Cells Of Myelodysplastic Syndromes Patients Research Articles

The CSN5/HSF/SPI1/PU.1 Axis Regulates Cell Proliferation in Hypocellular Myelodysplastic Syndrome Patients.

This study explored the relationship between the activation of the jak/stat3 signaling pathway and the CSN5 gene transcript and protein expression levels in the hematopoietic stem cells of patients with myelodysplastic syndromes (MDSs). This study also aimed to investigate the correlation between the expression level of CSN5 and the deubiquitination of HSF1, as well as the transcript level of the spi1/pu.1 genes to explore the pathogenesis of MDS. We isolated cells from normal individuals and MDS patients, and the mRNA and protein expression levels of spi1/pu.1 in cd34+ cells (hematopoietic stem cells) were measured by PCR and western blotting, respectively. A ChIP assay was used to detect the binding of HSF1 to the spi1/pu.1 promoter in cd34+ cells. The ubiquitination of HSF1 in cd34+ cells was detected by CO-IP. The binding of HSF1 and Fbxw7α was detected in in cd34+ cells by CO-IP. The binding of HSF1 and CSN5 was evaluated. A luciferase reporter assay was used to detect the effect of STAT3 on CSN5 promoter activation in cd34+ cells. Western blotting was used to detect the phosphorylation of STAT3 in cd34+ cells of MDS patients. The binding of STAT3 and C/EBP beta in cd34+ cells was detected by CO-IP. Inhibition of SPI1/PU.1 expression was observed in MDS samples with low proliferation ability. Further experiments proved that phosphorylation of STAT3 affected CSN5 function and mediated the ubiquitination of HSF, the upstream regulator of SPI1/PU.1 transcription, which led to the inhibition of SPI1/PU.1 expression. Restoration of CSN5 rescued the inhibition of HSF1 ubiquitination, causing SPI1/PU.1 transcription to resume and increasing SPI1/PU.1 expression, promoting the recovery of cell proliferation in hypocellular MDS. Our research revealed the regulatory role of the CSN5/HSF/SPI1/PU.1 axis in hypocellular MDS, providing a probable target for clinical intervention.

The Distribution and Significance of Activated T Cells and Lymphocyte Subsets in Myelodysplastic Syndrome

To investigate the distribution of bone marrow lymphocyte subsets in patients with myelodysplastic syndrome(MDS),the proportion of activated T cells with immunophenotype CD3+HLA-DR+ in the lymphocytes and its clinical significance, and to understand the effects of different types of MDS, different immunophenotypes, and different expression levels of WT1 on the proportion of lymphocyte subsets and activated T cells. The immunophenotypes of 96 MDS patients, the subsets of bone marrow lymphocytes and activated T cells were detected by flow cytometry. The relative expression of WT1 was detected by real-time fluorescent quantitative PCR, and the first induced remission rate (CR1) was calculated, the differences of lymphocyte subsets and activated T cells in MDS patients with different immunophenotype, different WT1 expression, and different course of disease were analyzed. The percentage of CD4+T lymphocyte in MDS-EB-2, IPSS high-risk, CD34+ cells >10%, and patients with CD34+CD7+ cell population and WT1 gene overexpression at intial diagnosis decreased significantly (P<0.05), and the percentage of NK cells and activated T cells increased significantly (P<0.05), but there was no significant difference in the ratio of B lymphocytes. Compared with the normal control group, the percentage of NK cells and activated T cells in IPSS-intermediate-2 group was significantly higher(P<0.05), but there was no significant difference in the percentage of CD3+T, CD4+T lymphocytes. The percentage of CD4+T cells in patients with complete remission after the first chemotherapy was significantly higher than in patients with incomplete remission(P<0.05), and the percentage of NK cells and activated T cells was significantly lower than that in patients with incomplete remission (P<0.05). In MDS patients, the proportion of CD3+T and CD4+T lymphocytes decreased, and the proportion of activated T cells increased, indicating that the differentiation type of MDS is more primitive and the prognosis is worse.

PD-1 Inhibitors Can be the First-Line Therapy for Myelodysplastic Syndrome (MDS) --Study on the Bone Marrow Immune Microenvironment of MDS By Multispectral Imaging of Multiplex Immunofluorescence

Objective: Myelodysplastic Syndrome (MDS) is a special myeloid neoplasm with still limited treatment choices and poor survival. Although current therapies including HMAs have been shown to prolong survival, only 40-50% of patients respond to therapy, and responses are universally transient, with loss of response within 2 years. With the increasing understanding of the pathogenesis of MDS in recent years, MDS was found closely associated with the bone marrow microenvironment, including immune microenvironment (IME). More and more evidences show that the immune microenvironment of MDS is related with its disease characteristics and prognosis. Knowing more of the IME of MDS may facilitate the diagnose and treatment on MDS. However, till now little was known about the bone marrow immune microenvironment of MDS. Previous studies mostly applied multiparameter flow cytometry and based on the PB samples or frozen bone marrow fluid samples, less was known about the immune landscape of MDS bone marrow biopsies. Methods: We use multispectral imaging of multiplex immunofluorescence (mIF) to analyze the bone marrow biopsy slides and explore the bone marrow immune microenvironment of MDS patients. A total of 20 de novo MDS patients, 20 post-treatment MDS patients and 20 normal controls were included in this study. In HMAs treated group, 10 patients were response to HMA and another 10 patients were not response. HMAs were either decitabine with a dose at 20mg/m2 d1-5 or 5-Azacytidine with a dose at 75mg/m2 d1-7. The multiplex staining panel could differentiate the distinct cell subpopulations into CD34+CD117+ cells, CD8+ cells, PD1+ cells, CTLA4+ cells, CD8+PD1+ cells and CD8+CTLA4+ cells, CD8-PD1+ cells and CD8-CTLA4+ cells, respectively. We analyzed the proportion of these cells in MDS patients and normal controls, and analyzed the proportion of these cells in MDS patients with different IPSS risk stratifications, and we also assessed the degree of myelofibrosis in MDS patients and analyzed the relationship between myelofibrosis and immune cells. Results: We found that compared with the normal control, the proportion of CD8+ cells in de novo MDS patients increased, and CD8+PD1+ T cells increased too, but the CD8+CTLA4+ T cells decreased. Compared with the lower-risk groups, CD8+ T cells as well as CD8+PD1+ T cells increased in higher-risk groups, while CD8+CTLA4+ T cells decreased. We also found a higher CD8+ T cells as well as CD8+/PD1+ T cells in MDS-F patients, especially in MDS-F patients with higher IPSS risk levels. We also found that compared with the normal control, the proportion of CD8+ T cells per CD34+CD117+ cell reduced, and was lower in IPSS int-2 risk/high-risk group than that in low-risk/int-1 risk group. But the proportion of CD8+PD1+/CD34+CD117+ increased compared with normal control. To analyze the bone marrow immune microenvironment after HMAs treatment, CD8+PD1+ T cells decreased in patients who are effective to HMAs, but still remain high in patients who had no response to HMAs, so did the proportion of CD8+PD1+/CD8+ and CD8+PD1+/CD34+CD117+. However, such findings were not found on CD8+/CTLA4+ T cells. Conclusions: Our research findings provide a new insight on the bone marrow IME of MDS. The results confirmed that the immune checkpoint molecule PD-1 positive CD8+ T cells are abundant in MDS IME and associated with the risk. However, CTLA4 may not be a major molecule interfere with the IME of MDS. Our result also suggest that PD-1 inhibitor combines with HMAs might be used as a first-line therapy for de novo MDS patients to cover those patients who may not have response to HMAs. Also, PD-1 inhibitor may cover higher risk MDS and MDS-F, the latter is a high-risk subtype of MDS. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

