Effects of anticoagulant treatment on intestinal ischaemia and reperfusion injury in rats

Tissue Injury Protection: The Other Face of Anticoagulant Treatments in the Context of Ischemia and Reperfusion Injury with a Focus on Transplantation

Organ transplantation has enhanced the length and quality of life of patients suffering from life-threatening organ failure. Donors deceased after brain death (DBDDs) have been a primary source of organs for transplantation for a long time, but the need to find new strategies to face organ shortages has led to the broadening of the criteria for selecting DBDDs and advancing utilization of donors deceased after circulatory death. These new sources of organs come with an elevated risk of procuring organs of suboptimal quality. Whatever the source of organs for transplant, one constant issue is the occurrence of ischemia-reperfusion (IR) injury. The latter results from the variation of oxygen supply during the sequence of ischemia and reperfusion, from organ procurement to the restoration of blood circulation, triggering many deleterious interdependent processes involving biochemical, immune, vascular and coagulation systems. In this review, we focus on the roles of thrombo-inflammation and coagulation as part of IR injury, and we give an overview of the state of the art and perspectives on anticoagulant therapies in the field of transplantation, discussing benefits and risks and proposing a strategic guide to their use during transplantation procedures.

Effects of Preoperative Glycyrrhizin Infusion for the Prevention of Venous Thrombosis on the Tissue Expression of Antithrombin in a Rat Model

OBJECTIVE

Using a thrombus model prepared by ligation of the inferior vena cava (IVC), the influences of the glycoside, glycyrrhizin, on plasma antithrombin levels and antithrombin mRNA expression levels in the liver and IVC with the inhibition of venous thrombosis were investigated.

MATERIALS AND METHODS

The rat IVC was exposed and ligated for 24 h immediately after the intravenous administration of 300 mg/kg glycyrrhizin. Among antithrombotic drugs, the Xa inhibitor, fondaparinux sodium, was used as a control drug.

RESULTS

The mean thrombus weight was significantly smaller in the glycyrrhizin-treated group (18.3 mg) than in the saline-treated group (34.3 mg). In contrast, the inhibition of thrombosis was not observed in the fondaparinux-treated group. Antithrombin mRNA expression levels in the liver were significantly higher in the ligated groups than in the baseline control group. The mean plasma antithrombin level was significantly lower in the glycyrrhizin group (96.6%) than in the saline group (114.4%), but was not significantly different from that in the baseline control group (102.4%).

CONCLUSION

The pretreatment with glycyrrhizin inhibited venous thrombosis, and antithrombin mRNA expression levels in the liver and IVC as well as plasma antithrombin levels were significantly lower than those in the saline group.

Hypercoagulation following brain death cannot be reversed by the neutralization of systemic tissue factor

BACKGROUND

Cerebral injury and brain death is associated with apparent hypercoagulation and poor organ outcome. This experimental study challenges the hypotheses that i) brain death causes hypercoagulation and microvascular thrombosis and that ii) neutralizing systemic tissue factor (TF) by in vitro addition of a TF inhibitor (recombinant active site-inhibited factor VIIa (ASIS)) can reverse the hypercoagulable profile.

METHODS

Using a validated pig model of intracranial hemorrhage and brain death, 20 pigs were randomized to either control or brain death. The primary endpoints were coagulation parameters measured with whole blood thromboelastometry (ROTEM), thrombin generation and a porcine TF-sensitive plasma clotting time assay. In vitro spiking experiments with ASIS were performed in parallel with the latter two assessments. The kidneys were examined histologically for microvascular thromboses.

RESULTS

Brain death induced hypercoagulation, as demonstrated with ROTEM, thrombin generation, and reduced TF-sensitive plasma clotting time. In vitro inhibition of TF with ASIS did not reverse the hypercoagulation. No microvascular thromboses were found in the kidneys.

CONCLUSION

Brain death causes hypercoagulation; however, inhibition of TF does not reverse the coagulopathy. Thus, TF release does not seem to be the primary cause of this hypercoagulation. Minor changes in the levels of protein C suggest that the protein C pathway may be linked to the observed coagulopathy.

Oral administration of lactoferrin attenuates intestinal ischemia-reperfusion injury in rats

BACKGROUND

Intestinal ischemia-reperfusion (I/R) is a common and serious clinical condition. Lactoferrin (Lf) has displayed antioxidative and anti-inflammatory activities in protecting the intestinal mucosa. The objective of this study was to investigate whether oral administration of Lf could attenuate I/R-induced intestinal injury.

