BDNF Val66Met polymorphism is associated with unstable angina

The BDNF Val66Met polymorphism serves as a potential marker of body weight in patients with psychiatric disorders

Brain-derived neurotrophic factor (BDNF) is a predominant neurotrophic factor in the brain, indispensable for neuronal growth, synaptic development, neuronal repair, and hippocampal neuroplasticity. Among its genetic variants, the BDNF Val66Met polymorphism is widespread in the population and has been associated with the onset and aggravation of diverse pathologies, including metabolic conditions like obesity and diabetes, cardiovascular ailments, cancer, and an array of psychiatric disorders. Psychiatric disorders constitute a broad category of mental health issues that influence mood, cognition, and behavior. Despite advances in research and treatment, challenges persist that hinder our understanding and effective intervention of these multifaceted conditions. Achieving and maintaining stable body weight is pivotal for overall health and well-being, and the relationship between psychiatric conditions and body weight is notably intricate and reciprocal. Both weight gain and loss have been linked to varying mental health challenges, making the disentanglement of this relationship critical for crafting holistic treatment strategies. The BDNF Val66Met polymorphism's connection to weight fluctuation in psychiatric patients has garnered attention. This review investigated the effects and underlying mechanisms by which the BDNF Val66Met polymorphism moderates body weight among individuals with psychiatric disorders. It posits the polymorphism as a potential biomarker, offering prospects for improved monitoring and therapeutic approaches for mental illnesses.

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.

Associations of the BDNF Val66Met Polymorphism With Body Composition, Cardiometabolic Risk Factors, and Energy Intake in Youth With Obesity: Findings From the HEARTY Study

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is functionally related to BDNF, and is associated with obesity and metabolic complications in adults, but limited research exists among adolescents. This study comparatively examined carriers and non-carriers of the BDNF Val66Met polymorphism on body composition, energy intake, and cardiometabolic profile among adolescents with obesity. The sample consisted of 187 adolescents with obesity; 99 were carriers of the homozygous Val (G/G) alleles and 88 were carriers of the Val/Met (G/A) or Met (A/A) alleles. Cardiometabolic profile and DNA were quantified from fasted blood samples. Body composition was assessed by magnetic resonance imaging (MRI). Compared to carriers of the homozygous Val (G/G) allele, carriers of the Val/Met (G/A) or Met/Met (A/A) variants exhibited significantly higher protein (p = 0.01) and fat (p = 0.05) intake, C-Reactive protein (p = 0.05), and a trend toward higher overall energy intake (p = 0.07), fat-free mass (p = 0.07), and lower HDL-C (p = 0.07) Results showed for the first time that among youth with obesity, carriers of the Val66Met BDNF Met-alleles exhibited significantly higher C-reactive protein and energy intake in the form of fat and protein compared to Val-allele carriers, thereby providing support for the possible role of BDNF in appetite, weight, and metabolic regulation during adolescence. Clinical Trial Registration: http://clinicaltrials.gov/, identifier NCT00195858.

An Integrative Review of Brain-Derived Neurotrophic Factor and Serious Cardiovascular Conditions

BACKGROUND

There is emerging evidence that supports a role for brain-derived neurotrophic factor (BDNF) in the risk and presence of serious cardiovascular conditions. However, few existing literature reviews methodically describe empirical findings regarding this relationship.

OBJECTIVES

The purpose of this integrative review was to (a) evaluate BDNF (serum/plasma BDNF levels, BDNF Val66Met genotype) among humans at risk for or with serious cardiovascular conditions and (b) investigate the relationship between BDNF and risk/presence of serious cardiovascular conditions in humans.

METHODS

An integrative review was conducted. Articles in English included human subjects, a measure of BDNF levels or BDNF gene, serious cardiovascular conditions, and quantitative data analyses. The search resulted in 475 unique titles, with the final sample including 35 articles representing 30 studies. Articles that received "good" or "fair" ratings (n = 31) using the National Heart, Lung, and Blood Institute Study Quality Assessment Tools were included for synthesis.

RESULTS

The retrieved articles were largely nonexperimental, with sample sizes ranging from 20 to 5,510 participants. Overall, BDNF levels were lower in patients with chronic heart failure and stroke, but higher in patients with unstable angina and recent myocardial infarction. Lower BDNF levels were associated with higher incidence of cardiovascular events in patients with a prior history of serious cardiovascular conditions and decreased cardiovascular risk in healthy samples. For BDNF genotype, on average, 36.3% of participants had Met alleles. The frequency of the BDNF Met allele varied across race/ethnicity and cardiovascular conditions and in terms of association with serious cardiovascular condition incidence/risk.

DISCUSSION

These findings indicate an emerging area of science. Future investigation is needed on serious cardiovascular condition phenotypes in relationship to BDNF in the same study conditions. Results also suggest for use of standardized BDNF measurement across studies and additional investigation in cardiovascular inflammatory processes that affect BDNF. Moreover, within specific populations, the frequency of Met alleles may be too low to be detected in sample sizes normally found in these types of studies.

