43 research outputs found

    The Role of SDF-1-CXCR4/CXCR7 Axis in the Therapeutic Effects of Hypoxia-Preconditioned Mesenchymal Stem Cells for Renal Ischemia/Reperfusion Injury

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    In vitro hypoxic preconditioning (HP) of mesenchymal stem cells (MSCs) could ameliorate their viability and tissue repair capabilities after transplantation into the injured tissue through yet undefined mechanisms. There is also experimental evidence that HP enhances the expression of both stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7, which are involved in migration and survival of MSCs in vitro, but little is known about their role in the in vivo therapeutic effectiveness of MSCs in renal ischemia/reperfusion (I/R) injury. Here, we evaluated the role of SDF-1-CXCR4/CXCR7 pathway in regulating chemotaxis, viability and paracrine actions of HP-MSCs in vitro and in vivo. Compared with normoxic preconditioning (NP), HP not only improved MSC chemotaxis and viability but also stimulated secretion of proangiogenic and mitogenic factors. Importantly, both CXCR4 and CXCR7 were required for the production of paracrine factors by HP-MSCs though the former was only responsible for chemotaxis while the latter was for viability. SDF-1α expression was upregulated in postischemic kidneys. After 24 h systemical administration following I/R, HP-MSCs but not NP-MSCs were selectively recruited to ischemic kidneys and this improved recruitment was abolished by neutralization of CXCR4, but not CXCR7. Furthermore, the increased recruitment of HP-MSCs was associated with enhanced functional recovery, accelerated mitogenic response, and reduced apoptotic cell death. In addition, neutralization of either CXCR4 or CXCR7 impaired the improved therapeutic potential of HP-MSCs. These results advance our knowledge about SDF-1-CXCR4/CXCR7 axis as an attractive target pathway for improving the beneficial effects of MSC-based therapies for renal I/R

    Gypenoside Attenuates β Amyloid-Induced Inflammation in N9 Microglial Cells via SOCS1 Signaling

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    Reducing β amyloid- (Aβ-) induced microglial activation is believed to be effective in treating Alzheimer’s disease (AD). Microglia can be activated into classic activated state (M1 state) or alternative activated state (M2 state), and the former is harmful; in contrast, the latter is beneficial. Gypenoside (GP) is the major bioactive constituent of Gynostemma pentaphyllum, a traditional Chinese herb medicine. In this study, we hypothesized that GP attenuates Aβ-induced microglial activation by ameliorating microglial M1/M2 states, and the process may be mediated by suppressor of cell signaling protein 1 (SOCS1). In this study, we found that Aβ exposure increased the levels of microglial M1 markers, including iNOS expression, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 releases, and coadministration of GP reversed the increase of M1 markers and enhanced the levels of M2 markers, including arginase-1 (Arg-1) expression, IL-10, brain-derived neurotrophic factor (BDNF), and glial cell-derived neurotrophic factor (GDNF) releases in the Aβ-treated microglial cells. SOCS1-siRNA, however, significantly abolished the GP-induced effects on the levels of microglial M1 and M2 markers. These findings indicated that GP attenuates Aβ-induced microglial activation by ameliorating M1/M2 states, and the process may be mediated by SOCS1

    PRSS8 is Downregulated and Suppresses Tumour Growth and Metastases in Hepatocellular Carcinoma

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    Background: Protease serine 8 (PRSS8), a trypsin-like serine peptidase, has been shown to function as a tumour suppressor in various malignancies. The present study aimed to investigate the expression pattern, prognostic value and the biological role of PRSS8 in human hepatocellular carcinoma (HCC). Methods: PRSS8 expression in 106 HCC surgical specimens was examined by Real-time polymerase chain reaction (PCR) and immunohistochemistry, and its clinical significance was analysed. The role of PRSS8 in cell proliferation, apoptosis and invasion were examined in vitro and in vivo. Results: PRSS8 mRNA and protein expression were decreased in most HCC tumours from that in matched adjacent non-tumour tissues. Low intratumoral PRSS8 expression was significantly correlated with poor overall survival (OS) in patients with HCC (P = 0.001). PRSS8 expression was an independent prognostic factor for OS (hazard ratio [HR] = 1.704, P = 0.009). Furthermore, restoring PRSS8 expression in high metastatic HCCLM3 cells significantly inhibited cell proliferation and invasion. In contrast, silencing PRSS8 expression in non-metastatic HepG2 cells significantly enhanced cell growth and invasion. Moreover, our in vivo data revealed that attenuated PRSS8 expression in HepG2 cells greatly promoted tumour growth, while overexpression of PRSS8 remarkably inhibited tumour growth in an HCCLM3 xenograft model. Enhanced cell growth and invasion ability mediated by the loss of PRSS8 expression was associated with downregulation of PTEN, Bax and E-cadherin and an upregulation in Bcl-2, MMP9 and N-cadherin. Conclusions: Our data demonstrate that PRSS8 may serve as a tumour suppressor in HCC progression, and represent a valuable prognostic marker and potential therapeutic target for HCC

    Grid-based minimization at scale: Feldman-Cousins corrections for light sterile neutrino search

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    High Energy Physics (HEP) experiments generally employ sophisticated statistical methods to present results in searches of new physics. In the problem of searching for sterile neutrinos, likelihood ratio tests are applied to short-baseline neutrino oscillation experiments to construct confidence intervals for the parameters of interest. The test statistics of the form Δχ2 is often used to form the confidence intervals, however, this approach can lead to statistical inaccuracies due to the small signal rate in the region-of-interest. In this paper, we present a computational model for the computationally expensive Feldman-Cousins corrections to construct a statistically accurate confidence interval for neutrino oscillation analysis. The program performs a grid-based minimization over oscillation parameters and is written in C++. Our algorithms make use of vectorization through Eigen3, yielding a single-core speed-up of 350 compared to the original implementation, and achieve MPI data parallelism by employing DIY. We demonstrate the strong scaling of the application at High-Performance Computing (HPC) sites. We utilize HDF5 along with HighFive to write the results of the calculation to file

    A model of regenerative potential of HP-MSCs in repair of I/R-AKI.

