The mechanism of the receptors for advanced glycation end products affecting pericyte detachment from blood vessels after traumatic brain injury / 西安交通大学学报(医学版)

【Objective】 To observe the reactive change of cortical perivascular cells after craniocerebral injury and explore its mechanism. 【Methods】 The controllable cortical impact animal model was used to simulate craniocerebral injury, the expressions of cortical pericyte markers at different time points after trauma were studied by Western blotting, and the biological behavior of vascular pericytes after craniocerebral injury was determined by transmission electron microscopy. Post-traumatic high mobility group box 1 (HMGB1), receptor for advanced glycation end product (RAGE), and nuclear factor κB (NF-κB) were detected by Western blotting. The experimental animals were divided into FPS-ZM1 (a specific RAGE receptor blocker) injection group and wild-type group. Wet and dry brain weight and transmission electron microscopy were used to study the post-traumatic effects of HMGB1-RAGE on pericytes. The primary mouse brain microvascular pericytes were cultured and supplemented with HMGB1 recombinant protein; the cultured pericytes supplemented with FPS-ZM1 were used as the control to explore the effect of HMGB1-RAGE pathway on vascular pericytes in vitro. 【Results】 The expression levels of early post-traumatic cortical pericyte markers platelet-derived growth factor receptor beta (PDGFR-β) and NG2 proteoglycan (NG2) decreased (PDGFR-β, Control vs. CCI 3D P<0.05; NG2, Control vs. CCI 6H P<0.05; Control vs. CCI 1D P<0.05). We found that pericytes were detached from blood vessels, accompanied by local blood-brain barrier opening. The expression of HMGB1-RAGE-NF-κB signaling pathway was increased in the early cortex after trauma (HMGB1, Control vs. CCI 6H P<0.05, Control vs. CCI 1D P<0.05; RAGE, Control vs. CCI 6H P<0.05, Control vs. CCI 1D P<0.05, Control vs. CCI 3D P<0.05, Control vs. CCI 5D P<0.05, Control vs. CCI 7D P<0.05; NF-κB, Control vs. CCI 6H P<0.05, Control vs. CCI 1D P<0.05). After blocking the binding of RAGE with the ligand, cortical edema was reduced (CCI 6H P<0.05, CCI 1D P<0.05), and neurovascular unit damage was reduced. HMGB1 recombinant protein could increase the migration ability of cultured pericytes (Control vs. HMGB1 P<0.05, Control vs. HMGB1+FPS-ZM1 P<0.05), and could be reversed by FPS-ZM1 (HMGB1 vs. HMGB1+FPS-ZM1 P<0.05). 【Conclusion】 High-level HMGB1 after traumatic brain injury mediates pericytes’ detachment from blood vessels through RAGE on pericytes and leads to the occurrence of local cerebral edema.

