Xiaochun Ma

Artificial and bioartificial liver support systems for acute and acute-on-chronic hepatic failure: A meta-analysis and meta-regression

Artificial and bioartificial liver support systems (LSSs) appear to be safe and effective in the treatment of acute and acute-on-chronic hepatic failure (AHF and AOCHF); however, individually published studies and previous meta-analyses have revealed inconclusive results. The aim of the present meta-analysis was to derive a more precise estimation of the benefits and disadvantages of artificial and bioartificial LSSs for patients with AHF and AOCHF. A literature search was conducted in the PubMed, Embase, Web of Science and Chinese Biomedical (CBM) databases for publications prior to March 1, 2013. Crude relative risks (RRs) or standardized mean differences (SMDs) with 95% confidence intervals (95% CI) were calculated using either the fixed effects or random effects models. Nineteen randomized controlled trials (RCTs) were included, which comprised a total of 566 patients with AHF and 371 patients with AOCHF. The meta-analysis showed that artificial LSS therapy significantly reduced mortality in patients with AOCHF; however, it had no apparent effect on total mortality in patients with AHF. The results also indicated that the use of bioartificial LSSs was correlated with decreased mortality in patients with AHF. A significant reduction in the bridging to liver transplantation was observed in patients with AOCHF following artificial LSS therapy; however, similar results were not observed in patients with AHF. Patients with AHF and those with AOCHF showed significant reductions in total bilirubin levels following artificial LSS therapy. There were no significantly increased risks of hepatic encephalopathy or bleeding in either the patients with AHF or AOCHF following artificial or bioartificial LSS therapies. Univariate and multivariate meta-regression analyses confirmed that none of the factors explained the heterogeneity. The present meta-analysis indicated that artificial LSSs reduce mortality in patients with AOCHF, while the use of bioartificial LSSs was correlated with reduced mortality in patients with AHF.

Heparin attenuates lipopolysaccharide-induced acute lung injury by inhibiting nitric oxide synthase and TGF-β/Smad signaling pathway

INTRODUCTION Heparin, a potent blood anticoagulant, has been shown to exert a variety of pharmacological activities. The purpose of this study was to investigate whether heparin has a beneficial effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and to further explore the possible underlying mechanisms. MATERIALS AND METHODS Adult Sprague-Dawley rats were randomly assigned into the control, heparin, LPS, and LPS plus heparin groups. ALI was induced by intratracheal instillation of LPS at a dose of 1 mg/kg. Rats in the LPS plus heparin group were intravenously received 50 U/ kg heparin every 1 h after the induction of ALI. RESULTS We found that heparin significantly improved LPS-induced lung pathological changes, inhibited myeloperoxidase (MPO) activity, and reduced malondialdehyde (MDA) level and lung wet/dry weight ratio. Heparin also inhibited the release of tumor necrosis factor (TNF)-α and interleukin (IL)-6, and markedly decreased the expression of inducible nitric oxide synthase (iNOS) in lung tissues and thus prevented nitric oxide (NO) release in response to LPS challenge. Additionally, heparin decreased the expression of transforming growth factor-β1 (TGF-β1), p-Smad 2, and p-Smad 3, which are all important molecules of the TGF-β1/Smad signaling pathway. CONCLUSIONS Heparin significantly ameliorated the lung injury induced by LPS in rats via the inhibition of nitric oxide synthase expression and the TGF-β/Smad pathway. Heparin may be a potential therapeutic reagent for treating ALI in the future.

Treatment with unfractionated heparin attenuates coagulation and inflammation in endotoxemic mice.

