Remote ischemic preconditioning differentially affects NADPH oxidase isoforms during hepatic ischemia–reperfusion

Remote ischemic conditioning in experimental hepatic ischemia‑reperfusion: A systematic review and meta‑analysis

Remote ischemic conditioning (RIC), including pre-conditioning (RIPC, before the ischemic event), per-conditioning (RIPerC, during the ischemic event), and post-conditioning (RIPostC, after the ischemic event), protects the liver in animal hepatic ischemia-reperfusion injuries models. However, several questions regarding the optimal timing of intervention and administration protocols remain unanswered. Therefore, the preclinical evidence on RIC in the HIRI models was systematically reviewed and meta-analyzed in the present review to provide constructive and helpful information for future works. In the present review, 39 articles were identified by searching the PubMed, OVID, Web of Science and Embase databases spanned from database inception to July 2024. According to the preferred reporting items for systematic reviews and meta-analyses guidelines, data were extracted independently by two researchers. The primary outcomes evaluated in this study were those directly related to liver injury, such as alanine transaminase (ALT), aspartate transaminase (AST) and liver histopathology. The risk of bias was assessed using the risk of bias tool of the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE). The findings were expressed as standardized mean difference (SMD) and analyzed using random-effects models. Egger's test was used to evaluate the publication bias. RIC significantly reduced the changes in ALT, AST and liver histopathology (all P<0.00001). These effects had two peaks, with the first peak of RIPerC/RIPostC occurring earlier, regardless of models and species. RIPerC/RIPostC exerted significant effects on changes in ALT and AST [ALT SMD (95% confidence interval (CI]): RIPC -1.97 (-2.40, -1.55) vs. -2.78 (-3.77, -1.78); P=0.142; AST SMD (95%CI): RIPC -1.45 (-1.90, -0.99) vs. -2.13 (-2.91, -1.34); P=0.142], and RIPC had a greater effect on liver histopathology change [SMD (95%CI): RIPC -2.68 (-3.67, -1.69) vs. -1.58 (-2.24, -0.92); P=0.070]; however, no interactions were observed between the two groups in the meta-regression analysis. RIC is the most effective in experimental HIRI, using a 10-25-min dose. These outcomes suggest that RIC may be a promising strategy for treating HIRI; however, future studies using repeated doses in animal models with comorbidities will present novel ideas for its therapeutic application. The protocol of present study was registered with PROSPERO (CRD42023482725).

Cellular and molecular mechanisms of hepatic ischemia-reperfusion injury: The role of oxidative stress and therapeutic approaches

Ischemia-reperfusion (IR) or reoxygenation injury is the paradoxical exacerbation of cellular impairment following restoration of blood flow after a period of ischemia during surgical procedures or other conditions. Acute interruption of blood supply to the liver and subsequent reperfusion can result in hepatocyte injury, apoptosis, and necrosis. Since the liver requires a continuous supply of oxygen for many biochemical reactions, any obstruction of blood flow can rapidly lead to hepatic hypoxia, which could quickly progress to absolute anoxia. Reoxygenation results in the increased generation of reactive oxygen species and oxidative stress, which lead to the enhanced production of proinflammatory cytokines, chemokines, and other signaling molecules. Consequent acute inflammatory cascades lead to significant impairment of hepatocytes and nonparenchymal cells. Furthermore, the expression of several vascular growth factors results in the heterogeneous closure of numerous hepatic sinusoids, which leads to reduced oxygen supply in certain areas of the liver even after reperfusion. Therefore, it is vital to identify appropriate therapeutic modalities to mitigate hepatic IR injury and subsequent tissue damage. This review covers all the major aspects of cellular and molecular mechanisms underlying the pathogenesis of hepatic ischemia-reperfusion injury, with special emphasis on oxidative stress, associated inflammation and complications, and prospective therapeutic approaches.

