bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of β7 Integrin in Hematopoietic Stem Cell Trafficking.
Authors: Murakami Jodi , Xu Baohui , Franco Christopher B. , Galli Stephen J. , Weissman Irving L. , Chen Ching-Cheng 
Published: October 2019

Abstract
Abstract 2992
β7 integrin (β7), a well studied integrin chain, associates with either the α4 or αE chains to form a heterodimer on the cell surface. While it plays a key role in the migratory activities of hematopoietic progenitors and mature effector cells in the periphery, the overall importance of β7 in adult hematopoiesis remains controversial. We have recently identified a small subpopulation of hematopoietic stem cells (HSCs) in the bone marrow (BM) that express β7 integrin at steady state. These β7+ HSCs are capable of long-term reconstitution of both the lymphoid and myeloid compartments, ruling out the possibility that β7 expression on HSCs constitutes a marker for a homogeneous lineage-restricted progenitor population. We also found that these β7+ HSCs have an inherent advantage over β7− HSCs in competitive reconstitution assays. Loss of β7 results in the retention of HSCs in the BM and reduced HSC reconstitution potential. Quantitative real-time PCR revealed that β7 deficient HSCs downregulated the chemokine receptor Cxcr4. Furthermore, blockade of the α4β7 integrin ligand, mucosal addressin cell adhesion molecule 1 (MAdCAM-1), exhibits a similar phenotype in HSC retention and competitive reconstitution. Interestingly, we discovered that β7 deficient mice have enhanced survival and faster hematopoietic recovery after 5-fluorouracil-induced myeloablative stress, indicating that the decreased engraftment of β7 deficient HSCs may not due to a functional defect, but rather is more likely caused by impaired homing capabilities. Taken together, these data strongly suggest that β7 integrin is essential for HSC homing during the transplantation process.

Disclosures:
No relevant conflicts of interest to declare.
Impact of Thymic Function On Chronic Graft-Versus-Host Disease (cGVHD).
Authors: Mahadeo Kris M. , Shah Ami J , Masinsin Bernadette , Kapoor Neena , Abdel-Azim Hisham , Parkman Robertson 
Published: October 2019

Abstract
Abstract 3052
The initial analysis of the impact of cGVHD on thymic function used TREC analysis and demonstrated a sustained decrease in thympoiesis in hematopoietic stem cell transplant (HSCT) recipients with a history of cGVHD (Blood 97:1458, 2011). We have reported that HSCT recipients, who had the clinical resolution of their cGVHD, had increases in their resting regulatory T lymphocytes (rTreg) as compared to HSCT recipients with active cGVHD [ASH 2011]. The increase in rTreg lymphocytes suggested that clinical resolution of cGVHD might be due to improved thymic function, which resulted in the increased production of rTreg lymphocytes.
To measure the thymic function of pediatric HSCT recipients with cGVHD, we determined the frequency of recent thymic emigrants (RTE; CD4+, CD45RA+, CD31+) in the whole CD4 T lymphocyte population and the CD4 regulatory T (Treg; CD127-, CD25+) and CD4 conventional T lymphocytes (Tcon; CD127+, CD25+) subpopulations of normal individuals, HSCT recipients without a history of cGVHD (n =16) and HSCT recipients with a history of cGVHD (n=20). The frequency of RTE in total, Treg, and Tcon lymphocytes of the HSCT recipients with cGVHD was decreased (P=0.001) compared to HSCT recipients without a history of cGVHD but was the same as normal individuals. Thus, pediatric HSCT recipients with cGVHD have thymic function that is similar to normal individuals, but have decreased thymic reserves compared to HSCT recipients without cGVHD.
However, since rTreg lymphocytes (CD4+, CD127-, CD25+, CD45RA+, FoxP3+) represent only 20% of total Treg lymphocytes, we specifically determined the thymic contribution to rTreg lymphocytes. The RTE content of rTreg lymphocytes was determined in HSCT recipients with active or resolved cGVHD. The RTE content of the rTreg lymphocytes (as a percentage of total CD4 T lymphocytes) was similar in HSCT patients with both active and resolved cGVHD. Thus, the increase in rTreg lymphocytes present in HSCT recipients with the clinical resolution of their cGVHD is not due to an increase in the frequency of RTE in their rTreg lymphocyte population. Therefore, the increase in rTreg lymphocytes, that is associated with the clinical resolution of cGVHD, may be due to either their decreased conversion to Th17 lymphocytes or their decreased apoptosis.

