Absence of endogenous interleukin 10 enhances early stress response during post-ischaemic injury in mice intestine

Acrylamide Induced Toxicity and the Propensity of Phytochemicals in Amelioration: A Review

Acrylamide is widely found in baked and fried foods, produced in large amount in industries and is a prime component in toxicity. This review highlights various toxicities that are induced due to acrylamide, its proposed mode of action including oxidative stress cascades and ameliorative mechanisms using phytochemicals. Acrylamide formation, the mechanism of toxicity and the studies on the role of oxidative stress and mitochondrial dysfunctions are elaborated in this paper. The various types of toxicities caused by Acrylamide and the modulation studies using phytochemicals that are carried out on various type of toxicity like neurotoxicity, hepatotoxicity, cardiotoxicity, immune system, and skeletal system, as well as embryos have been explored. Lacunae of studies include the need to explore methods for reducing the formation of acrylamide in food while cooking and also better modulators for alleviating the toxicity and associated dysfunctions along with identifying its molecular mechanisms.

Curcumin and Intestinal Inflammatory Diseases: Molecular Mechanisms of Protection

Intestinal inflammatory diseases, such as Crohn’s disease, ulcerative colitis, and necrotizing enterocolitis, are becoming increasingly prevalent. While knowledge of the pathogenesis of these related diseases is currently incomplete, each of these conditions is thought to involve a dysfunctional, or overstated, host immunological response to both bacteria and dietary antigens, resulting in unchecked intestinal inflammation and, often, alterations in the intestinal microbiome. This inflammation can result in an impaired intestinal barrier allowing for bacterial translocation, potentially resulting in systemic inflammation and, in severe cases, sepsis. Chronic inflammation of this nature, in the case of inflammatory bowel disease, can even spur cancer growth in the longer-term. Recent research has indicated certain natural products with anti-inflammatory properties, such as curcumin, can help tame the inflammation involved in intestinal inflammatory diseases, thus improving intestinal barrier function, and potentially, clinical outcomes. In this review, we explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its antimicrobial and immunomodulatory properties, as well as its potential to alter the intestinal microbiome. Curcumin may play a significant role in intestinal inflammatory disease treatment in the future, particularly as an adjuvant therapy.

Gastrodin Attenuates Pentylenetetrazole-Induced Seizures by Modulating the Mitogen-Activated Protein Kinase-Associated Inflammatory Responses in Mice

Gastrodin, the major component isolated from the rhizome of the Chinese traditional medicinal herb Gastrodia elata ("Tianma"), has a long history in the treatment of epilepsy and other neurological disorders. However, the molecular mechanisms are not clear. Here, we found that gastrodin ameliorated pentylenetetrazole (PTZ)-induced epileptic seizures with improvement of the electroencephalographic pattern in mice. Further studies demonstrated that gastrodin decreased the levels of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α while increasing interleukin-10, an anti-inflammatory cytokine in the brain. Furthermore, gastrodin attenuated the PTZ-induced microglial activation along with inhibition of mitogen-activated protein kinases, cAMP response element binding protein, and NF-κB. Our data suggest that gastrodin attenuates seizures by modulating the mitogen-activated protein kinase-associated inflammatory responses.

Mesenchymal stem cells improve mouse non-heart-beating liver graft survival by inhibiting Kupffer cell apoptosis via TLR4-ERK1/2-Fas/FasL-caspase3 pathway regulation

Background

Liver transplantation is the optimal treatment option for end-stage liver disease, but organ shortages dramatically restrict its application. Donation after cardiac death (DCD) is an alternative approach that may expand the donor pool, but it faces challenges such as graft dysfunction, early graft loss, and cholangiopathy. Moreover, DCD liver grafts are no longer eligible for transplantation after their warm ischaemic time exceeds 30 min. Mesenchymal stem cells (MSCs) have been proposed as a promising therapy for treatment of certain liver diseases, but the role of MSCs in DCD liver graft function remains elusive.

Methods

In this study, we established an arterialized mouse non-heart-beating (NHB) liver transplantation model, and compared survival rates, cytokine and chemokine expression, histology, and the results of in vitro co-culture experiments in animals with or without MSC infusion.

Results

MSCs markedly ameliorated NHB liver graft injury and improved survival post-transplantation. Additionally, MSCs suppressed Kupffer cell apoptosis, Th1/Th17 immune responses, chemokine expression, and inflammatory cell infiltration. In vitro, PGE2 secreted by MSCs inhibited Kupffer cell apoptosis via TLR4-ERK1/2-caspase3 pathway regulation.

Conclusion

Our study uncovers a protective role for MSCs and elucidates the underlying immunomodulatory mechanism in an NHB liver transplantation model. Our results suggest that MSCs are uniquely positioned for use in future clinical studies owing to their ability to protect DCD liver grafts, particularly in patients for whom DCD organs are not an option according to current criteria.

Mesenchymal stem cells improve mouse non-heart-beating liver graft survival by inhibiting Kupffer cell apoptosis via TLR4-ERK1/2-Fas/FasL-caspase3 pathway regulation

BACKGROUND

Liver transplantation is the optimal treatment option for end-stage liver disease, but organ shortages dramatically restrict its application. Donation after cardiac death (DCD) is an alternative approach that may expand the donor pool, but it faces challenges such as graft dysfunction, early graft loss, and cholangiopathy. Moreover, DCD liver grafts are no longer eligible for transplantation after their warm ischaemic time exceeds 30 min. Mesenchymal stem cells (MSCs) have been proposed as a promising therapy for treatment of certain liver diseases, but the role of MSCs in DCD liver graft function remains elusive.

METHODS

In this study, we established an arterialized mouse non-heart-beating (NHB) liver transplantation model, and compared survival rates, cytokine and chemokine expression, histology, and the results of in vitro co-culture experiments in animals with or without MSC infusion.

RESULTS

MSCs markedly ameliorated NHB liver graft injury and improved survival post-transplantation. Additionally, MSCs suppressed Kupffer cell apoptosis, Th1/Th17 immune responses, chemokine expression, and inflammatory cell infiltration. In vitro, PGE2 secreted by MSCs inhibited Kupffer cell apoptosis via TLR4-ERK1/2-caspase3 pathway regulation.

CONCLUSION

Our study uncovers a protective role for MSCs and elucidates the underlying immunomodulatory mechanism in an NHB liver transplantation model. Our results suggest that MSCs are uniquely positioned for use in future clinical studies owing to their ability to protect DCD liver grafts, particularly in patients for whom DCD organs are not an option according to current criteria.

Protective effects of isohelenin, an inhibitor of nuclear factor κB, in endotoxic shock in rats

Recent in vitro studies have shown that isohelenin, a sesquiterpene lactone, inhibits the NF-κB pathway. This study examines the effect of isoheleninin endotoxic shock induced by administration of Escherichia coli endotoxini n male Wistar rats. A group of rats received isohelenin (2 mg/kg intraperitoneally)15 min before endotoxin. In vehicle-treated rats, administration of endotoxin caused severe hypotension, which was associated with a marked hyporeactivity to norepinephrine and acetylcholine in ex vivo aortas. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were preceded by cytosolic degradation of inhibitor-κBα (IκBα) and activation of nuclear factor-κB (NF-κB) in the lung within 15 min of endotoxin administration. Treatment with isohelenin resulted in hemodynamicimprovement and reduced plasma levels of NO metabolites. Nuclear translocation of NF-κB was inhibited by isohelenin treatment in the lung, whereas degradation of IκBα was unchanged. In a separate set of experiments, treatment with isohelenin significantly improved survival in mice challenged with endotoxin. We conclude that isohelenin exerts beneficial therapeutic effects during endotoxic shock through inhibition of NF-κB.

The Effect of High-Dose Vitamin D3 on Soluble P-Selectin and hs-CRP Level in Patients With Venous Thromboembolism

High plasma level of P-selectin is associated with the development of venous thromboembolism (VTE). Furthermore, supplementation of vitamin D could decrease thrombotic events. Hence, this study was designed to examine whether the administration of vitamin D can influence the plasma level of P-selectin in patients with VTE. In the randomized controlled trial, 60 patients with confirmed acute deep vein thrombosis and/or pulmonary embolism (PE) were randomized into the intervention (n = 20) and control (n = 40) groups. The intervention arm was given an intramuscular single dose of 300 000 IU vitamin D3. Plasma level of 25-hydroxy vitamin D, P-selectin, and high-sensitive C-reactive protein (hs-CRP) was measured at baseline and 4 weeks after. The plasma level of P-selectin (95% confidence interval = −5.99 to −1.63, P = .022) and hs-CRP ( P = .024) significantly declined in vitamin D-treated group, while only hs-CRP was significantly decreased in the control group ( P = .011). However, the magnitude of these reductions was not statistically significant. This study could not support the potential benefit of the high-dose vitamin D on plasma level of P-selectin and hs-CRP in patients with VTE.

