The effect of FK506 on warm ischemia and reperfusion injury in the rat liver

Assessment of Effect of Intraperitoneal Tacrolimus on Liver Regeneration in Major (70%) Hepatectomy Model After Experimental Pringle Maneuver in Rats

AIM

Small-for-size grafts have become more important, especially in living donor liver transplants. The Pringle maneuver, used to reduce blood loss, and the immunosuppressive medications used to prevent graft rejection in liver transplants have different side effects on liver regeneration. We researched the effect of situations where tacrolimus and the Pringle maneuver were applied or not on liver regeneration in rats with partial hepatectomy.

MATERIAL AND METHODS

This study was completed with 35 Wistar Albino rats. The subjects were randomly divided into 5 groups: Group 1 had the abdomen opened and no other procedure was performed; Group 2 underwent a 70% hepatectomy; Group 3 underwent a 15-minute Pringle maneuver + 70% hepatectomy; Group 4 underwent a 70% hepatectomy + 5 days of 1 mg/kg/day intraperitoneal tacrolimus; and Group 5 underwent a 150 minute Pringle maneuver + 0% hepatectomy + 5 days of 1 mg/kg/day intraperitoneal tacrolimus. All rats were sacrificed on the seventh postoperative day, remaining liver tissue was weighed, and weight indices created. The remaining liver tissue was stained with phosphohistone H3 and the mitotic index calculated.

RESULTS

The groups that underwent the Pringle maneuver, 70% hepatectomy, and tacrolimus administration were compared with the control group in terms of mitotic index and weight index, but no statistically significant differences were identified.

CONCLUSION

Suppression of regeneration forms a risk after liver transplantation with small-volume grafts. As a result, research on the effect of tacrolimus combined with the Pringle maneuver is important, especially for transplantations using segmented liver grafts. In our study, we showed that the use of tacrolimus had no negative effect on liver regeneration.

The protective effects of tacrolimus on rat uteri exposed to ischemia-reperfusion injury: a biochemical and histopathologic evaluation

OBJECTIVE

To evaluate the effects of the immunosuppressant tacrolimus as an antioxidant and analyze the histopathologic changes in rat uteri exposed to experimental ischemia-reperfusion (I/R) injury.

DESIGN

Experimental study.

SETTING

Experimental surgery laboratory in a university.

ANIMAL(S)

Twenty-eight female rats exposed to experimentally induced uterine I/R injury.

INTERVENTION(S)

Group I: control group; group II: uterine I/R injury-induced group; group III: pre-ischemia tacrolimus group; group IV: post-ischemia tacrolimus group.

MAIN OUTCOME MEASURE(S)

Uterine tissue malondialdehyde (MDA) level as a marker of lipid peroxidation and glutathione (GSH) level and superoxide dismutase (SOD) and catalase (CAT) activities as markers of tissue antioxidant capacity; histopathologic examination of all uterine rat tissue.

RESULT(S)

Following aortic I/R injury, MDA levels were significantly increased whereas GSH levels and CAT and SOD activities were found to be decreased compared with control animals. MDA levels were found to recover prominently after the administration of tacrolimus in both groups III and IV. Administration of tacrolimus improved uterine GSH levels and CAT activity in the tacrolimus-treated groups.

CONCLUSION(S)

Our results indicate that tacrolimus reduces oxidative damage in rat uteri exposed to I/R injury induced by distal abdominal aortic occlusion. Histologic evaluation reveals that tacrolimus attenuates the inflammatory response and protects the tissue damage induced by I/R injury.

Warm ischemia-reperfusion injury is decreased by tacrolimus in steatotic rat liver

Ischemia-reperfusion (I-R) injury is poorly tolerated by fatty livers, most probably secondary to reduced cellular adenosine triphosphate (ATP) levels. We investigated the effectiveness of tacrolimus pretreatment on fatty liver I-R injury in obese Zucker rats. Tacrolimus (0.3 mg/kg, intravenously) was injected 24 hours before a 75-minute ischemic period and rats were sacrificed 6 hours later. Tacrolimus modified the response to I-R observed in obese Zucker rats, when compared to nontreated obese rats: a significant reduction in hepatocyte necrosis was associated with a significant increase in hepatocyte apoptosis. In addition, cell necrosis and apoptosis were significantly and inversely correlated in lean nontreated and treated obese Zucker rats following I-R. Tacrolimus also significantly increased the hepatic ATP levels, reduced in nontreated obese rats, toward values found in lean Zucker rat livers. This protective effect of tacrolimus was further confirmed in vivo by a significantly improved survival following pretreatment with tacrolimus, 24 hours prior to ischemia. In conclusion, in obese Zucker rat livers, tacrolimus pretreatment reversed the I-R injury toward the one found in lean Zucker rats. The correlations between ATP levels and the opposite changes in necrosis and apoptotic pathways strongly suggest a cause-effect relationship between tacrolimus and changes in ATP levels.

