Importance of interleukin-7 in the development of experimental graft-versus-host disease

Defibrotide impact on the acute GVHD disease incidence in pediatric hematopoietic stem cell transplant recipients

Despite advances in acute graft-versus-host disease (aGVHD) prophylaxis, current pharmacological approaches fail to prevent aGVHD. The protective effect of defibrotide on GVHD incidence and GVHD-free survival has not been sufficiently studied. 91 pediatric patients included in this retrospective study were divided into two groups based on defibrotide use. We compared the incidence of aGVHD and chronic GVHD-free survival between the defibrotide and control groups. The incidence and severity of aGVHD were significantly lower in patients who received defibrotide prophylactic administration than in the control group. This improvement was observed in the liver and intestinal aGVHD. No defibrotide prophylaxis benefit was observed in the prevention of chronic GVHD. The pro-inflammatory cytokine levels were significantly higher in the control group. Our findings suggest that prophylactic administration of defibrotide in pediatric patients significantly reduces the incidence and severity of aGVHD, with a modification of cytokine pattern, both strongly coherent with the protective drug's action. This evidence adds to pediatric retrospective studies and preclinical data suggesting a possible defibrotide role in this setting.

Identification of New Soluble Factors Correlated With the Development of Graft Failure After Haploidentical Hematopoietic Stem Cell Transplantation

Graft failure is a severe complication of allogeneic hematopoietic stem cell transplantation (HSCT). The mechanisms involved in this phenomenon are still not completely understood; data available suggest that recipient T lymphocytes surviving the conditioning regimen are the main mediators of immune-mediated graft failure. So far, no predictive marker or early detection method is available. In order to identify a non-invasive and efficient strategy to diagnose this complication, as well as to find possible targets to prevent/treat it, we performed a detailed analysis of serum of eight patients experiencing graft failure after T-cell depleted HLA-haploidentical HSCT. In this study, we confirm data describing graft failure to be a complex phenomenon involving different components of the immune system, mainly driven by the IFNγ pathway. We observed a significant modulation of IL7, IL8, IL18, IL27, CCL2, CCL5 (Rantes), CCL7, CCL20 (MIP3a), CCL24 (Eotaxin2), and CXCL11 in patients experiencing graft failure, as compared to matched patients not developing this complication. For some of these factors, the difference was already present at the time of infusion of the graft, thus allowing early risk stratification. Moreover, these cytokines/chemokines could represent possible targets, providing the rationale for exploring new therapeutic/preventive strategies.

Foxo1 and Foxp1 play opposing roles in regulating the differentiation and antitumor activity of TH9 cells programmed by IL-7

Tumor-specific CD4⁺ T helper 9 (T_H9) cells, so-called because of their production of the cytokine interleukin-9 (IL-9), are a powerful effector T cell subset for cancer immunotherapy. We found that pretreatment of naïve CD4⁺ T cells with IL-7 further enhanced their differentiation into T_H9 cells and augmented their antitumor activity. IL-7 markedly increased the abundance of the histone acetyltransferase p300 by activating the STAT5 and PI3K-AKT-mTOR signaling pathways and promoting the acetylation of histones at the Il9 promoter. As a result, the transcriptional regulator Foxo1 was dephosphorylated and translocated to the nucleus, bound to the Il9 promoter, and induced the production of IL-9 protein. In contrast, Foxp1, which bound to the Il9 promoter in naïve CD4⁺ T cells and inhibited Il9 expression, was outcompeted for binding to the Il9 promoter by Foxo1 and translocated to the cytoplasm. Furthermore, forced expression of Foxo1 or a deficiency in Foxp1 in CD4⁺ T cells markedly increased the production of IL-9, whereas a deficiency in Foxo1 inhibited the ability of IL-7 to enhance the differentiation and antitumor activity of T_H9 cells. Thus, we identified the roles of Foxo1 as a positive regulator and Foxp1 as a negative regulator of T_H9 cell differentiation and antitumor activity, which may provide potential targets for cancer immunotherapy.