Transient TLR activation restores inflammatory response and ability to control pulmonary bacterial infection in germfree mice

Mammals are colonized by an astronomical number of commensal microorganisms on their environmental exposed surfaces. These symbiotic species build up a complex community that aids their hosts in several physiological activities. We have shown that lack of intestinal microbiota is accompanied by a state of active IL-10-mediated inflammatory hyporesponsiveness. The present study investigated whether the germfree state and its hyporesponsive phenotype alter host resistance to an infectious bacterial insult. Experiments performed in germfree mice infected with Klebsiella pneumoniae showed that these animals are drastically susceptible to bacterial infection in an IL-10-dependent manner. In germfree mice, IL-10 restrains proinflammatory mediator production and neutrophil recruitment and favors pathogen growth and dissemination. Germfree mice were resistant to LPS treatment. However, priming of these animals with several TLR agonists recovered their inflammatory responsiveness to sterile injury. LPS pretreatment also rendered germfree mice resistant to pulmonary K. pneumoniae infection, abrogated IL-10 production, and restored TNF-α and CXCL1 production and neutrophil mobilization into lungs of infected germfree mice. This effective inflammatory response mounted by LPS-treated germfree mice resulted in bacterial clearance and enhanced survival upon infection. Therefore, host colonization by indigenous microbiota alters the way the host reacts to environmental infectious stimuli, probably through activation of TLR-dependent pathways. Symbiotic gut colonization enables proper inflammatory response to harmful insults to the host, and increases resilience of the entire mammal-microbiota consortium to environmental pressures.

Effects of Pantoprazole on Systemic and Gastric Pro- and Anti-inflammatory Cytokines in Critically Ill Patients

Stress-related mucosal damage (SRMD) is a significant cause of morbidity and mortality in critically ill patients due to the gastrointestinal blood loss. Prophylaxis of SRMD with proton pump inhibitors or histamine-2 blockers has gained widespread use in intensive care units. Both demonstrated to be effective in reducing clinically significant bleedings, while PPIs has shown to exert some anti inflammatory effects including the inhibition of producing pro-inflammatory cytokines. As cytokines have role in developing SRMD, the aim of this study was to evaluate the effect of PPIs on the inhibition of cytokine release following the critical illness. A total of 27 critically ill patients with risk factors of developing stress ulcer and intragastric pH < 3.0 enrolled to this Randomized clinical trial study. Patients were randomly assigned in three treatment groups; group one received 40 mg of intravenous pantoprazole every 12 h for 48 h (four doses), group two received 80 mg of intravenous pantoprazole every 24 h continuous infusion for 48 h and the third group received 150 mg of ranitidine intravenously as 24 h continuous infusion for 48 h. Plasma and gastric juice samples were obtained at 0th, 12th, 24th and 48th h for the measurement of EGF, IL-1β, IL-6, IL-10 and TNF-α. Pantoprazole infusion have decreased the plasma IL-1β concentrations (p = 0.041). No other significant differences in concentrations of EGF, IL-6, IL-10 and TNF-α were detected. There were reverse correlations between the intragastric pH with gastric juice IL-1β and TNF-α concentrations and a direct correlation between the intragastric pH and gastric juice EGF in pantoprazole groups. Our data suggest that pantoprazole may have some anti-inflammatory effects on patients. However, the exact impact of this effect on patients should be assessed by further studies.

Interleukin-13 protects mouse intestine from ischemia and reperfusion injury through regulation of innate and adaptive immunity

BACKGROUND

Ischemia-reperfusion (I/R) injury is a major factor leading to intestinal dysfunction or graft loss after intestinal surgery or transplantation. This study investigated the cytoprotective effects and putative mechanisms of interleukin (IL)-13 after intestinal I/R injury in the mouse.

METHODS

Mouse warm intestinal I/R injury induced by clamping the superior mesenteric artery for 100 min with tissue analysis at 4 and 24 hr after reperfusion. Treated animals received intravenous recombinant murine IL-13 (rIL-13) and anti-IL-13 antibody, whereas controls received saline.

RESULTS

rIL-13 administration markedly prolonged animal survival (100% vs. 50% in saline controls) and resulted in near normal histopathological architecture. rIL-13 treatment also significantly decreased myeloperoxidase activity. Mice conditioned with rIL-13 had a markedly depressed Toll-like receptor-4 expression and increased the expression of Stat6, antioxidant hemeoxygenase-1, and antiapoptotic A20, Bcl-2/Bcl-xl, compared with that of controls. Unlike in controls, the expression of mRNA coding for IL-2/interferon-γ, and interferon-γ-inducible protein (IP)-10/monocyte chemotactic protein-1 remained depressed, whereas that of IL-13/IL-4 reciprocally increased in the mice treated with rIL-13. Administration of anti-IL13 antibody alone or in combination with rIL-13 resulted in outcomes similar to that seen in controls.

CONCLUSIONS

This study demonstrates for the first time that IL-13 plays a protective role in intestinal warm I/R injury and a critical role in the regulation of Stat6 and Toll-like receptor-4 signaling. The administration of IL-13 exerts cytoprotective effects in this model by regulating innate and adaptive immunity while the removal of IL-13 using antibody therapy abrogates this effect.

Early enteral 5% glucose infusion maintains the epidermal growth factor levels in the jejunal flap used for pharyngo-oesophageal reconstruction

BACKGROUND

Free jejunal flap reconstruction is the main treatment for patients after pharyngo-oesophagectomy. Flaps are unavoidably subjected to ischaemia and reperfusion (I/R) during preparation. Enteral nutrition has been shown to improve the recovery of injured intestine, although the precise underlying mechanism remains unclear. This study was aimed to determine whether early enteral 5% glucose infusion is beneficial for the recovery of flap. Further, the possibility that enteral glucose infusion induces altered mucosal responses was evaluated.

PATIENTS AND METHODS

Patients, who underwent free jejunal flap reconstructions after pharyngo-oesophagectomy, were enrolled. An externalised monitor loop was made to observe the viability of flap and to collect intestinal fluid. Control patients (n = 11) received peripheral parenteral nutrition for seven post-operation days. For early enteral-fed patients (n = 12), in addition to fluid infusion, administration of 5% glucose (25 ml h(-1)) via a jejunostomy tube was initiated 6h after surgery. Blood, flap fluid and mucosal specimens were harvested. Plasma and flap luminal levels of interleukin (IL)-6, IL-10, epidermal growth factor (EGF) and secretory immunoglobulin A (sIgA) were measured. Further, mucosal morphology was examined.

RESULTS

There were no significant differences in either plasma or luminal concentrations of IL-6, IL-10 and sIgA at different time points between groups. The luminal EGF level in the control group reduced markedly from the 3rd postoperative day, contrasting with a well-maintained level in the early enteral-fed group. No significant difference in mucosal histology between groups was observed.

CONCLUSION

Early enteral glucose infusion does not significantly benefit the ischaemia-reperfusion-injured flap; however, it does preserve EGF levels in the flap lumen.

Curcumin protects intestinal mucosal barrier function of rat enteritis via activation of MKP-1 and attenuation of p38 and NF-κB activation

Background

Intestinal mucosa barrier (IMB) dysfunction results in many notorious diseases for which there are currently few effective treatments. We studied curcumin's protective effect on IMB and examined its mechanism by using methotrexate (MTX) induced rat enteritis model and lipopolysaccharide (LPS) treated cell death model.

Methodology/Principal Findings

Curcumin was intragastrically administrated from the first day, models were made for 7 days. Cells were treated with curcumin for 30 min before exposure to LPS. Rat intestinal mucosa was collected for evaluation of pathological changes. We detected the activities of D-lactate and diamine oxidase (DAO) according to previous research and measured the levels of myeloperoxidase (MPO) and superoxide dismutase (SOD) by colorimetric method. Intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were determined by RT-PCR and IL-10 production was determined by ELISA. We found Curcumin decreased the levels of D-lactate, DAO, MPO, ICAM-1, IL-1β and TNF-α, but increased the levels of IL-10 and SOD in rat models. We further confirmed mitogen-activated protein kinase phosphatase-1 (MKP-1) was activated but phospho-p38 was inhibited by curcumin by western blot assay. Finally, NF-κB translocation was monitored by immunofluorescent staining. We showed that curcumin repressed I-κB and interfered with the translocation of NF-κB into nucleus.

