Brain-derived Neurotrophic Factor Secretion Research Articles

The Val66Met BDNF Polymorphism and Peripheral Nerve Injury: Enhanced Regeneration in Mouse Met-Carriers Is Not Further Improved With Activity-Dependent Treatment

Activity-dependent treatments to enhance peripheral nerve regeneration after injury have shown great promise, and clinical trials implementing them have begun. Success of these treatments requires activity-dependent release of brain-derived neurotrophic factor (BDNF). A single nucleotide polymorphism (SNP) in the bdnf gene known as Val66Met, which is found in nearly one third of the human population, results in defective activity-dependent BDNF secretion and could impact the effectiveness of these therapies. Here, we used a mouse model of this SNP to test the efficacy of treadmill exercise in enhancing axon regeneration in animals both heterozygous (V/M) and homozygous (M/M) for the SNP. Axon regeneration was studied 4 weeks after complete transection and repair of the sciatic nerve in both male and female animals, using both electrophysiological and histological outcome measures. Regeneration was enhanced significantly without treatment in V/M mice, compared with wild type (V/V) controls. Unlike V/V mice, treatment of both V/M and M/M mice with treadmill exercise did not result in enhanced regeneration. These results were recapitulated in vitro using dissociated neurons containing the light-sensitive cation channel, channelrhodopsin. Three days after plating, neurites of neurons from V/M and M/M mice were longer than those of V/V neurons. In neurons from V/V mice, but not those from V/M or M/M animals, longer neurites were found after optogenetic stimulation. Taken together, Met-carriers possess an intrinsically greater capacity to regenerate axons in peripheral nerves, but this cannot be enhanced further by activity-dependent treatments.

The Epistasis Project: A Multi-Cohort Study of the Effects of BDNF, DBH, and SORT1 Epistasis on Alzheimer's Disease Risk.

Pre-synaptic secretion of brain-derived neurotrophic factor (BDNF) from noradrenergic neurons may protect the Alzheimer's disease (AD) brain from amyloid pathology. While the BDNF polymorphism (rs6265) is associated with faster cognitive decline and increased hippocampal atrophy, a replicable genetic association of BDNF with AD risk has yet to be demonstrated. This could be due to masking by underlying epistatic interactions between BDNF and other loci that encode proteins involved in moderating BDNF secretion (DBH and Sortilin). We performed a multi-cohort case-control association study of the BDNF, DBH, and SORT1 loci comprising 5,682 controls and 2,454 AD patients from Northern Europe (87% of samples) and Spain (13%). The BDNF locus was associated with increased AD risk (odds ratios; OR = 1.1-1.2, p = 0.005-0.3), an effect size that was consistent in the Northern European (OR = 1.1-1.2, p = 0.002-0.8) but not the smaller Spanish (OR = 0.8-1.6, p = 0.4-1.0) subset. A synergistic interaction between BDNF and sex (synergy factor; SF = 1.3-1.5 p = 0.002-0.02) translated to a greater risk of AD associated with BDNF in women (OR = 1.2-1.3, p = 0.007-0.00008) than men (OR = 0.9-1.0, p = 0.3-0.6). While the DBH polymorphism (rs1611115) was also associated with increased AD risk (OR = 1.1, p = 0.04) the synergistic interaction (SF = 2.2, p = 0.007) between BDNF (rs6265) and DBH (rs1611115) contributed greater AD risk than either gene alone, an effect that was greater in women (SF = 2.4, p = 0.04) than men (SF = 2.0, p = 0.2). These data support a complex genetic interaction at loci encoding proteins implicated in the DBH-BDNF inflammatory pathway that modifies AD risk, particularly in women.

Oligodendrocytes regulate presynaptic properties and neurotransmission through BDNF signaling in the mouse brainstem.

Neuron-glia communication contributes to the fine-tuning of synaptic functions. Oligodendrocytes near synapses detect and respond to neuronal activity, but their role in synapse development and plasticity remains largely unexplored. We show that oligodendrocytes modulate neurotransmitter release at presynaptic terminals through secretion of brain-derived neurotrophic factor (BDNF). Oligodendrocyte-derived BDNF functions via presynaptic tropomyosin receptor kinase B (TrkB) to ensure fast, reliable neurotransmitter release and auditory transmission in the developing brain. In auditory brainstem slices from Bdnf+/- mice, reduction in endogenous BDNF significantly decreased vesicular glutamate release by reducing the readily releasable pool of glutamate vesicles, without altering presynaptic Ca2+ channel activation or release probability. Using conditional knockout mice, cell-specific ablation of BDNF in oligodendrocytes largely recapitulated this effect, which was recovered by BDNF or TrkB agonist application. This study highlights a novel function for oligodendrocytes in synaptic transmission and their potential role in the activity-dependent refinement of presynaptic properties.

