Thymosin beta4 improves functional neurological outcome in a rat model of embolic stroke

Fecal microbiota transplantation alleviates neuronal Apoptosis, necroptosis and reactive microglia activation after ischemic stroke

OBJECTIVE

This study aims to delve into the mechanisms underlying the improvement of neurological function in rats with ischemic stroke through fecal microbiota transplantation.

METHODS

A total of fifty male Sprague-Dawley rats were categorized into four groups: Sham, MCAO, MCAO+vehicle and FMT. We assessed behavioral and pathological alterations in the rats using modified neurological function scoring and TTC staining.Additionally, Western blot and immunofluorescence were used to detect the expression levels of Apoptotic and Necroptosis markers in neurons of ischemic brain tissue, and immunofluorescence was used to analyze the degree of activation of microglia.

RESULTS

FMT group exhibited a decline in neurological function score compared to the MCAO and MCAO + vehicle group, accompanied by a reduction in infarct volume (P < 0.05). Relative to the SHAM group, the MCAO group displayed a significant increase in the expression levels of necroptosis-related proteins Phospho-RIP1, Phospho-RIP3, Phospho-MLKL, apoptotic proteins Bax and Cleaved caspase-3, and the iNOS positive microglia in ischemic brain tissue, while Bcl-2 expression was notably decreased (P < 0.05).Conversely, compared to the MCAO + vehicle group, the FMT group showed decreased expression levels of Phospho-RIP1, Phospho-RIP3, Phospho-MLKL, Bax, Cleaved caspase-3, and iNOS-positive microglia, while the expression of Bcl-2 was increased.

CONCLUSION

Fecal microbiota transplantation offers a promising approach to improving neurological function in rats with ischemic stroke by inhibiting neuronal apoptosis, necroptosis, and the polarization of inflammatory microglial cells.

Inhaled exogenous thymosin beta 4 suppresses bleomycin-induced pulmonary fibrosis in mice via TGF-β1 signalling pathway

OBJECTIVES

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fibrotic interstitial lung disease. The two drugs indicated for IPF have limited efficacy and there is an urgent need to develop new drugs. Thymosin β4 (Tβ4) is a natural endogenous repair factor whose antifibrotic effects have been reported. This study aimed to evaluate the effect of exogenous recombinant human thymosin beta 4 (rhTβ4) on pulmonary fibrosis.

METHODS

Pulmonary fibrosis was induced in mice with bleomycin, and rhTβ4 was administrated by nebulization following three strategies: early dosing, mid-term dosing, and late dosing. The rhTβ4 efficacy was assessed by hydroxyproline, lung function, and lung histopathology. In vitro, the effects of rhTβ4 on fibroblast and lung epithelial cell phenotypes, as well as the TGF-β1 pathway, were evaluated.

KEY FINDINGS

Aerosol administration of rhTβ4 could alleviate bleomycin-induced pulmonary fibrosis in mice at different stages of fibrosis. Studies conducted in vitro suggested that rhTβ4 could suppress lung fibroblasts from proliferating, migrating, and activation via regulating the TGF-β1 signalling pathway. In vitro, rhTβ4 also inhibited the epithelial-mesenchymal transition-like process of pulmonary epithelial cells.

CONCLUSIONS

This study suggests that nebulized rhTβ4 is a potential treatment for IPF.

Local and Systemic Peptide Therapies for Soft Tissue Regeneration: A Narrative Review

Background: The musculoskeletal system, due to inherent structure and function, lends itself to contributing toward joint pain, whether from inflammatory disorders such as rheumatoid arthritis, degenerative diseases such as osteoarthritis, or trauma causing soft tissue injury. Administration of peptides for treatment of joint pain or inflammation is an emerging line of therapy that seeks to offer therapeutic benefits while remaining safe and relatively non-invasive. Purpose: The purpose of this study is to review the current literature on existing oral peptide agents, intra-articular peptide agents, and new developments in human trials to assess route of administration (RoA) for drug delivery in terms of soft tissue regeneration. Study Design: Narrative Review. Methods: A comprehensive literature search was conducted using the PubMed database. The search included medical subject headings (MeSH) terms related to peptide therapy, soft tissue regeneration, and RoA. Inclusion criteria comprised articles focusing on the mechanisms of action of peptides, clinical or biochemical outcomes, and review articles. Exclusion criteria included insufficient literature or studies not meeting the set evidence level. Conclusion: The review identified various peptides demonstrating efficacy in soft tissue repair. Oral and intra-articular peptides showed distinct advantages in soft tissue regeneration, with intra-articular routes providing localized effects and oral routes offering systemic benefits. However, both routes have limitations in bioavailability and absorption. Still in their infancy, further inquiries/research into the properties and efficacy of emerging peptides will be necessary before widespread use. As a viable alternative prior to surgical intervention, peptide treatments present as promising candidates for positive outcomes in soft tissue regeneration.

Minimally invasive vagus nerve stimulation modulates mast cell degranulation via the microbiota-gut-brain axis to ameliorate blood-brain barrier and intestinal barrier damage following ischemic stroke

Mast cells (MCs) play a significant role in various diseases, and their activation and degranulation can trigger inflammatory responses and barrier damage. Several studies have indicated that vagus nerve stimulation (VNS) exerts ameliorates neurological injury, and regulates gut MC degranulation. However, there is limited research on the modulatory effect of VNS on MCs in both the gut and brain in brain ischemia-reperfusion (I/R) injury in this process. We aim to develop a minimally invasive, targeted and convenient VNS approach to assess the impact of VNS and to clarify the relationship between VNS and MCs on the prognosis of acute ischemic stroke. We utilized middle cerebral artery occlusion/reperfusion (MCAO/r) to induce brain I/R injury. After the experiment, the motor function and neurofunctional impairments of the rats were detected, and the gastrointestinal function, blood-brain barrier (BBB) and intestinal barrier damage, and systemic and local inflammation were evaluated by Nissl, TTC staining, Evans blue, immunofluorescence staining, transmission electron microscopy, western blot assays, ELISA, and fecal 16S rRNA sequencing methods. Our research confirmed that our minimally invasive VNS method is a novel approach for stimulating the vagus nerve. VNS alleviated motor deficits and gastrointestinal dysfunction while also suppressing intestinal and neuroinflammation. Additionally, VNS ameliorated gut microbiota dysbiosis in rats. Furthermore, our analysis indicated that VNS reduces chymase secretion by modulating MCs degranulation and improves intestinal and BBB damage. Our results showed that VNS treatment can alleviate the damage of BBB and colonic barrier after cerebral I/R by modulating mast cell degranulation, and alleviates systemic inflammatory responses.

Integrating network pharmacology and bioinformatics to explore and experimentally verify the regulatory effect of Buyang Huanwu decoction on glycolysis and angiogenesis after cerebral infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Promoting the recovery of cerebral blood circulation after cerebral infarction (CI) is an important intervention. Buyang Huanwu decoction (BHD) is a classic prescription for treating CI that promotes angiogenesis. Cytoplasmic glycolysis ischaemic-region cells after CI may be highly activated to maintain metabolic activity under hypoxia. From the perspective of long-term maintenance of glycolytic metabolism in the ischaemic area after CI, it may be beneficial to promote angiogenesis and maintain glial cell activation and neuronal survival. In this context, the regulatory relationship of lncRNAs and miRNAs with mRNAs is worthy of attention. Mining the competitive binding relationships among RNAs will aid in the screening of key gene targets post-CI. In this study, network pharmacology and bioinformatics were used to construct a ceRNA network, screen key targets, and explore the effect of glycolysis on angiogenesis during BHD-mediated CI regulation.

AIM OF THE STUDY

This study aimed to explore the effect of BHD on angiogenesis after glycolysis regulation in CI.

MATERIALS AND METHODS

According to the 21 active BHD ingredients we identified by our research team, we conducted network pharmacology. BHD targets that can regulate glycolysis and angiogenesis after CI were screened from the GeneCards, CTD and OMIM databases. We retrieved CI-related datasets from the GEO database and screened for differentially expressed lncRNAs and miRNAs. LncRNA‒miRNA-mRNA/TF targeting relationships were screened and organized with the miRcode, miRDB, TargetScan, miRWalk, and TransmiR v2.0 databases. Cytoscape was used to construct an lncRNA‒miRNA-mRNA/TF ceRNA network. Through BioGPS, key mRNAs/TFs in the network were screened for enrichment analysis. Animal experiments were then conducted to validate some key mRNAs/TFs and enriched signalling pathways.

RESULTS

PFKFB3 and other genes may help regulate glycolysis and angiogenesis through AMPK and other signalling pathways. The anti-CI effect of BHD may involve maintaining activation of genes such as AMPK and PFKFB3 in the ischaemic cortex, maintaining moderate glycolysis levels in brain tissue, and promoting angiogenesis.

