Toshiro Nagasawa

Efficient enucleation of erythroblasts differentiated in vitro from hematopoietic stem and progenitor cells

Erythroblast enucleation is thought to be largely dependent on signals mediated by other cells, such as macrophages. In an attempt to improve the in vitro production of red blood cells (RBCs) from immature hematopoietic progenitor cells, we have developed a method to produce enucleated RBCs efficiently in the absence of feeder cells. Our method may represent an efficient way to produce transfusable RBCs on a large scale from hematopoietic progenitors.

Repression via the GATA box is essential for tissue-specific erythropoietin gene expression

In response to anemia, erythropoietin (Epo) gene transcription is markedly induced in the kidney and liver. To elucidate how Epo gene expression is regulated in vivo, we established transgenic mouse lines expressing green fluorescent protein (GFP) under the control of a 180-kb mouse Epo gene locus. GFP expression was induced by anemia or hypoxia specifically in peritubular interstitial cells of the kidney and hepatocytes surrounding the central vein. Surprisingly, renal Epo-producing cells had a neuronlike morphology and expressed neuronal marker genes. Furthermore, the regulatory mechanisms of Epo gene expression were explored using transgenes containing mutations in the GATA motif of the promoter region. A single nucleotide mutation in this motif resulted in constitutive ectopic expression of transgenic GFP in renal distal tubules, collecting ducts, and certain populations of epithelial cells in other tissues. Since both GATA-2 and GATA-3 bind to the GATA box in distal tubular cells, both factors are likely to repress constitutively ectopic Epo gene expression in these cells. Thus, GATA-based repression is essential for the inducible and cell type-specific expression of the Epo gene.

IL-7 and IL-15 allow the generation of suicide gene–modified alloreactive self-renewing central memory human T lymphocytes

Long-term clinical remissions of leukemia, after allogeneic hematopoietic stem cell transplantation, depend on alloreactive memory T cells able to self-renew and differentiate into antileukemia effectors. This is counterbalanced by detrimental graft-versus-host disease (GVHD). Induction of a selective suicide in donor T cells is a current gene therapy approach to abrogate GVHD. Unfortunately, genetic modification reduces alloreactivity of lymphocytes. This associates with an effector memory (T(EM)) phenotype of gene-modified lymphocytes and may limit antileukemia effect. We hypothesized that alloreactivity of gene-modified lymphocytes segregates with the central memory (T(CM)) phenotype. To this, we generated suicide gene-modified T(CM) lymphocytes with a retroviral vector after CD28 costimulation and culture with IL-2, IL-7, or a combination of IL-7 and IL-15. In vitro, suicide gene-modified T(CM) cells self-renewed upon alloantigen stimulation and resisted activation-induced cell death. In a humanized mouse model, only suicide gene-modified T cells cultured with IL-7 and IL-15 persisted, differentiated in T(EM) cells, and were as potent as unmanipulated lymphocytes in causing GVHD. GVHD was halted through the activation of the suicide gene machinery. These results warrant the use of suicide gene-modified T(CM) cells cultured with IL-7 and IL-15 for the safe exploitation of the alloreactive response against cancer.

A GATA box in the GATA-1 gene hematopoietic enhancer is a critical element in the network of GATA factors and sites that regulate this gene.

ABSTRACT A region located at kbp −3.9 to −2.6 5′ to the first hematopoietic exon of the GATA-1 gene is necessary to recapitulate gene expression in both the primitive and definitive erythroid lineages. In transfection analyses, this region activated reporter gene expression from an artificial promoter in a position- and orientation-independent manner, indicating that the region functions as the GATA-1 gene hematopoietic enhancer (G1HE). However, when analyzed in transgenic embryos in vivo, G1HE activity was orientation dependent and also required the presence of the endogenousGATA-1 gene hematopoietic promoter. To define the boundaries of G1HE, a series of deletion constructs were prepared and tested in transfection and transgenic mice analyses. We show that G1HE contains a 149-bp core region which is critical for GATA-1gene expression in both primitive and definitive erythroid cells but that expression in megakaryocytes requires the core plus additional sequences from G1HE. This core region contains one GATA, one GAT, and two E boxes. Mutational analyses revealed that only the GATA box is critical for gene-regulatory activity. Importantly, G1HE was active in SCL−/− embryos. These results thus demonstrate the presence of a critical network of GATA factors and GATA binding sites that controls the expression of this gene.

