Splenectomy ameliorates hepatic ischemia and reperfusion injury mediated by heme oxygenase-1 induction in the rat

Splenectomy is associated with altered leukocyte kinetics after severe trauma

BACKGROUND

Inadequate activation of the innate immune system after trauma can lead to severe complications such as Acute Respiratory Distress Syndrome and Multiple Organ Dysfunction Syndrome. The spleen is thought to modulate the cellular immune system. Furthermore, splenectomy is associated with improved outcome in severely injured trauma patients. We hypothesized that a splenectomy alters the cellular immune response in polytrauma.

METHODS

All adult patients with an ISS ≥ 16 and suffering from splenic or hepatic injuries were selected from our prospective trauma database. Absolute leukocyte numbers in peripheral blood were measured. White blood cell kinetics during the first 14 days were compared between splenectomized patients, patients treated surgically for liver trauma and nonoperatively treated individuals.

RESULTS

A total of 129 patients with a mean ISS of 29 were included. Admission characteristics and leukocyte numbers were similar in all groups, except for slightly impaired hemodynamic status in patients with operatively treated liver injuries. On admission, leukocytosis occurred in all groups. During the first 24 h, leukopenia developed gradually, although significantly faster in the operatively treated patients. Thereafter, leukocyte levels normalized in all nonoperatively treated cases whereas leukocytosis persisted in operatively treated patients. This effect was significantly more prominent in splenectomized patients than all other conditions.

CONCLUSIONS

This study demonstrates that surgery for intra-abdominal injuries is associated with an early drop in leucocyte numbers in peripheral blood. Moreover, splenectomy in severely injured patients is associated with an altered cellular immune response reflected by a persistent state of prominent leukocytosis after trauma.

Splenic ischemic preconditioning attenuates oxidative stress induced by hepatic ischemia-reperfusion in rats

Purpose:

To evaluate the effects of splenic ischemic preconditioning (sIPC) on oxidative stress induced by hepatic ischemia-reperfusion in rats.

Methods:

Fifteen male Wistar rats were equally divided into 3 groups: SHAM, IRI and sIPC. Animals from IRI group were subjected to 45 minutes of partial liver ischemia (70%). In the sIPC group, splenic artery was clamped in 2 cycles of 5 min of ischemia and 5 min of reperfusion (20 min total) prior to hepatic ischemia. SHAM group underwent the same surgical procedures as in the remaining groups, but no liver ischemia or sIPC were induced. After 1h, hepatic and splenic tissue samples were harvested for TBARS, CAT, GPx and GSH-Rd measurement.

Results:

sIPC treatment significantly decreased both hepatic and splenic levels of TBARS when compared to IRI group (p<0.01). Furthermore, the hepatic and splenic activities of CAT, GPx and GSH- Rd were significantly higher in sIPC group than in IRI group.

Conclusion:

sIPC was able to attenuate hepatic and splenic IRI-induced oxidative stress.

Rodent models of hepatic ischemia-reperfusion injury: time and percentage-related pathophysiological mechanisms

Ischemia and reperfusion (IR) injury remains one of the major problems in liver surgery and transplantation, which determines the viability of the hepatic tissue after resection and of the grafted organ. This review aims to elucidate the mechanisms involved in IR injury of the liver in rodent experimental studies and the preventative methods and pharmacologic agents that have been applied. Many time- and percentage-related liver IR injury rodent models have been used to examine the pathophysiological mechanisms and the parameters implicated with different morbidity, mortality, and pathology findings. The most preferred experimental rodent model of liver IR is the induction of 70% IR for 45 min, which is associated with almost 100% survival. In this model, plasma levels of several parameters such as alanine transaminase, aspartate aminotransferase, gamma-glutamyltransferase, endothelin-1, malonodialdehyde, tumor necrosis factor α, interleukin 1b, inducible nitric oxide synthase, and caspases are increased. The increase of caspases is associated with the initiation of hepatic cellular apoptosis. The main injuries observed 24 h after reperfusion are nuclear pyknosis, cytoplasmic hypereosinophilia, severe necrosis, and loss of intercellular borders. Both ischemic pre- and post-conditioning preventative methods and pharmacologic agents are successfully applied to alleviate the IR injuries. The selection of the time- and percentage-related liver IR injury rodent model and the potential preventative method should be related to the clinical question being answered.