Conclusions/Significance

The effect of curcumin is mediated by the MKP-1-dependent inactivation of p38 and inhibition of NF-κB-mediated transcription. Curcumin, with anti-inflammatory and anti-oxidant activities may be used as an effective reagent for protecting intestinal mucosa barrier and other related intestinal diseases.

Mechanisms of acetaminophen-induced liver necrosis

Although considered safe at therapeutic doses, at higher doses, acetaminophen produces a centrilobular hepatic necrosis that can be fatal. Acetaminophen poisoning accounts for approximately one-half of all cases of acute liver failure in the United States and Great Britain today. The mechanism occurs by a complex sequence of events. These events include: (1) CYP metabolism to a reactive metabolite which depletes glutathione and covalently binds to proteins; (2) loss of glutathione with an increased formation of reactive oxygen and nitrogen species in hepatocytes undergoing necrotic changes; (3) increased oxidative stress, associated with alterations in calcium homeostasis and initiation of signal transduction responses, causing mitochondrial permeability transition; (4) mitochondrial permeability transition occurring with additional oxidative stress, loss of mitochondrial membrane potential, and loss of the ability of the mitochondria to synthesize ATP; and (5) loss of ATP which leads to necrosis. Associated with these essential events there appear to be a number of inflammatory mediators such as certain cytokines and chemokines that can modify the toxicity. Some have been shown to alter oxidative stress, but the relationship of these modulators to other critical mechanistic events has not been well delineated. In addition, existing data support the involvement of cytokines, chemokines, and growth factors in the initiation of regenerative processes leading to the reestablishment of hepatic structure and function.

Bacterial translocation in an experimental intestinal obstruction model. C-reactive protein reliability?

BACKGROUND

Bacterial translocation occurs in preseptic conditions such as intestinal obstruction through unclear mechanism. The C-reactive protein is an acute phase reactant and a marker of ischemia.

METHODS

45 albino male rats were divided into 3 groups each 15 rats. GI control, GII simple intestinal-obstruction and GIII strangulated obstruction. Outcome measures were: (1) Bacteriologic count and typing for intestinal contents, intestinal wall, liver, mesenteric lymph nodes and blood (cardiac and portal) (2) Histopathologic: mucosal injury score, inflammatory cell infiltrate in the wall, MLN, liver, (3) Biochemical: serum CRP, IL-10, mucosal stress pattern (glutathione peroxidase-malonyldialdhyde tissue levels).

RESULTS

(1) Intestinal obstruction associates with BT precursors (Bact-overgrowth, mucosal-acidosis, immuno-incomptence), (2) Bacterial translocation (frequency and density) was found higher in strangulated I.O, that was mainly enteric (aerobic and anaerobic) and mostly E.coli, (3) The pathogen commonality supports the gut origin hypothesis but the systemic inflammatory response goes with the cytokine generating one. (4) The CRP median values for GI, II, III were 0.5, 6.9, 8.5 mg/L, for BT +ve 8 mg/L and 0.75 mg/L for BT -ve rats.

CONCLUSION

Bacterial translocation occurs bi-directional (systemic-portal) in intestinal obstruction and the resultant inflammatory response pathogenesis is mostly 3 hit model. The CRP is a non selective marker of suspected I.O cases. However, it is a reliable marker of BT, BT density and vascular compromise during I.O.

Thermotolerance-induced goblet cell activity confers protection in post-operative gut barrier dysfunction

INTRODUCTION

There is evidence that some level of protection against the adverse sequelae of surgery is provided by induction of thermotolerance; this protective effect was explored by study of several indicators of bowel wall damage in animals exposed to surgical insults. It has been argued that the mechanism of the protective effect of thermotolerance involves heat shock proteins (HSPs). We hypothesized that the protective effect of thermotolerance may be due in part to changes in the bowel wall itself, and we investigated this hypothesis in an experimental rat model.

METHODS

Adult Sprague-Dawley rats were randomized into thermotolerant (n=16) and control (n=16) groups; half of the animals in each group were subjected to bowel-handling and half to ischaemia-reperfusion insults. The responses of the thermotolerant animals and controls were compared with respect to goblet cell type and number and histopathological changes of the bowel wall.

RESULTS

The thermotolerant animals were found to have significantly less oedema and histological damage. There was significant increase in the number of goblet cells in response to surgical insults (19.16+/-5.66 vs. 4.855+/-3.15), and specifically a greater increase in acidic goblet cells (19.42+/-4.58) as compared with neutral ones (13.28+/-5.53) (p<0.0001).

CONCLUSION

This suggests that the thermotolerant animals were not only able to recruit or produce more goblet cells to protect the gut surface, but that greater numbers of the goblet cells in the thermotolerant animals were of the mature acidic type and thus capable of functioning in a protective capacity. These findings provide evidence for thermotolerance-induced histological changes in the bowel wall providing a protective effect against adverse sequelae of surgery.

Direct hemoperfusion with a polymyxin B-immobilized cartridge in intestinal warm ischemia reperfusion

AIM: To investigate the effectiveness of direct hemoperfusion with polymyxin B-immobilized fibers (DHP-PMX therapy) on warm ischemia-reperfusion (I/R) injury of the small intestine.

METHODS: The proximal jejunum and distal ileum of mongrel dogs were resected. Warm ischemia was performed by clamping the superior mesenteric artery (SMA) and vein (SMV) for 2 h. Blood flow to the proximal small intestine was restored 1 h after reperfusion, and the distal small intestine was used as a stoma. The experiment was discontinued 6 h after reperfusion. The dogs were divided into two groups: the DHP-PMX group (n = 6, DHP-PMX was performed for 180 min; from 10 min prior to reperfusion to 170 min after reperfusion) and the control group (n = 5). The rate pressure product (RPP), SMA blood flow, mucosal tissue blood flow, and intramucosal pH (pHi) were compared between the two groups. The serum interleukin (IL)-10 levels measured 170 min after reperfusion were also compared.

RESULTS: The RPP at 6 h after reperfusion was significantly higher in the PMX group than in the control group (12 174 ± 1832 mmHg/min vs 8929 ± 1797 mmHg/min, P < 0.05). The recovery rates of the SMA blood flow at 1 and 6 h after reperfusion were significantly better in the PMX group than in the control group (61% ± 7% vs 44% ± 4%, P < 0.05, and 59% ± 5% vs 35% ± 5%, P < 0.05, respectively). The recovery rate of the mucosal tissue blood flow and the pHi levels at 6 h after reperfusion were significantly higher in the PMX group (61% ± 8% vs 31% ± 3%, P < 0.05 and 7.91 ± 0.06 vs 7.69 ± 0.08, P < 0.05, respectively). In addition, the serum IL-10 levels just before DHP-PMX removal were significantly higher in the PMX group than in the control group (1 569 ± 253 pg/mL vs 211 ± 40 pg/mL, P < 0.05).

CONCLUSION: DHP-PMX therapy reduced warm I/R injury of the small intestine. IL-10 may play a role in inhibiting I/R injury during DHP-PMX therapy.

The required role of endogenously produced lipoxin A4 and annexin-1 for the production of IL-10 and inflammatory hyporesponsiveness in mice

The appropriate development of an inflammatory response is central for the ability of a host to deal with any infectious insult. However, excessive, misplaced, or uncontrolled inflammation may lead to acute or chronic diseases. The microbiota plays an important role in the control of inflammatory responsiveness. In this study, we investigated the role of lipoxin A4 and annexin-1 for the IL-10-dependent inflammatory hyporesponsiveness observed in germfree mice. Administration of a 15-epi-lipoxin A4 analog or an annexin-1-derived peptide to conventional mice prevented tissue injury, TNF-alpha production, and lethality after intestinal ischemia/reperfusion. This was associated with enhanced IL-10 production. Lipoxin A4 and annexin-1 failed to prevent reperfusion injury in IL-10-deficient mice. In germfree mice, there was enhanced expression of both lipoxin A4 and annexin-1. Blockade of lipoxin A4 synthesis with a 5-lipoxygenase inhibitor or Abs against annexin-1 partially prevented IL-10 production and this was accompanied by partial reversion of inflammatory hyporesponsiveness in germfree mice. Administration of BOC-1, an antagonist of ALX receptors (at which both lipoxin A4 and annexin-1 act), or simultaneous administration of 5-lipoxygenase inhibitor and anti-annexin-1 Abs, was associated with tissue injury, TNF-alpha production, and lethality similar to that found in conventional mice. Thus, our data demonstrate that inflammatory responsiveness is tightly controlled by the presence of the microbiota and that the innate capacity of germfree mice to produce IL-10 is secondary to their endogenous greater ability to produce lipoxin A4 and annexin-1.

