Genetics of stroke recovery: BDNF val66met polymorphism in stroke recovery and its interaction with aging

Role of Brain Derived Neurotrophic Factor and Related Therapeutic Strategies in Central Post-Stroke Pain

Brain-derived neurotrophic factor (BDNF) is vital for synaptic plasticity, cell persistence, and neuronal development in peripheral and central nervous systems (CNS). Numerous intracellular signalling pathways involving BDNF are well recognized to affect neurogenesis, synaptic function, cell viability, and cognitive function, which in turn affects pathological and physiological aspects of neurons. Stroke has a significant psycho-socioeconomic impact globally. Central post-stroke pain (CPSP), also known as a type of chronic neuropathic pain, is caused by injury to the CNS following a stroke, specifically damage to the somatosensory system. BDNF regulates a broad range of functions directly or via its biologically active isoforms, regulating multiple signalling pathways through interactions with different types of receptors. BDNF has been shown to play a major role in facilitating neuroplasticity during post-stroke recovery and a pro-nociceptive role in pain development in the nervous system. BDNF-tyrosine kinase receptors B (TrkB) pathway promotes neurite outgrowth, neurogenesis, and the prevention of apoptosis, which helps in stroke recovery. Meanwhile, BDNF overexpression plays a role in CPSP via the activation of purinergic receptors P2X4R and P2X7R. The neuronal hyperexcitability that causes CPSP is linked with BDNF-TrkB interactions, changes in ion channels and inflammatory reactions. This review provides an overview of BDNF synthesis, interactions with certain receptors, and potential functions in regulating signalling pathways associated with stroke and CPSP. The pathophysiological mechanisms underlying CPSP, the role of BDNF in CPSP, and the challenges and current treatment strategies targeting BDNF are also discussed.

The cerebroprotection and prospects of FNDC5/irisin in stroke

Stroke, the leading cause of disability and cognitive impairment, is also the second leading cause of death worldwide. The drugs with multi-targeted brain cytoprotective effects are increasingly being advocated for the treatment of stroke. Irisin, a newly discovered myokine produced by cleavage of fibronectin type III domain 5, has been shown to regulate glucose metabolism, mitochondrial energy, and fat browning. A large amount of evidence indicated that irisin could exert anti-inflammatory, anti-apoptotic, and antioxidant properties in a variety of diseases such as myocardial infarction, inflammatory bowel disease, lung injury, and kidney or liver disease. Studies have found that irisin is widely distributed in multiple brain regions and also plays an important regulatory role in the central nervous system. The most common cause of a stroke is a sudden blockage of an artery (ischemic stroke), and in some circumstances, a blood vessel rupture can also result in a stroke (hemorrhagic stroke). After a stroke, complicated pathophysiological processes lead to serious brain injury and neurological dysfunction. According to recent investigations, irisin may protect elements of the neurovascular unit by acting on multiple pathological processes in stroke. This review aims to outline the currently recognized effects of irisin on stroke and propose possible directions for future research.

Genetic polymorphisms and post-stroke upper limb motor improvement - A systematic review and meta-analysis

Background

Post-stroke upper limb (UL) motor improvement is associated with adaptive neuroplasticity and motor learning. Both intervention-related (including provision of intensive, variable, and task-specific practice) and individual-specific factors (including the presence of genetic polymorphisms) influence improvement. In individuals with stroke, most commonly, polymorphisms are found in Brain Derived Neurotrophic Factor (BDNF), Apolipoprotein (APOE) and Catechol-O-Methyltransferase (COMT). These involve a replacement of cystine by arginine (APOEε4) or valines by 1 or 2 methionines (BDNF:val66met, met66met; COMT:val158met; met158met). However, the implications of these polymorphisms on post-stroke UL motor improvement specifically have not yet been elucidated.

Objective

Examine the influence of genetic polymorphism on post-stroke UL motor improvement.

Design

Systematic Review and Meta-Analysis.

Methods

We conducted a systematic search of the literature published in English language. The modified Downs and Black checklist helped assess study quality. We compared change in UL motor impairment and activity scores between individuals with and without the polymorphisms. Meta-analyses helped assess change in motor impairment (Fugl Meyer Assessment) scores based upon a minimum of 2 studies/time point. Effect sizes (ES) were quantified based upon the Rehabilitation Treatment Specification System as follows: small (0.08-0.18), medium (0.19 -0.40) and large (≥0.41).

Results

We retrieved 10 (4 good and 6 fair quality) studies. Compared to those with BDNF val66met and met66met polymorphism, meta-analyses revealed lower motor impairment (large ES) in those without the polymorphism at intervention completion (0.5, 95% CI: 0.11-0.88) and at retention (0.58, 95% CI:0.06-1.11). The presence of CoMT val158met or met158met polymorphism had similar results, with lower impairment (large ES ≥1.5) and higher activity scores (large ES ranging from 0.5-0.76) in those without the polymorphism. Presence of APOEε4 form did not influence UL motor improvement.

Conclusion

Polymorphisms with the presence of 1 or 2 met alleles in BDNF and COMT negatively influence UL motor improvement.

Registration

https://osf.io/wk9cf/.

Improving physical movement during stroke rehabilitation: investigating associations between sleep measured by wearable actigraphy technology, fatigue, and key biomarkers

BACKGROUND

Sleep disturbance and fatigue are common in individuals undergoing inpatient rehabilitation following stroke. Understanding the relationships between sleep, fatigue, motor performance, and key biomarkers of inflammation and neuroplasticity could provide valuable insight into stroke recovery, possibly leading to personalized rehabilitation strategies. This study aimed to investigate the influence of sleep quality on motor function following stroke utilizing wearable technology to obtain objective sleep measurements. Additionally, we aimed to determine if there were relationships between sleep, fatigue, and motor function. Lastly, the study aimed to determine if salivary biomarkers of stress, inflammation, and neuroplasticity were associated with motor function or fatigue post-stroke.

METHODS

Eighteen individuals who experienced a stroke and were undergoing inpatient rehabilitation participated in a cross-sectional observational study. Following consent, participants completed questionnaires to assess sleep patterns, fatigue, and quality of life. Objective sleep was measured throughout one night using the wearable Philips Actiwatch. Upper limb motor performance was assessed on the following day and saliva was collected for biomarker analysis. Correlation analyses were performed to assess the relationships between variables.

RESULTS

Participants reported poor sleep quality, frequent awakenings, and difficulties falling asleep following stroke. We identified a significant negative relationship between fatigue severity and both sleep quality (r=-0.539, p = 0.021) and participants experience of awakening from sleep (r=-0.656, p = 0.003). A significant positive relationship was found between grip strength on the non-hemiplegic limb and salivary gene expression of Brain-derived Neurotrophic Factor (r = 0.606, p = 0.028), as well as a significant negative relationship between grip strength on the hemiplegic side and salivary gene expression of C-reactive Protein (r=-0.556, p = 0.048).

CONCLUSION

The findings of this study emphasize the importance of considering sleep quality, fatigue, and biomarkers in stroke rehabilitation to optimize recovery and that interventions may need to be tailored to the individual. Future longitudinal studies are required to explore these relationships over time. Integrating wearable technology for sleep and biomarker analysis can enhance monitoring and prediction of outcomes following stroke, ultimately improving rehabilitation strategies and patient outcomes.