INTRODUCTION In the pathogenesis of sepsis, inflammation and coagulation play a pivotal role. In addition to the anticoagulant activity, unfractionated heparin (UFH) has important immunomodulatory properties. However, different studies have reported conflicting effects on sepsis in association with heparin. The objective of this study is to determine whether UFH is able to reduce endotoxin-induced inflammation and coagulation in mice or produce improved outcome. METHODS C57BL/6J mice were randomly divided into two groups. Experimental mice were given intravenous injection of 8 units/20 g body weight UFH (heparin sodium) diluted in 20 μl sterile saline while the control mice received vehicle sterile saline only. They were injected with LPS (30 mg/kg, i.p.) 0.5h later. Blood was collected and Livers were harvested at 3 and 6h for analysis. In survival studies, a separate group of mice were treated with 8 units/20 g UFH (n=20) or sterile saline (n=20) given intravenously at 1, 12, 24 and 36 hours after LPS injection. Mice were monitored every 12 hours for a maximum of 72 hrs. RESULTS 1) Pretreatment of mice with UFH strongly reduced the levels of TNF-α, IL-1β and TAT in plasma at 3 and 6h; 2) Pretreatment of mice with UFH inhibited the expression of TNF-α, IL-1β and tissue factor genes in blood cells at 3h; 3) UFH pretreatment dramatically diminished LPS-induced neutrophil sequestration (at 3 and 6h) , thrombi formation and fibrin(ogen) deposition in the liver (at 6h). 4) The UFH-pretreated group exhibited significantly lower levels of ALT and CRE at 6h. 5) Treatment with UFH could prevent mortality associated with endotoxin challenge. CONCLUSION These data suggest that UFH attenuates inflammation and coagulation and prevents lethality in endotoxemic mice.

Elevated levels of plasma TNF-α are associated with microvascular endothelial dysfunction in patients with sepsis through activating the NF-κB and p38 mitogen-activated protein kinase in endothelial cells.

ABSTRACT Inflammatory responses can induce microvascular and endothelial dysfunction, which is associated with the development of sepsis. This study is aimed at examining the concentrations of plasma tissue factor (TF), von Willebrand factor (vWF), and tumor necrosis factor-&agr; (TNF-&agr;) in patients with sepsis and at determining how septic plasma (SP) regulates TF and vWF expression and p38 mitogen activated protein kinase (p38 MAPK)/nuclear factor-&kgr;B (NF-&kgr;B) pathways in human endothelial cells. The concentrations of plasma TF, vWF, and TNF-&agr; in 22 septic patients and eight healthy controls (HCs) were examined by enzyme-linked immunosorbent assay, and their potential association with disease severity was analyzed. Human umbilical vein endothelial cells (HUVECs) were treated with SP from patients or normal plasma (NP) from the HCs, and the levels of TF and vWF were measured. The SP-induced ERK, p38 MAPK, and NF-&kgr;B activation was characterized by Western blot and immunofluorescent assays. The SP-induced HUVEC apoptosis was detected by flow cytometry. The concentrations of plasma TF, vWF, and TNF-&agr; in the patients were significantly higher than that in the HCs and were positively correlated with the Acute Physiology and Chronic Health Evaluation II scores in the patients. Furthermore, treatment with SP, but not NP, induced TF and vWF production in HUVECs in a dose- and time-dependent manner, which was associated with sequential activation of the p38 MAPK and NF-&kgr;B pathways. Septic plasma induced HUVEC apoptosis, which was inhibited by activating the NF-&kgr;B pathway. The sepsis-related inflammatory factors promoted endothelial cell activation, dysfunction, and apoptosis through activation of the p38 MAPK pathway that was regulated by NF-&kgr;B signaling.

Heparin Rescues Sepsis-Associated Acute Lung Injury and Lethality Through the Suppression of Inflammatory Responses

Heparin, a potent blood anticoagulant, is known to possess anti-inflammatory activity. In this work, we investigated whether heparin can ameliorate acute lung injury and lethal response in lipopolysaccharide (LPS)-induced mouse model of sepsis. We found that heparin effectively rescued lethality, improved lung pathological changes, inhibited myeloperoxidase (MPO) activity, and reduced malondialdehyde (MDA) level, lung wet/dry weight ratio and Evans blue values in LPS-induced septic mice. In addition, heparin also inhibited the release of tumor necrosis factor (TNF)-α, interleukin-6 (IL-6) and IL-1β in serum and decreased the expression of p-p38, nuclear factor κB (NF-κB) and p-c-SRC kinase in lungs of septic mice. Our findings suggest that heparin is capable of suppressing the lethal response and acute lung injury associated with sepsis, and support the notion that heparin may be a potential therapeutic agent for the conditions associated with septic shock.

