FK 506 pre-treatment is associated with reduced levels of tumor necrosis factor and interleukin 6 following hepatic ischemia/reperfusion

Microtubule-Actin Crosslinking Factor 1 and Plakins as Therapeutic Drug Targets

Plakins are a family of seven cytoskeletal cross-linker proteins (microtubule-actin crosslinking factor 1 (MACF), bullous pemphigoid antigen (BPAG1) desmoplakin, envoplakin, periplakin, plectin, epiplakin) that network the three major filaments that comprise the cytoskeleton. Plakins have been found to be involved in disorders and diseases of the skin, heart, nervous system, and cancer that are attributed to autoimmune responses and genetic alterations of these macromolecules. Despite their role and involvement across a spectrum of several diseases, there are no current drugs or pharmacological agents that specifically target the members of this protein family. On the contrary, microtubules have traditionally been targeted by microtubule inhibiting agents, used for the treatment of diseases such as cancer, in spite of the deleterious toxicities associated with their clinical utility. The Research Collaboratory for Structural Bioinformatics (RCSB) was used here to identify therapeutic drugs targeting the plakin proteins, particularly the spectraplakins MACF1 and BPAG1, which contain microtubule-binding domains. RCSB analysis revealed that plakin proteins had 329 ligands, of which more than 50% were MACF1 and BPAG1 ligands and 10 were documented, clinically or experimentally, to have several therapeutic applications as anticancer, anti-inflammatory, and antibiotic agents.

Design and physicochemical characterization of advanced spray-dried tacrolimus multifunctional particles for inhalation

The aim of this study was to design, develop, and optimize respirable tacrolimus microparticles and nanoparticles and multifunctional tacrolimus lung surfactant mimic particles for targeted dry powder inhalation delivery as a pulmonary nanomedicine. Particles were rationally designed and produced at different pump rates by advanced spray-drying particle engineering design from organic solution in closed mode. In addition, multifunctional tacrolimus lung surfactant mimic dry powder particles were prepared by co-dissolving tacrolimus and lung surfactant mimic phospholipids in methanol, followed by advanced co-spray-drying particle engineering design technology in closed mode. The lung surfactant mimic phospholipids were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-[phosphor-rac-1-glycerol]. Laser diffraction particle sizing indicated that the particle size distributions were suitable for pulmonary delivery, whereas scanning electron microscopy imaging indicated that these particles had both optimal particle morphology and surface morphology. Increasing the pump rate percent of tacrolimus solution resulted in a larger particle size. X-ray powder diffraction patterns and differential scanning calorimetry thermograms indicated that spray drying produced particles with higher amounts of amorphous phase. X-ray powder diffraction and differential scanning calorimetry also confirmed the preservation of the phospholipid bilayer structure in the solid state for all engineered respirable particles. Furthermore, it was observed in hot-stage micrographs that raw tacrolimus displayed a liquid crystal transition following the main phase transition, which is consistent with its interfacial properties. Water vapor uptake and lyotropic phase transitions in the solid state at varying levels of relative humidity were determined by gravimetric vapor sorption technique. Water content in the various powders was very low and well within the levels necessary for dry powder inhalation, as quantified by Karl Fisher coulometric titration. Conclusively, advanced spray-drying particle engineering design from organic solution in closed mode was successfully used to design and optimize solid-state particles in the respirable size range necessary for targeted pulmonary delivery, particularly for the deep lung. These particles were dry, stable, and had optimal properties for dry powder inhalation as a novel pulmonary nanomedicine.

Anti-Ischemic Effect of Selectin Blocker Through Modulation of Tumor Necrosis Factor-α and Interleukin-10

BACKGROUND

Preliminary studies in our laboratories indicate that a recently discovered synthetic drug, TBC-1269, acts as a multiple selectin blocker and provides protection against tissue damage in rats that are subjected to severe liver ischemia/reperfusion. Here, we report that this effect is dose and time dependent, with its effects acting through the modulation of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70-80%) hepatic ischemia and 3 h of reperfusion were divided into eight groups (n=6/group): sham, ischemic control (IC), three groups of TBC-1269-treated animals at different concentrations (10, 20, 40, mg/kg) and another three groups of TBC-1269 given at 40 mg/kg at different times of administration: 15 min prereperfusion but after ischemia (no pretreatment), at the time of reperfusion, and at 15 min after reperfusion. The parameters measured at 3 h of reperfusion included liver function tests (alanine aminotransferase and aspartate aminotransferase), histopathology analysis and measurements using enzyme-linked immunosorbent assay in serum of TNF-alpha and IL-10. Statistical analysis included analysis of variance with P values of <0.05 for significance. Results were expressed as mean +/- SD.

RESULTS

The liver function tests showed statistically significant differences between the ischemic control group and both the sham group and the group treated with 40 mg/kg at the time of reperfusion (40@RP). These results correlated well with the histopathological analysis in that we found no difference in vacuolization, congestion, and necrosis between the 40@RP group and the sham group. The TNF-alpha and the IL-10 also reflected the protection observed in histopathology, with a decrease in TNF- alpha from the high levels observed in the IC (32 +/- 2.32 pg/mL) to a lower level of 8.5 +/- 4.04 mg observed in the 40@RP group, and an increment in the levels of the protective IL-10 from 2.8 +/- 2.9 pg/mL in the IC group versus 37.9 +/- 11.6 pg/mL in the 40@RP treated group (P<0.05). Lower doses and different times of administration of TBC-1269 did not show a protective effect. The IC group showed no difference in damage by histopathology or liver enzymes compared to the rest of the groups, except the 40@RP group.

