Protective Effects of Ischemic Preconditioning Protocols on Ischemia-Reperfusion Injury in Rat Liver

Liver Transplantation: A Test of Cellular Physiology, Preservation, and Injury

Liver transplantation has evolved into a mature clinical field, but scarcity of usable organs poses a unique challenge. Expanding the donor pool requires novel approaches for protecting hepatic physiology and cellular homeostasis. Here we define hepatocellular injury during transplantation, with an emphasis on modifiable cell death pathways as future therapeutics.

Inflammatory setting, therapeutic strategies targeting some pro-inflammatory cytokines and pathways in mitigating ischemia/reperfusion-induced hepatic injury: a comprehensive review

Ischemia/reperfusion injury (IRI) is a key determining agent in the pathophysiology of clinical organ dysfunction. It is characterized by an aseptic local inflammatory reaction due to a decrease in blood supply, hence deprivation of dependent oxygen and nutrients. In instances of liver transplantation, this injury may have irreversible implications, resulting in eventual organ rejection. The deterioration associated with IRI is affected by the hepatic health status and various factors such as alterations in metabolism, oxidative stress, and pro-inflammatory cytokines. The primary cause of inflammation is the initial immune response of pro-inflammatory cytokines, while Kupffer cells (KFCs) and neutrophil-produced chemokines also play a significant role. Upon reperfusion, the activation of inflammatory responses can elicit further cellular damage and organ dysfunction. This review discusses the interplay between chemokines, pro-inflammatory cytokines, and other inflammatory mediators that contribute to the damage to hepatocytes and liver failure in rats following IR. Furthermore, it delves into the impact of anti-inflammatory therapies in safeguarding against liver failure and hepatocellular damage in rats following IR. This review investigates the correlation between cytokine factors and liver dysfunction via examining databases, such as PubMed, Google Scholar, Science Direct, Egyptian Knowledge Bank (EKB), and Research Gate.

Tolerogenic CD11c+dendritic cells regulate CD4+Tregs in replacing delayed ischemic preconditioning to alleviate ischemia-reperfusion acute kidney injury

Ischemia-reperfusion injury (IRI) is one of the primary clinical causes of acute kidney injury (AKI). The key to IRI lies in immune-inflammatory damage, where dendritic cells (DCs) play a central role in eliciting immune responses within the context of inflammation induced by ischemia-reperfusion. Our previous study has confirmed that delayed ischemic preconditioning (DIPC) can reduce the kidney injury by mediating DCs to regulate T-cells. However, the clinical feasibility of DIPC is limited, as pre-clamping of the renal artery is not applicable for the prevention and treatment of ischemia-reperfusion acute kidney injury (I/R-AKI) in clinical patients. Therefore, the infusion of DCs as a substitute for DIPC presents a more viable strategy for preventing renal IRI. In this study, we further evaluated the impact and mechanism of infused tolerogenic CD11c+DCs on the kidneys following IRI by isolating bone marrow-derived dendritic cells and establishing an I/R-AKI model after pre-infusion of DCs. Renal function was significantly improved in the I/R-AKI mouse model after pre-infused with CD11c+DCs. The pro-inflammatory response and oxidative damage were reduced, and the levels of T helper 2 (Th2) cells and related anti-inflammatory cytokines were increased, which was associated with the reduction of autologous DCs maturation mediated by CD11c+DCs and the increase of regulatory T-cells (Tregs). Next, knocking out CD11c+DCs, we found that the reduced immune protection of tolerogenic CD11c+DCs reinfusion was related to the absence of own DCs. Together, pre-infusion of tolerogenic CD11c+DCs can replace the regulatory of DIPC on DCs and T-cells to alleviate I/R-AKI. DC vaccine is expected to be a novel avenue to prevent and treat I/R-AKI.

