Tadayuki Sato

Microsatellite polymorphism between the tumor necrosis factor and HLA-B genes in Behçet's disease

Behçets disease is associated with the HLA-B51 antigen. However, it has not yet been clarified if the HLA-B51 gene itself is the susceptibility gene related to this disease or if it is some other non-HLA gene in linkage disequilibrium with HLA-B51. Therefore, we screened one of the HSP70 genes, HUM70t (HSP70-Hom), around the class III region and the microsatellite sequence located between the HLA-B and TNF genes for genetic polymorphism in BD. A comparison between patients with BD and healthy controls revealed no significant difference in the frequency of the HUM70t polymorphism. In the microsatellite sequence, Tau-a, in the region between the HLA-B and TNF genes, the frequency of 14 repetitions of GT was increased significantly and that of 11 repetitions was decreased significantly in the patient group. Further, the allelic distributions of the B51 antigen-associated microsatellite polymorphism differed significantly between patients and healthy controls, and in the B51 antigen-negative subjects, analysis of the microsatellite polymorphism also revealed a significant difference in the haplotype frequency between the patient and control groups. These results suggest that the HLA-B51 gene may not be the primary locus responsible for BD, and implicate some other gene(s) located between the TNF and HLA-B genes.

Murine Stromal Cell Line HESS-5 Maintains Reconstituting Ability of Ex Vivo-Generated Hematopoietic Stem Cells from Human Bone Marrow and Cytokine-Mobilized Peripheral Blood

Human bone marrow (BM) or mobilized peripheral blood (mPB) CD34+ cells have been shown to loose their stem cell quality during culture period more easily than those from cord blood (CB). We previously reported that human umbilical CB stem cells could effectively be expanded in the presence of human recombinant cytokines and a newly established murine bone marrow stromal cell line HESS‐5. In this study we assessed the efficacy of this xenogeneic coculture system using human BM and mPB CD34+ cells as materials. We measured the generation of CD34+CD38− cells and colony‐forming units, and assessed severe‐combined immunodeficient mouse‐repopulating cell (SRC) activity using cells five days after serum‐free cytokine‐containing culture in the presence or the absence of a direct contact with HESS‐5 cells. As compared with the stroma‐free culture, the xenogeneic coculture was significantly superior on expansion of CD34+CD38− cells and colony‐forming cells and on maintenance of SRC activity. The PKH26 study demonstrated that cell division was promoted faster in cells cocultured with HESS‐5 cells than in cells cultured without HESS‐5 cells. These results indicate that HESS‐5 supports rapid generation of primitive progenitor cells (PPC) and maintains reconstituting ability of newly generated stem cells during ex vivo culture irrespective of the source of samples. This xenogeneic coculture system will be useful for ex vivo manipulation such as gene transduction to promote cell division and the generation of PPC and to prevent loss of stem cell quality.

Efficient lentiviral transduction of human cord blood CD34(+) cells followed by their expansion and differentiation into dendritic cells.

OBJECTIVE To support immune reconstitution after cord blood transplantation, immunotherapy using gene-modified dendritic cells (DCs), the most potent antigen-presenting cells, can be a powerful strategy for preventing infection and recurrence. To investigate the applicability of lentiviral vector-transduced DCs compared to retroviral vectors, we transduced umbilical cord blood (CB) CD34(+) cells, then expanded and differentiated them into DCs. MATERIALS AND METHODS We transduced CB CD34(+) cells by vesicular stomatitis virus G-protein pseudotyped self-inactivating lentiviral vector or retroviral vectors carrying the enhanced green fluorescent protein gene. The cells were expanded in the stroma-dependent culture system and transferred to the culture condition for developing DCs. The efficiency of transduction and expression of the transgene in severe combined immunodeficiency (SCID) mice-repopulating cells (SRCs) and DCs were compared between lentiviral vector and retroviral vectors. Induced DCs were cocultured with allogeneic or autologous T cells to test the ability to present antigens. RESULTS CB CD34(+) cells transduced by lentiviral vector and expanded ex vivo sustained stable transgene expression and multipotentiality by assessing SRCs assay and clonogenic assay of bone marrow cells from the transplanted mice. DCs derived from these cells expressed green fluorescent protein and surface markers CD1a, CD80, and HLA-DR and showed potent allo-stimulatory activity as well as nontransduced DCs did. On the other hand, we did not detect transgene expression in SRCs and DCs transduced by retroviral vectors. CONCLUSION Gene-modified DCs derived from ex vivo expanded CB CD34(+) cells transduced by lentiviral vector will be useful in future immunotherapy protocols.

