Involvement of mitogen-activated protein kinases in the signal transduction pathway of bone marrow-derived macrophage activation in response to in vitro treatment with thymosin alpha 1

Phenotypic drug discovery: a case for thymosin alpha-1

Phenotypic drug discovery (PDD) involves screening compounds for their effects on cells, tissues, or whole organisms without necessarily understanding the underlying molecular targets. PDD differs from target-based strategies as it does not require knowledge of a specific drug target or its role in the disease. This approach can lead to the discovery of drugs with unexpected therapeutic effects or applications and allows for the identification of drugs based on their functional effects, rather than through a predefined target-based approach. Ultimately, disease definitions are mostly symptom-based rather than mechanism-based, and the therapeutics should be likewise. In recent years, there has been a renewed interest in PDD due to its potential to address the complexity of human diseases, including the holistic picture of multiple metabolites engaging with multiple targets constituting the central hub of the metabolic host-microbe interactions. Although PDD presents challenges such as hit validation and target deconvolution, significant achievements have been reached in the era of big data. This article explores the experiences of researchers testing the effect of a thymic peptide hormone, thymosin alpha-1, in preclinical and clinical settings and discuss how its therapeutic utility in the precision medicine era can be accommodated within the PDD framework.

Thymosin α1 and Its Role in Viral Infectious Diseases: The Mechanism and Clinical Application

Thymosin α1 (Tα1) is an immunostimulatory peptide that is commonly used as an immune enhancer in viral infectious diseases such as hepatitis B, hepatitis C, and acquired immune deficiency syndrome (AIDS). Tα1 can influence the functions of immune cells, such as T cells, B cells, macrophages, and natural killer cells, by interacting with various Toll-like receptors (TLRs). Generally, Tα1 can bind to TLR3/4/9 and activate downstream IRF3 and NF-κB signal pathways, thus promoting the proliferation and activation of target immune cells. Moreover, TLR2 and TLR7 are also associated with Tα1. TLR2/NF-κB, TLR2/p38MAPK, or TLR7/MyD88 signaling pathways are activated by Tα1 to promote the production of various cytokines, thereby enhancing the innate and adaptive immune responses. At present, there are many reports on the clinical application and pharmacological research of Tα1, but there is no systematic review to analyze its exact clinical efficacy in these viral infectious diseases via its modulation of immune function. This review offers an overview and discussion of the characteristics of Tα1, its immunomodulatory properties, the molecular mechanisms underlying its therapeutic effects, and its clinical applications in antiviral therapy.

Thymus Gland: A Double Edge Sword for Coronaviruses

The thymus is the main lymphoid organ that regulates the immune and endocrine systems by controlling thymic cell proliferation and differentiation. The gland is a primary lymphoid organ responsible for generating mature T cells into CD4+ or CD8+ single-positive (SP) T cells, contributing to cellular immunity. Regarding humoral immunity, the thymic plasma cells almost exclusively secrete IgG1 and IgG3, the two main complement-fixing effector IgG subclasses. Deformity in the thymus can lead to inflammatory diseases. Hassall’s corpuscles’ epithelial lining produces thymic stromal lymphopoietin, which induces differentiation of CDs thymocytes into regulatory T cells within the thymus medulla. Thymic B lymphocytes produce immunoglobulins and immunoregulating hormones, including thymosin. Modulation in T cell and naive T cells decrement due to thymus deformity induce alteration in the secretion of various inflammatory factors, resulting in multiple diseases. Influenza virus activates thymic CD4+ CD8+ thymocytes and a large amount of IFNγ. IFNs limit virus spread, enhance macrophages’ phagocytosis, and promote the natural killer cell restriction activity against infected cells. Th2 lymphocytes-produced cytokine IL-4 can bind to antiviral INFγ, decreasing the cell susceptibility and downregulating viral receptors. COVID-19 epitopes (S, M, and N proteins) with ≥90% identity to the SARS-CoV sequence have been predicted. These epitopes trigger immunity for antibodies production. Boosting the immune system by improving thymus function can be a therapeutic strategy for preventing virus-related diseases. This review aims to summarize the endocrine-immunoregulatory functions of the thymus and the underlying mechanisms in the prevention of COVID-19.

