Brain-Derived Neurotrophic Factor (BDNF) and Translocator Protein (TSPO) as Diagnostic Biomarkers for Acute Ischemic Stroke

Dysregulation of proBDNF/p75NTR and BDNF/TrkB Signaling in Acute Ischemic Stroke: Different Sides of the Same Coins

Acute ischemic stroke (AIS) is a focal neurological deficit due to sudden occlusion of cerebral vessels in the brain. AIS-induced neuronal injury and associated excite-toxicity and neurodegeneration affect the synthesis and the release of different neurotrophic factors such as brain-derived neurotropic factor (BDNF) and its precursor proBDNF. Both BDNF and proBDNF act on the specific receptors with different neurological effects. BDNF activates tropomyosin receptor kinase B (TrkB) receptor results in promoting neuronal survival, synaptic plasticity, and neuronal growth. However, the proBDNF activates p75 neurotrophin receptor (p75NTR) and sortilin which attenuates synaptic plasticity and promotes neuronal apoptosis. Dysregulation of central and peripheral expression of proBDNF/BDNF is linked with the severity and clinical outcomes of AIS. Therefore, this review aims to discuss the alterations of proBDNF/BDNF signaling in AIS. Findings from the present review illustrated that proBDNF/p75NTR/sortilin signaling pathway is exaggerated whereas; BDNF-TrkB signaling is reduced in AIS leading to neuronal apoptosis. Therefore, activation of BDNF-TrkB signaling, and inhibition of proBDNF/p75NTR/sortilin signaling pathway could be a promising therapeutic strategy in the management of AIS.

Association between miR-30 polymorphism and ischemic stroke in Chinese population

BACKGROUND

Ischemic stroke (IS) is a commonly seen cerebrovascular disease which seriously endangers the health of middle age and old people. However, its etiology and pathogenesis have not yet fully comprehended. miR-30 gene is a novel gene which may be involved in IS. However, no studies have investigated the relationship between IS and the single-nucleotide polymorphisms (SNPs) of miR-30. Therefore, this study examined the relationship between miR-30 polymorphisms (rs2222722, rs1192037, rs10095483 and rs16827546) and the risk of IS.

METHODS

Totally 248 IS patients and 230 age-, sex- and race-matched controls were involved in this study. Based on SNPscan technique, four polymorphisms (rs2222722, rs1192037, rs10095483 and rs16827546) were genotyped.

RESULTS

There exists a significant association between rs2222722 polymorphism and the risk of IS according to analyses of genotypes, models and alleles (GA vs. GG: adjusted OR = 1.616, 95% CI: 0.943-2.768, P = 0. 081); (AA vs. GG: adjusted OR = 2.447, 95% CI: 1.233-4.858, P = 0.011); dominant model: adjusted (OR = 1.806, 95% CI, 1.082-3.016, P = 0.024); (G vs. A: adjusted OR = 1.492, 95% CI: 1.148-1.939, P = 0.003). Besides, miR-30a expression was significantly higher in patients undergoing IS relative to that in controls (P < 0.05).

CONCLUSIONS

To conclude, the rs2222722 polymorphism of the miR-30 gene shows a significant relationship to elevate the risk of IS in Chinese population.

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

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

[Validation of a C57/BL6J mouse model of focal cerebral ischemia established by electrocoagulation of the middle cerebral artery]

OBJECTIVE

To modify the method for establishing mouse models of middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia using electrocoagulation.

METHODS

Forty-six C57/BL6J male mice were divided into MCAO model group (n=34) and sham-operated group (n=12). In the model group, MCAO was induced by permanent coagulation of the right middle cerebral artery (MCA) using a coagulator, and cerebral blood flow perfusion was monitored before and at 20 min and 1 day after modeling. Neurological deficits of the mice at 1, 7, and 14 days after modeling were evaluated using Longa score, mNSS score, beam walking test, cylinder test and corner test. TTC staining was used to measure the cerebral infarct size, and Western blotting was performed to detect the expressions of BDNF, GFAP and DCX proteins in the ischemic cortex.

RESULTS

The mice in the model group showed significantly reduced cerebral blood flow in the MCA on the ischemic side and obvious neurological deficits with increased forelimb use asymmetry on days 1, 7 and 14 after modeling (P < 0.05). In the cerebral cortex on the ischemic side of the model mice, the expressions of GFAP and DCX increased significantly at 1, 7, and 14 days (P < 0.05) and the expression of BDNF increased at 1 day after modeling ischemia (P < 0.05).

CONCLUSION

We successfully prepared mouse models of MCAO using a modified method by changing the electrocoagulation location from the distal location of the junction between the MCA and the inferior cerebral vein to a 2 mm segment medial to the junction between the MCA and the olfactory bundle.

Brain-Heart Axis: Brain-Derived Neurotrophic Factor and Cardiovascular Disease-A Review of Systematic Reviews

BACKGROUND

The brain-heart axis is an intra- and bidirectional complex that links central nervous system dysfunction and cardiac dysfunction. In recent decades, brain-derived neurotrophic factor (BDNF) has emerged as a strategic molecule involved in both brain and cardiovascular disease (CVD). This systematic review of systematic reviews aimed to (1) identify and summarize the evidence for the BDNF genotype and BDNF concentration in CVD risk assessment, (2) evaluate the evidence for the use of BDNF as a biomarker of CVD recovery, and (3) evaluate rehabilitation approaches that can restore BDNF concentration.

METHODS

A comprehensive search strategy was developed using PRISMA. The risk of bias was assessed via ROBIS.

RESULTS

Seven studies were identified, most of which aimed to evaluate the role of BDNF in stroke patients. Only two systematic reviews examined the association of BDNF concentration and polymorphism in CVDs other than stroke.

CONCLUSIONS

The overall evidence showed that BDNF plays a fundamental role in assessing the risk of CVD occurrence, because lower BDNF concentrations and rs6265 polymorphism are often associated with CVD. Nevertheless, much work remains to be carried out in current research to investigate how BDNF is modulated in different cardiovascular diseases and in different populations.