The effect of intracerebroventricular application of the caspase-3 inhibitor zDEVD-FMK on neurological outcome and neuronal cell death after global cerebral ischaemia due to cardiac arrest in rats

The tRF-3024b hijacks miR-192-5p to increase BCL-2-mediated resistance to cytotoxic T lymphocytes in Esophageal Squamous Cell Carcinoma

The limited efficacy of immune checkpoint inhibitors (ICIs) in the treatment of advanced Esophageal Squamous Cell Carcinoma (ESCC) poses a challenge. Recent evidence suggests that tumor cells' insensitivity to cytotoxic T lymphocytes (CTLs) contributes to drug resistance against ICIs. Here, a particular tRNA-derived fragment called tRF-3024b has been identified as playing a significant role in tumor cell resistance to CTLs. Through tRF sequencing (tRF-seq), we observed a high expression of tRF-3024b in ESCC cells that survived co-culture with CTLs. Further in vitro studies demonstrated that tRF-3024b reduced the apoptosis of tumor cells when co-cultured with CTLs. The mechanism behind this resistance involves tRF-3024b promoting the expression of B-cell lymphoma-2 (BCL-2) by sequestering miR-192-5p, a microRNA that would normally inhibit BCL-2 expression. This means that tRF-3024b indirectly enhances the protective effects of BCL-2, reducing apoptosis in tumor cells. Rescue assays confirmed that the suppressive function of tRF-3024b relies on BCL-2. In summary, the tRF-3024b/miR-192-5p/BCL-2 axis sheds light on the crucial role of tRF-3024b in regulating BCL-2 expression. These findings offer valuable insights into strategies to enhance the response of ESCC to CTLs and improve the effectiveness of immunotherapy approaches in treating ESCC.

Peptidyl Fluoromethyl Ketones and Their Applications in Medicinal Chemistry

Peptidyl fluoromethyl ketones occupy a pivotal role in the current scenario of synthetic chemistry, thanks to their numerous applications as inhibitors of hydrolytic enzymes. The insertion of one or more fluorine atoms adjacent to a C-terminal ketone moiety greatly modifies the physicochemical properties of the overall substrate, especially by increasing the reactivity of this functionalized carbonyl group toward nucleophiles. The main application of these peptidyl α-fluorinated ketones in medicinal chemistry relies in their ability to strongly and selectively inhibit serine and cysteine proteases. These compounds can be used as probes to study the proteolytic activity of the aforementioned proteases and to elucidate their role in the insurgence and progress on several diseases. Likewise, if the fluorinated methyl ketone moiety is suitably connected to a peptidic backbone, it may confer to the resulting structure an excellent substrate peculiarity and the possibility of being recognized by a specific subclass of human or pathogenic proteases. Therefore, peptidyl fluoromethyl ketones are also currently highly exploited for the target-based design of compounds for the treatment of topical diseases such as various types of cancer and viral infections.

Berberine Inhibits the Apoptosis-Induced Metastasis by Suppressing the iPLA2/LOX-5/LTB4 Pathway in Hepatocellular Carcinoma

Purpose

Hepatocellular carcinoma (HCC) is one of the most malignant cancers around the world. HCC is less sensitive to conventional cytotoxic agents and easily develops into systemic metastases. However, the molecular mechanisms of the metastasis of HCC are poorly understood and need elucidation.

Materials and Methods

Transwell system of the chemotherapy-challenged and unchallenged HepG2 cells was established. Adhesion assay and scratch-wound assay were utilized to analyze the adhesion and migration of HepG2 cells. iPLA2 and LOX-5 expression were analyzed by Western blot. LTB4 level was analyzed by ELISA.

Results

Chemotherapeutics are traditionally regarded as a way of killing tumor cells; on the other hand, we proved that the chemotherapeutics-induced tumor cell apoptosis can also change the tumor microenvironment by activating the LOX pathway and subsequently release inflammatory factors such as LTB4 which can stimulate the adhesion and migration of the small number of surviving cells. Berberine can reverse the adhesion and migration of HepG2 cells by inhibiting the expression of LOX-5 and reducing the LTB4 production in the tumor microenvironment.

Conclusion

Our study sheds light on a novel anti-metastasis strategy that the combination of Berberine and chemotherapy may prevent the chemotherapy-induced metastasis in HCC.

