Thymosin beta 4 regulation of actin in sepsis

Peptidome profiling of human, bovine, and donkey colostrum through label-free quantitative analysis reveals proteolysis of milk proteins

Proteins and peptides play vital roles in different biological processes in vivo. As a dynamic hydrolysis system, milk is rich in proteins and proteases and provides a constant supply of endogenous bioactive peptides to newborn mammals. Previous studies have primarily focused on researching bioactive peptides by adding exogenous enzymes to milk samples. However, such an approach overlooks the significance of endogenous peptides and parent proteins that naturally exist in milk. Herein, we analyzed and compared parent proteins and their releasing peptides in human colostrum (HC), bovine colostrum (BC), and donkey colostrum (DC). The predominant proteins and hydrolyzed peptides in the three types of milk were identified. Among them, peptides were found to possess common bioactivities, including ACE inhibitory, antioxidant, antibacterial and immunomodulatory properties in HC, BC, and DC. Furthermore, the biological functions of these parent proteins were clarified using bioinformatics. These insights offer a novel perspective on natural bioactive peptides and the potential utilization of specific parent proteins and peptides to develop infant formulae derived from diverse milk sources.

Ligustilide prevents thymic immune senescence by regulating Thymosin β15-dependent spatial distribution of thymic epithelial cells

BACKGROUND

Thymus is the most crucial organ connecting immunity and aging. The progressive senescence of thymic epithelial cells (TECs) leads to the involution of thymus under aging, chronic stress and other factors. Ligustilide (LIG) is a major active component of the anti-aging Chinese herbal medicine Angelica sinensis (Oliv.) Diels, but its role in preventing TEC-based thymic aging remains elusive.

PURPOSE

This study explored the protective role of Ligustilide in alleviating ADM (adriamycin) -induced thymic immune senescence and its underlying molecular mechanisms.

METHOD

The protective effect of Ligustilide on ADM-induced thymic atrophy was examined by mouse and organotypic models, and conformed by SA-β-gal staining in TECs. The abnormal spatial distribution of TECs in the senescent thymus was analyzed using H&E, immunofluorescence and flow cytometry. The possible mechanisms of Ligustilide in ADM-induced thymic aging were elucidated by qPCR, fluorescence labeling and Western blot. The mechanism of Ligustilide was subsequently validated through actin polymerization inhibitor, genetic engineering to regulate Thymosin β15 (Tβ15) and Tβ4 expression, molecular docking and β Thymosin-G-actin cross-linking assay.

RESULTS

At a 5 mg/kg dose, Ligustilide markedly ameliorated ADM-induced weight loss and limb grip weakness in mice. It also reversed thymic damage and restored positive selection impaired by ADM. In vitro, ADM disrupted thymic structure, reduced TECs number and hindered double negative (DN) T cell differentiation. Ligustilide counteracted these effects, promoted TEC proliferation and reticular differentiation, leading to an increase in CD4+ single positive (CD4SP) T cell proportion. Mechanistically, ADM diminished the microfilament quantity in immortalized TECs (iTECs), and lowered the expression of cytoskeletal marker proteins. Molecular docking and cross-linking assay revealed that Ligustilide inhibited the protein binding between G-actin and Tβ15 by inhibiting the formation of the Tβ15-G-actin complex, thus enhancing the microfilament assembly capacity in TECs.

CONCLUSION

This study, for the first time, reveals that Ligustilide can attenuate actin depolymerization, protects TECs from ADM-induced acute aging by inhibiting the binding of Tβ15 to G-actin, thereby improving thymic immune function. Moreover, it underscores the interesting role of Ligustilide in maintaining cytoskeletal assembly and network structure of TECs, offering a novel perspective for deeper understanding of anti thymic aging.

