Neuroprotective effects of thymosin beta4 in experimental models of excitotoxicity

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.

Effects of Thymosin β4 on Myocardial Apoptosis in Burned Rats

The aim of this study was to investigate the effects of thymosin β4 on myocardial apoptosis following burns. Fifty healthy Sprague Dawley (SD) rats were randomly divided into the normal control group, resuscitation group the low-dose Tβ4 (thymosin β4) group (2g), the medium-dose Tβ4 group (6g), and the high-dose Tβ4 group (18g). The rats were immersed in 95°C hot water for 18 seconds, and then the model of 30% body surface area (TBSA) III° scald was established. The resuscated rats were injected with lactate Ringer's solution for antishock rehydration, while the Tβ4 treatment group was injected with lactate Ringer's solution for antishock rehydration, and the animals were sacrificed 6 h after scald. The degree of histopathological damage was observed by HE (hematoxylin and eosin) staining. Western blot was used to detect STAT1 and STAT3 protein expression levels. Real-time PCR was used to detect mRNA expressions of STAT1 and STAT3. The results showed that the apoptosis rate of the resuscitation group was significantly higher than that of the control group (P < 0.01). Compared with the resuscitation group, the apoptosis rate of thymosin β4 in the treatment group was significantly reduced (P < 0.01). Compared with the normal control group, the expression of STAT1 protein was increased and the expression of STAT3 protein was decreased in model group rats after ischemia and reperfusion. Compared with the model group, the expression of STAT1 protein decreased and the expression of STAT3 protein increased after ischemia-reperfusion in the thymosin β4 treatment group. Thymosin β4 may protect the myocardium by downregulating STAT1 and upregulating STAT3 expression and inhibiting myocardial apoptosis induced by ischemia and reperfusion after severe scald injury.

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.

N-Acetyl-Seryl-Aspartyl-Lysyl-Proline Augments Thrombolysis of tPA (Tissue-Type Plasminogen Activator) in Aged Rats After Stroke

Background and Purpose- Stroke is a leading cause of disability worldwide, mainly affecting the elderly. However, preclinical studies in aged ischemic animals are limited. N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) is a naturally occurring tetrapeptide with vascular-protective properties. The present study investigated the effect of AcSDKP on tPA (tissue-type plasminogen activator)-induced thrombolysis in aged rats after ischemic stroke. Methods- Aged male rats (18 months) were subjected to embolic middle cerebral artery occlusion. Rats subjected to 4 hours of middle cerebral artery occlusion were randomized into the following groups: (1) AcSDKP; (2) tPA; (3) AcSDKP in combination with tPA; and (4) saline. Neurological deficits, cerebral microvascular patency and integrity, and infarction were examined at 1 day and 7 days after middle cerebral artery occlusion. In vitro experiments were performed to examine the effect of AcSDKP on aged cerebral endothelial cell permeability. Results- Compared with saline, AcSDKP, or tPA as monotherapy did not have any therapeutic effects, whereas AcSDKP in combination with tPA significantly reduced cerebral tissue infarction and improved neurological outcome without increasing cerebral hemorrhage. Concurrently, the combination treatment significantly augmented microvascular perfusion and reduced thrombosis and blood-brain barrier leakage. In vitro, compared with cerebral endothelial cells from ischemic adult rats, the endothelial cells from ischemic aged rats exhibited significantly increased leakage. AcSDKP suppressed tPA-induced aged endothelial cell leakage and reduced expression of ICAM-1 (intercellular adhesion molecule 1) and NF (nuclear factor)-κB. Conclusions- The present study provides evidence for the therapeutic efficacy of AcSDKP in combination tPA for the treatment of embolic stroke in aged rats at 4 hours after stroke onset. AcSDKP likely acts on cerebral endothelial cells to enhance the benefits of tPA by increasing tissue perfusion and augmenting the integrity of the blood-brain barrier. Visual Overview- An online visual overview is available for this article.

