Alloreactive effector T cells require the local formation of a proinflammatory environment to allow crosstalk and high avidity interaction with nonhematopoietic tissues to induce GVHD reactivity

Feasibility, safety, and efficacy of early prophylactic donor lymphocyte infusion after T cell-depleted allogeneic stem cell transplantation in acute leukemia patients

Prophylactic donor lymphocyte infusion (DLI) starting at 6 months after T cell-depleted allogeneic stem cell transplantation (TCD-alloSCT) can introduce a graft-versus-leukemia (GvL) effects with low risk of severe graft-versus-host-disease (GvHD). We established a policy to apply low-dose early DLI at 3 months after alloSCT to prevent early relapse. This study analyzes this strategy retrospectively. Of 220 consecutive acute leukemia patients undergoing TCD-alloSCT, 83 were prospectively classified to have a high relapse risk and 43 were scheduled for early DLI. 95% of these patients received freshly harvested DLI within 2 weeks of the planned date. In patients transplanted with reduced intensity conditioning and an unrelated donor, we found an increased cumulative incidence of GvHD between 3 and 6 months after TCD-alloSCT for patients receiving DLI at 3 months compared to patients who did not receive this DLI (0.42 (95%Confidence Interval (95% CI): 0.14-0.70) vs 0). Treatment success was defined as being alive without relapse or need for systemic immunosuppressive GvHD treatment. The five-year treatment success in patients with acute lymphatic leukemia was comparable between high- and non-high-risk disease (0.55 (95% CI: 0.42-0.74) and 0.59 (95% CI: 0.42-0.84)). It remained lower in high-risk acute myeloid leukemia (AML) (0.29 (95% CI: 0.18-0.46)) than in non-high-risk AML (0.47 (95% CI: 0.42-0.84)) due to an increased relapse rate despite early DLI.

Inhibition of interleukin-1 receptor-associated kinase 1 decreases murine acute GVHD while preserving graft-versus-lymphoma effect

BACKGROUND

Activation of antigen presenting cells (APC) is crucial in initiating inflammation and alloreaction during acute graft-versus-host disease (aGVHD), a common life-threatening complication of allogeneic hematopoietic cell transplantation. Interleukin-1 receptor-associated kinase 1 (IRAK1) regulates activation of APC in inflammatory settings. Inhibition of IRAK1 might decrease APC activation and aGVHD.

OBJECTIVE

To explore the impact of IRAK1 inhibition on APC activation and aGVHD in mice.

STUDY DESIGN

We administrated a selective IRAK1 inhibitor Jh-X-119-01 to recipient mice receiving allotransplants or co-challenged by A20 lymphoma cells. We assessed aGVHD and graft-versus-lymphoma (GVL) effect. Activations of T-cell and APC were also analyzed.

RESULTS

Jh-X-119-01 increased survival and decreased aGVHD of recipients. Jh-X-119-01 decreased proportions of Th1 cells and Tc1 cells in the aGVHD model and in the in vitro mixed lymphocyte reaction (MLR). The IRAK1 inhibitor reduced productions of TNFα and IFNγ in macrophages of recipient mice. In the in vitro cultured bone marrow dendric cells (BMDCs), Jh-X-119-01 decreased productions of inflammatory cytokines, reduced expressions of CD80 and CD86, and decreased protein levels of anti-apoptotic Bcl2 and phosphorylated NF-κB p65. RNA-seq analysis showed Jh-X-119-01 had an impact on several pathophysiological processes of BMDCs such as reduction of GVHD-relation genes and regulation of helper T cell differentiation. Importantly, IRAK1 inhibition did not impair cytotoxic function of T-cell or the allotransplant-related GVL effect against A20 lymphoma cells. In addition, the IRAK1 inhibitor did not retard recovery of hematopoietic cells in blood or bone marrow.

CONCLUSION

We show selective IRAK1 inhibition ameliorates murine aGVHD but preserves GVL effect. Our findings may have implication for using an IRAK1 inhibitor in allotransplant.