The genetics of circulating BDNF: towards understanding the role of BDNF in brain structure and function in middle and old ages

Brain-derived neurotrophic factor (BDNF) plays an important role in brain development and function. Substantial amounts of BDNF are present in peripheral blood, and may serve as biomarkers for Alzheimer’s disease incidence as well as targets for intervention to reduce Alzheimer’s disease risk. With the exception of the genetic polymorphism in the BDNF gene, Val66Met, which has been extensively studied with regard to neurodegenerative diseases, the genetic variation that influences circulating BDNF levels is unknown. We aimed to explore the genetic determinants of circulating BDNF levels in order to clarify its mechanistic involvement in brain structure and function and Alzheimer’s disease pathophysiology in middle-aged and old adults. Thus, we conducted a meta-analysis of genome-wide association study of circulating BDNF in 11 785 middle- and old-aged individuals of European ancestry from the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES), the Framingham Heart Study (FHS), the Rotterdam Study and the Study of Health in Pomerania (SHIP-Trend). Furthermore, we performed functional annotation analysis and related the genetic polymorphism influencing circulating BDNF to common Alzheimer’s disease pathologies from brain autopsies. Mendelian randomization was conducted to examine the possible causal role of circulating BDNF levels with various phenotypes including cognitive function, stroke, diabetes, cardiovascular disease, physical activity and diet patterns. Gene interaction networks analysis was also performed. The estimated heritability of BDNF levels was 30% (standard error = 0.0246, P-value = 4 × 10⁻⁴⁸). We identified seven novel independent loci mapped near the BDNF gene and in BRD3, CSRNP1, KDELC2, RUNX1 (two single-nucleotide polymorphisms) and BDNF-AS. The expression of BDNF was associated with neurofibrillary tangles in brain tissues from the Religious Orders Study and Rush Memory and Aging Project (ROSMAP). Seven additional genes (ACAT1, ATM, NPAT, WDR48, TTC21A, SCN114 and COX7B) were identified through expression and protein quantitative trait loci analyses. Mendelian randomization analyses indicated a potential causal role of BDNF in cardioembolism. Lastly, Ingenuity Pathway Analysis placed circulating BDNF levels in four major networks. Our study provides novel insights into genes and molecular pathways associated with circulating BDNF levels and highlights the possible involvement of plaque instability as an underlying mechanism linking BDNF with brain neurodegeneration. These findings provide a foundation for a better understanding of BDNF regulation and function in the context of brain aging and neurodegenerative pathophysiology.

Interaction between BDNF val66met polymorphism and personality on long-term cardiac outcomes in patients with acute coronary syndrome

Background

The prognostic role of BDNF val66met polymorphism on long-term cardiac outcomes in acute coronary syndrome (ACS) has been unclear. Environmental factors may modify the association, but these have not been investigated to date. This study aimed to investigate the potential interactive effects of BDNF val66met polymorphism and personality traits, one of the main environmental prognostic factors of ACS, on major adverse cardiac events (MACEs) in patients with ACS.

Methods

A total of 611 patients with recent ACS were recruited at a university hospital in Korea. Baseline evaluations from 2007 to 2012 assessed BDNF val66met polymorphism and personality using the Big Five Inventory, which yielded two personality clusters (resilient and vulnerable) and five dimensions (extraversion, agreeableness, conscientiousness, neuroticism, and openness). Over a 5~12 year follow-up after the index ACS, times to MACE were investigated using Cox regression models after adjustment for a range of covariates.

Results

The BDNF val66met polymorphism modified the associations between vulnerable personality type and worse long-term cardiac outcomes in ACS patients with significant interaction terms, in that the associations were statistically significant in the presence met allele. Similar findings were observed for the individual personality dimensions of agreeableness and neuroticism.

Conclusions

Gene (BDNF val66met polymorphism) x environment (personality traits) interactions on long-term cardiac outcomes were found in ACS.

Critical Issues in BDNF Val66Met Genetic Studies of Neuropsychiatric Disorders

Neurotrophins have been implicated in the pathophysiology of many neuropsychiatric diseases. Brain-derived neurotrophic factor (BDNF) is the most abundant and widely distributed neurotrophin in the brain. Its Val66Met polymorphism (refSNP Cluster Report: rs6265) is a common and functional single-nucleotide polymorphism (SNP) affecting the activity-dependent release of BDNF. BDNF Val66Met transgenic mice have been generated, which may provide further insight into the functional impact of this polymorphism in the brain. Considering the important role of BDNF in brain function, more than 1,100 genetic studies have investigated this polymorphism in the past 15 years. Although these studies have reported some encouraging positive findings initially, most of the findings cannot be replicated in following studies. These inconsistencies in BDNF Val66Met genetic studies may be attributed to many factors such as age, sex, environmental factors, ethnicity, genetic model used for analysis, and gene–gene interaction, which are discussed in this review. We also discuss the results of recent studies that have reported the novel functions of this polymorphism. Because many BDNF polymorphisms and non-genetic factors have been implicated in the complex traits of neuropsychiatric diseases, the conventional genetic association-based method is limited to address these complex interactions. Future studies should apply data mining and machine learning techniques to determine the genetic role of BDNF in neuropsychiatric diseases.

BDNFVal66met polymorphism: a potential bridge between depression and thrombosis

Aims

Epidemiological studies strongly suggest a link between stress, depression, and cardiovascular diseases (CVDs); the mechanistic correlation, however, is poorly understood. A single-nucleotide polymorphism in the BDNF gene (BDNFVal66Met), associated with depression and anxiety, has been proposed as a genetic risk factor for CVD. Using a knock-in mouse carrying the BDNFVal66Met human polymorphism, which phenocopies psychiatric-related symptoms found in humans, we investigated the impact of this SNP on thrombosis.

