Activation of T-LAK-cell-originated protein kinase-mediated antioxidation protects against focal cerebral ischemia-reperfusion injury

Research hotspots and frontiers of preconditioning in cerebral ischemia: A bibliometric analysis

Background

Preconditioning is a promising strategy against ischemic brain injury, and numerous studies in vitro and in vivo have demonstrated its neuroprotective effects. However, at present there is no bibliometric analysis of preconditioning in cerebral ischemia. Therefore, a comprehensive overview of the current status, hot spots, and emerging trends in this research field is necessary.

Materials and methods

Studies on preconditioning in cerebral ischemia from January 1999-December 2022 were retrieved from the Web of Science Core Collection (WOSCC) database. CiteSpace was used for data mining and visual analysis.

Results

A total of 1738 papers on preconditioning in cerebral ischemia were included in the study. The annual publications showed an upwards and then downwards trend but currently remain high in terms of annual publications. The US was the leading country, followed by China, the most active country in recent years. Capital Medical University published the largest number of articles. Perez-Pinzon, Miguel A contributed the most publications, while KITAGAWA K was the most cited author. The focus of the study covered three areas: (1) relevant diseases and experimental models, (2) types of preconditioning and stimuli, and (3) mechanisms of ischemic tolerance. Remote ischemic preconditioning, preconditioning of mesenchymal stem cells (MSCs), and inflammation are the frontiers of research in this field.

Conclusion

Our study provides a visual and scientific overview of research on preconditioning in cerebral ischemia, providing valuable information and new directions for researchers.

Nrf2 Regulates Oxidative Stress and Its Role in Cerebral Ischemic Stroke

Cerebral ischemic stroke is characterized by acute ischemia in a certain part of the brain, which leads to brain cells necrosis, apoptosis, ferroptosis, pyroptosis, etc. At present, there are limited effective clinical treatments for cerebral ischemic stroke, and the recovery of cerebral blood circulation will lead to cerebral ischemia-reperfusion injury (CIRI). Cerebral ischemic stroke involves many pathological processes such as oxidative stress, inflammation, and mitochondrial dysfunction. Nuclear factor erythroid 2-related factor 2 (Nrf2), as one of the most critical antioxidant transcription factors in cells, can coordinate various cytoprotective factors to inhibit oxidative stress. Targeting Nrf2 is considered as a potential strategy to prevent and treat cerebral ischemia injury. During cerebral ischemia, Nrf2 participates in signaling pathways such as Keap1, PI3K/AKT, MAPK, NF-κB, and HO-1, and then alleviates cerebral ischemia injury or CIRI by inhibiting oxidative stress, anti-inflammation, maintaining mitochondrial homeostasis, protecting the blood-brain barrier, and inhibiting ferroptosis. In this review, we have discussed the structure of Nrf2, the mechanisms of Nrf2 in cerebral ischemic stroke, the related research on the treatment of cerebral ischemia through the Nrf2 signaling pathway in recent years, and expounded the important role and future potential of the Nrf2 pathway in cerebral ischemic stroke.

Peptide OM-LV20 protects astrocytes against oxidative stress via the 'PAC1R/JNK/TPH1' axis

Stroke can lead to severe nerve injury and debilitation, resulting in considerable social and economic burdens. Due to the high complexity of post-injury repair mechanisms, drugs approved for use in stroke are extremely scarce, and thus, the discovery of new antistroke drugs and targets is critical. Tryptophan hydroxylase 1 (TPH1) is involved in a variety of mental and neurobehavioral processes, but its effects on stroke have not yet been reported. Here, we used primary astrocyte culture, quantitative real-time PCR, double immunofluorescence assay, lentiviral infection, cell viability analysis, Western blotting, and other biochemical experiments to explore the protective mechanism of peptide OM-LV20, which previously exhibited neuroprotective effects in rats after ischemic stroke via a mechanism that may involve TPH1. First, we showed that TPH1 was expressed in rat astrocytes. Next, we determined that OM-LV20 impacted expression changes of TPH1 in CTX-TNA2 cells and exhibited a protective effect on the decrease in cell viability and catalase (CAT) levels induced by hydrogen peroxide. Importantly, we also found that TPH1 expression induced by OM-LV20 may be related to the level of change in the pituitary adenylate cyclase-activating peptide type 1 receptor (PAC1R) and to the JNK signaling pathways, thereby exerting a protective effect on astrocytes against oxidative stress. The protective effects of OM-LV20 likely occur via the ‘PAC1R/JNK/TPH1’ axis, thus highlighting TPH1 as a novel antistroke drug target.