Heme oxygenase/carbon monoxide pathway inhibition plays a role in ameliorating fibrosis following splenectomy

Splenectomy is a recognized therapy for liver cirrhosis with splenomegaly, since it decreases free iron concentration that accompanies the destruction of red blood cells. Heme oxygenase (HO)-1 and its by-products, iron and carbon monoxide (CO), play crucial roles in hepatic fibrosis. The aim of the present study was to determine whether splenectomy in cirrhotic rats induced by bile duct ligation (BDL), through the HO/CO pathway, could slow down the development of liver fibrosis. Male Sprague-Dawley rats were divided randomly into the sham, BDL, splenectomy, Fe, zinc protoporphyrin (Znpp) and cobalt protoporphyrin (Copp) treatment groups, for inhibiting and inducing HO-1 expression. The level of HO-1 was detected by western blot analysis and reverse transcription-polymerase chain reaction. Serum carboxyhemoglobin (COHb), iron and portal vein pressure (PVP) were also quantified. Liver iron was measured by atomic absorption spectrometry with acetylene-air flame atomization. HO-1 and α-smooth muscle actin (α-SMA) were localized by immunohistochemistry. Liver and spleen iron were visualized by Perls' Prussian blue staining. Hepatic fibrosis was assessed using hematoxylin and eosin (H&E) staining. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum transforming growth factor-β1 (TGF-β1). The results showed that liver, spleen and serum levels of HO-1, COHb and iron were greatly enhanced in the BDL group compared with the sham group; they were reduced following splenectomy and Znpp treatment, but were elevated in the Copp and Fe groups. Hydroxyproline, TGF-β1, α-SMA, PVP and malonaldehyde levels were lower in the splenectomy and Znpp groups compared to BDL, while higher levels were observed in the Copp and Fe-treated groups. Our study shows that splenectomy reduces iron and CO levels in part by reducing HO-1 expression, and it decreases portal pressure and slightly decreases hepatic fibroproliferation.

New paradigms in post-hepatectomy liver failure

INTRODUCTION

Liver failure after hepatectomy remains the most feared postoperative complication. Many risk factors are already known, related to patient's comorbidities, underlying liver disease, received treatments and type of resection. Preoperative assessment of functional liver reserve must be a priority for the surgeon.

METHODS

Physiopathology of post-hepatectomy liver failure is not comparable to fulminant liver failure. Liver regeneration is an early phenomenon whose cellular mechanisms are beginning to be elucidated and allowing most of the time to quickly recover a functional organ. In some cases, microscopic and macroscopic disorganization appears. The hepatocyte hyperproliferation and the asynchronism between hepatocytes and non-hepatocyte cells mitosis probably play a major role in this pathogenesis.

RESULTS

Many peri- or intra-operative techniques try to prevent the occurrence of this potentially lethal complication, but a better understanding of involved mechanisms might help to completely avoid it, or even to extend the possibilities of resection.

CONCLUSION

Future prevention and management may include pharmacological slowing of proliferation, drug or physical modulation of portal flow to reduce shear-stress, stem cells or immortalized hepatocytes injection, and liver bioreactors. Everything must be done to avoid the need for transplantation, which remains today the most efficient treatment of liver failure.