Mechanism of Yitangkang in Improving Apoptosis of Skeletal Muscle Cells by Inhibiting AGE/RAGE Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo determine the mechanism of Yitangkang in correcting excessive apoptosis of skeletal muscle cells to improve insulin resistance （IR） by inhibiting the advanced glycation end product （AGE）/receptor for the advanced glycation end product （RAGE） signaling pathway. Method① In vitro experiments. Yitangkang-medicated serum was prepared. C2C12 cells were divided into a blank group， a model group， high-， medium-， and low-dose Yitangkang-medicated serum groups （40， 20， and 10 g·kg-1）， and a RAGE inhibitor group. The IR model was induced by palmitic acid in C2C12 cells except for those in the blank group. After the corresponding intervention methods were conducted，the cell viability and glucose consumption level of each group were determined. In addition，the apoptosis rate was determined using flow cytometry. The mRNA and protein expression levels of the important apoptotic proteins ［B-cell lymphoma 2 （Bcl-2）， Bcl-2-associated X protein （Bax）， p53， cysteinyl aspartate-specific protease-3 （Caspase-3）， and cysteinyl aspartate-specific protease-9 （Caspase-9）］ were determined using Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. ② In vivo experiments. Ninety-six eligible Wistar rats were divided into a blank group， a model group， high-，medium-，and low-dose Yitangkang groups （40， 20， and 10 g·kg-1）， and a western medicine group （pioglitazone hydrochloride，1.35 mg·kg-1）. The IR model was induced using high-glucose and high-fat feed for diabetes combined with intraperitoneal injection of low-dose streptozotocin （STZ） in animals and verified by the hyperinsulinemic-euglycemic clamp （HEC） test. After the model was determined successfully， the rats in each group were given intragastric administration of drugs as required. Terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL） assay was performed to determine the number of positive apoptotic cells in the skeletal muscle tissues of rats in each group，while Real-time polymerase chain reaction（Real-time PCR） and Western blot were performed to determine the mRNA and protein expression levels of the important apoptotic proteins Bcl-2， Bax， p53， Caspase-3， and Caspase-9. Result① In vitro experiments. compared with the blank group， the model groups showed increased apoptosis rate of C2C12 cells and decreased cell viability and glucose consumption （P<0.01）. Compared with the model group， the Yitangkang-medicated serum groups and the RAGE inhibitor group showed decreased apoptosis rate of C2C12 cells and increased cell viability and glucose consumption （P<0.01）. Compared with the blank group， the model group showed decreased expression levels of Bcl-2 mRNA and protein in C2C12 cells and increased mRNA and protein expression levels of Bax， p53， Caspase-3， and Caspase-9 （P<0.01）. Compared with the model group， the Yitangkang-medicated serum groups and the RAGE inhibitor group showed increased expression levels of Bcl-2 mRNA and protein in C2C12 cells （P<0.01） and decreased mRNA and protein expression levels of Bax， p53， Caspase-3， and Caspase-9 （P<0.05， P<0.01）. ② In vivo experiments. The number of positive apoptotic cells in the skeletal muscle tissues of rats in the model group significantly increased as compared with that in the blank group （P<0.01）. The number of positive apoptotic cells in the skeletal muscle tissues of rats in the Yitangkang groups and the western medicine group decreased as compared with that in the model group （P<0.01）. Compared with the blank group， the model group showed decreased expression levels of Bcl-2 mRNA and protein in skeletal muscle tissues of rats and increased mRNA and protein expression levels of Bax， p53， Caspase-3， and Caspase-9 （P<0.01）. Compared with the model group， the Yitangkang groups and the western medicine group showed increased expression levels of Bcl-2 mRNA and protein in skeletal muscle tissues of rats （P<0.01） and decreased mRNA and protein expression levels of Bax， p53， Caspase-3， and Caspase-9 （P<0.05， P<0.01）. The medium-dose Yitangkang showed a similar effect as RAGE inhibitor， and the effect was equivalent to that of pioglitazone hydrochloride. ConclusionYitangkang can inhibit skeletal muscle cell apoptosis by inhibiting the AGE/RAGE signaling pathway.

Effects of C3aR and receptor for advanced glycation end products on bone metabolism in APP/PS1 mice models of Alzheimer′s disease / 中华内分泌代谢杂志

Objective:To investigate the effects of complement C3a receptor(C3aR) and receptor for advanced glycation end product(RAGE) on bone metabolism in APP/PS1 mice model of Alzheimer′s disease.Methods:Alzheimer′s disease model APP/PS1 mice was hybridized with C3aR knockout mice(C3aR -/-), RAGE knockout mice(RAGE -/-) to generate APP/PS1-C3aR -/- and APP/PS1-RAGE -/-, respectively. In vivo, micro computed tomography(Micro-CT) scan, bone tissue osteocalcin immunohistochemical staining, tartrate-resistant acid phosphatase(TRAP) staining and Goldner′s trichrome staining were used to understand the variabilities of bone metabolism between different genotypes of mice; In vitro, bone marrow-derived osteoblast and osteoclast induction cultures were used to understand the effects of C3aR and RAGE on osteoblast and osteoclast differentiation. Results:In in vivo experiments, APP/PS1-C3aR -/- and APP/PS1-RAGE -/- mice showed increased bone mass, increased bone formation, decreased bone resorption, and increased osteoid compared to APP/PS1 mice( P<0.05). In in vitro experiments, bone marrow mesenchymal stem cells(BMSCs) derived from APP/PS1-C3aR -/- and APP/PS1-RAGE -/- mice showed enhanced osteoblast differentiation and elevated expression levels of alkaline phosphatase(ALP) and runt-related transcription factor 2(RUNX2), diminished osteoclast differentiation, and reduced positive TRAP staining( P<0.05). Conclusions:Both C3aR and RAGE are involved in regulating the process of APP/PS1 bone metabolism. Knockout of C3aR and RAGE can improve osteoporosis in APP/PS1, providing a new target for the clinical treatment of Alzheimer′s disease combined with osteoporosis.