CONCLUSION

BHD can regulate glycolysis and promote angiogenesis after CI through multiple pathways and targets, in which AMPK signalling pathway activation may be important.

Antioxioxidant and antiapoptotic effects of Thymosin β4 in Aβ-induced SH-SY5Y cells via the 5-HTR1A/ERK axis

Alzheimer's disease (AD) is a common amnestic cognitive impairment characterised by β-amyloid (Aβ) plaques deposit in the brain of the elderly. AD is a yet incurable disease due to its unknown exact pathogenesis and unavailability of effective remedies in clinical application. Thymosin β4 (Tβ4) is a housekeeping protein that plays important role in cell proliferation, migration and differentiation. It has the ability to protect and repair neurons however it is still unclear involvement in AD. Therefore, the aim of this study is to elucidate the role and mechanism of Tβ4 in mediating the improvement of AD. AD-like cell model was constructed in neuroblastoma cell line SH-SY5Y treated with Aβ. Overexpression of Tβ4 were done using lentivirus infection and downregulation through siRNA transfection. We performed western blot and flow cytometry to study the apoptosis and standard kits to measure the oxidative stress-associated biomarkers. There is significant increased in viability and decreased apoptosis in Tβ4 overexpression group compared to control. Furthermore, overexpression of Tβ4 suppressed the expression of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax meanwhile upregulated the expression of anti-apoptotic gene Bcl-2. Tβ4 alleviated oxidative damage by reducing MDA, LDH and ROS and increasing SOD and GSH-PX in Aβ-treated SH-SY5Y cells. We found that Tβ4 inhibit ERK/p38 MAPK pathway and intensify the expression of 5-HTR1A. Additionally, we showed that upregulation of 5-HTR1A dampened the Tβ4 to activate ERK signalling. In conclusion, our study revealed the neuroprotective role of Tβ4 in AD which may open up new therapeutic applications in AD treatment.

Comparative transcriptome findings reveal the neuroinflammatory network and potential biomarkers to early detection of ischemic stroke

INTRODUCTION

Ischemic stroke accounts for 70-80% of all stroke cases, leading to over two million people dying every year. Poor diagnosis and late detection are the major causes of the high death and disability rate.

METHODS

In the present study, we used the middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomic analysis, followed by a systematic advanced bioinformatic analysis, including gene ontology enrichment analysis and Ingenuity Pathway Analysis (IPA). We aimed to identify novel biomarkers for the early detection of ischemic stroke. In addition, we aimed to delineate the molecular mechanisms underlying the development of ischemic stroke, in which we hoped to identify novel therapeutic targets for treating ischemic stroke.

RESULTS

In the comparative transcriptomic analysis, we identified 2657 differentially expressed genes (DEGs) in the brain tissue of the MCAO model. The gene enrichment analysis highlighted the importance of these DEGs in oxygen regulation, neural functions, and inflammatory and immune responses. We identified the elevation of angiopoietin-2 and leptin receptor as potential novel biomarkers for early detection of ischemic stroke. Furthermore, the result of IPA suggested targeting the inflammasome pathway, integrin-linked kinase signaling pathway, and Th1 signaling pathway for treating ischemic stroke.

CONCLUSION

The results of the present study provide novel insight into the biomarkers and therapeutic targets as potential treatments of ischemic stroke.

Provocative non-canonical roles of p53 and AKT signaling: A role for Thymosin β4 in medulloblastoma

The PI3K/AKT and p53 pathways are key regulators of cancer cell survival and death, respectively. Contrary to their generally accepted roles, several lines of evidence, including ours in medulloblastoma, the most common childhood brain cancer, highlight non-canonical functions for both proteins and show a complex context-dependent dynamic behavior in determining cell fate. Interestingly, p53-mediated cell survival and AKT-mediated cell death can dominate in certain conditions, and these interchangeable physiological functions may potentially be manipulated for better clinical outcomes. This review article presents studies in which p53 and AKT behave contrary to their well-established functions. We discuss the factors and circumstances that may be involved in mediating these changes and the implications of these unique roles of p53 and AKT in devising therapeutic strategies. Lastly, based on our recent finding of Thymosin beta 4-mediated chemosensitivity via an AKT-p53 interaction in medulloblastoma cells, we also discuss the possible implications of Thymosin beta-4 in enhancing drug sensitivity in this deadly childhood disease.

Repetitive transcranial magnetic stimulation promotes neurological functional recovery in rats with traumatic brain injury by upregulating synaptic plasticity-related proteins

Studies have shown that repetitive transcranial magnetic stimulation (rTMS) can enhance synaptic plasticity and improve neurological dysfunction. However, the mechanism through which rTMS can improve moderate traumatic brain injury remains poorly understood. In this study, we established rat models of moderate traumatic brain injury using Feeney’s weight-dropping method and treated them using rTMS. To help determine the mechanism of action, we measured levels of several important brain activity-related proteins and their mRNA. On the injured side of the brain, we found that rTMS increased the protein levels and mRNA expression of brain-derived neurotrophic factor, tropomyosin receptor kinase B, N-methyl-D-aspartic acid receptor 1, and phosphorylated cAMP response element binding protein, which are closely associated with the occurrence of long-term potentiation. rTMS also partially reversed the loss of synaptophysin after injury and promoted the remodeling of synaptic ultrastructure. These findings suggest that upregulation of synaptic plasticity-related protein expression is the mechanism through which rTMS promotes neurological function recovery after moderate traumatic brain injury.

Chemokine receptor 7 mediates miRNA-182 to regulate cerebral ischemia/reperfusion injury in rats

AIMS

Chemokine receptor 7 (CXCR7) exerts protective effects on the brain. MicroRNAs (miRNAs) are involved in cerebral ischemia/reperfusion (I/R) injury, but their involvement in CXCR7-mediated brain protection is unknown. In this study, we investigated the role of miRNAs in CXCR7-mediated brain protection.

METHODS

CXCR7 levels in peripheral blood samples from patients with acute ischemic stroke (AIS) and ischemic penumbra area brain tissues from middle cerebral artery occlusion (MCAO) rats after recanalization were measured. An miRNA microarray analysis was performed to examine the expression of miRNAs caused by CXCR7 knockdown in ischemic penumbra area brain tissue in middle cerebral artery occlusion-reperfusion rats and to predict corresponding downstream target genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed the most enriched pathways. A dual-luciferase reporter assay confirmed the direct regulation of miR-182 on the target gene TCF7L2. The correlation between TCF7L2 and CXCR7/miR-182 was verified using rescue assays.

RESULTS

CXCR7 expression was upregulated in MCAO rats and mechanical thrombectomy patients with AIS compared to that in controls. The motor and sensory functions of MCAO rats with CXCR7 knockdown further decreased, and the infarct volume and cerebral edema increased. miRNA microarray data showed that seven miRNAs were differentially expressed after shRNA-CXCR7 treatment. The dual-luciferase reporter assay confirmed that miR-182 directly targeted the TCF7L2 gene. Rescue assays confirmed that TCF7L2 is downstream of CXCR7/miR-182. KEGG pathway analysis showed that the Hippo pathway may be a key pathway in CXCR7 upregulation and plays a role in protecting the brain after interventional surgery. Animal experiments have shown that CXCR7-mediated cerebral I/R injury promotes the phosphorylation of key molecules YAP and TAZ in the Hippo pathway.

CONCLUSION

CXCR7 protects against cerebral I/R injury, possibly via the miR-182/TCF7L2/Hippo pathway. These results indicate that CXCR7 affects cerebral ischemia-reperfusion injury through miRNA regulation and downstream pathways.

The Role of Tβ4-POP-Ac-SDKP Axis in Organ Fibrosis

Fibrosis is a pathological process in which parenchymal cells are necrotic and excess extracellular matrix (ECM) is accumulated due to dysregulation of tissue injury repair. Thymosin β4 (Tβ4) is a 43 amino acid multifunctional polypeptide that is involved in wound healing. Prolyl oligopeptidase (POP) is the main enzyme that hydrolyzes Tβ4 to produce its derivative N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) which is found to play a role in the regulation of fibrosis. Accumulating evidence suggests that the Tβ4-POP-Ac-SDKP axis widely exists in various tissues and organs including the liver, kidney, heart, and lung, and participates in the process of fibrogenesis. Herein, we aim to elucidate the role of Tβ4-POP-Ac-SDKP axis in hepatic fibrosis, renal fibrosis, cardiac fibrosis, and pulmonary fibrosis, as well as the underlying mechanisms. Based on this, we attempted to provide novel therapeutic strategies for the regulation of tissue damage repair and anti-fibrosis therapy. The Tβ4-POP-Ac-SDKP axis exerts protective effects against organ fibrosis. It is promising that appropriate dosing regimens that rely on this axis could serve as a new therapeutic strategy for alleviating organ fibrosis in the early and late stages.

