Recombinant human erythropoietin preconditioning attenuates liver ischemia reperfusion injury through the phosphatidylinositol-3 kinase/AKT/endothelial nitric oxide synthase pathway

Myricitrin pretreatment ameliorates mouse liver ischemia reperfusion injury

BACKGROUND

Myricitrin has been reported to exert protective effects on liver diseases, but the protective effects of myricitrin against liver ischemia reperfusion (I/R) injury and the underlying mechanisms remain unexplored. This study aimed to investigate the effects of myricitrin on liver I/R injury and elucidate the underlying mechanisms.

METHODS

Mice were pretreated with myricitrin before liver I/R injury modeling. The mice were pretreated with either myricitrin or vehicle prior to liver ischemia. Some mice were further pretreated with the PI3K inhibitor LY294002. Liver tissues and blood samples were collected after 6 h of reperfusion. The degree of liver damage was determined by the serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), and lactic dehydrogenase (LDH) and histological examinations. The tumour necrosis factor-α (TNF-α), interleukin--1β (IL-1β), IL-4 and IL-10 expression levels were assessed by qRT-PCR and enzyme-linked immunosorbent assays (ELISAs). Serum superoxide dismutase (SOD) activity, catalase (CAT) activity, and contents of malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) contents were measured. Western blotting and caspase-3 activity were conducted to determine the effect of myricitrin on apoptosis. The expression levels of proliferation related genes (Cyclin D1 and Cyclin E1) were determined by qRT-PCR and western-blotting. The expression of p-Akt, p-mTOR and p-eNOS in liver tissue were investigated by western-blotting.

RESULTS

Myricitrin not only significantly decreased the ALT, AST and LDH levels but also reduced the necrotic areas in the liver tissue compared with liver I/R injury group. In addition, myricitrin pretreatment alleviated liver injury by inhibiting the inflammatory response and suppressing oxidative stress. Western blotting and caspase-3 activity revealed that myricitrin inhibited liver I/R induced-apoptosis. Myricitrin promoted hepatocyte proliferation following liver I/R injury by upregulating the expression levels of Cyclin D1 and Cyclin E1. Further experiments indicated that the myricitrin pretreatment increased nitric oxide (NO) production by activating the PI3K/Akt signaling pathway. However, myricitrin triggered the hepatocyte proliferation and NO synthase activation was blocked by LY294002.

CONCLUSION

These results demonstrate that myricitrin alleviates liver I/R injury by suppressing oxidative stress, the inflammatory response, and apoptosis, improving liver proliferation and upregulating p-eNOS expression.

Chronic Regulation of miR-124-3p in the Perilesional Cortex after Experimental and Human TBI

Traumatic brain injury (TBI) dysregulates microRNAs, which are the master regulators of gene expression. Here we investigated the changes in a brain-enriched miR-124-3p, which is known to associate with major post-injury pathologies, such as neuroinflammation. RT-qPCR of the rat tissue sampled at 7 d and 3 months in the perilesional cortex adjacent to the necrotic lesion core (aPeCx) revealed downregulation of miR-124-3p at 7 d (fold-change (FC) 0.13, p < 0.05 compared with control) and 3 months (FC 0.40, p < 0.05) post-TBI. In situ hybridization confirmed the downregulation of miR-124-3p at 7 d and 3 months post-TBI in the aPeCx (both p < 0.01). RT-qPCR confirmed the upregulation of the miR-124-3p target Stat3 in the aPeCx at 7 d post-TBI (7-fold, p < 0.05). mRNA-Seq revealed 312 downregulated and 311 upregulated miR-124 targets (p < 0.05). To investigate whether experimental findings translated to humans, we performed in situ hybridization of miR-124-3p in temporal lobe autopsy samples of TBI patients. Our data revealed downregulation of miR-124-3p in individual neurons of cortical layer III. These findings indicate a persistent downregulation of miR-124-3p in the perilesional cortex that might contribute to post-injury neurodegeneration and inflammation.

