CCR5 Is a Therapeutic Target for Recovery after Stroke and Traumatic Brain Injury

Maf1 is an intrinsic suppressor against spontaneous neural repair and functional recovery after ischemic stroke

INTRODUCTION

Spontaneous recovery after CNS injury is often very limited and incomplete, leaving most stroke patients with permanent disability. Maf1 is known as a key growth suppressor in proliferating cells. However, its role in neuronal cells after stroke remains unclear.

OBJECTIVE

We aimed to investigate the mechanistic role of Maf1 in spontaneous neural repair and evaluated the therapeutic effect of targeting Maf1 on stroke recovery.

METHODS

We used mouse primary neurons to determine the signaling mechanism of Maf1, and the cleavage-under-targets-and-tagmentation-sequencing to map the whole-genome promoter binding sites of Maf1 in isolated mature cortical neurons. Photothrombotic stroke model was used to determine the therapeutic effect on neural repair and functional recovery by AAV-mediated Maf1 knockdown.

RESULTS

We found that Maf1 mediates mTOR signaling to regulate RNA polymerase III (Pol III)-dependent rRNA and tRNA transcription in mouse cortical neurons. mTOR regulates neuronal Maf1 phosphorylation and subcellular localization. Maf1 knockdown significantly increases Pol III transcription, neurite outgrowth and dendritic spine formation in neurons. Conversely, Maf1 overexpression suppresses such activities. In response to photothrombotic stroke in mice, Maf1 expression is increased and accumulates in the nucleus of neurons in the peripheral region of infarcted cortex, which is the key region for neural remodeling and repair during spontaneous recovery. Intriguingly, Maf1 knockdown in the peri-infarct cortex significantly enhances neural plasticity and functional recovery. Mechanistically, Maf1 not only interacts with the promoters and represses Pol III-transcribed genes, but also those of CREB-associated genes that are critical for promoting plasticity during neurodevelopment and neural repair.

CONCLUSION

These findings indicate Maf1 as an intrinsic neural repair suppressor against regenerative capability of mature CNS neurons, and suggest that Maf1 is a potential therapeutic target for enhancing functional recovery after ischemic stroke and other CNS injuries.

The NLRP3 inflammasome and gut dysbiosis as a putative link between HIV-1 infection and ischemic stroke

HIV-associated comorbidities, such as ischemic stroke, are prevalent in people with HIV (PWH). Several studies both in animal models and humans have revealed an association between activation of the inflammasome in HIV-1 infection and stroke. The gut microbiota is an important component in controlling neuroinflammation in the CNS. It has also been proposed to be involved in the pathobiology of HIV-1 infection, and has been associated with an increase in activation of the inflammasome. In this review, we provide an overview of the microbiota-gut-inflammasome-brain axis, focusing on the NLRP3 inflammasome and dysregulation of the microbiome as risk factors that may contribute to the outcome of ischemic stroke and recovery in PWH. We also focus on the potential of targeting the NLRP3 inflammasome as a novel therapeutic approach for PWH who are at risk of developing cerebrovascular diseases.

Prospects for Nerve Regeneration and Gene Therapy in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is a prevalent neurological disorder and a leading cause of death and disability worldwide. The high mortality rates result in a tremendous burden on society and families in terms of public health and economic costs. Despite advances in biomedical research, treatment options for TBI still remain limited, and there is no effective therapy to restore the structure and function of the injured brain. Regrettably, due to the excessive heterogeneity of TBI and the lack of objective and reliable efficacy evaluation indicators, no proven therapeutic drugs or drugs with clear benefits on functional outcomes have been successfully developed to date. Therefore, it is urgent to explore new therapeutic approaches to protect or regenerate the injured brain from different perspectives. In this review, we first provide a brief overview of the causes and current status of TBI and then summarize the preclinical and clinical research status of cutting-edge treatment methods, including nerve regeneration therapy and gene therapy, with the aim of providing valuable references for effective therapeutic strategies for TBI.

Two-photon microscopy: application advantages and latest progress for in vivo imaging of neurons and blood vessels after ischemic stroke

Two-photon microscopy (TPM) plays an important role in the study of the changes of the two important components of neurovascular units (NVU) - neurons and blood vessels after ischemic stroke (IS). IS refers to sudden neurological dysfunction caused by focal cerebral ischemia, which is one of the leading causes of death and disability worldwide. TPM is a new and rapidly developing high-resolution real-time imaging technique used in vivo that has attracted increasing attention from scientists in the neuroscience field. Neurons and blood vessels are important components of neurovascular units, and they undergo great changes after IS to respond to and compensate for ischemic injury. Here, we introduce the characteristics and pre-imaging preparations of TPM, and review the common methods and latest progress of TPM in the neuronal and vascular research for injury and recovery of IS in recent years. With the review, we clearly recognized that the most important advantage of TPM in the study of ischemic stroke is the ability to perform chronic longitudinal imaging of different tissues at a high resolution in vivo. Finally, we discuss the limitations of TPM and the technological advances in recent years.

Microglial-to-neuronal CCR5 signaling regulates autophagy in neurodegeneration

In neurodegenerative diseases, microglia switch to an activated state, which results in excessive secretion of pro-inflammatory factors. Our work aims to investigate how this paracrine signaling affects neuronal function. Here, we show that activated microglia mediate non-cell-autonomous inhibition of neuronal autophagy, a degradative pathway critical for the removal of toxic, aggregate-prone proteins accumulating in neurodegenerative diseases. We found that the microglial-derived CCL-3/-4/-5 bind and activate neuronal CCR5, which in turn promotes mTORC1 activation and disrupts autophagy and aggregate-prone protein clearance. CCR5 and its cognate chemokines are upregulated in the brains of pre-manifesting mouse models for Huntington's disease (HD) and tauopathy, suggesting a pathological role of this microglia-neuronal axis in the early phases of these diseases. CCR5 upregulation is self-sustaining, as CCL5-CCR5 autophagy inhibition impairs CCR5 degradation itself. Finally, pharmacological or genetic inhibition of CCR5 rescues mTORC1 hyperactivation and autophagy dysfunction, which ameliorates HD and tau pathologies in mouse models.

Site-specific transgene integration in chimeric antigen receptor (CAR) T cell therapies

Chimeric antigen receptor (CAR) T cells and natural killer (NK) cells are genetically engineered immune cells that can detect target antigens on the surface of target cells and eliminate them following adoptive transfer. Recent progress in CAR-based therapies has led to outstanding clinical success in certain patients with leukemias and lymphomas and offered therapeutic benefits to those resistant to conventional therapies. The universal approach to stable CAR transgene delivery into the T/NK cells is the use of viral particles. Such approaches mediate semi-random transgene insertions spanning the entire genome with a high preference for integration into sites surrounding highly-expressed genes and active loci. Regardless of the variable CAR expression level based on the integration site of the CAR transgene, foreign integrated DNA fragments may affect the neighboring endogenous genes and chromatin structure and potentially change a transduced T/NK cell behavior and function or even favor cellular transformation. In contrast, site-specific integration of CAR constructs using recent genome-editing technologies could overcome the limitations and disadvantages of universal random gene integration. Herein, we explain random and site-specific integration of CAR transgenes in CAR-T/NK cell therapies. Also, we tend to summarize the methods for site-specific integration as well as the clinical outcomes of certain gene disruptions or enhancements due to CAR transgene integration. Also, the advantages and limitations of using site-specific integration methods are discussed in this review. Ultimately, we will introduce the genomic safe harbor (GSH) standards and suggest some appropriate safety prospects for CAR integration in CAR-T/NK cell therapies.

Site-specific transgene integration in chimeric antigen receptor (CAR) T cell therapies

Chimeric antigen receptor (CAR) T cells and natural killer (NK) cells are genetically engineered immune cells that can detect target antigens on the surface of target cells and eliminate them following adoptive transfer. Recent progress in CAR-based therapies has led to outstanding clinical success in certain patients with leukemias and lymphomas and offered therapeutic benefits to those resistant to conventional therapies. The universal approach to stable CAR transgene delivery into the T/NK cells is the use of viral particles. Such approaches mediate semi-random transgene insertions spanning the entire genome with a high preference for integration into sites surrounding highly-expressed genes and active loci. Regardless of the variable CAR expression level based on the integration site of the CAR transgene, foreign integrated DNA fragments may affect the neighboring endogenous genes and chromatin structure and potentially change a transduced T/NK cell behavior and function or even favor cellular transformation. In contrast, site-specific integration of CAR constructs using recent genome-editing technologies could overcome the limitations and disadvantages of universal random gene integration. Herein, we explain random and site-specific integration of CAR transgenes in CAR-T/NK cell therapies. Also, we tend to summarize the methods for site-specific integration as well as the clinical outcomes of certain gene disruptions or enhancements due to CAR transgene integration. Also, the advantages and limitations of using site-specific integration methods are discussed in this review. Ultimately, we will introduce the genomic safe harbor (GSH) standards and suggest some appropriate safety prospects for CAR integration in CAR-T/NK cell therapies.

