bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deletions of 5q Promote Genome Instability in TP53-Mutant MDS/AML
Authors: Reilly Andreea , Busch Stephanie , Abkowitz Janis L. , Becker Pamela S. , Doulatov Sergei 
Published: November 2019

Purpose
TP53 mutations in myeloid neoplasms (MDS/AML) are associated with high-risk disease, poor outcome, and complex karyotype. The molecular mechanisms which lead to global chromosomal instability remain poorly understood. Loss of 5q [del(5q)] is the most frequent cytogenetic abnormality associated with TP53 mutations suggesting that haploinsufficiency of genes on 5q contributes to chromosomal instability.
Methods
We reprogrammed MDS/AML patient samples to establish genetically accurate iPSC lines from preleukemic subclones. We generated iPSCs with TP53 mutations and del(5q), differentiated them to hematopoietic progenitors (HPCs), and determined the contribution of del(5q) to genome instability.
Results
By reprogramming MDS/AML complex karyotype patient samples, we identified iPSCs with heterozygous TP53 mutations (TP53-only), as well as iPSCs with TP53 mutations and del5(q22-q31) (TP53;del5q), and an otherwise normal karyotype. HPCs derived from TP53;del5q iPSCs had decreased multilineage differentiation potential compared to the TP53-only HPCs. Gene expression analysis of TP53;del5q HPCs revealed downregulation of genes involved in chromosome segregation and DNA damage repair. Following irradiation TP53;del5q cells had significantly delayed DNA damage repair kinetics. In order to evaluate the effects of TP53 and del(5q) on chromosomal segregation during stress, we arrested the cells in mitosis by disrupting the mitotic spindle and quantified the induction of micronuclei, a marker of chromosomal instability that occurs due to lagging chromosomes. TP53;del5q cells had an increased frequency of micronuclei formation compared to TP53-only cells. We also detected micronuclei in primary AML patient samples. Micronuclei in iPSC-HPCs and primary patient cells had disrupted nuclear envelope and DNA damage marked by y-H2AX.
Conclusions
Our reprogramming approach revealed that TP53 mutations are disease-initiating and frequently followed by 5q loss. We propose that del(5q) cooperates with mutant TP53 to promote genome instability via two distinct mechanisms: classical double-stranded break repair and micronuclei formation. The latter is associated with global chromosomal instability, aneuploidy, and chromothripsis. We propose that loss of 5q accelerates genome instability in TP53-mutant cells which over time impedes normal hematopoietic differentiation and leads to complex karyotype.

Disclosures
Becker: The France Foundation: Honoraria; Accordant Health Services/Caremark: Consultancy; AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding.
ADAMTS13 Immunohistochemical Expression in Normal and Diseased Equine Tissues
Authors: Flax Sherri 
Published: November 2019

ADAMTS13 is a metallopeptidase primarily synthesized in the liver. Its main function is to cleave von Willebrand factor (VWF) on the endothelial surface, and thus regulate platelet adhesion at the sites of vascular injury; VWF acts as a scaffold at the site of injury for platelet activation, platelet binding, and clot formation. Platelet activation also results in the release of platelet-dense granule components (such as cytokines, pro- and anti-inflammatory factors and other bioactive molecules) that are essential regulators of coagulation, but are also associated with inflammation.
Reduced activity of ADAMTS13 is found in human patients with acquired thrombotic thrombocytopenic purpura (TPP), sepsis, and DIC. Both human TTP and equine colic are histologically characterized by the presence of microthrombi. Cleavage of VWF is dependent upon allosteric activation of ADAMTS13, which is broadly conserved in many animals, including horses. Human TTP and equine idiopathic colic share several interesting clinical similarities. Both have seasonal variations, typically in summer, can be associated with viral and bacterial infections, may be hereditary, have autoimmune associations, and recur. Both TTP and equine colic are clinically characterized by fever, abdominal pain renal failure, and neurologic symptoms. Microangiopathy is the predominant pathology in both TTP and equine colic.
Using tissues obtained from thirteen horses euthanized for non-thrombotic conditions, immunohistochemical stains indicate the presence of ADAMTS13 in equine liver and colon. Furthermore, in one horse with colic, immunohistochemical staining of the resected colon indicates the presence of ADAMTS13 in the aboral margin (Figure 1) and the absence ADAMTS13 staining in the diseased tissue.
These findings suggest that equine colic may be an animal model of thrombotic microangiopathy, very similar to TTP. Future studies will investigate immunohistochemical detection of ADAMTS13 in human tissues.
Figure 1

