scholarly journals Prevention of Chronic Gvhd By Targeting Xbp-1 Genetically or Pharmacologically in Mice

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4541-4541
Author(s):  
Steven D Schutt ◽  
Chih-Hang Anthony Tang ◽  
Yongxia Wu ◽  
David A Bastian ◽  
Juan Del Valle ◽  
...  
Keyword(s):  
T Cells ◽  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Chronic Gvhd ◽  
Critical Role ◽  
Conditional Knockout ◽  
Er Stress Response

Abstract Inhibition of the endoplasmic reticulum (ER) stress response via blockade of inositol-requiring enzyme-1α (IRE-1α) is currently a promising therapeutic strategy to treat B-cell leukemia, lymphoma, and myeloma. Because B cells play an important role in the development of chronic graft-versus-host disease (cGVHD), we hypothesize that the ER stress response contributes to B-cell function and pathogenicity in cGVHD. Here, we report that the ER stress response mediated by IRE-1α and its target X-box binding protein-1 (XBP-1) plays a critical role in cGVHD pathophysiology and represents a potential therapeutic target to prevent cGVHD. We tested the role of XBP-1 specifically in B cells by testing XBP-1 conditional knockout B cell grafts (XBP1fl/flCD19Cre+) in two mouse models of cGVHD. In the first model (B6 to BALB/c), recipients given XBP-1-deficient donor grafts showed significantly reduced cGVHD clinical scores, which were associated with reduced frequencies of donor-derived CD4 helper T cells within the lungs compared to the recipients of XBP-1fl/flCD19Cre- littermate donor grafts. XBP-1-deficient B cells produced significantly higher levels of IL-10 compared to WT control B cells after activation ex vivo. In the second model (B6 to B10.BR), the conversion of donor B cells to plasma cells (B220+CD38+CD138+) was reduced in both the spleens and lungs of recipients transplanted with XBP1fl/flCD19Cre+ grafts compared to those of the recipients given XBP1fl/flCD19Cre- grafts. Recipients given XBP1fl/flCD19Cre+ grafts also showed significantly higher total splenocytes and vastly increased splenic B-cell populations when compared with the recipients of XBP1fl/flCD19Cre- grafts. To expand on these findings, we tested if systemic XBP-1 blockade via a novel IRE-1α inhibitor, B-I09, would attenuate cGVHD. In a cutaneous model of cGVHD (B10.D2 to BALB/c), we found that prophylactic administration of B-I09 significantly reduced clinical features of cGVHD compared to vehicle controls (Fig. 1A). Validating these findings, hematoxylin and eosin stained skin sections of B-I09-treated mice had significantly lower pathology scores compared to vehicle controls (Fig. 1B). Isolated skin lymphocytes from recipients treated with B-I09 showed significant reductions in donor derived T cells and DCs compared to those treated with vehicle controls (Fig. 1C and D). Taken together, our findings reveal a novel role of the IRE-1α/XBP-1 pathway of the ER stress response in cGVHD pathophysiology and provide a readily translatable strategy to prevent the development of cGVHD in the clinic. Disclosures No relevant conflicts of interest to declare.

scholarly journals Ridd Is Required for the Prevention of Chronic Gvhd By Targeting IRE-1a/Xbp-1s Signaling

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1681-1681
Author(s):  
Hee-Jin Choi ◽  
Chih-Hang Anthony Tang ◽  
Linlu Tian ◽  
Yongxia Wu ◽  
Mohammed Hanief Sofi ◽  
...  
Keyword(s):  
T Cells ◽  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Critical Role ◽  
Secretory Cells ◽  
Hematopoietic Stem ◽  
Er Stress Response

