) activate the double-stranded RNA-activated protein kinase R (PKR) to trigger the inflammasome-dependent high mobility group box 1 (HMGB1) release. Extracellular ATP contributes to the inflammasome activation through binding to the plasma membrane purinergic P2X₇ receptor (P2X₇R), triggering the opening of P2X₇R channels and the pannexin-1 (panx-1) hemichannels permeable for larger molecules up to 900 daltons. It was previously unknown whether panx-1 channel blockers can abrogate lipopolysaccharide (LPS)-induced PKR activation and HMGB1 release in innate immune cells. Here we demonstrated that a major gancao (licorice) component (glycyrrhizin, or glycyrrhizic acid) derivative, carbenoxolone (CBX), dose dependently abrogated LPS-induced HMGB1 release in macrophage cultures with an estimated IC₅₀ ≈ 5 μmol/L. In an animal model of polymicrobial sepsis (induced by cecal ligation and puncture [CLP]), repetitive CBX administration beginning 24 h after CLP led to a significant reduction of circulating and peritoneal HMGB1 levels, and promoted a significant increase in animal survival rates. As did P2X₇R antagonists (for example, oxidized ATP, oATP), CBX also effectively attenuated LPS-induced P2X₇R/panx-1 channel activation (as judged by Lucifer Yellow dye uptake) and PKR phosphorylation in primary peritoneal macrophages. Collectively, these results suggested that CBX blocks LPS-induced HMGB1 release possibly through impairing PKR activation, supporting the involvement of PKR in the regulation of HMGB1 release.     

血清Klotho蛋白、视锥蛋白样蛋白-1、高迁移率族蛋白1与阿尔茨海默病患者认知功能和预后不良的关系

摘要 目的：探讨阿尔兹海默病（AD）患者血清Klotho蛋白、视锥蛋白样蛋白-1（VILIP-1）、高迁移率族蛋白1（HMGB1）与认知功能及预后的关系。方法：选取2019年4月-2021年5月在我院接受治疗的136例AD患者作为AD组,另选取150例同时期在我院进行体检的健康志愿者作为对照组,应用酶联免疫吸附法检测两组血清Klotho蛋白、VILIP-1、HMGB1表达水平,采用简易精神状态检查量表（MMSE）评估两组认知功能,采用Pearson相关性分析以上三指标与MMSE评分之间的关系;AD患者根据治疗1年后的预后情况分为预后良好组（n=74）与预后不良组（n=62）,应用单因素、多因素Logistic回归分析引发AD患者预后不良的危险因素;采用受试者工作特征（ROC）曲线评估血清Klotho蛋白、VILIP-1、HMGB1联合检测对AD患者预后的预测效能。结果：AD组的MMSE评分、血清Klotho蛋白水平显著低于对照组,而血清VILIP-1及HMGB1水平显著高于对照组（均P＜0.05）;Pearson相关性结果显示血清Klotho蛋白水平与MMSE评分之间呈显著正相关（P＜0.05）,而血清VILIP-1、HMGB1水平与MMSE评分之间呈显著负相关（均P＜0.05）;多因素Logistic回归分析显示血清VILIP-1、HMGB1水平升高是引发AD患者预后不良的独立危险因素,而血清Klotho蛋白水平升高是其保护因素（P＜0.05）;ROC曲线显示 Klotho蛋白、VILIP-1、HMGB1联合检测AD患者曲线下面积为0.839,敏感度为80.65%,特异度为83.78%。结论：血清Klotho蛋白、VILIP-1、HMGB1表达水平与AD患者认知功能和预后均具有较强的关联性,临床可以通过联合检测以上三指标辅助评估AD患者的预后。     

Gas Chromatography/Mass Spectrometry-Based Metabolomic Profiling Reveals Alterations in Mouse Plasma and Liver in Response to Fava Beans

Favism is a life-threatening hemolytic anemia resulting from the intake of fava beans by susceptible individuals with low erythrocytic glucose 6-phosphate dehydrogenase (G6PD) activity. However, little is known about the metabolomic changes in plasma and liver after the intake of fava beans in G6PD normal and deficient states. In this study, gas chromatography/mass spectrometry was used to analyze the plasma and liver metabolic alterations underlying the effects of fava beans in C3H- and G6PD-deficient (G6PDx) mice, and to find potential biomarkers and metabolic changes associated with favism. Our results showed that fava beans induced oxidative stress in both C3H and G6PDx mice. Significantly, metabolomic differences were observed in plasma and liver between the control and fava bean treated groups of both C3H and G6PDx mice. The levels of 7 and 21 metabolites in plasma showed significant differences between C3H-control (C3H-C)- and C3H fava beans-treated (C3H-FB) mice, and G6PDx-control (G6PDx-C)- and G6PDx fava beans-treated (G6PDx-FB) mice, respectively. Similarly, the levels of 7 and 25 metabolites in the liver showed significant differences between C3H and C3H-FB, and G6PDx and G6PDx-FB, respectively. The levels of oleic acid, linoleic acid, and creatinine were significantly increased in the plasma of both C3H-FB and G6PDx-FB mice. In the liver, more metabolic alterations were observed in G6PDx-FB mice than in C3H-FB mice, and were involved in a sugar, fatty acids, amino acids, cholesterol biosynthesis, the urea cycle, and the nucleotide metabolic pathway. These findings suggest that oleic acid, linoleic acid, and creatinine may be potential biomarkers of the response to fava beans in C3H and G6PDx mice and therefore that oleic acid and linoleic acid may be involved in oxidative stress induced by fava beans. This study demonstrates that G6PD activity in mice can affect their metabolic pathways in response to fava beans.