Guro Kristin Melve

The Pretransplantation Serum Cytokine Profile in Allogeneic Stem Cell Recipients Differs from Healthy Individuals, and Various Profiles are Associated with Different Risks of Posttransplantation Complications

Cytokines play a key role in regulation of normal and malignant hematopoiesis, angiogenesis, and inflammation. Serum levels of several cytokines are altered in patients with hematologic malignancies, and pretransplant cytokine levels seem to have a prognostic impact in patients treated with allogeneic stem cell transplantation. However, the cytokine system constitutes an interacting functional network, and it may therefore be more relevant to look at serum cytokine profiles rather than the serum levels of single cytokines in allotransplanted patients. We therefore investigated the pretransplantation serum levels of 35 cytokines in a group of 44 consecutive allogeneic stem cell transplantation patients, mainly with a primary diagnosis of acute leukemia. Serum samples were collected before the start of myeloablative conditioning therapy when all patients were in complete hematologic remission. Unsupervised hierarchical clustering analysis identified three major patient groups/subsets. These groups differed especially in the levels of hepatocyte growth factor and granulocyte-colony stimulating factor, and one of the groups was characterized by low early treatment-related morbidity and high levels of hepatocyte growth factor and granulocyte-colony stimulating factor. The degree of weight gain/fluid retention after conditioning therapy did not differ between the patient subsets, but fluid retention showed a significant correlation with pretransplantation serum levels of basic fibroblast growth factor. We conclude that the pretransplantation serum cytokine profile shows a considerable variation even between patients in complete hematologic remission and is associated with clinicopathologic features.

The chemokine system in allogeneic stem-cell transplantation: a possible therapeutic target?

Further improvements in allogeneic stem-cell transplantation will probably depend on a better balance between immunosuppression to control graft-versus-host disease and immunological reconstitution sufficient to ensure engraftment, reduction of infection-related mortality and maintenance of post-transplant antileukemic immune reactivity. The chemokine network is an important part of the immune system, and, in addition, CXCL12/CXCR4 seem to be essential for granulocyte colony-stimulating factor-induced stem-cell mobilization. Partial ex vivo graft T-cell depletion based on the expression of specific chemokine receptors involved in T-cell recruitment to graft-versus-host disease target organs may also become a future therapeutic strategy; an alternative approach could be pharmacological inhibition (single-receptor inhibitors or dual-receptor inhibitors) in vivo of specific chemokine receptors involved in this T-cell recruitment. Future clinical studies should therefore be based on a better characterization of various immunocompetent cells, including their chemokine receptor profile, both in the allografts and during post-transplant reconstitution.

Hyperleukocytosis and leukocytapheresis in acute leukaemias: experience from a single centre and review of the literature of leukocytapheresis in acute myeloid leukaemia

Hyperleukocytosis is usually defined as leukocyte count >100 × 109 L−1 and can be seen in newly diagnosed leukaemias. Hyperleukocytic leukaemia is associated with a risk of organ failure and early death secondary to leukostasis. Mechanical removal of leukocytes by the apheresis technique, leukocytapheresis, is a therapeutic option in these patients.

Future perspectives: should Th17 cells be considered as a possible therapeutic target in acute myeloid leukemia patients receiving allogeneic stem cell transplantation?

Th17 cells seem to promote proinflammatory effects, and their development seems to depend on intracellular signaling initiated by IL1β, supported by IL6 and IL23 and mediated by STAT3 and RORC2. Even though primary human AML cells may affect Th17 development through their constitutive cytokine release, the levels of circulating Th17 cells in older patients with untreated AML do not differ from healthy controls and show only minor variations during and following conventional intensive chemotherapy. IL17-A is the signature cytokine of Th17 cells, but in vitro studies have failed to demonstrate a direct antileukemic effect of IL17 on primary human AML cells for most patient samples. However, several observations suggest that Th17 cells mediate antileukemic effects through other mechanisms and are important in allogeneic stem cell transplantation. Firstly, genetic variants in IL23/Th17 pathway have a prognostic impact with regard to both development of GVHD and posttransplant infections. Secondly, circulating IL17-secreting cells are detected during early posttransplant pancytopenia, and their ability to release IL17 is associated with later GVHD. Thirdly, a high number of Th17 cells in allogeneic stem cell grafts are associated with later acute GVHD, levels of circulating Th17 cells are increased at the onset of acute GVHD, and these levels normalize during treatment. In the present article, we review previous studies of Th17 cells in AML and in the development of GVHD, possible therapeutic strategies and available therapeutic tools for targeting of Th17 cells.

