Relevance of Post-Stroke Circulating BDNF Levels as a Prognostic Biomarker of Stroke Outcome. Impact of rt-PA Treatment

Relationship between plasma brain-derived neurotrophic factor levels and neurological disorders: An investigation using Mendelian randomisation

Background

Altered brain-derived neurotrophic factor (BDNF) concentrations have been detected in the central nervous system tissues and peripheral blood. These alterations are associated with a series of neurological disorders.

Objective

To investigate the potential causal relationships between genetically determined plasma BDNF levels and various neurological diseases using a two-sample Mendelian randomisation study.

Methods

We selected single nucleotide polymorphisms strongly related to plasma BDNF levels as instrumental variables. Within the Mendelian randomisation framework, we used summary-level statistics for exposure (plasma BDNF levels) and outcomes (neurological disorders).

Results

We observed suggestive evidence of a relation between higher plasma BDNF levels and less risk of nontraumatic intracranial haemorrhage (nITH) (odds ratio [OR] = 0.861, 95 % confidence interval [CI]: 0.774-0.958, P = 0.006, PFDR = 0.078), epilepsy (OR = 0.927, 95 % CI: 0.880-0.976, P = 0.004, PFDR = 0.078), focal epilepsy (OR = 0.928, 95 % CI: 0.874-0.986, P = 0.016, PFDR = 0.139), and non-lesional focal epilepsy (OR = 0.981, 95 % CI: 0.964-0.999, P = 0.041, PFDR = 0.267). Combined with the UK Biobank dataset, the association of plasma BDNF levels with nITH remained significant (OR = 0.88, 95 % CI: 0.81-0.96, P < 0.01). The combined analysis of three consortium datasets demonstrated a considerable impact of plasma BDNF on epilepsy (OR = 0.94, 95 % CI: 0.90-0.98, P < 0.01) and a suggestive impact on focal epilepsy (OR = 0.94, 95 % CI: 0.89-0.99, P = 0.02). However, there was no apparent correlation between plasma BDNF levels and other neurological disorders or related subtypes.

Conclusions

Our study supports a possible causal relationship between elevated plasma BDNF levels and a reduced risk of nITH, epilepsy, and focal epilepsy.

The intriguing role of platelets as custodians of brain-derived neurotrophic factor

A State of the Art lecture titled "Platelets and neurotrophins" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. Neurotrophins, a family of neuronal growth factors known to support cognitive function, are increasingly recognized as important players in vascular health. Indeed, along with their canonical receptors, neurotrophins are expressed in peripheral tissues, particularly in the vasculature. The better-characterized neurotrophin in vascular biology is the brain-derived neurotrophic factor (BDNF). Its largest extracerebral pool resides within platelets, partly inherited from megakaryocytes and also likely internalized from circulation. Activation of platelets releases vast amounts of BDNF into their milieu and interestingly leads to platelet aggregation through binding of its receptor, the tropomyosin-related kinase B, on the platelet surface. As BDNF is readily available in plasma, a mechanism to preclude excessive platelet activation and aggregation appears critical. As such, binding of BDNF to α2-macroglobulin hinders its ability to bind its receptor and limits its platelet-activating effects to the site of vascular injury. Altogether, addition of BDNF to a forming clot facilitates not only paracrine platelet activation but also binding to fibrinogen, rendering the resulting clot more porous and plasma-permeable. Importantly, release of BDNF into circulation also appears to be protective against adverse cardiovascular and cerebrovascular outcomes, which has been reported in both animal models and epidemiologic studies. This opens an avenue for platelet-based strategies to deliver BDNF to vascular lesions and facilitate wound healing through its regenerative properties. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Modulation of neurotrophic factors in the treatment of dementia, stroke and TBI: Effects of Cerebrolysin

Neurotrophic factors (NTFs) are involved in the pathophysiology of neurological disorders such as dementia, stroke and traumatic brain injury (TBI), and constitute molecular targets of high interest for the therapy of these pathologies. In this review we provide an overview of current knowledge of the definition, discovery and mode of action of five NTFs, nerve growth factor, insulin-like growth factor 1, brain derived NTF, vascular endothelial growth factor and tumor necrosis factor alpha; as well as on their contribution to brain pathology and potential therapeutic use in dementia, stroke and TBI. Within the concept of NTFs in the treatment of these pathologies, we also review the neuropeptide preparation Cerebrolysin, which has been shown to resemble the activities of NTFs and to modulate the expression level of endogenous NTFs. Cerebrolysin has demonstrated beneficial treatment capabilities in vitro and in clinical studies, which are discussed within the context of the biochemistry of NTFs. The review focuses on the interactions of different NTFs, rather than addressing a single NTF, by outlining their signaling network and by reviewing their effect on clinical outcome in prevalent brain pathologies. The effects of the interactions of these NTFs and Cerebrolysin on neuroplasticity, neurogenesis, angiogenesis and inflammation, and their relevance for the treatment of dementia, stroke and TBI are summarized.

