IFNγ-Induced Necroptosis Contributes to Hematopoietic Stem and Progenitor Cell Death and Bone Marrow Failure

Abstract RIPK1 has important kinase-dependent and kinase-independent scaffolding functions that prevent or activate necroptosis or apoptosis. Complete RIPK1 deficiency results in cell death and widespread inflammation yet tissue specific RIPK1 deletion can result in apoptosis, necroptosis and/or systemic inflammation, depending on the cell type. We have previously demonstrated that a hematopoietic RIPK1 deficiency results in constitutive activation of RIPK3 and MLKL and induction of necroptosis (Roderick et al, PNAS, 2014). These mice exhibit elevated serum TNFα and IFNγ levels, hematopoietic stem and progenitor cell (HSPC) loss, and ultimately succumb to bone marrow failure (BMF). When mice with a hematopoietic RIPK1 deficiency were placed on a RIPK3 deficient background, plasma pro-inflammatory cytokine and chemokine levels were reduced, HSPC numbers increased and BMF was significantly delayed. These mouse genetic data demonstrate that necroptotic death contributes to BMF in the mouse. To identify the receptor/ligands that trigger necroptosis, we generated mice with a hematopoietic RIPK1-deficiency on the Tnfr1-/-and Tnfr1-/-Tnfr2-/-genetic backgrounds. An absence of TNF signaling failed to prevent necroptosis and consequently, vav-iCre Ripk1f/f Tnfr1-/- Tnfr2-/-mice succumbed to BMF. Because type II interferons can also induce necroptosis, we generated vav-iCre Ripk1f/f Ifngr1-/- mice. These mice appear phenotypically normal demonstrating that an absence of IFNγ signaling prevents HSPC necroptosis and BMF.Collectively, these data may implicate IFNγ-mediated, RIPK3-dependent necroptosis in human BMF syndromes and raise the intriguing possibility that the progressive HSPC elimination observed in these patients reflects in part, IFNγ-induced necroptotic death. Disclosures No relevant conflicts of interest to declare.

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Ripk-Mediated Necroptosis Induces Inflammation and Bone Marrow Failure in Mice

Blood ◽

10.1182/blood.v124.21.1599.1599 ◽

2014 ◽

Vol 124 (21) ◽

pp. 1599-1599

Author(s):

Justine E. Roderick ◽

Nicole Hermance ◽

Matija Zelic ◽

Matthew Simmons ◽

Apostolos Polykratis ◽

...

Keyword(s):

Bone Marrow ◽

Cell Death ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Human Bone ◽

Human Bone Marrow ◽

Type I ◽

Hematopoietic Stem ◽

Tnf Α ◽

Ifn Γ

Abstract TNF-α and IFN-γ overproduction are features associated with human bone marrow failure syndromes such as Fanconi Anemia (FA) and Aplastic Anemia (AA). Cells from these patients are known to be hypersensitive to TNF-α and IFN-γ-induced cell death. The serine threonine kinases RIPK1 and RIPK3 interact to mediate necroptosis induced by TNF-α, type I or II interferons. We demonstrate that a hematopoietic RIPK1 deficiency results in hematopoietic stem and progenitor cell loss and induction of bone marrow failure. The cell death reflects cell-intrinsic survival roles for RIPK1 in hematopoietic stem and progenitor cells, as Vav-iCre Ripk1fl/fl fetal liver cells failed to reconstitute hematopoiesis in lethally irradiated recipients. Hematopoietic failure in these mice is accompanied by increases in serum pro-inflammatory cytokines/chemokines and reduced hematopoietic colony formation in the presence of TNF-α, type I or II interferon. We provide genetic evidence that a RIPK3 deficiency rescues the bone marrow failure and significantly reduces serum cytokine and chemokine levels in Vav-iCre Ripk1fl/fl mice. These data reveal that in the hematopoietic lineage RIPK1 prevents inflammation by suppressing RIPK3 activity and raise the possibility that human bone marrow failure patients may benefit from selective RIPK inhibitors. Disclosures No relevant conflicts of interest to declare.