Integrative analysis of the roles of lncRNAs and mRNAs in ischaemic preconditioning to alleviate liver ischaemia-reperfusion injury in mice

The objective of our study was to elucidate the possible underlying mechanism for the protective effect of ischaemic preconditioning (IPC) against ischaemia-reperfusion (I/R) injury and to provide new research perspectives of long non-coding RNAs (lncRNAs). In this study, serum and liver tissue samples were collected to measure indexes of liver injury from a mouse liver model in sham, I/R injury and I/R + IPC groups. Furthermore, liver samples from 5 randomly selected mice per group were extracted and subjected to the microarray and subsequent bioinformatics analysis. IPC ameliorated liver damage by lowered liver transaminase levels and pro-inflammatory cytokines. A total of 167 lncRNAs and 108 messenger RNAs (mRNAs) were significantly differentially expressed genes (DEGs) between the I/R + IPC and I/R groups. Gene Ontology (GO) analysis revealed that these genes were mainly related to unfolded proteins, responses to topologically incorrect proteins, responses to temperature stimuli, protein folding and protein refolding. Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis indicated that the DEGs were enriched in the following pathways: protein processing in the endoplasmic reticulum; antigen processing and presentation; and fructose and mannose metabolism. Additionally, the 7 selected DEGs (Hspa1ab, Chka, Clec2h, Mvd, Adra1a, AK085737 and AK088966) were validated in modules of the lncRNA-mRNA weighted coexpression network, which agreed with the qRT-PCR and chip data. And the identified differentially expressed lncRNAs and mRNAs may provide new clues to understand the pivotal pathophysiological mechanism by which IPC alleviates I/R-caused liver damage.

Novel Targets and Therapeutic Strategies to Protect Against Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI), a fascinating topic that has drawn a lot of interest in the last few years, is a major complication caused by a variety of clinical situations, such as liver transplantation, severe trauma, vascular surgery, and hemorrhagic shock. The IRI process involves a series of complex events, including mitochondrial deenergization, metabolic acidosis, adenosine-5'-triphosphate depletion, Kupffer cell activation, calcium overload, oxidative stress, and the upregulation of pro-inflammatory cytokine signal transduction. A number of protective strategies have been reported to ameliorate IRI, including pharmacological therapy, ischemic pre-conditioning, ischemic post-conditioning, and machine reperfusion. However, most of these strategies are only at the stage of animal model research at present, and the potential mechanisms and exact therapeutic targets have yet to be clarified. IRI remains a main cause of postoperative liver dysfunction, often leading to postoperative morbidity or even mortality. Very recently, it was reported that the activation of peroxisome proliferator-activated receptor γ (PPARγ), a member of a superfamily of nuclear transcription factors activated by agonists, can attenuate IRI in the liver, and FAM3A has been confirmed to mediate the protective effect of PPARγ in hepatic IRI. In addition, non-coding RNAs, like LncRNAs and miRNAs, have also been reported to play a pivotal role in the liver IRI process. In this review, we presented an overview of the latest advances of treatment strategies and proposed potential mechanisms behind liver IRI. We also highlighted the role of several important molecules (PPARγ, FAM3A, and non-coding RNAs) in protecting against hepatic IRI. Only after achieving a comprehensive understanding of potential mechanisms and targets behind IRI can we effectively ameliorate IRI in the liver and achieve better therapeutic effects.

Umbelliferone alleviates hepatic ischemia/reperfusion-induced oxidative stress injury via targeting Keap-1/Nrf-2/ARE and TLR4/NF-κB-p65 signaling pathway

Umbelliferone (UMB; 7-hydroxycoumarin) is a natural compound that exhibited a diversity of pharmacological activities. Its protective effects against various ischemia/reperfusion (IR) injuries, including heart, kidney, and testis, have been observed. However, their effect on hepatic IR is still not investigated yet. Here, this study was conducted to examine the potential protective role of UMB during the early phase of hepatic IR injury via targeting Keap-1/Nrf-2/ARE and its closely related signaling pathway, TLR4/NF-κB-p65. Experimentally, forty Wistar albino rats were randomly divided into 4 groups: Sham control group (received 1% carboxymethyl cellulose as a vehicle), UMB group (30 mg/kg/day, P.O.), IR group (subjected to complete hepatic IR injury), and IR + UMB group. Our results revealed that oral UMB effectively reduced the serum levels of ALT, AST, ALP, and LDH along with the restoration of oxidant/antioxidant status. At the molecular level, UMB markedly activated Nrf-2 expression and its down-streaming targets: HO-1, NQO1, GCLC, SOD3, and TNXRD1, along with Keap-1 down-regulation. Besides, UMB significantly down-regulated NF-κB-p65 and TLR4 expressions with subsequent decreased TNF-α and IL-1β levels coupled with the up-regulation of the IL-10 level. Finally, biochemical findings were confirmed by attenuation of histopathological changes in liver tissues. Together, UMB is a promising agent for the amelioration of liver tissues against IR-induced oxidative injury through activation of the Keap-1/Nrf-2/ARE signaling pathway along with suppression of its closely related signaling pathways: TLR4/NF-κB-p65. Illustrated diagram explored the prospective underlying protective mechanism of UMB against IR-induced hepatic damage.

