Homing characteristics of donor T cells after experimental allogeneic bone marrow transplantation and posttransplantation therapy for multiple myeloma

Equine arteritis virus long-term persistence is orchestrated by CD8+ T lymphocyte transcription factors, inhibitory receptors, and the CXCL16/CXCR6 axis

Equine arteritis virus (EAV) has the unique ability to establish long-term persistent infection in the reproductive tract of stallions and be sexually transmitted. Previous studies showed that long-term persistent infection is associated with a specific allele of the CXCL16 gene (CXCL16S) and that persistence is maintained despite the presence of local inflammatory and humoral and mucosal antibody responses. Here, we performed transcriptomic analysis of the ampullae, the primary site of EAV persistence in long-term EAV carrier stallions, to understand the molecular signatures of viral persistence. We demonstrated that the local CD8+ T lymphocyte response is predominantly orchestrated by the transcription factors eomesodermin (EOMES) and nuclear factor of activated T-cells cytoplasmic 2 (NFATC2), which is likely modulated by the upregulation of inhibitory receptors. Most importantly, EAV persistence is associated with an enhanced expression of CXCL16 and CXCR6 by infiltrating lymphocytes, providing evidence of the implication of this chemokine axis in the pathogenesis of persistent EAV infection in the stallion reproductive tract. Furthermore, we have established a link between the CXCL16 genotype and the gene expression profile in the ampullae of the stallion reproductive tract. Specifically, CXCL16 acts as a "hub" gene likely driving a specific transcriptional network. The findings herein are novel and strongly suggest that RNA viruses such as EAV could exploit the CXCL16/CXCR6 axis in order to modulate local inflammatory and immune responses in the male reproductive tract by inducing a dysfunctional CD8+ T lymphocyte response and unique lymphocyte homing in the reproductive tract.

Chemokines Modulate Immune Surveillance in Tumorigenesis, Metastasis, and Response to Immunotherapy

Chemokines are small secreted proteins that orchestrate migration and positioning of immune cells within the tissues. Chemokines are essential for the function of the immune system. Accumulating evidence suggest that chemokines play important roles in tumor microenvironment. In this review we discuss an association of chemokine expression and activity within the tumor microenvironment with cancer outcome. We summarize regulation of immune cell recruitment into the tumor by chemokine-chemokine receptor interactions and describe evidence implicating chemokines in promotion of the "inflamed" immune-cell enriched tumor microenvironment. We review both tumor-promoting function of chemokines, such as regulation of tumor metastasis, and beneficial chemokine roles, including stimulation of anti-tumor immunity and response to immunotherapy. Finally, we discuss the therapeutic strategies target tumor-promoting chemokines or induce/deliver beneficial chemokines within the tumor focusing on pre-clinical studies and clinical trials going forward. The goal of this review is to provide insight into comprehensive role of chemokines and their receptors in tumor pathobiology and treatment.

CXCR4, but not CXCR3, drives CD8+ T-cell entry into and migration through the murine bone marrow

The BM serves as a blood-forming organ, but also supports the maintenance and immune surveillance function of many T cells. Yet, in contrast to other organs, little is known about the molecular mechanisms that drive T-cell migration to and localization inside the BM. As BM accumulates many CXCR3-expressing memory CD8⁺ T cells, we tested the involvement of this chemokine receptor, but found that CXCR3 is not required for BM entry. In contrast, we could demonstrate that CXCR4, which is highly expressed on both naive and memory CD8⁺ T cells in BM, is critically important for homing of all CD8⁺ T-cell subsets to the BM in mice. Upon entry into the BM parenchyma, both naïve and memory CD8⁺ T cells locate close to sinusoidal vessels. Intravital imaging experiments revealed that CD8 T cells are surprisingly immobile and we found that they interact with ICAM-1+VCAM-1+BP-1+ perivascular stromal cells. These cells are the major source of CXCL12, but also express key survival factors and maintenance cytokines IL-7 and IL-15. We therefore conclude that CXCR4 is not only crucial for entry of CD8⁺ T cells into the BM, but also controls their subsequent localization toward BM niches that support their survival.

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.