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23 Years of Management: A Retrospective Review of Treatment for Aplastic Anemia.

Blood ◽

10.1182/blood.v114.22.1091.1091 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1091-1091

Author(s):

Connie M Piccone ◽

Marie Boorman Martin ◽

Zung Vu Tran ◽

Kim Smith-Whitley

Keyword(s):

Bone Marrow ◽

Aplastic Anemia ◽

Retrospective Review ◽

Pediatric Patients ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Complete Response ◽

Primary Objective ◽

Hematopoietic Stem ◽

Transfusion Independence

Abstract Abstract 1091 Poster Board I-113 Introduction Aplastic anemia (AA) is a syndrome of bone marrow failure characterized by peripheral pancytopenia and marrow hypoplasia. In the past, AA was considered to be a fatal disease; however, current therapies, including bone marrow transplantation or immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and cyclosporine (CSA), are curative in the majority of patients. IST is effective at restoring hematopoietic stem cell production, but relapse and evolution to myelodysplastic syndromes remain clinical challenges. Additionally, there is no real consensus regarding optimal CSA levels, duration of CSA treatment, or the optimal use of growth factors and their relationship to the development of clonal disease. Objectives The primary objective was to review treatment management for severe AA in pediatric patients in order to elucidate treatment differences and review morbidity and mortality as they relate to treatment variation. Study Design/Methods A retrospective review of pediatric patients treated at the Children's Hospital of Philadelphia for AA (both severe and moderate) over a 23 year period was performed. Results A total of 70 patients with AA were treated at our institution from 1985 to July 2008. Exclusions included: 6 patients who received some type of initial treatment at outside institutions, 4 patients who had missing records, and 2 patients who had a diagnosis of moderate AA. Thus, a total of 58 patient records were included in the analysis. Of the total patients reviewed, 60% were male and 40% were female. 34.5% of patients were African-American, and 57% were diagnosed in 2000 or later. The mean age at diagnosis was 9.5±5.8 years. 52% fell into the category of very severe AA based on published diagnostic criteria, 45% had severe AA, and 2 patients (3%) had moderate AA. 15.5% of patients developed AA in the setting of acute hepatitis. More than half of the patients treated with IST had a complete response (CR). The average time to CR was 15±15 months. Average duration of CSA treatment was 15±13 months and 8.6±10.7 months for growth factor. Two patients (3.5%) died, one from complications unrelated to AA and one from infectious complications post-BMT after initial IST failure. Average time to transfusion independence for all patients was 8±11 months (with a range of 0-54 months). Not surprisingly, the time to transfusion independence was significantly associated with IST failure (p=0.010). Patients who failed treatment had an average time to transfusion independence of 17±16 months as compared to those who were complete responders who had an average time to transfusion independence of 3±3 months. Additionally, there was a significant association between IST failure and CSA levels (p=0.014). Patients who had nontherapeutic CSA levels overall had an increased rate of treatment failure. Of those patients who were nontherapeutic, 56% were noncompliant with CSA administration. There was no significant association between IST failure and bone marrow cellularity (p=0.251). PNH was diagnosed in 5% of patients; there were no patients with evidence of myelodysplastic syndrome (MDS). Two of the 3 patients with PNH failed initial IST. Another 2 patients had evidence of a cytogenetic abnormality (16q deletion), but never progressed to MDS. (Note: averages presented as mean±SD) Conclusions/Methods With current IST regimens, AA is curative in the majority of pediatric patients. IST failure was associated with nonadherence to CSA treatment. For patients with confirmed clonal disease, it is possible that IST failure and the ultimate development of clonal disease are related. Disclosures No relevant conflicts of interest to declare.

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Bone Marrow Failure with 13q Deletion: A Distinct Clinicopathological Entity with Immune Pathophysiology,

Blood ◽

10.1182/blood.v118.21.3420.3420 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3420-3420

Author(s):

Kohei Hosokawa ◽

Takamasa Katagiri ◽

Naomi Sugimori ◽

Ken Ishiyama ◽

Yumi Sasaki ◽

...

