Recipient CD4+ T cells that survive irradiation regulate chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is an increasingly common cause of morbidity and mortality in allogeneic stem cell transplantation (alloSCT). Relative to acute GVHD (aGVHD), much less is understood about cGVHD. Using the B10.D2 --> BALB/c murine cGVHD model, which shares critical pathologic features with human cGVHD, we find that radiation-resistant host T cells regulate cGVHD. We initially observed that recipients lacking all lymphocytes developed accelerated and more severe cGVHD. Using genetically deficient recipients, we determined that alphabeta+CD4+ T cells were required to regulate cGVHD. Increased cGVHD severity was not due to the absence of T cells per se. Rather, the potency of regulation was proportional to host T-cell receptor (TCR) diversity. Only CD4+CD25+, and not CD4+CD25-, host T cells ameliorated cGVHD when added back, indicating that host T cells acted not via host-versus-graft activity or by reducing homeostatic proliferation but by an undefined regulatory mechanism. Thus, preparative regimens that spare host CD4+CD25+ T cells may reduce cGVHD. Donor CD4+CD25+ T cells also reduced cGVHD. Depletion of CD4+CD25+ cells from the inoculum exacerbated disease, whereas transplantation of additional CD4+CD25+ cells protected against severe cGVHD. Additional CD4+CD25+ cells also promoted healing of established lesions, suggesting that their effects persist during the evolution of cGVHD.     

Effector memory CD4+ T cells mediate graft-versus-leukemia without inducing graft-versus-host disease

Much of the efficacy of allogeneic hematopoietic stem cell transplantation (alloSCT) in curing hematologic malignancies is due to a graft-versus-leukemia (GVL) effect mediated by donor T cells that recognize recipient alloantigens on leukemic cells. Donor T cells are also important for reconstituting immunity in the recipient. Unfortunately, donor T cells can attack nonmalignant host tissues and cause graft-versus-host disease (GVHD). We previously reported that donor CD4(+) effector memory T cells (T(EMs)) do not cause GVHD but transfer functional T-cell memory. In the present work, we demonstrate in an MHC-mismatched model that CD4(+) T(EMs) (unprimed to recipient antigens) mediate GVL against clinically relevant mouse models of chronic phase and blast crisis chronic myelogenous leukemia, without causing GVHD. By creating gene-deficient leukemias and using perforin-deficient T cells, we demonstrate that direct cytolytic function is essential for T(EM)-mediated GVL, but that GVL is retained when killing via FasL, TNF-alpha, TRAIL, and perforin is individually impaired. However, T(EM)-mediated GVL was diminished when both FasL and perforin pathways were blocked. Taken together, our studies identify T(EMs) as a clinically applicable cell therapy for promoting GVL and immune reconstitution, particularly in MHC-mismatched haploidentical alloSCTs in which T cell-depleted allografts are commonly used to minimize GVHD.     

Regulatory dendritic cells protect against cutaneous chronic graft-versus-host disease mediated through CD4+CD25+Foxp3+ regulatory T cells

Chronic graft-versus-host disease (cGVHD) is a common cause of morbidity and mortality in allogeneic bone marrow transplantation (alloBMT). However, effective strategies for the treatment of cGVHD have not been established. In this study, we examined the therapeutic utility of modified dendritic cells (DCs) with a greater capacity to regulate immune responses than previously known tolerogenic DCs, regulatory DCs (DC(regs)), in the major histocompatibility complex-compatible, and multiple minor histocompatibility antigen-incompatible model of cGVHD in alloBMT. Treatment of the recipient mice after alloBMT with the recipient-type DC(regs) led to greater suppression of the incidence and severity of cutaneous cGVHD than rapamycin, whereas treatment with the recipient-type mature DCs promoted the pathogenesis. Analysis of the recipient mice suggested that the protective effect of the recipient-type DC(regs) involved the peripheral generation of alloreactive CD4(+)CD25(+)Foxp3(+)regulatory T (T(R)) cells from donor-derived CD4(+)CD25(-)Foxp3(-) T cells. Thus, immunotherapy with DC(regs) is a promising strategy for the treatment of cGVHD in alloBMT mediated through the induction of a dominant tolerance involving CD4(+)CD25(+)Foxp3(+) T(R) cells.     

