Myeloid Progenitors Research Articles

Abstract C017: Exploring the composition of and interaction of the tumor microenvironment in Langerhans cell histiocytosis

Abstract Langerhans cell histiocytosis (LCH) is a rare inflammatory hematological neoplasm, characterized by the accumulation of LCH cells in various tissues and organs. These LCH cells originate from myeloid progenitors that carry a MAPK-pathway mutation. Once these mutated cells enter the tissue from the periphery, they differentiate into so-called LCH cells. In addition to LCH cells, the tumor microenvironment (TME) consists of a wide variety of immune cells. However, the interactions between these cells within the TME and their contribution to disease progression remain poorly understood. In this study, we focus on understanding the role of lymphocytes in LCH lesions. We used single-cell RNA sequencing to comprehensively profile the immune populations in LCH lesions on the transcriptomic level, which will be supplemented with spatial profiling. Our analysis identified a wide variety of infiltrating immune cells within LCH lesions with high cellular heterogeneity among patients. LCH- and T cells are the most prevalent cell types, suggesting a key role in lesion development and maintenance. Furthermore, the immune landscape includes several dendritic cell subsets – such as plasmacytoid DCs (pDCs), cDC1, and mature regulatory dendritic cells (mregDCs) – alongside tumor-associated macrophages (TAMs), monocytes, NK cells, B cells, and plasmablasts. Among T cells, regulatory T cells (Tregs) are particularly abundant and appear to be heavily influenced by LCH cells and other myeloid cells via the TNF-TNFR2 and CD86-CTLA4 pathways. Additionally, LCH cells express high levels of TGFβ – a known regulator of T cell activity – and MMP9 – which might hamper cytotoxic T cell infiltration. This suggests that LCH cells actively contribute to creating an immunosuppressive environment. Surprisingly, pDCs seem to be a major immune regulator within lesions and are likely to interact with T cells via TNFSF9 and Granzyme B. These insights into the immunosuppressive environment within LCH lesions highlight the critical role of Tregs as central regulators within the tumor microenvironment. The implications of these findings will be further explored and validated through in-vitro experiments and high-plex spatial protein profiling. Ultimately, our work may pave the way for developing targeted therapies aimed at modulating the TME, potentially enhancing anti-tumor immunity, and offering new strategies for treating LCH. Citation Format: Wouter van Midden, Raphaela Schwentner, Sebastian Eder, Philipp Ben Soussia-Weiss, Giulio Abagnale, Caroline Hutter. Exploring the composition of and interaction of the tumor microenvironment in Langerhans cell histiocytosis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C017.

IMMU-37. PRE-TREATMENT INNATE INFLAMMATION ASSOCIATES WITH SURVIVAL AFTER POLIO VIROTHERAPY AND CAN BE MODULATED TO SENSITIZE GLIOMAS TO IN SITU VACCINATION

Abstract Early-stage clinical trials in glioblastoma (GBM) have tested various virotherapy strategies, yet only a subset of patients appear to benefit. We previously demonstrated that a recombinant poliovirus (PVSRIPO) functions by inducing MDA5-dependent, type I interferon (IFN) dominant innate inflammation in myeloid cells to provoke durable and functional antitumor T cell responses in mice. Long-term survival after intratumoral PVSRIPO infusion was observed in a subset of patients with recurrent GBM (rGBM) in two clinical trials. Survival after PVSRIPO was associated with higher pre-treatment intratumoral neutrophil density and MHC-class II gene expression, but also higher pre-treatment inflammatory cytokines in blood. Post-treatment induction of type I/III IFNs detected in blood one day after PVSRIPO infusion also associated with survival of patients with rGBM, suggesting that the proficiency of IFN responses to PVSRIPO may dictate therapy outcome. In human ex vivo glioma tissue assays, only a subset of gliomas mounted type I IFN responses to PVSRIPO and STING agonist treatment, in a manner linked with higher pre-treatment IL-1b levels, and lower CXCL10 induction after treatment. Thus, baseline innate inflammation either influences or reflects the capacity of glioma tumors to respond to virotherapy. Strikingly, in glioma bearing mice, peripheral vaccination against tumor irrelevant vaccines in alum adjuvant (i.e., against antigens not expressed by the tumor) induced bone marrow, spleen and intratumoral innate inflammation; rescued the antitumor efficacy of PVSRIPO in an otherwise refractory glioma model; and improved survival after intratumor STING agonist therapy. Notably, peripheral vaccination induced intratumoral neutrophil and CD4+ T cell inflammation, and increased MHC-class II expression on myeloid cells. These data imply a role for pre-treatment systemic innate immune training in the antitumor efficacy of virotherapy and indicate that modulating either systemic innate inflammation and/or the inflammatory status of bone marrow myeloid progenitors may sensitize gliomas to virotherapy.

