Thymosin alpha(1) application augments immune response and down-regulates tumor weight and organ colonization in BALB/c-mice

Epithelial-mesenchymal transition in age-associated thymic involution: Mechanisms and therapeutic implications

The thymus is a critical immune organ with endocrine and immune functions that plays important roles in the physiological and pathological processes of the body. However, with aging, the thymus undergoes degenerative changes leading to decreased production and output of naive T cells and the secretion of thymic hormones and related cytokines, thereby promoting the occurrence and development of various age-associated diseases. Therefore, identifying essential processes that regulate age-associated thymic involution is crucial for long-term control of thymic involution and age-associated disease progression. Epithelial-mesenchymal transition (EMT) is a well-established process involved in organ aging and functional impairment through tissue fibrosis in several organs, such as the heart and kidney. In the thymus, EMT promotes fibrosis and potentially adipogenesis, leading to thymic involution. This review focuses on the factors involved in thymic involution, including oxidative stress, inflammation, and hormones, from the perspective of EMT. Furthermore, current interventions for reversing age-associated thymic involution by targeting EMT-associated processes are summarized. Understanding the key mechanisms of thymic involution through EMT as an entry point may promote the development of new therapies and clinical agents to reverse thymic involution and age-associated disease.

Thymosin alpha-1; a natural peptide inhibits cellular proliferation, cell migration, the level of reactive oxygen species and promotes the activity of antioxidant enzymes in human lung epithelial adenocarcinoma cell line (A549)

This research was conducted to investigate the biochemical effects of thymosin alpha-1 using human lung cancer cells (A549). The A549 cells were treated with different concentrations of Thα1 for 24 h and the growth, inhibition of cells was determined. Thα1 revealed anti-proliferative effect at 24 and 48 μg/ml after 24 h. Furthermore, it indicated antioxidant properties by significantly enhancing the activity of catalase (12 μg/ml), superoxide dismutase (6 and 12 μg/ml), and glutathione peroxidase (3, 6 and 12 μg/ml) and reducing the production of cellular ROS. Our results showed that Thα1 inhibits the migration of A549 cells in a concentration-dependent manner after 24 and 48 h. Moreover, the effect of Thα1 on apoptosis was investigated by Hoechst 33342 staining and cell cycle analysis. Results demonstrated no significant effect on the induction of apoptosis in A549 cells. In conclusion, our results showed the antioxidant properties of Thα1 on A549 cancer cells.

The in vivo immunomodulatory and synergistic anti-tumor activity of thymosin α1-thymopentin fusion peptide and its binding to TLR2

In the present study, the immunomodulatory and synergistic anti-tumor activity of thymosin α1-thymopentin fusion peptide (Tα1-TP5) was investigated in vivo. In addition, the potential receptor of Tα1-TP5 was investigated by surface plasmon resonance (SPR) binding studies. It was found that Tα1-TP5 (305 μg/kg) alleviated immunosuppression induced by hydrocortisone (HC). Tα1-TP5 (305 μg/kg) combined with cyclophosphamide (CY) had a better tumor growth inhibitory effect than CY alone. Furthermore, Tα1-TP5 had a higher affinity (KD=6.84 μmol/L) to toll-like receptor 2 (TLR2) than Tα1 (K(D)=35.4 μmol/L), but its affinity was not significantly different from that of TP5. The results of our present work indicate that Tα1-TP5 can possibly be developed as a new immunomodulatory agent.

Thymosin alpha 1: biological activities, applications and genetic engineering production

Thymosin alpha 1 (Tα1), a 28-amino acid peptide, was first described and characterized from calf thymuses in 1977. This peptide can enhance T-cell, dendritic cell (DC) and antibody responses, modulate cytokines and chemokines production and block steroid-induced apoptosis of thymocytes. Due to its pleiotropic biological activities, Tα1 has gained increasing interest in recent years and has been used for the treatment of various diseases in clinic. Accordingly, there is an increasing need for the production of this peptide. So far, Tα1 used in clinic is synthesized using solid phase peptide synthesis. Here, we summarize the genetic engineering methods to produce Tα1 using prokaryotic or eukaryotic expression systems. The effectiveness of these biological products in increasing the secretion of cytokines and in promoting lymphocyte proliferation were investigated in vitro studies. This opens the possibility for biotechnological production of Tα1 for the research and clinical applications.