The effect of intravenous thrombolytic therapy on post stroke depression and cognitive dysfunction: A 3-months follow up study

Several studies have demonstrated the efficacy of intravenous thrombolytic therapy with recombinant plasminogen activator (rt-PA) on functional recovery at 3-18 months following the treatment. The objectives of this study were to investigate differences between thrombolytic or no thrombolytic treatment and if could be a relationship between patients who have underwent the thrombolytic treatment in terms of depressive symptoms and cognitive impairment. In this retrospective study, we evaluated 92 patients affected by ischemic stroke recruited from our rehabilitation center, coming from a Stroke Unit. All the eligible subjects were assessed at admission (T0) and two months later, at discharge, upon concluded the rehabilitation program (T1). The patients were divided into two groups: Thrombolysis Group (n.40 subjects) and no Thrombolysis Group (n.52 subjects). Cognitive functions were evaluated with the Montreal Overall Cognitive Assessment. Functional status were evaluated with the Barthel Index and the Functional Independent Misure. We administered Beck Depression Inventory-II to verify the presence of a depressive state. We found that at three months after stroke, the prevalence of depressive symptoms and cognitive improvement, among patient who had undergone thrombolytic treatment, and who had not, was not different. Conversely, we found an improvement of depressive symptoms in each group.

Fluid biomarkers in stroke: From animal models to clinical care

Stroke is a leading cause of death and disability worldwide. Stroke prevention, early diagnosis, and efficient acute treatment are priorities to successfully impact stroke death and disability. Fluid biomarkers may improve stroke differential diagnostic, patient stratification for acute treatment, and post-stroke individualized rehabilitation. In the present work, we characterized the use of stroke animal models in fluid biomarker research through a systematic review of PubMed and Scopus databases, followed by a literature review on the translation to the human stroke care setting and future perspectives in the field. We found increasing numbers of publications but with limited translation to the clinic. Animal studies are very heterogeneous, do not account for several human features present in stroke, and, importantly, only a minority of such studies used human cohorts to validate biomarker findings. Clinical studies have found appealing candidates, both protein and circulating nucleic acids, to contribute to a more personalized stroke care pathway. Still, brain tissue complexity and the fact that different brain pathologies share lesion biomarkers make this task challenging due to biomarker low specificity. Moreover, the study design and lack of validation cohorts may have precluded a formal integration of biomarkers in different steps of stroke diagnosis and treatment. To overcome such issues, recent pivotal studies on biomarker dynamics in individual patients are providing added value to diagnosis and anticipating patients' early prognosis. Presently, the most consistent protein biomarkers for stroke diagnosis and short- and long-term prognosis are associated with tissue damage at neuronal (TAU), axonal (NFL), or astroglial (GFAP and S100β) levels. Most promising nucleic acids are microRNAs (miR), due to their stability in plasma and ease of access. Still, clinical validation and standardized quantitation place them a step behind compared protein as stroke biomarkers. Ultimately, the definition of clinically relevant biomarker panels and optimization of fast and sensitive biomarker measurements in the blood, together with their combination with clinical and neuroimaging data, will pave the way toward personalized stroke care.

Circulating brain-derived neurotrophic factor as a potential biomarker in stroke: a systematic review and meta-analysis

Background

Stroke, an acute cerebrovascular event, is a leading cause of disability, placing a significant psycho-socioeconomic burden worldwide. The adaptation and reorganization process following any neuronal damage is regarded as neuroplasticity. Among many factors believed to attribute to this process, Brain-derived Neurotrophic Factor (BDNF) is a neurotrophin coordinating neuroplasticity after various neurological disorders such as stroke.

Methods

We conducted a systematic search in the main electronic medical databases in January 2021. Primarily we want to compare BDNF levels between patients with stroke and healthy controls (HC). Additional aims included investigation of (1) longitudinal changes in the BDNF levels post-stroke, (2) effects of physical training, (3) repeated transcranial magnetic stimulation (rTMS), and presence of depression on BDNF levels in patients with stroke.

Results

Among 6243 reviewed records from PubMed, Web of Science, and Scopus, 62 studies were eligible for inclusion in our systematic review. Subjects with stroke, n = 1856, showed lower BDNF levels compared to HC, n = 1191 (SMD [95%CI] = − 1.04 [− 1.49 to − 0.58]). No significant difference was detected in the level of BDNF through time points past stroke. BDNF levels were lower in the patients with depression compared to non-depressed subjects (SMD [95%CI] = − 0.60 [− 1.10 to − 0.10]). Physical training had an immediate positive effect on the BDNF levels and not statistically significant effect in the long term; SMD [95%CI] = 0.49 [0.09 to 0.88]) and SMD [95%CI] = 0.02 [− 0.43 to 0.47]). Lastly, rTMS showed no effect on the level of BDNF with 0.00 SMD.

