Differential cytokine expression in acute and chronic murine graft-versus-host-disease

Treatment outcome at the pediatric stem cell transplantation center in Syria: A single-center experience

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is a therapeutic approach known for its high success rates in treating various hematologic malignancies, hemoglobinopathies, immune deficiencies, and other disorders. Notably, pediatric HSCT commenced in Syria in 2021 amidst the prevailing crisis. This study aims to assess the demographic and clinical profiles of pediatric patients who underwent stem cell transplantation and to analyze treatment outcomes at Syria's inaugural pediatric HSCT center.

METHODS

This study is a single-center retrospective analysis of 25 pediatric patients who underwent HSCT underage of 14 years in the National Stem Cell Center (HAYAT) in Damascus within the period 2021-2023. The databases were created based on data that were collected from patient medical records.

RESULTS

In autologous patients, transplant-related mortality (TRM) was 0%, with 4 (57%) experiencing disease relapse, resulting in the death of one patient. Additionally, 3 (42.8%) of patients remain alive under second-line management. The overall survival rate was 6 (85.7%), and the disease-free survival rate was 16 (88%). In allogeneic patients, TRM was 5.5% (1/18). One allogeneic patient experienced disease relapse and subsequently died. The overall survival rate and disease-free survival rate were 16 (88%).

CONCLUSIONS

The objective of this study was to assess the outcomes of pediatric HSCT patients who have undergone transplantation thus far. Given the recent initiation of pediatric stem cell transplantation in Syria, our dataset provides a basis for comparison with international hematopoietic stem cell transplantation centers regarding treatment complications and outcomes, notwithstanding the challenges and crises faced within our country.

Secreted osteopontin from CD4+ T cells limits acute graft-versus-host disease

Osteopontin (OPN) has been considered a potential biomarker of graft-versus-host disease (GVHD). However, the function of OPN in GVHD is still elusive. Using a mouse model of acute GVHD (aGVHD), we report that OPN generated by CD4+ T cells is sufficient to exert a beneficial effect in controlling aGVHD through limiting gastrointestinal pathology, a major target organ of aGVHD. CD4+ T cell-derived OPN works on CD44 expressed in intestinal epithelial cells (IECs) and abates cell death of IECs. OPN also modulates gut microbiota with enhanced health-associated commensal bacteria Akkermansia. Importantly, we use our in vivo mouse mutant model to specifically express OPN isoforms and demonstrate that secreted OPN (sOPN), not intracellular OPN (iOPN), is solely responsible for the protective role of OPN. This study demonstrates that sOPN generated by CD4+ T cells is potent enough to limit aGVHD.

Chronic graft-versus-host disease: biological insights from preclinical and clinical studies

With the increasing use of mismatched, unrelated, and granulocyte colony-stimulating factor-mobilized peripheral blood stem cell donor grafts and successful treatment of older recipients, chronic graft-versus-host disease (cGVHD) has emerged as the major cause of nonrelapse mortality and morbidity. cGVHD is characterized by lichenoid changes and fibrosis that affects a multitude of tissues, compromising organ function. Beyond steroids, effective treatment options are limited. Thus, new strategies to both prevent and treat disease are urgently required. Over the last 5 years, our understanding of cGVHD pathogenesis and basic biology, born out of a combination of mouse models and correlative clinical studies, has radically improved. We now understand that cGVHD is initiated by naive T cells, differentiating predominantly within highly inflammatory T-helper 17/T-cytotoxic 17 and T-follicular helper paradigms with consequent thymic damage and impaired donor antigen presentation in the periphery. This leads to aberrant T- and B-cell activation and differentiation, which cooperate to generate antibody-secreting cells that cause the deposition of antibodies to polymorphic recipient antigens (ie, alloantibody) or nonpolymorphic antigens common to both recipient and donor (ie, autoantibody). It is now clear that alloantibody can, in concert with colony-stimulating factor 1 (CSF-1)-dependent donor macrophages, induce a transforming growth factor β-high environment locally within target tissue that results in scleroderma and bronchiolitis obliterans, diagnostic features of cGVHD. These findings have yielded a raft of potential new therapeutics, centered on naive T-cell depletion, interleukin-17/21 inhibition, kinase inhibition, regulatory T-cell restoration, and CSF-1 inhibition. This new understanding of cGVHD finally gives hope that effective therapies are imminent for this devastating transplant complication.

Physical function and quality of life in patients with chronic GvHD: a summary of preclinical and clinical studies and a call for exercise intervention trials in patients

Allogeneic hematopoietic stem cell transplant, to reconstitute the hematopoietic and immune status of patients undergoing myeloablative therapy for hematologic disorders, has been of great benefit in minimizing or eradicating disease and extending survival. Patients who undergo allogeneic hematopoietic stem cell transplant (allo-HSCT) are subject to many comorbidities among which the most significant, affecting quality of life (QoL) and survival, are acute GvHD (aGvHD) and chronic GvHD (cGvHD), resulting from donor lymphocytes reacting to and damaging host tissues. Physical activity and exercise have clearly been shown, in both children and adults, to enhance fitness, improve symptomatology and QoL, reduce disease progression and extend survival for many diseases including malignancies. In some cases, vigorous exercise has been shown to be equal to or more effective than pharmacologic therapy. This review addresses how cGvHD affects patients' physical function and physical domain of QoL, and the potential benefits of exercise interventions along with recommendations for relevant research and evaluation targeted at incorporating this strategy as soon as possible after allo-HSCT and ideally, as soon as possible upon diagnosis of the condition leading to allo-HSCT.

The effect of extracorporeal photopheresis on T cell response in chronic graft-versus-host disease

Extracorporeal photopheresis (ECP) is a safe and effective immunoregulatory therapy for steroid-refractory chronic graft-versus-host disease (cGVHD) but its mechanism of action is poorly understood. In this study, we evaluated the effect of ECP in a sample of cGVHD patients. Our data showed that ECP-treated patients had lower CD4 T and B cells, and substantially higher NK cells than untreated patients. T regulatory (Treg) cells were similar between the two groups of patients. Interestingly, Treg cells were higher in ECP-treated patients and ECP-responders who had no history of aGVHD or sclerosis, than in those who had one of them or both. These findings suggest that at least one of the mechanisms of immunomodulation by ECP targets the Treg cell population and that an increase in Treg cells may be associated with response in patients with cGVHD. Together, the results of ECP are different depending on the patients' clinical condition.

Basophils inhibit proliferation of CD4⁺ T cells in autologous and allogeneic mixed lymphocyte reactions and limit disease activity in a murine model of graft versus host disease

Basophils are known to modulate the phenotype of CD4(+) T cells and to enhance T helper type 2 responses in vitro and in vivo. In this study, we demonstrate that murine basophils inhibit proliferation of CD4(+) T cells in autologous and allogeneic mixed lymphocyte reactions. The inhibition is independent of Fas and MHC class II, but dependent on activation of basophils with subsequent release of interleukin-4 (IL-4) and IL-6. The inhibitory effect of basophils on T-cell proliferation can be blocked with antibodies against IL-4 and IL-6 and is absent in IL-4/IL-6 double-deficient mice. In addition, we show that basophils and IL-4 have beneficial effects on disease activity in a murine model of acute graft-versus-host disease (GvHD). When basophils were depleted with the antibody MAR-1 before induction of GvHD, weight loss, GvHD score, mortality and plasma tumour necrosis factor levels were increased while injection of IL-4 improved GvHD. Basophil-depleted mice with GvHD also have increased numbers of CD4(+) T cells in the mesenteric lymph nodes. Our data show for the first time that basophils suppress autologous and allogeneic CD4(+) T-cell proliferation in an IL-4-dependent manner.