Inactivation of TOPK Caused by Hyperglycemia Blocks Diabetic Heart Sensitivity to Sevoflurane Postconditioning by Impairing the PTEN/PI3K/Akt Signaling

The cardioprotective effect of sevoflurane postconditioning (SPostC) is lost in diabetes that is associated with cardiac phosphatase and tensin homologue on chromosome 10 (PTEN) activation and phosphoinositide 3-kinase (PI3K)/Akt inactivation. T-LAK cell-originated protein kinase (TOPK), a mitogen-activated protein kinase- (MAPKK-) like serine/threonine kinase, has been shown to inactivate PTEN (phosphorylated status), which in turn activates the PI3K/Akt signaling (phosphorylated status). However, the functions of TOPK and molecular mechanism underlying SPostC cardioprotection in nondiabetes but not in diabetes remain unknown. We presumed that SPostC exerts cardioprotective effects by activating PTEN/PI3K/Akt through TOPK in nondiabetes and that impairment of TOPK/PTEN/Akt blocks diabetic heart sensitivity to SPostC. We found that in the nondiabetic C57BL/6 mice, SPostC significantly attenuated postischemic infarct size, oxidative stress, and myocardial apoptosis that was accompanied with enhanced p-TOPK, p-PTEN, and p-Akt. These beneficial effects of SPostC were abolished by either TOPK kinase inhibitor HI-TOPK-032 or PI3K/Akt inhibitor LY294002. Similarly, SPostC remarkably attenuated hypoxia/reoxygenation-induced cardiomyocyte damage and oxidative stress accompanied with increased p-TOPK, p-PTEN, and p-Akt in H9c2 cells exposed to normal glucose, which were canceled by either TOPK inhibition or Akt inhibition. However, either in streptozotocin-induced diabetic mice or in H9c2 cells exposed to high glucose, the cardioprotective effect of SPostC was canceled, accompanied by increased oxidative stress, decreased TOPK phosphorylation, and impaired PTEN/PI3K/Akt signaling. In addition, TOPK overexpression restored posthypoxic p-PTEN and p-Akt and decreased cell death and oxidative stress in H9c2 cells exposed to high glucose, which was blocked by PI3K/Akt inhibition. In summary, SPostC prevented myocardial ischemia/reperfusion injury possibly through TOPK-mediated PTEN/PI3K/Akt activation and impaired activation of this signaling pathway may be responsible for the loss of SPostC cardioprotection by SPostC in diabetes.

PBK/TOPK: A Therapeutic Target Worthy of Attention

Accumulating evidence supports the role of PDZ-binding kinase (PBK)/T-lymphokine-activated killer-cell-originated protein kinase (TOPK) in mitosis and cell-cycle progression of mitotically active cells, especially proliferative malignant cells. PBK/TOPK was confirmed to be associated with the development, progression, and metastasis of malignancies. Therefore, it is a potential therapeutic target in cancer therapy. Many studies have been conducted to explore the clinical applicability of potent PBK/TOPK inhibitors. However, PBK/TOPK has also been shown to be overexpressed in normal proliferative cells, including sperm and neural precursor cells in the subventricular zone of the adult brain, as well as under pathological conditions, such as ischemic tissues, including the heart, brain, and kidney, and plays important roles in their physiological functions, including proliferation and self-renewal. Thus, more research is warranted to further our understanding of PBK/TOPK inhibitors before we can consider their applicability in clinical practice. In this study, we first review the findings, general features, and signaling mechanisms involved in the regulation of mitosis and cell cycle. We then review the functions of PBK/TOPK in pathological conditions, including tumors and ischemic conditions in the heart, brain, and kidney. Finally, we summarize the advances in potent and selective inhibitors and describe the potential use of PBK/TOPK inhibitors in clinical settings.

Synthesis of Paeonol-Ozagrel Conjugate: Structure Characterization and In Vivo Anti-Ischemic Stroke potential

Ischemic stroke is a common neurological disease that can lead to mortality and disability. The current curative effect remains unsatisfactory because drug accumulation in the diseased areas is insufficient as a result of the unique blood–brain barrier. Therefore, much attention has been paid to develop a novel therapeutic compound, paeonol-ozagrel conjugate (POC), for ischemic stroke. Then, POC was successfully synthesized by conjugating of paeonol and ozagrel as mutual prodrug. A series of in vitro characterizations and evaluations, including high - resolution mass spectroscopy, nuclear magnetic resonance spectroscopy, partition coefficient, and assessment of cytotoxicity against PC12 cells, were performed. Pharmacokinetic study demonstrated POC is eliminated quickly (t_1/2 = 53.46 ± 19.64 min), which supported a short dosing interval. The neurological score, infarct volume, histopathological changes, oxidative stress, inflammatory cytokines levels, and TXA₂ levels also were evaluated in vivo in middle cerebral artery occlusion (MCAO) rats. All results showed that POC had a significant curative and therapeutic effect on ischemic stroke, as evaluated by the middle cerebral artery occlusion. Overall, POC can be expected to become a new drug candidate for the treatment of ischemic stroke.

