Donor T-cell production of RANTES significantly contributes to the development of idiopathic pneumonia syndrome after allogeneic stem cell transplantation

Prevention of non-infectious pulmonary complications after intra-bone marrow stem cell transplantation in mice

Non-infectious pulmonary complications including idiopathic pneumonia syndrome (IPS) and bronchiolitis obliterans syndrome (BOS), which are clinical and diagnostic manifestations of lung chronic graft-versus-host disease (GVHD), cause significant mortality after allogeneic stem cell transplantation (SCT). Increasing evidence suggests that alloantigen reactions in lung tissue play a central role in the pathogenesis of IPS and BOS; however, the mechanism is not fully understood. Several clinical and experimental studies have reported that intra-bone marrow (IBM)-SCT provides high rates of engraftment and is associated with a low incidence of acute GVHD. In the present study, allogeneic SCT was conducted in mouse models of IPS and BOS, to compare intravenous (IV)-SCT with IBM-SCT. Allogeneic IBM-SCT improved the clinical and pathological outcomes of pulmonary complications compared to those of IV-SCT. The mechanisms underlying the reductions in pulmonary complications in IBM-SCT mice were explored. The infiltrating lung cells were mainly CD11b+ myeloid and CD3+ T cells, in the same proportions as in transplanted donor cells. In an in vivo bioluminescence imaging, a higher proportion of injected donor cells was detected in the lung during the early phase (1 h after IV-SCT) than after IBM-SCT (16.7 ± 1.1 vs. 3.1 ± 0.7 × 10⁵ photons/s/animal, IV-SCT vs. IBM-SCT, P = 1.90 × 10⁻¹⁰). In the late phase (5 days) after SCT, there were also significantly more donor cells in the lung after IV-SCT than after IBM-SCT or allogeneic-SCT (508.5 ± 66.1 vs. 160.1 ± 61.9 × 10⁶ photons/s/animal, IV-SCT vs. IBM-SCT, P = 0.001), suggesting that the allogeneic reaction induces sustained donor cell infiltration in the lung during the late phase. These results demonstrated that IBM-SCT is capable of reducing injected donor cells in the lung; IBM-SCT decreases donor cell infiltration. IBM-SCT therefore represents a promising transplantation strategy for reducing pulmonary complications, by suppressing the first step in the pathophysiology of chronic GVHD.

Vitamin D Supplementation: Association With Serum Cytokines in Pediatric Hematopoietic Stem Cell Transplantation

Vitamin D deficiency is prevalent in pediatric patients presenting for hematopoietic stem cell transplantation (HSCT) and has been linked to poor clinical outcomes. Using the data from a randomized control trial, in this paper we explore the effects of vitamin D supplementation on circulating cytokine levels during pediatric HSCT (www.clinicaltrials.gov as NCT03176849). A total of 41 children, 20 received Stoss therapy and 21 children received standard of care vitamin D supplementation. Levels of 25(OH)D and 20 cytokines were assessed at baseline and day +30. Significantly (P < 0.05) higher levels of mostly proinflammatory cytokines, FGF, GCSF, TNFα, IL-2, IL-6, IP10 were detected pre-transplant for patients with low compared to those with normal vitamin D levels. In sex stratified models that compare changes in cytokines between Stoss vs. standard of care, females in the Stoss group show greater changes in mostly pro -inflammatory cytokines- IP-10 (P = 0.0047), MIG (P = 0.009), and RANTES (P = 0.0047), IL-2R (P = 0.07) and IL-6(P = 0.069). Despite a small sample size, these findings suggest vitamin D deficiency affects the pre-transplant cytokine milieu and higher doses of vitamin D (Stoss therapy) appears to influence proinflammatory cytokine responses in a sex specific manner during pediatric HSCT. Larger clinical trials are warranted to validate these results.

Pulmonary Complications of Pediatric Hematopoietic Cell Transplantation. A National Institutes of Health Workshop Summary

Approximately 2,500 pediatric hematopoietic cell transplants (HCTs), most of which are allogeneic, are performed annually in the United States for life-threatening malignant and nonmalignant conditions. Although HCT is undertaken with curative intent, post-HCT complications limit successful outcomes, with pulmonary dysfunction representing the leading cause of nonrelapse mortality. To better understand, predict, prevent, and/or treat pulmonary complications after HCT, a multidisciplinary group of 33 experts met in a 2-day National Institutes of Health Workshop to identify knowledge gaps and research strategies most likely to improve outcomes. This summary of Workshop deliberations outlines the consensus focus areas for future research.

