Resolvin D1 ameliorates cognitive impairment following traumatic brain injury via protecting astrocytic mitochondria

Mitophagy in acute central nervous system injuries: regulatory mechanisms and therapeutic potentials

Acute central nervous system injuries, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury, are a major global health challenge. Identifying optimal therapies and improving the long-term neurological functions of patients with acute central nervous system injuries are urgent priorities. Mitochondria are susceptible to damage after acute central nervous system injury, and this leads to the release of toxic levels of reactive oxygen species, which induce cell death. Mitophagy, a selective form of autophagy, is crucial in eliminating redundant or damaged mitochondria during these events. Recent evidence has highlighted the significant role of mitophagy in acute central nervous system injuries. In this review, we provide a comprehensive overview of the process, classification, and related mechanisms of mitophagy. We also highlight the recent developments in research into the role of mitophagy in various acute central nervous system injuries and drug therapies that regulate mitophagy. In the final section of this review, we emphasize the potential for treating these disorders by focusing on mitophagy and suggest future research paths in this area.

Tufm lactylation regulates neuronal apoptosis by modulating mitophagy in traumatic brain injury

Lactates accumulation following traumatic brain injury (TBI) is detrimental. However, whether lactylation is triggered and involved in the deterioration of TBI remains unknown. Here, we first report that Tufm lactylation pathway induces neuronal apoptosis in TBI. Lactylation is found significantly increased in brain tissues from patients with TBI and mice with controlled cortical impact (CCI), and in neuronal injury cell models. Tufm, a key factor in mitophagy, is screened and identified to be mostly lactylated. Tufm is detected to be lactylated at K286 and the lactylation inhibits the interaction of Tufm and Tomm40 on mitochondria. The mitochondrial distribution of Tufm is then inhibited. Consequently, Tufm-mediated mitophagy is suppressed while mitochondria-induced neuronal apoptosis is increased. In contrast, the knockin of a lactylation-deficient TufmK286R mutant in mice rescues the mitochondrial distribution of Tufm and Tufm-mediated mitophagy, and improves functional outcome after CCI. Likewise, mild hypothermia, as a critical therapeutic method in neuroprotection, helps in downregulating Tufm lactylation, increasing Tufm-mediated mitophagy, mitigating neuronal apoptosis, and eventually ameliorating the outcome of TBI. A novel molecular mechanism in neuronal apoptosis, TBI-initiated Tufm lactylation suppressing mitophagy, is thus revealed.

Mitochondrial-targeted therapies in traumatic brain injury: From bench to bedside

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide, with limited effective therapeutic options currently available. Recent research has highlighted the pivotal role of mitochondrial dysfunction in the pathophysiology of TBI, making mitochondria an attractive target for therapeutic intervention. This review comprehensively examines advancements in mitochondrial-targeted therapies for TBI, bridging the gap from basic research to clinical applications. We discuss the underlying mechanisms of mitochondrial damage in TBI, including oxidative stress, impaired bioenergetics, mitochondrial dynamics, and apoptotic pathways. Furthermore, we highlight the complex interplay between mitochondrial dysfunction, inflammation, and blood-brain barrier (BBB) integrity, elucidating how these interactions exacerbate injury and impede recovery. We also evaluate various preclinical studies exploring pharmacological agents, gene therapy, and novel drug delivery systems designed to protect and restore mitochondrial function. Clinical trials and their outcomes are assessed to evaluate the translational potential of mitochondrial-targeted therapies in TBI. By integrating findings from bench to bedside, this review emphasizes promising therapeutic avenues and addresses remaining challenges. It also provides guidance for future research to pave the way for innovative treatments that improve patient outcomes in TBI.

Omega-3 Fatty Acids and Traumatic Injury in the Adult and Immature Brain

Background/Objectives: Traumatic brain injury (TBI) can lead to substantial disability and health loss. Despite its importance and impact worldwide, no treatment options are currently available to help protect or preserve brain structure and function following injury. In this review, we discuss the potential benefits of using omega-3 polyunsaturated fatty acids (O3 PUFAs) as therapeutic agents in the context of TBI in the paediatric and adult populations. Methods: Preclinical and clinical research reports investigating the effects of O3 PUFA-based interventions on the consequences of TBI were retrieved and reviewed, and the evidence presented and discussed. Results: A range of animal models of TBI, types of injury, and O3 PUFA dosing regimens and administration protocols have been used in different strategies to investigate the effects of O3 PUFAs in TBI. Most evidence comes from preclinical studies, with limited clinical data available thus far. Overall, research indicates that high O3 PUFA levels help lessen the harmful effects of TBI by reducing tissue damage and cell loss, decreasing associated neuroinflammation and the immune response, which in turn moderates the severity of the associated neurological dysfunction. Conclusions: Data from the studies reviewed here indicate that O3 PUFAs could substantially alleviate the impact of traumatic injuries in the central nervous system, protect structure and help restore function in both the immature and adult brains.

Regulation of adult neurogenesis: the crucial role of astrocytic mitochondria

Neurogenesis has emerged as a promising therapeutic approach for central nervous system disorders. The role of neuronal mitochondria in neurogenesis is well-studied, however, recent evidence underscores the critical role of astrocytic mitochondrial function in regulating neurogenesis and the underlying mechanisms remain incompletely understood. This review highlights the regulatory effects of astrocyte mitochondria on neurogenesis, focusing on metabolic support, calcium homeostasis, and the secretion of neurotrophic factors. The effect of astrocytic mitochondrial dysfunction in the pathophysiology and treatment strategies of Alzheimer's disease and depression is discussed. Greater attention is needed to investigate the mitochondrial autophagy, dynamics, biogenesis, and energy metabolism in neurogenesis. Targeting astrocyte mitochondria presents a potential therapeutic strategy for enhancing neural regeneration.

The evolving pathophysiology of TBI and the advantages of temporally-guided combination therapies

Several clinical and experimental studies have demonstrated that traumatic brain injury (TBI) activates cascades of biochemical, molecular, structural, and pathological changes in the brain. These changes combine to contribute to the various outcomes observed after TBI. Given the breadth and complexity of changes, combination treatments may be an effective approach for targeting multiple detrimental pathways to yield meaningful improvements. In order to identify targets for therapy development, the temporally evolving pathophysiology of TBI needs to be elucidated in detail at both the cellular and molecular levels, as it has been shown that the mechanisms contributing to cognitive dysfunction change over time. Thus, a combination of individual mechanism-based therapies is likely to be effective when maintained based on the time courses of the cellular and molecular changes being targeted. In this review, we will discuss the temporal changes of some of the key clinical pathologies of human TBI, the underlying cellular and molecular mechanisms, and the results from preclinical and clinical studies aimed at mitigating their consequences. As most of the pathological events that occur after TBI are likely to have subsided in the chronic stage of the disease, combination treatments aimed at attenuating chronic conditions such as cognitive dysfunction may not require the initiation of individual treatments at a specific time. We propose that a combination of acute, subacute, and chronic interventions may be necessary to maximally improve health-related quality of life (HRQoL) for persons who have sustained a TBI.

Mitophagy-associated programmed neuronal death and neuroinflammation

Mitochondria are crucial organelles that play a central role in cellular metabolism and programmed cell death in eukaryotic cells. Mitochondrial autophagy (mitophagy) is a selective process where damaged mitochondria are encapsulated and degraded through autophagic mechanisms, ensuring the maintenance of both mitochondrial and cellular homeostasis. Excessive programmed cell death in neurons can result in functional impairments following cerebral ischemia and trauma, as well as in chronic neurodegenerative diseases, leading to irreversible declines in motor and cognitive functions. Neuroinflammation, an inflammatory response of the central nervous system to factors disrupting homeostasis, is a common feature across various neurological events, including ischemic, infectious, traumatic, and neurodegenerative conditions. Emerging research suggests that regulating autophagy may offer a promising therapeutic avenue for treating certain neurological diseases. Furthermore, existing literature indicates that various small molecule autophagy regulators have been tested in animal models and are linked to neurological disease outcomes. This review explores the role of mitophagy in programmed neuronal death and its connection to neuroinflammation.

