scholarly journals Harnessing Treg Homeostasis to Optimize Posttransplant Immunity: Current Concepts and Future Perspectives

2021 ◽  
Vol 12 ◽  
Author(s):  
Shuntaro Ikegawa ◽  
Ken-ichi Matsuoka
Keyword(s):  
T Cells ◽  
Therapeutic Strategy ◽  
Environmental Changes ◽  
Checkpoint Inhibitors ◽  
Interleukin 2 ◽  
Extrinsic Factors ◽  
Hematopoietic Stem ◽  
Factors Affecting ◽  
Post Transplant ◽  
Necessary And Sufficient

CD4+CD25+Foxp3+ regulatory T cells (Tregs) are functionally distinct subsets of mature T cells with broad suppressive activity and have been shown to play an important role in the establishment of immune tolerance after allogeneic hematopoietic stem cell transplantation (HSCT). Tregs exhibit an activated phenotype from the stage of emigration from the thymus and maintain continuous proliferation in the periphery. The distinctive feature in homeostasis enables Tregs to respond sensitively to small environmental changes and exert necessary and sufficient immune suppression; however, on the other hand, it also predisposes Tregs to be susceptible to apoptosis in the inflammatory condition post-transplant. Our studies have attempted to define the intrinsic and extrinsic factors affecting Treg homeostasis from the acute to chronic phases after allogeneic HSCT. We have found that altered cytokine environment in the prolonged post-HSCT lymphopenia or peri-transplant use of immune checkpoint inhibitors could hamper Treg reconstitution, leading to refractory graft-versus-host disease. Using murine models and clinical trials, we have also demonstrated that proper intervention with low-dose interleukin-2 or post-transplant cyclophosphamide could restore Treg homeostasis and further amplify the suppressive function after HSCT. The purpose of this review is to reconsider the distinctive characteristics of post-transplant Treg homeostasis and discuss how to harness Treg homeostasis to optimize posttransplant immunity for developing a safe and efficient therapeutic strategy.

scholarly journals Targeting Interleukin-2-Inducible T-Cell Kinase (ITK) Differentiates GVL and GVHD in Allo-HSCT

2020 ◽  
Vol 11 ◽  
Author(s):  
Mahinbanu Mammadli ◽  
Weishan Huang ◽  
Rebecca Harris ◽  
Aisha Sultana ◽  
Ying Cheng ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lymphoblastic Leukemia ◽  
Interleukin 2 ◽  
Treatment Strategies ◽  
Receptor Expression ◽  
Hematopoietic Stem ◽  
Target Organs ◽  
Donor T Cells ◽  
Inducible T Cell Kinase

Allogeneic hematopoietic stem cell transplantation is a potentially curative procedure for many malignant diseases. Donor T cells prevent disease recurrence via graft-versus-leukemia (GVL) effect. Donor T cells also contribute to graft-versus-host disease (GVHD), a debilitating and potentially fatal complication. Novel treatment strategies are needed which allow preservation of GVL effects without causing GVHD. Using murine models, we show that targeting IL-2-inducible T cell kinase (ITK) in donor T cells reduces GVHD while preserving GVL effects. Both CD8+ and CD4+ donor T cells from Itk-/- mice produce less inflammatory cytokines and show decrease migration to GVHD target organs such as the liver and small intestine, while maintaining GVL efficacy against primary B-cell acute lymphoblastic leukemia (B-ALL). Itk-/- T cells exhibit reduced expression of IRF4 and decreased JAK/STAT signaling activity but upregulating expression of Eomesodermin (Eomes) and preserve cytotoxicity, necessary for GVL effect. Transcriptome analysis indicates that ITK signaling controls chemokine receptor expression during alloactivation, which in turn affects the ability of donor T cells to migrate to GVHD target organs. Our data suggest that inhibiting ITK could be a therapeutic strategy to reduce GVHD while preserving the beneficial GVL effects following allo-HSCT treatment.

scholarly journals CD28-B7 interactions allow the induction of CD8+ cytotoxic T lymphocytes in the absence of exogenous help.