Human multipotent adult progenitor cells effectively reduce graft-vs-host disease while preserving graft-vs-leukemia activity

Graft‐vs‐host disease (GvHD) limits successful outcomes following allogeneic blood and marrow transplantation (allo‐BMT). We examined whether the administration of human, bone marrow‐derived, multipotent adult progenitor cells (MAPCs™) could regulate experimental GvHD. The immunoregulatory capacity of MAPC cells was evaluated in vivo using established murine GvHD models. Injection of MAPC cells on day +1 (D1) and +4 (D4) significantly reduced T‐cell expansion and the numbers of donor‐derived, Tumor Necrosis Factor Alpha (TNFα) and Interferon Gamma (IFNγ)‐producing, CD4+ and CD8+ cells by D10 compared with untreated controls. These findings were associated with reductions in serum levels of TNFα and IFNγ, intestinal and hepatic inflammation and systemic GvHD as measured by survival and clinical score. Biodistribution studies showed that MAPC cells tracked from the lung and to the liver, spleen, and mesenteric nodes within 24 hours after injection. MAPC cells inhibited mouse T‐cell proliferation in vitro and this effect was associated with reduced T‐cell activation and inflammatory cytokine secretion and robust increases in the concentrations of Prostaglandin E2 (PGE2) and Transforming Growth Factor Beta (TGFβ). Indomethacin and E‐prostanoid 2 (EP2) receptor antagonism both reversed while EP2 agonism restored MAPC cell‐mediated in vitro T‐cell suppression, confirming the role for PGE2. Furthermore, cyclo‐oxygenase inhibition following allo‐BMT abrogated the protective effects of MAPC cells. Importantly, MAPC cells had no effect on the generation cytotoxic T lymphocyte activity in vitro, and the administration of MAPC cells in the setting of leukemic challenge resulted in superior leukemia‐free survival. Collectively, these data provide valuable information regarding the biodistribution and regulatory capacity of MAPC cells, which may inform future clinical trial design.

Compound A Increases Cell Infiltration in Target Organs of Acute Graft-versus-Host Disease (aGVHD) in a Mouse Model

Systemic steroids are used to treat acute graft-versus-host disease (aGVHD) caused by allogenic bone marrow transplantation (allo-BMT); however, their prolonged use results in complications. Hence, new agents for treating aGVHD are required. Recently, a new compound A (CpdA), with anti-inflammatory activity and reduced side effects compared to steroids, has been identified. Here, we aimed to determine whether CpdA can improve the outcome of aGVHD when administered after transplantation in a mouse model (C57BL/6 in B6D2F1). After conditioning with 9Gy total body irradiation, mice were infused with bone marrow (BM) cells and splenocytes from either syngeneic (B6D2F1) or allogeneic (C57BL/6) donors. The animals were subsequently treated (3 days/week) with 7.5 mg/kg CpdA from day +15 to day +28; the controls received 0.9% NaCl. Thereafter, the incidence and severity of aGVHD in aGVHD target organs were analyzed. Survival and clinical scores did not differ significantly; however, CpdA-treated animals showed high cell infiltration in the target organs. In bulk mixed lymphocyte reactions, CpdA treatment reduced the cell proliferation and expression of inflammatory cytokines and chemokines compared to controls, whereas levels of TNF, IL-23, chemokines, and chemokine receptors increased. CpdA significantly reduced proliferation in vitro but increased T cell infiltration in target organs.

Endothelial cell function and endothelial-related disorders following haematopoietic cell transplantation

Use of haematopoietic cell transplantation (HCT) in the treatment of haematologic and neoplastic diseases may lead to life-threatening complications that cause substantial morbidity and mortality if untreated. In addition to patient- and disease-related factors, toxicity associated with HCT puts patients at risk for complications that share a similar pathophysiology involving endothelial cells (ECs). Normally, the endothelium plays a role in maintaining homeostasis, including regulation of coagulation, vascular tone, permeability and inflammatory processes. When activated, ECs acquire cellular features that may lead to phenotypic changes that induce procoagulant, pro-inflammatory and pro-apoptotic mediators leading to EC dysfunction and damage. Elevated levels of coagulation factors, cytokines and adhesion molecules are indicative of endothelial dysfunction, and endothelial damage may lead to clinical signs and symptoms of pathological post-HCT conditions, including veno-occlusive disease/sinusoidal obstruction syndrome, graft-versus-host disease, transplant-associated thrombotic microangiopathy and idiopathic pneumonia syndrome/diffuse alveolar haemorrhage. The endothelium represents a rational target for preventing and treating HCT complications arising from EC dysfunction and damage. Additionally, markers of endothelial damage may be useful in improving diagnosis of HCT-related complications and monitoring treatment effect. Continued research to effectively manage EC activation, injury and dysfunction may be important in improving patient outcomes after HCT.