Functional proteomic profiling links deficient DNA clearance with increased mortality in individuals with severe COVID-19 pneumonia

The factors that influence survival during severe infection are unclear. Extracellular chromatin drives pathology, but the mechanisms enabling its accumulation remain elusive. Here, we show that in murine sepsis models, splenocyte death interferes with chromatin clearance through the release of the DNase I inhibitor actin. Actin-mediated inhibition was compensated by upregulation of DNase I or the actin scavenger gelsolin. Splenocyte death and neutrophil extracellular trap (NET) clearance deficiencies were prevalent in individuals with severe COVID-19 pneumonia or microbial sepsis. Activity tracing by plasma proteomic profiling uncovered an association between low NET clearance and increased COVID-19 pathology and mortality. Low NET clearance activity with comparable proteome associations was prevalent in healthy donors with low-grade inflammation, implicating defective chromatin clearance in the development of cardiovascular disease and linking COVID-19 susceptibility to pre-existing conditions. Hence, the combination of aberrant chromatin release with defects in protective clearance mechanisms lead to poor survival outcomes.

Promoting effect of Tmsb4x on the differentiation of peripheral blood mononuclear cells to dendritic cells during septicemia

BACKGROUND

Thymosin beta 4 × (Tmsb4x) has been highlighted as an important regulator in immune and inflammation responses. Promoted differentiation of mononuclear cells into dendritic cells (DCs) exert a beneficial effect on septicemia. Herein, we investigated the effects of Tmsb4x on the mononuclear cells to affect immune responses during septicemia.

METHODS

Initially, we isolated peripheral blood samples from healthy individuals and patients with septicemia for extraction of mononuclear cells, followed by Tmsb4x expression quantification. A cell model was constructed with mononuclear cells through lipopolysaccharide stimulation. The viability and apoptosis were evaluated in response to Tmsb4x silencing or re-expression. Additionally, the proportion of DCs was assessed by determining levels of inflammatory factors as well as by flow cytometric analysis. A mouse septicemia model was developed for in vivo validation.

RESULTS

Cell and animal models demonstrated decreased Tmsb4x expression in the setting of septicemia, which led to increased inflammatory response and reduced proportion of DCs, along with inhibited mononuclear cell viability and promoted apoptosis. However, restoration of Tmsb4x facilitated the differentiation of mononuclear cells into DCs.

CONCLUSION

To conclude, upregulated Tmsb4x promoted the generation of DCs from mononuclear cells, which contributed to deep understanding of underpinning mechanisms in the development of septicemia.

Utilizing Developmentally Essential Secreted Peptides Such as Thymosin Beta-4 to Remind the Adult Organs of Their Embryonic State-New Directions in Anti-Aging Regenerative Therapies

Our dream of defeating the processes of aging has occupied the curious and has challenged scientists globally for hundreds of years. The history is long, and sadly, the solution is still elusive. Our endeavors to reverse the magnitude of damaging cellular and molecular alterations resulted in only a few, yet significant advancements. Furthermore, as our lifespan increases, physicians are facing more mind-bending questions in their routine practice than ever before. Although the ultimate goal is to successfully treat the body as a whole, steps towards regenerating individual organs are even considered significant. As our initial approach to enhance the endogenous restorative capacity by delivering exogenous progenitor cells appears limited, we propose, utilizing small molecules critical during embryonic development may prove to be a powerful tool to increase regeneration and to reverse the processes associated with aging. In this review, we introduce Thymosin beta-4, a 43aa secreted peptide fulfilling our hopes and capable of numerous regenerative achievements via systemic administration in the heart. Observing the broad capacity of this small, secreted peptide, we believe it is not the only molecule which nature conceals to our benefit. Hence, the discovery and postnatal administration of developmentally relevant agents along with other approaches may result in reversing the aging process.

Ectopic Expression of Human Thymosin β4 Confers Resistance to Legionella pneumophila during Pulmonary and Systemic Infection in Mice