In silico analysis of the V66M variant of human BDNF in psychiatric disorders: An approach to precision medicine.

Brain-derived neurotrophic factor (BDNF) plays an important role in neurogenesis and synapse formation. The V66M is the most prevalent BDNF mutation in humans and impairs the function and distribution of BDNF. This mutation is related to several psychiatric disorders. The pro-region of BDNF, particularly position 66 and its adjacent residues, are determinant for the intracellular sorting and activity-dependent secretion of BDNF. However, it has not yet been fully elucidated. The present study aims to analyze the effects of the V66M mutation on BDNF structure and function. Here, we applied nine algorithms, including SIFT and PolyPhen-2, for functional and stability prediction of the V66M mutation. The complete theoretical model of BNDF was generated by Rosetta and validated by PROCHECK, RAMPAGE, ProSa, QMEAN and Verify-3D algorithms. Structural alignment was performed using TM-align. Phylogenetic analysis was performed using the ConSurf server. Molecular dynamics (MD) simulations were performed and analyzed using the GROMACS 2018.2 package. The V66M mutation was predicted as deleterious by PolyPhen-2 and SIFT in addition to being predicted as destabilizing by I-Mutant. According to SNPeffect, the V66M mutation does not affect protein aggregation, amyloid propensity, and chaperone binding. The complete theoretical structure of BDNF proved to be a reliable model. Phylogenetic analysis indicated that the V66M mutation of BDNF occurs at a non-conserved position of the protein. MD analyses indicated that the V66M mutation does not affect the BDNF flexibility and surface-to-volume ratio, but affects the BDNF essential motions, hydrogen-bonding and secondary structure particularly at its pre and pro-domain, which are crucial for its activity and distribution. Thus, considering that these parameters are determinant for protein interactions and, consequently, protein function; the alterations observed throughout the MD analyses may be related to the functional impairment of BDNF upon V66M mutation, as well as its involvement in psychiatric disorders.

Preconditioning of Human Dental Pulp Stem Cells with Leukocyte- and Platelet-Rich Fibrin-Derived Factors Does Not Enhance Their Neuroregenerative Effect.

Pathologies of the central nervous system are characterized by loss of brain tissue and neuronal function which cannot be adequately restored by endogenous repair processes. This stresses the need for novel treatment options such as cell-based therapies that are able to restore damaged tissue or stimulate repair. This study investigated the neuroregenerative potential of the conditioned medium of human dental pulp stem cells (CM-hDPSCs) on neural stem cell (NSC) proliferation and migration as well as on neurite outgrowth of primary cortical neurons (pCNs). Additionally, the effect of leukocyte- and platelet-rich fibrin (L-PRF) priming on the neuroregenerative potential of the hDPSC secretome on NSCs and pCNs was evaluated. L-PRF contains factors that enhance stem cell-induced regeneration, but its effect on hDPSC-mediated neuroregeneration is unknown. This study demonstrated that CM-hDPSCs enhanced neuritogenesis. Moreover, CM-hDPSCs had a chemoattractant effect on NSCs. Although priming hDPSCs with L-PRF increased brain-derived neurotrophic factor secretion, no additional effects on the paracrine-mediated repair mechanisms were observed. These data support the neuroregenerative potential of hDPSCs, and although priming had no additional effect, the potential of L-PRF-primed hDPSCs on distinct regenerative mechanisms remains to be clarified.

Dysregulation of the SNARE-binding protein Munc18-1 impairs BDNF secretion and synaptic neurotransmission: a novel interventional target to protect the aging brain.

