Pharmacological hepatic preconditioning: involvement of 70-kDa heat shock proteins (HSP72 and HSP73) in ischaemic tolerance after intravenous administration of doxorubicin

Hypoxia-mediated prior induction of monocyte-expressed HSP72 and HSP32 provides protection to the disturbances to redox balance associated with human sub-maximal aerobic exercise

HSP72 is rapidly expressed in response to a variety of stressors in vitro and in vivo (including hypoxia). This project sought a hypoxic stimulus to elicit increases in HSP72 and HSP32 in attempts to confer protection to the sub-maximal aerobic exercise-induced disturbances to redox balance. Eight healthy recreationally active male subjects were exposed to five consecutive days of once-daily hypoxia (2,980 m, 75 min). Seven days prior to the hypoxic acclimation period, subjects performed 60 min of cycling on a cycle ergometer (exercise bout 1-EXB1), and this exercise bout was repeated 1 day post-cessation of the hypoxic period (exercise bout 2-EXB2). Blood samples were taken immediately pre- and post-exercise and 1, 4 and 8 h post-exercise for HSP72 and immediately pre, post and 1 h post-exercise for HSP32, TBARS and glutathione [reduced (GSH), oxidised (GSSG) and total (TGSH)], with additional blood samples obtained immediately pre-day 1 and post-day 5 of the hypoxic acclimation period for the same indices. Monocyte-expressed HSP32 and HSP72 were analysed by flow cytometry, with measures of oxidative stress accessed by commercially available kits. There were significant increases in HSP72 (P < 0.001), HSP32 (P = 0.03), GSSG (t = 9.5, P < 0.001) and TBARS (t = 5.6, P = 0.001) in response to the 5-day hypoxic intervention, whereas no significant changes were observed for GSH (P = 0.22) and TGSH (P = 0.25). Exercise-induced significant increases in HSP72 (P < 0.001) and HSP32 (P = 0.003) post-exercise in EXB1; this response was absent for HSP72 (P ≥ 0.79) and HSP32 (P ≥ 0.99) post-EXB2. The hypoxia-mediated increased bio-available HSP32 and HSP72 and favourable alterations in glutathione redox, prior to exercise commencing in EXB2 compared to EXB1, may acquiesce the disturbances to redox balance encountered during the second physiologically identical exercise bout.

Hypoxic hepatitis: a challenging diagnosis

Hypoxic hepatitis (HH), one of the most common causes of acute liver injury, has a prevalence of up to 10% of admissions in intensive care units across the world. Inadequate oxygen uptake by the hepatocytes resulting in centrilobular necrosis associated with abnormally raised levels of the serum transaminases (ALT, AST) in patients with clinical history of cardiac, respiratory, or circulatory failures is the key feature of this condition. Abstracts, reviews, case reports, and research letters from various sources such as Pubmed, Proquest, Ovid, Google Scholar, and ISI Web of Knowledge dating from 1970 to 2011 were read and analyzed thoroughly. A study of 100 patients with HH, carried out from 2009 to 2010 at Tongji Hospital of Tongji University, Shanghai, People's Republic of China, is also documented. The contributing factors leading to HH are passive congestion, ischemia, and arterial hypoxemia of the liver. Ischemia/reperfusion injury also has a major role in HH. Some of its complications are spontaneous hypoglycemia, a high level of serum ammonia, and respiratory insufficiency due to hepatopulmonary syndrome. The therapy of HH lies mainly in the treatment of the main underlying causes, and this leads to the successful reversion of HH. The aim of this review is to present a simplified concept about the etiology, pathophysiology, mechanism, clinical manifestations, diagnosis, and treatment of HH.

