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Atherosclerosis Jun 2024Dysregulated cholesterol metabolism is a hallmark of atherosclerotic cardiovascular diseases, yet our understanding of how endogenous cholesterol synthesis affects...
BACKGROUND AND AIMS
Dysregulated cholesterol metabolism is a hallmark of atherosclerotic cardiovascular diseases, yet our understanding of how endogenous cholesterol synthesis affects atherosclerosis is not clear. The energy sensor AMP-activated protein kinase (AMPK) phosphorylates and inhibits the rate-limiting enzyme in the mevalonate pathway HMG-CoA reductase (HMGCR). Recent work demonstrated that when AMPK-HMGCR signaling was compromised in an Apoe model of hypercholesterolemia, atherosclerosis was exacerbated due to elevated hematopoietic stem and progenitor cell mobilization and myelopoiesis. We sought to validate the significance of the AMPK-HMGCR signaling axis in atherosclerosis using a non-germline hypercholesterolemia model with functional ApoE.
METHODS
Male and female HMGCR S871A knock-in (KI) mice and wild-type (WT) littermate controls were made atherosclerotic by intravenous injection of a gain-of-function Pcsk9-adeno-associated virus followed by high-fat and high-cholesterol atherogenic western diet feeding for 16 weeks.
RESULTS
AMPK activation suppressed endogenous cholesterol synthesis in primary bone marrow-derived macrophages from WT but not HMGCR KI mice, without changing other parameters of cholesterol regulation. Atherosclerotic plaque area was unchanged between WT and HMGCR KI mice, independent of sex. Correspondingly, there were no phenotypic differences observed in hematopoietic progenitors or differentiated immune cells in the bone marrow, blood, or spleen, and no significant changes in systemic markers of inflammation. When lethally irradiated female mice were transplanted with KI bone marrow, there was similar plaque content relative to WT.
CONCLUSIONS
Given previous work, our study demonstrates the importance of preclinical atherosclerosis model comparison and brings into question the importance of AMPK-mediated control of cholesterol synthesis in atherosclerosis.
PubMed: 38880706
DOI: 10.1016/j.atherosclerosis.2024.117608 -
Critical Reviews in Oncology/hematology Jun 2024
Corrigendum to: The hematopoietic microenvironment of the fetal liver and transient abnormal myelopoiesis associated with Down syndrome: A review [Crit. Rev. Oncol. / Hematol., 199 (2024) 104382].
PubMed: 38880662
DOI: 10.1016/j.critrevonc.2024.104409 -
The Journal of Allergy and Clinical... Jun 2024
PubMed: 38866209
DOI: 10.1016/j.jaci.2024.06.005 -
BioRxiv : the Preprint Server For... May 2024Bone fracture is one of the most globally prevalent injuries, with an estimated 189 million bone fractures occurring annually. Delayed union or nonunion occurs in up to...
BACKGROUND
Bone fracture is one of the most globally prevalent injuries, with an estimated 189 million bone fractures occurring annually. Delayed union or nonunion occurs in up to 15% of fractures and involves the interruption or complete failure of bone continuity following fracture. Preclinical testing is essential to support the translation of novel strategies to promote improved fracture repair treatment, but there is a paucity of small animal models that recapitulate clinical attributes associated with delayed fracture healing. This study explores whether the (Z24 ) knockout mouse model of Hutchinson-Gilford progeria syndrome presents with delayed fracture healing. Leveraging the previously characterized Z24 phenotype of genomic instability, epigenetic changes, and fragility, we hypothesize that these underlying alterations will lead to significantly delayed fracture healing relative to age-matched wild type (WT) controls.
METHODS
WT and Z24 mice received intramedullary fixed tibia fractures at ∼12 weeks of age. Mice were sacrificed throughout the time course of repair for the collection of organs that would provide information regarding the local (fracture callus, bone marrow, inguinal lymph nodes) versus peripheral (peripheral blood, contralateral tibia, abdominal organs) tissue microenvironments. Analyses of these specimens include histomorphometry, μCT, mechanical strength testing, protein quantification, gene expression analysis, flow cytometry for cellular senescence, and immunophenotyping.
RESULTS
Z24 mice demonstrated a significantly delayed rate of healing compared to WT mice with consistently smaller fracture calli containing higher proportion of cartilage and less bone after injury. Cellular senescence and pro-inflammatory cytokines were elevated in the Z24 mice before and after fracture. These mice further presented with a dysregulated immune system, exhibiting generally decreased lymphopoiesis and increased myelopoiesis locally in the bone marrow, with more naïve and less memory T cell but greater myeloid activation systemically in the peripheral blood. Surprisingly, the ipsilateral lymph nodes had increased T cell activation and other pro-inflammatory NK and myeloid cells, suggesting that elevated myeloid abundance and activation contributes to an injury-specific hyperactivation of T cells.
