TB-500 Fragment

Thymosin beta 4 as an Alzheimer disease intervention target identified using human brain organoids.

The developmental origin of Alzheimer disease (AD) has been proposed but is arguably debated. Here, we developed cerebral organoids from induced pluripotent stem cells (iPSCs) with mutations in amyloid precursor protein (APP) associated with familial AD (fAD) and analyzed the dynamic changes of cellular states. We found that mature neurons induced in fAD organoids markedly decreased compared to that of health control, accompanied with increased cell senescence and β-amyloid (Aβ) production. Interestingly, the expression level of the gene TMSB4X that encodes thymosin beta 4 (Tβ4) significantly decreased both in fAD organoids' neurons and AD patients' excitatory neurons. Remarkably, the neurodevelopmental deficits and Aβ formation in fAD organoids were rescued by treatment with Tβ4. The beneficial effects of Tβ4 were also revealed in 5xfAD model mice. Thus, this study has identified Tβ4 as a neuroprotective factor that may mitigate altered neurogenesis and AD pathology, highlighting a potential for disease intervention.

The beta-thymosin enigma.

Actin dynamics in nonmuscle cells is controlled by the availability of actin nucleating sites and actin monomers. Thymosin beta-4 (Tbeta-4) has been implicated in modulating the availability of actin monomers in a large variety of cells. It together with actin nucleating, severing, and uncapping proteins, harnesses the intrinsic dynamic properties of actin to regulate the actin polymerization response in cells. Overexpression or addition of exogenous Tbeta-4 or its homolog, Tbeta-10, alters the actin cytoskeleton, and has multiple effects on cellular functions related to motility. Some of these effects are consistent with beta-thymosins functioning exclusively as monomer-binding proteins, while others are not. Therefore, the complex pleiotropic effects of beta-thymosin in cells may be due to direct and indirect effects on the actin cytoskeleton, as well as modulation of signaling pathways that will impact the cytoskeleton and a variety of cell functions.

Identification of glutamine as a potential therapeutic target in dry eye disease.

Dry eye disease (DED) is a prevalent inflammatory condition significantly impacting quality of life, yet lacks effective pharmacological therapies. Herein, we proposed a novel approach to modulate the inflammation through metabolic remodeling, thus promoting dry eye recovery. Our study demonstrated that co-treatment with mesenchymal stem cells (MSCs) and thymosin beta-4 (Tβ4) yielded the best therapeutic outcome against dry eye, surpassing monotherapy outcomes. In situ metabolomics through matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) revealed increased glutamine levels in cornea following MSC + Tβ4 combined therapy. Inhibition of glutamine reversed the anti-inflammatory, anti-apoptotic, and homeostasis-preserving effects observed with combined therapy, highlighting the critical role of glutamine in dry eye therapy. Clinical cases and rodent model showed elevated expression of glutaminase (GLS1), an upstream enzyme in glutamine metabolism, following dry eye injury. Mechanistic studies indicated that overexpression and inhibition of GLS1 counteracted and enhanced, respectively, the anti-inflammatory effects of combined therapy, underscoring GLS1's pivotal role in regulating glutamine metabolism. Furthermore, single-cell sequencing revealed a distinct subset of pro-inflammatory and pro-fibrotic corneal epithelial cells in the dry eye model, while glutamine treatment downregulated those subclusters, thereby reducing their inflammatory cytokine secretion. In summary, glutamine effectively ameliorated inflammation and the occurrence of apoptosis by downregulating the pro-inflammatory and pro-fibrotic corneal epithelial cells subclusters and the related IκBα/NF-κB signaling. The present study suggests that glutamine metabolism plays a critical, previously unrecognized role in DED and proposes an attractive strategy to enhance glutamine metabolism by inhibiting the enzyme GLS1 and thus alleviating inflammation-driven DED progression.

Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.

Peptides are short chains of amino acids with a unique pharmacological niche between small-molecule drugs and large proteins. Their use in sports medicine is rapidly expanding, driven by patient demand for accelerated injury recovery and performance enhancement. While numerous peptide drugs have undergone a rigorous approval process that evaluates both safety and efficacy, a parallel "gray market" of unapproved compounds has emerged, operating largely outside of regulatory oversight. Our objective is to present the pharmacological mechanisms, safety profiles, and regulatory status of prominent approved and unapproved peptides marketed direct to patients, including AOD-9604 (anti-obesity drug 9604), BPC-157 (body protection compound 157), CJC-1295, FS-344 (follistatin-344), GHK-Cu (glycyl-L-histidyl-L-lysine copper), ipamorelin, MOTS-C (mitochondrial ORF of the 12S rRNA type-c), sermorelin, SS-31 (elamipretide), tesamorelin (Egrifta), Tβ4 (thymosin beta-4), and TB-500 (thymosin beta-4 fragment). Many unapproved peptides demonstrate favorable tissue repair and metabolic outcomes in animal models, but rigorous human safety data are scarce, and there is potential for serious harm to patients. This narrative review focuses on the utilization of peptides in sports medicine, and alternative treatments that may be considered. We provide a framework to navigate patient discussions about peptides to better facilitate evidence-based practices for musculoskeletal healing and athletic performance. We also discuss the placebo effect as a mediator of peptide efficacy, and how social media amplifies this effect.

The platelet cytoskeleton.