Keyword(s):

Bone Marrow ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Survival Rates ◽

Snp Array ◽

Normal Karyotype ◽

Genetic Alterations ◽

Fish Analysis ◽

Hematopoietic Stem ◽

Who 2008

Abstract Abstract 3420 Background: Numerical karyotypic abnormalities such as −7/del(7q) and del(13q) are occasionally seen in patients with bone marrow (BM) failure who do not have typical signs of myelodysplasia. The WHO 2008 defined this subset of BM failure as MDS-U because of its likely association with a risk of evolving into leukemia, while the presence of isolated abnormalities including +8, del(20q), and -Y was not considered to be presumptive evidence of MDS. Previous studies showed that BM failure patients with del(13q) responded to immunosuppressive therapy (IST) and had a favorable prognosis (Ishiyama K et al, Br J Haematol; 117: 747. 2002; Sloand, JCO 2010). However, the clinical features of del(13q) BM failure remain unclear due to its low incidence as well as the frequently associated karyotypic abnormalities. Objectives/Methods: To characterize the clinicopathological features of patients with BM failure with del(13q), this study reviewed the clinical data of 1705 BM failure patients (733 with AA, 286 with MDS-RCUD, 149 with RCMD, 60 with MDS-U) whose blood was examined for the presence of glycosylphosphatidyl-inositol anchored protein (GPI-AP)-deficient granulocytes and erythrocytes from May 1999 through July 2010. Genomic DNA was isolated from the peripheral blood cells of 7 patients with 13q- and was subjected to SNP array-based genome-wide analysis for genetic alterations using GeneChip® 250K arrays to identify the gene locus that is commonly deleted as a result of 13q-. Results: The 13q- clone was found in 25 (1.5%) of the 1705 patients. All the 13q- patients were classified as MDS-U, due to the absence of significant dysplasia to fulfill the criteria for MDS defined by the WHO 2008 classification. BM was hypocellular in 17 patients and normocellular in 6. Seventeen patients had a clone with 13q- alone, while the remaining 8 patients had a clone with 13q- and other numerical abnormalities including –Y, +mar in 2, and −20, del(7q), +8, der(1;7) in 1. A significant increase in the percentage of GPI-AP- granulocytes was detected in 366 (50%) of 733 patients with AA and 115 (23%) of 495 patients with MDS. GPI-AP- cells were detected in all (100%) of the 17 patients with 13q- alone. On the other hand, the prevalence of increased GPI-AP− cells in patients with 13q- plus other abnormalities and in those with the normal karyotype was 38% (3/8) and 43% (405/937), respectively. Fifteen patients with 13q- alone were treated with IST (ATG + cyclosporine in 6 and cyclosporine ± anabolic steroid in 9) and all of them achieved either a PR or a CR, while in the patients with 13q- plus other abnormalities, the response rate to IST was 40%. A total of 106 patients with the normal karyotype were treated with ATG+CsA (48) or CsA±AS (58) and the response rates were 73% and 85%, respectively. None of the 17 13q- patients progressed to advanced MDS or AML during the follow-up period of 3 to 108 months (median: 52 months) while 2 of 8 patients with 13q- plus other abnormalities developed AML. The 5-year overall survival rates of the patients with 13q-, those with 13q- plus other abnormalities, and patients with a normal karyotype were 84%, 45%, and 91%, respectively. The percentage of 13q- clones increased in 5 patients, and decreased in 3 patients after successful IST. When GPI-AP- and GPI-AP+ granulocytes were subjected to a FISH analysis using a 13q probe (13q14.3), the 13q- clones were detected only in of GPI-AP+ granulocytes, suggesting that 13q- cells are derived from non-PIG-A mutant HSCs. SNP arrays identified 13q13.3 to 13q14.3 regions in all cases. Conclusions: MDS-U with 13q- is a benign BM failure syndrome characterized by a good response to IST and a markedly high prevalence of GPI-AP cells. Patients with this type of BM failure may be inappropriately treated with hypomethylating agents or hematopoietic stem cell transplantation from unrelated donors, which is associated with high therapy-related mortality. Therefore, del(13q) should be eliminated from the intermediate prognosis group defined by the IPSS, and BM failure with del(13q) should be managed as idiopathic AA. Disclosures: No relevant conflicts of interest to declare.