The role of signaling crosstalk of microglia in hippocampus on progression of ageing and Alzheimer's disease

Based on single-cell sequencing of the hippocampi of 5× familiar Alzheimer's disease (5× FAD) and wild type mice at 2-, 12-, and 24-month of age, we found an increased percentage of microglia in aging and Alzheimer's disease (AD) mice. Blood brain barrier injury may also have contributed to this increase. Immune regulation by microglia plays a major role in the progression of aging and AD, according to the functions of 41 intersecting differentially expressed genes in microglia. Signaling crosstalk between C-C motif chemokine ligand (CCL) and major histocompatibility complex-1 bridges intercellular communication in the hippocampus during aging and AD. The amyloid precursor protein (APP) and colony stimulating factor (CSF) signals drive 5× FAD to deviate from aging track to AD occurrence among intercellular communication in hippocampus. Microglia are involved in the progression of aging and AD can be divided into 10 functional types. The strength of the interaction among microglial subtypes weakened with aging, and the CCL and CSF signaling pathways were the fundamental bridge of communication among microglial subtypes.

Dual effect of C-C motif chemokine receptor 5 on ischemic stroke: More harm than benefit?

Ischemic stroke involves a series of complex pathological mechanisms, of which neuroinflammation is currently the most widely recognized. C-C motif chemokine receptor 5 (CCR5) has recently been shown to be upregulated after cerebral ischemia. Notably, CCR5 is not only involved in neuroinflammation, but also in the blood-brain barrier, neural structures, and connections. Accumulating experimental studies indicate that CCR5 has a dual effect on ischemic stroke. In the acute phase after cerebral ischemia, the pro-inflammatory and disruptive effect of CCR5 on the blood-brain barrier predominates. However, in the chronic phase, the effect of CCR5 on the repair of neural structures and connections is thought to be cell-type dependent. Interestingly, clinical evidence has shown that CCR5 might be harmful rather than beneficial. CCR5-Δ32 mutation or CCR5 antagonist exerts a neuroprotective effect in patients with ischemic stroke. Considering CCR5 as an attractive potential target, we introduce the current research progress of the entangled relationships between CCR5 and ischemic stroke. Clinical data are still needed to determine the efficacy of activating or inactivating CCR5 in the treatment of ischemic stroke, especially for potential phase- or cell type-dependent treatments in the future.

Supporting Post-Stroke Language and Cognition with Pharmacotherapy: Tools for Each Phase of Care

PURPOSE OF REVIEW

There is enormous enthusiasm for the possibility of pharmacotherapies to treat language deficits that can arise after stroke. Speech language therapy remains the most frequently utilized and most strongly evidenced treatment, but the numerous barriers to patients receiving the therapy necessary to recover have motivated the creation of a relatively modest, yet highly cited, body of evidence to support the use of pharmacotherapy to treat post-stroke aphasia directly or to augment traditional post-stroke aphasia treatment. In this review, we survey the use of pharmacotherapy to preserve and support language and cognition in the context of stroke across phases of care, discuss key ongoing clinical trials, and identify targets that may become emerging interventions in the future.

RECENT FINDINGS

Recent trials have shifted focus from short periods of drug therapy supporting therapy in the chronic phase to longer terms approaching pharmacological maintenance beginning more acutely. Recent innovations in hyperacute stroke care, such as tenecteplase, and acute initiation of neuroprotective agents and serotonin reuptake inhibitors are important areas of ongoing research that complement the ongoing search for effective adjuvants to later therapy. Currently there are no drugs approved in the United States for the treatment of aphasia. Nevertheless, pharmacological intervention may provide a benefit to all phases of stroke care.

Mice deficient for G-protein-coupled receptor 75 display altered presynaptic structural protein expression and disrupted fear conditioning recall

There are a number of G-protein-coupled receptors (GPCRs) that are considered "orphan receptors" because the information on their known ligands is incomplete. Yet, these receptors are important targets to characterize, as the discovery of their ligands may lead to potential new therapies. GPR75 was recently deorphanized because at least two ligands appear to bind to it, the chemokine CCL5 and the eicosanoid 20-Hydroxyeicosatetraenoic acid. Recent reports suggest that GPR75 may play a role in regulating insulin secretion and obesity. However, little is known about the function of this receptor in the brain. To study the function of GPR75, we have generated a knockout (KO) mouse model of this receptor and we evaluated the role that this receptor plays in the adult hippocampus by an array of histological, proteomic, and behavioral endpoints. Using RNAscope® technology, we identified GPR75 puncta in several Rbfox3-/NeuN-positive cells in the hippocampus, suggesting that this receptor has a neuronal expression. Proteomic analysis of the hippocampus in 3-month-old GPR75 KO animals revealed that several markers of synapses, including synapsin I and II are downregulated compared with wild type (WT). To examine the functional consequence of this down-regulation, WT and GPR75 KO mice were tested on a hippocampal-dependent behavioral task. Both contextual memory and anxiety-like behaviors were significantly altered in GPR75 KO, suggesting that GPR75 plays a role in hippocampal activity.

Cerebral organoids transplantation repairs infarcted cortex and restores impaired function after stroke

Stroke usually causes prolonged or lifelong disability, owing to the permanent loss of infarcted tissue. Although a variety of stem cell transplantation has been explored to improve neuronal defect behavior by enhancing neuroplasticity, it remains unknown whether the infarcted tissue can be reconstructed. We here cultured human cerebral organoids derived from human pluripotent stem cells (hPSCs) and transplanted them into the junction of the infarct core and the peri-infarct zone of NOD-SCID mice subjected to stroke. Months later, we found that the grafted organoids survived well in the infarcted core, differentiated into target neurons, repaired infarcted tissue, sent axons to distant brain targets, and integrated into the host neural circuit and thereby eliminated sensorimotor defect behaviors of stroke mice, whereas transplantation of dissociated single cells from organoids failed to repair the infarcted tissue. Our study offers a new strategy for reconstructing infarcted tissue via organoids transplantation thereby reversing stroke-induced disability.

Matrix disequilibrium in Alzheimer's disease and conditions that increase Alzheimer's disease risk

Alzheimer's Disease (AD) and related dementias are a leading cause of death globally and are predicted to increase in prevalence. Despite this expected increase in the prevalence of AD, we have yet to elucidate the causality of the neurodegeneration observed in AD and we lack effective therapeutics to combat the progressive neuronal loss. Throughout the past 30 years, several non-mutually exclusive hypotheses have arisen to explain the causative pathologies in AD: amyloid cascade, hyper-phosphorylated tau accumulation, cholinergic loss, chronic neuroinflammation, oxidative stress, and mitochondrial and cerebrovascular dysfunction. Published studies in this field have also focused on changes in neuronal extracellular matrix (ECM), which is critical to synaptic formation, function, and stability. Two of the greatest non-modifiable risk factors for development of AD (aside from autosomal dominant familial AD gene mutations) are aging and APOE status, and two of the greatest modifiable risk factors for AD and related dementias are untreated major depressive disorder (MDD) and obesity. Indeed, the risk of developing AD doubles for every 5 years after ≥ 65, and the APOE4 allele increases AD risk with the greatest risk in homozygous APOE4 carriers. In this review, we will describe mechanisms by which excess ECM accumulation may contribute to AD pathology and discuss pathological ECM alterations that occur in AD as well as conditions that increase the AD risk. We will discuss the relationship of AD risk factors to chronic central nervous system and peripheral inflammation and detail ECM changes that may follow. In addition, we will discuss recent data our lab has obtained on ECM components and effectors in APOE4/4 and APOE3/3 expressing murine brain lysates, as well as human cerebrospinal fluid (CSF) samples from APOE3 and APOE4 expressing AD individuals. We will describe the principal molecules that function in ECM turnover as well as abnormalities in these molecular systems that have been observed in AD. Finally, we will communicate therapeutic interventions that have the potential to modulate ECM deposition and turnover in vivo.

Ketone bodies promote stroke recovery via GAT-1-dependent cortical network remodeling

Stroke is a leading cause of adult disability worldwide, and better drugs are needed to promote functional recovery after stroke. Growing evidence suggests the critical role of network excitability during the repair phase for stroke recovery. Here, we show that β-hydroxybutyrate (β-HB), an essential ketone body (KB) component, is positively correlated with improved outcomes in patients with stroke and promotes functional recovery in rodents with stroke during the repair phase. These beneficial effects of β-HB depend on HDAC2/HDAC3-GABA transporter 1 (GAT-1) signaling-mediated enhancement of excitability and phasic GABA inhibition in the peri-infarct cortex and structural and functional plasticity in the ipsilateral cortex, the contralateral cortex, and the corticospinal tract. Together with available clinical approaches to elevate KB levels, our results offer a clinically translatable means to promote stroke recovery. Furthermore, GAT-1 can serve as a pharmacological target for developing drugs to promote functional recovery after stroke.

