Thymosin-β4 Attenuates Ethanol-induced Neurotoxicity in Cultured Cerebral Cortical Astrocytes by Inhibiting Apoptosis

Protection effect of thymosin β4 on ethanol injury in corneal stromal keratocyte

Purpose

To investigate the protective effects of thymosin β4 (Tβ4) on ethanol injured human corneal keratocytes (HCKs).

Methods

HCKs and BALB/c mice were chosen as the study subject. Ethanol was used to treat the cells and corneal stroma of mice to build the ethanol injured model in vitro and vivo respectively. CCK-8 was used to evaluate the cell metabolic activity. DCFH-DA was used to detect the intracellular reactive oxygen species level. TUNEL was chose to detect the cell apoptosis rate. The cell proliferation and migration were investigated by using wound healing insert. Wound healing of corneal surface and stroma was observed by using fluorescein sodium eyedrop and HE stain. RT-qPCR, ELISA, and immunostaining were performed to detect gene and protein expression in keratocytes or corneal stroma tissue of mice.

Results

Ethanol induced oxidative stress injury and cell apoptosis on HCKs, and Tβ4 can alleviate it by up-regulating the expression of Bcl-2, catalase, and CuZnSOD, and inhibiting the expression of Caspase-3. Tβ4 promotes the proliferation of HCKs and the process of corneal wound healing. It may relevant to the up-regulated expression of Ki67.

Conclusions

Our study established an ethanol-injured corneal stroma model in both vitro and vivo. The present study confirmed that Tβ4 play a protective effect on the reconstruction process of ethanol-injured corneal stroma.

Involvement of α7nAChR in the Protective Effects of Genistein Against β-Amyloid-Induced Oxidative Stress in Neurons via a PI3K/Akt/Nrf2 Pathway-Related Mechanism

Abnormal excessive production and deposition of β-amyloid (Aβ) peptides in selectively susceptible brain regions are thought to be a key pathogenic mechanism underlying Alzheimer's disease (AD), resulting in memory deficits and cognitive impairment. Genistein is a phytoestrogen with great promise for counteracting diverse Aβ-induced insults, including oxidative stress and mitochondrial dysfunction. However, the exact molecular mechanism or mechanisms underlying the neuroprotective effects of genistein against Aβ-induced insults are largely uncharacterized. To further elucidate the possible mechanism(s) underlying these protective effects, we investigated the neuroprotective effects of genistein against Aβ-induced oxidative stress mediated by orchestrating α7 nicotinic acetylcholine receptor (α7nAChR) signaling in rat primary hippocampal neurons. Genistein significantly increased cell viability, reduced the number of apoptotic cells, decreased accumulation of reactive oxygen species (ROS), decreased contents of malondialdehyde (MDA) and lactate dehydrogenase (LDH), upregulated BCL-2 expression, and suppressed Caspase-3 activity occurring after treatment with 25 μM Aβ25-35. Simultaneously, genistein markedly inhibited the decreases in α7nAChR mRNA and protein expression in cells treated with Aβ25-35. In addition, α7nAChR signaling was intimately involved in the genistein-mediated activation of phosphatidylinositol 3-kinase (PI3K)/Akt and Nrf2/keap1 signaling. Thus, α7nAChR activity together with the PI3K/Akt/Nrf2 signaling cascade likely orchestrates the molecular mechanism underlying the neuroprotective effects of genistein against Aβ-induced oxidative 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.

Thymosin beta 4 attenuates PrP(106-126)-induced human brain endothelial cells dysfunction

The blood-brain barrier (BBB) is a highly selective permeability barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system (CNS). The BBB is formed by cerebral endothelial cells connected by tight junctions. Prion diseases are neurodegenerative pathologies characterized by the accumulation of altered forms of the prion protein (PrP), named PrP^Sc. Thymosin beta 4 (Tβ₄) is an actin-sequestering peptide known to bind monomeric actin and inhibit its polymerization, and it is known to have a neuroprotective effect. However, the effect of Tβ₄ on prion disease has not yet been investigated. Therefore, in this study, we investigated the effect of Tβ₄ on prion-induced BBB dysfunction in hCMEC/D3 human cerebral endothelial cells. We found that Tβ₄ increased the expression of tight junction protein, but reduced the ratio of F-actin to G-actin. Moreover, we showed that Tβ₄ significantly improved PrP (106-126)-induced vascular permeability dysfunction in hCMEC/D3 cells. Through human BBB in vitro model, we found that PrP (106-126) could disrupt tight junctions and cytoskeleton arrangement. These results suggest that Tβ₄ may play a critical role in barrier stabilization. Furthermore, Tβ₄ may prevent neurodegenerative diseases caused by prion-induced BBB dysfunction.

Thymosin β4 in rheumatoid arthritis: Friend or foe

Rheumatoid arthritis (RA) has characteristic pannus tissues, which show tumor-like growth of the synovium through chronic joint inflammation. The synovium is highly penetrated by various immune cells, and the synovial lining becomes hyperplastic due to increased numbers of macrophage-like and fibroblast-like synoviocytes. Thus, a resultant hypoxic condition stimulates the expression of inflammation-related genes in various cells, in particular, vascular endothelial growth factor. Thymosin β4 (Tβ4), a 5-kDa protein, is known to play a significant role in various biological activities, such as actin sequestering, cell motility, migration, inflammation, and damage repair. Recent studies have provided evidence that Tβ4 may have a role in RA pathogenesis. The Tβ4 level has been shown to increase significantly in the joint fluid and serum of RA patients. However, whether Tβ4 stimulates or inhibits activation of RA immune responses remains to be determined. In the present study, we discuss the logical and clinical justifications for Tβ4 as a potential target for RA therapeutics.