Disclosures
No relevant conflicts of interest to declare.
Study of the Role of Hydroxychloroquine in Immunomodulation and Control of Hypercoagulability in Patients Diagnosed with Primary Antiphospholipid Syndrome
Authors: Mangolin Sabrina , Mazetto Bruna M , Annichino- Bizzacchi Joyce Maria , Orsi Fernanda Andrade 
Published: November 2019

Aim: Hydroxychloroquine (HCQ) could form an alternative treatment for thrombotic primary antiphospholipid syndrome (t-PAPS) if HCQ is proven to reduce the risk of thrombosis. We investigated whether HCQ affects immune response and lipid metabolism in t-PAPS.
Methods: HCQ at 400mg/day was given to anticoagulated t-PAPS patients for 6 months. After HCQ withdrawal and a wash-out period of 6 months, the same patients were followed for further 6 months. Blood samples taken at baseline and at the end of each 6-months follow-up period were analyzed employing flow cytometry and biochemical assays.
Result: Twenty-seven patients were included, mean age was 44 years, 78% were female, 44% had hypertension, 44% dyslipidemia, 7% diabetes, 77% had venous thrombosis, 30% arterial thrombosis and 33% recurrent thrombosis. Triple aPL positivity was detected in 37%. Lymphocyte counts decreased during HCQ use (mean change -318/mm3; 95%CI -438 to -198) and were not changed during non-HCQ use period. CD8+ and CD4+ cells decreased during HCQ treatment and remained unchanged during non-treatment period. In contrast, TREG (FoxP3+) cells increased during HCQ treatment (mean change 0.2U; 95%CI 0 to 0.4) and decreased in the period of non-HCQ treatment (mean change -0.6U; 95%CI -0.9 to -0.1). Serum glucose, total cholesterol and low density lipoprotein cholesterol decreased during HCQ use (7%, 9% and 12% respectively) and did not change substantially during non-HCQ period.
Conclusion: HCQ reduces cytotoxic T lymphocytes, increases regulatory T lymphocytes and decreases LDL cholesterol and serum glucose levels in t-PAPS. These HCQ may contribute to reduce the risk of thrombosis.

Disclosures
No relevant conflicts of interest to declare.
Iron Overload Impairs Bone Marrow Mesenchymal Stromal Cells from MDS Patients and Promotes Leukemia Transformation
Authors: Fu Rong , Zhaoyun Liu , Huang Lei , Liu Hui , Shao Zonghong , Ding Kai 
Published: November 2019

Bone marrow microenvironment plays an important role in the development of myelodysplastic syndrome (MDS). Iron overload (IO) may be related to the prognosis of the MDS patients. The effects of IO damaging mesenchymal stromal cells (MSCs) from MDS patients and promoting leukemia transformation were investigated. In our study, the IO group showed the decreased quantity and weakened abilities on proliferation and differentiation of MSCs. The gene expressions of VEGFA, CXCL12 and TGF-β1 in MSCs regulating hematopoiesis were significantly downregulated in IO group. The levels of reactive oxygen species (ROS) and apoptosis in IO group were significantly higher than those in non-iron overload (NIO) group, with highly expressed caspase3 and β-catenin. Meanwhile, the damages of MSCs caused by IO could be partially reversed by antioxidant or iron chelator. Due to the higher gene mutation frequency in IO group, the effects of IO promoting leukemia transformation were investigated. The IO MDS/AML group had a lower quantity of MSCs compared with IO MDS group, with significantly decreased expression of p-AKT. However, there was no significant differences in apoptosis, gene expressions of VEGF, CXCL12 supporting hematopoiesis, and β-catenin involving leukemia transformation in MSCs between them. In conclusion, IO damages MSCs of MDS patients by inducing ROS related apoptosis and activating caspase3 signals, which could be partially reversed by antioxidant or iron chelator. The increased genetic mutations and activated β-catenin signals in MSCs of MDS patients caused by IO may involve in promoting leukemia transformation.