Brain-derived neurotrophic factor (BDNF) has a central role in maintaining and strengthening neuronal connections and to stimulate neurogenesis in the adult brain. Decreased levels of BDNF in the aging brain are thought to usher cognitive impairment. BDNF is stored in dense core vesicles and released through exocytosis from the neurites. The exact mechanism for the regulation of BDNF secretion is not well understood. Munc18-1 (STXBP1) was found to be essential for the exocytosis of synaptic vesicles, but its involvement in BDNF secretion is not known. Interestingly, neurons lacking munc18-1 undergo severe degeneration in knock-out mice. Here, we report the effects of BDNF treatment on the presynaptic terminal using munc18-1-deficient neurons. Reduced expression of munc18-1 in heterozygous (+/-) neurons diminishes synaptic transmitter release, as tested here on individual synaptic connections with FM1-43 fluorescence imaging. Transduction of cultured neurons with BDNF markedly increased BDNF secretion in wild-type but was less effective in munc18-1 +/- cells. In turn, BDNF enhanced synaptic functions and restored the severe synaptic dysfunction induced by munc18-1 deficiency. The role of munc18-1 in the synaptic effect of BDNF is highlighted by the finding that BDNF upregulated the expression of munc18-1 in neurons, consistent with enhanced synaptic functions. Accordingly, this is the first evidence showing the functional effect of BDNF in munc18-1 deficient synapses and about the direct role of munc18-1 in the regulation of BDNF secretion. We propose a molecular model of BDNF secretion and discuss its potential as therapeutic target to prevent cognitive decline in the elderly.

NLRP3 inflammasome inhibition with MCC950 improves diabetes-mediated cognitive impairment and vasoneuronal remodeling after ischemia

Diabetes increases the risk and worsens the progression of cognitive impairment via the greater occurrence of small vessel disease and stroke. Yet, the underlying mechanisms are not fully understood. It is now accepted that cardiovascular health is critical for brain health and any neurorestorative approaches to prevent/delay cognitive deficits should target the conceptual neurovascular unit (NVU) rather than neurons alone. We have recently shown that there is augmented hippocampal NVU remodeling after a remote ischemic injury in diabetes. NLRP3 inflammasome signaling has been implicated in the development of diabetes and neurodegenerative diseases, but little is known about the impact of NLRP3 activation on functional and structural interaction within the NVU of hippocampus, a critical part of the brain that is involved in forming, organizing, and storing memories. Endothelial cells are at the center of the NVU and produce trophic factors such as brain derived neurotrophic factor (BDNF) contributing to neuronal survival, known as vasotrophic coupling. Therefore, the aims of this study focused on two hypotheses: 1) diabetes negatively impacts hippocampal NVU remodeling and worsens cognitive outcome after stroke, and 2) NLRP3 inhibition with MCC950 will improve NVU remodeling and cognitive outcome following stroke via vasotrophic (un)coupling between endothelial cells and hippocampal neurons. Stroke was induced through a 90-min transient middle cerebral artery occlusion (MCAO) in control and high-fat diet/streptozotocin-induced (HFD/STZ) diabetic male Wistar rats. Saline or MCC950 (3 mg/kg), an inhibitor of NLRP3, was injected at 1 and 3 h after reperfusion. Cognition was assessed over time and neuronal density, blood-brain barrier (BBB) permeability as well as NVU remodeling (aquaporin-4 [AQP4] polarity) was measured on day 14 after stroke. BDNF was measured in endothelial and hippocampal neuronal cultures under hypoxic and diabetes-mimicking condition with and without NLRP3 inhibition. Diabetes increased neuronal degeneration and BBB permeability, disrupted AQP4 polarity, impaired cognitive function and amplified NLRP3 activation after ischemia. Inhibition with MCC950 improved cognitive function and vascular integrity after stroke in diabetic animals and prevented hypoxia-mediated decrease in BDNF secretion. These results are the first to provide essential data showing MCC950 has the potential to become a therapeutic to prevent neurovascular remodeling and worsened cognitive decline in diabetic patients following stroke.

Abnormal TDP-43 function impairs activity-dependent BDNF secretion, synaptic plasticity, and cognitive behavior through altered Sortilin splicing.