TIM3/CEACAM1 pathway involves in myeloid-derived suppressor cells induced CD8+ T cells exhaustion and bone marrow inflammatory microenvironment in myelodysplastic syndrome.

Myeloid-derived suppressor cells (MDSC) induced cellular immune deficiency and bone marrow inflammatory microenvironment play an important role in the pathogenesis and progression of myelodysplastic syndrome (MDS), but the underlying mechanism remains unclear. Here, we revealed that immune checkpoint protein TIM3 and CEACAM1 were highly demonstrated on MDSC and CD8+ T cells in MDS patients. CD8+ T cells were reduced in number and function and presented a exhaustion state. The levels of pro-inflammatory cytokines (IL-1β, IL-18) and CEACAM1 were raised in bone marrow supernatants and MDSC culture supernatants. Blocking or neutralizing TIM3/CEACAM1 and IL-1β/IL-18 partially reversed exhaustion of CD8+ T cells. Moreover, TIM3 correlated with NF-κB /NLRP3 inflammatory pathway. The levels of NF-κB/NLRP3/Caspase-1/IL-1β and IL-18 were all increased in MDSC of MDS. Co-culturing MDSC from MDS patients with rhCEACAM1 enhanced NF-κB/NLRP3/Caspase-1/IL-1β and IL-18 levels, whereas blocking TIM3 could partially reverse the above manifestations. These results indicated that TIM3/CEACAM1 pathway involved in CD8+ T cells exhaustion and might activate the NF-κB/NLRP3/Caspase-1 pathway in MDSC, increasing pro-inflammatory cytokines secretion in MDS bone marrow microenvironment. This study provided a basis for applying immune checkpoint inhibitors that could simultaneously modulate pro-inflammatory cytokine secretion and enhance anti-tumour immune function in the treatment of MDS.

Combination of Ras Modulator and Azacitidine Impacts Innate Immune Signaling Pathway in MDS-L Cell Line

Background: Myelodysplastic syndrome (MDS) is a clinically heterogenous disease of hematopoietic stem cells (HSC) characterized by ineffective hematopoiesis, uni/multi-lineage dysplasia and a high tendency to transform into acute myeloid leukemia. Aberrant chromosomal and genetic lesions contribute to MDS pathogenesis which has been associated with chronic activation of the innate immune response and a hyperinflammatory microenvironment (Barryero L, et al. Blood, 2018). Dysfunction of Toll like receptors (TLR) and downstream effectors has been associated with the loss of progenitor function and differentiation of bone marrow (BM) cells in MDS patients. Azacitidine (AZA), a hypomethylating agent (HMA), is the mainstay of therapy for patients with higher-risk MDS (Silverman LR, The Myelodysplastic Syndrome in Cancer Medicine, Editors: R.J. Bast, et al. 2017) and carries an overall response rate (ORR) of 50% in patients with significant effects on hematopoiesis, ranging from improvement in a single lineage to complete restoration of blood counts and transfusion independence with survival benefits (Silverman LR, et al., Leukemia, 1993). The response to AZA is not durable and all patients relapse with worsening bone marrow failure.The paradigm of MDS therapy is now shifting to combinatorial drug treatment to overcome single-agent HMA resistance in higher-risk MDS patients. Rigosertib (RIGO), a Ras mimetic which had been shown to interfere with the Ras-Raf binding domain, has limited single-agent activity (ORR 15%) and failed to provide a survival benefit compared to standard of care in MDS patients failing an HMA. RIGO combined with AZA produced an ORR of 90% in HMA naïve patients and 54% in patients who failed HMA (Navada SC, et al. EHA Library 2019). This represents a critical observation in overcoming the epigenetic clinical resistance phenotype. The mechanism is still unclear.Method: We therefore investigated the pathways that are perturbed by AZA and RIGO monotherapy and in combination (RIGO-AZA). We used the MDS-L cell line as a model to limit the heterogeneity observed in MDS patients. The cells were treated with RIGO, AZA, and RIGO-AZA for 48 hrs and further analyzed by qPCR and western blot.Result: We found an increase in H3K9ac protein expression with RIGO and RIGO-AZA; AZA and RIGO alone each had similar effects on H3K4me3, however, its expression was markedly upregulated with RIGO-AZA (Figure A). Effects on H3K36me3 were comparable in all treated cells. We observed marked effects on the repression marks H3K9me3 and H3K27me3 by RIGO and RIGO-AZA combination (Figure A). Furthermore, we studied the expression of bacterial sensing TLRs (1, 2 and 6), viral sensing endosomal TLRs (3 and 9), and cytosolic viral particle sensing receptors like Retinoic acid inducible gene (RIG)-I, Melanoma differentiation-associated protein 5 (MDA5) and Stimulator of interferon genes (STING); their intermediate adaptor molecules Myeloid differentiation factor 88 (MYD88) (for all TLRs except TLR3), mitochondrial antiviral signaling (MAVS) gene (for RIG-I and MDA5); and interferon regulatory factor (IRF)-3 and -7 by qPCR. We observed that AZA, RIGO, and RIGO-AZA significantly inhibit the expression of TLR1, 2 and 6 (Figure B). However, TLR-3, 9, RIG-I, MDA5, STING, MAVS, MYD88, and IRF-3, 7 were significantly inhibited by RIGO and RIGO-AZA (Figure C-E).Conclusion: RIGO has effects on innate immune signaling and histone modification of both activator and repressor marks. Further studies are underway to determine the correlation of the histone modification and innate immune signaling changes, and if these mechanisms contribute to the improvement in hematopoiesis in MDS patients. [Display omitted] DisclosuresNavada: Janssen Pharmaceuticals, Inc.: Current Employment. Reddy: Onconova Therapeutics, Inc.: Current equity holder in publicly-traded company.

