Noriyuki Mitani

Donor cell-derived acute myeloid leukemia after unrelated umbilical cord blood transplantation

Donor cell-derived acute myeloid leukemia after unrelated umbilical cord blood transplantation

The anti-apoptotic role of the unfolded protein response in Bcr-Abl-positive leukemia cells

To define the role of the unfolded protein response (UPR) in leukemogenesis, we investigated UPR activation in the cells expressing the representative oncogene Bcr-Abl (B-A). The expression of UPR-related proteins and mRNAs, namely, X-box-binding protein (XBP1) and glucose-regulated protein 78 (GRP78) was increased in B-A. UPR inhibition using inositol-requiring enzyme 1alpha (IRE1alpha) or activating transcription factor 6 (ATF6) dominant-negative mutants diminished the ability of Bcr-Abl to protect the cells from etoposide- and imatinib-induced apoptosis. We also noted that the expression of UPR-related genes in primary leukemia cells from Philadelphia chromosome (Ph)-positive cells was higher than that in the control by quantitative RT-PCR assay. Thus, our results suggested that UPR is a downstream target of Bcr-Abl and plays an anti-apoptotic role in Ph-positive leukemia cells.

Elevation of serum high‐mobility group box 1 protein during granulocyte colony‐stimulating factor‐induced peripheral blood stem cell mobilisation

High mobility group box 1 (HMGB1) is a non‐histone protein involved in maintaining the architecture of chromatin. HMGB1 also acts extracellularly as a cytokine, in processes such as inflammation, cell migration and stem cell recruitment. The involvement of HMGB1 in granulocyte colony‐stimulating factor (G‐CSF)‐induced mobilisation of haematopoietic stem cells was investigated in 21 healthy donors. G‐CSF treatment significantly elevated serum HMGB1 levels, which increased from 1·16 ± 0·86 ng/ml, before treatment, to 31·1 ± 5·99 ng/ml, after treatment. These findings suggest HMGB1 may play a role during the mobilisation of stem cells from the bone marrow into the systemic circulation.

Increased serum levels of high‐mobility group box 1 protein in patients who developed acute graft‐versus‐host disease after allogeneic hematopoietic stem cell transplantation

To the Editor: High-mobility group box protein 1 (HMGB1) is a nonhistone nuclear protein that performs a dual function. Inside the cell, HMGB1 binds DNA, regulates transcription, and determines chromosomal architecture. Outside the cell, HMGB1 activates the innate immune system and mediates a wide range of physiological and pathological responses (1). HMGB1 is released when cells are damaged. It is also actively released from monocytes or macrophages exposed to lipopolysaccharide (LPS), proinflammatory cytokines, or nitric oxide. HMGB1 reportedly transmits signals via Toll-like receptor (TLR)2, TLR4, TLR9, and the receptor for advanced glycation end-products (2). Acute graft-versus-host disease (aGVHD) is the major cause of morbidity and mortality in patients who have undergone allogeneic hematopoietic stem cell transplantation (HSCT). The pathophysiology of aGVHD can be considered to be a three-step process involving the interaction of the innate and adaptive immune systems: (I) tissue damage to the recipient as a result of the radiation ⁄ chemotherapy pretransplant conditioning regimen, (II) donor T-cell activation and clonal expansion, and (III) release of cellular and inflammatory factors (3). Our aim was to determine the association of HMGB1 with the pathogenesis of aGVHD. We enrolled 29 consecutive patients who had undergone allogeneic HSCT for a variety of disorders at our hospital. Patient characteristics are summarized in Table 1. In the time period starting from before HSCT up to discharge from our hospital, venous blood was collected once a week without documented infections. The serum samples were frozen and stored at )80 C until the assays were performed. The serum level of HMGB1 was measured in duplicate by using enzyme-linked immunosorbent assay following the manufacturer’s protocol (Shino-Test Corporation, Kanagawa, Japan). The serum HMGB1 levels in the inactive state (before HSCT and in the absence of aGVHD after HSCT; GVHD)) were compared to the active state aGVHD (grades I–III; GVHD+) (Fig. 1). The serum HMGB1 levels in the active state of aGVHD (median 1.41 ng ⁄mL, IQR 0.06– 3.27 ng ⁄mL) were significantly higher than those in the inactive state (median 0.15 ng ⁄mL, IQR 0–1.06 ng ⁄mL) (P = 0.0002, Mann–Whitney U test). The serum levels of HMGB1 in patients with a higher aGVHD grade tended to be greater than those in patients with a lower aGVHD grade; however, these differences were not statistically significant (grade I: median 0.93 ng ⁄mL, IQR 0.06–2.95 ng ⁄mL; grade II: median 1.17 ng ⁄mL, IQR 0.47–2.35 ng ⁄mL; grade III: median 1.41 ng ⁄mL, IQR 1.25–2.36 ng ⁄mL; Kruskal–Wallis test). We have shown, for the first time, that serum HMGB1 levels are elevated in patients who develop aGVHD after allogeneic HSCT. Our data suggest that HMGB1 may be involved in the pathogenesis of aGVHD. High-dose preparative regimens damage tissues, particularly in the gut, allowing LPS from bacteria in the bowel to leak into adjacent tissues and the bloodstream. Distinct classes of conserved microbial molecules and damaged cell elements, including HMGB1, probably activate TLRs on Table 1 Characteristics of patients