CONCLUSION

In this work, we demonstrated that the small molecule multiple selectin inhibitor (TBC-1269) offered significant protection for the ischemic liver when given at 40 mg/kg at the time of perfusion. Lower doses and different times of administration did not show the optimal drug effect. The protection observed in the liver function tests (alanine aminotransferase and aspartate aminotransferase) and histopathology in this group was also reflected in the significant decrease in serum TNF-alpha and equally significant increase in serum protective IL-10.

Ryanodine receptor antagonism protects the ischemic liver and modulates TNF-alpha and IL-10

BACKGROUND

Dantrolene is a ryanodine receptor and intracellular calcium antagonist. The ryanodine receptor (RyR) Ca(2+) release channel mobilizes Ca(2+) from internal stores to support a variety of cellular functions, including the inflammatory response after ischemia and reperfusion. The pharmacological mechanism of dantrolene is associated with the inhibition of the release of Ca(2+) from the skeletal muscle sarcoplasmic reticulum (SR). We hypothesized that dantrolene could exert a protective effect in our model of liver ischemia and reperfusion by modulating TNF-alpha and IL-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70 to 80%) hepatic ischemia and 3 h of reperfusion were divided into five groups (n = 6/group): sham, ischemic control, and the dantrolene 1 mg/kg group studied at three times of administration: 15 min before reperfusion (DAN-PRE), at the time of reperfusion (DAN-RP), and 15 min after reperfusion (DAN-POS). The parameters measured at 3 h of reperfusion included serum liver function tests alanine aminotransferase (ALT) and aspartate aminotransferase (AST), TNF-alpha, and IL-10 in serum and liver histology.

RESULTS

It was demonstrated that the RyR intracellular calcium antagonist dantrolene offered the most significant protection for the ischemic liver when given before reperfusion and at the time of reperfusion. AST significantly differed between the control group and the DAN-PRE and DAN-RP groups (P < 0.05). ALT showed a statistically significant decrease in the DAN-PRE treated group and a decrease, although not significant, in the DAN-RP. Histological examination demonstrated a significant decrease in vacuolization in the same both groups (P < 0.05). Necrosis was significantly diminished when dantrolene was used at the time of reperfusion; congestion decreased in the same groups but without statistical significant difference. The levels of TNF-alpha were significantly decreased in the DAN-RP group. There was a decrease in TNF-alpha in the DAN-PRE group but not statistically significant. IL-10 reflected the protection observed in necrosis and vacuolization in the histopathology with an increment at the time of reperfusion (P < 0.05). DAN-POS did not exert a protective effect in ALT, AST, liver histology, or cytokine response.

CONCLUSION

For the first time the ryanodine receptor antagonist dantrolene offered significant functional and structural protection of the ischemic liver when given at the time for reperfusion and partial protection when given prereperfusion. RyR inhibition approach down-regulated the expression of TNF-alpha and induced an increment of the protective cytokine IL-10 when administered at the time of reperfusion. There was no protective effect of dantrolene after reperfusion.

FK506 Controls CD40L-Induced Systemic Autoimmunity in Mice

Autoimmunity results from loss of mechanisms controlling self-reactivity. Autoimmune disorders play an increasingly important role and CD40-CD40 ligand (CD40L) interaction on immunocompentent cells is able to break established immunotolerance. To study the effects of the calcineurin-inhibitor FK506 on CD40L-induced systemic autoimmunity, CD40L transgenic (tg) mice, which spontaneously develop a mixed connective tissue-like disease, were treated with FK506 after onset of overt autoimmunity. Interestingly, FK506-treated CD40L tg mice showed significantly reduced autoimmune dermatitis scores and markedly decreased numbers of lesional infiltrating leukocytes. This finding was associated with diminished lymphadenopathy induced by FK506 treatment. Furthermore, FK506 suppressed the development of cytotoxic/autoreactive CD8(+) T cells as evidenced by the reduced expression of T cell activation markers in treated CD40L tg mice. Importantly, FK506 induced a significant reduction in autoantibody titers in the serum of CD40L tg animals. As CD40L tg mice develop nephritis leading to loss of renal function proteinuria was determined after FK506 injections. Notably, FK506 treatment re-established renal function as indicated by significantly reduced uric protein concentrations of treated CD40L tg mice. Together, these findings show the beneficial therapeutic effects of FK506 for the treatment of CD40L-induced autoimmunity. Additionally, these results demonstrate that FK506 is able to suppress ongoing severe autoimmune responses.