Effects of thymosin β4 on oxygen‑glucose deprivation and reoxygenation‑induced injury

Cerebral ischemia causes severe brain injury and results in selective neuronal death through programmed cell death mechanisms, including apoptosis and autophagy. Minimizing neuronal injury has been considered a hot topic among clinicians. The present study elucidated the effect of thymosin β4 (Tβ4) on neuronal death induced by cerebral ischemia/reperfusion in PC12 cells that were subjected to oxygen‑glucose deprivation and reoxygenation (OGD/R). The survival, apoptotic and autophagy rates of PC12 cells were investigated. Tβ4 pre‑conditioning prior to OGD/R was performed to evaluate PC12‑cell viability and the protective mechanisms of Tβ4. Tβ4 significantly increased cell survival after OGD/R. Tβ4 inhibited the release of lactate dehydrogenase, downregulated malondialdehyde and upregulated the activities of glutathione peroxidase and superoxide dismutase. In addition, Tβ4 attenuated OGD/R‑associated decreases in the expression of P62 and the anti‑apoptotic protein B‑cell lymphoma‑2, as well as the upregulation of autophagy mediators, including autophagy‑related protein‑5 and the ratio of microtubule‑associated protein 1 light chain 3 (LC3) II vs. LC3 I. These results suggested that Tβ4 effectively inhibits cell apoptosis and autophagy induced by OGD/R. To the best of our knowledge, the present study was the first to report on the antioxidant, anti‑apoptotic and anti‑autophagic effects of Tβ4 in neuronal‑like PC12 cells. These results suggested that Tβ4 may be explored as a potential treatment for cerebral ischemia.

Proteomics in pediatric cystic craniopharyngioma

Adamantinomatous craniopharyngioma (ACP) is still often burdened by a poor prognosis in children as far as the risk of recurrence and the quality of life are concerned. Therefore, many efforts are now dedicated to investigate the molecular characteristics of this tumor aiming at finding new therapeutic options. ACP is prevalently a cystic lesion so that an increasing number of researches are focused on the analysis of its cystic content. In the present article, the main results of the current proteomic analysis (PA) on the ACP fluid are summarized. Both "bottom-up" and "top-down" approaches have been utilized. In the bottom-up approach, proteins and peptides are enzymatically or chemically digested prior to liquid chromatography and mass spectrometry analyses. The bottom-up approach pointed out several proteins of the inflammation (namely, α2-HS-glycoprotein, α1-antichymotrypsin and apolipoproteins) as possibly involved in the genesis and growth of the cystic component of ACP. The top-down strategy analyzes proteins and peptides in the intact state, making it particularly suitable for the identification of peptides and low molecular weight proteins and for the characterization of their possible isoforms and post-translational modifications. The top-down approach disclosed the presence of the thymosin β family. Thymosin β4, in particular, which is involved in the cytoskeleton organization and migration of several tumors, could play a role in the progression of ACP. Finally, PA was utilized to investigate alterations in cyst fluid character after treatment with interferon-α. The analyzed samples showed a progressive reduction of the levels of α-defensins (proteins involved in the inflammatory-mediated response) after the intracystic injection of interferon-α, thus reinforcing the hypothesis that inflammation contributes to ACP cyst pathogenesis. Additional studies on the solid component of ACP are still necessary to further validate the previous results and to identify possible markers for targeted therapy.

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.

Thymosin β4 up-regulation of microRNA-146a promotes oligodendrocyte differentiation and suppression of the Toll-like proinflammatory pathway

