Biology subjects

Richaud, M.

Publications and source records attributed to Richaud, M..

7 recordsLinked to original sources

bioRxiv2026

PVR and Nectin-2 blockade trigger macrophage anti-tumor functions, promote immune cell recruitment and prevent cervical tumor growth.

Despite vaccination, cervical tumors remain a health issue and require treatment improvement. In 2023, Pembrolizumab, an anti-PD-1 immune checkpoint blockade (ICB), was introduced in the case of advanced or metastatic cervical tumors. This treatment significantly increased progression free survival from 20% to 50%. However, some patients remain resistant to anti-PD-1 treatment, which calls for new targets. In our study, we highlighted poliovirus receptor (PVR) and Nectin-2 as potential ICB targets. Indeed, PVR and Nectin-2 are TIGIT ligands, an immunomodulatory checkpoint expressed by regulatory T cells or exhausted T cells. The binding of PVR or Nectin-2 to TIGIT maintains the immunosuppressive signal in the immune cells allowing tumor progression. Furthermore, we observed that PVR and Nectin-2 were highly expressed on tumor cells and tumor associated macrophages (TAMs) accross the different histological subsets of cervical tumors. Therefore, we hypothesized that using anti-PVR and anti-Nectin-2 anti-bodies would lift immunosuppression in cervical tumors. To that end, we used CyTOF to asses precise immunophenotyping of the targets ex vivo, high throughput confocal microscopy to assess phagocytosis, monocyte derived macrophages (MDM) coupled with 3D cell culture models to assess the impact of our treatment on MDM and TAM repolarization and tumor growth. We could demonstrate that our treatment repolarized macrophages towards an inflammatory profile and that this was followed by a reactivation of macrophage cytotoxic function such as phagocytosis. We also demonstrated that anti-PVR and Nectin-2 treatment allowed the control of tumor growth in 2D and 3D cell culture models. We could also develop a pre-clinical model of autologous cell culture from cervical cancer patients. Using the MIVO technology, which combine organotypic culture and fluidics, we could assess peripheral blood mononuclear cells recruitment towards tumor cells in the presence or absence of anti-PVR and anti-Nectin-2. In conclusion we could demonstrate that targeting macrophages via the PVR/Nectin-2 couple reactivates cervical tumor growth control and improves immune cell recruitment.

immunology↗

bioRxiv2026

Single Spectral Flow Cytometry Panel for Simultaneous Detection of Hematopoietic Stem, Progenitor, and Mature Lineages in Mouse Bone Marrow

Hematopoiesis occurs in the bone marrow of adult mammals and is supported by hematopoietic stem cells that sustain lifelong blood cell production. Pathological conditions can disrupt HSC differentiation, causing anaemia, immunodeficiency, and other cytopenias. Therefore, precise and simultaneous identification of hematopoietic populations from stem to mature cells is essential for understanding disease mechanisms and developing targeted therapies. In order to study these alterations, flow cytometry is generally a need-to-have monitoring technique. However, most cytometry panels are designed to thoroughly study a particular population, leaving out potential discoveries on other populations from the same microenvironment. Here we present the design of complex 19-marker spectral flow cytometry panel capable of simultaneously identifying HSPCs, erythroid, myeloid and lymphoid cells within a single murine BM sample. This integrated approach replaces multiple conventional panels and enables comprehensive mapping of hematopoietic differentiation from a single assay. Validation confirmed accurate detection of long-term and short-term HSCs, multipotent progenitors, common myeloid and lymphoid progenitors, and erythroid populations from proerythroblasts to reticulocytes. UMAP visualization captured the continuous trajectory of differentiation. We validated our method on aged and {beta}-thalassemic mouse models showing a clear detection of hematopoiesis and erythropoiesis alterations respectively. This panel provides a robust, flexible, and scalable platform suitable for both basic research and translational studies.