Pharmacological Benefits and Risk of Using Hormones in Organ Perfusion and Preservation Solutions in the Aspect of Minimizing Hepatic Ischemia-Reperfusion Injury during Storage

For several years, research has been carried out on the effectiveness of solutions for perfusion and preservation of organs, including the liver. There is a search for an optimal pharmacological composition of these solutions, allowing to preserve or improve vital functions of the organ for as long as possible until it is transplanted into a recipient. Hormones due to their properties, often resulting from their pleiotropic effects, may be a valuable component for optimizing the composition of liver perfusion and preservation solutions. The paper presents the current state of knowledge on liver perfusion and preservation solutions modified with hormones. It also shows the characteristics of the hormones evaluated, taking into account their physiological functions in the body.

Erythropoietin mediates brain-vascular-kidney crosstalk and may be a treatment target for pulmonary and resistant essential hypertension

Organ crosstalk pathways represent the next frontier for target-mining in molecular medicine for existing syndromes. Pulmonary hypertension and resistant essential hypertension are syndromes that have been proven elusive in etiology, and frequently refractory to first-line management. Underlying crosstalk mechanisms, not yet considered in these treatments, may hinder outcomes or unlock novel treatments. This review focuses systematically on erythropoietin, a synthesizable molecule, as a mediator of brain-kidney crosstalk. Insights gained from this review will be applied to cardiovascular diseases in a clinician-directed fashion.

New progress in roles of nitric oxide during hepatic ischemia reperfusion injury

Hepatic ischemia reperfusion injury (HIRI) is a clinical condition which may lead to cellular injury and organ dysfunction. The role of nitric oxide (NO) in HIRI is complicated and inconclusive. NO produced by endothelial nitric oxide synthase (eNOS) activation plays a protective role during early HIRI. But eNOS overexpression and the resulting excessive NO bioavailability can aggravate liver injury. NO induced by inducible nitric oxide synthase (iNOS) may have either a protective or a deleterious effect during the early phase of HIRI, but it may protect the liver during late HIRI. Here, we reviewed the latest findings on the role of NO during HIRI: (1) NO exerts a protective effect against HIRI by increasing NO bioavailability, downregulating p53 gene expression, decreasing inflammatory chemokines, reducing ROS via inhibiting the mitochondrial respiratory chain, activating sGC-GTP-cGMP signal pathway to reduce liver cell apoptosis, and regulating hepatic immune functions; (2) eNOS protects against HIRI by increasing NO levels, several eNOS/NO signal pathways (such as Akt-eNOS/NO, AMPK-eNOS/NO and HIF-1α-eNOS/NO) participating in the anti-HIRI process, and inhibiting over-expression of eNOS also protects against HIRI; and (3) the inhibition of iNOS prevents HIRI. Thus, the adverse effects of NO should be avoided, but its positive effect in the clinical treatment of diseases associated with HIRI should be recognized.

Akt: A Therapeutic Target in Hepatic Ischemia-Reperfusion Injury

BACKGROUND

Liver transplantation is the second most common transplant procedure in the United States. A leading cause of post-transplantation organ dysfunction is I/R injury. During I/R injury, the serine/threonine kinase Akt is activated, stimulating downstream mediators to promote cellular survival. Due to the cellular effects of Akt, therapeutic manipulation of the Akt pathway can help reduce cellular damage during hepatic I/R that occurs during liver transplantation.

OBJECTIVE

A full description of therapeutic options available that target Akt to reduce hepatic I/R injury has not been addressed within the literature. The purpose of this review is to illuminate advances in the manipulation of Akt that can be used to therapeutically target I/R injury in the liver.

METHODS

An in depth literature review was performed using the Scopus and PubMed databases. A total of 75 published articles were utilized for this manuscript. Terminology searched includes a combination of "hepatic ischemia/reperfusion injury", "Akt/PKB", "preconditioning" and "postconditioning."

RESULTS

Four principal methods that reduce I/R injury include hepatic pre- and postconditioning, pharmacological intervention and future miRNA/gene therapy. Discussed therapies used serum alanine aminotransferase levels, liver histology and phosphorylation of downstream mediators to confirm the Akt protective effect.

CONCLUSION

The activation of Akt from the reviewed therapies has resulted in predictable reduction in hepatocyte damage using the previously mentioned measurements. In a clinical setting, these therapies could potentially be used in combination to achieve better outcomes in hepatic transplant patients. Evidence supporting reduced I/R injury through Akt activation warrants further studies in human clinical trials.