Mild hypothermia enhances the neuroprotective effects of FK506 and expands its therapeutic window following transient focal ischemia in rats

FK506 (tacrolimus), an immunosuppressant, reportedly reduces ischemic brain injury following transient middle cerebral artery occlusion (MCAO) in rats. The authors previously reported that the therapeutic window of FK506 in this model is more than 1 h, but less than 2 h. The aim of the present study is to determine whether mild hypothermia (35 degrees C) enhances the neuroprotective effects of FK506 and expands its therapeutic window. Sprague-Dawley rats were subjected to 2 h MCAO followed by 24 h reperfusion. Animals were randomly divided into four groups: (I) vehicle-treated normothermic group; (II) FK506-treated normothermic group; (III) vehicle-treated hypothermic group; (IV) FK506-treated hypothermic group. Animals received a single injection of FK506 (0.3 mg/kg) or vehicle intravenously at 2 h after ischemic induction. During ischemia, temporal muscle and rectal temperatures were maintained at 37 degrees C in the normothermic animals and at 35 degrees C in the hypothermic animals. Infarct volumes and neurological performance were evaluated at 24 h after reperfusion. The combination of FK506 and mild hypothermia significantly reduced infarct volume (cortex, -61%; striatum, -31%) and edema volume (cortex, -57%; striatum, -41%), while mild hypothermia or FK506 alone failed to improve ischemic brain damage. Furthermore, this combination also provided for the best functional outcome. These results demonstrate that the combination of FK506 and mild hypothermia significantly reduces ischemic brain damage following transient MCAO in rats, and expands the therapeutic window for FK506. This therapy may be a new approach for treatment of acute stroke.

Effect of FK506 (tacrolimus) in animal models of inflammation

Inflammation is the response of living tissue to damage. Cytokines play an important role in inflammatory processes. FK506 (tacrolimus), an immunosuppressant, is known to reduce the activation of microglia in vitro and affect the expression of various cytokines like interleukin-1, interleukin-6 and tumor necrosis factor. With this background the present study was designed to explore the effect of FK506 in animal models of acute inflammation and experimental pleurisy. Acute inflammation in rats was induced by intraplantar injection of carrageenan (1%, w/v). Experimental pleurisy was induced in rats by intrapleural injection of carrageenan (2%, w/v). Pretreatment with FK506 (0.5-3 mg/kg p.o.) significantly and dose-dependently reduced carrageenan-induced increase in paw volume, as well as carrageenan-induced inflammatory nociception. FK506 (1 and 3 mg/kg p.o.) inhibits exudate formation and migration of polymorhonuclear leukocytes and monocytes in carrageenan-induced experimental pleurisy. The myeloperoxidase enzyme level was significantly increased in carrageenan-treated animals, which was significantly reversed by FK506 treatment. The results of the present study suggest the potential anti-inflammatory properties of FK506 against carrageenan-induced acute inflammation and experimental pleurisy.

Auxiliary partial orthotopic liver transplantation for fulminant hepatitis: regeneration of the diseased native liver in a pig model

BACKGROUND

This study was performed to develop a clinically relevant porcine model of auxiliary partial orthotopic liver transplantation (APOLT) for fulminant hepatic failure.

METHODS

FHF was induced by intraportal administration of alpha-amanitin and lipopolysaccharide. Thereafter, pigs were divided into four groups. Group 1 was an untreated, control group. In group 2, pigs underwent only a left hemihepatectomy. Pigs in groups 3 and 4 received APOLT after hemihepatectomy. Tacrolimus was administered to pigs in group 4, but not to those in group 3.

RESULTS

Two-week survival rates were 0%, 20%, 40%, and 100% for groups 1, 2, 3, and 4, respectively. In group 4, after abolishing the graft function at 1 week, pigs survived for more than 2 weeks, and regeneration of the native liver was confirmed histologically.

CONCLUSIONS

Pigs suffering from fulminant hepatic failure could achieve long survival and liver regeneration with a temporary support of the auxiliary graft.

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.

Tacrolimus as a liver flush solution to ameliorate the effects of ischemia/reperfusion injury following liver transplantation

The goal of this report is to evaluate in a prospective randomized fashion the effect of flushing hepatic allografts with tacrolimus before transplantation. A prospective, double-blinded, randomized trial was performed. Twenty patients receiving orthotopic liver transplants from October 2000 to October 2001 were randomized into two groups. Group 1 (active) was administered tacrolimus, 20 ng/mL, plus Plasma-lyte A (Baxter Healthcare Corp, Deerfield, IL) liver flush solution; and group 2 (placebo) was administered only Plasma-lyte A. Ischemia/reperfusion injury was assessed in both groups after transplantation by means of serum laboratory values to assess hepatocellular damage, synthetic function, and ion transport capacity. Peak values were recorded for each parameter, and their distributions were compared. There were no statistically significant differences between groups for age, sex, total ischemia time, or cause of liver disease. Global multivariate comparison of peak changes in all measures of liver function indicated liver injury was significantly lower with tacrolimus treatment than placebo (P =.01). The sample median for group 1 was less than for group 2 in all parameters measured. Individual statistical comparison showed that peak changes from baseline aspartate aminotransferase and activated partial thromboplastin time values were significantly improved (P </=.05) with tacrolimus treatment than placebo treatment. In this prospective, double-blinded, randomized trial, we show that flushing the liver before transplantation with Plasma-lyte A containing tacrolimus results in superior early graft function and decreased hepatocellular injury after reperfusion compared with flushing with Plasma-lyte A alone.