Disclosures
No relevant conflicts of interest to declare.
Tandem CAR T Cells Targeting CD19 and CD22 Is a Safe and Highly Efficacious Treatment for Relapse/ Refractory ALL Patients
Authors: Tang Xiaowen , Kang Liqing , Qi Wei , Cui Wei , Dai Haiping , Li Zheng , Yin Jia , Qu Changju , Xu Ting , Zhu Xiaming , Yu Lei , Wu Depei 
Published: November 2019

Background: CAR-T immunotherapy has shown remarkable promising results for relapsed/ refractory (R/R) acute lymphoblastic leukemia (ALL). However, CD19-targeted CAR T cell therapy for R/R ALL has a relapse rate of approximately 50% at 1 year after CART therapy, and the most common mechanism of relapse is due to CD19 antigen loss or decreased target expression on the surfaces of the lymphoblastic leukemia cells. Potential approaches to overcome this challenge include engineering CAR T cells to achieve multispecificity and to respond to lower expression levels of target antigens by dual target CAR T strategies.
Objective: In order to evaluate the efficacy and safety of CD19/CD22 dual target CAR T cells for R/R ALL patients to determine if targeting multiple antigens can prevent treatment failure and improve response rates and durability of response.
Method: A novel CAR T cells with tandem targeting CD19 and CD22 antigens and a third generation CAR construct of CD28 and OX40 co-stimulatory domains were administered to 23 patients with R/R ALL with a median age of 24(6-56)years. High-risk patients were enrolled in this cohort, including 10 with BCR-ABL+ALL (6 of 10 with T 315I mutation), 4 with TP53 mutation, 2 with Ph-like ALL and 3 with relapsed ALL post allo-HSCT. The patients received a single infusion of CAR T cells with dose escalation schedule:10%--30%--60%. The median infusion dose of CAR T cells was 1 (0.5- 2.5) ×107cells/kg.
Results: The median follow-up was 9 (3.5-20) months. The day 28 CR/CRi rate was 100% with21/22 (95.5%) molecular remission. Six-month OS was 94.4% and RFS was 76.9%. One-year OS was 57.2% and RFS was 67.3%. One-year OS of high tumor burden (BM blast&gt; 30%)(15/22) and low tumor burden(BM blast≤30%)(7/22) was 47.5% and 75% respectively (p&gt;0.05). The 1-year OS of the CAR T- to- allo-HSCT group(14/22) was better than that of the non-transplant group(8/22) (OS 72.9% vs. 26.7%, p = 0.116). The cumulative relapse rate of 6 months and 1 year were 23.1% and 32.7% respectively. The overall incidence of CRS were 91% included 22.7%grade III CRS ,4.5% grade IV CRS and 0% severe CRES. Only one patient presented MAH syndrome and was cured with low dose dexamethasone. There was no CAR T-related death.
Conclusions: The tandem CD19/CD22 dual target CAR T cells therapy is a safe and high efficacy treatment for R/R ALL patients. It is possible that multi-targeted CAR-T cell therapy may overcome this resistance mechanism and improve clinical outcomes.

Disclosures
No relevant conflicts of interest to declare.
Histopathology of Chronic Kidney Disease after Allogeneic Hematopoietic Cell Transplantation: A Multi-Center Observational Study of Kidney Biopsies
Authors: Chen Feng , Wu Depei , Wang Ran , Huang Xianghua , Li Xiaozhong , Huang Chaoxing 
Published: November 2019

Background Renal dysfunction is a common complication of allogeneic hematopoietic cell transplantation (Allo-HCT) with proven negative impact on early and long-term mortality. The cumulative incidence of chronic kidney disease(CKD) after Allo- HCT varies from 13~60% in adult studies to as high as 62% in children. So far, most knowledge on chronic renal impairment in the context of Allo-HCT is based on clinical and laboratory findings. Causes of CKD are diverse, usually overlapping, and poorly understood. Kidney biopsies are performed in less than 5% patients with CKD, the pathophysiology of idiopathic CKD remains obscure. We conducted a multi-center clinicopathologic study of Allo-HCT patients with CKD to described the histopathologic spectrum of renal manifestations.
Methods and Results Between 2005 and 2018, 24 recipients(17 males and 7 females) of Allo-HCT underwent kidney biopsy for either proteinuria or deterioration of kidney function at four centers. The median age was 43.8 (7.2~54.3) years, and the median time from Allo-HCT to kidney biopsy was 17.2(2.0~74.6)months. Evidence for GVHD was found in 20 (83.3%) patients. Among the 24 patients, 10 patients had a large amount of proteinuria (24-hour urine protein > 3.5 g/L), and 12 patients had elevated serum creatinine (Scr >110μmol/l). The most common pathological findings of kidney biopsy were GVHD (n=8), membranous nephropathy (MN, n=5), thrombotic microangiopathy (TMA, n=4), BK virus nephropathy (n=2), and we also found ischemic nephropathy, chronic interstitial nephritis, minimal change disease (MCD), GVHD with TMA, MN with focal segmental glomerular sclerosis (FSGS), MCD with acute tubular injury, BK virus nephropathy combined with calcineurin inhibitor nephrotoxicity in one case. The follow-up data showed 3 died of recurrent malignancy, 6 loss to follow-up , the median follow-up time was 18.3(12.3~120.2)months. Of the 18 patients, 8 (44.4%) had an estimated glomerular filtration rate (eGFR) of less than 60 ml/(min1.73m2), 5 (27.8%) still had moderate proteinuria.
Conclusions A wide spectrum of renal pathologic findings can be observed in Allo-HCT patients. Either severe proteinuria or elevated serum creatinine were common presentations in this unique setting, which can be due to GVHD , MN, TMA, BK virus nephropathy , MCD, FSGS, and overlapping lesions. Kidney biopsies are necessary to establish the underlying cause of CKD in Allo-HCT patients.

