A novel TWIK2 channel inhibitor binds at the bottom of the selectivity filter and protects against LPS-induced experimental endotoxemia in vivo

TWIK2 channel plays a critical role in NLRP3 inflammasome activation and mice deficient in TWIK2 channel are protected from sepsis and inflammatory lung injury. However, inhibitors of TWIK2 channel are currently in an early stage of development, and the molecular determinants underlying the chemical modulation of TWIK2 channel remain unexplored. In this study, we identified NPBA and the synthesized derivative NPBA-4 potently and selectively inhibited TWIK2 channel by using whole-cell patch clamp techniques. Furthermore, the mutation of the last residues of the selectivity filter in both P1 and P2 (i.e., T106A, T214A) of TWIK2 channel substantially abolished the effect of NPBA on TWIK2 channel. Our data suggest that NPBA blocked TWIK2 channel through binding at the bottom of the selectivity filter, which was also supported by molecular docking prediction. Moreover, we found that NPBA significantly suppressed NLRP3 inflammasome activation in macrophages and alleviated LPS-induced endotoxemia and organ injury in vivo. Notably, the protective effects of NPBA against LPS-induced endotoxemia were abolished in Kcnk6-/- mice. In summary, our study has uncovered a series of novel inhibitors of TWIK2 channel and revealed their distinct molecular determinants interacting TWIK2 channel. These findings provide new insights into the mechanisms of pharmacological action on TWIK2 channel and opportunities for the development of selective TWIK2 channel modulators to treat related inflammatory diseases.

Calorie restriction ameliorates hyperglycemia, modulates the disordered gut microbiota, and mitigates metabolic endotoxemia and inflammation in type 2 diabetic rats

PURPOSE

The effects of calorie restriction (CR) on gut microbiota and the mechanism of CR ameliorating hyperglycemia in streptozotocin (STZ)-induced T2DM model rats were explored.

METHODS

High-fat diet and STZ injection were applied to induce T2DM model rats. Rats were divided into the following three groups: the control-diet ad libitum group, the T2DM model group fed with ad libitum diet, and the T2DM group fed with 30% restriction diet. 16S rRNA sequencing was used to determine the bacterial communities. Lipopolysaccharide (LPS)-binding protein (LBP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured.

RESULTS

Glucose tolerance and insulin sensitivity were improved by CR, as well as the levels of fasting and random plasma glucose. Besides, CR not only modulated the overall structure of gut microbiota but also had selective enrichment in anti-inflammatory bacteria such as Lachnospiraceae_NK4A136_group, Ruminococcaceae_9, Allobaculum, Alistipes, and Oscillibacter, and decreased pro-inflammatory pathogenic bacteria such as Bacteroides, Lachnoclostridium, and Bifidobacterium. Tax4Fun indicated that CR could regulate related functional pathways such as lipopolysaccharide biosynthesis, and the plasma levels of LBP, IL-6, and TNF-α were markedly reduced by CR, suggesting the mechanism of CR ameliorating hyperglycemia may associate with the modulation of disordered gut microbiota and the reduction of metabolic endotoxemia and inflammation.

CONCLUSION

CR could ameliorate hyperglycemia, the mechanism of which may associate with the alteration of the overall structure of gut microbiota, restoration of disordered microbiota function, and the downregulation of metabolic endotoxemia and inflammation in diabetic rats.

Yogurt Supplementation Attenuates Insulin Resistance in Obese Mice by Reducing Metabolic Endotoxemia and Inflammation

BACKGROUND

Inflammation is an underlying mechanism for the development of obesity-related health complications. Yogurt consumption inhibits obesity-associated inflammation, but the tissue-specific mechanisms have not been adequately described.

OBJECTIVES

We aimed to determine the tissue-specific responses by which yogurt supplementation inhibits inflammation.

METHODS

C57BL/6 male mice (5 wk old) were fed a Teklad Global 14% Protein Rodent Maintenance diet as a control or a high-fat diet (60% calories from fat) to induce obesity for 11 wk, followed by feeding a Western diet (WD; 43% carbohydrate and 42% fat) or WD supplemented with 5.6% lyophilized yogurt powder for 3 wk to test for the impact of yogurt supplementation. Markers of metabolic endotoxemia and inflammation were assessed in plasma and tissues. Cecal and fecal microbiota were profiled by 16S rRNA sequencing.

RESULTS

In obese mice, relative to the WD control group, yogurt supplementation attenuated HOMA-IR by 57% (P = 0.020), plasma TNF-α by 31% (P < 0.05) and colonic IFN-γ by 46% (P = 0.0034), which were accompanied by a 40% reduction in plasma LPS binding protein (LBP) (P = 0.0019) and 45% less colonic Lbp expression (P = 0.037), as well as alteration in the beta diversity of cecal microbiota (P = 0.0090) and relative abundance of certain cecal microbes (e.g., Lachnospiraceae Dorea longicatena with P = 0.049). There were no differences in the LBP, Lbp, and Cd14 levels in the liver and small intestine between obese mice with and without yogurt supplementation (P > 0.05).

CONCLUSIONS

Yogurt consumption inhibits obesity-induced inflammation in mice by modulating colonic endotoxin detoxification, changing the gut microbiota, and improving glucose metabolism. This work helps to establish the underlying mechanisms by which yogurt consumption affects markers of metabolic and immune health.

Fisetin inhibits lipopolysaccharide-induced inflammatory response by activating β-catenin, leading to a decrease in endotoxic shock

Fisetin is a naturally occurring flavonoid that possesses several pharmacological benefits including anti-inflammatory activity. However, its precise anti-inflammatory mechanism is not clear. In the present study, we found that fisetin significantly inhibited the expression of proinflammatory mediators, such as nitric oxide (NO) and prostaglandin E2 (PGE2), and cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Additionally, fisetin attenuated LPS-induced mortality and abnormalities in zebrafish larvae and normalized the heart rate. Fisetin decreased the recruitment of macrophages and neutrophils to the LPS-microinjected inflammatory site in zebrafish larvae, concomitant with a significant downregulation of proinflammatory genes, such as inducible NO synthase (iNOS), cyclooxygenase-2a (COX-2a), IL-6, and TNF-α. Fisetin inhibited the nuclear localization of nuclear factor-kappa B (NF-κB), which reduced the expression of pro-inflammatory genes. Further, fisetin inactivated glycogen synthase kinase 3β (GSK-3β) via phosphorylation at Ser9, and inhibited the degradation of β-catenin, which consequently promoted the localization of β-catenin into the nucleus. The pharmacological inhibition of β-catenin with FH535 reversed the fisetin-induced anti-inflammatory activity and restored NF-κB activity, which indicated that fisetin-mediated activation of β-catenin results in the inhibition of LPS-induced NF-κB activity. In LPS-microinjected zebrafish larvae, FH535 promoted the migration of macrophages to the yolk sac and decreased resident neutrophil counts in the posterior blood island and induced high expression of iNOS and COX-2a, which was accompanied by the inhibition of fisetin-induced anti-inflammatory activity. Altogether, the current study confirmed that the dietary flavonoid, fisetin, inhibited LPS-induced inflammation and endotoxic shock through crosstalk between GSK-3β/β-catenin and the NF-κB signaling pathways.

Inhibition of Proprotein Convertase Subtilisin/Kexin Type 9 Ameliorates Liver Fibrosis via Mitigation of Intestinal Endotoxemia

Lipopolysaccharide (LPS) is demonstrated to cause "two-hit" injury to liver. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in LPS clearance. Hepatocyte nuclear factor-1 alpha (HNF-1α) and sterol regulatory element-binding protein 2 (SREBP2) were reported to be responsible for PCSK9 gene transcription and regulation. We aim to clarify the expression status of PCSK9 during the process of liver fibrosis and to verify the effect on liver fibrosis via PCSK9 inhibition. In this study, we found that PCSK9 increased significantly in human and BDL mouse injured liver tissues, so did HNF-1α and SREBP2. No significant difference of plasma PCSK9 was observed. Inhibited PCSK9 using CRISPR-PCSK9 adeno-associated virus in BDL mice ameliorated liver inflammation and fibrosis, with LPS decrease in serum, without any change in intestinal wall integrity. PCSK9 expression of L02 hepatocytes can be induced by LPS; however, they lose the ability at high content of LPS. L02 cells increased LPS uptake after PCSK9 knockout. Taken together, these results suggest that, with PCSK9 increasing during liver fibrosis advancement, its inhibition can ameliorate liver injury by enhancing LPS uptake in hepatocytes; however, the enhancement is limited for destruction to hepatocytes by high LPS.

Gut-liver axis modulation in fructose-fed mice: a role for PPAR-alpha and linagliptin

Fructose dietary intake affects the composition of the intestinal microbiota and influences the development of hepatic steatosis. Endotoxins produced by gram-negative bacteria alter intestinal permeability and cause bacterial translocation. This study evaluated the effects of gut microbiota modulation by a purified PPAR-alpha agonist (WY14643), a DPP-4 inhibitor (linagliptin), or their association on intestinal barrier integrity, endotoxemia, and hepatic energy metabolism in high-fructose-fed C57BL/6 mice. Fifty mice were divided to receive the control diet (C group) or the high-fructose diet (HFRU) for 12 weeks. Subsequently, the HFRU group was divided to initiate the treatment with PPAR-alpha agonist (3.5 mg/kg/BM) and DPP-4 inhibitor (15 mg/kg/BM). The HFRU group had glucose intolerance, endotoxemia, and dysbiosis (with increased Proteobacteria) without changes in body mass in comparison with the C group. HFRU group showed damaged intestinal ultrastructure, which led to liver inflammation and marked hepatic steatosis in the HFRU group when compared to the C group. PPAR-alpha activation and DPP-4 inhibition countered glucose intolerance, endotoxemia, and dysbiosis, ameliorating the ultrastructure of the intestinal barrier and reducing Tlr4 expression in the liver of treated animals. These beneficial effects suppressed lipogenesis and mitigated hepatic steatosis. In conclusion, the results herein propose a role for PPAR-alpha activation, DPP-4 inhibition, and their association in attenuating hepatic steatosis by gut-liver axis modulation in high-fructose mice model. These observations suggest these treatments as potential targets to treat hepatic steatosis and avoid its progression.