Targeting Oxidative Stress and Inflammation to Prevent Ischemia-Reperfusion Injury

The cerebral ischemia injury can result in neuronal death and/or functional impairment, which leads to further damage and dysfunction after recovery of blood supply. Cerebral ischemia/reperfusion injury (CIRI) often causes irreversible brain damage and neuronal injury and death, which involves many complex pathological processes including oxidative stress, amino acid toxicity, the release of endogenous substances, inflammation and apoptosis. Oxidative stress and inflammation are interactive and play critical roles in ischemia/reperfusion injury in the brain. Oxidative stress is important in the pathological process of ischemic stroke and is critical for the cascade development of ischemic injury. Oxidative stress is caused by reactive oxygen species (ROS) during cerebral ischemia and is more likely to lead to cell death and ultimately brain death after reperfusion. During reperfusion especially, superoxide anion free radicals, hydroxyl free radicals, and nitric oxide (NO) are produced, which can cause lipid peroxidation, inflammation and cell apoptosis. Inflammation alters the balance between pro-inflammatory and anti-inflammatory factors in cerebral ischemic injury. Inflammatory factors can therefore stimulate or exacerbate inflammation and aggravate ischemic injury. Neuroprotective therapies for various stages of the cerebral ischemia cascade response have received widespread attention. At present, neuroprotective drugs mainly include free radical scavengers, anti-inflammatory agents, and anti-apoptotic agents. However, the molecular mechanisms of the interaction between oxidative stress and inflammation, and their interplay with different types of programmed cell death in ischemia/reperfusion injury are unclear. The development of a suitable method for combination therapy has become a hot topic.

Interleukin-11 treatment protected against cerebral ischemia/reperfusion injury

OBJECTIVE

Inflammation and immune responses are crucial factors associated with the onset and progression of stroke. Interleukin-11 (IL-11) is a hematopoietic IL-6 family cytokine that functions as an anti-inflammatory agent against various inflammatory diseases. However, its roles in stroke remain unknown. In this study, we investigated the effects of IL-11 on cerebral ischemia-reperfusion injury in a model of focal cerebral ischemia.

METHODS

Mice were randomly divided into five groups the vehicle group, the middle cerebral artery occlusion (MCAO) group, the MCAO plus adenosine monophosphate-activated protein kinase (AMPK) inhibitor compound C group, the MCAO plus IL-11 treatment group, and the MCAO plus IL-11 treatment and compound C group. Focal cerebral ischemia was induced by occluding the left middle cerebral artery, and reperfusion was achieved by withdrawing the suture 2 h after ischemia. The protein expression levels of IL-11 were measured using Western blot analysis, and its location was detected using immunohistochemistry and immunofluorescence staining. The infarct volume was examined using 2,3,5-triphenyl tetrazolium chloride (TTC) staining, and the neurobehavioral progression was assessed using the neurological scoring system. The expression of astrocytes and microglia was detected using immunochemistry, and real-time quantitative PCR was used for the gene quantification of inflammatory cytokines. The extent of cerebral ischemia-reperfusion injury was tested using Nissl staining and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. The expression of the apoptotic proteins Bax, Bcl-2 and cleaved caspase-3 were detected using Western blot analysis, and the oxidative stress was also measured.

RESULTS

The expression of IL-11 mRNA and protein significantly decreased after cerebral ischemia. Immunohistochemical staining showed a large amount of IL-11 in the cerebral cortex of the mice in the vehicle group, whereas the immunoreactivity of IL-11 remained weak for 24 h in the MCAO group. Immunofluorescent staining further confirmed that IL-11 was mainly expressed in the neurons. It was suggested that IL-11 (20 μg/kg) treatment ameliorated infarction and reduced neurological scores. In addition, IL-11 proved to reduce neuropathic damage, glial activation, and the expression of proinflammatory cytokines and increase the expression of anti-inflammatory cytokines after cerebral ischemia. IL-11 was also able to alleviate oxidative stress caused by cerebral ischemia, and AMPK inhibition enhanced the alleviation. Moreover, IL-11 was found to inhibit apoptosis caused by cerebral ischemia, which could also be facilitated by AMPK inhibitors.

