Effect of ischemic preconditioning on P-selectin expression in hepatocytes of rats with cirrhotic ischemia-reperfusion injury

ZNF667 attenuates leukocyte-endothelial adhesion via downregulation of P-selectin in skin flap following remote limb ischemic preconditioning

We assessed the effects and potential mechanism of romote ischemic preconditioning (RIPC) on leukocytes-endothelium cell adhesion in the flap microvessel after ischemia-reperfusion (I/R) injury. Eight hours after reperfusion, edema and intravascular leukocyte aggregation were reduced and microvessels were more obvious in the group with superficial inferior epigastric artery (SIEA) perforator flap (SIEA-flap) subjected to RIPC than in the I/R group. Zinc finger protein 667 (ZNF667) was significantly increased but P-selectin was decreased in the flaps subjected to RIPC, compared to those in the I/R group. The low expression of P-selectin was associated with ZNF667 expression and activation in human dermal microvascular endothelial cells in response to hypoxic preconditioning. ZNF667 bound to the P-selectin promoter region, suppressing its transcription through a special core sequence. The ablation of P-selectin by small interfering RNA effectively prevented the leukocytes-endothelium cell adhesion effect of ZNF667-knockdown. ZNF667 upregulation attenuates leukocyte-endothelial cell adhesion by negatively regulating the expression of P-selectin in SIEA-flap subjected to RIPC.

The nitric oxide pathway--evidence and mechanisms for protection against liver ischaemia reperfusion injury

Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMP- protein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Modification of the hepatic mitochondrial proteome in response to ischemic preconditioning following ischemia-reperfusion injury of the rat liver

BACKGROUND/AIM

Ischemic preconditioning (IPC) may reduce hepatic ischemia-reperfusion (IR) injury, but efficacy of IPC on mitochondrial proteome is not demonstrated. We investigated how IPC modifies the mitochondrial proteome after IR injury.

METHODS

Rats were subjected to 25 min of portal triad crossclamping (IR group, n = 8). In the IPC group (n = 8), 10 min of temporal portal triad clamping was performed before 25 min of portal clamping. Samples were obtained after 24 h. The mitochondrial inner-membrane potential was measured by the uptake of a lipophilic cationic carbocyanine probe and mitochondrial proteome was also investigated using 2-dimensional differential in-gel electrophoresis and liquid chromatography-tandem mass spectrometry.

RESULTS

Mitochondrial inner-membrane potential and glutathione were lower and serum transaminase was higher in the IPC group than in the IR group. The mitochondrial precursor of aldehyde dehydrogenase 2 and alpha-methylacyl-CoA-racemase were upregulated in the IPC group in comparison to the IR group. In contrast, protein disulfide-isomerase A3 precursor, 60S acid ribosomal protein P0, carbonic anhydrase 3 and superoxide dismutase were significantly more downregulated in the IPC group than in the IR group.

CONCLUSIONS

A hepatoprotective effect by IPC was not shown; however, IPC caused significant up- or downregulation of several mitochondrial proteins.

Ischemic preconditioning versus intermittent vascular occlusion in liver resections performed under selective vascular exclusion: a prospective randomized study

BACKGROUND

The aim of this study was to compare ischemic preconditioning with the intermittent vascular occlusion technique in liver resections performed under inflow and outflow occlusion.

METHODS

Fifty-four patients with resectable liver tumors assigned were randomly to undergo surgery with either ischemic preconditioning (IP group, n = 27) or with intermittent vascular occlusion (IVO group, n = 27). Both groups were compared regarding surgical parameters, aspartate transaminase levels, and apoptosis.

RESULTS

For warm ischemic time less than 40 minutes, no significant difference was noticed between the 2 groups apart from caspase-3 activity, which was higher in the IVO group than in the IP group (17.2 +/- 3.4 vs. 10.3 +/- 5.2, P < .05). When warm ischemia exceeded 40 minutes, the IP group showed higher levels in blood aspartate transaminase levels on day 3 (442 +/- 178 IU/L vs. 305 +/- 104 IU/L, P < .05) and higher caspase-3 levels (26.5 +/- 5.7 count/high-power field [hpf] vs. 20.7 +/- 3.6 count/hpf, P < .05) and apoptotic activity (28.5 +/- 7.5 count/hpf vs. 20.2 +/- 4.1 count/hpf, P < .05), as compared with the IVO group.

CONCLUSIONS

Although both techniques showed comparable efficacy for short ischemic times, intermittent vascular occlusion provided better cytoprotection when ischemia exceeded 40 minutes.

Effects of different operations on cirrhotic portal hypertensive liver in rats

AIM: To evaluate respectively the effects of portaazygous disconnection (PAD), mesocaval shunt (MCS) and distal splenocaval shunt (DSCS) on the portasytemic shunting (PSS), hepatic function (HF), hepatic mitochondrial respiratory function (HMRF) and its ultrastructure, anti-oxidation ability (HAOA) and lipoperoxide (LPO), so as to provide theoretical basis to select a suitable operation.

METHODS: Using the cirrhotic portal hypertensive model induced by CCl₄/ethanol in Wristar rats, we investigated PSS, HF, HMRF and its HAOA and LPO during three wks after MCS, DSCS and PAD.

RESULTS: After MCS, the PSS were further increased, HF, HMRF and HAOA were significantly decreased, and LPO increased. Hepatic mitochondrial ultrastructure showed severely damaged. Only a little improvement was found on the third wk. After DSCS and PAD, above mentioned indexes were less influenced, and they were restored a little more quickly in DSCS groups than that in PAD groups. During the first postoperative wk, the PAD group showed the highest mortality.

CONCLUSION: DSCS may be a desirable operation among the three kinds of operation.

Gene expression profiles in liver cirrhosis and normal liver tissues

AIM: To describe liver specific gene expression profiles and to identify genes with differential expression between liver cirrhotic tissues and normal liver tissues.

METHODS: The cDNA probes which were labeled with α-³²P dATP were synthesized from total RNAs of liver cirrhosis and normal liver tissues and hybridized to two identical Atlas human cDNA expression arrays membranes containing 588 known genes respectively.

RESULTS: Autoradiographic results were analyzed by specific AtlasImage^TM (version1.01a) software. Among the 588 genes analyzed, 17 genes were found up-regulated in cirrhosis, including integrin beta 7 and collagen type XVIII, and 98 genes were down-regulated in cirrhosis, including TFDP2, BAK and ABL. Expression of the genes was associated with the regulation of cell proliferation, apoptosis, differen-tiation, cell-cell interaction, invasion regulators and cytokines altered.

CONCLUSION: The results obtained from Atlas microarray provide a comprehensive liver cirrhosis specific expression profile. These results may be helpful for identification of target genes for diagnosis and designing rational therapeutic strategies.