Consumption of Cooked Black Beans Stimulates a Cluster of Some Clostridia Class Bacteria Decreasing Inflammatory Response and Improving Insulin Sensitivity

There is limited information on the effect of black beans (BB) as a source of protein and resistant starch on the intestinal microbiota. The purpose of the present work was to study the effect of cooked black beans with and without high fat and sugar (HF + S) in the diet on body composition, energy expenditure, gut microbiota, short-chain fatty acids, NF-κB, occluding and insulin signaling in a rat model and the area under the curve for glucose, insulin and incretins in healthy subjects. The consumption of BB reduced the percentage of body fat, the area under the curve of glucose, serum leptin, LPS, glucose and insulin concentrations and increased energy expenditure even in the presence of HF + S. These results could be mediated in part by modification of the gut microbiota, by increasing a cluster of bacteria in the Clostridia class, mainly R. bromii, C. eutactus, R. callidus, R. flavefaciens and B. pullicaecorum and by an increase in the concentration of fecal butyrate. In conclusion, the consumption of BB can be recommended to prevent insulin resistance and metabolic endotoxemia by modifying the gut microbiota. Finally, the groups fed BB showed lower abundance of hepatic FMO-3, even with a high-fat diet protecting against the production of TMAO and obesity.

Roux-en-Y gastric bypass decreases endotoxemia and inflammatory stress in association with improvements in gut permeability in obese diabetic rats

BACKGROUND

Postoperative modulation of the gut microbiome has been suggested to contribute to the metabolic benefits after metabolic surgery, but the mechanisms underlying these metabolic benefits remain unknown. Previously, we reported that Roux-en-Y gastric bypass (RYGB) surgery in Zucker diabetic fatty (ZDF) rats increased the abundance of Proteobacteria and Gammaproteobacteria. However, theoretically, these Gram-negative bacteria may elevate lipopolysaccharide (LPS) levels. Therefore, in this study we further investigated the potential mechanisms by which RYGB improves glucose homeostasis, endotoxemia, and inflammatory stress in ZDF rats.

METHODS

Rats were divided into three groups: (a) an RYGB group (RY); (b) a sham-operated group pair-fed with the RY group; and (c) a sham-operated group fed ad libitum. Changes in LPS, cytokine levels, intestinal permeability (evaluated using the fluorescein isothiocyanate-dextran method), and intestinal epithelial tight junction proteins zona occludins (ZO)-1, occludin, and claudin-1 were assessed 10 weeks postoperatively.

RESULTS

Rats that underwent RYGB exhibited sustained weight loss and reduced glucose, as well as lower cytokine and LPS concentrations, than rats in the control groups. In the colonic epithelium, ZO1 and claudin-1 (Cldn1) mRNA levels were higher in the RY than control groups. Intestinal permeability declined in the RY group and was positively correlated with LPS levels and negatively correlated with ZO-1, occludin, and claudin-1 expression.

CONCLUSIONS

The results demonstrate that RYGB can reduce the extent of endotoxemia and inflammation, which is associated with improved tight junction integrity and intestinal barrier strength. These effects may explain why a low level of inflammation is maintained after RYGB and the postoperative increase in Gram-negative bacteria.

Green tea extract prevents obesity in male mice by alleviating gut dysbiosis in association with improved intestinal barrier function that limits endotoxin translocation and adipose inflammation

Gut-derived endotoxin translocation provokes obesity by inducing TLR4/NFκB inflammation. We hypothesized that catechin-rich green tea extract (GTE) would protect against obesity-associated TLR4/NFκB inflammation by alleviating gut dysbiosis and limiting endotoxin translocation. Male C57BL/6J mice were fed a low-fat (LF) or high-fat (HF) diet containing 0% or 2% GTE for 8 weeks. At Week 7, fluorescein isothiocyanate (FITC)-dextran was administered by oral gavage before assessing its serum concentrations as a gut permeability marker. HF-feeding increased (P<.05) adipose mass and adipose expression of genes involved in TLR4/NFκB-dependent inflammation and macrophage activation. GTE attenuated HF-induced obesity and pro-inflammatory gene expression. GTE in HF mice decreased serum FITC-dextran, and attenuated portal vein and circulating endotoxin concentrations. GTE in HF mice also prevented HF-induced decreases in the expression of intestinal tight junction proteins (TJPs) and hypoxia inducible factor-1α while preventing increases in TLR4/NFκB-dependent inflammatory genes. Gut microbial diversity was increased, and the Firmicutes:Bacteroidetes ratio was decreased, in HF mice fed GTE compared with HF controls. GTE in LF mice did not attenuate adiposity but decreased endotoxin and favorably altered several gut bacterial populations. Serum FITC-dextran was correlated with portal vein endotoxin (P<.001; r_P=0.66) and inversely correlated with colonic mRNA levels of TJPs (P<.05; r_P=-0.38 to -0.48). Colonic TJPs mRNA were inversely correlated with portal endotoxin (P<.05; r_P=-0.33 to -0.39). These data suggest that GTE protects against diet-induced obesity consistent with a mechanism involving the gut-adipose axis that limits endotoxin translocation and consequent adipose TLR4/NFκB inflammation by improving gut barrier function.

Comprehensive preoperative regime of selective gut decontamination in combination with probiotics, and smectite for reducing endotoxemia and cytokine activation during cardiopulmonary bypass: A pilot randomized, controlled trial

BACKGROUND

Both selective digestive decontamination (SDD) and probiotics have been reported to reduce endotoxemia. However, the available results are conflicting and few studies have investigated the combined effect of SDD and probiotics. This study aimed to examine the effectiveness of a comprehensive preoperative regimen of SDD in combination with probiotics and smectite on perioperative endotoxemia and cytokine activation in patients who underwent elective cardiac surgery with cardiopulmonary bypass (CPB) in a pilot, prospective, randomized, controlled trial.

METHODS

Patients who underwent elective Aortic Valve Replacement or Mitral Valve Replacement surgery from July 2010 to March 2015 were included. In total, 30 eligible patients were randomly assigned to receive either the comprehensive preoperative regimen (n = 15) (a combination of preoperative SDD, probiotics, and smectite) or the control group (n = 15) who did not receive this treatment. The levels of endotoxin, IL-6, and procalcitonin were measured at the time before anesthesia induction, immediately after cardiopulmonary bypass (CPB), 24 hours after CPB, and 48 hours after CPB. The primary outcomes were changes in endotoxin, IL-6, and procalcitonin concentrations after CPB.

RESULTS

The mean levels of change in endotoxin levels after CPB in patients receiving the comprehensive preoperative regimen was marginally significantly lower than those in control group (F = 4.0, P = .0552) but was not significantly different for procalcitonin (F = .14, P = .7134). An interaction between group and time for IL-6 was identified (F = 4.35, P = .0231). The increase in IL-6 concentration immediately after CPB in the comprehensive preoperative group was significantly lower than that in the control group (P = .0112). The changes in IL-6 concentration at 24 hours and 48 hours after CPB were not significant between the comprehensive preoperative group and control group.

CONCLUSION

The present pilot, prospective, randomized, controlled study in patients undergoing cardiac surgery with CPB demonstrated that 3 days of a comprehensive preoperative regime of SDD in combination with probiotics and smectite may reduce the endotoxin and IL-6 levels after CPB compared with the control group.

The Transplantation of ω3 PUFA-Altered Gut Microbiota of fat-1 Mice to Wild-Type Littermates Prevents Obesity and Associated Metabolic Disorders

Altering the gut microbiome may be beneficial to the host and recently arose as a promising strategy to manage obesity. Here, we investigated the relative contribution of ω3 polyunsaturated fatty acid (PUFA)-mediated alterations in the microbiota to metabolic parameter changes in mice. Four groups were compared: male fat-1 transgenic mice (with constitutive production of ω3 PUFAs) and male wild-type (WT) littermates fed an obesogenic (high fat/high sucrose [HFHS]) or a control diet. Unlike WT mice, HFHS-fed fat-1 mice were protected against obesity, glucose intolerance, and hepatic steatosis. Unlike WT mice, fat-1 mice maintained a normal barrier function, resulting in a significantly lower metabolic endotoxemia. The fat-1 mice displayed greater phylogenic diversity in the cecum, and fecal microbiota transplantation from fat-1 to WT mice was able to reverse weight gain and to normalize glucose tolerance and intestinal permeability. We concluded that the ω3 PUFA-mediated alteration of gut microbiota contributed to the prevention of metabolic syndrome in fat-1 mice. It occurred independently of changes in the PUFA content of host tissues and may represent a promising strategy to prevent metabolic disease and preserve a lean phenotype.