Influence of temporary abdominal wall repair on the intestinal integrity: an experimental study in the rat

BACKGROUND AND AIMS

The aim of this study was to analyze intestinal integrity after temporary abdominal wall repair with absorbable mesh.

METHODS

Rats underwent abdominal wall repair with absorbable mesh or sham operation. Myeloperoxidase-positive cells in the intestinal muscularis were histochemically quantified. Intestinal transit was visualized 48 h after surgery. Local and systemic inflammatory response was measured with TNF-alpha and IL-6 ELISA as well as malondialdehyde (MDA) expression in serum and peritoneal fluid.

RESULTS

Neutrophil count of the intestinal muscularis revealed that infiltration in the mesh-implanted and in the mesh-free animals 48 h postoperatively was similar. Gastrointestinal transit was similarly unaffected 48 h after surgery, with or without mesh implantation. TNF-alpha, IL-6 and MDA concentration in serum and peritoneal fluid showed no significant differences between the two groups.

CONCLUSION

Intestinal contractility and local and systemic inflammatory response remained unaffected. Therefore, absorbable mesh augmentation is a safe and reliable method for temporary repair of the abdominal wall without affecting the intestinal integrity.

Effects of PKF242-484 and PKF241-466, novel dual inhibitors of TNF-alpha converting enzyme and matrix metalloproteinases, in a model of intestinal reperfusion injury in mice

Tumor necrosis factor (TNF)-alpha plays an important role in the mediation of reperfusion-induced tissue injury and lethality. Here, we assessed the effects of PKF242-484 and PKF241-466, two dual inhibitors of TNF-alpha converting enzyme (TACE) and matrix metalloproteinases (MMPs), in a model of ischemia and reperfusion injury in mice. Reperfused animals that received PKF242-484 or PKF241-466 treatment had a dose-dependent reduction of TNF-alpha concentrations in serum. Both drugs delayed and partially inhibited the reperfusion-associated lethality. Maximal inhibition occurred at 10 mg/kg. At this dose, both inhibitors reduced reperfusion-associated local and remote tissue injury, as assessed by changes in vascular permeability, neutrophil recruitment and hemorrhage. In addition, the compounds markedly reduced production of TNF-alpha, CXCL1 (keratinocyte-derived chemokine, KC) and CCL2 (monocyte chemoattractant protein-1, MCP-1) in intestine and lungs of animals which underwent reperfusion. FN-439, an inhibitor of MMPs which possesses no effect on TACE, decreased MMP-2 and MMP-3 activity, but failed to affect tissue injury, TNF-alpha production or lethality. Thus, combined TACE and MMP inhibitors might be effective co-adjuvants in treatments of injuries that follow reperfusion of an ischemic vascular territory. The effects of these drugs on TNF-alpha production appear to be more relevant than their effects on MMP inhibition.

ST2, an IL-1R family member, attenuates inflammation and lethality after intestinal ischemia and reperfusion

Ischemia reperfusion injury is characterized by local and systemic inflammation leading to considerable mortality. Previously, we have reported that soluble T1/ST2 (sST2), a member of the IL-1 receptor gene family, inhibits LPS-induced macrophage proinflammatory cytokine production. Here, we report the therapeutic effect of sST2-Fc in a murine model of intestinal ischemia reperfusion-induced injury. Administration of sST2-Fc fusion protein i.v., 10 min before reperfusion, reduced the production of TNF-alpha dose-dependently in the intestine and in the lungs. The sST2-Fc treatment with the highest dose (100 mug) resulted in inhibited vascular permeability, neutrophilia, and hemorrhage in the intestine and the lungs compared with controls treated with normal IgG. This was associated with down-regulated tissue levels of proinflammatory cytokines, markedly reduced serum TNF-alpha levels, and increased survival of mice from the sST2-Fc-treated group after ischemia and reperfusion injury. The beneficial effect of sST2-Fc treatment was associated with elevated IL-10 production in intestine and lung. sST2-Fc was not able to prevent the inflammatory response associated with intestinal ischemia and reperfusion in IL-10-deficient mice, suggesting that sST2 exerts its anti-inflammatory effect in a IL-10-dependent manner. These results also demonstrate that sST2-Fc may provide a novel, complementary approach in treating ischemic reperfusion injury.

Tyrphostin AG 126 reduces intestinal ischemia-reperfusion injury in the rat

In this study, we evaluated the effect of tyrphostin AG126, a tyrosine kinase inhibitor, in the splanchnic artery occlusion (SAO) shock mediated injury. SAO shock was induced in rats by clamping both the superior mesenteric artery and the celiac trunk for 45 min. After 1 h of reperfusion, SAO shocked rats developed a significant fall in mean arterial blood pressure. Ileum analysis revealed that SAO shock is characterized by a significant (P<0.01) induction in TNF-alpha and IL-1 ileum levels, while immunohistochemistry examination of necrotic ileum demonstrated a marked increase in the immunoreactivity in intracellular adhesion molecule (ICAM-1) and nitrotyrosine formation. A significant increase in myeloperoxidase activity (P<0.01) was also observed in rats subjected to ischemia-reperfusion injury. Tyrphostin AG126, given intraperitoneally 30 min before ischemia at the dose of 5 mg/kg, significantly improved mean arterial blood pressure, markedly reduced TNF-alpha and IL-1beta levels and the positive staining of ICAM-1 into the reperfused ileum. Tyrphostin AG126 significantly improved the histological status of the reperfused tissue. In conclusion, this study demonstrates that tyrphostin AG126 exerts multiple protective effects in splanchnic artery occlusion/reperfusion shock and suggests that this tyrosine kinase inhibitor may be a candidate for consideration as a therapeutic intervention for ischemia-reperfusion injury.

ROLE OF ENDOGENOUS PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR-α (PPAR-α) LIGANDS IN THE DEVELOPMENT OF GUT ISCHEMIA AND REPERFUSION IN MICE

The peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The aim of the present study was to examine the effects of endogenous PPAR-alpha ligand on the development of gut ischemia and reperfusion injury. Splanchnic artery occlusion (SAO) shock was induced in mice by clamping both the superior mesenteric artery and the celiac artery for 30 min, followed thereafter by release of the clamp (reperfusion). At 60 min after reperfusion, animals were sacrificed for histological examination and biochemical studies. SAO-shocked WT mice developed a significant increase of ileum tissue, TNF-alpha, IL-1beta, myeloperoxidase activity, and marked histological injury. SAO shock was also associated with a significant mortality (0% survival at 24 h after reperfusion). Reperfused ileum tissue sections from SAO-shocked WT mice showed positive staining for P-selectin, ICAM-1, TNF-alpha, and IL-1beta. Absence of a functional PPAR-alpha gene in PPAR-alphaKO mice resulted in a significant augmentation of all the above-described parameters. Thus, endogenous PPAR-alpha ligands reduce the degree of ileum injury caused by ischemia and reperfusion.

Disruption of P-selectin signaling modulates cell trafficking and results in improved outcomes after mouse warm intestinal ischemia and reperfusion injury

BACKGROUND

This study analyzes the role of T lymphocytes and neutrophils (PMN) in intestinal ischemia and reperfusion injury (IRI) using either P-selectin blockade or elimination.

METHODS

Using a model of severe mouse warm intestinal IRI, the following groups were performed: group 1: wild type C57BL6 no treatment; group 2: wild type treated with r-PSGL1-Ig; group 3: C57BL6 genetically deficient in P-selectin. Survival was assessed at day 7; intestine was assayed for histopathology, apoptosis, myeloperoxidase (MPO), inflammatory cytokines, hemoxygenase-1 (HO-1), and CD3 lymphocytes. Standard statistical comparison was undertaken.

RESULTS

The survival was significantly (P < 0.01) improved in the treatment groups: group 1, 50%; group 2, 90%; group 3, 100%. Graded histopathology and crypt apoptosis were improved in groups 2 and 3. MPO and CD3 positive cells were significantly reduced in groups 2 and 3. A significant reduction in inflammatory/Th1-type cytokines was seen in groups 2 and 3 as compared to group 1. Conversely, a significant increase in Th2-type cytokines and HO-1 production was seen selectively in groups 2 and 3.