Unfractionated heparin attenuates lung vascular leak in a mouse model of sepsis:Role of RhoA/Rho kinase pathway

INTRODUCTION Excessive vascular permeability is a characteristic feature of ALI. We have previously demonstrated that UFH prevents LPS-induced disruption of endothelial barrier function in vitro. It was the objective of this study to determine whether UFH may attenuate endotoxin-induced lung vascular leak in mice and to further explore the possible underlying mechanisms. METHODS C57BL/6J mice were randomly divided into the control, LPS and LPS plus UFH groups. Sepsis was induced by intraperitoneal injection of LPS at a dose of 30 mg/kg. Mice in the LPS plus UFH group were intravenously received 8 units UFH (heparin sodium) diluted in 20 μl sterile saline at 0.5 h before the injection of LPS. RESULTS 1) UFH pretreatment attenuated LPS-induced histopathological changes in Lung at 6 h; 2) Pretreatment of mice with UFH ameliorated LPS-induced lung edema and lung vascular leak at 6 h; 3) UFH pretreatment dramatically inhibited RhoA and ROCK activation in the lung tissues of LPS-treated mice (3 and 6 h). 4) UFH pretreatment significantly down-regulated ROCK1 gene expression, but did not affect the increased expression of ROCK2 mRNA in the lung tissues of LPS-treated mice at 3 or 6 h. CONCLUSION These data suggest that UFH may attenuate endotoxin-induced lung vascular leak by regulating RhoA/Rho kinase pathway.

Treatment of Low Molecular Weight Heparin Inhibits Systemic Inflammation and Prevents Endotoxin-Induced Acute Lung Injury in Rats

To determine whether low molecular weight heparin (LMWH) is able to reduce pulmonary inflammation and improve the survival in rats with endotoxin-induced acute lung injury (ALI). Rat ALI model was reproduced by injection of lipopolysaccharide (LPS) into tail vein. Rats were divided randomly into three groups: control group, ALI group, LMWH-treated group. Blood was collected and lung tissue was harvested at the designated time points for analysis. The lung specimens were harvested for morphological studies, streptavidin-peroxidase immunohistochemistry examination. Lung tissue edema was evaluated by tissue water content. The levels of lung tissue myeloperoxidase (MPO) were determined. Meanwhile, the nuclear factor-kappa B (NF-κB) activation, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) levels and high mobility group box 1 (HMGB1) and intercellular adhesion molecule-1 (ICAM-1) protein levels in the lung were studied. In survival studies, a separate group of rats were treated with LMWH or sterile saline after LPS administration. Then, the mortality was recorded. Treatment with LMWH after ALI was associated with a reduction in the severity of LPS-induced lung injury. Treatment with LMWH significantly decreased the expression of TNF-α, IL-1β, HMGB1 and ICAM-1 in the lung of ALI rats. Similarly, treatment with LMWH dramatically diminished LPS-induced neutrophil sequestration and markedly reduced the enhanced lung permeability. In the present study, LMWH administration inhibited the nuclear translocation of NF-κB in the lung. Survival was significantly higher among the LMWH-treated group compared with the ALI group. These data suggest that LMWH attenuates inflammation and prevents lethality in endotoxemic rats.

Tetramethylpyrazine attenuates TNF-α-induced iNOS expression in human endothelial cells: Involvement of Syk-mediated activation of PI3K-IKK-IκB signaling pathways

Endothelial cells produce nitric oxide (NO) by activation of constitutive nitric oxide synthase (NOS) and transcription of inducible NO synthase (iNOS). We explored the effect of tetramethylpyrazine (TMP), a compound derived from chuanxiong, on tumor necrosis factor (TNF)-α-induced iNOS in human umbilical vein endothelial cells (HUVECs) and explored the signal pathways involved by using RT-PCR and Western blot. TMP suppressed TNF-α-induced expression of iNOS by inhibiting IκB kinase (IKK) phosphorylation, IκB degradation and nuclear factor κB (NF-κB) nuclear translocation, which were required for NO gene transcription. Exposure to wortmannin abrogated IKK/IκB/NF-κB-mediated iNOS expression, suggesting activation of such a signal pathway might be phosphoinositide-3-kinase (PI3K) dependent. Spleen tyrosine kinase (Syk) inhibitor piceatannol significantly inhibited NO production. Furthermore, piceatannol obviously suppressed TNF-α-induced IκB phosphorylation and the downstream NF-κB activation, suggesting that Syk is an upstream key regulator in the activation of PI3K/IKK/IκB-mediated signaling. TMP significantly inhibited TNF-α-induced phosphorylation of Syk and PI3K. Our data indicate that TMP might repress iNOS expression, at least in part, through its inhibitory effect of Syk-mediated PI3K phosphorylation in TNF-α-stimulated HUVECs.

