<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells."^^ . "Non-Hodgkin Lymphomas (NHL) represent one of the most common cancers worldwide. Among the most common forms of NHL are found Chronic Lymphocytic Leukemia (CLL), Diffuse Large B-cell Leukemia (DLBCL), and Follicular Lymphoma (FL). NHL is characterized by an expansion of myeloid cells with pro-tumoral properties, such as Tumor-associated macrophages (TAMs) or Myeloid-derived Suppressor Cells (MDSCs). However, little is known about the tumoral mechanisms leading to the expansion of those cell populations.\r\nIt was recently suggested that small extracellular vesicles (sEVs) secreted by tumor cells may contribute to the polarization of myeloid cells. Indeed, the treatment of myeloid cells with CLL- derived sEVs leads to an upregulation of PD-L1 at the surface of myeloid cells and an increased secretion of pro-inflammatory cytokines. Interestingly, CLL-derived sEVs were enriched in yRNA4, a small non-coding RNA. Treatment of myeloid cells with yRNA4 induces a similar response of myeloid cells to treatment with CLL-derived sEVs. This effect depends on the Toll-Like Receptor (TLR) 7, a member of the TLR family, and may be relevant for all small RNAs contained in sEVs. In this dissertation, I first investigated the involvement of other TLR in response to treatment with CLL-derived sEVs. I searched for candidate sEV-proteins that could drive the polarization of myeloid cells into a pro-tumoral phenotype. In parallel, I investigated the role played by yRNA4 in the polarization of myeloid cells.\r\nAs a first step, this dissertation presents a new approach for isolating and characterizing sEVs from human or murine lymphoid tissues. This approach combines differential centrifugation with size-exclusion chromatography, and turned out to be superior to previously used ultracentrifugation on a sucrose density cushion in terms of purity and yield of sEVs.\r\nA second step shows that the proteomic signature induced in myeloid cells following treatment with CLL-derived sEVs was broader than the signature induced in myeloid cells by yRNA4. The capacity of sEVs to induce a pro-inflammatory phenotype was tested using murine myeloid cells deficient for either TLR4, TLR7, or Myd88. Loss of TLR4 but not TLR7 nor Myd88 in myeloid cells leads to an impaired polarization of myeloid cells by tumor-derived sEVs. The activation of TLR2 and TLR4 following treatment with tumor-derived sEVs was also proven by using reporter cell assays.\r\nNext, I searched for potential TLR ligands present in NHL-derived sEVs. A proteomic comparison was performed with sEVs derived from the lymph nodes (LNs) of patients diagnosed with two subtypes of NHL, DLBCL and FL, as well as sEVs from patients with reactive lymph nodes as a non-tumoral control. Tumor LNs from DLBCL or FL patients were enriched in sEVs compared to reactive LNs. However, we observed a differential signature between the proteome of DLBCL-derived and FL-derived sEVs. Proteins unique to DLBCL- derived sEVs were primarily related to RNA processing, while proteins unique to FL-derived sEVs were more related to metabolism, among other pathways. Interestingly, sEVs from all\r\n4\r\nsources were found to be particularly enriched with Heat Shock Proteins (HSP), a family of proteins known to be endogenous ligands of TLRs.\r\nFinally, a knock-out of yRNA4 was induced using the CRISPR/Cas9 approach in the cell line HG-3, modeling CLL. The knock-out was validated using classical and real-time quantitative polymerase chain reactions and a Northern-blot assay. yRNA4 knock-out did not impair the capacity of the cells to secrete sEVs, nor their morphology, as investigated using transmission electron microscopy. However, sEVs derived from the yRNA4-deficient cell line showed a decreased capacity to induce the inflammatory phenotype in myeloid cells. The results raise the new hypothesis, that the reduced capacity of yRNA4-KO sEVs is due not only to the sole absence of yRNA4 but that the deletion of yRNA4 may impact the protein cargo loaded into the sEVs.\r\nAltogether, this dissertation allowed to decipher deeper the mechanisms by which tumor- derived sEVs influence the phenotype of myeloid cells. This mechanism was shown to be mediated by TLR2, TLR4 and TLR7; and the bioactive ligands include single-stranded RNAs such as yRNA4, as well as proteins, in particular the Heat-Shock Proteins. In the future, these findings may help finding new therapeutical targets to inhibit the modulation of the tumor microenvironment by tumor cells."^^ . "2023" . . . . . . . "Marie"^^ . "Bordas"^^ . "Marie Bordas"^^ . . . . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (PDF)"^^ . . . "Thesis_Bordas_2022.pdf"^^ . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Deciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells. (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #33182 \n\nDeciphering the role and the mechanism of B- cell Non-Hodgkin Lymphoma-derived small Extracellular Vesicles in modulating the phenotype of myeloid cells.\n\n" . "text/html" . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .