The p53 inactivators pifithrin-μ and pifithrin-α mitigate TBI-induced neuronal damage through regulation of oxidative stress, neuroinflammation, autophagy and mitophagy

Naoxintong capsule accelerates mitophagy in cerebral ischemia-reperfusion injury via TP53/PINK1/PRKN pathway based on network pharmacology analysis and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence and mortality of cerebrovascular diseases are increasing year by year. Cerebral ischemia-reperfusion injury (CIRI) is common in patients with ischemic stroke. Naoxintong (NXT) is composed of a variety of Chinese medicines and has the ability to treat CIRI.

AIM OF THE STUDY

The aim of this study is to investigate whether NXT regulates mitophagy in CIRI based on network pharmacology analysis and experimental validation.

MATERIALS AND METHODS

Oxygen and glucose deprivation/re-oxygenation (OGD/R, 2/22 h) model of PC12 cells and transient middle cerebral artery occlusion (tMCAO, 2/22 h) model of rats were established. Pharmacodynamic indicators include neurological deficit score, 2,3,5-triphenyte-trazoliumchloride (TTC) staining, hematoxylin-eosin (HE) staining and cell viability. Network pharmacology was used to predict pharmacological mechanisms. Pharmacological mechanism indexes include transmission electron microscopy (TEM), drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), immunohistochemistry (IHC), western blot (WB) and immunofluorescence (IF). Kevetrin (an agonists of p53) and pifithrin-α (an inhibitor of p53) used to detect the key role of p53 in mitophagy of NXT.

RESULTS

NXT (1% serum containing NXT and 110 mg/kg) improved the damage of OGD/R PC12 cells and tMCAO rats, and this protective effect was related to the anti-oxidation and ability to promote mitophagy of NXT. NXT and pifithrin-α increased the expression of promoting-mitophagy targets (PINK1, PRKN and LC3B) and inhibited the expression of inhibiting-mitophagy targets (p52) via restraining p53, and finally accelerated mitophagy caused by CIRI.

CONCLUSION

This study demonstrates that NXT promotes mitophagy in CIRI through restraining p53 and promoting PINK1/PRKN in vivo and in vitro.

Pifithrin-µ Induces Stress Granule Formation, Regulates Cell Survival, and Rewires Cellular Signaling

(1) Background: Stress granules (SGs) are cytoplasmic protein-RNA condensates that assemble in response to various insults. SG production is driven by signaling pathways that are relevant to human disease. Compounds that modulate SG characteristics are therefore of clinical interest. Pifithrin-µ is a candidate anti-tumor agent that inhibits members of the hsp70 chaperone family. While hsp70s are required for granulostasis, the impact of pifithrin-µ on SG formation is unknown. (2) Methods: Using HeLa cells as model system, cell-based assays evaluated the effects of pifithrin-µ on cell viability. Quantitative Western blotting assessed cell signaling events and SG proteins. Confocal microscopy combined with quantitative image analyses examined multiple SG parameters. (3) Results: Pifithrin-µ induced bona fide SGs in the absence of exogenous stress. These SGs were dynamic; their properties were determined by the duration of pifithrin-µ treatment. The phosphorylation of eIF2α was mandatory to generate SGs upon pifithrin-µ exposure. Moreover, the formation of pifithrin-µ SGs was accompanied by profound changes in cell signaling. Pifithrin-µ reduced the activation of 5'-AMP-activated protein kinase, whereas the pro-survival protein kinase Akt was activated. Long-term pifithrin-µ treatment caused a marked loss of cell viability. (4) Conclusions: Our study identified stress-related changes in cellular homeostasis that are elicited by pifithrin-µ. These insights are important knowledge for the appropriate therapeutic use of pifithrin-µ and related compounds.

Temporal and structural sensitivities of major biomarkers for detecting neuropathology after traumatic brain injury in the mouse

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality, especially in teenagers to young adults. In recent decades, different biomarkers and/or staining protocols have been employed to evaluate the post-injury development of pathological structures, but they have produced many contradictory findings. Since correctly identifying the underlying neuroanatomical changes is critical to advancing TBI research, we compared three commonly used markers for their ability to detect TBI pathological structures: Fluoro-Jade C, the rabbit monoclonal antibody Y188 against amyloid precursor protein and the NeuroSilver kit were used to stain adjacent slices from naïve or injured mouse brains harvested at different time points from 30 min to 3 months after lateral fluid percussion injury. Although not all pathological structures were stained by all markers at all time points, we found damaged neurons and deformed dendrites in gray matter, punctate and perivascular structures in white matter, and axonal blebs and Wallerian degeneration in both gray and white matter. The present study demonstrates the temporal and structural sensitivities of the three biomarkers: each marker is highly effective for a set of pathological structures, each of which in turn emerges at a particular time point. Furthermore, the different biomarkers showed different abilities at detecting identical types of pathological structures. In contrast to previous studies that have used a single biomarker at a single time range, the present report strongly recommends that a combination of different biomarkers should be adopted and different time points need to be checked when assessing neuropathology after TBI.