The identification of neutrophils-mediated mechanisms and potential therapeutic targets for the management of sepsis-induced acute immunosuppression using bioinformatics

Neutrophils have crucial roles in defensing against infection and adaptive immune responses. This study aimed to investigate the genetic mechanism in neutrophils in response to sepsis-induced immunosuppression.The GSE64457 dataset was downloaded from the Gene Expression Omnibus database and the neutrophil samples (D3-4 and D6-8 post sepsis shock) were assigned into two groups. The differentially expressed genes (DEGs) were identified. The Short Time-series Expression Miner (STEM) clustering analysis was conducted to select the consistently changed DEGs post sepsis shock. The overlapping genes between the DEGs and the deposited genes associated with immune, sepsis, and immunosuppression in the AmiGO2 and Comparative Toxicogenomics Database were screened out and used for the construction of the protein-protein interaction (PPI) network. The expression of several hub genes in sepsis patients was validated using the PCR analysis. The drugs targeting the hub genes and the therapy strategies for sepsis or immunosuppression were reviewed and used to construct the drug-gene-therapy-cell network to illustrate the potential therapeutic roles of the hub genes.A total of 357 overlapping DEGs between the two groups were identified and were used for the STEM clustering analysis, which generated four significant profiles with 195 upregulated (including annexin A1, ANXA1; matrix metallopeptidase 9, MMP9; and interleukin 15, IL-15) and 151 downregulated DEGs (including, AKT1, IFN-related genes, and HLA antigen genes). Then, a total of 34 of the 151 downregulated DEGs and 39 of the 195 upregulated DEGs were shared between the databases and above DEGs, respectively. The PPI network analysis identified a downregulated module including IFN-related genes. The deregulation of DEGs including AKT1 (down), IFN-inducible protein 6 (IFI6, down), IL-15 (up), and ANXA1 (up) was verified in the neutrophils from patients with sepsis-induced immunosuppression as compared with controls. Literature review focusing on the therapy showed that the upregulation of IL-15, IFN, and HLA antigens are the management targets. Besides, the AKT1 gene was targeted by gemcitabine.These findings provided additional clues for understanding the mechanisms of sepsis-induced immunosuppression. The drugs targeting AKT1 might provide now clues for the management strategy of immunosuppression with the intention to prevent neutrophil infiltration.

Effect of superoxide anion scavenger on rat hearts with chronic intermittent hypoxia

Only very limited information regarding the protective effects of the superoxide anion scavenger on chronic intermittent hypoxia-induced cardiac apoptosis is available. The purpose of this study is to evaluate the effects of the superoxide anion scavenger on cardiac apoptotic and prosurvival pathways in rats with sleep apnea. Forty-two Sprague-Dawley rats were divided into three groups, rats with normoxic exposure (Control, 21% O2, 1 mo), rats with chronic intermittent hypoxia exposure (Hypoxia, 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo), and rats with pretreatment of the superoxide anion scavenger and chronic intermittent hypoxia exposure (Hypoxia-O2 (-)-Scavenger, MnTMPyP pentachloride, 1 mg/kg ip per day; 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo) at 5-6 mo of age. After 1 mo, the protein levels and apoptotic cells of excised hearts from three groups were measured by Western blotting and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay. The superoxide anion scavenger decreased hypoxia-induced myocardial architecture abnormalities, left ventricular hypertrophy, and TUNEL-positive apoptosis. The superoxide anion scavenger decreased hypoxia-induced Fas ligand, Fas death receptors, Fas-associated death domain (FADD), activated caspase-8, and activated caspase-3 (Fas-dependent apoptotic pathway) as well as Bad, activated caspase-9 and activated caspase-3 (mitochondria-dependent apoptotic pathway), endonuclease G (EndoG), apoptosis-inducing factor (AIF), and TUNEL-positive apoptosis. The superoxide anion scavenger increased IGF-1, IGF-1R, p-PI3k, p-Akt, p-Bad, Bcl-2, and Bcl-xL (survival pathway). Our findings imply that the superoxide anion scavenger might prevent cardiac Fas-mediated and mitochondrial-mediated apoptosis and enhance the IGF-1-related survival pathway in chronic intermittent hypoxia. The superoxide anion scavenger may prevent chronic sleep apnea-enhanced cardiac apoptotic pathways and enhances cardiac survival pathways.

Is boosting the immune system in sepsis appropriate?

A relative immunosuppression is observed in patients after sepsis, trauma, burns, or any severe insults. It is currently proposed that selected patients will benefit from treatment aimed at boosting their immune systems. However, the host immune response needs to be considered in context with pathogen-type, timing, and mainly tissue specificity. Indeed, the immune status of leukocytes is not universally decreased and their activated status in tissues contributes to organ failure. Accordingly, any new immune-stimulatory therapeutic intervention should take into consideration potentially deleterious effects in some situations.

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.

