Immunomodulating effects of Vilon and its analogue in the culture of human and animal thymus cells

Peptides Regulating Proliferative Activity and Inflammatory Pathways in the Monocyte/Macrophage THP-1 Cell Line

This study evaluates the effects of five different peptides, the Epitalon^® tetrapeptide, the Vilon^® dipeptide, the Thymogen^® dipeptide, the Thymalin^® peptide complex, and the Chonluten^® tripeptide, as regulators of inflammatory and proliferative processes in the human monocytic THP-1, which is a human leukemia monocytic cell line capable of differentiating into macrophages by PMA in vitro. These peptides (Khavinson Peptides^®), characterized by Prof. Khavinson from 1973 onwards, were initially isolated from animal tissues and found to be organ specific. We tested the capacity of the five peptides to influence cell cultures in vitro by incubating THP-1 cells with peptides at certain concentrations known for being effective on recipient cells in culture. We found that all five peptides can modulate key proliferative patterns, increasing tyrosine phosphorylation of mitogen-activated cytoplasmic kinases. In addition, the Chonluten tripeptide, derived from bronchial epithelial cells, inhibited in vitro tumor necrosis factor (TNF) production of monocytes exposed to pro-inflammatory bacterial lipopolysaccharide (LPS). The low TNF release by monocytes is linked to a documented mechanism of TNF tolerance, promoting attenuation of inflammatory action. Therefore, all peptides inhibited the expression of TNF and pro-inflammatory IL-6 cytokine stimulated by LPS on terminally differentiated THP-1 cells. Lastly, by incubating the THP1 cells, treated with the peptides, on a layer of activated endothelial cells (HUVECs activated by LPS), we observed a reduction in cell adhesion, a typical pro-inflammatory mechanism. Overall, the results suggest that the Khavinson Peptides^® cooperate as natural inducers of TNF tolerance in monocyte, and act on macrophages as anti-inflammatory molecules during inflammatory and microbial-mediated activity.

The Use of Thymalin for Immunocorrection and Molecular Aspects of Biological Activity

The polypeptide drug thymalin is used for various diseases associated with immune dysfunction, viral and bacterial infections, regeneration normalization, immunodepression, and the depression of hematogenesis after chemical and radiotherapy. The molecular mechanism of the action of thymalin and its components, EW dipeptide (the drug thymogen), the dipeptide KE, and the tripeptide EDP, are analyzed. These short peptides regulate gene expression and the synthesis of heat-shock protein, cytokines, fibrinolysis, gerontogenes, and the differentiation, proliferation, apoptosis of cells. Thymalin and thymogen have practically no side effects and are used for various viral infections. These peptide drugs can likely be effective in the complex therapy for the coronavirus infection COVID-19.

Peptide Regulation of Cell Differentiation

Short peptides are molecules with small molecular weight, capable of penetrating the cell membrane and nuclear membrane for epigenetic regulation of gene expression, including the genes responsible for cell differentiation. The direction of cell differentiation induction depends on the peptide structure and concentration. AEDG and AEDP peptides induce differentiation of pluripotent cells in the epidermis, mesenchyme and nervous tissue. Peptides KE, AED, KED, AEDG and AAAAEKAAAAEKAAAAEK activate neural differentiation. Peptides AEDL and KEDW induce lung and pancreatic cell differentiation. Differentiation of immune cells is stimulated by KE, DS, (Nα-(γ-E)-E), K(Н-E-OH)-OH, AED, KED, EDA, and KEDG peptides. IRW, GRGDS and YCWSQYLCY peptides activate osteogenic differentiation of stem cells. KE, AEDL, and AEDG peptides also induce plant cells differentiation. Short peptides can take part in activation of the signaling pathways regulating expression of differentiation genes. They can interact with histones changing the availability of genes for transcription, regulate gene methylation and activate or inhibit their expression, as well as directly interact with the DNA. Research in the area of directed stem cell differentiation by peptide regulation is of special importance for developing innovative approaches to molecular medicine and cell therapy.