The bioenergetics of traumatic brain injury and its long-term impact for brain plasticity and function

Mitochondria provide the energy to keep cells alive and functioning and they have the capacity to influence highly complex molecular events. Mitochondria are essential to maintain cellular energy homeostasis that determines the course of neurological disorders, including traumatic brain injury (TBI). Various aspects of mitochondria metabolism such as autophagy can have long-term consequences for brain function and plasticity. In turn, mitochondria bioenergetics can impinge on molecular events associated with epigenetic modifications of DNA, which can extend cellular memory for a long time. Mitochondrial dysfunction leads to pathological manifestations such as oxidative stress, inflammation, and calcium imbalance that threaten brain plasticity and function. Hence, targeting mitochondrial function may have great potential to lessen the outcomes of TBI.

Tetramerization of PKM2 Alleviates Traumatic Brain Injury by Ameliorating Mitochondrial Damage in Microglia

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Microglial activation and neuroinflammation are key cellular events that determine the outcome of TBI, especially neuronal and cognitive function. Studies have suggested that the metabolic characteristics of microglia dictate their inflammatory response. The pyruvate kinase isoform M2 (PKM2), a key glycolytic enzyme, is involved in the regulation of various cellular metabolic processes, including mitochondrial metabolism. This suggests that PKM2 may also participate in the regulation of microglial activation during TBI. Therefore, the present study aimed to evaluate the role of PKM2 in regulating microglial activation and neuroinflammation and its effects on cognitive function following TBI. A controlled cortical impact (CCI) mouse model and inflammation-induced primary mouse microglial cells in vitro were used to investigate the potential effects of PKM2 inhibition and regulation. PKM2 was significantly increased during the acute and subacute phases of TBI and was predominantly detected in microglia rather than in neurons. Our results demonstrate that shikonin and TEPP-46 can inhibit microglial inflammation, improving mitochondria, improving mouse behavior, reducing brain defect volume, and alleviating pathological changes after TBI. There is a difference in the intervention of shikonin and TEPP-46 on PKM2. Shikonin directly inhibits General PKM2; TEPP-46 can promote the expression of PKM2 tetramer. In vitro experiments, TEPP-46 can promote the expression of PKM2 tetramer, enhance the interaction between PKM2 and MFN2, improve mitochondria, alleviate neuroinflammation. General inhibition and tetramerization activation of PKM2 attenuated cognitive function caused by TBI, whereas PKM2 tetramerization exhibited a better treatment effect. Our experiments demonstrated the non-metabolic role of PKM2 in the regulation of microglial activation following TBI. Both shikonin and TEPP-46 can inhibit pro-inflammatory factors, but only TEPP-46 can promote PKM2 tetramerization and upregulate the release of anti-inflammatory factors from microglia.

Eicosanoid signaling in neuroinflammation associated with Alzheimer's disease

Alzheimer's disease (AD) is a prevalent neurodegenerative condition affecting a substantial portion of the global population. It is marked by a complex interplay of factors, including the accumulation of amyloid plaques and tau tangles within the brain, leading to neuroinflammation and neuronal damage. Recent studies have underscored the role of free lipids and their derivatives in the initiation and progression of AD. Eicosanoids, metabolites of polyunsaturated fatty acids like arachidonic acid (AA), emerge as key players in this scenario. Remarkably, eicosanoids can either promote or inhibit the development of AD, and this multifaceted role is determined by how eicosanoid signaling influences the immune responses within the brain. However, the precise molecular mechanisms dictating the dual role of eicosanoids in AD remain elusive. In this comprehensive review, we explore the intricate involvement of eicosanoids in neuronal function and dysfunction. Furthermore, we assess the therapeutic potential of targeting eicosanoid signaling pathways as a viable strategy for mitigating or halting the progression of AD.

Synergism Between Hypothalamic Astrocytes and Neurons in Metabolic Control

Astrocytes are no longer considered as passive support cells. In the hypothalamus, these glial cells actively participate in the control of appetite, energy expenditure, and the processes leading to obesity and its secondary complications. Here we briefly review studies supporting this conclusion and the advances made in understanding the underlying mechanisms.

Astrocytes in ischemic stroke: Crosstalk in central nervous system and therapeutic potential

In the central nervous system (CNS), a large group of glial cells called astrocytes play important roles in both physiological and disease conditions. Astrocytes participate in the formation of neurovascular units and interact closely with other cells of the CNS, such as microglia and neurons. Stroke is a global disease with high mortality and disability rate, most of which are ischemic stroke. Significant strides in understanding astrocytes have been made over the past few decades. Astrocytes respond strongly to ischemic stroke through a process known as activation or reactivity. Given the important role played by reactive astrocytes (RAs) in different spatial and temporal aspects of ischemic stroke, there is a growing interest in the potential therapeutic role of astrocytes. Currently, interventions targeting astrocytes, such as mediating astrocyte polarization, reducing edema, regulating glial scar formation, and reprogramming astrocytes, have been proven in modulating the progression of ischemic stroke. The aforementioned potential interventions on astrocytes and the crosstalk between astrocytes and other cells of the CNS will be summarized in this review.

Activation of mitophagy improves cognitive dysfunction in diabetic mice with recurrent non-severe hypoglycemia

Recurrent non-severe hypoglycemia (RH) in patients with diabetes might be associated with cognitive impairment. Previously, we found that mitochondrial dysfunction plays an important role in this pathological process; however, the mechanism remains unclear. The objective of this study was to determine the molecular mechanisms of mitochondrial damage associated with RH in diabetes mellitus (DM). We found that RH is associated with reduced hippocampal mitophagy in diabetic mice, mainly manifested by reduced autophagosome formation and impaired recognition of impaired mitochondria, mediated by the PINK1/Parkin pathway. The same impaired mitophagy initiation was observed in an in vitro high-glucose cultured astrocyte model with recurrent low-glucose interventions. Promoting autophagosome formation and activating PINK1/Parkin-mediated mitophagy protected mitochondrial function and cognitive function in mice. The results showed that impaired mitophagy is involved in the occurrence of mitochondrial dysfunction, mediating the neurological impairment associated with recurrent low glucose under high glucose conditions.

Serum resolvin D1 potentially predicts neurofunctional recovery, the risk of recurrence and death in patients with acute ischemic stroke

Resolvin D1 (RvD1) represses inflammation, oxidative damage and neural injury related to acute ischemic stroke (AIS) progression. The present study aimed to explore the association of serum RvD1 with disease features, neurological recovery and prognosis in patients with AIS. A total of 212 patients with newly diagnosed AIS, whose serum RvD1 was quantified at admission and at discharge using an ELISA were enrolled in the current study. The modified Rankin scale (mRS) score was noted at 3 months after patient enrolment (M3), and patients were followed up for a median duration of 11.4 (range, 1.1-21.0) months. The median RvD1 in patients with AIS at admission was 1.07 (range, 0.11-9.29) ng/ml and it was negatively correlated with the neutrophil/lymphocyte ratio (r=-0.160; P=0.009) and C-reactive protein level (r=-0.272; P<0.001), but it was not correlated with comorbidities or other biochemical indexes. RvD1 at admission was lower in patients with mRS >2 at M3 (P=0.001), recurrence (P=0.001) or death (P=0.032) compared with that in patients without the aforementioned characteristics, which had a general ability to estimate mRS >2 at M3 [area under curve (AUC), 0.633], as well as lower risk of recurrence (AUC, 0.745) and death (AUC, 0.757) according to receiver operator characteristic (ROC) curve analyses. The median RvD1 was raised to 1.70 (range, 0.30-16.62) ng/ml at discharge. RvD1 at discharge was able to forecast mRS >2 at M3 (AUC, 0.678) and was able to predict the risk of recurrence (AUC, 0.796) and death (AUC, 0.826) in the ROC curve analyses. Increased serum RvD1 was associated with an attenuated inflammation status, and predicted improved neurological recovery, and lower risk of recurrence and death in patients with AIS. More specifically, its level at discharge exhibits a better prognostic utility than that at admission.