Prostaglandin E1 improved the function of transplanted fatty liver in a rat reduced-size-liver transplantation model under conditions of permissible cold preservation

The aim of this study was to determine whether the minimum necessary volume of a moderate fatty liver graft was similar to the normal liver volume and to elucidate means for improving the function of the transplanted fatty liver if it were inferior in volume to a normal liver under conditions of permissible cold preservation. Nine-week-old male Wistar rats were used. Normal rat chow was fed to the normal liver group, and fat-enriched rat chow was fed to the fatty liver group for 4 weeks to induce a moderately fatty liver. Liver transplantation with various volumes of reduced-size grafts, including whole liver graft (100%LT), 70% volume graft (70%LT), and 30% volume graft (30%LT), was performed with both groups of rats as donors. All procedures were performed under the conditions of 2-hour cold preservation. All rats with an implanted normal liver were surviving at 7 days after the operation regardless of the graft volume (100%LT, 5 of 5; 70%LT, 5 of 5; 30%LT, 5/5). In contrast, the survival rates decreased according to the graft volume in rats implanted with fatty livers (100%LT, 8 of 8; 70%LT, 5 of 8; 30%LT, 2/8). To improve the survival of 30%LT with fatty liver, we employed two potent inhibitors of ischemia-reperfusion injury: FK506 and prostaglandin E1. Though FK506 had no advantageous effect, prostaglandin E1 significantly improved the survival rate and diminished serum levels of alanine aminotransferase and hyaluronic acid. In conclusion, the volume of graft necessary for successful transplantation is larger in fatty livers than in normal livers in permissible cold preservation. Also, prostaglandin E1 protects grafts against ischemia-reperfusion injury and improves the functioning of a transplanted fatty liver.

Effect of tacrolimus on endotoxin-induced lung injury in sheep

Since tacrolimus (FK-506) is known to suppress the proliferation and generation of T cells and to inhibit the production of T cell derived cytokines, we examined the effect of FK-506 on endotoxin-induced lung injury. We administered FK-506 (0.1 mg/kg) intravenously before the infusion of endotoxin (1 microgram/kg) into conscious sheep. We measured pulmonary hemodynamics, lung fluid balance, circulating leukocyte count and arterial blood gas tensions. The increase in pulmonary arterial pressure was significantly attenuated by FK-506 during the late period (3-5 h after endotoxin). Arterial oxygen gas tension was significantly higher in the FK-506 treated sheep during this phase. However, no significant differences were observed in lung lymph balance and circulating leukocyte count between the endotoxin alone group and the FK-506 treated group. These findings suggest that FK-506 may improve gas exchange in acute lung injury although there is an increased pulmonary vascular leakage. It is probable that FK-506 may have a beneficial potential on endotoxin-induced lung injury in sheep.

Rat liver injury after normothermic ischemia is prevented by a phosphinic matrix metalloproteinase inhibitor

Hepatic ischemia occurs in liver transplantation, hemodynamic or cardiogenic shock, and liver resection associated with trauma or tumor. Ischemia/reperfusion (I/R) injury results in microcirculation failure followed by apoptosis and necrosis. Matrix metalloproteinases (MMPs) are involved in many physiological and pathological processes, but their expression and function during liver I/R remains poorly documented. In this study, we evaluated the expression of nine MMPs and their natural inhibitors, tissue inhibitors of MMPs (TIMPs), in a rat model of liver I/R. Analysis of MMP and TIMP expression show that although most of these genes are not constitutively expressed in the normal liver, they are induced in a specific time-dependent manner following I/R. Stromelysin-1, gelatinase B, and collagenase-3 are induced during the early phase of acute liver injury associated with inflammation and increased necrosis/apoptosis, whereas gelatinase A, membrane type-MMP, stromelysin-3, metalloelastase, TIMP-1, and TIMP-2 are essentially detectable during the recovery phase of liver injury corresponding to hepatocyte regeneration. This observation suggested that MMPs and TIMPs could play both deleterious and beneficial roles following I/R. We thus tested the effect of a specific phosphinic MMP inhibitor on acute liver I/R injury. Inhibition of MMP activity was shown to significantly decrease liver injury in ischemic/reperfused liver tissue as assessed by histological studies and serum hepatic enzyme levels. We therefore propose that MMP inhibitors may be of clinical relevance in liver-associated ischemic diseases or after liver transplantation.

Effects of endotoxin tolerance on liver function after hepatic ischemia/reperfusion injury in the rat

OBJECTIVE

It is known that endotoxin tolerance prevents lethality after ischemia/reperfusion injuries (e.g., myocardial infarction) in laboratory animals. We used a rat model of partial hepatic ischemia/reperfusion to investigate whether endotoxin tolerance prevents associated lethality and disorders of liver function.

DESIGN

Prospective animal study.

SETTING

University research facility.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Hepatic ischemia was initiated by atraumatic clipping across the portal venous and hepatic arterial blood supply to the left lateral lobe for 90 mins. The common bile duct was canalized, and in a second set of experiments the bile duct of the left lateral lobe was canalized selectively. Bile flow, bile acids, and transaminases were determined during ischemia and 300 mins of reperfusion in endotoxin-tolerant and -nontolerant rats.