Aberrant function of the RNA-binding protein TDP-43 has been causally linked to multiple neurodegenerative diseases. Due to its large number of targets, the mechanisms through which TDP-43 malfunction cause disease are unclear. Here, we report that knockdown, aggregation, or disease-associated mutation of TDP-43 all impair intracellular sorting and activity-dependent secretion of the neurotrophin brain-derived neurotrophic factor (BDNF) through altered splicing of the trafficking receptor Sortilin. Adult mice lacking TDP-43 specifically in hippocampal CA1 show memory impairment and synaptic plasticity defects that can be rescued by restoring Sortilin splicing or extracellular BDNF. Human neurons derived from patient iPSCs carrying mutated TDP-43 also show altered Sortilin splicing and reduced levels of activity-dependent BDNF secretion, which can be restored by correcting the mutation. We propose that major disease phenotypes caused by aberrant TDP-43 activity may be explained by the abnormal function of a handful of critical proteins, such as BDNF.

Microbiota and memory: A symbiotic therapy to counter cognitive decline?

The process of aging underlies many degenerative disorders that arise in the living body, including gradual neuronal loss of the hippocampus that often leads to decline in both memory and cognition. Recent evidence has shown a significant connection between gut microbiota and brain function, as butyrate production by microorganisms is believed to activate the secretion of brain-derived neurotrophic factor (BDNF). To investigate whether modification of intestinal microbiota could impact cognitive decline in the aging brain, Romo-Araiza et al. conducted a study to test how probiotic and prebiotic supplementation impacted spatial and associative memory in middle-aged rats. Their results showed that rats supplemented with the symbiotic (both probiotic and prebiotic) treatment performed significantly better than other groups in the spatial memory test, though not in that of associative memory. Their data also reported that this improvement correlated with increased levels of BDNF, decreased levels of pro-inflammatory cytokines, and better electrophysiological outcomes in the hippocampi of the symbiotic group. Thus, the results indicated that the progression of cognitive impairment is indeed affected by changes in microbiota induced by probiotics and prebiotics. Potential future applications of these findings center around combatting neurodegeneration and inflammation associated not only with aging but also with the damaging posttraumatic effects of ischemic stroke.

Repairing effect of Schwann cells combined with mesenchymal stem cells on optic nerve injury in rats.

To investigate the effect and the underlying mechanisms of combined transplantation of Schwann cells (Scs) and Mesenchymal stem cells (MSCs) on optic nerve injury in rats. A total of 160 normal healthy adult rats were randomly divided into 4 groups: optic nerve injury group, optic nerve injury + Sc transplantation group, optic nerve injury + MSC transplantation group and optic nerve injury + Sc + MSC transplantation group. The optic nerve in the left eye of each rat was damaged via clamping to establish a model of optic nerve injury, and the right eye was used as self-control. Scs + MSCs, Scs alone, MSCs alone and normal saline were injected into the vitreous space, respectively. After the treatment, the optic nerve tissues were collected and subjected to hematoxylin-eosin (HE) staining. Next, the morphologic and pathological changes of rats in each group were observed. Retrograde labeling was utilized to count the number of retinal ganglion cells (RGCs) in the optic nerve tissues. The apoptosis of RGCs was detected using flow cytometry. Western blot was carried out to measure the protein expression level of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax). The expression and distribution of brain-derived neurotrophic factor (BDNF) and growth associated protein-43 (GAP-43) in the optic nerve of rats in each group were detected by immunohistochemistry. Transplantation of Scs and MSCs could maintain the morphological structures of the retina and optic nerve of rats, increase the amount of RGCs in optic nerve tissues, reduce the apoptosis of RGCs, promote the expression of the Bcl-2 protein and decrease the expression of Bax protein. In addition, our joint transplantation strategy also showed an important role in repairing optic nerve injury by clearly promoting the secretion and expression of BDNF and GAP-43, which indicated a better curative effect than that of separate application of Scs or MSCs. Therapy with combined use of Scs and MSCs has a significant therapeutic effect in repairing optic nerve injury.

A Novel Peptide Interfering with proBDNF-Sortilin Interaction Alleviates Chronic Inflammatory Pain.