Methods and results

BDNFMet/Met mice displayed a depressive-like phenotype concomitantly with hypercoagulable state and platelet hyperreactivity. Proteomic analysis of aorta secretome from BDNFMet/Met and wild-type (WT) mice showed differential expression of proteins involved in the coagulation and inflammatory cascades. The BDNF Met allele predisposed to carotid artery thrombosis FeCl3-induced and to death after collagen/epinephrine injection. Interestingly, transfection with BDNFMet construct induced a prothrombotic/proinflammatory phenotype in WT cells. SIRT1 activation, using resveratrol and/or CAY10591, prevented thrombus formation and restored the physiological levels of coagulation and of platelet markers in BDNFMet/Met mice and/or cells transfected with the Met allele. Conversely, inhibition of SIRT1 by sirtinol and/or by specific siRNA induced the prothrombotic/proinflammatory phenotype in WT mice and cells. Finally, we found that BDNF Met homozygosity is associated with increased risk of acute myocardial infarction (AMI) in humans.

Conclusion

Activation of platelets, alteration in coagulation pathways, and changes in vessel wall protein expression in BDNFMet/Met mice recapitulate well the features occurring in the anxiety/depression condition. Furthermore, our data suggest that the BDNFVal66Met polymorphism contribute to the individual propensity for arterial thrombosis related to AMI.

Significant association between functional microRNA polymorphisms and coronary heart disease susceptibility: a comprehensive meta-analysis involving 16484 subjects

Molecular epidemiological studies suggest that microRNA polymorphisms may be associated with an increased risk of coronary heart disease (CHD). However, the results of these studies were inconsistent and inconclusive. To derive a more precise evaluation, we performed a meta-analysis focused on the associations between microRNA polymorphisms and CHD risk. PubMed, Embase, CNKI and Wanfang databases were searched. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the association between microRNA-146a rs2910164, microRNA-196a2 rs11614913, microRNA-499 rs3746444 and microRNA-149 rs71428439 polymorphisms and CHD susceptibility. Heterogeneity, publication bias and sensitivity analysis were conducted to measure the robustness of our findings. A total of thirteen related studies involving 8,120 patients and 8,364 controls were analyzed. Significant associations between microRNA-146a rs2910164 polymorphism and CHD risk were observed in the total population, as well as in subgroup analysis. For microRNA-196a2 rs11614913 and microRNA-499 rs3746444, similarly increased risks were also found. In addition, no significant association was detected between microRNA-149 rs71428439 polymorphism and CHD risk. In conclusion, our meta-analyses suggest that microRNA polymorphisms may be associated with increased risk of CHD development.

Brain-derived neurotrophic factor rs6265 (Val66Met) polymorphism is associated with disease severity and incidence of cardiovascular events in a patient cohort

BACKGROUND

The rs6265 (Val66Met) single-nucleotide polymorphism in the BDNF gene has been related to a number of endophenotypes that have in turn been shown to confer risk for atherosclerotic cardiovascular disease (CVD). To date, however, very few studies have examined the association of the Val66Met single-nucleotide polymorphism with CVD clinical outcomes.

METHODS

In a cohort of 5,510 Caucasian patients enrolled in the CATHeterization GENetics (CATHGEN) study at Duke University Hospital between 2001 and 2011, we determined the severity of coronary artery disease (CAD) and CVD event incidence through up to 11.8years of follow-up. We examined the association of Val66Met genotype with time-to-death or myocardial infarction, adjusting for age, sex, CAD risk variables, and CAD severity measures.

RESULTS

The Val/Val genotype was associated with a higher risk than Met carriers for clinical CVD events (P=.034, hazard ratio 1.12, 95% CI 1.01-1.24). In addition, compared with Met carriers, individuals with the Val/Val genotype had a greater odds of having more diseased vessels (odds ratio 1.17, 95% CI 1.06-1.30, P=.002), and lower left ventricular ejection fraction (β=-0.72, 95% CI, -1.42 to -0.02, P=.044).

CONCLUSIONS

The Val/Val genotype was associated with greater severity of CAD and incidence of CVD-related clinical events in a patient sample. If these findings are confirmed in further research, intervention studies in clinical groups with the Val/Val genotype could be undertaken to prevent disease and improve prognosis.

The synergistic effect of vascular cell adhesion molecule-1 and coronary artery disease on brain-derived neurotrophic factor

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is important for neural protection and energy homeostasis. In this study, we examined the effects of vascular cell adhesion molecule-1 (VCAM-1) and coronary artery disease (CAD) on BDNF.

METHODS

Subjects who had undergone diagnostic angiography for angina were recruited, and a total of 240 subjects (144 with CAD and 96 without CAD) were enrolled. Serum BDNF was determined at 0, 30, and 120min during an oral glucose tolerance test (OGTT) to calculate the area under the curve (AUC) for BDNF. Serum VCAM-1 was determined at fasting.