Pharmacological Modulation of the MIP-1 Family and Their Receptors Reduces Neuropathic Pain Symptoms and Influences Morphine Analgesia: Evidence from a Mouse Model

Neuropathic pain pathophysiology is not fully understood, but it was recently shown that MIP-1 family members (CCL3, CCL4, and CCL9) have strong pronociceptive properties. Our goal was to examine how pharmacological modulation of these chemokines and their receptors (CCR1 and CCR5) influence hypersensitivity after nerve injury in Albino Swiss male mice. The spinal changes in the mRNA/protein levels of the abovementioned chemokines and their receptors were measured using RT-qPCR and ELISA/Western blot techniques in a mouse model of chronic constriction injury of the sciatic nerve. Behavioral studies were performed using the von Frey and cold plate tests after pharmacological treatment with neutralizing antibodies (nAbs) against chemokines or antagonists (CCR1-J113863, CCR5-TAK-220/AZD-5672) alone and in coadministration with morphine on Day 7, when the hypersensitivity was fully developed. Our results showed enhanced protein levels of CCL3 and CCL9 1 and 7 days after nerve injury. The single intrathecal administration of CCL3 or CCL9 nAb, J113863, TAK-220, or AZD-5672 diminished neuropathic pain symptoms and enhanced morphine analgesia. These findings highlight the important roles of CCL3 and CCL9 in neuropathic pain and additionally indicate that these chemokines play essential roles in opioid analgesia. The obtained results suggest CCR1 and CCR5 as new, interesting targets in neuropathy treatment.

Neuroimmune mechanisms and therapies mediating post-ischaemic brain injury and repair

The nervous and immune systems control whole-body homeostasis and respond to various types of tissue injury, including stroke, in a coordinated manner. Cerebral ischaemia and subsequent neuronal cell death activate resident or infiltrating immune cells, which trigger neuroinflammation that affects functional prognosis after stroke. Inflammatory immune cells exacerbate ischaemic neuronal injury after the onset of brain ischaemia; however, some of the immune cells thereafter change their function to neural repair. The recovery processes after ischaemic brain injury require additional and close interactions between the nervous and immune systems through various mechanisms. Thus, the brain controls its own inflammation and repair processes after injury via the immune system, which provides a promising therapeutic opportunity for stroke recovery.

Acetylated α-tubulin alleviates injury to the dendritic spines after ischemic stroke in mice

BACKGROUND AND AIM

Functional recovery is associated with the preservation of dendritic spines in the penumbra area after stroke. Previous studies found that polymerized microtubules (MTs) serve a crucial role in regulating dendritic spine formation and plasticity. However, the mechanisms that are involved are poorly understood. This study is designed to understand whether the upregulation of acetylated α-tubulin (α-Ac-Tub, a marker for stable, and polymerized MTs) could alleviate injury to the dendritic spines in the penumbra area and motor dysfunction after ischemic stroke.

METHODS

Ischemic stroke was mimicked both in an in vivo and in vitro setup using middle cerebral artery occlusion and oxygen-glucose deprivation models. Thy1-YFP mice were utilized to observe the morphology of the dendritic spines in the penumbra area. MEC17 is the specific acetyltransferase of α-tubulin. Thy1 Cre^ERT2-eYFP and MEC17^fl/fl mice were mated to produce mice with decreased expression of α-Ac-Tub in dendritic spines of pyramidal neurons in the cerebral cortex. Moreover, AAV-PHP.B-DIO-MEC17 virus and tubastatin A (TBA) were injected into Thy1 Cre^ERT2-eYFP and Thy1-YFP mice to increase α-Ac-Tub expression. Single-pellet retrieval, irregular ladder walking, rotarod, and cylinder tests were performed to test the motor function after the ischemic stroke.

RESULTS

α-Ac-Tub was colocalized with postsynaptic density 95. Although knockout of MEC17 in the pyramidal neurons did not affect the density of the dendritic spines, it significantly aggravated the injury to them in the penumbra area and motor dysfunction after stroke. However, MEC17 upregulation in the pyramidal neurons and TBA treatment could maintain mature dendritic spine density and alleviate motor dysfunction after stroke.

CONCLUSION

Our study demonstrated that α-Ac-Tub plays a crucial role in the maintenance of the structure and functions of mature dendritic spines. Moreover, α-Ac-Tub protected the dendritic spines in the penumbra area and alleviated motor dysfunction after stroke.

CCL5/CCR5-mediated peripheral inflammation exacerbates blood‒brain barrier disruption after intracerebral hemorrhage in mice

BACKGROUND

Owing to metabolic disequilibrium and immune suppression, intracerebral hemorrhage (ICH) patients are prone to infections; according to a recent global analysis of stroke cases, approximately 10 million new-onset ICH patients had experienced concurrent infection. However, the intrinsic mechanisms underlying the effects of infection related peripheral inflammation after ICH remain unclear.

METHODS

Lipopolysaccharide (LPS) was intraperitoneally injected into ICH model mice to induce peripheral inflammation. Neurobehavioral deficits, blood‒brain barrier (BBB) disruption, and the expression of CCR5, JAK2, STAT3, and MMP9 were evaluated after treatment with recombinant CCL5 (rCCL5) (a CCR5 ligand), maraviroc (MVC) (an FDA-approved selective CCR5 antagonist), or JAK2 CRISPR plasmids.

RESULTS

Our study revealed that severe peripheral inflammation increased CCL5/CCR5 axis activation in multiple inflammatory cell types, including microglia, astrocytes, and monocytes, and aggravated BBB disruption and neurobehavioral dysfunction after ICH, possibly in part through the JAK2/STAT3 signaling pathway.

CONCLUSIONS

CCR5 might be a potential target for the clinical treatment of infection-induced exacerbation of BBB disruption following ICH.

Characteristics and pathogenesis of chemokines in the post-stroke stage

Chemokines, as small molecular proteins, play a crucial role in the immune and inflammatory responses after stroke. A large amount of evidence showed chemokines and their receptors were increasingly recognized as potential targets for stroke treatment, which were involved in the processing of neovascularization, neurogenesis, and neural network reconstruction. In this review, we summarized the characteristics of chemokine alterations throughout the post-stroke nerve repair phase to gain insight into the pathological mechanisms of chemokines and find effective therapeutic targets for stroke.

CCR5-Δ32 polymorphism-a possible protective factor from gait impairment amongst post-stroke patients

BACKGROUND AND PURPOSE

Stroke and small vessel disease cause gait disturbances and falls. The naturally occurring loss-of-function mutation in the C-C chemokine receptor 5 gene (CCR5-Δ32) has recently been reported as a protective factor in post-stroke motor and cognitive recovery. We sought to examine whether it also influences gait and balance measures up to 2 years after stroke.

METHOD

Participants were 575 survivors of first-ever, mild-moderate ischaemic stroke or transient ischaemic attack from the TABASCO prospective study, who underwent a 3 T magnetic resonance imaging at baseline and were examined by a multi-professional team 6, 12 and 24 months after the event, using neurological, neuropsychological and mobility examinations. Gait rhythm and the timing of the gait cycle were measured by force-sensitive insoles. CCR5-Δ32 status and gait measures were available for 335 patients.

RESULTS

CCR5-Δ32 carriers (16.4%) had higher gait speed and decreased (better) stride and swing time variability 6 and 12 months after the index event compared to non-carriers (p < 0.01 for all). The association remained significant after adjustment for age, gender, education, ethnicity and stroke severity.

CONCLUSIONS

Significant associations were found between gait measurements and CCR5-Δ32 loss-of-function mutation amongst stroke survivors. This is the first study showing that genetic predisposition may predict long-term gait function after ischaemic stroke.

The Finer Aspects of Grid-Walking and Cylinder Tests for Experimental Stroke Recovery Studies in Mice

The choice of behavioral tests and their proper execution is critically important for experimental and preclinical therapeutic stroke recovery studies, where improvement of impaired neurological function(s) is the main outcome measure. Two tests that focus on spontaneous motor behaviors of the forelimb during gait and exploratory rearing and are expert recommended for stroke recovery studies in mice are grid-walking and cylinder tasks. Both tests have been widely used in various experimental stroke studies to evaluate acute and chronic motor impairment. To facilitate adoption of these tests and consistency of use between different research laboratories, this chapter describes a simple and rigorous protocol and our schemes to successfully perform both tasks in mice and evaluate motor dysfunction and recovery after stroke. In addition, we provide practical tips to minimize experimental bias and acquire data for analyses.

