Increased levels of immune transcript in patients with acute GVHD after allogeneic stem cell transplantation

Recombinant CD95-Fc (APG101) prevents graft-versus-host disease in mice without disabling antitumor cytotoxicity and T-cell functions

Graft-versus-host disease (GVHD) induced by transplant-derived T cells represents a major complication after allogeneic bone marrow transplantation (BMT). However, these T cells support engraftment, early T-cell immunity, and mediate the graft-versus-tumor (GVT) effect. Cytotoxic effector functions by transplanted T cells are predominantly mediated by the perforin/granzyme and the CD95/CD95L system. APG101, a novel recombinant human fusion protein consisting of the extracellular domain of CD95 and the Fc domain of an IgG1 antibody inhibited CD95L-induced apoptosis without interfering with T-cell function in vitro and was therefore tested for its ability to prevent GVHD in murine BMT models across minor or major histocompatibility barriers. Starting APG101 treatment either 1 day before or 6 days after transplantation effectively reduced clinical GVHD and rescued survival between 60% and 100% if GVHD was CD95L mediated. APG101 did not interfere with the GVT effect, because P815 mastocytoma and most importantly primary Bcr-Abl-transformed B-cell leukemias were completely eradicated by the alloantigen-specific T cells. Phenotype and homing of alloantigen-specific T cells or their perforin/granzyme-mediated cytotoxicity and proliferative capacity were not affected by APG101 treatment suggesting that APG101 therapy might be useful in GVHD prophylaxis without impairing T-cell function and most importantly preserving GVT activity.

G-CSF induces a potentially tolerant gene and immunophenotype profile in T cells in vivo

G-CSF can induce functional immune tolerance in man. In this study, purified T cells from G-CSF-mobilized peripheral blood stem cell (PBSC) donors were analysed by gene expression profiling and immunophenotyping. Results suggested a predominantly immune tolerant profile with upregulation of genes related to Th2 and Treg cells, downregulation of genes associated with Th1 cells, cytotoxicity, antigen presentation and graft-versus-host disease (GVHD) and overexpression of negative regulators of Th17 differentiation. Immunophenotyping revealed that during G-CSF exposure donors had reduced levels of T cells with a Th17 phenotype (CD4+IL-17A+CCR6+IL-23R+), more than three times lower compared to normal controls. G-CSF also led to increased levels of CD4+CD25highCD45RO+ Treg cells. Furthermore, mRNA levels of RORgammat, a Th17-specific transcription factor, decreased in T cells isolated from G-CSF-mobilized PBSC harvests. Th17 cells have been implicated in autoimmune diseases and GVHD pathophysiology. Our study is the first to report the effect of G-CSF on the Th17 subpopulation.

Granzymes A and B serum levels in allo-SCT

Activated cytotoxic T lymphocytes and natural killer cells, which are involved in the pathogenesis of GVHD and viral infections after SCT produce granzymes (Grs). This study performed an ELISA in the serum of 86 patients at various time points before and after Allo-SCT to investigate GrA and GrB levels as potential markers for these serious complications. The increase in Gr levels from the day of transplantation until the appearance of the complication was highly predictive. If GrA increased to three times its pretransplant level, the cumulative incidence of developing acute GVHD was 73% and for CMV infection 68%, in comparison with 45 and 35%, respectively, for patients without these complications. A strong increase in GrA level correlated with clinical severity of acute GVHD. No correlation was observed with early relapse or long-term overall survival. In addition to clinical parameters, a strong increase in GrA levels was identified as an independent marker for the occurrence of acute GVHD as well as for CMV infection. Similar effects were observed with GrB. In conclusion, Gr protein levels can also be used as a marker for complications after Allo-SCT.

Evaluation of angiopoietins and cell-derived microparticles after stem cell transplantation

