scholarly journals The Role of Jarid2 in Leukemic Transformation of Chronic Myeloid Neoplasms

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1245-1245
Author(s):  
Hamza Celik ◽  
Andrew Martens ◽  
Cates Mallaney ◽  
Elizabeth Eultgen ◽  
Alok Kothari ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Tumor Suppressor ◽  
Mouse Model ◽  
B Cell ◽  
Median Survival ◽  
Wild Type ◽  
Self Renewal ◽  
H3k27 Methylation

Abstract Despite the increasing use of targeted therapies, a subset of patients with myeloproliferative neoplasms (MPN) transform to secondary acute myeloid leukemia (sAML). MPN patients who develop sAML have a dismal outcome, with a median survival of six-months. The mechanisms and pathways that contribute to transformation from MPN to sAML have not been well delineated. The most commonly mutated genes in MPN include JAK2, MPL and CALR and are likely responsible for initiation of the disease. Although these mutations have potential roles in the pathogenesis and for some cases progression to sAML, their role in sustaining the sAML clone is challenged by the finding that some patients with post-MPN sAML who harbor these mutations in their primary MPNs have no evidence of the same mutation in the leukemic blasts. Recent genome sequencing studies identified deletions of JARID2, associated with Polycomb Repressive Complex 2 (PRC2) involved in implementing global H3K27me3, only in leukemic phase of the disease, but not in chronic phase MPNs. This data suggests that JARID2 deletion could be a sAML-specific transforming event by acting as a tumor suppressor in HSCs. We show in 32D cells, Jarid2 pull-down is able to co-immunoprecipitate core PRC2 proteins, Ezh2 and Suz12, and Jarid2 depletion using shRNAs leads to reduction in global H3K27 methylation. These data suggest Jarid2 acts in concert with PRC2 in hematopoietic cells to mediate H3K27 methylation. To examine the function of Jarid2 in vivo, we generated a Jarid2 knockout mouse model (Mx1-CRE:Jarid2fl/fl; Jarid2-KO) in which Jarid2 is conditionally deleted in HSCs. Hematopoiesis in these mice was compromised with a 3-fold reduction in hematopoietic stem cell (HSC) number, defective B-cell generation in the bone marrow (BM), a differentiation block in T-cell development in thymus, and a significant reduction in peripheral blood counts. A competitive transplantation strategy was then employed to assess the potential of Jarid2-KO HSCs. One-hundred phenotypically defined Jarid2-KO HSCs (Lineage- Sca-1+ c-Kit+ CD48- CD150+) from 8-week old mice were transplanted into lethally irradiated recipient mice along with 250,000 whole bone marrow cells from genetically distinguishable wild-type mice. Preliminary analysis of these mice show that the loss of Jarid2 is deleterious for HSC function, leading to reduced lymphoid and enhanced myeloid output and failure to maintain HSC population compared to control HSCs. To further dissect the role of Jarid2 in HSC self-renewal, 18-weeks post-transplant, 100 HSCs were re-purified from the bone marrow of primary recipient mice and transplanted into the secondary recipients along with 250,000 fresh wild-type competitor cells. In this transplant setting, Jarid2-KO HSCs failed to contribute to any PB lineages (myeloid, B-cell and T-cell). Together, these data suggest that Jarid2 is essential for HSC maintenance and is required for HSC self-renewal. To study the tumor suppressor role of Jarid2 we are using mouse models of the MPN mutation FLT3ITD in combination with Jarid2 deletion to assess the function of Jarid2 as a sAML tumor suppresser. We have established a mouse model by crossing Mx1-CRE:Jarid2fl/fl mice with FLT3ITD/+ mice to generate a Mx1-CRE:Jarid2fl/fl FLT3ITD/+ strain. These mice express the germline ITD mutation under control of the endogenous murine FLT3 promoter and develop MPN with a median survival of 10 months. To mimic the genetic progression of chronic stage MPN to sAML, the genetic deletion of Jarid2 is induced in these mice by pIpC injections once MPN is established at 3-months of age. Blood counts of these mice (2 months after Jarid2 deletion, aged 5 months old) started showing the signs of worsening MPN in the absence of Jarid2 such as, high WBC counts and increased neutrophil differentials compared to control (Mx1-CRE: FLT3ITD/+). Our ultimate goal is to understand the genetic processes associated with progression of MPN to sAML, which could eventually improve treatment outcomes for patients who can be identified as at increased risk for undergoing sAML transformation. Disclosures No relevant conflicts of interest to declare.