The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature.

Murine chronic graft-versus-host disease proteome profiling discovers CCL15 as a novel biomarker in patients

Improved diagnostic and treatment methods are needed for chronic graft-versus-host disease (cGVHD), the leading cause of late nonrelapse mortality (NRM) in long-term survivors of allogenic hematopoietic cell transplantation. Validated biomarkers that facilitate disease diagnosis and classification generally are lacking in cGVHD. Here, we conducted whole serum proteomics analysis of a well-established murine multiorgan system cGVHD model. We discovered 4 upregulated proteins during cGVHD that are targetable by genetic ablation or blocking antibodies, including the RAS and JUN kinase activator, CRKL, and CXCL7, CCL8, and CCL9 chemokines. Donor T cells lacking CRK/CRKL prevented the generation of cGVHD, germinal center reactions, and macrophage infiltration seen with wild-type T cells. Whereas antibody blockade of CCL8 or CXCL7 was ineffective in treating cGVHD, CCL9 blockade reversed cGVHD clinical manifestations, histopathological changes, and immunopathological hallmarks. Mechanistically, elevated CCL9 expression was present predominantly in vascular smooth muscle cells and uniquely seen in cGVHD mice. Plasma concentrations of CCL15, the human homolog of mouse CCL9, were elevated in a previously published cohort of 211 cGVHD patients compared with controls and associated with NRM. In a cohort of 792 patients, CCL15 measured at day +100 could not predict cGVHD occurring within the next 3 months with clinically relevant sensitivity/specificity. Our findings demonstrate for the first time the utility of preclinical proteomics screening to identify potential new targets for cGVHD and specifically CCL15 as a diagnosis marker for cGVHD. These data warrant prospective biomarker validation studies.

Etanercept and Corticosteroid Therapy for the Treatment of Late-Onset Idiopathic Pneumonia Syndrome

Idiopathic pneumonia syndrome (IPS) is a complication of allogeneic hematopoietic stem cell transplantation (HSCT) that typically occurs within the first 100 days after transplantation. Tumor necrosis factor α (TNF-α) has been shown to be a key mediator of IPS, and the TNF-α binding protein etanercept appeared to improve IPS outcomes in small retrospective and prospective studies. IPS also has been observed to occur later (>100 days) after HSCT; however, little is known about the disease course and whether a TNF-α-based therapeutic strategy is efficacious in these patients. To address this question, we performed a retrospective analysis of 23 patients who underwent HSCT between 2004 and 2016 at our institution who developed late-onset IPS and received treatment with etanercept and high-dose corticosteroids (CS). Ten of the 23 patients (43%) attained a complete clinical response to etanercept and CS. Responses were significantly more likely to occur in patients who did not require positive pressure ventilation at the time of diagnosis. Those who responded experienced a durable survival benefit, with a 2-year overall survival of 67%. In the 13 patients (57%) who did not respond to etanercept and CS, the median overall survival was only 13 days (range, 1 to 60 days). The difference in 2-year overall survival between responders and nonresponders was statistically significant (67% versus 0%; P < .001). These results indicate that late-onset IPS carries high mortality, but that treatment with etanercept and CS has activity and can result in long-term survival in some patients. Prompt diagnosis and early institution of therapy before the need for advanced respiratory support is critical for maximizing responses.

A call to arms: a critical need for interventions to limit pulmonary toxicity in the stem cell transplantation patient population

Noninfectious pulmonary toxicity after allogeneic hematopoietic stem cell transplantation (allo-HSCT) causes significant morbidity and mortality. Main presentations are idiopathic pneumonia syndrome (IPS) in the acute setting and bronchiolitis obliterans syndrome (BOS) and cryptogenic organizing pneumonia (COP) at later time point. While COP responds well to corticosteroids, IPS and BOS often are treatment refractory. IPS, in most cases, is rapidly fatal, whereas BOS progresses over time, resulting in chronic respiratory failure, impaired quality of life, and eventually, death. Standard second-line treatments are currently lacking, and current approaches, such as augmented T cell-directed immunosuppression, B cell depletion, TNF blockade, extracorporeal photopheresis, and tyroskine kinase inhibitor therapy, are unsatisfactory with responses in only a subset of patients. Better understanding of underlying pathophysiology hopefully results in the identification of future targets for preventive and therapeutic strategies along with an emphasis on currently underutilized rehabilitative and supportive measures.