Although stem cell transplantation (SCT) is being used for hematopoietic reconstitution following high-dose chemotherapy for malignancy, it involves certain serious transplant-related complications such as graft-versus-host disease (GVHD). Angiopoietins play important roles in angiogenesis. However, the role of angiopoietins after SCT is poorly understood. In this study, 52 patients underwent SCT; 26 patients received allogeneic SCT, while the remaining 26 received autologous SCT. In 48 of 52 patients, levels of angiopoietins, cytokines, and soluble factors were measured by enzyme-linked immunosorbent assay. Soluble Fas ligand (sFasL) and endothelial cell-derived microparticle (EDMP) exhibited significant elevation in the early phase (2-3 weeks) after SCT. In addition, the elevation of interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, and sIL-2 receptor (sIL-2R), which are GVHD markers after allogeneic SCT was observed. The level of angiopoietin (Ang)-2 in allogeneic SCT continued to increase for up to 4 weeks, although the level of Ang-1 did not show significant changes. The patients with high Ang-2 exhibited significant increase of sFasL and EDMP compared with those with low Ang-2. In addition, the patients with high-grade GVHD exhibited a significant increase in Ang-2 compared to patients with low-grade GVHD. In the in vitro experiment using endothelial cells, the suppressive effect of Ang-1 on EDMP generation by TNF-alpha was partially inhibited by the addition of Ang-2. Furthermore, multivariate regression analysis showed that EDMP and sFasL were significant factors in Ang-2 elevation. Our results suggest that Ang-2 generation after allogeneic SCT relates to GVHD.

Pediatric myelodysplastic syndromes

A new classification of myelodysplastic and myeloproliferative diseases in childhood has greatly facilitated the diagnosis of these uncommon disorders. Because hematopoietic stem cell transplantation (HSCT) can cure more than half of the affected children, palliative treatment strategies often applied in adult myelodysplastic syndrome (MDS) are of little importance in pediatric MDS. Unraveling some of the underlying genetic factors predisposing to MDS at a young age may give important insights into leukemogenesis in the elderly.

The role of IL-4 and IL-12 in the regulation of collagen synthesis by fibroblasts

Chronic sclerodermifomic graft versus host disease is a rare but important complication of allogeneic hematopoietic stem cell transplantation that especially occurs in patients who are treated with donor lymphocyte infusions for relapse of a malignant disease. Today most knowledge about the pathogenesis of chronic Graft-versus-Host Disease is based on mice models. In this report we describe the development of an allogeneic in vitro model that allows studying the pathogenesis of chronic sclerodermifomic Graft-versus-Host Disease in the human setting. We report that priming of mononuclear cells in the presence of allogeneic fibroblasts and Interleukin (IL)-4 induces fibroblast collagen synthesis, whereas priming in the presence of IL-12 suppresses collagen synthesis during subsequent coculture of primed mononuclear cells with allogeneic fibroblasts. Since IL-12 is also known to mediate anti-tumor effects by stimulation of Natural Killer cell and Lymphokine Activated Killer cell activity, these findings indicate that treatment of patients with IL-12 or pretreatment of donor lymphocytes with IL-12 might strengthen a graft versus leukemia effect and at the same time decrease the risk of chronic sclerodermifomic Graft-versus-Host Disease development.

Distinct patterns of regeneration of central memory, effector memory and effector TCD8+ cell subsets after different hematopoietic cell transplant types: Possible influence in the recovery of anti-cytomegalovirus immune response and risk for its reactivation

TCD8+ cells may be divided into subsets with different phenotypes and functions: naive, central memory, effector memory and effector. Aiming to better understand the differences in early reconstitution of these TCD8+ cell subsets and their relationship with post-transplant anti-cytomegalovirus (CMV) immune responses recovery, we prospectively analyzed the transfer and expansion of these subsets in different transplant types. We found that graft cells from donor's peripheral blood, either allogeneic or autologous, were enriched for central memory, effector memory and effector phenotypes compared to allogeneic bone marrow grafts, as assessed by surface markers phenotyping and granzyme B expression. However, post-transplant, these subsets expanded in autologous recipients only, reaching numbers much greater than in allo-recipients at days +29 and +96. At the same time, autologous recipients presented less CMV reactivation and more vigorous CMV-induced interferon-gamma and lymphoproliferative responses. The marked loss of allo-transferred memory TCD8+ cells was probably due to the fact that they were more activated and more prone to apoptosis than auto-transferred TCD8+ cells as assessed by CD69 and active caspase 3 expression. Thus, transfer of peripheral blood stem cells in the allogeneic but not autologous setting is associated with poor expansion of memory TCD8+ cells, probably delaying antiviral immune reconstitution. These data may have important implications for the design of better strategies to immunoprotect this population against infectious challenges since different transplant types have different potentials for memory TCD8+ cells transfer and expansion.

