Effects of methylprednisolone and its liver-targeted dextran prodrug on ischemia-reperfusion injury in a rat liver transplantation model

Immunosuppression for in vivo research: state-of-the-art protocols and experimental approaches

Almost every experimental treatment strategy using non-autologous cell, tissue or organ transplantation is tested in small and large animal models before clinical translation. Because these strategies require immunosuppression in most cases, immunosuppressive protocols are a key element in transplantation experiments. However, standard immunosuppressive protocols are often applied without detailed knowledge regarding their efficacy within the particular experimental setting and in the chosen model species. Optimization of such protocols is pertinent to the translation of experimental results to human patients and thus warrants further investigation. This review summarizes current knowledge regarding immunosuppressive drug classes as well as their dosages and application regimens with consideration of species-specific drug metabolization and side effects. It also summarizes contemporary knowledge of novel immunomodulatory strategies, such as the use of mesenchymal stem cells or antibodies. Thus, this review is intended to serve as a state-of-the-art compendium for researchers to refine applied experimental immunosuppression and immunomodulation strategies to enhance the predictive value of preclinical transplantation studies.

A systematic review of pharmacological treatment options used to reduce ischemia reperfusion injury in rat liver transplantation

BACKGROUND

Although animal studies models are frequently used for the purpose of attenuating ischemia reperfusion injury (IRI) in liver transplantation (LT), many of pharmacological agents have not become part of clinical routine.

METHODS

A search was performed using the PubMed database to identify agents, from which 58 articles containing 2700 rat LT procedures were selected. The identified pharmacological agents were categorized as follows: I - adenosine agonists, nitric oxide agonists, endothelin antagonists, and prostaglandins, II - Kupffer cell inactivator, III - complement inhibiter, IV - antioxidant, V - neutrophil inactivator, VI -anti-apoptosis agent, VII - heat shock protein and nuclear factor kappa B inducer, VIII - metabolic agent, IX - traditional Chinese medicine, and X - others. Meta-analysis using 7-day-survival rate was also performed with Mantel-Haenszel's Random effects model.

RESULTS

The categorization revealed that the rate of donor-treated experiments in each group was highest for agents from Group II (70%) and VII (71%), whereas it was higher for agents from Group V (83%) in the recipient-treated experiments. Furthermore, 90% of the experiments with agents in Group II provided 7-day-survival benefits. The Risk Ratio (RR) of the meta-analysis was 2.43 [95% CI: 1.88-3.14] with moderate heterogeneity. However, the RR of each of the studies was too model-dependent to be used in the search for the most promising pharmacological agent.

CONCLUSION

With regard to hepatic IRI pathology, the categorization of agents of interest would be a first step in designing suitable multifactorial and pleiotropic approaches to develop pharmacological strategies.

The evaluation of different treatment protocols for trauma-induced lung injury in rats

BACKGROUND

Lung contusion is an important factor that affects mortality and morbidity of lung injury after blunt chest trauma (BCT). The present study aims to evaluate the effectiveness of different treatment regimens on BCT-induced lung injury.

METHODS

A total of 35 Sprague Dawley rats were divided into five experimental groups (n=7): sham, control; BCT; BCT + MP, BCT group treated with methylprednisolone (MP; 30 mg/kg on first day and 3 mg/kg/d on the following days); BCT + Q, BCT group treated with quercetin (Q; 50 mg/kg/d for seven days); and BCT + MP + Q, BCT group treated with the same doses of MP and Q. Serum Clara Cell Protein-16 (CC-16), thiobarbituric acid reactive substances (TBARS), and superoxide dismutase (SOD) levels were analyzed to determine histopathological changes in the lung tissues.

RESULTS

Elevated serum CC-16 and TBARS levels and reduced serum SOD levels were found in the BCT group compared to the Sham group. There was a significant change in the serum CC-16 levels in the BCT + MP group compared to the Sham group. Serum TBARS levels were significantly lower in the BCT + MP and BCT + Q group compared to the BCT group. The combined therapy regimen yielded significantly decreased CC-16 levels and increased serum SOD levels compared to the individual treatment groups. Serum TBARS levels did not significantly differ between the BCT + MP + Q group and the other treatment groups. Compared to the BCT + MP + Q group, the BCT + MP group showed significantly lower alveolar edema (AED) and alveolar exudate (AEX) scores, while the BCT + Q group showed significantly lower peribronchial inflammatory cell infiltration (PICI) and AED scores.

CONCLUSIONS

The combined usage of quercetin and low dose MP treatment after initial high dose MP at the early stage of lung injury after BCT is more effective.

