Biology subjects

Villard, M.

Publications and source records attributed to Villard, M..

6 recordsLinked to original sources

bioRxiv2025

Differentiation of naive into memory-phenotype CD8+ T cells does not promote the breakdown of peripheral tolerance in irradiated mice

Lymphodepletion, which is currently used as adjuvant for adoptive cytotoxic T cell immunotherapy in cancer, promotes the breakdown of peripheral CD8+ T cell tolerance. Under lymphopenic conditions, naive T cells proliferate due to a greater availability of homeostatic cues. Proliferating CD8+ T cells acquire a phenotype and functionality that is similar to memory cells and are termed memory-like cells. Since memory cells are thought to have a lower activation threshold than naive cells, it has been proposed that differentiation of potentially autoreactive CD8+ T cells into memory-like cells could drive the breakdown of tolerance under lymphopenic conditions. Here we studied whether lymphopenia induced proliferation and differentiation are required to overcome CD8+ T cell cross-tolerance in irradiated mice. Surprisingly, we found that blocking homeostatic proliferation by IL-7 neutralization did not prevent self-reactivity. CD8+ T cells that remained in a naive state still became effectors upon antigen cross-presentation as efficiently as memory-like cells. Nonetheless, lymphopenia induced proliferation did enhance CD8+ T cell mediated self-reactivity at low T cell frequencies by increasing autoreactive T cell numbers. Thus, although homeostatic proliferation enhances CD8+ T cell anti-self responses, differentiation into memory-like cells is not essential for the breakdown of cross-tolerance after irradiation.

immunology↗

bioRxiv2025

Immunological and clinical markers of post-acute sequelae of COVID-19: Insights from mild and severe cases six months post-infection

Post-acute sequelae of COVID-19 (PASC) is a complex and multifaceted clinical challenge requiring to emphasize its underlying pathophysiological mechanisms. This study assessed hundreds of virological, serological, immunological, and tissue damage biomarkers in two patient cohorts who experienced mild (n=270) or severe (n=188) COVID-19, 6 to 9 months post-initial infection, and in which 40% and 57.4% of patients, respectively, developed PASC. Blood analysis showed that mains differences observed in humoral, viral, and biological biomarkers were associated with the initial COVID-19 severity, rather than being specifically linked to PASC. However, patients with PASC displayed altered CD4+ and CD8+ memory T-cell subsets, with higher cytokine-secreting cells and increased terminally differentiated CD45RA+ effector memory T cells (TEMRA). Elevated SARS-CoV-2-specific T cells responsive to nucleocapsid/membrane proteins with a TEMRA phenotype were also observed. A random forest model identified these features and initial symptom duration as top variables discriminating PASC, achieving over 80% classification accuracy. HighlightsO_LINine months post-initial SARS-CoV-2 infection, over 40% of patients developed PASC C_LIO_LIRegardless of PASC, the initial disease form influenced the main immune differences C_LIO_LIPASC led to altered memory T-cell subsets with elevated TEMRA phenotype C_LIO_LIPASC presence is associated with disease form, initial symptom count and duration C_LI

immunology↗

bioRxiv2024

Inflamed Natural Killer cells with adhesion defects are associated with a poor prognosis in Multiple Myeloma