Cytokine Gene Expression in Peripheral Blood Mononuclear Cells and Alloreactivity in Hematopoietic Cell Transplantation with Nonmyeloablative Conditioning

Cytokines are thought to play an important role in the pathophysiology of graft-versus-host disease (GVHD). To study the relationship between cytokines and GVHD, we obtained peripheral blood mononuclear cells (MNCs) from 21 patients with hematologic malignancies and their HLA-identical sibling donors before and sequentially after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning. The MNCs were cultured for 72 hours either alone or in mixed lymphocyte cultures with irradiated MNCs of recipient, donor, or HLA-mismatched third-party origin. The gene expression of interleukin (IL)-2, IL-4, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta in each culture was then measured by real-time quantitative reverse transcriptase-polymerase chain reaction. The composition of the responder MNCs differed between patients and donors and changed after HCT, with a possible influence on the results. Early after transplantation (day +14), the IL-10 messenger RNA (mRNA) level in response to recipient or donor antigens was higher in patients who did not develop clinically significant acute GVHD when compared with the level in patients who subsequently developed acute GVHD grades II to IV (P = .005 and P = .004, respectively). The IL-10 mRNA level on day +14 was highly correlated with the pretransplantation mRNA level of the recipient MNCs but not with the level of the donor MNCs; this suggests that the IL-10 mRNA detected on day +14 originated from responder cells of recipient origin. A higher IL-10 mRNA level was found in MNCs obtained before transplantation from recipients whose disease progressed or relapsed after the transplantation when compared with the level in patients whose disease did not progress or relapse (P = .03). In conclusion, a high IL-10 gene expression in the recipient MNCs may be related to a reduced incidence of acute GVHD grades II to IV and a reduced graft-versus-tumor effect after HCT with nonmyeloablative conditioning.

The Pathophysiology of Acute Graft-Versus-Host Disease

Despite improvements in allogeneic stem cell transplantation, acute graft-versus-host disease (GVHD) remains a significant problem after transplantation, and it is still a major cause of post-transplant mortality. Disease progression is characterized by the differentiation of alloreactive T cells to effector cells leading to tissue damage, recruitment of additional inflammatory cell populations and further cytokine dysregulation. To make the complex process of acute GVHD more explicit, the pathophysiology of acute GVHD is often divided into three different phases. This review summarizes the mechanisms involved in the three phases of acute GVHD.

Differential Expression of Proteinase Inhibitor-9 and Granzyme B mRNAs in Activated Immunocompetent Cells

The role of proteinase inhibitor (PI)-9 in hematopoietic cells remains unclear. To clarify the role of PI-9 in these cells, we compared the expressions of PI-9 mRNA and antigen with those of granzyme B (GrB). While the strongest expression of PI-9 mRNA was observed in a NK cell line YT-N10, it was also expressed in a B-acute lymphoblastic leukemia cell line U-Tree02, an Epstein-Barr Virus (EBV)-transformed B cell clone, a CD8+ T lymphocyte clone and a megakaryocytic cell line CMK, but not in a T cell line Jurkat. Phorbol 12-myristate 13 acetate (PMA) enhanced PI-9 mRNA expression in the CD8+ T lymphocyte clone and YT-N10 cells prior to GrB mRNA expression. IL-2 and IL-12 also had similar effects. PMA increased PI-9 mRNA expression in the EBV-transformed B cell clone and CMK cells, but IL-6 showed no effect. No changes were noted in PI-9 and GrB antigens after the addition of these agonists. Patients with graft-versus-host disease (GVHD) may have activated CTLs and NK cells. We therefore examined the expression of PI-9 and GrB mRNAs in eight patients after allogeneic hematopoietic stem cell transplantation with GVHD (n = 4) or without chronic GVHD (n = 4). Expression of GrB mRNA was significantly increased in three patients with GVHD and one patient without GVHD. Surprisingly, PI-9 mRNA expression was decreased in the eight patients. These results indicate that earlier synthesis of PI-9 may be essential for the prevention of autolysis of immunocompetent cells, and that the expression of PI-9 and GrB mRNAs may be controlled through different pathways.