Effect of pheniramine maleate on reperfusion injury in brain tissue

BACKGROUND

The aim of this study was to investigate the protective effects of methylprednisolone (Pn), which is a potent anti-inflammatory agent, and pheniramine maleate (Ph), which is an antihistaminic with some anti-inflammatory effects, on reperfusion injury in brain developing after ischemia of the left lower extremity of rats.

MATERIAL AND METHODS

Twenty-eight randomly selected male Sprague-Dawley rats were divided into 4 groups: Group 1 was the control group, Group 2 was the sham group (I/R), Rats in Group 3 were subjected to I/R and given Ph, and rats in Group 4 were subjected to I/R and given Pn. A tourniquet was applied at the level of left groin region of subjects in the I/R group after induction of anesthesia. One h of ischemia was performed with no drug administration. In the Ph group, half of a total dose of 10 mg/kg Ph was administered intraperitoneally before ischemia and the remaining half before reperfusion. In the Pn group, subjects received a single dose of 50 mg/kg Pn intraperitoneally at the 30th min of ischemia. Brains of all subjects were removed after 24 h for examination.

RESULTS

Malondialdehyde (MDA) levels of the prefrontal cortex were significantly lower in the Ph group than in the I/R group (p<0.05). Superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were found to be significantly higher in the Ph group than in the I/R group (p<0.05). Histological examination demonstrated that Ph had protective effects against I/R injury developing in the brain tissue.

CONCLUSIONS

Ph has a protective effect against ischemia/reperfusion injury created experimentally in rat brains.

How effective are alprostadil and hydrocortisone on reperfusion injury in kidney after distant organ ischemia?

BACKGROUND

After reestablishment of blood flow to ischemic limb recirculation of free radicals may cause ischemia-reperfusion injury in many organs. This study designed to investigate effects of hydrocortisone and alprostadil distant injury to kidneys by both measuring biochemical markers of oxidative stress and histopathologic examination in an experimental rat model of hind limb ischemia-reperfusion.

MATERIALS AND METHODS

This study conducted in Isfahan University of Medical Sciences during 2011-2012. Ischemia was established by infra renal aortic clamping for 60 min in 32 male Wistar rats. Animals were divided into those receiving alprostadil (group ischemia-reperfusion plus alprostadil (IR/A), n = 8), those receiving hydrocortisone (group ischemia-reperfusion plus hydrocortisone (IR/H), n = 8), control group (group ischemia-reperfusion (IR), n = 8), and sham group (n = 8). After 120 min of reperfusion both kidneys were removed. Levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) as indirect markers of oxidative injury was measured. Finally all data in different groups were compared using the analysis of variance (ANOVA) test by Statistical Package for Social Sciences (SPSS) version 16.

RESULTS

Administration of alprostadil or hydrocortisone does not improve the biochemical parameters of oxidative injury including MDA and SOD. However, statistically significant difference was seen in GSH level among sham and IR groups. Mean (± standard deviation (SD)) concentration of GSH in IR, IR/A, IR/H, and sham groups were 1028.77 (72.65), 924.82 (70.66), 1000.28 (108.77), and 846.69 (163.52), respectively (P = 0.015). Histopathological study of specimens did not show any significant changes between groups.

CONCLUSION

Alprostadil and hydrocortisone do not improve the kidney GSH, SOD, and MDA level and kidney releases its GSH reserve during ischemia-reperfusion event, and another point is that, 3 h of ischemia-reperfusion does not develop injury in kidney.

Assessment of Protective Effects of Pheniramine Maleate on Reperfusion Injury in Lung After Distant Organ Ischemia

Objective:

The aim of this study is to investigate the protective effects of methylprednisolone (MP) and pheniramine maleate (PM) on reperfusion injury of lungs developing after ischemia of the left lower extremity of rats.

Materials and methods:

A total of 28 randomly selected male rats were divided into 4 groups, each consisting of 7 rats. Group 1 was the control group. Group 2 was the sham group (ischemia/reperfusion [I/R]). Rats in group 3 were subjected to I/R and given PM (Ph group) and rats in group 4 were subjected to I/R and given MP (Pn group).

Results:

Malondialdehyde levels were significantly lower in Ph group than in I/R group ( P < .05). Superoxide dismutase and glutathione peroxidase enzyme activities were found to be significantly higher in Ph group than in the I/R group ( P < .05). Histological examination demonstrated that PM had protective effects against I/R injury. Conclusions: The PM has a protective effect against I/R injury in rat lung.

