Biology subjects

Sukhikh, G. T.

Publications and source records attributed to Sukhikh, G. T..

4 recordsLinked to original sources

bioRxiv2025

Natural killers in pregnancy: servants of two masters

The absence of maternal immune rejection of a haploidentical fetus remains unexplained. We hypothesize that the presence of different HLA antigens on trophoblasts and maternal cells via killer cell immunoglobulin-like receptors (KIRs) provides two-way tuning (education) of decidual natural killer cells (dNK) with the appearance of allo- (HvG) and autoreactive (HvH) dNK. Disturbances in dNKHvG and dNKHvH representation may lead to abnormalities in placental development and pregnancy pathology. Our data show that recurrent pregnancy loss is not associated with specific HLA and KIR genotypes in mother and fetus, although the peculiarities of tuning involving KIR3DL2 may affect pregnancy outcome. Mathematical modeling shows the dependence of dNKHvG and dNKHvH representation on the probability of random KIR gene expression. The new description of NK cell involvement in the immune response in the placenta via two-way tuning is applicable to all cases where there are target cells with normal and different "guest" HLA expression (viral infections, tumors, etc.) Graphic abstract (Cover work) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/685990v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1e122a1org.highwire.dtl.DTLVardef@1a898caorg.highwire.dtl.DTLVardef@1c721b5org.highwire.dtl.DTLVardef@760a94_HPS_FORMAT_FIGEXP M_FIG C_FIG Image of fetus in utero in graphic abstract adapted from Servier Medical Art (https://smart.servier.com), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) HighlightsA hypothesis has been proposed according to which random expression of NK cell receptor genes in combination with two-way tuning (education) of NK cells by different affinity pairs of inhibitory killer cell immunoglobulin-like receptors (KIRs) and their ligands on decidual cells and trophoblasts leads to the presence of populations of maternal decidual NK cells with allo- and autoreactivity in the placenta. It has been shown that the features of the HLA and KIR genotypes of the mother and fetus are not the underlying cause of habitual miscarriage, although genetic features can affect the course of pregnancy. Model calculations of the representation of auto- and alloreactive maternal decidual NK cells show that the effectiveness of their participation in the structural and functional reorganization of the placenta should depend on the probability of KIR gene expression. The hypothesis of two-way tuning of NK cells in the presence of different target cells with normal and different "guest" HLA expressions is applicable to describe the involvement of the innate immune system in the response to pregnancy, viral infection, inflammation, wounds, tumors, and transplantation.

immunology↗

bioRxiv2025

Immune Antibodies Recognizing the Stem Region of SARS-CoV-2 Spike Protein: Molecular Modelling and In Vitro Study of Synthetic Peptides Presentation to the Antibodies

Antibodies to peptide 1147 (amino acids 1147-61) of the SARS-CoV-2 protein S are highly diagnostic. Peptide 1147, although located in a region that is partly spatially hidden in the intact protein, is not subject to mutations, suggesting therapeutic potential. The aim of this study was to elucidate the architecture of this region and the way in which it is presented to antibodies. As a model system, this peptide carrying a single lipophilic tail and the same peptide carrying a lipophilic tail at both ends (pseudocyclic) were incorporated into lipid membrane. Isolated anti-1147 antibodies interacted with it regardless of how the peptide was presented, be that freely exposed via the N-terminus, organized as a pseudocycle, or adsorbed on the surface. MDS showed that peptide 1147 is capable of closely approaching the membrane. Analysis of the surface properties of peptide 1147 in membrane-bound states and in available conformations in the full-sized S protein reveals interface for interaction with antibodies. Interestingly, the latter bears similarities to one published peptide-antibody complex. However, these antibodies, in spite of their high diagnostic significance, show no virus-neutralizing activity, indicating that peptide 1147 has no therapeutic value as a synthetic vaccine.

immunology↗

bioRxiv2021

Asymmetric depth-filtration - a versatile and scalable approach for isolation and purification of extracellular vesicles

A novel asymmetric depth filtration (DF) approach for isolation of extracellular vesicles (EVs) from biological fluids is presented, and its performance is compared with established methods. The developed workflow is simple, inexpensive, and relatively fast. Compared with ultracentrifugation and size-exclusion chromatography, the developed method isolates EVs with higher purity and yield. Only standard laboratory equipment is needed for its implementation, which makes it suitable for low-resource locations. The described implementation of the method is suitable for EV isolation from small biological samples in diagnostic and treatment guidance applications. Following the scale-up routes adopted in the biomanufacturing of therapeutics, which routinely rely on DF as one of the product purification steps, the developed method may be scaled up to harvesting therapeutic EVs from large volumes of growth medium.

bioengineering↗

bioRxiv2020

Mass Spectrometric detection of SARS-CoV-2 virus in scrapings of the epithelium of the nasopharynx of infected patients via Nucleocapsid N protein

Detection of viral RNA by PCR is currently the main diagnostic tool for COVID-19 [1]. The PCR-based test, however, shows limited sensitivity, especially at early and late stages of the disease development [2,3], and is relatively time consuming. Fast and reliable complementary methods for detecting the viral infection would be of help in the current pandemia conditions. Mass-spectrometry is one of such possibilities. We have developed a mass-spectrometry based method for the detection of the SARS CoV-2 virus in nasopharynx epithelial swabs, based on the detection of the viral nucleocapsid N protein. The N protein of the SARS-COV-2 virus, the most abundant protein in the virion, is the best candidate for mass-spectrometric detection of the infection, and MS-based detection of several peptides from the SARS-COoV-2 nucleoprotein has been reported earlier by the Sinz group [4]. Our approach shows confident identification of the N protein in patient samples even with the lowest viral loads and a much simpler preparation procedure. Our main protocol consists of virus inactivation by heating and adding of isopropanol, and tryptic digestion of the proteins sedimented from the swabs followed by MS analysis. A set of unique peptides, produced as a result of proteolysis of the nucleocapsid phosphoprotein of SARS-CoV-2, is detected. The obtained results can further be used to create fast parallel mass-spectrometric approaches for the detection of the virus in the nasopharyngeal mucosa, saliva, sputum and other physiological fluids.

molecular biology↗