Accelerated brain aging with opioid misuse and HIV: New insights on the role of glially derived pro-inflammation mediators and neuronal chloride homeostasis

Opioid use disorder (OUD) has become a national crisis and contributes to the spread of human immunodeficiency virus (HIV) infection. Emerging evidence and advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal that opioids per se can directly exacerbate the pathophysiology of neuroHIV. Despite substantial inroads, the impact of OUD on the severity, development, and prognosis of neuroHIV and HIV-associated neurocognitive disorders is not fully understood. In this review, we explore current evidence that OUD and neuroHIV interact to accelerate cognitive deficits and enhance the neurodegenerative changes typically seen with aging, through their effects on neuroinflammation. We suggest new thoughts on the processes that may underlie accelerated brain aging, including dysregulation of neuronal inhibition, and highlight findings suggesting that opioids, through actions at the μ-opioid receptor, interact with HIV in the central nervous system to promote unique structural and functional comorbid deficits not seen in either OUD or neuroHIV alone.

State of the Art and Future of Stem Cell Therapy in Ischemic Stroke: Why Don't We Focus on Their Administration?

Stroke is one of the leading causes of death and disability worldwide, so there is an urgent need to find a therapy for the tragic outcomes of this cerebrovascular disease. Stem cells appeared to be a good solution for many conditions, so different experiments were made to establish stem cells as a feasible therapy for stroke. The aim of this review is to analyze the state of the art of stem cell therapy for stroke and if the route of administration could represent a valid adjusting point for ameliorating the therapy's outcome. To obtain this, we searched the scientific literature of the last 10 years for relevant in vitro and in vivo evidence regarding stem cells' potential in stroke therapy. In vitro evidence points to hypoxia, among the preconditioning strategies, as the most used and probably efficient method to enhance cells qualities, while in vivo results raise the question if it is the type of cells or how they are administrated which can make the difference in terms of efficiency. Unfortunately, despite the number of clinical trials, only a few were successfully concluded, demonstrating how urgent the necessity is to translate pre-clinical results into clinics. Since any type of stem cell seems suitable for therapy, the chosen route of administration corresponds to different engraftment rates, distribution and efficiency in terms of the beneficial effects of stem cells. Intravenous administration was widely used for delivering stem cells into the human body, but recently intranasal administration has given promising results in vivo. It allows stem cells to efficiently reach the brain that was precluded to intravenous administration, so it is worth further investigation.

The roles of chemokines following intracerebral hemorrhage in animal models and humans

Intracerebral hemorrhage (ICH) is one common yet devastating stroke subtype, imposing considerable burdens on families and society. Current guidelines are limited to symptomatic treatments after ICH, and the death rate remains significant in the acute stage. Thus, it is crucial to promote research to develop new targets on brain injury after ICH. In response to hematoma formation, amounts of chemokines are released in the brain, triggering the infiltration of resident immune cells in the brain and the chemotaxis of peripheral immune cells via the broken blood-brain barrier. During the past decades, mounting studies have focused on the roles of chemokines and their receptors in ICH injury. This review summarizes the latest advances in the study of chemokine functions in the ICH. First, we provide an overview of ICH epidemiology and underlying injury mechanisms in the pathogenesis of ICH. Second, we introduce the biology of chemokines and their receptors in brief. Third, we outline the roles of chemokines in ICH according to subgroups, including CCL2, CCL3, CCL5, CCL12, CCL17, CXCL8, CXCL12, and CX3CL1. Finally, we summarize current drug usage targeting chemokines in ICH and other cardio-cerebrovascular diseases. This review discusses the expressions of these chemokines and receptors under normal or hemorrhagic conditions and cell-specific sources. Above all, we highlight the related data of these chemokines in the progression and outcomes of the ICH disease in preclinical and clinical studies and point to therapeutic opportunities targeting chemokines productions and interactions in treating ICH, such as accelerating hematoma absorption and alleviating brain edema.

Quantitative Spatial Mapping of Axons Across Cortical Regions to Assess Axonal Sprouting After Stroke

Neurological disease such as a stroke causes death of brain tissue and loss of connectivity. Paradoxically, the stroke itself induces growth of new axonal collaterals, a phenomenon that is restrained in the normal adult brain. Enhancements in sprouting of axons have been linked with enhancements in motor function. Here, we describe a method developed in-house using standard reagents to map and quantitatively assess differential sprouting responses in stroke and following treatment with candidate molecular or pharmacological targets. This method allows for measurements of axonal growth responses that act as structural correlates for neural repair processes in the brain that aid in stroke recovery.

Maraviroc promotes recovery from traumatic brain injury in mice by suppression of neuroinflammation and activation of neurotoxic reactive astrocytes

Neuroinflammation and the NACHT, LRR, and PYD domains-containing protein 3 inflammasome play crucial roles in secondary tissue damage following an initial insult in patients with traumatic brain injury (TBI). Maraviroc, a C-C chemokine receptor type 5 antagonist, has been viewed as a new therapeutic strategy for many neuroinflammatory diseases. We studied the effect of maraviroc on TBI-induced neuroinflammation. A moderate-TBI mouse model was subjected to a controlled cortical impact device. Maraviroc or vehicle was injected intraperitoneally 1 hour after TBI and then once per day for 3 consecutive days. Western blot, immunohistochemistry, and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) analyses were performed to evaluate the molecular mechanisms of maraviroc at 3 days post-TBI. Our results suggest that maraviroc administration reduced NACHT, LRR, and PYD domains-containing protein 3 inflammasome activation, modulated microglial polarization from M1 to M2, decreased neutrophil and macrophage infiltration, and inhibited the release of inflammatory factors after TBI. Moreover, maraviroc treatment decreased the activation of neurotoxic reactive astrocytes, which, in turn, exacerbated neuronal cell death. Additionally, we confirmed the neuroprotective effect of maraviroc using the modified neurological severity score, rotarod test, Morris water maze test, and lesion volume measurements. In summary, our findings indicate that maraviroc might be a desirable pharmacotherapeutic strategy for TBI, and C-C chemokine receptor type 5 might be a promising pharmacotherapeutic target to improve recovery after TBI.

Stroke: Molecular mechanisms and therapies: Update on recent developments

Stroke, a neurological disease, is one of the leading causes of death worldwide, resulting in long-term disability in most survivors. Annual stroke costs in the United States alone were estimated at $46 billion recently. Stroke pathophysiology is complex, involving multiple causal factors, among which atherosclerosis, thrombus, and embolus are prevalent. The molecular mechanisms involved in the pathophysiology are essential to understanding targeted drug development. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress, and neuroinflammation. In addition, various modifiable and non-modifiable risk factors increase the chances of stroke manifolds. Once a patient encounters a stroke, complete restoration of motor ability and cognitive skills is often rare. Therefore, shaping therapeutic strategies is paramount for finding a viable therapeutic agent. Apart from tPA, an FDA-approved therapy that is applied in most stroke cases, many other therapeutic strategies have been met with limited success. Stroke therapies often involve a combination of multiple strategies to restore the patient's normal function. Certain drugs like Gamma-aminobutyric receptor agonists (GABA), Glutamate Receptor inhibitors, Sodium, and Calcium channel blockers, and fibrinogen-depleting agents have shown promise in stroke treatment. Recently, a drug, DM199, a recombinant (synthetic) form of a naturally occurring protein called human tissue kallikrein-1 (KLK1), has shown great potential in treating stroke with fewer side effects. Furthermore, DM199 has been found to overcome the limitations presented when using tPA and/or mechanical thrombectomy. Cell-based therapies like Neural Stem Cells, Hematopoietic stem cells (HSCs), and Human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) are also being explored as a treatment of choice for stroke. These therapeutic agents come with merits and demerits, but continuous research and efforts are being made to develop the best therapeutic strategies to minimize the damage post-stroke and restore complete neurological function in stroke patients.

m6A methylation: Critical roles in aging and neurological diseases

N6-methyladenosine (m6A) is the most abundant internal RNA modification in eukaryotic cells, which participates in the functional regulation of various biological processes. It regulates the expression of targeted genes by affecting RNA translocation, alternative splicing, maturation, stability, and degradation. As recent evidence shows, of all organs, brain has the highest abundance of m6A methylation of RNAs, which indicates its regulating role in central nervous system (CNS) development and the remodeling of the cerebrovascular system. Recent studies have shown that altered m6A levels are crucial in the aging process and the onset and progression of age-related diseases. Considering that the incidence of cerebrovascular and degenerative neurologic diseases increase with aging, the importance of m6A in neurological manifestations cannot be ignored. In this manuscript, we focus on the role of m6A methylation in aging and neurological manifestations, hoping to provide a new direction for the molecular mechanism and novel therapeutic targets.