Adult porcine islets produce MCP-1 and recruit human monocytes in vitro

Type 1 diabetes can be cured by transplantation of isolated pancreatic islets. Because of the shortage of human donor tissue, adult porcine islets (APIs) constitute a possible alternative tissue source. Upon intraportal injection, islets are subjected to an instant blood-mediated inflammatory reaction (IBMIR) leading to blood clotting, leukocyte islet-infiltration, islet damage and insulin release. Xenogeneic islets surviving IBMIR are rejected in a cellular process involving CD4(+) T lymphocytes and macrophages. We have investigated whether APIs themselves produce and secrete chemokines and/or inflammatory cytokines that may contribute to IBMIR and/or cell-mediated rejection. APIs, cultured for 1, 4, 8 and 11 days post-isolation, expressed mRNA for monocyte chemoattractant protein-1 (MCP-1), IL-1beta and TNF-alpha. API culture supernatants induced migration of human monocytes, which was significantly blocked by an anti-human MCP-1 antibody (Ab). Immunohistochemistry revealed MCP-1 in the cytoplasm of alpha- and beta-cells in isolated islets and in islets in situ. However, APIs or their supernatants were not able to activate human aortic endothelial cells (HAECs) in vitro, and neither IL-1beta nor TNF-alpha were detected by enzyme-linked immunosorbent assay (ELISA) in API culture supernatants. Both recombinant porcine IL-1beta and TNF-alpha were able to activate human endothelial cells (ECs) inducing CD62E and CD106 expression as analyzed by flow cytometry. In conclusion, MCP-1 secreted by APIs may contribute to both IBMIR and rejection by attracting monocytes into the islet; monocytes which upon transformation into macrophages will potentiate antigen presentation and execute islet rejection.

Towards functional transplant donor matching by measurement of granzyme A and granzyme B production levels

Graft-versus-host disease (GvHD) can be a major complication after allogeneic stem cell transplantation (SCT) especially when donor and recipient are unrelated. The latter serious complication, together with the growing number of available unrelated stem cell donors, demand a simple in vitro assay for functional stem cell donor selection. Activated donor cytotoxic T lymphocytes (CTLs) and natural killer cells produce granzymes (Gr) that are involved in the pathogenesis of GvHD. We measured granzymes A and B (GrA and GrB) production levels in the supernatants of 96 h pretransplant mixed lymphocyte cultures (MLC) of 26 sibling and 31 unrelated patient/donor pairs by enzyme-linked immunosorbent assay (ELISA). In detail, the GrA and GrB production levels from a selected cohort of 37 potential patient/donor pairs were correlated with relative responses (RR) of MLC and with human leukocyte antigen (HLA) class II mismatches and with the development of acute GvHD in a second, consecutive cohort of 20 sibling SCT recipients. In vitro measurement of GrA and GrB production levels significantly correlated with the RR of pretransplant MLC (r=0.492, p< or =0.01 and r=0.853, p< or =0.01, respectively) and increased with the number of HLA class II mismatches between patient and donor. Pretransplant GrA production levels were significantly associated with the in vivo development of acute GvHD grades II-IV in patients transplanted with an HLA-identical sibling donor (p< or =0.001). In conclusion, in vitro GrA and GrB production levels can be measured by a quantitative and sensitive ELISA. This novel and simple method may be used for functional selection of unrelated stem cell donors and for the identification of patients who are at risk for acute GvHD grades II-IV.

Increased immune transcript levels are correlated with acute graft-versus-host disease and cytomegalovirus response after allogeneic stem cell transplantation

BACKGROUND

Donor T cells are primarily responsible for graft-versus-host disease (GVHD). Three effector pathways have been described for T-cell cytotoxicity: granzyme B/perforin, Fas/Fas ligand (FasL), and secreted molecules such as tumor necrosis factor (TNF)-alpha. Therefore, this study evaluates the gene expression pattern in the peripheral blood of patients after allogeneic stem cell transplantation and correlates the results to acute GVHD.

METHODS

Real-time quantitative reverse transcriptase-polymerase chain reaction was used to quantify the gene expression of granzyme B, perforin, FasL, and TNF-alpha in peripheral blood from 53 patients.

RESULTS

Samples were available from 27 of the 38 patients with acute GVHD diagnoses. Increased gene expression (>50%) during acute GVHD was detected in 23 of 27, 26 of 27, and 24 of 27 patients for granzyme B, perforin, and FasL, respectively. TNF-alpha showed a diffuse correlation. The median increases were as follows: granzyme B, 7.2x (1.6-183.2); perforin, 5.8x (1.6-254.9); and FasL, 8.5x (1.5-895.6). We also showed that all of the 10 patients with increasing levels of granzyme B, perforin, and FasL during steroid treatment demonstrated persistent or deteriorating GVHD. Patients with increasing transcription levels during cytomegalovirus (CMV) reactivation responded significantly better to therapy than those with declining levels. A total of 13 of 17 patients with increasing levels versus 0 of 11 patients with decreasing levels responded well to CMV treatment (P<0.01).

CONCLUSION

Although not specific for acute GVHD, quantitative assessment of immune transcripts may be of value in diagnosing and monitoring acute GVHD. It may also serve as a guide for the clinician in detecting patients who respond poorly to CMV therapy.