Recombinant IL-7/HGFβ hybrid cytokine separates acute graft-versus-host-disease from graft-versus-tumour activity by altering donor T cell trafficking

Given that donor T cells from a transplant contribute both the desired graft-versus-tumour (GVT) effect and detrimental graft-versus-host disease (GVHD), strategies to separate GVHD and GVT activity are a major clinical goal. We have previously demonstrated that in vivo administration of a recombinant (r)IL-7/HGFβ hybrid cytokine, consisting of interleukin-7 (IL-7, IL7) and the β-chain of hepatocyte growth factor (HGFβ), significantly inhibits the growth of cancer cells in murine tumour models. The antit-umour effect of rIL-7/HGFβ is related to a marked infiltration T cells in the tumour tissues. We have also shown that GVHD was not induced in rIL-7/HGFβ-treated T cell-depleted allogeneic haematopoietic stem cell transplantation (HSCT) recipients. We show here that, in T cell-replete allogeneic HSCT murine models, rIL-7/HGFβ attenuated acute GVHD (aGVHD), while promoting GVT activity. This was related to an alteration of donor T cell trafficking, with an increased infiltration of donor T cells into tumour tissues and the lympho-haematopoietic system but decreased number of the T cells in the GVHD target organs. Therefore, rIL-7/HGFβ may offer a new tool to alleviate aGVHD while prompting GVT, and to study the molecular regulation of T cell trafficking.

The Role of Biomarkers in the Diagnosis and Risk Stratification of Acute Graft-versus-Host Disease: A Systematic Review

Allogeneic hematopoietic cell transplantation (HCT) is an increasingly used curative modality for hematologic malignancies and other benign conditions. Attempts to reduce morbidity and mortality and improve survival in patients undergoing HCT are crucial. The ability to diagnose acute graft-versus-host disease (aGVHD) in a timely manner, or to even predict aGVHD before clinical manifestations, along with the accurate stratification of these patients, are critical steps to improve the treatment and outcomes of these patients. Many novel biomarkers that may help achieve these goals have been studied recently. This overview is intended to assist clinicians and investigators by providing a comprehensive review and analytical interpretation of the current knowledge concerning aGVHD and biomarkers likely to prove useful in diagnosis and risk stratification of this condition, along with the difficulties that hamper this approach.

Homeostatic cytokines in immune reconstitution and graft-versus-host disease

For numerous patients, allogeneic stem cell transplantation (SCT) is the only therapeutic option that could potentially cure their disease. Despite significant progress made in clinical management of allogeneic SCT, acute graft-versus-host disease (aGVHD) remains the second cause of death after disease recurrence. aGVHD is highly immunosuppressive and the adverse effect of allogeneic SCT on T cell regeneration is typically more important than the levels of immunosuppression normally seen after autologous SCT. In these patients, immune reconstitution often takes several years to occur and restoring immunocompetence after allogeneic SCT represents an important challenge, principally because clinical options are limited and current methods used to accelerate immune reconstitution are associated with increased GVHD. Interleukin-7 and IL-15 are both under clinical investigation and demonstrate the greatest potential on peripheral T cells regeneration in mice and humans. However, awareness has been raised about the use of IL-7 and IL-15 after allogeneic SCT with regards to potential adverse effects on aGVHD. In this review, we will discuss about recent progress made in lymphocyte regeneration, the critical role played by IL-7 and IL-15 in T cell homeostasis and how these cytokines could be used to improve immune reconstitution after allogeneic SCT.

IL-7 and SCF Levels Inversely Correlate with T Cell Reconstitution and Clinical Outcomes after Cord Blood Transplantation in Adults

Recovery of thymopoiesis is critical for immune reconstitution after HSCT. IL-7 and SCF are two major thymotropic cytokines. We investigated whether the kinetics of circulating levels of these cytokines might provide insight into the prolonged immunodeficiency after double umbilical cord blood transplantation (dUCBT) in adults. We examined plasma levels of IL-7 and SCF, T-cell receptor rearrangement excision circle (TREC) levels and T cell subsets in 60 adult patients undergoing dUCBT. Median levels of IL-7 increased by more than 3-fold at 4 weeks and remained elevated through 100 days after dUCBT. SCF showed a less than 2-fold increase and more protracted elevation than IL-7. IL-7 levels inversely correlated with the reconstitution of various T cell subsets but not with TRECs. SCF levels inversely correlated with reconstitution of CD4⁺T cells, especially the naïve CD4⁺CD45RA⁺ subset, and with TRECs suggesting that SCF but not IL-7 had an effect on thymic regeneration. In Cox models, elevated levels of IL-7 and SCF were associated with higher non-relapse mortality (p = 0.03 and p = 0.01) and worse overall survival (p = 0.002 and p = 0.001). Elevated IL-7 but not SCF was also associated with development of GvHD (p = 0.03). Thus, IL-7 and SCF are elevated for a prolonged period after dUCBT and persistently high levels of these cytokines may correlate with worse clinical outcomes.