Exercise benefits in chronic graft versus host disease: a murine model study

INTRODUCTION

Chronic graft versus host disease (cGVHD) is a life-threatening complication of allogeneic hematopoietic stem cell transplantation that generates considerable morbidity and compromises the physical capacity of patients. We determined the effects of an exercise training program performed after allogeneic hematopoietic stem cell transplantation on clinical and biological variables in a minor histocompatibility antigen-driven murine model of cGVHD treated with cyclosporine A.

METHODS

Recipient BALB/C female mice (age 8 wk) received bone marrow cells and splenocytes from donor B10.D2 male mice and were randomly assigned to an exercise (n = 11) or control group (n = 12). For approximately 11 wk after transplant, the exercise group completed a moderate-intensity treadmill program. Variables assessed were clinical severity scores, survival, physical fitness, cytokine profile, immune cell reconstitution, molecular markers of muscle exercise adaptations, and histological scores in affected tissues.

RESULTS

Exercise training increased survival (P = 0.011), diminished total clinical severity scores (P = 0.002), improved physical fitness (P = 0.030), and reduced blood IL-4 and tumor necrosis factor α levels (P = 0.03), while increasing circulating B220 (P = 0.008) and CD4 lymphocytes (P = 0.043).

CONCLUSIONS

A moderate-intensity exercise program that mimics widely accepted public health recommendations for physical activity in human adults was well tolerated and positive effects on survival as well as on clinical and biological indicators of cGVHD.

Kinetics of T helper subsets and associated cytokines correlate well with the clinical activity of graft-versus-host disease

Background

CD4⁺interferon (IFN)-γ⁺ T cell (Th1) and CD4⁺interleukin (IL)-4⁺ T cell (Th2) polarizations are crucial in the pathogenesis of graft-versus-host disease (GVHD). However, this hypothesis is largely based on animal experiments of Parent-into-F1 GVHD model. The causal relationship between kinetics of Th1, Th2 and associated cytokines and the clinical activity of GVHD in a real world situation remains unknown.

Methodology

Peripheral blood was collected every week prospectively from Day 0 to Day 210 (patients without GVHD) or Day 300 (patients with chronic GVHD) after allogeneic peripheral blood stem cell transplantation in consecutive 27 patients. The frequencies of Th1 and Th2 within CD4⁺ T cells were determined by flow cytometry and pplasma IFN-γ, IL-12, IL-4, and IL-10 were determined by ELISA.

Principal Findings

Kinetics of Th1, Th2 frequency, and the plasma IL-10 and IFN-γ more commonly coincided with, rather than predicted, the activity of GVHD. These markers are significantly higher when acute or chronic GVHD developed. The kinetics of IL-10 is especially correlated well with the activity of GVHD during clinical course of immunosuppressive treatment. For patients with hepatic GVHD, there is a positive correlation between plasma IL-10 levels and the severity of hepatic injury. The frequency of Th2 is also significant higher in acute GVHD and tends to be higher in chronic GVHD. Interestingly, there is a very good positive correlation between the frequency of Th1 and Th2 (r = 0.951, p<0.001). The plasma level of IL-4 and IL-12 are not associated with the activity of GVHD.

Conclusions

The frequency of Th1, Th2 within CD4⁺ T cells and plasma IL-10 and IFN-γ are good biomarkers of GVHD. Plasma IL-10 can also be used to monitor the therapeutic responsiveness. Furthermore, both Th1 and Th2 likely contribute to the pathogenesis of GVHD.

LBH589 enhances T cell activation in vivo and accelerates graft-versus-host disease in mice

Histone deacetylase inhibitors (HDACis) are a new class of compounds that induce acetylation of histone lysine tails in chromatin and modify gene expression. The Food & Drug Administration approved HDACi, Vorinostat, or suberoylanilide hydroxamic acid (SAHA), has been shown to inhibit tumor cell growth and the production of proinflammatory cytokines. In preclinical allogeneic transplant models, SAHA induces graft-versus-host disease (GVHD) amelioration in treated mice without impairing graft-versus-leukemia. LBH589 (Panobinostat), a structurally novel cinnamic hydroxamic acid class, is an HDACi more potent than SAHA. In the current work, we tested the hypothesis that LBH589 would be highly effective in the prevention of GVHD. Using mouse model of allogeneic bone marrow transplant (BMT), we unexpectedly found that treatment with LBH589 accelerated GVHD, in contrast to the treatment with SAHA that alleviated GVHD. Accelerated GVHD in the recipients treated with LBH589 was associated with elevated Th1 cytokines in recipient serum, enhanced CXCR3 expression on donor T cells, and T cell infiltration in the liver. The current study highlights the distinct effects of pan HDACi on allogeneic BMT and alerts that LBH589 (Panobinostat) could have an adverse effect on GVHD, and possibly on other inflammatory diseases.

The pathophysiology of chronic graft-versus-host disease: the unveiling of an enigma

Chronic graft-versus-host disease (CGVHD) is one of the most significant complications of long-term survivors after allogeneic hematopoietic stem cell transplantation (allo-HSCT). CGVHD may have protean manifestations and can pose unique diagnostic and therapeutic challenges. New recommendations that emphasize the importance of qualitative differences, as opposed to time of onset after HSCT, are now being used to standardize the diagnosis and clinical assessment of CGVHD, but they require validation. During the past 3 decades, experimental studies and clinical observations have elucidated the mechanisms of acute GVHD, but its biology is much less well-understood. Experimental studies have generated at least 4 theories to explain the pathophysiology of CGVHD: (1) thymic damage and the defective negative selection of T cells, (2) regulatory T cell deficiencies, (3) auto-antibody production by aberrant B cells, and (4) the formation of profibrotic lesions. Mouse models have provided important insights into the pathophysiology of CGVHD, and these have helped improve clinical outcomes following allo-HSCT, but no animal model fully replicates all of the features of CGVHD in humans. In this article, recent clinical changes, the pathogenesis of CGHVD, the cellular and cytokine networks implicated in its pathogenesis, and the animal models used to devise strategies to prevent and treat CGVHD are reviewed.

IL-17-producing T cells contribute to acute graft-versus-host disease in patients undergoing unmanipulated blood and marrow transplantation

The aim of this study was to investigate the effects of IL-17-producing T cells, including Th17 and Tc17 cells, on acute graft-versus-host disease (aGVHD) in patients who had undergone granulocyte colony-stimulating factor (G-CSF)-mobilised peripheral blood progenitor cell (PBPC) and G-CSF-primed bone marrow (G-BM) transplantation. Allografts from forty-one patients were analysed for IL-17-producing T cells with respect to aGVHD. Furthermore, ten patients with aGVHD onset were monitored for the presence of Th17 cells in the peripheral blood by flow cytometry. Patients who received a higher dose of Th17 cells in the G-BM (>8.5 × 10(4) /kg, p=0.005) or a higher dose of Tc17 cells in PBPC (>16.8 × 10(4) /kg, p=0.001) exhibited a higher incidence of aGVHD. An increased Th17 population (up to 4.99% CD4(+) T lymphocytes) was observed in patients with aGVHD onset. In contrast, the percentage of Th17 population decreased drastically in aGVHD patients following treatment to achieve partial and complete remission (p=0.013 and p=0.008, respectively). All percentages of Th17 and Tc17 cells were significantly reduced after in vivo G-CSF application. Our results suggested that IL-17-producing T cells contributed to aGVHD. The application of G-CSF in vivo aided in reducing the occurrence of aGVHD through a decrease in IL-17 secretion by T cells.