Abstract Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an effective therapeutic procedure to treat hematological malignancies. However, the benefit of allo-HCT is limited by a major complication, chronic graft-versus-host disease (cGVHD). Since transmembrane and secretory proteins are generated and modified in the endoplasmic reticulum (ER), the ER stress response is of great importance to secretory cells including B cells. By using conditional knock-out (KO) of XBP-1, IRE-1α or both specifically on B cells, we demonstrated that the IRE-1α/XBP-1s pathway, one of the major ER stress response mediators, plays a critical role in B cell pathogenicity on the induction of cGVHD in murine models of allo-HCT. Endoribonuclease activity of IRE-1α not only activates XBP-1s transcription factor by converting unspliced XBP-1 (XBP-1u) mRNA into spliced XBP-1 (XBP-1s) mRNA but also cleaves other ER-associated mRNAs through regulated IRE-1α-dependent decay (RIDD). Besides, it is known that ablation of XBP-1s production leads to unleashed activation of RIDD. Therefore, we hypothesized that RIDD plays an important role in B cells during cGVHD development. In this study, we found that B cells deficient for XBP-1s reduced ability to induce cGVHD, which however was reversed by inactivation of IRE-1α, highlighting the role of RIDD in controlling cGVHD (Fig. A). Activation of RIDD targets IgM mRNA of (Fig. B), a contributor to organ damage and fibrosis in cGVHD, which correlated with dysregulated expression of MHC II and costimulatory molecules such as CD86, CD40, and ICOSL in B cells (Fig. C). Alloreactive T cells need to be primed by APCs to initiate GVHD, and specifically, CD86 and CD40 mediated-costimulation from APCs has been demonstrated to play an essential role in eliciting cGVHD. We demonstrated that alloreactivity of T cells, especially CD4 T cells, can be recovered by suppressing RIDD in XBP-1s-deficient B cells (Fig. D). Since IRE-1α carrying a S729A mutation shows ablated RIDD activity without effect on splicing XBP-1 mRNA, we investigated the contribution of B cells from S729A knock-in mice to confirm the role of RIDD in B cells. We found that B cells from S729A mice increased GVHD severity (Fig. E). S729A B cells showed significant increases in IgM secretion (Fig. F), GC cell differentiation (Fig. G), and the expression levels of MHCII and co-stimulatory factors (Fig. H). In conclusion, these results provide a novel insight on how ER stress response regulates B cell activity after allo-HCT and suggest RIDD is an important mediator for reducing cGVHD pathogenesis. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals XBP-1s Promotes B Cell Pathogenicity in Chronic GVHD by Restraining the Activity of Regulated IRE-1α-Dependent Decay

2021 ◽  
Vol 12 ◽  
Author(s):  
Hee-Jin Choi ◽  
Chih-Hang Anthony Tang ◽  
Linlu Tian ◽  
Yongxia Wu ◽  
M. Hanief Sofi ◽  
...  
Keyword(s):  
Stress Response ◽  
B Cells ◽  
Er Stress ◽  
B Cell ◽  
Hematopoietic Cell Transplantation ◽  
Chronic Gvhd ◽  
Critical Role ◽  
Secretory Cells ◽  
Secretory Proteins ◽  
Er Stress Response

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective therapeutic procedure to treat hematological malignancies. However, the benefit of allo-HCT is limited by a major complication, chronic graft-versus-host disease (cGVHD). Since transmembrane and secretory proteins are generated and modified in the endoplasmic reticulum (ER), the ER stress response is of great importance to secretory cells including B cells. By using conditional knock-out (KO) of XBP-1, IRE-1α or both specifically on B cells, we demonstrated that the IRE-1α/XBP-1 pathway, one of the major ER stress response mediators, plays a critical role in B cell pathogenicity on the induction of cGVHD in murine models of allo-HCT. Endoribonuclease activity of IRE-1α activates XBP-1 signaling by converting unspliced XBP-1 (XBP-1u) mRNA into spliced XBP-1 (XBP-1s) mRNA but also cleaves other ER-associated mRNAs through regulated IRE-1α-dependent decay (RIDD). Further, ablation of XBP-1s production leads to unleashed activation of RIDD. Therefore, we hypothesized that RIDD plays an important role in B cells during cGVHD development. In this study, we found that the reduced pathogenicity of XBP-1 deficient B cells in cGVHD was reversed by RIDD restriction in IRE-1α kinase domain KO mice. Restraining RIDD activity per se in B cells resulted in an increased severity of cGVHD. Besides, inhibition of RIDD activity compromised B cell differentiation and led to dysregulated expression of MHC II and costimulatory molecules such as CD86, CD40, and ICOSL in B cells. Furthermore, restraining the RIDD activity without affecting XBP-1 splicing increased B cell ability to induce cGVHD after allo-HCT. These results suggest that RIDD is an important mediator for reducing cGVHD pathogenesis through targeting XBP-1s.