1993 ◽  
Vol 177 (6) ◽  
pp. 1791-1796 ◽  
Author(s):  
F A Harding ◽  
J P Allison
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cytotoxic T Cells ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Histocompatibility Complex ◽  
Necessary And Sufficient ◽  
Additional Antigen

The activation requirements for the generation of CD8+ cytotoxic T cells (CTL) are poorly understood. Here we demonstrate that in the absence of exogenous help, a CD28-B7 interaction is necessary and sufficient for generation of class I major histocompatibility complex-specific CTL. Costimulation is required only during the inductive phase of the response, and not during the effector phase. Transfection of the CD28 counter receptor, B7, into nonstimulatory P815 cells confers the ability to elicit P815-specific CTL, and this response can be inhibited by anti-CD28 Fab or by the chimeric B7-binding protein CTLA4Ig. Anti-CD28 monoclonal antibody (mAb) can provide a costimulatory signal to CD8+ T cells when the costimulatory capacity of splenic stimulators is destroyed by chemical fixation. CD28-mediated signaling provokes the release of interleukin 2 (IL-2) from the CD8+ CTL precursors, as anti-CD28 mAb could be substituted for by the addition of IL-2, and an anti-IL-2 mAb can block the generation of anti-CD28-induced CTL. CD4+ cells are not involved in the costimulatory response in the systems examined. We conclude that CD8+ T cell activation requires two signals: an antigen-specific signal mediated by the T cell receptor, and an additional antigen nonspecific signal provided via a CD28-B7 interaction.

scholarly journals Predictors of neutralizing antibody response to BNT162b2 vaccination in allogeneic hematopoietic stem cell transplant recipients

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Lorenzo Canti ◽  
Stéphanie Humblet-Baron ◽  
Isabelle Desombere ◽  
Julika Neumann ◽  
Pieter Pannus ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Chronic Gvhd ◽  
Neutralizing Antibody ◽  
Healthy Adults ◽  
Cell Transplant ◽  
Hematopoietic Stem ◽  
Factors Affecting

Abstract Background Factors affecting response to SARS-CoV-2 mRNA vaccine in allogeneic hematopoietic stem cell transplantation (allo-HCT) recipients remain to be elucidated. Methods Forty allo-HCT recipients were included in a study of immunization with BNT162b2 mRNA vaccine at days 0 and 21. Binding antibodies (Ab) to SARS-CoV-2 receptor binding domain (RBD) were assessed at days 0, 21, 28, and 49 while neutralizing Ab against SARS-CoV-2 wild type (NT50) were assessed at days 0 and 49. Results observed in allo-HCT patients were compared to those obtained in 40 healthy adults naive of SARS-CoV-2 infection. Flow cytometry analysis of peripheral blood cells was performed before vaccination to identify potential predictors of Ab responses. Results Three patients had detectable anti-RBD Ab before vaccination. Among the 37 SARS-CoV-2 naive patients, 20 (54%) and 32 (86%) patients had detectable anti-RBD Ab 21 days and 49 days postvaccination. Comparing anti-RBD Ab levels in allo-HCT recipients and healthy adults, we observed significantly lower anti-RBD Ab levels in allo-HCT recipients at days 21, 28 and 49. Further, 49% of allo-HCT patients versus 88% of healthy adults had detectable NT50 Ab at day 49 while allo-HCT recipients had significantly lower NT50 Ab titers than healthy adults (P = 0.0004). Ongoing moderate/severe chronic GVHD (P < 0.01) as well as rituximab administration in the year prior to vaccination (P < 0.05) correlated with low anti-RBD and NT50 Ab titers at 49 days after the first vaccination in multivariate analyses. Compared to healthy adults, allo-HCT patients without chronic GVHD or rituximab therapy had comparable anti-RBD Ab levels and NT50 Ab titers at day 49. Flow cytometry analyses before vaccination indicated that Ab responses in allo-HCT patients were strongly correlated with the number of memory B cells and of naive CD4+ T cells (r > 0.5, P < 0.01) and more weakly with the number of follicular helper T cells (r = 0.4, P = 0.01). Conclusions Chronic GVHD and rituximab administration in allo-HCT recipients are associated with reduced Ab responses to BNT162b2 vaccination. Immunological markers could help identify allo-HCT patients at risk of poor Ab response to mRNA vaccination. Trial registration The study was registered at clinicaltrialsregister.eu on 11 March 2021 (EudractCT # 2021-000673-83).

scholarly journals Impact of Different T Cell Depletion Protocols on Immune Reconstitution Following Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 43-44
Author(s):  
Amandine Pradier ◽  
Adrien Petitpas ◽  
Anne-Claire Mamez ◽  
Federica Giannotti ◽  
Sarah Morin ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Reconstitution ◽  
Cell Depletion ◽  
Unrelated Donor ◽  
T Cell Depletion ◽  
Hematopoietic Stem ◽  
Post Transplant ◽  
The Impact