CD8+ T cells drive autoimmune hematopoietic stem cell dysfunction and bone marrow failure

Bone marrow (BM) failure syndrome encompasses a group of disorders characterized by BM stem cell dysfunction, resulting in varying degrees of hypoplasia and blood pancytopenia, and in many patients is autoimmune and inflammatory in nature. The important role of T helper 1 (Th1) polarized CD4⁺ T cells in driving BM failure has been clearly established in several models. However, animal model data demonstrating a functional role for CD8⁺ T cells in BM dysfunction is largely lacking and our objective was to test the hypothesis that CD8⁺ T cells play a non-redundant role in driving BM failure. Clinical evidence implicates a detrimental role for CD8⁺ T cells in BM failure and a beneficial role for Foxp3⁺ regulatory T cells (Tregs) in maintaining immune tolerance in the BM. We demonstrate that IL-2-deficient mice, which have a deficit in functional Tregs, develop spontaneous BM failure. Furthermore, we demonstrate a critical role for CD8⁺ T cells in the development of BM failure, which is dependent on the cytokine, IFNγ. CD8⁺ T cells promote hematopoietic stem cell dysfunction and depletion of myeloid lineage progenitor cells, resulting in anemia. Adoptive transfer experiments demonstrate that CD8⁺ T cells dramatically expedite disease progression and promote CD4⁺ T cell accumulation in the BM. Thus, BM dysregulation in IL-2-deficient mice is mediated by a Th1 and IFNγ-producing CD8⁺ T cell (Tc1) response.

Insights into the mechanism of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis

The chemokine CXCL12 and its receptor CXCR4 are important signaling components required for human blastocyst implantation and the progression of pregnancy. Growing evidence indicates that the CXCL12/CXCR4 axis can regulate trophoblast function and uterine spiral artery remodeling, which plays a fundamental role in placentation and fetal outcome. The orphan receptor CXCR7 is also believed to partly regulate the function of the CXCL12/CXCR4 axis. Additionally, the CXCL12/CXCR4/CXCR7 axis can enhance the cross-talk between trophoblasts and decidual cells such as uterine natural killer cells and decidual stromal cells which are involved in regulation of trophoblast differentiation and invasion and placental angiogenesis. In addition, recent studies proved that CXCL12 expression is elevated in the placenta and mid-trimester amniotic fluid of pregnant women with preeclampsia, implying that dysregulation of CXCL12 plays a role in the pathogenesis of preeclampsia. Further understanding of the regulatory mechanisms of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis may help to design novel therapeutic approaches for pregnancy-associated diseases.

Establishment of a murine graft-versus-myeloma model using allogeneic stem cell transplantation

Background

Multiple myeloma (MM) is a malignant plasma cell disorder with poor long-term survival and high recurrence rates. Despite evidence of graft-versus-myeloma (GvM) effects, the use of allogeneic hematopoietic stem cell transplantation (allo-SCT) remains controversial in MM. In the current study, we investigated the anti-myeloma effects of allo-SCT from B10.D2 mice into MHC-matched myeloma-bearing Balb/cJ mice, with concomitant development of chronic graft-versus-host disease (GvHD).

Methods and results

Balb/cJ mice were injected intravenously with luciferase-transfected MOPC315.BM cells, and received an allogeneic (B10.D2 donor) or autologous (Balb/cJ donor) transplant 30 days later. We observed a GvM effect in 94% of the allogeneic transplanted mice, as the luciferase signal completely disappeared after transplantation, whereas all the autologous transplanted mice showed myeloma progression. Lower serum paraprotein levels and lower myeloma infiltration in bone marrow and spleen in the allogeneic setting confirmed the observed GvM effect. In addition, the treated mice also displayed chronic GvHD symptoms. In vivo and in vitro data suggested the involvement of effector memory CD4 and CD8 T cells associated with the GvM response. The essential role of CD8 T cells was demonstrated in vivo where CD8 T-cell depletion of the graft resulted in reduced GvM effects. Finally, TCR Vβ spectratyping analysis identified Vβ families within CD4 and CD8 T cells, which were associated with both GvM effects and GvHD, whereas other Vβ families within CD4 T cells were associated exclusively with either GvM or GvHD responses.

Conclusions

We successfully established an immunocompetent murine model of graft-versus-myeloma. This is the first murine GvM model using immunocompetent mice that develop MM which closely resembles human MM disease and that are treated after disease establishment with an allo-SCT. Importantly, using TCR Vβ spectratyping, we also demonstrated the presence of GvM unique responses potentially associated with the curative capacity of this immunotherapeutic approach.

Cellular immunotherapy in multiple myeloma: lessons from preclinical models

The majority of multiple myeloma patients relapse with the current treatment strategies, raising the need for alternative therapeutic approaches. Cellular immunotherapy is a rapidly evolving field and currently being translated into clinical trials with encouraging results in several cancer types, including multiple myeloma. Murine multiple myeloma models are of critical importance for the development and refinement of cellular immunotherapy. In this review, we summarize the immune cell changes that occur in multiple myeloma patients and we discuss the cell-based immunotherapies that have been tested in multiple myeloma, with a focus on murine models.

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.