Intestinal cytokine response after gut ischemia: role of gut barrier failure

Characterisation of Escherichia coli strains involved in transcytosis across gut epithelial cells exposed to metabolic and inflammatory stress

Translocation of normally non-pathogenic bacteria across the gut may drive inflammatory responses associated with sepsis and inflammatory bowel disease. Recent evidence suggests translocation may not be purely passive, but occurs via novel transcellular pathways activated in enterocytes by inflammatory and metabolic stress. The specificity of this pathway with respect to different E. coli strains and other bacterial species, and possible molecular determinants of the "translocating" phenotype have been investigated. Translocation of E. coli strains and other bacteria was studied across Caco-2 monolayers exposed to different forms of cellular stress. All bacteria, apart from the pathogen Shigella sonnei, exhibited low levels of translocation in untreated monolayers. However, following enterocyte stress, translocation of E. coli strains C25 and HBTEC-1 was markedly stimulated, accompanied by increased internalisation into enterocytes. C25 and HBTEC-1 were typed to ECOR group A and group D respectively. Pathoarray analysis showed both strains had profiles quite different to those predicted for typical ExPEC isolates, lacking many of the genes associated with pathogenicity, although they contained several ORFs in common with ExPEC isolates. These data suggest translocating E. coli strains associated with infections are not opportunistic ExPEC strains but may comprise a separate group of E. coli strains.

Splanchnic ischemia and gut permeability after acute brain injury secondary to intracranial hemorrhage

INTRODUCTION

Splanchnic ischemia (SI) and increased gut permeability (GP) have been described in acute brain injury (ABI), although their incidence and relation to the type and severity of injury are uncertain. The aim of this study was to evaluate the incidence of both abnormalities in a series of patients with severe ABI secondary to intracranial hemorrhage (ICH) managed with a resuscitation protocol pursuing adequate cerebral and systemic hemodynamics.

METHODS

Eight patients with severe ABI secondary to ICH were admitted to the ICU and were mechanically ventilated and monitored with intracranial pressure measurement, jugular bulb venous oxygen saturation, arterial lactate concentration and gastric tonometry. All patients were managed actively to maintain adequate blood and cerebral perfusion pressures with a protocol based on aggressive fluid resuscitation prior to vasoactive drugs administration. GP was assessed using the lactulose/mannitol test (LMT). Values were recorded during the first 7 days of hospital stay.

RESULTS

Arterial lactate concentration was within the normal range (1.9 +/- 0.5 mmol/l) in all patients. Upon admission, the mean pCO(2) gap was 8.2 +/- 4.3 mmHg (1.09 +/- 0.57 kPa) with an intramucosal pH of 7.4 +/- 0.1. All patients had an abnormal LMT (0.066 +/- 0.055) compared with 19 healthy volunteers (0.025 +/- 0.004) (p < 0.05, Mann Whitney test).

CONCLUSION

Splanchnic ischemia is uncommon among patients with acute brain injury secondary to intracranial hemorrhage, provided they are adequately resuscitated with a protocol based mainly on fluids to achieve an adequate CPP. Gut hyperpermeability is commonly present, despite the absence of splanchnic ischemia.

Influence of glutamine on intestinal inflammatory response, mucosa structure alterations and apoptosis following traumatic brain injury in rats

Traumatic brain injury (TBI) can induce a persistent inflammatory response, histopathological changes and apoptosis in the intestine. Glutamine has been shown to reduce bacterial translocation and maintain intestine mucosal integrity, but its effects on the inflammatory response, structural alterations and apoptosis in intestinal mucosa following TBI have not been previously investigated. Using the weight-drop method, a right parietal cortical contusion was induced in rats and, for the next 5 days, they were fed either chow alone or chow mixed with glutamine. Intestinal tissue samples were then removed for analysis. Following TBI, glutamine supplementation was found to: decrease intestinal concentrations of interleukin (IL) -1beta, tumour necrosis factor-alpha (TNF-alpha) and IL-6; downregulate intercellular adhesion molecule-1 (ICAM-1) expression; attenuate TBI-induced damage to the intestine structure; and reduce apoptosis. These results suggest that post-TBI glutamine administration could suppress intestinal inflammation, protect intestinal mucosal structure and reduce mucosal apoptosis.

Low levels of procalcitonin during episodes of necrotizing enterocolitis

The pathogenesis of necrotizing enterocolitis (NEC) remains poorly understood. We aimed to assess the extent of bacterial infection in the pathogenesis of NEC using serial procalcitonin measurements. Blood samples were drawn during the first 4 days following every clinical event requiring a workup for presumed NEC. Eight episodes were confirmed as NEC, 7 of which showed procalcitonin levels <1 ng/ml at presentation and <1.3 ng/ml thereafter, comparable to 24 healthy controls. The one infant with elevated procalcitonin had bacteremia in addition to NEC. Procalcitonin levels of 24 matched septic infants were higher than those of NEC infants, peaking at 4.1 ng/ml. We conclude that low procalcitonin values are the rule during episodes of NEC and provide further evidence that overactive local immune response, and not active infection, is primarily responsible for the mucosal damage in NEC.

C1-esterase inhibitor reverses functional consequences of superior mesenteric artery ischemia/reperfusion by limiting reperfusion injury and restoring microcirculatory perfusion

Activated complement contributes significantly to reperfusion injury after ischemia. This study explores functional consequences of C1-esterase inhibitor (C1-INH) treatment after superior mesenteric artery occlusion (SMAO)/reperfusion using intravital microscopy. Thirty anesthetized, spontaneously breathing, male Sprague-Dawley rats underwent SMAO for 60 min followed by reperfusion (4 h). C1-esterase inhibitor (100 and 200 IU/kg body weight) or saline (0.9%) was given as a single bolus before reperfusion. Sham-operated animals (n = 10) without SMAO served as controls. Systemic hemodynamics were monitored continuously, arterial blood gases analyzed intermittently, and leukocyte/endothelial interactions in the mesenteric microcirculation quantified at intervals using intravital microscopy. Ileal lipid-binding protein (I-LBP) levels were determined from serum samples with an enzyme-linked immunosorbent assay at the end of the experiments. C1-esterase inhibitor restored microcirculatory perfusion to baseline levels in a dose-dependent manner and reduced adherent leukocytes after SMAO/reperfusion to similar levels in both C1-INH-treated groups during reperfusion. Furthermore, C1-INH treatment efficiently prevented metabolic acidosis, reduced the need for intravenous fluids to support blood pressure, and decreased I-LBP levels in a dose-dependent manner. Survival rates were 100% in controls and after 200 IU/kg C1-INH, 90% after 100 IU/kg C1-INH, and 30% in saline-treated animals. C1-esterase inhibitor bolus infusion efficiently blunted functional consequences of mesenteric ischemia/reperfusion with I-LBP, proving to be a valuable serum marker mirroring the effect of ischemia/reperfusion and treatment at the end of the experiments.

Effects of progesterone on intestinal inflammatory response, mucosa structure alterations, and apoptosis following traumatic brain injury in male rats

BACKGROUND

Traumatic brain injury (TBI) can induce a persistent inflammatory response, histopathological changes, and apoptosis in the gut. Progesterone given after TBI has been shown to reduce the cerebral inflammation and neuronal apoptosis in the brain. However, the effects of progesterone on the inflammatory response, structure alterations, and apoptosis in the intestinal mucosa following TBI has not been investigated.

MATERIALS AND METHODS

Right parietal cortical contusion in male rats was made by using the weight-dropping method. Rats were given 0 or 16 mg/kg injections of progesterone at postinjury at 1 and 6 hours and on days 1, 2, 3, 4, and 5. Gut samples were extracted at 5 days after trauma. We measured the concentrations of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, and interleukin-6 (IL-6) by enzyme-linked immunosorbent assay; intercellular adhesion molecule-1 expression by immunohistochemistry; intestinal mucosal morphological changes by histopathological study and electron microscopy; and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining.

RESULTS

Administration of progesterone following TBI could decrease the intestinal concentrations of IL-1beta and tumor necrosis factor-alpha, but not IL-6. The level of intercellular adhesion molecule-1 expression in the gut was down-regulated by progesterone. TBI-induced damages of gut structure and apoptosis were attenuated after progesterone injections.

CONCLUSIONS

The results of the present study suggest that post-TBI progesterone administration could suppress the intestinal inflammation, protect the intestinal mucosal structure, and reduce the mucosa apoptosis.

The significance of bowel permeability

PURPOSE OF REVIEW

In clinical research, increased permeability has been scrutinized as a potential indicator of the severity of gastrointestinal disease and as a potential cause of the perpetuation of severe inflammatory activity in infectious states. This review discusses old and recent epidemiological and clinical evidence to establish whether increased permeability in sepsis is a sequel or a cause of multiple organ failure. In addition, old and new evidence linking inflammation and permeability in abnormal gastrointestinal anatomy and function to liver abnormalities in susceptible patients will be reviewed.

RECENT FINDINGS

Intestinal permeability has been found to be increased in several gastrointestinal diseases but not to be a very good marker of the severity of disease. Evidence is put forward supporting the claim that increased intestinal permeability is part of generalized leakiness of tight junctions in multiple organ failure and to play a less strong role as a primary event in its pathogenesis. Endemic malnutrition has been shown to be caused by interplay between malnutrition and intestinal inflammation. Recently experimental evidence has been put forward suggesting that enteral fat has anti-inflammatory effects on the intestine via the autonomic nervous system. Old clinical and new epidemiological evidence links intestinal inflammation, disruption of the enterohepatic cycle of bile acids, and liver disease.