In vivo-activated CD103+CD4+ regulatory T cells ameliorate ongoing chronic graft-versus-host disease

CD103 (alphaEbeta7) has been shown to be an excellent marker for identifying in vivo-activated FoxP3(+)CD4(+) regulatory T (Treg) cells. It is unknown whether reinfusion of in vivo-activated donor-type CD103(+) Treg cells from recipient can ameliorate ongoing chronic graft-versus-host disease (GVHD). Here, we showed that, in a chronic GVHD model of DBA/2 (H-2(d)) donor to BALB/c (H-2(d)) recipient, donor-type CD103(+) Treg cells from recipients were much more potent than CD25(hi) natural Treg cells from donors in reversing clinical signs of GVHD and tissue damage. Furthermore, in contrast to CD25(hi) natural Treg cells, CD103(+) Treg cells expressed high levels of CCR5 but low levels of CD62L and directly migrated to GVHD target tissues. In addition, the CD103(+) Treg cells strongly suppressed donor CD4(+) T-cell proliferation; they also induced apoptosis of in vivo-activated CD4(+) T and B cells and significantly reduced pathogenic T and B cells in GVHD target tissues. These results indicate that CD103(+) Treg cells from chronic GVHD recipients are functional, and reinfusion of the CD103(+) Treg cells can shift the balance between Treg cells and pathogenic T cells in chronic GVHD recipients and ameliorate ongoing disease.     

Inhibition of histone methylation arrests ongoing graft-versus-host disease in mice by selectively inducing apoptosis of alloreactive effector T cells

Histone methylation is thought to be important for regulating Ag-driven T-cell responses. However, little is known about the effect of modulating histone methylation on inflammatory T-cell responses. We demonstrate that in vivo administration of the histone methylation inhibitor 3-deazaneplanocin A (DZNep) arrests ongoing GVHD in mice after allogeneic BM transplantation. DZNep caused selective apoptosis in alloantigen-activated T cells mediating host tissue injury. This effect was associated with the ability of DZNep to selectively reduce trimethylation of histone H3 lysine 27, deplete the histone methyltransferase Ezh2 specific to trimethylation of histone H3 lysine 27, and activate proapoptotic gene Bim repressed by Ezh2 in antigenic-activated T cells. In contrast, DZNep did not affect the survival of alloantigen-unresponsive T cells in vivo and naive T cells stimulated by IL-2 or IL-7 in vitro. Importantly, inhibition of histone methylation by DZNep treatment in vivo preserved the antileukemia activity of donor T cells and did not impair the recovery of hematopoiesis and lymphocytes, leading to significantly improved survival of recipients after allogeneic BM transplantation. Our findings indicate that modulation of histone methylation may have significant implications in the development of novel approaches to treat ongoing GVHD and other T cell-mediated inflammatory disorders in a broad context.     

Donor-derived interferon gamma separates graft-versus-leukemia effects and graft-versus-host disease induced by donor CD8 T cells

The graft-versus-leukemia (GVL) effects and graft-versus-host disease (GVHD)-inducing activity of CD8 T cells was compared in murine recipients of wild-type (WT) or interferon gamma (IFN-gamma)-deficient (GKO) allogeneic donor cells. CD8 T cells (or CD4-depleted splenocytes) from GKO donor mice induced more severe GVHD in lethally irradiated allogeneic recipients compared to the same cell populations from WT donors. Consistent with GVHD severity, donor CD8 T-cell expansion in allogeneic recipients was augmented in the absence of IFN-gamma. These results demonstrate that IFN-gamma does not stimulate but instead down-modulates GVHD induced by donor CD8 T cells. Remarkably, antihost lymphohematopoietic reactions, including GVL effects against host leukemia/lymphoma cells, of CD8 T cells correlated inversely with their GVHD-inducing activity, and those of GKO donors were markedly weaker than those mediated by WT donor CD8 T cells. These data show for the first time that GVHD-inducing activity and GVL effects of allogeneic CD8 T cells can be separated by a single cytokine, IFN-gamma. (Blood. 2002;99:4207-4215)     