RESULTS

Significantly lower AUC of BDNF (42.8±10.7 vs. 47.4±11.7ng-h/ml, P=0.002) and higher serum VCAM-1 (583±383 vs. 482±171ng/ml, P=0.017) were noted in subjects with CAD compared to those without CAD. High VCAM-1 level was an independent predictor of low AUC of BDNF in subjects with and without CAD (95%CI between -0.011 and -0.002, P=0.008; -0.033 and -0.002, P=0.029, respectively). Serum BDNF was lowest in the CAD subjects with high VCAM-1 levels at all time points during OGTT.

CONCLUSION

Our results showed that CAD was associated with low serum BDNF in response to OGTT, and VCAM-1 had a synergistic effect with CAD on the BDNF.

Lack of an association of BDNF Val66Met polymorphism and plasma BDNF with hippocampal volume and memory

Brain-derived neurotrophic factor (BDNF) has been shown to be important for neuronal survival and synaptic plasticity in the hippocampus in nonhuman animals. The Val66Met polymorphism in the BDNF gene, involving a valine (Val) to methionine (Met) substitution at codon 66, has been associated with lower BDNF secretion in vitro. However, there have been mixed results regarding associations between either circulating BDNF or the BDNF Val66Met polymorphism with hippocampal volume and memory in humans. The current study examined the association of BDNF genotype and plasma BDNF with hippocampal volume and memory in two large independent cohorts of middle-aged and older adults (both cognitively normal and early-stage dementia). Sample sizes ranged from 123 to 649. Measures of the BDNF genotype, plasma BDNF, MRI-based hippocampal volume, and memory performance were obtained from the Knight Alzheimer Disease Research Center (ADRC) and the Alzheimer's Disease Neuroimaging Initiative (ADNI). There were no significant differences between BDNF Met+ and Met- groups on either hippocampal volume or memory in either cohort. In addition, plasma BDNF was not significantly associated with either hippocampal volume or memory in either cohort. Neither age, cognitive status, nor gender moderated any of the relationships. Overall, current findings suggest that BDNF genotype and plasma BDNF may not be robust predictors for variance in hippocampal volume and memory in middle age and older adult cohorts.

Reduced severity of posttraumatic stress disorder associated with Val allele of Val66Met polymorphism at brain-derived neurotrophic factor gene among Chinese adolescents after Wenchuan earthquake

The aim of the present study was to longitudinally investigate the association of BDNF Val66Met with PTSD symptoms in Chinese Han adolescents who experienced the 2008 Wenchuan earthquake. Variants of BDNF Val66Met were identified by polymerase chain reaction-restriction fragment length polymorphism analyses and verified by DNA sequencing. PTSD symptoms were assessed by the PTSD Checklist-Civilian Version (PCL-C) among high school students at 6, 12, and 18 months after the earthquake. No differences of PTSD prevalence and PCL-C scores were found between the Val/Val homozygotes and the Met allele carriers at 6, 12, and 18 months after the earthquake regardless of gender. Decreased PTSD prevalence was observed at 12 and 18 months when compared with that at 6 months after the earthquake regardless of gender and the genotype. Meanwhile, PCL-C scores were decreased consecutively in the female subjects regardless of the genotypes. However, the scores at 18 months were lower when compared with those at 12 months in the male Val/Val homozygotes, but not in the male Met allele carriers. In addition, differences were found for the predictors of PCL-C scores and PTSD prevalence between the Val/Val homozygotes and the Met allele carriers during follow-up. These findings suggest that the association of BDNF Val66Met with PTSD is longitudinally different in Chinese Han adolescents after the 2008 Wenchuan earthquake. The Val allele may be associated with reduced PTSD severity in male adolescents in the later stage of PTSD rehabilitation during follow-up.

Protective Effects of BDNF against C-Reactive Protein-Induced Inflammation in Women

Background. Since high sensitivity C-reactive protein (hsCRP) is predictive of cardiovascular events, it is important to examine the relationship between hsCRP and other inflammatory and oxidative stress markers linked to cardiovascular disease (CVD) etiology. Previously, we reported that hsCRP induces the oxidative stress adduct 8-oxo-7,8-dihydro-2′deoxyguanosine (8-oxodG) and that these markers are significantly associated in women. Recent data indicates that brain-derived neurotrophic factor (BDNF) may have a role in CVD. Methods and Results. We examined BDNF levels in 3 groups of women that were age- and race-matched with low (<3 mg/L), mid (>3–20 mg/L), and high (>20 mg/L) hsCRP (n = 39 per group) and found a significant association between hsCRP, BDNF, and 8-oxodG. In African American females with high hsCRP, increases in BDNF were associated with decreased serum 8-oxodG. This was not the case in white women where high hsCRP was associated with high levels of BDNF and high levels of 8-oxodG. BDNF treatment of cells reduced CRP levels and inhibited CRP-induced DNA damage. Conclusion. We discovered an important relationship between hsCRP, 8-oxodG, and BDNF in women at hsCRP levels >3 mg/L. These data suggest that BDNF may have a protective role in counteracting the inflammatory effects of hsCRP.