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Profilin 1 Is Essential for Retention and Metabolism of Hematopoietic Stem Cells in Bone Marrow

Blood ◽

10.1182/blood.v120.21.1224.1224 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1224-1224

Author(s):

Junke Zheng ◽

Chengcheng Zhang

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Actin Binding ◽

Wild Type ◽

Cell Fates ◽

Hematopoietic Stem ◽

Multiple Cell

Abstract Abstract 1224 How stem cells interact with the microenvironment to regulate their cell fates and metabolism is largely unknown. Here we show that, in a hematopoietic stem cell (HSC) -specific inducible knockout model, the cytoskeleton-modulating protein profilin 1 (pfn1) is essential for the maintenance of multiple cell fates and metabolism of HSCs. The deletion of pfn1 in HSCs led to bone marrow failure, loss of quiescence, increased apoptosis, and mobilization of HSCs in vivo. In reconstitution analyses, pfn1-deficient cells were selectively lost from mixed bone marrow chimeras. By contrast, pfn1 deletion did not significantly affect differentiation or homing of HSCs. When compared to wild-type cells, levels of expression of Hif-1a, EGR1, and MLL were lower and an earlier switch from glycolysis to mitochondrial respiration with increased ROS level was observed in pfn1-deficient HSCs. This switch preceded the detectable alteration of other cell fates. Importantly, treatment of pfn1-deficient mice with the antioxidant N-acetyl-l-cysteine reversed the ROS level and loss of quiescence of HSCs, suggesting that pfn1 maintained metabolism is required for the quiescence of HSCs. Furthermore, we demonstrated that expression of wild-type pfn1 but not the actin-binding deficient or poly-proline binding-deficient mutants of pfn1 rescued the defective phenotype of pfn1-deficient HSCs. This result indicates that actin-binding and proline-binding activities of pfn1 are required for its function in HSCs. Thus, pfn1 plays an essential role in regulating the retention and metabolism of HSCs in the bone marrow microenvironment. Disclosures: No relevant conflicts of interest to declare.

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G-CSF Treatment Induces Toll-Like Receptor Signaling and Regulates Hematopoietic Stem Cell Function

Blood ◽

10.1182/blood.v122.21.1181.1181 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1181-1181 ◽

Cited By ~ 1

Author(s):

Laura G. Schuettpelz ◽

Joshua N. Borgerding ◽

Priya Gopalan ◽

Matt Christopher ◽

Molly Romine ◽

...

Keyword(s):

Bone Marrow ◽

Cell Function ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Intestinal Flora ◽