Carbon monoxide induces hypothermia tolerance in Kupffer cells and attenuates liver ischemia/reperfusion injury in rats

Ischemia/reperfusion (I/R) injury in liver grafts, which is initiated by cold preservation and is augmented by reperfusion, is a major problem that complicates graft quality, posttransplant patient care, and outcomes of liver transplantation (LT). Kupffer cells (KCs) play important roles in I/R injury; however, little is known about their changes during cold preservation. We examined whether a pretreatment with carbon monoxide (CO), a cytoprotective product of heme degradation, could influence KC activity during cold storage and protect liver grafts against LT-induced I/R injury. In vitro, primary rat KCs were stimulated for 24 hours under hypothermic conditions (4°C, 20% O(2)), with lipopolysaccharide, or under hypoxic conditions (37°C, 5% O(2)) with or without a CO pretreatment. When rat KCs were exposed to hypothermic conditions, they produced reactive oxygen species (ROS), but they did not produce tumor necrosis factor α (TNF-α) or nitric oxide. The preincubation of KCs with CO up-regulated heat shock protein 70 (HSP70) and inhibited ROS generation. When liver grafts from donor rats exposed to CO (250 ppm) for 24 hours were transplanted after 18 hours of cold preservation in University of Wisconsin solution, HSP70 expression increased in these grafts versus control grafts, and serum aspartate aminotransferase and alanine aminotransferase levels as well as necrotic areas and inflammatory infiltrates were significantly reduced after LT. CO-pretreated liver grafts showed less up-regulation of TNF-α and inducible nitric oxide synthase messenger RNA (mRNA) and reduced expression of proapoptotic B cell lymphoma 2-associated X protein mRNA, cleaved caspase-3, and poly(adenosine diphosphate ribose) polymerase. In conclusion, the pretreatment of donors with CO ameliorates LT-associated I/R injury with increased hepatic HSP70 expression, particularly in the KC population.

Modified mild heat shock modality attenuates hepatic ischemia/reperfusion injury

BACKGROUND

Hepatic ischemia/reperfusion (I/R) injury is a pathologic process caused by hepatic surgery and transplantation, and still remains a severe clinical problem. It was shown that preconditioning by hyperthermia might protect tissues against I/R injury. But hyperthermia could be laborious and time-consuming. Alternatively, the application of mild electrical stimulation (MES) has been reported to have positive effects in clinical settings on several medical ailments. Thus, we modified the preconditioning approach by combining short-term mild heat shock (HS) and MES, and evaluated the effect of HS+MES pretreatment on hepatic injury induced by I/R.

MATERIALS AND METHODS

C57BL/6J mice were sham treated or treated three times with HS (42 degrees C) and/or MES (12V) for 20min, carried out every other d within 1 wk. After the last treatment, mice were subjected to hepatic ischemia for 30 or 60min and reperfusion for 6h. Liver injury was assessed by evaluating the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The expressions of pro-inflammatory cytokines and heat shock protein (Hsp) 72 in liver tissues were also assessed by real-time PCR and Western blotting analyses, respectively.

RESULTS

HS+MES pretreatment suppressed the hepatic I/R-induced release of serum AST and ALT and the mRNA levels of some pro-inflammatory cytokines. In addition, HS+MES up-regulated the expression of Hsp72 in mice liver.

CONCLUSIONS

HS+MES preconditioning ameliorated hepatic I/R injury possibly through Hsp72 induction, and suppressed pro-inflammatory cytokine expression in mice liver.

Donor pretreatment with FK506 reduces reperfusion injury and accelerates intestinal graft recovery in rats

BACKGROUND

FK506 alleviates warm ischemia-reperfusion injury, but it remains unknown if such protection is manifest after cold storage and transplantation. We studied the early outcome after transplantation of intestines from donors pretreated with FK506 compared to grafts from controls treated with saline (154 mM NaCl).