MerTK Receptor Tyrosine Kinase Inhibition As a Potential Strategy to Augment Immune-Mediated Clearance of Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4044-4044
Author(s):  
Lauren Shelby Page ◽  
Xiaodong Wang ◽  
H. Shelton Earp ◽  
Stephen Frye ◽  
Craig T Jordan ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Median Survival ◽  
Receptor Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Wild Type ◽  
Vehicle Treatment ◽  
Equity Ownership

Abstract The MerTK receptor tyrosine kinase is aberrantly expressed in 80-100% of acute myeloid leukemia (AML), and inhibition of MerTK prolongs leukemia-free survival in vivo, making it an appealing therapeutic target. MerTK is normally expressed on macrophages (MMs) and dendritic cells (DCs) and facilitates engulfment of apoptotic debris. Through this process, MerTK promotes tolerogenicity and anti-inflammatory cytokine production. We hypothesized that inhibition of MerTK will also mediate anti-leukemia effects through relief of microenvironment immunosuppression and stimulation of innate MM and DC activity leading to enhanced T-cell immunity. To test this hypothesis, we transplanted wild-type C57BL/6 mice with syngeneic murine MLL-ENL fusion AML or primary mouse MLL-AF9 AML. We evaluated the effects of MerTK inhibition using MRX-2843, a MerTK kinase inhibitor. Mice were treated daily and survival was monitored. Treatment with MRX-2843 prolonged median survival (43 days) compared to vehicle treatment (17 days) in mice transplanted with MLL-ENL AML (p<0.0001), and MLL-AF9 primary murine AML (42 days with MRX-2843, 30 days with vehicle; p<0.05). To explore the immune effects of MerTK inhibition in AML, we evaluated in vivoMMs and DCs by flow cytometry. Compared to non-leukemic controls, vehicle-treated leukemic mice demonstrated a significant infiltration of MMs and DCs into the primary sites of leukemic burden (spleen, bone marrow). These MMs and DCs expressed high levels of co-inhibitory ligands PD-L1 and PD-L2. Treatment with MRX-2843 significantly decreased PD-L1 and PD-L2 expressing MM and DCs in the spleen (p<0.01) and bone marrow (p<0.01) down to non-leukemic levels. Similar results were not obtained when mice were treated with the non-MerTK targeted FLT3 inhibitor AC220, suggesting that these effects are likely specific to MerTK inhibition. We next evaluated effects of MerTK inhibition on the leukemia microenvironment. We confirmed that T-cells do not express MerTK in-vivowith or without AML, nor +/- MRX-2843. Compared to non-leukemic mice, leukemic mice significantly upregulated co-inhibitory receptors PD-1 and Tim-3 on CD4 and CD-8 T-cells in the spleen and bone marrow. Treatment with MRX-2843 in leukemic mice significantly decreased CD4 and CD8 T-cell PD-1 and Tim-3 expression in the spleen (p<0.05) and bone marrow (p<0.05) down to non-leukemic levels. We next evaluated the role of functional T-cells in the anti-leukemia effects of MerTK inhibition. Wild-type mice and mice harboring a T-cell receptor mutation (TCRa-/-) were transplanted with MLL-ENL AML, treated with MRX-2843 or vehicle, and monitored for symptoms of leukemia. Median survival of all vehicle-treated mice with leukemia was 20-22 days. Median survival of TCRa-/- mice treated with MRX-2843 was 30 days, whereas median survival of MRX-2843 treated wild-type mice was significantly extended to 40 days (p<0.01). To confirm these findings, leukemic wild-type mice were CD8 depleted and treated as above. Median survival of CD8-depleted MRX-2843 treated mice was significantly diminished (30 days) compared to isotype (control) + MRX-2843 treatment (40 days, p<0.01). These data suggest an additional non-cell autonomous role of T-cell anti-tumor immunity in mice treated with a MerTK inhibitor. We next evaluated peripheral serum cytokines using Luminex magnetic bead analysis. Treatment with MerTK inhibition significantly increased serum [IL-18] (p<0.01) and [MCP-3/CCL7] (p<0.05) by 2-fold compared to vehicle-treated mice. Additionally, there was no correlation between co-inhibitor expression and serum [IFN-g]. These changes appeared to be mediated through MerTK and not solely attributable to tumor burden given that MLL-ENL cells in culture did not exhibit these changes +/-MRX-2843. However, MLL-ENL cells did secrete significantly less IL-4 (p<0.01) and LIF (p<0.05) with MerTK inhibition in vitrocompared to vehicle treatment. In conclusion, inhibition of MerTK decreased infiltration of immunosuppressive co-inhibitory ligand-expressing MMs and DCs into primary sites of leukemic engraftment. Furthermore, inhibition of MerTK altered the leukemia microenvironment to decrease T-cell co-inhibitory receptor expression and improve anti-leukemia effects. These preliminary studies demonstrate the potential of MerTK inhibition as an immunotherapeutic strategy in AML. Disclosures Wang: Meryx, Inc: Equity Ownership, Patents & Royalties: MRX-2843. Earp:Meryx: Employment, Patents & Royalties: MRX-2843. Frye:Meryx, Inc: Equity Ownership, Patents & Royalties: MRX-2843.