Enrichment Analysis ◽

Gene Set Enrichment Analysis ◽

Tlr Signaling ◽

Hematopoietic Stem

Abstract Recent studies demonstrate that inflammatory signals regulate hematopoietic stem cells (HSCs). Granulocyte-colony stimulating factor (G-CSF) is often induced with infection and plays a key role in the stress granulopoiesis response. However, its effects on HSCs are unclear. Herein, we show that treatment with G-CSF induces expansion and increased quiescence of phenotypic HSCs, but causes a marked, cell-autonomous HSC repopulating defect. RNA profiling and flow cytometry studies of HSCs from G-CSF treated mice show that multiple toll- like receptors (TLRs) are upregulated in HSCs upon G-CSF treatment, and gene set enrichment analysis shows enhancement of TLR signaling in G-CSF-treated HSCs. G-CSF-induced expansion of phenotypic HSCs is reduced in mice lacking the TLR signaling adaptors MyD88 or Trif, and the induction of quiescence is abrogated in mice lacking these adaptors. Furthermore, loss of TLR4 mitigates the G-CSF-mediated HSC repopulating defect. Interestingly, baseline HSC function is also dependent on TLR signaling. We show that HSC long-term repopulating activity is enhanced in Tlr4-/- and MyD88-/- mice, but not Trif-/- mice. One potential source of TLR ligands affecting HSC function in the bone marrow is the gut microbiota. Indeed, we show that in mice treated with antibiotics to suppress intestinal flora, G-CSF induced HSC quiescence and hematopoietic progenitor mobilization are attenuated. Moreover, in germ free mice, HSC long-term repopulating activity is enhanced. Collectively these data suggest that low level TLR agonist production by commensal flora contributes to the regulation of HSC function and that G-CSF negatively regulates HSCs, in part, by enhancing TLR signaling. Our finding of enhanced TLR signaling upon G-CSF treatment, and the mitigation of G-CSF’s effects in mice deficient for TLR signaling or commensal organisms, suggest that TLR antagonists and/or agonists may ultimately be used clinically to enhance engraftment following bone marrow transplantation or applied toward the treatment of patients with bone marrow failure. Disclosures: No relevant conflicts of interest to declare.

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Utility of Telomere in Diagnosis of Bone Marrow Failure Syndromes

Blood ◽

10.1182/blood.v126.23.4793.4793 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4793-4793

Author(s):

Hasan Ahmed Abdel-ghaffar ◽

Hosam Zaghloul ◽

Ahmed El-Waseef ◽

Mohamed El-Naggar ◽

Mohamed Mabed ◽

...

Keyword(s):

Bone Marrow ◽

Telomere Length ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Quantitative Polymerase Chain Reaction ◽

Control Group ◽

Hematopoietic Stem ◽

Relative Telomere Length ◽

Bone Marrow Failure Syndromes ◽

Significant Difference

Abstract Background and aim of the work: Bone marrow failure syndromes (BMFS) includes inherited and acquired conditions. Inherited bone marrow failure includes a number of syndromes; with Fanconi anemia (FA) being the most common one of them. Telomeres are eroded with cell division, but in hematopoietic stem cell, maintenance of their length is mediated by telomerase. Short telomeres can result in instability of cell function where diseases occur. Bone Marrow Failure might be developed due to low telomerase activity or short telomeres. Our study is aiming to evaluate the utility of Real Time Quantitative-Polymerase Chain Reaction (RT-qPCR) in measuring the relative telomere length and its significance in diagnosis and prognosis of patients with BMFS. Materials and methods: The study includes 3 groups: A group of congenital BMF (29 patients), a group of acquired BMF (10 patients) and a third control group (15 cases). The relative telomere length is evaluated for them using RT-qPCR. Results: We have found that there is a significant difference in relative telomere length between congenital group and controls (p=0.001), also a significant difference between acquired group and controls (p= 0.029). However, there is no significant difference between congenital and acquired groups (p= 0.479). There is no significant correlation between the telomere length and the overall survival or prognosis of the patients of BMFS. Conclusion: We conclude that the telomere length is significantly altered in patients with BMFS whether being congenital or acquired compared to the control group. Disclosures No relevant conflicts of interest to declare.

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Excelent Option Therapy of BONE Marrow Failure in Fanconi Anemia Patients Withouth Full Match Donnor

Blood ◽

10.1182/blood.v128.22.5075.5075 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5075-5075 ◽

Cited By ~ 1

Author(s):

Lisandro L Ribeiro ◽

Samantha Nichele ◽

marco Antonio Bitencourt ◽

Ricardo Petterle ◽

Gisele Loth ◽

...