Protective effect of methylprednisolone on warm ischemia-reperfusion injury in a cholestatic rat liver

BACKGROUND

Cholestasis has been identified as a risk factor for oxidative stress, and it potentially enhances after ischemic-reperfusion injury. The aim of this study was to evaluate the role of methylprednisolone on warm ischemia-reperfusion injury in the presence of cholestasis.

METHODS

A reversible cholestatic rat model was created. After 7 days, rats received 30 mg/kg of intravenous methylprednisolone 2 hours before ischemia, followed by 30 minutes of ischemia. Rats were euthanized 24 hours after ischemia. Serum aspartate aminotransferase and interleukin-6 were measured, and the liver was harvested for histology and myeloperoxidase estimation.

RESULTS

Methylprednisolone had a protective effect, with a statistically significant decrease in aspartate aminotransferase (P=.01) and a trend toward decreased levels of interleukin-6 (P=.07). Histology showed a significant difference in architectural distortion (P=.01), cytoplasmic vacuolation (P=.01), and nodular hepatocellular necrosis (P=.04).

CONCLUSIONS

Methylprednisolone attenuated the ischemic-reperfusion injury in the presence of cholestasis and can be considered for clinical use in the presence of cholestasis.

Rapamycin inhibits cholangiocyte regeneration by blocking interleukin-6-induced activation of signal transducer and activator of transcription 3 after liver transplantation

Cholangiocyte proliferation is necessary for biliary recovery from cold ischemia and reperfusion injury (CIRI), but there are few studies on its intracellular mechanism. In this process, the role of rapamycin, a new immunosuppressant used in liver transplantation, is still unknown. In order to determine whether rapamycin can depress cholangiocyte regeneration by inhibiting signal transducer and activator of transcription 3 (STAT3) activation, rapamycin (0.05 mg/kg) was administered to rats for 3 days before orthotopic liver transplantation. The results indicated that cholangiocytes responded to extended cold preservation (12 hours) with severe bile duct injures, marked activation of the interleukin-6 (IL-6)/STAT3 signal pathway, and increased expression of cyclin D1 until 7 days after transplantation, and this was followed by compensatory cholangiocyte regeneration. However, rapamycin treatment inhibited STAT3 activation and resulted in decreased cholangiocyte proliferation and delayed biliary recovery after liver transplantation. On the other hand, rapamycin showed no effect on the expression of IL-6. We conclude that the IL-6/STAT3 signal pathway is involved in initiating cholangiocytes to regenerate and repair CIRI. Rapamycin represses cholangiocyte regeneration by inhibiting STAT3 activation, which might have a negative effect on the healing and recovery of bile ducts in grafts with extended cold preservation. Insights gained from this study will be helpful in designing therapy using rapamycin in clinical patients after liver transplantation.

Effects of cytochrome p450 inhibition by cimetidine on the warm hepatic ischemia-reperfusion injury in rats

BACKGROUND

Cimetidine is an H(2)-antagonist with cytochrome P450 (P450) inhibitory activity. Recent studies showed that cimetidine improves warm ischemia-reperfusion (IR) injury in isolated rat heart and rabbit lung and in primary cultures of rat proximal tubule epithelial cells by inhibiting P450-mediated reactive oxygen species generation. Here, we studied the effects of cimetidine on the warm IR injury in the liver.

METHODS

Three groups of rats were treated with a single i.p. dose (0.6 mmol/kg) of cimetidine or ranitidine (an H(2) antagonist without a significant P450 inhibitory activity) or with saline 1.5 h before surgery. Livers were then subjected to 1 h of in vivo ischemia, followed by 1 h of ex vivo reperfusion using a physiologic buffer in a recirculating manner. A fourth group of animals, receiving saline pretreatment underwent sham operation instead of ischemia. Perfusate and bile samples were collected during the reperfusion, and the liver tissue was collected at the end of reperfusion period for measurement of various biochemical markers.

RESULTS

Warm IR resulted in a significant increase in the perfusate concentrations of liver enzymes (3- to 4.5-fold) and hepatic concentrations of lipid hydroperoxides (2-fold). Whereas the glutathione concentrations in the liver tissue were not affected by IR injury, the injury caused a significant decrease ( approximately 40%) in the biliary glutathione excretion. Cimetidine treatment completely or partially reversed all the IR-mediated changes, while ranitidine was ineffective. The protective effects of cimetidine were associated with a 60% decline in the microsomal CYP2C11 activity.

CONCLUSIONS

Whereas cimetidine, an H(2) blocker with substantial P450 inhibitory activity, is protective in warm IR injury, ranitidine, a similar drug with no significant P450 inhibitory activity, is devoid of any protective effects. Therefore, P450 inhibition appears to be the underlying mechanism in the protective effects of cimetidine in this model of IR injury.