MEASUREMENTS AND MAIN RESULTS

Endotoxin-nontolerant animals showed a 50% lethality after hepatic ischemia/reperfusion injuries. All endotoxin-tolerant rats survived and did not react with any change in bile flow, showing a constant flow. The amount of bile acids in the common bile duct was reduced during ischemia and regained the concentrations of sham-operated animals 60 mins after reperfusion. From 180 mins after reperfusion, the difference between endotoxin-tolerant and -nontolerant animals was statistically significant. When bile acid concentration was determined in the ischemic left lateral lobe, ischemia/reperfusion was found to significantly decrease in endotoxin-nontolerant rats 60 mins after reperfusion. In contrast, endotoxin-tolerant rats produced normal amounts of bile acids 60 mins after reperfusion. At 120 mins after reperfusion, the amount of bile acids in the formerly ischemic left lateral lobe was more than normal.

CONCLUSIONS

In this model of partial hepatic ischemia/reperfusion, endotoxin tolerance prevents ischemia/reperfusion injury-associated lethality and local disorders of liver function. This phenomenon induced by endotoxin tolerance may be useful in liver surgery to prevent ischemia/reperfusion injury.

Endotoxins and cytokines during liver transplantation: changes in plasma levels and effects on clinical outcome

Endotoxins, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and IL-6 are believed to have a key role in liver transplantation. The origin and course of these factors is not completely known. In this prospective study of 40 patients, we sought more understanding of the relations between these factors and their effects on clinical outcome by sampling at different sites. Endotoxemia was only present in 20% of the patients. In 75% of these patients, it was present during the anhepatic phase and quickly resolved after reperfusion. Endotoxemia was not related to a clinical adverse event. TNF-alpha was released from the graft after reperfusion, and initial levels after reperfusion were related to predonation levels in the donor. Only levels of TNF-alpha in the recipient before transplantation were found to be predictive of postoperative complications. We conclude that monitoring endotoxins and these cytokines is of very limited value in predicting outcome.

Increased monocyte nuclear factor-kappaB activation and tumor necrosis factor production in alcoholic hepatitis

Increased tumor necrosis factor-a activity has been reported in patients with alcoholic hepatitis and is implicated in its pathogenesis. The aim of this study was to investigate potential mechanisms of increased tumor necrosis factor-a activity in alcoholic hepatitis. Monocyte nuclear factor-kB activity was assessed by electrophoretic mobility shift assay, monocyte tumor necrosis factor-a mRNA was semi-quantitatively assessed by reverse transcriptase polymerase chain reaction, and tumor necrosis factor-a in monocyte culture supernatants was measured. There was significantly greater spontaneous nuclear factor-kB activity in the monocytes of 6 patients with alcoholic hepatitis as compared with that in the monocytes of control subjects. There was spontaneous tumor necrosis factor-a mRNA and tumor necrosis factor-a release from the monocytes of patients with alcoholic hepatitis but not from the monocytes of normal subjects. Endotoxin increased nuclear factor-kB activity and induced tumor necrosis factor-a mRNA and tumor necrosis factor-a release from normal subjects' monocytes. Endotoxin further increased nuclear factor-kB activity, tumor necrosis factor-a mRNA, and tumor necrosis factor-a release from the monocytes of patients with alcoholic hepatitis. Supershift assays indicate that the monocyte nuclear factor-kB activation involves the p50 and p65 subunits. Dysregulated tumor necrosis factor-a metabolism in alcoholic hepatitis monocytes is associated with increased nuclear factor-kB activity and tumor necrosis factor-a mRNA expression.

Modulating the functions of neutrophils and lipid peroxidation by FK506 in a rat model of thermal injury

Neutrophils diffusely invade lung, liver, kidney, intestine, muscle and burned skin following burn injury. To ameliorate this invasion and minimize its effects, neutrophils can be modulated by giving neutrophil inhibitors and modulators. In this study, FK506 was used to decrease neutrophil infiltration and lipid peroxidation in remote organs (lung, liver, kidney and intestine) in a burned rat model. FK506 is a new major immunosuppressive agent that is known to modulate neutrophils during inflammation. Neutrophil infiltration was assessed indirectly by measuring myeloperoxidase (MPO) activity biochemically in remote organs following 30% full thickness burn injury. Malondialdehyde (MDA), the end product of lipid peroxidation, was measured biochemically in remote organs and plasma to determine if there is a relationship between neutrophil infiltration and lipid peroxidation after burn injury. FK506 was given intramuscularly at the dose of 0.5 and 1.0 mg/kg for three days before burn injury. Thermal trauma to the skin caused a statistically significant increase in MPO activity and MDA content in remote organs. FK506 was effective in reducing lipid peroxidation and neutrophil infiltration especially at 24 h postinjury in lung, liver and kidney. FK506 may have some benefit (prophylactic) in reducing systemic neutrophilic injury and related lipid peroxidation in burns.

Treatment with glutathione precursor decreases cytokine activity

BACKGROUND

Inflammatory cytokine activity is increased in many forms of experimental and clinical liver injury including alcoholic liver disease (ALD). Monocytes and Kupffer cells produce cytokines such as tumor necrosis factor (TNF), interleukin (IL)-8, and IL-6 in response to stimuli such as endotoxin (lipopolysaccharide [LPS]). This cytokine production is regulated by the oxidative stress-sensitive transcription factor NFkappaB. Glutathione (GSH) prodrugs such as oxathizolidine-4-carboxylic acid (OTZ) can inhibit activation of NFkappaB and subsequent cytokine production in monocytes and Kupffer cells in vitro. The objective of this study was to treat stable cirrhotic patients with OTZ in vivo to evaluate its effects on monocyte cytokine production (TNF, IL-8, and IL-6) and whole blood GSH levels.