Rationale: Brain-derived neurotrophic factor (BDNF) is a key mediator in the development of chronic pain. Sortilin is known to interact with proBDNF and regulate its activity-dependent secretion in cortical neurons. In a rat model of inflammatory pain with intraplantar injection of complete Freund's adjuvant (CFA), we examined the functional role of proBDNF-sortilin interaction in dorsal root ganglia (DRG).Methods: Expression and co-localization of BDNF and sortilin were determined by immunofluorescence. ProBDNF-sortilin interaction interface was mapped using co-immunoprecipitation and bimolecular fluorescence complementation assay. The analgesic effect of intrathecal injection of a synthetic peptide interfering with proBDNF-sortilin interaction was measured in the CFA model.Results: BDNF and sortilin were co-localized and their expression was significantly increased in ipsilateral L4/5 DRG upon hind paw CFA injection. In vivo adeno-associated virus-mediated knockdown of sortilin-1 in L5 DRG alleviated pain-like responses. Mapping by serial deletions in the BDNF prodomain indicated that amino acid residues 71-100 supported the proBDNF-sortilin interaction. A synthetic peptide identical to amino acid residues 89-98 of proBDNF, as compared with scrambled peptide, was found to interfere with proBDNF-sortilin interaction, inhibit activity-dependent release of BDNF in vitro and reduce CFA-induced mechanical allodynia and heat hyperalgesia in vivo. The synthetic peptide also interfered with capsaicin-induced phosphorylation of extracellular signal-regulated kinases in ipsilateral spinal cord of CFA-injected rats.Conclusions: Sortilin-mediated secretion of BDNF from DRG neurons contributes to CFA-induced inflammatory pain. Interfering with proBDNF-sortilin interaction reduced activity-dependent release of BDNF and might serve as a therapeutic approach for chronic inflammatory pain.

Initial Assessment of Lactate as Mediator of Exercise-Induced Retinal Protection.

Physical exercise is protective in rodent models of retinal injury and disease. Data suggest that this is in part mediated by brain-derived neurotrophic factor (BDNF) signal transduction. It has been hypothesized that exercised-induced neuroprotection may be mediated by increases in circulating lactate that in turn alter BDNF secretion. We therefore tested whether mice undergoing a treadmill running regimen previously shown to be protective in a mouse model of retinal degeneration (RD) have increased serum levels of lactate. Lactate levels in exercised and non-exercised mice were statistically indistinguishable. A role for circulating lactate in exercise-induced retinal protection is unsupported.

The effect of lithium chloride on the motor function of spinal cord injury–controlled rat and the relevant mechanism

The objective of this study is to discuss the effect and mechanism of lithium chloride on the rehabilitation of locomotion post spinal cord injury (SCI) by observing the effect of lithium chloride on the expression of the brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) pathway. In total, 36 Sprague-Dawley (SD) rats were randomly divided into the sham operation group (n = 12), model group (n = 12), and lithium chloride group (n = 12). The sham operation group underwent laminectomy, while for the model group and the lithium chloride group with the NYU spinal cord impactor the SCI model was established. Basso, Beattie, and Bresnahan (BBB) score was used to evaluate locomotion after administration for 1, 3, 5, and 7 days, and the tissues were gathered for Nissl staining, transmission electron microscopy, immunofluorescence, and Western blot. With a statistical difference ( P < 0.05) on the 3rd day and significant difference ( P < 0.01) on the 5th day post administration, a higher BBB score was observed in the lithium chloride group indicating that lithium chloride improved the locomotion function after SCI. A better structure and morphology of neuron were observed by Nissl staining in the lithium chloride group. Lithium chloride promoted BDNF secretion from neurons in the spinal cord anterior horn with a significant difference compared to the model group ( P < 0.01). Compared with the model group, lithium chloride significantly promoted the expression of BDNF protein and phosphorylated TrkB protein ( P < 0.05), but no difference in the expression of TrkB was detected. Lithium chloride can alleviate the locomotion function after SCI with a mechanism that it can promote BDNF secretion from neurons in the spinal cord anterior horn and phosphorylation of TrkB to upregulate the BDNF/TrkB pathway supporting survival of neurons and regeneration and remyelination of axons.

High VEGF Level is Produced by Human Umbilical Cord- Mesenchymal Stem Cells (hUC-MSCs) in Amino Acid-Rich Medium and under Hypoxia Condition

