Repetitive Transcranial Magnetic Stimulation Alleviates Neurological Deficits After Cerebral Ischemia Through Interaction Between RACK1 and BDNF exon IV by the Phosphorylation-Dependent Factor MeCP2

The roles of RACK1 in the pathogenesis of Alzheimer's disease

The receptor for activated C kinase 1 (RACK1) is a protein that plays a crucial role in various signaling pathways and is involved in the pathogenesis of Alzheimer's disease (AD), a prevalent neurodegenerative disease. RACK1 is highly expressed in neuronal cells of the central nervous system and regulates the pathogenesis of AD. Specifically, RACK1 is involved in regulation of the amyloid-β precursor protein processing through α- or β-secretase by binding to different protein kinase C isoforms. Additionally, RACK1 promotes synaptogenesis and synaptic plasticity by inhibiting N-methyl-D-aspartate receptors and activating gamma-aminobutyric acid A receptors, thereby preventing neuronal excitotoxicity. RACK1 also assembles inflammasomes that are involved in various neuroinflammatory pathways, such as nuclear factor-kappa B, tumor necrosis factor-alpha, and NOD-like receptor family pyrin domain-containing 3 pathways. The potential to design therapeutics that block amyloid-β accumulation and inflammation or precisely regulate synaptic plasticity represents an attractive therapeutic strategy, in which RACK1 is a potential target. In this review, we summarize the contribution of RACK1 to the pathogenesis of AD and its potential as a therapeutic target.

The effect and optimal parameters of repetitive transcranial magnetic stimulation on lower extremity motor function in stroke patient: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in treating lower limb motor dysfunction after stroke and explore the optimal stimulation parameters.

METHODS

PubMed, Embase, Cochrane Library, and other relevant databases were systematically queried for randomised controlled trials (RCTs) investigating the efficacy of rTMS in addressing lower limb motor dysfunction post-stroke. The search encompassed records from inception to July 2022. The assessed outcomes encompassed parameters such as the Fugl-Meyer motor function score for lower limbs, balance function, and Barthel index (BI). Three independent researchers were responsible for research selection, data extraction, and quality assessment. Study screening, data extraction, and bias evaluation were performed independently by two reviewers. Data synthesis was undertaken using Review Manager 5.3, while Stata version 14.0 software was employed for generating the funnel plot.

RESULTS

A total of 13 studies and 428 patients were included. The meta-analysis indicated that rTMS had a positive effect on the BI (MD = 5.87, 95% CI [0.99, 10.76], p = 0.02, I2 = 86%, N of studies = 8, N of participants = 248). Subgroup analysis was performed on the stimulation frequency, treatment duration, and different stroke stages (stimulation frequency was low-frequency (LF)-rTMS (MD = 4.45, 95% CI [1.05, 7.85], p = 0.01, I2 = 0%, N of studies = 4, N of participants = 120); treatment time ≤ 15 d: (MD = 4.41, 95% CI [2.63, 6.18], p < 0.00001, I2 = 0%, N of studies = 4, N of participants = 124); post-stroke time ≤6 months: (MD = 4.37, 95% CI [2.42, 6.32], p < 0.0001, I2 = 0%, N of studies = 5, N of participants = 172).

CONCLUSION

LF-rTMS had a significant improvement effect on BI score, while high-frequency (HF)-rTMS and iTBS had no significant effect. And stroke time ≤6 months in patients with treatment duration ≤15 d had the best treatment effect.

Laser-activated autologous adipose tissue-derived stromal vascular fraction restores spinal cord architecture and function in multiple sclerosis cat model

BACKGROUND

Multiple sclerosis (MS) is the most frequent non-traumatic neurological debilitating disease among young adults with no cure. Over recent decades, efforts to treat neurodegenerative diseases have shifted to regenerative cell therapy. Adipose tissue-derived stromal vascular fraction (SVF) comprises a heterogeneous cell population, considered an easily accessible source of MSCs with therapeutic potential in autoimmune diseases. This study aimed to assess the regenerative capacity of low-level laser-activated SVF in an MS cat model.

METHODS

Fifteen adult Persian cats were used in this study: Group I (control negative group, normal cats), Group II (EB-treated group, induced for MS by ethidium bromide (EB) intrathecal injection), and Group III (SVF co-treated group, induced for MS then treated with SVF on day 14 post-induction). The SVF was obtained after digesting the adipose tissue with collagenase type I and injecting it intrathecal through the foramen magnum.