Dual cytoprotective effects of splenectomy for small-for-size liver transplantation in rats

The problems associated with small-for-size liver grafts (ie, high mortality rates, postoperative complications, and acute rejection) remain critical issues in partial orthotopic liver transplantation (OLT). In association with partial OLT, splenectomy (SP) is a procedure used to reduce the portal pressure. However, the precise effects of SP on partial OLT have been unclear. In this study, using small-for-size liver grafts in rats, we examined the cytoprotective effects of SP on OLT. Liver grafts were assigned to 2 groups: a control group (OLT alone) and an SP group (OLT after SP). SP significantly increased animal survival and decreased liver damage. SP exerted the following cytoprotective effects: (1) it improved hepatic microcirculation and prevented increases in the portal pressure after OLT, (2) it suppressed the hepatic infiltration of neutrophils and macrophages through the direct elimination of splenic inflammatory cells before OLT, (3) it decreased the hepatic expression of tumor necrosis factor α and interleukin-6, (4) it attenuated sinusoidal endothelial injury, (5) it decreased plasma endothelin 1 levels and increased hepatic heme oxygenase 1 expression, (6) it suppressed hepatocellular apoptosis through the down-regulation of hepatic caspase-3 and caspase-8 activity, and (7) it increased hepatic regeneration. In conclusion, SP for small-for-size grafts exerts dual cytoprotective effects by preventing excessive portal vein hepatic inflow and eliminating splenic inflammatory cell recruitment into the liver; this in turn inhibits hepatocellular apoptosis and improves liver regeneration.

Melatonin inhibits type 1 interferon signaling of toll-like receptor 4 via heme oxygenase-1 induction in hepatic ischemia/reperfusion

The cytoprotective mechanisms of melatonin in hepatic ischemia/reperfusion (I/R) injury associated with heme oxygenase-1 (HO-1) induction and type 1 interferon (IFN) signaling pathway downstream of toll-like receptor 4 (TLR4) were investigated. Rats were subjected to 60min of ischemia followed by 5-hr reperfusion. Melatonin (10mg/kg) or vehicle (5% ethanol in saline) was administered intraperitoneally 15min prior to ischemia and immediately before reperfusion. Rats were pretreated with zinc protoporphyrin (ZnPP, 10mg/kg, i.p.), a HO-1 inhibitor, at 16 and 3hr prior to ischemia. Melatonin attenuated the I/R-induced increase in serum alanine aminotransferase activity, and ZnPP reversed this attenuation. Melatonin augmented the levels of HO activity and HO-1 protein and mRNA expression, and this enhancement was reversed by ZnPP. Melatonin enhanced the level of NF-E2-related factor-2 (Nrf2) nuclear translocation, and ZnPP reversed this increase. Overexpression of TLR4 and its adaptor proteins, toll-receptor-associated activator of interferon (TRIF), and myeloid differentiation factor 88 (MyD88), induced by I/R, was attenuated by melatonin; ZnPP reversed the effect of melatonin on TLR4 and TRIF expression. Melatonin suppressed the increased interaction between TLR4/TRIF and TLR4/MyD88, which was reversed by ZnPP. Melatonin attenuated the increased levels of JAK2 and STAT1 activation as well as IFN-β, and ZnPP reversed these inhibitory effects of melatonin. Melatonin inhibited the level of chemokine (C-X-C motif) ligand 10 (CXCL-10), and ZnPP reversed this inhibition. Our findings suggest that melatonin protects the liver against I/R injury by HO-1 overexpression, which suppresses the type 1 IFN signaling pathway downstream of TLR4.

Splenic artery ligation: A protection against hepatic ischemia/reperfusion injury in partially hepatectomized rats

AIM

  In liver resection, the temporary occlusion of the hepatoduodenal ligament (Pringle maneuver) is often used. However, the maneuver causes ischemia/reperfusion (I/R) injury in the remnant liver. Heme oxygenase (HO)-1 has a cytoprotective role against this injury. Our aim is to investigate whether splenic artery ligation induces HO-1 expression in the liver and ameliorates the hepatic I/R injury in partially hepatectomized rats.

METHODS

  Rats underwent splenic artery ligation by occluding the main splenic artery. Two days later, the total hepatic ischemia (Pringle maneuver) was conducted, and then a two-thirds partial hepatectomy (PH) was performed just before the start of reperfusion. HO inhibitor was twice injected s.c. at 3 and 16 h before the Pringle maneuver. HO-1 levels were determined by western blotting. Liver injury was biochemically assessed.

