Biomedical subjects

Eirini P Papapetrou

Publications and source records attributed to Eirini P Papapetrou.

4 recordsLinked to original sources

PubMed2026

Impaired Glycolysis Leads to Defective Efferocytosis and Impaired Plaque Resolution in Tet2 Clonal Hematopoiesis.

BACKGROUND: Clonal hematopoiesis (CH) arising from mutations in hematopoietic genes has been identified as an important risk factor for atherosclerotic cardiovascular disease. Despite the established role of some CH mutations in promoting atherosclerosis progression, their role in clinically relevant LDL (low-density lipoprotein) lowering-induced plaque remodeling or regression has not been extensively studied. METHODS: To assess the effects of TET2 (tet methylcytosine dioxygenase 2) CH on plaque resolution, we prepared control or chimeric Tet2+/- CH mice with conditional deletion of Tet2 in hematopoietic stem cells during LDL lowering-induced plaque remodeling. After establishing atherosclerosis by Western diet feeding for 12 weeks in Ldlr-/- mice, Tet2 was deleted by tamoxifen injection, and hypercholesterolemia was either normalized to simulate clinical lipid management, or mice were continued on the Western diet. RESULTS: Unlike control mice, Tet2+/- CH mice failed to significantly reduce necrotic core area or increase fibrous cap thickness and showed impaired macrophage efferocytosis during LDL lowering. Single-cell RNA sequencing and gene set enrichment analysis of aortic cell populations revealed that Tet2 deficient monocyte/macrophage populations were defective in glycolysis, phagocytosis, and actin polymerization. Tet2-deficient bone marrow-derived macrophages and Tet2+/- induced pluripotent stem cell-derived human macrophages showed defective ability to sustain continuing rounds of efferocytosis. Bone marrow-derived macrophages displayed reduced apoptotic cell binding and internalization and impaired activity of Wiskott-Aldrich syndrome protein and SCAR (suppressor of cyclic AMP receptor) homolog complex mediated actin polymerization. We linked these defects to reduced anaerobic glycolysis and lactate levels and rescued them by lactate supplementation or by treatment with the HIF-1α (hypoxia-inducible factor 1α) activator molidustat. Molidustat treatment reversed the defects in necrotic core and fibrous cap formation during LDL lowering-induced plaque remodeling in Tet2+/- CH mice. Reduced plasma lactate levels were also shown in TET2 clonal hematopoiesis of indeterminate potential carriers in the UK Biobank. CONCLUSIONS: Our data identify impaired efferocytosis and glycolysis-lactate-actin polymerization pathways in advanced atherosclerosis as potential therapeutic targets to induce proresolving restructuring of the plaque immune cells and to promote beneficial atherosclerosis remodeling in subjects with TET2 CH.

LDL lowering↗

PubMed2026

RAS Pathway Activation and Microenvironmental Adaptation as Hallmarks of Myeloid Sarcoma.

UNLABELLED: Myeloid sarcoma, an aggressive extramedullary subtype of acute myeloid leukemia (AML), occurs in approximately 20% of patients and remains strikingly understudied in large-scale genomic and multiomic investigations. The key drivers of its tumor evolution are largely unknown; timely detection in asymptomatic patients poses a clinical challenge, and effective treatment options are limited, as patients are often excluded from clinical trials, rendering it a largely neglected disease entity. In this study, we demonstrate that myeloid sarcoma evolves from medullary AML but exhibits distinct site-specific clonal evolution. This is supported by unique transcriptional signatures of myeloid sarcoma, reflecting adaptation to the extramedullary microenvironment. We establish a proof of concept that circulating tumor DNA (ctDNA) sequencing captures the molecular composition of myeloid sarcoma, offering a potential noninvasive approach for molecular profiling of extramedullary AML. Our findings highlight marked differences between medullary AML and myeloid sarcoma, including universal molecular evolution and RAS pathway activation as disease hallmarks. SIGNIFICANCE: We provide a comprehensive multiomic characterization of myeloid sarcoma, identifying key molecular pathways that contribute to its development, and suggest ctDNA as a noninvasive method of detection. We identify RAS pathway activation and transcriptional adaptation to the solid tissue microenvironment as cardinal features of myeloid sarcoma, suggesting novel therapeutic avenues.

Sarcoma, Myeloid↗

PubMed2025

TET2-mutant myeloid cells mitigate Alzheimer's disease progression via CNS infiltration and enhanced phagocytosis in mice.

Clonal hematopoiesis (CH) is associated with many age-related diseases, but its interaction with Alzheimer's disease (AD) remains unclear. Here, we show that TET2-mutant CH is associated with a 47% reduced risk of late-onset AD (LOAD) in the UK Biobank, whereas other drivers of CH do not confer protection. In a mouse model of AD, transplantation of Tet2-mutant bone marrow reduced cognitive decline and β-amyloid plaque formation, effects not observed with Dnmt3a-mutant marrow. Bone-marrow-derived microglia-like cells were detected at an increased rate in Tet2-mutant marrow recipients, and TET2-mutant human induced pluripotent stem cell (iPSC)-derived microglia were more phagocytic and hyperinflammatory than DNMT3A-mutant or wild-type microglia. Strikingly, single-cell RNA sequencing (scRNA-seq) revealed that macrophages and patrolling monocytes were increased in brains of mice transplanted with Tet2-mutant marrow in response to chemokine signaling. These studies reveal a TET2-specific protective effect of CH on AD pathogenesis mediated by peripheral myeloid cell infiltration.

Animals↗

PubMed2025

Deconvoluting clonal and cellular architecture in IDH-mutant acute myeloid leukemia.

Isocitrate dehydrogenase 1/2 (IDH) mutations are early initiating events in acute myeloid leukemia (AML). The complex clonal architecture and cellular heterogeneity in IDH-mutant AML underlies the heterogeneous clinical presentation and outcomes. Integrating single-cell genotyping and transcriptomics, we demonstrate a stem-like and inflammatory phenotype of IDH-mutant AML and identify clone-specific programs associated with NPM1, NRAS, and SRSF2 co-mutations. Furthermore, these clones had distinct responses to treatment with combination IDH inhibitors and chemotherapy, including elimination, reconstitution of myeloid differentiation, or retention within progenitor populations. At relapse after IDH inhibitor monotherapy, we identify upregulated stemness, inflammation, mitochondrial metabolism, and anti-apoptotic factors, as well as downregulated major histocompatibility complex (MHC) class II antigen presentation. At the pre-leukemic stage, we observe upregulation of IDH2-associated pathways, including inflammation. We deliver a detailed phenotyping of IDH-mutant AML and a framework for dissecting contributions of recurrently mutated genes in AML at diagnosis and following therapy, with implications for precision medicine.

Leukemia, Myeloid, Acute↗