Delayed macrophage targeting by clodronate liposomes worsens the progression of cytokine storm syndrome.

Excessive macrophage activation and production of pro-inflammatory cytokines are hallmarks of the Cytokine Storm Syndrome (CSS), a lethal condition triggered by sepsis, autoimmune disorders, and cancer immunotherapies. While depletion of macrophages at disease onset protects from lethality in an infection-induced CSS murine model, patients are rarely diagnosed early, hence the need to characterize macrophage populations during CSS progression and assess the therapeutic implications of macrophage targeting after disease onset. In this study, we identified MHCII+F4/80+Tim4- macrophages as the primary contributors to the pro-inflammatory environment in CSS, while CD206+F4/80+Tim4+ macrophages, with an anti-inflammatory profile, become outnumbered. Additionally, we observed an expansion of Tim4- macrophages coinciding with increased hematopoietic stem progenitor cells and reduction of committed myeloid progenitors in bone marrow and spleen. Critically, macrophage targeting with clodronate liposomes at disease onset prolonged survival, while their targeting in mice with established CSS exacerbated disease severity, leading to a more dramatic loss of Tim4+ macrophages and an imbalance in pro- versus anti-inflammatory Tim4- macrophage ratio. Our findings highlight the significance of timing in macrophage-targeted interventions for effective management of CSS and suggest potential therapeutic strategies for diseases characterized by uncontrolled inflammation, such as sepsis.

Genetic iron overload aggravates, and pharmacological iron restriction improves, MDS pathophysiology in a preclinical study

AbstractAlthough iron overload is a common feature in myelodysplastic syndromes (MDSs), it remains unclear how iron excess is detrimental for disease pathophysiology. Taking advantage of complementary approaches, we analyzed the impact of iron overload and restriction achieved through genetic activation of ferroportin (FPN) via the C326S mutation (FPNC326S) and pharmacologic inhibition (vamifeport) of the iron exporter FPN, respectively, in a MDS mouse model. Although FPNC326S-induced iron overload did not significantly improve the late stages of erythroid maturation, vamifeport-mediated iron restriction ameliorated anemia and red blood cell maturation in MDS mice, through the reduction of oxidative stress and apoptosis in erythroid progenitors. Iron overload aggravated, and restriction alleviated, reactive oxygen species formation, DNA damage, and cell death in hematopoietic stem and progenitor cells, resulting in altered cell survival and quality. Finally, myeloid bias, indicated by expanded bone marrow myeloid progenitors and circulating immature myeloid blasts, was exacerbated by iron excess and attenuated by iron restriction. Overall, vamifeport treatment resulted in improved anemia and significant survival increment in MDS mice. Interestingly, the combined therapy with vamifeport and the erythroid maturation agent luspatercept has superior effect in improving anemia and myeloid bias as compared with single treatments and offers additive beneficial effects in MDS. Our results prove, to our knowledge, for the first time in a preclinical model, that iron plays a pathologic role in transfusion-independent MDS. This is likely aggravated by transfusional iron overload, as suggested by observations in the FPNC326SMDS model. Ultimately, the beneficial effects of pharmacologic FPN inhibition uncovers the therapeutic potential of early prevention of iron toxicity in transfusion-independent MDS.