The platelet cytoskeleton contains two actin filament-based components. One is the cytoplasmic actin filaments which fill the cytoplasm and mediate contractile events. The other is the membrane skeleton, which coats the plasma membrane and regulates properties of the membrane such as its contours and stability. In the unstimulated platelet, only 30-40% of the actin is polymerized into filaments; the rest is thought to be prevented from polymerizing by the association of thymosin beta 4 with monomeric actin and by the association of gelsolin with the barbed ends of pre-existing actin filaments. When platelets are activated, there is a rapid increase in actin polymerization; new filaments fill the extending filopodia and form a network at the periphery of the platelet. As a result of activation, myosin binds to cytoplasmic actin filaments, causing them to move towards the center of the platelet. As platelets aggregate, additional cytoskeletal reorganizations occur: GP IIb-IIIa associates with adhesive ligand in a platelet aggregate; this results in the association of GP IIb-IIIa, membrane skeleton proteins, and signaling molecules with cytoplasmic actin. Future studies should help to elucidate the significance of the cytoskeleton in regulating signal transduction events in platelets.

Cardioprotection by Thymosin Beta 4.

Treatment with thymosin beta 4 (Tβ4) reduces infarct volume and preserves cardiac function in preclinical models of cardiac ischemic injury. These effects stem in part from decreased infarct size, but additional benefits are likely due to specific antifibrotic and proangiogenic activities. Injected or transgenic Tβ4 increase blood vessel growth in large and small animal models, consistent with Tβ4 converting hibernating myocardium to an actively contractile state following ischemia. Tβ4 and its degradation products have antifibrotic effects in in vitro assays and in animal models of fibrosis not related to cardiac injury. This large number of pleiotropic effects results from Tβ4's many interactions with cellular signaling pathways, particularly indirect regulation of cellular motility and movement via the SRF-MRTF-G-actin transcriptional pathway. Variation in effects and effect sizes in animal models may potentially be due to variable distribution of Tβ4. Preclinical studies of PK/PD relationships and a reliable pharmacodynamic biomarker would facilitate clinical development of Tβ4.

Thymosin beta 4 interactions.

Thymosin beta 4 is a small, 5-kDa protein with a diverse range of activities, including its function as an actin monomer sequestering protein, an antiinflammatory agent, and an inhibitor of bone marrow stem cell proliferation. Only the effects of thymosin beta 4 on the actin cytoskeleton have an explanation based on identified molecular interactions. Thymosin beta 4 is largely unfolded or perhaps completely unfolded in solution. Based on the paradigm introduced by Wright and Dyson (1999) that unfolded proteins may have multiple functions based on their ability to recognize numerous ligands, the flexible structure of thymosin beta 4 may facilitate the recognition of a variety of molecular targets, thus explaining the plethora of functions attributed to thymosin beta 4. Furthermore, if multiple ligands bind to thymosin beta 4, then it is possible that thymosin beta 4 has a unique integrative function that links the actin cytoskeleton to important immune and cell growth-signaling cascades.

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 beta 4.

Thymosin beta 4 regulation of actin in sepsis.

Sepsis is the dysregulated host response to an infection resulting in life-threatening organ damage. Thymosin Beta 4 is an actin binding protein that inhibits the polymerization of G-actin into F-actin and improves mortality when administered intravenously to septic rats. Thymosin Beta 4 decreases inflammatory mediators, lowers reactive oxygen species, up-regulates anti-oxidative enzymes, anti-inflammatory genes, and anti-apoptotic enzymes making it an interesting protein to study in sepsis. The authors summarize the current knowledge of actin and Thymosin Beta 4 as it relates to sepsis via a comprehensive literature search. Sepsis results in measurable levels of F-actin in the circulation as well as a decreased concentration of Thymosin Beta 4. It is speculated that F-actinemia contributes to microcirculatory perturbations present in patients with sepsis by disturbing laminar flow. Given that Thymosin Beta 4 inhibits the polymerization of F-actin, it is possible that Thymosin Beta 4 decreases mortality in sepsis via the regulation of actin as well as its other anti-inflammatory properties and should be further pursued as a clinical trial in humans with sepsis.

The subcommissural organ regulates brain development via secreted peptides.

The subcommissural organ (SCO) is a gland located at the entrance of the aqueduct of Sylvius in the brain. It exists in species as distantly related as amphioxus and humans, but its function is largely unknown. Here, to explore its function, we compared transcriptomes of SCO and non-SCO brain regions and found three genes, Sspo, Car3 and Spdef, that are highly expressed in the SCO. Mouse strains expressing Cre recombinase from endogenous promoter/enhancer elements of these genes were used to genetically ablate SCO cells during embryonic development, resulting in severe hydrocephalus and defects in neuronal migration and development of neuronal axons and dendrites. Unbiased peptidomic analysis revealed enrichment of three SCO-derived peptides, namely, thymosin beta 4, thymosin beta 10 and NP24, and their reintroduction into SCO-ablated brain ventricles substantially rescued developmental defects. Together, these data identify a critical role for the SCO in brain development.

Thymosin β4 and β10 Expression in Human Organs during Development: A Review.

This review summarizes the results of a series of studies performed by our group with the aim to define the expression levels of thymosin β4 and thymosin β10 over time, starting from fetal development to different ages after birth, in different human organs and tissues. The first section describes the proteomics investigations performed on whole saliva from preterm newborns and gingival crevicular fluid, which revealed to us the importance of these acidic peptides and their multiple functions. These findings inspired us to start an in-depth investigation mainly based on immunochemistry to establish the distribution of thymosin β4 and thymosin β10 in different organs from adults and fetuses at different ages (after autopsy), and therefore to obtain suggestions on the functions of β-thymosins in health and disease. The functions of β-thymosins emerging from these studies, for instance, those performed during carcinogenesis, add significant details that could help to resolve the nowadays so-called "β-thymosin enigma", i.e., the potential molecular role played by these two pleiotropic peptides during human development.

Deficiency of endothelial sirtuin1 in mice stimulates skeletal muscle insulin sensitivity by modifying the secretome.

