Role of Semaphorins in Ischemic Stroke

Small extracellular vesicles derived from cerebral endothelial cells with elevated microRNA 27a promote ischemic stroke recovery

JOURNAL/nrgr/04.03/01300535-202501000-00030/figure1/v/2024-05-14T021156Z/r/image-tiff Axonal remodeling is a critical aspect of ischemic brain repair processes and contributes to spontaneous functional recovery. Our previous in vitro study demonstrated that exosomes/small extracellular vesicles (sEVs) isolated from cerebral endothelial cells (CEC-sEVs) of ischemic brain promote axonal growth of embryonic cortical neurons and that microRNA 27a (miR-27a) is an elevated miRNA in ischemic CEC-sEVs. In the present study, we investigated whether normal CEC-sEVs engineered to enrich their levels of miR-27a (27a-sEVs) further enhance axonal growth and improve neurological outcomes after ischemic stroke when compared with treatment with non-engineered CEC-sEVs. 27a-sEVs were isolated from the conditioned medium of healthy mouse CECs transfected with a lentiviral miR-27a expression vector. Small EVs isolated from CECs transfected with a scramble vector (Scra-sEVs) were used as a control. Adult male mice were subjected to permanent middle cerebral artery occlusion and then were randomly treated with 27a-sEVs or Scra-sEVs. An array of behavior assays was used to measure neurological function. Compared with treatment of ischemic stroke with Scra-sEVs, treatment with 27a-sEVs significantly augmented axons and spines in the peri-infarct zone and in the corticospinal tract of the spinal grey matter of the denervated side, and significantly improved neurological outcomes. In vitro studies demonstrated that CEC-sEVs carrying reduced miR-27a abolished 27a-sEV-augmented axonal growth. Ultrastructural analysis revealed that 27a-sEVs systemically administered preferentially localized to the pre-synaptic active zone, while quantitative reverse transcription-polymerase chain reaction and Western Blot analysis showed elevated miR-27a, and reduced axonal inhibitory proteins Semaphorin 6A and Ras Homolog Family Member A in the peri-infarct zone. Blockage of the Clathrin-dependent endocytosis pathway substantially reduced neuronal internalization of 27a-sEVs. Our data provide evidence that 27a-sEVs have a therapeutic effect on stroke recovery by promoting axonal remodeling and improving neurological outcomes. Our findings also suggest that suppression of axonal inhibitory proteins such as Semaphorin 6A may contribute to the beneficial effect of 27a-sEVs on axonal remodeling.

Changes in Gene Expression Profile with Age in SAMP8: Identifying Transcripts Involved in Cognitive Decline and Sporadic Alzheimer's Disease

Background: The senescence-accelerated mouse 8 (SAMP8) represents a model for Alzheimer's disease (AD) research because it exhibits age-related learning and memory impairments consistent with early onset and rapid progression of senescence. To identify transcriptional changes during AD progression, in this study, we analyzed and compared the gene expression profiles involved in molecular pathways of neurodegeneration and cognitive impairment in senescence-accelerated resistant 1 (SAMR1) and SAMP8 mice. Methods: In total, 48 female SAMR1 and SAMP8 mice were randomly divided into six groups (SAMR1 and SAMP8 at 3, 7, and 9 months of age). Microarray analysis of 22,000 genes was performed, followed by functional analysis using Gene Ontology (NCBI) and examination of altered molecular pathways using the KEGG (Kyoto Encyclopedia of Genes and Genomes). Results: SAMP8 mice had 2516 dysregulated transcripts at 3 months, 2549 transcripts at 7 months, and 2453 genes at 9 months compared to SAMR1 mice of the same age. These accounted for 11.3% of the total number. This showed that with age, the gene expression of downregulated transcripts increases, and that of over-expressed transcripts decreases. Most of these genes were involved in neurodegenerative metabolic pathways associated with Alzheimer's disease: apoptosis, inflammatory response, oxidative stress, and mitochondria. The qPCR results indicated that Ndufs4, TST/Rhodanese, Wnt3, and Sema6a expression was differentially expressed during aging. Conclusions: These results further revealed significant differences in gene expression profiles at different ages between SAMR1 and SAMP8 and showed alteration in genes involved in age-related cognitive decline and mitochondrial processes, demonstrating the relevance of the SAMP8 model as a model for sporadic AD.

