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The HMGB1/RAGE axis triggers neutrophil-mediated injury amplification following necrosis.

ABSTRACT: In contrast to microbially triggered inflammation, mechanisms promoting sterile inflammation remain poorly understood. Damage-associated molecular patterns (DAMPs) are considered key inducers of sterile inflammation following cell death, but the relative contribution of specific DAMPs, including high-mobility group box 1 (HMGB1), is ill defined. Due to the postnatal lethality of Hmgb1-knockout mice, the role of HMGB1 in sterile inflammation and disease processes in vivo remains controversial. Here, using conditional ablation strategies, we have demonstrated that epithelial, but not bone marrow-derived, HMGB1 is required for sterile inflammation following injury. Epithelial HMGB1, through its receptor RAGE, triggered recruitment of neutrophils, but not macrophages, toward necrosis. In clinically relevant models of necrosis, HMGB1/RAGE-induced neutrophil recruitment mediated subsequent amplification of injury, depending on the presence of neutrophil elastase. Notably, hepatocyte-specific HMGB1 ablation resulted in 100% survival following lethal acetaminophen intoxication. In contrast to necrosis, HMGB1 ablation did not alter inflammation or mortality in response to TNF- or FAS-mediated apoptosis. In LPS-induced shock, in which HMGB1 was considered a key mediator, HMGB1 ablation did not ameliorate inflammation or lethality, despite efficient reduction of HMGB1 serum levels. Our study establishes HMGB1 as a bona fide and targetable DAMP that selectively triggers a neutrophil-mediated injury amplification loop in the setting of necrosis.

SUBMITTER: Huebener P

PROVIDER: S-EPMC4319429 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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The HMGB1/RAGE axis triggers neutrophil-mediated injury amplification following necrosis.

Huebener Peter P Pradere Jean-Philippe JP Hernandez Celine C Gwak Geum-Youn GY Caviglia Jorge Matias JM Mu Xueru X Loike John D JD Schwabe Robert F RF

The Journal of clinical investigation 20141222 2

In contrast to microbially triggered inflammation, mechanisms promoting sterile inflammation remain poorly understood. Damage-associated molecular patterns (DAMPs) are considered key inducers of sterile inflammation following cell death, but the relative contribution of specific DAMPs, including high-mobility group box 1 (HMGB1), is ill defined. Due to the postnatal lethality of Hmgb1-knockout mice, the role of HMGB1 in sterile inflammation and disease processes in vivo remains controversial. He ...[more]

PMID: 25562324

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Project description:BACKGROUND:Spinal cord injury (SCI) favors a persistent pro-inflammatory macrophages/microglia-mediated response with only a transient appearance of anti-inflammatory phenotype of immune cells. However, the mechanisms controlling this special sterile inflammation after SCI are still not fully elucidated. It is known that damage-associated molecular patterns (DAMPs) released from necrotic cells after injury can trigger severe inflammation. High mobility group box 1(HMGB1), a ubiquitously expressed DNA binding protein, is an identified DAMP, and our previous study demonstrated that reactive astrocytes could undergo necroptosis and release HMGB1 after SCI in mice. The present study aimed to explore the effects and the possible mechanism of HMGB1on macrophages/microglia polarization, as well as the neuroprotective effects by HMGB1 inhibition after SCI. METHODS:In this study, the expression and the concentration of HMGB1 was determined by qRT-PCR, ELISA, and immunohistochemistry. Glycyrrhizin was applied to inhibit HMGB1, while FPS-ZM1 to suppress receptor for advanced glycation end products (RAGE). The polarization of macrophages/microglia in vitro and in vivo was detected by qRT-PCR, immunostaining, and western blot. The lesion area was detected by GFAP staining, while neuronal survival was examined by Nissl staining. Luxol fast blue (LFB) staining, DAB staining, and western blot were adopted to evaluate the myelin loss. Basso-Beattie-Bresnahan (BBB) scoring and rump-height Index (RHI) assay was applied to evaluate locomotor functional recovery. RESULTS:Our data showed that HMGB1 can be elevated and released from necroptotic astrocytes and HMGB1 could induce pro-inflammatory microglia through the RAGE-nuclear factor-kappa B (NF-?B) pathway. We further demonstrated that inhibiting HMGB1 or RAGE effectively decreased the numbers of detrimental pro-inflammatory macrophages/microglia while increased anti-inflammatory cells after SCI. Furthermore, our data showed that inhibiting HMGB1 or RAGE significantly decreased neuronal loss and demyelination, and improved functional recovery after SCI. CONCLUSIONS:The data implicated that HMGB1-RAGE axis contributed to the dominant pro-inflammatory macrophages/microglia-mediated pro-inflammatory response, and inhibiting this pathway afforded neuroprotection for SCI. Thus, therapies designed to modulate immune microenvironment based on this cascade might be a prospective treatment for SCI.