Positron Emission Tomography Imaging of Long-Term Expression of the 18 kDa Translocator Protein After Sudden Cardiac Arrest in Rats

BACKGROUND

Knowledge about the neuroinflammatory state during months after sudden cardiac arrest is scarce. Neuroinflammation is mediated by cells that express the 18 kDa translocator protein (TSPO). We determined the time course of TSPO-expressing cells in a rat model of sudden cardiac arrest using longitudinal in vivo positron emission tomography (PET) imaging with the TSPO-specific tracer [18F]DAA1106 over a period of 6 months.

METHODS

Five male Sprague Dawley rats were resuscitated from 6 min sudden cardiac arrest due to ventricular fibrillation, three animals served as shams. PET measurements were performed on day 5, 8, 14, 90, and 180 after intervention. Magnetic resonance imaging was performed on day 140. Imaging was preceded by Barnes Maze spatial memory testing on day 3, 13, 90, and 180. Specificity of [18F]DAA1106 binding was confirmed by Iba-1 immunohistochemistry.

RESULTS

[18F]DAA1106 accumulated bilaterally in the dorsal hippocampus of all sudden cardiac arrest animals on all measured time points. Immunohistochemistry confirmed Iba-1 expressing cells in the hippocampal CA1 region. The number of Iba-1-immunoreactive objects per mm2 was significantly correlated with [18F]DAA1106 uptake. Additionally, two of the five sudden cardiac arrest rats showed bilateral TSPO-expression in the striatum that persisted until day 180. In Barnes Maze, the relative time spent in the target quadrant negatively correlates with dorsal hippocampal [18F]DAA1106 uptake on day 14 and 180.

CONCLUSIONS

After sudden cardiac arrest, TSPO remains expressed over the long-term. Sustainable treatment options for neuroinflammation may be considered to improve cognitive functions after sudden cardiac arrest.

Bone marrow mesenchymal stem cells repair the hippocampal neurons and increase the expression of IGF-1 after cardiac arrest in rats

The present study aimed to investigate the beneficial effects and underlying mechanisms of bone marrow mesenchymal stem cells (BMSCs) on global ischemic hypoxic brain injury. Cells collected from the femurs and tibias of male Sprague Dawley rats were used to generate BMSCs following three culture passages. A rate model of cardiac arrest (CA) was induced by asphyxia. One hour following return of spontaneous circulation (ROSC), BMSCs were transplanted through injection into the tail vein. Neurological status was assessed using modified neurological severity score (mNSS) tests 1, 3 and 7 days following ROSC. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemical staining were used to detect insulin-like growth factor 1 (IGF-1) expression in the hippocampus. Furthermore, double-fluorescent labeling of green fluorescent protein (GFP) and IGF-1 was used to detect the IGF-1 expression in transplanted BMSCs. Serum levels of protein S100-B were examined using ELISA. GFP-labeled BMSCs were observed in the hippocampus at 1, 3 and 7 days post transplantation through fluorescent microscopy. BMSC transplantation resulted in reduced protein S100-B levels. The mNSS of the BMSC-treatment group was significantly reduced compared with that of the CA group. The RT-qPCR analysis and immunohistochemistry results demonstrated that BMSC treatment significantly increased IGF-1 expression in the hippocampus. In addition, the double-fluorescent labeling results demonstrated that transplanted BMSCs expressed IGF-1 in the hippocampus. The results of the present study suggest that BMSC treatment promotes the recovery of cerebral function following CA in rats possibly through the secretion of IGF-1.

The Brain after Cardiac Arrest

Cardiac arrest is common and deadly. Most patients who are treated in the hospital after achieving return of spontaneous circulation still go on to die from the sequelae of anoxic brain injury. In this review, the authors provide an overview of the mechanisms and consequences of postarrest brain injury. Special attention is paid to potentially modifiable mechanisms of secondary brain injury including seizures, hyperpyrexia, cerebral hypoxia and hypoperfusion, oxidative injury, and the development of cerebral edema. Finally, the authors discuss the outcomes of cardiac arrest survivors with a focus on commonly observed patterns of injury as well as the scales used to measure patient outcome and their limitations.