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

Considering the response in addition to the challenge - a narrative review in appraisal of a motor reserve framework

The remarkable increase in human life expectancy over the past century has been achieved at the expense of the risk of age-related impairment and disease. Neurodegeneration, be it part of normal aging or due to neurodegenerative disorders, is characterized by loss of specific neuronal populations, leading to increasing clinical impairment. The individual course may be described as balance between aging- or disease-related pathology and intrinsic mechanisms of adaptation. There is plenty of evidence that the human brain is provided with exhaustible resources to maintain function in the face of adverse conditions. While a reserve concept has mainly been coined in cognitive neuroscience, emerging evidence suggests similar mechanisms to underlie individual differences of adaptive capacity within the motor system. In this narrative review, we summarize what has been proposed to date about a motor reserve (mR) framework. We present current evidence from research in aging subjects and people with neurological conditions, followed by a description of what is known about potential neuronal substrates of mR so far. As there is no gold standard of mR quantification, we outline current approaches which describe various indicators of mR. We conclude by sketching out potential future directions of research. Expediting our understanding of differences in individual motor resilience towards aging and disease will eventually contribute to new, individually tailored therapeutic strategies. Provided early diagnosis, enhancing the individual mR may be suited to postpone disease onset by years and may be an efficacious contribution towards healthy aging, with an increased quality of life for the elderly.

Periplaneta Americana (L.) extract activates the ERK/CREB/BDNF pathway to promote post-stroke neuroregeneration and recovery of neurological functions in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Periplaneta americana (L.) (PA) has been used in traditional Chinese medicine for thousands of years for the effect of invigorating blood circulation and removing blood stasis. Modern pharmacological research shown that PA extract exhibits promising effects in promoting wound healing and regeneration, as well as in brain diseases such as Parkinson's disease (PD). However, whether it is effective for neuroregeneration and neurological function recovery after stroke still unknown.

AIM OF THE STUDY

This study aims to investigate the potential effect of PA extract to promote brain remodeling through the activation of endogenous neurogenesis and angiogenesis, in addition, preliminary exploration of its regulatory mechanism.

METHODS

Firstly, BrdU proliferation assay and immunofluorescence (IF) staining were used to evaluate the effect of PA extract on the neurogenesis and angiogenesis in vitro and in vivo. Subsequently, the effects of PA extract on brain injury in stroke rats were assessed by TTC and HE. While mNSS score, adhesive removal test, rota-rod test, and morris water maze test were used to assess the impact of PA extract on neurological function in post-stroke rats. Finally, the molecular mechanisms of PA extract regulation were explored by RNA-Seq and western blotting.

RESULTS

The number of BrdU+ cells in C17.2 cells, NSCs and BMECs dramatically increased, as well as the expression of astrocyte marker protein GFAP and neuronal marker protein Tuj-1 in C17.2 and NSCs. Moreover, PA extract also increased the number of BrdU+DCX+, BrdU+GFAP+, BrdU+CD31+ cells in the SGZ area of transient middle cerebral artery occlusion model (tMCAO) rats. TTC and HE staining revealed that PA extract significantly reduced the infarction volume and ameliorated the pathological damage. Behavioral tests demonstrated that treatment with PA extract reduced the mNSS score and the time required to remove adhesive tape, while increasing the time spent on the rotarod. Additionally, in the morris water maze test, the frequency of crossing platform and the time spent in the platform quadrant increased. Finally, RNA-Seq and Western blot revealed that PA extract increased the expression of p-ERK, p-CREB and BDNF. Importantly, PA extract mediated proliferation and differentiation of C17.2 and NSCs reversed by the ERK inhibitor SCH772984 and the BDNF inhibitor ANA-12, respectively.

CONCLUSION

Our study demonstrated that PA extract promoted neurogenesis and angiogenesis by activating the CREB/ERK signaling pathway and upregulating BDNF expression, thereby recovering neurological dysfunction in post-stroke.

Interactions between tDCS treatment and COMT Val158Met in poststroke cognitive impairment

OBJECTIVE

This study aimed to explore the effect of catechol-O-methyltransferase (COMT) Val158Met and brain-derived neurotrophic factor (BDNF) Val66Met to post-stroke cognitive impairment (PSCI) and the interaction with transcranial direct current stimulation (tDCS).

METHODS

Seventy-six patients with PSCI were randomly assigned to Group (1) (n = 38) to receive anodal tDCS of left dorsolateral prefrontal cortex or Group (2) (n = 38) to receive sham stimulation. The intensity of the tDCS was 2 mA, and the stimulations were applied over the left DLPFC for 10 sessions. The Montreal Cognitive Assessment (MoCA) and backward digit span test (BDST) were assessed before, immediately after, and one month after stimulation.

RESULTS

After stimulation, patients in the tDCS group showed better improvement in both MoCA and BDST than those in the sham group. The results of GLMs also supported the main effects of tDCS on general cognitive function and working memory. Then we found that COMT genotype may have a main effect on the improvement of MoCA and BDST, and there may be an interaction between COMT genotype and tDCS in enhancing BDST. In contrast, BDNF genotype showed no significant main or interaction effects on any scales.

CONCLUSIONS

These findings demonstrate that tDCS can improve cognition after stroke. Gene polymorphisms of COMT can affect the efficacy of tDCS on PSCI, but BDNF may not.

SIGNIFICANCE

This study found that COMT Val158Met has an interaction on the efficacy of prefrontal tDCS in cognitive function, which provides reference for future tDCS research and clinical application.

Exploring the Neuroprotective Effects of Lithium in Ischemic Stroke: A literature review

Ischemic stroke ranks among the foremost clinical causes of mortality and disability, instigating neuronal degeneration, fatalities, and various sequelae. While standard treatments, such as intravenous thrombolysis and endovascular thrombectomy, prove effective, they come with limitations. Hence, there is a compelling need to develop neuroprotective agents capable of improving the functional outcomes of the nervous system. Numerous preclinical studies have demonstrated that lithium can act in multiple molecular pathways, including glycogen synthase kinase 3(GSK-3), the Wnt signaling pathway, the mitogen-activated protein kinase (MAPK)/ extracellular signal-regulated kinase (ERK) signaling pathway, brain-derived neurotrophic factor (BDNF), mammalian target of rapamycin (mTOR), and glutamate receptors. Through these pathways, lithium has been shown to affect inflammation, autophagy, apoptosis, ferroptosis, excitotoxicity, and other pathological processes, thereby improving central nervous system (CNS) damage caused by ischemic stroke. Despite these promising preclinical findings, the number of clinical trials exploring lithium's efficacy remains limited. Additional trials are imperative to thoroughly ascertain the effectiveness and safety of lithium in clinical settings. This review delineates the mechanisms underpinning lithium's neuroprotective capabilities in the context of ischemic stroke. It elucidates the intricate interplay between these mechanisms and sheds light on the involvement of mitochondrial dysfunction and inflammatory markers in the pathophysiology of ischemic stroke. Furthermore, the review offers directions for future research, thereby advancing the understanding of the potential therapeutic utility of lithium and establishing a theoretical foundation for its clinical application.

Drivers of Chronic Pathology Following Ischemic Stroke: A Descriptive Review

Stroke is the third leading cause of death and long-term disability in the world. Considered largely a disease of aging, its global economic and healthcare burden is expected to rise as more people survive into advanced age. With recent advances in acute stroke management, including the expansion of time windows for treatment with intravenous thrombolysis and mechanical thrombectomy, we are likely to see an increase in survival rates. It is therefore critically important to understand the complete pathophysiology of ischemic stroke, both in the acute and subacute stages and during the chronic phase in the months and years following an ischemic event. One of the most clinically relevant aspects of the chronic sequelae of stroke is its extended negative effect on cognition. Cognitive impairment may be related to the deterioration and dysfunctional reorganization of white matter seen at later timepoints after stroke, as well as ongoing progressive neurodegeneration. The vasculature of the brain also undergoes significant insult and remodeling following stroke, undergoing changes which may further contribute to chronic stroke pathology. While inflammation and the immune response are well established drivers of acute stroke pathology, the chronicity and functional role of innate and adaptive immune responses in the post-ischemic brain and in the peripheral environment remain largely uncharacterized. In this review, we summarize the current literature on post-stroke injury progression, its chronic pathological features, and the putative secondary injury mechanisms underlying the development of cognitive impairment and dementia. We present findings from clinical and experimental studies and discuss the long-term effects of ischemic stroke on both brain anatomy and functional outcome. Identifying mechanisms that occur months to years after injury could lead to treatment strategies in the chronic phase of stroke to help mitigate stroke-associated cognitive decline in patients.