Preventive azithromycin treatment reduces noninfectious lung injury and acute graft-versus-host disease in a murine model of allogeneic hematopoietic cell transplantation

Noninfectious lung injury and acute graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) are associated with significant morbidity and mortality. Azithromycin is widely used in allogeneic HCT recipients for pulmonary chronic GVHD, although current data appear controversial. We induced GVHD and noninfectious lung injury in lethally irradiated B6D2F1 mice by transplanting bone marrow and splenic T cells from allogeneic C57BL/6 mice. Experimental groups were treated with oral azithromycin starting on day 14 until the end of week 6 or week 14 after transplantation. Azithromycin treatment resulted in improved survival and decreased lung injury; the latter characterized by improved pulmonary function, reduced peribronchial and perivascular inflammatory cell infiltrates along with diminished collagen deposition, and a decrease in lung cytokine and chemokine expression. Azithromycin also improved intestinal GVHD but did not affect liver GVHD at week 6 early after transplantation. At week 14, azithromycin decreased liver GVHD but had no effect on intestinal GVHD. In vitro, allogeneic antigen-presenting cell (APC)- dependent T cell proliferation and cytokine production were suppressed by azithromycin and inversely correlated with relative regulatory T cell (Treg) expansion, whereas no effect was seen when T cell proliferation occurred APC independently through CD3/CD28-stimulation. Further, azithromycin reduced alloreactive T cell expansion but increased Treg expansion in vivo with corresponding downregulation of MHC II on CD11c(+) dendritic cells. These results demonstrate that preventive administration of azithromycin can reduce the severity of acute GVHD and noninfectious lung injury after allo-HCT, supporting further investigation in clinical trials.

RANTES polymorphisms and the risk of graft-versus-host disease in human leukocyte antigen-matched sibling allogeneic hematopoietic stem cell transplantation

We investigated the association between RANTES (regulated upon activation, normal T cell expressed and secreted) polymorphisms and clinical outcomes in patients treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Three RANTES gene polymorphisms, i.e., -403G/A (rs2107538), -28C/G (rs2280788) and In1.1T/C (rs2280789), were genotyped, and the effects of the genotypes and haplotypes of RANTES on clinical outcomes were analyzed. The competing risk regression analysis was used to investigate the relationship between the polymorphisms and the cumulative risk of graft-versus-host disease (GVHD). An AGC haplotype in a recessive model showed significant harmful effects on the cumulative risk of acute GVHD and relapse-free survival (adjusted hazard ratios 2.42 and 2.71, 95% confidence intervals 1.29-4.55 and 1.30-5.64; p = 0.018 and 0.024, respectively), whereas a GCT haplotype did not. RANTES polymorphisms were not significantly associated with overall survival and the risk of chronic GVHD. This study suggests that RANTES polymorphisms might be associated with the occurrence of acute GVHD rather than of chronic GVHD and also of relapse-free survival in the patients treated with allo-HSCT. Further larger prospective investigations are needed to establish the role of RANTES polymorphisms in patients treated with allo-HSCT.

The role of chemokines in mediating graft versus host disease: opportunities for novel therapeutics

Bone marrow transplantation (BMT) is the current therapy of choice for several malignancies and severe autoimmune diseases. Graft versus host disease (GVHD) is the major complication associated with BMT. T lymphocytes and other leukocytes migrate into target organs during GVHD, become activated and mediate tissue damage. Chemokines are well known inducers of leukocyte trafficking and activation and contribute to the pathogenesis of GVHD. Here, we review the major animal models used to study GVHD and the role of chemokines in mediating tissue damage in these models. The role of these molecules in promoting potential beneficial effects of the graft, especially graft versus leukemia, is also discussed. Finally, the various pharmacological strategies to block the chemokine system or downstream signaling events in the context of GVHD are discussed.

An official American Thoracic Society research statement: noninfectious lung injury after hematopoietic stem cell transplantation: idiopathic pneumonia syndrome

RATIONALE

Acute lung dysfunction of noninfectious etiology, known as idiopathic pneumonia syndrome (IPS), is a severe complication following hematopoietic stem cell transplantation (HSCT). Several mouse models have been recently developed to determine the underlying causes of IPS. A cohesive interpretation of experimental data and their relationship to the findings of clinical research studies in humans is needed to better understand the basis for current and future clinical trials for the prevention/treatment of IPS.