A systematic review of neuroprotective strategies after cardiac arrest: from bench to bedside (Part I - Protection via specific pathways)

Neurocognitive deficits are a major source of morbidity in survivors of cardiac arrest. Treatment options that could be implemented either during cardiopulmonary resuscitation or after return of spontaneous circulation to improve these neurological deficits are limited. We conducted a literature review of treatment protocols designed to evaluate neurologic outcome and survival following cardiac arrest with associated global cerebral ischemia. The search was limited to investigational therapies that were utilized to treat global cerebral ischemia associated with cardiac arrest. In this review we discuss potential mechanisms of neurologic protection following cardiac arrest including actions of several medical gases such as xenon, argon, and nitric oxide. The 3 included mechanisms are: 1. Modulation of neuronal cell death; 2. Alteration of oxygen free radicals; and 3. Improving cerebral hemodynamics. Only a few approaches have been evaluated in limited fashion in cardiac arrest patients and results show inconclusive neuroprotective effects. Future research focusing on combined neuroprotective strategies that target multiple pathways are compelling in the setting of global brain ischemia resulting from cardiac arrest.

The effect of ischemic post-conditioning on hippocampal cell apoptosis following global brain ischemia in rats

We evaluated the effect of brain ischemic post-conditioning on cell apoptosis in the hippocampus following global brain ischemia in rats. Adult male Sprague-Dawley rats were randomly divided into three groups (n=15/group): sham operation, ischemia/reperfusion (I/R) and ischemic post-conditioning (I PostC). Global brain ischemia was induced by four-vessel occlusion. Ischemic post-conditioning consisted of six cycles of 10s/10s reperfusion/reocclusion at the onset of reperfusion. All rats were sacrificed 24 hours or 72 hours after reperfusion. The hippocampal CA1 regions were analysed using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end-labelling (Tunel) staining technique for determining cell apoptosis. Levels of caspase-3 and Bcl-2 were measured by Western blotting. After 72 hours, fewer Tunel-positive brain cells were observed in rats from the I PostC group than in rats from the I/R group (10.3 ± 2.7% versus 40.8 ± 6.2%, p<0.01). After reperfusion at 24 hours and 72 hours, expression of caspase-3 in the I PostC group was significantly decreased (p<0.01) and expression of Bcl-2 in the I PostC group was significantly increased (p<0.01) compared with the I/R group. We conclude that down-regulation of caspase-3 and up-regulation of Bcl-2 by ischemic post-conditioning may underlie the protective effects of post-conditioning.

Hypoxic preconditioning attenuates global cerebral ischemic injury following asphyxial cardiac arrest through regulation of delta opioid receptor system

This study was designed to investigate whether delta opioid receptor (DOR) is involved in the neuroprotective effect induced by hypoxic preconditioning (HPC) in the asphyxial cardiac arrest (CA) rat model. Twenty-four hours after the end of 7-day HPC, the rats were subjected to 8-min asphyxiation and resuscitated with a standardized method. In the asphyxial CA rat model, HPC improved the neurological deficit score (NDS), inhibited neuronal apoptosis, and increased the number of viable hippocampal CA1 neurons at 24 h, 72 h, or 7 days after restoration of spontaneous circulation (ROSC); however, the above-mentioned neuroprotection of HPC was attenuated by naltrindole (a selective DOR antagonist). The expression of hypoxia-inducible factor-1α (HIF-1α) and DOR, and the content of leucine enkephalin (L-ENK) in the brain were also investigated after the end of 7-day HPC. HPC upregulated the neuronal expression of HIF-1α and DOR, and synchronously elevated the content of L-ENK in the rat brain. HIF-1α siRNA was used to further elucidate the relationship between HIF-1α and DOR in the HPC-treated brain. Knockdown of HIF-1α by siRNA markedly abrogated the HPC induced upregulation of HIF-1α and DOR. The present study demonstrates that the expression of DOR in the rat brain is upregulated by HIF-1α following exposure to 7-day HPC, at the same time, HPC also increases the production of endogenous DOR ligand L-ENK in the brain. DOR activation after HPC results in prolonged neuroprotection against subsequent global cerebral ischemic injury, suggesting a new mechanism of HPC-induced neuroprotection on global cerebral ischemia following CA and resuscitation.