CONCLUSIONS

This study demonstrates the importance of P-selectin signaling in warm, murine intestinal IRI in that either the blockade of or the genetic deficiency in P-selectin confers a survival advantage and reduction in tissue injury/inflammation. The mechanism involves a reduction of PMN and CD3 T cell infiltration and an alteration in the cytokine microenvironment in favor of a Th2 profile. These data implicate T lymphocyte as an important regulatory cell in this inflammatory process.

Anemia after Late Introduction of Sirolimus May Correlate with Biochemical Evidence of a Chronic Inflammatory State

BACKGROUND

The responsibility of sirolimus (SRL) for postrenal transplant anemia has never been proven, because SRL is usually combined with myelotoxic drugs, and because of the high incidence of anemia in the posttransplant period.

METHODS

We retrospectively analyzed anemia in 46 renal transplant recipients, who had been switched from calcineurin inhibitors to SRL for biopsy-proven chronic allograft nephropathy.

RESULTS

The mean decrease in hemoglobin (Hb) after SRL introduction was 2.8 g/dl. The 24 patients, whose Hb fell by >or=2 g/dl, displayed microcytic aregenerative anemia with low serum iron despite high ferritinemia, consistent with anemia of chronic inflammatory states. Fibrinogen and CRP levels increased in these patients after sirolimus introduction. We subsequently focused our study on eight patients without confounding factors of anemia. Anemia improved in all eight after SRL withdrawal. IL6 and TNFalpha at the nadir of anemia were significantly higher than before SRL introduction and after its withdrawal. Decreases in Hb correlated with increases in proinflammatory cytokine levels in a linear regression model. Unchanged serum IL10 levels measured at the nadir of anemia were discordant with the inflammatory state.

CONCLUSIONS

Late introduction of SRL may induce anemia and correlates with biochemical evidence of a chronic inflammatory state possibly due to defective IL10-dependent inflammatory autoregulation.

EFFECTS OF HYPERICUM PERFORATUM EXTRACT IN A RAT MODEL OF ISCHEMIA AND REPERFUSION INJURY

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants, and/or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects ischemia and reperfusion. Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Because polyphenolic compounds have high antioxidant potential, in this study we evaluated the effect of H. perforatum extract on splanchnic artery occlusion (SAO) shock-mediated injury. SAO shock was induced in rats by clamping the superior mesenteric artery and the celiac trunk for 45 min. After 1 h of reperfusion, SAO-shocked rats developed a significant fall in mean arterial blood pressure. Treatment of rats with H. perforatum extract (applied at 25 mg/kg 15 min before reperfusion) significantly reduced a significant fall in mean arterial blood pressure and the migration of polymorphonuclear cells caused by SAO-shock. H. perforatum extract also attenuated the ileum injury (histology) as well as the increase in the tissue levels of myeloperoxidase and malondialdehyde caused by SAO shock in the ileum. Immunohistochemical analysis for nitrotyrosine and for poly ADP-ribosylated proteins revealed a positive staining in ileum from SAO-shocked rats. The degree of staining for nitrotyrosine and poly ADP-ribosylated proteins was markedly reduced in tissue sections obtained from SAO-shocked rats that had received H. perforatum extract. Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin and for intercellular adhesion molecule-1 in the vascular endothelial cells. H. perforatum extract treatment markedly reduced the intensity and degree of P-selectin and intercellular adhesion molecule-1 in tissue section from SAO-shocked rats. H. perforatum extract treatment significantly improved survival. In conclusion, this study demonstrates that H. perforatum extract exerts multiple protective effects in splanchnic artery occlusion-reperfusion shock and suggests that H. perforatum extract may be a candidate for consideration as a therapeutic intervention for ischemia-reperfusion injury.

Activator protein-1 signalling pathway and apoptosis are modulated by poly(ADP-ribose) polymerase-1 in experimental colitis

Poly(ADP-ribose) polymerase-1 (PARP-1) is activated in response to DNA injury in the nucleus of eukaryotic cells and has been implicated in intestinal barrier dysfunction during inflammatory bowel diseases. In this study we investigated whether PARP-1 may regulate the inflammatory response of experimental colitis at the level of signal transduction mechanisms. Mice genetically deficient of PARP-1 (PARP-1(-/-)) and wild-type littermates were subjected to rectal instillation of trinitrobenzene sulphonic acid (TNBS). Signs of inflammation were monitored for 14 days. In wild-type mice, TNBS treatment resulted in colonic ulceration and marked apoptosis, which was associated with decreased colon content of the antiapoptotic protein Bcl-2, whereas the proapoptotic Bax was unchanged. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were associated with activation of c-Jun-NH(2) terminal kinase (JNK), phosphorylation of c-Jun and activation of the nuclear transcription factor activator protein-1 (AP-1) in the colon. In contrast, PARP-1(-/-) mice exhibited a significant reduction of colon damage and apoptosis, which was associated with increased colonic expression of Bcl-2 and lower levels of plasma nitrate/nitrite when compared to wild-type mice. Amelioration of colon damage was associated with a significant reduction of the activation of JNK and reduction of the DNA binding of AP-1. The data indicate that PARP-1 exerts a pathological role in colitis possibly by regulating the early stress-related transcriptional response through a positive modulation of the AP-1 and JNK pathways.

CD62 Blockade with P-Selectin Glycoprotein Ligand-Immunoglobulin Fusion Protein Reduces Ischemia-Reperfusion Injury After Rat Intestinal Transplantation

BACKGROUND

Intestinal transplantation (ITx) is severely limited by ischemia-reperfusion (I/R) injury. This study investigates I/R injury and ameliorates its consequences by using a recombinant protein targeted against selectins (recombinant P-selectin glycoprotein ligand-immunoglobulin [rPSGL-Ig]).

METHODS

An isogeneic model of ITx was undertaken with control animals (no therapy) and treatment animals (rPSGL-Ig). Survival was assessed. Separate groups underwent an analysis examining tissue at multiple time points after I/R injury including histopathology; myeloperoxidase staining; immunostaining for CD3 and ED2; polymerase chain reaction analysis of interleukin (IL)-8/cytokine-inducible neutrophil chemoattractant, IL1beta, IL-6, interferon-gamma, IL-2, IL-4, and IL10; and western blots for hemoxygenase-1, BCL-2, and BCL-xl. Standard statistical analysis was undertaken.

RESULTS

Treatment with rPSGL-Ig resulted in significantly improved survival after ITx. Analysis demonstrated diminished injury on histopathology and reduced tissue infiltration of neutrophils and lymphocytes. Significant differences in the cytokine profile after ITx were seen between the two groups including the production of inflammatory cytokines at 24 hr and the Th1 and Th2 cytokines at 2 and 4 hr. Last, treatment resulted in increased production of hemoxygenase, BCL-2, and BCL-xl.

CONCLUSION

The results of this investigation of I/R injury after ITx revealed that rPSGL-Ig treatment led to marked improvement in outcome. The mechanism of action seems to involve the blockade of neutrophil and lymphocyte infiltration leading to a decreased inflammatory response possibly driven by Th2 cytokines. The results not only lend insight into the mechanisms behind I/R injury after ITx but also demonstrate a potential therapeutic modality to ameliorate its consequences.

The essential role of the intestinal microbiota in facilitating acute inflammatory responses

The restoration of blood flow, i.e., reperfusion, is the treatment of choice to save viable tissue following acute ischemia of a vascular territory. Nevertheless, reperfusion can be accompanied by significant inflammatory events that limit the beneficial effects of blood flow restoration. To evaluate the potential role of the intestinal microbiota in facilitating the development of tissue injury and systemic inflammation, germ-free and conventional mice were compared in their ability to respond to ischemia and reperfusion injury. In conventional mice, there was marked local (intestine) and remote (lung) edema formation, neutrophil influx, hemorrhage, and production of TNF-alpha, KC, MIP-2, and MCP-1. Moreover, there was an increase in the concentration of serum TNF-alpha and 100% lethality. In germ-free mice, there was no local, remote, or systemic inflammatory response or lethality after intestinal ischemia and reperfusion and, in contrast to conventional mice, germ-free animals produced greater amounts of IL-10. Similar results were obtained after administration of LPS, i.e., little production of TNF-alpha or lethality and production of IL-10 after LPS in germ-free mice. Blockade of IL-10 with Abs induced marked inflammation and lethality in germ-free mice after ischemia and reperfusion or LPS administration, demonstrating that the ability of these mice to produce IL-10 was largely responsible for their "no inflammation" phenotype. This was consistent with the prevention of reperfusion-associated injury by the exogenous administration of IL-10 to conventional mice. Thus, the lack of intestinal microbiota is accompanied by a state of active IL-10-mediated inflammatory hyporesponsiveness.