RESULTS

  In normal rats, HO-1 was highly expressed in the spleen, but not in the liver. Splenic artery ligation induced HO-1 in the livers. When rats underwent 20 and 30 min of Pringle maneuver/PH, survival rates were 28% and 8%, respectively. Splenic artery ligation significantly improved both the survival rates: 73% and 56%, respectively. Under these conditions, administration of HO-1 inhibitor at least partly negated the efficacy of splenic artery ligation. Splenic artery ligation also increased the recovery rate of the remnant liver mass and platelet counts in Pringle maneuver/PH-treated rats.

CONCLUSION

  Splenic artery ligation was significantly effective on the hepatic I/R injury in partially hepatectomized rats. Induction of HO-1 may be at least partly involved in the improvement of this injury.

Splenectomy protects the kidneys against ischemic reperfusion injury in the rat

BACKGROUND

Ischemic reperfusion (I/R) injury of the kidney is closely associated with delayed graft function, increased acute rejection, and late allograft dysfunction. Splenectomy reduced hepatic I/R injury by inhibiting leukocyte infiltration in the liver, release of TNF-α, cell apoptosis, and expression of caspase-3. Thus, we investigated the effects of splenectomy on renal I/R injury in the rat.

METHODS

Male Wistar rats were assigned to four groups: sham operation (sham group), sham operation+splenectomy (sham+SPLN group), right nephrectomy followed by clamping the left renal pedicle for 30min (I/R 30 group), and I/R 30+splenectomy (I/R 30+SPLN group). Renal function was determined by measuring the concentration of blood urea nitrogen (BUN) and serum creatinine (S-Cr). The serum level of tumor necrosis factor-α (TNF-α) was measured as the marker for inflammation. Left kidneys were obtained 24h after reperfusion. TUNEL assay was assessed for cell apoptosis. Spleens were obtained immediately (0-h group) and 3h after reperfusion (3-h group). The removed spleens were histologically evaluated.

RESULTS

The BUN and S-Cr levels were significantly lower in the I/R 30+SPLN group than in the I/R 30 group (p<0.05 for both). Apoptotic cells were significantly lower in the I/R 30+SPLN group than in the I/R 30 group. The serum level of TNF-α, which was increased after I/R, was significantly lower in the I/R 30+SPLN group than in the I/R 30 group (p<0.05). Spleen weights were significantly lower in the 3-h group than in the 0-h group (p<0.05).

CONCLUSION

These results suggest that splenectomy reduces renal I/R injury, and this effect may occur by an anti-inflammatory pathway and inhibition of cell apoptosis.

Protective effect of heme oxygenase-1 induction against hepatic injury in alcoholic steatotic liver exposed to cold ischemia/reperfusion

AIMS

The purpose of this study was to investigate the cytoprotective role of heme oxygenase-1 (HO-1) induction in hepatic injury in alcoholic steatotic liver exposed to cold ischemia/reperfusion (I/R).

MAIN METHODS

Animals were fed an ethanol liquid diet or isocaloric control diet for 5 weeks. Isolated perfused rat livers were preserved in Histidine-Tryptophan-Ketoglutarate at 4 °C. After 24 h of storage, livers were subjected to 120 min of reperfusion with Krebs-Henseleit bicarbonate buffer at 37 °C. Animals were pretreated with cobalt protoporphyrin (CoPP, 5 mg/kg, i.p.) or zinc protoporphyrin (ZnPP, 25 mg/kg, i.p.), HO-1 inducer and antagonist, respectively.

KEY FINDINGS

In the model of ischemia/isolated perfusion, endogenous HO-1 was downregulated in the livers fed with ethanol diet (ED I/R). In ED I/R group, portal pressure and lactate dehydrogenase release were significantly increased, while bile output and hyaluronic acid clearance decreased compared to rats fed on control diet (CD I/R). Furthermore, hepatic glutathione content decreased and lipid peroxidation increased in the ED I/R group compared to the CD I/R group. These alterations were attenuated by upregulation of HO-1 with CoPP pretreatment.