BACKGROUND: Secretome production by stem cells depends on their culture conditions such as oxygen concentration and the composition of the culture media. In this study, we investigated the secretion of neurotrophic growth factors of human umbilical cord mesenchymal stem cells (hUC-MSCs) in amino acid-rich culture medium and under hypoxic condition.METHODS: hUC-MSCs were cultured in normoxic and various hypoxic (1%, 5%, 10%) conditions in an amino acid-rich culture medium. The end-point parameters (cell proliferation and survival, cell morphology and growth factor secretion) were measured at 3 time-points (48 hours, 72 hours and 96 hours). ELISA-based methods were used for neurotrophic factors detection, including neurotrophic growth factor (NGF), vascular endothelial factor (VEGF), and brain-derived neurotrophic factor (BDNF).RESULTS: NGF secretion was not detectable at any time points both in normoxia and hypoxia. BDNF secretion under normoxia was induced at 48 h time point and reached the highest level at an average of 181.9±13.01 pg/mL at 96 hours, whereas hypoxia exposure to hUC-MSCs only induced the BDNF secretion at low level. VEGF secretion was barely detectable in normoxic condition. However, VEGF secretion reached the highest level at an average of 7707.55±2110.85 pg/mL in 5% hypoxia at 96 hours.CONCLUSION: Combination of amino acid-rich culture medium and hypoxia condition dramatically induced high VEGF secretion by hUC-MSCs, especially at 5% hypoxia, induced mild BDNF secretion and had no effect toward NGF secretion.KEYWORDS: human umbilical cord mesenchymal stem cells, neurotrophic growth factor, amino acid-rich, hypoxia

Probiotics and Prebiotics as a Therapeutic Strategy to Improve Memory in a Model of Middle-Aged Rats.

Aging is associated with morphological, physiological and metabolic changes, leading to multiorgan degenerative pathologies, such as cognitive function decline. It has been suggested that memory loss also involves a decrease in neurotrophic factors, including brain-derived neurotrophic factor (BDNF). In recent years, microbiota has been proposed as an essential player in brain development, as it is believed to activate BDNF secretion through butyrate production. Thus, microbiota modulation by supplementation with probiotics and prebiotics may impact cognitive decline. This study aimed to evaluate the effects of probiotics and prebiotics supplementation on the memory of middle-aged rats. Sprague-Dawley male rats were randomized in four groups (n = 13 per group): control (water), probiotic (E. faecium), prebiotic (agave inulin), symbiotic (E. faecium + inulin), which were administered for 5 weeks by oral gavage. Spatial and associative memory was analyzed using the Morris Water Maze (MWM) and Pavlovian autoshaping tests, respectively. Hippocampus was obtained to analyze cytokines [interleukin (IL-1β) and tumor necrosis factor (TNF-α)], BDNF and γ-aminobutyric acid (GABA) by enzyme-linked immunosorbent assay (ELISA). Butyrate concentrations were also evaluated in feces. The symbiotic group showed a significantly better performance in MWM (p < 0.01), but not in Pavlovian autoshaping test. It also showed significantly lower concentrations of pro-inflammatory cytokines (p < 0.01) and the reduction in IL-1β correlated with a better performance of the symbiotic group in MWM (p < 0.05). Symbiotic group also showed the highest BDNF and butyrate levels (p < 0.0001). Finally, we compared the electrophysiological responses of control (n = 8) and symbiotic (n = 8) groups. Passive properties of CA1 pyramidal cells (PCs) exhibited changes in response to the symbiotic treatment. Likewise, this group showed an increase in the N-methyl-D-aspartate receptor (NMDA)/AMPA ratio and exhibited robust long-term potentiation (LTP; p < 0.01). Integrated results suggest that symbiotics could improve age-related impaired memory.

Brain-derived neurotrophic factor, insulin like growth factor-1 and inflammatory cytokine responses to continuous and intermittent exercise in patients with type 1 diabetes