SUMMARY

The implications of the described findings are that inflammatory activity, locally induced by abnormal intestinal anatomy and disruption of the bile acid pool, or systemically by severe and uncontrolled inflammation/infection, should be the focus of treatment or research. In addition, the connection between intestinal inflammation and liver disease should be investigated.

Prolonged anorexia and elevated plasma cytokine levels following myeloablative allogeneic hematopoietic cell transplant

Myeloablative conditioning regimens commonly lead to prolonged anorexia and poor oral intake. In a prospective study of 147 patients receiving CY, total body irradiation and allogeneic hematopoietic cells, we determined the extent of decline in oral intake and assessed plasma cytokine levels and development of acute GVHD as explanations for protracted anorexia. For each patient, daily oral caloric intake was expressed as a percent of estimated basal requirements, calculated as basal energy expenditure, through day 20. Oral caloric intake was significantly reduced in 92% of patients and remained low. The nadir in oral intake occurred at days 10-12, when median oral caloric intake was 3% of basal energy requirements. Plasma cytokines known to affect appetite (IL2, IL6, tumor necrosis factor-alpha) were significantly elevated above normal following conditioning therapy (P<0.001 for each cytokine). Acute GVHD did not appear to affect oral intake to transplant day 20 in this cohort of patients; however, plasma levels of IL6 rose steeply before the clinical onset of GVHD. Persistent fever occurred with the greatest frequency in patients with most profound reduction in oral intake. We conclude that prolonged alterations in oral intake following this myeloablative regimen may be related to circulating cytokines known to alter eating behavior.

Donor pretreatment with FK506 reduces reperfusion injury and accelerates intestinal graft recovery in rats

BACKGROUND

FK506 alleviates warm ischemia-reperfusion injury, but it remains unknown if such protection is manifest after cold storage and transplantation. We studied the early outcome after transplantation of intestines from donors pretreated with FK506 compared to grafts from controls treated with saline (154 mM NaCl).

METHODS

Sprague-Dawley rats received 0.3 mg/kg FK506 or saline intravenously 6 hours before graft retrieval. The small bowel was harvested, stored for 3 hours, and then transplanted heterotopically. Samples were taken after preservation and at 20 minutes, 6 hours, 12 hours, and 24 hours after reperfusion. Heat shock protein 72 (Hsp72) and iintercellular adhesion molecule (ICAM)-1 expression and nuclear factor kappaB (NF-kappaB) activation were assessed via Western blots and eelectrophoretic mobility shift assay (EMSA), respectively. Dissacharidase activity and enterocyte proliferation rate were also studied.

RESULTS

Preservation injury was similar between groups, but pretreated grafts had better morphology already 20 minutes after reperfusion. Control grafts always had thinner mucosa and more PMN infiltration. Hsp72 expression was greater in pretreated grafts. ICAM-1 was absent after harvesting, preservation, and immediately after reperfusion but increased in control grafts at the later time points. Control grafts showed a biphasic NF-kappaB activation pattern, whereas NF-kappaB activation was inhibited effectively in pretreated grafts. Dissacharidase activity decreased during the first 6 hours after reperfusion but recovered within 24 hours in pretreated grafts but not in control grafts. Earlier enterocyte proliferation was observed in pretreated grafts.

CONCLUSIONS

FK506 donor pretreatment reduced graft proinflammatory activation and neutrophil inflammation. Pretreated groups revealed a milder reperfusion injury and accelerated morphologic and functional recovery. The mechanisms involved appear to involve Hsp72 upregulation and NF-kappaB inhibition.

The effect of L-arginine and aprotinin on intestinal ischemia-reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) results in local mucosal injury, systemic injuries, and organ dysfunction. These injuries are characterized by altered microvascular and epithelial permeability and villous damage. Activation of neutrophils, platelets, and endothelial factors are known to be involved in this process. Cytokines such as TNF-alpha, IL-1, IL-6, and oxygen-derived free radicals are believed to be important pathogenic mediators. Capillary no-reflow is also known to play a role in I/R. The aim of our study was to examine the role of L-arginine, a known nitric oxide (NO) donor, and aprotinin, a protease inhibitor with multiple effects, on intestinal I/R.

METHODS

Pigs weighing 20-25 kg were used. Ischemia was established by clamping the superior mesenteric artery (SMA) at its origin and was sustained for 2 hours. Duration of reperfusion was 2 hours. The animals were divided into four groups: group A, the control group, which was submitted to I/R injury only; group B, in which L-arginine was administered at a rate of 5 mg/kg/min during ischemia and continuing throughout reperfusion; group C, in which aprotinin was administered with an initial bolus dose of 20,000 U/kg during ischemia followed by a continuous dose at 50 U/hour throughout reperfusion; and group D in which both substances were administered. In all groups TNF-alpha, IL-1, and IL-6 levels were measured using ELISA at baseline, 2 hours of ischemia, and 1 hour and 2 hours of reperfusion. SMA blood flow was measured with a Doppler probe at baseline, 10 min, 1 hour, and 2 hours of reperfusion. Histological changes of the intestinal mucosa were examined and graded on a five-point scale in all groups.

RESULTS

In the control group, levels of TNF-alpha, IL-1, and IL-6 were significantly increased during reperfusion (p < 0.05) compared to baseline. Administration of L-arginine and aprotinin led to suppression of the release of TNF-alpha, IL-1, and IL-6 during reperfusion in a statistically significant manner (all p < 0.05). A synergistic or additive effect of L-arginine and aprotinin was not observed. SMA blood flow in the control group was decreased (p > 0.05) during reperfusion compared to baseline. In animals treated with L-arginine and aprotinin, SMA blood flow during reperfusion was significantly increased (p < 0.05) compared to the control group. Histologic examination of the intestinal mucosa was characterized by flattening of the villi and necrosis in the control group. In the treated animals, less severe histological changes were noted.

CONCLUSIONS

Administration of L: -arginine and aprotinin may lead to amelioration of intestinal I/R injury. We did not note a synergistic or additive effect of these two substances. These findings warrant further studies in clinical settings for future treatment efforts.

Heparin-binding EGF-like growth factor decreases inflammatory cytokine expression after intestinal ischemia/reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury is believed to be the major initiator of the systemic inflammatory response syndrome. As a result of intestinal I/R, the gut becomes a major source of inflammatory cytokine production. We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) is cytoprotective after intestinal I/R and down-regulates pro-inflammatory cytokine production in vitro. We now examine the effects of HB-EGF on pro-inflammatory cytokine expression in vivo.

MATERIALS AND METHODS

Rats were randomized into three groups: sham-operated, superior mesenteric artery occlusion (SMAO) for 90 min followed by 8 h of reperfusion (I/R), and I/R with intraluminal administration of HB-EGF 25 min after the initiation of ischemia (I/R + HB-EGF). Serum was drawn at 2, 4, 6, and 8 h post reperfusion for determination of cytokine protein levels using a bioplex suspension array system. Additional animals underwent the same ischemic protocol followed by 30 and 60 min of reperfusion with harvesting of ileal mucosa. Ileal pro-inflammatory cytokine gene expression was determined using reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for TNF-alpha, IL-6, and IL-1beta.

RESULTS

HB-EGF decreased TNF-alpha, IL-6, and IL-1beta serum protein levels at 4, 6, and 8 h after intestinal I/R injury. In addition, HB-EGF decreased local intestinal mucosal mRNA expression of TNF-alpha, IL-6, and IL-1beta 30 and 60 min after intestinal injury.

CONCLUSIONS

We conclude that pro-inflammatory cytokine expression is increased both locally and in the systemic circulation after intestinal I/R and that the administration of HB-EGF significantly reduces intestinal I/R-induced pro-inflammatory cytokine expression in vivo.

Intestinal involvement secondary to the antiphospholipid syndrome (APS): clinical and immunologic characteristics of 97 patients: comparison of classic and catastrophic APS

OBJECTIVE

To analyze the clinical and laboratory characteristics of 97 patients with intestinal involvement secondary to the antiphospholipid syndrome (APS) (37 patients with classic APS and 60 with catastrophic APS).

METHODS

A computer-assisted (PubMed) search of the literature was performed to identify all cases of intestinal involvement associated with the APS from 1983 to December 2005. In addition, we analyzed the web-site-based international registry of patients with catastrophic APS ("CAPS Registry").

RESULTS

There were no differences in distribution by gender, mean age, and previous clinical manifestations of APS between the 2 groups. The prevalence of abdominal pain as the presenting manifestation of intestinal ischemia was higher in patients with classic APS (76% versus 37%; P < 0.005). The main difference in histopathologic findings between the 2 groups was the higher rate of microthrombosis in patients with catastrophic APS (75% versus 4%; P < 0.0005). The mortality rate was higher in patients with catastrophic APS (55% versus 17%; P < 0.0005). Follow-up was available in 22 patients with classical APS: 17 of them were discharged on oral anticoagulation and with a mean follow-up of 13 months (range, 1 to 48); all were in good health without the development of new thrombotic events.

CONCLUSIONS

Intestinal involvement, although infrequent, is an important complication in patients with APS, especially in those with catastrophic APS. This would support the need for systematic screening for aPL in all cases of mesenteric thrombosis or ischemic colitis without clear underlying predisposing factors, and for systematic screening procedures in all classic APS patients complaining of abdominal pain.

