Cardioprotection by Thymosin Beta 4

The preliminary study of exosomes derived from thymosin beta 4-treated adipose-derived stem cells in fat grafting

BACKGROUND

The retention rate in autologous fat grafting is an increasing concern for surgeons and patients. Our previous research verified that thymosin beta 4 (Tβ4) positively affected fat survival, while the mechanism was unknown. The endothelial cells (ECs) and exosomes derived from adipose-derived stem cells (ADSCs) were regarded to play a critical role in fat transplantation.

OBJECTIVE

This study aimed to evaluate the effect of exosomes derived from Tβ4-treated ADSCs on EC proliferation and to identify the exosomal microRNA (miRNA) profile compared with the Tβ4-untreated group. Additionally, this research intended to recognize the related molecules and signaling pathways in the Tβ4-treated group with potential roles in fat transplants.

METHODS

ADSCs were collected from patients who underwent liposuction surgery. Depending on whether the medium was supplemented with exogenous Tβ4 or not, exosomes derived from cultured ADSCs were divided into the Tβ4-Exos group and Con-Exos group. Exosome uptake and cell counting kit-8 (CCK-8) assays assessed the influence of Tβ4-Exos on EC proliferation. The exosomal miRNAs of the two groups were analyzed by next-generation sequencing. With the criteria at the |log₂ (fold change)| ≥ 1 and p-value < 0.05, up-regulated and down-regulated differentially expressed miRNAs (DEMs) were obtained. Prediction databases were used to predict the downstream mRNAs for DEMs. And then, overlapping genes for the up-regulated DEMs and the down-regulated were screened out, followed by enrichment analysis, protein-protein interaction network construction, and the gene cluster and hub gene identification.

RESULTS

ADSCs were obtained from four female patients. The exosome uptake and CCK-8 assays showed that the Tβ4-Exos could increase cell growth rate compared with the control group (DMEM-H + PBS). In Tβ4-Exos and Con-Exos groups, 2651 exosomal miRNAs were recognized, with 80 up-regulated and 99 down-regulated DEMs according to the criteria. After the prediction, 621 overlapping genes for the up-regulated and 572 for the down-regulated DEMs were screened. The subsequent bioinformatics analysis found specific molecules and pathways related to the positive effect on fat survival.

CONCLUSIONS

The exosomes derived from Tβ4-treated ADSCs probably positively affect EC proliferation. Compared with the Con-Exos group, several exosomal DEMs, genes, and pathways were distinguished. These findings of this exploratory study provide the potential direction for future in-depth research on fat grafting.

An efficient system for bioconjugation based on a widely applicable engineered O-glycosylation tag

Bioconjugates are an important class of therapeutic molecules. To date, O-glycan-based metabolic glycoengineering has had limited use in this field, due to the complexities of the endogenous O-glycosylation pathway and the lack of an O-glycosylation consensus sequence. Here, we describe the development of a versatile on-demand O-glycosylation system that uses a novel, widely applicable 5 amino acid O-glycosylation tag, and a metabolically engineered UDP-galactose-4-eperimase (GALE) knock-out cell line. Optimization of the primary sequence of the tag enables the production of Fc-based proteins with either single or multiple O-glycans with complexity fully controlled by media supplementation. We demonstrate how the uniformly labeled proteins containing exclusively N-azido-acetylgalactosamine are used for CLICK chemistry-based bioconjugation to generate site-specifically fluorochrome-labeled antibodies, dual-payload molecules, and bioactive Fc-peptides for applications in basic research and drug discovery. To our knowledge, this is the first description of generating a site-specific O-glycosylation system by combining an O-glycosylation tag and a metabolically engineered cell line.

Thymosin β4 increases cardiac cell proliferation, cell engraftment, and the reparative potency of human induced-pluripotent stem cell-derived cardiomyocytes in a porcine model of acute myocardial infarction