Stromal-Derived Factor-1α and Interleukin-7 Treatment Improves Homeostatic Proliferation of Naïve CD4(+) T Cells after Allogeneic Stem Cell Transplantation

Graft-versus-host disease (GVHD) impairs immune reconstitution after allogeneic stem cell transplantation (allo-SCT) and effective therapies aimed at restoring T cell counts in GVHD patients have yet to be developed. During GVHD, CD4(+) T cell reconstitution is particularly affected and current models hold that GVHD insult to the peripheral lymphoid niche is responsible for this effect. Here, we show that naïve CD4(+) T cell homeostatic proliferation (HP) is lost during GVHD because of low systemic IL-7 and impaired dendritic cell (DC) regeneration. We assessed factors involved in DC differentiation and found that although fms-like tyrosine kinase 3 ligand (Flt3-L) levels were normal, stromal-derived factor-1α (SDF-1α) was diminished in the blood of GVHD mice. Unlike Flt3-L treatment, the administration of SDF-1α specifically increased CD8α(+) DC numbers and did not worsen GVHD. Importantly, CD4(+) T cell HP was enhanced only when IL-7 and SDF-1α or Flt3L were coadministered, confirming the crucial role of DCs and IL-7 in restoring CD4(+) T cell regeneration during GVHD. Altogether, our results indicate that CD8α(+) DCs are part of the peripheral niche that controls CD4(+) T cell HP and that their depletion, combined with low systemic IL-7, explains how GVHD constrains naïve CD4(+) T cell reconstitution after allo-SCT.

T cell reconstitution in allogeneic haematopoietic stem cell transplantation: prognostic significance of plasma interleukin-7

Infections and acute graft-versus-host disease (aGVHD) are major causes of treatment-related mortality and morbidity following allogeneic haematopoietic stem cell transplantation (HSCT). Both complications depend on reconstitution of the T-lymphocyte population based on donor T cells. Although it is well established that Interleukin-7 (IL-7) is a cytokine essential for de novo T cell development in the thymus and homoeostatic peripheral expansion of T cells, associations between circulating levels of IL-7 and T cell reconstitution following HSCT have not been investigated previously. We prospectively measured IL-7 levels in 81 patients undergoing myeloablative HSCT with either sibling donor or an unrelated donor. Plasma IL-7 levels peaked at day +7 post-transplant (1.3-82.4 pg/ml), at the time of maximal lymphopaenia. In multivariate analysis, peak levels of IL-7 were significantly higher in patients treated with anti-thymocyte globulin (ATG) compared with those not treated with ATG (P = 0.0079). IL-7 levels at day +7 were negatively associated with T cell counts at day +30 to +60 (at day +60: CD3(+) : β = -10.6 × 10(6) cells/l, P = 0.0030; CD8(+) : β = -8.4 × 10(6) cells/l, P = 0.061; CD4(+) : β = -2.1 × 10(6) cells/l, P = 0.062) in multivariate analyses. In adults, high IL-7 levels were associated with increased risk of grade II-IV aGVHD (OR = 5.4, P = 0.036) and reduced overall survival (P = 0.046). The present data indicate that high plasma levels of IL-7 in the early post-transplant period are predictive for slow T cell reconstitution, increased risk of aGVHD and increased mortality following HSCT.

Radiolabeled semi-quantitative RT-PCR assay for the analysis of alternative splicing of interleukin genes

Alternative splicing evolved as a very efficient way to generate proteome diversity from a limited number of genes, while at the same time modulating posttranscriptional events of gene expression-such as stability, turnover, subcellular localization, binding properties, and general activity of both mRNAs and proteins. Since the vast majority of human genes undergo alternative splicing, it comes to no surprise that interleukin genes also show extensive alternative splicing. In fact, there is a growing body of evidence indicating that alternative splicing plays a central role in modulating the pleiotropic functions of cytokines, and aberrant expression of alternatively spliced interleukin mRNAs has been linked to disease. However, while several interleukin splice variants have been described, their function is still poorly understood. This is particularly relevant, since alternatively spliced cytokine isoforms can act both as disease biomarkers and as candidate entry points for therapeutic intervention. In this chapter we describe a protocol that uses radiolabeled semi-quantitative RT-PCR to efficiently detect, analyze, and quantify alternative splicing patterns of cytokine genes.