METHODS

Sprague-Dawley rats received 0.3 mg/kg FK506 or saline intravenously 6 hours before graft retrieval. The small bowel was harvested, stored for 3 hours, and then transplanted heterotopically. Samples were taken after preservation and at 20 minutes, 6 hours, 12 hours, and 24 hours after reperfusion. Heat shock protein 72 (Hsp72) and iintercellular adhesion molecule (ICAM)-1 expression and nuclear factor kappaB (NF-kappaB) activation were assessed via Western blots and eelectrophoretic mobility shift assay (EMSA), respectively. Dissacharidase activity and enterocyte proliferation rate were also studied.

RESULTS

Preservation injury was similar between groups, but pretreated grafts had better morphology already 20 minutes after reperfusion. Control grafts always had thinner mucosa and more PMN infiltration. Hsp72 expression was greater in pretreated grafts. ICAM-1 was absent after harvesting, preservation, and immediately after reperfusion but increased in control grafts at the later time points. Control grafts showed a biphasic NF-kappaB activation pattern, whereas NF-kappaB activation was inhibited effectively in pretreated grafts. Dissacharidase activity decreased during the first 6 hours after reperfusion but recovered within 24 hours in pretreated grafts but not in control grafts. Earlier enterocyte proliferation was observed in pretreated grafts.

CONCLUSIONS

FK506 donor pretreatment reduced graft proinflammatory activation and neutrophil inflammation. Pretreated groups revealed a milder reperfusion injury and accelerated morphologic and functional recovery. The mechanisms involved appear to involve Hsp72 upregulation and NF-kappaB inhibition.

Ischemic preconditioning modulates the expression of several genes, leading to the overproduction of IL-1Ra, iNOS, and Bcl-2 in a human model of liver ischemia-reperfusion

Ischemia triggers an inflammatory response that precipitates cell death during reperfusion. Several studies have shown that tissues are protected by ischemic preconditioning (IP) consisting of 10 min of ischemia followed by 10 min of reperfusion just before ischemia. The molecular basis of this protective effect is poorly understood. We used cDNA arrays (20K) to compare global gene expression in liver biopsies from living human liver donors who underwent IP (n=7) or not (n=7) just before liver devascularization. Microarray data were analyzed using pairedt test with a type I error rate fixed at alpha = 2.5 10(6) (Bonferroni correction). We found that 60 genes were differentially expressed (36 over- and 24 underexpressed in preconditioning group). After IP, the most significantly overexpressed gene was IL-1Ra. This was confirmed by immunoblotting. Differentially expressed were genes involved in apoptosis (NOD2, ephrin-A1, and calpain) and in the carbohydrate metabolism. A significant increase in the amount of the anti-apoptotic protein Bcl-2 in preconditioned livers but no change in the cleavage of procaspase-3, -8, and -9 was observed. We also observed an increase in the amount in the inducible nitric oxide synthase. Therefore, the benefits of IP may be associated with the overproduction of IL-1Ra, Bcl-2, and NO countering the proinflammatory and proapoptotic effects generated during ischemia-reperfusion.

Hepatic preconditioning of doxorubicin in stop-flow chemotherapy: NF-κB/IκB-α pathway and expression of HSP72

AIM: To provide hepatic protection through administration of doxorubicin before stop-flow chemotherapy (SFC) and to investigate the expression of heat shock protein 72 (HSP72) and role of nuclear factor kappa B (NF-κB) in this effect.

METHODS: The hepatic preconditioning of doxorubicin was established in a porcine model by injection of doxorubicin (1 mg/kg) before SFC. The experimental animals were randomized into two groups: groups receiving doxorubicin (DOX) and normal saline (NS). Serial serum and tissue samples were taken from both groups to evaluate the protection of doxorubicin. Western blot and immuno-precipitation were applied to detect the expression of HSP72, NF-κB p65 protein, inhibitor κB-α (IκB-α) and phosphorylated IκB-α as well. The expression of tumor necrosis factor α (TNF-α) was estimated by semiquantitative RT-PCR. And the extent of the hepatic injury was estimated with the level of serum aminotransferases.