Magnitude of Off-Target Allo-HLA Reactivity by Third-Party Donor-Derived Virus-Specific T Cells Is Dictated by HLA-Restriction

T-cell products derived from third-party donors are clinically applied, but harbor the risk of off-target toxicity via induction of allo-HLA cross-reactivity directed against mismatched alleles. We used third-party donor-derived virus-specific T cells as model to investigate whether virus-specificity, HLA restriction and/or HLA background can predict the risk of allo-HLA cross-reactivity. Virus-specific CD8^pos T cells were isolated from HLA-A^*01:01/B^*08:01 or HLA-A^*02:01/B^*07:02 positive donors. Allo-HLA cross-reactivity was tested using an EBV-LCL panel covering 116 allogeneic HLA molecules and confirmed using K562 cells retrovirally transduced with single HLA-class-I alleles of interest. HLA-B^*08:01-restricted T cells showed the highest frequency and diversity of allo-HLA cross-reactivity, regardless of virus-specificity, which was skewed toward multiple recurrent allogeneic HLA-B molecules. Thymic selection for other HLA-B alleles significantly influenced the level of allo-HLA cross-reactivity mediated by HLA-B^*08:01-restricted T cells. These results suggest that the degree and specificity of allo-HLA cross-reactivity by T cells follow rules. The risk of off-target toxicity after infusion of incompletely matched third-party donor-derived virus-specific T cells may be reduced by selection of T cells with a specific HLA restriction and background.

Skewed Dendritic Cell Differentiation of MyD88-Deficient Donor Bone Marrow Cells, Instead of Massive Expansion as Myeloid-Derived Suppressor Cells, Aggravates GVHD

Graft-versus-host disease (GVHD), a life-threatening complication after bone marrow transplantation (BMT), is induced by activation of alloreactive donor T cells. Our previous study demonstrated that transplantation of myeloid differentiation factor 88 (MyD88)-deficient knockout (KO) bone marrow (BM) resulted in aggravation of GVHD. Here, to understand the cellular mechanism, we performed longitudinal in vivo imaging and flow cytometric analyses followed by transcriptome and functional examination of donor MyD88-KO BM progenies in GVHD hosts, using a major histocompatibility complex-matched but minor histocompatibility antigen-mismatched C57BL/6→BALB.B model. In GVHD hosts with MyD88-KO BMT, donor BM-derived CD11b⁺Gr-1⁺ cells were found to undergo cell death, a fate significantly different from the explosive expansion shown by the wild type (WT) counterparts, and also from the moderate expansion of the WT or MyD88-KO BM-derived cells in non-GVHD hosts. It was also revealed that MyD88-KO CD11b⁺Gr-1⁺ cells preferred differentiation into CD11c⁺ dendritic cells (DCs) to expansion as myeloid-derived suppressor cells in GVHD hosts or in high inflammatory in vitro conditions. These CD11c⁺ DCs comprised the majority of MyD88-KO CD11b⁺Gr-1⁺ apoptotic cells in GVHD hosts. Their ability to cross-present alloantigens of host origin contributed to the enhancement of T cell alloreactivity, causing GVHD aggravation and eventually death through the killing function of activated T cells. These results provide insights into the roles of MyD88 in myelopoiesis of donor BM and the protective effects in GVHD hosts, helpful information for development of a strategy to control GVHD.

Tissue Damage Caused by Myeloablative, but Not Non-Myeloablative, Conditioning before Allogeneic Stem Cell Transplantation Results in Dermal Macrophage Recruitment without Active T-Cell Interaction

Introduction

Conditioning regimens preceding allogeneic stem cell transplantation (alloSCT) can cause tissue damage and acceleration of the development of graft-versus-host disease (GVHD). T-cell-depleted alloSCT with postponed donor lymphocyte infusion (DLI) may reduce GVHD, because tissue injury can be restored at the time of DLI. In this study, we investigated the presence of tissue injury and inflammation in skin during the period of hematologic recovery and immune reconstitution after alloSCT.

Methods

Skin biopsies were immunohistochemically stained for HLA class II, CD1a, CD11c, CD40, CD54, CD68, CD86, CD206, CD3, and CD8. HLA class II-expressing cells were characterized as activated T-cells, antigen-presenting cells (APCs), or tissue repairing macrophages. In sex-mismatched patient and donor couples, origin of cells was determined by multiplex analysis combining XY-FISH and fluorescent immunohistochemistry.