Disclosures:
No relevant conflicts of interest to declare.
A Simple and Predictive Index for the Evaluation of Risk Stratification Following Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia in Remission.
Authors: Huang Xiao Jun , Wang Yu 
Published: October 2019

Abstract
Abstract 3066

Background.
The impact of risk-related parameters has not been defined in transplant settings.

Design and methods.
We analyzed the data of 255 consecutive patients (median age: 26) with acute myeloid leukemia (AML) in their first or second remission (CR1 or CR2) after haploidentical hematopoietic stem cell transplantation (HSCT).

Results.
Three parameters were found to be predictive of outcome: response after induction therapy, WBC count at diagnosis, and cytogenetics. These three factors were combined to yield two risk groups. The 2-year cumulative incidences of relapse for patients at low and high risk were 8% and 36% (p = 0.001), respectively. The three-year probabilities of leukemia-free survival (LFS) for these two groups were 80% and 52% (p = 0.001), respectively. Multivariate analysis for relapse and for LFS showed that not achieving CR after 2 courses of therapy was the strongest independent prognostic factor (p=0.001, and p=0.019, respectively). In addition, in a subgroup of patients with quantification of minimal residual disease (MRD) at the time of HSCT, positive MRD at this time point was correlated with a poor outcome.

Conclusions.
Our results suggest that the index is simple and predictive, so it might be applied to assist with risk-directed post-transplant therapy for young patients with AML in CR who have received myeloablative haploidentical HSCT.

Disclosures:
No relevant conflicts of interest to declare.
Anti-CD33 Chimeric Antigen Receptor Therapy For Acute Myeloid Leukemia
Authors: O'Hear Carol E. , Heiber Joshua , Geiger Terrence L. 
Published: October 2019

Abstract
CD33 is a protein expressed on most myeloid leukemia cells and committed myelomonocytic and erythroid progenitor cells, but not on other cell types. This makes it an attractive therapeutic target for acute myeloid leukemia (AML). CD33 positive cells can be specifically targeted for destruction through the use of a chimeric antigen receptor (CAR) expressed on cytotoxic T-lymphocytes (CTL). We have expressed a CD33-specific 41BB/CD3z second generation humanized chimeric antigen receptor (CAR) on human T cells by MSCV retroviral transduction, allowing for the generation of large numbers of CAR-modified CTLs. We assessed the activation and specific lytic ability of these CAR-modified T-cells by using murine and human CD33-transduced cell lines, as well as control CD33 negative lines. Our experiments show that anti-CD33 CAR CTLs specifically kill CD33-transduced 1498 and EL4 cells lines, with greater than 90% killing at 24 hours at a 1:1 effector to target ratio. These CTLs do not kill 1498 and EL4 cells that have not been transduced with CD33. In addition, anti-CD33 CTLs show significant (>90%) killing of multiple CD33 positive AML cell lines, including CHRF-288-11, HU-3, and UT-7, CMK, HL-60, Molm13, and Mv4-11. We have transduced a similar murine anti-CD33 CAR onto mouse CTLs. When these CTLs are injected into C57BL/6 mice with 1498 tumor cells transduced with CD33, the mice have a reduction in tumor burden compared with mice that have been injected with tumor cells and MSCV-negative control CTLs. This data suggests that our anti-CD33 CAR shows promise of therapeutic efficacy in the treatment of AML.

Disclosures:
No relevant conflicts of interest to declare.
Successful Engraftment of Hematopoietic Stem Cells into Immunocompetent Recipients Using Only Anti-CD117 Antibody and CD47 Blockade As Conditioning
Authors: Chhabra Akanksha , Ring Aaron M , Weiskopf Kipp , Weissman Irving L , Shizuru Judith A. 
Published: October 2019