Disclosures
No relevant conflicts of interest to declare.
Using Circ-ANAPC7 As a Novel Type of Biomarker in the Monitoring of Acute Myeloid Leukemia
Authors: Shen Ying , Jia Yachun , Zhang Ru , Chen Hongli , Feng Yuandong , Wang Fang-Xia , Zhao Wanhong , Wang Jianli , He Aili , Yang Yun , Xu Yan 
Published: November 2019

Introduction: Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the clonal proliferation of immature myeloid progenitor cells in the bone marrow, compressing normal blood cell production and leading to bone marrow failure ultimately. Overwhelming evidence has established that non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) have great role in AML pathogenesis. Circular RNAs (circRNAs) that occupy gene expression at the transcriptional or post-transcriptional level have great potential to be biomarker for types of cancers. We have screened one altered circRNA named circ-ANAPC7 in AML before. In this study, we aimed to validate its expression by enlarging sample size and illuminating the diagnostic and monitoring value of circ-ANAPC7 in AML.
Methods: Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was supposed to confirm the expression of circ-ANAPC7 of AML patients. The sequences of circ-ANAPC7 primers were as follows: 5′- GGGAGCAGCACTTAGGAACAT -3′ (sense) and 5′-AAAGCTGGTACTTCTGAGGTGG-3′ (antisense). Receiver operating characteristic (ROC) curve was carried out to evaluate the diagnostic value. Overall survival rate and event-free survival rate were estimated by the Kplan-Meier analysis and compared using the log-rank test. All tests were two-sided, and P < 0.05 was defined as a significant difference.
Results: The expression level of circ-ANAPC7 in newly diagnosed AML was significantly higher than CR patients and iron deficiency anemia (IDA) control group (P < 0.001) (Figure 1A). Furthermore, we chose 24 AML patients who undergo the condition of newly diagnosed AML, CR and relapse to dynamical monitor the expression of circ-ANAPC7. We discovered that circ-ANAPC7 expression level changed accompanied with the disease condition transformation. It was high expressed in newly diagnosed and relapsed AML patients. When patients got CR, the expression level of circ-ANAPC7 decreased (P < 0.05). In the continuous CR patients, it remained in a minimal level (Figure 1C). ROC curve analysis revealed that circ-ANAPC7 has significant value of AML diagnosis (AUC = 0.915, P < 0.001) (Figure 1B). Moreover, we conducted survival analysis to explore long-term effect of circ-ANAPC7 expression in AML patients. The result revealed that circ-ANAPC7 expression was not related to overall survival (OS) and disease-free survival (DFS) of AML patients (P > 0.05) (Figure 1D).
Conclusions: We validated that circ-ANAPC7 was upregulated in AML patients. The clinical analysis revealed that circ-ANAPC7 may be a predictive index for diagnosing and supervising early recurrence of AML. What's more, additional molecular mechanisms and biological functions of circ-ANAPC7 merit deeper investigation.
Figure 1

Disclosures
No relevant conflicts of interest to declare.
Life History of Normal Human Lymphocytes Revealed By Somatic Mutations
Authors: Machado Heather E , Øbro Nina Friesgaard , Mitchell Emily , Davies Megan , Green Anthony R , Saeb-Parsy Kourosh , Hodson Daniel James , Kent David , Campbell Peter J 
Published: November 2019