Role of B Cells in Graft-Versus-Leukemia and Graft-Versus-Host Disease

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. SCI-3-SCI-3
Author(s):  
Jerome Ritz
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Chronic Gvhd ◽  
Histocompatibility Antigens ◽  
Minor Histocompatibility Antigens ◽  
Graft Versus Host ◽  
Graft Versus Leukemia ◽  
Donor T Cells

Abstract The clinical outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) have steadily improved in the last two decades, but this remains a potentially toxic treatment approach and further improvements are needed. Both the benefits and potential toxicities of allogeneic HSCT derive from the replacement of the recipient’s immune system with donor cells. Donor T cells clearly play a critical role as the primary mediators of both graft-versus-leukemia (GVL) and graft-versus-host-disease (GVHD) after transplant. In this setting, donor T cells targeting tumor-specific antigens provide specific GVL activity and donor T cells targeting broadly expressed minor histocompatibility antigens (allo-antigens) lead to GVHD. Donor T cells targeting minor histocompatibility antigens with restricted expression on both normal and malignant hematopoietic cells in the recipient contribute to GVL as well as to the elimination of recipient hematopoietic cells and the establishment of full donor hematopoiesis. Although donor B cells do not contribute to acute GVHD, considerable evidence now suggests that donor B cells also play an important role in chronic GVHD (cGVHD). In male patients with female donors, Y chromosome encoded (HY) proteins represent a clinically relevant set of widely expressed minor histocompatibility antigens (mHA) that are frequently recognized by both donor T cells and B cells. HY antibodies typically develop four to eight months after HSCT and the development of HY antibodies is significantly associated with the development of cGVHD. Antibodies to autosomal mHA and tumor-associated antigens have also been detected. Development of antibodies to mHA has also been associated with a lower risk of relapse suggesting a role for donor B cells in GVL. Murine models have clearly demonstrated that donor B cell reconstitution after allogeneic HSCT contributes to the development of cGVHD. In one of these models, depletion of germinal center B cells prevents the development of bronchiolitis obliterans and other pathologic features of cGVHD. The homeostatic cytokine B-cell activating factor (BAFF) plays an important role in the regulation of donor B cell reconstitution. BAFF promotes B-cell proliferation, differentiation, and survival; but persistent, high levels of BAFF also support the survival of auto and allo-reactive B cells. Patients with cGVHD typically have delayed B-cell reconstitution and low numbers of circulating B cells associated with high levels of BAFF. A high BAFF to B-cell ratio promotes survival of antigen-activated B cells and prevents or delays the development of B-cell tolerance after transplant. The important role of B cells in cGVHD has been confirmed by numerous clinical reports demonstrating the efficacy of B-cell directed therapy with rituximab in patients with established cGVHD. Overall response rates of 40 to 70 percent have been reported, and clinical responses have been associated with reduced titers of allo-reactive antibodies and restoration of normal B-cell homeostasis, with increased numbers of circulating B cells and lower levels of BAFF after recovery from treatment. The efficacy of rituximab in the treatment of established cGVHD has led to recent studies evaluating rituximab as a prophylactic therapy for cGVHD. The results of single institution trials suggest that this may be an effective approach and further randomized multi-center trials evaluating the role of rituximab for cGVHD prophylaxis are currently in development. The efficacy of rituximab has also led to the evaluation of other B cell directed therapies in murine models. In particular, selective inhibitors of B cell signaling pathways have been developed and appear to be effective in preventing cGVHD in these model systems. Further evaluation of these new agents in the treatment and prevention of cGVHD is in development. Disclosures: Off Label Use: Rituximab - Use in treatment of chronic GVHD..

scholarly journals Hyaluronate-CD44 Interactions Can Induce Murine B-Cell Activation

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2901-2908 ◽  
Author(s):  
Asimah Rafi ◽  
Mitzi Nagarkatti ◽  
Prakash S. Nagarkatti
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Critical Role ◽  
Surface Glycoprotein ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Cell Surface Glycoprotein ◽  
Immunodeficient Mice