Results

No inflammatory environment due to pretransplant conditioning was detected at the time of alloSCT, irrespective of the conditioning regimen. An increase in HLA class II-positive macrophages and CD3 T-cells was observed 12–24 weeks after myeloablative alloSCT, but these macrophages did not show signs of interaction with the co-localized T-cells. In contrast, during GVHD, an increase in HLA class II-expressing cells coinciding with T-cell interaction was observed, resulting in an overt inflammatory reaction with the presence of activated APC, activated donor T-cells, and localized upregulation of HLA class II expression on epidermal cells. In the absence of GVHD, patient derived macrophages were gradually replaced by donor-derived macrophages although patient-derived macrophages were detectable even 24 weeks after alloSCT.

Conclusion

Conditioning regimens cause tissue damage in the skin, but this does not result in a local increase of activated APC. In contrast to the inflamed situation in GVHD, when interaction takes place between activated APC and donor T-cells, the tissue damage caused by myeloablative alloSCT results in dermal recruitment of HLA class II-positive tissue repairing macrophages co-existing with increased numbers of patient- and donor-derived T-cells, but without signs of specific interaction and initiation of an immune response. Thus, the local skin damage caused by the conditioning regimen appears to be insufficient as single factor to provoke GVHD induction.

Graft versus tumor effects and why people relapse

Graft-versus-tumor (GVT) reactivity mediated by donor T cells in the context of allogeneic stem cell transplantation (alloSCT) is one of the most potent forms of cellular immunotherapy. The antitumor effect against hematologic malignancies is mediated by a polyclonal T-cell response targeting polymorphic antigens expressed on hematopoietic tissues of the recipient, leaving donor hematopoiesis in the patient after transplantation unharmed. Fortunately, hematopoietic tissues (including malignant hematopoietic cell populations) are relatively susceptible to T-cell recognition. If, however, nonhematopoietic tissues of the recipient are targeted as well, graft-versus-host disease (GVHD) will occur. The balance between GVT and GVHD is influenced by the genetic disparity between donor and recipient, the number and origin of professional antigen-presenting cells provoking the immune response, the target antigen specificity, magnitude and diversity of the response, and the in vivo inflammatory environment, whereas inhibitory factors may silence the immune response. Manipulation of each of these factors will determine the balance between GVT and GVHD.

Donor T-cell responses and disease progression patterns of multiple myeloma

Donor T-cells transferred after allogeneic stem cell transplantation (alloSCT) can result in long-term disease control in myeloma by the graft-versus-myeloma (GvM) effect. However, T-cell therapy may show differential effectiveness against bone marrow (BM) infiltration and focal myeloma lesions resulting in different control and progression patterns. Outcomes of 43 myeloma patients who underwent T-cell-depleted alloSCT with scheduled donor lymphocyte infusion (DLI) were analyzed with respect to diffuse BM infiltration and focal progression. For comparison, 12 patients for whom a donor search was started but no alloSCT was performed, were analyzed. After DLI, complete disappearance of myeloma cells in BM occurred in 86% of evaluable patients. The probabilities of BM progression-free survival (PFS) at 2 years after start of donor search, alloSCT and DLI, were 17% (95% confidence interval 0-38%), 51% (36-66%), and 62% (44-80%) respectively. In contrast, the probabilities of focal PFS at 2 years after start of donor search, alloSCT and DLI, were 17% (0-38%), 30% (17-44%) and 28% (11-44%), respectively. Donor-derived T-cell responses effectively reduce BM infiltration, but not focal progression in myeloma, illustrating potent immunological responses in BM with only limited effect of T-cells on focal lesions.

Autosomal Minor Histocompatibility Antigens: How Genetic Variants Create Diversity in Immune Targets