RhoH-Deficient Mice Show Altered B Cell Populations In Vivo.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2307-2307
Author(s):  
Abel Sanchez-Aguilera ◽  
Jose Cancelas ◽  
David A. Williams
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Marginal Zone ◽  
Cell Receptor ◽  
Wild Type ◽  
Marginal Zone B Cells

Abstract RhoH is a GTPase-deficient, hematopoietic-specific member of the family of Rho GTPases (Li et al, 2002). RhoH has been described as regulating proliferation and engraftment of hematopoietic progenitor cells (Gu et al, 2005) and integrin-mediated adhesion in T cells (Cherry et al, 2004). Additionally, RhoH plays a critical role in T-cell development and T-cell receptor signaling (Gu et al, 2006; Dorn et al, 2007). However, the potential role of RhoH in the differentiation and biological functions of B cells are unknown. To answer these questions, we analyzed the B-cell phenotype of RhoH−/− mice and the in vitro properties of RhoH-deficient splenic B cells compared to their wild-type counterparts. RhoH−/− mice showed increased B-cell numbers in the bone marrow, mainly due to an increase in the number of pro-B, pre-B and immature B cells. In the spleen, lymph nodes and peripheral blood, RhoH−/− mice showed a significant decrease in the number of follicular (B-2) cells (B220+ CD93– IgDhigh CD21low). The number of splenic marginal zone B cells (B220+ CD93– IgDlow CD21high), plasma cells (CD93– CD38+ CD138+) in bone marrow and spleen, and B-1 cells (IgM+ CD5+) in peritoneal cavity were not significantly different from those in wild-type animals. These alterations have functional significance, since the serum concentrations of IgM and IgG1 were significantly lower in RhoH−/− mice. However, splenic B cells isolated from RhoH−/− mice did not show any significant differences in their in vitro activation by anti-IgM, CD40 ligation or IL-4 stimulation, nor did they differ in their proliferative response to lipopolysaccharide. In vitro migration of RhoH-deficient B cells in response to CXCL12 or CXCL13 was similar to that of wild-type B cells. Given the important role of RhoH in signal transduction downstream the T cell receptor, we investigated the possible role of RhoH in B cell receptor signaling. Although total splenic B cells from RhoH−/− mice showed markedly increased phosphorylation of SYK and ERK after anti-IgM stimulation compared to wild-type B cells, sorted populations of splenic B-2 and marginal zone B cells from RhoH−/− and wild-type animals did not differ in the activation of these kinases, suggesting that the observed difference can be attributed to the different cellular composition of the B cell compartment (i.e. B-2 vs marginal zone B cells) in RhoH−/− mice. These data imply that the phenotype observed in RhoH−/− mice may not reflect an intrinsic defect in B cells but may be attributed to crosstalk between B cells and other hematopoietic cell populations. Composition of B cell subsets in wild-type and RhoH−/− mice (total cell number ×106, ± standard deviation, N=9) Bone marrow Spleen (*) indicates p&lt;0.05; (**), p&lt;0.01; (***), p&lt;0.005 RhoH+/+ RhoH−/− RhoH+/+ RhoH−/− total B cells 7.8±1.8 11.0±2.4 (**) total B cells 31.7±10.1 25.4±8.8 pro-B 0.12±0.03 0.15±0.04 (*) transitional 8.7±1.2 8.6±2.8 pre-B 2.6±0.6 3.8±0.8 (***) B-2 11.6±4.1 7.6±2.5 (*) immature 1.5±0.4 2.1±0.5 (*) marginal 3.2±1.1 3.9±1.6 mature 1.4±0.7 1.7±0.9

A Critical Role for Innate Immunity In Allogeneic Hematopoietic Cell Rejection Via the TLR4/TRIF Pathway

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 77-77
Author(s):  
Hong Xu ◽  
Jun Yan ◽  
Ziqiang Zhu ◽  
Yiming Huang ◽  
Yujie Wen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Innate Immunity ◽  
T Cells ◽  
Immune System ◽  
T Cell ◽  
Innate Immune System ◽  
Critical Role ◽  
Innate Immune ◽  
Wild Type