Pomalidomide Improves Motor Behavioral Deficits and Protects Cerebral Cortex and Striatum Against Neurodegeneration Through a Reduction of Oxidative/Nitrosative Damages and Neuroinflammation After Traumatic Brain Injury

Neuronal damage resulting from traumatic brain injury (TBI) causes disruption of neuronal projections and neurotransmission that contribute to behavioral deficits. Cellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is an early event following TBI. ROS often damage DNA, lipids, proteins, and carbohydrates while RNS attack proteins. The products of lipid peroxidation 4-hydroxynonenal (4-HNE) and protein nitration 3-nitrotyrosine (3-NT) are often used as indicators of oxidative and nitrosative damages, respectively. Increasing evidence has shown that striatum is vulnerable to damage from TBI with a disturbed dopamine neurotransmission. TBI results in neurodegeneration, oxidative stress, neuroinflammation, neuronal apoptosis, and autophagy in the striatum and contribute to motor or behavioral deficits. Pomalidomide (Pom) is a Food and Drug Administration (FDA)-approved immunomodulatory drug clinically used in treating multiple myeloma. We previously showed that Pom reduces neuroinflammation and neuronal death induced by TBI in rat cerebral cortex. Here, we further compared the effects of Pom in cortex and striatum focusing on neurodegeneration, oxidative and nitrosative damages, as well as neuroinflammation following TBI. Sprague-Dawley rats subjected to a controlled cortical impact were used as the animal model of TBI. Systemic administration of Pom (0.5 mg/kg, intravenous [i.v.]) at 5 h post-injury alleviated motor behavioral deficits, contusion volume at 24 h after TBI. Pom alleviated TBI-induced neurodegeneration stained by Fluoro-Jade C in both cortex and striatum. Notably, Pom treatment reduces oxidative and nitrosative damages in cortex and striatum and is more efficacious in striatum (93% reduction in 4-HNE-positive and 84% reduction in 3-NT-positive neurons) than in cerebral cortex (42% reduction in 4-HNE-positive and 55% reduction in 3-NT-positive neurons). In addition, Pom attenuated microgliosis, astrogliosis, and elevations of proinflammatory cytokines in cortical and striatal tissue. We conclude that Pom may contribute to improved motor behavioral outcomes after TBI through targeting oxidative/nitrosative damages and neuroinflammation.

Detection and verification of neurodegeneration after traumatic brain injury in the mouse: Immunohistochemical staining for amyloid precursor protein

Previous studies of human traumatic brain injury (TBI) have shown diffuse axonal injury as varicosities or spheroids in white matter (WM) bundles when using immunoperoxidase-ABC staining with 22C11, a mouse monoclonal antibody against amyloid precursor protein (APP). These findings have been interpreted as TBI-induced axonal pathology. In a mouse model of TBI however, when we used immunofluorescent staining with 22C11, as opposed to immunoperoxidase staining, we did not observe varicosities or spheroids. To explore this discrepancy, we performed immunofluorescent staining with Y188, an APP knockout-validated rabbit monoclonal that shows baseline immunoreactivity in neurons and oligodendrocytes of non-injured mice, with some arranged-like varicosities. In gray matter after injury, Y188 intensely stained axonal blebs. In WM, we encountered large patches of heavily stained puncta, heterogeneous in size. Scattered axonal blebs were also identified among these Y188-stained puncta. To assess the neuronal origin of Y188 staining after TBI we made use of transgenic mice with fluorescently labeled neurons and axons. A close correlation was observed between Y188-stained axonal blebs and fluorescently labeled neuronal cell bodies/axons. By contrast, no correlation was observed between Y188-stained puncta and fluorescent axons in WM, suggesting that these puncta in WM did not originate from axons, and casting further doubt on the nature of previous reports with 22C11. As such, we strongly recommend Y188 as a biomarker for detecting damaged neurons and axons after TBI. With Y188, stained axonal blebs likely represent acute axonal truncations that may lead to death of the parent neurons. Y188-stained puncta in WM may indicate damaged oligodendrocytes, whose death and clearance can result in secondary demyelination and Wallerian degeneration of axons. We also provide evidence suggesting that 22C11-stained varicosities or spheroids previously reported in TBI patients might be showing damaged oligodendrocytes, due to a cross-reaction between the ABC kit and upregulated endogenous biotin.

Activation of autophagy after blast-induced traumatic brain injury in mice

Injury mechanism and treatment of blast-induced traumatic brain injury (bTBI) has not made a breakthrough so far. Previous reports demonstrate autophagy is involved in regulating the pathophysiological process after TBI. Therefore, this study explored whether autophagy was activated after bTBI. A total of 108 mice were divided randomly into six groups: 6 h, 1 d, 3 d, 7 d, 14 d after bTBI groups and sham group. The protein levels of anti-microtubule associated protein 1 light chain 3B (LC3B, hereafter referred to as LC3), beclin1 and p62 were detected using western blot. Moreover, HO-1 and Nrf2 were localized using histologic staining. Immunofluorescence of LC3 and immunohistochemistry of beclin1 were performed. The autophagy-related ultrastructure was observed by TEM. LC3-II and beclin1 reached their peak on day 3 after bTBI, while p62 showed a continuous downward trend. Immunofluorescence and immunohistochemistry also confirmed that the expression levels of LC3 and beclin1 were the highest at 3 days after bTBI. Autophagic vesicles containing lysosomes or digestive residual structures were observed then. Autophagy was induced in the frontal lobe tissues of bTBI mice induced by moderate-intensity explosion, with a peak at 3d and a gradual decline thereafter.