The inhibition of inducible nitric oxide synthase and oxidative stress by agmatine attenuates vascular dysfunction in rat acute endotoxemic model

Vascular dysfunction leading to hypotension is a major complication in patients with septic shock. Inducible nitric oxide synthase (iNOS) together with oxidative stress play an important role in development of vascular dysfunction in sepsis. Searching for an endogenous, safe and yet effective remedy was the chief goal for this study. The current study investigated the effect of agmatine (AGM), an endogenous metabolite of l-arginine, on sepsis-induced vascular dysfunction induced by lipopolysaccharides (LPS) in rats. AGM pretreatment (10mg/kg, i.v.) 1h before LPS (5mg/kg, i.v.) prevented the LPS-induced mortality and elevations in serum creatine kinase-MB isoenzyme (CK-MB) activity, lactate dehydrogenase (LDH) activity, C-reactive protein (CRP) level and total nitrite/nitrate (NOx) level after 24h from LPS injection. The elevation in aortic lipid peroxidation illustrated by increased malondialdehyde (MDA) content and the decrease in aortic glutathione (GSH) and superoxide dismutase (SOD) were also ameliorated by AGM. Additionally, AGM prevented LPS-induced elevation in mRNA expression of iNOS, while endothelial NOS (eNOS) mRNA was not affected. Furthermore AGM prevented the impaired aortic contraction to KCl and phenylephrine (PE) and endothelium-dependent relaxation to acetylcholine (ACh) without affecting endothelium-independent relaxation to sodium nitroprusside (SNP).

IN CONCLUSION

AGM may represent a potential endogenous therapeutic candidate for sepsis-induced vascular dysfunction through its inhibiting effect on iNOS expression and oxidative stress.

Expression of Calgranulin Genes S100A8, S100A9 and S100A12 Is Modulated by n-3 PUFA during Inflammation in Adipose Tissue and Mononuclear Cells

Calgranulin genes (S100A8, S100A9 and S100A12) play key immune response roles in inflammatory disorders, including cardiovascular disease. Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) may have systemic and adipose tissue-specific anti-inflammatory and cardio-protective action. Interactions between calgranulins and the unsaturated fatty acid arachidonic acid (AA) have been reported, yet little is known about the relationship between calgranulins and the LC n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We explored tissue-specific action of calgranulins in the setting of evoked endotoxemia and n-3 PUFA supplementation. Expression of calgranulins in adipose tissue in vivo was assessed by RNA sequencing (RNASeq) before and after n-3 PUFA supplementation and evoked endotoxemia in the fenofibrate and omega-3 fatty acid modulation of endotoxemia (FFAME) Study. Subjects received n-3 PUFA (n = 8; 3600mg/day EPA/DHA) or matched placebo (n = 6) for 6–8 weeks, before completing an endotoxin challenge (LPS 0.6 ng/kg). Calgranulin genes were up-regulated post-LPS, with greater increase in n-3 PUFA (S100A8 15-fold, p = 0.003; S100A9 7-fold, p = 0.003; S100A12 28-fold, p = 0.01) compared to placebo (S100A8 2-fold, p = 0.01; S100A9 1.4-fold, p = 0.4; S100A12 5-fold, p = 0.06). In an independent evoked endotoxemia study, calgranulin gene expression correlated with the systemic inflammatory response. Through in vivo and in vitro interrogation we highlight differential responses in adipocytes and mononuclear cells during inflammation, with n-3 PUFA leading to increased calgranulin expression in adipose, but decreased expression in circulating cells. In conclusion, we present a novel relationship between n-3 PUFA anti-inflammatory action in vivo and cell-specific modulation of calgranulin expression during innate immune activation.

Resveratrol alleviates endotoxemia-associated adrenal insufficiency by suppressing oxidative/nitrative stress

We have recently demonstrated that endotoxin causes oxidative stress and overproduction of nitric oxide in adrenal glands, thereby leading to adrenocortical insufficiency. The aim of this study is to investigate the effects of resveratrol, a natural plant polyphenol with anti-oxidant and anti-nitrative properties, on endotoxemia-associated adrenocortical insufficiency. Resveratrol was administered immediately before injection of lipopolysaccharide (LPS). Twenty four hours later, the adrenocorticotropic hormone (ACTH) stimulation tests was been performed to measure the plasma corticosterone level and the adrenal gland tissues were collected for histopathologic examination, and determination of malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity, inducible nitric oxide synthase (iNOS) expression, nitric oxide (NO) and peroxynitrite production. Treatment with resveratrol significantly inhibited endotoxemia-induced iNOS expression, NO production, and peroxynitrite formation and also attenuated LPS-induced oxidative stress in the adrenal gland, as evidenced by the decrease of pro-oxidant biomarker (MDA), and the increases of anti-oxidant biomarkers (T-AOC, CAT and SOD activity). H&E staining demonstrated that administration of LPS resulted in increased into the adrenal gland. H&E-stained sections of adrenal glands demonstrated signs of leukocyte infiltration and hemorrhage during endotoxemia, which were significantly improved by resveratrol treatment. In addition, resveratrol reversed the LPS-induced downregulation of ACTH receptor and silent information regulator 1 (SIRT1) in adrenal gland, as well as adrenocortical hyporesponsiveness to ACTH. Resveratrol exerts protective effects against endotoxemia-associated adrenocortical insufficiency by suppressing oxidative/nitrative stress. These findings support the potential for resveratrol as a possible pharmacological agent to improve adrenocortical insufficiency resulting from oxidative/nitrative damage.

Lipopolysaccharide Cross-Tolerance Delays Platelet-Activating Factor-Induced Sudden Death in Swiss Albino Mice: Involvement of Cyclooxygenase in Cross-Tolerance

Lipopolysaccharide (LPS) signaling through Toll-like receptor-4 (TLR-4) has been implicated in the pathogenesis of many infectious diseases. Some believe that TLR-mediated pathogenicity is due, in part, to the lipid pro-inflammatory mediator platelet-activating factor (PAF), but this has been questioned. To test the direct contribution of PAF in endotoxemia in murine models, we injected PAF intraperitoneally into Swiss albino mice in the presence and absence of LPS. PAF alone (5 μg/mouse) caused death within 15-20 min, but this could be prevented by pretreating mice with PAF-receptor (PAF-R) antagonists or PAF-acetylhydrolase (PAF-AH). A low dose of LPS (5 mg/kg body wt) did not impair PAF-induced death, whereas higher doses (10 or 20 mg/kg body wt) delayed death, probably via LPS cross-tolerance. Cross-tolerance occurred only when PAF was injected simultaneously with LPS or within 30 min of LPS injection. Tolerance does not appear to be due to an abundant soluble mediator. Histologic examination of lungs and liver and measurement of circulating TNF-α and IL-10 levels suggested that the inflammatory response is not diminished during cross-tolerance. Interestingly, aspirin, a non-specific cyclooxygenase (COX) inhibitor, partially blocked PAF-induced sudden death, whereas NS-398, a specific COX-2 inhibitor, completely protected mice from the lethal effects of PAF. Both COX inhibitors (at 20 mg/kg body wt) independently amplified the cross-tolerance exerted by higher dose of LPS, suggesting that COX-derived eicosanoids may be involved in these events. Thus, PAF does not seem to have a protective role in endotoxemia, but its effects are delayed by LPS in a COX-sensitive way. These findings are likely to shed light on basic aspects of the endotoxin cross-tolerance occurring in many disease conditions and may offer new opportunities for clinical intervention.

Rice hull smoke extract protects mice against a Salmonella lipopolysaccharide-induced endotoxemia

Endotoxemia (sepsis, septic shock) is an inflammatory, virulent disease that results mainly from infection by Gram-negative bacteria. The present study investigates the inhibitory effects of a rice hull smoke extract (RHSE) against murine endotoxemia induced by Salmonella lipopolysaccharide and d-galactosamine (LPS/GalN). Pretreatment of the mice with RHSE via dietary administration for 2 weeks resulted in the suppression (in %) of LPS/GalN-induced catalase by 70.7, superoxide dismutase (SOD) by 54.6, and transaminase (GOT/GPT) liver enzymes by 40.6/62.5, the amelioration of necrotic liver lesions, and the reduction of tumor necrosis factor-α (TNF-α) by 61.1 and nitrite serum level by 83.4, as well as myeloperoxidase (MPO) enzyme associated with necrotic injury of the lung and kidney by 65.7 and 63.3, respectively. The RHSE also extended the lifespan of the toxemic mice. The results using inflammation biomarkers and from the lifespan studies suggest that the RHSE can protect mice against LPS/GalN-induced liver, lung, and kidney injuries and inflammation by blocking oxidative stress and TNF-α production, thereby increasing the survival of the toxic-shock-induced mice. These beneficial effects and previous studies on the antimicrobial effects against Salmonella Typhimurium in culture and in mice suggest that the smoke extract also has the potential to serve as a new multifunctional resource in human food and animal feeds. Possible mechanisms of the beneficial effects at the cellular and molecular levels and suggested food uses are discussed.

A polysaccharide isolated from the liquid culture of Lentinus edodes (Shiitake) mushroom mycelia containing black rice bran protects mice against a Salmonella lipopolysaccharide-induced endotoxemia

Endotoxemia (sepsis, septic shock) is an inflammatory, virulent disease that results mainly from bacterial infection. The present study investigates the inhibitory effect of a bioprocessed polysaccharide (BPP) isolated from the edible Lentinus edodes liquid mycelial mushroom culture supplemented with black rice bran against murine endotoxemia induced by the Salmonella lipopolysaccharide and d-galactosamine (LPS/GalN). BPP was obtained after dialysis against water using a cellulose tube with a molecular weight cutoff of 10000. BPP eluted as a single peak on an HPLC chromatogram. Acid hydrolysis of BPP showed the presence of the following sugars: fucose, galactose, galactosamine, glucose, glucosamine, mannose, rhamnose, and xylose. Treatment of BPP with β-glucanase reduced its immunostimulating activity, suggesting that the polysaccharide has a β-glucan structure. Pretreatment of mice with BPP via oral or intraperitoneal (ip) administration for 2 weeks resulted in the suppression of LPS/GalN-induced catalase, superoxide dismutase (SOD), and transaminase (GOT/GPT) liver enzymes, amelioration of necrotic liver lesions, and reduction of tumor necrosis factor α (TNF-α) and nitrite serum levels as well as myeloperoxidase (MPO) activity, an index of necrotic injury. Immunostimulating macrophage activity was up to 5.4-fold greater than that observed with the culture without the rice bran. BPP also extended the lifespan of the toxemic mice. These positive results with inflammation biomarkers and lifespan studies suggest that the BPP can protect mice against LPS/GalN-induced liver, lung, and kidney injuries and inflammation by blocking oxidative stress and TNF-α production, thus increasing the survival of the toxic shock-induced mice. The polysaccharide has the potential to serve as a new functional food.