Conclusions

Our study confirms that stroke significantly decreases the level of BDNF in various domains such as cognition, affect, and motor function. As BDNF is the major representative of neuroplasticity within nervous system, it is believed that stroke has a significant impact on the CNS regeneration, which is permanent if left untreated. This effect is intensified with coexisting conditions such as depression which further decrease the BDNF level but the net impact yet needs to be discovered. We also conclude that exercise and some interventions such as different medications could effectively reverse the damage but further studies are crucial to reach the exact modality and dosage for their optimal effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03312-y.

The use of recombinant tissue plasminogen activator in in acute ischemic stroke is associated with increased level of BDNF

Much concern was directed towards the crucial role of recombinant tissue plasminogen activator (rt-PA) in improving neuroplasticity in patients with acute ischemic stroke. The aim of the work to investigate the effect of treating patients with acute ischemic stroke with rt-PA, on the level of brain derived neurotrophic factor (BDNF) as a marker of neuroplasticity. This study was conducted on 47 patients presenting with acute ischemic stroke (during the first 4.5 h from stroke onset); 26 patients of them eligible for receiving rt-PA (patient group) and 21 patients having contraindications for treatment with rt-PA (control group). Neurological, radiological and laboratory assessment (including BDNF serum level) were done for both groups at stroke onset (before receiving rt-PA) and at day 7. There was a statistically significant increase in BDNF serum level from day 1 to day 7 in rt-PA treated patients in comparison to control group (P-value˂ 0.001). Serum level of BDNF is significantly higher at the onset of stroke in female patients and non-smokers than males or smokers (P-value = 0.011, 0.01 respectively). There was no effect of either age, body mass index, hypertension, diabetes, drug abuse, past or family history of stroke, valvular heart diseases, atrial fibrillation, cardiomyopathy, ejection fraction, carotid atherosclerotic changes, lipid profile or uric acid, on BDNF serum level measured at the onset of stroke. Treatment of patients with acute ischemic stroke with rt-PA causes significant improvement in neuroplasticity through increasing BDNF serum level.

Serum BDNF Levels in Acute Stroke: A Systematic Review and Meta-Analysis

Background and objectives: Brain-derived neurotrophic factor (BDNF) is one of the most studied neurotrophins. Low BDNF concentrations have been noted in patients with traditional cardiovascular disease risk factors and have been associated with the increased risk of stroke/transient ischemic attack (TIA). We aimed to study the correlation of BDNF serum levels with acute stroke severity and its potential role as a biomarker in predicting functional outcome. Materials and methods: We systematically searched PubMed, Web of Science, and the Cochrane database using specific keywords. The endpoints examined were the correlation of BDNF with functional outcome, the National Institute of Health stroke scale (NIHSS) measured at the acute phase, and stroke infarct volume. We also compared serum BDNF levels between stroke patients and healthy controls. Results: Twenty-six records were included from the initial 3088 identified. Twenty-five studies reported NIHSS and BDNF levels on the first day after acute stroke. Nine studies were further meta-analyzed. A statistically significant negative correlation between NIHSS and BDNF levels during the acute phase of stroke was noted (COR: −0.3013, 95%CI: (−0.4725; −0.1082), z = −3.01, p = 0.0026). We also noted that BDNF levels were significantly lower in patients with stroke compared to healthy individuals. Due to the heterogeneity of studies, we only conducted a qualitative analysis regarding serum BDNF and functional outcome, while no correlation between BDNF levels and stroke infarct volume was noted. Conclusions: We conclude that in the acute stroke phase, stroke severity is negatively correlated with BDNF levels. Concurrently, patients with acute stroke have significantly lower BDNF levels in serum compared to healthy controls. No correlations between BDNF and stroke infarct volume or functional outcome at follow-up were noted.

Post-stroke BDNF concentration changes following proprioceptive neuromuscular facilitation (PNF) exercises

Background:

Brain-derived neurotrophic factor (BDNF) plays an important role in repairing normal as well as in the injured brain. Physical exercise may have a positive impact on the release of BDNF.

Objective:

PNF is a neurophysiological approach that facilitates the stimulation of central and peripheral nervous systems. In this study, our aim was to assess the levels of BDNF as well as functional recovery before and after the intervention of PNF in patients with acute stroke.

Methods:

A total of 208 patients with first time confirmed stroke were recruited and assessed for stroke severity, type, mini-mental state exam (MMSE), functional independence measure scale, and BDNF levels before and after PNF intervention. BDNF levels were also assessed in healthy individuals for control values.

