Suppressive activity of RGX-365 on HMGB1-mediated septic responses

Abstract RGX-365 is the main fraction of black ginseng conmprising protopanaxatriol (PPT)-type rare ginsenosides (ginsenosides Rg4, Rg6, Rh4, Rh1, and Rg2). No studies on the antiseptic activity of RGX-365 have been reported. High mobility group box 1 (HMGB1) is recognized as a late mediator of sepsis, and the inhibition of HMGB1 release and recovery of vascular barrier integrity have emerged as attractive therapeutic strategies for the management of sepsis. In this study, we examined the effects of RGX-365 on HMGB1-mediated septic responses and survival rate in a mouse sepsis model. RGX-365 was administered to the mice after HMGB1 challenge. The antiseptic activity of RGX-365 was assessed based on the production of HMGB1, measurement of permeability, and septic mouse mortality using a cecal ligation and puncture (CLP)-induced sepsis mouse model and HMGB1-activated human umbilical vein endothelial cells (HUVECs). We found that RGX-365 significantly reduced HMGB1 release from LPS- activated HUVECs and CLP-induced release of HMGB1 in mice. RGX-365 also restored HMGB1-mediated vascular disruption and inhibited hyperpermeability in the mice. In addition, treatment with RGX-365 reduced sepsis-related mortality in vivo. Our results suggest that RGX- 365 reduces HMGB1 release and septic mortality in vivo, indicating that it is useful in the treatment of sepsis.

Metabotropic glutamate receptor 5 may be involved in macrophage plasticity.

BACKGROUND: Macrophages are a functionally heterogeneous cell population and depending on microenvironments they polarize in two main groups: M1 and M2. Glutamic acid and glutamate receptors may participate in the regulation of macrophage plasticity. To investigate the role of glutamatergic systems in macrophages physiology, we performed the transfection of mGluR5 cDNAs into RAW-264.7 cells. RESULTS: Comparative analysis of modified (RAW-mGluR5 macrophages) and non-modified macrophages (RAW-macrophages) has shown that the RAW-mGluR5 macrophages absorbed more glutamate than control cells and the amount of intracellular glutamate correlated with the expression of excitatory amino acid transporters -2 (EAAT-2). Besides, our results have shown that RAW-mGluR5 macrophages expressed a higher level of peroxisome proliferator-activated receptor γ (PPAR-γ) and secreted more IL-10, high mobility group box 1 proteins (HMGB1) and Galectin-3 than control RAW-macrophages. CONCLUSIONS: We propose that elevation of intracellular glutamate and expression of mGluR5 may initiate the metabolic rearrangement in macrophages that could contribute to the formation of an immunosuppressive phenotype.

Metabotropic glutamate receptor 5 may be involved in macrophage plasticity

Abstract Background Macrophages are a functionally heterogeneous cell population and depending on microenvironments they polarize in two main groups: M1 and M2. Glutamic acid and glutamate receptors may participate in the regulation of macrophage plasticity. To investigate the role of glutamatergic systems in macrophages physiology, we performed the transfection of mGluR5 cDNAs into RAW-264.7 cells. Results Comparative analysis of modified (RAW-mGluR5 macrophages) and non-modified macrophages (RAW-macrophages) has shown that the RAW-mGluR5 macrophages absorbed more glutamate than control cells and the amount of intracellular glutamate correlated with the expression of excitatory amino acid transporters -2 (EAAT-2). Besides, our results have shown that RAW-mGluR5 macrophages expressed a higher level of peroxisome proliferator-activated receptor γ (PPAR-γ) and secreted more IL-10, high mobility group box 1 proteins (HMGB1) and Galectin-3 than control RAW-macrophages. Conclusions We propose that elevation of intracellular glutamate and expression of mGluR5 may initiate the metabolic rearrangement in macrophages that could contribute to the formation of an immunosuppressive phenotype.

Dexmedetomidine preconditioning inhibits the long term inflammation induced by renal ischemia/reperfusion injury in rats.