Effects of ketamine, propofol, and ketofol on proinflammatory cytokines and markers of oxidative stress in a rat model of endotoxemia-induced acute lung injury

Intravenous lipopolysaccharide (LPS) leads to acute lung injury (ALI) in rats. The purpose of this study was to examine the anti-inflammatory and antioxidant efficacy of ketamine, propofol, and ketofol in a rat model of ALI. We induced ALI in rats via intravenous injection of LPS (15 mg kg(-1)). The animals were randomly separated into five groups: control, LPS only, LPS + ketamine (10 mg·kg(-1)·h(-1)), LPS + propofol (10 mg·kg(-1)·h(-1)), LPS + ketofol (5 mg·kg(-1)·h(-1) ketamine + 5 mg·kg(-1)·h(-1) propofol). LPS resulted in an increase in the release of pro-inflammatory cytokines, mRNA expression related with inflammation, production of nitric oxide, and lipid peroxidation. Ketamine prevented the increase in markers of oxidative stress and inflammation mediators, both in plasma and lung tissue. Propofol decreased the levels of cytokines in plasma and lung tissue, whereas it had no effect on the IL-1-beta level in lung tissue. Ketamine downregulated mediators of lung tissue inflammation and reduced the level of circulating cytokines and protected lung tissue against lipid peroxidation. Ketofol decreased the level of TNF-α and IL-1β in plasma, as well as expression of cyclooxygenase-2 mRNA and the nitrate/nitrite level in lung tissue. The results of this investigation support the hypothesis that ketamine may be effective in preventing ALI.

Insulin hypersensitivity induced by hepatic PTEN gene ablation protects from murine endotoxemia

Sepsis still remains a major cause for morbidity and mortality in patients. The molecular mechanisms underlying the disease are still enigmatic. A great number of therapeutic approaches have failed and treatment strategies are limited to date. Among those few admitted for clinical intervention, intensive insulin treatment has proven to be effective in the reduction of disease related complications in critically ill patients. Insulin effectively reduces glucose levels and thereby contributes to protection. On the other hand insulin is a potent signaling pathway activator. One of those is the PI3K signaling axis. Activation of PI3K is known to limit pro-inflammatory gene expression. Here we can show that in a mouse model of insulin hypersensitivity induced by the deletion of the PI3K antagonist PTEN, specifically in hepatic tissue, significant protection is conferred in murine models of lethal endotoxemia and sepsis. Acute inflammatory responses are diminished, glucose metabolism normalized and vascular activation is reduced. Furthermore we investigated the hepatic gene expression profile of relevant anti-inflammatory genes in PTEN deficient mice and found marked upregulation of PPARγ and HO-1. We conclude from our data that insulin hypersensitivity via sustained activation of the PI3K signaling pathway exerts protective effects in acute inflammatory processes.

Lipoic acid suppresses portal endotoxemia-induced steatohepatitis and pancreatic inflammation in rats

AIM: To examine the effect of α-lipoic acid (LA) on mild portal endotoxemia-induced steatohepatitis and associated pancreatic abnormalities in fructose-fed rats.

METHODS: Rats were randomly assigned into two groups with a regular or 60% fructose-enriched diet for 8 wk. After fructose feeding for 4 wk, rats were further divided into four subgroups: with intraportal saline (F_PV), with intraportal saline plus administration of LA (F_{PV + LA}), with lipopolysaccharide (LPS) infusion (F_PLPS), and with LPS infusion plus administration of LA (F_{PLPS + LA}). Rats were treated with LPS using intraportal infusion while LA was administered orally. Metabolite levels, superoxide levels, inflammatory markers, malondialdehyde content, glutathione content and toll-like receptor 4 (TLR4) gene expression were all measured using standard biochemical techniques. Pancreatic insulin secretion was evaluated by a hyperglycemic clamp technique. Histology of liver and pancreas tissues were evaluated using hematoxylin and eosin staining and immunohistochemistry.

RESULTS: Fructose-induced elevation in plasma C-reactive protein, amylase, superoxide, white blood cell count as well as in hepatic and pancreatic contents of malondialdehyde, tumor necrosis factor alpha and interleukin-6 were increased in animals treated with LPS and reversed with LA administration. The augmented hepatic gene expression of TLR4 in fructose-fed rats was further increased in those with intraportal LPS infusion, which was partially reversed by LA administration. Pathological examination showed inflammatory changes and leukocyte infiltration in hepatic and pancreatic islets of animals treated with LPS but were rarely observed in those with LA treatment. In addition to affects on the liver, impaired pancreatic insulin secretion seen in fructose-fed rats was deteriorated in with LPS treatment and partially reversed with LA administration.

CONCLUSION: These data suggest LA could significantly suppress mild portal-endotoxemia but not fructose-induced liver and pancreatic abnormalities in a rodent model for metabolic syndrome.

Infecting mice with recombinant Ad5-BPI₂₃-Fcγ1 virus protects against systemic Escherichia coli challenge

Infections caused by Gram-negative bacteria (GNB) are increasingly common and can result in significant mortality rates due to the development of sepsis. To examine the potential usage of a recombinant Ad5-BPI(23)-Fcγ1 virus as a biological treatment against systemic infection by GNB, a construct containing the human bactericidal/permeability increasing protein (BPI) gene, encoding the functional N terminus (amino acid residues 1-199) of human BPI, and the Fcγ1 gene, encoding the Fc segment of human immunoglobulin G1, was inserted into an adenovirus serotype 5 (Ad5) chromosome to produce a recombinant Ad5-BPI(23)-Fcγ1 virus. Human A549 cells in culture and BALB/c mice were infected with the recombinant Ad5-BPI(23)-Fcγ1 virus and BPI(23)-Fcγ1 expression was confirmed by Western blot analysis and ELISA. The concentrations of BPI(23)-Fcγ1 protein were 5.59 µg ml(-1) in vitro and 21.37 ng ml(-1) in vivo and it was observed that these concentrations were sufficient to decrease endotoxin concentrations while enhancing bactericidal activity. In addition, mice treated with the recombinant Ad5-BPI(23)-Fcγ1 virus had decreased levels of IL-1β and TNF-α and were protected from an E. coli O111 : B4 challenge. Our data support the concept that Ad5-mediated BPI(23)-Fcγ1 gene delivery could be used as an ancillary biological treatment in the management of infection caused by GNB.

ATP-gated P2X1 ion channels protect against endotoxemia by dampening neutrophil activation

BACKGROUND

In sepsis, extracellular ATP, secreted by activated platelets and leukocytes, may contribute to the crosstalk between hemostasis and inflammation. Previously, we showed that, in addition to their role in platelet activation, ATP-gated P2X(1) ion channels are involved in promoting neutrophil chemotaxis.

OBJECTIVES

To elucidate the contribution of P2X(1) ion channels to sepsis and the associated disturbance of hemostasis.

METHODS

We used P2X(1) (-/-) mice in a model of lipopolysaccharide (LPS)-induced sepsis. Hemostasis and inflammation parameters were analyzed together with outcome. Mechanisms were further studied ex vivo with mouse and human blood or isolated neutrophils and monocytes.

RESULTS

P2X(1) (-/-) mice were more susceptible to LPS-induced shock than wild-type mice, despite normal cytokine production. Plasma levels of thrombin-antithrombin complexes were higher, thrombocytopenia was worsened, and whole blood coagulation time was markedly reduced, pointing to aggravated hemostasis disturbance in the absence of P2X(1). However, whole blood platelet aggregation occurred normally, and P2X(1) (-/-) macrophages displayed normal levels of total tissue factor activity. We found that P2X(1) (-/-) neutrophils produced higher amounts of reactive oxygen species. Increased amounts of myeloperoxidase were released in the blood of LPS-treated P2X(1) (-/-) mice, and circulating neutrophils and monocytes expressed higher levels of CD11b. Neutrophil accumulation in the lungs was also significantly augmented, as was lipid peroxidation in the liver. Desensitization of P2X(1) ion channels led to increased activation of human neutrophils and enhanced formation of platelet-leukocyte aggregates.

CONCLUSIONS

P2X(1) ion channels play a protective role in endotoxemia by negatively regulating systemic neutrophil activation, thereby limiting the oxidative response, coagulation, and organ damage.

[Study on the anti-endotoxin effect of saponin from Tupistra chinensis]

OBJECTIVE

To investigate the effect of saponin from Tupistra chinensis Baker (STCB) on lethal toxicity of endotoxin in mice and explore the underlying mechanism.

METHODS

Mouse models of endotoxin-induced death and endotoximia were established by intraperitoneal administration of KM mice with lipopolysaccharides (LPS) from Pseudomonas aeruginosa in doses of 60 mg/kg and 10 mg/kg respectively. Mouse survival rate and survival time were recorded and the serum levels of interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) in endotoximia mice were measured by enzyme-linked immunosorbent assay (ELISA). Mouse peritoneal exudate cells induced by LPS were used as an in vitro inflammatory model,which was then intervened with STCB and the levels of IL-1beta and TNF-alpha in the culture supernatants were measured by ELISA.

