Thymosin β4 for the treatment of acute stroke in aged rats

Injectable hyaluronic acid hydrogel loaded with BMSC and NGF for traumatic brain injury treatment

Injectable hydrogel has the advantage to fill the defective area and thereby shows promise as therapeutic implant or cell/drug delivery vehicle for tissue repair. In this study, an injectable hyaluronic acid hydrogel in situ dual-enzymatically cross-linked by galactose oxidase (GalOx) and horseradish peroxidase (HRP) was synthesized and optimized, and the therapeutic effect of this hydrogel encapsulated with bone mesenchymal stem cells (BMSC) and nerve growth factors (NGF) for traumatic brain injury (TBI) mice was investigated. Results from in vitro experiments showed that either tyramine-modified hyaluronic acid hydrogels (HT) or NGF loaded HT hydrogels (HT/NGF) possessed good biocompatibility. More importantly, the HT hydrogels loaded with BMSC and NGF could facilitate the survival and proliferation of endogenous neural cells probably by neurotrophic factors release and neuroinflammation regulation, and consequently improved the neurological function recovery and accelerated the repair process in a C57BL/6 TBI mice model. All these findings highlight that this injectable, BMSC and NGF-laden HT hydrogel has enormous potential for TBI and other tissue repair therapy.

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.

Tβ4-Ac-SDKP pathway: Any relevance for the cardiovascular system?

The last 20 years witnessed the emergence of the thymosin β4 (Tβ4)-N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) pathway as a new source of future therapeutic tools to treat cardiovascular and renal diseases. In this review article, we attempted to shed light on the numerous experimental findings pertaining to the many promising cardiovascular therapeutic avenues for Tβ4 and (or) its N-terminal derivative, Ac-SDKP. Specifically, Ac-SDKP is endogenously produced from the 43-amino acid Tβ4 by 2 successive enzymes, meprin α and prolyl oligopeptidase. We also discussed the possible mechanisms involved in the Tβ4-Ac-SDKP-associated cardiovascular biological effects. In infarcted myocardium, Tβ4 and Ac-SDKP facilitate cardiac repair after infarction by promoting endothelial cell migration and myocyte survival. Additionally, Tβ4 and Ac-SDKP have antifibrotic and anti-inflammatory properties in the arteries, heart, lungs, and kidneys, and stimulate both in vitro and in vivo angiogenesis. The effects of Tβ4 can be mediated directly through a putative receptor (Ku80) or via its enzymatically released N-terminal derivative Ac-SDKP. Despite the localization and characterization of Ac-SDKP binding sites in myocardium, more studies are needed to fully identify and clone Ac-SDKP receptors. It remains promising that Ac-SDKP or its degradation-resistant analogs could serve as new therapeutic tools to treat cardiac, vascular, and renal injury and dysfunction to be used alone or in combination with the already established pharmacotherapy for cardiovascular diseases.

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.

A dual-enzymatically cross-linked injectable gelatin hydrogel loaded with BMSC improves neurological function recovery of traumatic brain injury in rats

BMSC-laden gelatin hydrogels dual-enzymatically cross-linked by GOX and HRP could significantly promote the neurological function recovery of TBI in rats.

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 participate in antibacterial immunity of kuruma shrimp, Marsupenaeus japonicus

Thymosins β are actin-binding proteins that play a variety of different functions in inflammatory responses, wound healing, cell migration, angiogenesis, and stem cell recruitment and differentiation. In crayfish, thymosins participate in antiviral immunology. However, the roles of thymosin during bacterial infection in shrimp remain unclear. In the present study, four thymosins were identified from kuruma shrimp, Marsupenaeus japonicus, and named as Mjthymosin2, Mjthymosin3, Mjthymosin4, and Mjthymosin5 according the number of their thymosin beta actin-binding motifs. Mjthymosin3 was selected for further study because its expression level was the highest in hemocytes. Expression analysis showed that Mjthymosin3 was upregulated in hemocytes after challenged by Vibrio anguillarum or Staphylococcus aureus. The recombinant Mjthymosin3 protein could inhibit the growth of certain bacteria in an in vitro antibacterial test. Mjthymosins could facilitate external bacterial clearance in shrimp, and were beneficial to shrimp survival post V. anguillarum or S. aureus infection. The results suggested that Mjthymosins played important roles in the antibacterial immune response of kuruma shrimp.