Gonadotropin-releasing hormone and organs of the immune system

As a result of a literature search, the physiological aspects of the gonadotropin-releasing hormone (GnRH) influence on immune organs, such as red bone marrow, thymus, spleen and lymph nodes, were considered. The use of GnRH drugs leads to the replacement of red bone marrow with yellow one with an increase in the content of lymphoid and myeloid progenitor cells. In parallel, processes of osteoporosis occur due to increased bone resorption with corresponding changes in calcium metabolism and a decrease in the density of various bone tissues. At the same time, there are papers reporting no effect of GnRH on bone density and changes in calcium metabolism. GnRH acts on the thymus during embryonic development, and in postnatal ontogenesis, and during inflammation and age-related involution processes. Not only GnRH causes changes in the thymus; the thymus may also influence on the GnRH system. A direct effect of GnRH on spleen cells had not been detected, but the weight of the organ changed as a result of active immunization against GnRH in experiment. Unfortunately, very few articles demonstrate the physiological mechanisms of immunomodulation in such conditions. In any case, the obvious insufficiency and contradictory of publications on each aspect of GnRH effects indicates that they have been poorly studied, and it’s advisabile of further continuing not only applied research, but also fundamental investigations, due to its possible high prospects for creating immune control systems.

Immunotherapeutic Potential of Mutated NPM1 for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a malignant disease of the blood and bone marrow that is characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells. Nucleophosmin 1 (NPM1) gene mutations are the most common genetic abnormality in AML, detectable in blast cells from about one-third of adults with AML. AML NPM1mut is recognized as a separate entity in the World Health Organization classification of AML. Clinical and survival data suggest that patients with this form of AML often have a more favorable prognosis, which may be due to the immunogenicity created by the mutations in the NPM1 protein. Consequently, AML with NPM1mut can be considered an immunogenic subtype of AML. However, the underlying mechanisms of this immunogenicity and associated favorable survival outcomes need to be further investigated. Immune checkpoint molecules, such as the programmed cell death-1 (PD-1) protein and its ligand, PD-L1, play important roles in leukemogenesis through their maintenance of an immunosuppressive tumor microenvironment. Preclinical trials have shown that the use of PD-1/PD-L1 checkpoint inhibitors in solid tumors and lymphoma work best in novel therapy combinations. Patients with AML NPM1mut may be better suited to immunogenic strategies that are based on the inhibition of the PD-1 immune checkpoint pathway than patients without this mutation, suggesting the genetic landscape of patients may also inform best practice for the use of PD-1 inhibitors.

CAR T-cell therapy in acute myeloid leukemia.

Acute myeloid leukemia (AML) is an aggressive leukemic malignancy that affects myeloid lineage progenitors. Relapsed or refractory AML patients continue to have poor prognoses, necessitating the development of novel therapy alternatives. Adoptive T-cell therapy with chimeric antigen receptors (CARs) is an intriguing possibility in the field of leukemia treatment. Chimeric antigen receptor T-cell therapy is now being tested in clinical trials (mostly in phase I and phase II) using AML targets including CD33, CD123, and CLL-1. Preliminary data showed promising results. However, due to the cellular and molecular heterogeneity of AML and the co-expression of some AML targets on hematopoietic stem cells, these clinical investigations have shown substantial "on-target off-tumor" toxicities, indicating that more research is required. In this review, the latest significant breakthroughs in AML CAR T cell therapy are presented. Furthermore, the limitations of CAR T-cell technology and future directions to overcome these challenges are discussed.

Therapeutic Delivery of MICRORNA-369-3p Promotes Atherosclerosis Regression in Diabetic Mice by Regulating Bone Marrow Myeloid Progenitors

Therapeutic Delivery of MICRORNA-369-3p Promotes Atherosclerosis Regression in Diabetic Mice by Regulating Bone Marrow Myeloid Progenitors

The 129 strain-derived passenger mutations in ACKR1-deficient mice alter the expression of PYHIN and Fc-gamma receptor genes.

A majority of genetically modified mice have been produced using 129 strain-derived embryonic stem cells (ESCs). Despite ample backcrosses with other strains, these may retain characteristic for 129 passenger mutations leading to confounding phenotypes unrelated to targeted genes. Here we show that widely used Ackr1-/-129ES mice have approximately 6Mb of the 129-derived genome retained adjacently to the Ackr1 locus on chromosome 1, including several characteristic polymorphisms. These most notably affect the expression of PYHIN and Fc-gamma receptor genes in myeloid cells resulting in the overproduction of IL-1β by activated macrophages and the loss of Fc-gamma receptors on myeloid progenitor cells. Therefore, caution is warranted when interpreting Ackr1-/-129ES mouse phenotypes as being solely due to the ACKR1 deficiency. Our findings call for a careful reevaluation of data from previous studies using Ackr1-/-129ES mice and underscore the limitations and pitfalls inherent to mouse models produced using traditional genetic engineering techniques involving 129 ESCs.