RESULTS

The survival rates of mice prophylactically treated with STCB (200 and 400 mg/kg, in 5 consecutive days) were slightly higher compared with that in model group,but no statistical difference was observed (P>0.05). The survival time was much longer in the treated group (P<0.05). The serum levels of IL-1beta and TNF-alpha in STCB-treated mice (200 and 400 mg/kg, in 5 consecutive days) were significantly lower compared with those in model group (P<0.05). STCB (20 and 40 microg/mL) remarkably inhibited LPS-induced IL-1beta and TNF-alpha production by peritoneal exudate cells in vitro (P<0.05).

CONCLUSION

Saponin from Tupistra chinensis showed beneficial effect on the prevention of mice from lipopolysaccharides-induced death, in which down regulation of IL-1beta and TNF-alpha expression might be involved.

Berberine protects against lipopolysaccharide-induced intestinal injury in mice via alpha 2 adrenoceptor-independent mechanisms

AIM

To investigate the mechanisms responsible for the protective action of berberine (Ber) against gut damage in endotoxemic mice.

METHODS

Male BALB/c mice were administered intragastrically with distilled water (0.1 mL/10 g), Ber (50 mg/kg) alone, yohimbine (2 mg/kg) alone, or Ber (50 mg/kg) in combination with yohimbine (2 mg/kg) for 3 d. On the third day, lipopolysaccharide (LPS, 18 mg/kg) or normal saline was intraperitoneally injected one hour after the intragastric administration. Following the treatment, intestinal injury in the ileum was histopathologically accessed; enterocyte apoptosis was examined using TUNEL method; Toll-like receptor 4 (TLR4) mRNA expression was measured using RT-PCR assay; inhibitor protein-κBα (I-κBα) phosphorylation and myeloperoxidase content were examined using Western blloting. The macrophage inflammatory protein-2 (MIP-2) production was measured using ELISA assay.

RESULTS

Mice challenged with LPS caused extensive ileum injury, including a significantly increased injury score, decreased intestinal villus height, reduced gut mucosal weight and increased intestinal permeability. Furthermore, LPS significantly induced enterocyte apoptosis, increased TLR4 mRNA expression, I-κBα phosphorylation, MIP-2 production and myeloperoxidase content in the ileum. Pretreatment with Ber significantly alleviated all the alterations in the ileum in the endotoxemic mice. Pretreatment with the α2-adrenoceptor antagonist yohimbine did not block the protective action of Ber against LPS-induced intestinal injury. In addition, treatment with yohimbine alone did not prevent LPS-induced intestinal injury.

CONCLUSION

Pretreatment with Ber provides significant protection against LPS-induced intestinal injury in mice, via reducing enterocyte apoptosis, inhibiting the TLR4-nuclear factor κB-MIP-2 pathway and decreasing neutrophil infiltration that are independent of α2-adrenoceptors.

[Preparation of polyclonal antibody of recombinant human thioredoxin-1 and its protective effects on neonatal rats with endotoxemia]

OBJECTIVE

To clone the gene human thioredoxin 1 (hTrx-1) expressing its protein in the E.coli expression system and to obtain its polyclonal antibody, and to study the protective effects of hTrx-1 on neonatal rats with endotoxemia.

METHODS

DNA encoding hTrx-1 from fetal liver cells was isolated by RT-PCR. The hTrx-1 was cloned to the prokaryotic expression plasmid PET-28a to induce its protein expression in the E.coli expression system. The purified hTrx-1 was injected into rats to prepare polyclonal antibody. Newborn Sprague-Dawley rats were randomly assigned to three groups: control, lipopolysaccharide (LPS) and hTrx-1 (n=12 each). The control and the LPS groups were intraperitoneally injected with normal saline and LPS (5 mg/kg), respectively. The hTrx-1 group received an intraperitoneal injection of hTrx-1 (10 mg/kg) 30 minutes before LPS injection. The mortality rate 24 hrs after injection was compared between the three groups.

RESULTS

The prokaryotic expression plasmid PET-28a-hTrx-1 was constructed. The hTrx-1 protein was expressed and purified. The polyclonal antibody of hTrx-1 with the titer of 1∶51200 was prepared. The mortality rate of the control, LPS and hTrx-1 groups was 0, 67% and 17%, respectively (χ2=14.400, P<0.01).

CONCLUSIONS

The polyclonal antibody of hTrx-1 is prepared successfully. The hTrx-1 protein has protective effects on neonatal rats with endotoxiamia.

Propolis derivatives inhibit the systemic inflammatory response and protect hepatic and neuronal cells in acute septic shock

BACKGROUND

Severe pathogenic infection triggers excessive release of cytokines as part of the massive inflammatory response associated with septic shock.

OBJECTIVES

To investigate the protective effect of caffeic acid phenethyl ester (CAPE) against lipopolysaccharide (LPS) induced endotoxemia, hepatic and neuronal damage and the associated systemic inflammatory response (SIR).

METHODS

Fifty male Wister rats were divided into: control, LPS, and CAPE+LPS groups. Plasma concentrations of various cytokines, including TNF-α, IL-1α, IL-1β, IL-6, IL-4, IL-10, and sICAM-1 were evaluated. In addition, the histopathological changes in the hepatic and neural cells were assessed.

RESULTS

The LPS group showed high inflammatory cytokines and sICAM-1 levels reflecting the presence of SIR. Hepatocyte necrosis, apoptosis, extensive hemorrhage and inflammatory cellular infiltration together with brain astrocytes swelling, early neuron injury and presence of inflammatory foci confirmed the toxic tissue damage. Use of CAPE decreased the inflammatory cytokines and increased the anti-inflammatory cytokines levels. This biochemical evidence of decreased SIR was confirmed histologically by decreased cellular infiltration in the liver and brain tissue which coincides with preserved structure and protection of the liver and brain cells from the toxic effects of LPS.

CONCLUSION

The ability of CAPE to alleviate the SIR, hepatic and neuronal cell damage induced by LPS and galactosamine could be attributed to its ability to reverse the imbalance of the pro- and anti-inflammatory cytokines which may lead to the inhibition of adhesion molecules' expression. CAPE is a promising agent that could help in the prophylaxis and treatment of septic shock.

[The effect of extracellular recombinant human heat shock protein 70 (Hsp70) on protein pattern observed after endotoxin-induced macrophage activation]

The protein pattern of mouse macrophage strain (J774) has been investigated using 2D electrophoresis after combined action of bacterial endotoxins (LPS), heat shock treatment (HS) and administration of recombinant human Hsp70. The investigation demonstrated significant protective effect of HS and recombinant Hsp70 treatment applied before LPS introduction. This effect is apparently realized by means of several signal transduction systems. In the course of the investigation, we have identified eight proteins, which exhibited pronounced changes in their synthesis due to combined treatment. The data accumulated may shed light on molecular mechanisms underlying protective antiseptic action of HS and/or recombinant Hsp70 applied before LPS administration.

Methylene chloride fraction of the leaves of Thuja orientalis inhibits in vitro inflammatory biomarkers by blocking NF-κB and p38 MAPK signaling and protects mice from lethal endotoxemia

AIM OF THE STUDY

Thuja orientalis (TO) has been a recognized herbal medicine across Northeast Asian countries for thousands of years and used for the treatment of various inflammatory diseases through as yet undefined mechanisms. In this study, we set out to determine whether the anti-inflammatory effects of this plant are mediated to suppress mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) activation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells.

MATERIALS AND METHODS

RAW 264.7 cells were pretreated with the methylene chloride fraction of TO (MTO) and stimulated with LPS. Nitric oxide (NO) release was determined by the accumulation of nitrite in the culture supernatants and tumor necrosis factor-α (TNF-α) and IL-6 secretion were determined by immunoenzymatic assay. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were evaluated via RT-PCR and Western blotting. NF-κB activation was also evaluated by reporter gene assay and electrophoretic mobility shift assay (EMSA). In addition, the protective effect of MTO was evaluated by use of the LPS-induced endotoxin shock model in mice.

RESULTS

We found that MTO significantly suppressed LPS-stimulated NO and IL-6 production without affecting cell viability. MTO inhibited the expression of LPS-induced iNOS and COX-2 protein and their mRNA expression. Also, TNF-α and IL-6 secretion were decreased by MTO in both PMA and ionomycin-stimulated splenocytes. As a result, MTO inhibited pro-inflammatory cytokines such as TNF-α and IL-6, which is hypothesized as being due to the suppression of LPS-induced p38 MAPK and NF-κB activation. Moreover, MTO improved the survival rate during lethal endotoxemia by inhibiting the production of TNF-α in an animal model and our LC-MS analysis showed that a major component of MTO was pinusolide.

CONCLUSIONS

We demonstrate here the evidence that the methylene chloride fraction of Thuja orientalis (MTO) potentially inhibits the biomarkers related to inflammation in vitro and in vivo, and might be provided as a potential candidate for the treatment of inflammatory diseases.