Therapeutic activity of multiple common γ-chain cytokine inhibition in acute and chronic GVHD

The common γ chain (CD132) is a subunit of the interleukin (IL) receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. Because levels of several of these cytokines were shown to be increased in the serum of patients developing acute and chronic graft-versus-host disease (GVHD), we reasoned that inhibition of CD132 could have a profound effect on GVHD. We observed that anti-CD132 monoclonal antibody (mAb) reduced acute GVHD potently with respect to survival, production of tumor necrosis factor, interferon-γ, and IL-6, and GVHD histopathology. Anti-CD132 mAb afforded protection from GVHD partly via inhibition of granzyme B production in CD8 T cells, whereas exposure of CD8 T cells to IL-2, IL-7, IL-15, and IL-21 increased granzyme B production. Also, T cells exposed to anti-CD132 mAb displayed a more naive phenotype in microarray-based analyses and showed reduced Janus kinase 3 (JAK3) phosphorylation upon activation. Consistent with a role of JAK3 in GVHD, Jak3(-/-) T cells caused less severe GVHD. Additionally, anti-CD132 mAb treatment of established chronic GVHD reversed liver and lung fibrosis, and pulmonary dysfunction characteristic of bronchiolitis obliterans. We conclude that acute GVHD and chronic GVHD, caused by T cells activated by common γ-chain cytokines, each represent therapeutic targets for anti-CD132 mAb immunomodulation.

Nonalloreactive T cells prevent donor lymphocyte infusion-induced graft-versus-host disease by controlling microbial stimuli

In mice, graft-versus-host reactions, associated with powerful graft-versus-tumor effects, can be achieved without graft-versus-host disease (GVHD) by delayed administration of donor lymphocyte infusions (DLI) to established mixed chimeras. However, GVHD sometimes occurs after DLI in established mixed chimeric patients. In contrast to mice, in which T cell recovery from the thymus occurs prior to DLI administration, human T cell reconstitution following T cell-depleted hematopoietic cell transplantation is slow, resulting in lymphopenia at the time of DLI. We demonstrate in this study that T cell lymphopenia is an independent risk factor for GVHD following DLI in the absence of known inflammatory stimuli. DLI-induced GVHD was prevented in lymphopenic recipients by prior administration of a small number of nonalloreactive polyclonal T cells, insufficient to prevent lymphopenia-associated expansion of subsequently administered T cells, through a regulatory T cell-independent mechanism. GVHD was not inhibited by T cells with irrelevant specificity. Moreover, administration of antibiotics reduced the severity of GVHD in lymphopenic hosts. Accumulation of DLI-derived effector T cells and host hematopoietic cell elimination were markedly diminished by regulatory T cell-depleted, nonalloreactive T cells. Finally, thymectomized mixed chimeras showed increased GVHD following delayed DLI. Collectively, our data demonstrate that in the absence of known conditioning-induced inflammatory stimuli, T cell lymphopenia is a risk factor for GVHD in mixed chimeras receiving delayed DLI. Our data suggest that the predisposition to GVHD can at least in part be explained by the presence of occult inflammatory stimuli due to the absence of T cells to control microbial infections.

TGF-β sensitivity restrains CD8+ T cell homeostatic proliferation by enforcing sensitivity to IL-7 and IL-15

The pleiotropic cytokine TGF-β has been implicated in the regulation of numerous aspects of the immune response, including naïve T cell homeostasis. Previous studies found that impairing TGF-β responsiveness (through expression of a dominant-negative TGF-β RII [DNRII] transgene) leads to accumulation of memory phenotype CD8 T cells, and it was proposed that this resulted from enhanced IL-15 sensitivity. Here we show naïve DNRII CD8 T cells exhibit enhanced lymphopenia-driven proliferation and generation of “homeostatic” memory cells. However, this enhanced response occurred in the absence of IL-15 and, unexpectedly, even in the combined absence of IL-7 and IL-15, which were thought essential for CD8 T cell homeostatic expansion. DNRII transgenic CD8 T cells still require access to self Class I MHC for homeostatic proliferation, arguing against generalized dysregulation of homeostatic cues. These findings suggest TGF-β responsiveness is critical for enforcing sensitivity to homeostatic cytokines that limit maintenance and composition of the CD8 T cell pool. (154 words).