Allogeneic stem cell transplantation (alloSCT) can be a curative treatment for hematological malignancies. Unfortunately, the desired anti-tumor or graft-versus-leukemia (GvL) effect is often accompanied with undesired side effects against healthy tissues known as graft-versus-host disease (GvHD). After HLA-matched alloSCT, GvL and GvHD are both mediated by donor-derived T-cells recognizing polymorphic peptides presented by HLA surface molecules on patient cells. These polymorphic peptides or minor histocompatibility antigens (MiHA) are produced by genetic differences between patient and donor. Since polymorphic peptides may be useful targets to manipulate the balance between GvL and GvHD, the dominant repertoire of MiHA needs to be discovered. In this review, the diversity of autosomal MiHA characterized thus far as well as the various molecular mechanisms by which genetic variants create immune targets and the role of cryptic transcripts and proteins as antigen sources are described. The tissue distribution of MiHA as important factor in GvL and GvHD is considered as well as possibilities how hematopoietic MiHA can be used for immunotherapy to augment GvL after alloSCT. Although more MiHA are still needed for comprehensive understanding of the biology of GvL and GvHD and manipulation by immunotherapy, this review shows insight into the composition and kinetics of in vivo immune responses with respect to specificity, diversity, and frequency of specific T-cells and surface expression of HLA-peptide complexes and other (accessory) molecules on the target cell. A complex interplay between these factors and their environment ultimately determines the spectrum of clinical manifestations caused by immune responses after alloSCT.

Allo-reactive T cells for the treatment of hematological malignancies

Several mechanisms can be responsible for control of hematological tumors by allo-reactive T cells. Following allogeneic stem cell transplantation (alloSCT) donor T cells recognizing genetic disparities presented on recipient cells and not on donor cells are main effectors of tumor control, but also of the detrimental graft versus host disease (GVHD). Since after transplantation normal hematopoiesis is of donor origin, any T cell response directed against polymorphic antigens expressed on hematopoietic recipient cells but not on donor cells will result in an anti-tumor response not affecting normal hematopoiesis. After fully HLA-matched alloSCT, T cells recognizing polymorphic peptides derived from proteins encoded by genes selectively expressed in hematopoietic lineages may result in anti-tumor responses without GVHD. Due to the high susceptibility of hematopoietic cells for T cell recognition, a low amplitude of the overall T cell response may also be in favor of the anti-tumor reactivity in hematological malignancies. A mismatch between donor and patient for specific HLA-alleles can also be exploited to induce a selective T cell response against patient (malignant) hematopoietic cells. If restricting HLA class II molecules are selectively expressed on hematopoietic cells under non-inflammatory circumstances, allo HLA class-II responses may control the tumor with limited risk of GVHD. Alternatively, T cells recognizing hematopoiesis-restricted antigens presented in the context of mismatched HLA alleles may be used to treat patients with hematological cancers. This review discusses various ways to manipulate the allo-immune response aiming to exploit the powerful ability of allo-reactive T-cells to control the malignancies without causing severe damage to non-hematopoietic tissues.

Donor lymphocyte infusions to leukemic bone lesions are therapeutically effective in a Ph+ ALL patient with post-HSCT relapse

A Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) case was maintained in remission with the use of chemo-immunotherapy. The latter involved sibling bone marrow transplant (BMT) (three procedures) followed by intravenous (IV) donor lymphocyte infusion (DLI). The third relapse responded to routine chemotherapy and again DLI was employed. During hematological and molecular remission verified at the level of iliac crest aspiration, extra-medullary relapse in the bones was apparent. A novel procedure of donor lymphocyte injection to the bone leukemic lesions was developed and employed. A dose of 10(6) donor lymphocytes/kg body weight (BW) of the recipient were each time injected to the plane of the right and left tibia, the head of the humerus, and the calcaneus, which resulted in healing of the destructive process. In consequence of this novel approach, in addition to the healing of bone lesions, an accumulation of cytotoxic activated T-cells in the marrow was documented, which was mirrored by an increase in the number of transcripts for interferon (IFN)-γ, interleukin (IL)-17, as well as RORγt. The local administration of DLI directly to the leukemic lesions requires a lower dose that diminishes the toxicity due to the general immune system activation.