Unfractionated heparin attenuates LPS-induced IL-8 secretion via PI3K/Akt/NF-κB signaling pathway in human endothelial cells.

Unfractionated heparin (UFH) is largely used as anti-thrombotic drug. While UFH has been shown to suppress lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) activation, intracellular upstream events that cause NF-κB down-regulation in response to UFH remain unclear. Thus, we investigated the involvement of phosphoinositide-3-OH kinase (PI3K)/Akt in the inhibition of LPS-activated NF-κB pathway by UFH in human pulmonary microvascular endothelial cells (HPMECs). Pretreatment with UFH (0.1-1U/ml) significantly inhibited LPS (10μg/ml)-stimulated interleukin (IL)-6 and IL-8 production in HPMECs. LPS activated Akt and NF-κB, whereas UFH suppresses LPS-induced Akt phosphorylation and NF-κB nuclear translocation, which were required for IL-6 and IL-8 gene transcription. Inhibition studies by using wortmannin abrogated NF-κB-mediated IL-6 and IL-8 expression, suggesting the requirement of PI3K/Akt pathway. Our data provided the first evidence that UFH might repress LPS-activated PI3K/Akt pathway, leading to inhibitory effect of NF-κB activation with diminished IL-6 and IL-8 expression in HPMECs.

High glucose enhances LPS-stimulated human PMVEC hyperpermeability via the NO pathway.

Chronic hyperglycemia is an established risk factor for endothelial damage. It remains unclear, however, whether brief hyperglycemic exposure exacerbates the damage to vascular endothelial cells induced by endotoxin. We hypothesize that brief hyperglycemic exposure enhances the permeability of the endothelium following stimulation with lipopolysaccharide (LPS). Correlations between modulation of nitric oxide synthase (NOS) pathways and altered endothelial homeostasis have been studied and demonstrated in various pathophysiological conditions. NOS activities are regulated by endogenous inhibitors, including asymmetric dimethylarginine (ADMA), which is metabolized by dimethylarginine dimethylaminohydrolase (DDAH). Since previous data demonstrated that endothelial dysfunction may be related to reduced expression and/or activity of DDAH, in this study, we aimed to determine the effect of increased glucose levels on pulmonary microvascular endothelial cell (PMVEC) permeability, including effects on the NOS pathways. Human PMVECs were incubated with normal (5.5 mM) and high (33 mM) concentrations of D-glucose for 5 days to create a monolayer of cells prior to LPS stimulation (10 μg/ml) for 12 h. When stimulated with LPS, cells incubated with a high glucose (HG) concentration had significant microfilament rearrangement compared with cells incubated with a normal glucose concentration, as determined by immunofluorescence. Scanning electron microscopy revealed a larger average diameter and increased number of fenestrae on the hyperglycemic PMVECs when stimulated with LPS, compared with PMVECs cultured with a normal glucose concentration. The results demonstrated that a high concentration of glucose increases the LPS-stimulated horseradish peroxidase (HRP) permeability compared with a normal concentration of glucose. Furthermore, a HG concentration upregulated LPS-stimulated inducible NOS (iNOS) production and down-regulated endothelial NOS (eNOS) and DDAH-2 expression. Hyperglycemia significantly increased LPS-stimulated nitrite/nitrate production (stable NO end-products). Our results, thus, demonstrate that in vitro HG concentrations exacerbate LPS-stimulated cytoskeletal rearrangement and hyperpermeability of an endothelial monolayer, and cause further imbalance of the NO pathway. These results suggest that it is important to manage even short-term increases in blood glucose, particularly following acute infection.