Non-coding RNAs in stroke pathology, diagnostics, and therapeutics

Ischemic stroke is a leading cause of death and disability worldwide. Methods to alleviate functional deficits after ischemic stroke focus on restoration of cerebral blood flow to the affected area. However, pharmacological or surgical methods such as thrombolysis and thrombectomy have a narrow effective window. Harnessing and manipulating neurochemical processes of recovery may provide an alternative to these methods. Recently, non-coding RNA (ncRNA) have been increasingly investigated for their contributions to the pathology of diseases and potential for diagnostic and therapeutic applications. Here we will review several ncRNA - H19, MALAT1, ANRIL, NEAT1, pseudogenes, small nucleolar RNA, piwi-interacting RNA and circular RNA - and their involvement in stroke pathology. We also examine these ncRNA as potential diagnostic biomarkers, particularly in circulating blood, and as targets for therapeutic interventions. An important aspect of this is a discussion of potential methods of treatment delivery to allow for targeting of interventions past the blood-brain barrier, including lipid nanoparticles, polymer nanoparticles, and viral and non-viral vectors. Overall, several long non-coding RNA (lncRNA) discussed here have strong implications for the development of pathology and functional recovery after ischemic stroke. LncRNAs H19 and ANRIL show potential as diagnostic biomarkers, while H19 and MALAT1 may prove to be effective therapeutics for both minimising damage as well as promoting recovery. Other ncRNA have also been implicated in ischemic stroke but are currently too poorly understood to make inferences for diagnosis or treatment. Whilst the field of ncRNAs is relatively new, significant work has already highlighted that ncRNAs represent a promising novel investigative tool for understanding stroke pathology, could be used as diagnostic biomarkers, and as targets for therapeutic interventions.

Identification of co-expressed central genes and transcription factors in atherosclerosis-related intracranial aneurysm

Background

Numerous clinical studies have shown that atherosclerosis is one of the risk factors for intracranial aneurysms. Calcifications in the intracranial aneurysm walls are frequently correlated with atherosclerosis. However, the pathogenesis of atherosclerosis-related intracranial aneurysms remains unclear. This study aims to investigate this mechanism.

Methods

The Gene Expression Omnibus (GEO) database was used to download the gene expression profiles for atherosclerosis (GSE100927) and intracranial aneurysms (GSE75436). Following the identification of the common differentially expressed genes (DEGs) of atherosclerosis and intracranial aneurysm, the network creation of protein interactions, functional annotation, the identification of hub genes, and co-expression analysis were conducted. Thereafter, we predicted the transcription factors (TF) of hub genes and verified their expressions.

Results

A total of 270 common (62 downregulated and 208 upregulated) DEGs were identified for subsequent analysis. Functional analyses highlighted the significant role of phagocytosis, cytotoxicity, and T-cell receptor signaling pathways in this disease progression. Eight hub genes were identified and verified, namely, CCR5, FCGR3A, IL10RA, ITGAX, LCP2, PTPRC, TLR2, and TYROBP. Two TFs were also predicted and verified, which were IKZF1 and SPI1.

Conclusion

Intracranial aneurysms are correlated with atherosclerosis. We identified several hub genes for atherosclerosis-related intracranial aneurysms and explored the underlying pathogenesis. These discoveries may provide new insights for future experiments and clinical practice.

Transport of the Proinflammatory Chemokines C-C Motif Chemokine Ligand 2 (MCP-1) and C-C Motif Chemokine Ligand 5 (RANTES) across the Intact Mouse Blood-Brain Barrier Is Inhibited by Heparin and Eprodisate and Increased with Systemic Inflammation

One important function of the vascular blood-brain barrier (BBB) is to facilitate neuroimmune communication. The BBB fulfills this function, in part, through its ability to transport cytokines and chemokines. C-C motif chemokine receptor 2 (CCL2) (MCP-1) and C-C motif chemokine receptor 5 (CCL5) (RANTES) are proinflammatory chemokines that mediate neuroimmune responses to acute insults and aspects of brain injury and neurodegenerative diseases; however, a blood-to-brain transport system has not been evaluated for either chemokine in vivo. Therefore, we determined whether CCL2 and CCL5 in blood can cross the intact BBB and enter the brain. Using CD-1 mice, we found that ¹²⁵I-labeled CCL2 and CCL5 crossed the BBB and entered the brain parenchyma. We next aimed to identify the mechanisms of ¹²⁵I-CCL2 and ¹²⁵I-CCL5 transport in an in situ brain perfusion model. We found that both heparin and eprodisate inhibited brain uptake of ¹²⁵I-CCL2 and ¹²⁵I-CCL5 in situ, whereas antagonists of their receptors, CCR2 or CCR5, respectively, did not, suggesting that heparan sulfates at the endothelial surface mediate BBB transport. Finally, we showed that CCL2 and CCL5 transport across the BBB increased following a single injection of 0.3 mg/kg lipopolysaccharide. These data demonstrate that CCL2 and CCL5 in the brain can derive, in part, from the circulation, especially during systemic inflammation. Further, binding to the BBB-associated heparan sulfate is a mechanism by which both chemokines can cross the intact BBB, highlighting a novel therapeutic target for treating neuroinflammation. SIGNIFICANCE STATEMENT: Our work demonstrates that C-C motif chemokine ligand 2 (CCL2) and C-C motif chemokine ligand 5 (CCL5) can cross the intact blood-brain barrier and that transport is robustly increased during inflammation. These data suggest that circulating CCL2 and CCL5 can contribute to brain levels of each chemokine. We further show that the transport of both chemokines is inhibited by heparin and eprodisate, suggesting that CCL2/CCL5-heparan sulfate interactions could be therapeutically targeted to limit accumulation of these chemokines in the brain.

Targeting CCL5 signaling attenuates neuroinflammation after seizure

BACKGROUND

Epilepsy is a neurological condition that causes unprovoked, recurrent seizures. Accumulating evidence from clinical and experimental studies indicates that neuroinflammation exacerbates seizure activity.

METHODS

We investigated the transcriptional changes occurring in specific brain domains of a seizure mouse model, using 10× Genomics spatial transcriptomics. Differential gene expression and pathway analysis were applied to investigate potential signaling targets for seizure, including CCL5/CCR5 pathway. Maraviroc, an FDA-approved C-C chemokine receptor 5 (CCR5) antagonist, was used to verify the impact of CCL5/CCR5 signaling in seizure mice.

RESULTS

We found distinguished regional transcriptome features in the hippocampus of seizure mice. The hippocampus exhibited unique inflammatory gene signatures, including glia activation, apoptosis, and immune response in seizure mice. Especially, we observed notable expression of C-C chemokine ligand 5 (CCL5) throughout the entire seizure hippocampus. Blockade of CCL5/CCR5 signaling via maraviroc prevented microglia activation and neuron degeneration in seizure mice.

CONCLUSIONS

This study supports the potential of CCL5/CCR5 signaling for targeting neuroinflammation after seizure.

Multiscale imaging informs translational mouse modeling of neurological disease

Multiscale neurophysiology reveals that simple motor actions are associated with changes in neuronal firing in virtually every brain region studied. Accordingly, the assessment of focal pathology such as stroke or progressive neurodegenerative diseases must also extend widely across brain areas. To derive mechanistic information through imaging, multiple resolution scales and multimodal factors must be included, such as the structure and function of specific neurons and glial cells and the dynamics of specific neurotransmitters. Emerging multiscale methods in preclinical animal studies that span micro- to macroscale examinations fill this gap, allowing a circuit-based understanding of pathophysiological mechanisms. Combined with high-performance computation and open-source data repositories, these emerging multiscale and large field-of-view techniques include live functional ultrasound, multi- and single-photon wide-scale light microscopy, video-based miniscopes, and tissue-penetrating fiber photometry, as well as variants of post-mortem expansion microscopy. We present these technologies and outline use cases and data pipelines to uncover new knowledge within animal models of stroke, Alzheimer's disease, and movement disorders.

Osteopontin-integrin signaling positively regulates neuroplasticity through enhancing neural autophagy in the peri-infarct area after ischemic stroke

OBJECTIVE

To investigate the role of Osteopontin (OPN) in mediating macroautophagy, autophagy, and neuroplasticity in the ipsilateral hemisphere after stroke.

METHODS

Focal stroke was induced by photothrombosis in adult mice. Spatiotemporal expression of endogenous OPN and BECN1 was assessed by immunohistochemistry. Motor function was determined by the grid-walking and cylinder tasks. We also evaluated markers of neuroplasticity and autophagy using biochemical and histology analyses.