Dramatic intracerebral hemorrhagic presentations of reversible cerebral vasoconstriction syndrome: three cases and a literature review

Reversible cerebral vasoconstriction syndrome (RCVS) refers to a number of disorders characterized by severe and sudden-onset (“thunderclap”) headaches and angiographic features of reversible, segmental, multifocal vasoconstriction of cerebral arteries. Although RCVS generally resolves without significant sequelae, a rare and possibly underrecognized hemorrhagic presentation has a worse potential course. We report three cases of hemorrhagic RCVS and review the literature. Three females (42, 54, and 33 years old, resp.) presented with severe headache, neurological deficits, and dramatic intracerebral hemorrhage (ICH). Patient 1 presented comatose with a 9 × 4 × 6.6 cm left deep intraparenchymal hemorrhage (IPH) and 1 cm midline shift. She underwent emergent surgical intervention. Patient 2 had a 3.3 × 1.5 cm left superior frontal IPH that enlarged to 4 × 2.5 cm within 12 hours with worsening headache and neurological deficits. She was successfully managed nonoperatively. Patient 3, after uncomplicated pregnancy and delivery, presented with a 1.5 cm left superior parietal IPH on postpartum day 7. Two days later, she acutely developed right hemiplegia. Repeat CT demonstrated a new 3.3 × 1.7 cm left frontal IPH. She was also successfully managed nonoperatively. Many diverse conditions are grouped within the category of RCVS. Dramatic ICH remains a rare and possibly underrecognized presenting feature. Prompt diagnosis and management are essential for obtaining the best outcome.

Genetics of serum BDNF: meta-analysis of the Val66Met and genome-wide association study

OBJECTIVES

Lower levels of serum brain derived neurotrophic factor (BDNF) is one of the best known biomarkers of depression. To identify genetic variants associated with serum BDNF, we tested the Val66Met (rs6265) functional variant and conducted a genome-wide association scan (GWAS).

METHODS

In a community-based sample (N = 2054; aged 19-101, M = 51, SD = 15) from Sardinia, Italy, we measured serum BDNF concentration and conducted a GWAS.

RESULTS

We estimated the heritability of serum BDNF to be 0.48 from sib-pairs. There was no association between serum BDNF and Val66Met in the SardiNIA sample and in a meta-analysis of published studies (k = 13 studies, total n = 4727, P = 0.92). Although no genome-wide significant associations were identified, some evidence of association was found in the BDNF gene (rs11030102, P = 0.001) and at two loci (rs7170215, P = 4.8 × 10⁻⁵ and rs11073742 P = 1.2 × 10⁻⁵) near and within NTRK3 gene, a neurotrophic tyrosine kinase receptor.

CONCLUSIONS

Our study and meta-analysis of the literature indicate that the BDNF Val66Met variant is not associated with serum BDNF, but other variants in the BDNF and NTRK3 genes might regulate the level of serum BDNF.

Brain-derived neurotrophic factor G196A polymorphism predicts 90-day outcome of ischemic stroke in Chinese: a novel finding

BACKGROUND AND PURPOSE

Recovery after stroke varies considerably between individuals. An abundance of evidence suggests that genetic factors contribute to stroke recovery. The aim of this study was to determine whether or not the BDNF G196A polymorphism independently influences the occurrence, severity, and 90-day functional outcome in Chinese patients with ischemic stroke (IS).

METHODS

BDNF G196A genetic variants were investigated in 494 IS and 346 controls. Severity was assessed by the National Institutes of Health Stroke Scale at the time of admission. Three hundred and eight patients were assessed 90 days post-stroke using the Modified Rankin Scale to determine stroke outcome.

RESULTS

We showed that a significant association existed between the BDNF G196A AA genotype and the occurrence of IS (P=0.021), even after adjustment for covariates (P=0.028). The AA genotype of the BDNF G196A was associated with a poor outcome of recovery 3 months after stroke onset (P=0.008) was a novel finding, independent of other known predictors of poor outcome (P=0.012).

CONCLUSIONS

The BDNF G196A polymorphism was significantly associated with the occurrence and long-term outcomes of IS, thus BDNF G196A may be used as a prognostic biomarker and therapeutic target in IS.

Impaired cognition in bipolar I disorder: the roles of the serotonin transporter and brain-derived neurotrophic factor

BACKGROUND

Studies have proposed that cognitive deficits are present in a variety of mood states in bipolar disorder (BD). The goal of this study was to find the cognitive deficits in euthymic BD patients and to further explore possible underlying mechanisms of the deficits.

METHODS

Thirty-three healthy controls (HCs) and twenty-three euthymic BD type I patients were recruited. Single photon emission computed tomography (SPECT) with (123)I-ADAM was used to image the serotonin transporter (SERT). Ten milliliters of venous blood was drawn for the measurement of brain derived neurotrophic factor (BDNF). Cognitive functions were tested included attention, memory, and executive function.

RESULTS

We found that the SERT availability in both the midbrain and striatal regions was decreased in the BD patients compared with the HCs; however, the BDNF were not different between the two groups. There was no correlation between the SERT availability and the BDNF. Interestingly, there were statistically significant differences in sub-items of the facial memory test and the Wisconsin Card Sorting Test between the BD patients and the HCs, which showed that there was a cognitive deficit in the BD patients. However, the overall deficits in cognition were not significantly correlated with the SERT availability or the BDNF.

LIMITATION

The effect of medications on cognitive function and BDNF should be considered.

