Protective effects of lazaroid U74389G on intestinal graft after heterotopic small bowel transplantation in rats

Lazaroid U-74389G in liver ischemia-reperfusion injury: A swine model

Reactive oxygen species have a key role in liver ischemia-reperfusion (I/R) injury. In the present study, the effect of the anti-oxidant compound lazaroid U-74389G in preventing liver I/R injury was investigated in a swine model. Ischemia was produced by portal vein occlusion. Two sets of experiments were performed, each with two groups (n=7 per group). In the first group, the potential protective effect of an intracaval injection of U-74389G after a 30-min ischemia, followed by a 60-min reperfusion period was assessed (biopsies at 0, 15, 30 and 90 min experimental time). In the second set, the effect of intracaval U-74389G injection after 30 min of ischemia, followed by a longer reperfusion period of 120 min was determined (biopsies at 0, 15, 30 and 150 min experimental time). Liver malondialdehyde, hepatocyte vacuolation-degeneration, venous congestion, inflammatory cell infiltration, sinus congestion-dilation and Chiu score of intestinal damage were determined at up to 150 min of reperfusion. In the second set of experiments, the Chiu score of intestinal damage was improved by the administration of U-74389G (3.17±0.40 vs. 4.33±0.21; P=0.030). However, in the two sets of experiments, the liver inflammatory reaction was more pronounced in the U-74389G groups (P=0.017 for the first set, P=0.021 for the second set). No significant effect of U-74389G on any other parameters was detected. In conclusion, intestinal damage due to portal venous congestion and reflow appears to be mitigated by the lazaroid U-74389G; however, intracaval administration of U-74389G does not appear to exert any protective effects against liver I/R-induced inflammation.

Ubiquitin-proteasome system and oxidative stress in liver transplantation

A major issue in organ transplantation is the development of a protocol that can preserve organs under optimal conditions. Damage to organs is commonly a consequence of flow deprivation and oxygen starvation following the restoration of blood flow and reoxygenation. This is known as ischemia-reperfusion injury (IRI): a complex multifactorial process that causes cell damage. While the oxygen deprivation due to ischemia depletes cell energy, subsequent tissue oxygenation due to reperfusion induces many cascades, from reactive oxygen species production to apoptosis initiation. Autophagy has also been identified in the pathogenesis of IRI, although such alterations and their subsequent functional significance are controversial. Moreover, proteasome activation may be a relevant pathophysiological mechanism. Different strategies have been adopted to limit IRI damage, including the supplementation of commercial preservation media with pharmacological agents or additives. In this review, we focus on novel strategies related to the ubiquitin proteasome system and oxidative stress inhibition, which have been used to minimize damage in liver transplantation.

Experimental Hemorrhagic Shock Protocol in Swine Models: The Effects of 21-Aminosteroid on the Small Intestine

Background

The protective potential of lazaroids has been reported in previous studies on ischemia/reperfusion and induced hemorrhagic shock protocols.

Objectives

The present study is the first experimental protocol on the effects of the antioxidant factor U-74389G on the small intestine of swine models in a hemorrhagic shock protocol and resuscitation with 3 different types of fluids.

Methods

The study included 49 Landrace breed swine that were divided into groups of 7 each. Hemorrhage was provoked 45 minutes after starting the surgical protocol (0 minutes), followed by resuscitation starting 30 minutes after haemorrhage ceased by using 3 different fluids. Three groups (Group A, resuscitation using blood; Group B, resuscitation with Ringer’s lactate solution; and Group C, resuscitation with hypertonic saline solution) underwent resuscitation with fluid alone, and another 3 groups (named A', B,' and C') were administered lazaroid U-74389G in addition to fluid. Control Group S underwent all the surgical procedures without hemorrhagic shock. Vital signs, complete blood count, and biochemical markers were analyzed, and tissue samples of the small intestine were collected from all animals. Further, malondialdehyde, tumor necrosis factor-α, and levels of inflammation in the tissue sample were measured.

Results

In Group S-A-A' and Group S-C-C', the analysis did not show statistically significant differences in the percentage changes of histopathology, malondialdehyde, and tumor necrosis factor-α through time. In Group S-B-B', the malondialdehyde levels in the small intestine were reduced in both the B and B' groups, without lazaroid (Group B) (P = 0.038) and lazaroid (Group B') (P = 0.011), compared with Group S (control), but the group without lazaroid (Group B) had greater reduction in malondialdehyde levels than the group treated with lazaroid (Group B'). With regard to the biochemistry results, 24% reduction was observed for alkaline phosphatase (P = 0.022) in Group A' treated with lazaroid compared with that in the untreated group. Lastly, for the complete blood count parameters, a 14% reduction in white blood cells was observed in Group B', which was treated with lazaroid in all phases (P = 0.015) (absolute value = 6.23) compared with Group B (absolute value = 13.74).