SIGNIFICANCE

Our results suggest that chronic ethanol consumption aggravates hepatic injury during cold I/R and it is likely due to downregulation of endogenous HO-1. Prior induction of HO-1 expression may provide a new strategy to protect livers against hepatic I/R injury or to increase the donor transplant pool through modulation of marginal alcoholic steatotic livers.

Development of a porcine model of post-hepatectomy liver failure

BACKGROUND

The aim of this study was to develop a porcine model of post-operative liver failure (POLF) that could accurately reproduce all the neurological and metabolic parameters of the corresponding clinical syndrome that may develop after extensive liver resections.

METHODS

In our model, we induced POLF by combining extended left hepatectomy and ischemia of the small liver remnant of 150 min duration. Subsequently, the remnant liver parenchyma was reperfused and the animals were closely monitored for 24 h.

MATERIALS

Twelve Landrace pigs (weight 25-30 kg) were randomly assigned in two groups; eight of them constituted the experimental group, in which POLF was induced (POLF group, n = 8), whereas the rest of them (n = 4) were included in the control group (sham laparotomy without establishment of POLF). RESULTS (MEANS ± SD): All POLF animals gradually developed neurological and biochemical signs of liver failure including, among many other parameters, elevated intracranial pressure (24.00 ± 4.69 versus 10.17 ± 0.75, P = 0.004) and ammonia levels (633.00 ± 252.21 versus 51.50 ± 9.49, P = 0.004) compared with controls. Histopathologic evaluation of the liver at the end of the experiment demonstrated diffuse coagulative necrosis and severe architectural distortion of the hepatic parenchyma in all POLF animals.

CONCLUSION

Our surgical technique creates a reproducible porcine model of POLF which can be used to study the pathophysiology and possible therapeutic interventions in this serious complication of extensive hepatectomies.

Protective effects of penehyclidine hydrochloride on liver injury in a rat cardiopulmonary bypass model

BACKGROUND AND OBJECTIVE

Hepatic injury after cardiac surgery is considered to be a consequence of cardiopulmonary bypass (CPB). The aim of this study was to test the hypothesis that penehyclidine hydrochloride (PHC) could attenuate hepatic injury using a rat CPB model.

METHODS

Male Sprague-Dawley rats were randomly divided into six groups (eight per group), including sham-operated control, sham low-dose PHC control (0.6 mg kg), sham high-dose PHC control (2.0 mg kg), vehicle control, low-dose PHC (0.6 mg kg) and high-dose PHC (2.0 mg kg)-treated groups. Blood samples were collected from the femoral artery at the cessation of CPB and the serum levels of the liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were determined. The ultrastructure of liver tissue was also examined under an electron microscope.

RESULTS

In the sham-operated groups, high-dose PHC and low-dose PHC had no significant impact on the levels of respiratory rate, heart rate, blood pressure, ECG, ALT or AST. Compared with the sham group, the serum levels of ALT and AST were increased significantly in the surgical groups. PHC alleviated all the biochemical and histopathological changes in a dose-dependent manner. The ALT and AST levels in the high-dose PHC-treated groups were significantly lower than those in the vehicle control group.

CONCLUSION

Treatment with penehyclidine hydrochloride could improve liver function during CPB.

Protective role of heme oxygenase-1 against liver damage caused by hepatic ischemia and reperfusion in rats