CONCLUSION
Taken together, these data establish the Z24 progeria mouse as a model of delayed fracture healing that exhibits decreased bone in the fracture callus, with weaker overall bone quality, immune dysregulation, and increased cellular senescence. Based on this mechanism for delayed healing, we propose this Z24 progeria mouse model could be useful in testing novel therapeutics that could address delayed healing.
THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE
This study employs a novel animal model for delayed fracture healing that researchers can use to screen fracture healing therapeutics to address the globally prevalent issue of aberrant fracture healing.
PubMed: 38854043
DOI: 10.1101/2024.05.29.596277 -
Cellular & Molecular Immunology Jun 2024Acute systemic inflammation critically alters the function of the immune system, often promoting myelopoiesis at the expense of lymphopoiesis. In the thymus, systemic...
Acute systemic inflammation critically alters the function of the immune system, often promoting myelopoiesis at the expense of lymphopoiesis. In the thymus, systemic inflammation results in acute thymic atrophy and, consequently, impaired T-lymphopoiesis. The mechanism by which systemic inflammation impacts the thymus beyond suppressing T-cell development is still unclear. Here, we describe how the synergism between TL1A and IL-18 suppresses T-lymphopoiesis to promote thymic myelopoiesis. The protein levels of these two cytokines were elevated in the thymus during viral-induced thymus atrophy infection with murine cytomegalovirus (MCMV) or pneumonia virus of mice (PVM). In vivo administration of TL1A and IL-18 induced acute thymic atrophy, while thymic neutrophils expanded. Fate mapping with Ms4a3-Cre mice demonstrated that thymic neutrophils emerge from thymic granulocyte-monocyte progenitors (GMPs), while Rag1-Cre fate mapping revealed a common developmental path with lymphocytes. These effects could be modeled ex vivo using neonatal thymic organ cultures (NTOCs), where TL1A and IL-18 synergistically enhanced neutrophil production and egress. NOTCH blockade by the LY411575 inhibitor increased the number of neutrophils in the culture, indicating that NOTCH restricted steady-state thymic granulopoiesis. To promote myelopoiesis, TL1A, and IL-18 synergistically increased GM-CSF levels in the NTOC, which was mainly produced by thymic ILC1s. In support, TL1A- and IL-18-induced granulopoiesis was completely prevented in NTOCs derived from Csf2rb mice and by GM-CSFR antibody blockade, revealing that GM-CSF is the essential factor driving thymic granulopoiesis. Taken together, our findings reveal that TL1A and IL-18 synergism induce acute thymus atrophy while promoting extramedullary thymic granulopoiesis in a NOTCH and GM-CSF-controlled manner.
PubMed: 38839915
DOI: 10.1038/s41423-024-01180-8 -
Science Advances Jun 2024Nucleoporins, the components of nuclear pore complexes (NPCs), can play cell type- and tissue-specific functions. Yet, the physiological roles and mechanisms of action...
Nucleoporins, the components of nuclear pore complexes (NPCs), can play cell type- and tissue-specific functions. Yet, the physiological roles and mechanisms of action for most NPC components have not yet been established. We report that Nup358, a nucleoporin linked to several myeloid disorders, is required for the developmental progression of early myeloid progenitors. We found that Nup358 ablation in mice results in the loss of myeloid-committed progenitors and mature myeloid cells and the accumulation of myeloid-primed multipotent progenitors (MPPs) in bone marrow. Accumulated MPPs in Nup358 knockout mice are greatly restricted to megakaryocyte/erythrocyte-biased MPP2, which fail to progress into committed myeloid progenitors. Mechanistically, we found that Nup358 is required for histone deacetylase 3 (HDAC3) nuclear import and function in MPP2 cells and established that this nucleoporin regulates HDAC3 nuclear translocation in a SUMOylation-independent manner. Our study identifies a critical function for Nup358 in myeloid-primed MPP2 differentiation and uncovers an unexpected role for NPCs in the early steps of myelopoiesis.