Endotracheal calcineurin inhibition ameliorates injury in an experimental model of lung ischemia-reperfusion

OBJECTIVES

We previously demonstrated that calcineurin inhibitors given intravenously ameliorate experimental lung ischemia-reperfusion injury. This study evaluates whether these effects can be achieved when these agents are delivered endotracheally.

METHODS

Left lungs of Long Evans rats were rendered ischemic for 90 minutes and reperfused for up to 4 hours. Treated animals received tacrolimus endotracheally at doses of 0.2, 0.1, or 0.025 mg/kg 60 minutes before ischemia. Injury was quantitated in terms of vascular permeability. Additional animals treated at a dose of 0.1 mg/kg were assessed for lung tissue myeloperoxidase content and bronchoalveolar lavage leukocyte content. Bronchoalveolar lavage fluid was assessed for cytokine and chemokine content by enzyme-linked immunosorbent assay. Tissue samples were processed for nuclear factor-kappaB activation, and blood levels of tacrolimus were measured in treated animals.

RESULTS

Left lung vascular permeability was reduced in treated animals in a dose-dependent fashion compared with controls. The protective effects correlated with a 47% (0.50% +/- 0.06% vs 0.27% +/- 0.08%, respectively) reduction in tissue myeloperoxidase content (P <.004) and marked reductions in bronchoalveolar lavage leukocyte accumulation. This protection was also associated with decreased nuclear factor-kappaB activation and diminished expression of proinflammatory mediators. Blood tacrolimus levels in treated animals at 4 hours of reperfusion were undetectable.

CONCLUSIONS

Tacrolimus administered endotracheally is protective against lung ischemia-reperfusion injury in our model. This protection is associated with a decrease in nuclear factor-kappaB activation. This route of tacrolimus administration broadens its potential clinical use and decreases concerns about systemic and renal toxicity. It may be a useful therapy in lung donors to protect against lung ischemia-reperfusion injury.

Inhibitory effect of FK506 and Cyclosporine A on the growth and invasion of human liver cancer cells

BACKGROUND

The prognosis of liver transplantation for liver cancer is determined by recurrence in the liver graft. In this study, the effects of immunosuppressors, FK506 and cyclosporine A (CsA) on the migration of liver cancer cells were investigated.

METHODS

The effects of FK506 at concentrations of 1-100 ng/mL and CsA at 1-1000 ng/mL on the growth of poorly and well differentiated human hepatocellular carcinoma cell lines, HLE and HuH-7, respectively, were examined. After treatment of these cells with FK506 and CsA, the growth of these cells, their cytotoxicities and invasion assay on the Matrigel basement membrane invasion chamber were evaluated. In addition, the effects of FK506 and CsA on the changes in the production of a soluble intercellular adhesion molecule-1 (sICAM-1) of these cells were measured.

RESULTS

FK506 and CsA at concentrations of 1-10 ng/mL inhibited the growth of both HLE and HuH-7 and those immunosuppressors at concentrations over 100 ng/mL exhibited cytotoxicity on these cells. FK506 at concentration of 1 ng/mL significantly inhibited the invasion of poorly differentiated HLE, but not well differentiated HuH-7, after treatment for 2-5 days in culture (p<0.05), but FK 506 at 10 ng/mL showed less inhibitory efficient. CsA at concentrations of 1-10 ng/mL, however, did not inhibit or transiently inhibited the invasion of both cell lines. The production of ICAM-1 in HLE and HuH-7 was suppressed by FK506 at concentrations of 1-10 ng/mL after treatment for 3-5 days but the effect was not significant in the initial phase at days 1-2 and the last phase at days 5-6.

CONCLUSIONS

FK506, but not CsA, at a clinical dose of 1 ng/mL significantly inhibited the invasion of the poorly-differentiated HLE, but not HuH-7 and also inhibited the production of sICAM-1 in HLE.

Effects of tacrolimus on ischemia-reperfusion injury

In addition to efficacious immunosuppression for the benefit of organ transplantation, tacrolimus has diverse actions that result in amelioration of ischemia-reperfusion injury. Knowledge is accumulating rapidly on the mechanisms through which tacrolimus exerts these cytoprotective effects, including alterations in microcirculation, free radical metabolism, calcium-activated pathways, inflammatory cascades, mitochondrial stability, apoptosis, stress-response proteins, and tissue recovery. Within the nucleus, actions mediating the effects of tacrolimus appear to be dominantly influenced by interactions with the transcription factor, nuclear factor-kappaB. Because tacrolimus is a cornerstone agent in immunosuppression regimens throughout the world and knowledge of its cellular mechanisms is evolving, it is important to update the clinical literature with this information. We reviewed the published literature with intent to portray the interactions of tacrolimus in the intricate cellular mechanisms initiated by ischemia and reperfusion.