Remote Ischemic Preconditioning Attenuates Hepatic Ischemia/Reperfusion Injury after Hemorrhagic Shock by Increasing Autophagy

Fluid resuscitation after hemorrhagic shock is a model of systemic ischemia/reperfusion injury (SI/RI), and the liver is one of the main target organs. Ischemic preconditioning (IPC) can reduce hepatic ischemia-reperfusion injury (I/RI) via autophagy. However, whether remote ischemic preconditioning (RIPC) can alleviate the liver injury that is secondary to hemorrhagic shock and the role of autophagy in this process remain unclear. Thus, we constructed a hemorrhagic shock model in rats with or without RIPC to monitor mean arterial pressure (MAP) and investigate liver secondary injury levels via serum aminotransferase, ultrasound, HE staining and TUNEL fluorescence staining. We also detected levels of serum inflammatory factors including tumor necrosis factor-alpha (TNF-α) and interleukin 1β (IL-1β) by enzyme-linked immunosorbent assay (ELLSA), observed autophagosomes by Transmission electron microscopy (TEM), and analyzed LC3, Beclin-1, p62 protein expression levels by immunohistochemical (IHC) and western blot (WB). We found that RIPC increased blood pressure adaptability, decreased lactate (Lac) and aminotransferase levels, and delayed the decrease in liver density. Levels of inflammatory factors TNF-α, IL-1β and apoptosis were attenuated, autophagosomes was increased in the RIPC group compared with controls. IHC and WB both revealed increased LC3 and Beclin-1 but decreased p62 protein expression levels in the RIPC group. Together, our data suggest that RIPC-activated autophagy could play a protective role against secondary liver injury following hemorrhagic shock.

Effects of preoperative low-intensity training with slow movement on early quadriceps weakness after total knee arthroplasty in patients with knee osteoarthritis: a retrospective propensity score-matched study

Background

Severe and early quadriceps weakness (QW) after total knee arthroplasty (TKA), which is caused by acute inflammation resulting from surgical trauma and tourniquet-induced ischemia-reperfusion (IR) injury, can be especially problematic. We focused on tourniquet-induced IR injury, because it has been shown to be preventable through ischemic and exercise preconditioning. Low-intensity resistance exercise with slow movement and tonic force generation (LST) share some similarities with ischemic and exercise preconditioning. The present study primarily aimed to clarify the efficacy of preoperative LST program as prehabilitation for early QW among patients with TKA using propensity score matching analysis.

Methods

This single-center retrospective observational study used data from patients with knee osteoarthritis (n = 277) who were scheduled to undergo unilateral TKA between August 2015 and January 2017. Those with missing outcome data due to their inability to perform tests were excluded. The LST group included participants who performed LST and aerobic exercise (LST session) more than seven times for three months prior to surgery. The control group included participants who performed less than eight LST sessions, a general and light exercise or had no exercise for three months prior to surgery. Knee circumference, thigh volume, knee pain during quadriceps strength test (QST) and timed up and go test (TUG), quadriceps strength, and TUG were measured before and 4 days after surgery. Knee swelling, thigh swelling, Δknee pain, QW, and ΔTUG were determined by comparing pre- and postoperative measurements.

Results

Propensity score matching generated 41 matched pairs who had nearly balanced characteristics. The LST group had a significantly lower knee and thigh swelling, QW, and ΔTUG compared to the control group (all, p < 0.05). No significant differences in Δknee pain during the QST and TUG were observed between both groups (both, p > 0.05).

Conclusions

The present study demonstrated the beneficial effects of preoperative LST program on knee swelling, thigh swelling, QW, and walking disability immediately after TKA.