CP-690550, a Janus kinase inhibitor, suppresses CD4+ T-cell-mediated acute graft-versus-host disease by inhibiting the interferon-γ pathway

BACKGROUND

Acute graft-versus-host disease (GVHD) is a critical obstacle to bone marrow transplantation. Although numerous studies have described immunosuppression protocols to mitigate acute GVHD, the need still exists for a more efficient immunosuppressant with fewer side effects. Here, we evaluated the protective effect of CP-690550, a newly developed Janus kinase inhibitor, in an acute GVHD model.

METHODS

CP-690550 was chemically synthesized. Acute GVHD was induced through the transfer of parent B6 (H-2) bone marrow and CD4 T cells into lethally irradiated (B6×bm12)F1 (H-2) mice. RESULTS.: CP-690550 treatments confined to days -3 to 11 of GVHD induction provided full protection against allogeneic, acute GVHD-related lethality and histopathology. An analysis of the initial donor-derived CD4 T-cell responses revealed that the inhibitory effects of CP-690550 were largely related to the suppression of donor CD4 T-cell-mediated interferon (IFN)-γ production. Enhanced inhibition of T helper 1 cell differentiation, rather than the inhibition of allogeneic CD4 T-cell proliferation or T helper 17 cell differentiation, was also confirmed in allogeneic mixed lymphocyte reactions. Because lethality was considerably delayed by the systemic blockade of IFN-γ, the principal protective effect of CP-690550 occurred through the modulation of IFN-γ production.

CONCLUSION

The targeting of Janus kinase with a sensitive and specific inhibitor, CP-690550, conferred effective protection from acute GVHD induced by a semiallogeneic major histocompatibility complex class II-disparate combination. Protection from acute GVHD was largely mediated by the inhibition of IFN-γ production.

Indoleamine 2,3-dioxygenase in human hematopoietic stem cell transplantation

In recent years tryptophan metabolism and its rate limiting enzyme indoleamine 2,3-dioxygenase (IDO) have attracted increasing attention for their potential to modulate immune responses including the regulation of transplantation tolerance. The focus of this review is to discuss some features of IDO activity which particularly relate to hematopoietic stem cell transplantation (HSCT). HSCT invariably involves the establishment of some degree of a donor-derived immune system in the recipient. Thus, the outstanding feature of tolerance in HSCT is that in this type of transplantation it is not rejection, which causes the most severe problems to HSCT recipients, but the reverse, graft-versus-host (GvH) directed immune responses. We will discuss the peculiar role of IDO activity and accelerated tryptophan metabolism at the interface between immune activation and immune suppression and delineate from theoretical and experimental evidence the potential significance of IDO in mediating tolerance in HSCT. Finally, we will examine therapeutic options for exploitation of IDO activity in the generation of allo-antigen-specific tolerance, i.e. avoiding allo-reactivity while maintaining immunocompetence, in HSCT.

Contribution of B7RP-1/ICOS co-stimulation to lethal acute GVHD

Co-stimulatory molecules expressed on T cells critically regulate donor T-cell activation and are implicated in acute GVHD after allogeneic BMT. We here investigated the role of interaction between B7-related protein-1 (B7RP-1) and ICOS in murine acute GVHD model that received T cell-depleted BM cells and splenocytes. Administration of blocking anti-B7RP-1 mAb significantly reduced the lethality and symptoms in acute GVHD. A significant hypo-responsiveness of splenocytes to host alloantigen was observed in the recipient mice treated with anti-B7RP-1 mAb. Moreover, acute GVHD was significantly reduced in the recipients of T cells composed of ICOS-deficient CD8 T cells and WT CD4 T cells compared with that in the recipients of T cells composed of WT CD8 T cells and ICOS-deficient CD4 T cells. These results suggested that B7RP-1/ICOS co-stimulatory signal plays a role in the activation of alloantigen-reactive donor T cells, particularly in CD8 T cells, in murine acute GVHD model, and that the blockade of B7RP-1/ICOS interaction may be useful for selectively manipulating allo-reactive T cells in the recipients with acute GVHD.

Increased DNA damage in hematopoietic cells of mice with graft-versus-host disease

Patients who received hematopoietic cell transplants have an increased risk for a new malignancy. In addition to genotoxic regimens such as radiotherapy and chemotherapy, graft-versus-host disease (GVHD) is a risk factor for development of new malignancies in long-term survivors. To understand mechanisms underlying this malignant transformation, we evaluated genomic damage in several murine models of GVHD by enumerating reticulocytes containing micronuclei (MN) in the blood after semi-allogeneic (parent-into-F1) hematopoietic cell transplantation. On day 40 after transplantation, MN frequencies were significantly increased in unirradiated (C57BL6 x DBA/2) F1 (BDF1) and (BALB/c x C57BL6) F1 (CBF1) mice that received cells from C57BL6 (B6) donors. MN frequencies were not significantly increased in F1 mice that received cells from DBA/2 or BALB/c donors. Serum levels of tumor necrosis factor-alpha (TNF-alpha) were higher after transplantation with B6 donors than with DBA/2 or BALB/c donors. The results indicate that GVHD, without irradiation, can induce genomic damage associated with inflammatory reactions manifested by increased TNF-alpha levels.

Homing in on acute graft vs. host disease: tissue-specific T regulatory and Th17 cells

Acute graft vs. host disease (aGVHD) is a major limitation of hematopoietic stem cell transplantation (HSCT), and it causes significant morbidity and mortality for this patient population. This immune-mediated injury occurs unpredictably and is caused by donor-derived T cells reacting to recipient alloantigens. Although donor Th1 cells play a critical role in aGVHD generation, numerous arms of both the innate and the adaptive immune systems along with determinants of lymphocyte trafficking are likely involved in the multifaceted cascade of immunological events that culminates in clinical aGVHD. T regulatory and Th17 cells are T cell subsets distinct from Th1 cells that are likely involved with aGVHD. Regulatory T cells (Tregs) have been implicated in the prevention of aGVHD in both mouse and man, while Th17 cells may modulate early inflammatory responses associated with aGVHD, especially those involving the skin and the lungs. Interestingly, these two lymphocyte subsets appear to be reciprocally regulated in part through retinoic acid, through cytokines such as IL-6, and via interactions with dendritic cells. Another area under tight regulation appears to be the homing of lymphocytes to lymph nodes, skin, and gut. Adhesion molecules including chemokine receptors, selectins, and integrins may identify specific T cell subsets with unique migratory functional properties during HSCT. Controlling the migration patterns of Th17 cells and Tregs represents a potential therapeutic target. A major goal of HSCT research will be to develop approaches to pharmacologically manipulate T cell subsets in vivo or to select, expand, and infuse T cell subsets that will maximize the targeted graft vs. tumor effect while minimizing the potentially fatal side effects of aGVHD. A better understanding of Tregs and their tissue specificity should lead to improvement in the success of HSCT.

Effect of transplantation of splenic lymphoid cells on functional activity of the immune and nervous system in experimental animals

We studied the effect of transplantation of splenic lymphoid cells on functional activity of the nervous (orientation and exploratory behavior and expression of genes for interleukin-1beta, type 1 interleukin-1 receptor, and erythropoietin in the brain) and immune system (cellular and humoral immune response, proliferative activity of immunocompetent cells, and expression of cytokine genes in splenocytes) in syngeneic animals with different behavioral characteristics. Intravenous injection of the lymphoid fraction of splenocytes from donor mice with a certain behavioral pattern in the open-field test had a modulatory effect on vertical locomotor activity of syngeneic recipient mice. The increase or decrease in vertical locomotor activity due to transplantation of immunocompetent cells was accompanied by specific changes in mRNA level for erythropoietin receptor and type 1 interleukin-1 receptor in brain cells of recipient mice. The regulation of orientation and exploratory behavior was also accompanied by changes in functional activity of the immune system in recipient animals. It was manifested in modulation of proliferative activity of thymic and splenic cells and cytokine gene expression in splenocytes.