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    <p>Chemokine SDF-1 expression is upregulated in postischemic kidneys. HP enhances the expression of both SDF-1 receptors, CXCR4 and CXCR7, in MSCs. Intravenously injected HP-MSCs are recruited to the ischemic kidney and localized within the injured capillaries and in the interstitium through SDF-1α-CXCR4 interaction. The binding of SDF-1 to both CXCR4 and CXCR7 is responsible for the production of paracrine mediators, including VEGF, β-FGF, IGF-1 and HGF that exert mitogenic, anti-apoptotic, pro-angiogenic, and anti-inflammatory effects.</p

    Effects of SDF-1-CXCR4/CXCR7 pathway on H<sub>2</sub>O<sub>2</sub>-induced cytotoxicity in MSCs.

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    <p>The standard cytotoxicity tests, including propidium iodide (PI)-based cell viability (A1–A3), MTT assay for mitochondrial viability (B1–B3), LDH assay for membrane damage (C1–C3), were performed. (A1, B1, and C1) MSCs were incubated in H<sub>2</sub>O<sub>2</sub>-conditioned media (250 µM) added with or without SDF-1α (50 ng/ml) for 6 h. The cells incubated in absence of both H<sub>2</sub>O<sub>2</sub> and SDF-1α were used as control. A1 and C1: *<i>P</i><0.05, vs NP-MSCs; <sup>†</sup><i>P</i><0.05, vs Control; <sup>‡</sup><i>P</i><0.05, vs H<sub>2</sub>O<sub>2</sub>. B1: *<i>P</i><0.05, vs NP-MSCs; <sup>†</sup><i>P</i><0.05, vs Non-SDF-1. (A2, B2, and C2) Prior to H<sub>2</sub>O<sub>2</sub> treatment, HP-MSCs were treated with a neutralizing anti-CXCR4 antibody, an anti-CXCR7 antibody, and the respective isotype-matched control antibodies, respectively. *<i>P</i><0.05, vs the respective isotype-matched control antibodies; <sup>†</sup><i>P</i><0.05, vs non-SDF-1. (A3, B3, and C3) Prior to H<sub>2</sub>O<sub>2</sub> treatment, NP-MSCs were transiently overexpressed with CXCR4 using pORF9-mCXCR4 vector or with CXCR7 using pORF9-mCXCR7 vector. *<i>P</i><0.05, vs empty vector; <sup>†</sup><i>P</i><0.05, vs Non-SDF-1.</p

    Effects of HP on the expression of SDF-1α, CXCR4, CXCR7 in MSCs.

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    <p>(A) Semiquantitative RT-PCR was used for the analysis of SDF-1α, CXCR4 and CXCR7 mRNA levels in MSCs. GAPDH was used as a control. Lane 1 indicates bone marrow mononuclear cells (BMMCs); lanes 2 to 4, MSC cultures at passage 1 to 3; and lane 5, MSCs at passage 3 and exposed to hypoxia (3% O<sub>2</sub>) for 24 h. (B) Western blot analysis was performed to detect CXCR4, CXCR7 and SDF-1α protein expression. β-actin was used as a control. Lanes 1 indicates BMMCs; lanes 2 to 5, MSC cultures at passage 1 to 4; and lane 6, MSCs at the third passage to hypoxia for 24 h. (C) FCM was used to detect extracellular expression of CXCR4 or CXCR7 in MSCs exposed to the indicated periods of hypoxia. *<i>P</i><0.05, vs 0 h. (D) ELISA analysis was performed to determine production of SDF-1α from MSCs exposed to the indicated periods of hypoxia. *<i>P</i><0.05, vs 0 h.</p

    Effects of SDF-1-CXCR4/CXCR7 pathway on MSC paracrine actions.

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    <p>ELISA was performed to determine production of VEGF, β-FGF, IGF-1 and HGF from MSCs stimulated by hypoxia (3% O<sub>2</sub>) or/and SDF-1α (50 ng/ml). The cells stimulated by neither hypoxia nor SDF-1α were used as control. (A) MSCs were stimulated with hypoxia or/and SDF-1α. *<i>P</i><0.05, vs control; <sup>†</sup><i>P</i><0.05, vs SDF-1; <sup>‡</sup><i>P</i><0.05, vs hypoxia. (B and C) The HP-MSCs stimulated with or whthout SDF-1α were treated with an anti-CXCR4 antibody (B), an anti-CXCR7 antibody (C), and the respective isotype-matched control antibodies. *<i>P</i><0.05, vs IgG2B (B) or IgG (C); <sup>†</sup><i>P</i><0.05, vs αCXCR4 (B) or αCXCR7 (C); <sup>‡</sup><i>P</i><0.05, vs SDF-1+IgG2B (B) or SDF-1+IgG (C). (D) NP-MSCs were transiently overexpressed with CXCR4 using pORF9-mCXCR4 vector or with CXCR7 using pORF9-mCXCR7 vector. *<i>P</i><0.05, vs empty vector; <sup>†</sup><i>P</i><0.05, vs pORF9-mCXCR4 vector.</p
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