Phagocytosis checkpoints on hematopoietic stem cells in patients with myelodysplastic syndromes.

The myelodysplastic syndrome (MDS) is a high-risk hemocytopenia easily converted to acute myeloid leukemia. CD47 plays an important role in regulating phagocytosis, and its role in the pathogenesis of MDS is unclear. CD47 and PI3K/AKT/mTOR on CD34+ CD38- cells were detected by flow cytometry. NF-κB, PI3K, AKT, PTEN, and mTOR mRNA overexpressed in CD34+ CD38- CD47+ cells were performed by real-time quantitative transcriptase-polymerase chain reaction. Phagocytic capacity of macrophages was measured with carboxyfluorescein succinimidyl ester and fluorescent microspheres. Sorted CD34+ CD38- CD47+ cells were injected into NOD-Prkdcscid Il2rgnull mice. The expression of CD47 on CD34+ CD38- cells of the patients in high-risk MDS based on IPSS-R/WPSS score was higher than that in low-risk MDS and controls. The signaling pathway of PI3K/AKT/mTOR is active in CD34+ CD38- CD47+ cells of MDS patients. CD47 overexpressing CD34+ CD38- cells has antiphagocytosis. CD47 overexpressing leukemia stem cell (LSC) -transplanted mice has a short survival time. The macrophages originated from MDS might elicit a pro-tumor response in MDS by inhibiting phagocytosis. Phagocytosis checkpoints are impaired in MDS. High expression of CD47 on CD34+CD38- cells indicates poor clinical prognosis in MDS.

Lymphocyte activation gene 3 expression on T lymphocyte cell subsets in patients with myelodysplastic syndrome

Objective: To investigate the expression of Lymphocyte activation gene 3 (LAG3) in myelodysplastic syndromes (MDS) patients. Methods: A total of 16 MDS patients newly diagnosed in Hematology Department of Tianjin Medical University were enrolled from January to November 2019. The healthy control (HC) group includes 16 cases of healthy adults. The expression levels of LAG3 on CD8(+)T cells, CD4(+)T cells and regulatory T cells (Treg) in MDS patients and healthy controls were detected by flow cytometry. Results: A total of 16 patients with MDS were included, including 5 males and 11 females, with a median age of 56 (18-80) years old. HC group includes 16 healthy adults, 8 men and 8 women, with a median age of 40 (17-69) years. There was no statistically significant difference in gender and age composition between the two groups (both P>0.05). The expression of LAG3 on CD8(+)T cells in MDS patients (74.45%±22.31%) was significantly higher than that in HC group (58.78%±14.82%, P<0.05). The LAG3 expression on Treg in MDS patients (64.91%±10.32%) were significantly higher than that of HC group (49.09%±13.58%, P<0.05). There was no statistical difference in LAG3 expression on CD4(+)T cells between the two groups. Conclusion: The expression of LAG3 on CD8(+)T cells and Treg increases in MDS patients than that of healthy people.

CD8+ T cells exhaustion induced by myeloid-derived suppressor cells in myelodysplastic syndromes patients might be through TIM3/Gal-9 pathway.

CD8+ T cells play a central role in antitumour immunity, which often exhibit ‘exhaustion’ in the setting of malignancy and chronic viral infection due to T cell immunoglobulin and mucin domain 3 (TIM3) and myeloid‐derived suppressor cells (MDSCs). Our team previously found that overactive MDSCs and exhausted TIM3+CD8+ T cells were observed in myelodysplastic syndromes (MDS) patients. However, it is not obvious whether MDSCs suppress CD8+ T cells through TIM3/Gal‐9 pathway. Here, Gal‐9, as the ligand of TIM3, was overexpressed in MDSCs. The levels of Gal‐9 in bone marrow supernatants, serum and culture supernatants of MDSCs from MDS patients were elevated. CD8+ T cells from MDS or normal controls produced less perforin and granzyme B and exhibited increased early apoptosis after co‐culture with MDSCs from MDS. Meanwhile, the cytokines produced by CD8+ T cells could be partially restored by TIM3/Gal‐9 pathway inhibitors. Furthermore, CD8+ T cells produced less perforin and granzyme B after co‐culture with excess exogenous Gal‐9, and the function of CD8+ T cells was similarly restored by TIM3/Gal‐9 pathway inhibitors. Expression of Notch1, EOMES (associated with perforin and granzyme B secretion), p‐mTOR and p‐AKT (associated with cell proliferation) was decreased in CD8+ T cells from MDS after co‐culture with excess exogenous Gal‐9. These suggested that MDSCs might be the donor of Gal‐9, and TIM3/Gal‐9 pathway might be involved in CD8+ T cells exhaustion in MDS, and that TIM3/Gal‐9 pathway inhibitor might be the promising candidate for target therapy of MDS in the future.