Protective effects of nafamostat mesilate on liver injury induced by lipopolysaccharide in rats: possible involvement of CD14 and TLR-4 downregulation on Kupffer cells

Nafamostat mesilate (NM) is a synthetic protease inhibitor with various biological effects. To determine its effect on liver injury related to sepsis, we investigated the effects of NM on lipopolysaccharide (LPS)-induced liver injury. Wistar rats were allocated into two groups; the NM group underwent intraperitoneal NM administration 30 min before LPS administration, and the control group underwent PBS administration. Serum AST and ALT levels were significantly decreased in NM-treated rats. Reduced levels of TNF-alpha, IL-1beta, and IFN-gamma were observed after LPS administration in NM-treated rats. No significant differences were observed in IL-6 levels between the NM and the control group. In contrast, HGF levels were significantly increased only in control rats. NM treatment decreased protein and mRNA levels of TLR-4 and CD14. Our data suggest that NM treatment has protective effects against LPS-induced hepatotoxicity through downregulation of TLR4 and CD14 in liver, which decreased TNF-alpha, IL-1beta, and IFN-gammaproduction in liver.

Apoptosis and functional changes of dipeptide transporter (PepT1) in the rat small intestine after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) can induce significant alterations of intestinal mucosal structure and barrier function. However, it has not been investigated whether, and to what degree, apoptosis and alterations of absorptive function in the intestinal mucosal epithelium occur after TBI.

MATERIAL AND METHODS

Male Wistar rats were randomly divided into seven groups (five rats each group) including normal group, control group with sham operation, and TBI groups at hours 3, 12, 24, and 72, and on day 7. Parietal brain contusion was adopted using weight-dropping method. Intestinal mucosal structure was examined using histomorphmetric study and electron microscopy, and apoptosis was detected by TUNEL method. An everted sleeve of intestine was securely incubated in Kreb's solution with radioactive dipeptide ((3)H-Gly-Sar, 10 microCi/mL) to measure the uptake and transport of PepT1 of small intestinal epithelial cells.

RESULTS

The villous height, crypt depth and surface area were significantly decreased at 24 h after TBI, and further declined to the degree of mucosal atrophy on day 7 after TBI. Apoptotic changes of condensed nuclei in epithelial cells and fractured, distorted, and sparse microvilli were found by electron microscopy. The number of apoptotic cells in the mucosal epithelium was significantly increased since 3 h after TBI, peaked at 72 h post-injury, then declined at 7 days, but was still higher than that of control. There was a highly negative relation between the apoptotic index and the villous height, the crypt depth, and villous surface area. Compared with that of normal and control rats, the transport and uptake of dipeptide was significantly increased at 3 h post-injury (P < 0.01), peaked at 12 h and declined a bit at 24 h post-injury, and returned to the level of normal and control rats at 72 h and 7 days.

CONCLUSIONS

It is highly suggested that intestinal mucosa apoptosis plays an important role in the pathogenesis of acute gut damage after TBI. Intestinal PepT1 expression could be up-regulated after traumatic brain injury, and maintained the normal level under the condition of serious intestinal damage. Up-regulation of PepT1 may adaptively improve absorption of di- and tripeptides, independent of changes in the mucosal surface area.

The inflammation in the gut after experimental subarachnoid hemorrhage

BACKGROUND

Gastrointestinal dysfunction could be frequently observed in the patients suffering from SAH. This study test the hypothesis that experimental SAH could induce histopathological changes and inflammatory response associating with NF-kappaB activation pathway in the gut.

MATERIALS AND METHODS

A total of 17 rabbits were randomly divided into two groups: control group (n = 8) and SAH group (n = 9). In the SAH group, the animals were subjected to experimental SAH according to the "two-hemorrhage" method. The histopathological study was performed to detect the intestinal mucosal morphological changes and immunohistochemical study was used to detect the TNF-alpha and ICAM-1 expressions. NF-kappaB binding activity was measured using the electrophoretic mobility shift assay.

RESULTS

It was demonstrated that some damage changes and leukocytes infiltration occurred in the intestinal mucosa after SAH. More positive cells for TNF-alpha and ICAM-1 were observed in the SAH group. The NF-kappaB binding activity in the intestines was significantly increased in the SAH group (P < 0.01).

CONCLUSIONS

The results of the present study suggest that SAH in the rabbits could induce NF-kappaB and proinflammatory cytokines activation in the intestine, which is associated with morphological changes.

Vasoactive drugs and the gut: is there anything new?

PURPOSE OF REVIEW

Systemic changes in blood pressure and cardiac output induced by pressors and inotropes do not always correlate to improvements in regional perfusion. Since the gut is often referred to as the 'motor' of the systemic inflammatory response syndrome, the impact of vasoactive agents on splanchnic perfusion has theoretical importance. This review will highlight recent studies examining secondary effects of vasoactive agents on intestinal perfusion, metabolism, and barrier function.

RECENT FINDINGS

Norepinephrine has minimal impact on mesenteric blood flow although the combination of norepinephrine and dobutamine increases splanchnic blood flow in sepsis. Dopamine also increases mesenteric blood flow although this may be associated with negative hepatic energy balance at high does. Vasopressin and epinephrine both have negative effects on splanchnic blood flow. Newer inodilators levosimendan and olprinone preferentially improve mesenteric perfusion in animal models.

SUMMARY

Secondary effects of norepinephrine and dopamine on splanchnic perfusion are minor compared with their systemic effects. While vasopressin usage is increasing in the intensive care unit, caution should be used because of its adverse effects on gut perfusion. Experimental agents for the treatment of heart failure have beneficial gut-specific effects although the clinical significance of this is currently limited by their availability.

Transplantation of preconditioned intestinal grafts is associated with lower inflammatory activation and remote organ injury in rats

Reperfused grafts--particularly the intestine--release free radicals and cytokines into the systemic circulation. The type of discharge, which is greatly dependent on the local injury, may also induce inflammatory activation in distant organs and leading to multiple system and organ failure. It has been suggested that intestinal grafts from tacrolimus (TRL)-pretreated donors show improved morphology and microcirculation. We studied whether transplantation of intestines from TRL-pretreated donors influenced inflammatory response and remote organ injury posttransplantation. Donor Sprague Dawley rats received TRL or saline (controls) intravenously at 6 hours prior to graft harvest. The intestinal grafts were preserved in saline for 3 hours before transplantation. At 6 and 12 hours postreperfusion hepatic and renal cortical microcirculation were assessed using laser-Doppler flowmetry (n = 8-12 per group). Blood pressure was measured; liver, kidney, and serum samples were obtained. We analyzed hepatic and renal ICAM-1 expression and caspase-3-like activity as well as plasma content of tumor necrosis factor-alpha and interleukin-6. Pretreated graft recipients had higher mean arterial pressure (82 +/- 10 vs 51 +/- 17 mm Hg, P < .05) and renal perfusion at 6 hours whereas liver perfusion was similar at both 6 and 12 hours. Liver and renal functions were also superior among recipients of pretreated grafts. Both caspase-3-like activity and ICAM-1 expression in liver and kidney were lower in pretreated graft recipients. Plasma IL-6 levels were lower in animals receiving pretreated grafts. Transplantation of intestines from TRL-pretreated donors was followed by a lower systemic inflammatory response, improved organ function and decreased remote injury early posttransplantation compared with animals receiving grafts from untreated donors.

BIOACTIVITY OF POSTSHOCK MESENTERIC LYMPH DEPENDS ON THE DEPTH AND DURATION OF HEMORRHAGIC SHOCK

Mesenteric hypoperfusion due to circulatory shock is a key event in the pathogenesis of subsequent distant organ injury. Postshock mesenteric lymph (PSML) has been shown to contain proinflammatory mediators elaborated from the ischemic gut. We hypothesize that the relative bioactivity of PSML depends on the depth and duration of circulatory shock. To first determine the timing of PSML bioactivity, we subjected rats to hemorrhagic shock (30 mm Hg x 45 min) and then resuscitation with 50 vol% of shed blood and normal saline (4x shed blood) over 2 h. Mesenteric lymph was collected hourly up to 6 h after shock. Superoxide release was measured from human neutrophils (polymorphonuclear neutrophils [PMNs]) incubated with lymph fractions collected from each of the hourly time points. Rats were then subjected to four different shock variations: (1) 30 mm Hg x 45 min, (2) 30 mm Hg x 15 min, (3) 45 mm Hg x 45 min, and (4) 45 mm Hg x 15 min, and were resuscitated. PSML flow depends on depth of shock, but not duration of shock or resuscitation volume. Maximal PSML bioactivity, as measured by PMN priming for the respiratory burst, occurred during the third postshock hour, which correlated with peak lymph flow rate. PSML bioactivity was greatest with 30 mm Hg x 45 min, followed by 30 mm Hg x 15 min, 45 mm Hg x 45 min, and 45 mm Hg x 15 min. Hemorrhagic shock provokes the release of bioactive agents in PSML that is dependent on both depth and duration of shock.

Increased bacterial permeation in long-lasting ileoanal pouches

BACKGROUND AND AIMS

Bacterial overgrowth appears to play an important role in the pathogenesis of ileoanal pouches. Therefore, the capability of bacterial permeation and its determinants is of great interest. The aim of this study was to examine bacterial permeation in the ileoanal pouch and to correlate the results with the degree of inflammation, the epithelial resistance, the mucosal transport function, and the age of the ileoanal pouches.

MATERIALS AND METHODS

Biopsies were taken from 54 patients before colectomy (n = 13; preileal pouch-anal anastomosis [IPAA]), and closure of ileostomy (n = 7; deviation), <1 year after closure of ileostomy (n = 8; intact pouch I), >1 year after closure of ileostomy (n = 16; intact pouch II), in the case of pouchitis (n = 11), and in 11 controls. Tissues were mounted in a miniaturized Ussing chamber. Escherichia coli was added to the mucosal side of the Ussing chamber, and the permeation was proven by serosal presence of E. coli. Epithelial and subepithelial resistance was determined by transmural impedance analysis. Active Na-glucose cotransport and active Cl secretion were measured. Specimens were analyzed by fluorescent in situ hybridization with oligonucleotide probes targeting the bacterial 16s ribosomal RNA. The bacteria in and on the tissue were enumerated.

