Biology subjects

Maillard, I.

Publications and source records attributed to Maillard, I..

8 recordsLinked to original sources

bioRxiv2026

The Notch signaling pathway is a master regulator of CD8+ T cell exhaustion and differentiation during chronic infection

During chronic infection, the persistence of antigen and inflammation leads to the differentiation of CD8+ T cells into an exhausted state characterised by expression of inhibitory receptors (IRs) and the progressive loss of T cell functions. Among the different subsets of exhausted CD8+ T (Tex) cells, Tex progenitors expressing SLAMF6 and the transcription factor TCF-1 (TCF-1+) give rise to Tex effector-like cells expressing CX3CR1 and Tex terminal cells expressing CD101. PD-1/PD-L1 blockade acts on TCF-1+ Tex progenitor cells and promotes their differentiation into Tex effector-like cells. The molecular events controlling CD8+ Tex cell differentiation are still poorly defined. As Notch signaling may be sustained during chronic infection by persistent TCR stimulation and inflammation, we tested whether Notch signaling influences CD8+ T cell exhaustion. Using mice lacking (N1N2{triangleup}/{triangleup}) or not (N1N2fl/fl) Notch1/2 expression only in mature CD8+ T cells, we showed that the absence of Notch signal causes severe CD8+ T cell exhaustion during chronic LCMV infection. N1N2{triangleup}/{triangleup} Tex cells express higher levels of IRs and are less functional when compared to their wild-typee counterpart. In the absence of N1N2 receptors, Tex progenitor and Tex terminal cells accumulate and Tex cells cannot be reinvigorated by PD-1/PD-L1 blockade. We further demonstrated that Notch signaling is essential to promote the differentiation of Tex progenitors into Tex effector-like cells. Moreover, Notch signals, provided by stromal cells expressing the ligands Delta-like 1 and 4, are necessary during all stages of the infection to prevent severe exhaustion. Single-nucleus RNA and ATAC multiome profiling identifies Notch signaling as a critical role on effector transcriptional programming in exhausted CD8 T cells. Loss of Notch signaling impairs transcriptional program associated with migration and perception of CD4+ T cell help. Together, these alterations drive the differentiation of Tex progenitor cells toward a terminally exhausted Tex fate.

immunology↗

bioRxiv2025

Notch2 signaling instructs viral and bacterial TLR responsiveness in B cells

Marginal zone (MZ) B cells are hyperresponsive to bacterial Toll-like Receptor (TLR) ligands. However, the full extent of TLR responsiveness for MZ B cells and the mechanisms regulating such responses are unclear. We report that Notch2 activation establishes MZ B cell responsiveness for the viral dsRNA receptor TLR3 and augments responses for the LPS receptor TLR4. Notch2 ligation accelerated Myc induction, mitosis, and plasma cell differentiation to LPS. Further, TLR3 expression in MZ B cells was Notch2 dependent, and ectopic Notch2 signaling was sufficient to promote robust TLR3 responsiveness dependent on the TIR-domain-containing adapter TRIF and the kinase BTK. TLR3 engagement in MZ B cells promoted proliferation, differentiation, and the secretion of IgG2b and IgG2c antibodies. Our results establish a novel role for Notch2 in establishing TLR3 and TLR4 responsiveness in B cells and suggest that MZ B cells play unappreciated roles in immunity against RNA viruses.

immunology↗

bioRxiv2024

The follicular lymphoma and chronic lymphocytic leukemia proliferative microenvironment at single-cell resolution

Adaptive immune responses occur lymph nodes (LNs) in a microenvironment established by resident stromal cells. LNs are also a site of proliferation of chronic lymphocytic leukemia (CLL), a B cell cancer that alters LN structure in a stereotypic manner. To deeply characterize reactive and CLL LNs, we developed a single-cell RNA sequencing pipeline. We find that proliferation of CLL cells in proliferation centers (PCs), a CLL-specific niche, begins with transient upregulation of MYC, subsequent downregulation of which may limit CLL growth. PCs contain a distinct fibroblast population expressing CCL19 while CLL cells express the CCL19 receptor CCR7, providing a recruitment mechanism for CLL cells to PCs. Using informatic, spatial, and in situ analyses to identify ligand-receptor pairs involving PC CLL cells and nearby immune and stromal cells, we observe that PCs are enriched for macrophages expressing BAFF, the integrin X{beta}2 heterodimer, and Galectin9, factors implicated in cell growth, adhesion, and immunosuppression. The most common predicted interactions in PCs involve CD74 and ligands such as MIF, and we find that CD74 blockade consistently inhibits CLL cell growth in culture. Our work highlights key features of the CLL proliferative niche and provides a roadmap for identifying vulnerabilities and new therapeutic strategies.

pathology↗

bioRxiv2024

Distinct components of nucleoside-modified messenger RNA vaccines cooperate to instruct efficient germinal center responses

Nucleoside-modified mRNA vaccines elicit protective antibodies through their ability to promote T follicular helper (Tfh) cells. The lipid nanoparticle (LNP) component of mRNA vaccines possesses inherent adjuvant activity. However, to what extent the nucleoside-modified mRNA can be sensed and contribute to Tfh cell responses remains largely undefined. Herein, we deconvoluted the signals induced by LNP and mRNA that instruct dendritic cells (DCs) to promote Tfh cell differentiation. We demonstrated that the nucleoside-modified mRNA drives the production of type I interferons that act on DCs to induce their maturation and the induction of Th1-biased Tfh responses. Conversely, LNP favors the acquisition of a Tfh cell-inducing program in DCs, a stronger Th2 polarization in Tfh cells, and allows for rapid mRNA translation by DCs within the draining lymph node. Our work unravels distinct adjuvant features of mRNA and LNP necessary for the induction of Tfh cells, with implications for vaccine design.