METHODS

The experimental design consisted of three groups of Wistar rats (24 per group): sham operation, control (I/R, saline), Lf (I/R, Lf). Intestinal I/R was produced by occlusion of the superior mesenteric artery for 45 min. Eight rats from each group were randomly sacrificed 3, 12 or 36 h after reperfusion, and blood and intestinal samples were collected.

RESULTS

Intestinal I/R resulted in gut damage evidenced by morphological alteration, reduction of γ-glutamyl transpeptidase (γ-GGT) activity and increased cell apoptosis. Daily administration of Lf (200 mg/kg) for 14 days before surgery significantly attenuated gut damage by reducing the histologic score and apoptosis index, and restoring intestinal γ-GGT activity. Lf reduced intestinal malondialdehyde and myeloperoxidase, restored glutathione and decreased serum levels of tumor necrosis factor-α, interleukin (IL)-1β and IL-6 compared with saline control in I/R rats. In addition, oral administration of Lf did not produce any significant effects in healthy rats; Lf at doses of 50 or 100 mg/kg also attenuated I/R-induced gut damage, but administration of Lf for 7 days did not exert a significant protective effect against I/R-induced gut damage.

CONCLUSIONS

These results indicate that Lf may serve as a potent supplement in protecting the gut from intestinal I/R-induced injury by its antioxidative, anti-inflammatory and antiapoptotic activities.

Changes in the concentration of monocytic chemotaxic protein-1 in patients with unstable angina treated with arixtra

The time course of inflammatory reaction markers in the blood of patients with unstable angina was studied during therapy including arixtra. Plasma concentration of monocytic chemotaxic protein-1 (MCP-1) decreased on days 2 and 3 in patients receiving arixtra and a trend to an increase in MCP-1 concentration was observed on day 7 after the drug was discontinued. After 1 month, MCP-1 level decreased in all patients. The concentration of highly sensitive C-reactive protein also decreased 1 month after the disease onset; no changes in the concentrations of IL-8 and IL-2 receptor α-subunit were detected during these periods. It seems that arixtra is characterized by an anti-inflammatory effect manifesting by reduction of plasma chemokine MCP-1 concentration.

Oxymatrine attenuates intestinal ischemia/reperfusion injury in rats

PURPOSE

Intestinal ischemia/reperfusion (I/R) is a common and serious clinical condition. The anti-inflammatory and anti-apoptotic properties of oxymatrine, the extract from a traditional Chinese herb, Sophora flavescens Ait, have been shown to protect the liver from I/R injury and attenuate colitis. The objective of this study was to investigate if oxymatrine could attenuate intestinal I/R injury induced in rats.

METHODS

The experimental design consisted of three groups of 24 Wistar rats each: a sham-operation group (control group), a group subjected to intestinal I/R and then given saline (saline group), and a group subjected to intestinal I/R and then given oxymatrine (oxymatrine group). Intestinal I/R was induced by occluding the superior mesenteric artery for 45 min. Six rats from each group were killed at selected time points, and blood and intestinal samples were collected.

RESULTS

Morphological alteration, reduction of gamma-glutamyl transpeptidase (gamma-GGT) activity, and increased cell apoptosis confirmed intestinal I/R injury. The oxymatrine group had a significantly lower histological score and apoptosis index than the saline group, demonstrating that the preadministration of oxymatrine attenuated gut damage. Moreover, oxymatrine inhibited the production of lipid peroxides (LPO), decreased the serum levels of tumor necrosis factor (TNF)-alpha, and downregulated expression of phosphorylated p38 mitogen-activated protein kinase, Fas, and FasL, which had been elevated by I/R.

CONCLUSIONS

These results provide further evidence of the anti-inflammatory and anti-apoptotic activities of oxymatrine, which may become a potent drug for protecting the intestines against I/R injury.

Sirtinol attenuates hepatic injury and pro-inflammatory cytokine production following trauma-hemorrhage in male Sprague-Dawley rats

BACKGROUND

Although studies have demonstrated that sirtinol administration following adverse circulatory conditions is known to be protective, the mechanism by which sirtinol produces the salutary effects remains unknown. We hypothesized that sirtinol administration in male rats following trauma-hemorrhage decreases cytokine production and protects against hepatic injury.