Metformin improves implant osseointegration in type 2 diabetic rats through inhibition high mobility group box 1 and receptor for advanced glycation end product / 中华内分泌代谢杂志

Objective:To investigate the effects of metformin on the expression of high mobility group box 1 (HMGB1) and receptor for advanced glycation end product(RAGE) around implants in type 2 diabetic rats and underlying mechanism on bone bonding. To investigate the effect of metformin on osseointegration in non-diabetic rats.Methods:Forty male SD rats aged 6 to 8 weeks were randomly divided into 4 groups by random number table with 10 rats each: normal group (T0 group), normal+ metformin group (T1 group), diabetic group (T2 group), and diabetic+ metformin group (T3 group). After type 2 diabetes model was established in T2 and T3 groups, pure titanium implants were implanted in bilateral tibial epiphyseal of all rats. On the same day, T1 and T3 groups were given 300 mg·kg -1·d -1 metformin, and other groups were gavaged with the same amount of normal saline. At the 4th and 8th week after surgery, 5 rats in each group were randomly sacrificed, and bone structure was examined using HE staining and micro-computed tomography (micro-CT). The expression of related factors was detected with immunohistochemistry and enzyme linked immunosorbent assay. Results:At the 4th and 8th week after surgery, the trabecular bone structure, new bone formation quality, and bone microparameters in T3 group were better than those in T2 group. Compared with T2 group, the expression of HMGB1 and RAGE was decreased, the content of osteocalcin was increased, and the expression of tumor necrosis factor-α was decreased (all P<0.01). 4 weeks after operation, bone volume/tissue volume and trabecular number in T1 group was higher than that in T0 group [(0.569±0.013)% vs (0.523±0.030)%, P=0.014; (1.695±0.059)/mm vs (1.569±0.050)/mm, P=0.007]. 8 weeks after operation, trabecular number in T1 group was higher than that in T0 group [(2.324±0.337)/mm vs (1.882±0.057)/mm, P=0.042]. Compared with T0 group, the content of RAGE in T1 group was significantly decreased [(35.49±2.77)ng/L vs (44.92±7.99)ng/L, P=0.005]. The osteocalcin content in T1 group was significantly higher than that in T0 group [(1.32±0.19)ng/L vs (0.89±0.26)ng/L, P=0.001]. Conclusions:Metformin can reduce the expression of HMGB1 and RAGE in type 2 diabetic rats, which may be one of the mechanisms promoting implant bone binding. Metformin has bone protective effect on non-diabetic rats.

Diabetic nephropathy patients show hyper-responsiveness to N6-carboxymethyllysine

The aim of this study was to evaluate the impact of N6-carboxymethyllysine (CML) on NF-κB gene expression and tumor necrosis factor (TNF) production in diabetic nephropathy. This was an observational study comprised of three groups: diabetic nephropathy (n=30), type II diabetes mellitus (n=28), and healthy volunteers (n=30). Blood samples collected from the study participants were cultured for 24 h in the presence of CML or an appropriate control. After incubation, the cultures were centrifuged to separate the cells from the conditioned media. cDNA was prepared from the cell pellet and used to quantify NF-κB gene expression by quantitative real-time polymerase chain reaction (PCR). The conditioned media were used to measure TNF production by enzyme-linked immunosorbent assay (ELISA). The CML-induced fold change in NF-κB gene expression was significantly different among the study groups (P=5.4×10-5). Also, the CML-induced fold change in TNF levels was significantly different among the three groups (P=4.3×10-8). These results imply that patients with diabetic nephropathy and type II diabetes mellitus showed an elevated response to CML.

A Polypeptide Specifically Binds to RAGE can Alleviate the Destroy of Blood Brain-Barrier caused by Amyloid beta

Background The interaction of the receptor for advanced glycation end product (RAGE) on blood-brain-barrier(BBB) with amyloid β (Aβ) plays an important role in the occurrence and development of AD. RP1 is a RAGEspecific binding peptide, which was discovered in our previous experiments, and it has been proved to beeffective on AD cell model, however, its effects on BBB tight junctions (TJs) and on Aβ transport into the brain isunclear.Methods Immunofluorescence experiment was used to identify whether RP1 bound with RAGE specifically.BEnd3-immortalized mouse brain microvascular endothelial cells were used to construct a BBB model. TEER andFD40 tests were used to confirm the stability of the BBB model, and the colocalization of the RP1 and RAGE onthe surface bEnd3 cells was observed with confocal microscopy.Results We confirmed that RP1 can bind to RAGE specifically in vitro. Functional analyses indicated that RP1 caneffectively alleviate the destroy of TJs of BBB and the decrease of permeability of BBB caused by Aβ. Furthermore,RP1 can competitively inhibit the interaction of Aβ with the RAGE in vitro, and effectively inhibit Aβ transport intothe brain.Conclusion RP1 can inhibit BBB damage induced by Aβ and block RAGE-Aβ interaction effectively, and RP1 canbe a candidate of RAGE inhibitors contributing to AD treatment

