A concept of natural genome reconstruction.Part 2. Effect of extracellular double-stranded DNA fragments on hematopoietic stem cellsRuzanova, Oshikhmina, Proskurina
et alVavilovskii Zhurnal Genet Selektsii (2024) 28 (8), 993-1007
Abstract: In this part of the study, the first component of the concept of "natural genome reconstruction" is being proven. It was shown with mouse and human model organisms that CD34+ hematopoietic bone marrow progenitors take up fragments of extracellular double-stranded DNA through a natural mechanism. It is known that the process of internalization of extracellular DNA fragments involves glycocalyx structures, which include glycoproteins/protein glycans, glycosylphosphatidylinositol-anchored proteins and scavenger receptors. The bioinformatic analysis conducted indicates that the main surface marker proteins of hematopoietic stem cells belong to the indicated groups of factors and contain specific DNA binding sites, including a heparin-binding domain and clusters of positively charged amino acid residues. A direct interaction of CD34 and CD84 (SLAMF5) glycoproteins, markers of hematopoietic stem cells, with double-stranded DNA fragments was demonstrated using an electrophoretic mobility shift assay system. In cells negative for CD34, which also internalize fragments, concatemerization of the fragments delivered into the cell occurs. In this case, up to five oligonucleotide monomers containing 9 telomeric TTAGGG repeats are stitched together into one structure. Extracellular fragments delivered to hematopoietic stem cells initiate division of the original hematopoietic stem cell in such a way that one of the daughter cells becomes committed to terminal differentiation, and the second retains its low-differentiated status. After treatment of bone marrow cells with hDNAgr, the number of CD34+ cells in the colonies increases to 3 % (humans as the model organism). At the same time, treatment with hDNAgr induces proliferation of blood stem cells and their immediate descendants and stimulates colony formation (mouse, rat and humans as the model organisms). Most often, the granulocyte-macrophage lineage of hematopoiesis is activated as a result of processing extracellular double-stranded DNA. The commitment process is manifested by the appearance and repair of pangenomic single-strand breaks. The transition time in the direction of differentiation (the time it takes for pangenomic single-strand breaks to appear and to be repaired) is about 7 days. It is assumed that at the moment of initiation of pangenomic single-strand breaks, a "recombinogenic situation" ensues in the cell and molecular repair and recombination mechanisms are activated. In all experiments with individual molecules, recombinant human angiogenin was used as a comparison factor. In all other experiments, one of the experimental groups consisted of hematopoietic stem cells treated with angiogenin.Copyright © AUTHORS.
Targeting CD84 protein on myeloid-derived suppressor cells as a novel immunotherapy in solid tumorsMobini, Chizari, Rismani
et alComput Methods Programs Biomed (2025) 261, 108607
Abstract: Myeloid-derived suppressor cells (MDSCs) are a crucial and diverse group of cells found in the tumor microenvironment (TME) that facilitate progression, invasion, and metastasis within solid tumors. CD84, a homophilic adhesion molecule expressed on MDSCs, plays a critical role in their accumulation and function within the TME. This study aims to investigate the protein-protein interactions of CD84 using molecular dynamics simulations and to explore potential therapeutic strategies targeting these interactions.Through computational techniques, we generated highly potent mutated CD84 mini-proteins and peptides as antagonists with significantly higher affinity for CD84 to mimic the key features of the IgV-like domain of the protein. Additionally, we engineered an antibody capable of blocking CD84. Binding affinities were assessed using dissociation constant (Kd) calculations.Data analysis shows that the Kd values for the designed peptides ranged from 10 to 100 times stronger than those of the natural CD84 interactions, indicating efficient inhibition of CD84 interactions. Additionally, mutagenesis of the Ig-like V domain of CD84 resulted in variants with improved binding stability, with a Gibbs free energy change (ΔΔG) indicating enhanced interaction potential.This study provides insights into CD84 interactions and their implications for immunotherapy targeting MDSCs in solid tumors. However, experimental validation is necessary to confirm the findings of this study and evaluate peptide selectivity as potential molecular therapeutics.Copyright © 2025. Published by Elsevier B.V.