Differential effects of lipid fractions from silver carp brain on human cervical carcinoma cells in vitro

Previous research has revealed that n3 polyunsaturated fatty acids (PUFAs) exhibit anticancer activities. Lipids from a fish brain contain substantial n3 PUFAs. However, no research has been conducted on the action and mechanism of their potent anticancer activities. In this study, total lipids (TLs) from silver carp brain were isolated into polar lipids (PLs) and neutral lipids (NLs), and the anticancer potential of the lipid fractions (LFs) was investigated using the human cervical carcinoma HeLa cell line. LFs effectively inhibited the cell proliferation of HeLa cells in a time- and dose-dependent manner by cell cycle arrest at the S stage and by inducing apoptosis. Further analyses indicated that the loss of mitochondrial membrane potential could be one of mechanisms of apoptosis induced by LFs. Among the TLs, PLs have proven to be more effective in inducing cervical carcinoma cell death than NLs. This work will play a role in promoting lipids from silver carp brain as a potential preventive and therapeutic agent against human cervical carcinoma.

The proform of glia cell line-derived neurotrophic factor: a potentially biologically active protein

Growing evidences have revealed that the proforms of several neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT3), by binding to p75 neurotrophin receptor and sortilin, could induce neuronal apoptosis and are implicated in the pathogenesis of various neurodegenerative diseases. The glial cell line-derived neurotrophic factor (GDNF), one of the most potent useful neurotrophic factors for the treatment of Parkinson's disease (PD), is firstly synthesized as the proform (proGDNF) like other neurotrophin NGF, BDNF, and NT3. However, little is known about proGDNF expression and secretion under physiological as well as pathological states in vivo or in vitro. In this study, we investigated the expression profile and dynamic changes of proGDNF in brains of aging and PD animal models, with the interesting finding that proGDNF was a predominant form of GDNF with molecular weight of about 36 kDa by reducing and nonreducing immunoblots in adult brains and was unregulated in the aging, lipopolysaccharide (LPS), and 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine (MPTP) insult. We further provided direct evidence that accompanied activation of primary astrocytes as well as C6 cell line induced by LPS stimulation, proGDNF was increasingly synthesized and released as the uncleaved form in cell culture. Taken together, our results strongly suggest that proGDNF may be a biologically active protein and has specific effects on the cells close to its secreting site, and a potentially important role of proGDNF signaling in the brains, in the glia-neuronal interaction or in the pathogenesis of PD, should merit further investigation.

Involvement of α7 nAChR signaling cascade in epigallocatechin gallate suppression of β-amyloid-induced apoptotic cortical neuronal insults

Excessive generation and accumulation of the β-amyloid (Aβ) peptide in selectively vulnerable brain regions is a key pathogenic event in the Alzheimer's disease (AD), while epigallocatechin gallate (EGCG) is a very promising chemical to suppress a variety of Aβ-induced neurodegenerative disorders. However, the precise molecular mechanism of EGCG responsible for protection against neurotoxicity still remains elusive. To validate and further investigate the possible mechanism involved, we explored whether EGCG neuroprotection against neurotoxicity of Aβ is mediated through the α7 nicotinic acetylcholine receptor (α7 nAChR) signaling cascade. It was shown in rat primary cortical neurons that short-term treatment with EGCG significantly attenuated the neurotoxicity of Aβ1-42, as demonstrated by increased cell viability, reduced number of apoptotic cells, decreased reactive oxygen species (ROS) generation, and downregulated caspase-3 levels after treatment with 25-μM Aβ1-42. In addition, EGCG markedly strengthened activation of α7nAChR as well as its downstream pathway signaling molecules phosphatidylinositol 3-kinase (PI3K) and Akt, subsequently leading to suppression of Bcl-2 downregulation in Aβ-treated neurons. Conversely, administration of α7nAChR antagonist methyllycaconitine (MLA; 20 μM) to neuronal cultures significantly attenuated the neuroprotection of EGCG against Aβ-induced neurototoxicity, thus presenting new evidence that the α7nAChR activity together with PI3K/Akt transduction signaling may contribute to the molecular mechanism underlying the neuroprotective effects of EGCG against Aβ-induced cell death.

Comparative peptidomics analysis of neural adaptations in rats repeatedly exposed to amphetamine

Repeated exposure to amphetamine (AMPH) induces long-lasting behavioral changes, referred to as sensitization, that are accompanied by various neuroadaptations in the brain. To investigate the chemical changes that occur during behavioral sensitization, we applied a comparative proteomics approach to screen for neuropeptide changes in a rodent model of AMPH-induced sensitization. By measuring peptide profiles with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and comparing signal intensities using principal component analysis and variance statistics, subsets of peptides are found with significant differences in the dorsal striatum, nucleus accumbens, and medial prefrontal cortex of AMPH-sensitized male Sprague-Dawley rats. These biomarker peptides, identified in follow-up analyses using liquid chromatography and tandem mass spectrometry, suggest that behavioral sensitization to AMPH is associated with complex chemical adaptations that regulate energy/metabolism, neurotransmission, apoptosis, neuroprotection, and neuritogenesis, as well as cytoskeleton integrity and neuronal morphology. Our data contribute to a growing number of reports showing that in addition to the mesolimbic dopamine system, which is the best known signaling pathway involved with reinforcing the effect of psychostimulants, concomitant chemical changes in other pathways and in neuronal organization may play a part in the overall effect of chronic AMPH exposure on behavior.

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.