METHODS

Nine patients with stable cirrhosis received OTZ (70 mg/kg IV every 8 hours) for 9 days. Peripheral blood monocytes were obtained on study days 1 and 9, using density gradient centrifugation and adherence to plastic, and were stimulated with LPS (5 microg/mL). TNF, IL-8, and IL-6 were measured in culture supernatants by enzyme-linked serum immunosorbent assay. Whole blood GSH levels were measured by high-performance liquid chromatography.

RESULTS

There was a significant decrease in monocyte TNF, IL-8, and IL-6 production after OTZ therapy. Patients with cirrhosis had significantly lower admission whole blood GSH levels compared with controls and GSH normalized with OTZ administration.

CONCLUSIONS

Treatment with the GSH prodrug OTZ inhibited monocyte cytokine production and increased whole blood GSH. This may have important therapeutic implications for multiple cytokine-mediated disease processes.

Improvement of normothermic rat liver ischemia/reperfusion by muramyl dipeptide

Normothermic ischemia and reperfusion (I/R) of the liver remains a major problem after liver surgery and transplantation. Activation of Kupffer cells (KCs) after normothermic I/R is responsible for a massive release of various monokines such as tumor necrosis factor alpha (TNF-alpha) and a decrease in phagocytic activity. Muramyl dipeptide (MDP) is an immunostimulant that increases phagocytic activity of KCs. The aim of this study was to demonstrate that MDP pretreatment might protect the liver against I/R injury by a modification of KC functions. Rats were divided into three groups: group 1, control, Ringer's lactate administration; group 2, MDP (N-acetyl-muramyl-d-alanyl-d-isoglutamine) treatment; group 3, sham-operated control animals. MDP (500 microg/250 g) was injected intravenously 5 min before the induction of 90 min ischemia. Survival rates were compared and serum activities of TNF-alpha, aspartate aminotransferase, and alanine aminotransferase were assessed in the blood collected from the suprahepatic vena cava. Histology of the liver and KC activity were assessed 6 and 9 h after the end of ischemia, respectively. MDP treatment significantly increased 7-day survival (86.6%) compared with nontreated rats (40%, P < 0.001). Serum activities of TNF-alpha and aminotransferases were significantly decreased after MDP treatment, whereas phagocytic capacity of KCs was partially restored. The extent of liver necrosis was decreased after MDP administration. A significant difference was observed for other histological parameters studied, except for steatosis. Our findings have demonstrated that MDP is able to protect the liver from ischemic insult by modulation of KC activity (TNF-alpha release and phagocytic capacity). Control of macrophage activity may offer a new strategy to reduce ischemic injury of the liver.

Prolonged hepatic warm ischemia in non-heart-beating donors: protective effects of FK506 and a platelet activating factor antagonist in porcine liver transplantation

BACKGROUND

Prolonged warm ischemic injury in non-heart-beating donors (NHBDs) significantly affects hepatic allograft function after liver transplantation (LTx).

METHODS

The effects of FK506 and the platelet activating factor antagonist E5880 on postoperative function of hepatic allografts procured from NHBDs were evaluated in porcine orthotopic LTx. In donors, livers were subjected to 90 minutes of warm ischemia and a subsequent 4-hour cold preservation. Group 1 (n = 6) was the untreated control group. In group 2 (n = 4), donors were pretreated with FK506 (0.3 mg/kg). In group 3 (n = 4), donors and recipients were treated with E5880 (0.3 mg/kg). In group 4 (n = 6), pigs were treated with both FK506 and E5880.

RESULTS

All of the recipients in group 1 died within 12 hours. In groups 2 and 3, half of the recipients survived more than 12 hours. In group 4, all of the recipients survived more than 2 days (p < 0.01 compared with group 1). The improved survival seen in group 4 was associated with a reduction in the serum concentrations of glutamic oxaloacetic transaminase and lactate, and a restoration of hepatic energy charge.

CONCLUSIONS

The present study suggests that FK506 and E5880 can improve the function of hepatic allografts subjected to prolonged warm ischemia in NHBDs, and that the protective effects of the two drugs seem to be synergistic.

Postoperative fever, bowel ischaemia and cytokine response to abdominal aortic aneurysm repair--a comparison between endovascular and open surgery

OBJECTIVES

To study bowel ischaemia in transfemorally placed endoluminal grafting (TPEG) for abdominal aortic aneurysms, and any relation to cytokine response or postoperative fever.

DESIGN

Prospective not randomised. University hospital setting.

MATERIAL

Fourteen cases of conventional surgery and 23 cases of endovascular technique for infrarenal abdominal aortic aneurysm repair.

METHODS

Tonometry was used for sigmoid colon pH, and ELISAs for serum IL-6.

RESULTS

Mucosal pH in the sigmoid colon fell significantly during clamping and reperfusion in both groups. Lowest measured sigmoid colon pH was 7.10 in the open group, compared to 7.22 in the TPEG group (p < 0.05). The IL-6 levels in serum peaked after 4 h of reperfusion; 249 pg/ml in the open group, compared to 89 pg/ml in the TPEG group (p < 0.05). High levels of IL-6 in the postoperative period and persisting low sigmoidal pH were associated with serious complications. Postoperative temperature did not differ significantly between the groups, and no significant correlation could be found with sigmoid colon pH or IL-6 levels.