Collateral damage of nonhematopoietic tissue by hematopoiesis-specific T cells results in graft-versus-host disease during an ongoing profound graft-versus-leukemia reaction

After allogeneic stem cell transplantation (allo-SCT), donor T cells may recognize minor histocompatibility antigens (MiHA) specifically expressed on cells of the recipient. It has been hypothesized that T cells recognizing hematopoiesis-restricted MiHA mediate specific graft-versus-leukemia (GVL) activity without inducing graft-versus-host disease (GVHD), whereas T cells recognizing ubiquitously expressed MiHA induce both GVL and GVHD reactivity. It also has been hypothesized that alloreactive CD4 T cells are capable of mediating specific GVL reactivity due to the hematopoiesis-restricted expression of HLA class II. However, clinical observations suggest that an overt GVL response, associated with expansion of T cells specific for hematopoiesis-restricted antigens, is often associated with GVHD reactivity. Therefore, we developed in vitro models to investigate whether alloreactive T cells recognizing hematopoiesis-restricted antigens induce collateral damage to surrounding nonhematopoietic tissues. We found that collateral damage to MiHA-negative fibroblasts was induced by misdirection of cytotoxic granules released from MiHA-specific T cells activated by MiHA-positive hematopoietic cells, resulting in granzyme-B-mediated activation of apoptosis in the surrounding fibroblasts. We demonstrated that direct contact between the activated T cell and the fibroblast is a prerequisite for this collateral damage to occur. Our data suggest that hematopoiesis-restricted T cells actively participate in an overt GVL response and may contribute to GVHD via induction of collateral damage to nonhematopoietic targets.

Durable remission of renal cell carcinoma in conjuncture with graft versus host disease following allogeneic stem cell transplantation and donor lymphocyte infusion: rule or exception?

Allogeneic stem cell transplantation (alloSCT) followed by donor lymphocyte infusion (DLI) can be applied as immunotherapeutic intervention to treat malignant diseases. Here, we describe a patient with progressive metastatic clear cell renal cell carcinoma (RCC) who was treated with T cell depleted non-myeloablative alloSCT and DLI resulting in disease regression accompanied by extensive graft versus host disease (GVHD). We characterized the specificity of this immune response, and detected a dominant T cell population recognizing a novel minor histocompatibility antigen (MiHA) designated LB-FUCA2-1V. T cells specific for LB-FUCA2-1V were shown to recognize RCC cell lines, supporting a dominant role in the graft versus tumor (GVT) reaction. However, coinciding with the gradual disappearance of chronic GVHD, the anti-tumor effect declined and 3 years after alloSCT the metastases became progressive again. To re-initiate the GVT reaction, escalating doses of DLI were given, but no immune response could be induced and the patient died of progressive disease 8.5 years after alloSCT. Gene expression studies illustrated that only a minimal number of genes shared expression between RCC and professional antigen presenting cells but were not expressed by non-malignant healthy tissues, indicating that in patients suffering from RCC, GVT reactivity after alloSCT may be unavoidably linked to GVHD.

HLA class II upregulation during viral infection leads to HLA-DP-directed graft-versus-host disease after CD4+ donor lymphocyte infusion

CD8+ T cell-depleted (TCD) donor lymphocyte infusion (DLI) after TCD allogeneic hematopoietic stem cell transplantation (alloSCT) has been associated with a reduced risk of graft-versus-host disease (GVHD) while preserving conversion to donor hematopoiesis and antitumor immunity, providing a rationale for exploring CD4+ T cell-based immunotherapy for hematologic malignancies. Here, we analyzed the clinical course and specificity of T cell immune responses in 2 patients with acute myeloid leukemia (AML) who converted to full-donor chimerism but developed severe acute GVHD after prophylactic CD4+ DLI after 10/10-HLA-matched, but HLA-DPB1-mismatched TCD-alloSCT. Clonal analysis of activated T cells isolated during GVHD demonstrated allo-reactivity exerted by CD4+ T cells directed against patient-mismatched HLA-DPB1 molecules on hematopoietic cells and skin-derived fibroblasts only when cultured under inflammatory conditions. At the time of CD4+ DLI, both patients contained residual patient-derived T cells, including cytomegalovirus (CMV)-specific T cells as a result of CMV reactivations. Once activated by CMV antigens, these CMV-specific T cells could stimulate HLA-DPB1-specific CD4+ T cells, which in turn could target nonhematopoietic tissues in GVHD. In conclusion, our data demonstrate that GVHD after HLA-DPB1-mismatched CD4+ DLI can be mediated by allo-reactive HLA-DPB1-directed CD4+ T cells and that ongoing viral infections inducing HLA class II expression on nonhematopoietic cells may increase the likelihood of GVHD development. This trial is registered at http://www.controlled-trials.com/ISRCTN51398568/LUMC as #51398568.