Downregulation of endothelial Sirtuin1 (Sirt1) in insulin resistant states contributes to vascular dysfunction. Furthermore, Sirt1 deficiency in skeletal myocytes promotes insulin resistance. Here, we show that deletion of endothelial Sirt1, while impairing endothelial function, paradoxically improves skeletal muscle insulin sensitivity. Compared to wild-type mice, male mice lacking endothelial Sirt1 (E-Sirt1-KO) preferentially utilize glucose over fat, and have higher insulin sensitivity, glucose uptake, and Akt signaling in fast-twitch skeletal muscle. Enhanced insulin sensitivity of E-Sirt1-KO mice is transferrable to wild-type mice via the systemic circulation. Endothelial Sirt1 deficiency, by inhibiting autophagy and activating nuclear factor-kappa B signaling, augments expression and secretion of thymosin beta-4 (Tβ4) that promotes insulin signaling in skeletal myotubes. Thus, unlike in skeletal myocytes, Sirt1 deficiency in the endothelium promotes glucose homeostasis by stimulating skeletal muscle insulin sensitivity through a blood-borne mechanism, and augmented secretion of Tβ4 by Sirt1-deficient endothelial cells boosts insulin signaling in skeletal muscle cells.

Potential role of thymosin Beta 4 in liver fibrosis.

Liver fibrosis, the main characteristic of chronic liver diseases, is strongly associated with the activation of hepatic stellate cells (HSCs), which are responsible for extracellular matrix production. As such, investigating the effective regulators controlling HSC activation provides important clues for developing therapeutics to inhibit liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is known to be involved in various cellular responses. A growing body of evidence suggests that Tβ4 has a potential role in the pathogenesis of liver fibrosis and that it is especially associated with the activation of HSCs. However, it remains unclear whether Tβ4 promotes or suppresses the activation of HSCs. Herein, we review the potential role of Tβ4 in liver fibrosis by describing the effects of exogenous and endogenous Tβ4, and we discuss the possible signaling pathway regulated by Tβ4. Exogenous Tβ4 reduces liver fibrosis by inhibiting the proliferation and migration of HSCs. Tβ4 is expressed endogenously in the activated HSCs, but this endogenous Tβ4 displays opposite effects in HSC activation, either as an activator or an inhibitor. Although the role of Tβ4 has not been established, it is apparent that Tβ4 influences HSC activation, suggesting that Tβ4 is a potential therapeutic target for treating liver diseases.

Thymosin beta 4-like peptides.

Thymosin beta 4 and the eye: the journey from bench to bedside.

Thymosin beta 4 (Tβ4) has important applications in ocular repair and Phase 3 clinical trials using Tβ4 to treat dry eye and neurotrophic keratopathy are currently ongoing. These exciting clinical possibilities for Tβ4 in the eye are the result of seminal basic scientific discoveries and contributions from so many talented investigators. Areas covered: My personal Tβ4 journey began at the NIH in 1998 and propelled my career as a clinician scientist. As a tribute to the amazing individuals who have guided and supported me along with my brilliant colleagues and students who have contributed and collaborated with me over the years, this review will tell the cumulative story of how Tβ4 became a major potential new therapy for corneal wound healing disorders. The journey has been marked by the thrilling exhilaration from fundamental breakthroughs in the laboratory and clinic, combined with the challenging and often harsh realities of submitting grants and obtaining funding. Expert opinion: The electrifying possibility of Tβ4 as a revolutionary novel dry eye therapy is something that could have only been dreamed about just a few years ago. We believe that Tβ4 eyedrops will help many patients suffering from several ocular surface related disorders.

Thymosin beta-4 denotes new directions towards developing prosperous anti-aging regenerative therapies.

Our dream of defeating the processes of organ damage and aging remains a challenge scientists pursued for hundreds of years. Although the goal is to successfully treat the body as a whole, steps towards regenerating individual organs are even considered significant. Since initial approaches utilizing only progenitor cells appear limited, we propose interconnecting our collective knowledge regarding aging and embryonic development may lead to the discovery of molecules which provide alternatives to effectively reverse cellular damage. In this review, we introduce and summarize our results regarding Thymosin beta-4 (TB4) to support our hypothesis using the heart as model system. Accordingly, we investigated the developmental expression of TB4 in mouse embryos and determined the impact of the molecule in adult animals by systemically injecting the peptide following acute cardiac infarction or with no injury. Our results proved, TB4 is expressed in the developing heart and promotes cardiac cell migration and survival. In adults, the peptide enhances myocyte survival and improves cardiac function after coronary artery ligation. Moreover, intravenous injections of TB4 alter the morphology of the adult epicardium, and the changes resemble the characteristics of the embryo. Reactivation of the embryonic program became equally reflected by the increased number of cardiac vessels and by the alteration of the gene expression profile typical of the embryonic state. Moreover, we discovered TB4 is capable of epicardial progenitor activation, and revealed the effect is independent of hypoxic injury. By observing the above results, we believe, further discoveries and consequential postnatal administration of developmentally relevant candidate molecules such as TB4 may likely result in reversing aging processes and accelerate organ regeneration in the human body.

Thymosin Beta-4 Is Elevated in Women With Heart Failure With Preserved Ejection Fraction.