A combined treatment with tacrolimus (FK506) and recombinant tissue plasminogen activator for thrombotic focal cerebral ischemia in rats: increased neuroprotective efficacy and extended therapeutic time window

The authors evaluated the therapeutic efficacy of tacrolimus (FK506), administered alone or in combination with recombinant tissue plasminogen activator (t-PA), on brain infarction following thrombotic middle cerebral artery (MCA) occlusion. Thrombotic occlusion of the MCA was induced by a photochemical reaction between rose bengal and green light in Sprague-Dawley rats, and the volume of ischemic brain damage was determined 24 hours later. Intravenous administration of tacrolimus or t-PA dose-dependently reduced the volume of ischemic brain infarction, whether administered immediately or 1 hour after MCA occlusion. When tacrolimus or t-PA was administered 2 hours after MCA occlusion, each drug showed a tendency to reduce ischemic brain damage. However, combined treatment with both drugs resulted in a significant reduction in ischemic brain damage. On administration 3 hours after MCA occlusion, tacrolimus alone showed no effect, and t-PA tended to worsen ischemic brain damage. However, the combined treatment with both drugs not only ameliorated the worsening trend seen with t-PA alone, but also tended to reduce ischemic brain damage. In conclusion, tacrolimus, used in combination with t-PA, augmented therapeutic efficacy on brain damage associated with focal ischemia and extended the therapeutic time window compared to single-drug treatments.

Early and delayed neuroprotective effects of FK506 on experimental focal ischemia quantitatively assessed by diffusion-weighted MRI

The immunosuppressive drug FK506 (tacrolimus) has been reported to be a powerful neuroprotective agent in the focal ischemia of animals. However, no report has been published concerning neuroprotective effect of this compound on the morphology in superacute stage. The separate analysis between early and delayed effects of FK506 on the morphology may be helpful in the study of the compound's mechanism of action which is still unknown. The goal of this study was to determine early and delayed effects of pharmacological treatment with FK506 in permanent MCA occlusion using magnetic resonance imaging (MRI). Nineteen rats were subjected to permanent MCA occlusion, and given either intravenous injection of placebo or 1 mg/kg FK506 immediately after occlusion. DWI and T(2)-weighted MRI were performed 3 and 24 h after MCA occlusion, and postmortem histological analysis was also performed. FK506 drastically reduced the ischemic damage in 3-h apparent diffusion coefficient (ADC) map. This is the first report to demonstrate the neuroprotective effects of FK506 on focal cerebral ischemia in superacute stage. In addition, postmortem ischemic damage tended to be smaller than ischemic area indicated by 3-h ADC map in the FK506 group, whereas there was an excellent equality between them in the placebo group, suggesting the possible effect of FK506 on the later ischemic period. Our findings provide direct evidence for the neuroprotective effect of FK506 on ischemic cell damage in both early stage and possibly later stage.

Evaluation of asialoglycoprotein receptor imaging agent as a marker of hepatic ischemia-reperfusion injury and recovery

Protection of hepatocytes from ischemia-reperfusion injury is a clinically important issue. The purpose of this study was to evaluate changes in acute liver damage and recovery after ischemia-reperfusion in rats with asialoglycoprotein receptor (ASGP-R) ligand. Ischemia was induced by clamping the hepatoduodenal ligament for 90 min. At 1, 3, 24, 48 hr, 1 and 2 wk after reperfusion, I-125-GSA was injected. Five min after injection, blood samples were obtained and the liver was removed. Several regions from each lobe were dissected, weighed and counted. Mean uptakes (% dose/g) in the liver and blood samples were calculated. Histologic sections stained with hematoxylin-eosin (H-E) stain showed ischemic damage at 1 and 3 hr, and focal hepatocyte necrosis at 24 hr. Predominant massive necrosis was not seen. The mitotic index with H-E stain and proliferating cell nuclear antigen (PCNA) labeling index were highest at 1 wk, indicating liver regeneration. At 1 and 3 hr, liver uptake was significantly decreased, and blood uptake was significantly increased, indicating decreased tissue blood flow and ischemic damage. Liver uptake showed significant increases at 48 hr and 1 wk, and was the highest at 1 wk, indicating liver regeneration during the convalescence stage. ASGP-R binding may provide valuable information on ischemia-reperfusion injury and recovery.