Molecular mechanisms for the prevention and promoting the recovery from ischemic stroke by nutraceutical laminarin: A comparative transcriptomic approach

Stroke is the second leading cause of death and a major cause of disability worldwide. Ischemic stroke caused by atherosclerosis accounts for approximately 87% of all stroke cases. Ischemic stroke is a preventable disease; therefore, a better understanding of the molecular mechanisms underlying its pathogenesis and recovery processes could provide therapeutic targets for drug development and reduce the associated mortality rate. Laminarin, a polysaccharide, is a nutraceutical that can be found in brown algae. Accumulating evidence suggests that laminarin could reduce the detrimental effects of neuroinflammation on brain damage after stroke. However, the molecular mechanism underlying its beneficial effects remains largely unknown. In the present study, we used a middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomics to investigate the molecular targets and pathways involved in the beneficial effects of laminarin on ischemic stroke. Our results show the involvement of laminarin targets in biological processes related to blood circulation, oxygen supply, and anti-inflammatory responses in the normal brain. More importantly, laminarin treatment attenuated brain damage and neurodeficits caused by ischemic stroke. These beneficial effects are controlled by biological processes related to blood vessel development and brain cell death through the regulation of canonical pathways. Our study, for the first time, delineated the molecular mechanisms underlying the beneficial effects of laminarin on ischemic stroke prevention and recovery and provides novel therapeutic targets for drug development against ischemic stroke.

Regulation of Chemosensitivity in Human Medulloblastoma Cells by p53 and the PI3 Kinase Signaling Pathway

In medulloblastoma, p53 expression has been associated with chemoresistance and radiation resistance and with poor long-term outcomes in the p53-mutated sonic hedgehog, MYC-p53, and p53-positive medulloblastoma subgroups. We previously established a direct role for p53 in supporting drug resistance in medulloblastoma cells with high basal protein expression levels (D556 and DAOY). We now show that p53 genetic suppression in medulloblastoma cells with low basal p53 protein expression levels (D283 and UW228) significantly reduced drug responsiveness, suggesting opposing roles for low p53 protein expression levels. Mechanistically, the enhanced cell death by p53 knockdown in high-p53 cells was associated with an induction of mTOR/PI3K signaling. Both mTOR inhibition and p110α/PIK3CA induction confirmed these findings, which abrogated or accentuated the enhanced chemosensitivity response in D556 cells respectively while converse was seen in D283 cells. Co-treatment with G-actin-sequestering peptide, thymosin β4 (Tβ4), induced p-AKT^S473 in both p53-high and p53-low cells, enhancing chemosensitivity in D556 cells while enhancing chemoresistance in D283 and UW228 cells. IMPLICATIONS: Collectively, we identified an unexpected role for the PI3K signaling in enhancing cell death in medulloblastoma cells with high basal p53 expression. These studies indicate that levels of p53 immunopositivity may serve as a diagnostic marker of chemotherapy resistance and for defining therapeutic targeting.

Tβ4 ameliorates oxidative damage and apoptosis through ERK/MAPK and 5-HT1A signaling pathway in Aβ insulted SH-SY5Y cells

AIMS

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder seriously endangering the physical and mental health of the elderly, while no effective treatments and drugs in clinical practice are available. Thymosin β4 (Tβ4) is a multifunctional polypeptide involved in many physiological and pathological processes including AD. This study aims to understand the function and molecular mechanism of Tβ4 in the development of AD.

MAIN METHODS

Neuroblastoma cell line SH-SY5Y was treated with β-amyloid (Aβ) to induce AD-like pathological changes, which serves as Alzheimer's disease model. Tβ4 was overexpressed in SH-SY5Y cells by lentivirus infection, and downregulated by siRNA transfection. Apoptosis of transfected SH-SY5Y cells after Aβ-treatment was examined by western blot and flow cytometry. Apoptotic proteins and Tβ4-related signaling pathways were also investigated by western blot.

KEY FINDINGS

We found that Tβ4 overexpression increased viability and suppressed apoptosis of Aβ-treated SH-SY5Y cells. Tβ4 ameliorated oxidative damage and suppressed reactive oxygen species production in Aβ-treated SH-SY5Y cells. Consistently, Tβ4 overexpression down-regulated the expression levels of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax, while up-regulated the expression level of anti-apoptotic gene Bcl-2 in Aβ-stimulated SH-SY5Y cells. Mechanistically, we demonstrated that Tβ4 dampened ERK/p38 MAPK signaling and enhanced 5-HTR1A expression in Aβ-treated SH-SY5Y cells. Moreover, we revealed that Tβ4 inhibited the activation of ERK pathway through up-regulating 5-HTR1A in Aβ-treated SH-SY5Y cells.

SIGNIFICANCE

Taken together, our findings provide evidences to support the neuroprotective role of Tβ4 and might open up new therapeutic applications of Tβ4 in AD treatment.

Neuroprotective Effect of Maternal Resveratrol Supplementation in a Rat Model of Neonatal Hypoxia-Ischemia

Neonatal hypoxia-ischemia (nHI) is a major cause of death or subsequent disabilities in infants. Hypoxia-ischemia causes brain lesions, which are induced by a strong reduction in oxygen and nutrient supply. Hypothermia is the only validated beneficial intervention, but not all newborns respond to it and today no pharmacological treatment exists. Among possible therapeutic agents to test, trans-resveratrol is an interesting candidate as it has been reported to exhibit neuroprotective effects in some neurodegenerative diseases. This experimental study aimed to investigate a possible neuroprotection by resveratrol in rat nHI, when administered to the pregnant rat female, at a nutritional dose. Several groups of pregnant female rats were studied in which resveratrol was added to drinking water either during the last week of pregnancy, the first week of lactation, or both. Then, 7-day old pups underwent a hypoxic-ischemic event. Pups were followed longitudinally, using both MRI and behavioral testing. Finally, a last group was studied in which breastfeeding females were supplemented 1 week with resveratrol just after the hypoxic-ischemic event of the pups (to test the curative rather than the preventive effect). To decipher the molecular mechanisms of this neuroprotection, RT-qPCR and Western blots were also performed on pup brain samples. Data clearly indicated that when pregnant and/or breastfeeding females were supplemented with resveratrol, hypoxic-ischemic offspring brain lesions were significantly reduced. Moreover, maternal resveratrol supplementation allowed to reverse sensorimotor and cognitive deficits caused by the insult. The best recoveries were observed when resveratrol was administered during both gestation and lactation (2 weeks before the hypoxic-ischemic event in pups). Furthermore, neuroprotection was also observed in the curative group, but only at the latest stages examined. Our hypothesis is that resveratrol, in addition to the well-known neuroprotective benefits via the sirtuin’s pathway (antioxidant properties, inhibition of apoptosis), has an impact on brain metabolism, and more specifically on the astrocyte-neuron lactate shuttle (ANLS) as suggested by RT-qPCR and Western blot data, that contributes to the neuroprotective effects.

Protective effect of Tβ4 on central nervous system tissues and its developmental prospects

Tissue repair and regeneration in the central nervous system (CNS) remains a serious medical problem. CNS diseases such as traumatic and neurological brain injuries have a high mortality and disability rate, thereby bringing a considerable amount of economic burden to society and families. How to treat traumatic and neurological brain injuries has always been a serious issue faced by neurosurgeons. The global incidence of traumatic and neurological brain injuries has gradually increased and become a global challenge. Thymosin β4 (Tβ4) is the main G-actin variant molecule in eukaryotic cells. During the development of the CNS, Tβ4 regulates neurogenesis, tangential expansion, tissue growth, and cerebral hemisphere folding. In addition, Tβ4 has anti-apoptotic and anti-inflammatory properties. It promotes angiogenesis, wound healing, stem/progenitor cell differentiation, and other characteristics of cell migration and survival, providing a scientific basis for the repair and regeneration of injured nerve tissue. This review provides evidence to support the role of Tβ4 in the protection and repair of nervous tissue in CNS diseases, especially with the potential to control brain inflammatory processes, and thus open up new therapeutic applications for a series of neurodegenerative diseases.

High-frequency repetitive transcranial magnetic stimulation improves functional recovery by inhibiting neurotoxic polarization of astrocytes in ischemic rats

Background

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive treatment for ischemic stroke. Astrocytes regulation has been suggested as one mechanism for rTMS effectiveness. But how rTMS regulates astrocytes remains largely undetermined. There were neurotoxic and neuroprotective phenotypes of astrocytes (also denoted as classically and alternatively activated astrocytes or A1 and A2 astrocytes) pertaining to pro- or anti-inflammatory gene expression. Pro-inflammatory or neurotoxic polarized astrocytes were induced during cerebral ischemic stroke. The present study aimed to investigate the effects of rTMS on astrocytic polarization during cerebral ischemic/reperfusion injury.