Results:

A significant decline in levels of BDNF was observed after in stroke. BDNF levels in patients (with different risk factors) with diabetes, hypertension and DM+ HTN, alcohol, and smoking history were 8.8 ± 4.04 ng/mL, 8.86 ± 4.68 ng/mL, 8.65 ± 3.26 ng/mL, 8.51 ± 4.26 ng/mL, and 8.9 ± 3.4 ng/mL, respectively. A decline in BDNF levels was observed in accordance with the severity of stroke in both ischemic and hemorrhagic stroke with the least level being in severe stroke (NIHSS >15 and ICH >3). Despite the type of stroke and the presence of risk factors, a significant improvement in BDNF levels and FIM scale scores was seen in all subjects who received PNF exercises.

Conclusion:

Thus, PNF is efficient in improving functional level in acute stroke irrespective of the type of stroke and risk factors.

Brain-derived neurotrophic factor levels in acute stroke and its clinical implications

BACKGROUND:

Brain-derived neurotrophic factor (BDNF) has a very important role in repairing intact and injured brain, also known as neuroplasticity. Risk factors may affect neuroplasticity.

OBJECTIVES:

In this study, our aim was to delineate the levels of BDNF in acute stroke with different etiology and impact of risk factors on its levels.

METHODS:

In this prospective study, 208 patients with first-ever stroke, between 18 and 75 years, were included. All individuals were assessed for severity and type of stroke, risk factors, levels of BDNF in the acute stroke, and its association with outcome of stroke.

RESULTS:

The mean age of the patients in our study was 55.29 ± 11.6 years. Compared to healthy controls, a significant decline in the levels of BDNF was observed after stroke (P < 0.01). Patients with National Institutes of Health Stroke Scale (NIHSS) <6 on the 1^st day of stroke had significantly higher levels of BDNF than those with NIHSS >6 (9.8 ng/ml ± 3.8; P < 0.01). A significant difference in the levels of BDNF was observed on comparing the stroke patients and healthy individuals of age <55 and >55 years (<55 years: 10.4 ng/ml ± 3.2; >55 years: 9.8 ng/ml ± 4.5 and in healthy individuals <55 years: 22.97 ± 3.8, >55 years: 15.4 ± 4.9; P < 0.01). Risk factors have negative impact on levels of BDNF (diabetics, P = 0.001; alcoholics, P = 0.003; both diabetes mellitus + hypertension, P = 0.002; smokers, P = 0.001). The difference was not significant between hypertensives and nonhypertensives (P = 0.06).

CONCLUSION:

BDNF level is significantly reduced in acute stroke. The presence of risk factors further affects its level.

Serum BDNF's Role as a Biomarker for Motor Training in the Context of AR-Based Rehabilitation after Ischemic Stroke

BACKGROUND

brain-derived neurotrophic factor (BDNF) may play a role during neurorehabilitation following ischemic stroke. This study aimed to elucidate the possible role of BDNF during early recovery from ischemic stroke assisted by motor training.

METHODS

fifty patients were included after acute recovery from ischemic stroke: 21 first received classical rehabilitation followed by 'motor rehabilitation using motion sensors and augmented reality' (AR-rehabilitation), 14 only received AR-rehabilitation, and 15 were only observed. Serum BDNF levels were measured on the first day of stroke, on the 14th day, before AR-based rehabilitation (median, 45th day), and after the AR-based rehabilitation (median, 82nd day). Motor impairment was quantified clinically using the Fugl-Meyer scale (FMA); functional disability and activities of daily living (ADL) were measured using the Modified Rankin Scale (mRS). For comparison, serum BDNF was measured in 50 healthy individuals.

RESULTS

BDNF levels were found to significantly increase during the phase with AR-based rehabilitation. The pattern of the sequentially measured BDNF levels was similar in the treated patients. Untreated patients had significantly lower BDNF levels at the endpoint.

CONCLUSIONS

the fluctuations of BDNF levels are not consistently related to motor improvement but seem to react to active treatment. Without active rehabilitation treatment, BDNF tends to decrease.

Post-Stroke Cognitive Impairment: A Review Focusing on Molecular Biomarkers

Post-stroke cognitive impairment (PSCI), as one of the major complications after stroke, refers to a series of syndromes from mild cognitive impairment to dementia caused by stroke. Stroke has been reported to increase the risk of cognitive impairment by at least five to eight times. The assessment of PSCI usually relies on neuropsychological tests, but the results of these tests are subjective and inaccurate, and can be insufficient for the diagnosis and prognosis of PSCI. In recent years, an increasing number studies have indicated that changes in the expression of biomarkers such as C-reactive protein (CRP), interleukin 6 (IL-6) and IL-10 in blood, urine and other body fluids are associated with cognitive decline after stroke. Therefore, the detection of biomarkers in circulating blood serum, plasma and cerebrospinal fluid (CSF) may improve the accuracy of diagnosis and prognosis in PSCI. This review aims to summarize the studies on potential molecular biomarkers of PSCI.

