James Coghill

In vitro-differentiated TH17 cells mediate lethal acute graft-versus-host disease with severe cutaneous and pulmonary pathologic manifestations

The morbidity and mortality associated with graft-host-disease (GVHD) is a significant obstacle to the greater use of allogeneic stem cell transplantation. Donor T cells that predominantly differentiate into TH1/Tc1 T cells and generate pro-inflammatory cytokines such as interferon-gamma (IFN-gamma) mediate GVHD. Although numerous studies have described a pathogenic role for IFN-gamma, multiple reports have demonstrated that the lack of IFN-gamma paradoxically exacerbated GVHD lethality. This has led to speculation that another subset of T cells may significantly contribute to GVHD mortality. Several groups have demonstrated a new lineage of CD4+ T helper cell development distinct from TH1 or TH2 differentiation. This lineage is characterized by production of interleukin (IL)-17A, IL-17F, IL-22, and IL-21 and has been termed TH17 cells. Here, we demonstrate that a highly purified population of TH17 cells is capable of inducing lethal GVHD, hallmarked by extensive pathologic cutaneous and pulmonary lesions. Upon transfer, these cells migrate to and expand in GVHD target organs and secondary lymphoid tissues. Finally, we demonstrate differential roles for tumor necrosis factor-alpha (TNF-alpha) and IL-17A in the clinical manifestations of GVHD induced by TH17 cells. Our studies demonstrate that cells other than TH1/Tc1 can mediate acute GVHD.

Effector CD4+ T cells, the cytokines they generate, and GVHD: something old and something new

GVHD is a syndrome that results from minor and major histocompatibility complex incompatibilities between the donor and recipient. More than 50 years after its initial description, the pathophysiology of GVHD remains poorly understood. Nonetheless, donor T cells have been shown to be critical to the pathophysiology of acute and chronic GVHD, yet precisely how they function remains unclear. The effector mechanisms by which donor T cells mediate tissue inflammation is even less well understood. Identification of several new lineages of CD4(+) T cells made in the past decade and their roles in the pathophysiology of T cell-mediated diseases has shed new light on these effector mechanisms. In this review, we summarize the recent descriptions of these T-cell lineages and the current data supporting their role in acute and to a lesser extent chronic GVHD. Investigations into the activity of these new T-cell lineages may provide more rationale approaches to the treatment or prevention of GVHD.

Separation of graft-versus-host disease from graft-versus-leukemia responses by targeting CC-chemokine receptor 7 on donor T cells

CC-chemokine receptor 7 (CCR7) is expressed on the surface of naive T cells, and plays a critical role in their movement into secondary lymphoid tissue. Here, we show that murine T cells lacking CCR7 (CCR7(-/-)) generate attenuated graft-versus-host disease (GVHD) responses compared with wild-type (WT) cells, with the difference varying inversely with the degree of major histocompatibility complex (MHC) disparity between the donor and recipient. CCR7(-/-) T cells exhibited an impaired ability to traffic to recipient lymph nodes, with an increased capacity to home to the spleen. CCR7(-/-) T cells, however, demonstrated a reduced ability to undergo in vivo expansion in the spleen due to impaired interactions with splenic antigen-presenting cells. On a cellular level, CCR7(-/-) T cells were functionally competent, demonstrating a normal in vitro proliferative capacity and a preserved ability to produce inflammatory cytokines. Importantly, CCR7(-/-) T cells were capable of generating robust graft-versus-leukemia (GVL) responses in vivo, as well as complete donor T-cell reconstitution. CCR7(-/-) regulatory T cells were able to protect against lethal GVHD when administered before WT conventional T cells. Our data suggest that CCR7 inhibition in the early posttransplantation period may represent a feasible new therapeutic approach for acute GVHD attenuation without compromising GVL responses.

Attenuation of Acute Graft-versus-Host Disease in the Absence of the Transcription Factor RORγt

Graft-versus-host disease (GVHD) remains the most significant complication after allogeneic stem cell transplantation. Previously, acute GVHD had been considered to be mediated predominantly by Th1-polarized T cells. Recently, investigators have identified a second proinflammatory lineage of T cells termed Th17 that is critically dependent on the transcription factor retinoic acid-related orphan receptor (ROR)γt. In this study, we have evaluated the role of Th17 cells in murine acute GVHD by infusing donor T cells lacking RORC and as a consequence the isoform RORγt. Recipients given donor CD4+ and CD8+ T cells lacking RORC had significantly attenuated acute GVHD and markedly decreased tissue pathology in the colon, liver, and lung. Using a clinically relevant haploidentical murine transplantation model, we showed that RORC−/− CD4+ T cells alone diminished the severity and lethality of acute GVHD. This was not found when CD4+ T cells from RORC−/− mice were given to completely mismatched BALB/c mice, and it was correlated with absolute differences in the generation of TNF in the colon after transplant. Thus, CD4+ T cell expression of RORC is important in the pathogenesis of acute GVHD.