Thymosin β4 (Tβ4), a G-actin-sequestering peptide, improves neurological outcome in rat models of neurological injury. Tissue inflammation results from neurological injury, and regulation of the inflammatory response is vital for neurological recovery. The innate immune response system, which includes the Toll-like receptor (TLR) proinflammatory signaling pathway, regulates tissue injury. We hypothesized that Tβ4 regulates the TLR proinflammatory signaling pathway. Because oligodendrogenesis plays an important role in neurological recovery, we employed an in vitro primary rat embryonic cell model of oligodendrocyte progenitor cells (OPCs) and a mouse N20.1 OPC cell line to measure the effects of Tβ4 on the TLR pathway. Cells were grown in the presence of Tβ4, ranging from 25 to 100 ng/ml (RegeneRx Biopharmaceuticals Inc., Rockville, MD), for 4 days. Quantitative real-time PCR data demonstrated that Tβ4 treatment increased expression of microRNA-146a (miR-146a), a negative regulator the TLR signaling pathway, in these two cell models. Western blot analysis showed that Tβ4 treatment suppressed expression of IL-1 receptor-associated kinase 1 (IRAK1) and tumor necrosis factor receptor-associated factor 6 (TRAF6), two proinflammatory cytokines of the TLR signaling pathway. Transfection of miR-146a into both primary rat embryonic OPCs and mouse N20.1 OPCs treated with Tβ4 demonstrated an amplification of myelin basic protein (MBP) expression and differentiation of OPC into mature MBP-expressing oligodendrocytes. Transfection of anti-miR-146a nucleotides reversed the inhibitory effect of Tβ4 on IRAK1 and TRAF6 and decreased expression of MBP. These data suggest that Tβ4 suppresses the TLR proinflammatory pathway by up-regulating miR-146a.

Top-down proteomics with mass spectrometry imaging: a pilot study towards discovery of biomarkers for neurodevelopmental disorders

In the developing mammalian brain, inhibition of NMDA receptor can induce widespread neuroapoptosis, inhibit neurogenesis and cause impairment of learning and memory. Although some mechanistic insights into adverse neurological actions of these NMDA receptor antagonists exist, our understanding of the full spectrum of developmental events affected by early exposure to these chemical agents in the brain is still limited. Here we attempt to gain insights into the impact of pharmacologically induced excitatory/inhibitory imbalance in infancy on the brain proteome using mass spectrometric imaging (MSI). Our goal was to study changes in protein expression in postnatal day 10 (P10) rat brains following neonatal exposure to the NMDA receptor antagonist dizocilpine (MK801). Analysis of rat brains exposed to vehicle or MK801 and comparison of their MALDI MS images revealed differential relative abundances of several proteins. We then identified these markers such as ubiquitin, purkinje cell protein 4 (PEP-19), cytochrome c oxidase subunits and calmodulin, by a combination of reversed-phase (RP) HPLC fractionation and top-down tandem MS platform. More in-depth large scale study along with validation experiments will be carried out in the future. Overall, our findings indicate that a brief neonatal exposure to a compound that alters excitatory/inhibitory balance in the brain has a long term effect on protein expression patterns during subsequent development, highlighting the utility of MALDI-MSI as a discovery tool for potential biomarkers.

Combination treatment with N-acetyl-seryl-aspartyl-lysyl-proline and tissue plasminogen activator provides potent neuroprotection in rats after stroke

BACKGROUND AND PURPOSE

N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), an endogenously produced circulating peptide in humans and rodents, exerts anti-inflammatory and cardioprotective activities in various cardiovascular diseases.

METHODS

The present study evaluated the neuroprotective effect of AcSDKP alone and in combination with thrombolytic therapy in a rat model of embolic focal cerebral ischemia.

RESULTS

We found that treatment with AcSDKP alone at 1 hour or the combination treatment with AcSDKP and tissue plasminogen activator (tPA) at 4 hours after stroke onset substantially increased AcSDKP levels in plasma and cerebrospinal fluid and robustly reduced infarct volume and neurological deficits, without increasing the incidence of brain hemorrhage compared with ischemic rats treated with saline, AcSDKP alone at 4 hours, and tPA alone at 4 hours. Moreover, the combination treatment considerably reduced the density of nuclear transcription factor-κB (NF-κB), transforming growth factor β (TGF-β), and plasminogen activator inhibitor-1 (PAI-1) positive cerebral blood vessels in the ischemic brain, all of which were associated with reduced microvascular fibrin extravasation and platelet accumulation compared with tPA monotherapy. In vitro, AcSDKP blocked fibrin-elevated TGF-β1, PAI-1, and NF-κB proteins in primary human brain microvascular endothelial cells.