Abstract Abstract 77 Adaptive immunity, especially T cells, has long been believed to be the dominant immune barrier in allogeneic transplantation. Targeting host T cells significantly reduces conditioning for bone marrow cell (BMC) engraftment. Innate immunity has been recently shown to pose a significant barrier in solid organ transplantation, but has not been addressed in bone marrow transplantation (BMT). Using T cell deficient (TCR-β/δ−/−) or T and B cell deficient (Rag−/−) mice, we found that allogeneic BMC rejection occurred early before the time required for T cell activation and was T- and B-cell independent, suggesting an effector role for innate immune cells in BMC rejection. Therefore, we hypothesized that by controlling both innate and adaptive immunity, the donor BMC would have a window of advantage to engraft. Survival of BMC in vivo was significantly improved by depleting recipient macrophages and/or NK cells, but not neutrophils. Moreover, depletion of macrophages and NK cells in combination with co-stimulatory blockade with anti-CD154 and rapamycin as a novel form of conditioning resulted in 100% allogeneic engraftment without any irradiation and T cell depletion. Donor chimerism remained stable and durable up to 6 months. Moreover, specific Vβ5½ and Vβ11 clonal deletion was detected in host CD4+ T cells in chimeras, indicating central tolerance to donor alloantigens. Whether and how the innate immune system recognizes or responds to allogeneic BMCs remains unknown. Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. The signaling function of TLR depends on intracellular adaptors. The adaptor MyD88 transmits signals emanating from all TLR, except TLR3 while TRIF specifically mediates TLR3 and TLR4 signaling via type 1 IFN. To further determine the innate signaling pathways in allogeneic BMC rejection, B6 background (H2b) MyD88−/− and TRIF−/− mice were conditioned with anti-CD154/rapamycin plus 100 cGy total body irradiation and transplanted with 15 × 106 BALB/c (H2d) BMC. Only 33.3% of MyD88−/− recipients engrafted at 1 month, resembling outcomes for wild-type B6 mice. In contrast, 100% of TRIF−/− mice engrafted. The level of donor chimerism in TRIF−/− mice was 5.1 ± 0.6% at one month, significantly higher than in MyD88−/− and wild-type B6 controls (P < 0.005). To determine the mechanism of innate signaling in BMC rejection, we examined whether TRIF linked TLR3 or TLR4 is the key pattern recognition receptor involved in BMC recognition. To this end, TLR3−/− and TLR4−/− mice were transplanted with BALB/c BMC with same conditioning. None of the TLR3−/− mice engrafted. In contrast, engraftment was achieved in 100% of TLR4−/− mice up to 6 months follow up. Taken together, these results suggest that rejection of allogeneic BMC is uniquely dependent on the TLR4/TRIF signaling pathway. Thus, our results clearly demonstrate a previously unappreciated role for innate immunity in allogeneic BMC rejection. Our current findings are distinct from prior reports demonstrating a critical role of MyD88 in rejection of allogeneic skin grafts and lung, and may reflect unique features related to BMC. The findings of the role of innate immunity in BMC rejection would lead to revolutionary changes in our understanding and management of BMT. This would be informative in design of more specific innate immune targeted conditioning proposals in BMT to avoid the toxicity. Disclosures: Bozulic: Regenerex LLC: Employment. Ildstad:Regenerex LLC: Equity Ownership.

Non-Canonical NF-Kb Signaling Regulates Hematopoietic Stem Cell Self-Renewal and Microenvironment Interactions

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 859-859 ◽  
Author(s):  
Chen Zhao ◽  
Yan Xiu ◽  
John M Ashton ◽  
Lianping Xing ◽  
Yoshikazu Morita ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Wild Type ◽  
Double Knockout ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Physiological Processes ◽  
Marrow Cells

Abstract Abstract 859 RelB and NF-kB2 are the main effectors of NF-kB non-canonical signaling and play critical roles in many physiological processes. However, their role in hematopoietic stem/progenitor cell (HSPC) maintenance has not been characterized. To investigate this, we generated RelB/NF-kB2 double-knockout (dKO) mice and found that dKO HSPCs have profoundly impaired engraftment and self-renewal activity after transplantation into wild-type recipients. Transplantation of wild-type bone marrow cells into dKO mice to assess the role of the dKO microenvironment showed that wild-type HSPCs cycled more rapidly, were more abundant, and had developmental aberrancies: increased myeloid and decreased lymphoid lineages, similar to dKO HSPCs. Notably, when these wild-type cells were returned to normal hosts, these phenotypic changes were reversed, indicating a potent but transient phenotype conferred by the dKO microenvironment. However, dKO bone marrow stromal cell numbers were reduced, and bone-lining niche cells supported less HSPC expansion than controls. Further, increased dKO HSPC proliferation was associated with impaired expression of niche adhesion molecules by bone-lining cells and increased inflammatory cytokine expression by bone marrow cells. Thus, RelB/NF-kB2 signaling positively and intrinsically regulates HSPC self-renewal and maintains stromal/osteoblastic niches and negatively and extrinsically regulates HSPC expansion and lineage commitment through the marrow microenvironment. Disclosures: No relevant conflicts of interest to declare.