Potential Role of Thymosin-alpha1 Adjuvant Therapy for Glioblastoma

Glioblastomas are high-grade, malignant CNS neoplasms that are nearly always fatal within 12 months of diagnosis. Immunotherapy using proinflammatory cytokines such as IL-2 or IL-12 may prolong survival with glioblastoma. Thymosin-α1 (Talpha1) is a thymic hormone and immunemodulator that increase IL-2 production and T-cell proliferation. We examined potential therapeutic effects of Talpha1 in experimental in vivo glioblastoma, and characterized Talpha1's anti-tumor effects in vitro. Rar 9L cells (10⁴) were implanted into the right frontal lobe of adult Long Evans rats that were subsequently treated with vehicle, BCNU, Talpha1, or Talpha1+BCNU from postoperative day 6. Talpha1+BCNU significantly lowered tumor burdens, and increased cure rates. In vitro experiments demonstrated that Talpha1 had no direct effect on viability or mitochondrial function, and instead, it increased expression of pro-apoptosis genes, including FasL, FasR and TNFα-R1 (65.89%, 44.08%, and 22.18%, resp.), and increased 9L cell sensitivity to oxidative stress. Moreover, Talpha1 enhanced 9L cell sensitivity to both Granzyme B- and BCNU-mediated killing. The findings suggest that Talpha1 enhances BCNUmediated eradication of glioblastoma in vivo, and that Talpha1 mediates its effects by activating pro-apoptosis mechanisms, rendering neoplastic cells more sensitive to oxidative stress and immune-mediated killing by Granzyme B and chemotherapeutic agents.

Antitumor Activation of Peritoneal Macrophages by Thymosin Alpha-1

It was been previously reported that thyalpha1 can be used to activate monocytes, BMDM and TAM. However, the effect of thyalpha1 on other tissue macrophages has not been investigated. Moreover, there is no report about the use of thyalpha1-treated macrophages in adoptive immunotherapy of cancer. In view of these observations in the present study, we checked the response of various tissue macrophages to thyalpha1 for activation. Tissue macrophages showed differential response to thyalpha1; moreover, adoptive transfer of peritoneal macrophages treated with thyalpha1 to mice bearing spontaneous T-cell lymphoma designated as Dalton's lymphoma (DL) resulted in the prolongation of the survival time of tumor-bearing mice. The mechanism of macrophage therapy-dependent tumor regression was enhanced antitumor activity of macrophages in response to thyalpha1 treatment via their production of macrophage-activating cytokines that act in autocrine manner. These results will help in the development of immunotherapy against tumor based on activation of macrophage with thyalpha1.

Expression and hydroxylamine cleavage of thymosin alpha 1 concatemer

Human thymosin alpha 1 (Tα1) is an important peptide in the development and senescence of immunological competence in human, and many studies have reported the expression of this peptide. In this study, we designed and synthesized the Tα1 gene according to the E. coli codon usage preference and constructed a 6×Tα1 concatemer. The latter was inserted into an E. coli expression vector pET-22b (+), and transformed into E. coli BL21 (DE3). After induction with IPTG, the concatemer protein was successfully expressed in E. coli then cleaved by hydroxylamine to release the Tα1 monomer. Gly-SDS-PAGE and mass spectrometry confirmed that the recombinant protein was cleaved as intended. The bioactivity of the Tα1 monomer was analyzed by lymphocyte proliferation and by mitochondrial activity in two different tumor cell lines. This study provides a description of the preparation of a bioactive Tα1, which may prove useful in future biomedical research.

Thymosin alpha 1 improves severe acute pancreatitis in rats via regulation of peripheral T cell number and cytokine serum level

AIM

The aim of this study was to investigate the effect of thymosin alpha 1 (TA1) on severe acute pancreatitis (SAP) in rats.

METHODS

Healthy Sprague-Dawley rats (n = 72) were randomly divided into four groups: control group, SAP group, and two TA1 treated groups. SAP was induced by injection of 5% sterile sodium taurocholate into the biliopancreatic duct (BPD), after which TA1 was given subcutaneously at 0 and 2 h at a dose of 100 microg/kg. The rats were killed at 3, 6 and 12 h, respectively. Serum amylase and lipase, interleukin (IL)-1beta, tumor necrosis factor-alpha (TNF-alpha), pancreatic wet/dry weight ratio and the percentage of CD3/CD4+/CD8+ T cells in peripheral blood mononuclear cells (PBMC) were measured. Next, 30 rats were randomly divided into three groups (each group containing 10 animals): SAP group (S) and two TA1 treated groups. The effects of TA1 on the survival of SAP were assessed 72 h after the induction of SAP.

RESULTS

There was no significant change in the serum amylase and lipase levels after TA1 administration. Levels of serum IL-1beta, TNF-alpha and pancreatic wet/dry weight ratio were significantly reduced after TA1-treatment. Application of TA1 significantly balanced CD3/CD4+/CD8+ T cells of PBMC and improved histological scores and the survival rate.

CONCLUSION

TA1 can reduce pancreatic inflammation by regulating differentiation of CD3/CD4+ T cells and decreasing the release of cytokines, thus attenuates pancreatic severity in SAP rats.

Liposomal plasmid DNA encoding human thymosin alpha and interferon omega potently inhibits liver tumor growth in ICR mice

AIM

To evaluate the potential therapeutic effect of liposomal gene delivery, genes encoding for human thymosin alpha1 (Talpha1) and interferon omega1 were injected via the tail vein into mice bearing a Hep-A-22 liver tumor.