Topics: Animals; Histone Deacetylases; Nuclear Pore Complex Proteins; Mice; Cell Differentiation; Mice, Knockout; Molecular Chaperones; Myeloid Progenitor Cells; Active Transport, Cell Nucleus; Cell Nucleus; Multipotent Stem Cells; Myeloid Cells; Sumoylation; Myelopoiesis
PubMed: 38838144
DOI: 10.1126/sciadv.adn8963 -
BioRxiv : the Preprint Server For... May 2024Trisomy 21 (T21), or Down syndrome (DS), is associated with baseline macrocytic erythrocytosis, thrombocytopenia, and neutrophilia, and transient abnormal myelopoiesis...
Trisomy 21 (T21), or Down syndrome (DS), is associated with baseline macrocytic erythrocytosis, thrombocytopenia, and neutrophilia, and transient abnormal myelopoiesis (TAM) and myeloid leukemia of DS (ML-DS). TAM and ML-DS blasts both arise from an aberrant megakaryocyte-erythroid progenitor and exclusively express GATA1s, the truncated isoform of , while germline mutations in a non-T21 context lead to congenital cytopenias without a leukemic predisposition. This suggests that T21 and GATA1s perturb hematopoiesis independently and synergistically, but this interaction has been challenging to study in part due to limited human cell and murine models. To dissect the developmental impacts of GATA1s on hematopoiesis in euploid and T21 cells, we performed a single-cell RNA-sequencing timecourse on hematopoietic progenitors (HPCs) derived from isogenic human induced pluripotent stem cells differing only by chromosome 21 and/or status. These HPCs were surprisingly heterogeneous and displayed spontaneous lineage skew apparently dictated by T21 and/or GATA1s. In euploid cells, GATA1s nearly eliminated erythropoiesis, impaired MK maturation, and promoted an immature myelopoiesis, while in T21 cells, GATA1s appeared to compete with the enhanced erythropoiesis and suppressed megakaryopoiesis driven by T21 to give rise to immature erythrocytes, MKs, and myeloid cells. T21 and GATA1s both disrupted temporal regulation of lineage-specific transcriptional programs and specifically perturbed cell cycle genes. These findings in an isogenic system can thus be attributed specifically to T21 and GATA1s and suggest that these genetic changes together enhance HPC proliferation at the expense of maturation, consistent with a pro-leukemic phenotype.
PubMed: 38826323
DOI: 10.1101/2024.05.24.595827 -
Blood May 2024
Topics: Humans; Down Syndrome; Neutrophils; Myelopoiesis; Cytoplasmic Granules; Leukemoid Reaction; Male; Female; Child; Child, Preschool
PubMed: 38814653
DOI: 10.1182/blood.2024024317 -
European Journal of Immunology May 2024Stress exposure has been shown to modulate innate and adaptive immune responses. Indeed, stress favors myelopoiesis and monocyte generation and contributes to...
Stress exposure has been shown to modulate innate and adaptive immune responses. Indeed, stress favors myelopoiesis and monocyte generation and contributes to cardiovascular disease development. As sex hormones regulate innate and adaptive immune responses, we decided to investigate whether stress exposure leads to a different immune response in female and male mice. Our data demonstrated that psychosocial stressinduced neutrophilia in male, but not female mice. Importantly, we identified that B-cell numbers were reduced in female, but not male mice upon exposure to stress. Thus, our study revealed that the stress-induced immune alterations are sex-dependent, and this is an important feature to consider for future investigations.
PubMed: 38803021
DOI: 10.1002/eji.202350851 -
Immunity May 2024The activities, ontogeny, and mechanisms of lineage expansion of eosinophils are less well resolved than those of other immune cells, despite the use of biological...
The activities, ontogeny, and mechanisms of lineage expansion of eosinophils are less well resolved than those of other immune cells, despite the use of biological therapies targeting the eosinophilia-promoting cytokine interleukin (IL)-5 or its receptor, IL-5Rα. We combined single-cell proteomics and transcriptomics and generated transgenic IL-5Rα reporter mice to revisit eosinophilopoiesis. We reconciled human and murine eosinophilopoiesis and provided extensive cell-surface immunophenotyping and transcriptomes at different stages along the continuum of eosinophil maturation. We used these resources to show that IL-5 promoted eosinophil-lineage expansion via transit amplification, while its deletion or neutralization did not compromise eosinophil maturation. Informed from our resources, we also showed that interferon response factor-8, considered an essential promoter of myelopoiesis, was not intrinsically required for eosinophilopoiesis. This work hence provides resources, methods, and insights for understanding eosinophil ontogeny, the effects of current precision therapeutics, and the regulation of eosinophil development and numbers in health and disease.
PubMed: 38776917
DOI: 10.1016/j.immuni.2024.04.027