Introduction Allogeneic hematopoietic stem cell transplantation (HSCT) is a well-established therapeutic modality for a variety of hematological malignancies and congenital disorders. One of the major complications of the procedure is graft-versus-host-disease (GVHD) initiated by T cells co-administered with the graft. Removal of donor T cells from the graft is a widely employed and effective strategy to prevent GVHD, although its impact on post-transplant immune reconstitution might significantly affect anti-tumor and anti-infectious responses. Several approaches of T cell depletion (TCD) exist, including in vivo depletion using anti-thymocyte globulin (ATG) and/or post-transplant cyclophosphamide (PTCy) as well as in vitro manipulation of the graft. In this work, we analyzed the impact of different T cell depletion strategies on immune reconstitution after allogeneic HSCT. Methods We retrospectively analysed data from 168 patients transplanted between 2015 and 2019 at Geneva University Hospitals. In our center, several methods for TCD are being used, alone or in combination: 1) In vivo T cell depletion using ATG (ATG-Thymoglobulin 7.5 mg/kg or ATG-Fresenius 25 mg/kg); 2) in vitro partial T cell depletion (pTCD) of the graft obtained through in vitro incubation with alemtuzumab (Campath [Genzyme Corporation, Cambridge, MA]), washed before infusion and administered at day 0, followed on day +1 by an add-back of unmanipulated grafts containing about 100 × 106/kg donor T cells. The procedure is followed by donor lymphocyte infusions at incremental doses starting with 1 × 106 CD3/kg at 3 months to all patients who had received pTCD grafts with RIC in the absence of GVHD; 3) post-transplant cyclophosphamide (PTCy; 50 mg/kg) on days 3 and 4 post-HSCT. Absolute counts of CD3, CD4, CD8, CD19 and NK cells measured by flow cytometry during the first year after allogeneic HSCT were analyzed. Measures obtained from patients with mixed donor chimerism or after therapeutic DLI were excluded from the analysis. Cell numbers during time were compared using mixed-effects linear models depending on the TCD. Multivariable analysis was performed taking into account the impact of clinical factors differing between patients groups (patient's age, donor type and conditioning). Results ATG was administered to 77 (46%) patients, 15 (9%) patients received a pTCD graft and 26 (15%) patients received a combination of both ATG and pTCD graft. 24 (14%) patients were treated with PTCy and 26 (15%) patients received a T replete graft. 60% of patients had a reduced intensity conditioning (RIC). 48 (29%) patients received grafts from a sibling identical donor, 94 (56%) from a matched unrelated donor, 13 (8%) from mismatched unrelated donor and 13 (8%) received haploidentical grafts. TCD protocols had no significant impact on CD3 or CD8 T cell reconstitution during the first year post-HSCT (Figure 1). Conversely, CD4 T cells recovery was affected by the ATG/pTCD combination (coefficient ± SE: -67±28, p=0.019) when compared to the T cell replete group (Figure 1). Analysis of data censored for acute or chronic GVHD requiring treatment or relapse revealed a delay of CD4 T cell reconstitution in the ATG and/or pTCD treated groups on (ATG:-79±27, p=0.004; pTCD:-100±43, p=0.022; ATG/pTCD:-110±33, p&lt;0.001). Interestingly, pTCD alone or in combination with ATG resulted in a better reconstitution of NK cells compared to T replete group (pTCD: 152±45, p&lt;0.001; ATG/pTCD: 94±36, p=0.009; Figure 1). A similar effect of pTCD was also observed for B cells (pTCD: 170±48, p&lt;.001; ATG/pTCD: 127±38, p&lt;.001). The effect of pTCD on NK was confirmed when data were censored for GVHD and relapse (pTCD: 132±60, p=0.028; ATG/pTCD: 106±47, p=0.023) while only ATG/pTCD retained a significant impact on B cells (102±49, p=0.037). The use of PTCy did not affect T, NK or B cell reconstitution when compared to the T cell replete group. Conclusion Our results indicate that all TCD protocols with the only exception of PTCy are associated with a delayed recovery of CD4 T cells whereas pTCD of the graft, alone or in combination with ATG, significantly improves NK and B cell reconstitution. Figure 1 Disclosures No relevant conflicts of interest to declare.

scholarly journals Autoimmunity linked protein phosphatase PTPN22 as a target for cancer immunotherapy