The promising results obtained with immunotherapeutic approaches for multiple myeloma (MM) call for a better stratification of patients based on immune components. The most pressing being cytotoxic lymphocytes such as Natural Killer (NK) cells that are mandatory for MM surveillance and therapy. In this study, we performed a single cell RNA sequencing analysis of NK cells from 10 MM patients and 10 age/sex matched healthy donors (HD) that revealed important transcriptomic changes in NK cell landscape affecting both the bone marrow and peripheral blood compartment. The frequency of mature cytotoxic "CD56dim" NK cell subsets was reduced in MM patients at the advantage of late-stage NK cell subsets expressing NF{kappa}B and IFN-I inflammatory signatures. These NK cell subsets accumulating in MM patients were characterized by a low CD16 and CD226 expression and poor cytotoxic functions. MM CD16/CD226lo NK cells also had adhesion defects with reduced LFA-1 integrin activation and actin polymerization that may account for their limited effector functions in vitro. Finally, analysis of BM infiltrating NK cells in a retrospective cohort of 177 MM patients from the IFM 2009 trial demonstrated that a high frequency of NK cells and their low CD16 and CD226 expression were associated with a shorter overall survival. Thus, CD16/CD226lo NK cells with reduced effector functions accumulate along MM development and negatively impact patients clinical outcome. Given the growing interest in harnessing NK cells to treat myeloma, this improved knowledge around MM-associated NK cell dysfunction will stimulate the development of more efficient immunotherapeutic drugs against MM. Scientific category: Lymphoid Neoplasia; Immunobiology and Immunotherapy. KEY POINTSO_LIMM patients have increased CD16/CD226low NK cell subsets characterized by "inflammatory" signatures and reduced effector functions. C_LIO_LIThe frequency of CD16/CD226low NK cells correlate with MM patient clinical outcome C_LI

immunology↗

bioRxiv2020

Peripheral Natural Killer cells from chronic hepatitis B patients display molecular hallmarks of T cell exhaustion

A significant proportion of individuals infected by HBV develops chronic infection. Antiviral effectors such as Natural Killer (NK) cells have impaired functions in these patients, but the molecular mechanism responsible for this dysfunction remains poorly characterized. Here, we show that peripheral NK cells from chronic hepatitis B (CHB) patients have a defective capacity to produce IFN-{gamma}, MIP1-{beta} and TNF- but retain an intact killing capacity. This functional phenotype was associated with a decrease in the expression of NKp30 and CD16, combined with defects in IL-15 stimulation of the mTOR pathway. Transcriptome analysis of NK cells in CHB patients further revealed a strong enrichment for transcripts typically expressed in exhausted T cells suggesting that NK cell dysfunction and T cell exhaustion rely on common molecular mechanisms. In particular, the transcription factor thymocyte selection-associated HMG box protein (TOX) and several of its targets, including immune checkpoints, were over-expressed in NK cells of CHB patients. This T cell exhaustion signature was predicted to be dependent on the calcium (Ca2+)-associated transcription factor NFAT. In line with this, when stimulating the Ca2+-dependent pathway in isolation, we recapitulated the dysfunctional phenotype. Thus, deregulated Ca2+ signalling could be a central event in both T cell exhaustion and NK cell dysfunction that occur during chronic infections.

immunology↗

bioRxiv2019

Trivalent cocktail of de novo designed immunogens enables the robust induction and focusing of functional antibodies in vivo

De novo protein design has been successful in expanding the natural protein repertoire. However, most de novo proteins lack biological function, presenting a major methodological challenge. In vaccinology, the induction of precise antibody responses remains a cornerstone for next-generation vaccines. Here, we present a novel protein design algorithm, termed TopoBuilder, with which we engineered epitope-focused immunogens displaying complex structural motifs. Both in mice and non-human primates, cocktails of three de novo designed immunogens induced robust neutralizing responses against the respiratory syncytial virus. Furthermore, the immunogens refocused pre-existing antibody responses towards defined neutralization epitopes. Overall, our de novo design approach opens the possibility of targeting specific epitopes for vaccine and therapeutic antibody development, and more generally will be applicable to design de novo proteins displaying complex functional motifs.

bioengineering↗

bioRxiv2018

Rosetta FunFolDes - a general framework for the computational design of functional proteins

The robust computational design of functional proteins has the potential to deeply impact translational research and broaden our understanding of the determinants of protein function, nevertheless, it remains a challenge for state-of-the-art methodologies. Here, we present a computational design approach that couples conformational folding with sequence design to embed functional motifs into heterologous proteins. We performed extensive benchmarks, where the most unexpected finding was that the design of function into proteins may not necessarily reside in the global minimum of the energetic landscape, which could have important implications in the field. We have computationally designed and experimentally characterized a distant structural template and a de novo \"functionless\" fold, two prototypical design challenges, to present important viral epitopes. Overall, we present an accessible strategy to repurpose old protein folds for new functions, which may lead to important improvements on the computational design of functional proteins.

bioinformatics↗