Methods

Three rTMS protocols were applied to primary astrocytes under normal and oxygen-glucose deprivation/reoxygenation (OGD/R) conditions. Cell survival, proliferation, and phenotypic changes were assessed after 2-day treatment. Astrocytes culture medium (ACM) from control, OGD/R, and OGD/R + rTMS groups were mixed with neuronal medium to culture neurons for 48 h and 7 days, in order to explore the influence on neuronal survival and synaptic plasticity. In vivo, rats were subjected to middle cerebral artery occlusion (MCAO), and received posterior orbital intravenous injection of ACM collected from different groups at reperfusion, and at 3 days post reperfusion. The apoptosis in the ischemic penumbra, infarct volumes, and the modified Neurological Severity Score (mNSS) were evaluated at 1 week after reperfusion, and cognitive functions were evaluated using the Morris Water Maze (MWM) tests. Finally, the 10 Hz rTMS was directly applied to MCAO rats to verify the rTMS effects on astrocytic polarization.

Results

Among these three frequencies, the 10 Hz protocol exerted the greatest potential to modulate astrocytic polarization after OGD/R injury. Classically activated and A1 markers were significantly inhibited by rTMS treatment. In OGD/R model, the concentration of pro-inflammatory mediator TNF-α decreased from 57.7 to 23.0 рg/mL, while anti-inflammatory mediator IL-10 increased from 99.0 to 555.1 рg/mL in the ACM after rTMS treatment. The ACM collected from rTMS-treated astrocytes significantly alleviated neuronal apoptosis induced by OGD/R injury, and promoted neuronal plasticity. In MCAO rat model, the ACM collected from rTMS treatment decreased neuronal apoptosis and infarct volumes, and improved cognitive functions. The neurotoxic astrocytes were simultaneously inhibited after rTMS treatment.

Conclusion

Inhibition of neurotoxic astrocytic polarization is a potential mechanism for the effectiveness of high-frequency rTMS in cerebral ischemic stroke.

Role of p75 neurotrophin receptor in neuronal autophagy in intracerebral hemorrhage in rats through the mTOR signaling pathway

Rupture of weakened blood vessels could lead to severe intracerebral hemorrhage (ICH) and brain injuries. This study was designed to explore the roles of p75 neurotrophin receptor (p75^NTR) in neuronal autophagy in ICH rats. An ICH rat model was established, and then gain and loss of functions of p75^NTR in rat tissues were performed. Then, the pathologic morphology, water content, and inflammation in brain tissues were assessed. Western blot analysis was applied to detect the levels of inflammatory proteins, apoptosis- and autophagy-related proteins, and the mammalian target of rapamycin (mTOR) pathway-related proteins. Neuronal autophagy was further measured with mTOR activated. In vitro experiments were also performed on brain microvascular endothelial cells (BMECs) and astrocytes. Consequently, we found p75^NTR knockdown improved the pathologic morphology with reduced neuron damage, water content, permeability of blood-brain barrier and inflammation in ICH rat brain tissues. Besides, Knockdown of p75^NTR decreased neuronal apoptosis and inactivated mTOR signaling pathway, but it elevated the levels of autophagy-related proteins. In vivo results were reproduced in in vitro experiments. This study demonstrated that knockdown of p75^NTR could promote neuronal autophagy and reduce neuronal apoptosis via inactivating the mTOR pathway. We hope these findings could provide new therapeutic options for ICH treatment.

A new insight into thymosin β4, a promising therapeutic approach for neurodegenerative disorders

Thymosin β4 (Tβ4), a G-actin-sequestering secreted peptide, improves neurovascular remodeling and central nervous system plasticity, which leads to neurological recovery in many neurological diseases. Inflammatory response adjustment and tissue inflammation consequences from neurological injury are vital for neurological recovery. The innate or nonspecific immune system is made of different components. The Toll-like receptor pro-inflammatory signaling pathway, which is one of these components, regulates tissue injury. The main component of the Toll-like/IL-1 receptor signaling pathway, which is known as IRAK1, can be regulated by miR-146a and regulates NF-κB expression. Due to the significant role of Tβ4 in oligodendrocytes, neurons, and microglial cells in neurological recovery, it is suggested that Tβ4 regulates the Toll-like receptor (TLR) pro-inflammatory signaling pathway by upregulating miR-146a in neurological disorders. However, further investigations on the role of Tβ4 in regulating the expression of miR146a and TLR signaling pathway in the immune response adjustment in neurological disorders provides an insight into mechanisms of action and the possibility of Tβ4 therapeutic effect enhancement.

Ac-SDKP ameliorates the progression of experimental autoimmune encephalomyelitis via inhibition of ER stress and oxidative stress in the hippocampus of C57BL/6 mice

Despite the attention given to the treatment of multiple sclerosis (MS), still no certain cure is available. The main purpose of MS drugs is acting against neuroinflammation which underlies the pathology of MS. Neuroinflammation is associated with endoplasmic reticulum (ER) stress that mediates neural apoptosis. In the present study, we hypothesized that the tetrapeptide N-acetyl-ser-asp-lys-pro (Ac-SDKP) with the previously described anti-fibrotic effects might have anti-inflammatory, anti-oxidative and anti-ER stress roles in the hippocampus. We used myelin oligodendrocyte glycoprotein (MOG) to induce experimental autoimmune encephalomyelitis (EAE), a widely-accepted animal model of MS, in C57BL/6 mice. The protein levels of ER stress-related molecules including caspase-12, C/EBP homologous protein (CHOP), and protein disulfide isomerase (PDI) in the hippocampus were examined by immunoblotting. Hence, reactive oxygen species (ROS) production, lipid peroxidation and antioxidant capacity of the hippocampus were studied. Moreover, hippocampal morphology changes, leukocytes infiltration, and the levels of IL-6 and IL-1β pro-inflammatory cytokines were evaluated. Our results displayed that Ac-SDKP down regulates caspase-12 and CHOP expression in the hippocampus-resident oligodendrocytes of EAE mice. Further, treatment with Ac-SDKP decreased oxidative stress markers and caspase-3 activation in the hippocampus of EAE mice. According to our findings, Ac-SDKP showed beneficial effects against ER stress and oxidative stress in addition to inflammation in the hippocampus of EAE mice. The present study provides the basis for further research on the therapeutic applications of Ac-SDKP to reduce ER stress and oxidative stress-induced apoptosis in neurodegenerative disorders.

Emerging Roles of miRNAs in Brain Development and Perinatal Brain Injury

In human beings the immature brain is highly plastic and depending on the stage of gestation is particularly vulnerable to a range of insults that if sufficiently severe, can result in long-term motor, cognitive and behavioral impairment. With improved neonatal care, the incidence of major motor deficits such as cerebral palsy has declined with prematurity. Unfortunately, however, milder forms of injury characterized by diffuse non-cystic white matter lesions within the periventricular region and surrounding white matter, involving loss of oligodendrocyte progenitors and subsequent axonal hypomyelination as the brain matures have not. Existing therapeutic options for treatment of preterm infants have proved inadequate, partly owing to an incomplete understanding of underlying post-injury cellular and molecular changes that lead to poor neurodevelopmental outcomes. This has reinforced the need to improve our understanding of brain plasticity, explore novel solutions for the development of protective strategies, and identify biomarkers. Compelling evidence exists supporting the involvement of microRNAs (miRNAs), a class of small non-coding RNAs, as important post-transcriptional regulators of gene expression with functions including cell fate specification and plasticity of synaptic connections. Importantly, miRNAs are differentially expressed following brain injury, and can be packaged within exosomes/extracellular vesicles, which play a pivotal role in assuring their intercellular communication and passage across the blood-brain barrier. Indeed, an increasing number of investigations have examined the roles of specific miRNAs following injury and regeneration and it is apparent that this field of research could potentially identify protective therapeutic strategies to ameliorate perinatal brain injury. In this review, we discuss the most recent findings of some important miRNAs in relation to the development of the brain, their dysregulation, functions and regulatory roles following brain injury, and discuss how these can be targeted either as biomarkers of injury or neuroprotective agents.