DNA Methylation-Mediated Mfn2 Gene Regulation in the Brain: A Role in Brain Trauma-Induced Mitochondrial Dysfunction and Memory Deficits

Repeated mild traumatic brain injuries (rMTBI) affect mitochondrial homeostasis in the brain. However, mechanisms of long-lasting neurobehavioral effects of rMTBI are largely unknown. Mitofusin 2 (Mfn2) is a critical component of tethering complexes in mitochondria-associated membranes (MAMs) and thereby plays a pivotal role in mitochondrial functions. Herein, we investigated the implications of DNA methylation in the Mfn2 gene regulation, and its consequences on mitochondrial dysfunction in the hippocampus after rMTBI. rMTBI dramatically reduced the mitochondrial mass, which was concomitant with decrease in Mfn2 mRNA and protein levels. DNA hypermethylation at the Mfn2 gene promoter was observed post 30 days of rMTBI. The treatment of 5-Azacytidine, a pan DNA methyltransferase inhibitor, normalized DNA methylation levels at Mfn2 promoter, which further resulted into restoration of Mfn2 function. The normalization of Mfn2 function was well correlated with recovery in memory deficits in rMTBI-exposed rats. Since, glutamate excitotoxicity serves as a primary insult after TBI, we employed in vitro model of glutamate excitotoxicity in human neuronal cell line SH-SY5Y to investigate the causal epigenetic mechanisms of Mfn2 gene regulation. The glutamate excitotoxicity reduced Mfn2 levels via DNA hypermethylation at Mfn2 promoter. Loss of Mfn2 caused significant surge in cellular and mitochondrial ROS levels with lowered mitochondrial membrane potential in cultured SH-SY5Y cells. Like rMTBI, these consequences of glutamate excitotoxicity were also prevented by 5-AzaC pre-treatment. Therefore, DNA methylation serves as a vital epigenetic mechanism involved in Mfn2 expression in the brain; and this Mfn2 gene regulation may play a pivotal role in rMTBI-induced persistent cognitive deficits. Closed head weight drop injury method was employed to induce repeated mild traumatic brain (rMTBI) in jury in adult, male Wistar rats. rMTBI causes hyper DNA methylation at the Mfn2 promoter and lowers the Mfn2 expression triggering mitochondrial dysfunction. However, the treatment of 5-azacytidine normalizes DNA methylation at the Mfn2 promoter and restores mitochondrial function.

The Effects of Pifithrin-µ on Spermatogonial Stem Cell Viability and Pluripotency

INTRODUCTION

Spermatogonial stem cells (SSCs) offer remarkable competencies for animal reproduction and overcoming human disease as a result of their differentiation capability. We evaluated the effect of small molecule pifithrin-mu (PFT-µ), a well-known inhibitor of P53 on SSC biological processes such as viability, apoptosis, and gene expression pattern.

METHODS

The SSCs were isolated from the testes of adult NMRI mice and then cultured in DMEM/F12 medium containing 10% FBS. Then, they were characterized by the immunocytochemistry technique by high PLZF and low c-Kit expressions. SSC colony formation assay was carried out and their viability was estimated by methylthiazolyldiphenyl-tetrazolium bromide (MTT, or 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide) assay upon exposure to PFT-µ (0, 0.6, 1.2, 2.5, and 5 µm). The apoptosis percentages were also measured using FACS analysis, and finally, Oct4 and Stra8 expression at mRNA levels was assessed using real-time quantitative PCR.

RESULTS

The 0.6 and 1.2 µm PFT-µ improved the viability of SSC based on MTT assay results; however, 2.5 and 5 µm PFT-µ reduced SSC viability compared with the control group. Moreover, PFT-µ at lower concentrations enhanced the colony size of SSCs and diminished their apoptosis. As well, exposure to PFT-µ upregulated Oct4 expression while downregulating the meiotic entry marker, Stra8.

CONCLUSION

Based on findings, optimized concentrations of PFT-µ can decrease SSC apoptosis, and conversely potentiate their pluripotency and self-renewal capacities in vitro.

Neuroprotection of NRF2 against Ferroptosis after Traumatic Brain Injury in Mice

Ferroptosis and iron-related redox imbalance aggravate traumatic brain injury (TBI) outcomes. NRF2 is the predominant transcription factor regulating oxidative stress and neuroinflammation in TBI, but its role in iron-induced post-TBI damage is unclear. We investigated ferroptotic neuronal damage in the injured cortex and observed neurological deficits post-TBI. These were ameliorated by the iron chelator deferoxamine (DFO) in wild-type mice. In Nrf2-knockout (Nrf2−/−) mice, more sever ferroptosis and neurological deficits were detected. Dimethyl fumarate (DMF)-mediated NRF2 activation alleviated neural dysfunction in TBI mice, partly due to TBI-induced ferroptosis mitigation. Additionally, FTH-FTL and FSP1 protein levels, associated with iron metabolism and the ferroptotic redox balance, were highly NRF2-dependent post-TBI. Thus, NRF2 is neuroprotective against TBI-induced ferroptosis through both the xCT-GPX4- and FTH-FTL-determined free iron level and the FSP1-regulated redox status. This yields insights into the neuroprotective role of NRF2 in TBI-induced neuronal damage and its potential use in TBI treatment.

Fish oil fat emulsion alleviates traumatic brain injury in mice by regulation of microglia polarization

Microglia activation, a hallmark of brain neuroinflammation, contributes to the secondary damage following traumatic brain injury (TBI). To explore the potential roles of different fat emulsions-long chain triglyceride (LCT) / medium chain triglyceride (MCT) and fish oil (FO) fat emulsion in neuroprotection and neuroinflammation in TBI, in this study, we first generated the controlled cortical impact (CCI) model of TBI mice. Then either LCT/MCT or FO fat emulsion treated mice were studied by Nissl staining to assess the lesion volume. Sham and TBI mice treated with 0.9% saline were used as controls. The fatty acid composition in different TBI mouse brains was further evaluated by gas chromatography. Immunofluorescent staining and quantitative RT-PCR both demonstrated the suppression of pro-inflammatory microglia and upregulated anti-inflammatory microglia in FO fat emulsion treated TBI brain or primary microglia induced by lipopolysaccharide (LPS) in vitro. Furthermore, motor and cognitive behavioral tests showed FO fat emulsion could partially improve the motor function in TBI mice. Together, our results indicate that FO fat emulsion significantly alleviates the TBI injury and neuroinflammation probably by regulating microglia polarization.