This study investigated the time course of heme oxygenase (HO)-1 expression and the role of endogenous HO-1 in hepatic ischemia and reperfusion (I/R). Rats were pretreated with hemin, an HO-1 inducer, and zinc protoporphyrin (ZnPP), an HO-1 inhibitor. Hepatic HO activity increased at 1 h after reperfusion, reaching a maximum at 6 h after reperfusion and then declined. HO-1 mRNA and protein expression in I/R liver were upregulated prior to reperfusion and highly induced again by reperfusion. The ALT level was upregulated at all time points, with a peak at 4-6 h. This increase was augmented by ZnPP but attenuated by hemin. Lipid peroxidation and serum HMGB1 release significantly increased at 1 h after reperfusion and remained elevated throughout the 24 h of reperfusion period, whereas the glutathione content decreased markedly at 4-6 h after reperfusion. These changes were attenuated by hemin but augmented by ZnPP. The levels of serum TNF-α, iNOS, and COX-2 protein and mRNA expressions were upregulated after reperfusion, further enhanced by ZnPP, and suppressed by hemin. HO-1 overexpression protects the liver against I/R injury by modulating oxidative stress and proinflammatory mediators.

Beneficial effects of splenectomy on massive hepatectomy model in rats

AIM

Possible spleno-hepatic relationships during hepatectomy remain unclear. The purpose of this study was to investigate the impact of splenectomy during massive hepatectomy in rats.

METHODS

Rats were divided into the following two groups: 90% hepatectomy (Hx group), hepatectomy with splenectomy (Hx+Sp group). The following parameters were evaluated; survival rate, biochemical parameters, quantitative RT-PCR for hemeoxygenase-1 (HO-1) and tumor necrosing factor alpha (TNFalpha), immunohistochemical staining for HO-1, proliferating cell nuclear antigen labeling index and liver weights.

RESULTS

The survival rate after massive hepatectomy significantly improved in Hx+Sp group as well as serum biochemical parameters, compared with Hx group (P < 0.05). HO-1 positive hepatocytes and its mRNA expression significantly increased and TNFalpha mRNA expression significantly decreased in Hx+Sp group compared with Hx group (P < 0.05). Moreover, liver regeneration was significantly accelerated at 48 and 72 h after hepatectomy in Hx+Sp group.

CONCLUSIONS

Splenectomy had beneficial effects on massive hepatectomy by ameliorating liver injuries and promoting preferable liver regeneration.

Amelioration of hepatic ischemia/reperfusion injury in the remnant liver after partial hepatectomy in rats

BACKGROUND AND AIMS

Reactive oxygen species have been implicated in the development of hepatic ischemia/reperfusion (I/R) injury. I/R injury remains an important problem in massive hepatectomy and organ transplantation. The aim of this study was to examine the effect of edaravone, a newly synthesized free radical scavenger, on I/R injury in the remnant liver after partial hepatectomy in rats.

METHODS

Partial (70%) hepatic ischemia was induced in rats by occluding the hepatic artery, portal vein, and bile duct to left and median lobes of liver. Total hepatic ischemia (Pringle maneuver) was induced by occluding the hepatoduodenal ligament. Edaravone was intravenously administered to rats just before reperfusion and partial (70%) hepatectomy was performed just after reperfusion.

RESULTS

Edaravone significantly reduced the increases in the levels of serum alanine aminotransferase and aspartate aminotransferase in rats with liver injury induced by 90-min of partial ischemia followed by 120-min of reperfusion. Histopathological analysis showed that edaravone prevented inflammatory changes in the livers with I/R injury. Edaravone also decreased the levels of myeloperoxidase activity, which is an index of neutrophil infiltration, and interleukin-6 mRNA, which is a proinflammatory cytokine. Additionally, edaravone improved the survival rate in partial hepatectomy rats with I/R injury induced by the Pringle maneuver.

CONCLUSIONS

Edaravone administration prior to reperfusion protected the liver against I/R injury. Edaravone also improved the function of the remnant liver with I/R injury after partial hepatectomy. Therefore, edaravone may have applicability for major hepatectomy and liver transplantation in the clinical setting.

Effects of free radical scavenger on acute liver injury induced by d-galactosamine and lipopolysaccharide in rats

AIM

Acute severe liver injury still has a high mortality rate. Acute liver injury induced by a coadministration of d-galactosamine (GalN) and lipopolysaccharide (LPS) is an experimental model of fulminant hepatitis in rats. Our aim is to investigate the effects of free radical scavenger on the injury induced by GalN/LPS in rats.