RESULTS

Bacterial permeation occurred in 2 of 13 pre-IPAA, 2 of 7 deviations, 0 of 8 intact pouch I, 9 of 16 intact pouch II, 5 of 11 pouchitis specimens, and 0 of 11 ileum controls. The frequency of bacterial permeation in the intact pouch II group is higher than in the intact pouch I group (P < 0.001). Epithelial resistance, mannitol fluxes, electrogenic chloride secretion, sodium-glucose cotransport of the bacterially permeated specimens versus nonpermeated of the intact pouch II group, and the pouchitis group and subepithelial resistance remained unchanged. Intramural bacteria could be detected by fluorescence in situ hybridization mainly in long-lasting pouches, but there was no correlation with bacterial permeation.

CONCLUSIONS

The long-lasting ileoanal pouch is associated with increased bacterial permeability. This is not correlated with a disturbed function of the pouch mucosa but could be a precursor of pouchitis.

N/A

N/A

Intraluminal injection of short chain fatty acids diminishes intestinal mucosa injury in experimental ischemia-reperfusion

PURPOSE: Investigated the effect of intraluminal short-chain fatty acids (SCFA) on the intestinal mucosa in the presence of ischemia-reperfusion injury (IRI). METHODS: Six blind sacs of the small bowel (3at the jejunum and 3 at the ileum) were created in ten Wistar rats. The lateral sacs of both bowel regions were subjected to IRI (15/15 minutes) while the medial sacs were let free to receive blood supply. In the lateral sacs, it was injected either a solution containing SCFA (butyrate, propionate and acetate) or pure saline at the bowel lumen. No fluid was injected in the medial sacs. RESULTS: Both at the jejunum and at the ileum the score of the mucosal injury was higher in saline than in control sacs. SCFA treated sacs showed lesser score at the ileum (p=0.03) but were not significantly different at the jejunum (p=0.83) when compared with saline sacs. It was found a significant greater number of neutrophils (p < 0.01) in the sacs treated with saline than in the other two sacs in both regions. CONCLUSION: SCFA protect the distal small bowel mucosa and diminishes infiltration of neutrophils to the gut lamina propria in IRI.

Prevention of bacterial translocation using beta-(1-3)-D-glucan in small bowel ischemia and reperfusion in rats

PURPOSE: To investigate the role of beta-(1-3)-D-glucan on 99mTc labelled Escherichia coli translocation and cytokines secretion in rats submitted to small bowel ischemia/reperfusion injury. METHODS: Five groups (n=10 each) of Wistar rats were subjected to control(C), sham(S), group IR subjected to 45 min of bowel ischemia/60 min of reperfusion(I/R), and group I/R+glucan subjected to 45 min of bowel ischemia/60 min of reperfusion(I/R) and injected with 2mg/Kg intramuscular. Translocation of labelled bacteria to mesenteric lymph nodes, liver, spleen, lung and serum was determined using radioactivity/count and colony forming units/g(CFU/g). Serum TNFalpha, IL-1beta, IL-6, IL-10 were measured by ELISA. RESULTS: CFU/g and radioactivity/count were higher in I/R than in I/R+glucan rats. In C, S and S+glucan groups, bacteria and radioactivity/count were rarely detected. The I/R+glucan rats had enhancement of IL-10 and suppressed production of serum TNFalpha, IL-1beta and, IL-6, compared to I/R untreated animals. CONCLUSION: The beta-(1-3)-D-glucan modulated the production of pro-inflammatory and anti-inflammatory cytokines during bowel ischemia/reperfusion, and attenuated translocation of labelled bacteria.

Amelioration of intestinal reperfusion injury by moderate hypothermia is associated with serum sICAM-1 levels

BACKGROUND

The aim of this study was to investigate the effects of moderate hypothermia on various serum markers involving in inflammation after intestinal ischemia-reperfusion (IR).

MATERIALS AND METHODS

The model of 30 min intestinal ischemia +90 min reperfusion was used. Three groups of rats were studied, n=7-8 per group: 1) sham at normothermia, 36.5 to 37.5 degrees C; 2) IR at normothermia and; 3) IR at moderate hypothermia, 32 to 33 degrees C. Serum levels of TNF-alpha, lipopolysaccharide-inducible CXC chemokine (LIX), and soluble intercellular adhesion molecule-1 (sICAM-1) were determined using ELISA technique. Histological features of terminal ileum were also graded.

RESULTS

Intestinal IR at normothermia caused remarkable tissue injury together with an elevation in serum TNF-alpha, LIX, and sICAM-1 levels. Moderate hypothermia significantly decreased the degree of mucosal damage and attenuated the elevation of serum sICAM-1 levels. However, there were no significant differences in serum TNF-alpha and LIX levels between IR at normothermia and IR at hypothermia.

CONCLUSIONS

Intestinal IR at normothermia induces the elevation of serum TNF-alpha, LIX, and sICAM-1 levels. Moderate hypothermia protects the small intestine from reperfusion injury. This beneficial effect is associated with serum sICAM-1 levels but not with serum TNF-alpha and LIX levels. We speculate that one of the mechanisms, by which hypothermia blunts the tissue injury, is at the step of firm adhesion between leukocytes and endothelial cells.

Effects of Early Versus Delayed Nutrition on Intestinal Mucosal Apoptosis and Atrophy After Traumatic Brain Injury

PURPOSE

To determine the optimal time to start nutritional support after traumatic brain injury (TBI).

METHODS

Rats were divided into six groups of seven. All but one of these groups were subjected to moderate closed head trauma under general anesthesia. Groups Ia and Ib were commenced on immunonutrition and standard enteral nutrition, respectively, 8 h later; groups IIa and IIb were commenced on immunonutrition and standard enteral nutrition, respectively, 72 h later; and group III was commenced on a parenteral saline infusion 8 h later. Group IV was a control group fed a laboratory diet and not subjected to trauma. The rats were killed 7 days later, and ileal segments were examined using light and electron microscopy. We used the deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) technique to detect intestinal mucosal apoptosis.

RESULTS

Group III had a lower body weight than the other groups (P < 0.005). The mean villous height was highest in groups Ia and IV and lowest in group III. The villi count was lower in groups Ib, IIa, IIb, and III than in group IV (P < 0.005). The apoptotic index counts were higher in groups IIa, IIb, and III than in group IV (P < 0.005).

CONCLUSIONS

The addition of enriching immunonutrients to early enteral feeding helps preserve an almost normal gut mucosa.

The value of plasma cytokine measurement for the detection of strangulation in patients with bowel obstruction: a prospective, pilot study

PURPOSE

The aim of this prospective blinded study was to examine whether measurement of plasma cytokines is a predictor of strangulation in patients with bowel obstruction.

METHODS

Seventy-seven consecutive patients diagnosed with bowel obstruction were included. Blood samples were obtained at enrollment in all patients and at surgery (immediately before operation) if patients required surgery.

RESULTS

Forty-three patients were managed conservatively (group 1) and 34 patients required surgery, of whom 20 had no bowel strangulation (group 2) and 14 had bowel strangulation (group 3). The mean plasma interleukin (IL)-6 levels at enrollment were significantly higher in group 3 (107.8 pg/ml) than in groups 1 (11.3 pg/ml, P < 0.0001 vs. group 3) and 2 (23.6 pg/ml, P < 0.0001 vs. group 3). The sensitivity and specificity of plasma IL-6 level (> or = 40 pg/ml) in predicting strangulation were 86 percent (95 percent confidence interval, 60-97 percent) and 86 percent (95 percent confidence interval, 80-88 percent), respectively. The plasma IL-6 levels at surgery significantly increased compared to those at enrollment (from 107.8 pg/ml to 205.8 pg/ml, P = 0.0003) in group 3, however, they did not increase significantly in group 2. Among other clinical and laboratory parameters, plasma lactic acid levels (> or = 15 mg/dl) at enrollment were significantly associated with strangulation. In the multivariate analysis, both plasma IL-6 (</> or = 40 pg/ml) and lactic acid (</> or =15 mg/dl) levels at enrollment were significant predictive factors for strangulation. IL-1beta and tumor necrosis factor-alpha were not detected in the plasma of most patients during the study.

CONCLUSION

Plasma IL-6 measurement might be an additional diagnostic tool that can predict strangulation in patients with bowel obstruction.

Expressions of intestinal NF-kappaB, TNF-alpha, and IL-6 following traumatic brain injury in rats

BACKGROUND

NF-kappaB regulates a large number of genes involved in the inflammatory response to critical illness, but it is not well known if and how NF-kappaB is activated in the gut following traumatic brain injury (TBI) and what is the role of cytokine-mediated inflammation in the pathogenesis of acute gut mucosal injury.

MATERIALS AND METHODS

Male Wistar rats were randomly divided into control and TBI groups, each of which was subgrouped at hours 3, 12, 24, and 72 and on day 7. Parietal brain contusion was produced by a free-falling weight on the exposed dura of the right parietal lobe. NF-kappaB binding activity in jejunal tissue was measured using EMSA and the concentrations of TNF-alpha and IL-6 were detected using ELISA.