Improvement of fiber connectivity and functional recovery after stroke by montelukast, an available and safe anti-asthmatic drug

Stroke is one of the main causes of death, neurological dysfunctions or disability in elderly. Neuroprotective drugs have been proposed to improve long-term recovery after stroke, but failed to reach clinical effectiveness. Hence, recent studies suggested that restorative therapies should combine neuroprotection and remyelination. Montelukast, an anti-asthmatic drug, was shown to exert neuroprotection in animal models of CNS injuries, but its ability to affect oligodendrocytes, restoring fiber connectivity, remains to be determined. In this study, we evaluated whether montelukast induces long-term repair by promoting fiber connectivity up to 8 weeks after middle cerebral artery occlusion (MCAo), using different experimental approaches such as in vivo diffusion magnetic resonance imaging (MRI), electrophysiological techniques, ex vivo diffusion tensor imaging (DTI)-based fiber tracking and immunohistochemistry. We found that, in parallel with a reduced evolution of ischemic lesion and atrophy, montelukast increased the DTI-derived axial diffusivity and number of myelin fibers, the density of myelin binding protein (MBP) and the number of GSTpi⁺ mature oligodendrocytes. Together with the rescue of MCAo-induced impairments of local field potentials in ischemic cortex, the data suggest that montelukast may improve fibers reorganization. Thus, to ascertain whether this effect involved changes of oligodendrocyte precursor cells (OPCs) activation and maturation, we used the reporter GPR17iCreERT2:CAG-eGreen florescent protein (GFP) mice that allowed us to trace the fate of OPCs throughout animal's life. Our results showed that montelukast enhanced the OPC recruitment and proliferation at acute phase, and increased their differentiation to mature oligodendrocytes at chronic phase after MCAo. Considering the crosstalk between OPCs and microglia has been widely reported in the context of demyelinating insults, we also assessed microglia activation. We observed that montelukast influenced the phenotype of microglial cells, increasing the number of M2 polarized microglia/macrophages, over the M1 phenotype, at acute phase after MCAo. In conclusion, we demonstrated that montelukast improves fiber re-organization and long-term functional recovery after brain ischemia, enhancing recruitment and maturation of OPCs. The present data suggest that montelukast, an already approved drug, could be "repositioned "as a protective drug in stroke acting also on fiber re-organization.

Thymosin β4 for the treatment of acute stroke: neurorestorative or neuroprotective?

INTRODUCTION

Thymosin β4 (Tβ4) is a 5K peptide which influences cellular migration by inhibiting organization of the actin-cytoskeleton. Treatment of acute stroke presently involves use of rt-PA and/or endovascular treatment with thrombectomy, both of which have time limitations. Therefore, development of a treatment beyond these times is necessary as most stroke patients present beyond these time limits. A drug which could be administered within 24 h from symptom onset would provide substantial benefit.

AREAS COVERED

This review summarizes the data and results of two in-vivo studies testing Tβ4 in an embolic stroke model of young and aged rats. In addition, we describe in-vitro investigations of the neurorestorative and neuroprotective properties of Tβ4 in a variety of neuroprogenitor and oligoprogenitor cell models.

EXPERT OPINION

Tβ4 acts as a neurorestorative agent when employed in a young male rat model of embolic stroke while in an aged model it acts a neuroprotectant. However evaluation of Tβ4 as a treatment of stroke requires further preclinical evaluation in females and in males and females with comorbidities such as, hypertension and diabetes in models of embolic stroke to further define the mechanism of action and potential as a treatment of stroke in humans.

Thymosin β4 prevents oxygen-glucose deprivation/reperfusion-induced injury in rat cortical neurons

PURPOSE

This study investigated whether thymosin (T) β4 protects against oxygen-glucose deprivation/reperfusion (OGD/R) injury in rat cortical neurons, as well as the underlying mechanisms.

METHODS

Primary rat cortical neurons were transfected with Tβ4 overexpression plasmid; the transfection efficiency was confirmed by detecting Tβ4 expression by fluorescence quantitative PCR and Western blotting. The OGD/R model was established and apoptotic cells were quantified by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling. Structural changes in the endoplasmic reticulum were visualized by transmission electron microscopy. The expression levels of 78-kDa glucose-regulated protein (GRP) 78, C/EBP-homologous protein (CHOP), B-cell lymphoma (Bcl)-2, and Bcl-2-associated X protein (Bax) were determined by Western blotting. The effect of Tβ4 on OGD/R injury was evaluated by adding exogenous Tβ4 to neuronal cultures.

RESULTS

Cortical neurons were identified by the expression of neuron-specific enolase. In OGD/R cells, the rate of apoptosis was increased and GRP78, CHOP, and Bax were upregulated whereas Bcl-2 was downregulated relative to the control group. These effects were reversed by Tβ4 overexpression. Endoplasmic reticulum (ER) stress was observed in the OGD/R group, but this was abolished in neurons overexpressing Tβ4. The protective effect of Tβ4 against OGD/R injury was also demonstrated in cells treated with exogenous Tβ4 (10 ng/mL), which blocked OGD/R-induced apoptosis by inhibiting ER stress-related and pro-apoptotic protein expression.

CONCLUSION

Tβ4 prevents OGD/R-induced ER stress-dependent apoptosis in cortical neurons, and is a potential treatment for cerebral ischemia-reperfusion injury.

Thymosins in multiple sclerosis and its experimental models: moving from basic to clinical application

BACKGROUND

Multiple sclerosis (MS) afflicts more than 2.5 million individuals worldwide and this number is increasing over time. Within the past years, a great number of disease-modifying treatments have emerged; however, efficacious treatments and a cure for MS await discovery. Thymosins, soluble hormone-like peptides produced by the thymus gland, can mediate immune and non-immune physiological processes and have gained interest in recent years as therapeutics in inflammatory and autoimmune diseases.

METHODS

Pubmed was searched with no time constraints for articles using a combination of the keywords "thymosin/s" or "thymus factor/s" AND "multiple sclerosis", mesh terms with no language restriction.

RESULTS

Here, we review the state-of-the-art on the effects of thymosins on MS and its experimental models. In particular, we describe what is known in this field on the roles of thymosin-α1 (Tα1) and -β4 (Tβ4) as potential anti-inflammatory as well as neuroprotective and remyelinating molecules and their mechanisms of action.

CONCLUSION

Based on the data that Tα1 and Tβ4 act as anti-inflammatory molecules and as inducers of myelin repair and neuronal protection, respectively, a possible therapeutic application in MS for Tα1 and Tβ4 alone or combined with other approved drugs may be envisaged. This approach is reasonable in light of the current clinical usage of Tα1 and data demonstrating the safety, tolerability and efficacy of Tβ4 in clinical practice.

miR-146a mediates thymosin β4 induced neurovascular remodeling of diabetic peripheral neuropathy in type-II diabetic mice

Diabetes induces neurovascular dysfunction leading to peripheral neuropathy. MicroRNAs (miRNAs) affect many biological processes and the development of diabetic peripheral neuropathy. In the present study, we investigated whether thymosin-β4 (Tβ4) ameliorates diabetic peripheral neuropathy and whether miR-146a mediates the effect of Tβ4 on improved neurovascular function. Male Type II diabetic BKS. Cg-m+/+Lepr^db/J (db/db) mice at age 20 weeks were treated with Tβ4 for 8 consecutive weeks, and db/db mice treated with saline were used as a control group. Compared to non-diabetic mice, diabetic mice exhibited substantially reduced miR-146a expression, and increased IL-1R-associated kinase-1 (IRAK1), tumor necrosis factor (TNFR)-associated factor 6 (TRAF6) levels and nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) activity in sciatic nerve tissues. Treatment of diabetic mice with Tβ4 significantly elevated miR-146a levels and overcame the effect of diabetes on these proteins. Tβ4 treatment substantially improved motor and sensory conduction velocity of the sciatic nerve, which was associated with improvements in sensory function. Tβ4 treatment significantly increased intraepidermal nerve fiber density and augmented local blood flow and the density of fluorescein isothiocyanate (FITC)-dextran perfused vessels in the sciatic nerve tissue. In vitro, treatment of dorsal root ganglion (DRG) neurons and mouse dermal endothelial cells (MDEs) with Tβ4 significantly increased axonal outgrowth and capillary-like tube formation, whereas blocking miR-146a attenuated Tβ4-induced axonal outgrowth and capillary tube formation, respectively. Our data indicate that miR-146a may mediate Tβ4-induced neurovascular remodeling in diabetic mice, by suppressing pro-inflammatory signals.

SIL1 deficiency causes degenerative changes of peripheral nerves and neuromuscular junctions in fish, mice and human

BACKGROUND

Marinesco-Sjögren Syndrome (MSS) is a rare neuromuscular condition caused by recessive mutations in the SIL1 gene resulting in the absence of functional SIL1 protein, a co-chaperone for the major ER chaperone, BiP. As BiP is decisive for proper protein processing, loss of SIL1 results in the accumulation of misshaped proteins. This accumulation likely damages and destroys cells in vulnerable tissues, leading to congenital cataracts, cerebellar ataxia, vacuolar myopathy and other MSS phenotypes. Whether the peripheral nervous system (PNS) is affected in MSS has not been conclusively shown.

METHODS

To study PNS vulnerability in MSS, intramuscular nerves fibres from MSS patients and from SIL1-deficient mice (woozy) as well as sciatic nerves and neuromuscular junctions (NMJ) from these mice have been investigated via transmission electron microscopic and immunofluorescence studies accompanied by transcript studies and unbiased proteomic profiling. In addition, PNS and NMJ integrity were analyzed via immunofluorescence studies in an MSS-zebrafish model which has been generated for that purpose.