Heparin-binding epidermal growth factor-like growth factor and intestinal ischemia-reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury affects patients of different ages, especially premature babies and the elderly. The outcome after intestinal I/R is often dismal, which may be attributed to loss of the barrier and immune functions of the intestines, as well as development of secondary injury in remote organs. The available treatment for advanced gut ischemia mandates extensive resection, which may cause growth retardation in infants and nutritional problems in the elderly. Throughout the past decade we have been investigating the potential therapeutic role of heparin-binding epidermal growth factor-like factor (HB-EGF) in intestinal I/R. The mitogenic and chemoattractant functions of HB-EGF formed the initial rationale for our investigations. In addition, HB-EGF is a potent antiapoptotic protein that enables cells and tissues exposed to different apoptotic stimuli to survive hypoxic, oxidative, and nutritional stresses. HB-EGF is known to have a vital role in wound healing and postischemic regeneration in different organs. In the current review, we summarize the results of our findings of the beneficial effects of HB-EGF in intestinal I/R, supported by additional evidence from the literature and an explanation of different possible mechanisms of its actions. Collectively, the data strongly suggest a potential therapeutic role for the use of HB-EGF to treat intestinal ischemic diseases such as I/R and necrotizing enterocolitis.

Effect of tetramethylpyrazine on P-selectin and hepatic/renal ischemia and reperfusion injury in rats

AIM: To investigate the effect of tetramethylpyrazine on hepatic/renal ischemia and reperfusion injury in rats.

METHODS: Hepatic/renal function, histopathological changes, and hepatic/renal P-selectin expression were studied with biochemical measurement and immunohistochemistry in hepatic/renal ischemia and reperfusion injury in rat models.

RESULTS: Hepatic/renal insufficiency and histopathological damage were much less in the tetramethylpyrazine-treated group than those in the saline-treated groups. Hepatic/renal P-selectin expression was down regulated in the tetramethylpyrazine-treated group.

CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion injury. Tetramethylpyrazine might prevent hepatic/renal damage induced by ischemia and reperfusion injury through inhibition of P-selectin.

Platelet-activating factor promotes mucosal apoptosis via FasL-mediating caspase-9 active pathway in rat small intestine after ischemia-reperfusion

Platelet activating factor (PAF) is a proinflammatory lipid mediator for inflammatory response. It is unclear whether PAF is involved in the very complex process of ischemia-reperfusion (I/R) induced mucosal apoptosis in small intestine. Intestinal I/R was induced in rats intestine by 60 min occlusion of the superior mesenteric artery, followed by a 60 min reperfusion. I/R induced mucosal apoptosis and PAF activity but inhibited PAF-acetylhydrolase activity. Increases in interleukin-6 (IL-6) and decreases in IL-10 were observed. Western blot analysis showed that I/R induced expressions of platelet endothelial cell adhesion molecule-1 (PECAM-1) and Fas and Fas ligand (FasL) proteins, cleaved Bid, and enhanced the release of cytochrome c from mitochondria to activate caspase-9. Pretreatment of PAF antagonist BN-52021 attenuated these changes, except the increase in Fas. The results showed that I/R-inhibited mucosal PAF-acetylhydrolase activity resulted in an increase of activated PAF. The activated PAF increased the mucosal IL-6 and PECAM-1, enhanced the expression of FasL but not Fas, and led to the cleavage of Bid and the release of cytochrome c from mitochondria to activate caspase-9. This finding suggests that PAF promotes mucosal apoptosis after I/R in the rat small intestine partly through FasL mediating caspase-9 active pathway.

Role of PAF receptors during intestinal ischemia and reperfusion injury. A comparative study between PAF receptor-deficient mice and PAF receptor antagonist treatment

1 The reperfusion of ischemic tissues may be associated with local and systemic inflammation that prevents the full benefit of blood flow restoration. The present study aimed to confirm a role for platelet-activating factor receptor(s) (PAFR) during ischemia and reperfusion injury by using genetically modified mice deficient in the PAFR (PAFR(-/-) mice) and to evaluate comparatively the effectiveness of pharmacological treatment using the PAFR antagonist UK-74,505 (modipafant). 2 The reperfusion of the ischemic superior mesenteric artery (SMA) induced marked local (intestine) and remote (lungs) tissue injury, as assessed by the increase in vascular permeability, neutrophil influx and intestinal hemorrhage and in the production of TNF-alpha. There was also a systemic inflammatory response, as shown by the increase in serum TNF-alpha concentrations and marked reperfusion-associated lethality. 3 After reperfusion of the ischemic SMA, PAFR(-/-) mice had little tissue or systemic inflammation and lethality was delayed, but not prevented, in these mice. Interestingly, the reperfusion-associated increases in tissue concentrations of IL-10 were significantly greater in PAFR(-/-) than wild-type mice. 4 Pretreatment with PAFR antagonist UK-74,505 (1 mg kg(-1)) markedly prevented tissue injury, as assessed by the increase in vascular permeability, neutrophil accumulation, hemorrhage and TNF-alpha concentrations in the intestine and lungs. In contrast, UK-74,505 failed to affect reperfusion-associated lethality and increases in serum TNF-alpha when used at 1 mg kg(-1). 5 Reperfusion-associated lethality and increase in serum TNF-alpha were only affected when a supra-maximal dose of the antagonist was used (10 mg kg(-1)). At this dose, UK-74,505 also induced a marked enhancement of reperfusion-associated increases in tissue concentrations of IL-10. However, at the same dose, UK-74,505 failed to prevent reperfusion-associated lethality in PAFR(-/-) mice any further. 6 The present studies using genetically modified animals and a receptor antagonist firmly establish a role of PAFR activation for the local, remote and systemic inflammatory injury and lethality which follows reperfusion of the ischemic SMA in mice. Moreover, it is suggested that high doses of PAFR antagonists need to be used if the real efficacy of these compounds is to be tested clinically.

Inhibitors of poly (ADP-ribose) polymerase modulate signal transduction pathways in colitis

During inflammatory bowel diseases, oxidative and nitrosative stress induces DNA damage and activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP), resulting in depletion of intracellular energetics, intestinal barrier dysfunction and cellular death. The aim of our study was to evaluate the therapeutic efficacy of in vivo inhibition of PARP in experimental colitis, which was induced by rectal instillation of trinitrobenzene sulfonic acid (TNBS) in rats. In vehicle-treated rats, TNBS treatment resulted in colonic erosion and ulceration. Neutrophil infiltration (indicated by myeloperoxidase activity in the colon) was associated with formation of nitrotyrosine and marked apoptosis. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were associated with the activation of nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1) in the colon; NF-kappa B was maximally activated at 3 and 7 days, whereas AP-1 increased 1 day after TNBS administration and declined thereafter. Treatment of the rats with the PARP inhibitors, 3-aminobenzamide or 1,5-dihydroxyisoquinoline, resolved colonic damage and reduced plasma levels of NO metabolites. Resolution of the damage was associated with reduction of neutrophil infiltration, nitrotyrosine formation and apoptosis. Treatment with PARP inhibitors also reduced DNA binding of NF-kappa B and AP-1 in the colon. These data demonstrate that pharmacological inhibition of PARP ameliorates colitis. Reduction of the inflammatory process is associated with modification of the activation of signal transduction pathways.

Role of the bradykinin B2 receptor for the local and systemic inflammatory response that follows severe reperfusion injury

1. Bradykinin (BK) appears to play an important role in the development and maintenance of inflammation. Here, we assessed the role of the BK B(2) receptor for the injuries that occur after ischemia and reperfusion (I/R) of the territory irrigated by the superior mesenteric artery. 2. Tissue (lung and duodenum) kallikrein activity increased after ischemia with greater enhancement after reperfusion. A selective inhibitor of tissue kallikrein, Phenylacetyl-Phe-Ser-Arg-N-(2,3-dinitrophenyl)-ethylenediamine (TKI, 0.001-10 mg ml(-1)), inhibited kallikrein activity in a concentration-dependent manner in vitro. In vivo, pretreatment with TKI (30 mg kg(-1)) prevented the extravasation of plasma and the recruitment of neutrophils. 3. Similarly, the bradykinin B(2) receptor antagonists, HOE 140 (0.01-1.0 mg kg(-1)) or FR173657 (10.0 mg kg(-1)), inhibited reperfusion-induced increases in vascular permeability and the recruitment of neutrophils in the intestine and lungs. 4. In a model of more severe I/R injury, HOE 140 (1.0 mg kg(-1)) inhibited the increase in vascular permeability, neutrophil recruitment, haemorrhage and tissue pathology. Furthermore, HOE 140 significantly inhibited the elevations of TNF-alpha in tissue and serum and partially prevented lethality. This was associated with an increase in the concentrations of IL-10 in tissue and serum. 5. Thus, our results demonstrate that, following intestinal I/R injury, there is an increase in tissue kallikrein activity and activation of BK B(2) receptors. B(2) receptor activation is essential for the development of inflammatory tissue injury and lethality. These results contrast with those of others showing that BK mostly exerts a protective role during I/R injury.