Thymosin beta-4 (TB4) is an X-linked gene product with cardioprotective properties. Little is known about plasma concentration of TB4 in heart failure (HF), and its relationship with other cardiovascular biomarkers. We sought to evaluate circulating TB4 in HF patients with preserved (HFpEF) or reduced (HFrEF) ejection fraction compared to non-HF controls. TB4 was measured using a liquid chromatography and mass spectrometry assay in age- and sex-matched HFpEF (n=219), HFrEF (n=219) patients, and controls (n=219) from a prospective nationwide study. Additionally, a 92-marker multiplex proximity extension assay was measured to identify biomarker covariates. Compared with controls, plasma TB4 was elevated in HFpEF (985 [421-1723] ng/mL versus 1401 [720-2379] ng/mL, P<0.001), but not in HFrEF (1106 [556-1955] ng/mL, P=0.642). Stratifying by sex, only women (1623 [1040-2625] ng/mL versus 942 [386-1891] ng/mL, P<0.001), but not men (1238.5 [586-1967] ng/mL versus 1004 [451-1538] ng/mL, P=1.0), had significantly elevated TB4 in the setting of HFpEF. Adjusted for New York Heart Association class, N-terminal pro B-type natriuretic peptide, age, and myocardial infarction, hazard ratio to all-cause mortality is significantly higher in women with elevated TB4 (1.668, P=0.036), but not in men (0.791, P=0.456) with HF. TB4 is strongly correlated with a cluster of 7 markers from the proximity extension assay panel, which are either X-linked, regulated by sex hormones, or involved with NF-&#x3ba;B signaling. We show that plasma TB4 is elevated in women with HFpEF and has prognostic information. Because TB4 can preserve EF in animal studies of cardiac injury, the relation of endogenous, circulating TB4 to X chromosome biology and differential outcomes in female heart disease warrants further study.

Thymosin Beta-4 Modulates Cardiac Remodeling by Regulating ROCK1 Expression in Adult Mammals.

Although a myocardial infarction occurs roughly every minute in the U.S. alone, medical research has yet to unlock the key to fully enabling post-hypoxic myocardial regeneration. Thymosin beta-4 (TB4), a short, secreted peptide, was shown to possess a beneficial impact regarding myocardial cell survival, coronary re-growth and progenitor cell activation following myocardial infarction in adult mammals. It equally reduces scarring, however, the precise mechanisms through which the peptide assists this phenomenon have not been properly elucidated. Accordingly, the primary aim of our study was to identify novel molecular contributors responsible for the positive impact of TB4 during the remodeling processes of the infarcted heart. We performed miRNA profiling on adult mice hearts following permanent coronary ligation with or without systemic TB4 injection and searched for targets and novel mechanisms through which TB4 may mitigate pathological scarring in the heart. Our results revealed a significant increase in miR139-5p expression and identified ROCK1 as a potential target protein aligned. Real-time PCR, Western blot and immunostaining on adult mouse hearts and human cardiac cells revealed the peptide indirectly or directly modulates ROCK1 protein levels both in vivo and in vitro. We equally discovered TB4 may reverse or inhibit fibroblast/myofibroblast transformation and the potential downstream mechanisms by which TB4 alters cellular responses through ROCK1 are cell type specific. Given the beneficial effects of ROCK1 inhibition in various cardiac pathologies, we propose a potential utilization for TB4 as a ROCK1 inhibitor in the future.

Thymosin Beta 4 Is a Potential Regulator of Hepatic Stellate Cells.

Liver fibrosis, a major characteristic of chronic liver disease, is inappropriate tissue remodeling caused by prolonged parenchymal cell injury and inflammation. During liver injury, hepatic stellate cells (HSCs) undergo transdifferentiation from quiescent HSCs into activated HSCs, which promote the deposition of extracellular matrix proteins, leading to liver fibrosis. Thymosin beta 4 (T&#x3b2;4), a major actin-sequestering protein, is the most abundant member of the highly conserved &#x3b2;-thymosin family and controls cell morphogenesis and motility by regulating the dynamics of the actin cytoskeleton. T&#x3b2;4 is known to be involved in various cellular responses, including antiinflammation, wound healing, angiogenesis, and cancer progression. Emerging evidence suggests that T&#x3b2;4 is expressed in the liver; however, its biological roles are poorly understood. Herein, we introduce liver fibrogenesis and recent findings regarding the function of T&#x3b2;4 in various tissues and discuss the potential role of T&#x3b2;4 in liver fibrosis with a special focus on the effects of exogenous and endogenous T&#x3b2;4. Recent studies have revealed that activated HSCs express T&#x3b2;4 in vivo and in vitro. Treatment with the exogenous T&#x3b2;4 peptide inhibits the proliferation and migration of activated HSCs and reduces liver fibrosis, indicating it has an antifibrotic action. Meanwhile, the endogenously expressed T&#x3b2;4 in activated HSCs is shown to promote HSCs activation. Although the role of T&#x3b2;4 has not been elucidated, it is apparent that T&#x3b2;4 is associated with HSC activation. Therefore, understanding the potential roles and regulatory mechanisms of T&#x3b2;4 in liver fibrosis may provide a novel treatment for patients.

Small actin-binding proteins: the beta-thymosin family.

Thymosin beta 4 is a major actin monomer binding protein present at high concentration in many vertebrate cells and cell lines. The interactions of actin with thymosin beta 4, actobindin and profilin are compared. Nine beta-thymosins have been identified; six have been shown to bind to actin. Regulation of the synthesis of thymosin beta 10 and thymosin beta 4 has been found in brain development and after stimulation of several cell types, respectively. The extracellular effects of thymosin beta 4 still need clarification.

Thymosin beta4 and its posttranslational modifications.