Conditioning Intensity and T Cell Dose Determine Efficacy of CD19-Targeted T Cell-Mediated Tumor Eradication in an Immunocompetent Mouse Model of B-ALL.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2613-2613
Author(s):  
Marco L Davila ◽  
Christopher Kloss ◽  
Renier J Brentjens ◽  
Michel Sadelain
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Immunocompetent Mouse ◽  
Cell Dose ◽  
Conditioning Intensity

Abstract Abstract 2613 Recent work by our group and others demonstrates the therapeutic potential of CD19-targeted T cells to treat patients with indolent B cell malignancies. These studies make use of T cells that are genetically engineered with chimeric antigen receptors (CARs) comprising an scFv fused to various T cell activating elements. Whereas firs-generation CARs only direct T cell activation, second-generation CARs include two signal elements, such as CD3z and CD28 signaling domains (19–28z). We and our colleagues at MSKCC are currently evaluating the safety of 19–28z-transduced T cells in patients with acute leukemia (B-ALL) in a Phase I protocol (NCT01044069). Pre-clinical studies performed to date have mostly relied on xenogeneic models utilizing immunodeficient animals, which enable the evaluation of human engineered T cells but do not recapitulate all the interactions that may affect tumor eradication by CAR-modified T cells. We have therefore developed a pre-clinical immunocompetent mouse model of B-ALL, and addressed therein the impact of conditioning and T cell dose on the eradication of leukemia by syngeneic, CAR-targeted T cells. To establish an immunocompetent mouse model of B cell leukemia, we generated a clone from the lymph node of an Eμ-myc B6 transgenic mouse. The immunophenotype and gene-expression profile of clone Eμ-ALL01 is consistent with a progenitor B cell origin. Syngeneic B6 mice inoculated with this clone develop florid acute leukemia and die approximately 2–4 weeks after injection from progressive bone marrow infiltration. We created an anti-mouse CD19 CAR comprising all murine elements, including the CD8 signal peptide, a CD19-specific single chain variable fragment, the CD8 transmembrane region, and the CD28 and CD3z signaling domains. Transduction of the murine 19–28z CAR into mouse T cells was robust and successfully retargeted the T cells to B cells. In vitro assays demonstrated that m19–28 z transduced T cells mediated effective killing of CD19-expressing target cells and the production of effector cytokines such as IFNγ and TNFα. Cyclophosphamide either alone or in combination with control syngeneic T cells is insufficient to eradicate established Eμ-ALL01 in B6 mice. However, treatment with cyclophosphamide and m19–28z-transduced T cells cured nearly all mice. Mice sacrificed six months after treatment exhibited a dramatic reduction of B cells in the bone marrow (BM), blood, and spleen. The few remaining B lineage cells found in the BM had a phenotype consistent with early pro-B cells, suggesting that endogenous reconstitution of the B cell compartment was thwarted by persisting, functional m19–28z+ T cells. Thus, T cells are retained at the site of antigen expression, which is maintained through regeneration of progenitor B cells. The persisting CD19-targeted T cells in the BM exhibited a cell surface phenotype consistent with effector and central memory cells. Using B cell aplasia as a surrogate endpoint for assessing in vivo T cell function and persistence, we evaluated how conditioning chemotherapy and T cell dose determine the level of B cell depletion induced by adoptively transferred CD19-targeted T cells. Overall, increasing the cyclophosphamide or T cell dose, increased the degree and duration of B cell depletion and the number of persisting CAR-modified T cells. Significantly, increasing the T cell dose at a set cyclophosphamide level had a lesser impact than increasing the conditioning intensity for a given T cell dose. In summary, the new Eμ-ALL01 syngeneic, immunocompetent B-ALL model we describe here is a valuable tool for modeling CD19 CAR therapies. Our results indicate that m19–28z transduced T cells are effective at eradicating B-ALL tumor cells and persist long-term, preferentially in bone marrow. Our findings further establish that conditioning intensity and T cell dose directly determine B cell elimination and long-term T cell persistence. These studies in mice will serve as an important framework to further model and perfect our studies in patients with B-ALL. Disclosures: No relevant conflicts of interest to declare.