physiology↗

bioRxiv2025

Circulating DNA reveals nucleosome occupancy patterns that are associated with nucleosome-DNA affinity and are affected in cancer

The study of cell-free circulating DNA (cirDNA) fragments (fragmentomics) from liquid biopsies has received increasing attention. By constructing an atlas of these well-positioned nucleosomes, which we called WPNA, we found that their occupancy was associated with histone-DNA affinity, as evidenced by codon usage bias and differences in cirDNA fragment sizes. Moreover, WPNA nucleosome occupancy was different in healthy and cancer samples, thus allowing developing a high-performance machine learning approach for cancer detection (specificity and sensitivity >0.95 for seven cancer types). Cancer influenced WPNA nucleosome occupancy in a global manner, although distinct cancer types retained specific features. WPNA nucleosome occupancy at transcription factor binding sites revealed shared, pan-cancer regulation of transcriptional programs involved in hematopoietic cell differentiation and neutrophil biology, the main cirDNA sources. This work provides new fundamental insights into cirDNA and DNA sequence using cirDNA as a physical readout. It also bares translational significance by disclosing a new high-performance strategy for cancer detection from liquid biopsies.

genomics↗

bioRxiv2025

Single- and double-strand circulating DNA fragmentomics for enhanced cancer detection performance

In early detection of cancer, the use of circulating cell-free DNA (cirDNA) obtained from blood samples is notable for its minimally invasive nature. We have developed an algorithm designed to discriminate cancer patients and healthy individuals based on cirDNA fragment end motif analysis assisted by machine learning, using data obtained from shallow whole genome sequencing (a method we call EMA). We applied EMA to cirDNA from the plasma of patients with stage II-III breast cancer, stage I-III non-small cell lung cancer, and metastatic colorectal cancer (mCRC). CirDNA from 158 individuals was prepared following the conventional double-stranded DNA library preparation (DSP). Using 3 bp end motifs, each tumor type was detected with a sensitivity of 0.87-1.00, a specificity of 0.95, and an AUC above 0.96. The three selected cancer types could be differentiated with an accuracy (ACC) above 0.94. Multi-cancer detection by pooling samples from the three cancer types showed ACC, AUC and sensitivity of 0.98, 0.99 and 0.98, respectively. Comparisons with 4 and 2 bp end motifs were conducted, and our main observations were confirmed using an external public dataset (N=366). We also performed a single-stranded DNA library preparation (SSP) using mCRC patients and healthy control cirDNA, which allowed us to make the first ever end motif analysis in the literature which compares the use of DSP and SSP. As compared to EMAD (use of DSP), EMAS (use of SSP) produced a very significant difference in end motif frequency and an improved cancer detection performance (ACC, AUC and sensitivity of 0.97, 1.00 and 0.99, respectively). Furthermore, optimal performance was produced when the full-size range was used for EMAS, whereas when the dataset was restricted to fragments of 115 - 220 bp for EMAD. EMAS strong performance, coupled with its compatibility with cost-effective shallow cirDNA sequencing, positions this methodology as a potentially transformative tool in early cancer screening.

genomics↗

bioRxiv2025

TERT prevents obesity-induced metabolic disorders by promoting adipose stem cell expansion and differentiation

Obesity is linked to limited adipose tissue (AT) remodeling capacity, leading to hypertrophic adipocytes, senescence, and inflammation. We used a mouse model expressing mTert (p21+/Tert) from the Cdkn1a locus to investigate the role of mTERT in obesity-induced metabolic disorders. Conditional expression of mTERT reduces metabolic disorders associated with obesity. In AT, this is accompanied by a decrease in the number of senescent p21-positive cells, very short telomeres, and oxidative DNA damage. Single nucleus RNA-seq data reveal TERT expression attenuates senescence induced by HFD in particular in adipose stem and progenitor cells (ASPC). We show that ASPC expansion and differentiation are promoted in p21+/Tert obese mice, thereby reducing metabolic disorders. We further report that mTERT remodels the landscape of macrophages in AT of obese mice. Strikingly, inactivation of mTERT catalytic activity in p21+/Tert (p21+/TertCi) mice suppresses the promotion of adipocyte formation, but neither affects attenuation of senescence nor macrophage remodeling. These results highlight mTERTs canonical and non-canonical functions in reducing obesity-associated metabolic disorders. Conditional expression of TERT thus appears as a potential therapeutic option for obesity.