Severe chronic graft-versus-host disease is characterized by a preponderance of CD4(+) effector memory cells relative to central memory cells

Donor alloreactive CD4(+) T cells are important to the pathogenesis of chronic graft-versus-host disease (cGVHD), but specific subsets of CD4(+) T cells responsible for GVHD have not been defined. We hypothesized that cGVHD might be associated with a preponderance of CD4(+) effector memory cells (CCR7(-)/CD62L(low), CD4(EM)). We analyzed CCR7 and CD62L expression on CD4(+) T cells from stem cell transplantation patients, who did or did not develop cGVHD, and healthy donors. Patients with cGVHD had a higher percentage of CD4(EM) cells (35.5% +/- 2.9%) than healthy donors (13.8% +/- 0.7%; P <.0001) or patients without cGVHD that received a transplant (21.7% +/- 2.1%; P <.01). Using corticosteroid dose as a surrogate marker for cGVHD severity, severe cGVHD was associated with a higher percentage of CD4(EM) cells. The proportion of CD4(EM) cells in corticosteroid-dependent patients with systemic lupus erythematosis or Wegener granulomatosis did not differ from patients without cGVHD that received a transplant. This finding implies that overrepresentation of CD4(EM) cells is a unique feature of cGVHD.     

Transfer of allogeneic CD62L- memory T cells without graft-versus-host disease

The major challenge in allogeneic hematopoietic cell transplantation is how to transfer allogeneic T-cell immunity without causing graft-versus-host disease (GVHD). Here we report a novel strategy to selectively prevent GVHD by depleting CD62L(+) T cells (naive and a subset of memory T cells). In unprimed mice, CD62L(-) T cells (a subset of memory T cells) failed to proliferate in response to alloantigens (which the mice have never previously encountered) and were unable to induce GVHD in allogeneic hosts. CD62L(-) T cells contributed to T-cell reconstitution by peripheral expansion as well as by promoting T-cell regeneration from bone marrow stem/progenitor cells. CD62L(-) T cells from the animals previously primed with a tumor cell line (BCL1) were able to inhibit the tumor growth in vivo but were unable to induce GVHD in the third-party recipients. This novel technology may allow transfer of allogeneic recall antitumor and antimicrobial immunity without causing GVHD.     

Donor CD4+ T and B cells in transplants induce chronic graft-versus-host disease with autoimmune manifestations

Chronic graft-vs-host disease (GVHD) is a major cause of morbidity and mortality of long-term survivors of allogeneic hemato-poietic cell transplantation (HCT). Chronic GVHD can have features of an autoimmune collagen vascular disease with clinical manifestations similar to autoimmune scleroderma and systemic lupus erythematosus (SLE). However, the pathogenesis of chronic GVHD is poorly understood. It is unclear how autoreactive T and B cells are generated in chronic GVHD recipients. We have recently developed a new chronic GVHD model by transplantation of donor DBA/2 (H-2d) spleen cells into major histocompatibility complex (MHC)-matched but minor antigen-mismatched sublethally irradiated BALB/c (H-2d) recipients as well as athymic BALB/c(nu/nu) and adult-thymectomized BALB/c recipients. Both euthymic and athymic BALB/c recipients developed high levels of serum IgG autoantibodies, sclerodermatous skin damage, and glomerulonephritis. Disease induction required both donor CD25-CD4+ T and B cells in transplants. In contrast, donor CD25+CD4+ T regulatory (Treg) cells prevented the disease induction. These results indicate that host thymus is not required for induction of chronic GVHD and that quiescent autoreactive T and B cells in transplants from nonautoimmune donors may be activated and expanded to cause chronic GVHD with autoimmune manifestations in allogeneic recipients, and donor Treg cells can suppress this process.     

Imbalance of effector and regulatory CD4 T cells is associated with graft-versus-host disease after hematopoietic stem cell transplantation using a reduced intensity conditioning regimen and alemtuzumab

Background

A variety of immune pathways can lead to graft-versus-host disease. A better understanding of the type of immune response causing graft-versus-host disease in defined clinical hematopoietic stem cell transplant settings is required to inform development of methods for monitoring patients and providing them tailored care.