Solid tumour-induced systemic immunosuppression involves dichotomous myeloid-B cell interactions.

Solid tumours induce systemic immunosuppression that involves myeloid and T cells. B cell-related mechanisms remain relatively understudied. Here we discover two distinct patterns of tumour-induced B cell abnormality (TiBA; TiBA-1 and TiBA-2), both associated with abnormal myelopoiesis in the bone marrow. TiBA-1 probably results from the niche competition between pre-progenitor-B cells and myeloid progenitors, leading to a global reduction in downstream B cells. TiBA-2 is characterized by systemic accumulation of a unique early B cell population, driven by interaction with excessive neutrophils. Importantly, TiBA-2-associated early B cells foster the systemic accumulation of exhaustion-like T cells. Myeloid and B cells from the peripheral blood of patients with triple-negative breast cancer recapitulate the TiBA subtypes, and the distinct TiBA profile correlates with pathologic complete responses to standard-of-care immunotherapy. This study underscores the inter-patient diversity of tumour-induced systemic changes and emphasizes the need for treatments tailored to different B and myeloid cell abnormalities.

Lin-CD117+CD34+FcεRI+ progenitor cells are increased in chronic spontaneous urticaria and predict clinical responsiveness to anti-IgE therapy.

Chronic spontaneous urticaria (CSU) is a common, debilitating skin disorder characterized by recurring episodes of raised, itchy and sometimes painful wheals lasting longer than 6 weeks. CSU is mediated by mast cells which are absent from peripheral blood. However, lineage-CD34hiCD117int/hiFcεRI+ cells in blood have previously been shown to represent a mast cell precursor. We enumerated FcεRI-, FcεRI+ and FcεRIhi lineage-CD34+CD117+ cells using flow cytometry in blood of patients with CSU (n = 55), including 12 patients receiving omalizumab and 43 not receiving omalizumab (n = 43). Twenty-two control samples were studied. Disease control and patient response to omalizumab was evaluated using the urticaria control test. We performed single-cell RNA sequencing (scRNA-Seq) on lineage-CD34hiCD117hi blood cells from a subset of patients with CSU (n = 8) and healthy controls (n = 4). CSU patients had more lineage-CD34+CD117+FcεRI+ blood cells than controls. Lineage-CD34+CD117+FcεRI+ cells were significantly higher in patients with CSU who had an objective clinical response to omalizumab when compared to patients who had poor disease control 90 days after initiation of omalizumab. scRNA-Seq revealed that lineage-CD34+CD117+FcεRI+ cells contained both lymphoid and myeloid progenitor lineages, with omalizumab responsive patients having proportionally more myeloid progenitors. The myeloid progenitor lineage contained small numbers of true mast cell precursors along with more immature FcεRI- and FcεRI+ myeloid progenitors. Increased blood CD34+CD117+FcεRI+ cells may reflect enhanced bone marrow egress in the setting of CSU. High expression of these cells strongly predicts better clinical responses to the anti-IgE therapy, omalizumab.

Potential molecular metabolic mechanisms underlying the effects of cimifugin in gastric cancer through single-cell and bulk RNA sequencing combined with network pharmacology.