Association between HLA-DPB1 matching and 1-year rejection-free graft survival in high-risk corneal transplantation

We analyzed the effect of matching for HLA class II alleles on corneal graft outcome in a single-center, retrospective study from January 1991 through April 1996. The study involved 81 transplant recipients at high and low risk of corneal graft rejection, who were typed by the polymerase chain reaction-restriction fragment length polymorphism method and who completed at least 1-year of follow-up. The DRB1, DQB1, and DPB1 alleles were analyzed together and transplant recipients were subdivided into groups with matching (one to four alleles matched in the high risk or one to five alleles matched in the low risk) and without matching (no allele matched) for HLA class II. A significantly higher rate of 1-year rejection-free graft survival was revealed in high-risk transplant recipients with matching, compared with those without matching (P=0.0238). We have shown that matching for at least one HLA class II allele was actually beneficial in high-risk transplants. An analysis of matching for each allele separately, detected that only HLA-DPB1 matching was significantly associated with a higher rate of 1-year rejection-free graft survival in high-risk transplant recipients with matching (one or two alleles matched) compared with those without matching (no allele matched) (P=0.0139). In particular, matching for one DPB1 allele was significantly beneficial compared with no matching (P=0.0140). There was no significant effect of HLA-DRB1 and -DQB1 matching (P=0.3177 and P=0.2878, respectively). Furthermore, a strong association between DPB1 matching and 1-year rejection-free graft survival was observed in DRB1-incompatible high-risk transplant recipients (P=0.0308). Nevertheless, no significant effect of DPB1 matching was detected in DQB1-incompatible transplant recipients. Our findings indicate that HLA class II DNA typing is clinically relevant for corneal transplant recipients and that especially HLA-DPB1 matching has a beneficial effect in high-risk corneal transplantation.

The Role of Transfected HLA-DQ Genes in the Mixed Lymphocyte Reaction-Like Condition

DR gene products are commonly thought to be involved in the induction of the mixed lymphocyte reaction (MLR). However, very little is known about the role of HLA DQ antigens in the MLR. To address this question, we introduced DQα andβ chain genes into mouse L cells, a human T -cell line, and a human premonocytoid cell line using a liposome-mediated transfer technique. The DQα and DQβ genomic clones were isolated from a DR2 DQw1 and a DR3 DQw2 phage library, respectively. ThepSV2-Neo gene was introduced as a selection marker with both DQα and DQβ. The resultant transfected cells were able to bind several HLA class II monoclonal antibodies. In addition, these cells were found to be efficient in stimulating peripheral blood lymphocyte proliferation under MLR-like conditions, implying a role for HLA-DQ molecules in HLA-D typing differences.

Recessive Inheritance of Population-Specific Intronic LINE-1 Insertion Causes a Rotor Syndrome Phenotype

Sequences of long‐interspersed elements (LINE‐1, L1) make up ∼17% of the human genome. De novo insertions of retrotransposition‐active L1s can result in genetic diseases. It has been recently shown that the homozygous inactivation of two adjacent genes SLCO1B1 and SLCO1B3 encoding organic anion transporting polypeptides OATP1B1 and OATP1B3 causes a benign recessive disease presenting with conjugated hyperbilirubinemia, Rotor syndrome. Here, we examined SLCO1B1 and SLCO1B3 genes in six Japanese diagnosed with Rotor syndrome on the basis of laboratory data and laparoscopy. All six Japanese patients were homozygous for the c.1738C>T nonsense mutation in SLCO1B1 and homozygous for the insertion of a ∼6.1‐kbp L1 retrotransposon in intron 5 of SLCO1B3, which altogether make up a Japanese‐specific haplotype. RNA analysis revealed that the L1 insertion induced deleterious splicing resulting in SLCO1B3 transcripts lacking exon 5 or exons 5–7 and containing premature stop codons. The expression of OATP1B1 and OATP1B3 proteins was not detected in liver tissues. This is the first documented case of a population‐specific polymorphic intronic L1 transposon insertion contributing to molecular etiology of recessive genetic disease. Since L1 activity in human genomes is currently seen as a major source of individual genetic variation, further investigations are warranted to determine whether this phenomenon results in other autosomal‐recessive diseases.

A Combination of Mitochondrial Oxidative Stress and Excess Fat/Calorie Intake Accelerates Steatohepatitis by Enhancing Hepatic CC Chemokine Production in Mice.