2020 ◽  
Vol 8 (2) ◽  
pp. e001439 ◽  
Author(s):  
Rafael Cubas ◽  
Zia Khan ◽  
Qian Gong ◽  
Marina Moskalenko ◽  
Huizhong Xiong ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cancer Immunotherapy ◽  
Phosphatase Activity ◽  
Tumor Regression ◽  
Checkpoint Inhibitors ◽  
Therapeutic Option ◽  
Interleukin 2 ◽  
Cell Functions ◽  
Increased Risk

BackgroundCancer immunotherapy has evolved from interferon-alpha (IFNα) and interleukin-2 in the 1980s to CTLA-4 and PD-1/PD-L1 checkpoint inhibitors (CPIs), the latter highlighting the importance of enhancing T-cell functions. While the search for novel immunomodulatory pathways continues, combination therapies augmenting multiple pathways can also increase efficacy. The association of autoimmune-related adverse events with clinical efficacy following CPI treatment has been inferred and suggests that breaking tolerance thresholds associated with autoimmunity may affect host immune responses for effective cancer immunotherapy.ResultsHere, we show that loss of autoimmune associated PTPN22, a key desensitization node for multiple signaling pathways, including IFNα receptor (IFNAR) and T-cell receptor, can augment tumor responses. Implantation of syngeneic tumors in Ptpn22-/- mice led to expansion and activation of peripheral and intratumoral T cells and, in turn, spontaneous tumor regression as well as enhanced responses in combination with anti-PD-L1 treatment. Using genetically modified mice expressing a catalytically inactive PTPN22 or the autoimmunity-associated human single-nucleotide polymorphism variant, augmentation of antitumor immunity was dependent on PTPN22 phosphatase activity and partially on its adaptor functions. Further, antitumor responses were dependent on both CD4+ and CD8+T cells and, in part, IFNAR function. Finally, we demonstrate that the autoimmune susceptibility Ptpn22(C1858T) variant is associated with lower risk of developing non-melanoma skin cancers, improved overall survival and increased risk for development of hyperthyroidism or hypothyroidism following atezolizumab (anti-PD-L1) treatment.ConclusionsTogether, these data suggest that inhibition of PTPN22 phosphatase activity may provide an effective therapeutic option for cancer immunotherapy and that exploring genetic variants that shift immune tolerance thresholds may serve as a paradigm for finding new cancer immunotherapy targets.

Rapid T Cell Recovery and Possible Auto-GVHD Following Adoptive Transfer of Ex-Vivo Costimulated Autologous T Cells at Day +2 Post-Transplant.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 769-769 ◽  
Author(s):  
Aaron P. Rapoport ◽  
Stephan A. Grupp ◽  
Edward A. Stadtmauer ◽  
Robert H. Vonderheide ◽  
Bruce L. Levine ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adoptive Transfer ◽  
Ex Vivo ◽  
Cell Recovery ◽  
Hematopoietic Stem ◽  
Post Transplant ◽  
Cell Counts ◽  
Engraftment Syndrome ◽  
The Impact

