[POEMS syndrome: monoclonal plasma cell disorder with polyneuropathy].

Polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome is a rare multi-organ disease. Because the peripheral neuropathy is frequently the overriding symptom and because the characteristics of the neuropathy are similar to that chronic inflammatory demyelinating polyneuropathy(CIDP), patient are frequently misdiagnosed with CIDP or monoclonal gammopathy of undetermined significance (MGUS) -associated peripheral neuropathy. Production of vascular endothelial growth factor (VEGF), secreted by plasmacytoma, is considered responsible for these symptoms. For isolated plasmacytoma, radiotherapy is usually highly effective. Patients without isolated plasmacytoma require systemic chemotherapy, which is ineffective in many cases. In recent reports, high dose chemotherapy followed by autologous peripheral blood stem cell transplantation can dramatically improve clinical manifestations, particularly for polyneuropathy in such patients refractory for standard chemotherapy.

Collection of mobilized peripheral blood stem cells from a donor with severe iron deficient anemia.

We report a 45-year-old woman with iron deficient anemia (IDA) who underwent a collection of allogeneic peripheral blood stem cells (PBSCs) induced by granulocyte-colony stimulating factor (G-CSF) after a rapid improvement of IDA by iron replacement. Her peripheral red blood cells (RBCs) after iron therapy were composed of two different-sized subpopulations; one consisted of microcytes, which were iron deficient RBCs, and another of normocytes, which were produced after iron replacement. On the first day of PBSC collection, the interface setting was maintained aiming at 2% hematocrit as usual; however, PBSCs could not be collected adequately. Sedimentation of iron deficient, lighter RBCs under centrifugation within a blood cell separator could be similar to that of mononuclear cells, and the lighter RBCs could contaminate the mononuclear cell layer, resulting in the collection of the lighter layers of mononuclear cells than desired. On the second day, we succeeded in obtaining enough PBSCs by collecting heavier layers than those collected on the first day by using a 4% hematocrit and monitoring white blood cell counts of the collection line serially. It should be noted that the lighter RBCs from a donor with a history of IDA could complicate collection of PBSCs.

Chronic thrombopoietin overexpression induces mesangioproliferative glomerulopathy in mice.

We previously reported that mice transgenic (Tg) for thrombopoietin (TPO) developed progressive fibrosis and osteosclerosis of the bone marrow. Here, we show that TPO-overexpressing mice also exhibited notable histological changes in the kidneys, including an increased number of mesangial cells, expansion of the mesangial matrix in the glomerulus, and atrophy of the renal tubuli. Plasma transforming growth factor (TGF)-beta1 and platelet-derived growth factor (PDGF)-BB, which could induce mesangioproliferative responses in glomeruli, were both elevated in TPO Tg mice, even though TPO itself has no effect on mesangial cells due to their lack of c-Mpl. The mesangial proliferative change in TPO Tg mice was thought to be induced by the elevation of these cytokines. In conclusion, our finding that TPO-overexpressing mice developed mesangioproliferative glomerulopathy might represent an undesirable effect of chronically elevated TPO in vivo, which should be taken into consideration before new TPO-like growth factors become available in clinical practice.

The effect of anabolic steroids on anemia in myelofibrosis with myeloid metaplasia: retrospective analysis of 39 patients in Japan.

Between 1999 and 2005, 285 patients received new diagnoses of myelofibrosis with myeloid metaplasia (MMM) in Japan. Anemic symptoms were present in 162 patients, and hemoglobin (Hb) concentrations were <10 g/dL in 197 patients. Fifty-five MMM patients were treated with anabolic steroids, and their effect on anemia during MMM was evaluated in 39 patients. A "good" response was defined as an Hb increase of >or=1.5 g/dL, cessation of transfusion dependence, and an Hb concentration of >10 g/dL maintained for at least 8 weeks. A "minimum" response was defined as an Hb increase of >or=1.5 g/dL and transfusion independence for at least 8 weeks. Both good and minimum responses were considered "favorable." Favorable responses were achieved in 17 patients (44%, 8 good and 9 minimum responses). None of the pretreatment variables, such as the lack of transfusion dependence, a higher Hb concentration at the start of treatment, or the absence of cytogenetic abnormalities, were associated with a response to anabolic steroid therapy. Adverse events associated with anabolic steroid therapy were moderate and transient. Two patients required definitive withdrawal of treatment. Thus, anabolic steroids are well tolerated and effective for the treatment of anemia in a subset of MMM patients.