IL-17 contributes to CD4-mediated graft-versus-host disease

CD4(+) interleukin-17 (IL-17)(+) T cells (Th17 cells) have been implicated in allograft rejection of solid organs and several autoimmune diseases. However, the functional role of Th17 cells in the development of acute graft-versus-host disease (GVHD) has not been well-characterized. We detected significant numbers of alloreactive CD4(+) donor T cells expressing IL-17, IL-17F, or IL-22 in the lymphoid organs of recipients of an allogeneic bone marrow transplant. We found no differences in GVHD mortality or graft-versus-tumor (GVT) activity between wild type (WT) and IL-17(-/-) T-cell recipients. However, upon transfer of murine IL-17(-/-) CD4(+) T cells in an allogeneic BMT model, GVHD development was significantly delayed behind recipients of WT CD4(+) T cells, yet overall GVHD mortality was unaffected. Moreover, recipients of IL-17(-/-) CD4(+) T cells had significantly fewer Th1 cells during the early stages of GVHD. Furthermore, we observed a decrease in the number of IFN-gamma-secreting macrophages and granulocytes and decreased production of proinflammatory cytokines (interferon [IFN]-gamma, IL-4, and IL-6) in recipients of IL-17(-/-) CD4(+) T cells. We conclude that IL-17 is dispensable for GVHD and GVT activity by whole T cells, but contributes to the early development of CD4-mediated GVHD by promoting production of proinflammatory cytokines.

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

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

Lacking cytokine production in ES cells and ES-cell-derived vascular cells stimulated by TNF-alpha is rescued by HDAC inhibitor trichostatin A

Inflammation and TNF-alpha signaling play a central role in most of the pathological conditions where cell transplantation could be applied. As shown by initial experiments, embryonic stem (ES) cells and ES-cell derived vascular cells express very low levels of TNF-alpha receptor I (TNFRp55) and thus do not induce cytokine expression in response to TNF-alpha stimulation. Transient transfection analysis of wild-type or deletion variants of the TNFRp55 gene promoter showed a strong activity for a 250-bp fragment in the upstream region of the gene. This activity was abolished by mutations targeting the Sp1/Sp3 or AP1 binding sites. Moreover, treatment with trichostatin A (TSA) led to a pronounced increase in TNFRp55 mRNA and promoter activity. Overexpression of Sp1 or c-fos further enhanced the TSA-induced luciferase activity, and this response was attenuated by Sp3 or c-jun coexpression. Additional experiments revealed that TSA did not affect the Sp1/Sp3 ratio but caused transcriptional activation of the c-fos gene. Thus, we provide the first evidence that ES and ES-cell-derived vascular cells lack cytokine expression in response to TNF-alpha stimulation due to low levels of c-fos and transcriptional activation of Sp1 that can be regulated by inhibition of histone deacetylase activity.

Graft-versus-host disease

Allogeneic haematopoietic stem-cell transplantation (SCT) is a curative therapy for haematological malignancies and inherited disorders of blood cells, such as sickle-cell anaemia. Mature alphabeta T cells that are contained in the allografts reconstitute T-cell immunity and can eradicate malignant cells in the recipient. Unfortunately, these T cells recognize the recipient as 'non-self' and employ a wide range of immune mechanisms to attack recipient tissues in a process known as graft-versus-host disease (GVHD). The full therapeutic potential of allogeneic haematopoietic SCT will not be realized until approaches to minimize GVHD, while maintaining the positive contributions of donor T cells, are developed. This Review focuses on research in mouse models pursued to achieve this goal.

Effect of transplantation of immunocompetent cell on orientation and exploratory behavior and cytokine gene expression in the brain of experimental animals

Intravenous injection of adherent splenocyte fraction from donor (CBAxC57Bl/6)F(1) mice characterized by specific open-field behavior modified this behavior in syngeneic recipient mice. This was paralleled by appropriate changes in the levels of IL-1b and type 1 IL-1 receptor mRNA in the brain cells of recipient mice. Hence, we demonstrated the possibility of directed regulation of orientation and exploratory behavior in mice by transplantation of immunocompetent cells. Mononuclear phagocytes play an important role in this phenomenon.

IL-10-transduced bone marrow mesenchymal stem cells can attenuate the severity of acute graft-versus-host disease after experimental allogeneic stem cell transplantation

Recent data suggest that adult mesenchymal stem cells (MSCs) might enhance allogeneic hematopoietic engraftment and prevent graft-versus-host disease (GVHD) owing to their immunosuppressive nature. Using a murine model of acute GVHD, this study examined whether or not the immunosuppressive properties of MSCs could reduce the severity of experimental GVHD. The early injection of MSCs after transplant did not attenuate the severity of acute GVHD. Therefore, this study investigated whether or not the use of IL-10-transduced MSCs (IL-10 MSCs) could reduce the severity of acute GVHD. Lethally irradiated recipients were transplanted and injected with IL-10 MSCs, the MSC-expressing vector alone (vector MSCs), or the diluent (controls), respectively, on day +1. Compared with the vector MSCs or controls, there was a significantly lower mortality in the recipients of the IL-10 MSCs at day 50 after the transplant (percent survival, 0 or 10 vs 70%, P=0.0004 or 0.0064, respectively). The decrease in mortality was confirmed by the semi-quantitative GVHD score (P<0.05), and was associated with decreased serum levels of the pro-inflammatory cytokines, IFN-gamma, on day +7 (P=0.015). Therefore, beneficial effects on GVHD were observed when MSCs were engineered to express the anti-inflammatory cytokine, IL-10.

The effect of extracorporeal photoimmunotherapy (ECP) on serum TNF-a level in chronic graft versus host disease (GvHD)

Graft versus host disease (GvHD) is the most prominent cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (Allo-HCT). Extracorporeal photoimmunotherapy (ECP) is an alternative therapeutic modality in steroid and/or cyclosporin-A refractory GvHD developing after Allo-HCT. The aim of this study was to evaluate whether there was any relation between serum TNF-a levels and the response to ECP in patients with steroid refractory of extensive chronic GvHD. Between March 2001 and August 2003, seven patients (male: 1, female: 6) had ECP for treatment of steroid refractory extensive chronic GvHD. Five age and gender matched healthy volunteers were included in this study as the control group. The age of the patients ranged from 18 to 49 years. All patients were allografted from HLA-identical sibling donors. The median number of ECP sessions was 10 (8-36), consisting of two sequential cycles monthly. For measurement of serum TNF-a levels, blood samples were obtained both prior to ECP (basal) and after the first and second in all patients and in five patients after the 10th session. Serum TNF-a levels (Quantakine HS, R&D system, UK) were measured in peripheral venous blood samples by an ELISA method. ECP was given at a median of 5.8 months (1-14 months) after allo-HCT. No complications were seen during or after the ECP procedures. The median time of an ECP session was 183 minutes. The median volume of Uvadex used per session was 4.40 ml (3.61-5.61). The basal mean level of TNF-a was higher in patients than in the control group (2.47+/-0.83 pg/ml vs. 1.75+/-0.06, p=0.05). The mean TNF-a levels decreased from 2.47+/-0.83 pg/ml to 1.77+/-0.93 pg/ml after the initial session (p=0.045) and from 2.32+/-0.92 pg/ml to 1.69+/-0.93 pg/ml after the second day (p=0.015). After completion of the ECP sessions, extensive chronic GvHD recovered in only three patients. In three clinically responsive patients, the TNF-a levels were significantly reduced after both the second and tenth sessions. In contrast, in two patients not responding to ECP therapy, TNF-a levels were increased. In order to report whether these changes in TNF levels is an early predictor for evaluation of the efficacy of ECP in extensive chronic GvHD, TNF-a levels should be studied in a larger series.