Estrogen-dependent efficacy of limb ischemic preconditioning in female rats

Our aim was to examine the effects of ischemic preconditioning (IPC) on the local periosteal and systemic inflammatory consequences of hindlimb ischemia-reperfusion (IR) in Sprague-Dawley rats with chronic estrogen deficiency (13 weeks after ovariectomy, OVX) in the presence and absence of chronic 17beta-estradiol supplementation (E2, 20 µg kg^-1 , 5 days/week for 5 weeks); sham-operated (non-OVX) animals served as controls. As assessed by intravital fluorescence microscopy, rolling and the firm adhesion of polymorphonuclear neutrophil leukocytes (PMNs) gave similar results in the Sham + IR and OVX + IR groups in the tibial periosteal microcirculation during the 3-h reperfusion period after a 60-min tourniquet ischemia. Postischemic increases in periosteal PMN adhesion and PMN-derived adhesion molecule CD11b expressions, however, were significantly reduced by IPC (two cycles of 10'/10') in Sham animals, but not in OVX animals; neither plasma free radical levels (as measured by chemiluminescence), nor TNF-alpha release was affected by IPC. E2 supplementation in OVX animals restored the IPC-related microcirculatory integrity and PMN-derived CD11b levels, and TNF-alpha and free radical levels were reduced by IPC only with E2. An enhanced estrogen receptor beta expression could also be demonstrated after E2 in the periosteum. Overall, the beneficial periosteal microcirculatory effects of limb IPC are lost in chronic estrogen deficiency, but they can be restored by E2 supplementation. This suggests that the presence of endogenous estrogen is a necessary facilitating factor of the anti-inflammatory protection provided by limb IPC in females. The IPC-independent effects of E2 on inflammatory reactions should also be taken into account in this model. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:97-105, 2018.

Ischemic preconditioning modulates ROS to confer protection in liver ischemia and reperfusion

Ischemia reperfusion (IR) injury is a significant cause of morbidity and mortality in liver transplantation. When oxygen is reintroduced to the liver graft it initiates a cascade of molecular reactions leading to the release of reactive oxygen species (ROS) and pro-inflammatory cytokines. These soluble mediators propagate a sterile immune response to cause significant tissue damage. Ischemic preconditioning (IPC) is one method that reduces hepatocellular injury by altering the immune response and inhibiting the production of ROS. Studies quantifying the effects of IPC in humans have demonstrated an improved liver enzyme panel in patients receiving grafts pretreated with IPC as compared to patients receiving the standard of care. In our review, we explore current literature in the field in order to describe the mechanism through which IPC regulates the production of ROS and improves IR injury.

Molecular pathways in protecting the liver from ischaemia/reperfusion injury: a 2015 update

Ischaemia/reperfusion injury is an important cause of liver damage during surgical procedures such as hepatic resection and liver transplantation, and represents the main cause of graft dysfunction post-transplantation. Molecular processes occurring during hepatic ischaemia/reperfusion are diverse, and continuously include new and complex mechanisms. The present review aims to summarize the newest concepts and hypotheses regarding the pathophysiology of liver ischaemia/reperfusion, making clear distinction between situations of cold and warm ischaemia. Moreover, the most updated therapeutic strategies including pharmacological, genetic and surgical interventions, as well as some of the scientific controversies in the field are described.

Aggravation of post-ischemic liver injury by overexpression of insulin-like growth factor binding protein 3

Insulin-like growth factor-1 (IGF-1) is known to inhibit reperfusion-induced apoptosis. IGF-binding protein-3 (IGFBP-3) is the major circulating carrier protein for IGF-1 and induces apoptosis. In this study, we determined if IGFBP-3 was important in the hepatic response to I/R. To deliver IGFBP-3, we used an adenovirus containing IGFBP-3 cDNA (AdIGFBP-3) or an IGFBP-3 mutant devoid of IGF binding affinity but retaining IGFBP-3 receptor binding ability (AdIGFBP-3(GGG)). Mice subjected to I/R injury showed typical patterns of hepatocellular damage. Protein levels of IGFBP-3 were increased after reperfusion and showed a positive correlation with the extent of liver injury. Prior injection with AdIGFBP-3 aggravated liver injury: serum aminotransferases, prothrombin time, proinflammatory cytokines, hepatocellular necrosis and apoptosis, and neutrophil infiltration were markedly increased compared to control mice. A decrease in antioxidant potential and an upregulation of NADPH oxidase might have caused these aggravating effects of IGFBP-3. Experiments using HepG2 cells and N-acetylcysteine-pretreated mice showed a discernible effect of IGFBP-3 on reactive oxygen species generation. Lastly, AdIGFBP-3 abolished the beneficial effects of ischemic preconditioning and hypothermia. Mice treated with AdIGFBP-3(GGG) exhibited effects similar to those of AdIGFBP-3, suggesting a ligand-independent effect of IGFBP-3. Our results suggest IGFBP-3 as an aggravating factor during hepatic I/R injury.