CONCLUSIONS

Our data indicate that AcSDKP passes the blood-brain barrier, and that treatment of acute stroke with AcSDKP either alone at 1 hour or in combination with tPA at 4 hours of the onset of stroke is effective to reduce ischemic cell damage in a rat model of embolic stroke. Inactivation of TGF-β and NF-κB signaling by AcSDKP in the neurovascular unit may underlie the neuroprotective effect of AcSDKP.

Identification of thymosins β4 and β 10 in paediatric craniopharyngioma cystic fluid

BACKGROUND

Adamantinomatous craniopharyngioma is the third most recurrent paediatric brain tumour. Although histologically benign, it behaves aggressively as a malignant tumour due to invasion of the hypothalamus and visual pathways. Surgery is still the first and almost the only mode of treatment, although serious damage can occur as a consequence of tumour localization. The proteomic characterization of the intracystic tumoural fluid could contribute to the comprehension of the tumorigenesis processes and to the development of therapeutic targets to reduce cyst volume, allowing less invasive surgery and/or delay of the radical resection of the tumour mass and the collateral serious effects.

METHODS

Intracystic fluid was analysed by a LC-ESI-IT-MS top-down platform after acidification, deproteinization and chloroform liquid/liquid extraction.

FINDINGS

Thymosin β4 and β10 peptides were for the first time identified in the intracystic fluid of adamantinomatous craniopharyngioma by low- and high-resolution MS analysis coupled with LC. The two peptides showed the same distribution trend in the analysed samples. Thymosin β4 and β10 were present in 77 % of the analysed samples. These peptides were not found in the cerebrospinal fluid available for two patients.

INTERPRETATION

The presence of β-thymosins in the intracystic fluid of the tumour confirmed the secretion of these proteins in the extracellular environment. Due to their G-actin-sequestering activity and antiapoptotic and anti-inflammatory properties, these peptides could be strictly involved in both tumour progression and cyst development and growth.

Effects of maternal separation and methamphetamine exposure on protein expression in the nucleus accumbens shell and core

Early life adversity has been suggested to predispose an individual to later drug abuse. The core and shell sub-regions of the nucleus accumbens are differentially affected by both stressors and methamphetamine. This study aimed to characterize and quantify methamphetamine-induced protein expression in the shell and core of the nucleus accumbens in animals exposed to maternal separation during early development. Isobaric tagging (iTRAQ) which enables simultaneous identification and quantification of peptides with tandem mass spectrometry (MS/MS) was used. We found that maternal separation altered more proteins involved in structure and redox regulation in the shell than in the core of the nucleus accumbens, and that maternal separation and methamphetamine had differential effects on signaling proteins in the shell and core. Compared to maternal separation or methamphetamine alone, the maternal separation/methamphetamine combination altered more proteins involved in energy metabolism, redox regulatory processes and neurotrophic proteins. Methamphetamine treatment of rats subjected to maternal separation caused a reduction of cytoskeletal proteins in the shell and altered cytoskeletal, signaling, energy metabolism and redox proteins in the core. Comparison of maternal separation/methamphetamine to methamphetamine alone resulted in decreased cytoskeletal proteins in both the shell and core and increased neurotrophic proteins in the core. This study confirms that both early life stress and methamphetamine differentially affect the shell and core of the nucleus accumbens and demonstrates that the combination of early life adversity and later methamphetamine use results in more proteins being affected in the nucleus accumbens than either treatment alone.

Neuroprotective and neurorestorative effects of thymosin β4 treatment initiated 6 hours after traumatic brain injury in rats

OBJECT

Thymosin β4 (Tβ4) is a regenerative multifunctional peptide. The aim of this study was to test the hypothesis that Tβ4 treatment initiated 6 hours postinjury reduces brain damage and improves functional recovery in rats subjected to traumatic brain injury (TBI).