Mitochondrial oxidative stress is considered as a key accelerator of fibrosis in various organs including the liver. However, the production of oxidative stress and progression of liver fibrosis may merely represent the independent consequences of hepatocellular injury caused by the primary disease. Because of a lack of appropriate experimental models to evaluate the sole effects of oxidative stress, it is virtually unknown whether this stress is causatively linked to the progression of liver fibrosis. Here, we examined the direct effects of mitochondrial reactive oxygen species (ROS) on the progression of high fat/calorie diet-induced steatohepatitis using Tet-mev-1 mice, in which a mutated succinate dehydrogenase transgene impairs the mitochondrial electron transport and generates an excess amount of ROS in response to doxycycline administration. Wild type and Tet-mev-1 mice that had been continuously given doxycycline-containing water were subsequently fed either normal chow or a cholesterol-free high-fat/high-sucrose diet for 4 months at approximately 1 or 2 years of age. Histopathological examinations indicated that neither the mitochondrial ROS induced in Tet-mev-1 mice nor the feeding of wild type animals with high-fat/high-sucrose diet alone caused significant liver fibrosis. Only when the Tet-mev-1 mice were fed a high-fat/high-sucrose diet, it induced lipid peroxidation in hepatocytes and enhanced hepatic CC chemokine expression. These events were accompanied by increased infiltration of CCR5-positive cells and activation of myofibroblasts, resulting in extensive liver fibrosis. Interestingly, this combinatorial effect of mitochondrial ROS and excess fat/calorie intake on liver fibrosis was observed only in 2-year-old Tet-mev-1 mice, not in the 1-year-old animals. Collectively, these results indicate that mitochondrial ROS in combination with excess fat/calorie intake accelerates liver fibrosis by enhancing CC chemokine production in aged animals. We have provided a good experimental model to explore how high fat/calorie intake increases the susceptibility to nonalcoholic steatohepatitis in aged individuals who have impaired mitochondrial adaptation.

Imatinib mesylate directly impairs class switch recombination through down-regulation of AID: its potential efficacy as an AID suppressor

Activation-induced cytidine deaminase (AID) is essential for class switch recombination and somatic hypermutation. Its deregulated expression acts as a genomic mutator that can contribute to the development of various malignancies. During treatment with imatinib mesylate (IM), patients with chronic myeloid leukemia often develop hypogammaglobulinemia, the mechanism of which has not yet been clarified. Here, we provide evidence that class switch recombination on B-cell activation is apparently inhibited by IM through down-regulation of AID. Furthermore, expression of E2A, a key transcription factor for AID induction, was markedly suppressed by IM. These results elucidate not only the underlying mechanism of IM-induced hypogammaglobulinemia but also its potential efficacy as an AID suppressor.

Establishment of a Humanized APL Model via the Transplantation of PML-RARA-Transduced Human Common Myeloid Progenitors into Immunodeficient Mice

Recent advances in cancer biology have revealed that many malignancies possess a hierarchal system, and leukemic stem cells (LSC) or leukemia-initiating cells (LIC) appear to be obligatory for disease progression. Acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia characterized by the formation of a PML-RARα fusion protein, leads to the accumulation of abnormal promyelocytes. In order to understand the precise mechanisms involved in human APL leukemogenesis, we established a humanized in vivo APL model involving retroviral transduction of PML-RARA into CD34+ hematopoietic cells from human cord blood and transplantation of these cells into immunodeficient mice. The leukemia well recapitulated human APL, consisting of leukemic cells with abundant azurophilic abnormal granules in the cytoplasm, which expressed CD13, CD33 and CD117, but not HLA-DR and CD34, were clustered in the same category as human APL samples in the gene expression analysis, and demonstrated sensitivity to ATRA. As seen in human APL, the induced APL cells showed a low transplantation efficiency in the secondary recipients, which was also exhibited in the transplantations that were carried out using the sorted CD34− fraction. In order to analyze the mechanisms underlying APL initiation and development, fractionated human cord blood was transduced with PML-RARA. Common myeloid progenitors (CMP) from CD34+/CD38+ cells developed APL. These findings demonstrate that CMP are a target fraction for PML-RARA in APL, whereas the resultant CD34− APL cells may share the ability to maintain the tumor.

Oxidative stress tolerance of early stage diabetic endothelial progenitor cell

Introduction One of the causes for poor vasculogenesis of diabetes mellitus (DM) is known to rise from the dysfunction of bone marrow-derived endothelial progenitor cells (BM EPCs). However, the origin of its cause is less understood. We aimed to investigate the effect of oxidative stress in early stage of diabetic BM-EPC and whether its vasculogenic dysfunction is caused by oxidative stress. Methods Bone marrow c-Kit+Sca-1+Lin− (BM-KSL) cells were sorted from control and streptozotocin-induced diabetic C57BL6J mice by flow cytometry. BM-KSLs were then assessed for vasculogenic potential (colony forming assay; EPC-CFA), accumulation of intracellular ROS (CM-H2DCFDA), carbonylated protein (ELISA), anti-oxidative enzymes expression (RT-qPCR) and catalase activity (Amplex Red). Results Compared to control, DM BM-KSL had significantly lower EPC-CFUs in both definitive EPC-CFU and total EPC-CFU (p < 0.05). Interestingly, the oxidative stress level of DM BM-KSL was comparable and was not significantly different to control followed by increased in anti-oxidative enzymes expression and catalase activity. Conclusions Primitive BM-EPCs showed vasculogenic dysfunction in early diabetes. However the oxidative stress is not denoted as the major initiating factor of its cause. Our results suggest that primitive BM-KSL cell has the ability to compensate oxidative stress levels in early diabetes by increasing the expression of anti-oxidative enzymes.