Association of High Serum Levels of Growth Factors with Good Outcome in Ischemic Stroke: a Multicenter Study

The main objective of this research work was to study the association of serum levels of growth factors (GF) and SDF-1α with the functional outcome and reduction of lesion volume in ischemic stroke patients. In this multicenter study, 552 patients with non-lacunar stroke (male, 62.1%; mean age, 68.2 ± 11.4) were included within 24 h from symptom onset. The main outcome variable was good functional outcome (modified Rankin Scale [mRS] ≤ 2) at 12 months. Secondary outcome variable was infarct volume (in mL) after 6 ± 3 months. Serum levels of VEGF, Ang-1, G-CSF, BDNF, and SDF-1α were measured by ELISA at admission, 7 ± 1 days, at 3 ± 1 months, and 12 ± 3 months. Except for BDNF, all GF and SDF-1α serum levels showed a peak value at day 7 and remained elevated during the first 3 months (all p < 0.01). High serum levels at day 7 of VEGF (OR, 19.3), Ang-1 (OR, 14.7), G-CSF (OR, 9.6), and SDF-1α (OR, 28.5) were independently associated with good outcome at 12 months (all p < 0.0001). On the other hand, serum levels of VEGF (B, − 21.4), G-CSF (B, − 14.0), Ang-1 (B, − 13.3), and SDF-1α (B, − 44.6) measured at day 7 were independently associated with lesion volume at 6 months (p < 0.01). In summary, high serum levels of VEGF, Ang-1, G-CSF, and SDF-1α at day 7 and 3 months after ischemic stroke are associated with good functional outcome and smaller residual lesion at 1 year of follow-up.

Novel Evidence of the Increase in Angiogenic Factor Plasma Levels after Lineage-Negative Stem/Progenitor Cell Intracoronary Infusion in Patients with Acute Myocardial Infarction

Cell therapy raises hope to reduce the harmful effects of acute myocardial ischemia. Stem and progenitor cells (SPCs) may be a valuable source of trophic factors. In this study, we assessed the plasma levels of selected trophic factors in patients undergoing application of autologous bone marrow (BM)-derived, lineage-negative (Lin^-) stem/progenitor cells into the coronary artery in the acute phase of myocardial infarction. The study group consisted of 15 patients with acute myocardial infarction (AMI) who underwent percutaneous revascularization and, afterwards, Lin^- stem/progenitor cell administration into the infarct-related artery. The control group consisted of 19 patients. BM Lin^- cells were isolated using immunomagnetic methods. Peripheral blood was collected on day 0, 2, 4, and 7 and after the first and third month to assess the concentration of selected trophic factors using multiplex fluorescent bead-based immunoassays. We found in the Lin^- group that several angiogenic trophic factors (vascular endothelial growth factor, Angiopoietin-1, basic fibroblast growth factor, platelet-derived growth factor-aa) plasma level significantly increased to the 4th day after myocardial infarction. In parallel, we noticed a tendency where the plasma levels of the brain-derived neurotrophic factor were increased in the Lin^- group. The obtained results suggest that the administered SPCs may be a valuable source of angiogenic trophic factors for damaged myocardium, although this observation requires further in-depth studies.

Protective properties of the aqueous extract of saffron (Crocus sativus L.) in ischemic stroke, randomized clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Crocus sativus L. has been used throughout the world in traditional medicine as a treatment for neurological disorders such as depression. Growing attention is currently being paid to the use of neuroprotective agents in ischemic strokes.

AIM OF THE STUDY

This study assed the effect of saffron as a neuroprotective natural product in cerebral ischemia in human.

STUDY DESIGN

Patients with acute ischemic stroke were randomly allocated to receive either routine stroke care (control group, n = 20) or routine care plus aqueous extract of saffron capsule (200 mg/day) (saffron-treated group, n = 19). Both groups were monitored during their four-day hospital stay and the three-month follow-up period. The groups were compared in terms of short- and long-term effects of saffron capsules using the National Institute of Health Stoke Scale (NIHSS), Barthel Scale, and serum neuron specific enolase (NSE), Brain-derived neurotrophic factor (BDNF), S100 levels.

RESULTS

Based on the NIHSS, the severity of stroke during the first four days was significantly lower in the saffron-treated group than in the control group (P < 0.05). Compared to the levels on the first day, serum NSE and s100 levels were significantly decreased and BDNF concentration was increased in the saffron-treated group on the fourth day. Also, our results showed there was a negative significant non-linear cubic regression between BDNF concentration and score of NIHSS. At the end of the three-month follow-up period, the mean Barthel index was significantly higher in the saffron-treated group than in the control group (P < 0.001).

CONCLUSION

The results of this study confirmed the short and long-term neuroprotective effects of aqueous extract of saffron on ischemic stroke in humans.