Neuropharmacological insight into preventive intervention in posttraumatic epilepsy based on regulating glutamate homeostasis

BACKGROUND

Posttraumatic epilepsy (PTE) is one of the most critical complications of traumatic brain injury (TBI), significantly increasing TBI patients' neuropsychiatric symptoms and mortality. The abnormal accumulation of glutamate caused by TBI and its secondary excitotoxicity are essential reasons for neural network reorganization and functional neural plasticity changes, contributing to the occurrence and development of PTE. Restoring glutamate balance in the early stage of TBI is expected to play a neuroprotective role and reduce the risk of PTE.

AIMS

To provide a neuropharmacological insight for drug development to prevent PTE based on regulating glutamate homeostasis.

METHODS

We discussed how TBI affects glutamate homeostasis and its relationship with PTE. Furthermore, we also summarized the research progress of molecular pathways for regulating glutamate homeostasis after TBI and pharmacological studies aim to prevent PTE by restoring glutamate balance.

RESULTS

TBI can lead to the accumulation of glutamate in the brain, which increases the risk of PTE. Targeting the molecular pathways affecting glutamate homeostasis helps restore normal glutamate levels and is neuroprotective.

DISCUSSION

Taking glutamate homeostasis regulation as a means for new drug development can avoid the side effects caused by direct inhibition of glutamate receptors, expecting to alleviate the diseases related to abnormal glutamate levels in the brain, such as PTE, Parkinson's disease, depression, and cognitive impairment.

CONCLUSION

It is a promising strategy to regulate glutamate homeostasis through pharmacological methods after TBI, thereby decreasing nerve injury and preventing PTE.

Declined Serum Resolvin D1 Levels to Predict Severity and Prognosis of Human Aneurysmal Subarachnoid Hemorrhage: A Prospective Cohort Study

Background

Resolvin D1 (RvD1) possesses anti-inflammatory properties and may be neuroprotective. This study was designed to ascertain the potential role of serum RvD1 in the evaluation of aSAH severity and prognosis of human aneurysmal subarachnoid hemorrhage (aSAH).

Methods

In this prospective observational study, serum RvD1 levels were measured in 123 patients with aSAH and in 123 healthy volunteers. Six-month neurological function was assessed using extended Glasgow outcome scale (GOSE). A prognostic prediction model was appraised using a series of evaluative tools, such as a nomogram, receiver operating characteristic (ROC) curve, decision curve, calibration curve, restricted cubic spline, and Hosmer-Lemeshow goodness of fit statistics.

Results

Serum RvD1 levels were markedly lower in patients than in controls (median, 0.54 versus 1.47 ng/mL; P<0.001). Serum RvD1 levels were independently correlated with Hunt-Hess scores (beta, -0.154; 95% confidence interval [CI], -0.198--0.109; VIF, 1.769; P=0.001), modified Fisher scores (beta, -0.066; 95% CI, -0.125--0.006; VIF, 1.567; P=0.031) and 6-month GOSE scores (beta, 1.864; 95% CI, 0.759-2.970; VIF, 1.911; P=0.001) and were independently predictive of a poor prognosis (GOSE scores of 1-4) (odds ratio, 0.137; 95% CI, 0.023-0.817; P=0.029). Serum RvD1 levels significantly distinguished the risk of a worse prognosis, with an area under the ROC curve of 0.750 (95% CI, 0.664-0.824). Using the Youden method, serum RvD1 levels < 0.6 ng/mL was effective in predicting worse prognosis with 84.1% sensitivity and 62.0% specificity. Moreover, the model containing serum RvD1 levels, Hunt-Hess scores and modified Fisher scores was efficient, reliable and beneficial in prognostic prediction using a series of the afore-mentioned evaluative tools.

Conclusion

A decline in serum RvD1 levels following aSAH is closely correlated with illness severity and independently predicts a worse outcome in patients with aSAH, implying that serum RvD1, as a prognostic biomarker of aSAH, may be of clinical value in aSAH.

Prognostic significance of serum resolvin D1 levels in patients with acute supratentorial intracerebral hemorrhage: a prospective longitudinal cohort study

OBJECTIVE

Resolvin D1 (RvD1) has anti-inflammatory properties and may be neuroprotective. This study was designed to assess usability of serum RvD1 as a prognostic biomarker after intracerebral hemorrhage (ICH).

METHODS

In this prospective, observational study of 135 patients and 135 controls, serum RvD1 levels were measured. Its relations to severity, early neurologic deterioration (END) and poststroke 6-month worse outcome (modified Rankin Scale scores of 3-6) were determined via multivariate analysis. Predictive effectiveness was evaluated based on area under receiver operating characteristic curve (AUC).

RESULTS

Patients had markedly lower serum RvD1 levels than controls (median, 0.69 ng/ml versus 2.15 ng/ml). Serum RvD1 levels were independently correlated with the National Institutes of Health Stroke Scale (NIHSS) [β, -0.036; 95% confidence interval (CI), -0.060--0.013; VIF, 2.633; t=-3.025; P=0.003] and hematoma volume (β, -0.019; 95% CI, -0.056--0.009; VIF, 1.688; t=-2.703; P=0.008). Serum RvD1 levels substantially discriminated risks of END and worse outcome with AUCs at 0.762 (95% CI, 0.681-0.831) and 0.783 (95% CI, 0.704-0.850) respectively. A RvD1 cut-off value of 0.85 ng/ml was effective in predicting END with a sensitivity of 95.0% and specificity of 48.4% and its levels <0.77 ng/ml distinguished patients at risk of worse outcome with a sensitivity of 84.5% and specificity of 63.6%. Under restricted cubic spline, serum RvD1 levels were linearly related to risk of END and worse outcome (both P>0.05). Serum RvD1 levels and NIHSS scores independently predicted END with odds ratio (OR) values of 0.082 (95% CI, 0.010-0.687) and 1.280 (95% CI, 1.084-1.513) respectively. Serum RvD1 levels (OR, 0.075; 95% CI, 0.011-0.521), hematoma volume (OR, 1.084; 95% CI, 1.035-1.135) and NIHSS scores (OR, 1.240; 95% CI, 1.060-1.452) were independently associated with worse outcome. END prediction model containing serum RvD1 levels and NIHSS scores, and prognostic prediction model containing serum RvD1 levels, hematoma volumes and NIHSS scores displayed efficient predictive ability with AUCs at 0.828 (95% CI, 0.754-0.888) and 0.873 (95% CI, 0.805-0.924) respectively. Such two models were visually shown via building two nomograms. Using Hosmer-Lemeshow test, calibration curve and decision curve, the models were comparatively stable and had clinical benefit.

CONCLUSION

There is a dramatical declination of serum RvD1 levels after ICH, which is tightly related to stroke severity and is independently predictive of poor clinical outcome, implying that serum RvD1 may be of clinical significance as a prognostic marker of ICH.

Essential lipid autacoids rewire mitochondrial energy efficiency in metabolic dysfunction-associated fatty liver disease

BACKGROUND AND AIM

Injury to hepatocyte mitochondria is common in metabolic dysfunction-associated fatty liver disease. Here, we investigated whether changes in the content of essential fatty acid-derived lipid autacoids affect hepatocyte mitochondrial bioenergetics and metabolic efficiency.