Prognostic Significance of Reduced BCAS4 expression in Bone Marrow Cells of Patients with Myelodysplastic Syndromes

Deletion of long arm of chromosome 20 (del(20q)) is commonly observed in myelodysplastic syndromes (MDS). Reduced expression of genes located within the common deleted region (CDR) of del(20q) due to haploinsufficiency may play a role in molecular pathogenesis of MDS. In the previous study, we examined expression of genes located within the CDR which we determined using array-CGH, in bone marrow mononuclear cells in MDS patients with or without del(20q), indicating that BCAS4 expression was significantly reduced in bone marrow cells in MDS patients with or without del(20q). The BCAS4 gene, which was identified as a fusion transcript expressed in MCF7 cells, encodes 23kD protein. Although function of BCAS4 protein remains unclear, it could be a member of "cappuccino" family, which belong to lysosome-related organelles. Abnormality of genes encoding lysosome-related organelles cause variety of congenital disorders, including the Hermansky-Pudlak syndromes, which is characterized by oculocutaneous albinism and bleeding tendency due to platelet dysfunction as a result of lysosome abnormalities. In the present study we investigated clinical implication of BCAS4 expression level in MDS patients. Mononuclear cells separated from bone marrow samples taken at the time of MDS diagnosis were used for analysis. Written informed consent was obtained from patients before study. To analyze BCAS4 expression, quantitative RT-PCR was performed using cDNA from mononuclear cells as template by the TaqMan probe method (Applied Biosystems) with co-amplification of the endogenous control gene, human GAPDH (Applied Biosystems). Samples from 103 MDS patients, 64 males and 39 females with median age of 67 years (range: 20-91 years), with (n=14) or without (n=89) del(20q), were examined in the present study. Patients were classified as RCUD (n=12), RCMD (n=55), RARS (n=9), RAEB-1 (n=10), and RAEB-2 (n=13), according to WHO 2008 classification, and in RAEB-T (n=4) according to FAB classification. They also were categorized in four IPSS risk groups, low risk (n=30), intermediate-1 risk (n=46), intermediate-2 risk (n=18), and high risk (n=9). There was no significant difference in relative BCAS4 expression level between patients with del(20q) and those without del(20q), and among WHO subtypes. Higher IPSS risk groups (INT-2 and High) showed trend in association with reduced BCAS4 expression compared with lower IPSS risk groups (Low and INT-1) (P=0.104). We analyzed impact of BCAS4 expression on overall survival (OS). Based on BCAS4 expression level, 103 patients were divided into four groups, highest (Q1), intermediate (Q2, Q3), and lowest (Q4) quartiles. The Kaplan-Meier analysis demonstrated that Q4 showed significantly worse OS compared with remaining quartiles (Q1-Q3) (log-rank test, P=0.0031). The estimated 2-year OS rates in Q1-3 group and Q4 group were 75.1% and 48.9%, respectively. According to the COX proportional hazards model, univariate analysis showed lower BCAS4 expression (Q4 vs Q1-Q3) was associated with worse OS (hazard ratio 3.43, 95%CI 1.89-6.11, P=0.0001) as well as older age (65 years or older vs less than 65 years), and higher IPSS risk groups (INT-2 and High vs Low and INT-1). Multivariate analysis indicated that lower BCAS4 expression showed trend for association with worse OS (hazard ratio 1.90, 95%CI 0.96-3.64, P=0.0651) by analyzing with two variables (older age and higher IPSS groups). Next, we investigated whether OS is predicted by combination of three variables, BCAS4 expression level, IPSS risk groups, and age at diagnosis. We defined lower BCAS4 expression (Q4), higher IPSS (INT-2 and High), and older age (65 years or older), as risk factors. The Kaplan-Meier analysis showed that survival curves were well separated according to number of risk factors (0, 1, and 2 or more) (P&lt;0.0001). The estimated 1-year, 2-year, and 5-year survival rates were 100%, 100%, and 86.5% in patients without risk factor, 75%, 70.2%, and 51.7% in patients with one risk factor, and 54%, 34.3%, and 11.4% in patients with two or more risk factors. The present study demonstrated that reduced BCAS4 expression is associated with inferior clinical outcome, indicating that BCAS4 expression level could be a useful prognostic marker in MDS, especially by combination with IPSS risk and patients age at diagnosis. Disclosures Tanaka: Bristol-Myers Squibb: Research Funding.

R-Loops-Induced ATR Signaling As a Potential Therapeutic Target in Myelodysplastic Syndrome

Introduction: Somatic mutations in genes coding for splicing factors (e.g. SF3B1, U2AF1 and SRSF2) are found in about 50% of patients with Myelodysplastic Syndrome (MDS). These mutations have been shown to frequently occur early in the mutational hierarchy of the disease making them particularly attractive therapeutic targets. Recent research has revealed an association of splicing factor mutations (sfm) with elevated levels of DNA:RNA intermediates (R-loops), which induce replication stress and downstream activation of the ataxia telangiectasia and Rad3-related protein (ATR) pathway. The aim of this work was to investigate R-loops-associated ATR signaling as a novel therapeutic concept in primary CD34+ MDS patient cells carrying sfm, and to identify possible novel options for combination therapy. Methods: Using quantitative immunofluorescence microscopy we assessed levels of R-loops in primary CD34+ bone marrow cells isolated from MDS patients (n=23) with and without sfm. In addition, we evaluated the direct association of R-loops with induction of replication stress and activation of associated signaling by analyzing replication fork progression rates and phosphorylation of ATR target proteins. Furthermore, we determined the in vitro sensitivity of mutant (n=12) and non-mutant CD34+ (n=10) cells of MDS patients towards ATR inhibitors (VE-821 and AZD6738) alone and in combination with splicing modulator Pladienolide B and investigated the impact on DNA damage accumulation and apoptosis. We also performed these experiments in cord blood derived CD34+ cells overexpressing SRSF2P95H without other MDS-associated cellular alterations. Results: We found significantly elevated levels of R-loops in CD34+ cells from MDS patients carrying sfm compared to non-splicing factor mutated (non-sfm) MDS cells and healthy controls (mean MFI= 177 (sfm) vs. 78 (non-sfm) vs. 91 (healthy), p&lt;0.0001). These were primarily found in the stem and progenitor as well as myeloid cell compartments, while lymphoid cells showed normal levels. Induced R-loops caused delayed replication fork dynamics as determined by fiber assay (mean fork speed= 0.282 kb/min (sfm) vs. 0.401 kb/min (non-sfm), p ≤0.0001), which in association with elevated levels of single-strand DNA marker replication protein A (RPA) strongly suggests the presence of replication stress in splicing factor mutated CD34+ cells. When exposed to ATR inhibitors in vitro, splicing factor mutant cells showed a significantly elevated sensitivity towards these drugs (normalized mean IC50= 0.89 µM (sfm) vs. 2.84 µM (non-sfm), p ≤0.001) associated with heightened levels of DNA damage and apoptosis, both of which were further increased by the addition of splicing modulator Pladienolide B. We also confirmed a direct correlation of R-loops associated ATR signaling with the presence of mutant SRSF2P95H by lentiviral overexpression in cord blood CD34+ cells. Conclusion: Overall, our results identify ATR as a promising novel therapeutic target in MDS with splicing factor mutations and provide a preclinical rationale for combination therapy with splicing modulator drugs. Disclosures Nolte: Novartis: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.