Abstract CD44 is a widely distributed cell surface glycoprotein whose principal ligand has been identified as hyaluronic acid (HA), a major component of the extracellular matrix (ECM). Recent studies have demonstrated that activation through CD44 leads to induction of effector function in T cells and macrophages. In the current study, we investigated whether HA or monoclonal antibodies (MoAbs) against CD44 would induce a proliferative response in mouse lymphocytes. Spleen cells from normal and nude, but not severe combined immunodeficient mice, exhibited strong proliferative responsiveness to stimulation with soluble HA or anti-CD44 MoAbs. Furthermore, purified B cells, but not T cells, were found to respond to HA. HA was unable to stimulate T cells even in the presence of antigen presenting cells (APC) and was unable to act as a costimulus in the presence of mitogenic or submitogenic concentrations of anti-CD3 MoAbs. In contrast, stimulation of B cells with HA in vitro, led to B-cell differentiation as measured by production of IgM antibodies in addition to increased expression of CD44 and decreased levels of CD45R. The fact that the B cells were responding directly to HA through its binding to CD44 and not to any contaminants or endotoxins was demonstrated by the fact that F(ab)2 fragments of anti-CD44 MoAbs or soluble CD44 fusion proteins could significantly inhibit the HA-induced proliferation of B cells. Also, HA-induced proliferation of B cells was not affected by the addition of polymixin B, and B cells from lipopolysaccharide (LPS)-unresponsive C3H/HeJ strain responded strongly to stimulation with HA. Furthermore, HA, but not chondroitin-sulfate, another major component of the ECM, induced B-cell activation. It was also noted that injection of HA intraperitoneally, triggered splenic B cell proliferation in vivo. Together, the current study demonstrates that interaction between HA and CD44 can regulate murine B-cell effector functions and that such interactions may play a critical role during normal or autoimmune responsiveness of B cells.

scholarly journals The allogeneic bisection of carrier-specific enhancement of monoclonal B-cell responses.

1975 ◽  
Vol 142 (5) ◽  
pp. 1165-1179 ◽  
Author(s):  
S K Pierce ◽  
N R Klinman
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Immunoglobulin Class ◽  
Cell Responses ◽  
Cell Clones ◽  
Ia Antigens ◽  
Collaborative Interactions ◽  
B Cell Responses

The ability of T cells to enhance the response of syngeneic and allogeneic B cells to thymus-dependent hapten-carrier conjugates was analyzed. This analysis was carried out on individual primary B cells in splenic fragment cultures derived from irradiated reconstituted mice. This system has several advantages: (a) the response of the B cells is entirely dependent on carrier priming of the irradiated recipient; (b) this B-cell response can be quantitated in terms of the number of responding cells; and (c) very small B-cell responses can be readily detected and analyzed. The results indicate that the majority of hapten-specific B cells were stimulated in allogeneic and syngeneic recipients only if these recipients were previously carrier primed. The number of B cells responding in carrier-primed allogeneic recipients was 60-70% of that in syngeneic carrier-primed recipients. The antibody-forming cell clones resulting from B cells stimulated in the allogeneic environment produced small amounts of antibody and antibody solely of the IgM immunoglobulin class, while the larger responses in syngeneic recipients were predominantly IgG1 or IgM plus IgG1. The capacity of collaborative interactions between carrier-primed T cells and primary B cells to yield IgG1 antibody-producing clones was shown to be dependent on syngeny between these cells in the H-2 gene complex. It is concluded that: (a) B cells can be triggered by T-dependent antigens to clone formation through collaboration with T cells which differ at the H-2 complex as long as these T cells recognize the antigen; (b) the immunoglobulin class produced by the progeny of stimulated B cells generally depends on the nature of the stimulatory event rather than the nature of the B cell itself; and (c) stimulation to IgG1 production is dependent on syngeny between the collaborating T and B cells probably within the Ir-1A region. The role of the Ia antigens in the formation of IgG1-producing clones is not yet clear; Ia identity could permit IgG1 production or, conversely, nonidentity of Ia could induce all allogeneic interactions which prohibit IgG1 production.