Receptors for advanced glycation end products is associated with autophagy in the clear cell renal cell carcinoma

Background: The receptor for advanced glycation end-product (RAGE) was one of the signal transduction receptors. RAGE interacted with various signaling molecules which were involved in human disease processes including tumorigenesis. Previous reports have indicated that RAGE/high-mobility group box 1 (HMGB1) could regulate autophagy in different carcinomas. However, the functional role of RAGE/ HMGB1 in the regulation of clear cell renal cell carcinoma (ccRCC) autophagy remained unrevealed. Methods: Western blot, quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence were used in the present study. Results: In this study, we demonstrated that the levels of RAGE/HMGB1 and autophagic protein LC3, Beclin-1, PI3K were much higher in ccRCC samples than those of in adjacent normal tissues. RAGE and autophagic protein expression was regulated with RAGE/HMGB1 in human RCC cell lines. Conclusion: Our results implicated that RAGE and autophagy played important roles in ccRCC, and RAGE/HMGB1 might serve as a novel therapeutic target for future ccRCC treatment

Up-Regulation of MiR-1915 Inhibits Proliferation, Invasion, and Migration of Helicobacter pylori-Infected Gastric Cancer Cells via Targeting RAGE

PURPOSE: Helicobacter pylori (HP)-infected gastric cancer (GC) is known to be a fatal malignant tumor, but the molecular mechanisms underlying its proliferation, invasion, and migration remain far from being completely understood. Our aim in this study was to explore miR-1915 expression and its molecular mechanisms in regulating proliferation, invasion, and migration of HP-infected GC cells. MATERIALS AND METHODS: Quantitative real-time PCR and western blot analysis were performed to determine miR-1915 and receptor for advanced glycation end product (RAGE) expression in HP-infected GC tissues and gastritis tissues, as well as human gastric mucosal cell line GES-1 and human GC cell lines SGC-7901 and MKN45. CCK8 assay and transwell assay were performed to detect the proliferation, invasion, and migration capabilities. MiR-1915 mimics and miR-1915 inhibitor were transfected into GC cells to determine the target relationship between miR-1915 and RAGE. RESULTS: MiR-1915 was under-expressed, while RAGE was over-expressed in HP-infected GC tissues and GC cells. Over-expressed miR-1915 could attenuate cellular proliferation, invasion, and migration capacities. RAGE was confirmed to be the target gene of miR-1915 by bioinformatics analysis and luciferase reporter assay. Moreover, HP-infected GC cellular proliferation, invasion, and migration were inhibited after treatment with pcDNA-RAGE. CONCLUSION: MiR-1915 exerted tumor-suppressive effects on cellular proliferation, invasion, and migration of HP-infected GC cells via targeting RAGE, which provided an innovative target candidate for treatment of HP-infected GC.

Effects of Dihuang Yinzi on RAGE/ROS/Apoptosis Pathway in SH-SY5Y Cells Induced by Aβ1-42 / 广州中医药大学学报

