Yuka Takata

Periostin and bone marrow fibrosis

Periostin is a secreted protein that shares structural homology with the insect axon guidance protein fasciclin 1. Periostin is expressed predominantly in collagen-rich fibrous connective tissues that are subjected to constant mechanical stresses. We have shown previously that periostin is a novel component of subepithelial fibrosis in bronchial asthma. Here, we investigated the relationship between periostin and bone marrow (BM) fibrosis. Periostin was expressed in the stroma and stromal cells of BM fibrosis specimens and to a great extent its expression levels correlated closely to the grade of fibrosis, as estimated by silver staining. However, in the present study, we found no relationship between plasma periostin levels and the extent of BM fibrosis. We also demonstrated that periostin is secreted by human BM hTERT stromal cells and that its secretion is enhanced by TGF-β, a cytokine produced by clonal proliferation of megakaryocytes and/or monocytes. These results indicate that periostin is a component of BM fibrosis and that it may play a role in the disease progression.

A Case of 8p11 Myeloproliferative Syndrome with BCR-FGFR1 Gene Fusion Presenting with Trilineage Acute Leukemia/Lymphoma, Successfully Treated by Cord Blood Transplantation

The 8p11 myeloproliferative syndrome is a rare neoplasm associated with chromosomal translocations involving the fibroblast growth factor receptor 1 (FGFR1) gene located at chromosome 8p11–12. FGFR1 encodes a transmembrane receptor tyrosine kinase. The resultant fusion proteins are constitutively active tyrosine kinases that drive the proliferation of hematopoietic cells, whose uncontrolled growth can present as a myeloproliferative neoplasm. We report here the case of a 50-year-old man harboring the t(8;22)(p12;q11) chromosomal translocation in cells from both bone marrow and lymph nodes. He presented with acute leukemia and lymphoma with trilineage features. A novel mRNA in-frame fusion between exon 4 of the breakpoint cluster region (BCR) gene at chromosome 22q11 and exon 9 of FGFR1 gene on chromosome 8p11–12 was identified by reverse transcription polymerase chain reaction analysis and was confirmed by DNA sequencing. Because the patient was refractory to chemotherapy, cord blood transplantation was performed in progressive disease. It resulted in a successful outcome in which cytogenetic complete remission has been maintained for 2 years till date.

Characterization of the light chain-restricted clonal B cells in peripheral blood of HCV-positive patients.

To investigate the association between hepatitis C virus (HCV) and B cell proliferation, we searched for the clonal B cells by flow cytometric analysis of the surface immunoglobulin kappa (κ):lambda (λ) light chain ratios of the circulating B (CD19+) cells in 240 HCV-positive patients and 150 negative controls with liver diseases. Clonal B cells with light chain restriction (κ:λ ratio >3:1 or <1:2) were analyzed for CD5 expression and the presence of monoclonal immunoglobulin heavy-chain (IGH) gene rearrangements and the t(14;18) chromosomal translocation. Clonal B cells were detected in 7 cases with HCV (2.9%), but was never detected in the controls (p < 0.05). Of the 7 cases, all had monoclonal IGH gene rearrangements and one had the t(14;18) chromosomal translocation. These HCV-related clonal B cells are not uniform in the intensity of CD5 expression and showed no increase in the frequencies of CD5+ population compared with non-clonal B cells. No “chronic lymphocytic leukemia-phenotype” cells were found. The loss of clonality was observed in 2 cases treated with interferon and in one case treated with splenectomy. The longitudinal study is required to determine whether these circulating clonal B cells progress to lymphoproliferative disorders in future or not.

Platelets with a W127X mutation in GPIX express sufficient residual amounts of GPIbα to support adhesion to von Willebrand factor and collagen

Bernard–Soulier syndrome (BSS) is an inherited bleeding disorder caused by a defect in the platelet glycoprotein (GP) Ib/IX complex. The GPIX W127X mutation is the most common genetic defect in Japanese patients with BSS, which is often misdiagnosed as immune thrombocytopenic purpura, presumably due to residual expression of GPIbα. Neither the mechanism by which this mutation leads to a mild bleeding diathesis, nor whether functional GPIbα is expressed on platelet surfaces is known. We investigated GPIbα expression and function in platelets with a GPIX W127X mutation (GPIXW127X). GPIbα complexed with GPIbβ by disulfide bonding was expressed on GPIXW127X platelets and stable CHO-K1 cells lacking GPIX but expressing GPIbα and GPIbβ. Expression of GPIbα/β on GPIXW127X platelets was sufficient to support adhesion to immobilized von Willebrand factor and type III collagen and ristocetin-induced platelet agglutination. A residual amount of functional GPIbα/β heteromer expressed on GPIXW127X platelets partially compensates for the absence of the GPIb/IX complex. This may account for the mild bleeding phenotype of the BSS variant characterized by a non-sense mutation in GPIX.

Promyelocytic crisis of chronic myelogenous leukaemia during imatinib mesylate treatment.

An untreated 66-year-old woman with chronic myelogenous leukaemia (CML) in the chronic phase was initially given imatinib mesylate, rapidly achieving a good cytogenetic response with treatment. However, acute promyelocytic leukaemia complicated by a disseminated intravascular coagulation occurred 9 months after beginning imatinib treatment. Promyelocytic crisis of CML was diagnosed by demonstration of both BCR/ABL and PML/RARα chimeric genes in leukaemic cells by karyotypic and fluorescence in situ hybridization analysis. Clonal evolution with addition of the PML/RARα translocation may have arisen in the early chronic phase of CML, with expansion of this clone during imatinib treatment. Promyelocytic crisis of CML is rare; furthermore, we know of no previous report of promyelocytic crisis occurring during treatment with imatinib.