CONCLUSIONS

We replicated previous findings that showed cognitive deficits in euthymic BD patients. However, the underlying mechanism of cognitive deficits in euthymic BD patients cannot be entirely explained by SERT and BDNF.

Brain-derived neurotrophic factor not associated with metabolic syndrome but inversely correlated with vascular cell adhesion molecule-1 in men without diabetes

BACKGROUND

Excessive visceral fat with unbalanced adipokines is a critical pathogenic factor of metabolic syndrome (MetS), which is associated with disorders of the central nervous system and cardiovascular disease. Because brain-derived neurotrophic factor (BDNF) plays an important role in neurons, we examined the relationship of BDNF to MetS, adipose tissue and biomarkers in men.

METHODS

Thirty-four non-diabetic men with MetS and another 24 age-matched men without MetS were enrolled. In addition to fasting blood samples, the area of adipose tissue at the waist was assessed by magnetic resonance imaging (MRI).

RESULTS

There was no significant difference in serum BDNF concentrations between men with or without MetS (40.9±8.0 vs. 43.2±6.1 ng/ml, P=0.235). However, the serum concentration of soluble vascular cell adhesion molecule-1 (VCAM-1) was higher in the subjects with a lower BDNF level (737±230 vs. 628±115 ng/ml, P=0.025). An inverse correlation between VCAM-1 and BDNF was observed (r=-0.391, P=0.002). After adjusting for visceral adipose tissue, VCAM-1 was found to be independently associated with BDNF [95% confidence interval (-0.025, -0.005), P=0.004].

CONCLUSION

These data show no difference in serum BDNF levels between the men with MetS and controls. However, serum BDNF was inversely correlated with serum VCAM-1 in men without diabetes.

Val66Met polymorphism and serum brain-derived neurotrophic factor concentration in depressed patients

Zhang X, Wang X, Sha W, Zhou H, Zhang Y. Val66Met polymorphism and serum brain-derived neurotrophic factor concentration in depressed patients.

Objective: Accumulating evidence has suggested a pathophysiological role for brain-derived neurotrophic factor (BDNF) in major depressive disorder (MDD). The present study evaluated serum levels of BDNF and explored whether Val66Met BDNF gene polymorphism is correlated with changes in circulating BDNF levels in patients with MDD and control subjects.

Methods: Subjects were 76 patients with MDD and 50 controls. Diagnosis of MDD was determined by the use of a structured clinical interview according to Diagnostic and Statistical Manual of Mental Disorder-IV (DSM-IV) criteria. The concentrations of BDNF were measured by using the enzyme-linked immunosorbent assay. The Val66Met BDNF gene polymorphism was examined by the polymerase chain reaction technique.

Results: Serum BDNF was significantly lower in MDD patients than in normal control subjects (p < 0.001). There were no significant differences either in allele or genotype in the Val66Met polymorphism between the MDD and control groups. Moreover, genotype did not significantly correlate with the BDNF serum levels in the MDD or control groups.

Conclusions: Our study suggests that there is a decrease in serum BDNF levels in untreated MDD patients. However, serum BDNF levels were not associated with the Val66Met polymorphism.

A brain-derived neurotrophic factor polymorphism Val66Met identifies fibromyalgia syndrome subgroup with higher body mass index and C-reactive protein

A common single nucleotide polymorphism (SNP) in the gene of brain-derived neurotrophic factor (BDNF) results from a substitution at position 66 from valine (Val) to methionine (Met) and may predispose to human neuropsychiatric disorders. We proposed to determine whether these BDNF gene SNPs were associated with fibromyalgia syndrome (FMS) and/or any of its typical phenotypes. Patients with FMS (N = 95) and healthy normal controls (HNC, N = 58) were studied. Serum high-sensitivity C-reactive protein (hsCRP) levels were measured using an enzyme-linked immunosorbent assay (ELISA). The BDNF SNPs were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).The BDNF SNP distribution was 65 (68%) Val/Val, 28 (30%) Val/Met, and 2 (2%) Met/Met for FMS and 40 (69%), 17(29%), and 1 (2%) for HNC, respectively. The serum high-sensitivity C-reactive protein (hsCRP)and body mass index (BMI) in FMS were higher than in HNC. The FMS with BDNF Val66Val had significantly higher mean BMI (P = 0.0001) and hsCRP (P = 0.02) than did FMS carrying the Val66Met genotype. This pattern was not found in HNC. Phenotypic measures of subjective pain, pain threshold, depression, or insomnia did not relate to either of the BDNF SNPs in FMS. The relative distribution BDNF SNPs did not differ between FMS and HNC. The BDNF Val66Met polymorphism is not selective for FMS. The BDNF Val66Val SNP identifies a subgroup of FMS with elevated hsCRP and higher BMI. This is the first study to associate a BDNF polymorphism with a FMS subgroup phenotype.

Brain-derived neurotrophic factor gene Val66Met polymorphism modulates reversible cerebral vasoconstriction syndromes

Background

Reversible cerebral vasoconstriction syndrome (RCVS) could be complicated by cerebral ischemic events. Hypothetical mechanisms of RCVS involve endothelial dysfunction and sympathetic overactivity, both of which were reported to be related to brain-derived neurotrophic factor (BDNF). The study investigated the association between functional BDNF Val66Met polymorphism and RCVS.

