Zhaofan Xia

Activation of p38 MAPK by Reactive Oxygen Species Is Essential in a Rat Model of Stress-Induced Gastric Mucosal Injury

Stress ulceration is a common complication in critically ill patients and can result in significant upper gastrointestinal bleeding associated with a high morbidity and mortality. At present, little is known of the molecular mechanisms underlying the incidence of this type of gastric damage. In the present study, we investigated the temporal activation of the redox-sensitive p38 signaling transduction cascade and its roles in a well-defined experimental model of cold immobilization stress-induced gastric ulceration. Exposure of Sprague-Dawley rats to 6 h of cold immobilization stress led to a rapid activation of p38 in the gastric mucosa at as early as 15 min after stress, and this activation was maximal after 1.5 h of stress and still persisted until the end of stress. Selectively blocking p38 by pretreatment with SB 239063, a potent and selective p38 inhibitor, suppressed the stress-promoted TNF-α, IL-1β, and CINC-1 production and then prevented the subsequent neutrophil infiltration, gastric mucosal epithelial necrosis and apoptosis, and the ulcerative lesions formation. Prior administration of the free radical scavengers, tempol and N-acetyl-l-cysteine, abolished the stress induction of p38 activation and the resulting mucosal inflammation and gastric injury. These results demonstrate that reactive oxygen species-mediated p38 activation plays an essential role in the pathogenesis of stress-induced gastric inflammatory damage in the rat model of cold immobilization stress. Our findings suggested that inhibition of p38 activation might be a potential strategy for the prophylaxis and treatment of stress ulceration.

TLR4 Mediates Lung Injury and Inflammation in Intestinal Ischemia-Reperfusion

BACKGROUND Splanchnic ischemia is common in critically ill patients, and it can result in injury not only of the intestine but also in distant organs, particularly in the lung. Local inflammatory changes play a pivotal role in the development of acute lung injury after intestinal ischemia, but the underlying molecular mechanisms are not fully understood. We sought to examine the role of Toll-like receptor 4 (TLR4) in the mouse model of intestinal ischemia-reperfusion (I/R)-induced lung injury and inflammation. MATERIALS AND METHODS Adult male TLR4 mutant (C3H/HeJ) mice and TLR4 wild-type (WT) (C3H/HeOuJ) mice were subjected to 40 min of intestinal ischemia by clamping the superior mesenteric artery followed by 6 h of reperfusion. Lung histology was assessed and parameters of pulmonary microvascular permeability, inflammatory cytokine expression, and neutrophil infiltration were measured. Activation of mitogen-activated protein kinases (MAPKs) and the transcription factors nuclear factor κB (NF-κB) and activator protein-1 (AP-1) in the lungs were also detected. RESULTS After intestinal I/R, lungs from TLR4 mutant mice demonstrated a significantly lower histological injury, a marked reduction of epithelial apoptosis associated with the decreased level of cleaved caspase-3 and the increased ratio of Bcl-xL to Bax proteins, and a large reduction in pulmonary vascular permeability and myeloperoxidase (MPO) activity in comparison with WT mice. TLR4 mutant mice also displayed marked decreases in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) expression. Following intestinal I/R, phosporylation of p38 MAPK and activation of NF-κB and AP-1 were significantly inhibited in lung tissue from TLR4 mutant mice compared with WT controls. CONCLUSIONS These data suggest that TLR4 plays an important role in the pathogenesis of intestinal I/R-induced acute lung injury and inflammation and that p38 kinase and NF-κB may be involved in TLR4 signaling-mediated lung inflammatory processes during intestinal I/R.

Hydrogen resuscitation, a new cytoprotective approach

1. Hydrogen is a colourless, odourless, tasteless and flammable gas. Hydrogen is considered a physiologically inert gas and is often used in deep sea diving medicine. In mammals, endogenous hydrogen is produced as a result of the fermentation of non‐digestible carbohydrates by intestinal bacteria and it is absorbed into the systemic circulation.