immunology↗

bioRxiv2023

A novel cryopreservation and biobanking strategy to study lymphoid tissue stromal cells in human disease

Non-hematopoietic lymph node stromal cells (LNSCs) regulate lymphocyte trafficking, survival, and function for key roles in host defense, autoimmunity, alloimmunity, and lymphoproliferative disorders. However, study of LNSCs in human diseases is complicated by a dependence on viable lymphoid tissues, which are most often excised prior to establishment of a specific diagnosis. Here, we demonstrate that cryopreservation can be used to bank lymphoid tissue for the study of LNSCs in human disease. Using human tonsils, lymphoid tissue fragments were cryopreserved for subsequent enzymatic digestion and recovery of viable non-hematopoietic cells. Flow cytometry and single-cell transcriptomics identified comparable proportions of LNSC cell types in fresh and cryopreserved tissue. Moreover, cryopreservation had little effect on transcriptional profiles, which showed significant overlap between tonsils and lymph nodes. The presence and spatial distribution of transcriptionally defined cell types was confirmed by in situ analyses. Our broadly applicable approach promises to greatly enable research into the roles of LNSC in human disease.

immunology↗

bioRxiv2022

Evolutionarily conserved effects of Notch signaling drive intestinal graft-versus-host disease in mice and non-human primates

Notch signaling promotes T-cell pathogenicity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) in mice, with a dominant role for the Delta-like ligand DLL4. To assess if Notchs effects are evolutionarily conserved and identify key mechanisms, we studied antibody-mediated DLL4 blockade in a non-human primate model similar to human allo-HCT. Short-term DLL4 blockade improved post-transplant survival with striking, durable protection from gastrointestinal GVHD, out of proportion to other disease sites. Unlike prior immunosuppressive strategies, anti-DLL4 interfered with a T-cell transcriptional program associated with intestinal infiltration. In cross-species investigations, Notch inhibition decreased surface abundance of the gut-homing integrin a4b7 in conventional T-cells via b1 competition for a4 binding, while preserving a4b7 in regulatory T-cells. Thereby, DLL4/Notch blockade decreased effector T-cell infiltration into the gut, with increased regulatory to conventional T-cell ratios early after allo-HCT. Our results identify a conserved, biologically unique and targetable role of DLL4/Notch signaling in GVHD. One Sentence SummaryNotch signaling promotes pathogenic effector T cell infiltration of the intestine during acute graft-versus-host disease.

immunology↗

bioRxiv2021

Differential impact of a dyskeratosis congenita mutation in TPP1 on mouse hematopoiesis and germline

Telomerase extends chromosome ends in somatic and germline stem cells to ensure continued proliferation. Mutations in genes critical for telomerase function result in telomeropathies such as dyskeratosis congenita (DC), frequently resulting in spontaneous bone marrow failure. While knockout of telomerase in mice has been instrumental in highlighting the importance of telomere length maintenance at an organismal level, it may not be representative of human telomeropathy mutations in vivo. A DC mutation in the shelterin protein TPP1 (K170{Delta}) that compromises telomerase recruitment to telomeres but leaves other functions of TPP1 and the integrity of the telomerase holoenzyme intact is a physiologically relevant tool to evaluate telomerase-dependent telomere length maintenance in mice. We used CRISPR-Cas9 to generate a mutant mouse knocked in for the equivalent of the TPP1 K170{Delta} mutation (TPP1 K82{Delta}) and investigated both its bone marrow and germline compartments in unprecedented detail. TPP1 K82{Delta} caused progressive telomere erosion with increasing generation number but did not induce steady-state hematopoietic defects. Strikingly, K82{Delta} caused mouse infertility, consistent with gross morphological defects in the testis and sperm, the appearance of either empty or severely disorganized seminiferous tubules, and a decrease in both spermatogonia and spermatocytes. It is intriguing that both TPP1 K82{Delta} mice and previously characterized telomerase knockout mice show no spontaneous bone marrow failure but rather succumb to a robust infertility phenotype at steady state. We speculate that telomere length maintenance contributes differently to the evolutionary fitness of humans and mice. Telomere length maintenance in the human bone marrow can ensure progression to reproductive age, while that in the mouse germline can help meet the elevated demand for sperm to produce multiple offspring.

cell biology↗

bioRxiv2021

Systemic inflammation recruits fast-acting anti-inflammatory innate myeloid progenitors from BM into lymphatics

Innate immune cellular effectors are actively consumed during systemic inflammation but the systemic traffic and the mechanisms that support their replenishment remain unknown. Here we demonstrate that acute systemic inflammation induces the emergent activation of a previously unrecognized system of rapid migration of granulocyte-macrophage progenitors and committed macrophage-dendritic progenitors, but not other progenitors or stem cells, from bone marrow (BM) to lymphatic capillaries. The progenitor traffic to the systemic lymphatic circulation is mediated by Ccl19/Ccr7 and is NF{kappa}B independent, Traf6/I{kappa}B-kinase/SNAP23 activation which is responsible for the secretion of pre-stored Ccl19 by a subpopulation of CD205+/CD172a+ conventional dendritic cells type 2 (cDC2) and upregulation of BM myeloid progenitor Ccr7 signaling. The consequence of this progenitor traffic is anti-inflammatory with promotion of early survival and initiation of replenishment of lymph node cDC.

immunology↗