METHODS

Free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) was twice injected into rats 5 min before and 60 min after the GalN/LPS injection. Liver injury was biochemically and histologically assessed. The survival rate was examined 72 h after the intoxication.

RESULTS

In the GalN/LPS-treated rats, a marked elevation in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels was observed. On the other hand, edaravone significantly inhibited the elevation in serum AST and ALT levels. The efficacy of edaravone was also confirmedby histological analysis. Edaravone lowered the levels of proinflammatory cytokines TNF-alpha mRNA and interleukin-6 mRNA expression, antioxidative enzyme heme oxygenase-1 protein and myeloperoxidase activity, a marker of neutrophil infiltration, in rat livers. In addition, edaravone reduced the mortality rate in GalN/LPS-treated rats as compared to the rats without edaravone treatment.

CONCLUSIONS

Free radical scavenger edaravone effectively ameliorated the liver injury induced by the GalN/LPS administration in rats, not only by attenuating oxidative stress, but also by reducing the expression of proinflammatory cytokines.

Splenic artery ligation improves remnant liver function in partially hepatectomized rats with ischemia/reperfusion injury

BACKGROUND

In liver resection, the temporary occlusion of the hepatoduodenal ligament (Pringle maneuver) is often used. However, the maneuver causes severe ischemia/reperfusion injury in the remnant liver. Our aim was to investigate the effects of splenic artery ligation on the liver function in partially hepatectomized rat with the Pringle maneuver.

METHODS

The Pringle maneuver was conducted for 30 min just before a two-thirds partial hepatectomy. Splenic artery ligation was performed before the Pringle maneuver. The efficacy of splenic artery ligation was assessed by survival, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), recovery of remnant liver weight, and portal pressure.

RESULTS

On day 3, animal survival was four rats of 12 in partially hepatectomized rats with the Pringle maneuver and 10 rats of 12 in the splenic artery ligation-treated partially hepatectomized rats with the Pringle maneuver. A two-thirds partial hepatectomy alone or splenic artery ligation itself did not show any effects on the survival. Compared with partially hepatectomized rats with the Pringle maneuver, splenic artery-ligated animals had lower serum AST and ALT levels, and higher recovery of remnant liver weight. Splenic artery ligation significantly reduced the portal pressure and also decreased the fatality in excessively hepatectomized rats.

CONCLUSIONS

Splenic artery ligation ameliorated the remnant liver function in partially hepatectomized rats with the Pringle maneuver and excessively hepatectomized rats. The amelioration may be mediated at least by decreasing portal pressure.

Splenectomy ameliorates acute multiple organ damage induced by liver warm ischemia reperfusion in rats

BACKGROUND

Liver ischemia/reperfusion (I/R) results in the release of destructive proinflammatory cytokines and oxygen-derived radicals, which in turn cause injury to liver and other organs such as kidney, lung, and intestine. Splenectomy protects organs from intestinal I/R injury. Therefore, the present study aims to investigate whether splenectomy could also ameliorate multiple organ damage caused by liver I/R.

METHODS

Wistar rats randomly assigned into 4 groups underwent sham-operation, splenectomy, hepatic I/R induced by occlusion of hepatic artery and portal vein, and splenectomy plus hepatic I/R, respectively. Blood samples were collected for assessing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity, and tumor necrosis factor-alpha (TNF-alpha) levels. The activity of myeloperoxidase (MPO) in liver tissues was assessed. Livers, kidneys, lungs, and small intestines underwent histopathologic examination for scoring injury severity and TUNEL assay for cell apoptosis. The expression of caspase-3 was evaluated with Western blot analysis.

RESULTS

Liver I/R resulted in liver injury as evidenced by morphologic abnormalities, increased serum activities of AST and ALT, and increased percentage of apoptotic cells. The activity of MPO in liver tissues and the serum levels of TNF-alpha were increased after I/R. Splenectomy significantly decreased the histologic severity score, apoptotic index, MPO activity, and serum levels of AST, ALT, and TNF-alpha. Hepatic I/R also caused damage to kidneys, lungs, and small intestines, as evaluated by histologic alterations and increased apoptotic cells; these changes were ameliorated by splenectomy. The expression of caspase-3 was upregulated in the 4 organs by hepatic I/R and inhibited by splenectomy.