OBJECTIVES

Our goal was to perform a comprehensive review of the preclinical (i.e., murine models) and clinical research on IPS.

METHODS

An ATS committee performed PubMed and OVID searches for published, peer-reviewed articles using the keywords "idiopathic pneumonia syndrome" or "lung injury" or "pulmonary complications" AND "bone marrow transplant" or "hematopoietic stem cell transplant." No specific inclusion or exclusion criteria were determined a priori for this review.

MEASUREMENTS AND MAIN RESULTS

Experimental models that reproduce the various patterns of lung injury observed after HSCT have identified that both soluble and cellular inflammatory mediators contribute to the inflammation engendered during the development of IPS. To date, 10 preclinical murine models of the IPS spectrum have been established using various donor and host strain combinations used to study graft-versus-host disease (GVHD). This, as well as the demonstrated T cell dependency of IPS development in these models, supports the concept that the lung is a target of immune-mediated attack after HSCT. The most developed therapeutic strategy for IPS involves blocking TNF signaling with etanercept, which is currently being evaluated in clinical trials.

CONCLUSIONS

IPS remains a frequently fatal complication that limits the broader use of allogeneic HSCT as a successful treatment modality. Faced with the clinical syndrome of IPS, one can categorize the disease entity with the appropriate tools, although cases of unclassifiable IPS will remain. Significant research efforts have resulted in a paradigm shift away from identifying noninfectious lung injury after HSCT solely as an idiopathic clinical syndrome and toward understanding IPS as a process involving aspects of both the adaptive and the innate immune response. Importantly, new laboratory insights are currently being translated to the clinic and will likely prove important to the development of future strategies to prevent or treat this serious disorder.

Steroid treatment alters adhesion molecule and chemokine expression in experimental acute graft-vs.-host disease of the intestinal tract

OBJECTIVE

Acute graft-vs.-host disease (aGVHD) is a major complication after allogeneic bone marrow transplantation (allo-BMT) that is characterized by high morbidity and mortality. Systemic treatment with steroids has been the mainstay of first-line therapy of aGVHD, although controlled experimental data in this context are limited.

MATERIALS AND METHODS

Using a haploidentical murine BMT model, steroid effects on hepatic and intestinal inflammation during aGVHD have been investigated. Lethally irradiated B6D2F1 mice received bone marrow cells and splenocytes from either syngeneic (B6D2F1) or allogeneic (C57BL/6) donors.

RESULTS

Intraperitoneal administration of prednisolone (2 mg/kg body weight every day) early after onset of GVHD from day +10 until day +42 resulted in reduced clinical GVHD severity and improved survival of allogeneic recipients. Although the liver was barely affected by prednisolone treatment, aGVHD-related histopathologic injury of the gastrointestinal tract was strongly reduced in association with diminished expression of interferon-γ, tumor necrosis factor, CXCL 9-11, CCL2-3, mucosal addressin cell adhesion molecule-1, and intercellular adhesion molecule-1. Prednisolone-induced reduction of adhesion molecule expression in the gut manifested earlier than seen for cytokines or chemokines. Interestingly, when starting steroid treatment on day +28, the course of GVHD was unchanged and no major differences in cyto- or chemokine expression in gastrointestinal tract or liver on day +42 were seen.

CONCLUSIONS

When started early after GVHD onset, prednisolone-related beneficial effects can affect aGVHD target organs differently, involving divergent regulation of inflammation and leukocyte migration. Specifically, a change in adhesion properties between leukocytes and endothelial cells in the gastrointestinal tract may be one of the initial steps in a cascade of steroid-related aGVHD-attenuating events.

The chemokine system: a possible therapeutic target in acute graft versus host disease

Allogeneic hematopoetic stem cell transplantation often presents the only chance for cure in a number of malignant and nonmalignant hematologic diseases. However, its beneficial effects are counterweighed by the development of potentially lethal complications, most importantly the development of acute and chronic graft-vs.-host disease (GVHD). Alloantigen-reactive immune responses mediate injury and destruction of GVHD target organs, including the gastrointestinal tract, the liver, the skin, and the lung. Donor leukocyte infiltration into the respective tissues is orchestrated by interactions between chemokines and chemokine receptors, which will be reviewed using a basic science - clinical comparative approach.