METHODS

Traumatic brain injury was induced by controlled cortical impact over the left parietal cortex in young adult male Wistar rats. The rats were randomly divided into the following groups: 1) saline group (n = 7); 2) 6 mg/kg Tβ4 group (n = 8); and 3) 30 mg/kg Tβ4 group (n = 8). Thymosin β4 or saline was administered intraperitoneally starting at 6 hours postinjury and again at 24 and 48 hours. An additional group of 6 animals underwent surgery without TBI (sham-injury group). Sensorimotor function and spatial learning were assessed using the modified Neurological Severity Score and the Morris water maze test, respectively. Animals were euthanized 35 days after injury, and brain sections were processed to assess lesion volume, hippocampal cell loss, cell proliferation, and neurogenesis after Tβ4 treatment.

RESULTS

Compared with saline administration, Tβ4 treatment initiated 6 hours postinjury significantly improved sensorimotor functional recovery and spatial learning, reduced cortical lesion volume and hippocampal cell loss, and enhanced cell proliferation and neurogenesis in the injured hippocampus. The high dose of Tβ4 showed better beneficial effects compared with the low-dose treatment.

CONCLUSIONS

Thymosin β4 treatment initiated 6 hours postinjury provides both neuroprotection and neurorestoration after TBI, indicating that Tβ4 has promising therapeutic potential in patients with TBI. These data warrant further investigation of the optimal dose and therapeutic window of Tβ4 treatment for TBI and the associated underlying mechanisms.

Quantitative iTRAQ analysis of retinal ganglion cell degeneration after optic nerve crush

Retinal ganglion cells (RGCs) are central nervous system (CNS) neurons that transmit visual information from the retina to the brain. Apoptotic RGC degeneration causes visual impairment that can be modeled by optic nerve crush. Neuronal apoptosis is also a salient feature of CNS trauma, ischemia (stroke), and diseases of the CNS such as Alzheimer's, Parkinson's, multiple sclerosis, and amyotrophic lateral sclerosis. Optic nerve crush induces the apoptotic cell death of ∼ 70% of RGCs within the first 14 days after injury. This model is particularly attractive for studying adult neuron apoptosis because the time-course of RGC death is well established and axon regeneration within the myelinated optic nerve can be concurrently evaluated. Here, we performed a large scale iTRAQ proteomic study to identify and quantify proteins of the rat retina at 1, 3, 4, 7, 14, and 21 days after optic nerve crush. In total, 337 proteins were identified, and 110 were differentially regulated after injury. Of these, 58 proteins were upregulated (>1.3 ×), 46 were downregulated (<0.7 ×), and 6 showed both positive and negative regulation over 21 days, relative to normal retinas. Among the differentially expressed proteins, Thymosin-β4 showed an early upregulation at 3 days, the time-point that immediately precedes the induction of RGC apoptosis after injury. We examined the effect of exogenous Thymosin-β4 administration on RGC death after optic nerve injury. Intraocular injections of Thymosin-β4 significantly increased RGC survival by ∼ 3-fold compared to controls and enhanced axon regeneration after crush, demonstrating therapeutic potential for CNS insults. Overall, our study identified numerous proteins that are differentially regulated at key time-points after optic nerve crush, and how the temporal profiles of their expression parallel RGC death. This data will aid in the future development of novel therapeutics to promote neuronal survival and regeneration in the adult CNS.

Dose-dependent neurorestorative effects of delayed treatment of traumatic brain injury with recombinant human erythropoietin in rats

OBJECT

Delayed (24 hours postinjury) treatment with erythropoietin (EPO) improves functional recovery following experimental traumatic brain injury (TBI). In this study, the authors tested whether therapeutic effects of delayed EPO treatment for TBI are dose dependent in an attempt to establish an optimal dose paradigm for the delayed EPO treatment.

METHODS

Experimental TBI was performed in anesthetized young adult male Wistar rats using a controlled cortical impact device. Sham animals underwent the same surgical procedure without injury. The animals (8 rats/group) received 3 intraperitoneal injections of EPO (0, 1000, 3000, 5000, or 7000 U/kg body weight, at 24, 48, and 72 hours) after TBI. Sensorimotor and cognitive functions were assessed using a modified neurological severity score and foot fault test, and Morris water maze tests, respectively. Animals were killed 35 days after injury, and the brain sections were stained for immunohistochemical analyses.