RESULTS

The results showed that the pelvic limb's weight-bearing locomotion activity was significantly (P ≤ 0.05) recovered in Group III, and the Basso, Beattie, and Bresnahan (BBB) scores of hindlimb locomotion were significantly higher in Group III (14 ± 0.44) than Group II (4 ± 0.31). The lesion's extent and intensity were reduced in the magnetic resonance imaging (MRI) of Group III. Besides, the same group showed a significant increase in the expression of neurotrophic factors: BDNF, SDF and NGF (0.61 ± 0.01, 0.51 ± 0.01 and 0.67 ± 0.01, respectively) compared with Group II (0.33 ± 0.01, 0.36 ± 0.006 and 0.2 ± 0.01, respectively). Furthermore, SVF co-treated group revealed a significant (P ≤ 0.05) increase in oligodendrocyte transcription factor (Olig2) and myelin basic protein (4 ± 0.35 and 6 ± 0.45, respectively) that was decreased in group II (1.8 ± 0.22 and 2.9 ± 0.20, respectively). Moreover, group III showed a significant (P ≤ 0.05) reduction in Bax and glial fibrillary acidic protein (4 ± 0.53 and 3.8 ± 0.52, respectively) as compared with group II (10.7 ± 0.49 and 8.7 ± 0.78, respectively). The transmission electron microscopy demonstrated regular more compact, and markedly (P ≤ 0.05) thicker myelin sheaths (mm) in Group III (0.3 ± 0.006) as compared with group II (0.1 ± 0.004). Based on our results, the SVF co-treated group revealed remyelination and regeneration capacity with a reduction in apoptosis and axonal degeneration.

CONCLUSION

SVF is considered an easy, valuable, and promising therapeutic approach for treating spinal cord injuries, particularly MS.

Study protocol of a randomized controlled trial for the synergizing effects of rTMS and Tui Na on upper limb motor function and cortical activity in ischemic stroke

Upper limb motor dysfunction after stroke is a serious threat to the living quality of patients and their families. Recovery of upper limb motor function after stroke largely relies on the activation and remodeling of neural circuits. rTMS (repetitive transcranial magnetic stimulation) has been proved to promote the reconstruction of neural synapses and neural circuits. However, there are still a large number of patients who cannot fully recover and leave behind varying degrees of dysfunction. Considering the systemic pathology after stroke, in addition to focal brain injury, stroke can also cause extensive dysfunction of peripheral organs. The rehabilitation strategy for stroke should combine the treatment of primary brain lesions with the intervention of secondary systemic damage. The aim of this trial is to verify the efficacy of rTMS synergize with Tui Na (Chinese Massage) on upper limb motor function after ischemic stroke, and to explore the mechanism of activation and remodeling of sensorimotor neural circuits with functional near-infrared spectroscopy. Ninety patients will be randomly assigned to either rTMS + Tui Na + conventional rehabilitation group (the experimental group) or rTMS + conventional rehabilitation group (the control group) in 1:1 ratio. Intervention is conducted five sessions a week, with a total of twenty sessions. The primary outcome is Fugl-Meyer Assessment, and the secondary outcomes include Muscle Strength, Modified Ashworth Assessment, Modified Barthel Index Assessment, motor evoked potentials and functional near-infrared spectroscopy. There are four time points for the evaluation, including baseline, 2 weeks and 4 weeks after the start of treatment, and 4 weeks after the end of treatment. This study is a randomized controlled trial. This study was approved by Institutional Ethics Committee of Shanghai Third Rehabilitation Hospital Affiliated to Shanghai University of Traditional Chinese Medicine (approval No. SH3RH-2021-EC-012) on December, 16th, 2021. The protocol was registered with Chinese Clinical Trial Registry (ChiCTR2200056266), on February 3th, 2022. Patient recruitment was initiated on February 10th, 2022, and the study will be continued until December 2023.

Repetitive Transcranial Magnetic Stimulation of the Brain After Ischemic Stroke: Mechanisms from Animal Models

Stroke is a common cerebrovascular disease with high morbidity, mortality, and disability worldwide. Post-stroke dysfunction is related to the death of neurons and impairment of synaptic structure, which results from cerebral ischemic damage. Currently, transcranial magnetic stimulation (TMS) techniques are available to provide clinically effective interventions and quantitative diagnostic and prognostic biomarkers. The development of TMS has been 40 years and a range of repetitive TMS (rTMS) protocols are now available to regulate neuronal plasticity in many neurological disorders, such as stroke, Parkinson disease, psychiatric disorders, Alzheimer disease, and so on. Basic studies in an animal model with ischemic stroke are significant for demonstrating potential mechanisms of neural restoration induced by rTMS. In this review, the mechanisms were summarized, involving synaptic plasticity, neural cell death, neurogenesis, immune response, and blood-brain barrier (BBB) disruption in vitro and vivo experiments with ischemic stroke models. Those findings can contribute to the understanding of how rTMS modulated function recovery and the exploration of novel therapeutic targets. The mechanisms of rTMS in treating ischemic stroke from animal models. rTMS can prompt synaptic plasticity by increasing NMDAR, AMPAR and BDNF expression; rTMS can inhibit pro-inflammatory cytokines TNF and facilitate the expression of anti-inflammatory cytokines IL-10 by shifting astrocytic phenotypes from A1 to A2, and shifting microglial phenotypes from M1 to M2; rTMS facilitated the release of angiogenesis-related factors TGFβ and VEGF in A2 astrocytes, which can contribute to vasculogenesis and angiogenesis; rTMS can suppress apoptosis by increasing Bcl-2 expression and inhibiting Bax, caspase-3 expression; rTMS can also suppress pyroptosis by decreasing caspase-1, IL-1β, ASC, GSDMD and NLRP1 expression. rTMS, repetitive transcranial magnetic stimulation; NMDAR, N-methyl-D-aspartic acid receptors; AMPAR: α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; BDNF, brain-derived neurotrophic factor; VEGF, vascular endothelial growth factor; GSDMD: cleaved Caspase-1 cleaves Gasdermin D; CBF: cerebral blood flow.