APPROACH AND RESULTS

The study was performed in transgenic mice for the fat-1 gene, which allows the endogenous replacement of the membrane omega-6-polyunsaturated fatty acid (PUFA) composition by omega-3-PUFA. Transmission electron microscopy revealed that hepatocyte mitochondria of fat-1 mice had more abundant intact cristae and higher mitochondrial aspect ratio. Fat-1 mice had increased expression of oxidative phosphorylation complexes I and II and translocases of both inner (translocase of inner mitochondrial membrane 44) and outer (translocase of the outer membrane 20) mitochondrial membranes. Fat-1 mice also showed increased mitofusin-2 and reduced dynamin-like protein 1 phosphorylation, which mediate mitochondrial fusion and fission, respectively. Mitochondria of fat-1 mice exhibited enhanced oxygen consumption rate, fatty acid β-oxidation, and energy substrate utilization as determined by high-resolution respirometry, [1- 14 C]-oleate oxidation and nicotinamide adenine dinucleotide hydride/dihydroflavine-adenine dinucleotide production, respectively. Untargeted lipidomics identified a rich hepatic omega-3-PUFA composition and a specific docosahexaenoic acid (DHA)-enriched lipid fingerprint in fat-1 mice. Targeted lipidomics uncovered a higher content of DHA-derived lipid autacoids, namely resolvin D1 and maresin 1, which rescued hepatocytes from TNFα-induced mitochondrial dysfunction, and unblocked the tricarboxylic acid cycle flux and metabolic utilization of long-chain acyl-carnitines, amino acids, and carbohydrates. Importantly, fat-1 mice were protected against mitochondrial injury induced by obesogenic and fibrogenic insults.

CONCLUSION

Our data uncover the importance of a lipid membrane composition rich in DHA and its lipid autacoid derivatives to have optimal hepatic mitochondrial and metabolic efficiency.

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.

Resolvins Lipid Mediators: Potential Therapeutic Targets in Alzheimer and Parkinson Disease

Inflammation and resolution are highly programmed processes involving a plethora of immune cells. Lipid mediators synthesized from arachidonic acid metabolism play a pivotal role in orchestrating the signaling cascades in the game of inflammation. The majority of the studies carried out so far on inflammation were aimed at inhibiting the generation of inflammatory molecules, whereas recent research has shifted more towards understanding the resolution of inflammation. Owing to chronic inflammation as evident in neuropathophysiology, the resolution of inflammation together with the class of lipid mediators actively involved in its regulation has attracted the attention of the scientific community as therapeutic targets. Both omega-three polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid, orchestrate a vital regulatory role in inflammation development. Resolvins derived from these fatty acids comprise the D-and E-series resolvins. A growing body of evidence using in vitro and in vivo models has revealed the pro-resolving and anti-inflammatory potential of resolvins. This systematic review sheds light on the synthesis, specialized receptors, and resolution of inflammation mediated by resolvins in Alzheimer's and Parkinson's disease.

Roles of Resolvins in Chronic Inflammatory Response

An inflammatory response is beneficial to the organism, while an excessive uncontrolled inflammatory response can lead to the nonspecific killing of tissue cells. Therefore, promoting the resolution of inflammation is an important mechanism for protecting an organism suffering from chronic inflammatory diseases. Resolvins are a series of endogenous lipid mediums and have the functions of inhibiting a leukocyte infiltration, increasing macrophagocyte phagocytosis, regulating cytokines, and alleviating inflammatory pain. By promoting the inflammation resolution, resolvins play an irreplaceable role throughout the pathological process of some joint inflammation, neuroinflammation, vascular inflammation, and tissue inflammation. Although a large number of experiments have been conducted to study different subtypes of resolvins in different directions, the differences in the action targets between the different subtypes are rarely compared. Hence, this paper reviews the generation of resolvins, the characteristics of resolvins, and the actions of resolvins under a chronic inflammatory response and clinical translation of resolvins for the treatment of chronic inflammatory diseases.

SIRT3 alleviates mitochondrial dysfunction induced by recurrent low glucose and improves the supportive function of astrocytes to neurons

Hypoglycemia is an independent risk factor of cognitive impairment in patients with diabetes. Our previous study indicated that dysfunction of astrocytic mitochondria induced by recurrent low glucose (RLG) may account for hypoglycemia-associated neuronal injury and cognitive decline. Sirtuin 3 (SIRT3) is a key deacetylase for mitochondrial proteins and has recently been demonstrated to be an important regulator of mitochondrial function. However, whether mitochondrial dysfunction due to hypoglycemia is associated with astrocytic SIRT3 remains unclear, and few studies have focused on the impact of astrocytic SIRT3 on neuronal survival. In the present work, primary mouse cortical astrocytes cultured in normal glucose (5.5 mM) and high glucose (16.5 mM) were treated with five rounds of RLG (0.1 mM). The results showed that RLG suppressed SIRT3 expression in a glucose-dependent manner. High-glucose culture considerably increased the vulnerability of SIRT3 to RLG, leading to disrupted mitochondrial morphology in astrocytes. Overexpression of SIRT3 markedly improved astrocytic mitochondrial function and reduced RLG-induced oxidative stress. Moreover, SIRT3 suppressed a shift towards a neuroinflammatory A1-like reactive phenotype of astrocytes in response to RLG with reduced IL-1β, IL-6, and TNFα levels. Furthermore, it elevated brain-derived neurotrophic factor (BDNF) levels and promoted neurite growth by activating BDNF/TrkB signaling in the co-cultured neurons. The present study reveals the probable crosstalk between neurons and astrocytes after hypoglycemic exposure and provides a potential target in treating hypoglycemia-associated neuronal injury.

Downregulated formyl peptide receptor 2 expression in the epileptogenic foci of patients with focal cortical dysplasia type IIb and tuberous sclerosis complex

BACKGROUND

Focal cortical dysplasia type IIb (FCDIIb) and tuberous sclerosis complex (TSC) show persistent neuroinflammation, which promotes epileptogenesis and epilepsy progression, suggesting that endogenous resolution of inflammation is inadequate to relieve neuronal network hyperexcitability. To explore the potential roles of formyl peptide receptor 2 (FPR2), which is a key regulator of inflammation resolution, in epilepsy caused by FCDIIb and TSC, we examined the expression and cellular distribution of FPR2.

METHOD

The expression of FPR2 and nuclear factor-κB (NF-κB) signaling pathway was examined by real-time PCR, western blots, and analyzed via one-way analysis of variance. The distribution of FPR2 was detected using immunostaining. The expression of resolvin D1 (RvD1, the endogenous ligand of FPR2) was observed via enzyme-linked immunosorbent assay. Pearson's correlation test was used to evaluate the correlation between the expression levels of FPR2 and RvD1 and the clinical variants.

RESULTS

The expression of FPR2 was significantly lower in FCDIIb (p = .0146) and TSC (p = .0006) cortical lesions than in controls, as was the expression of RvD1 (FCDIIb: p = .00431; TSC: p = .0439). Weak FPR2 immunoreactivity was observed in dysmorphic neurons (DNs), balloon cells (BCs), and giant cells (GCs) in FCDIIb and TSC tissues. Moreover, FPR2 was mainly distributed in dysplastic neurons; it was sparse in microglia and nearly absent in astrocytes. The NF-κB pathway was significantly activated in patients with FCDIIb and TSC, and the protein level of NF-κB was negatively correlated with the protein level of FPR2 (FCDIIb: p = .00395; TSC: p = .0399). In addition, the protein level of FPR2 was negatively correlated with seizure frequency in FCDIIb (p = .0434) and TSC (p = .0351) patients.

CONCLUSION

In summary, these results showed that the expression and specific distribution of FPR2 may be involved in epilepsy caused by FCDIIb and TSC, indicating that downregulation of FPR2 mediated the dysfunction of neuroinflammation resolution in FCDIIb and TSC.