Thymosin beta(4) as well as the other members of the beta-thymosin family are important G-actin sequestering peptides. The chemical properties, the biosynthesis, and posttranslational modifications (PTMs) of these peptides are discussed. During biosynthesis of thymosin beta(4) the initiator methionine is removed and the N-terminus is acetylated. Research on proteomics revealed several acetylated lysine residues and two phosphorylated threonine residues. The enormous number of phosphorylable and acetylable sites in the human proteome raises the question about the biological significance of these PTMs in the context of beta-thymosins. Presently, this question cannot be answered because neither the concentration of these modified beta-thymosins in cells is known nor the consequences of the modifications on the biological function(s) of beta-thymosins have been studied yet. Thymosin beta(4) is also posttranslationally modified by transglutaminase forming covalent bonds with other molecules. Prolyl oligopeptidase generates ac-SDKP from thymosin beta(4). The concentration of C-terminal peptide fragments of thymosin beta(4) is elevated in the blood of patients with rheumatoid arthritis.

Sources of variability in quantifying circulating thymosin beta-4: literature review and recommendations.

Thymosin beta-4 (TB4) is an endogenous peptide with protective and regenerative effects in models of cellular and organ injury. TB4 is increasingly measured as a potential plasma or serum biomarker in human cardiovascular, liver, infectious, and autoimmune disease. The focus of this review is the quantification of TB4 in clinical cohort studies and whether reported TB4 concentrations differ with respect to method of sample preparation. We survey current literature for studies measuring TB4 in human serum or plasma and compare reported concentrations in healthy controls. We find substantial intra- and inter- study variability in healthy controls, and a lack of protocol standardization. We further highlight three factors that may confound TB4 clinical measurements and should be considered in future study design: 1) residual platelets remaining in suspension after centrifugation, 2) TB4 release following ex vivo platelet activation, and 3) specificity of assays towards posttranslational modifications. Accordingly, we put forth our recommendations to minimize residual and activated platelets during sample collection, and to cross-validate TB4 measurements using both antibody-based and mass spectrometry-based methods.

Thymosin Beta-4 Induces Mouse Hair Growth.

Thymosin beta-4 (T&#x3b2;4) is known to induce hair growth and hair follicle (HF) development; however, its mechanism of action is unknown. We generated mice that overexpressed T&#x3b2;4 in the epidermis, as well as T&#x3b2;4 global knockout mice, to study the role of T&#x3b2;4 in HF development and explore the mechanism of T&#x3b2;4 on hair growth. To study T&#x3b2;4 function, we depilated control and experimental mice and made tissue sections stained with hematoxylin and eosin (H&E). To explore the effect of T&#x3b2;4 on hair growth and HF development, the mRNA and protein levels of T&#x3b2;4 and VEGF were detected by real-time PCR and western blotting in control and experimental mice. Protein expression levels and the phosphorylation of P38, ERK and AKT were also examined by western blotting. The results of depilation indicated that hair re-growth was faster in T&#x3b2;4-overexpressing mice, but slower in knockout mice. Histological examination revealed that T&#x3b2;4-overexpressing mice had a higher number of hair shafts and HFs clustered together to form groups, while the HFs of control mice and knockout mice were separate. Hair shafts in knockout mice were significantly reduced in number compared with control mice. Increased T&#x3b2;4 expression at the mRNA and protein levels was confirmed in T&#x3b2;4-overexpressing mice, which also had increased VEGF expression. On the other hand, knockout mice had reduced levels of VEGF expression. Mechanistically, T&#x3b2;4-overexpressing mice showed increased protein expression levels and phosphorylation of P38, ERK and AKT, whereas knockout mice had decreased levels of both expression and phosphorylation of these proteins. T&#x3b2;4 appears to regulate P38/ERK/AKT signaling via its effect on VEGF expression, with a resultant effect on the speed of hair growth, the pattern of HFs and the number of hair shafts.

Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion.

Despite advancements in primary percutaneous coronary intervention (PCI), cardiac dysfunction remains a challenge in patients with ST-segment elevation myocardial infarction (STEMI). Although thymosin beta 4 has shown cardioprotective effects in preclinical MI models, its impact on chronic cardiac functional recovery post ischemia/reperfusion (I/R), especially in STEMI, warrants further investigation. This study aims to explore the therapeutic potential of recombinant human thymosin beta 4 (rhTB4) in both murine models subjected to I/R and in subjects with STEMI post-PCI. In C57BL/6J mice, 7-day rhTB4 treatment prevented cardiac dysfunction and fibrosis 28 days post-I/R surgery and significantly reduced plasma NT-proBNP levels at both 1 day and 28 days post-I/R. Similarly, in a permanent ligation model, rhTB4 improved cardiac function and reduced infarct size at 8 weeks post-MI. RNA-seq analysis of I/R heart tissues revealed that rhTB4 modulated the ErbB signaling pathway. In vitro hypoxia/reoxygenation (H/R) models (HL-1, neonatal mouse cardiomyocytes, H9C2) demonstrated that rhTB4 activated the ErbB2/Raf1 signaling pathway, attenuated cardiomyocyte apoptosis and suppressed pro-apoptotic protein Bad expression. The cardioprotective effects of rhTB4 on cardiac function and adverse cardiac remodeling in I/R mice were abolished by ErbB2 inhibition. In a randomized, placebo-controlled, double-blind trial involving 96 STEMI patients, the infarcted areas were significantly reduced in the rhTB4 group, which received the first dose of rhTB4 within 8&#x2005;h after PCI (n = 43), as compared to the placebo group at the 90-day follow-up. However, the overall differences in infarcted areas were not significantly between the rhTB4 group and the placebo group (n = 96). These findings underscore the crucial role of rhTB4 in mitigating cardiac dysfunction in an ErbB2-dependent manner. The clinical relevance of rhTB4 is demonstrated through a randomized controlled trial, emphasizing its translational potential. Further rigorous randomized studies are needed to assess the significance of early rhTB4 use post-myocardial infarction reperfusion.