Abstract Retrospective studies suggest that rapid lymphocyte recovery following autologous stem cell transplants (SCT) may be associated with better outcomes. Previously we showed that adoptive transfer of in-vivo vaccine-primed and ex-vivo (anti-CD3/anti-CD28) costimulated autologous T cells (ex-T) at about day 14 post-transplant increased CD4 and CD8 T cell counts at day 42 post-transplant and induced pneumococcal conjugate vaccine-directed T and B-cell responses [Rapoport et al, Nature Medicine, 2005]. In 2 current studies, we are further investigating the impact of ex-vivo costimulated autologous T cells on vaccine responses after SCT. In the first study, we are investigating whether a similar strategy of pre- and post-transplant immunizations along with an early infusion of vaccine-primed ex-T can induce responses to a putative tumor vaccine composed of 4 HLA-A2-restricted peptides derived from survivin and hTERT in pts undergoing SCT for myeloma. In the second (randomized) trial, the impact of early ex-T on immune recovery and vaccine reponses is being tested in pediatric neuroblastoma pts. Compared to the previous study, two methodologic changes were made: The target number of T cells infused was raised 5-fold to 5 x 1010 (109/kg) T cells were infused on day + 2 to take greater advantage of homeostatic expansion mechanisms. Patients were monitored for delayed hematopoietic recovery because of this switch to early ex-T and the fact that survivin and hTERT are also expressed in hematopoietic stem cells. At the time of submission, 16 adult and 30 pediatric patients have been enrolled on these trials of whom 11 and 21, respectively, are evaluable for post-transplant hematopoietic and T-cell recovery. On the myeloma trial, the mean # of T cells infused was 3.95 x 1010 with 96% viability and a CD4/CD8 ratio of 1.8:1. At day 14 post-transplant, the median CD4 count was 1951/mcl (range 651–7668) and the median CD8 count was 4117/mcl (range 1499–39,354). The median # days to achieve an absolute neutrophil count (ANC) > 500 was 12 (range 11–14) and the median # days to achieve a PLT count >20,000/mcl was 13 days (range 0–28). Similarly, in the pediatric cohort, median CD4 and CD8 counts at day 30 were 1500 and 2100/mcl, respectively, compared to 22 and 14 in a group of pts who did not receive d+2 ex-T, with no impact on engraftment. 1 adult and 3 pediatric pts also developed an “engraftment syndrome” characterized by GHVD-like features with or without fever. The adult pt with day 14 CD4 and CD8 counts of 2,724 and 11,571 cells/mcl had clinical and histologic features of (autologous) gut GVHD. 3 pediatric pts developed pruritic rashes clinically and pathologically indistiguishable from GVHD within 14 d of ex-T infusion, with fever seen in 1. In the adult and 1 pediatric pt, steroid treatment led to complete resolution of symptoms. These combined data sets demonstrate that robust CD4 and CD8 T cells counts can be achieved as early as day 14 post-SCT when adults or children receive ex-T at day +2 post-SCT without exogenous IL-2 or other cytokine support. It appears that a subset of patients develop a T cell “engraftment syndrome” similar to autologous GVHD. The mechanisms responsible for this rapid immune cell recovery are currently under investigation.

CD11b− Donor Dendritic Cells Enhance Donor T-Cells’ Th1 Polarization and Graft Versus Leukemia Activity in Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1252-1252 ◽  
Author(s):  
Jian-Ming Li ◽  
Kataryna A. Darlak ◽  
Ying Lu ◽  
Cynthia Giver ◽  
Wayne Harris ◽  
...  
Keyword(s):  
T Cells ◽  
Serum Levels ◽  
Hematopoietic Stem ◽  
Treatment Groups ◽  
Post Transplant ◽  
Tumor Bearing ◽  
Donor T Cells ◽  
Ifn Γ ◽  
Th1 Cytokines