Genetic Variations and Altered Blood mRNA Level of Circadian Genes and BDNF as Risk Factors of Post-Stroke Cognitive Impairment Among Eastern Indians

Post-stroke cognitive impairment (PSCI) is a clinical outcome in around 30% of post-stroke survivors. BDNF is a major gene in this regard. It is regulated by circadian rhythm. The circadian genes are correlated with stroke timings at molecular level. However, studies suggesting the role of these on susceptibility to PSCI are limited. We aim here to determine: (a) genetic risk variants in circadian clock genes, BDNF and (b) dysregulation in expression level of CLOCK, BMAL1, and BDNF that may be associated with PSCI. BDNF (rs6265G/A, rs56164415C/T), CLOCK (rs1801260T/C, rs4580704G/C), and CRY2 (rs2292912C/G) genes variants were genotyped among 119 post-stroke survivors and 292 controls from Eastern part of India. In addition, we analyzed their gene expression in Peripheral blood Mononuclear cells (PBMC) from 15 PSCI cases and 12 controls. The mRNA data for BDNF was further validated by its plasma level through ELISA (n = 38). Among the studied variants, only rs4580704/CLOCK showed an overall association with PSCI (P = 0.001) and lower Bengali Mini-Mental State Examination (BMSE) score. Its 'C' allele showed a correlation with attention deficiency. The language and memory impairments showed association with rs6265/BDNF, while the 'CC' genotype of rs2292912/CRY2 negatively influenced language and executive function. A significant decrease in gene expression for CLOCK and BDNF in PBMC (influenced by specific genotypes) of PSCI patients was observed than controls. Unlike Pro-BDNF, plasma-level mBDNF was also lower in them. Our results suggest the genetic variants in CLOCK, CRY2, and BDNF as risk factors for PSCI among eastern Indians. At the same time, a lowering expression of CLOCK and BDNF genes in PSCI patients than controls describes their transcriptional dysregulation as underlying mechanism for post-stroke cognitive decline.

Brain-derived neurotrophic factor Val66Met and neuropsychological functioning after early childhood traumatic brain injury

OBJECTIVE

The present study examined the differential effect of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism on neuropsychological functioning in children with traumatic brain injury (TBI) relative to orthopedic injury (OI).

METHODS

Participants were drawn from a prospective, longitudinal study of children who sustained a TBI (n = 69) or OI (n = 72) between 3 and 7 years of age. Children completed a battery of neuropsychological measures targeting attention, memory, and executive functions at four timepoints spanning the immediate post-acute period to 18 months post-injury. Children also completed a comparable age-appropriate battery of measures approximately 7 years post-injury. Parents rated children's dysexecutive behaviors at all timepoints.

RESULTS

Longitudinal mixed models revealed a significant allele status × injury group interaction with a medium effect size for verbal fluency. Cross-sectional models at 7 years post-injury revealed non-significant but medium effect sizes for the allele status x injury group interaction for fluid reasoning and immediate and delayed verbal memory. Post hoc stratified analyses revealed a consistent pattern of poorer neuropsychological functioning in Met carriers relative to Val/Val homozygotes in the TBI group, with small effect sizes; the opposite trend or no appreciable effect was observed in the OI group.

CONCLUSIONS

The results suggest a differential effect of the BDNF Val66Met polymorphism on verbal fluency, and possibly fluid reasoning and immediate and delayed verbal memory, in children with early TBI relative to OI. The Met allele-associated with reduced activity-dependent secretion of BDNF-may confer risk for poorer neuropsychological functioning in children with TBI.

Neutrophil Heterogeneity and its Roles in the Inflammatory Network after Ischemic Stroke

As the first peripheral immune cells to enter the brain after ischemic stroke, neutrophils are important participants in stroke-related neuroinflammation. Neutrophils are quickly mobilized from the periphery in response to a stroke episode and cross the blood-brain barrier to reach the ischemic brain parenchyma. This process involves the mobilization and activation of neutrophils from peripheral immune organs (including the bone marrow and spleen), their chemotaxis in the peripheral blood, and their infiltration into the brain parenchyma (including disruption of the blood-brain barrier, inflammatory effects on brain tissue, and interactions with other immune cell types). In the past, it was believed that neutrophils aggravated brain injuries through the massive release of proteases, reactive oxygen species, pro-inflammatory factors, and extracellular structures known as neutrophil extracellular traps (NETs). With the failure of early clinical trials targeting neutrophils and uncovering their underlying heterogeneity, our view of their role in ischemic stroke has become more complex and multifaceted. As neutrophils can be divided into N1 and N2 phenotypes in tumors, neutrophils have also been found to have similar phenotypes after ischemic stroke, and play different roles in the development and prognosis of ischemic stroke. N1 neutrophils are dominant during the acute phase of stroke (within three days) and are responsible for the damage to neural structures via the aforementioned mechanisms. However, the proportion of N2 neutrophils gradually increases in later phases, and this has a beneficial effect through the release of anti-inflammatory factors and other neuroprotective mediators. Moreover, the N1 and N2 phenotypes are highly plastic and can be transformed into each other under certain conditions. The pronounced differences in their function and their high degree of plasticity make these neutrophil subpopulations promising targets for the treatment of ischemic stroke.

Home-based portable fNIRS-derived cortical laterality correlates with impairment and function in chronic stroke

Introduction

Improved understanding of the relationship between post-stroke rehabilitation interventions and functional motor outcomes could result in improvements in the efficacy of post-stroke physical rehabilitation. The laterality of motor cortex activity (M1-LAT) during paretic upper-extremity movement has been documented as a useful biomarker of post-stroke motor recovery. However, the expensive, labor intensive, and laboratory-based equipment required to take measurements of M1-LAT limit its potential clinical utility in improving post-stroke physical rehabilitation. The present study tested the ability of a mobile functional near-infrared spectroscopy (fNIRS) system (designed to enable independent measurement by stroke survivors) to measure cerebral hemodynamics at the motor cortex in the homes of chronic stroke survivors.

Methods

Eleven chronic stroke survivors, ranging widely in their level of upper-extremity motor deficit, used their stroke-affected upper-extremity to perform a simple unilateral movement protocol in their homes while a wireless prototype fNIRS headband took measurements at the motor cortex. Measures of participants' upper-extremity impairment and function were taken.

Results

Participants demonstrated either a typically lateralized response, with an increase in contralateral relative oxyhemoglobin (ΔHbO), or response showing a bilateral pattern of increase in ΔHbO during the motor task. During the simple unilateral task, M1-LAT correlated significantly with measures of both upper-extremity impairment and function, indicating that participants with more severe motor deficits had more a more atypical (i.e., bilateral) pattern of lateralization.

Discussion

These results indicate it is feasible to gain M1-LAT measures from stroke survivors in their homes using fNIRS. These findings represent a preliminary step toward the goals of using ergonomic functional neuroimaging to improve post-stroke rehabilitative care, via the capture of neural biomarkers of post-stroke motor recovery, and/or via use as part of an accessible rehabilitation brain-computer-interface.