PURPOSE: To investigate the protective effects of dexmedetomidine (Dex) against renal ischemia/reperfusion injury (IRI). METHODS: Sprague-Dawley rats were randomly divided to sham group, IRI group and Dex group. The SD rats were subjected to 45 min of ischemia followed by eight weeks of reperfusion. Prior to ischemia, rats were either treated with Dex or not. Blood samples were collected for the detection of blood urea nitrogen (BUN) and creatinine (Cr) levels. Immunohistochemistry was performed for CD3 T-cell infiltrates. Real-time PCR and western blot were detected for the expression of TNF-α, IL-1ß, ICAM-1, HMGB1 and TLR4. RESULTS: Compared with sham group, renal IRI significantly increased the serum levels of BUN and Cr. The H&E staining indicated that renal IRI resulted in obvious renal injury and immunohistochemistry found that there were more CD3 T-cell infiltrates in IRI group. Also, renal IRI upregulated the expression of TNF-α, IL-1ß, ICAM-1, HMGB1 and TLR4. However, all these changes were alleviated by the treatment with Dex. CONCLUSIONS: Dexmedetomidine has beneficial effects on long term inflammation induced by renal ischemia/reperfusion injury. Its mechanisms may be achieved through inhibiting the HMGB1/TLR4 pathway to exert protective effects.

Dexmedetomidine preconditioning inhibits the long term inflammation induced by renal ischemia/reperfusion injury in rats

PURPOSE: To investigate the protective effects of dexmedetomidine (Dex) against renal ischemia/reperfusion injury (IRI). METHODS: Sprague-Dawley rats were randomly divided to sham group, IRI group and Dex group. The SD rats were subjected to 45 min of ischemia followed by eight weeks of reperfusion. Prior to ischemia, rats were either treated with Dex or not. Blood samples were collected for the detection of blood urea nitrogen (BUN) and creatinine (Cr) levels. Immunohistochemistry was performed for CD3 T-cell infiltrates. Real-time PCR and western blot were detected for the expression of TNF-α, IL-1β, ICAM-1, HMGB1 and TLR4. RESULTS: Compared with sham group, renal IRI significantly increased the serum levels of BUN and Cr. The H&E staining indicated that renal IRI resulted in obvious renal injury and immunohistochemistry found that there were more CD3 T-cell infiltrates in IRI group. Also, renal IRI upregulated the expression of TNF-α, IL-1β, ICAM-1, HMGB1 and TLR4. However, all these changes were alleviated by the treatment with Dex. CONCLUSIONS: Dexmedetomidine has beneficial effects on long term inflammation induced by renal ischemia/reperfusion injury. Its mechanisms may be achieved through inhibiting the HMGB1/TLR4 pathway to exert protective effects.

Effect of ulinastatin on HMGB1 expression in rats with acute lung injury induced by sepsis.

The aim of this study was to investigate the influence of ulinastatin (UTI) on high mobility group box 1 (HMGB1), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 expression in acute lung injury (ALI) rats with sepsis caused by cecal ligation and puncture (CLP) surgery, as well as to examine the underlying biological mechanism. Thirty rats were randomly and evenly divided into sham (control), CLP, and CLP + UTI groups. Thirty minutes after the surgery, the rats in the CLP + UTI group received UTI via the caudal vein, while normal saline was administered to rats in the other groups. Blood, lung tissues, and bronchoalveolar lavage fluid (BALF) were collected at different time points (6, 12, 24, and 48 h) after surgery for determination of related indicators. Compared with the CLP group, rats in the CLP + UTI group exhibited higher seven day survival rates, less lung injury, and decreased HMGB1 expression in the lung tissue, serum, and BALF. In addition, the levels of TNF-α and IL-6 at 24 h in the CLP + UTI group were markedly lower than those in the CLP group. These results suggest that by deregulation, UTI might decrease the lung injury and increase the survival time of ALI rats by downregulating HMGB1 expression as well as by inhibiting TNF-α and IL-6 levels in serum and BALF.