RESULTS

NF-kappaB binding activity in the jejunum was significantly increased at 3 h following TBI, was maximal at 72 h, and remained elevated by 7 days postinjury. TNF-alpha and IL-6 concentrations were also significantly increased by 3 h postinjury, but peaked at 24 h and remained elevated on Day 7 postinjury.

CONCLUSIONS

TBI induced a rapid and persistent up-regulation of NF-kappaB and proinflammatory cytokines in the gut, which may play an important role in the pathogenesis of acute gut mucosal injury mediated by inflammation.

Persistent HIF-1alpha activation in gut ischemia/reperfusion injury: potential role of bacteria and lipopolysaccharide

In both animal models of hemorrhagic shock and clinical settings, shock-induced gut ischemia has been implicated in the development of the systemic inflammatory response syndrome and distant organ injury, yet the factors transducing these events remain to be fully determined. Because hypoxia-inducible factor (HIF-1), a transcription factor composed of oxygen-labile HIF-1alpha and constitutive HIF-1beta subunits, regulates the physiologic/pathophysiologic response to hypoxia and ischemia, we examined the HIF-1 response in two rat models of gut ischemia-reperfusion. We found that ileal nuclear HIF-1alpha protein levels were induced in rats subjected to trauma (laparotomy) plus hemorrhagic shock for 90 min relative to their trauma sham-shock and naïve counterparts and that this trauma hemorrhagic shock-induced mucosal HIF-1alpha protein response persisted after 1 h and 3 h of reperfusion. Likewise, in a model of isolated gut ischemia-reperfusion injury, where the superior mesenteric artery was occluded for 45 min, nuclear HIF-1alpha were induced in the gut mucosa relative to their sham counterparts and persisted after 1 h and 3 h or reperfusion. Similar to the in vivo response, in vitro hypoxia induced HIF-alpha expression in three different enterocyte cell lines (rat IEC-6 and human Caco-2 and HT-29 cell lines). However, in contrast to the in vivo response, HIF-1 expression rapidly disappeared on subsequent reoxygenation. Because in vivo enterocytes are exposed to bacteria, we tested whether the in vitro HIF-1alpha response would persist on reoxygenation if the enterocytes were cocultured with bacteria. P. aeruginosa, an enteric bacterium, markedly induced enterocyte HIF-1alpha protein levels under normoxic conditions. Furthermore, the addition of P. aeruginosa during either the hypoxic or reoxygenation phase prevented the degradation of HIF-1alpha protein levels. Moreover, the observation that lipopolysaccharide induced HIF-1alpha expression in a time-dependent manner in IEC-6 cells indicated that the induction of HIF-1 by exposure to P. aeruginosa is not dependent on bacterial viability. In conclusion, these results suggest that HIF-1alpha activation is an early reperfusion-independent event in models of gut ischemia-reperfusion and that this HIF-1alpha response is potentiated by the presence of P. aeruginosa or lipopolysaccharide.

Up-regulation of intestinal nuclear factor kappa B and intercellular adhesion molecule-1 following traumatic brain injury in rats

AIM: Nuclear factor kappa B (NF-κB) regulates a large number of genes involved in the inflammatory response to critical illnesses, but it is not known if and how NF-κB is activated and intercellular adhesion molecule-1 (ICAM-1) expressed in the gut following traumatic brain injury (TBI). The aim of current study was to investigate the temporal pattern of intestinal NF-κB activation and ICAM-1 expression following TBI.

METHODS: Male Wistar rats were randomly divided into six groups (6 rats in each group) including controls with sham operation and TBI groups at hours 3, 12, 24, and 72, and on d 7. Parietal brain contusion was adopted using weight-dropping method. All rats were decapitated at corresponding time point and mid-jejunum samples were taken. NF-κB binding activity in jejunal tissue was measured using EMSA. Immunohistochemistry was used for detection of ICAM-1 expression in jejunal samples.

RESULTS: There was a very low NF-κB binding activity and little ICAM-1 expression in the gut of control rats after sham surgery. NF-κB binding activity in jejunum significantly increased by 160% at 3 h following TBI (P<0.05 vs control), peaked at 72 h (500% increase) and remained elevated on d 7 post-injury by 390% increase. Compared to controls, ICAM-1 was significantly up-regulated on the endothelia of microvessels in villous interstitium and lamina propria by 24 h following TBI and maximally expressed at 72 h post-injury (P<0.001). The endothelial ICAM-1 immunoreactivity in jejunal mucosa still remained strong on d 7 post-injury. The peak of NF-κB activation and endothelial ICAM-1 expression coincided in time with the period during which secondary mucosal injury of the gut was also at their culmination following TBI.

CONCLUSION: TBI could induce an immediate and persistent up-regulation of NF-κB activity and subsequent up-regulation of ICAM-1 expression in the intestine. Inflammatory response mediated by increased NF-κB activation and ICAM-1 expression may play an important role in the pathogenesis of acute gut mucosal injury following TBI.

L-arginine administration ameliorates serum and pulmonary cytokine response after gut ischemia-reperfusion in immature rats

AIM: Small intestinal ischemia-reperfusion (IR) has been demonstrated to result in both local mucosal injury and systemic injuries. The exact role of nitric oxide (NO) in intestinal IR is unclear. We propose that NO and some other cytokines change in the reperfusion period and these changes are associated with lung injury. The aim of this study was to determine the effect of supplementing NO substrate, L-arginine (L-arg), on serum and pulmonary cytokine production during small intestinal IR in immature rats.

METHODS: Immature rats underwent 60 min. of superior mesenteric artery occlusion followed by 90 min of reperfusion. L-arg (250 mg/kg) was given intravenously to the experimental group (IR+L-arg) which received L-arg after 45 min of intestinal ischemia. Serum and lung endothelin-1 (ET-1), NO, malondialdehyde (MDA), and tumor necrosis factor α (TNFα) were measured. Sham operation (SHAM) and intestinal IR (IR) groups were performed as control. The lavage fluid of the lung was collected by bronchoalveolar lavage (BAL) and white blood cells and polymorphonuclear cells (PMNs) were immediately counted to identify lung damage.

RESULTS: When L-arg was given during small intestinal IR, serum NO concentration increased significantly in IR+L-arg group (162.17±42.93 μmol/L) when compared with IR group (87.57±23.17 μmol/L, t = 3.190, P = 0.008<0.01). Serum MDA reduced significantly in IR+L-arg group (8.93±1.50 nmol/L) when compared with SHAM (23.78±7.81 nmol/L, t = 3.243, P = 0.007<0.01) and IR (25.54±9.32 nmol/L, t = 3.421, P = 0.006<0.01). ET-1 level in lung tissues was significantly lower in IR+L-arg group (13.81±7.84 pg/mL) than that in SHAM (35.52±10.82 pg/mL, t = 2.571, P = 0.03<0.05) and IR (50.83±22.05 pg/mL, t = 3.025, P = 0.009<0.01) groups. MDA contents in lung tissues were significantly lower in IR+L-arg group (10.73±1.99 nmol/L) than in SHAM (16.62±2.28 nmol/L, t = 3.280, P = 0.007<0.01) and IR (21.90±4.82 nmol/L, t = 3.322, P = 0.007<0.01) groups. Serum and lung TNFα concentrations were not significantly different in three groups. NO contents in lung homogenates and white blood cell counts in BAL had no significant difference in three groups; but the percentage of PMNs in BAL was 13.50±8.92, 33.20±16.59, and 22.50±6.09 in SHAM, IR, and IR+L-arg groups, respectively.

CONCLUSION: Small intestinal IR induced increases of pulmonary neutrophil infiltration in immature rats. Neutrophil infiltration in lung tissues was reduced by L-arg administration but remained higher than in SHAM group. L-arg administration during intestinal IR enhances serum NO production, reduces serum MDA and lung ET-1 and MDA levels, resulting in the improvement of systemic endothelial function. L-arg supplementation before reperfusion may act as a useful clinical adjunct in the management of intestinal IR, thus preventing the development of adult respiratory distress syndrome, even multiple organ dysfunction syndrome (MODS).

Failure of the gut barrier system enhances liver injury in rats: protection of hepatocytes by gut-derived hepatocyte growth factor

OBJECTIVE

Clinical and experimental studies suggest that impairment of the mucosal barrier system increases gut-derived endotoxin in the portal blood, which causes liver injury. The aim of this study was to elucidate the mechanism of liver injury caused by gut defence failure.

DESIGN

Wistar rats were administered either enteral lipopolysaccharide (LPS) or LPS via the portal vein.

METHODS

Blood samples were collected via the inferior vena cava at necropsy. Serum aspartate transaminase (AST) and alanine transaminase (ALT) were analysed by standard enzymatic procedures and cytokines [tumour necrosis factor-alpha, interleukin (IL)-1beta, interferon-gamma, IL-6 and hepatocyte growth factor (HGF)] were measured by enzyme-linked immunosorbent assay. Livers were removed and snap-frozen in liquid nitrogen. CD14, CD68, Toll-like receptor (TLR) 2, TLR4 and Fas ligand (FasL) were analysed immunohistochemically. Expression of TLR2, TLR4 and CD14 mRNA was determined by reverse transcriptase-polymerase chain reaction.

RESULTS

In enterally-treated rats, AST and ALT were not increased and cytokine levels were under the limits of detection in the absence of a rise in HGF. Enteral administration of LPS increased HGF dose-dependently. Injection of LPS in the portal vein resulted in significant increases in AST, ALT, tumour necrosis factor-alpha, IL-1beta, interferon-gamma and IL-6 levels, but no change in HGF levels. Immunohistochemical analysis revealed that intraportal LPS administration increased CD14, TLR4, CD68 and FasL. Reverse transcriptase-polymerase chain reaction analysis demonstrated that TLR4 mRNA expression was upregulated 0.5 h after intraportal LPS administration.