AimsType 1 diabetes mellitus (T1DM) is an important risk factor for cognitive decline and motor dysfunction due to progressive muscular atrophy. Chronic hyperglycemia may be responsible for impaired vascular function, loss of muscle mass, and morphological abnormalities in the myocytes. For the proper functioning of the neuromuscular system, two crucial growth factors are necessary: brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1), whose reduced expressions have been implicated in progressive neuropathy and muscle atrophy in patients with T1DM.The aim of the study was to compare the effects of two different exercise regimes (continuous and intermittent) on BDNF, IGF-1, blood glucose and inflammatory cytokine responses in young adults with and without Type 1 diabetes. MethodsFourteen patients (aged: 26.9 years) with T1DM and age-matched adults without diabetes participated in a 40 min continuous exercise (ExC, 50% of lactate threshold) and a high intensity intermittent exercise (ExInt, 120% of lactate threshold). During the study the patients performed self-monitoring of blood glucose levels (SMBG) under glycemic control. The effects of ExC and ExInt on BDNF, IGF-1, insulin like growth factor binding protein (IGFBP-3), insulin (INS), vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-β) and tumor necrosis factor alpha (TNF-α) were analyzed. ResultsBDNF and IGF-1 baseline serum levels were significantly lower in the T1DM patients compared to the healthy controls, but we found that ExInt and ExC significantly increase the secretion of BDNF and IGF-1 levels. Significant increases in BDNF and TGF-β levels, higher blood glucose decline, and a lower incidence of hypoglycaemia in ExInt compared to ExC were observed. Lower IGFBP-3 concentrations were revealed in T1DM patients in response to ExInt compared to ExC, suggesting a positive effect on IGF-1/IGFBP-3 ratio and the bioavailability of IGF-1. ConclusionsAccording to our results physical exercise has beneficial effects on serum BDNF and IGF-1 levels. A high-intensity intermittent exercise may be more effective at reducing the risk of exercise-induced glycaemic disorders in the T1DM patients as compared to continuous exercise.

Design of a Novel Gene Therapy Construct to Achieve Sustained Brain-Derived Neurotrophic Factor Signaling in Neurons.

Brain-derived neurotrophic factor (BDNF) acting through the tropomyosin-related receptor-B (TrkB) is an important signaling system for the maintenance and survival of neurons. Gene therapy using either recombinant adeno-associated virus (AAV) or lentiviral vectors can provide sustained delivery of BDNF to tissues where reduced BDNF signaling is hypothesized to contribute to disease pathophysiology. However, elevation in BDNF at target sites has been shown to lead to a downregulation of TrkB receptors, thereby reducing the effect of chronic BDNF delivery over time. A novel gene sequence has been designed coding both the ligand (BDNF) and the TrkB receptor in a single transgene separated by a short viral-2A sequence. The single transgene is efficiently processed intracellularly in vitro and in vivo to yield the two mature proteins, which are then independently transported to their final cellular locations: TrkB receptors to the cell surface, and BDNF contained within secretory vesicles. To accommodate the coding sequences of both BDNF and TrkB receptors within the narrow confines of the AAV vectors (4.7 kb pairs), the coding region for the pro-domain of BDNF was removed and the signal peptide sequence modified to improve production, intracellular transport, and secretion of mature BDNF (mBDNF). Intracellular processing and efficacy was shown in HEK293 cells and SH-SY5Y neuroblastoma cells using plasmid DNA and after incorporating the TrkB-2A-mBDNF into an AAV2 vector. Increased BDNF/TrkB-mediated intracellular signaling pathways were observed after AAV2 vector transfection while increased TrkB phosphorylation could be detected in combination with neuroprotection from hydrogen peroxide–induced oxidative stress. Correct processing was also shown in vivo in mouse retinal ganglion cells after AAV2 vector administration to the eye. This novel construct is currently being investigated for its efficacy in animal models to determine its potential to progress to human clinical studies in the future.

Association of BDNF VAL66MET with post-stroke functional recovery

The Val66Met single nucleotide polymorphism (SNP rs6265) of the Brain-Derived Neurotrophic Factor ( BDNF ) gene decreases BDNF secretion. Previous studies in patients with stroke have shown that the Val66Met polymorphism is associated with poorer outcome. The aim of this study was to determine whether or not the BDNF Val66Met genotype is associated with functional outcome after stroke in our inpatient rehabilitation sample. One hundred and five individuals admitted for inpatient rehabilitation following a stroke and who were also enrolled in the Partners HealthCare Biobank. The genotypes for BDNF SNP rs6265 for individuals with stroke were obtained from the Partners HealthCare Biobank Portal. Main outcome measures were the Functional Independence Measure (FIM) on admission and discharge. Stroke outcome was defined as the change in FIM scores between discharge and admission. The prediction of motor and cognitive outcome at discharge was modeled using BDNF Val66Met genotype. Regression analyses were performed to identify the significant associations of the genetic factor with functional outcome. Individuals with stroke who were homozygous for the GG genotype had significantly lower FIM cognition subscale ( P = 0.023) and memory subscores ( P = 0.011) as compared to those with either the heterozygous AG or homozygouse AA genotypes. In addition, the GG genotype was a significant predictor for poor memory outcome ( P = 0.021, OR = −0.036 [B = −0.067 to −0.005]) when controlling for age and gender. This association may be due to the association with memory since the memory score is contained within the cognition subscale. The preliminary data suggests that BDNF Val66Met polymorphsim may impede stroke recovery, especially cognitive function. Further studies with larger samples are warranted to elucidate the role and mechanism of BDNF genetic variants in stroke recovery.