Hepatic ischemia reperfusion injury: A systematic review of literature and the role of current drugs and biomarkers

Hepatic ischemia reperfusion injury (IRI) is not only a pathophysiological process involving the liver, but also a complex systemic process affecting multiple tissues and organs. Hepatic IRI can seriously impair liver function, even producing irreversible damage, which causes a cascade of multiple organ dysfunction. Many factors, including anaerobic metabolism, mitochondrial damage, oxidative stress and secretion of ROS, intracellular Ca(2+) overload, cytokines and chemokines produced by KCs and neutrophils, and NO, are involved in the regulation of hepatic IRI processes. Matrix Metalloproteinases (MMPs) can be an important mediator of early leukocyte recruitment and target in acute and chronic liver injury associated to ischemia. MMPs and neutrophil gelatinase-associated lipocalin (NGAL) could be used as markers of I-R injury severity stages. This review explores the relationship between factors and inflammatory pathways that characterize hepatic IRI, MMPs and current pharmacological approaches to this disease.

Role of JAK-STAT pathway in reducing cardiomyocytes hypoxia/reoxygenation injury induced by S1P postconditioning

This experiment was designed to explore the protection of sphingosine1-phosphate (S1P) postconditioning on rat myocardial cells injured by hypoxia/reoxygenation acting via the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signal pathway. The data showed that S1P could significantly increase cell viability, lower the rate of apoptosis, decrease the content of lactate dehydrogenase (LDH) and caspase3 activity in the culture medium, increase the activity of total superoxide dismutase (T-SOD) and manganese superoxide dismutase (Mn-SOD), reduce the loss of mitochondrial membrane potential and the fluorescence intensity of intracellular calcium, as well as increase the phosphorylation of JAK2 and STAT3 in comparison with the H/R group. When the JAK inhibitor AG490 or the STAT inhibitor stattic were added, the effects of S1P were inhibited. Our date shows that S1P protects H9c2 cells from hypoxia/reoxygenation injury and that the protection by S1P was inhibited by AG490 and stattic. Therefore S1P protects H9c2 cells against hypoxia/reoxygenation injury via the JAK-STAT pathway.

Regeneration in the nervous system with erythropoietin

Globally, greater than 30 million individuals are afflicted with disorders of the nervous system accompanied by tens of thousands of new cases annually with limited, if any, treatment options. Erythropoietin (EPO) offers an exciting and novel therapeutic strategy to address both acute and chronic neurodegenerative disorders. EPO governs a number of critical protective and regenerative mechanisms that can impact apoptotic and autophagic programmed cell death pathways through protein kinase B (Akt), sirtuins, mammalian forkhead transcription factors, and wingless signaling. Translation of the cytoprotective pathways of EPO into clinically effective treatments for some neurodegenerative disorders has been promising, but additional work is necessary. In particular, development of new treatments with erythropoiesis-stimulating agents such as EPO brings several important challenges that involve detrimental vascular outcomes and tumorigenesis. Future work that can effectively and safely harness the complexity of the signaling pathways of EPO will be vital for the fruitful treatment of disorders of the nervous system.

Erythropoietin and diabetes mellitus

Erythropoietin (EPO) is a 30.4 kDa growth factor and cytokine that governs cell proliferation, immune modulation, metabolic homeostasis, vascular function, and cytoprotection. EPO is under investigation for the treatment of variety of diseases, but appears especially suited for the treatment of disorders of metabolism that include diabetes mellitus (DM). DM and the complications of this disease impact a significant portion of the global population leading to disability and death with currently limited therapeutic options. In addition to its utility for the treatment of anemia, EPO can improve cardiac function, reduce fatigue, and improve cognition in patients with DM as well as regulate cellular energy metabolism, obesity, tissue repair and regeneration, apoptosis, and autophagy in experimental models of DM. Yet, EPO can have adverse effects that involve the vasculature system and unchecked cellular proliferation. Critical to the cytoprotective capacity and the potential for a positive clinical outcome with EPO are the control of signal transduction pathways that include protein kinase B, the mechanistic target of rapamycin, Wnt signaling, mammalian forkhead transcription factors of the O class, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), and AMP activated protein kinase. Therapeutic strategies that can specifically target and control EPO and its signaling pathways hold great promise for the development of new and effective clinical treatments for DM and the complications of this disorder.