CONCLUSIONS

Splenectomy protects the liver as well as the kidney, lung, and intestine from injury by hepatic I/R. Although the mechanism needs further investigation, this study demonstrated that splenectomy inhibited leukocyte infiltration in livers, release of TNF-alpha, cell apoptosis, and expression of caspase-3.

Splenic artery ligation ameliorates hepatic ischemia and reperfusion injury in rats

BACKGROUND/AIMS

Hepatic injury caused by ischemia/reperfusion (I/R) is a key clinical problem associated with liver transplantation and liver surgery. The spleen is involved in hepatic I/R injury. In this study, we examined the effects of splenic artery ligation on hepatic I/R injury.

METHODS

Splenic artery ligation was performed 7 days, 3 days, or just before the hepatic ischemia. Hepatic ischemia was conducted by occluding the blood vessels to the median and left lateral lobes with an atraumatic vascular clamp. Hepatic I/R injury was induced by 45 min of ischemia followed by 120 min of reperfusion.

RESULTS

When splenic artery ligation was performed at 3 days or just before the ischemia, serum aspartate transaminase and alanine transaminase activities, as markers for hepatic injury, decreased as compared with the rats with I/R alone. Splenic artery ligation also reduced the myeloperoxidase activity, an enzyme present in neutrophils, and the expression of interleukin-6 mRNA, a proinflammatory cytokine, in rat livers with I/R. Efficacy of splenic artery ligation on hepatic I/R injury was also confirmed by histology. On the other hand, when splenic artery ligation was conducted 7 days before the ischemia, efficacy of splenic artery ligation was disappeared.

CONCLUSIONS

Splenic artery ligation ameliorates hepatic I/R injury in rats. These results strongly suggest the clinical usefulness of this surgical procedure to protect the liver against I/R injury.

Effects of prior splenectomy on remnant liver after partial hepatectomy with Pringle maneuver in rats

BACKGROUND/AIMS

In the case of the liver resection, the temporary occlusion of the hepatoduodenal ligament (Pringle maneuver) is often used. However, the maneuver causes hepatic ischemia/reperfusion (I/R) injury that strongly affects the recovery of patients. The present study investigated the effects of prior splenectomy on the remnant liver in partial hepatectomized rat with Pringle maneuver.

METHODS

Pringle maneuver was conducted just before a two-thirds partial hepatectomy. Efficacy of splenectomy was assessed by survival rate, serum alanine aminotransferase (ALT), neutrophil infiltration into liver, recovery of remnant liver weight, and liver proliferating cell nuclear antigen (PCNA) levels. Ischemic preconditioning was performed as follows; 10 min of total hepatic ischemia followed by 10 min of reperfusion.

RESULTS

In partial hepatectomized rats with 30 min of Pringle maneuver, seven out of 12 rats died within 3 days. On the other hand, when splenectomy was performed on 3 days before the maneuver, only one out of 12 rats died. When prior splenectomy was performed on eight and 18 days before the Pringle maneuver, respectively, similar efficacy was observed. In addition, prior splenectomy on 3 days before the maneuver showed that serum ALT activity, neutrophil infiltration, recovery of remnant liver weight, and PCNA levels in partial hepatectomized rats with Pringle maneuver were also ameliorated as compared with those of control rats without splenectomy. When effects of prior splenectomy were compared with those of ischemic preconditioning in these situations, efficacy of prior splenectomy was comparable with that of the ischemic preconditioning.

CONCLUSIONS

Prior splenectomy ameliorated the I/R injury in the remnant liver after partial hepatectomy with Pringle maneuver. Effects of prior splenectomy may influence the liver for long duration, because splenectomy on 18 days before the maneuver still exerts effective action.