Long range interaction of cis‐DNA elements mediated by architectural transcription factor Bach1

A central question in vertebrate transcriptional regulation is how cis‐regulatory modules, including enhancers, silencers and promoters, communicate with each other over long distances to mandate proper gene expression. In order to address this question we analysed protein/DNA interactions in the human β‐globin locus control region (LCR). One of the many proteins that are potentially implicated in LCR function is Bach1. Bach1 possesses a basic leucine zipper (bZip) domain, as well as a BTB/POZ domain that has been shown to be involved in the regulation of chromatin structure. Bach1 forms heterodimers with small Maf proteins through its leucine zipper and binds to Maf recognition elements (MARE).

Interleukin-6 and Tumor Necrosis Factor-α in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

Background: In previous studies, significantly elevated levels of vascular endothelial growth factor (VEGF) have been reported in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS). On the other hand, plasma tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) have been significantly higher in mild sleep apneics than in normal controls. However, this study included a small number of patients and milder cases of OSAHS. Objectives andMethods: To assess the involvement of IL-6 and TNF-α in VEGF increases in patients with severe OSAHS, serum levels of IL-6 and TNF-α were determined in patients with severe OSAHS (n = 110) and compared to those of controls (n = 45) using an enzyme-linked immunosorbent assay. Results: No significant increase in IL-6 or TNF-α was detected in the present study cohort. However, the body mass index was significantly correlated with the severity of the apnea-hypopnea index. Conclusions: These data suggest that the elevation in VEGF is not directly related to IL-6 or TNF-α levels. However, the question of whether VEGF is the cause or the result of OSAHS remains to be determined. Further studies are needed to clarify the role of IL-6 and TNF-α in the pathogenesis of OSAHS, in which obesity should be entered as an independent factor.

Overproduction of platelet microparticles in cyanotic congenital heart disease with polycythemia

OBJECTIVES We sought to clarify the role of platelets in the pathogenesis of abnormal coagulation in patients with cyanotic congenital heart disease (CCHD) with polycythemia; we evaluated the production of platelet microparticles (MPs), platelet degranulation and aggregation response, as well as the correlations of these variables with polycythemia. BACKGROUND A shortened life span and suppressed aggregability of platelets are well known in patients with CCHD. Although platelet MPs are overproduced and play an important role in the coagulation process in various hematologic and cardiovascular disorders, the production of MPs remains to be elucidated in CCHD. We studied 19 patients who had CCHD with polycythemia and 21 age-matched subjects with acyanotic congenital heart disease (ACHD). Flow cytometry, using monoclonal antibodies, showed the presence of MPs as particles positive for the surface antigen (glycoprotein IIb/IIIa) specific to platelets, and platelet alpha-degranulation was recognized as platelets positive for the surface antigen of P-selectin. Platelet aggregation was assessed as the response to adenosine diphosphate (ADP). Relationships between these indexes and hematocrit (Hct) values were also evaluated. RESULTS Production of MPs correlated positively with Hct and markedly increased at Hct values above 60% in patients with CCHD. Surface P-selectin and the mean platelet volume in patients with CCHD were comparable with those in patients with ACHD. The platelet aggregation response to ADP significantly and negatively correlated with Hct. In two subjects who showed hemoptysis and underwent phlebotomy, MPs were reduced 6 h after the procedure. CONCLUSIONS Platelet MPs are overproduced in patients who have CCHD with polycythemia, probably due to a high shear stress derived from blood hyperviscosity. Circulating incompetent platelets, which have already been activated, as well as MPs, might play an important role in the coagulation abnormalities identified in such patients.

Lipocalin 2-mediated growth suppression is evident in human erythroid and monocyte/macrophage lineage cells

Lipocalin 2 (LCN2), a secreted protein of the lipocalin family, induces apoptosis in some types of cells and inhibits bacterial growth by sequestration of the iron‐laden bacterial siderophore. We have recently reported that LCN2 inhibits the production of red blood cells in the mouse. Here we analyzed the role of LCN2 in human hematopoiesis. Expression of LCN2 was observed not only in mature cells such as those of the granulocyte/macrophage and erythroid lineages but also in hematopoietic stem/progenitor cells. We also examined expression of two candidate receptors for LCN2, brain type organic cation transporter (BOCT) and megalin, in various cell types. BOCT showed relatively high levels of expression in erythroid and hematopoietic stem/progenitor cells but lower levels in granulocyte/macrophage and T lymphoid cells. Megalin was expressed at high levels in T lymphoid and erythroid cells but at lower levels in granulocyte/macrophage lineage cells. LCN2 suppressed the growth of erythroid and monocyte/macrophage lineages in vitro, but did not have this effect on cells of other lineages. In addition, immature hematopoietic stem/progenitor cells were not sensitive to LCN2. These results demonstrate a lineage‐specific role for LCN2 in human hematopoiesis that is reminiscent of its effects upon mouse hematopoiesis and strongly suggest an important in vivo function of LCN2 in the regulation of human hematopoiesis. J. Cell. Physiol. 215: 526–537, 2008.