Resolvin D1: A key endogenous inhibitor of neuroinflammation

After the initiation of inflammation, a series of processes start to resolve the inflammation. A group of endogenous lipid mediators, namely specialized pro-resolving lipid mediators is at the top list of inflammation resolution. Resolvin D1 (RvD1), is one of the lipid mediators with significant anti-inflammatory properties. It is produced from docosahexaenoic acid (omega-3 polyunsaturated fatty acid) in the body. In this article, we aimed to review the most recent findings concerning the pharmacological effects of RvD1 in the central nervous system with a focus on major neurological diseases and dysfunctions. A literature review of the past studies demonstrated that RvD1 plasma level changes during mania, depression, and Parkinson's disease. Furthermore, RVD1 and its epimer, aspirin-triggered RvD1 (AT-RvD1), have significant therapeutic effects on experimental models of ischemic and traumatic brain injuries, memory dysfunction, pain, depression, amyotrophic lateral sclerosis, and Alzheimer's and Parkinson's diseases. Interestingly, the beneficial effects of RvD1 and AT-RvD1 were mostly induced at nanomolar and micromolar concentrations implying the significant potency of these lipid mediators in treating diseases with inflammation.

Preventive Effect of Hippocampal Sparing on Cognitive Dysfunction of Patients Undergoing Whole-Brain Radiotherapy and Imaging Assessment of Hippocampal Volume Changes

Objective

Preventive effect of hippocampal sparing on cognitive dysfunction of patients undergoing whole-brain radiotherapy and imaging assessment of hippocampal volume changes.

Methods

Forty patients with brain metastases who attended Liaoning Cancer Hospital from January 2018 to December 2019 were identified as research subjects and were randomly divided into a control group and an experimental group, with 20 cases in each group. The control group was treated with whole-brain radiotherapy (WBRT), and the experimental group was treated with hippocampal sparing-WBRT (HS-WBRT). The Montreal Cognitive Assessment (MoCA) score, Eastern Cooperative Oncology Group (ECOG) score, cancer quality-of-life questionnaire (QLQ-C3O) score, hippocampal volume changes, and prognosis of the two groups were compared.

Results

The MoCA scores decreased in both groups at 3, 6, and 12 months after radiotherapy, with significantly higher scores in the experimental group than in the control group (P < 0.05). After radiotherapy, both groups had lower ECOG scores, with those in the experimental group being significantly lower than those in the control group (P < 0.05). After radiotherapy, the QLQ-C30 score was elevated in both groups, and that of the experimental group was significantly higher than that of the control group (P < 0.05). The experimental group outperformed the control group in terms of the prognosis (P < 0.05). The hippocampal volume of the control group was significantly smaller than that of the experimental group (P < 0.05).

Conclusion

The application of hippocampal sparing in patients receiving whole-brain radiotherapy is effective in preventing cognitive dysfunction, improving the quality of life and prognosis of patients, and avoiding shrinkage of hippocampal volume.

Intranasal delivery of pro-resolving lipid mediators rescues memory and gamma oscillation impairment in AppNL-G-F/NL-G-F mice

Sustained microglial activation and increased pro-inflammatory signalling cause chronic inflammation and neuronal damage in Alzheimer’s disease (AD). Resolution of inflammation follows neutralization of pathogens and is a response to limit damage and promote healing, mediated by pro-resolving lipid mediators (LMs). Since resolution is impaired in AD brains, we decided to test if intranasal administration of pro-resolving LMs in the App^{NL-G-F/NL-G-F} mouse model for AD could resolve inflammation and ameliorate pathology in the brain. A mixture of the pro-resolving LMs resolvin (Rv) E1, RvD1, RvD2, maresin 1 (MaR1) and neuroprotectin D1 (NPD1) was administered to stimulate their respective receptors. We examined amyloid load, cognition, neuronal network oscillations, glial activation and inflammatory factors. The treatment ameliorated memory deficits accompanied by a restoration of gamma oscillation deficits, together with a dramatic decrease in microglial activation. These findings open potential avenues for therapeutic exploration of pro-resolving LMs in AD, using a non-invasive route.

Intranasal administration of pro-resolving lipid mediators improves memory deficits and reduce microglial activation in a mouse model for Alzheimer’s disease, suggesting a future therapy.

NF-κB Signaling and Inflammation-Drug Repurposing to Treat Inflammatory Disorders?

NF-κB is a central mediator of inflammation, response to DNA damage and oxidative stress. As a result of its central role in so many important cellular processes, NF-κB dysregulation has been implicated in the pathology of important human diseases. NF-κB activation causes inappropriate inflammatory responses in diseases including rheumatoid arthritis (RA) and multiple sclerosis (MS). Thus, modulation of NF-κB signaling is being widely investigated as an approach to treat chronic inflammatory diseases, autoimmunity and cancer. The emergence of COVID-19 in late 2019, the subsequent pandemic and the huge clinical burden of patients with life-threatening SARS-CoV-2 pneumonia led to a massive scramble to repurpose existing medicines to treat lung inflammation in a wide range of healthcare systems. These efforts continue and have proven to be controversial. Drug repurposing strategies are a promising alternative to de novo drug development, as they minimize drug development timelines and reduce the risk of failure due to unexpected side effects. Different experimental approaches have been applied to identify existing medicines which inhibit NF-κB that could be repurposed as anti-inflammatory drugs.

Oridonin ameliorates traumatic brain injury-induced neurological damage by improving mitochondrial function and antioxidant capacity and suppressing neuroinflammation through the Nrf2 pathway

Traumatic brain injury (TBI) is a global public health concern, and few effective treatments for its delayed damages are available. Oridonin (Ori) has been recently reported to show a promising neuroprotective efficacy, but its potential therapeutic effect on TBI has not been thoroughly elucidated. TBI mouse models were established and treated with Ori or vehicle 30 minutes post-operation and every 24 hours since then. Impairments in cognitive and motor function and neuropathological changes were evaluated and compared. The therapeutic efficacy and mechanisms of action of Ori were further investigated using animal tissues and cell cultures. Ori restored motor function and cognition following TBI-induced impairment and exerted neuroprotective effects by reducing cerebral edema and cortical lesion volume. Ori increased neuronal survival, ameliorating gliosis and the accumulation of macrophages after injury. It suppressed the increased production of reactive oxygen species, lipid peroxide, and malondialdehyde; and reversed the decrease of mitochondrial membrane potential and adenosine triphosphate content, which was also identified in oxidatively stressed neuronal cultures. Furthermore, Ori inhibited the expression of NLRP3 inflammasome proteins and NLRP3-dependent cytokine IL-1β that can be induced by oxidative stress following TBI. Regarding underlying mechanisms, Ori significantly enhanced expression of key proteins of the Nrf2/HO-1 pathway. Our results demonstrated that Ori effectively improved functional impairments and neuropathological changes in TBI animals. By activating the Nrf2 pathway, it improved mitochondrial function and antioxidant capacity, and suppressed the neuroinflammation induced by oxidative stress. The results therefore suggest Ori as a potent candidate for treating neurological damage after TBI.

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.

Reactive Astrocytes in Central Nervous System Injury: Subgroup and Potential Therapy

Traumatic central nervous system (CNS) injury, which includes both traumatic brain injury (TBI) and spinal cord injury (SCI), is associated with irreversible loss of neurological function and high medical care costs. Currently, no effective treatment exists to improve the prognosis of patients. Astrocytes comprise the largest population of glial cells in the CNS and, with the advancements in the field of neurology, are increasingly recognized as having key functions in both the brain and the spinal cord. When stimulated by disease or injury, astrocytes become activated and undergo a series of changes, including alterations in gene expression, hypertrophy, the loss of inherent functions, and the acquisition of new ones. Studies have shown that astrocytes are highly heterogeneous with respect to their gene expression profiles, and this heterogeneity accounts for their observed context-dependent phenotypic diversity. In the inured CNS, activated astrocytes play a dual role both as regulators of neuroinflammation and in scar formation. Identifying the subpopulations of reactive astrocytes that exert beneficial or harmful effects will aid in deciphering the pathological mechanisms underlying CNS injuries and ultimately provide a theoretical basis for the development of effective strategies for the treatment of associated conditions. Following CNS injury, as the disease progresses, astrocyte phenotypes undergo continuous changes. Although current research methods do not allow a comprehensive and accurate classification of astrocyte subpopulations in complex pathological contexts, they can nonetheless aid in understanding the roles of astrocytes in disease. In this review, after a brief introduction to the pathology of CNS injury, we summarize current knowledge regarding astrocyte activation following CNS injury, including: (a) the regulatory factors involved in this process; (b) the functions of different astrocyte subgroups based on the existing classification of astrocytes; and (c) attempts at astrocyte-targeted therapy.