Serum levels of insulin-like growth factor-1 and brain-derived neurotrophic factor as potential recovery biomarkers in stroke

OBJECTIVES

Our objectives were: 1) to determine whether maximal aerobic exercise increased serum neurotrophins in chronic stroke and 2) to determine the factors that predict resting and exercise-dependent levels.

METHODS

We investigated the potential predictors of resting and exercise-dependent serum insulin-like growth factor-1 and brain-derived neurotrophic factor among 35 chronic stroke patients. Predictors from three domains (demographic, disease burden, and cardiometabolic) were entered into 4 separate stepwise linear regression models with outcome variables: resting insulin-like growth factor, resting brain-derived neurotrophic factor, exercise-dependent change in insulin-like growth factor, and exercise-dependent change brain-derived neurotrophic factor.

RESULTS

Insulin-like growth factor decreased after exercise (p = 0.001) while brain-derived neurotrophic factor did not change (p = 0.38). Greater lower extremity impairment predicted higher resting brain-derived neurotrophic factor (p = 0.004, r² = 0.23). Higher fluid intelligence predicted greater brain-derived neurotrophic factor response to exercise (p = 0.01, r² = 0.18). There were no significant predictors of resting or percent change insulin-like growth factor-1.

DISCUSSION

Biomarkers have the potential to characterize an individual's potential for recovery from stroke. Neurotrophins such as insulin-like growth factor-1 and brain-derived neurotrophic factor are thought to be important in neurorehabilitation; however, the factors that modulate these biomarkers are not well understood. Resting brain-derived neurotrophic factor and percent change in brain-derived neurotrophic factor were related to physical and cognitive recovery in chronic stroke, albeit weakly. Insulin-like growth factor-1 was not an informative biomarker among chronic stroke patients. The novel finding that fluid intelligence positively correlated with exercise-induced change in brain-derived neurotrophic factor warrants further research.

Brain-derived neurotrophic factor in peripheral blood mononuclear cells and stroke outcome

Stroke outcome is dependent on brain-derived neurotrophic factor (BDNF)-dependent neuroplasticity. As peripheral blood mononuclear cells (PBMC) contain BDNF, diapedesis of these cells might be followed by BDNF delivery to the ischemic brain. To test this hypothesis, we investigated the association between BDNF levels in PBMC and functional outcome in patients with ischemic stroke. BDNF was measured in PBMC that were isolated from ischemic stroke patients ( n = 40) just before (day 0) and after (days 1 and 3) fibrinolysis. Three months after stroke, patients were stratified using the modified Rankin Scale (mRS) according to the unfavorable (mRS scores 3–6) and favorable (mRS scores 0–2) functional outcome. We used univariate and multivariate logistic regressions to assess the relationship between BDNF levels in PBMC and functional outcome. BDNF levels in PBMC decreased from day 0 to day 3 in patients with unfavorable outcome, while they remained stable in patients with favorable outcome. Patients with favorable outcome exhibited at day 3 higher PBMC-BDNF levels than patients with unfavorable outcome and the levels were associated with good outcome (odd ratio: 12.0; 95% confidence interval, 1.4–106.2, P = 0.023). PBMC-BDNF levels remained a predictor of stroke outcome after adjusting from cardiovascular risk, interval between admission and fibrinolysis, stroke severity from hospital admission to discharge, lymphocytes count, neutrophils/lymphocytes ratio at admission. Favorable functional outcome in ischemic stroke patients that benefited from fibrinolysis was predicted by a high BDNF level in PBMC, suggesting that PBMC might serve as a cellular vector to deliver BDNF to the ischemic brain.

Impact statement

There are a great number of arguments suggesting that BDNF could be involved in stroke recovery dependent of neuroplasticity. Methods that can enhance BDNF levels in the ischemic brain could therefore have great clinical value. Peripheral blood mononuclear cells (PBMC) that contain BDNF and infiltrate early and sustainably the ischemic brain might be used as a cellular vector to deliver BDNF to the ischemic brain and consequently promote recovery. This work is important in this field to show if this BDNF derived from BDNF could exert a positive action on stroke recovery. Our main results showed that a high BDNF level at day 3 after hospital admission was associated with a 12.4 fold increase in favorable outcome after adjusting for still recognized prognostic markers. The new information in this field is this finding identifies PBMC as an attractive cellular vector to deliver BDNF to the ischemic brain.

Depressive symptoms in stroke patients treated and non-treated with intravenous thrombolytic therapy: a 1-year follow-up study

INTRODUCTION

This is a prospective study, first to compare the frequency of depressive symptoms in stroke survivors treated, and non-treated, with intravenous thrombolysis and second, to explore relationships between post-stroke depression (PSD) and stroke treatment modalities, taking into account other possible determinants of PSD, including post-traumatic stress symptoms.

METHODS

Groups of 73 thrombolysed and 73 non-thrombolysed patients matched for age and gender were examined at 3 and 12 months after discharge. PSD was assessed using the Beck Depression Inventory. Post-traumatic stress symptoms (PTSS), disability and social support were assessed with the Impact of Event Scale-Revised, the Barthel Index and the Berlin Social Support Scale.