Conclusions

Despite few initial findings of this study suggesting that administration of lazaroid U-74389G may have some potential in attenuation of the effects of hemorrhagic shock in the small intestine of swine models, no differences remained after correction for multiple comparisons was made. Therefore, further research is required to investigate this result thoroughly.

Effects of lazaroid U-74389G on intestinal ischemia and reperfusion injury in porcine experimental model

BACKGROUND

The readmission of molecular oxygen into an ischemic tissue promotes the oxidation of resuscitated tissue with certain pathophysiologic mechanisms.

MATERIALS AND METHODS

Twenty four pigs (male or female) were randomized in this study. The animals were allocated to four groups with an equal number (n = 6) in each group: (1) control group-ischemia for 30 min and reperfusion for 60 min. (2) control group-ischemia for 30 min and reperfusion for 120 min. (3) ischemia for 30 min and immediate iv injection of lazaroid U-74389G and reperfusion for 60 min. (4) ischemia for 30 min and immediate iv injection of lazaroid U-74389G and reperfusion for 120 min.

RESULTS

We investigated further the role of an antioxidant molecule such as U-74389G and we concluded that there is statistically significant relation in MDA (malondialdeyde), TNF -α (tumor necrosis factor-α) measurement in tissue, while the histological score in the groups that the lazaroid was administered was improved.

CONCLUSIONS

In many emergency clinical situations, such as reperfusion of the intestine, the role of U-74389G can be protective.

Effectiveness of sildenafil and U-74389G in a rat model of colitis

BACKGROUND

Crohn disease is still incurable. Compounds with anti-inflammatory and/or antioxidative effects are tested in various preclinical models of the disease. Our aim was to investigate the effects of sildenafil and lazaroid U-74389G in an experimental rat model of trinitrobenzenesulfonic acid-induced colitis.

MATERIALS AND METHODS

Trinitrobenzenesulfonic acid was instilled into the colon of all male Wistar rats except for the rats belonging to the first group. For 6 days, the animals in group 3 were administered daily sildenafil orally, the rats in group 4 were administered daily U-74389G intravenously, and the rats in group 5 were coadministered daily sildenafil orally and intravenous U-74389G. The rats in groups 1 and 2 were not administered any treatment. During the study, the weights were recorded as a marker of clinical condition. The colon damage was evaluated using macroscopic colon mucosal damage index (CMDI), microscopic (Geboes score), and biochemical methods (tissue tumor necrosis factor [TNF]-α and malondialdehyde [MDA]).

RESULTS

Sildenafil reduced TNF-α tissue levels and increased body weight. U-74389G reduced TNF-α, the macroscopic index of mucosal damage score (CMDI) and increased body weight. The combined treatment with sildenafil and U-74389G reduced tissue levels of both TNF-α and MDA, lowered CMDI and microscopic Geboes score, and increased body weight.

CONCLUSIONS

U-74389G demonstrated a significant anti-inflammatory activity related to its ability to reduce colonic TNF-α, CMDI score, and improve weight change. We confirmed that sildenafil has anti-inflammatory capacity by reducing colonic TNF-α and by improving body weight. Finally, the combined treatment showed superior effects by reducing colonic TNF-α, colonic MDA, CMDI score, Geboes score, and by improving weight.

Effects of lazaroids on intestinal ischemia and reperfusion injury in experimental models

Mesenteric ischemia occurs in a number of clinically relevant pathophysiologic processes, including sepsis, hemorrhage, intestinal transplantation, severe burns, and mesenteric thrombosis. The readmission of molecular oxygen into an ischemic tissue promotes the oxidation of resuscitated tissue with certain pathophysiologic mechanisms. Depending on the duration and the intensity of ischemia, reoxygenation of the intestine that has been reperfused may further induce tissue injury. Intestinal ischemia and reperfusion injury can accelerate complex processes between the endothelium and different cell types leading to microvascular injury, cellular necrosis, and apoptosis. The injury due to reperfusion is found predominantly in the intestinal mucosa and submucosa, causing endothelial detachment. The 21-aminosteroids (lazaroids) are a family of compounds that inhibit lipid membrane peroxidation. Many of the performed studies show conflicting results, which reflect differences in experimental design, evolving time that (I/R) is induced, total or partial vascular occlusion, dosage of the lazaroid, and the exact period of time that the lazaroid is administered.