Abstract Background: Based on a clinical association of donor plasmacytoid dendritic cell (DC) content with leukemia relapses after allogeneic BMT (Waller, Blood 2001), we have previously reported that CD11b− donor DC added to a graft containing FACS-purified hematopoietic stem cells (HSC) and T-cells enhanced interferon-γ (IFN-γ) production and GvL activity in MHC-mismatched allogeneic transplant mouse models (Li, Blood 2007). Objective: In this study, we studied the mechanisms whereby donor DC in the graft modulate donor T-cell activity and the graft-versus-leukemia (GvL) effect in MiHA (C3H.SW → C57BL/6J)- and MHC (C57BL/6J → B10.BR)- mismatched models of allogeneic hematopoietic stem cell transplantation (HSCT). Methods: Mice irradiated to 11 Gy received 5 × 104 log-phase viable MMB3.19 myeloid lymphoma cells via intraperitoneal injection or intravenous injection of 1 x 105 LBRM T-cell lymphoma cells one day before transplant. Allografts consisted of 5 × 104 FACS-purified donor BM CD11b− DC or CD11b+ DC plus 3 × 103 FACS-purified c-kit+ sca-1+ lineage− hematopoietic stem cells (HSC) in combination with either 3 × 105 T-cells, 3 × 105 CD8+ T-cells or no additional T-cells transplanted via tail vein. Graft-versus-host disease (GvHD) clinical scores (based on body weight loss, posture, skin, fur texture, activity) were recorded twice weekly in non-tumor bearing recipients. In vitro proliferation and cytotoxic activity of donor-derived T-cells against tumor targets was assessed by CFSE staining and a caspase flow cytometry assay (CyToxiLux PLUS) using donor T-cells harvested from recipients on day 34 and day 82 post transplant. Serum and intracellular Th1 cytokines (IFN-γ, IL-2, and TNF-α) and Th2 cytokines (IL-4, IL-5, and IL-10) from recipients’ peripheral blood and spleens day 3 and day 10 post-transplant was measured by ELISA and flow cytometry. IFN-γ direct killing of leukemia cells was tested by in vitro IFN-γ exposure. Results: In non-tumor bearing mice, recipients of all combinations of donor DC subsets, with and without donor T-cells had equivalent survival (75% – 85%) at 3 months post transplant without significant clinical signs of GvHD. Transplantation of tumor cells to recipients of HSC alone, HSC plus donor T-cells, or HSC plus T-cells and CD11b+ DC in the MiHA- and the MHC-mismatched transplant models led to 0% or 5% 3 month survival, respectively. Strikingly, tumor-bearing mice transplanted with CD11b− DC had significantly enhanced 3 month survival (35% in the MiHA-mismatched model and 45% in the MHCmismatched model) without increased GvHD (p&lt;0.001). There was no significant difference in survival between mice that received HSC plus CD11b− DC and a mixture of CD4+ and CD8+ donor T-cells versus mice that received HSC plus CD11b− DC and only CD8+ donor T-cells. Donor T-cells harvested from recipients of CD11b− DC 34 days after transplant in the MiHA-mismatched model as well as 82 days after transplant in the MHC-mismatched model displayed increased cell proliferation following co-culture with irradiated hosttype splenocytes as a source of alloantigen compared with donor T-cells harvested from recipients of CD11b+ DC or recipients of HSC plus T-cells without donor DC. Leukemia cell killing was greater following incubation of purified donor T-cells recovered from recipients of CD11b− DC with tumor targets compared to T-cells recovered from other treatment groups. Recipients of CD11b− DC had higher serum levels of Th1 cytokines IFN-γ and IL-2 and higher number of Th1 positive donor T-cells compared with recipients of other treatment groups. In contrast, recipients of CD11b+ DC had higher serum levels of Th2 cytokines IL-4, IL-5, and IL-10 and higher number of Th2 positive donor T-cells. IFN-γ added to in vitro cultures with MMB3.19, and LBRM, had no direct cell killing effect. Conclusion: CD11b− donor DC enhanced Th1 polarization of donor T-cells and GvL without increasing GvHD. Donor CD8+ T-cells mediated tumor killing effect. CD11b+ donor DC enhanced Th2 polarization of donor CD4+ T-cells and led to limited GvHD and GvL.

Flagellin, a TLR5 Agonist, Reduces GvHD in Allogeneic HSCT Recipients While Enhancing Anti-Viral Immunity: A Novel Therapeutic Approach

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 144-144
Author(s):  
Mohammad S Hossain ◽  
David L Jaye ◽  
Brian P Pollack ◽  
Alton B Farr ◽  
John Roback ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Cd8 T Cells ◽  
Viral Immunity ◽  
Hematopoietic Stem ◽  
Allogeneic Hsct ◽  
Post Transplant ◽  
Radiation Chimeras ◽  
Donor T Cells