Differential Effects of TLR1/2 and TLR2/6 Signaling on Normal and Premalignant Hematopoietic Stem and Progenitor Cells

Prior studies from our lab and others have demonstrated a role for Toll-like receptor 2 (TLR2) in regulating both normal and premalignant hematopoietic stem and progenitor cells (HSPCs), however the contributions of its binding partners, TLR1 and TLR6, remain unknown. In CD34+ bone marrow cells of patients with myelodysplastic syndrome (MDS), increased TLR2 was associated with lower-risk disease, elevated rates of apoptosis associated with improved prognosis, and enhanced survival. Conversely, increased levels of TLR6, but not TLR1, was associated with higher-risk disease and an increased percentage of bone marrow blasts (Zeng et al., Exp Cell Res 2016 and Wei et al., Leukemia 2013). These data suggest that there may be heterodimer-specific effects of TLR2 signaling on HSPCs influencing disease progression.To elucidate the unique contributions of the heterodimer pairs in MDS pathogenesis and leukemogenesis, we utilized a well-established mouse model of MDS that expresses the NUP98-HOXD13 fusion from the hematopoietic Vav-1 promoter. The “NHD13” mice recapitulate many of the salient features of human MDS and succumb to cytopenias or leukemia by 14 months of age (Lin et al., Blood 2005). Importantly, we observed significantly increased expression of TLRs 1, 2, and 6 on the c-Kit+, Sca-1+, Lineage- (“KSL”) HSPCs of the NHD13 mice, similar to the increased expression of these TLRs on CD34+ cells of MDS patients. To begin to delineate the heterodimeric differences, NHD13 mice were treated chronically with either PAM2CSK4 (PAM2), a TLR2/6-specific agonist, or PAM3CSK4 (PAM3), a TLR1/2-specific agonist, to assess the effects on cytopenias and survival. After five months of treatment, a significant increase was observed in the total number of white blood cells in NHD13 mice treated with PAM2 (p=0.007), but not PAM3 (vs. vehicle (water)-treated controls), a finding that was not recapitulated in wild-type (WT) controls. On the contrary, a significant decrease in the total number of platelets in both NHD13 and WT mice treated with PAM3 was observed as compared to vehicle-treated controls (p=0.024 and p=0.011, respectively). Further supporting the existence of heterodimer-specific differences, death was expedited in NHD13 mice treated with PAM2 as compared to those treated with PAM3 (p=0.019), with a median survival of 243 days vs. 338 for the PAM3-treated cohort. The cause of death, as determined by a hematopathologist based on cytology and blast percentage, was most often due to leukemia.To investigate the potential mechanism through which enhanced TLR2/6 signaling accelerates leukemogenesis and death in NHD13 mice, the HSPCs of premalignant NHD13 mice treated with PAM2 or PAM3 were characterized by flow cytometry and evaluated for cell cycling and cell death. Both the total number and frequency of KSL cells were significantly increased in NHD13 mice treated with PAM2 (p=0.007 and p<0.0001, respectively), but not PAM3, vs. water-treated controls. No significant changes were noted in either cell cycling or apoptosis following agonist treatment. A microarray of bone marrow KSL cells revealed that stimulation of the TLR2/6 pathway is associated with an activated c-Myc signature, suggesting that enhanced signaling through this pathway, but not TLR1/2, may enhance leukemogenesis via Myc activation. Further, the expression levels of six downstream targets of c-Myc, including BAX, APEX1, ODC1, FKBP4, NCL, and HSPD1, were significantly increased in both WT and NHD13 mice following PAM2 treatment. Evaluation of serum cytokines also revealed heterodimer-specific alterations, including increased IL-6 levels in NHD13 mice treated with PAM2, but not PAM3. These data corroborate numerous previous reports linking IL-6 to MDS pathogenesis and transformation to acute myeloid leukemia. Ongoing studies involving mass cytometry, IL-6knockout mice, and pharmacological inhibitors of both IL-6 and c-Myc aim to further elucidate the mechanism through which TLR2/6-specific activation accelerates leukemogenesis and death in the NHD13 mouse model of MDS. These studies hope to inform more targeted therapeutics that could potentially delay MDS progression and reduce off-target effects. DisclosuresNo relevant conflicts of interest to declare.

Increased separase activity and occurrence of centrosome aberrations concur with transformation of MDS.

ESPL1/separase, a cysteine endopeptidase, is a key player in centrosome duplication and mitotic sister chromatid separation. Aberrant expression and/or altered separase proteolytic activity are associated with centrosome amplification, aneuploidy, tumorigenesis and disease progression. Since centrosome alterations are a common and early detectable feature in patients with myelodysplastic syndrome (MDS) and cytogenetic aberrations play an important role in disease risk stratification, we examined separase activity on single cell level in 67 bone marrow samples obtained from patients with MDS, secondary acute myeloid leukemia (sAML), de novo acute myeloid leukemia (AML) and healthy controls by a flow cytometric separase activity assay. The separase activity distribution (SAD) value, a calculated measure for the occurrence of cells with prominent separase activity within the analyzed sample, was tested for correlation with the centrosome, karyotype and gene mutation status. We found higher SAD values in bone marrow cells of sAML patients than in corresponding cells of MDS patients. This concurred with an increased incidence of aberrant centrosome phenotypes in sAML vs. MDS samples. No correlation was found between SAD values and the karyotype/gene mutation status. During follow-up of four MDS patients we observed increasing SAD values after transformation to sAML, in two patients SAD values decreased during azacitidine therapy. Cell culture experiments employing MDS-L cells as an in vitro model of MDS revealed that treatment with rigosertib, a PLK1 inhibitor and therapeutic drug known to induce G2/M arrest, results in decreased SAD values. In conclusion, the appearance of cells with unusual high separase activity levels, as indicated by increased SAD values, concurs with the transformation of MDS to sAML and may reflect separase dysregulation potentially contributing to clonal evolution during MDS progression. Separase activity measurement may therefore be useful as a novel additional molecular marker for disease monitoring.