Localization of thymosin beta-4 in tumors.

Overexpression of thymosin beta-4 has been linked to malignant progression but the localization of this polypeptide within tumors is incompletely known. We therefore examined breast cancers for thymosin beta-4 using immunofluorescence. Reactive cells were identified with monoclonal cell marker antibodies. A very heterogeneous staining pattern for thymosin beta-4 was observed. Thus, while leukocytes and macrophages showed intense reactivity for this polypeptide, cancer cells, and endothelial cells showed a much more variable reactivity. A similar heterogeneous staining was observed also in colorectal carcinomas. The degree of staining of breast cancer cells for thymosin beta-4 correlated neither to histological grade nor to endothelial cell staining. However, there was a tendency toward correlation (P = 0.07) between staining of endothelial cells and histological grade. Treatment of cultured breast cancer cells (SK-BR-3) with 1-4 microg thymosin beta-4/mL significantly increased cell numbers, as determined by MTT-assays. These data reveal an unexpected cellular heterogeneity of thymosin beta-4 expression in breast and colonic carcinomas and suggest that local release of this polypeptide in the tumor microenvironment may modulate tumor behavior.

Chemical characterization of thymosin beta 4.

As part of our ongoing investigations on the endocrine thymus, we have isolated and purified to homogeneity a hormone-like peptide which we have termed thymosin beta 4. Thymosin beta 4 has Mr = 4982 and an isoelectric point of 5.1. The complete amino acid sequence of this polypeptide has been established by automated Edman degradation as well as by manual sequence analysis. Thymosin beta 4 is composed of 43 amino acid residues with acetylserine at the NH2 terminus. This molecule induces expression of terminal deoxynucleotidyl transferase in transferase-negative murine thymocytes in vivo and in vitro. It also exhibits ability to inhibit the migration of macrophages. Comparison of the sequence of thymosin beta 4 to other thymic hormones or other published protein sequences does not reveal any statistically significant relationship. Two helical regions were identified in the structure using data for prediction of protein conformation. It is proposed that thymosin beta 4 is one of the biologically active peptides present in thymosin fractions 5 and 5A which participate in the regulation, differentiation, and function of thymus-derived lymphocytes and may also act directly or indirectly on macrophages and perhaps other cells involved in cell-mediated immunity.

Thymosin beta 4: A potential novel adjunct treatment for bacterial keratitis.

Microbial keratitis is a rapidly progressing, visually debilitating infection of the cornea that can lead to corneal scarring, endophthalmitis, and perforation. Corneal opacification or scarring, a complication of keratitis, is among the leading causes of legal blindness worldwide, second to cataracts.Pseudomonas aeruginosaandStaphylococcus aureusare the two bacteria most commonly associated with this type of infection. Risk factors include patients who are immunocompromised, those who have undergone refractive corneal surgery, and those with prior penetrating keratoplasty, as well as extended wear contact lens users. Current treatment of microbial keratitis primarily addresses the pathogen using antibiotics. Bacterial clearance is of utmost importance yet does not guarantee good visual outcome. Clinicians are often left to rely upon the eye's innate ability to heal itself, as there are limited options beyond antibiotics and corticosteroids for treating patients with corneal infection. Beyond antibiotics, agents in use, such as lubricating ointments, artificial tears, and anti-inflammatory drops, do not fully accommodate clinical needs and have many potential harmful complications. To this end, treatments are needed that both regulate the inflammatory response and promote corneal wound healing to resolve visual disturbances and improve quality of life. Thymosin beta 4 is a small, naturally occurring 43-amino-acid protein that promotes wound healing and reduces corneal inflammation and is currently in Phase 3 human clinical trials for dry eye disease. Our previous work has shown that topical T&#x3b2;4 as an adjunct to ciprofloxacin treatment reduces inflammatory mediators and inflammatory cell infiltrates (neutrophils/PMN and macrophages) while enhancing bacterial killing and wound healing pathway activation in an experimental model ofP. aeruginosa-induced keratitis. Adjunctive thymosin beta 4 treatment holds novel therapeutic potential to regulate and, optimally, resolve disease pathogenesis in the cornea and perhaps other infectious and immune-based inflammatory disease. We plan to establish the importance of thymosin beta 4 as a therapeutic agent in conjunction with antibiotics with high impact for immediate clinical development.

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

Thymosin beta 4 (T&#x3b2;4), a secreted 43 amino acid peptide, promotes oligodendrogenesis, and improves neurological outcome in rat models of neurologic injury. We demonstrated that exogenous T&#x3b2;4 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 T&#x3b2;4 treatment in vitro. Thus, T&#x3b2;4 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. T&#x3b2;4-induced micro-RNA-200a (miR-200a) regulates EGFR signaling pathways for MBP synthesis and apoptosis: up-regulation of miR-200a after T&#x3b2;4 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.

Loss of endogenous thymosin &#x3b2;4 accelerates glomerular disease.

Glomerular disease is characterized by morphologic changes in podocyte cells accompanied by inflammation and fibrosis. Thymosin &#x3b2;4 regulates cell morphology, inflammation, and fibrosis in several organs and administration of exogenous thymosin &#x3b2;4 improves animal models of unilateral ureteral obstruction and diabetic nephropathy. However, the role of endogenous thymosin &#x3b2;4 in the kidney is unknown. We demonstrate that thymosin &#x3b2;4 is expressed prominently in podocytes of developing and adult mouse glomeruli. Global loss of thymosin &#x3b2;4 did not affect healthy glomeruli, but accelerated the severity of immune-mediated nephrotoxic nephritis with worse renal function, periglomerular inflammation, and fibrosis. Lack of thymosin &#x3b2;4 in nephrotoxic nephritis led to the redistribution of podocytes from the glomerular tuft toward the Bowman capsule suggesting a role for thymosin &#x3b2;4 in the migration of these cells. Thymosin &#x3b2;4 knockdown in cultured podocytes also increased migration in a wound-healing assay, accompanied by F-actin rearrangement and increased RhoA activity. We propose that endogenous thymosin &#x3b2;4 is a modifier of glomerular injury, likely having a protective role acting as a brake to slow disease progression.