Preventive usage of broad spectrum chemokine inhibitor NR58-3.14.3 reduces the severity of pulmonary and hepatic graft-versus-host disease

Pulmonary graft-versus-host disease (pGVHD) is a major complication after allogeneic bone marrow transplantation (BMT), which involves donor leukocyte migration into the lung along chemokine gradients, leading to pulmonary dysfunction and respiratory insufficiency. As broad spectrum chemokine inhibitor (BSCI) NR58-3.14.3 suppresses leukocyte migration in response to various chemokines, including CCL2, CCL3, CCL5, we investigated the effects of NR58-3.14.3 on the evolution of pGVHD. Lethally irradiated B6D2F1 mice received BMT from syngeneic (B6D2F1) or allogeneic (C57BL/6) donors, and animals were treated with either NR58-3.14.3 or vehicle control from day -1 to day +14. At week 6, in allogeneic recipients that received BSCI, inflammatory cell infiltrates in the lung were decreased, and reduced histopathologic changes translated into improved pulmonary function when compared to allo-controls. Acute GVHD of the liver was also diminished, whereas no differences were seen in the gut. Alloantigen-dependent splenic T cell expansion and systemic TNF-alpha and IFN-gamma levels were comparable in NR58-3.14.3-treated animals and allo-controls. No suppressive effect of NR58-3.14.3 on CTL cytotoxicity was found, and diminished cellular infiltrates in lung and liver were most likely due to decreased migration of mononuclear cells. Therefore, novel approaches involving BSCIs may provide a promising tool in the management of pGVHD.

Pulmonary function changes in experimental graft-versus-host disease of the lung

Pulmonary graft-versus-host disease (p-GVHD) is a serious complication after allogeneic stem cell transplantation (allo-SCT) of high morbidity and high mortality. We characterized breathing patterns and pulmonary function changes in correlation to lung histopathology and survival by using a well-established murine model of p-GVHD. Lethally irradiated B6D2F1 mice received SCT from either syngeneic B6D2F1 or allogeneic C57BL/6 animals. Within 6 weeks, severe p-GVHD developed in allogeneic recipients characterized by progressive interstitial, alveolar, peribronchial, and periluminal inflammatory cell infiltration, whereas in syngeneic recipients lung histology remained normal. Allogeneic recipients demonstrated decreased minute ventilation (MV), reduced peak inspiratory and expiratory flow rates as early as 1 week after SCT. In addition, allo-SCT resulted in restrictive pulmonary function changes as early as 7 days after transplantation and in progressive airflow obstruction within 6 weeks. Decreased breathing abilities and pulmonary function changes of allogeneic recipients were associated with increased mortality and the severity of acute graft-versus-host disease (aGVHD). These findings show that p-GVHD can be characterized by changes in pulmonary function and functional respiratory insufficiency. Furthermore, our data strengthen the understanding, that the lung is a critical target organ of aGVHD.

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.

A role for TNF receptor type II in leukocyte infiltration into the lung during experimental idiopathic pneumonia syndrome

Idiopathic pneumonia syndrome (IPS) is a frequently fatal complication following allogeneic stem cell transplantation (allo-SCT). Experimental models have revealed that TNF-alpha contributes to pulmonary vascular endothelial cell (EC) apoptosis, and modulates the infiltration of donor leukocytes into the lung parenchyma. The inflammatory effects of TNF-alpha are mediated by signaling through the type I (TNFRI) or type II (TNFRII) TNF receptors. We investigated the relative contribution of TNFRI and TNFRII to leukocyte infiltration into the lung following allo-SCT by using established murine models. Wild-type (wt) B6 mice or B6 animals deficient in either TNFRI or TNFRII were lethally irradiated and received SCT from allogeneic (LP/J) or syngeneic (B6) donors. At week 5 following SCT, the severity of IPS was significantly reduced in TNFRII-/- recipients compared to wt controls, but no effect was observed in TNFRI-/- animals. Bronchoalveolar lavage fluid (BALF) levels of RANTES and pulmonary ICAM-1 expression in TNFRII-/- recipients were also reduced, and correlated with a reduction of CD8(+) cells in the lung. Pulmonary inflammation was also decreased in TNFRII-/- mice using an isolated MHC class I disparate model (bm1 --> B6), and in bm1 wt mice transplanted with B6 TNF-alpha-/- donor cells. Collectively, these data demonstrate a role for TNF-alpha signaling through TNFRII in leukocyte infiltration into the lung following allo-SCT, and suggest that disruption of the TNF-alpha:TNFRII pathway may be an effective tool to prevent or treat IPS.