RESULTS

Compared with the saline treatment, EPO treatment at doses from 1000 to 7000 U/kg did not alter lesion volume but significantly reduced hippocampal neuron loss, enhanced angiogenesis and neurogenesis in the injured cortex and hippocampus, and significantly improved sensorimotor function and spatial learning. The animals receiving the medium dose of 5000 U/kg exhibited a significant improvement in histological and functional outcomes compared with the lower or higher EPO dose groups.

CONCLUSIONS

These data demonstrate that delayed (24 hours postinjury) treatment with EPO provides dose-dependent neurorestoration, which may contribute to improved functional recovery after TBI, implying that application of an optimal dose of EPO is likely to increase successful preclinical and clinical trials for treatment of TBI.

Erythropoietin promotes neurovascular remodeling and long-term functional recovery in rats following traumatic brain injury

Erythropoietin (EPO) improves functional recovery after traumatic brain injury (TBI). This study was designed to investigate long-term (3 months) effects of EPO on brain remodeling and functional recovery in rats after TBI. Young male Wistar rats were subjected to unilateral controlled cortical impact injury. TBI rats were divided into the following groups: (1) saline group (n=7); (2) EPO-6h group (n=8); and (3) EPO-24h group (n=8). EPO (5000 U/kg in saline) was administered intraperitoneally at 6h, and 1 and 2 days (EPO-6h group) or at 1, 2, and 3 days (EPO-24h group) postinjury. Neurological function was assessed using a modified neurological severity score, footfault and Morris water maze tests. Animals were sacrificed at 3 months after injury and brain sections were stained for immunohistochemical analyses. Compared to the saline, EPO-6h treatment significantly reduced cortical lesion volume, while EPO-24h therapy did not affect the lesion volume (P<0.05). Both the EPO-6h and EPO-24h treatments significantly reduced hippocampal cell loss (P<0.05), promoted angiogenesis (P<0.05) and increased endogenous cellular proliferation (BrdU-positive cells) in the injury boundary zone and hippocampus (P<0.05) compared to saline controls. Significantly enhanced neurogenesis (BrdU/NeuN-positive cells) was seen in the dentate gyrus of both EPO groups compared to the saline group. Both EPO treatments significantly improved long-term sensorimotor and cognitive functional recovery after TBI. In conclusion, the beneficial effects of posttraumatic EPO treatment on injured brain persisted for at least 3 months. The long-term improvement in functional outcome may in part be related to the neurovascular remodeling induced by EPO.

Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications

Published studies have described a number of physiological properties and cellular functions of thymosin beta4 (Tbeta4), the major G-actin-sequestering molecule in mammalian cells. Those activities include the promotion of cell migration, blood vessel formation, cell survival, stem cell differentiation, the modulation of cytokines, chemokines, and specific proteases, the upregulation of matrix molecules and gene expression, and the downregulation of a major nuclear transcription factor. Such properties have provided the scientific rationale for a number of ongoing and planned dermal, corneal, cardiac clinical trials evaluating the tissue protective, regenerative and repair potential of Tbeta4, and direction for future clinical applications in the treatment of diseases of the central nervous system, lung inflammatory disease, and sepsis. A special emphasis is placed on the development of Tbeta4 in the treatment of patients with ST elevation myocardial infarction in combination with percutaneous coronary intervention.

Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide

Studies in various animal models of disease and repair with thymosin beta(4) (Tbeta(4)), the major actin-sequestering molecule in mammalian cells, have provided the scientific foundation for the ongoing dermal, corneal, and cardiac wound repair multicenter clinical trials. Tbeta(4) has of multiple biological activities, which include down-regulation of inflammatory chemokines and cytokines, and promotion of cell migration, blood vessel formation, cell survival, and stem cell maturation. All of these activities contribute to the multiple wound healing properties that have been observed in animal studies. This paper reviews and discusses the topical and systemic uses of Tbeta(4) in various animal models that demonstrate its potential for clinical use.

