Sepsis often results in damage to multiple organ systems, possibly due to severe mitochondrial dysfunction. Two members of the sirtuin family, SIRT1 and SIRT3, have been implicated in the reversal of mitochondrial damage. The aim of this study was to determine the role of SIRT1/3 in acute kidney injury (AKI) following sepsis in a septic rat model. After drug pretreatment and cecal ligation and puncture (CLP) model reproduction in the rats, we performed survival time evaluation and kidney tissue extraction and renal tubular epithelial cell (RTEC) isolation. We observed reduced SIRT1/3 activity, elevated acetylated SOD2 (ac‐SOD2) levels and oxidative stress, and damaged mitochondria in RTECs following sepsis. Treatment with resveratrol (RSV), a chemical SIRT1 activator, effectively restored SIRT1/3 activity, reduced acetylated SOD2 levels, ameliorated oxidative stress and mitochondrial function of RTECs, and prolonged survival time. However, the beneficial effects of RSV were greatly abrogated by Ex527, a selective inhibitor of SIRT1. These results suggest a therapeutic role for SIRT1 in the reversal of AKI in septic rat, which may rely on SIRT3‐mediated deacetylation of SOD2. SIRT1/3 activation could therefore be a promising therapeutic strategy to treat sepsis‐associated AKI.

Objective—: Although biglycan (BGN) and oxidized low-density lipoprotein (oxLDL) accumulation has been observed in calcific, stenotic aortic valves, their role in the pathogenesis of calcific aortic valve disease is poorly understood. We hypothesized that soluble BGN induces the osteogenic response in human aortic valve interstitial cells via Toll-like receptor (TLR) 2 and TLR4 and mediates the proosteogenic effect of oxLDL. Methods and Results—: Aortic valve interstitial cells of stenotic valves express higher levels of BGN. Stimulation of cells from normal valves with BGN increased the expression of bone morphogenetic protein-2 (BMP-2) and alkaline phosphatase (ALP) among the chondrogenic/osteogenic markers examined and caused accumulation of calcium deposits. TLR2 silencing, but not TLR4 silencing, reduced BMP-2 and ALP levels after BGN stimulation although coimmunoprecipitation revealed that BGN interacts with both TLR2 and TLR4. BGN induced the phosphorylation of extracellular signal-regulated protein kinase -1/2, p38 mitogen-activated protein kinase and nuclear factor-κB. Inhibition of extracellular-regulated kinase -1/2 markedly reduced the upregulation of BMP-2 and ALP expression by BGN whereas inhibition of p38 mitogen-activated protein kinase or nuclear factor-κB had a moderate effect. Stimulation of aortic valve interstitial cells with oxLDL upregulated BGN expression and release. Knockdown and neutralization of BGN reduced the effect of oxLDL on BMP-2 and ALP expression. Conclusion—: Extracellular soluble BGN induces the expression of BMP-2 and ALP in human aortic valve interstitial cells primarily via TLR2 and contributes to the proosteogenic effect of oxLDL. These findings highlight the potential role of soluble BGN and oxLDL in the development of calcific aortic valve disease.

Lipopolysaccharide (LPS) stimulation of endothelial cells induces the expression of intercellular adhesion molecule-1 (ICAM-1), a critical adhesion molecule involved in the adhesive interaction between leukocytes and endothelial cells in shock and inflammation. Although there is little literature about role of p38 mitogen-activated protein kinase (MAPK) in ICAM-1 protein expression of LPS-induced endothelial cells, it is still not defined whether gene transcription is regulated by p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells. In this study, the potential role of p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells was studied in vitro and in vivo. In vitro studies, the results showed that compared with basic expression of ICAM-1 protein on cultured human umbilical vein endothelial cells (HUVECs), the ICAM-1 expression was increased initially at 2 h after LPS stimulation, reached peak value at 24 h, and descended at 36 h obviously. A dose-dependent relationship existed between LPS concentration and ICAM-1 expression. The abundance of ICAM-1 mRNA in cytoplasma of endothelial cells was upregulated significantly by LPS stimulation at 2 h and was maintained at a high level from 4 to 36 h. The upregulation of ICAM-1 protein and mRNA expression of LPS-induced HUVECs was markedly inhibited by SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole], a highly specific inhibitor of p38 MAPK. Activity of p38 MAPK in HUVECs was increased at 15 min after LPS stimulation and reached the maximum at 60 min, then descended significantly. Activity of p38 MAPK was inhibited significantly by SB203580 in vitro. In vivo studies, administration of SB203580 (12.5 or 25 mg/kg, per ora) markedly reduced LPS-induced expression of ICAM-1 protein and mRNA of lung tissues of male BALB/c mice. These data highlight that the upregulation of ICAM-1 expression of LPS-induced endothelial cells in vitro and in vivo is mediated by p38 MAPK pathway at the level of gene transcription. The ICAM-1 expression of LPS-induced endothelial cells is characteristic of time dependence and dose dependence, and tolerates to chronic LPS stimulation. Inhibition of the p38 MAPK signal pathway may be used as an approach to attenuate ICAM-1 production in the treatment of septic shock.

(2013). Polydatin – a new mitochondria protector for acute severe hemorrhagic shock treatment. Expert Opinion on Investigational Drugs: Vol. 22, No. 2, pp. 169-179.

Objectives. To ascertain if mitochondrial dysfunction (MD) of kidney cells is present in severe hemorrhagic shock and to investigate whether polydatin (PD) can attenuate MD and its protective mechanisms. Research Design and Methods. Renal tubular epithelial cells (RTECs) from rat kidneys experiencing HS and a cell line (HK‐2) under hypoxia/reoxygenation (H/R) treatment were used. Morphology and function of mitochondria in isolated RTECs or cultured HK‐2 cells were evaluated, accompanied by mitochondrial apoptosis pathway‐related proteins. Result. Severe MD was found in rat kidneys, especially in RTECs, as evidenced by swollen mitochondria and poorly defined cristae, decreased mitochondrial membrane potential (ΔΨm), and reduced ATP content. PD treatment attenuated MD partially and inhibited expression of proapoptotic proteins. PD treatment increased SIRT1 activity and decreased acetylated‐p53 levels. Beneficial effect of PD was abolished partially when the SIRT1 inhibitor Ex527 was added. Similar phenomena were shown in the H/R cell model; when pifithrin‐α (p53 inhibitor) was added to the PD/Ex527 group, considerable therapeutic effects were regained compared with the PD group apart from increased SIRT1 activity. Conclusions. MD is present in severe HS, and PD can attenuate MD of RTECs via the SIRT1‐p53 pathway. PD might be a promising therapeutic drug for acute renal injury.