RhoF GTPase Transcription Is Upregulated in Germinal Center B-Cells, Shows Altered Expression in Malignant B-Cells, and Interacts with the ATM Pathway.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 285-285
Author(s):  
Launce G. Gouw ◽  
N. Scott Reading ◽  
David K. Crockett ◽  
Philippe Szankasi ◽  
Megan S. Lim ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
De Novo ◽  
Cell Lymphoma ◽  
Lymphocyte Subpopulations ◽  
Interacting Proteins ◽  
Tissue Samples

Abstract Follicular lymphoma (FL) is the most common low-grade B-cell non Hodgkin lymphoma in the Western hemisphere. A significant proportion of FL undergo histologic transformation to diffuse large B-cell lymphoma (DLBCL). Using cDNA microarray analysis, we identified an expressed sequence tag GI#10952525 consistently differentially expressed in transformed follicular lymphomas (tFL). This was characterized as RhoF, a novel member of the Rho family. Rho GTPases play central roles in cytoskeletal dynamics, cell-cell interactions, and intracellular signaling pathways involved in migration, proliferation and survival. Dysregulation of Rho proteins are key events implicated in tumorigenesis. To define the role of RhoF in lymphocyte physiology and lymphoma transformation, we assessed its expression across phenotypically defined lymphocyte subpopulations, using quantitative real-time PCR. We determined relative RhoF levels in immunomagnetic bead purified normal lymphoid subpopulations [naïve B-cells, memory B-cells, germinal center B-cells and T-cells], reactive lymphoid tissues (n=5), cell lines [derived from t(14;18) tFL (n =3), de novo DLBCL (n=7), and T-cell malignancy (n=3)] and tissue from primary human lymphoid neoplasms [FL (n=5), de novo DLBCL (n=5), tFL (n=5), CLL/SLL (n=4), anaplastic large cell lymphoma (n=8), mantle cell lymphoma (n=5), and T-cell acute lymphoblastic leukemia (n=5)]. RhoF was expressed at significantly higher levels in B-cells relative to T-cells. We saw this pattern in purified lymphocyte subpopulations, in cell lines, and in primary lymphoma tissue samples. Notably, we detected elevated levels of RhoF transcript in B-cells of germinal center (GC) origin, both in the reactive and neoplastic samples of GC-derived B-cells. The highest transcriptional levels of RhoF were in malignant B-cells of GC origin; both in heterogeneous primary tissue samples and in homogeneous tissue culture preparations. To investigate its functional role, we cloned RhoF into a vector coding for a C-terminal polyhistidine- and V5 epitope-tag. We expressed the constructs in HEK 293T cells, and purified the RhoF-containing complexes using a tandem affinity purification approach. We ran cell lysates through a nickel column; non-interacting proteins were washed off under native conditions and the bound RhoF complexes eluted with imidazole. Eluate was immunoprecipitated with sepharose-bound anti-V5 antibody. Immunoprecipitated complexes were denatured and resolved by 1D-PAGE. Unique bands representing RhoF interacting proteins were isolated and enzymatically cleaved with trypsin. Resultant peptides underwent liquid chromatography and tandem mass spectrometry. Data were searched against the NCBI nr.FASTA nonredundant protein database using the SEQUEST algorithm and false positive rates determined with INTERACT and ProteinProphet. Among several putative RhoF interactors, we identified ATM as an important RhoF binding partner. In conclusion, our demonstration of the differential expression of RhoF in GC-derived cells and its upregulation in tFL provide evidence for a connection between the role of this novel protein in B-cell development and malignancy. In addition, evidence of an association between RhoF and ATM may provide a link between DNA repair, cell cycle control and morphological dynamics.

Targeting Proteinkinase C Alters ER-Stress and b-Catenin Signaling in Multiple Myeloma: Therapeutic Implications.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 258-258
Author(s):  
Marc S. Raab ◽  
Klaus Podar ◽  
Jing Zhang ◽  
Giovanni Tonon ◽  
Johannes H. Fruehauf ◽  
...  
Keyword(s):  
Cell Death ◽  
Stress Response ◽  
Growth Inhibition ◽  
Er Stress ◽  
Cell Lines ◽  
Wnt Pathway ◽  
Dependent Manner ◽  
P53 Family ◽  
Er Stress Response