Abstract
Bone marrow transplantation (BMT) is an efficacious therapy for many otherwise incurable hematologic malignancies and disorders that affect production of hematopoietic cells, including life-threatening anemias, and immunodeficiency syndromes. In a successful transplantation, clearance of bone-marrow niches must be achieved for donor hematopoietic stem cell (HSC) to engraft. Current methods to clear niche space rely on radiation and/or chemotherapy, which can impart toxic adverse effects that greatly limit the potential clinical utility of BMT. Thus, there is a major clinical need for safer conditioning regimens. To this end, a monoclonal antibody against CD117 (ACK2) has been shown to transiently deplete HSCs in immunocompromised mice and enable donor cell engraftment. However, this regimen has proved ineffective in immunocompetent animals. We hypothesized that HSC-depletion by this antibody may occur, in part, through Fc-mediated effector functions, such as antibody-dependent cellular phagocytosis (ADCP). We thus sought to enhance the ADCP activity of anti-CD117 antibodies by blocking the inhibitory CD47-SIRPα “don’t eat me” pathway. Consistent with previous reports, we found treatment of wild-type mice (C57BL/6) with ACK2 alone resulted in only modest and transient depletion of hematopoietic stem and progenitor cells (HSPCs). Strikingly, the addition of the CD47-antagonist CV1 (Weiskopf & Ring, 2013) in combination with ACK2 resulted in rapid and prolonged depletion of bone marrow HSPCs as well as clearance of the bone marrow niche. This depletion was accompanied by profound reductions in hematocrit and blood leukocyte counts not observed in mice treated with ACK2 alone. In support of the role of Fc receptors in the treatment regimen, depletion of HSCs was not observed in mice lacking functional Fc receptors, nor in animals treated with high-doses F(ab) fragments of ACK2. Finally, high levels of granulocyte chimerism (~70%) were achieved post-BMT in mice receiving the combination of ACK2 and CV1 as compared to no chimerism in animals treated with ACK2 alone (p-value <0.0001). Our results show that targeted biologic agents have the potential to replace the toxic preconditioning therapies that are currently clinically utilized. This can lead to safer preparative regimens, which will allow BMT to treat a broader patient population and larger spectrum of hematologic disorders.

Disclosures
Ring: Stanford University: PCT/US2013/021937 Patents & Royalties. Weiskopf:Stanford University: PCT/US2013/021937 Patents & Royalties. Weissman:Stanford University: PCT/US2013/021937 Patents & Royalties.
Metabolic Activity Distinguish Reserve and Primed HSCs
Authors: Li Zhenrui , He Xi , Paulson Ariel , Zhao Meng , Qian Pengxu , Tao Fang , Ding Wenxing , Dobrowsky Rick , Li Linheng 
Published: October 2019

Abstract
A population of reserve HSCs has been reported to be in a deep-quiescent (or dormant) state and function as a back-up population of HSCs to support life-time hematopoiesis (Li and Clevers, 2010; Wilson et al., 2008). Currently, characterization of reserve HSCs is mainly based on cell cycle quiescence, however, the metabolic state in reserve HSCs is yet to be defined. Here, we show that reserve HSCs maintain not only a quiescent state but also an overall low metabolic activity whereas the primed HSCs maintain still a quiescent state but primed at metabolic state. First, we used CD49b(Benveniste et al., 2010) to further separate conventional long-term (LT) HSCs (CD34-Flk2-Lineage-Sca-1+c-Kit+)(Yang et al., 2005) into CD49blo and CD49bhi subpopulations and confirmed their enrichment with previously identified dormant (Scl-H2B-GFP label retaining cells, LRCs), thus we termed CD49blo and CD49bhi subpopulations as candidates of reserve and primed HSCs. We then determined the cell cycle frequencies of reserve, primed, and ST-HSCs (Cd34+Flk2-LSK) respectively as once in 3 months, 3-4 weeks, and 3-4 days. Functionally, Reserve HSCs had on average 3.5-fold higher functional capacity compared with primed HSCs. RNA-seq analysis revealed that reserve HSC predominantly expressed a list of imprinting genes that associate with growth-restriction functions; primed HSCs expressed relatively-high number of genes involving in mitochondria fusion, organization, and function, while ST-HSCs expressed genes reflecting an active cycling state. Conducting metabolic assays, we found that reserve HSCs not only maintain quiescence but also maintain overall low metabolic activity in both glycolysis and mitochondrial capacity. In contrast, primed HSCs are in a quiescent state, but with their metabolic state primed as evidenced by an increased glycolytic activity and mitochondrial potential for subsequent active proliferating state in ST-HSCs. Intriguingly, our data suggests that the functionality of reserve HSCs correlates to metabolic state rather than cell cycle.