RESULTS

At 3 months, PSD was present in 23.3% of the thrombolysed and 31.5% in the non-thrombolysed groups (p = 0.265). At 12 months, the frequencies were 29.2 and 20.6% (p = 0.229). Logistic regression of the combined group of thrombolysed and non-thrombolysed patients indicated that at 3 months, the adjusted predictors of PSD were disability (OR 24.35), presence of PTSS (OR 9.32), low social support (OR 3.68) and non-thrombolytic treatment (OR 3.19). At 12 months, the predictors were disability (OR 15.78) and low education (OR 3.61).

LIMITATIONS

The use of a questionnaire for the detection of depression, the relatively small sample size and a significant drop-out rate could limit the interpretation of these results.

CONCLUSIONS

(1) Thrombolysed and non-thrombolysed stroke survivors had similar frequency of depressive symptoms although the thrombolysed patients had more severe neurological deficits in the acute phase. It can be assumed that if thrombolysis had not been used, depressive symptoms would have been more frequent. (2) Lack of the rt-PA treatment was associated with three-time greater odds of screening for PSD at 3 months post-stroke, after adjustment for other PSD correlates. (3) Therefore, thrombolytic therapy seems to have a positive, but indirect, effect on patients' mood, especially in the first months after stroke. (4) All stroke patients, irrespective of the method of treatment, should be monitored for the presence of depression.

Circulating biomarkers in extremely preterm infants associated with ultrasound indicators of brain damage

AIM

To assess to what extent the blood concentrations of proteins with neurotrophic and angiogenic properties measured during the first postnatal month convey information about the risk of sonographically-identified brain damage among very preterm newborns.

METHODS

Study participants were 1219 children who had a cranial ultrasound scan during their stay in the intensive care nursery and blood specimens collected on 2 separate days at least a week apart during the first postnatal month. Concentrations of selected proteins in blood spots were measured with electrochemiluminescence or with a multiplex immunobead assay and the risks of cranial ultrasound images associated with top-quartile concentrations were assessed.

RESULTS

High concentrations of multiple inflammation-related proteins during the first 2 postnatal weeks were associated with increased risk of ventriculomegaly, while high concentrations of just 3 inflammation-related proteins were associated with increased risk of an echolucent/hypoechoic lesion (IL-6, IL-8, ICAM-1), especially on day 7. Concomitant high concentrations of IL6R and bFGF appeared to modulate the increased risks of ventriculomegaly and an echolucent lesion associated with inflammation. More commonly high concentrations of putative protectors/repair-enhancers did not appear to diminish these increased risks.

CONCLUSION

Our findings provide support for the hypothesis that endogenous proteins are capable of either protecting the brain against damage and/or enhancing repair of damage.

Association between brain-derived neurotrophic factor and von Willebrand factor levels in patients with stable coronary artery disease

Background

Brain-derived neurotrophic factor (BDNF) is a neurotrophin involved in angiogenesis and maintenance of endothelial integrity. Whether circulating BDNF levels are associated with von Willebrand factor (vWF) levels, which are indicators of endothelial dysfunction is not known. This study investigated the association between plasma BNDF and vWF levels and whether these biomarkers could predict cardiovascular events at a 12-month follow-up in patients with stable coronary artery disease (CAD).

Methods

We recruited 234 patients with suspected angina pectoris. Subjects were divided into CAD (n = 143) and control (n = 91) groups based on coronary angiography. Plasma BDNF and vWF levels were measured using ELISA. Patients were followed-up for one year, and information on adverse cardiac events was collected.

Results

CAD patients exhibited significantly lower plasma BDNF and higher vWF levels than those of control patients. High vWF levels were associated with low BDNF levels even after adjustment for age, gender, low-density lipoprotein (LDL) levels, and the presence of diabetes mellitus. A receiver operating characteristic curve was used to determine whether low BDNF and high vWF levels could predict adverse cardiovascular events. The area under the curve for vWF and the inverse of BDNF were 0.774 and 0.804, respectively.

Conclusions

These findings suggest that endothelial dysfunction is an important determinant of the impaired circulating BDNF levels, and they further reflected cardiovascular prognosis in stable CAD patients.