Inhibition of Connexin43 hemichannels with Gap19 protects cerebral ischemia/reperfusion injury via the JAK2/STAT3 pathway in mice

Functional disruption of the neurovascular unit may lead to aggravation of ischemic cerebral injury. Connexin43 (Cx43)-dependent gap junctional channels (GJCs) are critical in maintaining brain homeostasis. However, excessive opening of hemichannels (HCs) after cerebral ischemia may cause apoptosis and finally lead to amplification of ischemic injury. Previous studies indicated that Cx43 mimetic peptides Gap26 and Gap27 may protect cerebral ischemic injury, but the latest studies showed they also inhibit the opening of GJCs, which are beneficial for neuroprotection. Recent studies showed that Gap19 is a new specific inhibitor of Cx43 HCs. We investigated the role of Gap19 on cerebral ischemia/reperfusion (I/R) injury in a mouse model of middle cerebral artery occlusion (MCAO). Ventricle-injected Gap19 significantly alleviated infarct volume, neuronal cell damage and neurological deficits after ischemia, the neuroprotective effect of Gap19 was significant stronger than Gap26. Post-treatment with TAT-Gap19 still provided neuroprotection when it was administered intraperitoneally at 4 h after reperfusion. In addition, we found that Gap19 decreased the levels of cleaved caspase-3 and Bax and increased the level of Bcl-2, suggesting the anti-apoptotic activity of specifically blocking the Cx43 HCs. Furthermore, our data indicate that Gap19 treatment increased the levels of phosphorylated JAK2 and STAT3 both in vivo and in vitro. Gap19 inhibited hemichannel activity assessed by dye uptake in astrocytes. And we detected that pSTAT3 co-localized with Cx43 together in astrocytes after oxygen glucose deprivation (OGD) injury. Finally, AG490, a blocker of the JAK2/STAT3 pathway, could reverse the neuroprotective effects of Gap19 both in vivo and in vitro. Our experiment investigated the anti-apoptotic activity of Gap19, the specific inhibitor of Cx43 HCs, and the potential mechanisms. Our results demonstrated that Gap19 plays an anti-apoptotic role via activating the JAK2/STAT3 pathway after cerebral I/R injury, indicating that specific blocking of Cx43 HCs is a potential target for ischemic stroke.

A self-organized actomyosin drives multiple intercellular junction disruption and directly promotes neutrophil recruitment in lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI), with the hallmarks of vascular integrity disruption and neutrophil recruitment, is associated with high morbidity and mortality. Enhanced actomyosin assembly contributes to endothelial cell contact dysfunction. However, the roles and mechanisms of actomyosin assembly in ALI are not totally clear. We investigated the dynamic alterations and roles of actomyosin in ALI in vivo and in vitro models induced by LPS. Pulmonary levels of E-cadherin, vascular endothelial-cadherin, occludin, myosin phosphatase target subunit 1, and thymosin β4 were decreased, and the number and activity of neutrophils and the levels of actomyosin, p-ρ-associated protein kinase, p-myosin light-chain kinase, and profilin1 were increased within 3 d after LPS administration, and then, those alterations were recovered within the next 4 d, which was consistent with the alterations of lung histology, vascular permeability, edema, and serum levels of IL-6 and TNF-α. Direct or indirect inhibition of increased F-actin or myosin assembly ameliorated the reduction of intercellular junction molecules, the activation and migration of neutrophils, and the degree of lung injury. Moreover, neutrophil activation further promoted actomyosin assembly and aggravated lung injury. Conclusively, the enhancement of self-organized actomyosin contributes to alveolar-capillary barrier disruption and neutrophil recruitment in inflammatory response, which is a potential therapeutic target for ALI.-Chen, B., Yang, Z., Yang, C., Qin, W., Gu, J., Hu, C., Chen, A., Ning, J., Yi, B., Lu, K. A self-organized actomyosin drives multiple intercellular junction disruption and directly promotes neutrophil recruitment in lipopolysaccharide-induced acute lung injury.

Potential application of an injectable hydrogel scaffold loaded with mesenchymal stem cells for treating traumatic brain injury

In this contribution, we developed an injectable hydrogel composed of sodium alginate and hyaluronic acid that acts as a tissue scaffold to create a more optimal microenvironment for the stem cells for potential application of traumatic brain injury implantation.