A diet rich in docosahexaenoic acid enhances reactive astrogliosis and ramified microglia morphology in apolipoprotein E epsilon 4-targeted replacement mice

Docosahexaenoic acid (DHA) consumption reduces spatial memory impairment in mice carrying the human apolipoprotein E ε4 (APOE4) allele. The current study evaluated whether astrocyte and microglia morphology contribute to the mechanism of this result. APOE3 and APOE4 mice were fed either a DHA-enriched diet or a control diet from 4 to 12 months of age. Coronal brain sections were immunostained for GFAP, Iba1, and NeuN. Astrocytes from APOE4 mice exhibited signs of reactive astrogliosis compared to APOE3 mice. Consumption of DHA exacerbated reactive astrocyte morphology in APOE4 carriers. Microglia from APOE4-control mice exhibited characteristics of amoeboid morphology and other characteristics of ramified morphology (more processes, greater process complexity, and greater distance between neighboring microglia). DHA enhanced ramified microglia morphology in APOE4 mice. In addition, APOE4 mice fed the DHA diet had lower hippocampal concentrations of interleukin-7, lipopolysaccharide-induced CXC chemokine and monocyte chemoattractant protein 1, and higher concentration of interferon-gamma compared to APOE4-control mice. Our results indicate that a diet rich in DHA enhances reactive astrogliosis and ramified microglia morphology in APOE4 mice.

The Roles of Neurotrophins in Traumatic Brain Injury

Neurotrophins are a collection of structurally and functionally related proteins. They play important roles in many aspects of neural development, survival, and plasticity. Traumatic brain injury (TBI) leads to different levels of central nervous tissue destruction and cellular repair through various compensatory mechanisms promoted by the injured brain. Many studies have shown that neurotrophins are key modulators of neuroinflammation, apoptosis, blood–brain barrier permeability, memory capacity, and neurite regeneration. The expression of neurotrophins following TBI is affected by the severity of injury, genetic polymorphism, and different post-traumatic time points. Emerging research is focused on the potential therapeutic applications of neurotrophins in managing TBI. We conducted a comprehensive review by organizing the studies that demonstrate the role of neurotrophins in the management of TBI.

Mitochondrial Dysfunction in Advanced Liver Disease: Emerging Concepts

Mitochondria are entrusted with the challenging task of providing energy through the generation of ATP, the universal cellular currency, thereby being highly flexible to different acute and chronic nutrient demands of the cell. The fact that mitochondrial diseases (genetic disorders caused by mutations in the nuclear or mitochondrial genome) manifest through a remarkable clinical variation of symptoms in affected individuals underlines the far-reaching implications of mitochondrial dysfunction. The study of mitochondrial function in genetic or non-genetic diseases therefore requires a multi-angled approach. Taking into account that the liver is among the organs richest in mitochondria, it stands to reason that in the process of unravelling the pathogenesis of liver-related diseases, researchers give special focus to characterizing mitochondrial function. However, mitochondrial dysfunction is not a uniformly defined term. It can refer to a decline in energy production, increase in reactive oxygen species and so forth. Therefore, any study on mitochondrial dysfunction first needs to define the dysfunction to be investigated. Here, we review the alterations of mitochondrial function in liver cirrhosis with emphasis on acutely decompensated liver cirrhosis and acute-on-chronic liver failure (ACLF), the latter being a form of acute decompensation characterized by a generalized state of systemic hyperinflammation/immunosuppression and high mortality rate. The studies that we discuss were either carried out in liver tissue itself of these patients, or in circulating leukocytes, whose mitochondrial alterations might reflect tissue and organ mitochondrial dysfunction. In addition, we present different methodological approaches that can be of utility to address the diverse aspects of hepatocyte and leukocyte mitochondrial function in liver disease. They include assays to measure metabolic fluxes using the comparatively novel Biolog’s MitoPlates in a 96-well format as well as assessment of mitochondrial respiration by high-resolution respirometry using Oroboros’ O2k-technology and Agilent Seahorse XF technology.

Metformin attenuates LPS-induced neuronal injury and cognitive impairments by blocking NF-κB pathway

BACKGROUND

Neuroinflammatory response is considered to be a high-risk factor for cognitive impairments in the brain. Lipopolysaccharides (LPS) is an endotoxin that induces acute inflammatory responses in injected bodies. However, the molecular mechanisms underlying LPS-associated cognitive impairments still remain unclear.

METHODS

Here, primary hippocampal neurons were treated with LPS, and western blotting and immunofluorescence were used to investigate whether LPS induces neurons damage. At the same time, SD rats were injected with LPS (830 μg/Kg) intraperitoneally, and Open field test, Novel Objective Recognition test, Fear condition test were used to detect cognitive function. LTP was used to assess synaptic plasticity, and molecular biology technology was used to assess the NF-κB pathway, while ELISA was used to detect inflammatory factors. In addition, metformin was used to treat primary hippocampal neurons, and intraventricularly administered to SD rats. The same molecular technics, behavioral and electrophysiological tests were used to examine whether metformin could alleviate the LPS-associated neuronal damage, as well as synaptic plasticity, and behavioral alterations in SD rats.

RESULTS

Altogether, neuronal damage were observed in primary hippocampal neurons after LPS intervention, which were alleviated by metformin treatment. At the same time, LPS injection in rat triggers cognitive impairment through activation of NF-κB signaling pathway, and metformin administration alleviates the LPS-induced memory dysfunction and improves synaptic plasticity.

CONCLUSION

These findings highlight a novel pathogenic mechanism of LPS-related cognitive impairments through activation of NF-κB signaling pathway, and accumulation of inflammatory mediators, which induces neuronal pathologic changes and cognitive impairments. However, metformin attenuates LPS-induced neuronal injury and cognitive impairments by blocking NF-κB pathway.

Biofidelic dynamic compression of human cortical spheroids reproduces neurotrauma phenotypes

Fundamental questions about patient heterogeneity and human-specific pathophysiology currently obstruct progress towards a therapy for traumatic brain injury (TBI). Human in vitro models have the potential to address these questions. 3D spheroidal cell culture protocols for human-origin neural cells have several important advantages over their 2D monolayer counterparts. Three dimensional spheroidal cultures may mature more quickly, develop more biofidelic electrophysiological activity and/or reproduce some aspects of brain architecture. Here, we present the first human in vitro model of non-penetrating TBI employing 3D spheroidal cultures. We used a custom-built device to traumatize these spheroids in a quantifiable, repeatable and biofidelic manner and correlated the heterogeneous, mechanical strain field with the injury phenotype. Trauma reduced cell viability, mitochondrial membrane potential and spontaneous, synchronous, electrophysiological activity in the spheroids. Electrophysiological deficits emerged at lower injury severities than changes in cell viability. Also, traumatized spheroids secreted lactate dehydrogenase, a marker of cell damage, and neurofilament light chain, a promising clinical biomarker of neurotrauma. These results demonstrate that 3D human in vitro models can reproduce important phenotypes of neurotrauma in vitro.