Is there a scientific basis for a recommended standardization of collection and cryopreservation of peripheral blood stem cell grafts

High-dose chemotherapy followed by autologous stem cell transplantation has been used extensively during the last two decades in the treatment of hematologic malignancies. The vast majority of recent transplantations have been performed using mobilized peripheral blood stem cells, because they have become the preferred source of hematopoietic cells rather than bone marrow stem cells. The mobilization is achieved by growth factors, eventually combined with chemotherapy, and the cells are then harvested and cryopreserved until reinfusion. Despite extensive use for many years, few attempts have been made to standardize the various steps in mobilization, harvesting and cryopreservation. Furthermore, the autografts only represent relative stem cell enrichment and contain a wide range of more mature hematopoietic and immunocompetent cells; the potential clinical importance of these normal cells is largely unknown and represents an additional non-standardized factor in this treatment. We have reviewed the various methodologic approaches for stem cell mobilization, collection and cryopreservation of autografts with a special focus on the cryopreservation procedures, immunocompetent cells in the graft, and cytokine content of the graft supernatant. We conclude that the factors/aspects mentioned above should be standardized in future clinical studies of autotransplantation for human hematologic malignancies. Alternatively, detailed methodologic descriptions should be required when the results are published. Standardization of autograft preparation and cryopreservation will be achieved if/when transplantation units assess and adopt new standards based not only on the technology but, more importantly, on the quality of evidence and data related to that technology/methodology.

Effects of peripheral blood stem cell apheresis on systemic cytokine levels in patients with multiple myeloma.

BACKGROUND AIMS. Pro-angiogenic cytokines can affect myeloma cell proliferation directly and indirectly through stimulation of cancer-associated angiogenesis. METHODS. We investigated how peripheral blood stem cell (PBSC) collection affected plasma angioregulatory cytokine levels in 15 consecutive myeloma patients. RESULTS. Plasma levels of hepatocyte growth factor (HGF) were significantly increased prior to apheresis in patients compared with donors, and a further increase was detected immediately after PBSC apheresis. HGF levels decreased within 24 h, but were still higher than the levels in healthy donors, whose HGF levels were not altered by platelet apheresis. Pre-apheresis levels of other angioregulatory cytokines, angiopoietin-2 and vascular endothelial growth factor (VEGF), were also increased in patients, whereas angiopoietin-1, angiogenin and basic fibroblast growth factor levels did not differ from healthy controls. PBSC harvesting decreased angiopoietin-1 and VEGF levels, increased the microvascular endothelial cell marker endocan levels but did not affect the other mediators. CONCLUSIONS. Our results show that PBSC apheresis alters systemic angioregulatory profiles in myeloma patients. This cytokine modulation is not a general characteristic of all apheresis procedures and was not seen in healthy platelet donors.

Targeted anti-leukemic therapy as disease-stabilizing treatment for acute myeloid leukemia relapse after allogeneic stem cell transplantation: Will it be possible to combine these strategies with retransplantation or donor lymphocyte infusions?

Allogeneic stem cell transplantation is commonly used in the treatment of high-risk acute myeloid leukemia (AML). This intensive treatment has a high early transplant-related mortality, and an additional significant cause of death in these patients is later AML relapse. Retransplantation can be considered for a minority of patients, but only 10-20% of selected patients then achieve long-term survival. Donor lymphocyte infusion (DLI) has an antileukemic effect, but the effect of this treatment usually lasts for only 3-4 months. A possible strategy to improve the prognosis could be to combine antileukemic T-cell therapy (i.e. DLI) with AML-targeting therapy. Several aspects have to be considered for such approaches: (i) the therapy should have immunomodulatory rather than immunosuppressive effects; (ii) the regimen should have a low hematological toxicity to preserve residual normal bone marrow function; and (iii) the treatment should have a documented antileukemic effect. DLI elicit both graft versus host and graft versus leukemia effects, and could be added to pharmacological treatment. Epigenetic targeting should be considered in these patients because both demethylating agents as well as the histone deacetylase inhibitors have documented antileukemic effects and have a relatively low hematological toxicity. Other drugs to consider are thalidomide, lenalidomide, antiangiogenic agents, tyrosine kinase inhibitors and heat shock protein 90 inhibitors, which all have both antileukemic and immunomodulatory effects. Relatively few clinical studies are available for patients with this high-risk disease. The designs of future clinical trials have to carefully consider the antileukemic and immunomodulatory effects together with the risk of especially hematological toxicity.