Mitophagy and Traumatic Brain Injury: Regulatory Mechanisms and Therapeutic Potentials

Traumatic brain injury (TBI), a kind of external trauma-induced brain function alteration, has posed a financial burden on the public health system. TBI pathogenesis involves a complicated set of events, including primary and secondary injuries that can cause mitochondrial damage. Mitophagy, a process in which defective mitochondria are specifically degraded, segregates and degrades defective mitochondria allowing a healthier mitochondrial network. Mitophagy ensures that mitochondria remain healthy during TBI, determining whether neurons live or die. Mitophagy acts as a critical regulator in maintaining neuronal survival and healthy. This review will discuss the TBI pathophysiology and the consequences of the damage it causes to mitochondria. This review article will explore the mitophagy process, its key factors, and pathways and reveal the role of mitophagy in TBI. Mitophagy will be further recognized as a therapeutic approach in TBI. This review will offer new insights into mitophagy's role in TBI progression.

Inhibiting miR-186-5p relieves traumatic brain injury by regulating insulin-like growth factor-I-NLRP3/ASC/caspase-1 signaling pathway

Previous studies have shown that micro-RNA (miR)-186-5p can affect apoptosis of cells by regulating insulin-like growth factor-I (IGF-1). However, the role of miR-186-5p-IGF1 axis in traumatic brain injury (TBI), especially oxidative stress and neuroinflammatory response, remains to be further studied. Lipopolysaccharide (5 μg/mL) was used to activate microglia in vitro . The expression of miR-186-5p, IGF-1 was detected by quantitative reverse transcription PCR (qRT-PCR). ELISA and western blot were used to detect the inflammatory factors and oxidative stress. Western blot was used to detect apoptotic proteins (Bax, Bcl2 and C-caspase3), inflammatory proteins (iNOS and COX2), oxidative stress proteins (Nrf2 and HO-1) and NLRP3/apoptosis-associated speck-like protein containing a CARD (ASC)/caspase-1 inflammatory bodies. MiR-186-5p inhibitor could reduce the inflammatory factors and oxidative stress in BV2 treated with lipopolysaccharide, and reduce apoptosis. In addition, we also found that inhibition of miR-186-5p increased the expression of IGF-1, which is necessary for nervous system development. Luciferase activity assay confirmed that IGF-1 was the direct target gene of miR-186-5p. Inhibiting miR-186-5p, through upregulation IGF-1, attenuates the inflammatory factors, oxidative stress and by inhibiting NLRP3/ASC/caspase-1 signal pathway TBI in-vitro model.

Autophagy and Apoptosis in Acute Brain Injuries: From Mechanism to Treatment

Significance: Autophagy and apoptosis are two important cellular mechanisms behind brain injuries, which are severe clinical situations with increasing incidences worldwide. To search for more and better treatments for brain injuries, it is essential to deepen the understanding of autophagy, apoptosis, and their interactions in brain injuries. This article first analyzes how autophagy and apoptosis participate in the pathogenetic processes of brain injuries respectively and mutually, then summarizes some promising treatments targeting autophagy and apoptosis to show the potential clinical applications in personalized medicine and precision medicine in the future. Recent Advances: Most current studies suggest that apoptosis is detrimental to brain recovery. Several studies indicate that autophagy can cause unnecessary death of neurons after brain injuries, while others show that autophagy is beneficial for acute brain injuries (ABIs) by facilitating the removal of damaged proteins and organelles. Whether autophagy is beneficial or detrimental in ABIs depends on many factors, and the results from different research groups are diverse or even controversial, making this topic more appealing to be explored further. Critical Issues: Neuronal autophagy and apoptosis are two primary pathological processes in ABIs. How they interact with each other and how their regulations affect the outcome and prognosis of brain injuries remain uncertain, making these answers more critical. Future Directions: Insights into the interplay between autophagy and apoptosis and the accurate regulations of their balance in ABIs may promote personalized and precise treatments in the field of brain injuries. Antioxid. Redox Signal. 38, 234-257.

Low-intensity focused ultrasound attenuates early traumatic brain injury by OX-A/NF-κB/NLRP3 signaling pathway

Background: Traumatic brain injury (TBI) is a serious hazard to human health and is characterized by high rates of disability and mortality. It is necessary to explore new effective treatment methods to reduce the impact of TBI on individuals and society. As an emerging neuromodulation technique, ultrasound is used to treat some neurological diseases, but the neuroprotective mechanism of low-intensity focused ultrasound (LIFUS) in TBI remains unclear. We aimed to investigate the protective effects and potential mechanisms of LIFUS in TBI.

Methods: A rat model of TBI was established using the free-fall method. After establishing the TBI model, the hypothalamus region was covered with LIFUS radiation, and an orexin receptor 1 (OXR1) antagonist (SB334867) was injected intraperitoneally. Neurobehavioral examination, Nissl staining, hematoxylin and eosin staining of the brain tissue, and brain water content, were performed 3 days later. Western blotting, quantitative real-time polymerase chain reaction, immunofluorescence staining, and immunohistochemical staining, were used to evaluate the neuroprotective mechanisms of LIFUS.

Results: LIFUS improved tissue damage, neurological deficits, and brain edema. LIFUS can increase the expression of orexin-A (OX-A) and OXR1, significantly inhibit the activation of nuclear factor-κB (NF-κB) protein and nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome after TBI, and reduce the release of pro-inflammatory factors after TBI; however, SB334867 can reverse this effect.

Conclusions: This study suggests that LIFUS may play a neuroprotective role by promoting the release of OX-A from the hypothalamus and inhibiting the inflammatory response after TBI through the OX-A /NF-κB/NLRP3 pathway.