IL-7 in human health and disease

IL-7 plays many essential roles in human health and disease. Congenital deficiencies in IL-7 signaling result in profound immunodeficiency, polymorphisms in IL7Rα modulate susceptibility to autoimmune disease, and acquired somatic activating mutations in IL7Rα contribute to neoplastic transformation in B cell and T cell leukemia. In response to lymphopenia, IL-7 accumulates to supranormal levels, which alters T cell homeostasis by augmenting T cell reactivity toward self and cognate antigens. This physiologic response is now routinely exploited to improve the efficacy of adoptive cell therapies for cancer. Clinical trials of recombinant IL-7 have demonstrated safety and potent immunorestorative effects, and current studies are investigating whether rhIL-7 therapy can improve outcomes in chronic viral infection and in the context of cancer immunotherapies. Building upon the large fund of knowledge regarding the basic biology of IL-7, this review will discuss the many and varied roles of IL-7 in human health and disease.

T-lymphocyte recovery and function after cord blood transplantation

The Szabolcs laboratory is focused on understanding the biology of donor-derived cellular immunity in recipients of allogeneic hematopoietic cell transplantation that can be translated into new immunotherapy strategies. To this end, we are focused on developing novel laboratory approaches to analyze and augment immune recovery for high risk patient cohorts without increasing graft-versus-host disease. Much of our work has focused on unrelated cord blood transplantation as the dominant clinical scenario and laboratory model. Our overarching goal is to minimize transplant-related mortality and morbidity and render HLA-mismatched unrelated cord blood transplant, a widely accepted safe cellular therapy. Donor leukocyte infusions in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Our laboratory has a major focus toward ex vivo expansion of cord blood T cells with anti-apoptotic cytokines and CD3/CD28 co-stimulatory beads. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. These findings offer a major step in fulfilling critical biological requirements to quickly generate a cellular product ex vivo, using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

The immunobiology of cord blood transplantation

Despite significant recent advances in the applicability and outcome following unrelated cord blood transplantation (UCBT), infections remain a major cause of mortality associated with poor immune recovery in the first 6 months after UCBT. Enhanced immune reconstitution not only could improve survival by reduced transplant related mortality, but may also favorably impact on relapse incidence by improved graft-versus-leukemia effects. This review will summarize our current understanding of the biology of immune recovery post-UCBT with an emphasis on adaptive T cell dependent immunity. New efforts to boost immunity will be also highlighted including our own laboratory, where ex vivo T cell expansion is pursued towards adoptive immunotherapy.

Interleukin-7 permits Th1/Tc1 maturation and promotes ex vivo expansion of cord blood T cells: a critical step toward adoptive immunotherapy after cord blood transplantation

Donor leukocyte infusions (DLI) in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Despite significant advances in applicability, DLI has not been available for single-unit recipients of unrelated cord blood transplant. Ex vivo expansion of cord blood T cells can be achieved with interleukin (IL)-2 and CD3/CD28 costimulatory beads. However, significant apoptosis occurs in proliferating T cells, diminishing the yield and skewing the CD4/CD8 ratio in the T-cell population, jeopardizing the potential efficacy of DLI. In this study, we show that interleukin (IL)-7 not only reduces apoptosis of activated T lymphocytes and enhances their proliferation but also promotes functional maturation, leading to secretion of IFN-gamma and other key cytokines. Recognizing that infused T lymphocytes will need to meet microbial antigens in secondary lymphoid organs to generate effectors, we also show that expansion with IL-7 promotes the preservation of a polyclonal broad T-cell receptor repertoire and a surface phenotype that favors lymph node homing. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells, indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. Taken together, our findings offer a major step in fulfilling critical numerical and biological requirements to quickly generate a DLI product ex vivo using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

Modulating T-cell homeostasis with IL-7: preclinical and clinical studies

Interleukin-7 (IL-7) is required for the development and survival of T cells and plays a critical role in modulating T-cell homeostasis. This review will address current understanding of IL-7 biology, review recent clinical experiences and discuss potential future clinical applications of IL-7, or IL-7 blockade, in the setting of disease.