Treatment of traumatic brain injury with thymosin β₄ in rats

OBJECT

This study was designed to investigate the efficacy of delayed thymosin β(4) (Tβ(4)) treatment of traumatic brain injury (TBI) in rats.

METHODS

Young adult male Wistar rats were divided into the following groups: 1) sham group (6 rats); 2) TBI + saline group (9 rats); 3) and TBI + Tβ(4) group (10 rats). Traumatic brain injury was induced by controlled cortical impact over the left parietal cortex. Thymosin β(4) (6 mg/kg) or saline was administered intraperitoneally starting at Day 1 and then every 3 days for an additional 4 doses. Neurological function was assessed using a modified neurological severity score (mNSS), foot fault, and Morris water maze tests. Animals were killed 35 days after injury, and brain sections were stained for immunohistochemistry to assess angiogenesis, neurogenesis, and oligodendrogenesis after Tβ(4) treatment.

RESULTS

Compared with the saline treatment, delayed Tβ(4) treatment did not affect lesion volume but significantly reduced hippocampal cell loss, enhanced angiogenesis and neurogenesis in the injured cortex and hippocampus, increased oligodendrogenesis in the CA3 region, and significantly improved sensorimotor functional recovery and spatial learning.

CONCLUSIONS

These data for the first time demonstrate that delayed administration of Tβ(4) significantly improves histological and functional outcomes in rats with TBI, indicating that Tβ(4) has considerable therapeutic potential for patients with TBI.

Thymosin-beta4 attenuates ethanol-induced neurotoxicity in cultured cerebral cortical astrocytes by inhibiting apoptosis

Thymosin-beta4 (Tbeta4) is a major actin monomer-binding peptide in mammalian tissues and plays a crucial role in the nervous system in synaptogenesis, neuronal survival and migration, axonal growth, and plastic changes of dendritic spines. However, it is unknown whether Tbeta4 is also involved in challenges with external stress such as ethanol-induced neurotoxicity. In the present study, we investigated the effects of Tbeta4 on ethanol-induced neurotoxicity in cultured cerebral cortical astrocytes and the underlying mechanisms. Primarily cultured astrocytes were treated with 1 microg/ml Tbeta4 2 h prior to administration of 100 mM ethanol for 0.5, 1, 3 and 6 days, respectively. The results showed that ethanol caused neurotoxicity in cultured astrocytes, as shown by declined cell viability, distinct astroglial apoptosis and increased intracellular peroxidation. Tbeta4 markedly promoted cell viability, ameliorated the injury of intracellular glial fibrillary acidic protein-immunopositive cytoskeletal structures, reduced the percentage of apoptotic astrocyte and cellular DNA fragmentation, suppressed caspase-3 activity and upregulated Bcl-2 expression, inhibited the accumulation of reactive oxygen species and production of malondialdehyde in ethanol-treated astrocytes in a time-dependent manner. These data indicated that Tbeta4 attenuates ethanol-induced neurotoxicity in cultured cortical astrocytes through inhibition of apoptosis signaling, and one of the mechanisms underlying the capacity of Tbeta4 to suppress apoptosis may in part be due to its effect of anti-peroxidation.

Downregulation of thymosin beta4 in neural progenitor grafts promotes spinal cord regeneration