Project description:BACKGROUND:Kawasaki disease (KD) is a common, yet unknown etiology disease in Asian countries, which causes acquired heart disease in childhood. It is characterized by an inflammatory acute febrile vasculitis of medium-sized arteries, particularly the coronary arteries. High-mobility group box-1 protein (HMGB1) is a non-histone chromosomal-binding protein present in the nucleus of eukaryotic cells, which contains 215 amino acid residues. Although the cellular signal transduction mechanisms of HMGB1 are currently unclear, the important role of the receptor for advanced glycation end-products (RAGE), the main receptor for HMGB1 has been reported in detail. The purpose of our study was to verify the mechanism and clinical significance of HMGB1-RAGE in coronary artery injury of Kawasaki disease. METHODS:52 blood samples of patients in KD were collected, and the coronary artery Z score was calculated according to the echocardiographic results. The Z score???2.0 was classified as coronary artery lesions (CAL); otherwise, it was no-coronary artery lesions (NCAL). In addition, the fever group and control group were set. Among them, the fever group were children with fever due to respiratory tract infection at the same time period as KD (heat peak???38.5 ?). The normal group were children at a routine physical examination in the outpatient clinic of Nantong University and the physical examination center of the child care insurance, and there were no infectious diseases and heart diseases. The serum levels of HMGB1, RAGE, and NF-?B in each group were detected by ELISA. The animal model of KD was established using the New Zealand young rabbits. We used RT-qPCR/H&E staining/immunohistochemistry/ELISA and western blot to detect the level of HMGB1/RAGE and NF-?B. RESULTS:In this study, we found that the HMGB1/RAGE/NF-?B axis was elevated in the serum of children with KD. In addition, an animal model of KD was subsequently prepared to examine the pathological changes of the coronary arteries. We found that the serum levels of HMGB1/RAGE/NF-?B in rabbits with KD were significantly higher than those of the control group. Moreover, the lumen diameter of the coronary artery was slightly enlarged, and the wall of the tube became thinner and deformed. In addition, the HMGB1/RAGE/NF-?B levels in the coronary artery were higher in the rabbits with KD in the acute phase. CONCLUSIONS:On the whole, the findings of this study demonstrate that the expression of HMGB1/RAGE/NF-?B is altered at different stages of KD, suggesting that the HMGB1/RAGE/NF-?B signaling pathway plays an important role in vascular injury in KD. The results of this study may have important implications for the early warning of coronary artery lesions in KD.

Project description:AIM: High mobility group box protein 1 (HMGB1) and receptor for the advanced glycation end product (RAGE) play pivotal roles in vascular inflammation and atherosclerosis. The aim of this study was to determine whether the HMGB1-RAGE axis was involved in the actions of simvastatin on vascular inflammation and atherosclerosis in ApoE(-/-) mice. METHODS: Five-week old ApoE(-/-) mice and wild-type C57BL/6 mice were fed a Western diet. At 8 weeks of age, ApoE(-/-) mice were administered simvastatin (50 mg·kg(-1)·d(-1)) or vehicle by gavage, and the wild-type mice were treated with vehicle. The mice were sacrificed at 11 weeks of age, and the atherosclerotic lesions in aortic sinus were assessed with Oil Red O staining. Macrophage migration was determined with scanning EM and immunohistochemistry. Human umbilical vein endothelial cells (HUVECs) were used for in vitro study. Western blots were used to quantify the protein expression of HMGB1, RAGE, vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1). RESULTS: Vehicle-treated ApoE(-/-) mice exhibited significant increases in aortic inflammation and atherosclerosis as well as enhanced expression of HMGB1, RAGE, VCAM-1, and MCP-1 in aortic tissues as compared to the wild-type mice. Furthermore, serum total cholesterol, triglyceride and LDL levels were markedly increased, while serum HDL level was decreased in vehicle-treated ApoE(-/-) mice. Administration with simvastatin in ApoE(-/-) mice markedly attenuated the vascular inflammation and atherosclerotic lesion area, and decreased the aortic expression of HMGB1, RAGE, VCAM-1, and MCP-1. However, simvastatin did not affect the abnormal levels of serum total cholesterol, triglyceride, LDL and HDL in ApoE(-/-) mice. Exposure of HUVECs to HMGB1 (100 ng/mL) markedly increased the expression of HMGB1, RAGE and VCAM-1, whereas pretreatment of the cells with simvastatin (10 μmol/L) blocked the HMGB1-caused changes. CONCLUSION: Simvastatin inhibits vascular inflammation and atherosclerosis in ApoE(-/-) mice, which may be mediated through downregulation of the HMGB1-RAGE axis.

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The HMGB1/RAGE axis triggers neutrophil-mediated injury amplification following necrosis.

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The HMGB1/RAGE axis triggers neutrophil-mediated injury amplification following necrosis.

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