FK506 promotes liver regeneration by suppressing natural killer cell activity

We examined the mechanism of promotion of liver regeneration by tacrolimus hydrate (FK506), a potent immunosuppressant, after partial hepatectomy. The administration of FK506 significantly increased the bromodeoxyuridine (BrdU) labelling index at 36 and 48 h after 70% hepatectomy compared with the placebo group. Using the same model, we examined the effect of FK506 on the expression of hepatocyte growth factor (HGF) and transforming growth factor-beta 1 (TGF-beta 1) and found no changes in HGF and TGF-beta 1 mRNA expression in the liver or in the HGF protein concentration in plasma. We found that pretreatment with FK506 markedly reduced the activity and number of liver-resident natural killer (NK) cells at the time of partial hepatectomy. Our observations suggest that the promotion of liver regeneration by FK506 may be attributable to a reduction in the number of liver-resident NK cells and to inhibition of their activity.

Tacrolimus (FK506) attenuates leukocyte accumulation after transient retinal ischemia

BACKGROUND AND PURPOSE

Tacrolimus, an immunosuppressant agent, has been shown to reduce tissue injury and leukocyte accumulation after transient ischemia. This study was designed to evaluate quantitatively the inhibitory effects of tacrolimus on leukocyte rolling and on subsequent leukocyte accumulation in vivo after transient retinal ischemia and the protective effects of tacrolimus on ischemia-induced neural damage.

METHODS

Retinal ischemia was induced for 60 minutes in anesthetized pigmented rats by temporary ligation of the optic sheath. Tacrolimus was administered at 10 minutes after ischemic induction. At 4, 12, 24, and 48 hours after reperfusion, leukocyte behavior in the retinal microcirculation was evaluated in vivo with acridine orange digital fluorography. After 7 days of reperfusion, ischemia-induced retinal damage was evaluated histologically.

RESULTS

Treatment with tacrolimus suppressed leukocyte rolling; the maximum number of rolling leukocytes was reduced by 60.1% at 12 hours after reperfusion (P<0.05). In tacrolimus-treated rats, the velocity of rolling leukocytes was significantly faster than in vehicle-treated rats (P<0.01). The subsequent leukocyte accumulation was reduced by 61.6% at 24 hours after reperfusion (P<0.01). Histological examination demonstrated the protective effect of tacrolimus on ischemia-induced retinal damage, which was more substantial in the inner retina (P<0.01).

CONCLUSIONS

The present study demonstrated the inhibitory effect of tacrolimus on leukocyte rolling and on subsequent leukocyte accumulation and the therapeutic potency to neural injury after transient retinal ischemia.

Tacrolimus (FK506) down-regulates free radical tissue levels, serum cytokines, and neutrophil infiltration after severe liver ischemia

BACKGROUND

Liver ischemia and reperfusion injury is associated with activation of multiple inflammatory pathways, including free radicals, cytokines, and neutrophil-mediated tissue damage among others. Tacrolimus (FK506) has shown important regulatory effects on some inflammatory pathways, such as cytokines, neutrophils, and adhesion molecules. In this study, we explored a new potential protective mechanism for tacrolimus in the liver inflammatory response after ischemia and reperfusion, specifically its effect on liver tissue free radicals.

METHODS

Total hepatic ischemia was produced in the rat for 90 min with an extracorporeal portosystemic shunt. Animals (n=96) were divided into four groups: group 1 comprised normal rats for reference values; group 2 comprised sham operated rats; in group 3, ischemic control rats received only the vehicle; and the experimental treatment group, group 4, received tacrolimus at a dose of 0.3 mg/kg, 4 hr before ischemia. Animal survival was followed up to 7 days. Liver function tests were performed and liver tissue free radicals and myeloperoxidase, serum cytokines (interleukin 1, tumor necrosis factor-alpha), and liver histology were measured 4 hr after reperfusion.

RESULTS

Seven-day survival was significantly improved from only 20% in the control group to 55% in the tacrolimus group (P<0.01). Liver function tests, histology, and myeloperoxidase tissue values were significantly improved (P<0.05) with tacrolimus pretreatment. Furthermore, a significant (P<0.05) down-regulation of serum cytokines and liver tissue free radicals was observed.

CONCLUSIONS

These data indicate a new and different protective mechanism for FK506 in regard to its ability to down-regulate free radical levels in livers subjected to severe ischemia and reperfusion. Tacrolimus, also confirmed to be a potent suppressor of the cytokine response, specifically interleukin 1 and tumor necrosis, decreased neutrophil tissue migration as well.