RESULTS

Herein, we showed that endogenous OPN and beclin1 were increased in the peri-infarct area of stroked patients and mice. Intracerebral administration of OPN (0.1 mg/ml; 3 ml) significantly improved performance in motor behavioral tasks compared with non-OPN-treated stroke mice. Furthermore, the neural repair was induced in OPN-treated stroke mice. We found that OPN treatment resulted in a significantly higher density of a presynaptic marker (vesicular glutamate transporter 1, VgluT1) and synaptic plasticity marker (synaptophysin, SYN) within the peri-infarct region. OPN treatment in stroke mice not only increased protein levels of integrin β1 but also promoted the expression of beclin1 and LC3, two autophagy-related proteins in the peri-infarct area. Additionally, OPN-induced neuroplasticity and autophagy were blocked by an integrin antagonist.

CONCLUSION

Our findings indicate that OPN may enhance neuroplasticity via autophagy, providing a new therapeutic strategy for ischemic stroke.

PDE2A Inhibition Enhances Axonal Sprouting, Functional Connectivity, and Recovery after Stroke

Phosphodiesterase (PDE) inhibitors have been safely and effectively used in the clinic and increase the concentration of intracellular cyclic nucleotides (cAMP/cGMP). These molecules activate downstream mediators, including the cAMP response element-binding protein (CREB), which controls neuronal excitability and growth responses. CREB gain of function enhances learning and allocates neurons into memory engrams. CREB also controls recovery after stroke. PDE inhibitors are linked to recovery from neural damage and to stroke recovery in specific sites within the brain. PDE2A is enriched in cortex. In the present study, we use a mouse cortical stroke model in young adult and aged male mice to test the effect of PDE2A inhibition on functional recovery, and on downstream mechanisms of axonal sprouting, tissue repair, and the functional connectivity of neurons in recovering cortex. Stroke causes deficits in use of the contralateral forelimb, loss of axonal projections in cortex adjacent to the infarct, and functional disconnection of neuronal networks. PDE2A inhibition enhances functional recovery, increases axonal projections in peri-infarct cortex, and, through two-photon in vivo imaging, enhances the functional connectivity of motor system excitatory neurons. PDE2A inhibition after stroke does not have an effect on other aspects of tissue repair, such as angiogenesis, gliogenesis, neurogenesis, and inflammatory responses. These data suggest that PDE2A inhibition is an effective therapeutic approach for stroke recovery in the rodent and that it simultaneously enhances connectivity in peri-infarct neuronal populations.SIGNIFICANCE STATEMENT Inhibition of PDE2A enhances motor recovery, axonal projections, and functional connectivity of neurons in peri-infarct tissue. This represents an avenue for a pharmacological therapy for stroke recovery.

Traumatic brain injury: progress and challenges in prevention, clinical care, and research

Traumatic brain injury (TBI) has the highest incidence of all common neurological disorders, and poses a substantial public health burden. TBI is increasingly documented not only as an acute condition but also as a chronic disease with long-term consequences, including an increased risk of late-onset neurodegeneration. The first Lancet Neurology Commission on TBI, published in 2017, called for a concerted effort to tackle the global health problem posed by TBI. Since then, funding agencies have supported research both in high-income countries (HICs) and in low-income and middle-income countries (LMICs). In November 2020, the World Health Assembly, the decision-making body of WHO, passed resolution WHA73.10 for global actions on epilepsy and other neurological disorders, and WHO launched the Decade for Action on Road Safety plan in 2021. New knowledge has been generated by large observational studies, including those conducted under the umbrella of the International Traumatic Brain Injury Research (InTBIR) initiative, established as a collaboration of funding agencies in 2011. InTBIR has also provided a huge stimulus to collaborative research in TBI and has facilitated participation of global partners. The return on investment has been high, but many needs of patients with TBI remain unaddressed. This update to the 2017 Commission presents advances and discusses persisting and new challenges in prevention, clinical care, and research.

In LMICs, the occurrence of TBI is driven by road traffic incidents, often involving vulnerable road users such as motorcyclists and pedestrians. In HICs, most TBI is caused by falls, particularly in older people (aged ≥65 years), who often have comorbidities. Risk factors such as frailty and alcohol misuse provide opportunities for targeted prevention actions. Little evidence exists to inform treatment of older patients, who have been commonly excluded from past clinical trials—consequently, appropriate evidence is urgently required. Although increasing age is associated with worse outcomes from TBI, age should not dictate limitations in therapy. However, patients injured by low-energy falls (who are mostly older people) are about 50% less likely to receive critical care or emergency interventions, compared with those injured by high-energy mechanisms, such as road traffic incidents.

Mild TBI, defined as a Glasgow Coma sum score of 13–15, comprises most of the TBI cases (over 90%) presenting to hospital. Around 50% of adult patients with mild TBI presenting to hospital do not recover to pre-TBI levels of health by 6 months after their injury. Fewer than 10% of patients discharged after presenting to an emergency department for TBI in Europe currently receive follow-up. Structured follow-up after mild TBI should be considered good practice, and urgent research is needed to identify which patients with mild TBI are at risk for incomplete recovery.

The selection of patients for CT is an important triage decision in mild TBI since it allows early identification of lesions that can trigger hospital admission or life-saving surgery. Current decision making for deciding on CT is inefficient, with 90–95% of scanned patients showing no intracranial injury but being subjected to radiation risks. InTBIR studies have shown that measurement of blood-based biomarkers adds value to previously proposed clinical decision rules, holding the potential to improve efficiency while reducing radiation exposure. Increased concentrations of biomarkers in the blood of patients with a normal presentation CT scan suggest structural brain damage, which is seen on MR scanning in up to 30% of patients with mild TBI. Advanced MRI, including diffusion tensor imaging and volumetric analyses, can identify additional injuries not detectable by visual inspection of standard clinical MR images. Thus, the absence of CT abnormalities does not exclude structural damage—an observation relevant to litigation procedures, to management of mild TBI, and when CT scans are insufficient to explain the severity of the clinical condition.

Although blood-based protein biomarkers have been shown to have important roles in the evaluation of TBI, most available assays are for research use only. To date, there is only one vendor of such assays with regulatory clearance in Europe and the USA with an indication to rule out the need for CT imaging for patients with suspected TBI. Regulatory clearance is provided for a combination of biomarkers, although evidence is accumulating that a single biomarker can perform as well as a combination. Additional biomarkers and more clinical-use platforms are on the horizon, but cross-platform harmonisation of results is needed. Health-care efficiency would benefit from diversity in providers.

In the intensive care setting, automated analysis of blood pressure and intracranial pressure with calculation of derived parameters can help individualise management of TBI. Interest in the identification of subgroups of patients who might benefit more from some specific therapeutic approaches than others represents a welcome shift towards precision medicine. Comparative-effectiveness research to identify best practice has delivered on expectations for providing evidence in support of best practices, both in adult and paediatric patients with TBI.

Progress has also been made in improving outcome assessment after TBI. Key instruments have been translated into up to 20 languages and linguistically validated, and are now internationally available for clinical and research use. TBI affects multiple domains of functioning, and outcomes are affected by personal characteristics and life-course events, consistent with a multifactorial bio-psycho-socio-ecological model of TBI, as presented in the US National Academies of Sciences, Engineering, and Medicine (NASEM) 2022 report. Multidimensional assessment is desirable and might be best based on measurement of global functional impairment. More work is required to develop and implement recommendations for multidimensional assessment. Prediction of outcome is relevant to patients and their families, and can facilitate the benchmarking of quality of care. InTBIR studies have identified new building blocks (eg, blood biomarkers and quantitative CT analysis) to refine existing prognostic models. Further improvement in prognostication could come from MRI, genetics, and the integration of dynamic changes in patient status after presentation.

Neurotrauma researchers traditionally seek translation of their research findings through publications, clinical guidelines, and industry collaborations. However, to effectively impact clinical care and outcome, interactions are also needed with research funders, regulators, and policy makers, and partnership with patient organisations. Such interactions are increasingly taking place, with exemplars including interactions with the All Party Parliamentary Group on Acquired Brain Injury in the UK, the production of the NASEM report in the USA, and interactions with the US Food and Drug Administration. More interactions should be encouraged, and future discussions with regulators should include debates around consent from patients with acute mental incapacity and data sharing. Data sharing is strongly advocated by funding agencies. From January 2023, the US National Institutes of Health will require upload of research data into public repositories, but the EU requires data controllers to safeguard data security and privacy regulation. The tension between open data-sharing and adherence to privacy regulation could be resolved by cross-dataset analyses on federated platforms, with the data remaining at their original safe location. Tools already exist for conventional statistical analyses on federated platforms, however federated machine learning requires further development. Support for further development of federated platforms, and neuroinformatics more generally, should be a priority.