METHODS

The cDNA of human Talpha1 and interferon omega1 were obtained by synthesis or reverse transcription-polymerase chain reaction (RT-PCR), respectively. Eukaryotic expressing vectors pIRES2, encoding Talpha1 and/or interferon omega1, were constructed and injected with liposome via the tail vein into ICR mice bearing a Hep-A-22 tumor. The potency of tumor inhibition was evaluated when three treated groups were compared with the group receiving the empty vector. Apoptosis of tumor cells was investigated by analyzing DNA fragmentation.

RESULTS

Only the group treated with dual-gene plasmid reached an eligible level of tumor inhibition (43%). The difference in tumor weight was statistically significant between the Talpha1 gene or the interferon omega1 gene treated groups and the control (P<0.05), and highly significant between the dual-gene treated group and the control (P<0.01). DNA ladder was observed in the tumor cells from the purpose gene treated groups but not from the control.

CONCLUSION

The dual-gene plasmid-liposome complex showed more potent inhibition than the single gene constructs on the growth of Hep-A-22 tumor cells in mice, which may be attributed to indirect and additive induction of apoptosis in tumor cells by increased expression of Talpha1 and interferon omega1.

Thymosin alpha 1 attenuates lipid peroxidation and improves fructose-induced steatohepatitis in rats

OBJECTIVES

The aim of this study was to investigate the effects of thymosin alpha(1) (Talpha(1)) in rats having fructose-induced steatosis. Fructose leads to experimental steatosis in the liver by exerting its effect on some components of the oxidant/antioxidant system, and on several cytokines (interleukin-1beta, -2, and -6) in blood.

METHODS

Twenty-four rats at random were divided into three groups (each group containing eight animals); the control group (C), which received a purified diet; the high-fructose-fed group (F); and the high-fructose-fed and Talpha(1) injected group (F + T). After the experimental period of 10 days, liver lipid peroxidation and antioxidant status, and blood IL-1beta, IL-2, and IL-6 levels were quantified.

RESULTS

In comparison with the C group, the F group had a higher nitric oxide (NO) level, xanthine oxidase (XO) activity, and lipid peroxidation, as indicated by concentrations of thiobarbituric acid reactive substances (TBARS), and lower superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the liver. In the F + T group, these markers were near the values of the control group. In addition, increased IL-1beta and IL-6 levels were kept at near to normal levels with treatment of Talpha(1), but not IL-2 levels. In the F group, the most consistent findings in the histologic sections of liver tissues were the macrovesicular and microvesicular steatosis. Talpha(1) treatment protected the majority of the liver cells, while minimal macrovesicular and microvesicular steatosis was observed in the remaining cells.

CONCLUSIONS

These results show that a high-fructose diet in rats leads to hepatic steatosis and a defect in the free radical defense system, and that treatment of Talpha(1) may improve these biochemical and morphologic changes in the fructose-fed rat livers.

Effect of thymosin alpha 1 on the antitumor activity of tumor-associated macrophage-derived dendritic cells

We have previously suggested that thymosin alpha(1) (thyalpha1), an immunomodulating thymic hormone, can activate tumor-associated macrophages to a tumoricidal state in a murine model bearing a transplantable T-cell lymphoma of spontaneous origin designated as Dalton's lymphoma (DL). Since tumor-infiltrating dendritic cells (DC) also play an important role in the host's antitumor response and are as such in an immunocompromised state in a tumor-bearing host, in the present investigation we studied if thyalpha1 is able to influence the differentiation of tumor-associated macrophages (TAM) into DC with granulocyte macrophage colony stimulating factor (GM-CSF), interleukin (IL)-4 and tumor necrosis factor (TNF) and whether these TAM-derived DC show enhanced antitumor activity. It was observed that DC generated from thyalpha1-administered tumor-bearing mice showed augmented antitumor activity in vitro. Adoptive immunotherapy using TAM-derived DC showed a significant delay in the tumor growth and a prolongation of the survival time in tumor-bearing mice. DC obtained from TAM of thyalpha1-administered mice also produced an enhanced amount of cytokines like IL-1 and TNF-alpha. This is the first study of its kind regarding the effect of thyalpha1 on the differentiation of DC from TAM and the role of TAM-derived DC in tumor progression.

Application of standardized mistletoe extracts augment immune response and down regulates metastatic organ colonization in murine models

The immunomodulatory and antimetastatic activity of standardized aqueous mistletoe extracts from plants grown on fir trees (ME-A) and pine trees (ME-P) were evaluated in BALB/c-mice. Regular subcutaneous (s.c.) and intraperitoneal (i.p.) applications (three times per week for 14 consecutive days; 5 and 50 microg per injection and mouse) upregulated thymus weight and peripheral blood leukocyte counts in tumor bearing mice. To check the influence of ME-A and ME-P treatment on growth of experimental metastases, RAW 117 H 10 lymphosarcoma cells and L-1 sarcoma cells were intravenously inoculated into BALB/c-mice to establish liver and lung colonization. ME-A and ME-P were regularly administered starting 24 h after tumor cell challenge. Organ colonization was investigated on day 14 after tumor cell inoculation and demonstrated statistically significant (P<0.05) reductions of experimental liver and lung metastases for ME-A and ME-P treated mice.