Effects of arsenic disulfide on apoptosis, histone acetylation, toll like receptor 2 activation, and erythropoiesis in bone marrow mononuclear cells of myelodysplastic syndromes patients in vitro

ObjectiveAs the main component of traditional Chinese medicine realgar, arsenic disulfide (As2S2) is widely used in treating myelodysplastic syndromes (MDS). The goal of the current study is to assess the effects of As2S2 on bone marrow mononuclear cells (BMMNC) of MDS. MethodsBMMNCs were obtained from 10 lower risk MDS patients, 5 higher risk MDS patients, and 3 healthy controls. Then, the cells were treated with As2S2 for 48h, using vorinostat (also known as SAHA) as control. Cell proliferation and apoptosis were detected. mRNA and protein levels of histone deacetylase-1 (HDAC1), Toll-like receptor 2 (TLR2), and erythroid transcription factor (GATA-1) were detected by quantitative real-time PCR and western blot analysis. ResultsAfter As2S2 treatment in concentrations ranging from 3.125 to 100μmol/L, cell proliferation was inhibited in both lower risk and higher risk MDS. Fifty percent inhibitory concentrations were 24.4μmol/L and 23.6μmol/L, respectively, for lower and higher risk MDS. Apoptotic cells significantly increased in both types of MDS. mRNA and protein levels of HDAC1 and TLR2 were reduced, whereas GATA-1 was increased in both types of MDS. ConclusionsAs2S2 could inhibit cell proliferation and induce apoptosis through histone acetylation modulation in MDS. Similar to SAHA, As2S2 could reduce TLR2 activation and increase GATA-1 expression. Current data suggest epigenetic and immunological alternations are involved in therapeutic mechanisms of realgar in the treatment of MDS.

Subtype and Functional Biomarker Changes of NK Cells in Peripheral Blood of Patients with Myelodysplastic Syndrome

To analyze the subtype and functional biomarker expression changes of natural kill cells(NK) in peripheral blood of patients with myelodysplastic syndrome(MDS) and normal people, so as to evaluate the relationships between these changes and hematopoietic functions and to explore the role of NK cells in the pathogenesis of MDS. The quantity of NK cells and the expression of biomarkers(NKp30,NKp46,NKG2A) on NK cells were detected by flow cytometry in 35 MDS patients from 2015 to 2016 in our hospital and 34 normal controls. The correlation between these changes and hematopoietic functions, including the percentages of neutrophil(ANC), hemoglobin in peripheral blood and the hematopoietic function in bone marrow(CD34+%) were evaluated. The percentage and quantity of NK cells and CD56dim NK cells in MDS patients were significantly lower than those in normal controls(P<0.05); the percentage of CD56bright NK cells was higher than that in controls. The percentage of CD56dim NK cells in NK cells of MDS patients was significantly lower than that of controls; the percentage of CD56bright NK cells in NK cells of MDS patients was significantly higher than that of controls. The expression of NKp30 and NKp46 of MDS patients was significantly lower than that of controls. In MDS group, the percentage of NK cells and CD56dim NK cells of peripheral blood lymphocytes in high risk MDS group was significantly lower than that in low risk MDS group. The percentage of NK and CD56dim NK cells negatively correlated with that of CD34+% in bone marrow, but positively correlated with ANC and Hb. The CD34+% in bone marrow negatively correlated with expression of NKp46, but positively correlated with expression of NKG2A. The decrease of NK number and function may cause the immune surveillance and lead to disease progression.

Levels and Significance of Serum Interleukin-35 and the New Regulatory T Cells -iTR35 Cells in Myelodysplastic Syndrome Patients

To investigate the significance of serum interleukin-35 level and the new regulatory T cells -iTR35 cells in patients with myelodysplastic syndrome (MDS). Twenty three cases of newly diagnosed MDS were enrolled in this study from January 2014 to January 2016 in Department of Hematology of The First Hospital of Quanzhou in Fujian Province. According to MDS International Prognostic Scoring System (IPSS), the 23 patients were divided into 4 groups: high-risk (n=4), intermediate risk-2 (n=10), intermediate risk-1 (n=5) and low-risk group(n=4). Twenty healthy people of routine physical examination were used as control during the same period. Enzyme Linked Immunosorbent assay(ELISA) and flow cytometry(FCM) were used to detect the expression level of serum IL-35, the proportion of iTR35 cells, and the expression levels of associated molecules such as IL-12p35,IL-27EBl3 respectively. The proportion of CD4+ CD25+ Foxp3+ Treg cells in peripheral blood of MDS patients was significantly higher than that in controls (P<0.01). The proportion of iTR35 cells was also higher than that in controls(P<0.01). However, the proportion of CD4+ CD25- Foxp3+ T cells was not significantly different between 2 groups (P>0.05). The level of serum IL-35 in MDS patients was significantly higher than that in control group (P<0.05). The expression levels of IL-12p35 and IL-27EBl3 in the Treg cells were also significantly upregulated than those in control group(P<0.05), the expression levels of IL-35, IL-12p35 and IL-27EBl3 in MDS group positively correlated with the proportion of iTR35 cells(r=0.92, 0.99 and 0.52, P<0.05, respectively). IL-35 level and the proportion of iTR35 cells in 4 groups of MDS showed significantly difference in general term, no significant difference was found in IL-35 level between the high-risk group and intermediate risk-2 group (P>0.05), but the IL-35 levels in both groups were significantly higher than those in intermediate risk-1 group and the low-risk group (P<0.05), and the level in the intermediate risk-2 group was significantly higher than that in the intermediate risk-1 group and the low-risk group (P<0.05), while there was not different between the intermediate risk-1group and the low risk group (P>0.05). The proportion of iTR35 cells was not significantly different between the high-risk group and the intermediate risk-2 group. The proportions of iTR35 cells in the high-risk group and the intermediate risk-2 group were higher than those in the intermediate risk-1 group and the low-risk group respectively (P<0.05), but there was no differentce in population of iTR35 between the intermediate risk-1 group and the low-risk group (P>0.05). The imbalance between IL-35 level and iTR35 cells propertion may play an important role in the development of MDS, which possibly to provides a new theoretical basis for the study of MDS immune targeting therapy.