Emotional and qualitative outcomes among patients with left and right hemisphere stroke

The differences in mental health outcomes of right and left hemisphere strokes are well studied; however, there is a long-standing controversy surrounding whether depression is associated with lateralization of stroke or not. In this investigation, we examined the effect of lesion location on post-stroke depression controlling for lesion size and hemiparesis in a longitudinal sample assessed at acute, subacute, and chronic timepoints. As a secondary aim, we further examined the effect of lesion location on self-reported difficulties across a wide array of domains. A series of 134 patients with left hemisphere strokes and 79 with right hemisphere strokes completed the Patient Health Questionnaire-9 and an inventory of post-stroke abilities at within acute, subacute, and chronic windows following stroke. When controlling for hemiparesis and overall lesion volume, we found no difference in depression between groups at any timepoint. Additional exploratory analyses provided a further look at differing challenges associated with depression in each group.

Transcriptomic Profiling of Electroacupuncture Regulating the Molecular Network in Hippocampus of Rats with Cerebral Ischemia-Reperfusion Injury

Objective. To explore the mechanism of electroacupuncture stimulation of the hand-taiyin meridian in regulating the molecular network of rats with cerebral ischemia-reperfusion injury based on transcriptomics. Methods. Male SD rats were randomly divided into sham operation group, model group, and electroacupuncture (EA) group. Middle cerebral artery embolization/reperfusion injury (MCAO/R) was used to establish the model group and EA group. The sham operation group only performed sham operation without modeling and any intervention, and the model group was bound daily. The EA group received electroacupuncture to stimulate the acupoints of hand-taiyin meridian for 14 days. Then, neurological scores, pathomorphological observations, and Tunel staining were performed. Finally, the affected hippocampus of the rat was used for transcriptome sequencing and RT-PCR detection. Results. After electroacupuncture intervention in rats, neurological function scores were improved, and neuronal apoptosis was reduced. The results of transcriptomics showed that a total of 1097 differentially expressed genes were obtained, of which 422 were upregulated and 675 were downregulated. The bioinformatics analysis showed that those differentially expressed genes were related to axon development, neuron projection development, neuron projection morphogenesis, plasma membrane cell projection morphogenesis, cell part morphogenesis, notch signaling pathway, long-term potentiation, MAPK signaling pathway, Hedgehog signaling pathway, and so on. The results of RT-PCR showed that Caspase 9 mRNA increased and BDNF, Grin2a, and PlexinD1 mRNA decreased after electroacupuncture intervention $\left(P<0.05\right)$ . Conclusion. Electroacupuncture intervention on hand-taiyin meridian may reduce neurological function scores, inhibit neuron apoptosis, and enhance neuronal repair neuroreparation in MCAO/R rats, which may be related to the regulation of genes such as Caspase 9, BDNF, Grin2a, and PlexinD1.

Impact of MMP2 rs243849 and rs14070 genetic polymorphisms on the ischemic stroke susceptibility in Chinese Shaanxi population

Background

Ischemic stroke (IS) is a complex neurological disease affected by genetics and environment. Matrix metalloproteinase-2 (MMP2) is involved in extracellular matrix (ECM) degradation, inflammation and angiogenesis to regulate the development and recovery of IS.

Purposes

The aim of this study was to explore the association of rs1053605, rs243849 and rs14070 in MMP2 with the risk of IS in Chinese Shaanxi population.

Methods

In this study, 677 IS patients and 681 normal controls were recruited. Rs1053605, rs243849 and rs14070 in MMP2 were genotyped. Logistic regression analysis was applied to evaluate the association of rs1053605, rs243849 and rs14070 in MMP2 with IS susceptibility and the association of environmental factors with MMP2 genetic susceptibility to IS.

Results

The results of the overall analysis demonstrated that rs14070 in MMP2 significantly reduced the risk of IS in Chinese Shaanxi population (OR = 0.767, 95% CI = 0.619–0.952, P = 0.016). Subgroup analysis illustrated that rs243849 in MMP2 evidently increased the risk of IS among drinkers, while rs14070 in MMP2 apparently reduced IS susceptibility among females, participants with aged >55, smokers and drinkers.

Conclusions

Collectively, rs243849 and rs14070 in MMP2 were significantly associated with the risk of IS in Chinese Shaanxi population, and the effect of MMP2 to IS may be associated with its genetic susceptibility.

Transcranial ultrasound stimulation applied in ischemic stroke rehabilitation: A review

Ischemic stroke is a serious medical condition that is caused by cerebral vascular occlusion and leads to neurological dysfunction. After stroke, patients suffer from long-term sensory, motor and cognitive impairment. Non-invasive neuromodulation technology has been widely studied in the field of stroke rehabilitation. Transcranial ultrasound stimulation (TUS), as a safe and non-invasive technique with deep penetration ability and a tiny focus, is an emerging technology. It can produce mechanical and thermal effects by delivering sound waves to brain tissue that can induce the production of neurotrophic factors (NFs) in the brain, and reduce cell apoptosis and the inflammatory response. TUS, which involves application of an acoustic wave, can also dissolve blood clots and be used to deliver therapeutic drugs to the ischemic region. TUS has great potential in the treatment of ischemic stroke. Future advancements in imaging and parameter optimization will improve the safety and efficacy of this technology in the treatment of ischemic stroke.

Plasma levels of BDNF and EGF are reduced in acute stroke patients

Stroke affects almost 14 million people worldwide each year. It is the second leading cause of death and a major cause of acquired disability. The degree of initial impairment in cognitive and motor functions greatly affects the recovery, but idiosyncratic factors also contribute. These are largely unidentified, which contributes to making accurate prediction of recovery challenging. Release of soluble regulators of neurotoxicity, neuroprotection and repair are presumably essential. Here we measured plasma levels of known regulators of neuroprotection and repair in patients with mild acute ischemic stroke and compared them to the plasma levels in healthy age and gender matched controls. We found that the levels of BDNF and EGF were substantially lower in stroke patients than in healthy controls, while the levels of bFGF and irisin did not differ between the groups. The lower levels of growth factors highlight that during the acute phase of stroke, there is a mismatch between the need for neuroprotection and repair, and the brain's ability to induce these processes. Large individual differences in growth factor levels were seen among the stroke patients, but whether these can be used as predictors of long-term prognosis remains to be investigated.

Brain-Derived Neurotrophic Factor and Nerve Growth Factor Therapeutics for Brain Injury: The Current Translational Challenges in Preclinical and Clinical Research

Ischemic stroke and traumatic brain injury (TBI) are among the leading causes of death and disability worldwide with impairments ranging from mild to severe. Many therapies are aimed at improving functional and cognitive recovery by targeting neural repair but have encountered issues involving efficacy and drug delivery. As a result, therapeutic options for patients are sparse. Neurotrophic factors are one of the key mediators of neural plasticity and functional recovery. Neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) serve as potential therapeutic options to increase neural repair and recovery as they promote neuroprotection and regeneration. BDNF and NGF have demonstrated the ability to improve functional recovery in preclinical and to a lesser extent clinical studies. Direct and indirect methods to increase levels of neurotrophic factors in animal models have been successful in improving postinjury outcome measures. However, the translation of these studies into clinical trials has been limited. Preclinical experiments have largely failed to result in significant impacts in clinical research. This review will focus on the administration of these neurotrophic factors in preclinical and clinical stroke and TBI and the challenges in translating these therapies from the bench to the clinic.