Interleukin-7 receptor-alpha gene polymorphisms in bone marrow transplant recipients

Graft-versus-host disease is the main complication after hematopoietic stem cells transplantation (HSCT). Non-HLA genotypes, such as cytokines, have been investigated for their potential roles in the occurrence and severity of GVHD as well as for their contribution to overall transplant-related mortality and survival. IL-7 which is secreted by bone marrow stromal cells plays an important role in the development and survival of T cells. Its effect is mediated via interleukin 7 receptor (IL7R). This study investigates the possible links between IL-7alphaR single nucleotide polymorphisms (+510 C/T, +1237 A/G, +2087 T/C and +3110A/G) and transplant outcomes among 116 recipients of HSCT. Genotypes were determined using polymerase chain reaction-sequence-specific primers. No significant differences were observed between the genotypic distributions of IL-7alphaR polymorphisms and incidence of acute or chronic graft versus host disease. Additional studies with larger sample are necessary to further define the influence of IL-7alphaR on the immune response after bone marrow transplantation.

Immune reconstitution and implications for immunotherapy following haematopoietic stem cell transplantation

Recovery of a fully functional immune system is a slow and often incomplete process following allogeneic stem cell transplantation. While innate immunity reconstitutes quickly, adaptive B- and especially T-cell lymphopoeisis may be compromised for years following transplantation. In large part, these immune system deficits are due to the decrease, or even absence, of thymopoiesis following transplantation. Thereby, T-cell reconstitution initially relies upon expansion of mature donor T cells; a proliferation driven by high cytokine levels and the presence of allo-reactive antigens. This peripheral mechanism of T-cell generation may have important clinical consequences. By expanding tumouricidal T cells, it may provide a venue to enhance T-cellular immunotherapy following transplantation. Alternatively, decreased thymic function may impair long-term anti-tumour immunity and increase the likelihood of graft-versus-host disease.

Association of serum interleukin-7 levels with the development of acute graft-versus-host disease

PURPOSE

Morbidity from acute graft-versus-host disease (GVHD) limits the success of allogeneic hematopoietic stem-cell transplantation (HSCT) to treat malignancy. Interleukin-7 (IL-7), the principal homeostatic cytokine for T cells, is required for acute GVHD in murine models. In contrast to inflammatory cytokines (eg, IL-2, tumor necrosis factor alpha), IL-7 has not been studied extensively in the clinical transplant setting relative to its relationship with acute GVHD.

PATIENTS AND METHODS

We evaluated the association of serum IL-7 levels with acute GVHD in 31 patients who were uniformly treated in a prospective clinical trial with reduced-intensity allogeneic HSCT from human leukocyte antigen-identical siblings. GVHD prophylaxis consisted of cyclosporine and methotrexate. Serum IL-7 levels and lymphocyte populations were determined at enrollment, the day of transplantation before the allograft infusion, and at specified intervals through 12 months post-transplantation.

RESULTS

As expected, IL-7 levels were inversely correlated with T-cell populations (P < .00001). Acute GVHD was significantly associated with higher IL-7 levels at day +7 (P = .01) and day +14 (P = .00003) post-transplantation as well as with the allograft CD34(+) cell dose (P = .01). IL-7 levels at day +14 also correlated with the severity of acute GVHD (P < .0001). In logistic regression models, these factors were highly sensitive (up to 86%) and specific (100%) for classifying whether patients developed acute GVHD.

CONCLUSION

These data support preclinical observations that IL-7 plays a critical role in inducing acute GVHD and provide a rational basis for novel approaches to prevent and treat acute GVHD through modulation of the IL-7 pathway.

Immunomodulation and pharmacological strategies in the treatment of graft-versus-host disease

BACKGROUND

Allogeneic hematopoietic stem cell transplantation offers great promise for the treatment of a variety of diseases including malignancies and other diseases of hematopoietic origin. However, morbidity and mortality due to graft-versus-host disease (GVHD) remain a major barrier to its application.

OBJECTIVE

This review will provide an overview of the pathophysiology of GVHD and discuss the recent advances in GVHD management in both preclinical and clinical studies.

METHODS

An extensive literature search on PubMed from 1995 to 2008 was performed.

RESULTS/CONCLUSION

There has been much progress in our understanding of GVHD and finding new means to control acute GVHD. While these approaches hold promise, as yet none has been able to replace the standard methods we may use routinely to decrease the incidence of the condition.