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JCI Insight Apr 2024Acute myeloid leukemia (AML) is a fatal disease characterized by the accumulation of undifferentiated myeloblasts, and agents that promote differentiation have been...
Acute myeloid leukemia (AML) is a fatal disease characterized by the accumulation of undifferentiated myeloblasts, and agents that promote differentiation have been effective in this disease but are not curative. Dihydroorotate dehydrogenase inhibitors (DHODHi) have the ability to promote AML differentiation and target aberrant malignant myelopoiesis. We introduce HOSU-53, a DHODHi with significant monotherapy activity, which is further enhanced when combined with other standard-of-care therapeutics. We further discovered that DHODHi modulated surface expression of CD38 and CD47, prompting the evaluation of HOSU-53 combined with anti-CD38 and anti-CD47 therapies, where we identified a compelling curative potential in an aggressive AML model with CD47 targeting. Finally, we explored using plasma dihydroorotate (DHO) levels to monitor HOSU-53 safety and found that the level of DHO accumulation could predict HOSU-53 intolerability, suggesting the clinical use of plasma DHO to determine safe DHODHi doses. Collectively, our data support the clinical translation of HOSU-53 in AML, particularly to augment immune therapies. Potent DHODHi to date have been limited by their therapeutic index; however, we introduce pharmacodynamic monitoring to predict tolerability while preserving antitumor activity. We additionally suggest that DHODHi is effective at lower doses with select immune therapies, widening the therapeutic index.
Topics: Leukemia, Myeloid, Acute; Humans; Pyrimidines; Mice; Animals; Dihydroorotate Dehydrogenase; Immunotherapy; Cell Line, Tumor; Xenograft Model Antitumor Assays; Female
PubMed: 38646934
DOI: 10.1172/jci.insight.173646 -
Histopathology Oct 2023Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection broadly affects organ homeostasis, including the haematopoietic system. Autopsy studies are a...
AIMS
Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection broadly affects organ homeostasis, including the haematopoietic system. Autopsy studies are a crucial tool for investigation of organ-specific pathologies. Here we perform an in-depth analysis of the impact of severe coronavirus disease 2019 (COVID-19) on bone marrow haematopoiesis in correlation with clinical and laboratory parameters.
METHODS AND RESULTS
Twenty-eight autopsy cases and five controls from two academic centres were included in the study. We performed a comprehensive analysis of bone marrow pathology and microenvironment features with clinical and laboratory parameters and assessed SARS-CoV-2 infection of the bone marrow by quantitative polymerase chain reaction (qPCR) analysis. In COVID-19 patients, bone marrow specimens showed a left-shifted myelopoiesis (19 of 28, 64%), increased myeloid-erythroid ratio (eight of 28, 28%), increased megakaryopoiesis (six of 28, 21%) and lymphocytosis (four of 28, 14%). Strikingly, a high proportion of COVID-19 specimens showed erythrophagocytosis (15 of 28, 54%) and the presence of siderophages (11 of 15, 73%) compared to control cases (none of five, 0%). Clinically, erythrophagocytosis correlated with lower haemoglobin levels and was more frequently observed in patients from the second wave. Analysis of the immune environment showed a strong increase in CD68+ macrophages (16 of 28, 57%) and a borderline lymphocytosis (five of 28, 18%). The stromal microenvironment showed oedema (two of 28, 7%) and severe capillary congestion (one of 28, 4%) in isolated cases. No stromal fibrosis or microvascular thrombosis was found. While all cases had confirmed positive testing of SARS-CoV-2 in the respiratory system, SARS-CoV-2 was not detected in the bone marrow by high-sensitivity PCR, suggesting that SARS-CoV-2 does not commonly replicate in the haematopoietic microenvironment.
CONCLUSIONS
SARS-CoV-2 infection indirectly impacts the haematological compartment and the bone marrow immune environment. Erythrophagocytosis is frequent and associated with lower haemoglobin levels in patients with severe COVID-19.
Topics: Humans; COVID-19; SARS-CoV-2; Bone Marrow; Lymphocytosis; Hematopoiesis; Hemoglobins
PubMed: 37317636
DOI: 10.1111/his.14969 -
Clinical and Translational Medicine Dec 2023Whereas most infants infected with respiratory syncytial virus (RSV) show no or only mild symptoms, an estimated 3 million children under five are hospitalized annually...