CONCLUSION

s Our data suggest that Kupffer cell activation mediated by intraportal LPS via TLR4 is involved in liver injury, possibly through both tumour necrosis factor-alpha/IL-1beta and FasL, and that lack of HGF activity in the impaired gut could not counteract liver injury.

Infarcted intestine: a diagnostic void

The diagnostic approaches to infarction of the small intestine are reviewed in the present paper. The inadequacy of current methods, especially biochemical methods, are highlighted. Additionally, the benefits of a sensitive and specific test of intestinal infarction are discussed.

Translocation of 99mTc labelled bacteria after intestinal ischemia and reperfusion

PURPOSE: Ischemia and reperfusion of the small intestine disrupts gut barrier, causes bacterial translocation and activates inflammatory responses. An experimental study was planned to evaluate if 99mTc labelled Escherichia coli translocates to mesenteric lymph nodes, liver, spleen, lung and serum of rats submitted to mesenteric ischemia/reperfusion. Additionally, it was observed if the time of reperfusion influences the level of translocation. METHODS: Forty male Wistar rats underwent 45 minutes of gut ischemia by occlusion of the superior mesenteric artery. The translocation of labelled bacteria to different organs and portal serum was determined in rats reperfused for 30 minutes, 24 hours, sham(S) and controls(C), using radioactivity count and colony forming units/g (CFU). RESULTS: All the organs from rats observed for 24 hours after reperfusion had higher levels of radioactivity and positive cultures (CFU) than did the organs of rats reperfused for 30 minutes, C and S, except in the spleen (p<0,01). CONCLUSION: The results of this study indicated that intestinal ischemia/reperfusion led to bacterial translocation, mostly after 24 hours of reperfusion.

Protection against ischemia/reperfusion injury by the cavitary two-layer method in canine small intestinal transplantation with reduction of reactive oxygen species

BACKGROUND

Ischemia and reperfusion (I/R) injury is a major determinant of early graft dysfunction and long-term graft survival in small intestinal transplantation. The cavitary two-layer method (TLM) has been reported to be superior to the University of Wisconsin cold storage method (UWM) in long-term preservation of canine small intestine. This study was designed to evaluate the protective effect of the cavitary TLM against I/R injury in canine small intestinal transplantation.

METHODS

Intestinal grafts harvested from beagles were allotransplanted after 24-hour preservation by UWM (group 1) or the cavitary TLM (group 2). The graft in the controls (group 3) was immediately allotransplanted without preservation. I/R injury was assessed by functional success rates, biochemical assay, graft adenosine triphosphate (ATP) and lipid peroxidation (LPO) concentrations, and histopathologic examination including TUNEL staining for apoptosis.

RESULTS

In group 1, ATP recovery was delayed after reperfusion, and most recipients died with hemorrhage of the grafts and lungs. In group 2, graft ATP concentrations recovered rapidly, and I/R injury was prevented with reduced LPO production, resulting in good outcome.

CONCLUSIONS

The cavitary TLM protected intestinal grafts against I/R injury evidenced by maintenance of graft ATP levels and reduction of LPO production compared with UWM in canine small intestinal transplantation.

Arginine vasopressin compromises gut mucosal microcirculation in septic rats

OBJECTIVE

Arginine vasopressin (AVP) is increasingly used in the therapy of septic patients with hypotension. However, its effects on the microvascular networks have not been studied in detail. This study was designed to determine the effects of AVP infusion on the villus microcirculation of the septic rat ileum.

DESIGN

Prospective, placebo-controlled, randomized, single-blinded trial.

SETTING

University research laboratory.

SUBJECTS

Fifteen male Sprague-Dawley rats.

INTERVENTIONS

Twenty-four hours after cecal ligation and perforation to create sepsis (M1), rats (n = 8) received a continuous AVP infusion to increase mean arterial pressure by 20 mm Hg (M2) and 40 mm Hg (M3) from M1. In the control group (n = 7), an equivalent volume of normal saline was infused.

MEASUREMENTS AND MAIN RESULTS

Videomicroscopy was performed on 6-10 villi of ileum mucosa at M1 and was repeated at M2 and M3. Blood was drawn to determine plasma levels of AVP and interleukin-6. At M1, both study groups were hypotensive compared with preseptic data (mean arterial pressure, -25%). The increase in mean arterial pressure was linked to supraphysiologic AVP plasma levels and was accompanied by a decrease in mean mucosal blood flow by 76% at M2 and 81% at M3 (p <.001 vs. control). Red blood cell velocity fell by 45% and 47%, respectively (p <.05 vs. control). Whereas periods of arrested villus blood flow increased from 8.1 +/- 2.6 secs/min to 43.8 +/- 5.2 and 47 +/- 6.2 secs/min at M2 and M3 (p <.001), the diameter of terminal arterioles remained unchanged. In addition, AVP infusion further augmented the sepsis-associated increase in interleukin-6 levels (AVP, 905 +/- 160 vs. control, 638 +/- 55 pg/mL; p =.022).

CONCLUSIONS

This study provides evidence for severe abnormalities in gut mucosal blood flow after AVP infusion in septic rats, accompanied by an augmented inflammatory response to the septic injury. The effects of AVP on microvascular blood flow in this model may be related to AVP activities on larger arterioles (>40 microm), a concomitant reduction in cardiac output, or even both.

Glutamine: recent developments in research on the clinical significance of glutamine

PURPOSE OF REVIEW

The aim of this review is to describe the clinical relevance of supplementation of glutamine from the recent literature. First, new basic research is examined and subsequently recent clinical trials and a metaanalysis are illustrated.

RECENT FINDINGS

Glutamine has a major impact on the functionality of the immune system. It has recently been established that glutamine not only has a protective effect on cells of the immune system, but also on other cells of the body, for instance cardiomyocytes. Evidence is accumulating for an effect of glutamine via glutathione, heat shock proteins as well as taurine. Another area of interest is the way glutamine enhances gut barrier function. More and more research is concentrating on the positive effect of glutamine on the gut-associated lymphoid tissue.

SUMMARY

Based on a recent meta-analysis and up-to-date clinical trials, we may conclude that glutamine has a beneficial effect on infectious complications and reduces hospital stay. In critically ill patients glutamine supplementation may reduce morbidity and mortality. The greatest effect was observed in patients receiving high dose parenteral glutamine. A recent study with high dose enteral glutamine demonstrated a reduced mortality in the glutamine supplemented group. In the future more trials with larger numbers of participants are needed, especially with high dose enteral glutamine in the perioperatively and the intensive care unit setting.

Alterations of intestinal mucosa structure and barrier function following traumatic brain injury in rats

AIM: Gastrointestinal dysfunction is a common complication in patients with traumatic brain injury (TBI). However, the effect of traumatic brain injury on intestinal mucosa has not been studied previously. The aim of the current study was to explore the alterations of intestinal mucosa morphology and barrier function, and to determine how rapidly the impairment of gut barrier function occurs and how long it persists following traumatic brain injury.

METHODS: Male Wistar rats were randomly divided into six groups (6 rats each group) including controls without brain injury and traumatic brain injury groups at hours 3, 12, 24, and 72, and on day 7. The intestinal mucosa structure was detected by histopathological examination and electron microscopy. Gut barrier dysfunction was evaluated by detecting serum endotoxin and intestinal permeability. The level of serum endotoxin and intestinal permeability was measured by using chromogenic limulus amebocyte lysate and lactulose/mannitol (L/M) ratio, respectively.

RESULTS: After traumatic brain injury, the histopathological alterations of gut mucosa occurred rapidly as early as 3 hours and progressed to a serious state, including shedding of epithelial cells, fracture of villi, focal ulcer, fusion of adjacent villi, dilation of central chyle duct, mucosal atrophy, and vascular dilation, congestion and edema in the villous interstitium and lamina propria. Apoptosis of epithelial cells, fracture and sparseness of microvilli, loss of tight junction between enterocytes, damage of mitochondria and endoplasm, were found by electron microscopy. The villous height, crypt depth and surface area in jejunum decreased progressively with the time of brain injury. As compared with that of control group (183.7 ± 41.8 EU/L), serum endotoxin level was significantly increased at 3, 12, and 24 hours following TBI (434.8 ± 54.9 EU/L, 324.2 ± 61.7 EU/L and 303.3 ± 60.2 EU/L, respectively), and peaked at 72 hours (560.5 ± 76.2 EU/L), then declined on day 7 (306.7 ± 62.4 EU/L, P < 0.01). Two peaks of serum endotoxin level were found at hours 3 and 72 following TBI. L/M ratio was also significantly higher in TBI groups than that in control group (control, 0.0172 ± 0.0009; 12 h, 0.0303 ± 0.0013; 24 h, 0.0354 ± 0.0025; 72 h, 0.0736 ± 0.0105; 7 d, 0.0588 ± 0.0083; P < 0.01).

CONCLUSION: Traumatic brain injury can induce significant damages of gut structure and impairment of barrier function which occur rapidly as early as 3 hours following brain injury and lasts for more than 7 days with marked mucosal atrophy.

Effects of the anti-ICAM-1 monoclonal antibody, allopurinol, and methylene blue on intestinal reperfusion injury

PURPOSE

The aim of this study was to evaluate the effect of allopurinol, methylene blue, and a monoclonal antibody to the adhesion molecule ICAM-1 in intestinal ischemia and reperfusion injury.