Spatial-temporal changes of iron deposition and iron metabolism after traumatic brain injury in mice

Excessive iron released by hemoglobin and necrotic tissues is the predominant factor that aggravates the outcome of traumatic brain injury (TBI). Regulating the levels of iron and its metabolism is a feasible way to alleviate damage due to TBI. However, the spatial-temporal iron metabolism and iron deposition in neurons and glial cells after TBI remains unclear. In our study, male C57BL/6 mice (8–12 weeks old, weighing 20–26 g) were conducted using controlled cortical impact (CCI) models, combined with treatment of iron chelator deferoxamine (DFO), followed by systematical evaluation on iron deposition, cell-specific expression of iron metabolic proteins and ferroptosis in ipsilateral cortex. Herein, ferroptosis manifest by iron overload and lipid peroxidation was noticed in ipsilateral cortex. Furthermore, iron deposition and cell-specific expression of iron metabolic proteins were observed in the ipsilateral cortical neurons at 1–3 days post-injury. However, iron overload was absent in astrocytes, even though they had intense TBI-induced oxidative stress. In addition, iron accumulation in oligodendrocytes was only observed at 7–14 days post-injury, which was in accordance with the corresponding interval of cellular repair. Microglia play significant roles in iron engulfment and metabolism after TBI, and excessive affects the transformation of M1 and M2 subtypes and activation of microglial cells. Our study revealed that TBI led to ferroptosis in ipsilateral cortex, iron deposition and metabolism exhibited cell-type-specific spatial-temporal changes in neurons and glial cells after TBI. The different effects and dynamic changes in iron deposition and iron metabolism in neurons and glial cells are conducive to providing new insights into the iron-metabolic mechanism and strategies for improving the treatment of TBI.

Role of autophagy and transcriptome regulation in acute brain injury

Autophagy is an evolutionarily conserved intracellular system that routes distinct cytoplasmic cargo to lysosomes for degradation and recycling. Accumulating evidence highlight the mechanisms of autophagy, such as clearance of proteins, carbohydrates, lipids and damaged organelles. The critical role of autophagy in selective degradation of the transcriptome is still emerging and could shape the total proteome of the cell, and thus can regulate the homeostasis under stressful conditions. Unregulated autophagy that potentiates secondary brain damage is a key pathological features of acute CNS injuries such as stroke and traumatic brain injury. This review discussed the mutual modulation of autophagy and RNA and its significance in mediating the functional consequences of acute CNS injuries.

Neurobiological Links between Stress, Brain Injury, and Disease

Stress, which refers to a combination of physiological, neuroendocrine, behavioral, and emotional responses to novel or threatening stimuli, is essentially a defensive adaptation under physiological conditions. However, strong and long-lasting stress can lead to psychological and pathological damage. Growing evidence suggests that patients suffering from mild and moderate brain injuries and diseases often show severe neurological dysfunction and experience severe and persistent stressful events or environmental stimuli, whether in the acute, subacute, or recovery stage. Previous studies have shown that stress has a remarkable influence on key brain regions and brain diseases. The mechanisms through which stress affects the brain are diverse, including activation of endoplasmic reticulum stress (ERS), apoptosis, oxidative stress, and excitatory/inhibitory neuron imbalance, and may lead to behavioral and cognitive deficits. The impact of stress on brain diseases is complex and involves impediment of recovery, aggravation of cognitive impairment, and neurodegeneration. This review summarizes various stress models and their applications and then discusses the effects and mechanisms of stress on key brain regions—including the hippocampus, hypothalamus, amygdala, and prefrontal cortex—and in brain injuries and diseases—including Alzheimer’s disease, stroke, traumatic brain injury, and epilepsy. Lastly, this review highlights psychological interventions and potential therapeutic targets for patients with brain injuries and diseases who experience severe and persistent stressful events.

PES derivative PESA is a potent tool to globally profile cellular targets of PES

PES (2-phenylethynesulfonamide, pifithrin-μ, PFTμ) is an electrophilic compound that exhibits anticancer properties, protects against chemotherapy-induced peripheral neuropathy in chemotherapy, and shows immunomodulatory, anti-inflammatory and anti-viral activities. PES generally shows higher cytotoxicity towards tumor cells than non-tumor cells. The mechanism of action of PES is unclear but may involve the covalent modification of proteins as PES has been found to be a covalent inhibitor of Hsp70. We developed a new PES derivative PESA with a terminal alkynyl group to perform click-reaction-assisted activity-based protein profiling (click-reaction ABPP) and used this to screen for cellular targets of PES. We found PES and its derivatives PES-Cl and PESA have comparable ability to undergo a Michael addition reaction with GSH and Hsp70, and showed similar cytotoxicity. By fluorescence imaging and proteomics studies we identified over 300 PESA-attached proteins in DOHH2 cells. Some proteins involved in cancer-related redox processes, such as peroxiredoxin 1 (PRDX1), showed higher frequency and abundance in mass spectrometry detection. Our results suggest that cytotoxicity of PES and its derivatives may be related to attack of protein thiols and cellular GSH resulting in breakdown of cellular redox homeostasis. This study provides a powerful new tool compound within the PES class of bioactive compounds and gives insight into the working mechanisms of PES and its derivatives.

Research Progress on the Inflammatory Effects of Long Non-coding RNA in Traumatic Brain Injury

Globally, traumatic brain injury (TBI) is an acute clinical event and an important cause of death and long-term disability. However, the underlying mechanism of the pathophysiological has not been fully elucidated and the lack of effective treatment a huge burden to individuals, families, and society. Several studies have shown that long non-coding RNAs (lncRNAs) might play a crucial role in TBI; they are abundant in the central nervous system (CNS) and participate in a variety of pathophysiological processes, including oxidative stress, inflammation, apoptosis, blood-brain barrier protection, angiogenesis, and neurogenesis. Some lncRNAs modulate multiple therapeutic targets after TBI, including inflammation, thus, these lncRNAs have tremendous therapeutic potential for TBI, as they are promising biomarkers for TBI diagnosis, treatment, and prognosis prediction. This review discusses the differential expression of different lncRNAs in brain tissue during TBI, which is likely related to the physiological and pathological processes involved in TBI. These findings may provide new targets for further scientific research on the molecular mechanisms of TBI and potential therapeutic interventions.