Poly(Adenosine Phosphate Ribose) Polymerase 1 Inhibition Enhances Brain-derived Neurotrophic Factor Secretion in Dental Pulp Stem Cell–derived Odontoblastlike Cells

IntroductionThe nuclear enzyme poly(adenosine phosphate ribose) polymerase 1 (PARP-1) has been implicated in the maintenance and differentiation of several stem cells. The role of PARP-1 in dental pulp stem cell (DPSC) differentiation, especially in the context of its ability to modulate nerve regeneration factors, has not been investigated. Regeneration of neuronal components in pulp tissue is important for the assessment of tooth vitality. Brain-derived neurotrophic factor (BDNF) is known to play an integral signaling factor during nerve regeneration. In this study, we identified the role of PARP-1 in the modulation of BDNF in DPSC differentiation into odontoblastlike cells. MethodsHuman DPSCs were prepared from healthy molars and cultured in regular and osteogenic media treated with PARP-1 antagonist and PARP-1 exogeneous protein. Polymerase chain reaction and immunohistochemistry analysis for BDNF and various differentiation markers were performed. ResultsOur polymerase chain reaction results showed that differentiated cells show odontoblastlike properties because they express odontogenic markers such as dentin sialophosphoprotein and dentin matrix protein 1. Both PARP-1 inhibitor and protein did not affect odontogenic differentiation and proliferation because the number of the differentiated cells was unaffected, and the expression of dentin sialophosphoprotein and dentin matrix protein 1 was not significantly changed. There is the possibility that PARP-1 treatment induces DPSCs into the unique cell lineage. Some differentiated cells show a very unique morphology with large irregular cytoplasm and an oval nucleus. Moreover, PARP-1 inhibition significantly increased BDNF secretion in DPSC-derived odontoblastlike cells. This observation was also confirmed by immunohistochemistry. ConclusionsTaken together, our results indicate PARP-1 as a negative regulator in BDNF secretion during odontogenic DPSC differentiation, showing its potential application for translational nerve regeneration strategies to improve dental pulp tissue vitality assessments.

Protective effect of transplantation of bone mesenchymal stem cells on demyelination in spinal cord injury

Bone mesenchymal stem cells (BMSCs) have been used worldwide to treat spinal cord injury, but their therapeutic mechanism is poorly understood. In this study, BMSCs were transplanted to aneurysm clip-injured rats to demonstrate their protective effect. We observed myelin sheaths through Luxol fast blue (LFB) staining, osmic acid staining, TUNEL and transmission electron microscopy (TEM). We performed Western blotting to analyze the expressions of brain-derived neurotrophic factor (BDNF) and caspase 3. BMSCs were transplanted at 1, 7 and 14 days after spinal cord injury. Hindlimb movement (Basso, Beattie and Bresnahan; BBB) score, CNPase (2', 3'-cyclic-nucleotide 3'-phosphodiesterase), myelin basic protein (MBP) and caspase 3 protein levels were detected. Immunofluorescence was used to test the differentiation of BMSCs after implanted into damaged spinal cord and co-expression of CNPase-caspase 3+. At 7 days after BMSCs transplantation, some injected BMSCs expressed neuronal and oligodendrocyte markers. And both locomotor skills and ultra-structural features of myelin sheaths were significantly improved. The expressions of BDNF were clearly increased by BMSCs transplantation, the expression of caspase 3 was the opposite. Compared with the 1 and 14 days transplantation after spinal cord injury, MBP and CNPase expressions were highest, caspase 3 expression was lowest in 7 days BMSCs transplantation. After BMSCs transplantation, CNPase-caspase 3+ cells scattered in the white matter of the spinal cord. Therefore, BMSCs had a tendency to differentiate into neurons and oligodendrocytes after transplantation, which could promote the secretion of BDNF. BMSCs protected neural myelin sheaths by inhibiting oligodendrocyte apoptosis via increased secretion of BDNF after SCI. The best therapeutic time was 7 days after spinal cord injury.