Biology subjects

Michonneau, D.

Publications and source records attributed to Michonneau, D..

3 recordsLinked to original sources

bioRxiv2025

Clonal memory of cell division in humans diverges between healthy haematopoiesis and acute myeloid leukaemia

Clonal memory, a cellular property inherited across at least two divisions, has emerged as a key driver of cell heterogeneity. To uncover its roles in human haematopoiesis, we developed high-resolution ex vivo tools that track both division and fate commitment of individual primary human haematopoietic stem and progenitor cells (HSPCs). We show that human HSPCs display a clonal memory of division, as cells descending from the same ancestor cell divide synchronously over multiple generations. In parallel, HSPCs inherit a clonal memory of fate commitment, independently of lineage identity. Both forms of clonal memory persist over at least two divisions, across different HSPC commitment stages and cell culture conditions. In contrast, malignant haematopoiesis exhibits lower synchronicity, revealing a disruption of clonal memory in leukemic cells. Epigenetic remodelling using a bromodomain inhibitor partially restores the clonal memory in division in leukemic HSPCs, highlighting the plasticity of this trait and its potential for therapeutic modulation. Our findings position clonal memory as a key regulator of human haematopoietic stem cell behaviour. Demonstrating that clonal memory can be modulated opens new avenues for tuning cell heterogeneity in healthy and pathological tissues.

cell biology↗

bioRxiv2025

Corticosteroid resistance is predetermined by early immune response dynamics at acute Graft Versus Host disease onset

Steroid-resistant acute graft versus host disease (SR-aGVHD) is the leading life-threatening complication following allogeneic hematopoietic stem cell transplantation. Novel therapeutics development is impeded by scares knowledge on biological pathways leading to steroid resistance at time of aGVHD diagnosis. To gain insight into our understanding on circulating immune cell subsets and functions at time of aGVHD, a single cell deep phenotyping and transcriptome analysis was performed on peripheral blood mononuclear cells from patients with aGVHD before steroid treatment or without aGVHD. We aimed at identifying biological patterns associated with steroid resistance at early onset of aGVHD. First, circulating immune cell subsets were associated with increased incidence of aGVHD, but not with steroid sensitivity. Then, pathway analysis and inferred ligand/receptor interactions revealed major functional divergences between steroid-sensitive (SS-) and SR-aGVHD, including enrichment of TNF activation in SR-GVHD, as well as TNF/TNFR, CCL3, CCL4 and IL18 signaling, and decreased interferon and {gamma} signaling pathways, suggesting that steroid resistance in an intrinsic property of immune cells before any treatment. To go deeper into the understanding of mechanisms at play during SR-aGVHD, we modeled immune trajectories within CD8+ T cells and evidenced specific direct transition, from an early naive state to a highly activated one. By contrast, SS-aGVHD involved specific gene signatures across multiple intermediate differentiation stages during cell-to-cell transitions. These findings provide evidence that steroid resistance is driven by intrinsic mechanisms already present at the onset of alloimmune response, that may serve as potential new therapeutic targets.

molecular biology↗

bioRxiv2024

A spatial atlas of human gastro-intestinal acute GVHD reveals epithelial and immune dynamics underlying disease pathophysiology

Acute graft-versus-host disease (aGVHD) is a significant complication of allogeneic hematopoietic stem cell transplantation (aHSCT), driven by alloreactive donor T cells in the gut. However, the roles of additional donor and host cells in this process are not fully understood. We conducted multiplexed imaging on 59 biopsies from patients with gastrointestinal GVHD and 10 healthy controls, revealing key pathological changes, including fibrosis, crypt alterations, loss of Paneth cells, accumulation of endocrine cells, and disrupted immune organization, particularly a reduction in IgA-secreting plasma cells. Interestingly, CD8T cells were enriched only in a subset of patients, while others exhibited non-canonical enrichments of macrophages and neutrophils. Post-transplantation time significantly influenced immune composition, with host cells dominating plasma and T cell compartments long after transplantation. This spatial atlas of healthy duodenum and GVHD uncovers non-canonical immune dynamics, offering insights into disease pathophysiology and potential clinical applications in GVHD and other inflammatory bowel diseases.

immunology↗