This update to the 2017 Commission presents new insights and challenges across a range of topics around TBI: epidemiology and prevention (section 1 ); system of care (section 2 ); clinical management (section 3 ); characterisation of TBI (section 4 ); outcome assessment (section 5 ); prognosis (Section 6 ); and new directions for acquiring and implementing evidence (section 7 ). Table 1 summarises key messages from this Commission and proposes recommendations for the way forward to advance research and clinical management of TBI.

Roles of peripheral immune cells in the recovery of neurological function after ischemic stroke

Stroke is a leading cause of mortality and long-term disability worldwide, with limited spontaneous repair processes occurring after injury. Immune cells are involved in multiple aspects of ischemic stroke, from early damage processes to late recovery-related events. Compared with the substantial advances that have been made in elucidating how immune cells modulate acute ischemic injury, the understanding of the impact of the immune system on functional recovery is limited. In this review, we summarized the mechanisms of brain repair after ischemic stroke from both the neuronal and non-neuronal perspectives, and we review advances in understanding of the effects on functional recovery after ischemic stroke mediated by infiltrated peripheral innate and adaptive immune cells, immune cell-released cytokines and cell-cell interactions. We also highlight studies that advance our understanding of the mechanisms underlying functional recovery mediated by peripheral immune cells after ischemia. Insights into these processes will shed light on the double-edged role of infiltrated peripheral immune cells in functional recovery after ischemic stroke and provide clues for new therapies for improving neurological function.

Computational study of the structural ensemble of CC chemokine receptor type 5 (CCR5) and its interactions with different ligands

CC Chemokine receptor 5 (CCR5), a member of the Superfamily of G Protein-Coupled Receptors (GPCRs), is an important effector in multiple physiopathological processes such as inflammatory and infectious entities, including central nervous system neuroinflammatory diseases such as Alzheimer's disease, recovery from nervous injuries, and in the HIV-AIDS infective processes. Thus, CCR5 is an attractive target for pharmacological modulation. Since maraviroc was described as a CCR5 ligand that modifies the HIV-AIDS progression, multiple efforts have been developed to describe the functionality of the receptor. In this work, we characterized key structural features of the CCR5 receptor employing extensive atomistic molecular dynamics (MD) in its apo form and in complex with an endogenous agonist, the chemokine CCL5/RANTES, an HIV entry inhibitor, the partial inverse agonist maraviroc, and the experimental antagonists Compound 21 and 34, aiming to elucidate the structural features and mechanistic processes that constitute its functional states, contributing with structural details and a general understanding of this relevant system.

Cerebral ischemia in the developing brain

Brain ischemia affects all ages, from neonates to the elderly population, and is a leading cause of mortality and morbidity. Multiple preclinical rodent models involving different ages have been developed to investigate the effect of ischemia during different times of key brain maturation events. Traditional models of developmental brain ischemia have focused on rodents at postnatal day 7-10, though emerging models in juvenile rodents (postnatal days 17-25) indicate that there may be fundamental differences in neuronal injury and functional outcomes following focal or global cerebral ischemia at different developmental ages, as well as in adults. Here, we consider the timing of injury in terms of excitation/inhibition balance, oxidative stress, inflammatory responses, blood brain barrier integrity, and white matter injury. Finally, we review translational strategies to improve function after ischemic brain injury, including new ideas regarding neurorestoration, or neural repair strategies that restore plasticity, at delayed time points after ischemia.

Crossing nerve transfer drives sensory input-dependent plasticity for motor recovery after brain injury

Restoring limb movements after central nervous system injury remains a substantial challenge. Recent studies proved that crossing nerve transfer surgery could rebuild physiological connectivity between the contralesional cortex and the paralyzed arm to compensate for the lost function after brain injury. However, the neural mechanism by which this surgery mediates motor recovery remains still unclear. Here, using a clinical mouse model, we showed that this surgery can restore skilled forelimb function in adult mice with unilateral cortical lesion by inducing cortical remapping and promoting corticospinal tract sprouting. After reestablishing the ipsilateral descending pathway, resecting of the artificially rebuilt peripheral nerve did not affect motor improvements. Furthermore, retaining the sensory afferent, but not the motor efferent, of the transferred nerve was sufficient for inducing brain remapping and facilitating motor restoration. Thus, our results demonstrate that surgically rebuilt sensory input triggers neural plasticity for accelerating motor recovery, which provides an approach for treating central nervous system injuries.

CCL5 Levels Predict Stroke Volume Growth in Acute Ischemic Stroke and Significantly Diminish in Hemorrhagic Stroke Patients

Stroke remains an important health challenge. Here, we study whether circulating chemokine (C-C motif) ligand 5 (CCL5) levels may predict clinical outcomes for stroke patients. A total of 100 consecutive stroke patients (36 acute ischemic and 64 hemorrhagic) were admitted to the stroke unit. Clinical history data and monitoring parameters were recorded. Blood serum was collected at days 0, 1, and hospital discharge to measure CCL5 levels by ELISA. Infarct or hemorrhagic volume, neurological severity (NIHSS), and functional prognosis (mRankin scale) were measured as clinical outcomes. CCL5 levels were lower in patients with hemorrhagic stroke than in patients with acute ischemic stroke. No differences were found between females and males in both types of stroke. Ischemic stroke patients whose infarct volume grew had lower CCL5 levels at day 0. Levels of CCL5 in ischemic and hemorrhagic patients were not associated with more severe symptoms/worse prognosis (NIHSS > 3; mRankin > 2) at admission or at 3 months. CCL5 could be used as a diagnostic marker to distinguish between ischemic and hemorrhagic strokes. Furthermore, CCL5 levels could predict the infarct volume outcomes in ischemic patients.

Exercise modulates central and peripheral inflammatory responses and ameliorates methamphetamine-induced anxiety-like symptoms in mice

Anxiety-like symptoms are common symptoms of methamphetamine (METH) users, especially in the acute withdrawal period, which is an important factor for the high relapse rate during METH acute withdrawal. Exercise has been demonstrated to relieve anxiety-like symptoms during METH withdrawal, but the underlying mechanisms of this anti-anxiety effect are still unclear. Activated microglia and abnormal neuroinflammation play an important role in the pathogenesis of anxiety-like symptoms after METH withdrawal. Moreover, peripheral immune factors were also significantly associated with anxiety symptoms. However, the effects of treadmill exercise on microglial function and neuroinflammation in the striatum and hippocampus during acute METH withdrawal have not been reported. In the current study, we found severe peripheral immune dysfunction in METH users during acute withdrawal, which may in part contribute to anxiety symptoms during METH acute withdrawal. We also showed that 2 weeks of METH exposure induced anxiety-like symptoms in the acute withdrawal period. Additionally, METH exposure resulted in increased microglial activation and proinflammatory cytokines released in the mouse striatum and hippocampus during acute withdrawal. We next evaluated the effects of treadmill exercise in countering anxiety-like symptoms induced by METH acute withdrawal. The results showed that anxiety-like symptoms induced by acute METH withdrawal were attenuated by coadministration of treadmill exercise. In addition, treadmill exercise counteracted METH-induced microglial activation in the mouse striatum and various subregions of the hippocampus. Furthermore, treadmill exercise also reversed the increase in proinflammatory cytokines induced by acute METH withdrawal in the mouse striatum, hippocampus and serum. Our findings suggest that the anti-anxiety effect of treadmill exercise may be mediated by reducing microglial activation and regulating central and peripheral inflammatory responses.

New research tools suggest a “levels-less” image of the behaving organism and dissolution of the reduction vs. anti-reduction dispute

A kind of “ruthless reductionism” characterized the experimental practices of the first two decades of molecular and cellular cognition (MCC). More recently, new research tools have expanded experimental practices in this field, enabling researchers to image and manipulate individual molecular mechanisms in behaving organisms with an unprecedented temporal, sub-cellular, cellular, and even circuit-wide specificity. These tools dramatically expand the range and reach of experiments in MCC, and in doing so they may help us transcend the worn-out and counterproductive debates about “reductionism” and “emergence” that divide neuroscientists and philosophers alike. We describe examples of these new tools and illustrate their practical power by presenting an exemplary recent case of MCC research using them. From these tools and results, we provide an initial sketch of a new image of the behaving organism in its full causal-interactive complexity, with its molecules, cells, and circuits combined within the single system that it is. This new image stands in opposition to the traditional “levels” image of the behaving organism, and even the initial sketch we provide of it here offers hope for avoiding the dreary metaphysical debates about “emergence” and “downward causation,” and even the reduction vs. anti-reduction dispute, all dependent upon the familiar “levels” image.