Alloreaction increases or restores CD40, CD54, and/or HLA molecule expression in acute myelogenous leukemia blasts, through secretion of inflammatory cytokines: dominant role for TNFβ, in concert with IFNγ

We have previously reported that alloreaction can lead to activation of dendritic cells through secretion of inflammatory cytokines. Here, we addressed whether alloreaction-derived cytokines may also lead to acute myelogenous leukemia (AML) blast differentiation. With this aim, supernatant (sn) harvested from major or minor histocompatibility antigen-mismatched mixed lymphocyte reaction (MLR) were used to culture French American Bristish (FAB) type M4 or M5 AML blasts. Our results showed that the secreted factors induced upregulation of CD40, CD54, and/or HLA molecules in AML blasts. Protein fractionation, blockade experiments and exogenous cytokine reconstitution demonstrated the involvement of TNF in the upregulation of CD54, CD40 and HLA-class II molecules, and of IFNgamma in the increase of HLA-class I and class II molecule expression. But, in line of its much higher levels of secretion, TNFbeta, rather than TNFalpha, was likely to play a preponderant role in AML blast differentiation. Moreover TNFbeta and IFNgamma were also likely to be involved in the AML blast differentiation-mediated by HLA-identical donor T-cell alloresponse against recipient AML blasts. In conclusion, we show herein that upon allogeneic reaction, TNFbeta secretion contributes, in concert with IFNgamma, to increase or restore surface molecules involved in AML blast interaction with T cells.

Modulation of acute graft-versus-host disease and chimerism after adoptive transfer of in vitro-expanded invariant Valpha14 natural killer T cells

Mouse natural killer T cells with an invariant Valpha14-Jalpha18 TCR rearrangement (Valpha14i NKT cells) are able to regulate immune responses through rapid and large amounts of Th1 and Th2 cytokine production. It has been reported that in vivo administration of the Valpha14i NKT cell ligand, alpha-galactosylceramide (alpha-GalCer) significantly reduced morbidity and mortality of acute graft-versus-host disease (GVHD) in mice. In this study, we examined whether adoptive transfer of in vitro-expanded Valpha14i NKT cells using alpha-GalCer and IL-2 could modulate acute GVHD in the transplantation of spleen cells of C57BL/6 mice into (B6xDBA/2) F(1) mice. We found that the adoptive transfer of cultured spleen cells with a combination of alpha-GalCer and IL-2, which contained many Valpha14i NKT cells, modulated acute GVHD by exhibiting long-term mixed chimerism and reducing liver damage. Subsequently, the transfer of Valpha14i NKT cells purified from spleen cells cultured with alpha-GalCer and IL-2 also inhibited acute GVHD. This inhibition of acute GVHD by Valpha14i NKT cells was blocked by anti-IL-4 but not by anti-IFN-gamma monoclonal antibody. Therefore, the inhibition was dependent on IL-4 production by Valpha14i NKT cells. Our findings highlight the therapeutic potential of in vitro-expanded Valpha14i NKT cells for the prevention of acute GVHD after allogeneic hematopoietic stem cell transplantation.

Expression level of costimulatory receptor ICOS is critical for determining the polarization of helper T cell function

We found that inducible costimulator (ICOS)-deficient spleen cells have a defect in the ability to induce Th2-mediated chronic graft-versus-host disease (GVHD), whereas they were fully capable of inducing Th1-mediated acute GVHD. In contrast, CD28-deficient spleen cells induced neither acute nor chronic GVHD. To define the mechanisms of how these two CD28 family molecules manifest distinct functions in GVHD, the kinetics of their surface expression by donor T cells in two types of GVHD were investigated. It was found that expression of ICOS by donor T cells dramatically up-regulated after adoptive transfer in both acute and chronic GVHD, but in acute GVHD this up-regulation was transient and quickly down-regulated. In contrast, donor T cells in chronic GVHD maintained high levels of ICOS expression throughout the experiment. These results suggested that ICOS-mediated costimulatory signals are predominantly active in Th2-dominant responses. Changing patterns of CD28 expression by donor T cell were identical in both GVHD as they exhibited slight but sustained up-regulation after transfer, suggesting that CD28 provides a costimulatory signal necessary for the initial T cell activation, regardless of whether in Th1 or Th2 responses. These results lead us to propose that the expression levels of costimulatory receptors are critical for determining the polarization of helper T cell function.

T-cell P/E-selectin ligand α(1,3)fucosylation is not required for graft-vs-host disease induction

OBJECTIVE

Recognition of E- and P-selectins on vascular endothelium by their leukocyte glycoprotein counterreceptor P-selectin glycoprotein ligand-1 (PSGL-1) initiates and sustains leukocyte rolling, culminating in extravasation of lymphocytes from blood into organs. PSGL-1 is rendered functional by terminal glycosylation steps, which occur mainly in activated Th1 but not Th2 cells. alpha(1,3)Fucosyltransferases IV and VII control this glycosylation pathway. Mice lacking these transferases (Fuc-TIV(-/-)/Fuc-TVII(-/-)) lack functional E- and P-selectin ligands. We hypothesized that Fuc-TIV(-/-)/Fuc-TVII(-/-) donor T cells might have reduced capacity to roll on vessels of inflamed target tissues and mediate graft-vs-host disease (GVHD).

MATERIALS AND METHODS

We compared the ability of Fuc-TIV(-/-)/Fuc-TVII(-/-) and wild-type (WT) C57BL/6 (B6) spleen cells (SPCs) to produce GVHD in lethally irradiated major histocompatibility complex (MHC) haplotype-mismatched B6D2F1 recipients. Clinical GVHD, GVHD pathology in target organs, memory phenotype conversion, proliferation of donor T cells, and tissue and serum cytokine expression were examined.

RESULTS

Surprisingly, clinical GVHD was not reduced in lethally irradiated mice receiving full haplotype MHC mismatched or matched Fuc-TIV(-/-)/Fuc-TVII(-/-) SPCs compared to those receiving WT SPCs. GVHD pathology in target organs, memory phenotype conversion, and proliferation of donor T cells were similar in both groups. However, reduced interferon-gamma was detected in liver and lung, and serum levels of tumor necrosis factor-alpha were higher in mice receiving Fuc-TIV(-/-)/Fuc-TVII(-/-) SPCs compared with WT SPCs.

CONCLUSIONS

These results suggest that donor T cells, including Th1, are capable of trafficking to GVHD target tissues independently of P- and E- selectin ligand in conditioned hosts.