Thymosin beta4 (Tbeta4) is an actin-binding peptide whose expression in developing brain correlates with migration and neurite extension of neurons. Here, we studied the effects of the downregulation of Tbeta4 expression on growth and differentiation of murine neural progenitor cells (NPCs), using an antisense lentiviral vector. In differentiation-promoting medium, we found twice the number of neurons derived from the Tbeta4-antisense-transduced NPCs, which showed enhanced neurite outgrowth accompanied by increased expression of the adhesion complex N-cadherin-beta-catenin and increased ERK activation. Importantly, when the Tbeta4-antisense-transduced NPCs were transplanted in vivo into a mouse model of spinal cord injury, they promoted a significantly greater functional recovery. Locomotory recovery correlated with increased expression of the regeneration-promoting cell adhesion molecule L1 by the grafted Tbeta4-antisense-transduced NPCs. This resulted in an increased number of regenerating axons and in sprouting of serotonergic fibers surrounding and contacting the Tbeta4-antisense-transduced NPCs grafted into the lesion site. In conclusion, our data identify a new role for Tbeta4 in neuronal differentiation of NPCs by regulating fate determination and process outgrowth. Moreover, NPCs with reduced Tbeta4 levels generate an L1-enriched environment in the lesioned spinal cord that favors growth and sprouting of spared host axons and enhances the endogenous tissue-repair processes.

Thymosin beta 4 mRNA and peptide expression in phagocytic cells of different mouse tissues

Thymosin beta 4 (Tbeta4) is a peptide of 43 amino acids, mainly recognized as a regulator of actin polymerization by sequestering G-actin. Meanwhile, the peptide has been implicated in lymphocyte maturation, carcinogenesis, apoptosis, angiogenesis, blood coagulation and wound healing. The peptide is also involved in lesion-induced neuroplasticity through microglia upregulation and it participates in the growth of neuronal processes. However, its precise cellular localization throughout the entire body of the mouse has not been documented. We therefore initiated a detailed investigation of the tissue distribution and cellular expression of the Tbeta4 peptide and its precursor mRNA by immunocytochemistry and in situ hybridization, respectively. In the brain, Tbeta4 was clearly present in neurons of the olfactory bulb, neocortex, hippocampus, striatum, amygdala, piriform cortex and cerebellum, and in microglia across the entire brain. We further localized Tbeta4 in cells, typically with many processes, inside thymus, spleen, lung, kidney, liver, adrenal gland, stomach and intestine. Remarkably, Tbeta4 was thus associated with microglia and macrophages, the differentiated phagocytic cells residing in every tissue. Motility and phagocytosis, two important activities of macrophages, depend on actin, which can explain the presence of Tbeta4 in these cells.

Neurological functional recovery after thymosin beta4 treatment in mice with experimental auto encephalomyelitis

In the present study, we hypothesized that thymosin beta 4 (Tbeta4) is a potential therapy of multiple sclerosis (MS). To test this hypothesis, SJL/J mice (n=21) were subjected to experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE mice were treated with saline or Tbeta4 (6 mg/kg, n=10) every 3 days starting on the day of myelin proteolipid protein (PLP) immunization for total five doses. Neurological function, inflammatory infiltration, oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes were measured in the brain of EAE mice. Double immunohistochemical staining was used to detect proliferation and differentiation of OPCs. Tbeta4 was used to treat N20.1 cells (premature oligodendrocyte cell line) in vitro, and proliferation of N20.1 cells was measured by bromodeoxyuridine (BrdU) immunostaining. Tbeta4 treatment improved functional recovery after EAE. Inflammatory infiltrates were significantly reduced in the Tbeta4 treatment group compared to the saline groups (3.6+/-0.3/slide vs 5+/-0.5/slide, P<0.05). NG2(+) OPCs (447.7+/-41.9 vs 195.2+/-31/mm(2) in subventricular zone (SVZ), 75.1+/-4.7 vs 41.7+/-3.2/mm(2) in white matter), CNPase(+) mature oligodendrocytes (267.5+/-10.3 vs 141.4+/-22.9/mm(2)), BrdU(+) with NG2(+) OPCs (32.9+/-3.7 vs 17.9+/-3.6/mm(2)), BrdU(+) with CNPase(+) mature oligodendrocytes (18.2+/-1.7 vs 10.7+/-2.2/mm(2)) were significantly increased in the Tbeta4 treated mice compared to those of saline controls (P<0.05). These data indicate that Tbeta4 treatment improved functional recovery after EAE, possibly, via reducing inflammatory infiltrates, and stimulating oligodendrogenesis.