METHODS

Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure 40 mmHg for 90 min, then resuscitation). A single dose of sirtinol (1 mg/kg of body weight) or vehicle was administered intravenously during resuscitation. Twenty-four hours thereafter, tissue myeloperoxidase (MPO) activity (a marker of neutrophil sequestration), cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-3, intercellular adhesion molecule (ICAM)-1, and interleukin (IL)-6 levels in the liver and plasma alanine aminotransferase (ALT) concentrations were measured (n=6 Sprague-Dawley rats/group).

RESULTS

Trauma-hemorrhage increased hepatic MPO activity, CINC-1, CINC-3, ICAM-1, and IL-6 levels and plasma ALT concentrations. These parameters were significantly improved in the sirtinol-treated rats subjected to trauma-hemorrhage.

CONCLUSION

The salutary effects of sirtinol administration on attenuation of hepatic injury following trauma-hemorrhage are, at least in part, related to reduction of pro-inflammatory mediators.

Taurine attenuates multiple organ injury induced by intestinal ischemia reperfusion in rats

BACKGROUND

Intestinal ischemia reperfusion (II/R) is a serious clinical condition associated with simultaneous multiple organ dysfunction. The purpose of this study was to investigate whether taurine, an anti-oxidative, anti-inflammatory, and anti-apoptotic agent, could attenuate multiple organ injury induced by II/R.

MATERIALS AND METHODS

Taurine was intravenously injected to Wistar rats 30 min before II/R; physiological saline and sham operation served as controls. II/R was produced by occlusion of superior mesenteric artery for 60 min. Rats were randomly sacrificed 1.5, 3, 12, and 36 h after II/R; blood samples were collected for assessing alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), and tumor necrosis factor-alpha (TNF-alpha), and intestines, livers, kidneys, and lungs were removed for histological examination of scoring injury severity and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling analysis. The amount of lipid peroxides (LPO) was measured in intestinal tissues, and expression of caspase-3 was detected in all of the tissues with Western blot analysis.

RESULTS

II/R resulted in injury to intestines as well as livers, kidneys, and lungs, evidenced by morphological alteration, increased cell apoptosis, and elevated serum levels of ALT, AST, BUN, and Cr. The damage reached peak 3 h after II/R. The intestinal LPO and serum levels of TNF-alpha were increased after II/R. Pre-administration of taurine significantly attenuated multiple organ injury as the histological score, apoptosis index, LPO, and levels of ALT, AST, BUN, Cr, and TNF-alpha were significantly lower compared with saline controls.

CONCLUSIONS

Taurine attenuates multiple organ injury induced by II/R. Although the mechanism needs further investigation, taurine inhibits production of intestinal LPO, release of TNF-alpha, cell apoptosis, and expression of caspase-3.

Intestinal ischemia-reperfusion injury alters purinergic receptor expression in clinically relevant extraintestinal organs

BACKGROUND

Intestinal ischemia-reperfusion (IIR) injury is known to initiate the systemic inflammatory response syndrome, which often progresses to multiple organ failure. We investigated changes in purinoceptor expression in clinically relevant extra-intestinal organs following IIR injury.

MATERIALS AND METHODS

Anesthetized adult male BalbC mice were randomized to sham laparotomy (control, n = 5), or 15 min of superior mesenteric artery occlusion. Experimental ischemia was followed by a period of reperfusion [1 min (n = 6) or 1 h (n = 6)]. Mice were then sacrificed and lung, kidney, and intestinal tissues were harvested. Following RNA extraction, purinoceptor mRNA expression for P2Y2, A3, P2X7, A2b, P2Y4, and P2Y6 was analyzed using real-time RT-PCR.

RESULTS

Significant differences in purinoceptor expression were observed in the lungs and kidneys of mice exposed to IIR injury when compared to controls. Pulmonary P2Y2 receptor expression was increased in the 1 h IIR group when compared to control, while pulmonary A3 receptor expression was incrementally elevated following IIR injury. In the kidney, P2Y2 receptor expression was increased in the 1 h IIR group compared to both 1 min IIR and control, and A3 receptor expression was decreased in the 1 h IIR group compared to the 1 min IIR group. No significant changes were observed in the intestinal purinoceptor profiles.

CONCLUSION

Purinoceptor expression is altered in the murine lung and kidney, but not intestine following experimental IIR injury. These findings may implicate extracellular nucleotides and purinoceptors as possible mediators of the extra-intestinal organ dysfunction associated with IIR injury.