RESULTS

Electron microscopy revealed morphological changes indicative of impaired autophagy and mitochondrial maintenance in distal axons and in Schwann cells. Moreover, changes of the morphology of NMJs as well as of transcripts encoding proteins important for NMJ function were detected in woozy mice. These findings were in line with a grossly abnormal structure of NMJs in SIL1-deficient zebrafish embryos. Proteome profiling of sciatic nerve specimens from woozy mice revealed altered levels of proteins implicated in neuronal maintenance suggesting the activation of compensatory mechanisms.

CONCLUSION

Taken together, our combined data expand the spectrum of tissues affected by SIL1-loss and suggest that impaired neuromuscular transmission might be part of MSS pathophysiology.

Angiopoietin-1/Tie2 signaling pathway contributes to the therapeutic effect of thymosin β4 on diabetic peripheral neuropathy

Angiopoietin-1 (Ang1) and its receptor Tie2 regulate vascular function. Our previous study demonstrated that thymosin beta 4 (Tβ4) ameliorates neurological function of diabetic peripheral neuropathy. Mechanisms underlying the therapeutic effect of Tβ4 on diabetic peripheral neuropathy have not been fully investigated. The present in vivo study investigated whether the Ang1/Tie2 signaling pathway is involved in Tβ4-improved neurovascular remodeling in diabetic peripheral neuropathy. Diabetic BKS. Cg-m+/+Lepr^db/J (db/db) mice at age 20 weeks were treated with Tβ4 and neutralizing antibody against mouse Tie2 for 4 consecutive weeks. Neurological functional and neurovascular remodeling were measured. Administration of the neutralizing antibody against Tie2 attenuated the therapeutic effect of Tβ4 on improved diabetic peripheral neuropathy as measured by motor and sensory nerve conduction velocity and thermal hypoesthesia compared to diabetic db/db mice treated with Tβ4 only. Histopathological analysis revealed that the neutralizing antibody against Tie2 abolished Tβ4-increased microvascular density in sciatic nerve and intraepidermal nerve fiber density, which were associated with suppression of Tβ4-upregulated occludin expression and Tβ4-reduced protein levels of nuclear factor-κB (NF-κB) and vascular cell adhesion molecule-1 (VCAM1). Our data provide in vivo evidence that the Ang1/Tie2 pathway contributes to the therapeutic effect of Tβ4 on diabetic peripheral neuropathy.

RGN-259 (thymosin β4) improves clinically important dry eye efficacies in comparison with prescription drugs in a dry eye model

This study evaluated the clinical activity of RGN-259 (thymosin β4) in comparison with cyclosporine A (CsA), diquafosol (DQS), and lifitegrast (LFA) in a murine model of dry eye. The model was NOD.B10-H2^b mice in a 30–40% humidified environment together with daily scopolamine hydrobromide injections for 10 days. After desiccation stress, all drugs were evaluated after 10 treatment days. RGN-259 increased tear production similar to that in the DQS- and LFA-treated mice while CsA was inactive. RGN-259 improved corneal smoothness and decreased fluorescein staining similar to that of LFA group while CsA and DQS were inactive. Corneal epithelial detachment was reduced by RGN-259, and DQS and LFA showed similar activity but the CsA was inactive. RGN-259 increased conjunctival goblet cells and mucin production comparable to that seen with CsA, while DQS and LFA were inactive. RGN-259 reduced the over-expression of inflammatory factors comparable to that with CsA and LFA, while DQS was inactive. RGN-259 increased mucin production comparable to that observed with CsA, while DQS and LFA were inactive. In conclusion, RGN-259 promoted recovery of mucins and goblet cells, improved corneal integrity, and reduced inflammation in a dry eye mouse model and was equal to or more effective than prescription treatments.

Thymosin β4 Deficiency Exacerbates Renal and Cardiac Injury in Angiotensin-II-Induced Hypertension

Thymosin β4 (Tβ4), a ubiquitous peptide, regulates several cellular processes that include cell morphology, wound healing, and inflammatory response. Administration of exogenous Tβ4 is protective in diabetic nephropathy and in a unilateral ureteral obstruction model. However, the role of endogenous Tβ4 in health and disease conditions remains unclear. To elucidate the pathophysiological role of endogenous Tβ4 in hypertension, we examined angiotensin-II (Ang-II)-induced renal and cardiac damage in Tβ4 knockout (Tβ4 KO) mice. Tβ4 KO and wild-type C57BL/6 mice were infused continuously for 6 weeks with either vehicle or Ang-II (980 ng/kg per minute). At baseline, Tβ4 deficiency did not affect renal and cardiac function. Systolic blood pressure in the Ang-II group was similar in wild-type and Tβ4 KO mice (wild-type Ang-II, 179.25±10.11 mm Hg; Tβ4 KO Ang-II, 169.81±6.54 mm Hg). Despite the similar systolic blood pressure after Ang-II infusion, Tβ4-deficient mice had dramatically increased albuminuria and decreased nephrin expression in the kidney (P<0.005). In the heart of Tβ4 KO mice, Ang-II reduced ejection fraction and shortening fraction (ejection fraction: wild-type Ang-II 77.95%±1.03%; Tβ4 KO Ang-II 62.58%±3.25%; P<0.005), which was accompanied by cardiac hypertrophy and left ventricular dilatation. In addition, renal and cardiac infiltration of CD68 macrophages, intercellular adhesion molecule-1, and total collagen content were increased after Ang-II infusion in Tβ4 KO mice (P<0.005). Overall, our data indicate that endogenous Tβ4 is crucial in preventing tissue injury from Ang-II-induced hypertension. This study gives new insights into the protective role of endogenous Tβ4 in hypertensive end-organ damage.

Thymosin β4 for the treatment of acute stroke in aged rats

Thymosin β4 (Tβ4) is a 5K peptide which influences cellular migration by inhibiting organization of the actin-cytoskeleton. Tβ4 has neurorestorative properties and is a potential candidate for the treatment of sub-acute stroke. Previous research demonstrated that Tβ4 improved neurological outcome in a young (3 months) rat model of embolic stroke. We hypothesized that Tβ4 would improve neurological outcome in an aged rat model of embolic stroke when administered 24h after embolic stroke. Aged Male Wistar rats (Charles River, France 18-21 months) were subjected to embolic middle cerebral artery occlusion (MCAo). Rats were randomized to receive Tβ4 (12mg/kg, RegeneRx Biopharmaceuticals, Inc.) or control 24h after MCAo and then every 3days for 4 additional doses. The dose of 12mg/kg was the maximal dose of Tβ4 that showed functional improvement in a young rat model of embolic stroke. Functional tests (adhesive-removal test (ART), foot fault test (FFT) and the modified Neurological Severity Score (mNSS)) were performed weekly. The rats were sacrificed 56days after MCAo and lesion volumes were measured. Immunohistochemical analysis for oligodendrogenesis, myelination and gliosis was also performed. Twenty-three rats were included in the study: control group (n=12) and Tβ4 group (n=11). After randomization, there were three deaths in both the control and Tβ4 groups. The Tβ4 treatment reduced infarct volume by more than 50% (12.8%±9.3%, mean±SE, p<0.05) compared to the control group (26.0%±4.3%). However, Tβ4 did not show improvement in functional outcome compared to control. There was no significant increase in oligodendrogenesis, myelination and gliosis between control and treatment with Tβ4, however, we unexpectedly observed that overall (control and Tβ4 groups) astrocytic gliosis as measured by GFAP immunoreactivity was significantly inversely correlated with neurological outcome measured using the modified Neurological Severity Score (mNSS) (p<0.01), suggesting that greater gliosis may be related to improvement of neurological outcome in aged rats. In summary, Tβ4 treatment of stroke aged rats significantly reduces infarct volume compared to vehicle treated stroke, however, Tβ4 treatment did not show improvement in functional outcome, myelination or gliosis when compared to control. GFAP staining was significantly inversely correlated to improvement in the mNSS, suggesting that gliosis in the aged rat may be of benefit in improvement of functional outcome.

Electromagnetic Fields for the Regulation of Neural Stem Cells

Localized magnetic fields (MFs) could easily penetrate the scalp, skull, and meninges, thus inducing an electrical current in both the central and peripheral nervous systems, which is primarily used in transcranial magnetic stimulation (TMS) for inducing specific effects on different regions or cells that play roles in various brain activities. Studies of repetitive transcranial magnetic stimulation (rTMS) have led to novel attractive therapeutic approaches. Neural stem cells (NSCs) in adult human brain are able to self-renew and possess multidifferential ability to maintain homeostasis and repair damage after acute central nervous system. In the present review, we summarized the electrical activity of NSCs and the fundamental mechanism of electromagnetic fields and their effects on regulating NSC proliferation, differentiation, migration, and maturation. Although it was authorized for the rTMS use in resistant depression patients by US FDA, there are still unveiling mechanism and limitations for rTMS in clinical applications of acute central nervous system injury, especially on NSC regulation as a rehabilitation strategy. More in-depth studies should be performed to provide detailed parameters and mechanisms of rTMS in further studies, making it a powerful tool to treat people who are surviving with acute central nervous system injuries.