Design and Methods

Twenty-five patients were recruited presenting with myeloid malignancies and treated with a reduced intensity conditioning transplant regimen with graft-versus-host disease prophylaxis comprising in vivo lymphocyte depletion with alemtuzumab and cyclosporin. A prospective study was performed of lymphocyte subset reconstitution in peripheral blood in relation to the incidence of graft-versus-host disease.

Results

Acute graft-versus-host disease was associated with significantly higher numbers of natural killer cells and donor-derived effector CD4 T cells (CD45RO⁺ CD27⁻) early (day 30) after transplantation (p=0.04 and p=0.02, respectively). This association was evident before the emergence of clinical pathology in six out of seven patients. Although numbers of regulatory CD4 T cells (CD25^high Foxp3⁺) were similar at day 30 in all patients, a significant deficit in those who developed acute graft-versus-host disease was apparent relative to effector CD4 T cells (median of 41 effectors per regulatory cell compared to 12 to 1 for patients without graft-versus-host disease) (p=0.03). By day 180, a functional regulatory CD4 T-cell population had expanded significantly in patients who developed chronic graft-versus-host disease, reversing the imbalance (median of 3 effectors per regulatory cell compared to 9.6 to 1 for patients without graft-versus-host disease) (p=0.018) suggesting no overt absence of immune regulation in the late onset form of the disease.

Conclusions

Imbalance of effector and regulatory CD4 T cells is a signature of graft-versus-host disease in this transplantation protocol.     

Migration and accumulation of effector CD4+ T cells in nonlymphoid tissues

The migration of antigen-specific T cells to nonlymphoid tissues is thought to be important for the elimination of foreign antigens from the body. Here, we review the evidence that naive CD4(+) T cells are first activated by antigen presentation in secondary lymphoid organs, proliferate, and differentiate into effector cells capable of producing antimicrobial lymphokines. These effector cells then leave the secondary lymphoid organs and use newly acquired trafficking receptors to extravasate at sites of inflammation. We argue that antigen presentation is required to retain effector CD4(+) T cells in inflamed sites, and speculate on the antigen-presenting cells and adhesion pathways that are involved.     

Chronic graft-versus-host disease is associated with increased numbers of peripheral blood CD4+CD25high regulatory T cells

Chronic graft-versus-host disease (cGVHD) is characterized by a state of profound immunodeficiency in association with alloreactive and autoimmune phenomena. These observations indicate an impairment of immunologic tolerance that could involve both central and peripheral mechanisms. Defective thymic function may contribute to dysregulation of central tolerance, but few studies have addressed peripheral tolerance. Recently a population of CD4+CD25+ T cells (Treg cells) has been characterized, which controls immunologic reactivity in vivo and which on transfer can prevent experimental acute GVHD. We investigated the number and function of peripheral blood CD4+CD25high T cells in patients more than 100 days after allogeneic hematopoietic stem cell transplantation. Patients with cGVHD had markedly elevated numbers of CD4+CD25high T cells as compared to patients without GVHD. CD4+CD25high T cells derived from patients in both groups were of donor origin, lacked markers of recent activation, and expressed intracellular CD152. In contrast to controls, CD4+CD25high T cells derived from patients with cGVHD were characterized by lower surface CD62L expression. In vitro, CD4+CD25high T cells were hyporesponsive to polyclonal stimulation and suppressed the proliferation and cytokine synthesis of CD4+CD25- cells, an effect that was independent of interleukin 10. These results indicate that chronic graft-versus-host injury does not occur as a result of Treg cell deficiency.     

Effects of donor T-cell trafficking and priming site on graft-versus-host disease induction by naive and memory phenotype CD4 T cells

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality in allogeneic stem cell transplantation. Effector memory T cells (T_EM) do not cause GVHD but engraft and mount immune responses, including graft-versus-tumor effects. One potential explanation for the inability of T_EM to cause GVHD is that T_EM lack CD62L and CCR7, which are instrumental in directing naive T cells (T_N) to lymph nodes (LN) and Peyer patches (PP), putative sites of GVHD initiation. Thus T_EM should be relatively excluded from LN and PP, possibly explaining their inability to cause GVHD. We tested this hypothesis using T cells deficient in CD62L or CCR7, transplant recipients lacking PNAd ligands for CD62L, and recipients without LN and PP or LN, PP, and spleen. Surprisingly, CD62L and CCR7 were not required for T_N-mediated GVHD. Moreover, in multiple strain pairings, GVHD developed in recipients that lacked LN and PP. Mild GVHD could even be induced in mice lacking all major secondary lymphoid tissues (SLT). Conversely, enforced constitutive expression of CD62L on T_EM did not endow them with the ability to cause GVHD. Taken together, these data argue against the hypothesis that T_EM fail to induce GVHD because of inefficient trafficking to LN and PP.      