In vivo investigation of the efficacy of a customized solution to attenuate injury following low-flow ischemia and reperfusion injury in the jejunum of horses

OBJECTIVE

To evaluate the efficacy of a customized solution to attenuate intestinal injury following 20% low-flow ischemia and reperfusion in the jejunum of horses.

ANIMALS

10 healthy adult horses.

PROCEDURE

Two 30.5-cm-long segments of jejunum were exteriorized through a ventral midline incision and the mesenteric artery and vein supplying that portion of the intestine were instrumented with flow probes. Blood flow was decreased to 20% of baseline for 90 minutes followed by 90 minutes of reperfusion. In 5 horses, 60 mL of the customized solution was placed in the lumen of each segment (treatment-group horses), and 60 mL of lactated Ringer's solution was placed in the lumen of 5 additional horses (control-group horses). Biopsy specimens were obtained from 1 segment in both groups for histologic evaluation. Aliquots of luminal fluid were obtained from the other segment in both groups for determination of albumin concentrations as an index of mucosal permeability.

RESULTS

Compared with control-group horses, treatment-group horses had a significant decrease in luminal albumin concentration following reperfusion. Although differences in mucosal grades were not significantly different between control- and treatment-group horses, treatment-group horses had significantly greater jejunal villous length and area, compared with that of control-group horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Intraluminal administration of the customized solution in the jejunum, compared with lactated Ringer's solution, results in an improvement in histologic findings and mucosal translocation of albumin in horses with mild intestinal injury.

Mice with targeted disruption of p8 gene show increased sensitivity to lipopolysaccharide and DNA microarray analysis of livers reveals an aberrant gene expression response

BACKGROUND

p8 is a DNA-binding protein induced in many tissues in response to LPS treatment. Hence, p8 could be a mediator of LPS-associated effects or, on the contrary, p8 expression may be part of the protective mechanism of the tissues in response to LPS. Finally, p8 expression in response to LPS could also be a simple epiphenomenon.

METHODS

To investigate the role of p8 in vivo, we generated p8-deficient mice by gene targeting. Because p8 is a stress protein, we analyzed the response of p8-/- mice to a systemic stress induced by LPS injection. Liver was chosen as model organ to monitor alterations in gene expression.

RESULTS

LPS resulted in higher serum TNF-alpha concentration and higher mortality rate in p8-deficient mice than in wild-type. Also, liver and pancreas, but not lung, from p8-/- mice showed increased amounts of MPO and HPO. To gain insight into the molecular bases of such susceptibility, we used high density DNA microarrays consisting of ~6000 genes and ESTs to compare gene regulation in response to LPS in p8+/+ and p8-/- livers. In wild-type, 105 genes and 73 ESTs were up-regulated and 232 genes and 138 ESTs down-regulated. By contrast, 212 genes and 125 ESTs were found up-regulated and 90 genes and 85 ESTs down regulated in p8-/- mice. Among them, only 93 (51 induced and 42 repressed) corresponded to the wild-type pattern, demonstrating that p8 deficiency hinders the normal response to LPS, which may account for the increased sensitivity of p8-/-mice to the endotoxin.

CONCLUSIONS

The large number of genes showing abnormal regulation after LPS suggests that p8 is an important regulatory factor involved in many cellular defence pathways.

Lazaroid (U74389G)-supplemented cardioplegia: results of a double-blind, randomized, controlled trial in a porcine model of orthotopic heart transplantation

BACKGROUND

U74389G (16-desmethyl tirilazad), a 21-aminosteroid or "lazaroid," inhibits lipid peroxidation, which is an important element of ischemia-reperfusion injury. The aim of this study was to determine whether the addition of U74389G to the cardioplegic preservation solution could improve early cardiac allograft function.

METHODS

A porcine model of donor brain death and orthotopic cardiac transplantation was used. Hearts were arrested and preserved for 6 hours in an aspartate-enriched extracellular cardioplegia that had been supplemented with either U74389G and its carrier (n = 7) or the carrier alone (n = 9). Epicardial sonomicrometry and transmyocardial micromanometry were used to obtain pressure-volume loops before and after transplantation. Left ventricular wall volume was measured by volume displacement.