Tyk2 mutation homologous to V617F Jak2 is not found in essential thrombocythaemia, although it induces constitutive signaling and growth factor independence.

A single somatic mutation, V617F, in the pseudokinase domain of the Jak2 is the primary cause of many chronic myeloproliferative diseases. As valine 617 of Jak2 is conserved as valine 678 of Tyk2, we examined the effect of a homologous mutation in Tyk2 (V678F Tyk2) on cell growth. V678F Tyk2 augmented the transcriptional activity of Stat3 and Stat5. The expression of V678F Tyk2 in Ba/F3 cells induced autonomous cell growth and showed hyper-responsiveness to IL-3. Although V678F Tyk2 might cause MPD, no cases of ET patients lacking the V617F Jak2 mutation harbored the Tyk2 mutation.

A novel mutation in the juxtamembrane intracellular sequence of the granulocyte colony-stimulating factor (G-CSF) receptor gene in a patient with severe congenital neutropenia augments GCSF proliferation activity but not through the MAP kinase cascade.

We analyzed the structure of the granulocyte colony-stimulating factor (G-CSF) receptor gene in a 6-year-old female patient with severe congenital neutropenia (SCN) who experienced severe recurrent infections since 1 month of age. There is no family history of any similar disease. When the patient was 4 months old, she began receiving treatment with recombinant human G-CSF that resulted in a small increase in the neutrophil count sufficient for the prevention and treatment of bacterial infection. An analysis of complementary DNA for the patient's G-CSF receptor revealed a 3-base pair deletion in the juxtamembrane intracellular sequence. This deletion at the beginning of exon 16 was thought to be caused by alternative splicing; analysis of the DNA revealed a G-to-A point mutation of the final nucleotide of intron 15. To evaluate the functional activity of the G-CSF receptor with this 3-base pair deletion of the juxtamembrane region, we transfected this G-CSF receptor mutant into an interleukin 3-dependent cell line, BAF/3. BAF/3 cells expressing the mutant G-CSF receptor showed augmented proliferation activity in response to G-CSF compared with cells having the wild-type G-CSF receptor. Although the proliferation signal of G-CSF in normal hematopoiesis is transduced through the activation of MAP kinases, this G-CSF receptor mutant showed decreased activation of ERKI/2 in response to G-CSF compared with the wild type, but the transduced sig-nal for Stat3 activation by G-CSF was of the same magnitude as that of the wild-type G-CSF receptor. This result means that the augmented proliferation activity in response to G-CSF that we observed in cells having the G-CSF receptor gene with the 3-base pair deletion is transduced through an intracellular signaling pathway other than MAP kinase. Because SCN patients with a mutation in the G-CSF receptor frequently develop leukemia, this 3-base pair deletion in the juxtamembrane sequence of the G-CSF receptor gene in this patient may be one step in the course of leukemic transformation.

Transgenic mice overexpressing murine thrombopoietin develop myelofibrosis and osteosclerosis.