Plasma lipoproteins are required for both basal and stress-induced adrenal glucocorticoid synthesis and protection against endotoxemia in mice

Lipoprotein-associated cholesterol has been suggested to make a significant contribution to adrenal steroidogenesis in vivo. To determine whether lipoproteins indeed contribute to optimal adrenal steroidogenesis in mice, in the current study we have determined the effect of relative lipoprotein deficiency on adrenal steroidogenesis in C57BL/6 wild-type mice. Feeding C57BL/6 mice the lipid-lowering drug probucol (0.25% wt/wt) for 2 wk induced a 90% decrease in plasma high-density lipoprotein (HDL) cholesterol levels and a 77% reduction in low-density lipoprotein (LDL) cholesterol levels. Neutral lipid stores were depleted upon probucol treatment specifically in the glucocorticoid-producing zona fasciculata of the adrenal, leading to a 44% decreased plasma corticosterone level under basal conditions. Exposure to lipopolysaccharide (LPS) induced a 37% increase in the adrenal uptake of HDL cholesteryl esters. Probucol-treated mice could induce only a relatively minor corticosterone response upon a LPS challenge compared with controls, which coincided with an approximately twofold increased hepatic expression level of interleukin-6 and tumor necrosis factor (TNF)α and an 89% higher TNFα response in plasma. Furthermore, a compensatory two- to fivefold upregulation of LDL receptor (cholesterol uptake) and HMG-CoA reductase (cholesterol synthesis) expression was noticed in the adrenals of probucol-treated mice. In conclusion, we have shown that lipoprotein deficiency in mice as a result of probucol feeding is associated with decreased adrenal cortex cholesterol levels, a lower basal and stress-induced plasma glucocorticoid level, and an increased susceptibility to LPS-induced inflammation. Therefore, it is suggested that plasma lipoproteins are required for optimal adrenal steroidogenesis and protection against endotoxemia in mice.

Effects of IL-18 and IL-10 pre-treatment on the alteration of endogenous cytokines in liver and spleen of mice with experimental endotoxemia

Mechanisms of interleukin-18 (IL-18) and interleukin-10 (IL-10) in lipopolysaccharide (LPS) induced endotoxemia are not clear; their protective role is being investigated so that they may effectively modulate the host cytokine levels during endotoxemia. The aim of the study was to evaluate protective effects of IL-18 and IL-10 in experimentally induced endotoxemia in mice correlating the changes in tissue anti-oxidant enzymes and circulating cytokines. Liver injury was determined by estimation of serum glutamate oxalate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT), serum nitric oxide (NOx), hepatic anti-oxidant enzyme and cytokine content in LPS (250 microg/kg) induced endotoxemic mice receiving either IL-18 (500 ng/mouse) or IL-10 (600 ng/mouse) treatment. Mice (87% of IL-10 treated and 74% of IL-18 treated) survived when administered prior to LPS challenge. Pre-treatment of mice with either IL-10 or IL-18 followed by LPS, lead to reduction in SGPT and SGOT level, serum NOx, and altered hepatic anti-oxidant enzymes activity and myeloperoxidase activity than the only LPS treated group. Marked reduction in the amounts of LPS-induced hepatic and splenic TNF-u content has been observed after IL-10 pre-treatment. Results suggested that attenuating the induction of TNF-alpha and IFN-gamma and subsequent induction of nitric oxide formation in response to LPS may in part account for efficient protection by IL-18 and IL-10 in the reduction of LPS-induced liver injury.

[Protection of PD-1 against LPS-induced endotoxemia and the underlying mechanism]

OBJECTIVE

Gram-negative bacteria-induced multiple organ failure/dysfunction syndrome (MOF/MODS) is one of the leading causes of death through the world. The member of immunoglobulin family programmed death-1 (PD-1) is a negative immune regulator. This study investigated the protective effect of PD-1 as well as the underlying mechanism in LPS-induced endotoxemia.

METHODS

Ten PD-1(+/+) and ten PD-1 knockout (PD-1(-/-)) mice were injected peritoneally with LPS (10 mg/kg), and the survival was observed within 72 hrs after LPS injection. The other 40 PD-1(+/+) and 40 PD-1(-/-) mice were injected peritoneally with LPS (5 mg/kg). Blood samples were collected before injection and 1.5, 3 and 6 hrs after LPS injection (n=10 each time point). Serum levels of various inflammatory mediators were measured using ELISA.

RESULTS

The survival rate in PD-1(-/-) mice was noticeably lower than that in PD-1(+/+) mice after 10 mg/kg LPS injection. Serum levels of inflammatory mediators TNF-α, IL-1β, IL-12 and IL-17 in PD-1/mice were higher than those in PD-1(+/+) mice after 5 mg/kg LPS injection.

CONCLUSIONS

PD-1 can protect mice from LPS-induced endotoxemia probably through its regulation on inflammatory mediator production.

Distamycin A inhibits HMGA1-binding to the P-selectin promoter and attenuates lung and liver inflammation during murine endotoxemia

BACKGROUND

The architectural transcription factor High Mobility Group-A1 (HMGA1) binds to the minor groove of AT-rich DNA and forms transcription factor complexes ("enhanceosomes") that upregulate expression of select genes within the inflammatory cascade during critical illness syndromes such as acute lung injury (ALI). AT-rich regions of DNA surround transcription factor binding sites in genes critical for the inflammatory response. Minor groove binding drugs (MGBs), such as Distamycin A (Dist A), interfere with AT-rich region DNA binding in a sequence and conformation-specific manner, and HMGA1 is one of the few transcription factors whose binding is inhibited by MGBs.

OBJECTIVES

To determine whether MGBs exert beneficial effects during endotoxemia through attenuating tissue inflammation via interfering with HMGA1-DNA binding and modulating expression of adhesion molecules.

METHODOLOGY/PRINCIPAL FINDINGS

Administration of Dist A significantly decreased lung and liver inflammation during murine endotoxemia. In intravital microscopy studies, Dist A attenuated neutrophil-endothelial interactions in vivo following an inflammatory stimulus. Endotoxin induction of P-selectin expression in lung and liver tissue and promoter activity in endothelial cells was significantly reduced by Dist A, while E-selectin induction was not significantly affected. Moreover, Dist A disrupted formation of an inducible complex containing NF-kappaB that binds an AT-rich region of the P-selectin promoter. Transfection studies demonstrated a critical role for HMGA1 in facilitating cytokine and NF-kappaB induction of P-selectin promoter activity, and Dist A inhibited binding of HMGA1 to this AT-rich region of the P-selectin promoter in vivo.

CONCLUSIONS/SIGNIFICANCE

We describe a novel targeted approach in modulating lung and liver inflammation in vivo during murine endotoxemia through decreasing binding of HMGA1 to a distinct AT-rich region of the P-selectin promoter. These studies highlight the ability of MGBs to function as molecular tools for dissecting transcriptional mechanisms in vivo and suggest alternative treatment approaches for critical illness.

[Antibacterial therapy in surgical treatment of chronic hepatic abscess]

The results of surgical treatment of 58 patients for chronic hepatic abscess were presented. In patients of the main group hepatic resection was performed and in a control one--sanation and drainage of the abscess cavity. Antibacterial therapy was conducted in patients of both groups before and after operative treatment. The peculiarities and common efficacy of antibacterial therapy depending on the operative treatment kind were noted.

[Evaluation of endogenous intoxication from average molecular weight peptides during emergency situations]

Determination of the serum content of average molecular weight peptides that are markers of endogenous intoxication in the burnt, patients with acute poisoning by psychopharmacologicals, pancreatic necrosis, generalized peritonitis, small pelvic inflammation may serve as an additional laboratory criteria for rating the severity of critical conditions, predicting the development of complications, the outcome of diseases, and evaluating the efficiency of treatment.

Lactobacillus GG treatment ameliorates alcohol-induced intestinal oxidative stress, gut leakiness, and liver injury in a rat model of alcoholic steatohepatitis

Because only 30% of alcoholics develop alcoholic liver disease (ALD), a factor other than heavy alcohol consumption must be involved in the development of alcohol-induced liver injury. Animal and human studies suggest that bacterial products, such as endotoxins, are the second key co-factors, and oxidant-mediated gut leakiness is one of the sources of endotoxemia. Probiotics have been used to prevent and treat diseases associated with gut-derived bacterial products and disorders associated with gut leakiness. Indeed, "probiotic"Lactobacillus rhamnosus has been successfully used to treat alcohol-induced liver injury in rats. However, the mechanism of action involved in the potential beneficial effects of L. rhamnosus in alcohol liver injury is not known. We hypothesized that probiotics could preserve normal barrier function in an animal model of ALD by preventing alcohol-induced oxidative stress and thus prevent the development of hyperpermeability and subsequent alcoholic steatohepatitis (ASH). Male Sprague-Dawley rats were gavaged with alcohol twice daily (8 gm/kg) for 10 weeks. In addition, alcoholic rats were also treated with once daily gavage of either 2.5 x 10(7) live L. rhamnosus Gorbach-Goldin (LGG) or vehicle (V). Intestinal permeability (baseline and at 10 weeks) was determined using a sugar bolus and GC analysis of urinary sugars. Intestinal and liver tissues were analyzed for markers of oxidative stress and inflammation. In addition, livers were assessed histologically for severity of ASH and total fat (steatosis). Alcohol+LGG (ALC+LGG)-fed rats had significantly (P< or =.05) less severe ASH than ALC+V-fed rats. L. rhamnosus Gorbach-Goldin also reduced alcohol-induced gut leakiness and significantly blunted alcohol-induced oxidative stress and inflammation in both intestine and the liver. L. rhamnosus Gorbach-Goldin probiotic gavage significantly ameliorated ASH in rats. This improvement was associated with reduced markers of intestinal and liver oxidative stress and inflammation and preserved gut barrier function. Our study provides a scientific rationale to test probiotics for treatment and/or prevention of alcoholic liver disease in man.

[Effect of the amount of portal blood stasis removal on endotoxemia and liver function after liver transplantation]

OBJECTIVE

To investigate the influence of the amount of portal blood stasis removal on endotoxemia and liver function after liver transplantation.

METHODS

Forty-seven patients who received liver transplantation from February 2006 to November 2007 were divided into 2 groups according to the amount of portal blood stasis removal during operation: group A (n = 26) 50 ml and group B (n = 21) 200 ml of portal blood stasis removal respectively. The levels of plasma endotoxin, D-lactate, tumor necrosis factor-alpha, interleukin-6, liver function and blood coagulation were examined and analyzed.

RESULTS

Under the condition of no significant difference in sex, age, primary liver diseases and Child-pugh's classification, cold ischemic time, total operation and anhepatic time, operation methods, volume of blood loss and transfusion, and all preoperative observations. Most of observations showed the restoration of the patients in group B was better than that in group A. The plasma levels of endotoxin, D-lactate, tumor necrosis factor-alpha, interleukin-6, alanine aminotransferase, aspartate aminotransferase, prothrombin time and activated partial thromboplastin time in group B were significantly lower than those in group A (P < 0.05). The level of plasma prealbumin in group B was significantly higher than that in group A (P < 0.05).

CONCLUSIONS

The removal of 200 ml portal blood stasis leads to a better results than that of 50 ml, and it can help alleviate endotoxemia and facilitate the restoration of the liver function after liver transplantation.

Changes in gut microbiota control metabolic endotoxemia-induced inflammation in high-fat diet-induced obesity and diabetes in mice

OBJECTIVE

Diabetes and obesity are characterized by a low-grade inflammation whose molecular origin is unknown. We previously determined, first, that metabolic endotoxemia controls the inflammatory tone, body weight gain, and diabetes, and second, that high-fat feeding modulates gut microbiota and the plasma concentration of lipopolysaccharide (LPS), i.e., metabolic endotoxemia. Therefore, it remained to demonstrate whether changes in gut microbiota control the occurrence of metabolic diseases.

RESEARCH DESIGN AND METHODS

We changed gut microbiota by means of antibiotic treatment to demonstrate, first, that changes in gut microbiota could be responsible for the control of metabolic endotoxemia, the low-grade inflammation, obesity, and type 2 diabetes and, second, to provide some mechanisms responsible for such effect.

RESULTS

We found that changes of gut microbiota induced by an antibiotic treatment reduced metabolic endotoxemia and the cecal content of LPS in both high-fat-fed and ob/ob mice. This effect was correlated with reduced glucose intolerance, body weight gain, fat mass development, lower inflammation, oxidative stress, and macrophage infiltration marker mRNA expression in visceral adipose tissue. Importantly, high-fat feeding strongly increased intestinal permeability and reduced the expression of genes coding for proteins of the tight junctions. Furthermore, the absence of CD14 in ob/ob CD14(-)(/)(-) mutant mice mimicked the metabolic and inflammatory effects of antibiotics.

CONCLUSIONS

This new finding demonstrates that changes in gut microbiota controls metabolic endotoxemia, inflammation, and associated disorders by a mechanism that could increase intestinal permeability. It would thus be useful to develop strategies for changing gut microbiota to control, intestinal permeability, metabolic endotoxemia, and associated disorders.

[Reamberin application in the treatment of obturational jaundice of nontumoral etiology]

The influence of the preparation reamberin on endogenic intoxication severity in the patients, operated on for obturational jaundice of nontumoral etiology, was studied up. In 10 patients 1.5% solution of reamberin, infused continuously intravenously in 400 ml/day dosage during 3-10 days, was applied in complex postoperative therapy. It was established, that obturational jaundice of nontumoral etiology goes together with endogenic intoxication and the antioxidant defence system (ADS) inhibition. The preparation reamberin application had promoted more rapid normalization of the endotoxicosis and ADS indexes, comparing with such in controls.

The IFN-inducible GTPase LRG47 (Irgm1) negatively regulates TLR4-triggered proinflammatory cytokine production and prevents endotoxemia

LRG47/Irgm1, a 47-kDa IFN-inducible GTPase, plays a major role in regulating host resistance as well as the hemopoietic response to intracellular pathogens. LRG47 expression in macrophages has been shown previously to be stimulated in vitro by bacterial LPS, a TLR4 ligand. In this study, we demonstrate that induction of LRG47 by LPS is not dependent on MyD88 signaling, but rather, requires STAT-1 and IFN-beta. In addition, LRG47-deficient mice are highly susceptible to LPS, but not TLR2 ligand-induced shock, an outcome that correlates with enhanced proinflammatory cytokine production in vitro and in vivo. Further analysis revealed that LPS-stimulated LRG47-deficient macrophages display enhanced phosphorylation of p38, a downstream response associated with TLR4/MyD88 rather than IFN-beta/STAT-1 signaling. In contrast, LPS-induced phosphorylation of IFN regulatory factor-3 and expression of IFN-beta or the type I IFN-regulated genes, CCL5 and CCL10, were unaltered in LRG47(-/-) cells. Together, these observations indicate that in LPS-stimulated murine macrophages LRG47 is induced by IFN-beta and negatively regulates TLR4 signaling to prevent excess proinflammatory cytokine production and shock. Thus, our findings reveal a new host-protective function for this GTPase in the response to pathogenic encounter.

Inhibition of inducible nitric oxide synthase attenuates acute endotoxin-induced lung injury in rats

1. In the present study, we investigated the effects of the inducible nitric oxide (iNOS) inhibitors S-methylisothiourea (SMT) and l-N(6)-(1-iminoethyl)-lysine (l-Nil) on endotoxin-induced acute lung injury (ALI), as well as the associated physiological, biomedical and pathological changes, in anaesthetized Sprague-Dawley rats and in rat isolated perfused lungs. 2. Endotoxaemia was induced by an intravenous (i.v.) infusion of lipopolysaccharide (LPS; Escherichia coli 10 mg/kg). Lipopolysaccharide produced systemic hypotension and tachycardia. It also increased the lung weight/bodyweight ratio, lung weight gain, exhaled nitric oxide (NO), the protein concentration in bronchoalveolar lavage and microvascular permeability. 3. Following infusion of LPS, plasma nitrate/nitrite, methyl guanidine, pro-inflammatory cytokines (tumour necrosis factor-alpha and interleukin-1beta) were markedly elevated. Pathological examination revealed severe pulmonary oedema and inflammatory cell infiltration. Pretreatment with SMT (3 mg/kg, i.v.) or l-Nil (3 mg/kg, i.v.) significantly attenuated the LPS-induced changes and ALI. 4. The results suggest that the inflammatory responses and ALI following infusion of LPS are due to the production of NO, free radicals and pro-inflammatory cytokines through the iNOS system. Inhibition of iNOS is effective in mitigating the endotoxaemic changes and lung pathology. Inhibitors of iNOS may be potential therapeutic agents for clinical application in patients with acute respiratory distress syndrome.

Hypoxic preconditioning attenuates lipopolysaccharide-induced oxidative stress in rat kidneys

Chronic hypoxic (CH) preconditioning reduces superoxide-induced renal dysfunction via the upregulation of superoxide dismutase (SOD) activity and contents. Endotoxaemia reduces renal antioxidant status. We hypothesize that CH preconditioning might protect the kidney from subsequent endotoxaemia-induced oxidative injury. Endotoxaemia was induced by intraperitoneal injection of lipopolysaccharide (LPS; 4 mg kg(-1)) in rats kept at sea level (SL) and rats with CH in an altitude chamber (5500 m for 15 h day(-1)) for 4 weeks. LPS enhanced xanthine oxidase (XO) and gp91phox (catalytic subunit of NADPH oxidase) expression associated with burst amount of superoxide production from the SL kidney surface and renal venous blood detected by lucigenin-enhanced chemiluminescence. LPS induced a morphologic-independent renal dysfunction in baseline and acute saline loading stages and increased renal IL-1beta protein and urinary protein concentration in the SL rats. After 4 weeks of induction, CH significantly increased Cu/ZnSOD, MnSOD and catalase expression (16 +/- 17, 128 +/- 35 and 48 +/- 21, respectively) in renal cortex, and depressed renal cortex XO (44 +/- 16%) and renal cortex (20 +/- 9%) and medulla (28 +/- 11%) gp91phox when compared with SL rats. The combined effect of enhanced antioxidant proteins and depressed oxidative proteins significantly reduced LPS-enhanced superoxide production, renal XO and gp91phox expression, renal IL-1beta production, and urinary protein level. CH also ameliorated LPS-induced renal dysfunction in the baseline and acute saline loading periods. We conclude that CH treatment enhances the intrarenal antioxidant/oxidative protein ratio to overcome endotoxaemia-induced reactive oxygen species formation and inflammatory cytokine release.

Exercise training attenuates septic responses in conscious rats

PURPOSE

To evaluate the effects of exercise training on the changes induced by endotoxin in arterial pressure, heart rate (HR), blood cells, biochemical factors, plasma nitrite/nitrate, methyl guanidine (MG), proinflammatory cytokines, and pathology of the heart, liver, and lung.

METHODS

Twenty-four 10-wk-old male Wistar-Kyoto rats weighing 320-350 g were randomly assigned into two groups. The exercise-trained group (Tr; N = 12) received exercise training for 4 wk. The control (Con) group was placed on the treadmill and remained sedentary for the same time period. Endotoxemia was induced by intravenous (i.v.) infusion of lipopolysaccharide (LPS; 10 mg.kg(-1)) for 20 min, after which the animals were observed for 72 h. The femoral artery was cannulated to monitor arterial pressure and HR. Blood samples were collected 1 h before and at various times after LPS infusion. We determined plasma nitrite/nitrate, MG, white blood cells, neutrophils, lymphocytes, red blood cells, blood urea nitrogen, creatinine (Cr), aspartate aminotransferase, alanine aminotransferase, lactic acid dehydrogenase, creatine phosphokinase, amylase, lipase, tumor necrosis factor(alpha), and interleukin-1(beta). The heart, liver, and lung were taken for pathological examination and assessment after the experiment.