Immunopharmacology of thymosin alpha1 and cytokine synergy

Thymosin alpha1 (Talpha1) is a 28 amino acid biologically active protein cleaved from positions 2-29 of a precursor protein, prothymosin alpha. Since its discovery, Talpha1 has been administered to animals and humans in a wide variety of settings and its pharmacologic effects are to enhance cellular immunity. Talpha1 administration is highly effective in settings where irradiation, chemotherapy, tumor burden, or immune senescence have caused a reduction of T cell number and/or function. Recent in vitro studies, including the one reported here, suggest that Talpha1 may act via pathways commonly used by various cytokines. This raises the possibility that Talpha1 and cytokines may have synergistic activity through potentiation of cytokine activity by Talpha1. Improved control of tumor growth when tumor-bearing mice were treated with Talpha1 and high doses of IL-2 has been previously reported. We extended those studies with the Lewis lung carcinoma mouse model using IRX-2, a natural well-defined biologic containing multiple cytokines, in combination with Talpha1 (IRX-3). Although IRX-2 was effective alone (using doses that contain significantly less IL-2 than in most typical studies), adding Talpha1 led to significant improvement in survival of the tumor-bearing mice. Based on these observations, the immunopharmacology of Talpha1 predicts an important clinical role for Talpha1 in the restoration of cellular immune activity when used in combination with cytokines. Patients who experience immune suppression due to the presence of tumor, irradiation, and/or chemotherapy or aging of the host would most benefit from this treatment combination.

Thymosin-alpha1 modulates dendritic cell differentiation and functional maturation from human peripheral blood CD14+ monocytes

Although thymosins have been demonstrated to have immunomodulatory effects, it is still not clear whether they could affect dendritic cells (DCs), the most professional antigen-presenting cells. The objective of this study was to determine the effect and potential mechanisms of thymosin-alpha1 (Talpha1) on DC differentiation and functional maturation. Human peripheral blood CD14(+) monocytes were purified by using a magnetic separation column and cultured with GM-CSF and IL-4 to differentiate into immature DCs (iDCs). In the presence of Talpha1, iDC surface markers CD40, CD80, MHC class I and class II molecules were significantly upregulated as measured by flow cytemotry analysis. However, Tbeta4 or Tbeta10 did not show these effects on iDCs. There was an approximately 30% reduction in antigen (FITC-conjugated dextran)-uptake by Talpha1-treated iDCs as compared with non-Talpha1-treated iDCs. In addition, Talpha1-treated matured DCs (mDCs) showed an increased stimulation of allogeneic CD3(+) T-cell proliferation as measured by a mixed-lymphocyte reaction assay. Talpha1-treated mDCs also increased the production of several Th1- and Th2-type cytokines as measured by a Bio-Plex cytokine assay. Furthermore, rapid activation of p38 MAPK and NFkappaB was seen in Talpha1-treated iDCs as measured by a Bio-Plex phosphoprotein assay. Thus, Talpha1 significantly enhances DC differentiation, activation, and functions from human peripheral blood CD14(+) monocytes possibly through a mechanism of the activation of p38 MAPK and NFkappaB pathways. This study provides a basis to further evaluate Talpha1 as a possible adjuvant for a DC-directed vaccine or therapy.

Thymosin alpha1: an endogenous regulator of inflammation, immunity, and tolerance

Thymosin alpha1 (Talpha1), first described and characterized by Allan Goldstein in 1972, is used worldwide for the treatment of some immunodeficiencies, malignancies, and infections. Although Talpha1 has shown a variety of effects on cells and pathways of the immune system, its central role in modulating dendritic cell (DC) function has only recently been appreciated. As DCs have the ability to sense infection and tissue stress and to translate collectively this information into an appropriate immune response, an action on DCs would predict a central role for Talpha1 in inducing different forms of immunity and tolerance. Recent results have shown that Talpha1: (a) primed DCs for antifungal Th1 resistance through Toll-like receptor (TLR)/MyD88-dependent signaling and this translated in vivo in protection against aspergillosis; (b) activated plasmacytoid DCs (pDC) via the TLR9/MyD88-dependent viral recognition, thus leading to the activation of interferon regulatory factor 7 and the promotion of the IFN-alpha/IFN-gamma-dependent effector pathway, which resulted in vivo in protection against primary murine cytomegalovirus infection; (c) induced indoleamine 2,3-dioxygenase activity in DCs, thus affecting tolerization toward self as well as microbial non-self-antigens, and this resulted in vivo in transplantation tolerance and protection from inflammatory allergy. Talpha1 is produced in vivo by cleavage of prothymosin alpha in diverse mammalian tissues. Our data qualify Talpha1 as an endogenous regulator of immune homeostasis and suggest that instructive immunotherapy with Talpha1, via DCs and tryptophan catabolism, could be at work to control inflammation, immunity, and tolerance in a variety of clinical settings.