Microstructure and Genetic Polymorphisms: Role in Motor Rehabilitation After Subcortical Stroke

Background and Purpose: Motor deficits are the most common disability after stroke, and early prediction of motor outcomes is critical for guiding the choice of early interventions. Two main factors that may impact the response to rehabilitation are variations in the microstructure of the affected corticospinal tract (CST) and genetic polymorphisms in brain-derived neurotrophic factor (BDNF). The purpose of this article was to review the role of these factors in stroke recovery, which will be useful for constructing a predictive model of rehabilitation outcomes.

Summary of Review: We review the microstructure of the CST, including its origins in the primary motor area (M1), primary sensory area (S1), premotor cortex (PMC), and supplementary motor area (SMA). Damage to these fibers is disease-causing and can directly affect rehabilitation after subcortical stroke. BDNF polymorphisms are not disease-causing but can indirectly affect neuroplasticity and thus motor recovery. Both factors are known to be correlated with motor recovery. Further work is needed using large longitudinal patient samples and animal experiments to better establish the role of these two factors in stroke rehabilitation.

Conclusions: Microstructure and genetic polymorphisms should be considered possible predictors or covariates in studies investigating motor recovery after subcortical stroke. Future predictive models of stroke recovery will likely include a combination of structural and genetic factors to allow precise individualization of stroke rehabilitation strategies.

Genetics in aphasia recovery

Considerable research efforts have been exerted toward understanding the mechanisms underlying recovery in aphasia. However, predictive models of spontaneous and treatment-induced recovery remain imprecise. Some of the hitherto unexplained variability in recovery may be accounted for with genetic data. A few studies have examined the effects of the BDNF val66met polymorphism on aphasia recovery, yielding mixed results. Advances in the study of stroke genetics and genetics of stroke recovery, including identification of several susceptibility genes through candidate-gene or genome-wide association studies, may have implications for the recovery of language function. The current chapter discusses both the direct and indirect evidence for a genetic basis of aphasia recovery, the implications of recent findings within the field, and potential future directions to advance understanding of the genetics-recovery associations.

BDNF polymorphism and inter hemispheric balance of motor cortex excitability: a preliminary study

Preclinical studies have demonstrated that Brain-Derived Neurotrophic Factor (BDNF) plays a crucial role in the homeostatic regulation of cortical excitability and excitation/inhibition balance. Using transcranial magnetic stimulation (TMS) techniques we investigated whether BDNF polymorphism could influence cortical excitability of the left and right primary motor cortex in healthy humans. Twenty-nine participants were recruited and genotyped for the presence of the BDNF Val66Met polymorphism, namely homozygous for the valine allele (Val/Val), heterozygotes (Val/Met), and homozygous for the methionine allele (Met/Met). Blinded to the latter, we evaluated inhibitory and facilitatory circuits of the left (LH) and right motor cortex (RH) by measuring resting (RMT) and active motor threshold (AMT), short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). For each neurophysiological metric we also considered the inter-hemispheric balance expressed by the Laterality Index (LI). Val/Val participants (n= 21) exhibited an overall higher excitability of the LH compared to the RH, as probed by lower motor thresholds, lower SICI and higher ICF. Val/Val participants displayed positive LI, especially for AMT and ICF (all p< 0.05), indicating higher LH excitability and more pronounced inter-hemispheric excitability imbalance as compared to Met carriers. Our preliminary results suggest that BDNF Val66Met polymorphism might influence interhemispheric balance of motor cortex excitability.

Genetic Factors, Brain Atrophy, and Response to Rehabilitation Therapy After Stroke

OBJECTIVE

Patients show substantial differences in response to rehabilitation therapy after stroke. We hypothesized that specific genetic profiles might explain some of this variance and, secondarily, that genetic factors are related to cerebral atrophy post-stroke.

METHODS

The phase 3 ICARE study examined response to motor rehabilitation therapies. In 216 ICARE enrollees, DNA was analyzed for presence of the BDNF val⁶⁶met and the ApoE ε4 polymorphism. The relationship of polymorphism status to 12-month change in motor status (Wolf Motor Function Test, WMFT) was examined. Neuroimaging data were also evaluated (n=127).

RESULTS

Subjects were 61±13 years old (mean±SD) and enrolled 43±22 days post-stroke; 19.7% were BDNF val⁶⁶met carriers and 29.8% ApoE ε4 carriers. Carrier status for each polymorphism was not associated with WMFT, either at baseline or over 12 months of follow-up. Neuroimaging, acquired 5±11 days post-stroke, showed that BDNF val⁶⁶met polymorphism carriers had a 1.34-greater degree of cerebral atrophy compared to non-carriers (P=.01). Post hoc analysis found that age of stroke onset was 4.6 years younger in subjects with the ApoE ε4 polymorphism (P=.02).

CONCLUSION

Neither the val⁶⁶met BDNF nor ApoE ε4 polymorphism explained inter-subject differences in response to rehabilitation therapy. The BDNF val⁶⁶met polymorphism was associated with cerebral atrophy at baseline, echoing findings in healthy subjects, and suggesting an endophenotype. The ApoE ε4 polymorphism was associated with younger age at stroke onset, echoing findings in Alzheimer's disease and suggesting a common biology. Genetic associations provide insights useful to understanding the biology of outcomes after stroke.

Using Human Genetics to Understand Mechanisms in Ischemic Stroke Outcome: From Early Brain Injury to Long-Term Recovery

There is a critical need to elucidate molecular mechanisms underlying brain injury, repair, and recovery following ischemic stroke-a global health problem with major social and economic impact. Despite 5 decades of intensive research, there are no widely accepted neuroprotective drugs that mitigate ischemic brain injury, or neuroreparative drugs, or personalized approaches that guide therapies to enhance recovery. We here explore novel reverse translational approaches that will complement traditional forward translational methods in identifying mechanisms relevant to human stroke outcome. Although genome-wide association studies have yielded over 30 genetic loci that influence ischemic stroke risk, only a few genome-wide association studies have been performed for stroke outcome. We discuss important considerations for genetic studies of ischemic stroke outcome-including carefully designed phenotypes that capture injury/recovery mechanisms, anchored in time to stroke onset. We also address recent genome-wide association studies that provide insight into mechanisms underlying brain injury and repair. There are several ongoing initiatives exploring genomic associations with novel phenotypes related to stroke outcome. To improve the understanding of the genetic architecture of ischemic stroke outcome, larger studies using standardized phenotypes, preferably embedded in standard-of-care measures, are needed. Novel techniques beyond genome-wide association studies-including exploiting informatics, multi-omics, and novel analytics-promise to uncover genetic and molecular pathways from which drug targets and other new interventions may be identified.

Brain-Derived Neurotrophic Factor Polymorphism and Aphasia after Stroke

Stroke is one of the most deliberating causes of mortality and disability worldwide. Studies have implicated Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene as a genetic factor influencing stroke recovery. Still, the role of BDNF polymorphism in poststroke aphasia is relatively unclear. This review assesses the recent evidence on the association between the BDNF polymorphism and aphasia recovery in poststroke patients. The article highlights BNDF polymorphism characteristics, speech and language interventions delivered, and the influence of BNDF polymorphism on poststroke aphasia recovery. We conducted a literature search through PubMed and Google Scholar with the following terms: “brain derived-neurotrophic factor” and “aphasia” for original articles from January 2000 until June 2020. Out of 69 search results, a detailed selection process produced a total of 3 articles that met the eligibility criteria. All three studies included Val66Met polymorphism as the studied human BDNF gene. One of the studies demonstrated insufficient evidence to conclude that BDNF polymorphism plays a role in poststroke aphasia recovery. The remaining two studies have shown that Met allele genotype (either single or double nucleotides) was associated with poor aphasia recovery, in either acute or chronic stroke. Carriers of the Val66Met polymorphism of BDNF gave a poorer response to aphasia intervention and presented with more severe aphasia.