Factors affecting survival in adult patients with massive burns

OBJECTIVE To identify treatment-related factors associated with mortality in massively burned adult patients. METHODS This retrospective cohort study examined survival outcomes at a burn unit of 54 beds and 10 burn ICU beds, totaling 900 admissions per year. The cases of 102 adult patients, admitted consecutively from January 1993 to October 2007, with massive burns (burn area>70% of the total body surface area, TBSA) were studied. Relevant variables were recorded from the initial injury and throughout the hospital course. Survival analysis, based on univariate and stepwise multivariate Cox proportional hazards regression, was performed to determine which variables predicted mortality. RESULTS The overall mortality rate was 30.4%. Burn size, severe inhalation injury, full-thickness burns, serum creatinine levels, inotropic support, platelet counts<20,000 per mm3, sepsis and ventilator dependency were significantly associated with mortality as determined by univariate analysis. Only sepsis, ventilator dependency and platelet counts were significant independent predictors of mortality as determined by multivariate analysis. CONCLUSIONS Sepsis, ventilator dependence (indicating severe respiratory complications), and low platelet counts (indicating thrombocytopenia) are associated with increased mortality risk in adult patients with massive burns. Methods should be sought to ameliorate these complications during treatment in burn-care units.

Notoginsenoside R1 attenuates renal ischemia-reperfusion injury in rats.

Ischemia-reperfusion (I/R) injury of the kidney is a complex pathophysiological process and a major cause of acute renal failure. It has been shown that I/R injury is related to inflammatory responses and activation of apoptotic pathways. Inhibition of certain elements of inflammatory responses and apoptotic pathway seemed to ameliorate renal I/R injury. As an effective element of Panax notoginseng, NR1 has antioxidant, anti-inflammatory, antiapoptotic, and immune-stimulatory activities. Therefore, we speculate that NR1 can attenuate renal I/R injury. Ischemia-reperfusion injury was induced by renal pedicle ligation followed by reperfusion along with a contralateral nephrectomy. Male Sprague-Dawley rats were randomized to four groups: sham group, I/R control group, NR1-1 group (rats treated with NR1, 20 mg·kg−1·d−1) and NR1-2 group (rats treated with NR1, 40 mg·kg−1·d−1). All animals were killed 72 h after I/R induction. Blood and renal tissues were collected. Renal dysfunction was observed by the level of serum creatinine and histological evaluation. Apoptosis and inflammatory response in the tissue of kidney were detected mainly with molecular biological methods. NR1 attenuated I/R-induced renal dysfunction as indicated by the level of serum creatinine and histological evaluation. It prevented the I/R-induced increases in the levels of proinflammatory cytokine TNF-&agr;, myeloperoxidase activity, phosphorylation of p38, and activation of nuclear factor &kgr;B with cell apoptosis in the kidney and enhanced expression of antiapoptosis cytokine bcl-2. Treatment with NR1 improves renal function after I/R associated with a significant reduction in cell apoptosis and inflammatory responses, which may be related to p38 and nuclear factor &kgr;B inhibition.

Evaluation of long term health-related quality of life in extensive burns: A 12-year experience in a burn center

OBJECTIVES We sought to evaluate the long term health-related quality of life (HRQOL) in patients survived severely extensive burn and identify their clinical predicting factors correlated with HRQOL. METHODS A cross-sectional study was conducted in 20 patients survived more than 2 years with extensive burn involving ≥70% total body surface area (TBSA) between 1997 and 2009 in a burn center in Shanghai. Short Form-36 Medical Outcomes Survey (SF-36), Brief Version of Burn Specific Health Scale (BSHS-B) and Michigan Hand Outcome Questionnaire (MHQ) were used for the present evaluation. SF-36 scores were compared with a healthy Chinese population, and linear correlation analysis was performed to screen the clinical relating factors predicting physical and mental component summary (PCS and MCS) scores from SF-36. RESULTS HRQOL scores from SF-36 were significantly lower in the domains of physical functioning, role limitations due to physical problems, pain, social functioning and role limitations due to emotional problems compared with population norms. Multiple linear regression analysis demonstrated that only return to work (RTW) predicted improved PCS. While age at injury, facial burns, skin grafting and length of hospital stay were correlated with MCS. Work, body image and heat sensitivity obtained the lowest BSHS-B scores in all 9 domains. Improvements of HRQOL could still be seen in BSHS-B scores in domains of simple abilities, hand function, work and affect even after a quite long interval between burns and testing. Hand function of extensive burn patients obtained relatively poor MHQ scores, especially in those without RTW. CONCLUSIONS Patients with extensive burns have a poorer quality of life compared with that of general population. Relatively poor physical and psychological problems still exist even after a long period. Meanwhile, a trend of gradual improvements was noted. This information will aid clinicians in decision-making of comprehensive systematic regimens for long term rehabilitation and psychosocial treatment.