Cell populations and adhesion molecules expression in conjunctiva before and after bone marrow transplantation

We were interested to analyse the composition of the cellular infiltrate and adhesion molecules expression in the conjunctiva before and at least one hundred days after autologous and allogenic bone marrow transplantation (BMT) and its relation with the presence of dry eye. We used immunohistochemistry on cryopreserved human conjunctiva with monoclonal antibodies to T-lymphocytes (CD3, CD4 and CD8), B-lymphocytes (CD19), macrophages (CD14), natural killer cells (NK, CD57), intercellular adhesion molecule 1 (ICAM-1), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), lymphocyte function associated antigen-1 (LFA-1), very late antigen-4 (VLA-4), interleukin 2 receptor (IL2r, CD25) and HLA-DR. Our autologous recipients had no graft-versus-host disease (GVHD) but allogenic patients had chronic GVHD. After autologous BMT the conjunctiva had significantly more: (1) T lymphocytes (CD3+, CD4+, CD8+) in the epithelium; (2) CD4+ and CD14+ cells in the stroma; and (3) VLA-4 expression in the stroma than before BMT. After allogenic BMT, the conjunctiva exhibited a significant increase of: (1) CD3+ and CD14+ cells in the epithelium; (2) T lymphocytes (CD3+, CD4+, CD8+) and CD14+ cells in the stroma; and (3) VLA-4 and LFA-1 expression in the stroma than before BMT. After the engraftment, the comparison between autologous and allogenic recipients revealed that: (1) there were no significant differences in adhesion molecule expression; (2) the epithelium of autologous recipients had significantly more CD3+ cells; and (3) the stroma of allogenic patients had significantly more CD3+ and CD8+ cells. Among allogenic recipients, CD14+ cells were significantly increased both in the epithelium and in the stroma of patients with signs or symptoms of dry eye in comparison with patients without ocular involvement. Additionally, those having keratoconjunctivitis sicca (KCS) had CD4/CD8 ratios significantly higher than those without KCS. In conclusion, in the conjunctiva after autologous BMT a subclinical cell mediated immune reaction seems to take place. The conjunctivitis of chronic GVHD is complex, with T cells and macrophages dramatically contributing to the process.

IL-4-producing CD8+ T cells may be an immunological hallmark of chronic GVHD

Chronic graft-versus-host disease (cGVHD) occurs in approximately 60-80% of those who survive over 100 days after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the pathophysiology of cGVHD is poorly understood. To gain more insight into the immunological mechanism of cGVHD, we examine cytokine production of peripheral blood T cells from 19 patients in the chronic phase of allo-HSCT. The percentage of IFN-gamma-producing CD8(+) T cells among CD8(+) T cells was significantly higher in patients with or without cGVHD than in normal control subjects (P<0.001). On the other hand, the percentage of IL-4-producing CD8(+) T cells among CD8(+) T cells was significantly higher in patients with cGVHD (mean 3.3%; range 1.3-8.2%) than in patients without cGVHD (mean 1.2%; range 0.8-1.7%) and normal control subjects (mean 1.1%; range 0.1-1.6%) (both P<0.001). By contrast, the percentage of IL-4-producing CD4(+) T cells was not different among patients with and without cGVHD and normal controls. These findings suggest that IL-4-producing CD8(+) T cells may be an immunological marker of cGVHD.

Recovery of Valpha24+ NKT cells after hematopoietic stem cell transplantation

Human Valpha24+ natural killer T (NKT) cells have an invariant T-cell receptor-alpha chain and are activated in a CD1d-restricted manner. Valpha24+ NKT cells are thought to regulate immune responses and to play important roles in the induction of allograft tolerance. In this report, we analyzed the recovery of Valpha24+ NKT cells after hematopoietic stem cell transplantation and its correlation with graft-versus-host disease (GVHD). Patients who received a dose-reduced conditioning regimen, antithymocyte globulin- or CAMPATH-1H-containing conditioning regimen were excluded. NKT cells were reconstituted within 1 month after transplantation in peripheral blood stem cell transplantation recipients, while their numbers remained low for more than 1 year in bone marrow transplantation (BMT) recipients. The number of Valpha24+ NKT cells in BMT recipients with acute GVHD was lower than that in patients without acute GVHD, and both the CD4+ and CD4- Valpha24+ NKT subsets were significantly reduced. With regard to chronic GVHD, BMT recipients with extensive GVHD had significantly fewer Valpha24+ NKT cells than other patients. Furthermore, the number of CD4+ Valpha24+ NKT cells was also significantly reduced in patients with chronic extensive GVHD. Our results raise the possibility that the number of Valpha24+ NKT cells could be related to the development of GVHD.

Biomechanical stress induces IL-6 expression in smooth muscle cells via Ras/Rac1-p38 MAPK-NF-kappaB signaling pathways

IL-6, a proinflammatory cytokine, has been implicated in the development of vascular diseases. We previously demonstrated that mechanical stress can initiate signaling pathways leading to smooth muscle cell (SMC) proliferation and apoptosis, but little is known concerning cyclic stress-induced inflammatory response. To explore the role of stretch in the upregulation of cytokine expression in SMCs we performed RNase protection assay for a panel of cytokines and found that mechanical stress resulted in a time-dependent induction of IL-6 mRNA but not other cytokines, e.g., IL-1alpha, IL-1beta, IL-6, IL-10, IL-12p35, IL-12p40, IL-18, IFN-gamma, and macrophage migration inhibitory factor (MIF). This induction also correlated with elevated IL-6 protein levels in the supernatant. Pretreatment of the cells with NF-kappaB inhibitors inhibited NF-kappaB activity and resulted in marked inhibition (50%) of IL-6 protein. Moreover, SMC lines stably expressing dominant-negative Ras (RasN17) or Rac (RacN17) exhibited a remarkable decrease in p38 MAPK activity and IL-6 mRNA induction by mechanical stress. Furthermore, a significant inhibition of 30 and 40% in IL-6 protein was observed in SMCs pretreated with inhibitors of p38 MAPK and ERK1/2, respectively, but not JNK. Interestingly, SMCs isolated from PKC-delta-deficient mice exhibited higher levels of IL-6 compared with wild-type cells. Finally, high levels of IL-6 expression were observed in atherosclerotic lesions of vein bypass grafts, which are related to altered biomechanical stress. Our findings demonstrate that biomechanical stress-induced IL-6 expression occurs via a mechanism that involves Ras/Rac/p38 MAPK/NF-kappaB/NF-IL6 signaling pathways, which is downregulated by PKC-delta, and suggest that modulation of this event contributes to the pathogenesis of atherosclerosis.

Aspergillus infections in transplant recipients

Aspergillus infections are occurring with an increasing frequency in transplant recipients. Notable changes in the epidemiologic characteristics of this infection have occurred; these include a change in risk factors and later onset of infection. Management of invasive aspergillosis continues to be challenging, and the mortality rate, despite the use of newer antifungal agents, remains unacceptably high. Performing molecular studies to discern new targets for antifungal activity, identifying signaling pathways that may be amenable to immunologic interventions, assessing combination regimens of antifungal agents or combining antifungal agents with modulation of the host defense mechanisms, and devising diagnostic assays that can rapidly and reliably diagnose infections represent areas for future investigations that may lead to further improvement in outcomes.

Immunomorphological characteristics of animals with different levels of orientation and exploratory behavior

We revealed some relationships between the level of orientation and exploratory behavior, functional activity of the immune system, and structural and functional organization of the CNS in animals. Significant differences in brain morphology and expression of cytokine IL-1 beta, type I IL-1 receptor, and erythropoietin receptor genes in brain cells were detected in (CBA x C57Bl/6)F1 mice with different initial levels of orientation and exploratory behavior. Immunocompetent cells of mice with high and low levels of exploratory behavior differ by spontaneous and mitogen-induced proliferative activity. The formation of humoral and cellular immune response in these animals causes opposite changes in exploratory behavior and the type of these changes depends on the initial level of this behavioral reaction.