Gastric cancer (GC) is a leading cause of cancer-related mortality worldwide, posing a significant clinical challenge due to its complex tumor microenvironment (TME) and metabolic heterogeneity. Despite continuous improvements in treatment strategies including surgery, chemotherapy, and targeted therapies, the metabolic reprogramming in GC continues to impede treatment efficacy, highlighting an urgent need for the development of novel therapeutic strategies. This persistent issue underscores the urgent need for novel therapeutic approaches that can effectively address the diverse and dynamic characteristics of GC. Cimifugin, a traditional Chinese medicine (TCM), has garnered attention for its potential role in alleviating inflammation, neurological disorders, pain, and metabolic disorders. Its multi-targeting properties and minimal side effects suggest a broad potential for cancer management, which is currently being explored. This study aims to delineate the molecular mechanisms that cimifugin may impact within the TME and metabolic pathways of GC, with the expectation of contributing to a deeper understanding of GC and the development of innovative treatment strategies. We identified the GC-related TME cell types and metabolic profiles and pathways by using relevant data from the single-cell RNA sequencing (scRNA-seq) database GSE134520 and the stomach adenocarcinoma (STAD) data set from The Cancer Genome Atlas (TCGA). We also assessed the effects of cimifugin on MKN28 cell proliferation, invasion, and migration. By using six public platforms, we comprehensively predicted the potential biological targets of cimifugin. Clinical prognosis and immunohistochemistry (IHC), molecular docking, and dynamics simulations were used to confirm the clinical relevance and stability of the aforementioned targets. Cimifugin inhibited MKN28 cell proliferation, migration, and invasion. Cimifugin may potentially act on various metabolic pathways in GC, including folate biosynthesis, xenobiotic metabolism via cytochrome P450 (CYP), glutathione metabolism, steroid hormone biosynthesis, and tryptophan metabolism. Cimifugin was noted to stably bind to three significant core targets associated with metabolic reprogramming in GC: AKR1C2, MAOB, and PDE2A; all three targets were strongly expressed in endocrince cells, pit mucous cells (PMCs), and common myeloid progenitors (CMPs). We verified the pharmacological effects of cimifugin on GC cell proliferation, invasion, and migration. AKR1C2, MAOB, and PDE2A were identified as the key targets of cimifugin in GC-related metabolic reprogramming and pathogenesis. Our research provides preliminary insights into the potential therapeutic effects of cimifugin, which could be considered for future exploration in the context of GC treatment.

Deciphering bone marrow engraftment after allogeneic stem cell transplantation in humans using single-cell analyses.

BACKGROUNDDonor cell engraftment is a prerequisite of successful allogeneic hematopoietic stem cell transplantation. Based on peripheral blood analyses, it is characterized by early myeloid recovery and T and B cell lymphopenia. However, cellular networks associated with bone marrow engraftment of allogeneic human cells have been poorly described.METHODSMass cytometry and CITE-Seq analyses were performed on bone marrow cells 3 months after transplantation in patients with acute myelogenous leukemia.RESULTSMass cytometric analyses in 26 patients and 20 healthy controls disclosed profound alterations in myeloid and B cell progenitors, with a shift toward terminal myeloid differentiation and decreased B cell progenitors. Unsupervised analysis separated recipients into 2 groups, one of them being driven by previous graft-versus-host disease (R2 patients). We then used single-cell CITE-Seq to decipher engraftment, which resolved 36 clusters, encompassing all bone marrow cellular components. Hematopoiesis in transplant recipients was sustained by committed myeloid and erythroid progenitors in a setting of monocyte-, NK cell-, and T cell-mediated inflammation. Gene expression revealed major pathways in transplant recipients, namely, TNF-α signaling via NF-κB and the IFN-γ response. The hallmark of allograft rejection was consistently found in clusters from transplant recipients, especially in R2 recipients.CONCLUSIONBone marrow cell engraftment of allogeneic donor cells is characterized by a state of emergency hematopoiesis in the setting of an allogeneic response driving inflammation.FUNDINGThis study was supported by the French National Cancer Institute (Institut National du Cancer; PLBIO19-239) and by an unrestricted research grant by Alexion Pharmaceuticals.

Cutting-edge developments in acute myeloid leukaemia: innovations in diagnosis and treatment

Acute Myeloid Leukaemia (AML) is a fast-growing hematologic malignancy that is distinguished by the clonal proliferation of myeloid progenitors in bone marrow. Recent advances in molecular biology and genomic technology have altered the landscape of AML diagnosis and therapy, resulting in more tailored and successful therapeutic approaches. This study reviews recent innovations in the diagnosis and treatment of AML, focusing on genomic profiling, next-generation sequencing (NGS), and novel targeted therapies. Data was collected from recent clinical trials, peer-reviewed journals, and case studies. Comparative analysis was conducted to evaluate the efficacy of emerging diagnostic tools and treatments. NGS and MRD monitoring have greatly improved diagnosis accuracy and therapy customization. Targeted medicines have enhanced remission rates and decreased recurrence rates in individuals with certain genetic alterations. Immunotherapies have showed long-term efficacy and controllable safety profiles. Combining modern diagnostic technologies with customized medicines ushers in a new era of AML care, enhancing prognosis and quality of life. Ongoing research and clinical trials are critical for improving these therapies and expanding their advantages to a larger patient group.