The Prognostic Significance of TMSB4X in Glioma Patients.

The goal of this study was to analyze in depth the importance of the thymosin beta 4 X-linked gene (TMSB4X) in the disease process of gliomas for the prediction of patient prognosis. We explored the expression of TMSB4X by analyzing datasets from The Cancer Genome Atlas (TCGA) datasets and the Chinese Glioma Genome Atlas (CGGA). Tumor sample tissues and corresponding paracancerous tissues of glioma patients were collected, and TMSB4X expression in glioma tissues was analyzed using Real-Time PCR to investigate its prognostic significance in glioma patients. In addition, we have plotted the ROC curves for the survival rate, performed univariate and multivariate Cox analyses and constructed nomogram. Differential expression analyses were performed on the basis of median expression levels of the TMSB4X gene, and Intuitive graphical presentation and visualisation of the 403 proteins screened were carried out using the Cytoscape software platform. (version: 3.9.1). The top 50 core genes were then screened using the cyto Hubba algorithm, these genes were analyzed using The Gene Ontology Database (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). TCGA datasets was utilized for Gene Set Enrichment Analysis (GSEA) to obtain potential NF-&#x3ba;B-related pathways in gliomas. Independent prognostic analyses show that the TMSB4X gene was identified as an independent prognostic indicator for gliomas. In GOKEGG and GSEA analyses, the analyses indicate that TMSB4X may play a crucial role in glioma patients by up-regulating I-kappaB kinase/NF-kappaB signaling. In glioma patients, upregulation of the I-kappaB kinase and NF-kappaB signalling pathways plays a crucial role, which may be linked to CASP1. The findings showed that TMSB4X was identified as an potential independent risk factor in the prognosis of glioma patients, a finding that implies that TMSB4X has the potential to serve as a key biomarker for predicting the prognostic status of glioma patients.

Potential role of thymosin beta 4 in the treatment of nonalcoholic fatty liver disease.

As a result of increased prevalence of obesity worldwide, non-alcoholic fatty liver disease (NAFLD) has become one of the most common causes of chronic liver disease. Although most NAFLD cases remain benign, some progress to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma. Therefore, treatment should be considered for NAFLD patients who are likely to progress to nonalcoholic steatohepatitis (NASH) or fibrosis. Thymosin beta 4 (T&#x3b2;4), a G-actin sequestering peptide, regulates actin polymerization in mammalian cells. In addition, studies have reported anti-inflammatory, insulin-sensitizing, and anti-fibrotic effects of T&#x3b2;4. However, no research has been done to investigate the effects of T&#x3b2;4 on NAFLD. Based on the findings above mentioned, we hypothesize that T&#x3b2;4 may represent an effective treatment for NAFLD.

Thymosin &#x3b2;4 as a restorative/regenerative therapy for neurological injury and neurodegenerative diseases.

Thymosin &#x3b2;4 (T&#x3b2;4) promotes CNS and peripheral nervous system (PNS) plasticity and neurovascular remodeling leading to neurological recovery in a range of neurological diseases. Treatment of neural injury and neurodegenerative disease 24 h or more post-injury and disease onset with T&#x3b2;4 enhances angiogenesis, neurogenesis, neurite and axonal outgrowth, and oligodendrogenesis, and thereby, significantly improves functional and behavioral outcomes. We propose that oligodendrogenesis is a common link by which T&#x3b2;4 promotes recovery after neural injury and neurodegenerative disease. The ability to target many diverse restorative processes via multiple molecular pathways that drive oligodendrogenesis and neurovascular remodeling may be mediated by the ability of T&#x3b2;4 to alter cellular expression of microRNAs (miRNAs). However, further investigations on the essential role of miRNAs in regulating protein expression and the remarkable exosomal intercellular communication network via exosomes will likely provide insight into mechanisms of action and means to amplify the therapeutic effects of T&#x3b2;4.

Thymosin beta 4 prevents systemic lipopolysaccharide-induced plaque load in middle-age APP/PS1 mice.

Lipopolysaccharide (LPS) produced by the gut during systemic infections and inflammation is thought to contribute to Alzheimer's disease (AD) progression. Since thymosin beta 4 (T&#x3b2;4) effectively reduces LPS-induced inflammation in sepsis, we tested its potential to alleviate the impact of LPS in the brain of the APPswePS1dE9 mouse model of AD (APP/PS1) and wildtype (WT) mice. 12.5-month-old male APP/PS1 mice (n&#xa0;=&#xa0;30) and their WT littermates (n&#xa0;=&#xa0;29) were tested for baseline food burrowing performance, spatial working memory and exploratory drive in the spontaneous alternation and open-field tests, prior to being challenged with LPS (100ug/kg, i.v.) or its vehicle phosphate buffered saline (PBS). T&#x3b2;4 (5&#xa0;mg/kg, i.v.) or PBS, was administered immediately following and at 2 and 4&#xa0;h after the PBS or LPS challenge, and then once daily for 6&#xa0;days (n&#xa0;=&#xa0;7-8). LPS-induced sickness was assessed though monitoring of changes in body weight and behaviour over a 7-day period. Brains were collected for the determination of amyloid plaque load and reactive gliosis in the hippocampus and cortex. Treatment with T&#x3b2;4 alleviated sickness symptoms to a greater extent in APP/PS1 than in WT mice by limiting LPS-induced weight loss and inhibition of food burrowing behaviour. It prevented LPS-induced amyloid burden in APP/PS1 mice but increased astrocytic and microglial proliferation in the hippocampus of LPS-treated WT mice. These data show that T&#x3b2;4 can alleviate the adverse effects of systemic LPS in the brain by preventing exacerbation of amyloid deposition in AD mice and by inducing reactive microgliosis in aging WT mice.