SIGNIFICANCE

Our research suggests that IL-11 is decreased during cerebral ischemia-reperfusion injury, but IL-11 treatment can improve neurological function and reduce the cerebral infarct volume, which can trigger stroke in mice. AMPK inhibition can further promote the protective effect of IL-11 in stroke. Overall, we demonstrate that IL-11 is of therapeutic interest in controlling stroke and managing cerebral ischemia-reperfusion injury.

A11, a novel diaryl acylhydrazone derivative, exerts neuroprotection against ischemic injury in vitro and in vivo

There is an urgent need to develop effective therapies for ischemic stroke, but the complicated pathological processes after ischemia make doing so difficult. In the current study, we identified a novel diaryl acylhydrazone derivative, A11, which has multiple neuroprotective properties in ischemic stroke models. First, A11 was demonstrated to induce neuroprotection against ischemic injury in a dose-dependent manner (from 0.3 to 3 μM) in three in vitro experimental ischemic stroke models: oxygen glucose deprivation (OGD), hydrogen peroxide, and glutamate-stimulated neuronal cell injury models. Moreover, A11 was able to potently alleviate three critical pathological changes, apoptosis, oxidative stress, and mitochondrial dysfunction, following ischemic insult in neuronal cells. Further analysis revealed that A11 upregulated the phosphorylation levels of protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) in OGD-exposed neuronal cells, suggesting joint activation of the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MEK)/ERK pathways. In rats with middle cerebral artery occlusion, single-dose administration of A11 (3 mg/kg per day, i.v.) at the onset of reperfusion significantly reduced the infarct volumes and ameliorated neurological deficits. Our study, for the first time, reports the anti-ischemic effect of diaryl acylhydrazone chemical entities, especially A11, which acts on multiple ischemia-associated pathological processes. Our results may provide new clues for the development of an effective therapeutic agent for ischemic stroke.

TOPK Promotes Microglia/Macrophage Polarization towards M2 Phenotype via Inhibition of HDAC1 and HDAC2 Activity after Transient Cerebral Ischemia

T-LAK-cell-originated protein kinase (TOPK) is a newly identified member of the mitogen-activated protein kinase family. Our previous study has showed that TOPK has neuroprotective effects against cerebral ischemia-reperfusion injury. Here, we investigated the involvement of TOPK in microglia/ macrophage M1/M2 polarization and the underlying epigenetic mechanism. The expression profiles, co-localization and in vivo interaction of TOPK, M1/M2 surface markers, and HDAC1/HDAC2 were detected after middle cerebral artery occlusion models (MCAO). We demonstrated that TOPK, the M2 surface markers CD206 and Arg1, p-HDAC1, and p-HDAC2 showed a similar pattern of in vivo expression over time after MCAO. TOPK co-localized with CD206, p-HDAC1, and p-HDAC2 positive cells, and was shown to bind to HDAC1 and HDAC2. In vitro study showed that TOPK overexpression in BV2 cells up-regulated CD206 and Arg1, and promoted the phosphorylation of HDAC1 and HDAC2. In addition, TOPK overexpression also prevented LPS plus IFN-γ-induced M1 transformation through reducing release of inflammatory factor of M1 phenotype TNF-α, IL-6 and IL-1β, and increasing TGF-β release and the mRNA levels of TGF-β and SOCS3, cytokine of M2 phenotype and its regulator. Moreover, the increased TNF-α induced by TOPK siRNA could be reversed by HDAC1/HDAC2 inhibitor, FK228. TOPK overexpression increased M2 marker expression in vivo concomitant with the amelioration of cerebral injury, neurological functions deficits, whereas TOPK silencing had the opposite effects, which were completely reversed by the FK228 and partially by the SAHA. These findings suggest that TOPK positively regulates microglia/macrophage M2 polarization by inhibiting HDAC1/HDAC2 activity, which may contribute to its neuroprotective effects against cerebral ischemia-reperfusion injury.

Efficacy and safety of cord blood-derived dendritic cells plus cytokine-induced killer cells combined with chemotherapy in the treatment of patients with advanced gastric cancer: a randomized Phase II study

Background

Cellular immunotherapy has been widely used in the treatment of solid tumors. However, the clinical application of cord blood-derived dendritic cells and cytokine-induced killer cells (CB-DC-CIK) for the treatment of gastric cancer has not been frequently reported. In this study, the efficacy and safety of CB-DC-CIK for the treatment of gastric cancer were evaluated both in vitro and in vivo.