Potential Prognostic Impact of Dopamine Receptor D1 (rs4532) Polymorphism in Post-stroke Outcome in the Elderly

Background: Single-nucleotide polymorphisms (SNPs) may affect post-stroke motor recovery, and some SNPs have been implicated in swallowing disturbances after stroke. Certain SNPs may also have altered influences according to different age. Objective: This post-hoc study investigated whether SNPs have different effects on dysphagia recovery between the elderly vs. young stroke patients. Methods: Analysis was conducted from a previous study including 218 stroke subjects with dysphagia. They were stratified into two groups, aged <65 and aged ≥65 years. The primary outcome was persistence of nil per mouth (NPM) at 3 months post-stroke onset. Association between outcome and nine different SNPs were investigated. Results: The elderly group (50%, n = 103) showed poorer swallowing outcomes than the young group. The minor allele of the dopamine receptor D1 (DRD1, rs4532) polymorphism showed potential association (p = 0.022) with an increased risk of NPM at 12 weeks post-stroke in the elderly, both in the additive (OR, 2.94; 95% CI, 1.17-7.37) and dominant models (OR, 2.93; 95% CI, 1.04-8.23) but did not reach statistical significance after Bonferonni correction. Logistic regression analysis showed that in those aged ≥65 years, models including the minor allele of rs4532 predicted the risk of the poor outcome with good accuracies even after adjustment of clinical factors, such as previous pneumonia episodes (AUROC, 0.86; 95% CI, 0.79-0.93) or the National Institutes of Health Stroke Scale (AUROC, 0.82; 95% CI, 0.67-0.92). In contrast, those aged <65 years seemed not to be affected by the presence of the rs4532 polymorphism, and models that included intubation history (AUROC, 0.81; 95% CI, 0.73-0.90) or previous pneumonia episodes (AUROC, 0.77; 95% CI, 0.68-0.87) showed modest levels of accuracies in predicting NPM at 12 weeks poststroke. Conclusions: Our study suggests a possible association between the rs4532 and post-stroke swallowing recovery, primarily in those aged ≥65 years. Certain SNPs may lead to less favorable outcomes in the elderly. The gene-age interaction should be considered in post-stroke swallowing recovery. Clinical Trial Registration: https://www.clinicaltrials.gov, Unique identifier [NCT03577444].

The Influence of Val66Met Polymorphism in Brain-Derived Neurotrophic Factor on Stroke Recovery Outcome: A Systematic Review and Meta-analysis

Background and purpose. A single nucleotide polymorphism at nucleotide 196 (G/A) in the human brain-derived neurotrophic factor (BDNF) gene produces an amino acid substitution (valine to methionine) at codon 66(Val66Met). It is unclear whether carriers of this substitution may have worse functional outcomes after stroke. We aimed to explore the distribution of Val66Met polymorphism and evaluate the effect of different genotypes on stroke functional recovery. Methods. Several databases were searched using the keywords BDNF or brain-derived neurotrophic factor, codon66, G196A, rs6265, or Val66Met, and stroke. Results. A total of 25 articles were relevant to estimate the distribution of alleles; 5 reports were applied in the meta-analysis to assess genetic differences on recovery outcomes. The genetic model analysis showed that the recessive model should be used; we combined data for AA versus GA+GG (GG-Val/Val, GA-Val/Met, AA-Met/Met). The results showed that stroke patients with AA might have worse recovery outcomes than those with GA+GG (odds ratio = 1.90; 95% CI: 1.17-3.10; P = .010; I² = 69.2%). Overall, the A allele may be more common in Asian patients (48.6%; 95% CI: 45.8%-51.4%, I² = 54.2%) than Caucasian patients (29.8%; 95% CI: 7.5%-52.1%; I² = 99.1%). However, in Caucasian patients, the frequency of the A allele in Iranians (87.9%; 95% CI: 83.4%-92.3%) was quite higher than that in other Caucasians (18.7%; 95% CI: 16.6%-20.9%; I² = 0.00%). Conclusion. Val66Met AA carriers may have worse rehabilitation outcomes than GA+GG carriers. Further studies are needed to determine the effect of Val66Met polymorphism on stroke recovery and to evaluate this relationship with ethnicity, sex, age, stroke type, observe duration, stroke severity, injury location, and therapies.

Predictors of Function, Activity, and Participation of Stroke Patients Undergoing Intensive Rehabilitation: A Multicenter Prospective Observational Study Protocol

Background: The complex nature of stroke sequelae, the heterogeneity in rehabilitation pathways, and the lack of validated prediction models of rehabilitation outcomes challenge stroke rehabilitation quality assessment and clinical research. An integrated care pathway (ICP), defining a reproducible rehabilitation assessment and process, may provide a structured frame within investigated outcomes and individual predictors of response to treatment, including neurophysiological and neurogenetic biomarkers. Predictors may differ for different interventions, suggesting clues to personalize and optimize rehabilitation. To date, a large representative Italian cohort study focusing on individual variability of response to an evidence-based ICP is lacking, and predictors of individual response to rehabilitation are largely unexplored. This paper describes a multicenter study protocol to prospectively investigate outcomes and predictors of response to an evidence-based ICP in a large Italian cohort of stroke survivors undergoing post-acute inpatient rehabilitation.

Methods: All patients with diagnosis of ischemic or hemorrhagic stroke confirmed both by clinical and brain imaging evaluation, admitted to four intensive rehabilitation units (adopting the same stroke rehabilitation ICP) within 30 days from the acute event, aged 18+, and providing informed consent will be enrolled (expected sample: 270 patients). Measures will be taken at admission (T0), at discharge (T1), and at follow-up 6 months after a stroke (T2), including clinical data, nutritional, functional, neurological, and neuropsychological measures, electroencephalography and motor evoked potentials, and analysis of neurogenetic biomarkers.

Statistics: In addition to classical multivariate logistic regression analysis, advanced machine learning algorithms will be cross-validated to achieve data-driven prognosis prediction models.

Discussion: By identifying data-driven prognosis prediction models in stroke rehabilitation, this study might contribute to the development of patient-oriented therapy and to optimize rehabilitation outcomes.

Clinical Trial Registration:ClinicalTrials.gov, NCT03968627. https://www.clinicaltrials.gov/ct2/show/NCT03968627?term=Cecchi&cond=Stroke&draw=2&rank=2.

Motor Recovery: How Rehabilitation Techniques and Technologies Can Enhance Recovery and Neuroplasticity

There are now a large number of technological and methodological approaches to the rehabilitation of motor function after stroke. It is important to employ these approaches in a manner that is tailored to specific patient impairments and desired functional outcomes, while avoiding the hype of overly broad or unsubstantiated claims for efficacy. Here we review the evidence for poststroke plasticity, including therapy-related plasticity and functional imaging data. Early demonstrations of remapping in somatomotor and somatosensory representations have been succeeded by findings of white matter plasticity and a focus on activity-dependent changes in neuronal properties and connections. The methods employed in neurorehabilitation have their roots in early understanding of neuronal circuitry and plasticity, and therapies involving large numbers of repetitions, such as robotic therapy and constraint-induced movement therapy (CIMT), change measurable nervous systems properties. Other methods that involve stimulation of brain and peripheral excitable structures have the potential to harness neuroplastic mechanisms, but remain experimental. Gaps in our understanding of the neural substrates targeted by neurorehabilitation technology and techniques remain, preventing their prescriptive application in individual patients as well as their general refinement. However, with ongoing research-facilitated in part by technologies that can capture quantitative information about motor performance-this gap is narrowing. These research approaches can improve efforts to attain the shared goal of better functional recovery after stroke.