Promoting Regulation Via the Inhibition of DNAM-1 After Transplantation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 338-338
Author(s):  
Motoko Koyama ◽  
Rachel D Kuns ◽  
Stuart D Olver ◽  
Katie E Lineburg ◽  
Mary Lor ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Steady State ◽  
T Cell ◽  
Median Survival ◽  
Cd4 T Cells ◽  
Cell Expansion ◽  
Acute Gvhd ◽  
Cd4 T Cell

Abstract Abstract 338 Graft-versus-host disease (GVHD) is the major limitation of allogeneic hematopoietic bone marrow transplantation (BMT). Donor T cells play pivotal roles in GVHD and graft-versus-leukemia (GVL) effects and following BMT all T cell fractions, including regulatory T cells (Treg) express the DNAX accessory molecule-1 (DNAM-1, CD226) and T cell Immunoglobulin and ITIM domain (TIGIT) molecule. DNAM-1 is a co-stimulatory and adhesion molecule, expressed mainly by NK cells and CD8+ T cells at steady state to promote adhesion to ligand (CD155, CD112)–expressing targets and enhance cytolysis. TIGIT is a regulatory ligand expressed predominantly by Treg as steady state which competes for CD155 binding, We have analyzed the role of this pathway in GVHD and GVL. Lethally irradiated C3H/Hej (H-2k) mice were injected with bone marrow cells and T cells from MHC disparate wild-type (wt) or DNAM-1–/– C57Bl6 (H-2b) mice. Recipients of DNAM-1–/– grafts were protected from GVHD (survival 67% vs. 7%, P < .0001). We also confirmed the role of DNAM-1 in GVHD in a MHC-matched BMT model (B6 → BALB/B (H-2b)) where GVHD is directed to multiple minor histocompatibility antigens. Next we examined the donor populations expressing DNAM-1 which mediate this effect. DNAM-1 had little impact on acute GVHD severity in the B6 → bm1 BMT model where GVHD is directed against an isolated MHC class I mismatch and is CD8-dependent. In contrast, recipients of wt bone marrow and DNAM-1–/– CD4 T cells survived long-term (compared to recipients of wt CD4 T cells, survival 81% vs. 25%, P = .003) in the B6 → B6C3F1 BMT model, confirming the protection from GVHD is CD4-dependent. Donor CD4 T cell expansion and effector function (Th1 and Th17), and CD8 T cell expansion and cytotoxic function were equivalent in recipients of wt and DNAM-1–/– grafts. However the percentage and number of Treg were significantly increased in recipients of DNAM-1–/– grafts compared to those of wt grafts. The depletion of Treg from donor grafts eliminated the protection from GVHD seen in the absence of DNAM-1 signalling (median survival 16 days vs. 15.5 days, P = 0.53). Adoptive transfer experiments using FACS-sorted Treg were undertaken to compare the relative ability of B6.WT and B6.DNAM-1–/– Treg to suppress GVHD. The majority of recipients of DNAM-1–/– Treg survived beyond day 50 (median survival; day 56), demonstrating a superior ability to suppress acute GVHD relative to wt Treg where the median survival was day 36 (survival 47% vs. 0%, P = .001). These data demonstrate that donor DNAM-1 expression promotes GVHD in a CD4+ T cell-dependent manner via the inhibition of donor Foxp3+ Treg. Finally, the absence of donor DNAM-1 did not influence leukemia-specific mortality in multiple GVL models, regardless of whether the tumor expressed CD155 or not. Thus we demonstrate that the DNAM-1 pathway promotes GVHD, putatively due to competition with TIGIT on Treg, thereby inhibiting regulatory function. This provides support for therapeutic DNAM-1 inhibition to promote tolerance not only after transplant but also in relevant inflammatory based diseases characterized by T cell activation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Reproducing Transformation of Indolent B-cell Lymphoma by T-cell Immunosuppression of L.CD40 Mice

2018 ◽  
Author(s):  
Christelle Vincent-Fabert ◽  
Alexis Saintamand ◽  
Amandine David ◽  
Mehdi Alizadeh ◽  
François Boyer ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Immune Suppression ◽  
Clinical Course ◽  
Cell Lymphoma ◽  
Immune Surveillance ◽  
B Cell Lymphoma