Potential Use of Biological Proteins for Liver Failure Therapy

Biological proteins have unlimited potential for use as pharmaceutical products due to their various biological activities, which include non-toxicity, biocompatibility, and biodegradability. Recent scientific advances allow for the development of novel innovative protein-based products that draw on the quality of their innate biological activities. Some of them hold promising potential for novel therapeutic agents/devices for addressing hepatic diseases such as hepatitis, fibrosis, and hepatocarcinomas. This review attempts to provide an overview of the development of protein-based products that take advantage of their biological activity for medication, and discusses possibilities for the therapeutic potential of protein-based products produced through different approaches to specifically target the liver (or hepatic cells: hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells, and Kupffer cells) in the treatment of hepatic diseases.

Cutting through the complexities of mTOR for the treatment of stroke

On a global basis, at least 15 million individuals suffer some form of a stroke every year. Of these individuals, approximately 800,000 of these cerebrovascular events occur in the United States (US) alone. The incidence of stroke in the US has declined from the third leading cause of death to the fourth, a result that can be attributed to multiple factors that include improved vascular disease management, reduced tobacco use, and more rapid time to treatment in patients that are clinically appropriate to receive recombinant tissue plasminogen activator. However, treatment strategies for the majority of stroke patients are extremely limited and represent a critical void for care. A number of new therapeutic considerations for stroke are under consideration, but it is the mammalian target of rapamycin (mTOR) that is receiving intense focus as a potential new target for cerebrovascular disease. As part of the phosphoinositide 3-kinase (PI 3-K) and protein kinase B (Akt) cascade, mTOR is an essential component of mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) to govern cell death involving apoptosis, autophagy, and necroptosis, cellular metabolism, and gene transcription. Vital for the consideration of new therapeutic strategies for stroke is the ability to understand how the intricate and complex pathways of mTOR signaling sometimes lead to disparate clinical outcomes.

Effects of JAK2-STAT3 signaling after cerebral insults

The JAK2-STAT3 signaling pathway has been shown to regulate the expression of genes involved in cell survival, cell proliferation, cell-cycle progression, and angiogenesis in development and after cerebral insults. Until recently, little has been known about the effects of this pathway activation after cerebral insults and if blocking this pathway leads to better recovery. This review exams the role of this pathway after 3 cerebral insults (traumatic brain injury, stroke, and status epilepticus).

Recombinant adiponectin ameliorates liver ischemia reperfusion injury via activating the AMPK/eNOS pathway

BACKGROUND

It is of importance to minimize ischemia reperfusion (I/R) injury during liver operations. Reducing the inflammatory reaction is an effective way to achieve this goal. Notably, adiponectin (APN) was found to have anti-inflammatory activity in heart and renal I/R injury. Herein, we investigated the role of APN in liver I/R injury.

METHODS

WISTAR RATS WERE RANDOMIZED TO FOUR GROUPS: (1) sham group; (2) I/R control group; (3) I/R+APN group; and (4) I/R+APN+AMPK inhibitor group. Liver and blood samples were collected 6h and 24h after reperfusion. Liver function and histopathologic changes were assessed. Macrophage and neutrophil infiltration was detected by immunohistochemistry staining, while pro-inflammatory cytokines and chemokines released in the liver were measured using ELISA and RT-PCR, respectively. Apoptosis was analyzed by TUNEL staining and caspase-3 expression in the liver. Downstream molecules of APN were investigated by Western blotting.

RESULTS

Circulatory APN was down-regulated during liver I/R. When exogenous APN treatment was administered during liver I/R, alanine transaminase (ALT) and aspartate aminotransferase (AST) were decreased, and less hepatocyte necrosis was observed. Less inflammatory cell infiltration and pro-inflammatory cytokines/chemokines release were also observed in the I/R+APN group when compared with the I/R control group. APN treatment also reduced hepatocyte apoptosis, evidenced by reduced TUNEL positive cells and less caspase-3 expression in the reperfused liver. Finally, the AMPK/eNOS pathway was found to be activated by APN, and administration of an AMPK inhibitor reversed the beneficial effects of APN.

CONCLUSION

APN can protect the liver from I/R injury by reducing the inflammatory response and hepatocyte apoptosis, a process that likely involves the AMPK/eNOS pathway. The current study provides a potential pharmacologic target for liver I/R injury.