CC chemokine receptor 8 potentiates donor Treg survival and is critical for the prevention of murine graft-versus-host disease.

The infusion of donor regulatory T cells (Tregs) has been used to prevent acute graft-versus-host disease (GVHD) in mice and has shown promise in phase 1 clinical trials. Previous work suggested that early Treg migration into lymphoid tissue was important for GVHD prevention. However, it is unclear how and where Tregs function longitudinally to affect GVHD. To better understand their mechanism of action, we studied 2 Treg-associated chemokine receptors in murine stem cell transplant models. CC chemokine receptor (CCR) 4 was dispensable for donor Treg function in the transplant setting. Donor Tregs lacking CCR8 (CCR8(-/-)), however, were severely impaired in their ability to prevent lethal GVHD because of increased cell death. By itself, CCR8 stimulation was unable to rescue Tregs from apoptosis. Instead, CCR8 potentiated Treg survival by promoting critical interactions with dendritic cells. In vivo, donor bone marrow-derived CD11c(+) antigen-presenting cells (APCs) were important for promoting donor Treg maintenance after transplant. In contrast, host CD11c(+) APCs appeared to be dispensable for early activation and expansion of donor Tregs. Collectively, our data indicate that a sustained donor Treg presence is critical for their beneficial properties, and that their survival depends on CCR8 and donor but not host CD11c(+) APCs.

Intravital imaging of donor allogeneic effector and regulatory T cells with host dendritic cells during GVHD

Graft-versus-host disease (GVHD) is a systemic inflammatory response due to the recognition of major histocompatibility complex disparity between donor and recipient after hematopoietic stem cell transplantation (HSCT). T-cell activation is critical to the induction of GVHD, and data from our group and others have shown that regulatory T cells (Tregs) prevent GVHD when given at the time of HSCT. Using multiphoton laser scanning microscopy, we examined the single cell dynamics of donor T cells and dendritic cells (DCs) with or without Tregs postallogeneic transplantation. We found that donor conventional T cells (Tcons) spent very little time screening host DCs. Tcons formed stable contacts with DCs very early after transplantation and only increased velocity in the lymph node at 20 hours after transplant. We also observed that Tregs reduced the interaction time between Tcons and DCs, which was dependent on the generation of interleukin 10 by Tregs. Imaging using inducible Tregs showed similar disruption of Tcon-DC contact. Additionally, we found that donor Tregs induce host DC death and down-regulate surface proteins required for donor T-cell activation. These data indicate that Tregs use multiple mechanisms that affect host DC numbers and function to mitigate acute GVHD.

The biology and therapeutic potential of natural regulatory T-cells in the bone marrow transplant setting

Graft-versus-host disease (GVHD) remains a major barrier to the long-term success of allogeneic hematopoietic stem-cell transplantation for hematologic malignancies. This has prompted a great deal of interest in the development of alternative GVHD management strategies such as the adoptive transfer of lymphocytes with immunosuppressant activity. This review will focus on the biology of thymically derived regulatory T-cells (Tregs) and their potential therapeutic role in human bone marrow transplantation. A discussion of their basic suppressive mechanisms and in vivo trafficking patterns will be presented, along with an overview of important preclinical studies using murine GVHD/tumor models. Currently available clinical data will also be discussed, including the contribution of Tregs to various transplant outcome parameters such as GVHD incidence and malignancy relapse rates.

Effectiveness of etoposide chemomobilization in lymphoma patients undergoing auto-SCT

The effectiveness of stem cell mobilization with G-CSF in lymphoma patients is suboptimal. We reviewed our institutional experience using chemomobilization with etoposide (VP-16; 375 mg/m2 on days +1 and +2) and G-CSF (5 μg/kg twice daily from day +3 through the final day of collection) in 159 patients with lymphoma. This approach resulted in successful mobilization (>2 × 106 CD34+ cells collected) in 94% of patients (83% within 4 apheresis sessions). Fifty-seven percent of patients yielded at least 5 × 106 cells in ⩽2 days and were defined as good mobilizers. The regimen was safe with a low rate of rehospitalization. Average costs were

Type 2 innate lymphoid cells treat and prevent acute gastrointestinal graft-versus-host disease

14 923 for good mobilizers and

Peptide/MHC tetramer-based sorting of CD8 T cells to a Leukemia antigen yields clonotypes drawn nonspecifically from an underlying restricted repertoire

27 044 for poor mobilizers (P<0.05). Using our data, we performed a ‘break-even’ analysis that demonstrated that adding two doses of Plerixafor to predicted poor mobilizers at the time of first CD34+ cell count would achieve cost neutrality if the frequency of good mobilizers were to increase by 21%, while the frequency of good mobilizers would need to increase by 25% if three doses of Plerixafor were used. We conclude that chemomobilization with etoposide and G-CSF in patients with lymphoma is effective, with future opportunities for cost-neutral improvement using novel agents.