Rationale: Previous studies have shown that human embryonic stem cell-derived cardiomyocytes improved myocardial recovery when administered to infarcted pig and non-human primate hearts. However, the engraftment of intramyocardially delivered cells is poor and the effectiveness of clinically relevant doses of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in large animal models of myocardial injury remains unknown. Here, we determined whether thymosin β4 (Tb4) could improve the engraftment and reparative potency of transplanted hiPSC-CMs in a porcine model of myocardial infarction (MI). Methods: Tb4 was delivered from injected gelatin microspheres, which extended the duration of Tb4 administration for up to two weeks in vitro. After MI induction, pigs were randomly distributed into 4 treatment groups: the MI Group was injected with basal medium; the Tb4 Group received gelatin microspheres carrying Tb4; the CM Group was treated with 1.2 × 10⁸ hiPSC-CMs; and the Tb4+CM Group received both the Tb4 microspheres and hiPSC-CMs. Myocardial recovery was assessed by cardiac magnetic resonance imaging (MRI), arrhythmogenesis was monitored with implanted loop recorders, and tumorigenesis was evaluated via whole-body MRI. Results: In vitro, 600 ng/mL of Tb4 protected cultured hiPSC-CMs from hypoxic damage by upregulating AKT activity and BcL-XL and promoted hiPSC-CM and hiPSC-EC proliferation. In infarcted pig hearts, hiPSC-CM transplantation alone had a minimal effect on myocardial recovery, but co-treatment with Tb4 significantly enhanced hiPSC-CM engraftment, induced vasculogenesis and the proliferation of cardiomyocytes and endothelial cells, improved left ventricular systolic function, and reduced infarct size. hiPSC-CM implantation did not increase incidence of ventricular arrhythmia and did not induce tumorigenesis in the immunosuppressed pigs. Conclusions: Co-treatment with Tb4-microspheres and hiPSC-CMs was safe and enhanced the reparative potency of hiPSC-CMs for myocardial repair in a large-animal model of MI.

PASylated Thymosin α1: A Long-Acting Immunostimulatory Peptide for Applications in Oncology and Virology

Thymosin α1 (Tα1) is an immunostimulatory peptide for the treatment of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections and used as an immune enhancer, which also offers prospects in the context of COVID-19 infections and cancer. Manufacturing of this N-terminally acetylated 28-residue peptide is demanding, and its short plasma half-life limits in vivo efficacy and requires frequent dosing. Here, we combined the PASylation technology with enzymatic in situ N-acetylation by RimJ to produce a long-acting version of Tα1 in Escherichia coli at high yield. ESI-MS analysis of the purified fusion protein indicated the expected composition without any signs of proteolysis. SEC analysis revealed a 10-fold expanded hydrodynamic volume resulting from the fusion with a conformationally disordered Pro/Ala/Ser (PAS) polypeptide of 600 residues. This size effect led to a plasma half-life in rats extended by more than a factor 8 compared to the original synthetic peptide due to retarded kidney filtration. Our study provides the basis for therapeutic development of a next generation thymosin α1 with prolonged circulation. Generally, the strategy of producing an N-terminally protected PASylated peptide solves three major problems of peptide drugs: (i) instability in the expression host, (ii) rapid degradation by serum exopeptidases, and (iii) low bioactivity because of fast renal clearance.

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.

Thymosinβ4 alleviates cholestatic liver fibrosis in mice through downregulating PDGF/PDGFR and TGFβ/Smad pathways

Liver fibrosis is an important health problem without adequate and effective therapeutics. In this study, effects of thymosinβ4 (Tβ4) on hepatic fibrogenesis and the underlying molecular mechanisms were explored in bile duct ligation (BDL)-induced mice cholestatic liver fibrosis model. Results showed exogenous Tβ4 significantly reduced the mortality and liver/body weight ratio in BDL mice. Histological examinations and biochemical analyses demonstrated that BDL induced evident portal fibrosis and a significant increase in hepatic collagen contents. However, these changes were significantly attenuated by exogenous Tβ4. Quantitative real-time PCR assays showed that Tβ4 suppressed BDL-induced increases in many fibrotic genes expression including α-smooth muscle actin (α-SMA), collagen I, III and fibronectin, TGFβ1, TGFβR II, Smad2, Smad3, and PDGFRβ. Results from immunohistochemistry and Western blots also showed that Tβ4 reduced TGFβ1 and PDGFRβ protein levels in the liver tissues of BDL mice. In vitro studies using LX-2 cells demonstrated that Tβ4 could decrease PDGFRβ and TGFβR II levels in hepatic stellate cells. Taken together, findings in our present studies suggested that exogenous Tβ4 alleviated BDL-induced cholestatic liver fibrosis through downregulating PDGF/PDGFR and TGFβ/Smad pathways.

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.