Reprogramming myeloid bone marrow progenitors in non-medullary thyroid cancer using trained immunity

Reprogramming myeloid bone marrow progenitors in non-medullary thyroid cancer using trained immunity

Molecular characteristics of NPM1 mutations in AML patients using targeted NGS

ABSTRACT Background Acute myeloid leukemia (AML) is a clonal hematopoietic stem cell malignancy characterized by the accumulation of myeloid progenitor cells with arrested differentiation, leading to the suppression of normal hematopoiesis. The disease exhibits significant heterogeneity, with less than 30% five-year overall survival. Nucleophosmin 1 (NPM1) is the most commonly mutated gene in adult AML, found in approximately 25–35% of patients, and is recognized as a distinct subtype by the WHO. Methods The mutational status of NPM1 was assessed using the Oncomine Myeloid research panel on the Ion5S NGS platform (Thermo Fisher Scientific, USA). Results In our AML cohort, NPM1 was the most frequently mutated gene (75%). Indel mutations in the NPM1 gene, frequently resulting in frameshift consequences, show a statistically significant difference in variant allele frequency (VAF) compared to other mutation types. Specifically, NPM1-mutated cases exhibit a VAF that is positively correlated with initial bone marrow (BM) blast counts. Univariate logistic regression analysis reveals that a high VAF is significantly associated with non-complete remission (Non-CR), while a low VAF is significantly associated with complete remission (CR), indicating a statistically significant difference in outcomes (p = 0.012). Conclusion Targeted NGS technology enables the simultaneous analysis of multiple AML-relevant genes, offering a comprehensive mutational profile that supports risk stratification, diagnosis, and personalized treatment. Our findings highlight the significant impact of NPM1 mutations on patient outcomes, revealing their molecular characteristics and their correlation with different clinical parameters.

The Role of Epithelial-to-Mesenchymal Transition Transcription Factors (EMT-TFs) in Acute Myeloid Leukemia Progression.

Acute myeloid leukemia (AML) is a diverse malignancy originating from myeloid progenitor cells, with significant genetic and clinical variability. Modern classification systems like those from the World Health Organization (WHO) and European LeukemiaNet use immunophenotyping, molecular genetics, and clinical features to categorize AML subtypes. This classification highlights crucial genetic markers such as FLT3, NPM1 mutations, and MLL-AF9 fusion, which are essential for prognosis and directing targeted therapies. The MLL-AF9 fusion protein is often linked with therapy-resistant AML, highlighting the risk of relapse due to standard chemotherapeutic regimes. In this sense, factors like the ZEB, SNAI, and TWIST gene families, known for their roles in epithelial-mesenchymal transition (EMT) and cancer metastasis, also regulate hematopoiesis and may serve as effective therapeutic targets in AML. These genes contribute to cell proliferation, differentiation, and extramedullary hematopoiesis, suggesting new possibilities for treatment. Advancing our understanding of the molecular mechanisms that promote AML, especially how the bone marrow microenvironment affects invasion and drug resistance, is crucial. This comprehensive insight into the molecular and environmental interactions in AML emphasizes the need for ongoing research and more effective treatments.

Perinatal liver inflammation is associated with persistent elevation of CXCL10 and its canonical receptor CXCR3 on common myeloid progenitors.

Biliary atresia (BA) is a leading cause of liver failure in infants. Despite effective surgical drainage, patients with BA exhibit attenuated immune responses to childhood vaccines, suggesting there are long-lasting alterations to immune function. The perinatal liver is home to hematopoietic stem and progenitor cells (HSPCs) and serves as the epicenter for rapidly progressive and significantly morbid inflammatory diseases like BA. We have previously established the role of neonatal myeloid progenitors in the pathogenesis of perinatal liver inflammation (PLI) and hypothesize that PLI leads to long-term changes to HSPCs in mice that recovered from PLI. To test this hypothesis, we compared the changes that occur to HSPCs and mature myeloid populations in the bone marrow of adult mice during homeostasis and during PLI. Our results demonstrate that HSPCs from animals that recover from PLI ("PLI-recovered") undergo long-term expansion with a reduced proliferative capacity. Notably, PLI leads to persistent activation of common myeloid progenitors through the involvement of CXCL10 and its canonical receptor, CXCR3. Our data suggests that the CXCR3-CXCL10 axis may mediate the changes in HSPCs that lead to altered immune function observed in BA, providing support for a targetable pathway to mitigate the detrimental long-term immune effects observed in patients with BA.