Disclosures
No relevant conflicts of interest to declare.
T-Cell Receptor Engagement Confers Resistance to Chemotherapy in T-Cell Lymphoproliferative Disorders
Authors: Wang Tianjiao , Polk Avery , Lu Ye , Wilcox Ryan A 
Published: October 2019

Abstract
Background: Chemotherapy resistance and primary refractory disease are common among patients with the more common peripheral T-cell lymphomas (TCL) treated with anthracycline-based chemotherapy. Antigen-receptor signaling activates a number of proliferation and survival pathways in normal lymphocytes. When activated in lymphomas, antigen-receptor signaling might confer resistance to chemotherapy. Until recently, the role of antigen-receptor signaling in B-cell malignancies was poorly understood. It is now appreciated that B-cell receptor (BCR) signaling is an important driver of B-cell lymphoma growth and survival, and represents an attractive therapeutic target in these lymphomas. In contrast, the potential role of T-cell receptor (TCR) signaling in T-cell lymphomagenesis is poorly understood. The observation that most (≈95%) TCLs express an intact TCR suggests that malignant T cells, like their B-cell counterparts, may benefit from antigen-receptor signaling.
Methods: TCL cell lines and primary patient specimens were subjected to TCR activation by CD3/CD28 beads. Gene expression profiling was performed by Affymetrix human gene 2.1 ST array at different time points (4, 8, 24 hours) following TCR engagement. Results were further validated by immunophenotyping by flow cytometry, western blot and cytokine measurement by enzyme-linked immunosorbent assay (ELISA). The proliferation and chemoresistance of the TCL cells following TCR engagement were determined by MTT assay.
Results: Microarray gene expression profiling of TCLs showed differential gene expression upon TCR engagement by CD3/CD28 beads at different time points. A total of 1274 genes were differentially expressed commonly in the patient specimens. Some of the differentially expressed genes were confirmed in independent samples by immunophenotyping (CD25, CD30, CD69, CD137, CCR4, GITR) and cytokine (IL2, IL13, IL10, IFNγ) release. Gene enrichment analysis of the common differentially expressed genes showed that pro-proliferation and pro-survival signaling pathways, including TCR (FDR: 0.05%), MAPK (FDR: 2.8%), NFκB (FDR: 0.1%) and cytokines (FDR: 0.03%) were enriched in TCR-engaged TCL cells. The activation of TCR and NFκB signaling in TCR-engaged TCLs was also confirmed by western blot and flow cytometry. More importantly, the proliferation of TCLs increased by 2-4 fold when cocultured with CD3/CD28 beads for 72 hours (p<0.01). In the presence of either vincristine or romidepsin, the viability of TCLs increased by 1.5-4 fold by CD3/CD28 bead treatment (p<0.01). TCR-dependent proliferation and chemoresistance in TCLs was significantly inhibited by agents targeting TCR and NFκB signaling pathways.
Conclusions: T-cell receptor dependent signaling pathways are rational therapeutic targets in the T-cell lymphomas.

Disclosures
No relevant conflicts of interest to declare.
Inferior Long-Term Outcome of Front-Line Hypomethylating Agent Compared to Supportive Care in Patients with Lower Risk Myelodysplastic Syndrome: Prosensity Score Matched Analysis
Authors: Sohn Sang Kyun , Moon Joon Ho , Jae Sook Ahn , Kim Hyeoung Joon , Song Moo kon , Shin Ho-Jin , Lee Won Sik , Lee Sang Min , Joo Young Don , Lee Ho Sup , Kim Yang Soo , Cho Yoon Young , Bae Sung Hwa 
Published: October 2019

Abstract

Background
Supportive care (BSC) including hematopoietic cytokines still remains an important component of treatment for lower-risk myelodysplastic syndrome (LR-MDS) including low or intermediate-1 risk by International Prognostic Scoring System (IPSS) even in the era of hypomethylating agents (HMA). The role of front-line HMA for LR-MDS has not been clearly defined yet. In the current study, we evaluated the long-term outcomes of patients with LR-MDS treated with front-line HMA compared to those treated with supportive care.
Methods
The data of 353 patients diagnosed with LR-MDS from Oct 1992 to Jul 2013 were retrospectively evaluated. The prognostic factors affecting overall survival were evaluated within all population. Then, we performed a case-constrol study using 122 patients with propensity score matched (PSM) population.
Results
Initial patient population (n=353) included 110 patients treated with BSC and 243 treated with HMA. Patients characteristics (age, gender, IPSS risk groups, IPSS blast score, IPSS cytopenia score) were similar between two groups, however, ECOG performance status (PS) and IPSS cytogenetic score were biased between two groups. ECOG-PS 2-3 were 32 patients (29.1%) in BSC and 20 (9.3%) in HMA group (p<0.001) and IPSS cytogenetic score °Ã0.5 were 27 patients (25.2%) and 33 (14.6%) in HMA group (p=0.032). In the multivariate analysis, ECOG-PS 2-3 (HR 4.586, p<0.001), IPSS blast °Ã0.5% (HR 2.549, p<0.001) and front-line HMA therapy (HR 2.019, p=0.006) were unfavorable factors affecting OS. Using PSM population, we performed a case-control study comparing the outcomes of 61 patients in each group who treated with BSC and front-line HMA. Patient characteristics were well balanced between two group. In the multivariate analysis, ECOG-PS 2-3 (HR5.036, p<0.001), IPSS blast °Ã0.5% (HR 2.157, p=0.035), and first-line HMA therapy (HR 2.213, p=0.026) were still unfavorable factors for OS. The 5-year OS rate was 62.5±10.8% in BSC group and 41.0±7.4 in HMA group, respectively (p=0.049).
Conclusion
Front-line HMA for patient with LR-MDS showed inferior long-term outcomes compared to BSC in PSM population. The role of front-line HMA should be elucidated in prospective studies on LR-MDS patients.
Figure. Overall survival between BSC and HMA groups in propensity score matched population Figure. Overall survival between BSC and HMA groups in propensity score matched population