Role of rs6265 BDNF polymorphisms and post-stroke dysphagia recovery-A prospective cohort study

BACKGROUND

Previous studies suggest that specific genes may predispose some to increased risk of dysphagia in the geriatric population, but whether these genes may affect swallowing recovery after a stroke is unknown. This study investigated whether single-nucleotide polymorphisms (SNP) of the brain-derived neurotrophic factor (BDNF), catechol-O-methyl transferase, apolipoprotein E, interleukin-1 receptor antagonist, and dopamine, which have been linked to swallowing, could adversely affect the prognosis of post-stroke dysphagia.

METHODS

In this study, 218 subjects with confirmed post-stroke dysphagia were enrolled. The primary endpoint was failed recovery from nil per mouth (NPM) status with the first 3 months post-stroke.

KEY RESULTS

The Val/Val group from the rs6265, BDNF, showed higher score changes on the Functional Oral Intake Scale at 1 month. The proportion of patients with recovery from NPM status within the first 1 month was 60.8% in the Val/Val group, which was statistically higher than those in the Met allele groups (38.1%, P = .017). At 3 months, the BDNF rs6265 showed significant group differences in Modified Barium Swallow Impairment Profile^© score changes with the Val/Val allele leading to greater improvement. However, no single SNP was associated with increased risk of poor recovery with persistence of NPM at 3 months post-stroke.

CONCLUSIONS AND INFERENCES

Those with the dominant Val/Val phenotype of BDNF manifested with faster and greater improvement than the Met-phenotypes. Based on our results, the BDNF Val allele may play a positive role with faster score improvement and rapid recovery from NPM than the Met allele. Clinical Trials gov: NCT03577444 (https://clinicaltrials.gov/ct2/show/study/NCT03577444).

Post-Stroke Social Isolation Reduces Cell Proliferation in the Dentate Gyrus and Alters miRNA Profiles in the Aged Female Mice Brain

Social isolation and loneliness are risk factors for stroke. Elderly women are more likely to be isolated. Census data shows that in homeowners over the age of 65, women are much more likely to live alone. However, the underlying mechanisms of the detrimental effects of isolation have not been well studied in older females. In this study, we hypothesized that isolation impairs post-stroke recovery in aged female mice, leading to dysregulated microRNAs (miRNAs) in the brain, including those previously shown to be involved in response to social isolation (SI). Aged C57BL/6 female mice were subjected to a 60-min middle cerebral artery occlusion and were randomly assigned to either single housing (SI) or continued pair housing (PH) immediately after stroke for 15 days. SI immediately after stroke led to significantly more brain tissue loss after stroke and higher mortality. Furthermore, SI significantly delayed motor and sensory recovery and worsened cognitive function, compared to PH. A decrease in cell proliferation was seen in the dentate gyrus of SI mice assessed by bromodeoxyuridine (BrdU) labeling. miRNAome data analysis revealed changes in several miRNAs in the brain, such as miR-297a-3p and miR-200c-3p, which are known to regulate pathways involved in cell proliferation. In conclusion, our data suggest that SI can lead to a poor post-stroke recovery in aged females and dysregulation of miRNAs and reduced hippocampal cell proliferation.

Effects of the BDNF Val66Met polymorphism on functional status and disability in young stroke patients

BACKGROUND AND PURPOSE

The preponderance of evidence from recent studies in human subjects supports a negative effect of the BDNF Val66Met polymorphism on motor outcomes and motor recovery. However prior studies have generally reported the effect of the Met allele in older stroke patients, while potential effects in younger stroke patients have remained essentially unexamined. The lack of research in younger patients is significant since aging effects on CNS repair and functional recovery after stroke are known to interact with the effects of genetic polymorphisms. Here we present a study of first-ever ischemic stroke patients aged 15-49 years that examines the effect of Met carrier status on functional disability.

METHODS

829 patients with a first ischemic stroke (Average age = 41.4 years, SD = 6.9) were recruited from the Baltimore-Washington region. Genotyping was performed at the Johns Hopkins University Center for Inherited Disease Research (CIDR). Data cleaning and harmonization were done at the GEI-funded GENEVA Coordinating Center at the University of Washington. Our sample contained 165 Met carriers and 664 non-Met carriers. Modified Rankin scores as recorded at discharge were obtained from the hospital records by study personnel blinded to genotype, and binarized into "Good" versus "Poor" outcomes (mRS 0-2 vs. 3+), with mRS scores 3+ reflecting a degree of disability that causes loss of independence.

RESULTS

Our analysis showed that the Met allele conveyed a proportionally greater risk for poor outcomes and disability-related loss of independence with mRS scores 3+ (adjusted OR 1.73, 95% CI 1.13-2.64, p = 0.01).

CONCLUSIONS

The BDNF Val66Met polymorphism was negatively associated with functional outcomes at discharge in our sample of 829 young stroke patients. This finding stands in contrast to what would be predicted under the tenets of the resource modulation hypothesis (i.e. that younger patients would be spared from the negative effect of the Met allele on recovery since it is posited to arise as a manifestation of age-related decline in physiologic resources).

Neurotrophic Factor BDNF, Physiological Functions and Therapeutic Potential in Depression, Neurodegeneration and Brain Cancer

Brain-derived neurotrophic factor (BDNF) is one of the most distributed and extensively studied neurotrophins in the mammalian brain. BDNF signals through the tropomycin receptor kinase B (TrkB) and the low affinity p75 neurotrophin receptor (p75NTR). BDNF plays an important role in proper growth, development, and plasticity of glutamatergic and GABAergic synapses and through modulation of neuronal differentiation, it influences serotonergic and dopaminergic neurotransmission. BDNF acts as paracrine and autocrine factor, on both pre-synaptic and post-synaptic target sites. It is crucial in the transformation of synaptic activity into long-term synaptic memories. BDNF is considered an instructive mediator of functional and structural plasticity in the central nervous system (CNS), influencing dendritic spines and, at least in the hippocampus, the adult neurogenesis. Changes in the rate of adult neurogenesis and in spine density can influence several forms of learning and memory and can contribute to depression-like behaviors. The possible roles of BDNF in neuronal plasticity highlighted in this review focus on the effect of antidepressant therapies on BDNF-mediated plasticity. Moreover, we will review data that illustrate the role of BDNF as a potent protective factor that is able to confer protection against neurodegeneration, in particular in Alzheimer's disease. Finally, we will give evidence of how the involvement of BDNF in the pathogenesis of brain glioblastoma has emerged, thus opening new avenues for the treatment of this deadly cancer.

[Assessment of the levels of neuron-specific enolase and BDNF at the stages of rehabilitation in the acute and early recovery periods of ischemic stroke]

BACKGROUND

The issue of the diagnostic significance and clinical value of neuron-specific enolase (NSE) and brain-derived neurotropic factor (BDNF) in the acute period of stroke remains controversial. Therefore, it is advisable to study the correlation of biomarkers with the clinical characteristics of stroke in the time period of early recovery.

OBJECTIVE

To monitor NSE and BDNF levels in peripheral blood, to analyze the clinical and laboratory correlations in patients with ischemic stroke at the stages of medical rehabilitation in the early recovery period.

MATERIAL AND METHODS

Forty-nine patients with ischemic stroke in the middle cerebral artery were examined. The observation period is 90 days. Observation Points are Day 1; Day 14; Day 45; Day 90. The National Institute of Health Stroke Scale (NIHSS), the Fugle-Meyer Scale (FMA), the Modified Rankin Scale (mRS) were administered. NSE was determined in blood serum by enzyme-linked immunosorbent assay, BDNF was analyzed on a multiplex analyzer.