Introduction: Mature blood cells harbor a mixture of mutations inherited from ancestral hematopoietic stem cells (HSCs) and mutations accumulated after maturation. The landscape of these somatic mutations in normal blood is poorly mapped, with questions as simple as "how many mutations does a memory T cell accumulate throughout life?" remaining unanswered. This gap in our knowledge is particularly relevant for hematopoietic malignancy- while we know that lymphomas derive from lymphocytes of particular stages of differentiation, we do not know if the patterns we see are reflected in their normal counterparts.
Results: In order to characterize normal somatic mutation in lymphocytes, we performed single-cell expansion and whole genome sequencing of over 600 T and B lymphocytes and 200 HSC and progenitor cells across 5 individuals (ages 0-85). All lymphocyte subsets show increased mutation burden with respect to HSCs across all classes of variants (Figure 1). Some of this increase can explained by lymphocyte-specific mutational processes, such as the activity of RAG, accounting for at least 20% of observed structural variants. We also find a striking variation in mutation burden within and between lymphocyte subsets. Microenvironment specific mutational processes dominate the observed differences. Examples of this include germinal center ("non-canonical AID") mutations in memory B cells and UV-like mutations in memory T cells (putatively skin resident cells). Naive B and T cells show a lack of variation in discrete mutational patterns relative to their memory counterparts, and have mutational profiles and mutation burdens more similar to that of HSCs. We also observe differences in the mutational patterns between B and T cells that are indicative of the increased divergence of T lymphocytes from the HSC pool. In general, the mutation burden we observe in normal lymphocytes approach those seen in lymphoma.
Conclusions: Our work highlights the substantial genetic diversity in normal lymphocytes, with some cells accumulating thousands of mutations on top of those inherited from the HSC compartment. These mutations can be used to describe the life history of each individual lymphocyte including their exposure to specific microenvironments. Our findings shed light on the biology of these cells and will help differentiate between normal and disease processes.
Figure 1

Disclosures
No relevant conflicts of interest to declare.
iPLA2β Contributes to Activation of Human and Mouse Platelets Via ITAM Receptors Fcγ RIIA and GPVI
Authors: Abraham Shaji , Patel Pravin , Naik Ulhas P. , McKenzie Steven Edward 
Published: November 2019

Platelet activation by ITAM receptors contributes to hemostasis, thrombosis, vascular integrity and host defense. In the course of our studies of FcγRIIA-mediated platelet activation, we became interested in those mechanisms that require neither full Syk activation nor changes in intracellular calcium. Calcium-independent phospholipase family member iPLA2β has been observed to modulate phospholipid remodeling and second messenger generation in human platelets (Beckett, Thromb Res 2007; Duvernay, Biochem 2015), while iPLA2γ has been studied in knockout mouse platelets (Yoda, JTH 2014) with modest effects noted on thrombosis and hemostasis. These enzymes do not require increased cytoplasmic calcium for their activity in cleaving the acyl group from the sn2 position of phospholipids to yield a free fatty acid and a lysophospholipid. However, the precise role of iPLA2β in human and mouse platelet activation has not been elucidated. Neither has the contribution of iPLA2β in the response to FcγRIIA-mediated activation been reported.
We identified the presence of iPLA2β protein in western blots of human and FcγRIIA transgenic mouse platelets. Of interest, multiple isoforms arising from proteolytic cleavage were detected. We treated washed human and FcγRIIA transgenic mouse platelets with agonists to FcγRIIA (IV.3 + GAM) and to GPVI (collagen or collagen-related peptide) in the absence and presence of pharmacologic inhibitors of iPLA2β. At a range of agonist doses up to 3X threshold, we observed significant inhibition of aggregation, dense granule secretion and alpha granule secretion (p<0.05 vs. vehicle only, n = 3 to 4 each). Inhibition occurred with either S-BEL (bromo-enolactone) or with FKGK18 (a fluoroketone), two chemically distinct iPLA2β inhibitor molecules with different modes of action. The IC50 for S-BEL was found to be 1.02 uM for human FcγRIIA, 2.04 uM for human GPVI, and 2.76 uM for transgenic mouse FcγRIIA activated platelets. FKGK18 was less potent, with IC50s at 7.88 uM for human FcγRIIA. In contrast, iPLA2γ inhibitor R-BEL was able to inhibit FcγRIIA -mediated activation, but at an IC50 of 2.62 uM. Notably, iPLA2β inhibition could eliminate ATP secretion from dense granules downstream of FcγRIIA and GPVI activation. When we added ADP to FcγRIIA stimulation in the presence of inhibitory doses of S-BEL, we overcame the inhibition.
We have identified for the first time that iPLA2β contributes to aggregation and secretion of both human and FcγRIIA transgenic mouse platelets. The platelets were slightly more sensitive to FcγRIIA than to GPVI inhibition. In other activatable secretory cells, iPLA2β plays both a homeostatic and signaling role. The mechanisms of iPLA2β action in platelets merit further study. Studies are in progress with genetic knockdown and knockout of the enzyme, to complement the findings with inhibitors.

Disclosures
No relevant conflicts of interest to declare.