Keyword(s):

Bone Marrow ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Hematological Parameters ◽

Severe Neutropenia ◽

Cell Transplant ◽

Variable Degree ◽

Duration Of Treatment ◽

Hematopoietic Stem ◽

Hematological Response

Abstract The main cause of morbidity and mortality of FA pts is bone marrow failure (BMF), which usually arises in the first decade of life and progresses to transfusion dependence and severe neutropenia. Androgen treatment has been recommended for FA pts with BMF for whom there is no acceptable hematopoietic stem cell transplant donor. Oxymetholone and Danazol are frequently used in these pts. We retrospectively analyzed data on 67 FA pts who received oxymetholone or danazol for the treatment of their BMF. The starting dose was approximately 1mg/kg for oxy and 2-4mg/kg for danazol. The hematological parameters at the initiation of treatment were hemoglobin (Hb) < 8 g/dL and/or thrombocytes < 30.000/μl. Patients were diagnosed between 01.2005 and 01.2016. The median age was 10.5 ys (2.9 - 40ys). Gender: 39M/27F. The median duration of treatment was 18m (3m - 95m). Fifty-three patients (79%) showed hematological response and became transfusion independence at a median of 3 months after beginning oxymetholone (2-9m) and 5 months after danazol (4-7m). Two adult pts treated with danazol achieved total hematological response with 2.5mg/kg. Seven pts are stable after tapering and stopping androgen with a median follow up of 4 ys (6m-8.5ys). Fourteen pts did not respond to treatment (21%). Eleven pts received an HSCT and seven are alive and well. Three pts were not transplanted and two are alive but transfusion dependent and one pt died from CNS bleeding. All patients developed variable degree of virilization but it was more evident with oxymetholone therapy. Older age at starting therapy was related to less virilization. Conclusion: This study shows the largest number of FA pts treated with androgen up till now. Androgen is an effective and well-tolerated treatment option for FA pts who develop BMF with 79% of them showing transfusion free after 3-5 months. This response may give us time to search for better donors. Disclosures No relevant conflicts of interest to declare.

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Activation of Non-Canonical Immune Signalling Pathways Drives Marrow Failure in a Murine Model of MDS

Blood ◽

10.1182/blood.v124.21.3246.3246 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3246-3246

Author(s):

Rawa Ibrahim ◽

Joanna Wegrzyn ◽

Linda Ya-Ting Chang ◽

Patricia Umlandt ◽

Jeff Lam ◽

...

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Cell Line ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Signalling Pathway ◽

Gene Set Enrichment Analysis ◽

Mouse Bone Marrow ◽

Bone Marrow Niche ◽

Hematopoietic Stem

Abstract The Myelodysplastic Syndromes (MDS) are the most common hematological malignancies arising from stem/progenitor cells. MDS is characterized by ineffective hematopoiesis in one or more lineages of the bone marrow, resulting in peripheral cytopenias and the propensity to progress to either acute myeloid leukemia (AML) or bone marrow failure (BMF). The most common cytogenetic aberration associated with MDS is deletion of the long arm of chromosome 5. Many of the molecular events involved in the development of del(5q) MDS have been elucidated including haploinsufficiency of the gene encoding the ribosomal protein RPS14, responsible for the anemia observed, and haploinsufficency of the miRNAs miR-145 and miR-146a, which together target the innate immune signaling pathway, specifically, the Toll-like receptor-4 (TLR-4)signalling pathway. It has been demonstrated that overexpression of a target of miR-146a,TRAF6, in mouse bone marrow can recapitulate the phenotype of del(5q) MDS including the cytopenias and progression to BMF or AML. However, enforced expression of TIRAP, a miR-145 target gene, results in rapid BMF independent of TRAF6. The molecular and cellular mechanisms responsible for the differential outcome of overexpression of two genes that act within the same signalling pathway remain to be fully understood. We have identified several differentially expressed cytokines, including interferon gamma (IFNγ) and interleukin-10 (IL-10), following TIRAP overexpression compared with TRAF6 overexpression. Promoter methylation analysis has shown hypermethylation of key adaptors and signal transducers that lie between TIRAP and TRAF6 in the TLR-4 signalling pathway, suggesting activation of different pathways by TIRAP and TRAF6 overexpression. Indeed, blockade of TRAF6 and MyD88 did not inhibit TIRAP induced expression of these cytokines, suggesting that IFNγ and IL-10 production occurs in a TRAF6 and MyD88 independent manner. We identified IFNγ as the critical effector cytokine responsible for TIRAP mediated marrow failure. Gene set enrichment analysis has shown an enrichment of an IFNγ signature in MDS patients with a low risk of transformation to AML compared to healthy controls. Furthermore, interferon signatures were highly enriched in MDS patients compared to patients with AML, suggesting an important role for IFNγ signaling in driving MDS progression toward marrow failure as opposed to leukemic progression. IFNγ has been shown to inhibit components of the bone marrow niche by blocking RANK signalling in stromal cells such as osteoclast progenitors. Using coculture of TIRAP expressing bone marrow cells with the RAW264.7 monocyte cell line, a cell line that is capable of differentiation into osteoclasts, we found an inhibition in the ability of these cells to form osteoclasts compared to control. This provides the first line of evidence suggesting that immune signalling defects arising from genetic perturbations in the hematopoietic stem cell compartment can result in stem cell niche dysfunction leading to marrow failure. Disclosures No relevant conflicts of interest to declare.