Abstract We have previously shown that the novel orally available small molecule inhibitor of PKC enzastaurin (Eli Lilly and Company) inhibits MM cell growth, survival and angiogenesis both in vitro and in vivo. To date, however, the downstream effects contributing to growth inhibition and cell death remain to be determined. Here, we performed global gene expression profiling on enzastaurin treated MM cells and identified 200 Genes to be differentially regulated with a > 2-fold cut off. Strikingly, two major groups of up-regulated probe sets were associated with either of two pathways - endoplasmatic reticulum (ER)-stress response or WNT-signaling. Importantly, MM cells, producing high levels of paraprotein, are highly susceptible to perturbation of ER function and protein folding. Moreover, PKC isoforms have been reported to directly regulate the canonical WNT pathway via phosphorylation of b-catenin (CAT), leading to its ubiquination and proteasomal degradation. Specifically, we fist evaluated the role of enzastaurin in mediating ER-stress in MM cells. The transcriptional up-regulation of genes involved in ER-stress (GADD153/CHOP, GADD34, ATF3), triggered by enzastaurin at 3h, was confirmed by western blot analysis, accompanied by induction of the molecular ER chaperone BiP/grp78, phosphorylation of eIF2a consistent with PERK activation, and up-regulation of p21. These events were preceded by an early (1h) increase of intracellular calcium levels, a hallmark of ER-stress, assessed by FLUO4 staining. These data suggest an important role of ER-stress response in the early growth inhibition of MM cells caused by enzastaurin. Second, we delineated effects of enzastaurin on WNT pathway in MM and other tumor cell lines. Upon enzastaurin treatment, CAT was dephosphorylated at Ser33, 37, 41 in a dose- and time-dependent manner in all cell lines tested (10 MM, 3 colon cancer, HeLa, as well as human embryonic kidney 293 cells). Consequently, accumulation of CAT occurred in both cytosolic and nuclear fractions of treated MM cells, associated with activated TOPflash LUC-reporter system, confirming nuclear transactivating activity. Specific inhibition of CAT by siRNA partially rescued HeLa, HEK 293, and MM cells from cell death induced by enzastaurin. Analysis of downstream target molecules revealed a CAT-dependent up-regulation of c-Jun, but not of c-Myc or Cyclin D1. c-Jun has been reported to stabilize p73, a pro-apoptotic p53-family member; CAT induction by enzastaurin led to p73 (but not p53) activation and was also abrogated by CAT-specific siRNA. In turn, specific knockdown of p73 by siRNA rescued cells from enzastaurin-induced apoptosis. Finally, ectopic overexpression of CAT in HeLa and MM cells induced c-Jun expression and p73 activation, followed by apoptotic cell death. Our studies therefore indicate that ER-stress response contributes to the immediate inhibition of proliferation by enzastaurin, followed by CAT accumulation leading to p73 activation, contributing to enzastaurin-mediated cell death. These findings provide a novel link between CAT and p53-family members. Moreover p73, which is only rarely mutated in human cancers, represents a novel therapeutic target in MM.

scholarly journals Posttransplant Cyclophosphamide Promote Naïve-Subset Dominant B Cell Recovery Coordinated with Early Treg Expansion; Implication of Reduced Risk of Pathogenesis into Chronic Gvhd

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4566-4566
Author(s):  
Miki Iwamoto ◽  
Yusuke Meguri ◽  
Takumi Kondo ◽  
Hiroyuki Sugiura ◽  
Shuntaro Ikegawa ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Population ◽  
Cd8 T Cells ◽  
Peripheral Blood ◽  
Chronic Gvhd ◽  
Lymphocyte Subset ◽  
Cell Recovery ◽  
Haplo Group