METHODS

The rats were divided into 5 groups. CG (n = 8) was untreated controls, SISG (n = 11) received sterile isotonic saline solution, ICAMG (n = 12) received a monoclonal antibody to rat ICAM-1, ALLOG (n = 12) received allopurinol, and MBG (n = 14) received methylene blue. Intestinal ischemia was performed for 60 minutes followed by 60 minutes of reperfusion. The agents were injected 10 minutes before the reperfusion to animals. After 60 minutes of reperfusion, the plasma samples for myeloperoxidase (MPO) activity, tumor necrosis factor alpha (TNF-alpha) and uric acid levels, and the intestinal biopsies of ileum and jejunum for histopathologic examination were taken.

RESULTS

The mucosal damage was attenuated, and TNF-alpha level significantly decreased in ALLOG and ICAMG compared with SISG. The MPO activity was the lowest in ICAMG, and uric acid level was significantly decreased in ALLOG compared with the other groups. Methylene blue decreased TNF-alpha response to reperfusion injury but significantly increased the grade of the mucosal damage and the MPO activity.

CONCLUSIONS

This study shows that prereperfusion application of allopurinol and monoclonal antibody to the adhesion molecule ICAM-1 may attenuate the damage caused by intestinal ischemia and reperfusion, but the different time-points for application, the effects observed in the different ischemia and reperfusion durations, and the long-term results also should be investigated in the same experimental model before the final conclusion. Methylene blue was not effective to prevent or attenuate the intestinal tissue injury, but because this was the first study examining the effect of methylene blue on intestinal reperfusion injury, further studies with the different doses, ischemic duration, and application times will be needed.

Splenectomy attenuates intestinal ischemia-reperfusion-induced acute lung injury

BACKGROUND/PURPOSE

Intestinal ischemia-reperfusion (IIR) induced acute lung injury (ALI) has been documented. Kupffer cell blockage with gadolinium chloride (GdCl(3)) has been shown to attenuate IIR-induced ALI. However, the effects of splenic monocytes/macrophages on IIR-induced ALI has not been studied previously. In the current study, the authors aimed to investigate the role of splenectomy in IIR-induced ALI.

METHODS

Forty-eight rats were divided randomly into 6 groups as follows: SHAM, SHAM + KCB, SHAM + SPLN, IIR, IIR + KCB, IIR + SPLN. Two hours of ischemia and 1 hour of reperfusion has been applied by clipping the SMA. GdCl3 was given 24 hours before experiment. Splenectomy was done just before SMA clipping. Lung levels of tumor necrosis-factor (TNF), interleukin (IL)-6, myeloperoxidase (MPO), and malondialdehyde (MDA) were assayed biochemically. Lung leukosequestration was determined by counting PMNLs histologically. Kruskal-Wallis and Mann-Whitney U tests were done; P values less than.003 were considered significant.

RESULTS

Polimorphonuclear leukocyte (PMNL) counts and biochemical parameters in the IIR group were significantly higher than the other groups (P <.003). When compared with IIR group, PMNL counts and biochemical parameters were significantly decreased in the IIR+KCB and IIR+SPLN groups, respectively (P <.003). However, they were still significantly higher than their sham-operated controls (P <.003).

CONCLUSIONS

This study documents that splenectomy attenuates ALI as well as Kupffer cell blockage. Spleen, an important component of mononuclear phagocytic system as liver Kupffer cells, might play an important role in the IIR-induced ALI.

The Abdominal Compartment Syndrome as a Second Insult During Systemic Neutrophil Priming Provokes Multiple Organ Injury

In our recent clinical study of damage control laparotomy, the abdominal compartment syndrome (ACS) emerged as an independent risk factor for postinjury multiple organ failure (MOF). We and others have shown previously that the ACS promotes the systemic production of proinflammatory cytokines. Our study objective was to develop a clinically relevant two-event animal model of postinjury MOF using the ACS as a second insult during systemic neutrophil priming to provoke organ dysfunction. Male adult rats underwent hemorrhagic shock (30 mmHg x 45 min) and were resuscitated with crystalloids and shed blood. The timing of postshock systemic neutrophil (PMN) priming was determined by the surface expression of CD11b via flow cytometry. Finding maximal PMN priming at 8 h, but no priming at 2 h (early) and 18 h (late), the ACS (25 mmHg x 60 min) was introduced at these time points. At 24 h postshock, lung injury was assessed by lung elastase concentration and Evans blue dye extravasation in bronchoalveolar lavage. Liver and renal injuries were determined by serum alanine aminotransferase, serum creatinine, and blood urea nitrogen. The ACS during the time of maximal systemic PMN priming (8 h) provoked lung and liver injury, but did not if introduced at 2 or 18 h postshock when there was no evidence of systemic PMN priming. The 24-h mortality of this two-event model was 33%. These findings corroborate the potential for the ACS to promote multiple organ injury when occurring at the time of systemic PMN priming. This clinically relevant two-event animal model of PMN organ injury may be useful in elucidating therapy strategies to prevent postinjury MOF.

Pathogenesis of neonatal necrotizing enterocolitis: a study of the role of intraluminal pressure, age and bacterial concentration

The pathogenesis of neonatal necrotizing enterocolitis (NEC) is unknown. Intestinal dilatation and preferred occurrence of NEC at sites of bacterial overgrowth (colon and ileum) are common findings. The study attempted to produce NEC with increasing intraluminal pressures and bacterial concentrations in two different aged groups of rats. First, 10-cm terminal ileum segments were isolated with intact vascular pedicles in 1-and 3-month-old rats, and a dose of 10(11) E. coli in 1 ml was injected into each segment. Intraluminal pressure was sustained for 1 h at 150, 100, 50 and 0 cmH(2)0, respectively, in four experimental groups ( n=6). The isolated loop was then returned to the abdominal cavity and assessed grossly for NEC after 24 h. Histological examination was performed by a pathologist (KWC) who was blinded to the procedures. Second, the procedure was repeated with doses of 10(8), 10(5) and 0 bacteria/ml ( n=6) at intraluminal pressure of 100 cmH(2)0 in 1-month-old rats. Third, in another experimental group, oxygenation of the pedicled loop was assessed by oximetry as the intraluminal pressure increased and the findings were correlated with aortic blood pressure. The blood pressures (mean+/-SD) for 3- and 1-month-old rats were 110+/-6 and 72+/-4 mmHg, respectively. Hypoxia (<50% oxygen saturation) of the bowel was detected when the intraluminal pressure exceeded the mean blood pressure. The relative incidences of NEC in the bowel with intraluminal pressure above and below mean blood pressure were 100% (6/6) vs. 4% (1/24; P<0.05) in 3-month-old rats, and 100% (12/12) vs. 11% (2/18; P<0.05) in 1-month-old rats. There was no occurrence of NEC in bowel injected with 10(5) E. coli/ml and less at 100 cm intraluminal pressure. Increased intraluminal pressure results in bowel hypoxia and in the presence of adequate bacterial concentration predisposes to the development of NEC. Young age is associated with a lower threshold for increased intraluminal pressure leading to NEC.

Trauma care in Germany

Trauma Care in Germany fulfils all requirements to deal with injured young and mobile individuals as well as with an increasing number of injured elderly patient. Furthermore, it is prepared to cope with mass casualties of injured. As a public task the Trauma System in Germany is well organized and follows clear cut demands. To perform technical and medical therapy at highest available level as soon as possible, a ground system of physician staffed ambulances is supported by a network of physician-staffed HEMS all over Germany. Therefore, enormous efforts in financing, basic research and quality management have been undertaken during recent years to create such a sophisticated rescue system.

Protection against experimental small intestinal ischaemia-reperfusion injury with oxygenated perfluorochemical

BACKGROUND

Intestinal ischaemia-reperfusion (IR) injury frequently occurs in abdominal surgery. Perfluorochemical (PFC) can be used to oxygenate intestinal organs directly and allows adenosine 5'-triphosphate (ATP) production within the submerged organs during ischaemia. This study was designed to evaluate the protective effect of PFC in IR injury, focusing on cytokine production in rat small intestine.

METHODS

The superior mesenteric artery was occluded in rats for 60 min and the small bowel placed in an intestinal bag containing either normal saline (group 1), oxygenated saline (group 2) or oxygenated PFC (group 3). The arterial clip was subsequently removed, allowing reperfusion. The number of rats that survived for 7 days, tissue ATP levels, biochemical variables, tissue lipid peroxidation (LPO), bacterial cultures and histological changes were examined after reperfusion.

RESULTS

The use of oxygenated PFC in group 3 improved survival compared with the other groups. Serum creatine phosphokinase and lactate dehydrogenase levels in groups 1 and 2 reflected small intestinal damage, and plasma levels of tumour necrosis factor alpha and interleukin 6 were raised. In contrast, oxygenated PFC decreased these levels, and reduced LPO, bacterial translocation and augmented apoptosis of the small intestine after reperfusion.

CONCLUSION

An intestinal bag containing oxygenated PFC showed protective effects during bowel ischaemia.