Objective To investigate the effects of Dihuang Yinzi (DY) on the receptor for advanced glycation end-products(RAGE)/reactive oxygen species(ROS)/apoptosis pathway in SH-SY5Y cells induced by amyloid-beta1-42 (Aβ1-42) oligomer. Methods Firstly, we adopted methyl thiazolyl tetrazolium(MTT) method to detect the cell vitality in fetal bovine serum (FBS) group, blank serum group, and low-, middle- and high- dose DY-containing serum groups, so as to confirm the optimal concentration and treatment time of DY-containing serum. Secondly, we applied MTT method to detect cell vitality and applied Annexin V/propidium iodide (PI) staining method to observe the apoptosis of SH-SY5Y cells treated with 0~20 μmol/L Aβ1-42 for 24 and 48 h, so as toconfirm the optimal concentration and treatment time of Aβ1-42 for establishing Alzheimer's disease (AD) model in vitro. Thirdly, MTT method was used for the detection of cell vitality, and Annexin V/PI staining method was used for detection of the apoptosis of SH-SY5Y cells in blank serum group, model group, western medicine control group and low-, middle-and high-dose DY-containing serum groups, and Dihydroethidium (DHE) method was used for the assay of ROS contents, so as to observe the effect of DY on the recovery of injured SH-SY5Y cells induced by Aβ1-42. Finally, we applied Western blot method to detect the expression level of RAGE in SH-SY5Y cells of blank group, model group and DY-containing serum group; after Aβ1-42-induced SH-SY5Y cells were transfected with RAGE gene, we adopted DHE staining method and Annexin V/PI staining method to detect ROS content and cell apoptotic rate in all of the above groups, so as to observe the effect of DY on SH-SY5Y cell apoptosis and RAGE expression. Results The cell vitalities were increased in low- and middle-dose DY-containing serum groups at 24 h (P < 0.05 or P < 0.01 compared with that in the blank serum group). The conditions for the establishment of AD model in vitro were as follows: the optimal concentration of Aβ1-42 was 5μmol/L, and the treatment time was 24 h. The cell vitalities were significantly enhanced, the cell apoptotic rate and ROS content were significantly lowered in Aβ1-42-induced SH-SY5Y cells of the medication groups(P <0.05 or P < 0.01 compared with those in the model group) , and the cell vitality was the highest and the cell apoptotic rate was the lowest in the middle-dose DY-containing serum group. The RAGE expression level was decreased in Aβ1-42-induced SH-SY5Y cells of the middle-dose DY-containing serum group(P < 0.05 compared with that in the model group) . ROS content and cell apoptotic rate were decreased in Aβ1-42-induced SH-SY5Y cells transfected with RAGE gene in the middle-dose DY-containing serum group (P<0.01). Conclusion DY may play an anti-oxidative role through inhibiting the production of ROS and cell apoptosis, thus to suppress RAGE protein and to achieve the preventive and therapeutic effect for AD.

Protective roles of pulmonary rehabilitation mixture in experimental pulmonary fibrosis in vitro and in vivo

Abnormal high mobility group protein B1 (HMGB1) activation is involved in the pathogenesis of pulmonary fibrosis. Pulmonary rehabilitation mixture (PRM), which combines extracts from eight traditional Chinese medicines, has very good lung protection in clinical use. However, it is not known if PRM has anti-fibrotic activity. In this study, we investigated the effects of PRM on transforming growth factor-β1 (TGF-β1)-mediated and bleomycin (BLM)-induced pulmonary fibrosis in vitro and in vivo. The effects of PRM on TGF-β1-mediated epithelial-mesenchymal transition (EMT) in A549 cells, on the proliferation of human lung fibroblasts (HLF-1) in vitro, and on BLM-induced pulmonary fibrosis in vivo were investigated. PRM treatment resulted in a reduction of EMT in A549 cells that was associated with attenuating an increase of vimentin and a decrease of E-cadherin. PRM inhibited the proliferation of HLF-1 at an IC50 of 0.51 µg/mL. PRM ameliorated BLM-induced pulmonary fibrosis in rats, with reduction of histopathological scores and collagen deposition, and a decrease in α-smooth muscle actin (α-SMA) and HMGB1 expression. An increase in receptor for advanced glycation end-product (RAGE) expression was found in BLM-instilled lungs. PRM significantly decreased EMT and prevented pulmonary fibrosis through decreasing HMGB1 and regulating RAGE in vitro and in vivo. PRM inhibited TGF-β1-induced EMT via decreased HMGB1 and vimentin and increased RAGE and E-cadherin levels. In summary, PRM prevented experimental pulmonary fibrosis by modulating the HMGB1/RAGE pathway.

S100A8 and S100A9 in autoimmune diseases / 国际儿科学杂志

S100A8 and S100A9 are abundantly expressed in neutrophils cytoplasm,they are calciumbinding proteins and they often exist as S100A8/A9 heterodimer.Previous studies have shown that the biological functions of S100A8 and S100A9 are associated with chronic inflammatory diseases and a variety of cancers.They are important to inflammation by binding and activation Toll-like receptor4 (TLR4) and receptor for advanced glycation end products(RAGE),and mediating intracellular inflammatory signaling transduction.This review summarizes the studies on functions and molecular mechanism of S100A8 and S100A9 in autoimmune diseases,which might propose new strategies for diagnosis,treatment and suggested disease activity.