Increased TIM3+CD8+T cells in Myelodysplastic Syndrome patients displayed less perforin and granzyme B secretion and higher CD95 expression

T cell immunoglobulin and mucin domain 3(TIM3) is a negative regulator of cellular immunity and it is highly expressed on CD8+T cells in persistent viral infection and cancer setting as report. However, how TIM3 expressed on CD8+T cells in myelodysplastic syndrome (MDS), that is a malignant disorder, has not been clarified. Here, decreased CD8+T cells, less IFN-γ secretion in CD8+T cells and increased TIM3 on CD8+T cells had been seen. Increased TIM3+CD8+T cells with lower perforin and granzyme B expression and higher CD95 expression in MDS patients had been observed. These findings suggested that TIM3 might be related to CD8+T cells defect. Therefore, further explorations about mechanism of TIM3+CD8+T cells defect are needed, which might be helpful for adoptive T-cell therapy in MDS.

IL-32 mRNA Expression of Bone Marrow Stromal Cells and Its Correlation with Cell Apoptosis in Patients with Myelodysplastic Syndrome

To investigate the IL-32 mRNA expression of bone marrow stromal cells and its correlation with apoptosis of bone marrow mononuclear cells in patients with myelodysplastic syndrome (MDS). Bone marrow samples from 26 MDS patients and 10 iron deficiency anemia (IDA, as control) patients were collected, RT-PCR was used to detect the IL-32 mRNA expression of bone marrow stromal cells, and the apoptosis of bone marrow mononuclear cells was detected by flow cytometry with Annexin V-FITC/PI dowble staining. The born marrow lymphocytes and NK cells were detected by means of direct immunofluorescence labeling whole blood hemolysis and flow cytometry. IL-32 mRNA expression of bone marrow stromal cells in the MDS patients was significantly higher than that of control group, the IL-32 mRNA expression of bone marrow stromal cells in patients with RA, RAS and RCMD was significantly higher than that in patients with RAEB. There was no obvious difference between RAEB and the control groups. The apoptosis of bone marrow mononuclear cells in MDS group was significantly higher than that in the control group, the apoptosis of bone marrow mononuclear cells in patients with RA, RAS and RCMD was significantly higher than that in RAEB. There was no significant difference between RAEB group and control group. The IL-32 mRNA expression in bone marrow stromal cells significantly correlated with the apoptosis of bone marrow mononuclear cells in MDS patients. The NK cell number in born marrow of MDS patients and the control group had no significant difference. The expression of IL-32 mRNA in bone marrow stromal cells significantly relates with the apoptosis of MDS cells, and the secretion of IL-32 by bone marrow stromal cells may be one of the reasons for the apoptosis of MDS bone marrow cells. It is speculated that the abnormal MDS bone marrow microenvironment is involved in the apoptosis of bone marrow cells.

Increased Expression of HERG1 K+ Channels Contribute to MDS Progression and Display Correlation with Prognosis Stratification

Background: Myelodysplastic syndromes (MDS) are defined as a heterogeneous group of clonal hematopoietic stem cell (HSC) malignant disorders which are characterized by bone marrow failure and dysplasia of blood cells. As continually terminated in AML, MDS are treated as the "pre-leukemia" condition. HERG K+ channels, being three subtypes: HERG1, HERG.2, HERG3, are expressed transiently at early stages of cells such as progenitor and stem cells, disappearing at later stages of cells like mature cells. Our previous work and others demonstrated that HERG1, as an oncoprotein, was over expressed in AML cells and played crucial roles in SDF-1induced leukemia cell migration. The expression and functional role of HERG1 K+ channels in MDS development is not reported. We investigated the HERG1 K+ channels expression and explored the functional link between HERG1 K+ channels and MDS progressionMethods: The expression of HERG1 K+ channels in untreated MDS, AML patients and normal control was detected by flow cytometry. The roles of HERG1K+ channels in regulation of SKM-1 cell proliferation, apoptosis and cell cycle by CCK-8 assay and flow cytometry, respectively.Results: We observed that the expression of HERG1 K+ channels on bone marrow (BM) mononuclear cells (MNCs) in MDS patients was significantly higher than that in the controls (42 ± 7.62% vs 19.8 ± 2.79%, p < 0.01) , but was lower than that in AML (42 ± 7.62% vs 52.18 ± 9.72%, p < 0.01). MDS subtypes mainly contained refractory cytopenia unilineage dysplasia (RCUD), refractory cytopenia with multilineage dysplasia (RCMD), refractory anemia with excess blast I (RAEB-I), refractory anemia with excess blasts II (RAEB-II) and MDS-unclassified (MDS-U). We next analyzed percentage of HERG1 K+ channels in MDS subtypes and found that level of HERG1 K+ channels on the MNCs in each subtypes of MDS was significant higher than that in the control group (Control: 19.8 ± 2.79%, MDS-RCUD: 30.91 ± 1.48%, MDS-RCMD: 39.06 ± 2.47%, MDS-RAEB-I: 44.76 ± 5.54%, MDS-RAEB-II: 49.69 ± 3.28%, p < 0.01), suggesting that HERG1 K+ channels expression might be positively associated with malignancy degree of MDS.HSCs played important roles in the pathophysiology of MDS. Our results also revealed that with the increase of malignancy degree, the percentage of HERG1K+ channels on CD34+CD38- derived cells from MDS subtypes tended to elevate in corresponding MDS subtypes (MDS-RCUD: 61.21 ± 9.46%, MDS-RCMD: 65.66 ± 4.57%, MDS-RAEB-I: 72.35 ± 9.38%, MDS-RAEB-II: 75.71 ± 4.24%, p < 0.05), which supported the notion in other way that MDS are HSC malignant disorders. The over-expression of HERG1 K+ channels on CD34+CD38- cells in MDS patients might be correlated with the oncogenesis of MDS.In addition, the prognosis stratification of MDS patients was performed according to International Prognostic Scoring System (IPSS) scores and the untreated MDS cohort was categorized as four risk groups: Low-R, Int-1-R, Int-2-R and High-R. Our results showed that there was a positively correlation between HERG1 level and IPSS scores of patients (Low-R: 31.93 ± 3.47%, Int-1-R: 39.95 ± 5.76%, Int-2-R: 45.94 ± 6.34%, High-R: 49.05 ± 3.04%, p < 0.01). This showed that expression level of HERG1 K+ channels was helpful for predicting the prognosis of de novo MDS.Furthermore, we analyzed HERG1 K+ channel role on MDS cell proliferation and apoptosis. Incubation with 0, 10, 20 uM E-4031 ( HERG K+ channels inhibitor) with SKM-1 cells (MDS cell line) for 48 h, the results showed that blockage of HERG1 decreased the proliferation of SKM-1 cells but had rarely effects on cell apoptosis and cell cycle distribution. In consistent with other studies, HERG1 K+ channels had already been shown to be necessary for growth of cancer cells through specific activities independent of cell cycle such as interacting with TNFR1 protein which could activate NF-κB to facilitate cell proliferation and favoring transduction of growth signals by MAP kinase/c-fos pathway. These findings showed that physiological activity of HERG1 K+ channels was crucial for MDS cell proliferation and HERG1 K+ channels may be a potential therapeutic target for MDS.Conclusion: Briefly, our study firstly showed that HERG1 K+ channels were aberrantly over-expressed on MDS stem cells, mononuclear cells, and positively associated with malignancy degree of MDS. HERG1 K+ channels functionally contribute to MDS progression and may be a potential therapeutic target for MDS. DisclosuresNo relevant conflicts of interest to declare.