Systemic Inflammation during the First Postnatal Month and the Risk of Attention Deficit Hyperactivity Disorder Characteristics among 10 year-old Children Born Extremely Preterm

Although multiple sources link inflammation with attention difficulties, the only human study that evaluated the relationship between systemic inflammation and attention problems assessed attention at age 2 years. Parent and/or teacher completion of the Childhood Symptom Inventory-4 (CSI-4) provided information about characteristics that screen for attention deficit hyperactive disorder (ADHD) among 793 10-year-old children born before the 28th week of gestation who had an IQ ≥ 70. The concentrations of 27 proteins in blood spots obtained during the first postnatal month were measured. 151 children with ADHD behaviors were identified by parent report, while 128 children were identified by teacher report. Top-quartile concentrations of IL-6R, TNF-α, IL-8, VEGF, VEFG-R1, and VEGF-R2 on multiple days were associated with increased risk of ADHD symptoms as assessed by a teacher. Some of this increased risk was modulated by top-quartile concentrations of IL-6R, RANTES, EPO, NT-4, BDNF, bFGF, IGF-1, PIGF, Ang-1, and Ang-2. Systemic inflammation during the first postnatal month among children born extremely preterm appears to increase the risk of teacher-identified ADHD characteristics, and high concentrations of proteins with neurotrophic properties appear capable of modulating this increased risk.

Molecular mechanisms of brain-derived neurotrophic factor in neuro-protection: Recent developments

Neuronal cell injury, as a consequence of acute or chronic neurological trauma, is a significant cause of mortality around the world. On a molecular level, the condition is characterized by widespread cell death and poor regeneration, which can result in severe morbidity in survivors. Potential therapeutics are of major interest, with a promising candidate being brain-derived neurotrophic factor (BDNF), a ubiquitous agent in the brain which has been associated with neural development and may facilitate protective and regenerative effects following injury. This review summarizes the available information on the potential benefits of BDNF and the molecular mechanisms involved in several pathological conditions, including hypoxic brain injury, stroke, Alzheimer's disease and Parkinson's disease. It further explores the methods in which BDNF can be applied in clinical and therapeutic settings, and the potential challenges to overcome.

Association of lower serum Brain-derived neurotrophic factor levels with larger infarct volumes in acute ischemic stroke

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a potential role in stroke recovery, as it promotes plasticity. The aim of this study is to investigate the association between infarct volume using DWI and BDNF at admission in patients with acute ischemic stroke (AIS).

METHODS

The study population comprised consecutive patients with an AIS diagnosis who had been referred to our hospital between January 2015 and June 2016. The severity of stroke was evaluated by the National Institutes of Health Stroke Scale (NIHSS) at admission. Infarct volumes indicated by DWI were measured with MIPAV software. The relationship between median DWI infarct volume and serum BDNF level quartiles was evaluated using a semiparametric approach with univariate and multivariate quartile regression analysis.

RESULTS

In this study, 270 patients were included and met the study criteria. The median DWI infarct volumes for the serum BDNF level quartiles (lowest to highest) were 10.56, 5.13, 3.75 and 2.43ml. Nonparametric Spearman rank correlation revealed a statistically significant negative correlation between serum BDNF level and DWI infarct volume (r=-0.363; P<0.001). The median DWI infarct volume in the lowest BDNF quartile was significantly larger than those in the upper 3 quartiles (P<0.001). Further, median adjusted DWI infarct volumes (IQR) for each of the BDNF level quartiles were 7.77, 4.56, 3.75, and 2.43ml from lowest to highest quartiles.

CONCLUSIONS

Larger stroke infarct volumes using DWI are associated with lower levels of BDNF at admission. Further investigations are suggested to elucidate the role of BDNF as part of a potential neuroprotective strategy.

Decreased Brain-Derived Neurotrophic Factor Serum Concentrations in Chronic Post-Stroke Subjects

BACKGROUND

Brain-derived neurotrophic factor (BDNF) plays a critical role in sensorimotor recovery after a stroke. However, few studies have assessed the circulating BDNF levels in post-stroke humans to understand its changes. This study was conducted to measure BDNF serum concentrations in subjects with chronic hemiparesis, as well as to correlate serum concentrations with age, post-stroke time, total score of Stroke Specific Quality of Life Scale (SS-QOL), mobility subscale score, and motor function of SS-QOL.

METHODS

Seventeen chronic post-stroke subjects matched by age and gender with healthy controls took part in the study. Personal data (age, hemiparesis side, and post-stroke time) were collected, and a physical examination (weight, height, body mass index) and SS-QOL assessment were carried out. On the same day, after the initial evaluation, venous blood samples were collected from the chronic post-stroke subjects and the healthy subjects. The BDNF serum concentrations were measured blindly by enzyme-linked immunosorbent assay.

RESULTS

Subjects with chronic hemiparesis presented a decrease in BDNF serum compared with healthy subjects (P < .01). There was no correlation between BDNF serum levels with post-stroke time, age or quality of life, mobility, and the upper extremity motor function (P > .05). BDNF concentrations are related to structural and functional recovery after stroke; thus, this reduction is important to understand the rehabilitation process more clearly. However, more studies are needed considering the genetic variations and other tools to assess motor impairment and functional independence.

CONCLUSION

Chronic post-stroke subjects presented a decrease in BDNF serum concentrations, without a correlation with post-stroke time, age, and quality of life.