The Protective Role of E-64d in Hippocampal Excitotoxic Neuronal Injury Induced by Glutamate in HT22 Hippocampal Neuronal Cells

Epilepsy is the most common childhood neurologic disorder. Status epilepticus (SE), which refers to continuous epileptic seizures, occurs more frequently in children than in adults, and approximately 40–50% of all cases occur in children under 2 years of age. Conventional antiepileptic drugs currently used in clinical practice have a number of adverse side effects. Drug-resistant epilepsy (DRE) can progressively develop in children with persistent SE, necessitating the development of novel therapeutic drugs. During SE, the persistent activation of neurons leads to decreased glutamate clearance with corresponding glutamate accumulation in the synaptic extracellular space, increasing the chance of neuronal excitotoxicity. Our previous study demonstrated that after developmental seizures in rats, E-64d exerts a neuroprotective effect on the seizure-induced brain damage by modulating lipid metabolism enzymes, especially ApoE and ApoJ/clusterin. In this study, we investigated the impact and mechanisms of E-64d administration on neuronal excitotoxicity. To test our hypothesis that E-64d confers neuroprotective effects by regulating autophagy and mitochondrial pathway activity, we simulated neuronal excitotoxicity in vitro using an immortalized hippocampal neuron cell line (HT22). We found that E-64d improved cell viability while reducing oxidative stress and neuronal apoptosis. In addition, E-64d treatment regulated mitochondrial pathway activity and inhibited chaperone-mediated autophagy in HT22 cells. Our findings indicate that E-64d may alleviate glutamate-induced damage via regulation of mitochondrial fission and apoptosis, as well as inhibition of chaperone-mediated autophagy. Thus, E-64d may be a promising therapeutic treatment for hippocampal injury associated with SE.

Resolvin D1 prevents cadmium chloride-induced memory loss and hippocampal damage in rats by activation/upregulation of PTEN-induced suppression of PI3K/Akt/mTOR signaling pathway

This study evaluated the protective effect of resolvin D1 (RVD1) against cadmium chloride (CdCl₂ )-induced hippocampal damage and memory loss in rats and investigated if such protection is mediated by modulating the PTEN/PI3K/Akt/mTOR pathway. Adult male Wistar rats (n = 18/group) were divided as control, control + RVD1, CdCl₂ , CdCl₂  + RVD1 and CdCl₂  + RVD1 + bpV(pic), a PTEN inhibitor. All treatments were conducted for 4 weeks. Resolvin D1 improved the memory function as measured by Morris water maze (MWM), preserved the structure of CA1 area of the hippocampus, and increased hippocampal levels of RVD1 in the CdCl₂ -treated rats. Resolvin D1 also suppressed the generation of reactive oxygen species (ROS), tumour necrosis factor-α and interleukine-6 (IL-6), inhibited nuclear factor κB (NF-κB) p65, stimulated levels of glutathione (GSH), manganese superoxide dismutase (MnSOD), and Bcl2 but reduced the expression of Bax and cleaved caspase 3 in hippocampi of CdCl₂ -treated rats. Concomitantly, it stimulated levels and activity of PTEN and reduced the phosphorylation (activation) of PI3K, Akt and mTOR in hippocampi of CdCl₂ -treated rats. In conclusion, RVD1 attenuates CdCl₂ -induced memory loss and hippocampal damage in rats mainly by activating PTEN-induced suppression of PI3K/Akt/mTOR, an effect that seems secondary to its' anti-oxidant and anti-inflammatory potential.

Pursuing Multiple Biomarkers for Early Idiopathic Parkinson's Disease Diagnosis

Parkinson's disease (PD) ranks first in the world as a neurodegenerative movement disorder and occurs most commonly in an idiopathic form. PD patients may have motor symptoms, non-motor symptoms, including cognitive and behavioral changes, and symptoms related to autonomic nervous system (ANS) failures, such as gastrointestinal, urinary, and cardiovascular symptoms. Unfortunately, the diagnostic accuracy of PD by general neurologists is relatively low. Currently, there is no objective molecular or biochemical test for PD; its diagnosis is based on clinical criteria, mainly by cardinal motor symptoms, which manifest when patients have lost about 60-80% of dopaminergic neurons. Therefore, it is urgent to establish a panel of biomarkers for the early and accurate diagnosis of PD. Once the disease is accurately diagnosed, it may be easier to unravel idiopathic PD's pathogenesis, and ultimately, finding a cure. This review discusses several biomarkers' potential to set a panel for early idiopathic PD diagnosis and future directions.

Single-Cell Transcriptomics-Based Study of Transcriptional Regulatory Features in the Mouse Brain Vasculature

Background

The critical role of vascular health on brain function has received much attention in recent years. At the single-cell level, studies on the developmental processes of cerebral vascular growth are still relatively few. Techniques for constructing gene regulatory networks (GRNs) based on single-cell transcriptome expression data have made significant progress in recent years. Herein, we constructed a single-cell transcriptional regulatory network of mouse cerebrovascular cells.

Methods

The single-cell RNA-seq dataset of mouse brain vessels was downloaded from GEO (GSE98816). This cell clustering was annotated separately using singleR and CellMarker. We then used a modified version of the SCENIC method to construct GRNs. Next, we used a mouse version of SEEK to assess whether genes in the regulon were coexpressed. Finally, regulatory module analysis was performed to complete the cell type relationship quantification.

Results

Single-cell RNA-seq data were used to analyze the heterogeneity of mouse cerebrovascular cells, whereby four cell types including endothelial cells, fibroblasts, microglia, and oligodendrocytes were defined. These subpopulations of cells and marker genes together characterize the molecular profile of mouse cerebrovascular cells. Through these signatures, key transcriptional regulators that maintain cell identity were identified. Our findings identified genes like Lmo2, which play an important role in endothelial cells. The same cell type, for instance, fibroblasts, was found to have different regulatory networks, which may influence the functional characteristics of local tissues.

Conclusions

In this study, a transcriptional regulatory network based on single-cell analysis was constructed. Additionally, the study identified and profiled mouse cerebrovascular cells using single-cell transcriptome data as well as defined TFs that affect the regulatory network of the mouse brain vasculature.

Sex and Age-Related Differences in Neuroinflammation and Apoptosis in Balb/c Mice Retina Involve Resolvin D1

(1) Background: The pro-resolving lipid mediator Resolvin D1 (RvD1) has already shown protective effects in animal models of diabetic retinopathy. This study aimed to investigate the retinal levels of RvD1 in aged (24 months) and younger (3 months) Balb/c mice, along with the activation of macro- and microglia, apoptosis, and neuroinflammation. (2) Methods: Retinas from male and female mice were used for immunohistochemistry, immunofluorescence, transmission electron microscopy, Western blotting, and enzyme-linked immunosorbent assays. (3) Results: Endogenous retinal levels of RvD1 were reduced in aged mice. While RvD1 levels were similar in younger males and females, they were markedly decreased in aged males but less reduced in aged females. Both aged males and females showed a significant increase in retinal microglia activation compared to younger mice, with a more marked reactivity in aged males than in aged females. The same trend was shown by astrocyte activation, neuroinflammation, apoptosis, and nitrosative stress, in line with the microglia and Müller cell hypertrophy evidenced in aged retinas by electron microscopy. (4) Conclusions: Aged mice had sex-related differences in neuroinflammation and apoptosis and low retinal levels of endogenous RvD1.

Bioactive Lipid Mediators in the Initiation and Resolution of Inflammation after Spinal Cord Injury

Neuroinflammation is a prominent feature of the response to CNS trauma. It is also an important hallmark of various neurodegenerative diseases in which inflammation contributes to the progression of pathology. Inflammation in the CNS can contribute to secondary damage and is therefore an excellent therapeutic target for a range of neurological conditions. Inflammation in the nervous system is complex and varies in its fine details in different conditions. It involves a wide variety of secreted factors such as chemokines and cytokines, cell adhesion molecules, and different cell types that include resident cell of the CNS, as well as immune cells recruited from the peripheral circulation. Added to this complexity is the fact that some aspects of inflammation are beneficial, while other aspects can induce secondary damage in the acute, subacute and chronic phases. Understanding these aspects of the inflammatory profile is essential for developing effective therapies. Bioactive lipids constitute a large group of molecules that modulate the initiation and the resolution of inflammation. Dysregulation of these bioactive lipid pathways can lead to excessive acute inflammation, and failure to resolve this by specialized pro-resolution lipid mediators can lead to the development of chronic inflammation. The focus of this review is to discuss the effects of bioactive lipids in spinal cord trauma and their potential for therapies.