Reduced PLCG1 expression Is Associated with Inferior Survival in Myelodysplastic Syndromes

The PLCG1 gene encodes phospholipase C g isoform, which is involved in diverse physiological and pathological cellular processes through catalyzing the hydrolysis of phosphatidylinositol 4,5-bisphosphate to produce the second messenger molecules inositol 1,4,5-trisphosphate and diacylglycerole. Until now, roles of phospholipase C g 1 in hematopoiesis have been shown in animal models. Plcg1 deficient mouse lacks erythropoiesis and die in early embryonic stage. In zebrafish model, it was demonstrated that phospholipase C g 1 is required in granulocyte maturation. Physiological and/or pathological role of phospholipase C g 1 in human hematopoiesis has not been elucidated. In human, the PLCG1 gene is located on long arm of chromosome 20. Deletion of long arm of chromosome 20 (del(20q)) is commonly observed in myelodysplastic syndromes (MDS). Previously, we determined the common deleted region (CDR) of del(20q) in MDS, and the PLCG1 gene is located within the CDR. Reduced expression of genes located in the CDR due to haploinsufficiency may play role in molecular pathogenesis of MDS. Therefore, we analyzed PLCG1 expression in bone marrow mononuclear cells in MDS patients with or without del(20q), and investigated its clinical significance in the present study.Mononuclear cells separated from bone marrow samples taken at the time of diagnosis with written informed consent from patients were used. To analyze PLCG1 expression, quantitative RT-PCR was performed. Total RNA was extracted from mononuclear cells and subjected to cDNA synthesis. Real-time RT-PCR was carried out using cDNA as template by the TaqMan probe method (Applied Biosystems) with co-amplification of the endogenous control gene, human GAPDH (Applied Biosystems) were performed. The human PLCG1 primer-probe set was from Applied Biosystems. A total of 109 MDS patients, 65 males and 44 females with median age of 69 years (range: 22-91 years), with (n=20) or without (n=89) del(20q), were included in the present study. They were classified as RCUD (n=11), RCMD (n=55), RARS (n=11), RAEB-1 (n=16), and RAEB-2 (n=16) according to WHO classification. They were categorized in four IPSS risk groups, low risk (n=21), intermediate-1 risk (n=52), intermediate-2 risk (n=20), and high risk (n=6).Relative PLCG1 expression level was significantly reduced in MDS patients with del(20q) compared to control subjects (n=20) (P=0.011). Median values of relative PLCG1 expression level in MDS patients with del(20q) and control subjects were 0.94 and 1.96. In addition, relative expression level of PLCG1 in whole MDS cohort significantly lower than that in control subjects (P=0.046). Expression patterns of PLCG1 among, were not different. Median values of relative PLCG1 expression level in five WHO-subtypes, RCUD, RCMD, RARS, RAEB-1, and RAEB-2 were 1.50, 1.55, 1.29, 1.13, and 1.12, respectively, but no statistically difference was observed. WHO-subtypes with high blast counts (RAEB-1 and RAEB-2) showed trend in association with reduced PLCG1 expression compared with those with low blast counts (RCUD, RCMD, and RARS) (median value: 1.01 vs. 1.54, P =0.11). To investigate prognostic implication of PLCG1 expression in MDS, we analyzed impact of PLCG1 expression on overall survival (OS). Based on PLCG1 expression level, 109 patients were divided into four groups, high (Q1), intermediate (Q2, Q3), and low (Q4) quartiles. Kaplan-Meier analysis demonstrated that the lowest quartile (Q4) showed significantly worse survival compared with remaining quartiles (Q1-Q3) (P =0.0015). The estimated 5-year OS rates in Q1-3 group and Q4 group were 63.2% and 29.7%, respectively. Percentage of patients with WHO-subtypes with high blast count (RAEB-1 and RAEB-2) was significantly higher in Q4 than other quartiles (46.9% vs 22.1%, P =0.019 by Fisher's exact test).The present study demonstrated that reduced PLCG1 expression is associated with inferior clinical outcome, indicating that PLCG1 expression could be a useful prognostic marker in MDS. Association between reduced PLCG1 expression and WHO-subtypes with high blasts counts, suggesting that PLCG1 dysfunction play a role in disease progression. DisclosuresNo relevant conflicts of interest to declare.

Abnormal Proliferation and Differentiation of Hematopoietic Cells in Myelodysplastic Syndrome Patients

Myelodysplastic Syndrome (MDS) is a group of clonal disorders of hematopoietic stem cells characterized by peripheral cytopenia, ineffective hematopoiesis, morphologically apparent multilineage dysplasia, and enhanced risk of evolution towards acute myeloid leukemia (AML). Most of the research findings have verified the abnormal proliferation and differentiation of hematopoietic cells in MDS. The defects of cellular and molecular factors such as transcription factors (GATA-1~GATA-3, FOG1, Pu.1), growth factors (Epo, G-CSF, GM-CSF) and anti-apoptosis genes ultimately affect the cell cycle regulation and mismatch repair of DNA, changes of hematopoietic microenvironment and immune response. These defects result in ineffective hematopoiesis and dysplasia.