High-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Improves Functional Recovery by Enhancing Neurogenesis and Activating BDNF/TrkB Signaling in Ischemic Rats

Repetitive transcranial magnetic stimulation (rTMS) has rapidly become an attractive therapeutic approach for stroke. However, the mechanisms underlying this remain elusive. This study aimed to investigate whether high-frequency rTMS improves functional recovery mediated by enhanced neurogenesis and activation of brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway and to compare the effect of conventional 20 Hz rTMS and intermittent theta burst stimulation (iTBS) on ischemic rats. Rats after rTMS were sacrificed seven and 14 days after middle cerebral artery occlusion (MCAO), following evaluation of neurological function. Neurogenesis was measured using specific markers: Ki67, Nestin, doublecortin (DCX), NeuN and glial fibrillary acidic protein (GFAP), and the expression levels of BDNF were visualized by Western blotting and RT-PCR analysis. Both high-frequency rTMS methods significantly improved neurological function and reduced infarct volume. Moreover, 20 Hz rTMS and iTBS significantly promoted neurogenesis, shown by an increase of Ki67/DCX, Ki67/Nestin, and Ki67/NeuN-positive cells in the peri-infarct striatum. These beneficial effects were accompanied by elevated protein levels of BDNF and phosphorylated-TrkB. In conclusion, high-frequency rTMS improves functional recovery possibly by enhancing neurogenesis and activating BDNF/TrkB signaling pathway and conventional 20 Hz rTMS is better than iTBS at enhancing neurogenesis in ischemic rats.

A Novel Therapeutic Peptide as a Partial Agonist of RANKL in Ischemic Stroke

The enhanced receptor activator of nuclear factor-κB (NFκB) ligand (RANKL) and its receptor (RANK) signal have been reported to attenuate ischemic brain injury through inhibition of Toll-like receptor (TLR) 4-mediated inflammation. However, augmentation of the RANKL/RANK signal also accelerates osteoporosis, which is a potential problem in clinical use of RANKL. Therefore, we developed novel peptides, microglial healing peptides (MHPs), which were based on the DE and/or EF loop of RANKL. Among them, MHP1 was the most effective inhibitor of TLR4-induced inflammations in microglia/macrophages. The effects depended on RANK, as confirmed by knockdown experiments. In contrast to RANKL, MHP1 did not stimulate osteoclast differentiation. Unexpectedly, MHP1 inhibited RANKL-induced osteoclast differentiation. These findings suggested that MHP1 was a partial agonist of RANKL, and administration of MHP1 attenuated ischemic injury by decreasing inflammation. MHP1 could be a novel therapeutic agent for treating ischemic stroke.

Pharmacological approaches to intervention in hypomyelinating and demyelinating white matter pathology

White matter disease afflicts both developing and mature central nervous systems. Both cell intrinsic and extrinsic dysregulation result in profound changes in cell survival, axonal metabolism and functional performance. Experimental models of developmental white matter (WM) injury and demyelination have not only delineated mechanisms of signaling and inflammation, but have also paved the way for the discovery of pharmacological approaches to intervention. These reagents have been shown to enhance protection of the mature oligodendrocyte cell, accelerate progenitor cell recruitment and/or differentiation, or attenuate pathological stimuli arising from the inflammatory response to injury. Here we highlight reports of studies in the CNS in which compounds, namely peptides, hormones, and small molecule agonists/antagonists, have been used in experimental animal models of demyelination and neonatal brain injury that affect aspects of excitotoxicity, oligodendrocyte development and survival, and progenitor cell function, and which have been demonstrated to attenuate damage and improve WM protection in experimental models of injury. The molecular targets of these agents include growth factor and neurotransmitter receptors, morphogens and their signaling components, nuclear receptors, as well as the processes of iron transport and actin binding. By surveying the current evidence in non-immune targets of both the immature and mature WM, we aim to better understand pharmacological approaches modulating endogenous oligodendroglia that show potential for success in the contexts of developmental and adult WM pathology. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

Rodent Gymnastics: Neurobehavioral Assays in Ischemic Stroke

Despite years of research, most preclinical trials on ischemic stroke have remained unsuccessful owing to poor methodological and statistical standards leading to "translational roadblocks." Various behavioral tests have been established to evaluate traits such as sensorimotor function, cognitive and social interactions, and anxiety-like and depression-like behavior. A test's validity is of cardinal importance as it influences the chance of a successful translation of preclinical results to clinical settings. The mission of choosing a behavioral test for a particular project is, therefore, imperative and the present review aims to provide a structured way to evaluate rodent behavioral tests with implications in ischemic stroke.

Thymosin β4 inhibits microglia activation through microRNA 146a in neonatal rats following hypoxia injury

Neuroinflammation mediated by activated microglia plays a pivotal role in the pathogenesis of neurological disorders, including hypoxic injury of the developing brain. Thymosin β4 (Tβ4), the major G-actin-sequestering molecule, has an anti-inflammatory effect and has been used to treat various neurological diseases. However, the effect of Tβ4 on hypoxia-induced microglia activation in the developing brain remains unclear. We investigate here the effect of Tβ4 on microglia activation of neonatal rats after hypoxia exposure. Tβ4 treatment was carried out on 1-day-old rats and BV-2 cells. Tβ4 expression in microglia was determined by quantitative real time-PCR, western blotting, and immunofluorescence staining. Secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nitric oxide (NO) was assessed by enzyme-linked immunosorbent assay and colorimetric assay. mRNA expression of TNF-α and IL-1β, and microRNA 146a expression was determined by quantitative real time-PCR. We showed that Tβ4 treatment significantly inhibited secretion of inflammatory mediators in the cerebellum of neonatal rats following hypoxia injury. Increased expression of endogenous Tβ4 in microglia was observed both in hypoxic rats and in BV-2 cells. Tβ4 treatment significantly inhibited the expression and secretion of hypoxia-induced TNF-α, IL-1β, and NO. Remarkably, microRNA 146a expression was found to have increased in Tβ4-treated BV-2 cells. We demonstrated the anti-inflammatory effect of Tβ4 in neonatal rats following hypoxic brain injury. More importantly, our data reveal, for the first time, that Tβ4 inhibits microglia activation in vitro. Therefore, this study contributes to understanding the role and mechanism of Tβ4 function in central nervous system diseases.

MALDI imaging mass spectrometry analysis-A new approach for protein mapping in multiple sclerosis brain lesions

Multiple sclerosis is a disease of the central nervous system characterized by recurrent inflammatory demyelinating lesions in the early disease stage. Lesion formation and mechanisms leading to lesion remyelination are not fully understood. Matrix Assisted Laser Desorption Ionisation Mass Spectrometry imaging (MALDI-IMS) is a technology which analyses proteins and peptides in tissue, preserves their spatial localization, and generates molecular maps within the tissue section. In a pilot study we employed MALDI imaging mass spectrometry to profile and identify peptides and proteins expressed in normal-appearing white matter, grey matter and multiple sclerosis brain lesions with different extents of remyelination. The unsupervised clustering analysis of the mass spectra generated images which reflected the tissue section morphology in luxol fast blue stain and in myelin basic protein immunohistochemistry. Lesions with low remyelination extent were defined by compounds with molecular weight smaller than 5300Da, while more completely remyelinated lesions showed compounds with molecular weights greater than 15,200Da. An in-depth analysis of the mass spectra enabled the detection of cortical lesions which were not seen by routine luxol fast blue histology. An ion mass, mainly distributed at the rim of multiple sclerosis lesions, was identified by liquid chromatography and tandem mass spectrometry as thymosin beta-4, a protein known to be involved in cell migration and in restorative processes. The ion mass of thymosin beta-4 was profiled by MALDI imaging mass spectrometry in brain slides of 12 multiple sclerosis patients and validated by immunohistochemical analysis. In summary, our results demonstrate the ability of the MALDI-IMS technology to map proteins within the brain parenchyma and multiple sclerosis lesions and to identify potential markers involved in multiple sclerosis pathogenesis and/or remyelination.