Methods

The phenotypes, cytokines, and cytotoxicity of CB-DC-CIK were detected in vitro. Patients with advanced gastric cancer were divided into the following two groups: the experimental group (CB-DC-CIK combined with chemotherapy) and the control group (chemotherapy alone). The curative effects and immune function were compared between the two groups.

Results

First, the results showed that combination therapy significantly increased the overall disease-free survival rate (P=0.0448) compared with chemotherapy alone. The overall survival rate (P=0.0646), overall response rate (P=0.410), and disease control rate (P=0.396) were improved in the experimental group, but these changes did not reach statistical significance. Second, the percentage of T-cell subsets (CD4⁺, CD3⁻CD56⁺, and CD3⁺CD56⁺) and the levels of IFN-γ, TNF-α, and IL-2, which reflect immune function, were significantly increased (P<0.05) after immunotherapy. Finally, no serious side effects appeared in patients with gastric cancer after the application of cellular immunotherapy based on CB-DC-CIK.

Conclusion

CB-DC-CIK combined with chemotherapy is effective and safe for the treatment of patients with advanced gastric cancer.

The Protective Role of the TOPK/PBK Pathway in Myocardial Ischemia/Reperfusion and H₂O₂-Induced Injury in H9C2 Cardiomyocytes

T-LAK-cell-originated protein kinase (TOPK) is a PDZ-binding kinase (PBK) that was recently identified as a novel member of the mitogen-activated protein kinase (MAPK) family. It has been shown to play an important role in many cellular functions. However, its role in cardiac function remains unclear. Thus, we have herein explored the biological function of TOPK in myocardial ischemia/reperfusion (I/R) and oxidative stress injury in H9C2 cardiomyocytes. I/R and ischemic preconditioning (IPC) were induced in rats by 3-hour reperfusion after 30-min occlusion of the left anterior descending coronary artery and by 3 cycles of 5-min I/R. Hydrogen peroxide (H₂O₂) was used to induce oxidative stress in H9C2 cardiomyocytes. TOPK expression was analyzed by western blotting, RT-PCR, immunohistochemical staining, and immunofluorescence imaging studies. The effects of TOPK gene overexpression and its inhibition via its inhibitor HI-TOPK-032 on cell viability and Bcl-2, Bax, ERK1/2, and p-ERK1/2 protein expression were analyzed by MTS assay and western blotting, respectively. The results showed that IPC alleviated myocardial I/R injury and induced TOPK activation. Furthermore, H₂O₂ induced TOPK phosphorylation in a time-dependent manner. Interestingly, TOPK inhibition aggravated the H₂O₂-induced oxidative stress injury in myocardiocytes, whereas overexpression relieved it. In addition, the ERK pathway was positively regulated by TOPK signaling. In conclusion, our results indicate that TOPK might mediate a novel survival signal in myocardial I/R, and that its effect on anti-oxidative stress involves the ERK signaling pathway.

Baclofen mediates neuroprotection on hippocampal CA1 pyramidal cells through the regulation of autophagy under chronic cerebral hypoperfusion

GABA receptors play an important role in ischemic brain injury. Studies have indicated that autophagy is closely related to neurodegenerative diseases. However, during chronic cerebral hypoperfusion, the changes of autophagy in the hippocampal CA1 area, the correlation between GABA receptors and autophagy, and their influences on hippocampal neuronal apoptosis have not been well established. Here, we found that chronic cerebral hypoperfusion resulted in rat hippocampal atrophy, neuronal apoptosis, enhancement and redistribution of autophagy, down-regulation of Bcl-2/Bax ratio, elevation of cleaved caspase-3 levels, reduction of surface expression of GABAA receptor α1 subunit and an increase in surface and mitochondrial expression of connexin 43 (CX43) and CX36. Chronic administration of GABAB receptors agonist baclofen significantly alleviated neuronal damage. Meanwhile, baclofen could up-regulate the ratio of Bcl-2/Bax and increase the activation of Akt, GSK-3β and ERK which suppressed cytodestructive autophagy. The study also provided evidence that baclofen could attenuate the decrease in surface expression of GABAA receptor α1 subunit, and down-regulate surface and mitochondrial expression of CX43 and CX36, which might enhance protective autophagy. The current findings suggested that, under chronic cerebral hypoperfusion, the effects of GABAB receptors activation on autophagy regulation could reverse neuronal damage.