Peripheral CD4(+)CD8(+) T cells are differentiated effector memory cells with antiviral functions

Although an increased frequency of CD4(+)CD8(+) T cells has been observed in the peripheral blood during viral infections, their role, function, and biologic significance are still poorly understood. Here we demonstrate that the circulating CD4(+)CD8(+) T-cell population contains mature effector memory lymphocytes specific for antigens of multiple past, latent, and high-level persistent viral infections. Upon in vitro antigenic challenge, a higher frequency of CD4(+)CD8(+) than single-positive cells displayed a T helper 1/T cytotoxic 1 (Th1/Tc1) cytokine profile and proliferated. Ex vivo, more double-positive than single-positive cells exhibited a differentiated phenotype. Accordingly, their lower T-cell receptor excision circles (TREC) content and shorter telomeres proved they had divided more frequently than single-positive cells. Consistent with expression of the tissue-homing marker CXCR3, CD4(+)CD8(+) T cells were demonstrated in situ at the site of persistent viral infection (ie, in the liver during chronic hepatitis C). Finally, a prospective analysis of hepatitis C virus (HCV) infection in a chimpanzee, the only animal model for HCV infection, showed a close correlation between the frequency of activated CD4(+)CD8(+) T cells and viral kinetics. Collectively, these findings demonstrate that peripheral CD4(+)CD8(+) T cells take part in the adaptive immune response against infectious pathogens and broaden the perception of the T-cell populations involved in antiviral immune responses.     

Maintenance of HIV-specific central and effector memory CD4 and CD8 T cells requires antigen persistence

The HIV-specific central and effector CD4 and CD8 memory T cell populations disappear from the peripheral blood of infected individuals under highly active antiretroviral therapy (HAART) with a mean half-life of 6.0 and 7.7 months, respectively. By contrast, cytomegalovirus (CMV)-specific responses are stable or increase. The striking quantitative differences between T cell memory to two persistent viral infections are instructive as to how antigen dosage contributes to the maintenance of antigen-specific memory T cell responses in humans.     

Glucocorticoid-induced tumor necrosis factor receptor family-related protein triggering enhances HIV-specific CD4+ T cell cytokine secretion and protects HIV-specific CD4+ T cells from apoptosis

Human immunodeficiency virus (HIV)-specific CD4(+) T cell cytokine secretion is characteristically weak during HIV infection, in part because HIV-specific CD4(+) T cells undergo massive apoptotic deletion. Glucocorticoid-induced tumor necrosis factor (TNF) receptor family-related (GITR) protein triggering enhances murine antigen-specific T cell cytokine secretion by protecting T cells from apoptosis. Therefore, we investigated the impact of GITR triggering on HIV-specific CD4(+) T cell cytokine secretion and on apoptosis of HIV-specific CD4(+) T cells. In HIV-infected subjects, CD4(+) T cell surface expression of GITR was greater than that in uninfected control subjects, and phytohemagglutinin induction of additional GITR expression was impaired. However, antibody triggering of GITR significantly increased HIV-specific CD4(+) T cell expression of TNF- alpha and interferon (IFN)- gamma . The percentage increase in HIV-specific CD4(+) T cell expression of TNF- alpha correlated directly with the absolute peripheral CD4(+) T cell count. Furthermore, GITR triggering reduced the expression of intracellular activated caspase-3 in HIV-specific CD4(+) T cells. Taken together, these data suggest that, despite abnormal GITR expression during HIV infection, GITR triggering enhances HIV-specific CD4(+) T cell cytokine expression and protects HIV-specific CD4(+) T cells from apoptosis.