Whereas most infants infected with respiratory syncytial virus (RSV) show no or only mild symptoms, an estimated 3 million children under five are hospitalized annually due to RSV disease. This study aimed to investigate biological mechanisms and associated biomarkers underlying RSV disease heterogeneity in young infants, enabling the potential to objectively categorize RSV-infected infants according to their medical needs. Immunophenotypic and functional profiling demonstrated the emergence of immature and progenitor-like neutrophils, proliferative monocytes (HLA-DR , Ki67+), impaired antigen-presenting function, downregulation of T cell response and low abundance of HLA-DR B cells in severe RSV disease. HLA-DR monocytes were found as a hallmark of RSV-infected infants requiring hospitalization. Complementary transcriptomics identified genes associated with disease severity and pointed to the emergency myelopoiesis response. These results shed new light on mechanisms underlying the pathogenesis and development of severe RSV disease and identified potential new candidate biomarkers for patient stratification.
Topics: Infant; Child; Humans; Myelopoiesis; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; HLA-DR Antigens; Biomarkers
PubMed: 38115705
DOI: 10.1002/ctm2.1507 -
Basic Research in Cardiology Apr 2024Myocardial infarction (MI) induces the generation of proinflammatory Ly6C monocytes in the spleen and the recruitment of these cells to the myocardium. CD4 Foxp3 CD25...
Myocardial infarction (MI) induces the generation of proinflammatory Ly6C monocytes in the spleen and the recruitment of these cells to the myocardium. CD4 Foxp3 CD25 T-cells (Tregs) promote the healing process after myocardial infarction by engendering a pro-healing differentiation state in myocardial monocyte-derived macrophages. We aimed to study the effects of CD4 T-cells on splenic myelopoiesis and monocyte differentiation. We instigated MI in mice and found that MI-induced splenic myelopoiesis is abrogated in CD4 T-cell deficient animals. Conventional CD4 T-cells promoted myelopoiesis in vitro by cell-cell-contact and paracrine mechanisms, including interferon-gamma (IFN-γ) signalling. Depletion of regulatory T-cells enhanced myelopoiesis in vivo, as evidenced by increases in progenitor cell numbers and proliferative activity in the spleen 5 days after MI. The frequency of CD4 T-cells-producing factors that promote myelopoiesis increased within the spleen of Treg-depleted mice. Moreover, depletion of Tregs caused a proinflammatory bias in splenic Ly6C monocytes, which showed predominantly upregulated expression of IFN-γ responsive genes after MI. Our results indicate that conventional CD4 T-cells promote and Tregs attenuate splenic myelopoiesis and proinflammatory differentiation of monocytes.
Topics: Mice; Animals; Monocytes; Myelopoiesis; Spleen; Myocardial Infarction; T-Lymphocytes, Regulatory; Interferon-gamma; Mice, Inbred C57BL
PubMed: 38436707
DOI: 10.1007/s00395-024-01035-3 -
Cureus Nov 2023Hematological disorders pose a diagnostic challenge due to overlapping clinical features, as demonstrated by the difficulty in differentiating between aplastic anemia...