Evaluation of the persistence and characteristics of indeterminate reactivity against hepatitis C virus in blood donors

BACKGROUND: A substantial number of individuals are excluded from blood donation due to indeterminate results in screening tests for hepatitis C virus antibody (anti‐HCV). Disclosure of the characteristics of the indeterminate serologic pattern could optimize the testing and the management and care of blood donors.

Stem cell mobilization and harvesting by leukapheresis alters systemic cytokine levels in patients with multiple myeloma

BACKGROUND AIMS Stem cell mobilization and harvesting by peripheral blood leukapheresis in patients with myeloma can alter plasma levels of certain cytokines. In the present study, we investigated the effects of these interventions on a larger group of cytokines. METHODS Plasma cytokine levels were determined in 15 patients with myeloma who were undergoing peripheral blood stem cell harvesting, and we compared the patients with healthy donors who were undergoing platelet apheresis. RESULTS Several cytokines showed altered levels in patients with myeloma when examined after chemotherapy plus granulocyte colony-stimulating factor-induced stem cell mobilization. The most striking effect was increased levels of several CCL (CCL2/3/4) and CXCL (CXCL5/8/10/11) chemokines as well as increased thrombopoietin, interleukin 1 receptor antagonist, interleukin-4, granulocyte colony-stimulating factor and hepatocyte growth factor. Stem cell harvesting by apheresis altered the plasma levels of several mediators (CD40 ligand, interleukin 1 receptor antagonist, CCL5 and CXCL5/8/10/11). Apheresis in patients with myeloma had divergent effects on these chemokine levels, although they were all still significantly higher than for healthy individuals. Thrombapheresis in healthy individuals had only minor effects on plasma cytokine levels. Stem cell graft supernatants showed high levels of several cytokines, especially CCL and CXCL chemokines. Analyses of chemokine profiles in pre-apheresis plasma and graft supernatants suggested that such profiling can be used to detect prognostically relevant differences between patients. CONCLUSIONS Our results demonstrate that patients with myeloma have an altered cytokine network during stem cell mobilization, and the network is further altered during stem cell harvesting by leukapheresis. These treatment- or procedure-induced alterations involve several mediators known to affect myeloma cell proliferation, migration and survival.

Peripheral blood stem cell mobilization in healthy Donors by granulocyte colony-stimulating factor causes preferential mobilization of lymphocyte subsets

Background Allogeneic hematopoietic stem cell transplantation is associated with a high risk of immune-mediated post-transplant complications. Graft depletion of immunocompetent cell subsets is regarded as a possible strategy to reduce this risk without reducing antileukemic immune reactivity. Study design and methods We investigated the effect of hematopoietic stem cell mobilization with granulocyte colony-stimulating factor (G-CSF) on peripheral blood and stem cell graft levels of various T, B, and NK cell subsets in healthy donors. The results from flow cytometric cell quantification were examined by bioinformatics analyses. Results The G-CSF-induced mobilization of lymphocytes was a non-random process with preferential mobilization of naïve CD4+ and CD8+ T cells together with T cell receptor αβ+ T cells, naïve T regulatory cells, type 1 T regulatory cells, mature and memory B cells, and cytokine-producing NK cells. Analysis of circulating lymphoid cell capacity to release various cytokines (IFNγ, IL10, TGFβ, IL4, IL9, IL17, and IL22) showed preferential mobilization of IL10 releasing CD4+ T cells and CD3−19− cells. During G-CSF treatment, the healthy donors formed two subsets with generally strong and weaker mobilization of immunocompetent cells, respectively; hence the donors differed in their G-CSF responsiveness with regard to mobilization of immunocompetent cells. The different responsiveness was not reflected in the graft levels of various immunocompetent cell subsets. Furthermore, differences in donor G-CSF responsiveness were associated with time until platelet engraftment. Finally, strong G-CSF-induced mobilization of various T cell subsets seemed to increase the risk of recipient acute graft versus host disease, and this was independent of the graft T cell levels. Conclusion Healthy donors differ in their G-CSF responsiveness and preferential mobilization of immunocompetent cells. This difference seems to influence post-transplant recipient outcomes.