physiology↗

bioRxiv2023

A comparative ultrastructure study of the tardigrade Ramazzottius varieornatus in the hydrated state, after desiccation and during the process of rehydration.

Tardigrades can survive hostile environments such as desiccation by adopting a state of anhydrobiosis. Numerous tardigrade species have been described thus far, and recent genome and transcriptome analyses revealed that several distinct strategies were employed to cope with harsh environments depending on the evolutionary lineages. Detailed analyses at the cellular and subcellular levels are essential to complete these data. In this work, we analyzed a tardigrade species that can withstand rapid dehydration, Ramazzottius varieornatus. Surprisingly, we noted an absence of the anhydrobiotic-specific extracellular structure previously described for the Hypsibius exemplaris species. Both Ramazzottius varieornatus and Hypsibius exemplaris belong to the same evolutionary class of Eutardigrada. Nevertheless, our observations reveal discrepancies in the anhydrobiosis mechanisms between these two species. Interestingly, these discrepancies are correlated with their variations in dehydration resistance.

cell biology↗

bioRxiv2022

Vγ9Vδ2 T cells are potent inhibitors of SARS-CoV-2 replication and exert effector phenotypes in COVID-19 patients

V{gamma}9V{delta}2 T cells play a key role in the innate immune response to viral infections, including SARS-CoV-1 and 2, and are activated through butyrophilin (BTN)-3A. Here, the objectives were to: 1) characterize the effects of SARS-CoV-2 infection on the number, phenotype, and activation of V{gamma}9V{delta}2 T cells in infected patients, and 2) assess the effects of in vitro SARS-CoV-2 infection on the expression of BTN3A and its impact on the activation and response of V{gamma}9V{delta}2 T cells to an anti-BTN3A antibody. Blood V{gamma}9V{delta}2 T cells decreased in clinically mild SARS-CoV-2 infections compared to healthy volunteers (HV). This decrease was maintained up to 28 days and in the recovery period. Terminally differentiated V{gamma}9V{delta}2 T cells tend to be enriched on the day of diagnosis, 28 days after and during the recovery period compared to HV. Furthermore, these cells showed cytotoxic and inflammatory activities as shown by TNF, IFN{gamma} and CD107a/b increase following anti-BTN3A activation. Moreover, BTN3A upregulation and V{gamma}9V{delta}2 T cell infiltration were observed in a lung biopsy from a fatal SARS-CoV-2 infection, as compared to HV. In vitro, SARS-CoV-2 infection significantly increased BTN3A expression in macrophages and lung cell lines. The activation via BTN3A enhanced the anti-SARS-CoV-2 V{gamma}9V{delta}2 T cells cytotoxicity and IFN-{gamma} and TNF in SARS-CoV-2 infected patient. Increasing concentrations of anti-BTN3A were accompanied by an inhibition of viral replication. Altogether, these data suggest that V{gamma}9V{delta}2 T cells are important in the immune response against SARS-CoV-2 infection and that activation by an anti-BTN3A antibody may enhance their response. KEY POINTSO_LISARS-CoV-2 mediates upregulation of the key receptor of V{gamma}9V{delta}2 T cells BTN3A on lung tissues and cell lines as well as monocytes C_LIO_LIDuring SARS-CoV-2 infection, V{gamma}9V{delta}2 are differentiated and efficiently degranulate and secrete cytokines upon activation with BTN3A mAb C_LI

immunology↗