RESULTS

The Tr group had lower basal levels of arterial pressure, HR, MG, neutrophils, and Cr than the Con group. Exercise training attenuated the LPS-induced decreases in blood cells. After LPS administration, plasma levels of nitrate/nitrite, MG, biochemical factors, and proinflammatory cytokines in the Con group were higher than in the Tr group. Pathological examination and assessment revealed that cardiac, hepatic, and pulmonary injury were more severe in the Con group than in the Tr group.

CONCLUSIONS

Exercise training attenuates septic responses and protects organs from damage in sepsis.

Effects of preoperatively selected gut decontamination on cardiopulmonary bypass-induced endotoxemia

OBJECTIVE

To evaluate the influence of preoperatively selected gut decontamination (SGD) on intestinally derived endotoxemia(ETM) in patients with rheumatic heart disease undergoing valve replacement operation with cardiopulmonary bypass(CPB).

METHODS

Thirty patients were randomly divided into control group and SGD group. The patients in control group underwent preoperative bowel preparation, i.e, diet preparation and enema. The patients in SGD group were administrated 100 mg Tobramycin, 40 mg garlicin and 20% Lactulose for 10 ml three times per day for 3 days besides routinely preoperative bowel preparation. Bacteria cultivation and identification and Gram staining of feces in both groups were used to evaluate species of intestinal flora and their ratios. The levels of endotoxin, D-lactate, TNF-alpha and complement 3 were determined at four time points of anesthetic induction, CPB end, 2 h after CPB, 24 h after CPB. And the related clinical biochemical and clinical markers were recorded.

RESULTS

Aerobic gram-negative bacilli (AGNB) ratio in post-SGD group decreased significantly as compared with that in control group and pre-SGD group (P less than 0.05). The level of D-lactate reduced significantly at time points of anesthetic induction and 2 h after CPB (P less than 0.05). Endotoxin levels of patients in both groups elevated significantly after CPB (P less than 0.05), and endotoxin levels of the patients in SGD group decreased significantly at points of CPB end (P less than 0.01) and 24 h after CPB (P less than 0.05) compared with those in control group. The levels of TNF-alpha and complement 3 were similar in both groups as well as clinical and biochemical markers.

CONCLUSIONS

CPB induces endotoxemia, while the regime of SGD is an effective way to prevent endotoxemia but may not affect activation of inflammatory media and clinical outcomes.

Endogenous platelet factor 4 stimulates activated protein C generation in vivo and improves survival after thrombin or lipopolysaccharide challenge

Pharmacologic infusion of activated protein C (APC) improves survival in severe sepsis, and platelet factor 4 (PF4) accelerates APC generation in a primate thrombin-infusion model. We now tested whether endogenous platelet PF4 content affects APC generation. Mice completely deficient in PF4 (mPF4(-/-)) had impaired APC generation and survival after thrombin infusion, similar to the impairment seen in heterozygote protein C-deficient (PC(+/-)) mice. Transgenic mice overexpressing human PF4 (hPF4(+)) had increased plasma APC generation. Overexpression of platelet PF4 compensated for the defect seen in PC(+/-) mice. In both a thrombin and a lipopolysaccharide (LPS) survival model, hPF4(+) and PC(+/-)/hPF4(+) mice had improved survival. Further, infusion of hPF4(+) platelets improved survival of wild-type mice after an LPS challenge. These studies suggest that endogenous PF4 release may have biologic consequences for APC generation and survival in clinical sepsis. Infusions of PF4-rich platelets may be an effective strategy to improve outcome in this setting.

A cardiovascular drug rescues mice from lethal sepsis by selectively attenuating a late-acting proinflammatory mediator, high mobility group box 1

The pathogenesis of sepsis is mediated in part by bacterial endotoxin, which stimulates macrophages/monocytes to sequentially release early (e.g., TNF, IL-1, and IFN-gamma) and late (e.g., high mobility group box 1 (HMGB1) protein) proinflammatory cytokines. The recent discovery of HMGB1 as a late mediator of lethal sepsis has prompted investigation for development of new experimental therapeutics. We found that many steroidal drugs (such as dexamethasone and cortisone) and nonsteroidal anti-inflammatory drugs (such as aspirin, ibuprofen, and indomethacin) failed to influence endotoxin-induced HMGB1 release even at superpharmacological concentrations (up to 10-25 microM). However, several steroid-like pigments (tanshinone I, tanshinone IIA, and cryptotanshinone) of a popular Chinese herb, Danshen (Salvia miltiorrhiza), dose dependently attenuated endotoxin-induced HMGB1 release in macrophage/monocyte cultures. A water-soluble tanshinone IIA sodium sulfonate derivative (TSNIIA-SS), which has been widely used as a Chinese medicine for patients with cardiovascular disorders, selectively abrogated endotoxin-induced HMGB1 cytoplasmic translocation and release in a glucocorticoid receptor-independent manner. Administration of TSNIIA-SS significantly protected mice against lethal endotoxemia and rescued mice from lethal sepsis even when the first dose was given 24 h after the onset of sepsis. The therapeutic effects were partly attributable to attenuation of systemic accumulation of HMGB1 (but not TNF and NO) and improvement of cardiovascular physiologic parameters (e.g., decrease in total peripheral vascular resistance and increase in cardiac stroke volume) in septic animals. Taken together, these data re-enforce the pathogenic role of HMGB1 in lethal sepsis, and support a therapeutic potential for TSNIIA-SS in the treatment of human sepsis.

Oral and systemic administration of beta-glucan protects against lipopolysaccharide-induced shock and organ injury in rats

beta-Glucans are glucose polymers with a variety of stimulatory effects on the immune system. The objective of this study was to determine the effect of prophylactic oral administration of soluble Saccharomyces cerevisiae-derived beta-1,3/1,6-glucan (SBG) on the outcome of experimental endotoxaemia and shock-associated organ injury. Male Wistar rats were pretreated with SBG orally (SBGpo, 20 mg/kg/day) for 14 days, subcutaneously (SBGsc, 2 mg/kg/day) for 3 days, or vehicle (placebo). Rats were anaesthetized and subjected to endotoxaemia by intravenous infusion of Escherichia coli lipopolysaccharide (LPS) (6 mg/kg) or saline infusion (sham). We observed significant levels of plasma beta-glucan in the SBGpo group (P<0 x 5), although the SBGsc group had levels approximately 40-fold higher despite a 10-fold lower dose. SBG prophylaxis caused enhanced blood pressure recovery following LPS-induced blood pressure collapse. Oral treatment with SBG attenuated the LPS-induced rise in plasma creatinine levels (P<0 x 05), indicating protection against renal injury. SBG also attenuated the plasma levels of aspartate aminotransferase and alanine aminotransferase (SBGpo, P<0 x 01; SBGsc, P<0 x 01), indicating protection against LPS-induced hepatic injury. A moderate increase in baseline interleukin (IL)-1beta levels was observed in the SBGsc group (P< 0 x 05). In the LPS-challenged rats, plasma levels of proinflammatory cytokines was moderately reduced in both SBG-treated groups compared to placebo. SBG treatment, particularly oral administration, had a striking effect on the haemodynamics of LPS-treated rats, although only a minute fraction of the orally administered beta-glucan translocated to the circulation. Enhanced organ perfusion may thus be responsible for the attenuated levels of indicators of kidney and liver injury seen in SBG-treated rats.

The alpha2-adrenergic receptor antagonist yohimbine improves endotoxin-induced inhibition of gastrointestinal motility in mice

BACKGROUND

Sepsis inhibits gastrointestinal motility. Although the exact mechanism of this is unclear, lipopolysaccharide is known to activate macrophages in the gastrointestinal wall, which upregulate their expression of inducible nitric oxide synthase (iNOS). This leads to an increased production of nitric oxide, which relaxes the gastrointestinal muscles. We studied endotoxaemic mice to determine whether yohimbine improved delayed gastric emptying and gastrointestinal transit.

METHODS

Male Balb/c mice (n = 49) were randomly allocated to two groups, and either yohimbine 25 microg or saline was injected s.c. Four hours later, mice in each group were further randomly allocated to two groups, and either lipopolysaccharide 100 microg or saline was injected intraperitoneally. Eight hours later, liquid containing fluorescent microbeads was infused into the stomach, and 30 min later, gastric emptying and gastrointestinal transit were measured using flow cytometry. We also studied whether yohimbine given after injection of lipopolysaccharide was effective (n = 22). In another group of mice (n = 32), iNOS in the gastrointestinal tract was measured using western blotting.

RESULTS

Lipopolysaccharide significantly inhibited gastric emptying and gastrointestinal transit. Yohimbine, given before or after lipopolysaccharide, significantly attenuated the inhibitory effects of lipopolysaccharide. Lipopolysaccharide increased the expression of iNOS in the small intestine and yohimbine suppressed the effects of lipopolysaccharide.

CONCLUSIONS

In endotoxaemic mice, yohimbine improved delayed gastric emptying and gastrointestinal transit, possibly by downregulating lipopolysaccharide-induced increased expression of iNOS.

Lung protective ventilatory strategies in acute lung injury and acute respiratory distress syndrome: from experimental findings to clinical application

This review addresses the physiological background and the current status of evidence regarding ventilator-induced lung injury and lung protective strategies. Lung protective ventilatory strategies have been shown to reduce mortality from adult respiratory distress syndrome (ARDS). We review the latest knowledge on the progression of lung injury by mechanical ventilation and correlate the findings of experimental work with results from clinical studies. We describe the experimental and clinical evidence of the effect of lung protective ventilatory strategies and open lung strategies on the progression of lung injury and current controversies surrounding these subjects. We describe a rational strategy, the open lung strategy, to accomplish an open lung, which may further prevent injury caused by mechanical ventilation. Finally, the clinician is offered directions on lung protective ventilation in the early phase of ARDS which can be applied on the intensive care unit.