CONCLUSIONS

The less pronounced perioperative bowel ischaemia in TPEG patients indicates an advantage of the TPEG technique. Splanchnic ischaemia was not related to postoperative fever, nor the IL-6 or TNF response.

Immunopharmacologic agents in the amelioration of hepatic injuries

A number of immunomodulating agents of different origin have been shown to reduce liver injury of various etiologies. Immunostimulants like levamisole, BCG, a protein polysaccharide from myceria Coriolus vesicolor PS-K, a streptoccocal preparation OK-432 and immunomodulators like N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) and its analogs. Selective T-cell suppressors like the polypeptide cyclosporine A (CsA) and the macrolide FK 506 (tacrolimus) have also been claimed to possess hepatoprotrophic or hepatoprotective properties at low doses. The aim of this review article is to highlight the interplay between the administration of immunomodulating agents and the amelioration of hepatic injuries. Hepatic effects of exogenous immunomodulators are discussed with special focus on the most widely used immunosuppressive agents, CsA and tacrolimus. An important question exists as to whether these potential hepatoprotective effects are related mechanistically to the immune system or are working at different levels. Due to the differences in effects and modes of actions of various immunoactive substances presented herein, a common mechanism for their cytoprotective effects cannot be formulated at this stage. Levamisole and cyanidanol may protect cells against necrosis by acting as free radical scavengers. MDP and its analogs reduce carbon tetrachloride-elevated (CCl4) lipid peroxides and their protective effects are primarily on hepatic cytoplasmic membranes where lipid peroxidation and calcium homeostasis interact. MDP reduced CCl4-elevated calcium in both intact hepatocytes and in the post microsomal supernatant suggest that the influx of extracellular calcium across plasma membrane is affected. Elevations of intracellular calcium above a threshold are involved in: the stimulation of Ca2+-sensitive enzymes such as phospholipase A2, endonucleases and proteases, the conversion of xanthine dehydrogenase to xanthine oxidase and the formation of free radicals, all of which disturb biomembranes. MDP and its analogs, in a specific dose range, may act to maintain intracellular calcium within physiological ranges. Highly complex cellular signalling systems, including calcium, are involved in the explanation of the mechanism of the immunosuppressive effect of CsA and tacrolimus. The hepatoprotective effects of these selective immunosuppressive agents, however, are independent of the inhibition of T-cell activation. The cyclophilin and tacrolimus binding proteins of the mitochondria are the receptors for these compounds and play a key role in the regulation of mitochondrial permeability transition pores. CsA or tacrolimus inhibition of mitochondrial permeability transition pores does not require interaction with calcineurin, indicating a dissociation between immunosuppression and mitochondrial protection. The involvement of intracellular or intramitochondrial proteins in the modulation of mitochondrial permeability transition pores with the creation of a partially impermeable state for Ca2+ movement in drug-treated mitochondria and the dissociation of this effect from immunomodulatory actions potentially offers new and promising approaches for the development of new pharmacologicals targeted at therapeutic intervention. Clinical trials of these drugs as hepatoprotective agents are limited. Use of CsA in patients with primary biliary cirrhosis and autoimmune chronic hepatitis and in cirrhotic animal models produced by chronic administration of CCl4 have yielded encouraging results. It seems that this class of compounds may be of substantial benefit in liver protection against many pathological conditions where disturbance in mitochondrial function and in Ca2+ homeostasis appear to be prerequisites for cell injury.

Immunosuppressants decrease neutrophil chemoattractant and attenuate ischemia/reperfusion injury of the liver in rats

BACKGROUND

Neutrophils may play an important role in the development of liver ischemia/reperfusion injury. We investigated the effects of the immunosuppressants azathioprine (AZA), cyclosporine A (CsA), tacrolimus (FK506), and rapamycin (RPM) on the expression of cytokine-induced neutrophil chemoattractant (CINC) after ischemia/reperfusion of the liver.

METHODS

Liver ischemia was induced in male Wistar rats by occluding the portal vein with a microvascular clip for 30 minutes. Rats received two intramuscular injections of AZA (4 mg/kg), CsA (5 mg/kg), FK506 (0.5 mg/kg), or RPM (0.5 mg/kg) 3 and 24 hours before ischemia/reperfusion of the liver.

RESULTS

Serum CINC concentrations in untreated animals increased, peaked 6 hours after reperfusion, and thereafter decreased gradually. Pretreatment with AZA, CsA, FK506, and RPM, however, inhibited the increase in serum CINC concentrations after reperfusion. CINC mRNA in liver tissue increased and peaked 3 hours after reperfusion, but was significantly lower in animals treated with AZA, CsA, FK506, and RPM. In vitro CINC production by Kupffer cells harvested from animals treated with AZA, CsA, FK506, or RPM 3 hours after reperfusion was also significantly lower than that observed in untreated animals. Both myeloperoxidase activity and the number of neutrophils accumulating in the liver 24 hours after reperfusion in animals treated with AZA, CsA, FK506, and RPM were significantly lower than in untreated animals. This correlated with lower serum aspartate transaminase, alanine transaminase, and lactate dehydrogenase levels in animals treated with AZA, CsA, FK506, and RPM 24 hours after reperfusion.