Thymosinalpha1 stimulates cell proliferation by activating ERK1/2, JNK, and increasing cytokine secretion in human pancreatic cancer cells

In this study, we investigated the expression and function of thymosinalpha1 (Thyalpha1) in human pancreatic cancer. We found that human pancreatic cancer cell lines Panc-1, Panc03.27, ASPC-1, and PL45 cells significantly over-expressed the mRNA of Thyalpha1 as compared to the normal human pancreatic ductal epithelium (HPDE) cells.. Thyalpha1 mRNA and protein levels were also over-expressed in clinical pancreatic adenocarcinoma specimens. In addition, synthetic Thyalpha1 significantly promoted Panc-1 cell proliferation and increased phosphorylation of ERK1/2 and JNK. Furthermore, Thyalpha1 increased the secretion of multiple cytokines including IL-10, IL-13, and IL-17 in Panc-1 cells. Thus, Thyalpha1 may have a new role in pancreatic cancer pathogenesis.

The modulation of thymosin alpha 1 in the maturation, differentiation and function of murine bone marrow-derived dendritic cells in the absence or presence of tumor necrosis factor-alpha

Thymosin alpha 1 (Talpha1) has immunomodulatory effects on T-cells, NK-cells and macrophages, but its action on dendritic cells (DCs), which are recognized as the sole professional antigen presenting cells (APCs) capable of priming naïve T-cells, is poorly understood. In this study, the effect of Talpha1 in vitro on murine bone marrow-derived DCs (BMDCs) maturation, differentiation, and function with or without tumor necrosis factor-alpha (TNF-alpha), which is one of the important inflammatory parameters, has been investigated. We have shown, through flow cytometry, ELISA and mixed leukocyte reaction (MLR), that Talpha1 promoted CD4-expressed DC differentiation and the expression of activation markers, but did not influence IL-12 production and T cell-stimulatory capacity of DCs in the absence of TNFalpha during BMDCs maturation. Furthermore, in the presence of TNF-alpha, Talpha1 has been shown not only to promote the expression of CD4 on MHC class II+ DCs and enhance the up-regulated levels of mature markers induced by TNF-alpha, but also to suppress the up-regulated IL-12 production. Particularly, thus effects seen were obvious at pharmacological Talpha1 concentrations. However, Talpha1 did not inhibit TNF-alpha-induced T-cell stimulating function of DCs. This is the first reported example of a direct Talpha1-DC interaction and suggests a mechanism by which Talpha1 may in part affect T-cell responses by acting at the DC level and it may play an important role in the modulation of the local inflammatory responses in vivo.

Thymosin alpha 1 activates dendritic cells for antifungal Th1 resistance through toll-like receptor signaling

Dendritic cells (DCs) show a remarkable functional plasticity in the recognition of Aspergillus fumigatus and orchestrate the antifungal immune resistance in the lungs. Here, we show that thymosin alpha 1, a naturally occurring thymic peptide, induces functional maturation and interleukin-12 production by fungus-pulsed DCs through the p38 mitogen-activated protein kinase/nuclear factor (NF)-kappaB-dependent pathway. This occurs by signaling through the myeloid differentiation factor 88-dependent pathway, involving distinct Toll-like receptors. In vivo, the synthetic peptide activates T-helper (Th) cell 1-dependent antifungal immunity, accelerates myeloid cell recovery, and protects highly susceptible mice that received hematopoietic transplants from aspergillosis. By revealing the unexpected activity of an old molecule, our finding provides the rationale for its therapeutic utility and qualify the synthetic peptide as a candidate adjuvant promoting the coordinated activation of the innate and adaptive Th immunity to the fungus.

Thymosin alpha-1 modulates excitatory synaptic transmission in cultured hippocampal neurons in rats

Thymosin alpha-1 (Talpha1) not only possesses immunoregulatory properties in periphery but also is expressed in the central nervous system (CNS) and affects the function of the CNS. To further elucidate the role of Talpha1 in the CNS, the whole-cell recording technique was used to observe the effect of Talpha1 on the spontaneous excitatory synaptic transmission in cultured rat hippocampal neurons. The results showed that acute treatment with Talpha1 significantly enhanced the frequency of AMPA-mediated spontaneous excitatory postsynaptic current (sEPSC) at the concentrations of 1 and 10 microg/ml and also enhanced the frequency of AMPA-mediated miniature excitatory postsynaptic current (mEPSC) at 10 microg/ml. However, the amplitude of both sEPSC and mEPSC were not changed by Talpha1. Those results suggested that Talpha1 involves in the regulation of excitatory synaptic transmission in hippocampal neurons, which contribute to its neurophysiological function in the CNS.