Depletion of myeloid-derived suppressor cells sensitizes murine multiple myeloma to PD-1 checkpoint inhibitorsXiong, Xiao, Duan
et alJ Immunother Cancer (2025) 13 (1)
Abstract: Cancer immunotherapy using immune checkpoint blockade (ICB) has revolutionized cancer treatment. However, patients with multiple myeloma (MM) rarely respond to ICB. Accumulating evidence indicates that the complicated tumor microenvironment (TME) significantly impacts the efficacy of ICB therapy. Therefore, investigating how TME components in MM influence ICB treatment is urgent.We employed two well-established murine myeloma models, 5TGM1 and Vk*MYC, by intravenously injecting 5TGM1 or Vk*MYC cells into mice, respectively, to determine ICB therapeutic efficacy in MM. Total mouse IgG or Ig2b ELISA or QuickGel split beta SPE kits and in vivo bioluminescent imaging were used to monitor MM tumor burden. Cytometry by time of flight (CyTOF) was used to quantify MM TME components. T cell proliferation and function were detected using flow cytometry. Peptide-Fc fusion proteins were used to deplete myeloid-derived suppressor cells (MDSCs). MMDTR, Foxp3DTR, CD4 KO and CD8 KO mice were used to elucidate the underlying mechanisms. Gene expression levels in human MM were analyzed using Gene Expression Omnibus public datasets.We found that programmed cell death protein 1 (PD-1) antibody treatment had a therapeutic effect in 5TGM1 mice; it was ineffective in Vk*MYC mice. CyTOF indicated that the bone marrow (BM) of both models was inflamed, suggesting that immune suppressive cells might be inhibiting the reactivation of T cells in the BM. We observed higher numbers of MDSCs, regulatory T (Treg) cells, and tumor-associated macrophage (TAMs) in myeloma BM compared with that of tumor-free mice. Specifically, depleting MDSCs, but not Treg cells or TAMs, sensitized Vk*MYC mice and enhanced the response of 5TGM1 mice to PD-1 ICB, which was dependent on CD8+ but not CD4+ T cells. MDSCs, especially M-MDSCs and CD84+ MDSCs, significantly inhibited the activation and cytotoxic cytokine production of CD8+ T cells in vitro. Moreover, database profiling of patient BM revealed a negative correlation between MDSCs signature genes and cytotoxic CD8+ T cell signature genes, with post-maintenance patients with myeloma displaying a higher ratio of cytotoxic CD8+ T cell to MDSCs signature genes compared with pretreated patients.Our study highlights the potential of MDSCs depletion in enhancing the sensitivity of patients with myeloma to PD-1 ICB therapy.© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.
Ischemia/reperfusion injury in acute human and experimental stroke: focus on thrombo-inflammatory mechanisms and treatmentsStoll, Nieswandt, Schuhmann
Neurol Res Pract (2024) 6 (1), 57
Abstract: Despite high recanalization rates of > 90% after endovascular thrombectomy (EVT) clinical outcome in around 50% of treated acute ischemic stroke (AIS) patients is still poor. Novel treatments augmenting the beneficial effects of recanalization are eagerly awaited, but this requires mechanistic insights to explain and overcome futile recanalization.At least two mechanisms contribute to futile recanalization after cerebral large vessel occlusions (LVO): (i) the no reflow phenomenon as evidenced by randomly distributed areas without return of blood flow despite reperfusion of large cerebral arteries, and (ii) ischemia/reperfusion (I/R) injury, the paradoxically harmful aspect of blood flow return in transiently ischemic organs. There is accumulating evidence from experimental stroke models that platelets and leukocytes interact and partly obstruct the microvasculature under LVO, and that platelet-driven inflammation (designated thrombo-inflammation) extends into the reperfusion phase and causes I/R injury. Blocking of platelet glycoprotein receptors (GP) Ib and GPVI ameliorated inflammation and I/R injury providing novel therapeutic options. Recently, MRI studies confirmed a significant, up to 40% infarct expansion after recanalization in AIS thereby proofing the existance of I/R injury in the human brain. Moreover, analysis of minute samples of ischemic arterial blood aspirated directly from the pial cerebral collateral circulation under LVO during the routine EVT procedure confirmed platelet activation and platelet-driven leukocyte accumulation in AIS and, thus, the principal transferability of pathophysiological stroke mechanisms from rodents to man. Two recently published clinical phase 1b/2a trials targeted (thrombo-) inflammation in AIS: The ACTIMIS trial targeting platelet GPVI by glenzocimab provided encouraging safety signals in AIS similar to the ApTOLL trial targeting toll-like receptor 4, a central receptor guiding stroke-induced innate immunity. However, both studies were not powered to show clinical efficacy.The fact that the significance of I/R injury in AIS has recently been formally established and given the decisive role of platelet-leukocytes interactions herein, new avenues for adjunct stroke treatments emerge. Adjusted study designs to increase the probability of success are of outmost importance and we look forward from what can be learned from the so far unpublished, presumbably negative ACTISAFE and MOST trials.© 2024. The Author(s).
膜杰作
Star Staining