Hematological disorders pose a diagnostic challenge due to overlapping clinical features, as demonstrated by the difficulty in differentiating between aplastic anemia (AA) and primary myelofibrosis (PM). Myeloproliferative disorders, characterized by aberrant proliferation of bone marrow stem cells, present complexities in diagnosis, often requiring a comprehensive evaluation to distinguish between disorders with similar manifestations. The distinctions between myelofibrosis and AA lie not only in clinical presentations but also in genetic and molecular markers, necessitating a nuanced diagnostic approach. We present a case of a 37-year-old male initially diagnosed with myelofibrosis based on a history of pancytopenia, warm submandibular and submental swelling, and negative BCR-ABL and JAK2 mutations. Further examination revealed empty fragmented cells, hypoplastic bone marrow, and suppressed erythropoiesis and myelopoiesis. Subsequent core biopsy showed increased megakaryocytes, prompting a revised diagnosis of AA. This case underscores the importance of a meticulous diagnostic journey, incorporating physical examination, genetic testing, and advanced imaging to unravel the complexities of hematological disorders. The intricacies of this case prompt a reevaluation of diagnostic paradigms, highlighting the limitations of relying solely on specific mutations for diagnosis. The absence of BCR-ABL and JAK2 mutations in AA raises questions about its genetic landscape, necessitating further exploration. Immunological considerations, given the immune-mediated nature of AA, provide a foundation for future research into immune dysregulation and potential therapeutic interventions. The clinical management challenges posed by AA underscore the need for personalized treatment strategies, guided by a deeper understanding of its underlying pathophysiology. Advanced imaging techniques, in conjunction with traditional diagnostic methods, emerge as crucial tools for enhancing diagnostic accuracy in hematological disorders. This case serves as a paradigm for ongoing medical education, multidisciplinary collaboration, and innovative approaches in the evolving landscape of hematology, emphasizing the imperative for continuous refinement in diagnostic strategies and patient care.
PubMed: 38149134
DOI: 10.7759/cureus.49445 -
Developmental Cell Jul 2023Embryonic definitive hematopoiesis generates hematopoietic stem and progenitor cells (HSPCs) that are essential for the establishment and maintenance of the adult blood...
Embryonic definitive hematopoiesis generates hematopoietic stem and progenitor cells (HSPCs) that are essential for the establishment and maintenance of the adult blood system. This process requires the specification of a subset of vascular endothelial cells (ECs) to become hemogenic ECs and to have subsequent endothelial-to-hematopoietic transition (EHT), and the underlying mechanisms are largely undefined. We identified microRNA (miR)-223 as a negative regulator of murine hemogenic EC specification and EHT. Loss of miR-223 leads to increased formation of hemogenic ECs and HSPCs, which is associated with increased retinoic acid signaling, which we previously showed as promoting hemogenic EC specification. Additionally, loss of miR-223 leads to the generation of myeloid-biased hemogenic ECs and HSPCs, which results in an increased proportion of myeloid cells throughout embryonic and postnatal life. Our findings identify a negative regulator of hemogenic EC specification and highlight the importance of this process for the establishment of the adult blood system.
Topics: Mice; Animals; Hemangioblasts; Myelopoiesis; Hematopoietic Stem Cells; Hematopoiesis; Cell Differentiation; MicroRNAs
PubMed: 37295435
DOI: 10.1016/j.devcel.2023.05.007 -
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 -
Stem Cell Reports Feb 2024Emergency myelopoiesis (EM) is essential in immune defense against pathogens for rapid replenishing of mature myeloid cells. During the EM process, a rapid cell-cycle...
Emergency myelopoiesis (EM) is essential in immune defense against pathogens for rapid replenishing of mature myeloid cells. During the EM process, a rapid cell-cycle switch from the quiescent hematopoietic stem cells (HSCs) to highly proliferative myeloid progenitors (MPs) is critical. How the rapid proliferation of MPs during EM is regulated remains poorly understood. Here, we reveal that ATG7, a critical autophagy factor, is essential for the rapid proliferation of MPs during human myelopoiesis. Peripheral blood (PB)-mobilized hematopoietic stem/progenitor cells (HSPCs) with ATG7 knockdown or HSPCs derived from ATG7 human embryonic stem cells (hESCs) exhibit severe defect in proliferation during fate transition from HSPCs to MPs. Mechanistically, we show that ATG7 deficiency reduces p53 localization in lysosome for a potential autophagy-mediated degradation. Together, we reveal a previously unrecognized role of autophagy to regulate p53 for a rapid proliferation of MPs in human myelopoiesis.
Topics: Humans; Myelopoiesis; Tumor Suppressor Protein p53; Hematopoietic Stem Cells; Myeloid Cells; Autophagy
PubMed: 38215759
DOI: 10.1016/j.stemcr.2023.12.005 -
Annals of African Medicine 2023Aplastic anemia (AA) is an uncommon condition characterized by pancytopenia and hypocellular bone marrow. Interleukin (IL)-6 and IL-8 have been shown to inhibit...