Nitric oxide synthesis contributes to inhibition of graft-versus-tumor-effects against intraperitoneal Meth A tumor

The role of nitric oxide (NO) in graft-versus-tumor-effect (GVT) was evaluated in the present study. GVT was induced by intravenous injection of C57BL/6J (H-2b) mouse splenocytes to {C57BL/6J (H-2b) x BALB/c (H-2d)} F1 mice bearing Meth A (H-2d) ascites tumors. Induction of GVT increased nitrite production and expression of inducible NO synthase by ascites cells. The increased nitrite production was inhibited by NG-monomethyl-L-arginine (MLA). Experiments employing immunomagnetic depletion of Mac-1+ cells from ascites indicated that macrophages were a major cellular source of the nitrite production. Interferon-gamma levels were increased in both serum and ascites fluid during GVT. Induction of GVT prolonged survival of ascites-bearing mice, and increased urinary nitrate excretion. MLA administration inhibited GVT-induced increase in urinary nitrate excretion, and further prolonged GVT-induced increase in survival. These results indicate that NO synthesis is induced in tumors during GVT, and the NO acts as an inhibitor of GVT.

Endogenous Nitric Oxide Protects against T Cell-Dependent Lethality during Graft-versus-Host Disease and Idiopathic Pneumonia Syndrome

The pathogenesis of idiopathic pneumonia syndrome (IPS), a noninfectious pulmonary complication of allogeneic bone marrow transplantation (BMT), has not been fully elucidated. However, several contributing factors have been proposed, including lung injury caused by reactive oxygen and nitrogen intermediates during preconditioning and development of graft-vs-host disease (GVHD). Studies on the role of reactive oxygen and nitrogen intermediates in IPS have yielded conflicting results. We have described a murine model of IPS, in which the onset of lung inflammation was delayed by several weeks relative to GVHD. This study evaluated whether the delay in onset of IPS was due to slow turnover of NO-producing, immunosuppressive alveolar macrophages (AM) following BMT. The results indicated that AM were immunosuppressive due to synthesis of NO. However, NO production and immunosuppressive activity by AM did not decline after BMT, but rather remained elevated throughout the 12-wk development of GVHD and IPS. In a 14-day model of IPS, continuous inhibition of NO with aminoguanidine (AG) reduced signs of IPS/GVHD, but also led to higher mortality. When AG treatment was initiated after onset of IPS/GVHD, rapid mortality occurred that depended on the severity of IPS/GVHD. AG-enhanced mortality was not due to inhibition of marrow engraftment, elevated serum TNF-alpha, liver injury, or hypertensive responses. In contrast, T cells were involved, because depletion of CD4(+) lymphocytes 24 h before AG treatment prevented mortality. Thus, NO production following allogeneic BMT affords a protective effect that helps down-regulate injury caused by T cells during GVHD and IPS.

Comparative analysis of clinical outcomes after allogeneic bone marrow transplantation versus peripheral blood stem cell transplantation from a related donor in Japanese patients

A reduced incidence of graft versus host disease (GvHD) has been documented among Japanese allogeneic bone marrow transplantation (BMT) patients, as the Japanese are genetically more homogeneous than western populations. To clarify whether this ethnic difference affects the results of allogeneic peripheral blood stem cell transplantation (PBSCT), we conducted a nationwide survey to compare clinical outcomes of allogeneic PBSCT (n = 214) and BMT (n = 295) from a human leucocyte antigen-identical-related donor in Japanese patients. The cumulative incidence of grades II-IV acute GvHD was 37.4% for PBSCT and 32.0% for BMT. The cumulative incidence of extensive chronic GvHD at 1 year was significantly higher after PBSCT than BMT (42% vs. 27%; P < 0.01). The organ involvement patterns of GvHD were different between the two groups. By multivariate analyses, the incidence of chronic GvHD was significantly increased in PBSCT, whereas the stem cell source did not affect the incidence of acute GvHD, transplant-related mortality, relapse or survival. We concluded that Japanese PBSCT patients have an increased risk of chronic GvHD compared with BMT patients, but the incidence of acute GvHD was still lower than in western populations. Thus, the choice of haematopoietic stem cell source should be considered based on data for individual ethnic populations.

Inhibition of calpain cleavage of huntingtin reduces toxicity: accumulation of calpain/caspase fragments in the nucleus

Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine (polyQ) tract expansion near the N terminus of huntingtin (Htt). Proteolytic processing of mutant Htt and abnormal calcium signaling may play a critical role in disease progression and pathogenesis. Recent work indicates that calpains may participate in the increased and/or altered patterns of Htt proteolysis leading to the selective toxicity observed in HD striatum. Here, we identify two calpain cleavage sites in Htt and show that mutation of these sites renders the polyQ expanded Htt less susceptible to proteolysis and aggregation, resulting in decreased toxicity in an in vitro cell culture model. In addition, we found that calpain- and caspase-derived Htt fragments preferentially accumulate in the nucleus without the requirement of further cleavage into smaller fragments. Calpain family members, calpain-1, -5, -7, and -10, have increased levels or are activated in HD tissue culture and transgenic mouse models, suggesting they may play a key role in Htt proteolysis and disease pathology. Interestingly, calpain-1, -5, -7, and -10 localize to the cytoplasm and the nucleus, whereas the activated forms of calpain-7 and -10 are found only in the nucleus. These results support the role of calpain-derived Htt fragmentation in HD and suggest that aberrant activation of calpains may play a role in HD pathogenesis.

Allogeneic reaction induces dendritic cell maturation through proinflammatory cytokine secretion1

BACKGROUND

A bone marrow transplantation conditioning regimen is known to activate host dendritic cells (DC), which then become able to initiate graft-versus-host disease (GVHD) by presenting alloantigens. In this article, the authors addressed whether the alloreaction could reciprocally maintain DC in an activation state through secretion of proinflammatory cytokines.

METHODS

Skin biopsy specimens from GVHD patients were analyzed for the presence of DC. Supernatants collected from primary major histocompatibility antigen (allogeneic mixed leukocyte reaction [MLR] supernatant [SN]) or secondary minor histocompatibility antigen-mismatched mixed lymphocyte reactions were used to culture cytokine-promoted immature (im) DC. DC phenotype, function, and migration were analyzed.

RESULTS

Immunostaining from GVHD skin biopsy specimens showed a deficit of Langerhans cells (LC) in the epidermis but the presence of mature DC in the dermis. Because LC should have recovered in the epidermis by this time, the authors then addressed whether the allogeneic reaction could maintain DC in an activation and migratory state, through secretion of inflammatory cytokines. With this aim, cytokine-mediated imDC were exposed to alloMLR-SN for 2 days. The authors observed that DC increased their expression of CD80, CD86, CD40, and human leukocyte antigen (HLA)-DR and neoexpressed CD83, DC-LAMP/CD208, and CCR7. At the functional level, alloMLR-SN-treated DC lost their ability to capture dextran, improved their allostimulatory capacity, and migrated in response to macrophage inflammatory protein 3beta. Interestingly, SN collected from secondary HLA-identical but minor histocompatibility antigen-mismatched MLR induced almost equivalent DC phenotypic maturation.

CONCLUSIONS

The authors' results show that the allogeneic reaction leads to maturation and migration of DC through proinflammatory cytokine secretion. This might contribute to the impairment of LC reconstitution in the skin of patients with GVHD.