IL-1-driven endogenous IL-10 production protects against the systemic and local acute inflammatory response following intestinal reperfusion injury

TNF-alpha release and action are central in the pathogenesis of the local and systemic inflammatory responses that occur after intestinal reperfusion. In this study we examined whether IL-1 participated in the cascade of events leading to TNF-alpha production and TNF-alpha-mediated injury following reperfusion of the ischemic superior mesenteric artery in rats. Blockade of the action of IL-1 by the use of anti-IL-1 antiserum or administration of IL-1R antagonist (IL-1ra), a natural antagonist of IL-1Rs, resulted in marked enhancement of reperfusion-associated tissue injury, TNF-alpha expression, and lethality. In contrast, there was marked decrease in IL-10 production. Facilitation of IL-1 action by administration of anti-IL-1ra, which antagonizes endogenous IL-1ra, or exogenous administration of rIL-1beta suppressed reperfusion-induced tissue pathology, TNF-alpha production, and lethality, but increased IL-10 production. Exogenous administration of IL-10 was effective in preventing the increase in tissue or plasma levels of TNF-alpha, the exacerbated tissue injury, and lethality. An opposite effect was observed after treatment with anti-IL-10, demonstrating a role for endogenous production of IL-10 in modulating exacerbated reperfusion-associated tissue pathology and lethality. Finally, pretreatment with anti-IL-10 reversed the protective effect of IL-1beta on reperfusion-associated lethality. Thus, IL-1 plays a major role in driving endogenous IL-10 production and protects against the TNF-alpha-dependent systemic and local acute inflammatory response following intestinal reperfusion injury.

Preconditioning of donors with interleukin-10 reduces hepatic ischemia-reperfusion injury after liver transplantation in pigs

BACKGROUND

Graft ischemia-reperfusion injury (IRI) resulting from postreperfusion inflammatory reaction remains a major cause of complications after liver transplantation. In this article, the authors investigated the effect of anti-inflammatory cytokine interleukin (IL)-10 on IRI, in a preclinical model of liver transplantation in pigs.

METHODS

Donor pigs received IL-10 or saline at the start of liver graft harvesting. After 5 hr of cold ischemia, liver grafts were transplanted into untreated recipient pigs. IRI severity was measured in recipients by transaminase release and by cellular infiltration and necrosis on liver biopsy specimens.

RESULTS

Donor IL-10 administration attenuated IRI, as indicated by significant reduction of mean peak of transaminase in recipients of grafts from IL-10-treated donors. In contrast, no significant differences in cell infiltration or amount of necrosis were observed on liver biopsy specimens between groups.

CONCLUSIONS

Donor preconditioning with IL-10 may constitute an interesting pharmacologic approach to reduce IRI severity after liver transplantation.

The heat shock response and cytoprotection of the intestinal epithelium

Following heat stress, the mammalian intestinal epithelial cells respond by producing heat shock proteins that confer protection under stressful conditions, which would otherwise lead to cell damage or death. Some of the noxious processes against which the heat shock response protects cells include heat stress, infection, and inflammation. The mechanisms of heat shock response-induced cytoprotection involve inhibition of proinflammatory cytokine production and induction of cellular proliferation for restitution of the damaged epithelium. This can mean selective interference of pathways, such as nuclear factor kappa B (NF-kappaB) and mitogen-activated protein kinase (MAPK), that mediate cytokine production and growth responses. Insight into elucidating the exact protective mechanisms could have therapeutic significance in treating intestinal inflammations and in aiding maintenance of intestinal integrity. Herein we review findings on heat shock response-induced intestinal epithelial protection involving regulation of NF-kappaB and MAPK cytokine production.

Ileal cytokine dysregulation in experimental necrotizing enterocolitis is reduced by epidermal growth factor

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. We have shown in previous studies that proinflammatory interleukin-18 and interleukin-12 are up-regulated in the ileum of rats with experimental NEC and that epidermal growth factor (EGF) reduces the development of disease. Here we investigated whether the protective effects of EGF are a result of changes in ileal interleukin-18, interleukin-12 and/or antiinflammatory interleukin-10.

METHODS

Newborn rats were artificially fed with either growth-factor-free rat milk substitute (RMS) or RMS supplemented with 500 ng/mL EGF (RMS + EGF) and NEC was induced via exposure to asphyxia and cold stress. Cytokine expression and localization were assessed using reverse-transcription real-time polymerase chain reaction and immunohistology/confocal microscopy.

RESULTS

Enteral administration of EGF (RMS + EGF) decreased overproduction of interleukin-18 and increased interleukin-10 production in the ileum. Furthermore, increased interleukin-10 production was associated with up-regulation of the transcription factor Sp1 in RMS + EGF rats.

CONCLUSIONS

These data suggest that EGF may reduce NEC via increased interleukin-10 and decreased interleukin-18 and that EGF-mediated up-regulation of Sp1 may account for the increased interleukin-10.

Modulation of nuclear factor-kappaB activation and decreased markers of neurological injury associated with hypothermic therapy in experimental bacterial meningitis

OBJECTIVE

This study was designed to evaluate the use of moderate hypothermia in a model of meningitis-induced brain injury and its effect on the activation of nuclear factor-kappaB, biological markers of neuronal injury, and neurobehavioral performance.

DESIGN

Randomized, prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Animals underwent a basilar cistern tap receiving either sterile saline as a placebo or an equivalent volume of a group B streptococcal suspension. Sixteen hours after inoculation, animals were stratified by their clinical severity score, were randomized to either hypothermic (32-34 degrees C) or normothermic (37-39 degrees C) conditions, and received antibiotics. Hypothermic animals were kept under these temperature conditions for 6 hrs before rewarming. Two protocols were used. For the first protocol, changes in nuclear factor-kappaB activation and heat shock protein induction at 24 hrs and 48 hrs after inoculation were evaluated. In the second protocol, serum C-tau concentrations at 5 days and neurobehavioral performances at 3 wks were assessed.

MEASUREMENTS AND MAIN RESULTS

Meningitis triggered a >50% increase in cerebral nuclear factor-kappaB activation. The addition of a 6-hr period of hypothermia reduced nuclear factor-kappaB activation by 32% when measured at the end of the hypothermic period. At 48 hrs, this decrease in nuclear factor-kappaB activation was no longer apparent, but there was a significant decrease in the heat shock response. Serum C-tau concentrations at 5 days postinjury, a biomarker of brain injury, were reduced by 69% in hypothermic treated animals. Furthermore, hypothermia reduced the brain water content of infected animals. However, hypothermia did not improve the animals' neurobehavioral performance.

CONCLUSION

The findings from this study suggest that hypothermia produces a transitory attenuation of nuclear factor-kappaB activation in meningitic brain injury and improvement in some biomarkers of neuronal injury. The consequence of intermittent suppression of nuclear factor-kappaB activation by inducing specific periods of hypothermia requires further study.

The regulation of ischemic acute renal failure by extrarenal organs

PURPOSE OF REVIEW

Recent work suggests that extrarenal organs, such as the liver, lung, spleen, brain, lymphoid tissues, and bone marrow, regulate acute renal failure. We now review several examples of such regulation.

RECENT FINDINGS

First, we demonstrate kidney-liver crosstalk during ischemic renal failure. Renal ischemia induces the renal production of interleukin 6 and the renal expression of interleukin 10 receptors; interleukin 6 stimulates the production of interleukin 10 by the liver; interleukin 10 ameliorates renal injury. The potential mechanisms of interleukin 6 and 10 are discussed. Second, we review the possible effects of the acute phase response on renal ischemic injury. We point out potential analogies between the recently reported association of increased interleukin 6 and C-reactive protein with myocardial ischemia, and renal ischemia. Third, we briefly review the salutary effects of hepatocyte growth factor, produced by the lung, spleen, and liver, on ischemic renal injury. Finally, we discuss how renal ischemia elicits an inflammatory response of neutrophils, macrophages, and T cells that may exacerbate the injury. Granulocyte-colony stimulating factor, produced by the kidney in response to ischemia, may participate in eliciting this inflammation. Such inflammation may be exacerbated by cytokines and growth factors released by the brain after traumatic injury.