ALK, CD30, CD20 Large B-Cell Lymphoma Containing Anaplastic Lymphoma Kinase (ALK) Fused to Clathrin Heavy Chain Gene (CLTC)

Pathological features and genomic basis of a rare case of ALK+, CD30−, CD20− large B-cell lymphoma were analyzed. A 36-year-old Japanese female was admitted because of lumbago and constitutional symptoms. Physical examination and laboratory tests showed anemia (hemoglobin, 7.5 g/dL), mild hepatosplenomegaly, and immunoglobin G (IgG) λ-type monoclonal gammopathy (IgG, 2782 mg/dL). The lymphoma spread exclusively in extranodal sites such as bone marrow, liver, spleen, ovary, and muscle. Biopsy specimens obtained from the ovary showed monomorphic proliferation of large immunoblastic cells with basophilic cytoplasm, round-shaped nuclei with a high nuclear to cytoplasmic ratio, and prominent single nucleolus. Immunostaining with anti-anaplastic lymphoma kinase (ALK) antibody, ALK1, showed finely granular cytoplasmic staining pattern. These cells were also positive for epithelial membrane antigen, CD4, CD19, CD38, CD138, cytoplasmic IgG, and λ chain, but negative for CD30 (Ber-H2), CD56, CD57, and other T- and B-cell markers. Southern blot analyses revealed that Ig heavy and λ light chain genes, but not T-cell receptor (TCR) β gene, were clonally rearranged. Chromosomal analyses by conventional G-banding, spectral karyotyping, and fluorescence in situ hybridization showed complex abnormality involving 2p23, and chromosome 2 was translocated to chromosome 17. As 2;17 translocation resulting in the fusion of clathrin heavy chain (CLTC) gene with ALK was previously reported in inflammatory myofibroblastic tumor, we performed reverse transcriptase-polymerase chain reaction and demonstrated that the lymphoma cells contained CLTC-ALK fusion transcript. Under the diagnosis of ALK+, CD30−, CD20− large B-cell lymphoma, she was treated with conventional combination chemotherapies. However, the lymphoma was primarily chemotherapy resistant, and the patient died 11 months after admission. We consider that this case confirms the existence of ALK+, CD30−, CD20− large B-cell lymphomas proposed by Delsol et al. (16) and further provides relevant information regarding their clinicopathological features and cytogenetics.

Aprotinin Inhibits Plasmin-Induced Platelet Activation During Cardiopulmonary Bypass

BACKGROUND In the past few years, aprotinin has been used in cardiac surgery with impressive results of reducing blood loss, but several adverse effects of aprotinin also have been reported. One of the most likely mechanisms is the inhibition of plasmin by aprotinin, although this indirect effect has not been reproduced in all experimental studies. METHODS AND RESULTS We evaluated the platelet function and fibrinolytic activity during human cardiac surgery, with or without aprotinin. During cardiopulmonary bypass (CPB) in humans without aprotinin (n=16), decrease of platelet aggregation induced by thrombin, increase of alpha-granule secretion of platelet and microparticle formation, and increase of plasmin/alpha2-antiplasmin complex (PIC) were observed. In contrast, low-dose aprotinin (1.0 x 10(6) KIU), which was administered only into the priming fluid of extracorporeal circuits (n=10), maintained platelet aggregation induced by thrombin and reduced alpha-granule secretion and microparticle formation of platelets during CPB. In vitro, plasmin (0.8 CU/mL) released alpha-granules of washed platelets, and this activation was completely inhibited by aprotinin (10 KIU/mL). CONCLUSIONS Aprotinin has indirect effects to inhibit platelet activation, and this may partly explain the reduction of blood loss during cardiac surgery. To prevent the adverse effects, a single and minimal use of aprotinin is important. The results of in vivo and in vitro studies suggest that platelet preservation was demonstrated by the lower concentration of aprotinin (1.0 x 10(6) KIU per patient or 10 KIU/mL) compared with the concentration that inhibits plasma fibrinolysis.