Specialized Pro-resolving Lipid Mediators and Glial Cells: Emerging Candidates for Brain Homeostasis and Repair

Astrocytes and oligodendrocytes are known to play critical roles in the central nervous system development, homeostasis and response to injury. In addition to their well-defined functions in synaptic signaling, blood-brain barrier control and myelination, it is now becoming clear that both glial cells also actively produce a wide range of immune-regulatory factors and engage in an intricate communication with neurons, microglia or with infiltrated immune cells, thus taking a center stage in both inflammation and resolution processes occurring within the brain. Resolution of inflammation is operated by the superfamily of specialized pro-resolving lipid mediators (SPMs), that include lipoxins, resolvins, protectins and maresins, and that altogether activate a series of cellular and molecular events that lead to spontaneous regression of inflammatory processes and restoration of tissue homeostasis. Here, we review the manifold effects of SPMs on modulation of astrocytes and oligodendrocytes, along with the mechanisms through which they either inhibit inflammatory pathways or induce the activation of protective ones. Furthermore, the possible role of SPMs in modulating the cross-talk between microglia, astrocytes and oligodendrocytes is also summarized. This SPM-mediated mechanism uncovers novel pathways of immune regulation in the brain that could be further exploited to control neuroinflammation and neurodegeneration.

Recurrent non-severe hypoglycemia aggravates cognitive decline in diabetes and induces mitochondrial dysfunction in cultured astrocytes

The present study aimed to determine the relationship between astrocytes and recurrent non-severe hypoglycemia (RH)2 -associated cognitive decline in diabetes. RH induced cognitive impairment and neuronal cell death in the cerebral cortex of diabetic mice, accompanied by excessive activation of astrocytes. Levels of the neurotrophins BDNF and GDNF, together with BDNF and GDNF- related signaling, were downregulated by RH. In vitro, recurrent low glucose (RLG)3 impaired cell viability and induced apoptosis of high-glucose cultured astrocytes. Accumulating mitochondrial ROS and dysregulated mitochondrial functions, including abnormal morphology, decreased membrane potential, downregulated ATP levels, and disrupted bioenergetic status, were observed in these cells. SS-31 mediated protection of mitochondrial functions reversed RLG-induced cell viability defects and neurotrophin production. These findings demonstrate that RH induced astrocyte overactivation and mitochondrial dysfunction, leading to astrocyte-derived neurotrophin disturbance, which might contribute to diabetic cognitive decline. Targeting astrocyte mitochondria might represent a neuroprotective therapy for hypoglycemia-associated neurodegeneration in diabetes.

Exploiting formyl peptide receptor 2 to promote microglial resolution: a new approach to Alzheimer's disease treatment

Alzheimer's disease and dementia are among the most significant current healthcare challenges given the rapidly growing elderly population, and the almost total lack of effective therapeutic interventions. Alzheimer's disease pathology has long been considered in terms of accumulation of amyloid beta and hyperphosphorylated tau, but the importance of neuroinflammation in driving disease has taken greater precedence over the last 15-20 years. Inflammatory activation of the primary brain immune cells, the microglia, has been implicated in Alzheimer's pathogenesis through genetic, preclinical, imaging and postmortem human studies, and strategies to regulate microglial activity may hold great promise for disease modification. Neuroinflammation is necessary for defence of the brain against pathogen invasion or damage but is normally self-limiting due to the engagement of endogenous pro-resolving circuitry that terminates inflammatory activity, a process that appears to fail in Alzheimer's disease. Here, we discuss the potential for a major regulator and promoter of resolution, the receptor FPR2, to restrain pro-inflammatory microglial activity, and propose that it may serve as a valuable target for therapeutic investigation in Alzheimer's disease.

The Role of BDNF in Experimental and Clinical Traumatic Brain Injury

Traumatic brain injury is one of the leading causes of mortality and morbidity in the world with no current pharmacological treatment. The role of BDNF in neural repair and regeneration is well established and has also been the focus of TBI research. Here, we review experimental animal models assessing BDNF expression following injury as well as clinical studies in humans including the role of BDNF polymorphism in TBI. There is a large heterogeneity in experimental setups and hence the results with different regional and temporal changes in BDNF expression. Several studies have also assessed different interventions to affect the BDNF expression following injury. Clinical studies highlight the importance of BDNF polymorphism in the outcome and indicate a protective role of BDNF polymorphism following injury. Considering the possibility of affecting the BDNF pathway with available substances, we discuss future studies using transgenic mice as well as iPSC in order to understand the underlying mechanism of BDNF polymorphism in TBI and develop a possible pharmacological treatment.

Resolvin D1 ameliorates Inflammation-Mediated Blood-Brain Barrier Disruption After Subarachnoid Hemorrhage in rats by Modulating A20 and NLRP3 Inflammasome

Inflammation is typically related to dysfunction of the blood-brain barrier (BBB) that leads to early brain injury (EBI) after subarachnoid hemorrhage (SAH). Resolvin D1 (RVD1), a lipid mediator derived from docosahexaenoic acid, possesses anti-inflammatory and neuroprotective properties. This study investigated the effects and mechanisms of RVD1 in SAH. A Sprague-Dawley rat model of SAH was established through endovascular perforation. RVD1was injected through the femoral vein at 1 and 12 h after SAH induction. To further explore the potential neuroprotective mechanism, a formyl peptide receptor two antagonist (WRW4) was intracerebroventricularly administered 1 h after SAH induction. The expression of endogenous RVD1 was decreased whereas A20 and NLRP3 levels were increased after SAH. An exogenous RVD1 administration increased RVD1 concentration in brain tissue, and improved neurological function, neuroinflammation, BBB disruption, and brain edema. RVD1 treatment upregulated the expression of A20, occludin, claudin-5, and zona occludens-1, as well as downregulated nuclear factor-κBp65, NLRP3, matrix metallopeptidase 9, and intercellular cell adhesion molecule-1 expression. Furthermore, RVD1 inhibited microglial activation and neutrophil infiltration and promoted neutrophil apoptosis. However, the neuroprotective effects of RVD1 were abolished by WRW4. In summary, our findings reveal that RVD1 provides beneficial effects against inflammation-triggered BBB dysfunction after SAH by modulating A20 and NLRP3 inflammasome.

Blockage of AEP attenuates TBI-induced tau hyperphosphorylation and cognitive impairments in rats

Traumatic brain injury (TBI) is regarded as a high-risk factor for Alzheimer's disease (AD). Asparaginyl endopeptidase (AEP), a lysosomal cysteine protease involved in AD pathogenesis, is normally activated under acidic conditions and also in TBI. However, both the molecular mechanism underlying AEP activation-mediated TBI-related AD pathologies, and the role of AEP as an AD therapeutic target, still remain unclear. Here, we report that TBI induces hippocampus dependent cognitive deficit and synaptic dysfunction, accompanied with AEP activation, I2PP2A (inhibitor 2 of PP2A, also called SET) mis-translocation from neuronal nucleus to cytoplasm, an obvious increase in AEP interaction with SET, and tau hyperphosphorylation in hippocampus of rats. Oxygen-glucose deprivation (OGD), mimicking an acidic condition, also leads to AEP activation, SET mis-translocation, PP2A inhibition, tau hyperphosphorylation, and a decrease in synaptic proteins, all of which are abrogated by AEP inhibitor AENK in primary neurons. Interestingly, AENK restores SET back to the nucleus, mitigates tau pathologies, rescuing TBI-induced cognitive deficit in rats. These findings highlight a novel etiopathogenic mechanism of TBI-related AD, which is initiated by AEP activation, accumulating SET in cytoplasm, and favoring tau pathology and cognitive impairments. Lowering AEP activity by AEP inhibitor would be beneficial to AD patients with TBI.