The protective effect of esculentoside a on experimental acute liver injury in mice.

Inflammatory response and oxidative stress are considered to play an important role in the development of acute liver injury induced by carbon tetrachloride (CCl4) and galactosamine (GalN)/lipopolysaccharides (LPS). Esculentoside A (EsA), isolated from the Chinese herb phytolacca esculenta, has the effect of modulating immune response, cell proliferation and apoptosis as well as anti-inflammatory effects. The present study is to evaluate the protective effect of EsA on CCl4 and GalN/LPS-induced acute liver injury. In vitro, CCK-8 assays showed that EsA had no cytotoxicity, while it significantly reduced levels of TNF-α and cell death rate challenged by CCl4. Moreover, EsA treatment up-regulated PPAR-γ expression of LO2 cells and reduced levels of reactive oxygen species (ROS) challenged by CCl4. In vivo, EsA prevented mice from CCl4-induced liver histopathological damage. In addition, levels of AST and ALT were significantly decreased by EsA treatment. Furthermore, the mice treated with EsA had a lower level of TNF-α, Interleukin (IL)-1β and IL-6 in mRNA expression. EsA prevented MDA release and increased GSH-Px activity in liver tissues. Immunohistochemical staining showed that over-expression of F4/80 and CD11b were markedly inhibited by EsA. The western bolt results showed that EsA significantly inhibited CCl4-induced phosphonated IkBalpha (P-IκB) and ERK. Furthermore, EsA treatment also alleviated GalN/LPS-induced acute liver injury on liver enzyme and histopathological damage. Unfortunately, our results exhibited that EsA had no effects on CCl4-induced hepatocyte apoptosis which were showed by TUNEL staining and Bax, Caspase-3 and cleaved Caspase-3 expression. Our results proved that EsA treatment attenuated CCl4 and GalN/LPS-induced acute liver injury in mice and its protective effects might be involved in inhibiting inflammatory response and oxidative stress, but not apoptosis with its underlying mechanism associated with PPAR-γ, NF-κB and ERK signal pathways.

Hydrogen inhalation ameliorates lipopolysaccharide-induced acute lung injury in mice

Acute lung injury (ALI) is a serious illness, the incidence and mortality of which are very high. Free radicals, such as hydroxyl radicals (OH) and peroxynitrite (ONOO(-)), are considered to be the final causative molecules in the pathogenesis of ALI. Hydrogen, a new antioxidant, can selectively reduce OH and ONOO(-). In the present study, we investigated the hypothesis that hydrogen inhalation could ameliorate ALI induced by intra-tracheal lipopolysaccharide (LPS, 5mg/kg body weight). Mice were randomized into three groups: sham group (physiological saline+2% hydrogen mixed gas), control group (LPS+normal air) and experiment group (LPS+2% hydrogen mixed gas). Bronchoalveolar lavage fluid (BALF) was performed to determine the total protein concentrations and pro-inflammatory cytokines. Lung tissues were assayed for oxidative stress variables, wet/dry (W/D) ratio, histological, immunohistochemistry and Western blotting examinations. Our experiments exhibited that hydrogen improved the survival rate of mice and induced a decrease in lung W/D ratio. In addition, hydrogen decreased malonaldehyde and nitrotyrosine content, inhibited myeloperoxidase and maintained superoxide dismutase activity in lung tissues and associated with a decrease in the expression of TNF-α, IL-1β, IL-6 and total protein concentrations in the BALF. Hydrogen further attenuated histopathological alterations and mitigated lung cell apoptosis. Importantly, hydrogen inhibited the activation of P-JNK, and also reversed changes in Bax, Bcl-xl and caspase-3. In conclusion, our data demonstrated that hydrogen inhalation ameliorated LPS-induced ALI and it may be exerting its protective role by preventing the activation of ROS-JNK-caspase-3 pathway.