CCR1/CCL5 (RANTES) receptor-ligand interactions modulate allogeneic T-cell responses and graft-versus-host disease following stem-cell transplantation

Acute graft-versus-host disease (GVHD) and leukemic relapse are serious complications of allogeneic stem-cell transplantation (SCT). Recruitment of activated T cells to host target tissues or sites of leukemic infiltration (graft-versus-leukemia [GVL]) is likely mediated by chemokine receptor-ligand interactions. We examined the contribution of donor cell CCR1 expression to the development of GVHD and GVL using a well-established murine SCT model (B6 --> B6D2F1) and CCR1-deficient mice (CCR1(-/-)). Allo-SCT with CCR1(-/-) donor cells significantly reduced systemic and target organ GVHD severity, and CCR1 expression on both T cells and accessory cells contributed to GVHD mortality. Significant GVL activity was preserved following CCR1(-/-) SCT, but the survival advantage diminished with increasing tumor burden. We then explored the effects of CCR1 expression on allo-specific T-cell responses. Although cytolytic effector function was maintained on a per-cell basis, T-cell proliferation and IFNgamma secretion were significantly reduced both in vivo and in vitro. T-cell function was partially dependent on interactions between CCR1 and CCL5. Collectively, these data demonstrate that CCR1 expression on donor cells contributes to the development of both GVHD and GVL, and suggest that CCR1/CCL5 receptor-ligand interactions modulate allo-specific T-cell responses occurring in this context.

IFNgamma differentially controls the development of idiopathic pneumonia syndrome and GVHD of the gastrointestinal tract

Although proinflammatory cytokines are key mediators of tissue damage during graft-versus-host disease (GVHD), IFNgamma has previously been attributed with both protective and pathogenic effects. We have resolved this paradox by using wild-type (wt), IFNgamma(-/-), and IFNgammaR(-/-) mice as donors or recipients in well-described models of allogeneic stem cell transplantation (SCT). We show that donor-derived IFNgamma augments acute GVHD via direct effects on (1) the donor T cell to promote T helper 1 (Th1) differentiation and (2) the gastrointestinal (GI) tract to augment inflammatory cytokine generation. However, these detrimental effects are overwhelmed by a protective role of IFNgamma in preventing the development of idiopathic pneumonia syndrome (IPS). This is the result of direct effects on pulmonary parenchyma to prevent donor cell migration and expansion within the lung. Thus, IFNgamma is the key cytokine differentially controlling the development of IPS and gastrointestinal GVHD after allogeneic SCT.

Inflammatory cytokines and the development of pulmonary complications after allogeneic hematopoietic cell transplantation in patients with inherited metabolic storage disorders

Patients with inherited metabolic storage disorders are at a higher risk of developing pulmonary complications after hematopoietic cell transplantation (HCT). This single-center prospective study of 48 consecutive inherited metabolic storage disorder patients was performed to identify risk factors for the development of pulmonary complications after HCT. Before HCT, subjects underwent bronchoalveolar lavage (BAL) for cell count, culture, nitrite levels, and analysis of proinflammatory cytokines and chemokines. The overall incidence of pulmonary complications was 52% (infectious, 23%; noninfectious, 29%) over a period of 4 years. Diffuse alveolar hemorrhage was the most frequent noninfectious complication and occurred in 19% of patients, all of whom had a diagnosis of mucopolysaccharidosis (Hurler and Maroteaux-Lamy syndromes). Levels of interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor alpha, macrophage inflammatory protein 1alpha, and granulocyte colony-stimulating factor in BAL fluid samples obtained before HCT were higher in patients with mucopolysaccharidoses than in patients with leukodystrophies. In addition, levels of IL-1beta, IL-6, IL-8, and granulocyte colony-stimulating factor were increased in the BAL fluid of patients who developed noninfectious pulmonary complications compared with those who did not develop pulmonary complications. It is interesting to note that most noninfectious pulmonary complications occurred in patients with mucopolysaccharidoses, especially diffuse alveolar hemorrhage, which occurred exclusively in patients with mucopolysaccharidoses. Higher levels of bronchial proinflammatory cytokines and chemokines may be predictive of the development of subsequent posttransplantation noninfectious complications in patients with mucopolysaccharidoses, especially those with Hurler syndrome. Larger studies will be required to further elucidate etiologic mechanisms and predictive factors.