AbstractTransformation of an indolent B-cell lymphoma is associated with a more aggressive clinical course and poor survival. The role of immune surveillance in the transformation of a B-cell indolent lymphoma towards a more aggressive form is poorly documented. To experimentally address this question, we used the L.CD40 mouse model, which is characterized by B-cell specific continuous CD40 signaling, responsible for spleen indolent clonal or oligoclonal B-cell lymphoma after one year in 60% cases. Immunosuppression was obtained either by T/NK cell depletion or by treatment with the T-cell immunosuppressive drug cyclosporin A. Immunosuppressed L.CD40 mice had larger splenomegaly with increased numbers of B-cells in both spleen and peripheral blood. High-throughput sequencing of immunoglobulin variable segments revealed that clonal expansion was increased in immunosuppressed L.CD40 mice. Tumor B cells of immunosuppressed mice were larger with an immunoblastic aspect, both on blood smears and spleen tissue sections, with increased proliferation rate and increased numbers of activated B-cells. Collectively, these features suggest that immune suppression induced a shift from indolent lymphomas into aggressive ones. Thus, as a preclinical model, immunosuppressed L.CD40 mice reproduce aggressive transformation of an indolent B-cell tumor and highlight the role of the immune surveillance in its clinical course, opening new perspective for immune restoration therapies.Summary statementHighlighting the role of immune surveillance, transformation of indolent B-cell lymphoma into an aggressive malignancy is experimentally reproduced after T-cell immune suppression in the L.CD40 preclinical mouse model.

Loss of Gfi1 Impedes Development of T-Cell Lymphoma upon Exposure to N-ethyl-N-nitrosourea but Predisposes to Severe Myleodysplastic Changes.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2221-2221
Author(s):  
Cyrus Khandanpour ◽  
Ulrich Duehrsen ◽  
Tarik Möröy
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Dna Damage ◽  
T Cell ◽  
Bone Marrow Cells ◽  
Cell Lymphoma ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Deficient Mice

Abstract Exogenous toxic substances often cause the initiation and development of leukemia and lymphoma by acting as mutagens. N-ethyl-N-nitrosourea (ENU) is a paradigmatic example for such a substance, which introduces point mutations in the genome through DNA damage and repair pathways. ENU is widely used to experimentally induce T-cell lymphomas in mice. We have used ENU to investigate whether the hematopoietic transcription factor Gfi1 is required for lymphomagenesis. The Gfi1 gene was originally discovered as a proviral target gene and a series of experiments with transgenic mice had suggested a role of Gfi1 as a dominant oncogene with the ability to cooperate with Myc and Pim genes in the generation of T-cell lymphoma. In addition, Gfi1 deficient mice showed a defect in T-cell maturation but also aberration in myeloid differentiation and an accumulation of myelomonocytic cells. ENU was administered i.p. once a week for three weeks with a total dose of 300mg/kg to wild type (wt) and Gfi1 null mice. Wild type mice (12/12) predominantly developed T-cell tumors and rarely acute myeloid leukemia, as expected. However, only 2/8 Gfi1 −/− mice succumbed to lymphoid neoplasia; they rather showed a severe dysplasia of the bone marrow that was more pronounced than in wt controls. These changes in Gfi1 null mice were accompanied by a dramatic decrease of the LSK (Lin-, Sca1- and c-Kit+) bone marrow fraction that contains hematopoietic stem cells and by a higher percentage (18%) of bone marrow cells, not expressing any lineage markers (CD4, CD 8, Ter 119, Mac1, Gr1, B220, CD3). In particular, we found that the LSK subpopulation of Gfi1 deficient mice showed a noticeable increase in cells undergoing apoptosis suggesting a role of Gfi1 in hematopoietic stem cell survival. In addition, Gfi1−/− bone marrow cells and thymic T-cells were more sensitive to DNA damage such as radiation and exposure to ENU than their wt counterparts pointing to a role of Gfi1 in DNA damage response. Our results indicate that Gfi1 is required for development of T-cell tumors and that a loss of Gfi1 may sensitize hematopoietic cells and possibly hematopoietic stem cells for programmed cell death. Further studies have to show whether interfering with Gfi1 expression or function might represent a tool in the therapy of leukemia.

TLE1 Null Mice Have Altered Myeloid and B-Cell Differentiation As Well As Impaired Regulation of Inflammation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1197-1197 ◽  
Author(s):  
Selvi Ramasamy ◽  
Saez Borja ◽  
Subhankar Mukhopadhyay ◽  
Jianfeng Wang ◽  
Daching Ding ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Tumor Suppressor ◽  
Inflammatory Cytokines ◽  
Knockout Mice ◽  
Suppressor Gene ◽  
Wild Type ◽  
Hematopoietic System ◽  
Knock Out ◽  
Knock Out Mice