Thymosin beta-4 (Tβ4) is an actin-sequestering peptide that plays important roles in regeneration and remodeling of injured tissues. However, its function in a naturally occurring pathogenic bacterial infection model has remained elusive. We adopted Tβ4-overexpressing transgenic (Tg) mice to investigate the role of Tβ4 in acute pulmonary infection and systemic sepsis caused by Legionella pneumophila Upon infection, Tβ4-Tg mice demonstrated significantly lower bacterial loads in the lung, less hyaline membranes and necrotic abscess, with lower interstitial infiltration of neutrophils, CD4⁺, and CD8⁺ T cells. Bronchoalveolar lavage fluid of Tβ4-Tg mice possessed higher bactericidal activity against exogenously added L. pneumophila, suggesting that constitutive expression of Tβ4 could efficiently control L. pneumophila Furthermore, qPCR analysis of lung homogenates demonstrated significant reduction of interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α), which primarily originate from lung macrophages, in Tβ4-Tg mice after pulmonary infection. Upon L. pneumophila challenge of bone marrow-derived macrophages (BMDM) in vitro, secretion of IL-1β and TNF-α proteins was also reduced in Tβ4-Tg macrophages, without affecting their survival. The anti-inflammatory effects of BMDM in Tβ4-Tg mice on each cytokine were affected when triggering with tlr2, tlr4, tlr5, or tlr9 ligands, suggesting that anti-inflammatory effects of Tβ4 are likely mediated by the reduced activation of Toll-like receptors (TLR). Finally, Tβ4-Tg mice in a systemic sepsis model were protected from L. pneumophila-induced lethality compared to wild-type controls. Therefore, Tβ4 confers effective resistance against L. pneumophila via two pathways, a bactericidal and an anti-inflammatory pathway, which can be harnessed to treat acute pneumonia and septic conditions caused by L. pneumophila in humans.

Identification of the Diagnostic Signature of Sepsis Based on Bioinformatic Analysis of Gene Expression and Machine Learning

BACKGROUND

Sepsis is a life-threatening disease caused by the dysregulated host response to the infection and the major cause of death of patients in the intensive care unit (ICU).

OBJECTIVE

Early diagnosis of sepsis could significantly reduce in-hospital mortality. Though generated from infection, the development of sepsis follows its own psychological process and disciplines, alters with gender, health status and other factors. Hence, the analysis of mass data by bioinformatics tools and machine learning is a promising method for exploring early diagnosis.

METHODS

We collected miRNA and mRNA expression data of sepsis blood samples from Gene Expression Omnibus (GEO) and ArrayExpress databases, screened out differentially expressed genes (DEGs) by R software, predicted miRNA targets on TargetScanHuman and miRTarBase websites, conducted Gene Ontology (GO) term and KEGG pathway enrichment analysis based on overlapping DEGs. The STRING database and Cytoscape were used to build protein-protein interaction (PPI) network and predict hub genes. Then we constructed a Random Forest model by using the hub genes to assess sample type.

RESULTS

Bioinformatic analysis of GEO dataset revealed 46 overlapping DEGs in sepsis. The PPI network analysis identified five hub genes, SOCS3, KBTBD6, FBXL5, FEM1C and WSB1. Random Forest model based on these five hub genes was used to assess GSE95233 and GSE95233 datasets, and the area under the curve (AUC) of ROC was 0.900 and 0.7988, respectively, which confirmed the efficacy of this model.

CONCLUSION

The integrated analysis of gene expression in sepsis and the effective Random Forest model built in this study may provide promising diagnostic methods for sepsis.

Anti-Inflammatory Activity of β-thymosin Peptide Derived from Pacific Oyster (Crassostrea gigas) on NO and PGE₂ Production by Down-Regulating NF-κB in LPS-Induced RAW264.7 Macrophage Cells

β-thymosin is known for having 43 amino acids, being water-soluble, having a light molecular weight and ubiquitous polypeptide. The biological activities of β-thymosin are diverse and include the promotion of wound healing, reduction of inflammation, differentiation of T cells and inhibition of apoptosis. Our previous studies showed that oyster β-thymosin originated from the mantle of the Pacific oyster, Crassostrea gigas and had antimicrobial activity. In this study, we investigated the anti-inflammatory effects of oyster β-thymosin in lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells using human β-thymosin as a control. Oyster β-thymosin inhibited the nitric oxide (NO) production as much as human β-thymosin in LPS-induced RAW264.7 cells. It also showed that oyster β-thymosin suppressed the expression of prostaglandin E₂ (PGE₂), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, oyster β-thymosin reduced inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Oyster β-thymosin also suppressed the nuclear translocation of phosphorylated nuclear factor-κB (NF-κB) and degradation of inhibitory κB (IκB) in LPS-induced RAW264.7 cells. These results suggest that oyster β-thymosin, which is derived from the mantle of the Pacific oyster, has as much anti-inflammatory effects as human β-thymosin. Additionally, oyster β-thymosin suppressed NO production, PGE₂ production and inflammatory cytokines expression via NF-κB in LPS-induced RAW264.7 cells.