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 PrPSc. Thymosin beta 4 (T&#x3b2;4) 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 T&#x3b2;4 on prion disease has not yet been investigated. Therefore, in this study, we investigated the effect of T&#x3b2;4 on prion-induced BBB dysfunction in hCMEC/D3 human cerebral endothelial cells. We found that T&#x3b2;4 increased the expression of tight junction protein, but reduced the ratio of F-actin to G-actin. Moreover, we showed that T&#x3b2;4 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 T&#x3b2;4 may play a critical role in barrier stabilization. Furthermore, T&#x3b2;4 may prevent neurodegenerative diseases caused by prion-induced BBB dysfunction.

Isolation and structural characterization of thymosin-beta 4 from a human medullary thyroid carcinoma.

An extract of a tumour metastases from a human medullary thyroid carcinoma contained a high concentration (at least 2.9 nmol/g wet weight) of the immunoregulatory peptide, thymosin-beta 4. The peptide was isolated as a mixture of two components with free and blocked NH2-terminal amino acid residues, the latter form predominating (approximately 98% of the total). The primary structure of the peptide was established by automated Edman degradation after cleavage with cyanogen bromide. The amino acid sequence of human thymosin-beta 4 was identical to thymosin-beta 4 previously isolated from calf thymus. Further studies are warranted to determine whether thymosin-beta 4 production is a useful marker for thyroid and other tumours.

T&#x3b2;4-Ac-SDKP pathway: Any relevance for the cardiovascular system?

The last 20 years witnessed the emergence of the thymosin &#x3b2;4 (T&#x3b2;4)-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 T&#x3b2;4 and (or) its N-terminal derivative, Ac-SDKP. Specifically, Ac-SDKP is endogenously produced from the 43-amino acid T&#x3b2;4 by 2 successive enzymes, meprin &#x3b1; and prolyl oligopeptidase. We also discussed the possible mechanisms involved in the T&#x3b2;4-Ac-SDKP-associated cardiovascular biological effects. In infarcted myocardium, T&#x3b2;4 and Ac-SDKP facilitate cardiac repair after infarction by promoting endothelial cell migration and myocyte survival. Additionally, T&#x3b2;4 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 T&#x3b2;4 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.

Reconsidering an active role for G-actin in cytoskeletal regulation.

Globular (G)-actin, the actin monomer, assembles into polarized filaments that form networks that can provide structural support, generate force and organize the cell. Many of these structures are highly dynamic and to maintain them, the cell relies on a large reserve of monomers. Classically, the G-actin pool has been thought of as homogenous. However, recent work has shown that actin monomers can exist in distinct groups that can be targeted to specific networks, where they drive and modify filament assembly in ways that can have profound effects on cellular behavior. This Review focuses on the potential factors that could create functionally distinct pools of actin monomers in the cell, including differences between the actin isoforms and the regulation of G-actin by monomer binding proteins, such as profilin and thymosin &#x3b2;4. Owing to difficulties in studying and visualizing G-actin, our knowledge over the precise role that specific actin monomer pools play in regulating cellular actin dynamics remains incomplete. Here, we discuss some of these unanswered questions and also provide a summary of the methodologies currently available for the imaging of G-actin.

Thymosin Beta 4 Protects Hippocampal Neuronal Cells against PrP (106-126) via Neurotrophic Factor Signaling.

Prion protein peptide (PrP) has demonstrated neurotoxicity in brain cells, resulting in the progression of prion diseases with spongiform degenerative, amyloidogenic, and aggregative properties. Thymosin beta 4 (T&#x3b2;4) plays a role in the nervous system and may be related to motility, axonal enlargement, differentiation, neurite outgrowth, and proliferation. However, no studies about the effects of T&#x3b2;4 on prion disease have been performed yet. In the present study, we investigated the protective effect of T&#x3b2;4 against synthetic PrP (106-126) and considered possible mechanisms. Hippocampal neuronal HT22 cells were treated with T&#x3b2;4 and PrP (106-126) for 24 h. T&#x3b2;4 significantly reversed cell viability and reactive oxidative species (ROS) affected by PrP (106-126). Apoptotic proteins induced by PrP (106-126) were reduced by T&#x3b2;4. Interestingly, a balance of neurotrophic factors (nerve growth factor and brain-derived neurotrophic factor) and receptors (nerve growth factor receptor p75, tropomyosin related kinase A and B) were competitively maintained by T&#x3b2;4 through receptors reacting to PrP (106-126). Our results demonstrate that T&#x3b2;4 protects neuronal cells against PrP (106-126) neurotoxicity via the interaction of neurotrophic factors/receptors.

Profilin: emerging concepts and lingering misconceptions.

Conflicting data suggest that profilin might function to promote either actin polymerization or depolymerization in cells. There are theoretical reasons and supportive data to suggest that profilin might do both. Perhaps the most accurate description of profilin emphasizes its ability to augment actin-filament dynamics, both in polymerization and in depolymerization. The effect of profilin on the critical concentration of actin, its ability to depolymerize filaments at the barbed end and the formation of a ternary complex with thymosin beta(4) all need to be accurately represented in any attempt to determine a model for profilin function.