The CCR5 antagonist maraviroc exerts limited neuroprotection without improving neurofunctional outcome in experimental pneumococcal meningitis

One-third of pneumococcal meningitis (PM) survivors suffer from neurological sequelae including learning disabilities and hearing loss due to excessive neuroinflammation. There is a lack of efficacious compounds for adjuvant therapy to control this long-term consequence of PM. One hallmark is the recruitment of leukocytes to the brain to combat the bacterial spread. However, this process induces excessive inflammation, causing neuronal injury. Maraviroc (MVC)—a CCR5 antagonist—was demonstrated to inhibit leukocyte recruitment and attenuate neuroinflammation in several inflammatory diseases. Here, we show that in vitro, MVC decreased nitric oxide production in astroglial cells upon pneumococcal stimulation. In vivo, infant Wistar rats were infected with 1 × 10⁴ CFU/ml S. pneumoniae and randomized for treatment with ceftriaxone plus MVC (100 mg/kg) or ceftriaxone monotherapy. During the acute phase, neuroinflammation in the CSF was measured and histopathological analyses were performed to determine neuronal injury. Long-term neurofunctional outcome (learning/memory and hearing capacity) after PM was assessed. MVC treatment reduced hippocampal cell apoptosis but did not affect CSF neuroinflammation and the neurofunctional outcome after PM. We conclude that MVC treatment only exerted limited effect on the pathophysiology of PM and is, therefore, not sufficiently beneficial in this experimental paradigm of PM.

A Novel In Vivo Model for Multiplexed Analysis of Callosal Connections upon Cortical Damage

Brain damage is the major cause of permanent disability and it is particularly relevant in the elderly. While most studies focused on the immediate phase of neuronal loss upon injury, much less is known about the process of axonal regeneration after damage. The development of new refined preclinical models to investigate neuronal regeneration and the recovery of brain tissue upon injury is a major unmet challenge. Here, we present a novel experimental paradigm in mice that entails the (i) tracing of cortico-callosal connections, (ii) a mechanical lesion of the motor cortex, (iii) the stereological and histological analysis of the damaged tissue, and (iv) the functional characterization of motor deficits. By combining conventional microscopy with semi-automated 3D reconstruction, this approach allows the analysis of fine subcellular structures, such as axonal terminals, with the tridimensional overview of the connectivity and tissue integrity around the lesioned area. Since this 3D reconstruction is performed in serial sections, multiple labeling can be performed by combining diverse histological markers. We provide an example of how this methodology can be used to study cellular interactions. Namely, we show the correlation between active microglial cells and the perineuronal nets that envelop parvalbumin interneurons. In conclusion, this novel experimental paradigm will contribute to a better understanding of the molecular and cellular interactions underpinning the process of cortical regeneration upon brain damage.

Methods for culturing adult CNS neurons reveal a CNS conditioning effect

Neuronal cultures provide a basis for reductionist insights that rely on molecular and pharmacological manipulation. However, the inability to culture mature adult CNS neurons limits our understanding of adult neuronal physiology. Here, we report methods for culturing adult central nervous system neurons in large numbers and across multiple brain regions for extended time periods. Primary adult neuronal cultures develop polarity; they establish segregated dendritic and axonal compartments, maintain resting membrane potentials, exhibit spontaneous and evoked electrical activity, and form neural networks. Cultured adult neurons isolated from different brain regions such as the hippocampus, cortex, brainstem, and cerebellum exhibit distinct cell morphologies, growth patterns, and spontaneous firing characteristics reflective of their regions of origin. Using adult motor cortex cultures, we identify a CNS "conditioning" effect after spinal cord injury. The ability to culture adult neurons offers a valuable tool for studying basic and therapeutic science of the brain.

Metabolism regulator adiponectin prevents cardiac remodeling and ventricular arrhythmias via sympathetic modulation in a myocardial infarction model

The stellate ganglia play an important role in cardiac remodeling after myocardial infarction (MI). This study aimed to investigate whether adiponectin (APN), an adipokine mainly secreted by adipose tissue, could modulate the left stellate ganglion (LSG) and exert cardioprotective effects through the sympathetic nervous system (SNS) in a canine model of MI. APN microinjection and APN overexpression with recombinant adeno-associated virus vector in the LSG were performed in acute and chronic MI models, respectively. The results showed that acute APN microinjection decreased LSG function and neural activity, and suppressed ischemia-induced ventricular arrhythmia. Chronic MI led to a decrease in the effective refractory period and action potential duration at 90% and deterioration in echocardiography performance, all of which was blunted by APN overexpression. Moreover, APN gene transfer resulted in favorable heart rate variability alteration, and decreased cardiac SNS activity, serum noradrenaline and neuropeptide Y, which were augmented after MI. APN overexpression also decreased the expression of nerve growth factor and growth associated protein 43 in the LSG and peri-infarct myocardium, respectively. Furthermore, RNA sequencing of LSG indicated that 4-week MI up-regulated the mRNA levels of macrophage/microglia activation marker Iba1, chemokine ligands (CXCL10, CCL20), chemokine receptor CCR5 and pro-inflammatory cytokine IL6, and downregulated IL1RN and IL10 mRNA, which were reversed by APN overexpression. Our results reveal that APN inhibits cardiac sympathetic remodeling and mitigates cardiac remodeling after MI. APN-mediated gene therapy may provide a potential therapeutic strategy for the treatment of MI.

Pregabalin improves axon regeneration and motor outcome in a rodent stroke model

Ischaemic stroke remains a leading cause of death and disability worldwide. Surviving neurons in the peri-infarct area are able to establish novel axonal projections to juxtalesional regions, but this regeneration is curtailed by a growth-inhibitory environment induced by cells such as reactive astrocytes in the glial scar. Here, we found that the astroglial synaptogenic cue thrombospondin-1 is upregulated in the peri-infarct area, and hence tested the effects of the anticonvulsant pregabalin, a blocker of the neuronal thrombospondin-1 receptor Alpha2delta1/2, in a mouse model of cortical stroke. Studying axonal projections after cortical stroke in mice by three-dimensional imaging of cleared whole-brain preparations, we found that pregabalin, when administered systemically for 5 weeks after stroke, augments novel peri-infarct motor cortex projections and improves skilled forelimb motor function. Thus, the promotion of axon elongation across the glial scar by pregabalin represents a promising target beyond the acute phase after stroke to improve structural and functional recovery.

The role of CCR5 in HIV-associated neurocognitive disorders

While combination antiretroviral therapy (cART) has successfully increased the lifespan of individuals infected with HIV, a significant portion of this population remains affected by HIV-associated neurocognitive disorder (HAND). C-C chemokine receptor 5 (CCR5) has been well studied in immune response and as a co-receptor for HIV infection. HIV-infected (HIV⁺) patients experienced mild to significant amelioration of cognitive function when treated with different CCR5 antagonists, including maraviroc and cenicriviroc. Consistent with clinical results, Ccr5 knockout or knockdown rescued cognitive deficits in HIV animal models, with mechanisms of reduced microgliosis and neuroinflammation. Pharmacologic inhibition of CCR5 directly improved cerebral and hippocampal neuronal plasticity and cognitive function. By summarizing the animal and human studies of CCR5 in HIV-associated cognitive deficits, this review aims to provide an overview of the mechanistic role of CCR5 in HAND pathophysiology. This review also discusses the addition of CCR5 antagonists, such as maraviroc, to cART for targeted prevention and treatment of cognitive impairments in patients infected with HIV.

Deep Phenotyping of T-Cells Derived From the Aneurysm Wall in a Pediatric Case of Subarachnoid Hemorrhage

Intracranial aneurysms (IAs) are very rare in children, and the characteristics of the T-cells in the IA wall are largely unknown. A comatose 7-years-old child was admitted to our center because of a subarachnoid hemorrhage due to a ruptured giant aneurysm of the right middle cerebral artery. Two days after the aneurysm clipping the patient was fully awake with left hemiparesis. T-cells from the IA wall and from peripheral blood of this patient were analyzed by multi-dimensional flow cytometry. Unbiased analysis, based on the use of FlowSOM clustering and dimensionality reduction technique UMAP, indicated that there was virtually no overlap between circulating and tissue-infiltrating T-cells. Thus, naïve T-cells and canonical memory T-cells were largely restricted to peripheral blood, while CD4^-CD8^-T-cells were strongly enriched in the IA wall. The unique CD4⁺, CD8⁺ and CD4^-CD8^-T-cell clusters from the IA wall expressed high levels of CCR5, Granzyme B and CD69, displaying thus characteristics of cytotoxic and tissue-resident effector cells. Low Ki67 expression indicated that they were nevertheless in a resting state. Among regulatory T-cell subsets, Eomes⁺Tr1-like cells were strongly enriched in the IA wall. Finally, analysis of cytokine producing capacities unveiled that the IA wall contained poly-functional T-cells, which expressed predominantly IFN-γ, TNF and IL-2. CD4⁺T-cells co-expressed also CD40L, and produced some IL-17, GM-CSF and IL-10. This report provides to our knowledge the first detailed characterization of the human T-cell compartment in the IA wall.