Metabolomic analysis of thermally injured and/or septic rats

INTRODUCTION Early diagnosis and treatment for thermal injury with septic complications continue to be a serious clinical problem. In this study, plasma biomarkers of rats in the burn and/or septic models were investigated with a metabolomic method. METHODS Rat plasma samples were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Multivariate analysis, the principal components analysis (PCA), was used to validate metabolic changes. In addition, another multivariate method, the orthogonal partial least-squares analysis (OPLS), was used to profile potential biomarkers in models. RESULTS Nine characteristic metabolites, including hypoxanthine, indoxyl sufate, glucuronic acid, gluconic acid, proline, uracil, nitrotyrosine, uric acid, and trihydroxy cholanoic acid were identified in models of thermal injury and/or sepsis. CONCLUSION These biomarkers were mainly involved in oxidative stress and tissue damage, and might supply evidence for distinguishing burned septic patients from non-septic ones.

Sustained activation of nuclear factor-κB by reactive oxygen species is involved in the pathogenesis of stress-induced gastric damage in rats

Objective:Stress ulceration is a common complication in critically ill patients, but the mechanisms involved are poorly understood. In this study we investigated the temporal activation of the redox-sensitive transcription factor nuclear factor-&kgr;B and its roles in an experimental model of cold immobilization stress-induced gastric mucosal lesions. Design:Prospective, controlled, and randomized animal study. Setting:University research laboratory. Subjects:Male Sprague-Dawley rats. Interventions:The rats were subjected to cold immobilization stress for a total of 6 hrs. The temporal profiles of nuclear factor-&kgr;B activation and expression of tumor necrosis factor-&agr;, interleukin-1&bgr;, cytokine-induced neutrophil chemoattractant-1 (CINC-1), intercellular adhesion molecule-1 (ICAM-1), and inducible nitric oxide synthase (iNOS) were determined in the gastric corpus mucosa of stressed rats. To study the roles of nuclear factor-&kgr;B activation, rats received an intravenous bolus of a specific nuclear factor-&kgr;B inhibitor Bay 11-7082 (20 mg/kg) 1 hr before stress. For antioxidant administration, rats were treated with intravenous injection of a free radical scavenger pyrrolidine dithiocarbamate (50, 100, and 200 mg/kg) 1 hr before stress. Measurements and Main Results:Exposure of rats to 6 hrs of stress led to a rapid and persistent activation of nuclear factor-&kgr;B, which was associated with transient degradation of inhibitory protein I&kgr;B&agr; and slower but sustained degradation of I&kgr;B&bgr;. Nuclear factor-&kgr;B activation preceded the induction of tumor necrosis factor-&agr;, interleukin-1&bgr;, CINC-1, ICAM-1, and iNOS messenger RNAs, all of which were linearly increased with the duration of stress. Bay 11-7082 selectively blocked the stress-induced nuclear factor-&kgr;B activation and up-regulation of tumor necrosis factor-&agr;, interleukin-1&bgr;, CINC-1, ICAM-1, and iNOS messenger RNAs. Inhibition of expression of these proinflammatory genes prevented the increases in myeloperoxidase activity (an indicator of neutrophil infiltration) in gastric mucosa and the development of gastric damage. Pyrrolidine dithiocarbamate dose-dependently inhibited the stress-induced nuclear factor-&kgr;B pathway activation and consequential proinflammatory gene expression, neutrophil infiltration, and gastric damage, suggesting the involvement of reactive oxygen species in these processes. Conclusions:Sustained activation of nuclear factor-&kgr;B by reactive oxygen species is an important in vivo mechanism mediating stress-induced gastric inflammatory damage in rats.