Cytomegalovirus ventriculoencephalitis in a reduced- intensity conditioning cord blood transplant recipient

T. Ando, N. Mitani, K. Yamashita, T. Takahashi, E. Ohama, H. Miyata, T. Yujiri, Y. Tanizawa. Cytomegalovirus ventriculoencephalitis in a reduced‐intensity conditioning cord blood transplant recipient.
Transpl Infect Dis 2010: 12: 441–445. All rights reserved

Recurrent extramedullary relapse of acute myelogenous leukemia after allogeneic hematopoietic stem cell transplantation in a patient with the chromosomal abnormality t(8;21) and CD56-positivity

Isolated extramedullary (EM) relapse of acute myelogenous leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is rare. Predisposing factors include CD56 expression and the chromosomal abnormality t(8;21). We describe an AML patient showing the chromosomal abnormality t(8;21) and CD56 expression who experienced a unique EM relapse after allo-HSCT. Approximately 10 months after allo-HSCT, he experienced relapse involving the femur and lumbar vertebrae and, subsequently, an EM relapse of the stomach. Although we administered only local radiotherapy and not systemic chemotherapy, he showed no bone marrow relapse on long-term follow-up after achieving complete hematological remission. These findings suggest that the graft-versus-leukemia effect may preferentially maintain marrow remission rather than prevent EM relapse. In addition, our findings show that extended survival is possible after EM relapse following allo-HSCT in patients with marrow hematopoiesis of donor origin, and that augmentation of the graft-versus-leukemia effect may be useful.

Hematopoietic progenitor cell count, but not immature platelet fraction value, predicts successful harvest of autologous peripheral blood stem cells

Mobilized stem cells in the peripheral blood (PB) must be efficiently harvested at the appropriate time before autologous PB stem cell (PBSC) transplantation. Enumeration of CD34+ cells in the PB before apheresis predicts the number of PBSCs that can be collected, but the cytometric techniques used are complex and expensive. Therefore, it is necessary to identify an alternative to the CD34+ cell count in PBSC harvest‐time monitoring. Fully automated flow cytometry using blood cell counters now allows reliable quantification of immature myeloid cells in the PB, referred to as hematopoietic progenitor cells (HPC), and reticulated platelets, expressed as the immature platelet fraction (IPF). Immature or reticulated platelets are thought to correlate with thrombopoietic activity of the marrow. Following a chemotherapy nadir, the recovery of white blood cell and platelet counts has been used to determine the right time for apheresis. Therefore, we examined whether the HPC count and IPF value could be used to predict PBSC mobilization in 20 patients with hematological malignancies. The HPC count was found to be correlated with the CD34+ cell count (r = 0.84, P < 0.01), whereas the IPF value was not (r = 0.37, P = 0.44). Therefore, the HPC count, but not the IPF value, is a possible predictor of the timing of autologous stem cell transplantation. J. Clin. Apheresis, 2011.

Alteration of adipokines during peripheral blood stem cell mobilization induced by granulocyte colony-stimulating factor.

Adipokines, soluble mediators produced by adipocytes, have been shown to play a role in various physiological and pathological conditions. We investigated the involvement of adipokines in granulocyte colony‐stimulating factor (G‐CSF)‐induced mobilization of hematopoietic stem cells in 21 healthy donors. We found that serum visfatin and resistin levels, but not leptin and adiponectin levels, were significantly elevated by G‐CSF treatment. G‐CSF treatment activated signaling proteins like extracellular signal‐regulated kinase and stimulated secretion of visfatin from 3T3‐L1 adipocytes. These findings suggest that some adipokines may play a role in G‐CSF‐induced mobilization of stem cells from the bone marrow into systemic circulation. J. Clin. Apheresis 2009.

Activation of the unfolded protein response in primary acute myeloid leukemia cells.

The unfolded protein response (UPR), which plays an important role in maintaining homeostasis of the endoplasmic reticulum (ER), is known to be activated in various solid tumors [1]. The role of the UPR in different forms of cancer or metastasis remains poorly characterized, and it is unclear whether UPR activation in cancer is due solely to microenvironmental stress, or to other mechanisms. The influence of the UPR on leukemogenesis remains largely uninvestigated. We previously reported that the UPR is activated in Philadelphia (Ph)-positive leukemia cells using cell lines and primary cells from Ph-positive acute lymphoid leukemia (ALL) patients [2]. In the present study, we investigated whether the UPR is activated in another type of acute leukemia, primary acute myeloid leukemia (AML).

Increased serum levels of matrix metalloproteinase-9 in acute graft-versus-host disease after allogeneic haematopoietic stem cell transplantation

Matrix metalloproteinases (MMPs) have been implicated in a variety of normal and pathological conditions that involve matrix degradation and remodelling. We investigated the role of MMPs in acute graft-versus-host disease (aGVHD) in 29 patients who had undergone allogeneic haematopoietic stem cell transplantation. The present study showed that the serum levels of MMP-9, but not those of MMP-2, significantly correlated with the occurrence and severity of aGVHD. Moreover, immunohistochemical analysis of the cutaneous lesions of patients with aGVHD revealed an increased number of inflammatory cells positive for MMP-9. These results suggest that MMP-9 might play an important role in the pathogenesis of aGVHD.