RESULTS: An abundance production of HSP72 in porcine liver was observed after 24 h of intravenous administration of doxorubicin, but without any change in the expression of NF-κB p65 subunit in cytoplasm. NF-κB p65 subunit accumulated in nuclei at the end of SFC and reached its highest level at 30 min after the restoration of the abdominal circulation and decreased gradually during the 6 h after SFC in NS group, while there was little change in DOX group. There was also a slight decrease of IκB-α at 30 min after the restoration of the abdominal circulation in NS group accompanying with the appearance of phosphorylated IκB-α. The expression of TNF-α was significantly higher in NS group than that in DOX group (average 1.40±0.17 vs 0.62±0.22, P<0.01) at serial time points after SFC. Serum ALT and AST levels of NS group were higher after 24 h than those of DOX group (93.2±7.8 IU/L vs 53.3±13.9 IU/L, 217.0±29.4 IU/L vs 155.0±15.6 IU/L for ALT and AST respectively, P<0.05) and after 48 h than those of DOX group (66.6±18.1 IU/L vs 43.3±16.7 IU/L, 174.4±21.3 IU/L vs 125.7±10.5 IU/L for ALT and AST respectively, P<0.05).

CONCLUSION: Doxorubicin renders the liver to be tolerant to the hepatic influence in SFC in a porcine model through the NF-κB/IκB-α pathway with the expression of HSP72.

Induction of heme oxygenase-1 and dilatation of hepatic sinusoids by an administration of pyrrolidine dithiocarbamate in rat livers

INTRODUCTION

Inducing heme oxygenase-1 (HO-1) provides the liver with various protective effects against stressful conditions. In this article, we report our use of pyrrolidine dithiocarbamate (PDTC) to induce HO-1 in the liver in vivo and its impact on hepatic microcirculation.

MATERIALS AND METHODS

PDTC was injected intramuscularly into rats and the expression of HO-1 in liver tissue was assessed by measuring both mRNA and protein levels. The distribution of induced HO-1 was evaluated immunohistochemically. The effect of PDTC administration on hepatic microcirculation was evaluated using intravital microscopy (IVM). Rats were divided into three groups: PDTC administration (group P), vehicle administration only (group C), and ZnPP-an inhibitor of HO-1-administration after PDTC treatment (group Z). Sinusoidal diameters were measured 24 h after the injections.

RESULTS

PDTC administration induced HO-1 strongly in the liver, but not in other organs. HO-1 mRNA expression in liver tissue peaked 3 h after PDTC injection and then gradually decreased. The protein expression reached a maximum level at 24-48 h after the injection, and its expression was dose-dependent with PDTC. Immunohistochemistry revealed that HO-1 was induced not only in Kupffer cells, but also in hepatocytes in the pericentral area. IVM showed that in group P, sinusoidal diameters in zone 3 (21.94 +/- 1.29 microm) were twice as large as those in group C (11.14 +/- 0.28 microm, P < 0.0001). This dilation of sinusoids was completely reversed by ZnPP (10.95 +/- 0.37 microm, P < 0.0001).

CONCLUSION

A single administration of PDTC induced HO-1 in the liver with remarkable sinusoidal dilation. PDTC administration, therefore, may be a useful, new strategy in place of other stress preconditioning.

Protection of the liver by ischemic preconditioning: a review of mechanisms and clinical applications

Ischemic preconditioning refers to the endogenous mechanism of protection against a sustained ischemic insult following an initial, brief ischemic stimulus. Ischemia-reperfusion injury of the liver is a major cause of morbidity and mortality in liver surgery and transplantation and ischemic preconditioning is a promising strategy for improving the outcome of liver surgery. The preconditioning phenomenon was first described in a canine model of myocardial ischemia-reperfusion injury in 1986 and since then has been shown to exist in other organs including skeletal muscle, brain, kidneys, retina and liver. In the liver, the preconditioning effect has been demonstrated in rodents and a recent study has demonstrated human clinical benefits of preconditioning during hemihepatectomies. Ischemic preconditioning has been described as an adaptive response and although the precise mechanism of hepatoprotection from preconditioning is unknown it is likely to be a receptor-mediated process. Several hypotheses have been proposed and this review assesses possible mechanisms of ischemic preconditioning and its role in hepatic surgery and liver transplantation. The future lies in defining the mechanisms of the ischemic preconditioning effect to allow drug targeting to induce the preconditioning response.