Navigating a Paradigm Shift Venetoclax Treatment Redefines Landscape of Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the accumulation of malignant myeloid progenitor hematopoietic cells in the bone marrow and peripheral blood. Recent studies have shown promising results with the use of small molecule inhibitors and targeted therapy in the treatment of patients with AML. One such molecule is venetoclax, which has been approved in AML by the FDA in combination with hypomethylating agents or low-dose cytarabine. We thoroughly searched electronic literature related to venetoclax and its role in AML, using databases such as MEDLINE, PubMed, Google Scholar, and PsychInfo, through April 2024. We applied population, intervention, comparison, and outcome criteria, specifically focusing on studies with a population using venetoclax from review articles and clinical trials. All selected studies were required to be in English, and any study that did not involve the use of venetoclax was excluded. A meticulous literature review was conducted to consolidate the current knowledge and new combination therapies on AML. In our review article, we focused on the latest advances in the treatment of patients with AML. Based on the literature, we recommend that physicians prioritize the use of venetoclax in the management of this deadly disease because it has been shown to significantly impact the course of the disease.

Burn Injury Results in Myeloid Priming during Emergency Hematopoiesis.

Hematopoiesis proceeds in a tiered pattern of differentiation, beginning with hematopoietic stem cells (HSC) and culminating in erythroid, myeloid, and lymphoid lineages. Pathologically altered lineage commitment can result in inadequate leukocyte production or dysfunctional cell lines. Drivers of emergency hematopoiesis after burn injury are inadequately defined. Burn injury induces a myeloid predominance associated with infection that worsens outcomes. This study aims to further profile bone marrow HSCs following burn injury in a murine model. C57BL/6 mice received burn or sham injury with ~12% total body surface area (TBSA) scald burn on the dorsal surface with subsequent sacrifice at 1, 2, 3, 7 and 10 days post-injury. Bone marrow (BM) from hindlimbs were analyzed for HSC populations via flow cytometry and analyzed using FlowJo Software (version 10.6). Event counts and frequencies were analyzed with multiple unpaired t-tests and linear mixed-effect regression. RT-PCR performed on isolated lineage negative BM cell RNA targeted PU.1, GATA-1, and GATA-3 with subsequent analysis conducted with QuantStudio 3 software. Statistical analysis and representation were performed on GraphPad software (Prism). Flow cytometry revealed significantly elevated proportions of Long-Term HSCs at 3 days post-injury (p < .05) and Short-Term HSCs at days 2, 3, and 10 (all p < .05) in burn-injured mice. There was a sustained, but not significant, increase in proportions in the multi-potent progenitor (MPP) 2 and 3 subpopulations in the burn cohort compared to sham controls. The common myeloid progenitor (CMP) proportion was significantly higher on days 3 and 10 (both p < .01), while the granulocyte-macrophage progenitor (GMP) proportion increased on days 1, 2, and 10 (p < .05, p < .01, p < .01). Although the megakaryocyte-erythrocyte progenitor (MEP) proportion appeared consistently lower in the burn cohort, this did not reach significance. mRNA analysis resulted in a downregulation of PU.1 on day 1 (p = 0.0002) with an upregulation by day 7 (p < 0.01). GATA-1 downregulation occurred by day 7 (p < 0.05), and GATA3 showed downregulation on days 3 and 7 (p < 0.05). Full-thickness burn results in an emergency hematopoiesis via proportional increase of Long Term-HSC and Short Term-HSC/MPP1 subpopulations beginning in the early post-injury period. Subsequent lineage commitment displays a myeloid predominance with a shift toward myeloid progenitors with mRNA analysis corroborating this finding with associated upregulation of PU.1 and downregulation of GATA-1 and GATA-3. Further studies are needed to understand how burn-induced emergency hematopoiesis may predispose to infection by pathologic lineage selection.