Abstract Posttransplant cyclophosphamide (PTCy) is an effective prophylaxis for both acute and chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). We recently studied the immune reconstitution dynamics of each lymphocyte subset after PTCy-based transplant using murine haploidentical BMT model and reported that PTCy strongly promoted Treg-dominant T-cell reconstitution and stem cell-derived mature B-cell generation with broad BCR-diversity. We also found that the early reconstitution of Treg could contribute to promote naïve B cell emergence from bone marrow, indicating the T and B cell recovery might be mutually coordinated after PTCy-based transplant (Iwamoto et al, ASH2017). However, the detailed process of immune reconstitution in patients after haploidentical HSCT with PTCy has not been well studied. To address this issue, we here investigated the early dynamics of donor-lymphocyte subset chimerisms in patient after clinical PTCy-based haploidentical HSCT with comparing those in patients after low-dose ATG-based haploidentical HSCT and patients after cord blood transplantation. Laboratory studies were undertaken in 13 adult patients who received HLA-mismatched allogeneic graft; unrelated cord blood (n=5), and haploidentical related peripheral blood after ATG-based conditioning (n=5) and haploidentical related peripheral blood after PTCy-based conditioning (n=5). Blood samples were obtained before and at 1, 2, 4, 6 and 8 weeks after HSCT. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples by density gradient centrifugation and cryopreserved before being analyzed. After thawing, to analyze the subset-specific chimerism, PBMCs were stained with anti-HLA monoclonal antibodies and other subset-specific antibodies as follows: Pacific Blue conjugated anti-CD4, eFluor450 conjugated anti-CD3, PE-Cy7 conjugated anti-CD25, anti-CD14, APC conjugated anti-CD127, anti-CD56, and APC-eFluor780 conjugated anti-CD8a, anti-CD19. Gated lymphotes (CD4+Tcons, CD4+Tregs, CD8+T cells, B cells, NK cells, Monocytes) were analyzed their chimerism by flowcytometry. To examine the detailed phenotype of B cells, the expression of CD27, CD24, CD38 and IgD were tested. Flowcytometry-based method enables us to analyze the lymphocyte subset chemerism in the very early phase after HSCT. At 2 weeks after HSCT, our analysis revealed that CD4+Tcons, CD4+Tregs and CD8+T cells had already achieved complete donor chimerisms (>95% in all subsets) in patients after ATG-based SCT and had been approaching complete donor chimerisms (85.8%, 75.4% and 87.2%, respectively) in patients after CBT. In contrast, percentage of donor chimerisms of CD4+Tcons, CD4+Tregs and CD8+T cells after PTCy-based haplo-SCT was 73.5%, 59.6% and 59.2%, respectively, and those remained to be in the lower levels than other 2 groups. However, at 4 weeks after HSCT, all examined patients achieved complete donor chimerism of T cells, NK cells and Monocytes (>90%). At 8 weeks after HSCT, the number of B cells in PTCy-based haplo-group was higher than in ATG-based haplo-group (3494 vs 1901/mm3). Of note, B cell population in PTCy-based haplo-group at 8 weeks contained the significantly higher percentage of CD24+CD27-IgD+CD38+ transitional/naïve subset and the significantly lower percentage of CD24+CD27+IgD-CD38neg/dim activated/switched-memory subset when compared to B cell population in ATG-based haplo-group (59.9% vs 10.2%, 2.6% vs 21.5%, P<0.02 respectively), suggesting PTCy treatment might be associated with the favorable B cell reconstitution with naïve-subset dominant composition. Moreover, in patients after PTCy-based haplo-group, the percentage of activated/switched-memory subsets in B cell population at 8 weeks was inversely correlated with percentage of Treg in CD4 T cells at 4 weeks (P<0.05, r2=0.77). Taken together, consistently with our murine study, the current data from clinical samples again suggest that PTCy-based immune-modulation lead to coordinated T and B cell recovery, especially promoting naïve-subset dominant B cell recovery with help of the early expansion of Treg, which might reduce the risk of subsequent chronic GVHD. These data provide the important information for understanding the immunological reconstitution after PTCy-based haploidentical HSCT. Disclosures No relevant conflicts of interest to declare.

scholarly journals Chronic GvHD Is Characterized By Impaired B Cell Development in the Bone Marrow

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1883-1883
Author(s):  
Oleg Kolupaev ◽  
Michelle West ◽  
Bruce R. Blazar ◽  
Stephen Tilley ◽  
James Coghill ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cd4 T Cells ◽  
Critical Role ◽  
Cell Development ◽  
B Cell Development ◽  
B Lymphopoiesis