Cell-autonomous CCL5 transcription by memory CD8 T cells is regulated by IL-4

Immunological memory is associated with the display of improved effector functions. The maintenance by CD8 memory cells of high levels of untranslated CCL5 mRNA allows these cells to immediately secrete this chemokine upon Ag stimulation. Untranslated mRNA storage is a newly described process supporting the immediate display of an effector function by memory lymphocytes. We have tested the capacity of different cytokines to regulate the memorization of CCL5 by memory CD8 T cells. We found that IL-4 treatment of murine CD8 T cells impairs immediate CCL5 secretion capacity by inhibiting CCL5 mRNA transcription through a STAT6-dependent pathway. The inhibition by IL-4 is reversible, as memory CD8 T cells reconstitute their CCL5 mRNA stores and reacquire their immediate CCL5 secretion capacity when IL-4 is withdrawn. This recovery is cell autonomous because it proceeds in culture medium in the absence of exogenous growth factors, suggesting that CCL5 expression by memory CD8 T cells is a default process. Overall, these results indicate that the expression of CCL5 is an intrinsic property acquired by memory CD8 T cells that is regulated by environmental factors.

Pulmonary complications after T-cell-depleted allogeneic stem cell transplantation: low incidence and strong association with acute graft-versus-host disease

Lung injury limits the success of allogeneic stem cell transplantation (SCT). The overall incidence varies from 30 to 50% and non-infectious causes occur in one-third to one-half of these. We reviewed pulmonary complications in 369 consecutive patients who received a partially T-cell-depleted myeloablative allogeneic hematopoietic SCT at our institution between 1993 and 2003. All patients were treated uniformly with cyclophosphamide followed by total body irradiation. Control subjects were matched on sex, underlying diagnosis, age, type of transplantation and cytomegalovirus (CMV)-serostatus. Sixty-one patients (16.5%) developed pulmonary complications. Twenty-one patients (5.7%) developed infectious pneumonia. Forty patients developed non-infectious complications which were further subclassified as bronchiolitis obliterans (3.5%), bronchiolitis obliterans-organizing pneumonia (0.5%), diffuse alveolar hemorrhage (0.8%), idiopathic pneumonia syndrome (5.5%) or mixed etiology (0.5%). Acute graft-versus-host disease (GVHD) > or =grade II was significantly more common in pulmonary patients than in the controls (36/61 versus 22/61 patients, P=0.02). There was no significant difference in the incidence of chronic GVHD (P=0.09). CMV reactivation was significantly more frequent in patients with lung injury (P=0.02). Median survival was 41 weeks for the pulmonary patients and 350 weeks for the controls (P=0.001). Altogether, the incidence of pulmonary complications is low after T-cell-depleted SCT and is associated with acute GVHD and CMV reactivation.

Bone marrow transplantation and approaches to avoid graft-versus-host disease (GVHD)

Haematopoietic stem cell transplantation (HSCT) offers promise for the treatment of haematological and immune disorders, solid tumours, and as a tolerance inducing regimen for organ transplantation. Allogeneic HSCTs engraftment requires immunosuppression and the anti-tumour effects are dependent upon the immune effector cells that are contained within or generated from the donor graft. However, significant toxicities currently limit its efficacy. These problems include: (i) graft-versus-host disease (GVHD) in which donor T cells attack the recipient resulting in multi-organ attack and morbidity, (ii) a profound period of immune deficiency following HSCT, and (iii) donor graft rejection. Currently available methods to prevent or treat GVHD with systemic immunosuppression can lead to impaired immune recovery, increased opportunistic infections, and higher relapse rates. This review will provide an overview of GVHD pathophysiology and discuss the roles of various cells, pathways, and factors in the GVHD generation process and in the preservation of graft-versus-tumour effects. Variables that need to be taken into consideration in attempting to extrapolate preclinical results to the clinical paradigm will be highlighted.

Leukocyte migration and graft-versus-host disease

Graft-versus-host disease (GVHD) remains a significant complication of allogeneic bone marrow transplantation (allo-BMT). Acute GVHD is mediated by immunocompetent donor T cells, which migrate to lymphoid tissues soon after infusion, recognize host alloantigens, and become activated upon interaction with host antigen-presenting cells (APCs). Recent work from our group and others suggests that activated effector T cells exit lymphoid tissues and traffic to mucosal sites and parenchymal target organs such as the gastrointestinal (GI) tract, liver, lung, and skin where they cause tissue damage. The molecular interactions necessary for effector cell migration during GVHD have become the focus of a growing body of research, as these interactions represent potential therapeutic targets. In this review we discuss chemokine and chemokine receptor interactions and adhesion molecules that have been shown to play roles in effector cell migration in experimental GVHD models, and we discuss a potential model for the role of chemokines during the activation phase of GVHD.