Mitophagy in Traumatic Brain Injury: A New Target for Therapeutic Intervention

Traumatic brain injury (TBI) contributes to death, and disability worldwide more than any other traumatic insult and damage to cellular components including mitochondria leads to the impairment of cellular functions and brain function. In neurons, mitophagy, autophagy-mediated degradation of damaged mitochondria, is a key process in cellular quality control including mitochondrial homeostasis and energy supply and plays a fundamental role in neuronal survival and health. Conversely, defective mitophagy leads to the accumulation of damaged mitochondria and cellular dysfunction, contributing to inflammation, oxidative stress, and neuronal cell death. Therefore, an extensive characterization of mitophagy-related protective mechanisms, taking into account the complex mechanisms by which each molecular player is connected to the others, may provide a rationale for the development of new therapeutic strategies in TBI patients. Here, we discuss the contribution of defective mitophagy in TBI, and the underlying molecular mechanisms of mitophagy in inflammation, oxidative stress, and neuronal cell death highlight novel therapeutics based on newly discovered mitophagy-inducing strategies.

Autophagy-Lysosomal Pathway as Potential Therapeutic Target in Parkinson's Disease

Cellular quality control systems have gained much attention in recent decades. Among these, autophagy is a natural self-preservation mechanism that continuously eliminates toxic cellular components and acts as an anti-ageing process. It is vital for cell survival and to preserve homeostasis. Several cell-type-dependent canonical or non-canonical autophagy pathways have been reported showing varying degrees of selectivity with regard to the substrates targeted. Here, we provide an updated review of the autophagy machinery and discuss the role of various forms of autophagy in neurodegenerative diseases, with a particular focus on Parkinson's disease. We describe recent findings that have led to the proposal of therapeutic strategies targeting autophagy to alter the course of Parkinson's disease progression.

3,6'-Dithiopomalidomide Ameliorates Hippocampal Neurodegeneration, Microgliosis and Astrogliosis and Improves Cognitive Behaviors in Rats with a Moderate Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of disability and mortality worldwide. It can instigate immediate cell death, followed by a time-dependent secondary injury that results from disproportionate microglial and astrocyte activation, excessive inflammation and oxidative stress in brain tissue, culminating in both short- and long-term cognitive dysfunction and behavioral deficits. Within the brain, the hippocampus is particularly vulnerable to a TBI. We studied a new pomalidomide (Pom) analog, namely, 3,6′-dithioPom (DP), and Pom as immunomodulatory imide drugs (IMiD) for mitigating TBI-induced hippocampal neurodegeneration, microgliosis, astrogliosis and behavioral impairments in a controlled cortical impact (CCI) model of TBI in rats. Both agents were administered as a single intravenous dose (0.5 mg/kg) at 5 h post injury so that the efficacies could be compared. Pom and DP significantly reduced the contusion volume evaluated at 24 h and 7 days post injury. Both agents ameliorated short-term memory deficits and anxiety behavior at 7 days after a TBI. The number of degenerating neurons in the CA1 and dentate gyrus (DG) regions of the hippocampus after a TBI was reduced by Pom and DP. DP, but not Pom, significantly attenuated the TBI-induced microgliosis and DP was more efficacious than Pom at attenuating the TBI-induced astrogliosis in CA1 and DG at 7D after a TBI. In summary, a single intravenous injection of Pom or DP, given 5 h post TBI, significantly reduced hippocampal neurodegeneration and prevented cognitive deficits with a concomitant attenuation of the neuroinflammation in the hippocampus.

Improving Drug Delivery for Alzheimer's Disease Through Nose-to-Brain Delivery Using Nanoemulsions, Nanostructured Lipid Carriers (NLC) and in situ Hydrogels

Current treatments for Alzheimer's disease (AD) attenuate the progression of symptoms and aim to improve the patient's quality of life. Licensed medicines are mostly for oral administration and are limited by the difficulty in crossing the blood-brain barrier (BBB). Here in, the nasal route has been explored as an alternative pathway that allows drugs to be directly delivered to the brain via the nasal cavity. However, clearance mechanisms in the nasal cavity impair the delivery of drugs to the brain and limit their bioavailability. To optimize nose-to-brain delivery, formulations of lipid-based nanosystems, namely nanoemulsions and nanostructured lipid carriers (NLC), formulated in situ gelling hydrogels have been proposed as approaches for nose-to-brain delivery. These formulations possess characteristics that facilitate drug transport directly to the brain, minimizing side effects and maximizing therapeutic benefits. It has been recommended that the manufacture of these drug delivery systems follows the quality by design (QbD) approach based on nasal administration requirements. This review provides an insight into the current knowledge of the AD, highlighting the need for an effective drug delivery to the brain. Considering the mounting interest in the use of nanoemulsions and NLC for nose-to-brain delivery, a description of drug transport pathways in the nasal cavity and the application of these nanosystems and their in situ hydrogels through the intranasal route are presented. Relevant preclinical studies are summarised, and the future prospects for the use of lipid-based nanosystems in the treatment of AD are emphasized.