Disclosures
Off Label Use: Rituximab has been used as an off-label drug for adult ALL, and has been provided by Roche Inc. for scientific purpose. .
Multiple Myeloma Cells Induce Mitochondrial Stress Response in Bone Marrow Mesenchymal Stromal Cells
Authors: Berenstein Rimma , Blau Olga , Nogai Axel , Wächter Marlies , Schmidt-Hieber Martin , Pezzutto Antonio , Dörken Bernd , Blau Igor Wolfgang 
Published: October 2019

Abstract
Introduction: Interaction of multiple myeloma (MM) cells with the surrounding bone marrow mesenchymal stromal cells (BMMSCs) is crucial for MM proliferation and survival. We have previously reported that in vitro cultured MM-BMMSCs display premature stress-induced senescence and constitutive changes in gene expression (Blood, 2013). Because mitochondrial oxidative stress could be the reason for senescence in MM-BMMSCs we investigated the metabolic interplay between MM-BMMSCs and MM cells.
Methods: In this study we analyzed 51 patients with MM, 4 patients with monoclonal gammopathy of undetermined significance (MGUS) and 10 healthy donors. Investigations ofNAD-dependent deacetylase sirtuin-3 (SIRT3) expression and mitochondrial mass were performed with SYBR-Green Real-Time PCR and relative quantification by linear regression. In addition, 20 co-cultures of MM-BMMSCs and KMS12-PE MM cell line were carried out. After incubation for 72 h SIRT3 expression in MM-BMMSCs was analyzed. Moreover, reactive oxygen species (ROS) production and mitochondrial membrane potential (ΔΨM) in co-cultured KMS12-PE cells and MM-BMMSCs were investigated by FACS analysis.
Results: MM-BMMSCs displayed a 2-fold decrease in SIRT3 expression and a 2-fold increase in mitochondrial mass compared to healthy donor BMMSCs (HD-BMMSCs). These changes were not detected in MGUS-BMMSCs, suggesting an association with disease progression. Furthermore, the increase in mitochondrial mass could be induced by oxidative stress in MM-BMMSCs and is a feature of senescent cells. Because SIRT3 is a major regulator of the mitochondrial function, reduced expression could account for accumulation of reactive oxygen species in MM-BMMSCs cultured in vitro. Interestingly we found a 4-fold upregulation of SIRT3 expression in MM-BMMSCs when co-cultured with KMS12-PE myeloma cells. This indicates that cell-cell-contact to MM cells influences the mitochondrial function in MM-BMMSCs and induces mitochondrial stress response. Moreover, we found decreased levels of ROS and ΔΨM in co-cultured KMS12-PE myeloma cells and MM-BMMSCs compared to cells cultured alone. Therefore, MM cells seem to modify the mitochondrial function and induce expression of antioxidants in MM-BMMSCs aimed at reducing ROS levels and increasing cell proliferation and survival pathways in both cell types.
Conclusion: Our results indicate that MM cells influence the mitochondrial function of MM-BMMSCs. This interaction leads to reduced ROS levels in both cell types and could support their survival and growth. Moreover, the sustained induction of mitochondrial stress response could be the reason for premature senescence in MM-BMMSCs when separated from MM cells. Therefore, MM therapy outcome may be improved through the disabling of the metabolic interplay between MM cells and MM-BMMSCs.

Disclosures
No relevant conflicts of interest to declare.