Role for complement in mediating intestinal nitric oxide synthase-2 and superoxide dismutase expression

Inducible nitric oxide synthase (iNOS) and superoxide dismutase (SOD) play an important role in the pathology of ischemia-reperfusion. This study sought to determine if the proinflammatory effects of complement modulate iNOS and SOD in the rat after gastrointestinal ischemia and reperfusion (GI/R). An inhibitory or noninhibitory anti-complement component 5 (C5) monoclonal antibody (18A or 16C, respectively) was administered before GI/R. RT-PCR revealed a significant increase in intestinal iNOS mRNA compared with sham after GI/R that was attenuated significantly by 18A. Immunohistochemistry demonstrated increased iNOS protein expression within the intestinal crypts after GI/R. Cu/Zn SOD (mRNA and protein) was unaffected by GI/R, whereas Cu/Zn SOD activity was reduced significantly. Mn SOD protein expression was decreased significantly by GI/R. Anti-C5 preserved Cu/Zn SOD activity and Mn SOD protein expression. Staining for nitrotyrosine showed that anti-C5 treatment reduced protein nitration in the reperfused intestine. Immunohistochemistry demonstrated prominent phosphorylated (p) inhibitory factor-kappaB (IkappaB)-alpha staining of intestinal tissue after GI/R, whereas anti-C5 reduced p-IkappaB-alpha expression. These data indicate that complement may mediate tissue damage during GI/R by increasing intestinal iNOS and decreasing the activity and protein levels of Cu/Zn SOD and Mn SOD, respectively.

Benefits of intraluminal injection of glutamine for intestinal mucosa during ischemia-reperfusion

BACKGROUND

We investigated the effect of intraluminal glutamine on the intestinal mucosa in the presence of ischemia-reperfusion injury (IRI).

METHODS

Six blind sacs were created in the small bowel (3 at the jejunum and 3 at the ileum) in 10 Wistar rats. The lateral sacs of both bowel regions were submitted to IRI (30/30 min), while the medial sacs were left free to receive blood supply. In the lateral sacs, a solution containing either saline plus 4% glutamine or pure saline was injected at the bowel lumen. No fluid was injected in the medial sacs.

RESULTS

Both at the jejunum and at the ileum, the score of the mucosal injury was higher in saline-injected sacs than in either glutamine-injected or control sacs. There was a significantly greater number of neutrophils in the sacs treated with saline than in the other two groups of sacs.

CONCLUSION

Glutamine protects the mucosa and diminishes the accumulation of neutrophils at the lamina propria of the small bowel in IRI.

Pulmonary transplantation: the role of brain death in donor lung injury

The paucity of suitable lung donors and the high early mortality as the result of primary graft failure remain major challenges in pulmonary transplantation. There is evidence that the lung is injured in the donor by the process of brain death and often is made unusable or fails posttransplantation after amplification of the injury by the process of ischemia-reperfusion. An understanding of the mechanism of donor lung injury could lead to the development of new treatment strategies for the donor to reduce lung injury, increase the number of donors with acceptable lungs, and improve the results of transplantation. The pathophysiology of brain death is complex and involves sympathetic, hemodynamic, and inflammatory mechanisms that can injure the lung. The literature is reviewed, and these mechanisms are discussed together with their possible interrelations.

Sepsis from Pseudomonas aeruginosa pneumonia decreases intestinal proliferation and induces gut epithelial cell cycle arrest

OBJECTIVES

To evaluate whether the up-regulation in sepsis-induced gut epithelial apoptosis is balanced by an increase in intestinal proliferation and to assess mechanisms affecting the gut's regenerative response to overwhelming infection.

DESIGN

Prospective, randomized, controlled study.

SETTING

Animal laboratory in a university medical center.

INTERVENTIONS

Mice were subjected to intratracheal injection of Pseudomonas aeruginosa and killed between 1.5 and 24 hrs after induction of pneumonia-induced sepsis to assess for gut epithelial proliferation and cell division and for apoptosis. Animals were compared with sham-operation controls, septic transgenic mice that overexpress Bcl-2 throughout their small intestinal epithelium, and septic p53-/- mice.

MEASUREMENTS AND MAIN RESULTS

Proliferation and cell division were assessed by measuring S-phase and M-phase cells in intestinal crypts. The number of S-phase cells showed a progressive decline at all time points measured, with a 5-fold decrease in proliferation between control animals and septic mice 24 hrs after intratracheal injection of pathogenic bacteria (p <.0001). In contrast, cells in M-phase remained constant for the first 12 hrs after the onset of sepsis, but increased nearly 50% at 24 hrs after instillation of P. aeruginosa (p <.005). Both the decrease in S-phase cells and the increase in M-phase cells were partially suppressible in Bcl-2 overexpressors, but cellular proliferation and division were similar between septic p53-/- and p53+/+ mice. Crypt apoptosis was increased at all time points, with maximal death occurring between 12 and 24 hrs.

CONCLUSIONS

Sepsis from P. aeruginosa pneumonia induces a p53-independent decrease in gut epithelial proliferation. Despite an increase in sepsis-induced intestinal apoptosis, there is no compensatory increase in intestinal epithelial proliferation, and there is evidence of a cell cycle block with an accumulation of cells in M-phase. Decreasing gut apoptosis by overexpression of Bcl-2 is associated with a partial reversal of the effect of sepsis on the cell cycle.

Local intravascular coagulation and fibrin deposition on intestinal ischemia-reperfusion in rats

BACKGROUND

This study investigates intravascular coagulation and thrombotic obstruction in the splanchnic vasculature after intestinal ischemia in relation to epithelial integrity and function.

METHODS

Intestinal ischemia was induced in rats by superior mesenteric artery occlusion for 20 or 40 minutes. Intestinal injury was assessed by histologic analysis, biochemical markers, and functional studies. During reperfusion, portal and systemic blood samples were collected to analyze activation of coagulation and fibrinolysis.

RESULTS

Superior mesenteric artery occlusion resulted in mild to moderate intestinal injury. Twenty and 40 minutes of ischemia and 3 hours of reperfusion resulted in local intestinal thrombin generation and conversion of fibrinogen to fibrin, reflected by 3- and 4-fold increases in thrombin-antithrombin complex levels and a 3-fold elevation of fibrin degradation products (D-dimer), respectively. During reperfusion, after a short-lasting initial activation of local fibrinolysis, plasminogen activator activity was suppressed, as indicated by an approximately 4-fold increase in portal plasma levels of the plasminogen activator inhibitor. D-dimer levels showed that activation of coagulation and depression of fibrinolysis resulted in fibrin formation, which was confirmed to be intravascular fibrin deposition by histologic examination.

CONCLUSIONS

Intestinal ischemia-reperfusion results in local intravascular coagulation and fibrin deposition.

Glutamine deprivation facilitates tumour necrosis factor induced bacterial translocation in Caco-2 cells by depletion of enterocyte fuel substrate

BACKGROUND AND AIMS

Factors that induce luminal bacteria to cross the intestinal epithelium following injury remain poorly defined. The aim of this study was to investigate the interaction between glutamine metabolism, energy supply, and inflammatory mediators in determining the translocation of non-pathogenic bacteria across cultured enterocytes.

METHODS

The effect of tumour necrosis factor alpha (TNF-alpha) on translocation of Escherichia coli C25 across Caco-2 epithelial monolayers was studied in the presence of products and inhibitors of glutamine metabolism. Simultaneous measurements of transepithelial electrical resistance (TEER) and flux of lucifer yellow were used to assess effects on the paracellular pathway. Lactate dehydrogenase release was used to monitor enterocyte integrity. Imaging of monolayers in these experimental conditions was undertaken with transmission electron microscopy.

RESULTS

Exposure to basolateral TNF-alpha (20 ng/ml) for six hours induced translocation of E coli across Caco-2 but only if accompanied by simultaneous glutamine depletion (p<0.01). Translocation was inhibited by addition of glutamine for two hours (p<0.01) but not by an isonitrogenous mixture of non-glutamine containing amino acids. Inhibition of glutamine conversion to alpha-ketoglutarate, but not blockade of glutathione or polyamine synthesis, also induced translocation in the presence of TNF-alpha. Manipulations that induced bacterial translocation were associated with a marked reduction in enterocyte ATP levels. No effect of these treatments on paracellular permeability or lactate dehydrogenase release was observed. Conditions in which translocation occurred were associated with the presence of bacteria within enterocyte vacuoles but not the paracellular space.

CONCLUSIONS

In inflammatory conditions, the availability of glutamine as an enterocyte fuel substrate is essential for the preservation of a functional barrier to microorganisms. In conditions of acute glutamine depletion, cytokine mediated bacterial translocation appears to be primarily a transcellular process.

Kinetics of endotoxin concentration and tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 activities in the systemic and portal circulation during small intestinal ischemia and reperfusion in dogs

OBJECTIVE

To determine whether small intestinal ischemia and reperfusion induces bacterial translocation and proinflammatory cytokine response in either the systemic or portal circulation in dogs.

ANIMALS

17 healthy adult Beagles.

PROCEDURE

The superior mesenteric artery (SMA) was occluded for 0 (group-3 dogs), 30 (group-1 dogs), or 60 (group-2 dogs) minutes, followed by reperfusion for 180 minutes; serum lactate and endotoxin concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 activities in the systemic and portal circulation and intramucosal pH were measured at various time points.

RESULTS

In group-2 dogs, TNFalpha activity was found to be significantly increased in the portal circulation, peaking at 60 minutes of reperfusion; TNF-alpha activity, in the systemic circulation, gradually increased from 60 minutes of reperfusion to the end of the experiment; however, the increase was not significant. In group-1 and -2 dogs, IL-6 activities significantly and gradually increased in the systemic and portal circulation during the reperfusion phase, and the magnitude of these increases was dependent on the duration of the ischemic phase. There were no significant changes in IL-1beta activity or endotoxin concentration in any dog group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of the our study indicate that intestinal ischemia and reperfusion leads to significant increases of the circulating TNF-alpha and IL-6 activities, depending on the duration of the ischemia phase, in the absence of detectable endotoxin in the circulation. This finding suggests that intestinal ischemia and reperfusion induces a systemic proinflammatory cytokine response in dogs.