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Acute Lymphoblastic Leukemia in a Patient with Monomac Syndrome/GATA2 Haploinsufficiency

Blood ◽

10.1182/blood.v126.23.3729.3729 ◽

2015 ◽

Vol 126 (23) ◽

pp. 3729-3729

Author(s):

Ashley Koegel ◽

Venee N. Tubman ◽

Inga Hofmann

Keyword(s):

Bone Marrow ◽

Acute Lymphoblastic Leukemia ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Lymphoblastic Leukemia ◽

Killer Cell ◽

Cell Transplant ◽

Hematopoietic Stem ◽

Monosomy 7 ◽

Definitive Therapy

Abstract Background: Heterozygous germline mutations in GATA2 have been described in three distinct conditions: 1) familial myelodysplastic syndrome (MDS)/ acute myeloid leukemia (AML), 2) Emberger syndrome which is characterized by lymphedema, warts and predisposition to MDS/AML, 3) MonoMac syndrome which is comprised of atypical nontuberculous mycobacterial infection, monocyte, and B and natural killer cell lymphoid deficiency. It is now recognized that these conditions represent a spectrum of hematopoietic, lymphatic and immune system disorders due to GATA2 haplosinsufficiency. MDS/AML due to GATA2 mutation shows a unique histopathology with characteristic dysplasia and is often associated with monosomy 7. Although many patients with GATA2 haploinsufficiency are initially asymptomatic the majority of patients will ultimately experience a significant complication such as severe infections due to immunodeficiency, pulmonary alveolar proteinosis (PAP), thrombotic events, bone marrow failure, MDS and progression to AML. Allogenic hematopoietic stem cell transplant (HSCT) is the only curative treatment for patients with GATA2 haploinsufficiency and those who develop MDS/AML. Here we report a unique patient who presented with with acute lymphoblastic leukemia (ALL) and was later found to have classical features of MonoMAC syndrome and GATA2 haploinsufficiency. Case Summary: A previously healthy 11 year-old girl presented with fever, cellulitis, and pancytopenia. Bone marrow biopsy and aspirate were diagnostic for B-precursor acute lymphoblastic leukemia (ALL) with associated monosomy 7 and the following karyotype: 45,XX,-7,del(9)(p13),del(10)(q24). She was treated on Dana Farber Cancer Institute (DFCI) Consortium ALL Protocol 05-001, achieving a morphological and cytogenetic remission. During induction, she developed necrotizing aspergillus pneumonia and molluscum contagiousum. Her planned course of therapy was abbreviated due to the development of restrictive lung disease associated with PAP and disseminated Mycobacterium kansasii infection. Serial off therapy bone marrow studies were obtained given poor count recovery and revealed significant morphologic dysplasia, most prominent in the megakaryocytes. These findings were reminiscent of those characteristically seen in patients with GATA2 haploinsufficiency. Her infectious complications, profound monocytopenia, PAP and bone marrow dysplasia raised concern for MonoMAC Syndrome. Sanger Sequencing of GATA2 revealed a point mutation in the regulatory enhancer region of intron 5 (c.1017+572C>T) confirming the diagnosis. More than 3 years following remission of ALL, she developed a bone marrow relapse with her initial clone. Given her diagnosis of GATA2 haploinsufficiency, HSCT was selected as consolidation therapy in second remission. She succumbed to complications of HSCT 4 months after transplantation. Conclusion: Patients with GATA2 haploinsufficiency show a heterogeneous clinical presentation and are at high risk for MDS/AML often associated with monosomy 7. The development of ALL in association with GATA2 haploinsufficiency has not been described in the literature. Hematologist and oncologists should be aware that ALL may be associated with GATA2 haploinsufficiency and should be attuned to the clinical, laboratory and histopathologic features of the MonoMAC syndrome that would prompt additional testing and potentially alter treatment regimens. As allogenic HSCT is the only definitive therapy for patients with GATA2 mutation, consideration of immediate HSCT following induction of remission should be considered in patients with ALL and GATA2 haploinsufficiency. Further, as patients with GATA2 mutations can be asymptomatic, it is imperative to screen family members for GATA2 mutations and offer genetic counselling prior to consideration as potential bone marrow donors. Disclosures No relevant conflicts of interest to declare.