CONCLUSION

The immunosuppressants AZA, CsA, FK506, and RPM reduce neutrophil accumulation and attenuate ischemia/reperfusion injury of the liver.

Post-ischaemic organ dysfunction: a review

OBJECTIVES

The aim of this review is to consider the pathophysiology of ischaemia-reperfusion in organs that may be affected by either its local or remote consequences. Potential therapeutic strategies are also considered.

DESIGN

A general discussion of the biochemical (including oxygen free radicals, complement, cytokines) and cellular events (endothelial cells, neutrophils) responsible for the mediation of reperfusion injury is presented, with special consideration of the organ-specific differences affecting the myocardium, central nervous system, gut, liver, kidney and skeletal muscle. Similarly, events which promote remote organ injury are described.

CONCLUSIONS

Although it is recognised that prolonged ischaemia results in tissue and organ damage, the concept of reperfusion-induced tissue injury, defined as tissue damage occurring as a direct consequence of revascularisation, is relatively recent. Such events may increase the morbidity and mortality of patients undergoing vascular reconstruction, trauma surgery and transplantation. A clear understanding of the factors responsible for its development is therefore vital if protocols that reduce its impact are to be developed.

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.

Effects of topical FK506 on endotoxin-induced uveitis (EIU) in the Lewis rat

FK506 is a macrolide antibiotic and a potent immunosuppressant. To investigate the effect of topical FK506 on acute ocular inflammation, we evaluated its action on the development of endotoxin-induced uveitis (EIU). At two different concentrations of 0.05% and 0.3%, topical FK506 was applied to Lewis rats with EIU. In aqueous, the mean number of inflammatory cells per microliter +/- SEM was 2,389 +/- 1,277, 1,571 +/- 1,562, 898 +/- 882, and 69 +/- 152 for rats treated with vehicle alone, 0.05%, 0.3% FK506, and 1% prednisolone acetate. The median of histological grades was 2, 1.5, 0.8, and 0.5 for animals treated with these 4 different regimens respectively. Analysis of aqueous protein showed a small reduction in FK506-treated animals. Mean blood levels of FK506 were low in rats treated with topical FK506 (0.05%, 0.84 ng/ml; 0.3%, 2.0 ng/ml) suggesting that its therapeutic effect was not secondary to the systemic absorption of the drug. Although FK506 is not as effective as prednisolone, 0.3% FK506 produced significant decreases in the mean aqueous inflammatory cell number and histological inflammatory score as compared to control vehicle alone. We conclude that topical FK506 can suppress EIU in a dose-dependent fashion and may be an alternative medication for patients with anterior uveitis and contra-indication to topical steroid.

Tacrolimus. A review of its pharmacology, and therapeutic potential in hepatic and renal transplantation

Tacrolimus (FK 506) is a macrolide immunosuppressant which possesses similar but more potent immunosuppressant properties compared with cyclosporin, inhibiting cell-mediated and humoral immune responses. Like cyclosporin, tacrolimus demonstrates considerable interindividual variation in its pharmacokinetic profile. This has caused difficulty in defining the optimum dosage regimen and has highlighted the usefulness of therapeutic drug monitoring. Most clinical studies with tacrolimus have neither been published in their entirety nor subjected to extensive peer review; there is also a paucity of published randomised investigations of tacrolimus versus cyclosporin, particularly in renal transplantation. Despite these drawbacks, tacrolimus has shown notable efficacy as a rescue or primary immunosuppressant therapy when combined with corticosteroids in adult and paediatric recipients following liver or kidney transplantation. Indeed, graft salvage rates in patients experiencing rejection or drug-related toxicity were > or = 50%, although data in renal transplantation are limited. Compared with cyclosporin as a primary immunosuppressant, tacrolimus showed comparable or greater patient/graft survival rates in liver allograft recipients (where cost savings associated with reduced hospitalisation costs were evident in one study), and comparable patient/graft survival in patients following kidney transplantation. Worthy of note was the efficacy of tacrolimus as a primary immunosuppressant in patients who received en bloc kidney allografts. The incidence of rejection was largely reduced following rescue therapy with tacrolimus and was generally lower (notably for refractory rejection) than that observed for cyclosporin, at least in liver allograft recipients. This was reflected in less need for adjunct immunotherapy including antilymphocyte preparations for the treatment of rejection episodes. The potential for reduction or withdrawal of corticosteroid therapy with tacrolimus appears to be a distinct advantage compared with cyclosporin, and this may be enhanced by the reduced incidence of infectious complications and of hypertension and hypercholesterolaemia reported by some investigators. In other respects, however, the tolerability profile of tacrolimus appears to be broadly similar to that of cyclosporin. Against this background, preliminary data indicate that tacrolimus provides a valuable therapeutic alternative to retransplantation in patients experiencing liver or kidney graft rejection or drug-related toxicity. Pending confirmation of initial randomised studies and preliminary results from large randomised investigations, tacrolimus may well be considered as an alternative primary immunosuppressant to cyclosporin in hepatic (particularly) and renal transplantation. Furthermore, the steroid-sparing effects of tacrolimus, although of benefit to all patient groups, may prove to be of particular worth in children and in en bloc kidney recipients. In these patients tacrolimus may well emerge as the drug of choice.(ABSTRACT TRUNCATED AT 400 WORDS)