Calpain: The regulatory point of cardiovascular and cerebrovascular diseases

Calpain, a key member of the Calpain cysteine protease superfamily, performs limited protein hydrolysis in a calcium-dependent manner. Its activity is tightly regulated due to the potential for non-specific cleavage of various intracellular proteins upon aberrant activation. A thorough review of the literature from 2010 to 2023 reveals 121 references discussing cardiovascular and cerebrovascular diseases. Dysregulation of the Calpain system is associated with various pathological phenomena, including lipid metabolism disorders, inflammation, apoptosis, and excitotoxicity. Although recent studies have revealed the significant role of Calpain in cardiovascular and cerebrovascular diseases, the precise mechanisms remain incompletely understood. Exploring the potential of Calpain inhibition as a therapeutic approach for the treatment of cardiovascular and cerebrovascular diseases may emerge as a compelling area of interest for future calpain research.

Transcription Factor EB: A Promising Therapeutic Target for Ischemic Stroke

Transcription factor EB (TFEB) is an important endogenous defensive protein that responds to ischemic stimuli. Acute ischemic stroke is a growing concern due to its high morbidity and mortality. Most survivors suffer from disabilities such as numbness or weakness in an arm or leg, facial droop, difficulty speaking or understanding speech, confusion, impaired balance or coordination, or loss of vision. Although TFEB plays a neuroprotective role, its potential effect on ischemic stroke remains unclear. This article describes the basic structure, regulation of transcriptional activity, and biological roles of TFEB relevant to ischemic stroke. Additionally, we explore the effects of TFEB on the various pathological processes underlying ischemic stroke and current therapeutic approaches. The information compiled here may inform clinical and basic studies on TFEB, which may be an effective therapeutic drug target for ischemic stroke.

The proteomic and metabolomic signatures of isolated and polytrauma traumatic brain injury

BACKGROUND

The interactions of polytrauma, shock, and traumatic brain injury (TBI) on thromboinflammatory responses remain unclear and warrant investigation as we strive towards personalized medicine in trauma. We hypothesized that comprehensive omics characterization of plasma would identify unique metabolic and thromboinflammatory pathways following TBI.

METHODS

Patients were categorized as TBI vs Non-TBI, and stratified into Polytrauma or minimally injured. Discovery 'omics was employed to quantify the top differently expressed proteins and metabolites of TBI and Non-TBI patient groups.

RESULTS

TBI compared to Non-TBI showed gene enrichment in coagulation/complement cascades and neuronal markers. TBI was associated with elevation in glycolytic metabolites and conjugated bile acids. Division into isolated TBI vs polytrauma showed further distinction of proteomic and metabolomic signatures.

CONCLUSION

Identified mediators involving in neural inflammation, blood brain barrier disruption, and bile acid building leading to TBI associated coagulopathy offer suggestions for follow up mechanistic studies to target personalized interventions.

Neuroimmune mechanisms and therapies mediating post-ischaemic brain injury and repair

The nervous and immune systems control whole-body homeostasis and respond to various types of tissue injury, including stroke, in a coordinated manner. Cerebral ischaemia and subsequent neuronal cell death activate resident or infiltrating immune cells, which trigger neuroinflammation that affects functional prognosis after stroke. Inflammatory immune cells exacerbate ischaemic neuronal injury after the onset of brain ischaemia; however, some of the immune cells thereafter change their function to neural repair. The recovery processes after ischaemic brain injury require additional and close interactions between the nervous and immune systems through various mechanisms. Thus, the brain controls its own inflammation and repair processes after injury via the immune system, which provides a promising therapeutic opportunity for stroke recovery.

Semaphorin 6D regulate corralling, hematoma compaction and white matter injury in mice after intracerebral hemorrhage

OBJECTIVES

The Semaphorin 6D (SEMA6D) shows important roles in cell guidance and lipid metabolism, but the effects and mechanisms of SEMA6D on tissue repair, white matter injury and the recovery of neurological function after intracerebral hemorrhage have not been well studied.

MATERIALS AND METHODS

In this study, the autologous whole blood injection model of intracerebral hemorrhage was established in C57 male mice. SEMA6D knockout CRISPR utilized in the study. Assessments included neurological score evaluation and immunofluorescence.

RESULTS

SEMA6D increased and peaked at 7d after intracerebral hemorrhage, and mainly located in neurons, microglia and astrocytes. SEMA6D knockout CRISPR aggravated neurological function and showed signs of poorer corralling and hematoma resolution, with more compartments of well-established physical barrier and more extensive GFAP positive astrocytic border. Furthermore, SEMA6D can prevent the decrease of NF-H in the peri-hematoma region, while SEMA6D knockout aggravated WMI.

CONCLUSIONS

Our study suggested that SEMA6D could influence the recovery of neurological function by regulating the corralling, hematoma compaction and WMI in mice after intracerebral hemorrhage.