RESULTS AND CONCLUSION

NSE_Day1 in patients was significantly higher than in the comparison group (p_{Day1-comparison group}<0.001) with a trend to a maximum decrease on the 90th day of stroke (p_Day1-90<0.001). BDNF_Day1 turned out to be lower than in the comparison group (p_{Day1-comparison group}=0.006) and significantly increased by the 14th day of the stroke (p_Day1-14<0.001; p_{Day14-comparison group}=0.637). A negative correlation was found between a decrease in NSE_Day14 and an increase in BDNF_Day14 (r= -0.349; p=0.05). A positive correlation was found between an increase in BDNF_Day14 and a decrease in mRS scores _Day90 (r=0.499, p=0.035). Outcomes in patients in group 1 (after stages I and II of rehabilitation) on the assessment scales were significantly better than in patients discharged after stage I for outpatient monitoring - group 2 (p<0.05). In group 1, BDNF_Day90 did not differ from BDNF_Day14 (p_{Day14-90-Group1}=0.17), and in group 2 it was significantly lower by the end of the early recovery period (p_{Day14-90-Group2}=0.002).

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

We tested a newly described molecular memory system, CCR5 signaling, for its role in recovery after stroke and traumatic brain injury (TBI). CCR5 is uniquely expressed in cortical neurons after stroke. Post-stroke neuronal knockdown of CCR5 in pre-motor cortex leads to early recovery of motor control. Recovery is associated with preservation of dendritic spines, new patterns of cortical projections to contralateral pre-motor cortex, and upregulation of CREB and DLK signaling. Administration of a clinically utilized FDA-approved CCR5 antagonist, devised for HIV treatment, produces similar effects on motor recovery post stroke and cognitive decline post TBI. Finally, in a large clinical cohort of stroke patients, carriers for a naturally occurring loss-of-function mutation in CCR5 (CCR5-Δ32) exhibited greater recovery of neurological impairments and cognitive function. In summary, CCR5 is a translational target for neural repair in stroke and TBI and the first reported gene associated with enhanced recovery in human stroke.

Brain-Derived Neurotrophic Factor Genotype-Specific Differences in Cortical Activation in Chronic Aphasia

Purpose The brain-derived neurotrophic factor (BDNF) gene has been shown to be important for synaptic plasticity in animal models. Human research has suggested that BDNF genotype may influence stroke recovery. Some studies have suggested a genotype-specific motor-related brain activation in stroke recovery. However, recovery from aphasia in relation to BDNF genotype and language-related brain activation has received limited attention. We aimed to explore functional brain activation by BDNF genotype in individuals with chronic aphasia. Consistent with findings in healthy individuals and individuals with poststroke motor impairment, we hypothesized that, among individuals with aphasia, the presence of the Met allele of the BDNF gene is associated with reduced functional brain activation compared to noncarriers of the Met allele. Method Eighty-seven individuals with chronic stroke-induced aphasia performed a naming task during functional magnetic resonance imaging scanning and submitted blood or saliva samples for BDNF genotyping. The mean number of activated voxels was compared between groups, and group-based activation maps were directly compared. Neuropsychological testing was conducted to compare language impairment between BDNF genotype groups. The Western Aphasia Battery Aphasia Quotient (Kertesz, 2007) was included as a covariate in all analyses. Results While lesion size was comparable between groups, the amount of activation, quantified as the number of activated voxels, was significantly greater in noncarriers of the Met allele (whole brain: 98,500 vs. 28,630, p < .001; left hemisphere only: 37,209 vs. 7,000, p < .001; right hemisphere only: 74,830 vs. 30,630, p < .001). This difference was most strongly expressed in the right hemisphere posterior temporal area, pre- and postcentral gyrus, and frontal lobe, extending into the white matter. Correspondingly, the atypical BDNF genotype group was found to have significantly less severe aphasia (Western Aphasia Battery Aphasia Quotient of 64.2 vs. 54.3, p = .033) and performed better on a naming task (Philadelphia Naming Test [Roach, Schwartz, Martin, Grewal, & Brecher, 1996] score of 74.7 vs. 52.8, p = .047). A region of interest analysis of intensity of activation revealed no group differences, and a direct comparison of average activation maps across groups similarly yielded null results. Conclusion BDNF genotype mediates cortical brain activation in individuals with chronic aphasia. Correspondingly, individuals carrying the Met allele present with more severe aphasia compared to noncarriers. These findings warrant further study into the effects of BDNF genotype in aphasia. Supplemental Material https://doi.org/10.23641/asha.10073147 Presentation Video https://doi.org/10.23641/asha.10257581.

An Increase of Excitatory-to-Inhibitory Synaptic Balance in the Contralateral Cortico-Striatal Pathway Underlies Improved Stroke Recovery in BDNF Val66Met SNP Mice

Despite negative association in cognition and memory, mice harboring Val66Met BDNF SNP (BDNF^M/M) exhibit enhanced motor recovery accompanied by elevated excitatory synaptic markers VGLUT1 and VGLUT2 in striatum contralateral to unilateral ischemic stroke. The cortico-striatal pathway is a critical gateway for plasticity of motor/gait function. We hypothesized that enhanced excitability of the cortico-striatal pathway, especially of the contralateral hemisphere, underlies improved motor recovery. To test this hypothesis, we examined the key molecules involving excitatory synaptogenesis: Thrombospondins (TSP1/2) and their neuronal receptor α2δ-1. In WT brains, stroke induced expressions of TSP1/2-mRNA. The contralateral hemisphere of BDNF^M/M mice showed heightened TSP2 and α2δ-1 mRNA and protein specifically at 6 months post-stroke. Immunoreactivities of TSPs and α2δ-1 were increased in cortical layers 1/2 of stroked BDNF^M/M animals compared with BDNF^M/M sham brains at this time. Areal densities of excitatory synapses in cortical layer 1 and striatum were also increased in stroked BDNF^M/M brains, relative to stroked WT brains. Notably, the frequency of GABAergic synapses was greatly reduced along distal dendrites in cortical layer 1 in BDNF^M/M brains, whether or not stroked, compared with WT brains. There was no effect of genotype or treatment on the density of GABAergic synapses onto striatal medium spiny neurons. The study identified molecular and synaptic substrates in the contralateral hemisphere of BDNF^M/M mice, especially in cortical layers 1/2, which indicates selective region-related synaptic plasticity. The study suggests that an increase in excitatory-to-inhibitory synaptic balance along the contralateral cortico-striatal pathway underlies the enhanced functional recovery of BDNF^M/M mice.

Actions of Brain-Derived Neurotrophin Factor in the Neurogenesis and Neuronal Function, and Its Involvement in the Pathophysiology of Brain Diseases

It is well known that brain-derived neurotrophic factor, BDNF, has an important role in a variety of neuronal aspects, such as differentiation, maturation, and synaptic function in the central nervous system (CNS). BDNF stimulates mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), phosphoinositide-3kinase (PI3K), and phospholipase C (PLC)-gamma pathways via activation of tropomyosin receptor kinase B (TrkB), a high affinity receptor for BDNF. Evidence has shown significant contributions of these signaling pathways in neurogenesis and synaptic plasticity in in vivo and in vitro experiments. Importantly, it has been demonstrated that dysfunction of the BDNF/TrkB system is involved in the onset of brain diseases, including neurodegenerative and psychiatric disorders. In this review, we discuss actions of BDNF and related signaling molecules on CNS neurons, and their contributions to the pathophysiology of brain diseases.