Pharmacological preconditioning with doxorubicin. Implications of heme oxygenase-1 induction in doxorubicin-induced hepatic injury in rats

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme into biliverdin, carbon monoxide, and iron. HO-1, an inducible form, is thought to contribute to resistance to various types of oxidative stress. Doxorubicin (DOX) produces clinically useful responses in a variety of human cancers. We reported previously that prior administration of DOX ameliorated subsequent hepatic ischemia and reperfusion injury. The aim of this study was to examine whether this pharmacological preconditioning was useful for another type of hepatic injury induced by a non-surgical method. When a high dose of DOX (10 mg/kg body weight) was administered directly to rat liver via the portal vein, serum aspartate transaminase (AST) and alanine transaminase (ALT) levels increased markedly 24 hr after the injection. Under this condition, zinc-protoporphyrin IX, a specific inhibitor of HO-1, caused both serum AST and ALT levels to be elevated further. When a low dose of DOX (5 mg/kg body weight) was administered to rats via the tail vein as pharmacological preconditioning 3 days before the injection of a high dose of DOX via the portal vein, the levels of serum AST and ALT in rats clearly were improved as compared with rats without the preconditioning. Expression of HO-1 in the liver was confirmed 3 days after the administration of a low dose of DOX. In addition, prior administration of zinc-protoporphyrin IX abolished the effect of DOX preconditioning. Immunohistochemical analysis showed that the positive staining of HO-1 protein induced by a low dose of DOX was localized to histiocytes infiltrating periportal areas. These results strongly suggest that pharmacological preconditioning with DOX may generally help to attenuate subsequent oxidant-induced hepatic injury.

Preconditioning somatothermal stimulation on right seventh intercostal nerve territory increases hepatic heat shock protein 70 and protects the liver from ischemia-reperfusion injury in rats

Hyperthermic preconditioning attenuates the heat-induced cellular response to a subsequent severe heat challenge. However, it is impractical to perform whole-body hyperthermia in humans. This study was designed to test the hypotheses that hepatic heat shock protein 70 (Hsp70) could be induced by local somatothermal stimulation (LSTS) on right seventh intercostal nerve territory and that preconditioning the rats with LSTS protects the liver from subsequent ischemia-reperfusion injury. LSTS was brought about by application of a heating rod above right seventh intercostal nerve territory in male Sprague-Dawley rats. Hepatic gene expression of Hsp70 was assessed by Western blot and reverse transcription polymerase chain reaction (RT-PCR). Finally, serum ALT and AST and the lipid peroxidation product malondialdehyde (MDA) were evaluated in ischemic-reperfused rats preconditioned by application of LSTS on right seventh intercostal nerve territory. The results showed that hepatic gene expression of Hsp70 was upregulated in rats treated with LSTS. When animals were preconditioned with LSTS, followed by subsequent ischemia-reperfusion injury of the liver, there were significant decreases in liver enzymes (ALT/AST) and MDA formation in rats pretreated with one dose of LSTS (LSTS-1 group) as compared with those not treated with LSTS (control group) or treated with three doses of LSTS (LSTS-3 group). We conclude that mild local heat stress (one dose) on right seventh intercostal nerve territory upregulates hepatic gene expression of Hsp70 and protects the liver from subsequent ischemia-reperfusion injury. This might provide an easily applicable method for those patients facing ischemia-reperfusion challenge of the liver, as in liver resection and liver transplantation.