Systematic search for structural motifs of peptide binding to double-stranded DNA

A large variety of short biologically active peptides possesses antioxidant, antibacterial, antitumour, anti-ageing and anti-inflammatory activity, involved in the regulation of neuro-immuno-endocrine system functions, cell apoptosis, proliferation and differentiation. Therefore, the mechanisms of their biological activity are attracting increasing attention not only in modern molecular biology, biochemistry and biophysics, but also in pharmacology and medicine. In this work, we systematically analysed the ability of dipeptides (all possible combinations of the 20 standard amino acids) to bind all possible combinations of tetra-nucleotides in the central part of dsDNA in the classic B-form using molecular docking and molecular dynamics. The vast majority of the dipeptides were found to be unable to bind dsDNA. However, we were able to identify 57 low-energy dipeptide complexes with peptide-dsDNA possessing high selectivity for DNA binding. The analysis of the dsDNA complexes with dipeptides with free and blocked N- and C-terminus showed that selective peptide binding to dsDNA can increase dramatically with the peptide length.

Peptide KE in Human Proteome

Peptide KE exhibits immunoprotective, geroprotective, and oncostatic activities and stimulates functional activity of fibroblasts. The KE motif is present in amino acid sequences of some cytokines and peptide hormones functionally similar to KE peptide. However, the relationship between the presence of KE motif and protein functions on the scale of known human proteome has not yet received sufficient attention. The incidence of bioregulatory peptide KE in proteins of various functional groups constituting human proteome is studied. The study is carried out with the use of the available data on the human proteome (UniProt portal) comprising 20,417 proteins. The levels of KE motifs were maximum in cytoplasmic and nuclear proteins, while the presence of KE in the membrane and all other proteins was the minimum. KE peptide molecules released from nuclear proteins during limited proteolysis can bind to DNA and regulate gene expression.

Establishment and characterization of a new triple-negative canine mammary cancer cell line

Canine mammary tumor (CMT) has always been an ideal animal model for human breast cancer (HBC) research, however, there is a lack of various established CMT cell lines corresponding to HBC cell lines. This study was designed to establish a new type of CMT cell line. The primary tumor, CMT-7364, was identified as the intraductal papillary carcinoma, and showed negative immunoreactivity to estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor-2 (HER-2) by immunohistochemistry (IHC) analysis. The CMT-7364 cell line from this primary tumor also shows a negative immunoreactivity to ER, PR, and HER-2, and was negative to epithelial cell markers and positive to mesenchymal cell markers by immunocytochemistry (ICC) analysis. This cell line, which has been stably cultured for more than 115 passages, and was characterized by epithelial origin with the expression of the epithelial antigen by ICC analysis and invasion ability by transwell analysis. In vivo, tumor mass and metastases in the lung were found after inoculating the CMT-7364 cells in the nude mice model, and the immune-complete mice model respectively. The tissues from the xenograft tumor were also negative to ER, PR, and HER-2 by IHC analysis. Thus, a novel triple negative canine mammary cancer cell line, CMT-7364, was successfully established, which could be used as a promising model for the research of immunotherapy and Epithelial-Mesenchymal Transition (EMT) mechanism of the triple-negative breast cancer both in canine and human.

Dipeptides Increase Functional Activity of Human Skin Fibroblasts

We analyzed the effect of dipeptide Glu-Trp and isovaleroyl-Glu-Trp in concentrations of 0.2, 2 and 20 μg/ml and Actovegin preparation on functional activity of human skin fibroblasts. Dipeptides, especially Glu-Trp, produce a stimulating effect on human skin fibroblasts and their effect is equivalent to that of Actovegin. Dipeptides stimulate cell renewal processes by activating synthesis of Ki-67 and reducing expression of caspase-9 and enhance antioxidant function of the cells by stimulating the expression of Hsp-90 and inducible NO-synthase. These findings suggest that dipeptides are promising candidates for preparations stimulating reparative processes.