RESULTS

A higher proportion of U74389G-treated hearts were weaned successfully from cardiopulmonary bypass, but this difference did not achieve statistical significance (86% [6 of 7] vs 56% [5 of 9]; p = 0.308). In the hearts that were weaned successfully, preservation of left ventricular contractility, as judged by the pre-load recruitable stroke work relationship, was significantly better in the U74389G-treated hearts (p = 0.0271). In contrast, left ventricular compliance, as judged by the end-diastolic pressure-volume relationship, was significantly better preserved in the control group (p < 0.0001). U74389G-treated hearts developed less myocardial edema, as judged by the post-transplant left ventricular wall volume/baseline steady-state epicardial end-diastolic volume ratio (64 +/- 9% vs 76 +/- 11%; p = 0.045).

CONCLUSIONS

The benefit obtained from U74389G-supplemented cardioplegic preservation solution was marginal for hearts stored for 6 hours. After longer ischemic times, the benefit may be clearer.

In vitro evaluation of an intraluminal solution to attenuate effects of ischemia and reperfusion in the small intestine of horses

OBJECTIVE

To evaluate the efficacy of intraluminal administration of a customized solution during low-flow ischemia and reperfusion in the jejunum of horses.

SAMPLE POPULATION

Segments of jejunum obtained from 13 healthy adult horses.

PROCEDURE

In isolated segments of jejunum maintained in an extracorporeal circuit, arterial flow was reduced to 20% of baseline for 40 minutes (ischemia) followed by 60 minutes of reperfusion. In 2 groups, a customized solution (concentrations, 12.5 and 25%, respectively) was placed in the lumen prior to low-flow ischemia and maintained during reperfusion. The control group received intraluminal lactated Ringer's solution for the same duration. Various metabolic, hemodynamic, histologic, and permeability variables were recorded.

RESULTS

The 12.5% solution resulted in less histomorphologic injury and reduced mucosal permeability to albumin, compared with the 25% solution and the lactated Ringer's solution. Morphologic injury and permeability were reduced in tissues that received the 25% solution, compared with the control group, but this difference was not significant.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of a 12.5% customized solution appeared to minimize injury in the isolated extracoporeal jejunal loop, which provides some indication that it might be useful in clinical situations.

Bacterial [correction of baterial] translocation in humans

Bacterial translocation is a phenomenon in which live bacteria cross the intestinal barrier. The definition may be broadened to include transmural passage of bacterial cell wall components such as lipopolysaccharide and peptidoglycan polysaccharide. After translocation, bacteria or their products reach the mesenteric lymph nodes. From there, it is possible that enteric bacteria, their cell wall components, or both may disseminate throughout the body, causing sepsis, shock, multisystem organ dysfunction, or death of the host. Bacterial translocation and its complications have been shown clearly to occur in animal models, but its existence and importance in humans has been difficult to ascertain. The purpose of this review is to evaluate the data from studies in humans on the occurrence of bacterial translocation and, more importantly, to evaluate its role as a cause of death in humans. Studies from trauma and intensive care centers often imply that bacterial translocation is a major contributor to sepsis, shock, and multisystem organ failure in humans. However, the data reviewed herein do not support that view clearly. Carefully designed studies are needed to determine the relevance of bacterial translocation in human disease.

Bacterial translocation in clinical intestinal transplantation

BACKGROUND

Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after small bowel transplantation (SBTx). Bacterial overgrowth, alteration of the mucosal barrier function as a consequence of preservation injury or acute rejection (AR), and potent immunosuppression are all associated with BT. The aim of this study was to evaluate and quantify the correlation of BT with these events.

METHODS

Fifty pediatric SBTx recipients on tacrolimus and prednisone immunosuppression were analyzed. Blood, stool, and liver biopsies and peritoneal fluid were cultured (circa 4000 total specimens) when infection was clinically suspected or as part of follow-up. BT episodes were considered when microorganisms were found simultaneously in blood or liver biopsy and stool.

RESULTS

BT (average of 2.0 episodes/patient) was evident in 44% of patients and was most frequently caused by Enterococcus, Staphylococcus, Enterobacter, and Klebsiella. The presence of a colon allograft was associated with a higher rate of BT (75% vs. 33.3%). Furthermore, the transplantation procedure (colon vs. no colon) affected the rate of BT: SBTx=40% vs. 25%, combined liver and SBTx=100% vs. 30%, multivisceral transplantation=25% vs. 50%. AR was associated with 39% of BT episodes. BT followed AR in 9.6% of the cases. In 5.2% of the cases, positive blood cultures without stool confirmation of the bacteria were seen. Prolonged cold ischemia time (CIT) affected BT rate significantly (CIT>9 hr 76% vs. CIT<9 hr 20.8%).

CONCLUSIONS

This study shows that 1) a substantial percentage of, but not all, BT is associated with AR, 2) the presence of a colon allograft increases the risk for BT, and 3) a long CIT is associated with a high incidence of BT after SBTx.