Abstract Abstract 1197 TLE1 belongs to the Groucho/TLE family of co-repressors that act as master regulators during development affecting segmentation, neurogenesis, myogenesis, and multiple cell fate decisions. TLE1 modulate several major signaling pathways including Wnt and Notch, and specifically interacts with multiple transcription factors involved in hematopoiesis such TCF/LEF, HES1, RUNX1/AML. TLE1 has also been implicated in Crohn's disease via its interaction with NOD2, a regulator of NFkB. Our laboratory identified TLE1 as a likely AML tumor suppressor gene, commonly deleted in subgroups of AML, and others have shown its role as a tumor suppressor gene in myeloid and other hematopoietic malignancies. To better understand the role of TLE1 in hematopoiesis and leukemogenesis we created a line of Tle1 null mice. Tle1 null mice are born normally, but become progressively growth retarded by 3 days of life, with only 50% survival by 4 weeks as compared to heterozygous and wild type littermates. Abnormalities are observed in several organs systems including the hematopoietic system. We characterized the hematopoietic system in Tle1 knock out mice between two and 12 weeks of age. The bone marrow cellularity in the Tle1 knock out mice is comparable to the wild type mice at all time points examined. However, frequency of granulocyte macrophage progenitors in bone marrow mononuclear cells is significantly higher in the Tle1 knockout bone marrow compared to heterozygous and wild type mice. The proportion and number of myeloid cells as evidenced by Gr1, Mac1 expression are significantly higher in the bone marrow, spleen and blood of these knockout mice. There were significantly lower B-cells (B220+cells) in the Tle1 knockout mice compared to heterozygous and wild type. In colony forming assays there was a trend towards higher number of CFU-GM (7.66 vs 5), p=0.07) and CFU-M (27.16 vs 12.5, p=0.05) colonies from Tle1 null bone marrow as compared to wild type bone marrow. The spleens from four week and 17 months old Tle1 knockout mice had higher frequency of Gr1-negative, Mac1-positive and F4/80 positive macrophages. We also observed a significantly higher production of the inflammatory cytokines IL6 and TNFafrom peritoneal macrophages harvested from Tle1 null mice as compared to those from wild type mice in response to TLR ligand stimulation. To investigate the potential mechanism of this inhibitory effect of TLE1 on inflammation we demonstrated that TLE1 expression is able to block the nuclear translocation of NFkB in THP1 cells in response to LPS-K12 (p<0.05). In summary this work demonstrates that the lack of Tle1 expression biases hematopoiesis towards myeloid differentiation, a finding of potential relevance given the inactivation of TLE1 seen in subsets of myeloid malignancies. We further show that inactivation of Tle1 leads to an increase in macrophages primed to release increased inflammatory cytokines. This is notable given the recent observation that TLE1 may modulate the effects of NOD2 in the pathogenesis of Crohn's disease. These Tle1 null mice will allow the investigation of the potential role of TLE1 as a modulator of a variety of other inflammatory diseases. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The Influence of Bone Marrow-Secreted IL-10 in a Mouse Model of Cerulein-Induced Pancreatic Fibrosis

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Wey-Ran Lin ◽  
Siew-Na Lim ◽  
Tzung-Hai Yen ◽  
Malcolm R. Alison
Keyword(s):  
Bone Marrow ◽  
Mouse Model ◽  
Inflammatory Cell ◽  
Inflammatory Cell Infiltration ◽  
Pancreatic Fibrosis ◽  
Cell Infiltration ◽  
Collagen Deposition ◽  
Wild Type

This study aimed to understand the role of IL-10 secreted from bone marrow (BM) in a mouse model of pancreatic fibrosis. The severity of cerulein-induced inflammation, fibrosis, and the frequency of BM-derived myofibroblasts were evaluated in the pancreas of mice receiving either a wild-type (WT) BM or an IL-10 knockout (KO) BM transplantation. The area of collagen deposition increased significantly in the 3 weeks after cerulein cessation in mice with an IL-10 KO BM transplant (13.7 ± 0.6% and 18.4 ± 1.1%,p< 0.05), but no further increase was seen in WT BM recipients over this time. The percentage of BM-derived myofibroblasts also increased in the pancreas of the IL-10 KO BM recipients after cessation of cerulein (6.7 ± 1.1% and 11.9 ± 1.3%,p< 0.05), while this figure fell in WT BM recipients after cerulein withdrawal. Furthermore, macrophages were more numerous in the IL-10 KO BM recipients than the WT BM recipients after cerulein cessation (23.2 ± 2.3 versus 15.3 ± 1.7 per HPF,p< 0.05). In conclusion, the degree of fibrosis, inflammatory cell infiltration, and the number of BM-derived myofibroblasts were significantly different between IL-10 KO BM and WT BM transplanted mice, highlighting a likely role of IL-10 in pancreatitis.

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