BACKGROUND
Aplastic anemia (AA) is an uncommon condition characterized by pancytopenia and hypocellular bone marrow. Interleukin (IL)-6 and IL-8 have been shown to inhibit myelopoiesis and are major mediators of tissue damage. The primary goal of this study was to determine the IL-6 and IL-8 levels in children with AA, as well as their relationship to illness severity and immunosuppressive medication response.
MATERIALS AND METHODS
The IL-6 and IL-8 levels were tested in 50 children aged 3-18 years who had AA. As controls, 50 healthy age and sex matched individuals were used. A sandwich enzyme-linked immunosorbent assay kit (solid-phase) was used to measure IL-6 and IL-8 levels quantitatively. The concentrations of IL-6 and IL-8 in pg/mL were used to represent the results. Immunosuppressive medication was given to the patients in accordance with the British Committee for Standards in Haematology Guidelines 2009.
RESULTS
The patients' average age was 11.3 ± 3.7 years. Patients with AA had significantly higher IL-6 and IL-8 levels than controls (278.88 ± 216.03 vs. 4.51 ± 3.26; P < 0.001) and (120.28 ± 94.98 vs. 1.79 ± 0.78; P < 0.001), respectively. The IL-6 and IL-8 levels were also investigated with respect to AA severity, with statistically significant differences (P < 0.01) between different grading strata. Patients with very severe AA (VSAA) had the highest IL-6 levels (499.52 ± 66.19), followed by severe AA (SAA) (201.28 ± 157.77) and non-SAA (NSAA) (22.62 ± 14.63). For IL-8 levels, a similar trend (P < 0.01) was detected, with values of 209.81 ± 38.85, 92.12 ± 78.0, and 9.29 ± 10.68 for VSAA, SAA, and NSAA, respectively. After 6 months of immunosuppressive treatment (IST), mean levels of IL-6 and IL-8 in responders and nonresponders were again assessed. The mean IL-6 level in the responders' group (46.50 ± 45.41) was significantly lower, when compared to the nonresponders' group (145.76 ± 116.32) (P < 0.001). Similarly, the mean IL-8 level in the responder's group (33.57 ± 27.14) was significantly lower, compared to the nonresponder's group (97.49 ± 69.00) (P < 0.001).
CONCLUSIONS
Children with AA had higher IL-6 and IL-8 levels than normal age- and sex-matched controls. Increased levels were linked to the severity of the condition, suggesting that IL may have a role in AA. IL levels can be monitored in AA patients during IST, which can assist in predicting response to IST.
Topics: Child; Humans; Adolescent; Anemia, Aplastic; Interleukin-6; Interleukin-8; Treatment Outcome; Immunosuppressive Agents; Immunosuppression Therapy; Patient Acuity
PubMed: 38358144
DOI: 10.4103/aam.aam_106_22 -
Frontiers in Immunology 2024The recent identification of skull bone marrow as a reactive hematopoietic niche that can contribute to and direct leukocyte trafficking into the meninges and brain has... (Review)
Review
The recent identification of skull bone marrow as a reactive hematopoietic niche that can contribute to and direct leukocyte trafficking into the meninges and brain has transformed our view of this bone structure from a solid, protective casing to a living, dynamic tissue poised to modulate brain homeostasis and neuroinflammation. This emerging concept may be highly relevant to injuries that directly impact the skull such as in traumatic brain injury (TBI). From mild concussion to severe contusion with skull fracturing, the bone marrow response of this local myeloid cell reservoir has the potential to impact not just the acute inflammatory response in the brain, but also the remodeling of the calvarium itself, influencing its response to future head impacts. If we borrow understanding from recent discoveries in other CNS immunological niches and extend them to this nascent, but growing, subfield of neuroimmunology, it is not unreasonable to consider the hematopoietic compartment in the skull may similarly play an important role in health, aging, and neurodegenerative disease following TBI. This literature review briefly summarizes the traditional role of the skull in TBI and offers some additional insights into skull-brain interactions and their potential role in affecting secondary neuroinflammation and injury outcomes.
Topics: Humans; Brain Injuries, Traumatic; Animals; Brain; Skull; Neuroinflammatory Diseases; Bone Marrow
PubMed: 38680490
DOI: 10.3389/fimmu.2024.1353513