Abstract Abstract 144 In MHC-mismatched allogeneic hematopoietic stem cell transplantation (allo-HSCT), host antigen specific donor T cells mediate acute and chronic graft-versus-host disease (GvHD). Based upon the radio-protective effects of flagellin, a TLR5 agonist protein (∼50 kDa) extracted from bacterial flagella, we reasoned that flagellin might modulate donor T cells immune responses toward host antigens, reduce GvHD, and improve immune responses to CMV infection in experimental models of allogeneic HSCT. Two 50mg/mouse i.p doses of highly purified flagellin were administered 3 hrs before irradiation and 24 hrs after allo-HSCT in H-2b ^ CB6F1 and H-2k ^ B6 models. GvHD scores were obtained with weekly clinical examination and with histological scoring of intestine, colon, liver and skin at necropsy. Flagellin treatment successfully protected allo-HSCT recipients from acute and chronic GvHDs after transplantation of 5×106 splenocytes and 5×106 T cell depleted (TCD) BM, and significantly increased survival compared to PBS-treated control recipients. Reduced acute GvHD was associated with significant reduction of a) early post-transplant proliferation of donor CD4+ and CD8+ T cells measured by Ki67 and CFSE staining, b) fewer CD62L+, CD69+, CD25+, ICOS-1+ and PD-1+ donor CD4+ and CD8+ T cells compared with the PBS-treated control recipients. Decreased numbers of activated and proliferating donor T cells were associated with significantly reduced pro-inflammatory serum IFN-g, TNF-a, and IL-6 on days 4–10 post transplant in flagellin-treated recipients compared with the PBS-treated recipients. Interestingly, both flagellin-treated recipients and PBS-treated recipients had over 99% donor T cell chimerism at 2 months post transplant. Moreover, MCMV infection on 100+ days post-transplant flagellin-treated mice significantly enhanced anti-viral immunity, including more donor MCMV-peptide-tetramer+ CD8+ T cells in the blood (p<0.05), and less MCMV in the liver on day 10 post infection (p<0.02) compared with the PBS-treated control recipients. Overall immune reconstitution after flagellin-treatment was robust and associated with larger numbers of CD4+CD25+foxp3+ regulatory T cells in the thymus. To further define the role of flagellin-TLR5 agonistic interactions in the reduction of GvHD, we next generated B6 ^ TLR5 KO (KO) and KOB^6 radiation chimeras by transplanting 10 × 106 BM cells from wild-type (WT) B6 or TLR5 KO donors into the congenic CD45.1+ B6 or KO recipients conditioned with 11Gy (5.5Gyx2) TBI. The radiation chimeras were irradiated again with 9.0Gy (4.5Gy × 2) on 60 days after the first transplant and transplanted with 3 × 106 splenocytes and 5 × 106 TCD BM from H-2K congenic donors. Two 50mg doses of flagellin were administered 3 hrs before irradiation and 24 hrs after HSCT. All flagellin-treated B6 ^ B6 radiation chimeras survived with only 12% weight-loss by 80 days post transplant compared with 50% survival among recipients of flagellin-treated B6 ^ KO and 40% survival among KO ^ B6 radiation chimeras. All flagellin-treated KO^ KO and PBS-treated radiation chimeras died within 65 days post transplant. These data suggested that interaction of flagellin with the TLR5 expressing host gut epithelium and donor hematopoietic cells are both required for the maximum protective effect of this TLR5 agonist on GvHD in allogeneic HSCT recipients. Together our data demonstrate that peritransplant administration of flagellin effectively controls acute and chronic GvHD while preserving enhanced post-transplant donor anti-opportunistic immunity. Since flagellin has been found to be safe for use in humans as vaccine adjuvant in a number of clinical trials, the clinical use of flagellin in the setting of allogeneic HSCT is of interest. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Single-cell multiomics reveals increased plasticity, resistant populations and stem-cell-like blasts in KMT2A-rearranged leukemia

Blood ◽  
2021 ◽  
Author(s):  
Changya Chen ◽  
Wenbao Yu ◽  
Fatemeh Alikarami ◽  
Qi Qiu ◽  
Chia-hui Chen ◽  
...  
Keyword(s):  
Single Cell ◽  
Young Patients ◽  
Cytotoxic Lymphocytes ◽  
Extrinsic Factors ◽  
Hematopoietic Stem ◽  
Younger Patients ◽  
Factors Affecting ◽  
Immune Mediated ◽  
Younger Age ◽  
Increased Risk

KMT2A-rearranged (KMT2A-r) infant ALL is a devastating malignancy with a dismal outcome, and younger age at diagnosis is associated with increased risk of relapse. To discover age-specific differences and critical drivers that mediate poor outcome in KMT2A-r ALL, we subjected KMT2A-r leukemias and normal hematopoietic cells from patients of different ages to single cell multi-omics analyses. We uncovered the following critical new insights: leukemia cells from patients younger than 6 months have significantly increased lineage plasticity. Steroid response pathways are downregulated in the most immature blasts from younger patients. We identify a hematopoietic stem and progenitor-like (HSPC-like) population in the blood of younger patients that contains leukemic blasts and form an immunosuppressive signaling circuit with cytotoxic lymphocytes. These observations offer a compelling explanation for the ability of leukemias in young patients to evade chemotherapy and immune mediated control. Our analysis also revealed pre-existing lymphomyeloid primed progenitors and myeloid blasts at initial diagnosis of B-ALL. Tracking of leukemic clones in two patients whose leukemia underwent a lineage switch documented the evolution of such clones into frank AML. These findings provide critical insights into KMT2A-r ALL and have clinical implications for molecularly targeted and immunotherapy approaches. Beyond infant ALL, our study demonstrates the power of single cell multi-omics to detect tumor intrinsic and extrinsic factors affecting rare but critical subpopulations within a malignant population that ultimately determines patient outcome.