P53 inhibitor pifithrin-α inhibits ropivacaine-induced neuronal apoptosis via the mitochondrial apoptosis pathway

The neurotoxicity of local anesthetics (LAs) has attracted more and more attention, However, they lack preventive and therapeutic measures. Many studies have shown that apoptosis plays an important role in the process of LA-induced neurotoxicity. As an important signaling molecule to activate apoptosis, p53 has been proved to be involved in the neurotoxicity induced by LAs, but the mechanism is unclear. In this study, we explored the effect of pifithrin-α (PFT-α), a p53 inhibitor, on apoptosis by ropivacaine (Rop) in vivo and in vitro. Cell viability and apoptosis detected by CCK-8 and a JC-1 apoptosis detection kit, the changes of spinal cord structure observed after hematoxylin and eosin staining, apoptosis of the spinal cord measured by terminal deoxynucleotidyl transferase dUTP nick end labeling staining, behavioral assessment of the nerve Injury evaluated by the detection of sciatic nerve conduction velocity (SNCV) andmechanical withdrawal threshold (MWT), the expression of p53 and many apoptosis-related genes included Bax, Bcl-2, and caspase-3 detected by quantitative real-time polymerase chain reaction, Western blot analysis, immunofluorescence, and immunohistochemistry. Results showed that PC12 cell viability decreased because of Rop, but the pretreatment of PFT-α could protect it. And PFT-α reduced the injuries in the spinal cord by Rop included vacuoles or edema. The results of immunofluorescence and immunohistochemistry testing showed that PFT-α inhibited the p53 protein upregulated by Rop. Apoptosis rate and many proapoptotic genes include p53, Bax, caspase-3 messenger RNA, and proteins were increased by Rop, but PFT-α could decrease it. In conclusion, PFT-α inhibited cell apoptosis and spinal cord injuries induced by Rop.

Xinmailong Attenuates Doxorubicin-Induced Lysosomal Dysfunction and Oxidative Stress in H9c2 Cells via HO-1

The clinical use of doxorubicin (DOX) is limited by its cardiotoxicity, which is closely associated with oxidative stress. Xinmailong (XML) is a bioactive peptide extracted from American cockroaches, which has been mainly applied to treat chronic heart failure in China. Our previous study showed that XML attenuates DOX-induced oxidative stress. However, the mechanism of XML in DOX-induced cardiotoxicity remains unclear. Heme oxygenase-1 (HO-1), an enzyme that is ubiquitously expressed in all cell types, has been found to take antioxidant effects in many cardiovascular diseases, and its expression is protectively upregulated under DOX treatment. Lysosome and autophagy are closely involved in oxidative stress as well. It is still unknown whether XML could attenuate doxorubicin-induced lysosomal dysfunction and oxidative stress in H9c2 cells via HO-1. Thus, this study was aimed at investigating the involvement of HO-1-mediated lysosomal function and autophagy flux in DOX-induced oxidative stress and cardiotoxicity in H9c2 cells. Our results showed that XML treatment markedly increased cell proliferation and SOD activity, improved lysosomal function, and ameliorated autophagy flux block in DOX-treated H9c2 cells. Furthermore, XML significantly increased HO-1 expression following DOX treatment. Importantly, HO-1-specific inhibitor (Znpp) or HO-1 siRNA could significantly attenuate the protective effects of XML against DOX-induced cell injury, oxidative stress, lysosomal dysfunction, and autophagy flux block. These results suggest that XML protects against DOX-induced cardiotoxicity through HO-1-mediated recovery of lysosomal function and autophagy flux and decreases oxidative stress, providing a novel mechanism responsible for the protection of XML against DOX-induced cardiomyopathy.

Epigenetic Blockade of Hippocampal SOD2 Via DNMT3b-Mediated DNA Methylation: Implications in Mild Traumatic Brain Injury-Induced Persistent Oxidative Damage

The recurrent events of mild trauma exacerbate the vulnerability for post-traumatic stress disorder; however, the underlying molecular mechanisms are scarcely known. The repeated mild traumatic brain injury (rMTBI) perturbs redox homeostasis which is primarily managed by superoxide dismutase 2 (SOD2). The current study investigates the role of DNA methylation in SOD2 gene regulation and its involvement in rMTBI-induced persistent neuropathology inflicted by weight drop injury paradigm. The oxidative damage, neurodegenerative indicators, and SOD2 function and its regulation in the hippocampus were analyzed after 48 h and 30 days of rMTBI. The temporal and episodic increase in ROS levels (oxidative stress) heightened 8-hydroxyguanosine levels indicating oxidative damage after rMTBI that was concomitant with decline in SOD2 function. In parallel, occupancy of DNMT3b at SOD2 promoter was higher post 30 days of the first episode of rMTBI causing hypermethylation at SOD2 promoter. This epigenetic silencing of SOD2 promoter was sustained after the second episode of rMTBI causing permanent blockade in SOD2 response. The resultant oxidative stress further culminated into the increasing number of degenerating neurons. The treatment with 5-azacytidine, a pan DNMT inhibitor, normalized DNA methylation levels and revived SOD2 function after the second episode of rMTBI. The release of blockade in SOD2 expression by DNMT inhibition also normalized the post-traumatic oxidative consequences and relieved the neurodegeneration and deficits in learning and memory as measured by novel object recognition test. In conclusion, DNMT3b-mediated DNA methylation plays a critical role in SOD2 gene regulation in the hippocampus, and the perturbations therein post rMTBI are detrimental to redox homeostasis manifesting into neurological consequences.