Amelioration of graft versus host disease by galectin-1

Graft versus host disease is a significant cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation. Galectin-1, a mammalian lectin that modulates T cell function and apoptosis, has been shown to be immunomodulatory in animal models of autoimmune disease. We investigated the efficacy of galectin-1 in a murine model of graft versus host disease and found that 68% of galectin-1-treated mice survived, compared to 3% of vehicle-treated mice. Galectin-1-treated animals also had reduced inflammatory infiltrates in tissues compared to animals treated with vehicle alone. Galectin-1 did not affect engraftment of donor hematopoietic cells. However, galectin-1-treated animals demonstrated increased cellularity in bone marrow and spleen with increased numbers of splenic B cells and CD4 T cells compared to those animals treated with vehicle alone. Galectin-1 treatment also significantly improved reconstitution of normal splenic architecture following transplant. Production of type I cytokines interleukin-2 (IL-2) and interferon-gamma was reduced in splenocytes derived from galectin-1-treated transplanted mice when compared to animals treated with vehicle alone, while production of the type II cytokines, IL-4 and IL-10, was similar between the two groups of animals. Although splenocytes from galectin-1-treated transplanted animals responded to both third party antigens and leukemic challenge, host alloreactivity was significantly reduced when compared to cells from vehicle-treated animals. These results demonstrate that galectin-1 therapy is capable of increasing survival and suppressing the graft versus host immune response without compromising engraftment or immune reconstitution following allogeneic hematopoietic stem cell transplant.

Acute inflammatory response and remodeling of airway epithelium after subspecies B1 human adenovirus infection of the mouse lower respiratory tract

Despite the well-recognized role of adenoviruses of species B in the etiology of severe respiratory disease, the lack of an experimental in vivo model system has limited the understanding of the molecular pathogenesis of species B adenovirus-induced pneumonia. Intratracheal instillation of 5 x 10(8) plaque-forming units (pfu) of adenoviruses 3p and 7h resulted in a robust inflammatory response in the lungs of infected mice. A marked infiltration of neutrophils into the lung air spaces was observed at 1 and 2 days postinfection (dpi), with a concomitant increase in the levels of neutrophil chemokines MIP-2 and KC. The overall histological severity scores were significantly higher for Ad3p-infected mice at 2 dpi, but similar between the two viruses at other time points. Remodeling of the airway epithelia and mucous cell metaplasia were noted in the proximal airways of infected mice, indicating marked epithelial differentiation and/or injury. The proinflammatory cytokines interleukin-beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma [see symbol in text]), and interleukin-12 (IL-12) were induced by viral infection. Expression of the early viral immunomodulatory genes E3-15.3K and E3gp19K mRNA was readily detectable in the lungs of infected mice by reverse transcription-polymerase chain reaction (RT-PCR) at 1 and 2 dpi, coinciding with the peak levels of TNF-alpha. While the detection of gp19K mRNA declined thereafter, 15.3K mRNA was detectable up to 6 dpi. Our results indicate that human Ad3 and Ad7 cause marked pulmonary pathology, inducing similar host responses in the respiratory tract, thus validating the use of the mouse model for the study of early virus-host interactions during lung infection by adenoviruses of subspecies B1.

Allograft inflammatory factor-1 regulates trinitrobenzene sulphonic acid-induced colitis

The expression of allograft inflammatory factor-1 (AIF-1) in 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis, a model for T helper 1 (Th1) type disease, was investigated in BALB/c mice. The AIF-1 expression was significantly increased in the colitis lesion compared to that in the normal colon. We then prepared AIF-1 transgenic mice (Tgm) with the BALB/c background that express high levels of AIF-1 in lymphoid tissues and the colon. When AIF-1 Tgm were administrated TNBS, the TNBS-induced colitis was ameliorated compared with that in non-transgenic littermates. The amelioration of colitis was associated with the low expression of interleukin-1beta in the colon. The present findings suggest that AIF-1 regulates Th1-type inflammatory responses.

Early expression of interferon gamma following oral antigen administration is associated with peripheral tolerance induction

Oral tolerance is the induction of immune hyporesponsiveness to orally administered antigens. It was described in association with a decrease in interferon gamma (IFNgamma) production by activated T cells. To determine the role of IFNgamma and IL10 in immunemodulation via oral tolerization. Colitis was induced by intracolonic instillation of trinitrobenzene sulfonic acid. Treated mice received five oral doses of colitis-extracted proteins (CEPs) every other day, starting immediately after colitis induction. Control mice received similar doses of bovine serum albumin. Colitis was assessed in both groups by standard clinical, micro- and macroscopic scores. IFNgamma and IL10 expression in splenic lymphocytes from both groups was tested by RT-PCR immediately after oral feeding, 1, 4, 8, 12, and 24 h thereafter and then every 24 h for 2 weeks. Feeding of CEPs markedly ameliorated experimental colitis. These mice gained weight and showed markedly improved macro- and microscopic parameters of colitis. Tolerized mice exhibited IFNgamma expression in splenic lymphocytes starting immediately following oral CEP immunization and up to 14 d thereafter. IL10 was expressed starting 1 h after CEP feeding and during the first 48 h thereafter. In contrast, non-tolerized control mice manifested IFNgamma expression starting on day 6 and had no IL10 expression. Early induction of IFNgamma expression by oral antigen may be associated with systemic tolerance in the experimental colitis setting. In contrast, late expression of IFNgamma is associated with a pro-inflammatory response in non-tolerized controls.

In vivo evidence for interferon-gamma-mediated homeostatic mechanisms in small intestine of the NHE3 Na+/H+ exchanger knockout model of congenital diarrhea

Mice lacking NHE3, the major absorptive Na(+)/H(+) exchanger in the intestine, are the only animal model of congenital diarrhea. To identify molecular changes underlying compensatory mechanisms activated in chronic diarrheas, cDNA microarrays and Northern blot analyses were used to compare global mRNA expression patterns in small intestine of NHE3-deficient and wild-type mice. Among the genes identified were members of the RegIII family of growth factors, which may contribute to the increased absorptive area, and a large number of interferon-gamma-responsive genes. The latter finding is of particular interest, since interferon-gamma has been shown to regulate ion transporter activities in intestinal epithelial cells. Serum interferon-gamma was elevated 5-fold in NHE3-deficient mice; however, there was no evidence of inflammation, and unlike conditions such as inflammatory bowel disease, levels of other cytokines were unchanged. In addition, quantitative PCR analysis showed that up-regulation of interferon-gamma mRNA was localized to the small intestine and did not occur in the colon, spleen, or kidney. These in vivo data suggest that elevated interferon-gamma, produced by gut-associated lymphoid tissue in the small intestine, is part of a homeostatic mechanism that is activated in response to the intestinal absorptive defect in order to regulate the fluidity of the intestinal tract.

SSR125329A, a high affinity sigma receptor ligand with potent anti-inflammatory properties

SSR125329A ([(Z)-3-(4-Adamantan-2-yl-3,5-dichloro-phenyl)-allyl]-cyclohexyl-ethyl-amine) is a new ligand exhibiting high affinity for sigma(1) and sigma(2) receptors and for the human Delta8-Delta7-sterol isomerase. Here we show that this molecule has potent immunoregulatory properties both in vitro and in vivo. SSR125329A inhibited staphylococcal enterotoxin B-induced mouse splenocyte proliferation in vitro, whereas in vivo it enhanced lipopolysaccharide-induced systemic release of interleukin-10 while simultaneously inhibiting tumor necrosis factor-alpha (TNF-alpha) synthesis. It also prevented graft-versus-host disease in B6D2F1 mice and protected Mrl/lpr mice against the development of its spontaneous rheumatoid-like syndrome. There is high interplay of pro- and anti-inflammatory cytokines in inflammatory processes, particularly in human rheumatoid arthritis. The results of this study provide substantial evidence that sigma receptor ligands may represent a new effective approach for rheumatoid arthritis treatment.