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Genetics in Inherited Bone Marrow Failure Disorders

Blood ◽

10.1182/blood.v126.23.sci-1.sci-1 ◽

2015 ◽

Vol 126 (23) ◽

pp. SCI-1-SCI-1

Author(s):

Sioban Keel

Keyword(s):

Bone Marrow ◽

Aplastic Anemia ◽

Conflicts Of Interest ◽

Bone Marrow Failure ◽

Accurate Diagnosis ◽

Cell Transplant ◽

Medical Monitoring ◽

Hematopoietic Stem ◽

New Genes ◽

Increased Risk

The classical Inherited Bone Marrow Failure Syndromes (IBMFS) such as Fanconi anemia, Dyskeratosis Congenita, Shwachman-Diamond syndrome, and Diamond-Blackfan anemia are a heterogeneous group of disorders, all of which are characterized by impaired hematopoiesis, varying degrees of peripheral cytopenias and marrow hypoplasia and dysplasia. Many of these are associated with an increased risk of clonal dominance and evolution to myelodyplastic syndrome (MDS) and acute myeloid leukemia (AML). For the purposes of this talk, the familial MDS and acute leukemia predisposition syndromes are also included in the broad term IBMFS. The genes responsible for a subset of IBMFS have been identified and will be reviewed. However, the causative mutations in many patients presenting with seemingly inherited marrow failure remain unknown. Gene discovery in IBMFS has been difficult in large part due to the phenotypic heterogeneity of these syndromes. Some patients with IBMFS display a distinct clinical phenotype with associated syndromic abnormalities, others are variable and overlap with one another or with acquired MDS or idiopathic acquired aplastic anemia, and additional cases are more obscure and have evaded classification altogether. Accurate diagnosis of IBMFS inform patient care as it allows appropriate screening of siblings to avoid choosing an affected donor if marrow transplant is indicated and the selection of an appropriate transplant conditioning regiment to avoid undue toxicity. Additionally, accurate diagnosis allows appropriate medical monitoring and early intervention to successfully treat disease-specific non-hematologic medical complications. The application of next generation sequencing approaches for comprehensive genetic screening of IBMFS, including these cryptic or atypical presentations will be reviewed. In addition to providing accurate diagnoses in a subset of patients, genetic characterization in small family kindreds or even in single individuals presents unique opportunities to discover new genes and pathways contributing to dysfunctional hematopoiesis and clonal progression. The frequency of inherited mutations in known IBMFS genes among seemingly idiopathic acquired aplastic anemia patients or pediatric and younger adults with MDS referred for hematopoietic stem cell transplant will be reviewed. Future genetic studies are needed to characterize the secondary genetic events that lead to disease progression in IBMFS. Disclosures No relevant conflicts of interest to declare.

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