Upregulation of Sec22b plays a neuroprotective role in a rat model of traumatic brain injury via inducing protective autophagy

Cortical neuronal cell death following traumatic brain injury (TBI) evoked by the cortical impact is a significant factor that contributes to neurological deficits. In the current study, we harvested the injured area and perilesional area of the injured brain induced by TBI. We explored the functions of Sec22b, an apoptosis-promoting kinase, and a pivotal bridge builder of apoptotic signaling in the etiopathogenesis of an experimental rat model of TBI. We found that Sec22b was expressed in neurons in the injured cortical area, and the expression level significantly decreased after TBI, especially at 24 h. Administration of Sec22b overexpressed plasmid significantly ameliorated TBI-induced apoptosis, neurological deficits, and blood-brain barrier permeability, accompanied by the activation of autophagy. However, the administration of Sec22b knockdown resulted in the opposite eff ;ects. Altogether, these findings indicated that Sec22b plays a neuroprotective role after TBI, suggesting that Sec22b may be a potential therapeutic target for TBI. We speculated that this neuroprotective effect might be achieved by upregulating autophagy levels and required further studies to explore.

Raloxifene as Treatment for Various Types of Brain Injuries and Neurodegenerative Diseases: A Good Start

Recent studies have shown that the selective estrogen receptor modulator (SERM) raloxifene had pronounced protective effects against progressing brain damage after traumatic brain injury (TBI) in mice. These studies, indicating beneficial effects of raloxifene for brain health, prompted the study of the history and present state of knowledge of this topic. It appears that, apart from raloxifene, to date, four nonrelated compounds have shown comparable beneficial effects—fucoidan, pifithrin, SMM-189 (5-dihydroxy-phenyl]-phenyl-methanone), and translocator protein (TSPO) ligands. Raloxifene, however, is ahead of the field, as for more than two decades it has been used in medical practice for various chronic ailments in humans. Thus, apart from different types of animal and cell culture studies, it has also been assessed in various human clinical trials, including assaying its effects on mild cognitive impairments. Regarding cell types, raloxifene protects neurons from cell death, prevents glial activation, ameliorates myelin damage, and maintains health of endothelial cells. At whole central nervous system (CNS) levels, raloxifene ameliorated mild cognitive impairments, as seen in clinical trials, and showed beneficial effects in animal models of Parkinson’s disease. Moreover, with stroke and TBI in animal models, raloxifene showed curative effects. Furthermore, raloxifene showed healing effects regarding multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) in cell culture. The adverse biological signals typical of these conditions relate to neuronal activity, neurotransmitters and their receptors, plasticity, inflammation, oxidative stress, nitric oxide, calcium homeostasis, cell death, behavioral impairments, etc. Raloxifene favorably modulates these signals toward cell health—on the one hand, by modulating gene expression of the relevant proteins, for example by way of its binding to the cell nuclear estrogen receptors ERα and ERβ (genomic effects) and, on the other hand (nongenomic effects) by modulation of mitochondrial activity, reduction of oxidative stress and programmed cell death, maintaining metabolic balance, degradation of Abeta, and modulation of intracellular cholesterol levels. More specifically regarding Alzheimer’s disease, raloxifene may not cure diagnosed Alzheimer’s disease. However, the onset of Alzheimer’s disease may be delayed or arrested by raloxifene’s capability to attenuate mild cognitive impairment. Mild cognitive impairment is a condition that may precede diagnosis of Alzheimer’s disease. In this review, relatively new insights are addressed regarding the notion that Alzheimer’s disease can be caused by bacterial (as well as viral) infections, together with the most recent findings that raloxifene can counteract infections of at least some bacterial and viral strains. Thus, here, an overview of potential treatments of neurodegenerative disease by raloxifene is presented, and attention is paid to subcellular molecular biological pathways that may be involved.

Construction prognosis model based on autophagy-related gene signatures in hepatocellular carcinoma

Aim: To develop robust and accurate prognostic biomarkers to help clinicians optimize therapeutic strategies. Materials & methods: Differentially prognosis-related autophagy genes were identified by bioinformatics analysis method. Results: Seven prognosis-related autophagy genes were more significantly related to the prognosis of hepatocellular carcinoma (HCC). Functional enrichment analysis demonstrated that these genes were mainly enriched in the autophagy pathway. BIRC5, HSPB8 and TMEM74 exhibited significant prognostic value for HCC. Besides, the risk score and BIRC5 have significant significance with clinicopathological significance of HCC. Conclusion: The research has identified a number of prognosis-related autophagy genes that associated with the survival and clinical stage of HCC. In addition, the prognostic model can be used to calculate the patient's risk score and these prognosis-related autophagy genes might serve as therapeutic targets.

Vagus Nerve Stimulation Attenuates Early Traumatic Brain Injury by Regulating the NF-κB/NLRP3 Signaling Pathway

BACKGROUND

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Oxidative stress, inflammation, and apoptosis are vital pathophysiological features post-TBI.

OBJECTIVES

Research has shown that vagus nerve stimulation (VNS) can attenuate oxidative stress in various diseases. However, the critical role of VNS in TBI is still not completely understood. This study investigated the protective effects and potential mechanism of VNS on TBI.

METHODS

Male Sprague-Dawley rats were randomized into 3 groups: sham, TBI, and TBI + VNS. The TBI model was induced in rats by the free-fall drop method. The vagal nerve trunk was separated, and VNS was performed after establishing the TBI model.

RESULTS

The results showed that VNS significantly ameliorated tissue damage, neurological deficits, and cerebral edema, compared with the sham VNS group. Additionally, VNS alleviated oxidative stress, inflammation, and apoptosis in the pericontusive cortex of rats after TBI. VNS also significantly suppressed expression of the nuclear factor-κB (NF-κB) protein in the nucleus and activation of the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome.

CONCLUSIONS

Taken together, the present study indicates that VNS may attenuate brain damage after TBI by inhibiting oxidative stress, inflammation, and apoptosis, possibly through the NF-κB/NLRP3 signaling pathway.