Flagellin, a TLR5 Agonist, Down-Regulate CD62L on Donor T Cells and Limit GvHD in Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3521-3521
Author(s):  
Mohammad Hossain ◽  
Andrew T Gewirtz ◽  
John D Roback ◽  
Edmund K. Waller
Keyword(s):  
T Cells ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Immune Reconstitution ◽  
Major Complication ◽  
Hematopoietic Stem ◽  
Allogeneic Hsct ◽  
Post Transplant ◽  
Donor T Cells

Abstract Bacground: Graft-vs-host disease (GvHD) is a major complication in allogeneic Hematopoietic Stem Cell Transplant (HSCT) recipients. Flagellin is a bacterial protein and a TLR5 agonist that showed diverse immunological responses in both human and animal including both activation of dendritic cells and immuno-suppression. We recently observed that prophylactic use of flagellin protected allogeneic HSCT recipient from GvHD without affecting host immune reconstitution. Acute GvHD has been reported to be mediated by allo-reactive CD62L+ T cells, and over 80% of murine naïve splenic CD4+ and CD8+ T cells express CD62L. In order to test the effect of flagellin on GvHD mediated by the CD62L+ CD4+ and CD62L+CD8+ donor T cells, we investigated clinical manifestation of GvHD as well as the in vivo expression of CD62L on donor T cells in flagellin treated versus control treated allogeneic HSCT recipients. Methods: We established a parent →F1 MHC major mismatched model (C57BL/6 → C57BL/6 × BALB/c) for allogeneic HSCT for which GvHD is the major complication. Recipient mice received 5 × 10^6 T cell depleted (TCD) bone marrow cells and 5×10^6 or 10×10^6 CFSE labeled donor splenocytes from naïve C57Bl/6 congenic donors. 50 μg flagellin per recipient was administered intraperitoneally 3 hours before irradiation and 24 hours after allogeneic HSCT (treated). CB6F1 recipients that received no flagellin (untreated) and recipients of syngeneic HSCT were used as control. Recipients were sacrificed on day 66+ transplant and the numbers of CD62L+ T cells and foxp3+CD4+CD25+ T cells were determined by FACS. Recipients of CFSE treated donor splenocytes were sacrificed on day 4 post HSCT, splenocytes were harvested and analyzed for CD62L expression on T cell subsets undergone in vivo cell division by Flow cytometry. 5 mice were used per group. Results: Flagellin treated recipients did not have GvHD and had no mortality. Untreated control recipients had 87% survival at 30 days post transplant and had signs of chronic GvHD. While total cell number and also donor spleen- and BM-derived CD4+ and CD8+ T cells per spleen in untreated recipients were significantly lower compared to flagellin treated recipients (p=0.0006) on day 66 post transplant, persistent of donor spleen-derived CD62L+CD4+ T cells and CD62L+CD8+ T cells per spleen were not significantly different (p=0.13 and p=0.07, respectively). Moreover, higher number of foxp3+CD25+CD4+ regulatory T cells were found in the spleen and thymus in treated recipients compared to untreated recipients. Within day 4 post transplant, the number of CD4+ T cells per spleen of treated and untreated recipients increased significantly compared to syngeneic recipients (p=0.001 and p=0.03, respectively). Although equivalent numbers of CD62L+CD4+ T cells were observed in both treated and untreated recipients (p=0.3), significantly increased numbers of CD62L+CD8+ T cells was found in treated recipients compare to untreated recipients (p=0.02). Moreover, significantly higher numbers of divided (far left CFSE staining population) CD62L+CD4+ and CD62L+CD8+ T cells were found in recipients of treated splenocytes within day 4 post transplant followed by down regulation of CD62L surface marker compared to untreated recipients (p=0.02 and p=0.01, respectively). Conclusion: Flagellin treated recipients had limited GvHD and had rapid increased divided CD4+CD62L+ T cells followed by CD62L-ve activated CD4+ T cells per spleen in treated recipients compared to untreated recipients may be one of the major affect mediated by flagellin. Flagellin-TLR5 receptor agonistic effect may reduce production of biological factor(s) essential to generate allo-reactive T cells or directly stimulate CD62L+CD4+ and CD62L+CD8+ T cells in different activation status other than allo-reactive T cells; maintain a balanced immune reconstitution in lymphoid organs by producing regulatory T cells through their thymus. Therefore, use of flagellin may be a novel therapeutic approach to treat blood cancer patients with allogeneic HSCT without GvHD and toxicity.

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