SUMMARY

We discuss the existing evidence for extrarenal regulation of acute renal failure. This suggests that concurrent disease of those extrarenal organs might alter the course of acute renal failure.

IL-10 is not protective in intestinal ischemia reperfusion injury

BACKGROUND

Ischemia/reperfusion of the small intestine disrupts gut barrier function, increases bacterial translocation, and activates systemic pro-inflammatory responses. Pharmacological treatment with the anti-inflammatory cytokine interleukin-10 (IL-10) following ischemia to muscle reduces the severity of local and systemic inflammation. While endogenous IL-10 is protective in murine models of acute endotoxemia, its physiological role during direct gut injury is unknown.

PATIENTS AND MATERIALS

Mice genetically deficient in IL-10 (IL-10(-/-)) and their normal littermates (IL-10(+/+)) underwent 20 to 50 min of gut ischemia by occlusion of the superior mesenteric artery.

RESULTS

Both short- and long-term (>16 h) survival after reperfusion of IL-10(-/-) mice was identical to that of the wild-type littermates, with 50% mortality observed at 35 min of occlusion. The small bowel demonstrated discrete gross areas of hemorrhage and ischemia localized to the jejunum. No significant difference in the extent or time for occurrence of macroscopic or microscopic intestinal damage to the small bowel was observed in IL-10(-/-) or IL-10(+/+) mice, despite the marked elevation in serum IL-6.

CONCLUSIONS

The absolute serum concentration of IL-6 in the presence or the absence of IL-10 does not affect local or systemic response to ischemic intestinal injury. These results also demonstrate that the anti-inflammatory cytokine IL-10 does not play a significant local or systemic protective role in this model of ischemia/reperfusion.

Inducible nitric oxide synthase is not required in the development of endotoxin tolerance in mice

We investigated the role of inducible nitric oxide synthase (iNOS) in endotoxin tolerance, which was induced in mice genetically deficient of iNOS (iNOS-/-) and in wild-type littermates. In non-tolerant wild-type mice, endotoxin induced high mortality, elevation of plasma levels of nitrite and nitrate, tumor necrosis factor a (TNFalpha), and interleukin 10 (IL-10). These events were preceded by degradation of inhibitors kappaBalpha (IkappaBalpha) and kappaBI (IkappaBbeta), and activation of nuclear factor-kappaB (NF-kappaB) in the lung. Pretreatment of wild-type mice with a sublethal dose of endotoxin prior to lethal endotoxin administration ameliorated lethality and blunted TNFalpha production, whereas IL-10, nitrite, and nitrate production was maintained. These events were associated with reduction of IKBa degradation and NF-kappaB activation in the lung. The kinetics of degradation of IkappaBbeta were also altered. In parallel experiments, nontolerant iNOS-/- mice experienced similar mortality after endotoxin as nontolerant wild-type mice. Plasma levels of nitrite and nitrate were not elevated after lethal endotoxin administration. IL-10 levels were significantly reduced in comparison to nontolerant wild-type mice, whereas TNFalpha levels were similarly increased. These events were preceded by lesser degradation of IkappaBalpha and reduced NF-kappaB activation in the lung. Pretreatment of iNOS-/- mice with a sublethal endotoxin ameliorated lethality. TNFalpha production was significantly reduced, whereas IL-10 production was significantly increased when compared to nontolerant iNOS-/- mice. Degradation of IkappaBalpha and activation of NF-kappaB in the lung were not altered by endotoxin tolerance, whereas kinetics of IkappaBbeta degradation was only delayed. Our data suggests that iNOS is not required for the development of endotoxin tolerance, and that other signal transduction pathways, rather than NF-kappaB, may regulate induction of endotoxin tolerance in the absence of iNOS.

Protective role of cyclooxygenase (COX) inhibitors in burn-induced intestinal and liver damage

The aim of this study was to investigate the role of cyclooxygenase (COX) inhibition in intestinal motility and in the extent of tissue injury of the small intestine and liver with the use of various COX inhibitors. Wistar albino rats were exposed to 90 degrees C water bath for 10s. The intestinal transit index decreased compared to control group and treatment with nimesulide (NIM; 10mg/kg, subcutaneously) or piroxicam (Pir; 5mg/kg, orogastrically) reversed this effect significantly. The intestinal and liver glutathione levels showed a significant decrease in the burn group compared to sham (P<0.001 and P<0.05, respectively). Decrease in intestinal glutathione level was reversed by NIM or Pir treatment (P<0.01 and P<0.01, respectively), whereas all drugs tested were effective in reversing low liver glutathione level. The MPO activity in intestinal segments were significantly high in burned animals compared to sham. All test drugs reversed this effect but ketorolac (Ket; 3mg/kg, orogastrically) was the most effective one. The liver samples characterized by sinusoidal dilatation and pericentral atrophy in burn group were protected by treatment with Ket or Pir (P<0.05). Plasma ALT and AST activities were markedly high in this burn group compared to sham (P<0.0001 and P<0.001, respectively). None of the agents reversed these high enzyme activities. These data suggest that not only COX-2 but also COX-1 inhibition is required for protection against inflammatory changes in liver and small intestine following burn injury.

The heat shock response and cytoprotection of the intestinal epithelium

Following heat stress, the mammalian intestinal epithelial cells respond by producing heat shock proteins that confer protection under stressful conditions, which would otherwise lead to cell damage or death. Some of the noxious processes against which the heat shock response protects cells include heat stress, infection, and inflammation. The mechanisms of heat shock response-induced cytoprotection involve inhibition of proinflammatory cytokine production and induction of cellular proliferation for restitution of the damaged epithelium. This can mean selective interference of pathways, such as nuclear factor kappa B (NF-kappaB) and mitogen-activated protein kinase (MAPK), that mediate cytokine production and growth responses. Insight into elucidating the exact protective mechanisms could have therapeutic significance in treating intestinal inflammations and in aiding maintenance of intestinal integrity. Herein we review findings on heat shock response-induced intestinal epithelial protection involving regulation of NF-kappaB and MAPK cytokine production.

Absence of inducible nitric oxide synthase modulates early reperfusion-induced NF-kappaB and AP-1 activation and enhances myocardial damage

The role of nitric oxide (NO) generated by the inducible NO synthase (iNOS) during myocardial ischemia and reperfusion is not understood. We investigated the role of iNOS during early reperfusion damage induced in genetically deficient iNOS (iNOS-/-) mice and wild-type littermates. In wild-type mice, ischemia (60 min) and reperfusion (60 min) induced an elevation in serum levels of creatine phosphokinase and myocardial injury characterized by the presence of scattered apoptotic myocytes and mild neutrophil infiltration. Northern blot analysis showed increased expression of iNOS, whose activity was markedly elevated after reperfusion. Immunohistochemistry showed staining for nitrotyrosine; Western blot analysis showed elevated expression of heat shock protein 70 (HSP70), a putative cardioprotective mediator. Plasma levels of nitrite and nitrate, tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and IL-10 were also increased. These events were preceded by degradation of inhibitor kappaBalpha (IkappaBalpha), activation of IkappaB kinase complex (IKK) and c-Jun-NH2-terminal kinase (JNK), and subsequently activation of nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) as early as 15 min after reperfusion. In contrast, iNOS-/- mice experienced 35% mortality after reperfusion. The extensive myocardial injury was associated with marked apoptosis and infiltration of neutrophils whereas expression of HSP70 was less pronounced. Nitrotyrosine formation and plasma levels of nitrite and nitrate were undetectable. TNF-alpha and IL-6 were increased and IL-10 was reduced in earlier stages of reperfusion. Activation of IKK and JNK and binding activity of NF-kappaB and AP-1 were significantly reduced. Thus, we conclude that iNOS plays a beneficial role in modulating the early defensive inflammatory response against reperfusion injury through regulation of signal transduction.

New advances in the molecular and cellular biology of the small intestine

Research into the structure and function of the small intestinal mucosa is becoming increasingly focused on the molecular and cellular biology of this fascinating tissue. There is a growing understanding of the factors determining the expression of specific genes at different stages of development and differentiation in the multiple cell types, and several important transcription factors have emerged. Recent publications have included studies of the effects of commensal bacteria on gene expression and the molecules producing apoptosis. Mechanisms of the intestinal adaptation to injury or surgery involve a number of hormones; current research has shown a major role for glucagon-like peptide 2.