Methods

Patients with RCVS and controls were prospectively recruited and genotyped for the BDNF Val66Met polymorphism. Magnetic resonance angiography (MRA) and transcranial color-coded Doppler sonography were employed to evaluate cerebral vasoconstriction. Genotyping results, clinical parameters, vasoconstriction scores, mean flow velocities of the middle cerebral artery (V_MCA), and Lindegaard indices were analyzed. Split-sample approach was employed to internally validate the data.

Principal Findings

Ninety Taiwanese patients with RCVS and 180 age- and gender-matched normal controls of the same ethnicity completed the study. The genotype frequencies did not differ between patients and controls. Compared to patients with Met/Met homozygosity, patients with Val allele had higher mean vasoconstriction scores of all arterial segments (1.60±0.72 vs. 0.87±0.39, p<0.001), V_MCA values (116.7±36.2 vs. 82.7±17.9 cm/s, p<0.001), and LI (2.41±0.91 vs. 1.89±0.41, p = 0.001). None of the Met/Met homozygotes, but 38.9% of the Val carriers, had V_MCA values of >120 cm/s (p<0.001). Split-sample validation by randomization, age, entry time or residence of patients demonstrated concordant findings.

Conclusions

Our findings link BDNF Val66Met polymorphism with the severity of RCVS for the first time and implicate possible pathogenic mechanisms for vasoconstriction in RCVS.

Decreased serum brain-derived neurotrophic factor (BDNF) is associated with post-stroke depression but not with BDNF gene Val66Met polymorphism

BACKGROUND

Decreased brain-derived neurotrophic factor (BDNF) has been demonstrated in animal models and patients with depression. However, little is known about changes in BDNF in post-stroke depression (PSD). This study investigated the changes in serum BDNF in patients with PSD, and evaluated whether serum concentrations of BDNF were associated with BDNF gene Val66Met polymorphism.

METHODS

PSD patients were diagnosed in accordance with DSM-IV criteria, and the severity of depression was evaluated with the Hamilton Rating Scale for depression. Serum BDNF was measured twice, first at 7 days after the onset of stroke and then at 3-6 months after stroke. Val66Met polymorphisms of the BDNF gene were determined using the polymerase chain reaction-restriction fragment length polymorphism method. BDNF concentrations and Val66Met polymorphisms were also measured in 30 healthly controls.

RESULTS

A total of 93 patients admitted as a result of first time acute ischemic stroke were included. During the 6-month follow-up, 35 patients (37.6%) were diagnosed with PSD. Serum BDNF concentrations were decreased in PSD patients at 3-6 months after stroke (p < 0.05). The serum BDNF concentrations were not associated with BDNF gene Val66Met polymorphisms in either patients or healthy controls.

CONCLUSIONS

Serum concentrations of BDNF decrease in PSD patients and BDNF may play an important role in the pathogenesis of PSD. However, Val66Met polymorphisms are not associated with serum concentrations of BDNF. The mechanism of decreased serum BDNF requires further study.

Transcriptional upregulation of brain-derived neurotrophic factor in rostral ventrolateral medulla by angiotensin II: significance in superoxide homeostasis and neural regulation of arterial pressure

RATIONALE

Oxidative stress in rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons for the maintenance of neurogenic vasomotor tone are located, contributes to neural mechanisms of hypertension. Emerging evidence suggests that brain-derived neurotrophic factor (BDNF) manifests "nontrophic" actions.

OBJECTIVE

We assessed the hypothesis that BDNF plays an active role in oxidative stress-associated neurogenic hypertension by maintaining superoxide anion (O⁻(.)₂) homeostasis in RVLM.

METHODS AND RESULTS

In Wistar-Kyoto rats, microinjection of angiotensin II (Ang II) bilaterally into RVLM upregulated BDNF mRNA and protein and induced cAMP response element binding protein (CREB) phosphorylation. The Ang II-induced BDNF upregulation in RVLM was attenuated by coadministration of the NADPH oxidase inhibitor apocynin; the superoxide dismutase mimetic tempol; or an antisense oligonucleotide against CREB. Intracisternal infusion of Ang II elicited phosphorylation of p47(phox) subunit of NADPH oxidase, suppression of mitochondrial electron coupling capacity, and augmentation in mitochondrial uncoupling protein (UCP)2 expression in RVLM. The former 2 cellular events were enhanced, whereas UCP2 upregulation was attenuated by gene knockdown of BDNF or depletion of tropomyosin receptor kinase (Trk)B ligands with recombinant human TrkB-Fc fusion protein. The same treatments also significantly potentiated both Ang II-induced (O⁻(.)₂) production in RVLM and chronic pressor response.

CONCLUSIONS

Ang II induces (O⁻(.)₂) -dependent upregulation of BDNF in RVLM via phosphorylation of CREB. The Ang II-activated BDNF/TrkB signaling, in turn, exerts negative-feedback regulation on tissue (O⁻(.)₂) level in RVLM through inhibition of p47(phox) phosphorylation, preservation of mitochondrial electron transport capacity, and upregulation of mitochondrial UCP2, resulting in protection against Ang II-induced oxidative stress and long-term pressor response.