Abstract Background. Chronic-graft-versus-host disease (cGvHD) continues to be a major complication following allogeneic hematopoietic stem cell transplantation (HSCT). Despite significant progress, mechanisms underlying development of the pathology are yet to be fully understood. Recent studies utilizing mouse models and patient samples have demonstrated a critical role for B cells in GvHD pathogenesis. Bone marrow (BM)-derived B cells can produce auto-reactive antibodies causing tissue fibrosis and multiorgan cGvHD. Impaired B cell homeostasis in the periphery, activation due to abnormally high levels of B cell-activating factor (BAFF), increased survival of auto-reactive B cells and aberrant BCR signaling are shown to be important for disease progression in cGvHD patients. Murine models also highlighted the critical role of germinal center reactions, particularly interactions between T follicular helper (Tfh) cells and B cells for generation of auto-antibodies which are responsible for triggering immune responses and cell-mediated toxicity. A growing body of evidence has emerged highlighting the fact that BM itself is a target organ during acute GvHD (aGvHD) with recent work suggesting a role for donor CD4+ T cells in BM specific aGvHD. Our group has shown that patients with higher numbers of BM B cell precursors were less likely to develop cGvHD after allogeneic HSCT (Fedoriw et al., 2012). These observations indicate clinical relevance of impaired BM B lymphopoiesis for cGvHD development. Methods. In order to investigate the effect of cGvHD on BM B cell development, we used the well-characterized major mismatch B6 into B10.BR model of systemic cGvHD. Recipient mice were treated with cyclophosphamide on day -3 and -2, irradiated with 700 cGy on day -1, and injected with 107 T cell depleted (TCD) BM with or without total splenic T cells (0.5-1x105). Mice were monitored for 30 days, and BM and spleen was harvested and analyzed using flow cytometry. Results. Consistent with patient data, we observed a decrease in the frequency and number of donor-derived uncommitted common lymphoid progenitors (CLP) and B cell progenitors in the BM+ allogeneic T cells group (CLP: 0.17±0.03% vs. 0.06±0.01%, p <0.01; pro B: 2.2 ± 0.5% vs. 0.7 ± 0.3%, p<0.05; pre B: 15.3±1.8% vs. 6.3±2.4%, p<0.05; immature B cells: 5.7±0.7% vs. 2.1±0.7%, p<0.01) (Fig.1). As previously reported for this model, we also found a decrease in the frequency of follicular (FO) B cells (Flynn et al., 2014). We hypothesized that during cGvHD the B cell progenitor BM niche is affected by donor CD4+ T cells leading to impaired B lymphopoiesis. Bone marrow from BM+T cell animals had a significantly higher frequency of CD4+ cells compared to the control group (0.45±0.06% vs. 0.2±0.02%). Depletion of CD4+ T cells using anti-CD4 antibody during the first two weeks after transplant improved pathology scores and prevented weight loss in BM+T cells mice. We also observedpartial recovery of B cell progenitors and Lin-CD45-CD31-CD51+ osteoblasts (OB) in animals treated with anti-CD4 antibodies (pre B 3.5±1.1% vs. 20.4±4.5%, p<0.05; immature B: 1.9±0.9% vs. 3.5±0.3%; OB: 0.8±0.1% vs.1.2±0.2%). A recent study showed that activation and proliferation of conventional T cells in aGvHD model can be prevented by in vivo expansion of regulatory T cells (Tregs) using αDR3 antibody (4C12). We adopted this approach to determine whether Tregs can suppress the cytotoxic effect of donor CD4+ T cells in BM in cGvHD model. Animals that received T cells from 4C12-treated donors had an increase in survival and lower cGvHD pathology scores. These mice also had higher frequency of pro B, pre B, and immature B cells compared to the mice infused with T cells from isotype-treated donors. Conclusions. These studies demonstrate that BM development of B lymphocytes is impaired in a mouse model of systemic cGvHD. Our data suggests that donor-derived CD4+ T cells are involved in the destruction of hematopoietic niches in BM, particularly OB, which support B lymphopoiesis. Moreover, depletion of CD4+ T cells and infusion with in vivo expanded Tregs reduced the severity of cGvHD. Thus, Treg therapy in patients with cGvHD may be important for BM B cell development, and improvement of clinical outcomes. Disclosures No relevant conflicts of interest to declare.

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