MeCP2 inhibits ischemic neuronal injury by enhancing methylation of the FOXO3a promoter to repress the SPRY2-ZEB1 axis

Methyl CpG binding protein 2 (MeCP2) is involved in nerve regeneration following ischemic stroke, but the related mechanism remains unclear. Here, we found low MeCP2 expression in hippocampal tissues. Using functional analysis, we demonstrated that MeCP2 accelerated FOXO3a methylation and subsequently inhibited its expression, thus repressing the apoptosis of neuronal cells. Mechanistically, FOXO3a could bind to the promoter region of SPRY2, consequently inducing its transcription and promoting the expression of the downstream target gene ZEB1. Altogether, our study revealed that overexpression of MeCP2 can protect mice against ischemic brain injury via disruption of the FOXO3a/SPRY2/ZEB1 signaling axis. Our results identify ectopic expression of MeCP2 as a therapeutic target in ischemic stroke.

Novel Therapeutic Strategies for Ischemic Stroke: Recent Insights into Autophagy

Stroke is one of the leading causes of death and disability worldwide. Autophagy is a conserved cellular catabolic pathway that maintains cellular homeostasis by removal of damaged proteins and organelles, which is critical for the maintenance of energy and function homeostasis of cells. Accumulating evidence demonstrates that autophagy plays important roles in pathophysiological mechanisms under ischemic stroke. Previous investigations show that autophagy serves as a “double-edged sword” in ischemic stroke as it can either promote the survival of neuronal cells or induce cell death in special conditions. Following ischemic stroke, autophagy is activated or inhibited in several cell types in brain, including neurons, astrocytes, and microglia, as well as microvascular endothelial cells, which involves in inflammatory activation, modulation of microglial phenotypes, and blood-brain barrier permeability. However, the exact mechanisms of underlying the role of autophagy in ischemic stroke are not fully understood. This review focuses on the recent advances regarding potential molecular mechanisms of autophagy in different cell types. The focus is also on discussing the “double-edged sword” effect of autophagy in ischemic stroke and its possible underlying mechanisms. In addition, potential therapeutic strategies for ischemic stroke targeting autophagy are also reviewed.

Brain-derived neurotrophic factor in Alzheimer's disease and its pharmaceutical potential

Synaptic abnormalities are a cardinal feature of Alzheimer's disease (AD) that are known to arise as the disease progresses. A growing body of evidence suggests that pathological alterations to neuronal circuits and synapses may provide a mechanistic link between amyloid β (Aβ) and tau pathology and thus may serve as an obligatory relay of the cognitive impairment in AD. Brain-derived neurotrophic factors (BDNFs) play an important role in maintaining synaptic plasticity in learning and memory. Considering AD as a synaptic disorder, BDNF has attracted increasing attention as a potential diagnostic biomarker and a therapeutical molecule for AD. Although depletion of BDNF has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation and neuronal apoptosis, the exact mechanisms underlying the effect of impaired BDNF signaling on AD are still unknown. Here, we present an overview of how BDNF genomic structure is connected to factors that regulate BDNF signaling. We then discuss the role of BDNF in AD and the potential of BDNF-targeting therapeutics for AD.

Administration of rTMS Alleviates Stroke-Induced Cognitive Deficits by Modulating miR-409-3p/CTRP3/AMPK/Sirt1 Axis

Cognitive deficit is a typical complication induced by stroke injuries. Repetitive transcranial magnetic stimulation (rTMS) is a technique that can both attenuate neuropsychiatric disorders and influence miR levels. We attempted to assess effects of rTMS on post-stroke cognitive deficit (PSCD) by focusing on the activity of miR-409-3p/CTRP3/AMPK/Sirt1 axis. PSCD was induced in rats using middle cerebral artery occlusion (MCAO) method and handled with rTMS. MiRs responding to rTMS administration were determined using microarray method. Changes in cognitive function, brain histological feature, neuron apoptosis, and activity of miR-409-3p/CTR3/AMPK/Sirt1 axis were detected. The interaction between of miR-409-3p and rTMS was verified by inducing its level in MCAO rats. rTMS influenced levels of miRs in MCAO rats, with 104 miRs being upregulated and 249 s miR being downregulated, contributing to the function changes in multiple biological processes. Moreover, the technique improved brain function and structure in model rats. At the molecular level, rTMS inhibited miR-409-3p and activated CTRP3/AMPK/Sirt1 pathway. After the induction of miR-409-3p, effects of rTMS were counteracted, which were represented by the impaired cognitive function and neuron viability in model rats. Collectively, rTMS could protect against stroke-induced cognitive deficits, which depended on the inhibition of miR-409-3p level.