Thymosin β4 Promotes Dermal Healing

No agent has been identified that significantly accelerates the repair of chronic dermal wounds in humans. Thymosin beta 4 (Tβ4) is a small, abundant, naturally occurring regenerative protein that is found in body fluids and inside cells. It was found to have angiogenic and antiinflammatory activity and to be high in platelets that aggregate at the wound site. Thus we used Tβ4 initially in dermal healing. It has since been shown to have many activities important in tissue protection, repair, and regeneration. Tβ4 increases the rate of dermal healing in various preclinical animal models, including diabetic and aged animals, and is active for burns as well. Tβ4 also accelerated the rate of repair in phase 2 trials with patients having pressure ulcers, stasis ulcers, and epidermolysis bullosa wounds. It is safe and well tolerated and will likely have additional uses in the skin and in injured organs for tissue repair and regeneration.

Strategies targeting endogenous neurogenic cell response to improve recovery following traumatic brain injury

Traumatic brain injury (TBI) affects over 1.7 million people in the United States alone and poses many clinical challenges due to the variability of the injuries and complexity of biochemical mechanisms involved. Thus far, there is still no effective therapy for TBI. Failure of preventative therapeutic strategies has led studies focusing on regenerative approaches. Recent studies have shown evidence that mature brains harbors multipotent neural stem cells capable of becoming mature neurons in the neurogenic regions. Following brain insults including TBI, the injured brain has increased level of neurogenic response in the subventricular zone and dentate gyrus of the hippocampus and this endogenous response is associated with cognitive function following injury. In this review, we highlight recent development and strategies aimed at targeting this endogenous cell response to enhance post-TBI functional recovery. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Thymosin beta 4 up-regulates miR-200a expression and induces differentiation and survival of rat brain progenitor cells

Thymosin beta 4 (Tβ4), a secreted 43 amino acid peptide, promotes oligodendrogenesis, and improves neurological outcome in rat models of neurologic injury. We demonstrated that exogenous Tβ4 treatment up-regulated the expression of the miR-200a in vitro in rat brain progenitor cells and in vivo in the peri-infarct area of rats subjected to middle cerebral artery occlusion (MCAO). The up-regulation of miR-200a down-regulated the expression of the following targets in vitro and in vivo models: (i) growth factor receptor-bound protein 2 (Grb2), an adaptor protein involved in epidermal growth factor receptor (EGFR)/Grb2/Ras/MEK/ERK1/c-Jun signaling pathway, which negatively regulates the expression of myelin basic protein (MBP), a marker of mature oligodendrocyte; (ii) ERRFI-1/Mig-6, an endogenous potent kinase inhibitor of EGFR, which resulted in activation/phosphorylation of EGFR; (iii) friend of GATA 2, and phosphatase and tensin homolog deleted in chromosome 10 (PTEN), which are potent inhibitors of the phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway, and resulted in marked activation of AKT; and (iv) transcription factor, p53, which induces pro-apoptotic genes, and possibly reduced apoptosis of the progenitor cells subjected to oxygen glucose deprivation (OGD). Anti-miR-200a transfection reversed all the effects of Tβ4 treatment in vitro. Thus, Tβ4 up-regulated MBP synthesis, and inhibited OGD-induced apoptosis in a novel miR-200a dependent EGFR signaling pathway. Our findings of miR-200a-mediated protection of progenitor cells may provide a new therapeutic importance for the treatment of neurologic injury. Tβ4-induced micro-RNA-200a (miR-200a) regulates EGFR signaling pathways for MBP synthesis and apoptosis: up-regulation of miR-200a after Tβ4 treatment, increases MBP synthesis after targeting Grb2 and thereby inactivating c-Jun from inhibition of MBP synthesis; and also inhibits OGD-mediated apoptosis after targeting EGFR inhibitor (Mig-6), PI3K inhibitors (FOG2 and Pten) and an inducer (p53) of pro-apoptotic genes, for AKT activation and down-regulation of p53. These findings may contribute the therapeutic benefits for stroke and other neuronal diseases associated with demyelination disorders.

Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial

PURPOSE

Standard therapies for severe dry eye are limited and fail to resolve the problem. The purpose of this study was to evaluate the safety and efficacy of Thymosin β4 eye drops (RGN-259) as a novel therapy for severe dry eye disease (including that associated with graft vs. host disease).

METHODS

A small, multicenter, randomized, double-masked, placebo-controlled 56-day phase 2 clinical trial including a 28-day follow-up at 2 US sites. Nine patients with severe dry eye were treated with either RGN-259 (0.1%) or vehicle control 6 times daily over a period of 28 days. Dry eye sign and symptom assessments, such as ocular discomfort (using the OSDI questionnaire) and corneal fluorescein staining (using the NEI workshop grading system), were evaluated at various time points.

RESULTS

Statistically significant differences in both symptom and sign assessments, were seen at various time points throughout the study. Of particular note at day 56, the RGN-259-treated group (12 eyes) had 35.1% reduction of ocular discomfort compared with vehicle control (6 eyes) (P = 0.0141), and 59.1% reduction of total corneal fluorescein staining compared with vehicle control (P = 0.0108). Other improvements seen in the RGN-259-treated patients included tear film breakup time and increased tear volume production.

CONCLUSIONS

In this small trial, RGN-259 eye drops were safe and well tolerated and met key efficacy objectives with statistically significant symptom and sign improvements, compared with vehicle control, at various time intervals, including 28-days posttreatment. CLINICAL TRIAL REGISTRATION--URL: http://www.clinicaltrials.gov. Unique identifier: NCT01393132.

Peptide fragment of thymosin β4 increases hippocampal neurogenesis and facilitates spatial memory

Although several studies have suggested the neuroprotective effect of thymosin β4 (TB4), a major actin-sequestering protein, on the central nervous system, little is understood regarding the action of N-acetyl-serylaspartyl-lysyl-proline (Ac-SDKP), a peptide fragment of TB4 on brain function. Here, we examined neurogenesis-stimulative effect of Ac-SDKP. Intrahippocampal infusion of Ac-SDKP facilitated the generation of new neurons in the hippocampus. Ac-SDKP-treated mouse hippocampus showed an increase in β-catenin stability with reduction of glycogen synthase kinase-3β (GSK-3β) activity. Moreover, inhibition of vascular endothelial growth factor (VEGF) signaling blocked Ac-SDKP-facilitated neural proliferation. Subchronic intrahippocampal infusion of Ac-SDKP also increased spatial memory. Taken together, these data demonstrate that Ac-SDKP functions as a regulator of neural proliferation and indicate that Ac-SDKP may be a therapeutic candidate for diseases characterized by neuronal loss.

Effects of Tetramethylpyrazine on Functional Recovery and Neuronal Dendritic Plasticity after Experimental Stroke

The 2,3,5,6-tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic stroke by Chinese doctors. Here, we report the effects of TMP on functional recovery and dendritic plasticity after ischemic stroke. A classical model of middle cerebral artery occlusion (MCAO) was established in this study. The rats were assigned into 3 groups: sham group (sham operated rats treated with saline), model group (MCAO rats treated with saline) and TMP group (MCAO rats treated with 20 mg/kg/d TMP). The neurological function test of animals was evaluated using the modified neurological severity score (mNSS) at 3 d, 7 d, and 14 d after MCAO. Animals were euthanized for immunohistochemical labeling to measure MAP-2 levels in the peri-infarct area. Golgi-Cox staining was performed to test effect of TMP on dendritic plasticity at 14 d after MCAO. TMP significantly improved neurological function at 7 d and 14 d after ischemia, increased MAP-2 level at 14 d after ischemia, and enhanced spine density of basilar dendrites. TMP failed to affect the spine density of apical dendrites and the total dendritic length. Data analyses indicate that there was significant negative correlation between mNSS and plasticity measured at 14 d after MCAO. Thus, enhanced dendritic plasticity contributes to TMP-elicited functional recovery after ischemic stroke.

Thymosin β4 significantly reduces the signs of dryness in a murine controlled adverse environment model of experimental dry eye

OBJECTIVE

Dry eye syndrome is a common condition that affects up to 20% of the population aged 45 and older. There are no successful treatments to date. The goal of this research was to determine the efficacy of various doses and the optimal frequency of thymosin β4 (Tβ4) treatment in a murine severe dry eye model.

RESEARCH DESIGN AND METHODS

The study was performed using a controlled adverse environment chamber (CAE) in combination with scopolamine to induce moderate to severe dry eye in mice. The study included five mice per group and tested six different doses of Tβ4 twice per day for 12 days. Tβ4 at 0.1% was also administered 2 - 4 times per day for 12 days. Healing was measured by fluorescein staining.

MAIN OUTCOME MEASURES

Tβ4 significantly reduced the signs of dry eye relative to controls. The treatment effect was more pronounced than the positive controls, doxycycline and Restasis (cyclosporine 0.05%). Active doses of 0.1 and 0.5% were determined, and it was found that the frequency of dosing at 2 times per day was the most effective for healing.

CONCLUSIONS

Tβ4 has the potential to be an important new effective therapeutic for dry eye.