Plasma BDNF concentration, Val66Met genetic variant and depression-related personality traits

Brain-derived neurotrophic factor (BDNF) regulates synaptic plasticity and neurogenesis, and BDNF plasma and serum levels have been associated with depression, Alzheimer's disease, and other psychiatric and neurodegenerative disorders. In a relatively large community sample, drawn from the Baltimore Longitudinal Study of Aging (BLSA), we examine whether BDNF plasma concentration is associated with the Val66Met functional polymorphism of the BDNF gene (n = 335) and with depression-related personality traits assessed with the NEO-PI-R (n = 391). Plasma concentration of BDNF was not associated with the Val66Met variant in either men or women. However, in men, but not in women, BDNF plasma level was associated with personality traits linked to depression. Contrary to the notion that low BDNF is associated with negative outcomes, we found lower plasma levels in men who score lower on depression and vulnerability to stress (two facets of Neuroticism) and higher on Conscientiousness and Extraversion. These findings challenge the prevailing hypothesis that lower peripheral levels of BDNF are a marker of depression.

Non-synonymous single-nucleotide polymorphisms associated with blood pressure and hypertension

In this study, we determined the association of 1180 non-synonymous single-nucleotide polymorphisms (SNPs) with systolic blood pressure (SBP) and hypertensive status. A total of 8842 subjects were taken from two community-based cohorts--Ansung (n=4183) and Ansan (n=4659), South Korea--which had been established for genome-wide association studies (GWAS). Five SNPs (rs16835244, rs2286672, rs6265, rs17237198 and rs7312017) were significantly associated (P-values: 0.003-0.0001, not corrected for genome-wide significance) with SBP in both cohorts. Of these SNPs, rs16835244 and rs2286672 correlated with risk for hypertension. The rs16835244 SNP replaces Ala288 in arginine decarboxylase (ADC) with serine, and rs2286672 replaces Arg172 in phospholipase D2 (PLD2) with cysteine. A comparison of peptide sequences between vertebrate homologues revealed that the SNPs identified occur at conserved amino-acid residues. In silico analysis of the protein structure showed that the substitution of a polar residue, serine, for a non-polar alanine at amino-acid residue 288 affects a conformational change in ADC, and that Arg172 in PLD2 resides in the PX domain, which is important for membrane trafficking. These results provide insights into the function of these non-synonymous SNPs in the development of hypertension. The study investigating non-synonymous SNPs from GWAS not only by statistical association analysis but also by biological relevance through the protein structure might be a good approach for identifying genetic risk factors for hypertension, in addition to discovering causative variations.

BDNF Val66Met polymorphism and protein levels in amniotic fluid

Background

Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which plays survival- and growth-promoting activity in neuronal cells and it is involved in cellular plasticity mechanisms as it controls activity dependent synaptic transmission. A functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF has been associated with memory and cognitive deficits as well as to an increased susceptibility for several psychiatric disorders especially those with a neurodevelopmental origin. To date, no study has evaluated the influence of the Val66Met polymorphism on BDNF levels in a peripheral system that may reflect fetal neurodevelopment. Therefore we investigated in amniotic fluids (AF) obtained from 139 healthy women during 15-17 week of pregnancy, BDNF protein levels in correlation with the Val66Met polymorphism.

Results

Interestingly we found a significant BDNF protein levels reduction in 55 Met carriers (Val/Met and Met/Met) (p = 0.002) as compared to 84 non carriers (Val/Val), and no effect of fetus gender, maternal age or gestation week on BDNF levels has been observed.

Conclusion

These results, although explorative, indicate that during fetal life the Val66Met genotype might influences BDNF protein levels in AF supporting the involvement of this polymorphism in behavioral and functional brain individual differences in the adulthood.

Serum brain-derived neurotrophic factor and platelet activation evaluated by soluble P-selectin and soluble CD-40-ligand in patients with acute myocardial infarction

Little is known about the role of neurotrophins (NT) under adult vascular homeostasis in normal and pathological conditions. The NT family, including nerve growth factor and brain-derived neurotrophic factor (BDNF) are expressed in atherosclerotic vessels. Previous studies demonstrated that plasma BDNF levels were increased in the coronary circulation in patients with unstable angina. However, the role of BDNF during the onset and evolution of unstable angina remains to be elucidated. The objective of this study was to evaluate the relationship between BDNF, functional parameters and biological markers associated with inflammatory processes and platelet activation. BDNF serum levels were assessed in patients with acute myocardial infarction (MI) (n = 20) or stable angina pectoris (SAP) (n = 20) who underwent coronary angiography. Serum levels of IL-6, MCP1, sVCAM, soluble CD-40-ligand (sCD40L) and soluble P-selectin (sP-selectin) were measured simultaneously by flux cytometry. Median BDNF levels were higher in the MI than in the SAP group (1730 vs. 877 pg/mL, respectively; P = 0.025). In MI patients, we observed a significant correlation between BDNF and sP-selectin (r = 0.58, P = 0.023), although we found a non-significant trend between BDNF and sCD40L (r = +0.35, P = 0.144). By contrast, no such correlation was observed in SAP patients (r = -0.22, P = 0.425). No difference was observed between the two groups regarding baseline demographics, risk factors, biological data and angiographic findings. The study suggests that BDNF serum levels in MI patients could be related to platelet activation and the inflammatory response. Further studies are needed to investigate the role of NT in the setting of acute MI.