Thrombopoietin (TPO) regulates megakaryocytopoiesis and platelet production in vivo and in vitro. Exogenous overexpression of TPO in vivo by viral-mediated gene transfer induced bone marrow (BM) fibrosis and osteosclerosis. On the other hand, transgenic mice (Tg) overexpressing TPO using a liver-specific apolipoprotein E (Apo-E) promoter did not exhibit myelofibrosis or osteosclerosis. These discrepancies in phenotype are not fully understood. Then we have investigated the consequences of long-term in vivo overexpression of TPO in a mouse model. Murine TPO Tg mice driven by the IgH promoter were generated. The number of platelets and neutrophils in peripheral blood, and the number of megakaryocytes and granulocytic immature cells in the BM was elevated, together with the number of progenitor cells for megakaryocyte and myeloid cells. TPO Tg mice demonstrated anemia but the number of progenitor cells for the erythrocyte was increased. TPO Tg mice developed myelofibrosis and osteosclerosis as they aged with extramedullary hematopoiesis in the spleen. As plasma transforming growth factors (TGF)-beta1 and osteoprotegerin (OPG) levels were higher in TPO Tg mice than in wild-type mice, the development of myelofibrosis and osteosclerosis depends on local TPO levels in BM and might be due to elevated TGF-beta1 and OPG.

Cyclophosphamide-induced cardiomyopathy in a patient with seminoma and a history of mediastinal irradiation.

A 17-year-old man with mediastinal seminoma was treated with chemotherapy and mediastinal irradiation therapy. Then he received high-dose chemotherapy containing cyclophosphamide (CY) followed by autologous peripheral blood stem cell transplantation. He suffered from CY-induced cardiomyopathy beginning six days after the administration of high-dose CY. The predictable factors associated with the onset of CY-induced cardiomyopathy are not precisely known. It is suggested that the history of mediastinal irradiation was responsible for the onset of cardiomyopathy.

Roles of Stat3 and ERK in G-CSF signaling.

G-CSF specifically stimulates the proliferation and differentiation of cells that are committed to the neutrophil-granulocyte lineage. Although Stat3 was thought to be essential for the transduction of G-CSF-induced cell proliferation and differentiation signals, mice deficient for Stat3 in hematopoietic cells show neutrocytosis and infiltration of cells into the digestive tract. The number of progenitor cells in the neutrophil lineage is not changed, and G-CSF-induced proliferation of progenitor cells and prolonged neutrophil survival were observed in Stat3-deficient mice. In hematopoietic cells from Stat3-deficient mice, trace levels of SOCS3, a negative regulator of granulopoiesis, were observed, and SOCS3 expression was not induced by G-CSF stimulation. Stat3-null bone marrow cells displayed a significant activation of extra-cellular regulated kinase 1 (ERK1)/ERK2 under basal conditions, and the activation of ERK was enhanced and sustained by G-CSF stimulation. Furthermore, the augmented proliferation of Stat3-deficient bone marrow cells in response to G-CSF was dramatically decreased by addition of a MEK1 inhibitor. These results indicate that Stat3 functions as a negative regulator of G-CSF signaling by inducing SOCS3 expression and that ERK activation is the major factor responsible for inducing the proliferation of hematopoietic cells in response to G-CSF.

Tyrosine kinase 2 interacts with and phosphorylates receptor for activated C kinase-1, a WD motif-containing protein.

Receptor for activated C kinase (Rack)-1 is a protein kinase C-interacting protein, and contains a WD repeat but has no enzymatic activity. In addition to protein kinase C, Rack-1 also binds to Src, phospholipase Cgamma, and ras-GTPase-activating proteins. Thus, Rack-1 is thought to function as a scaffold protein that recruits specific signaling elements. In a cytokine signaling cascade, Rack-1 has been reported to interact with the IFN-alphabeta receptor and Stat1. In addition, we show here that Rack-1 associates with a member of Jak, tyrosine kinase 2 (Tyk2). Rack-1 interacts weakly with the kinase domain and interacts strongly with the pseudokinase domain of Tyk2. Rack-1 associates with Tyk2 via two regions, one in the N terminus and one in the middle portion (aa 138-203) of Rack-1. Jak activation causes the phosphorylation of tyrosine 194 on Rack-1. After phosphorylation, Rack-1 is translocated toward the perinuclear region. In addition to functioning as a scaffolding protein, these results raise the possibility that Rack-1 functions as a signaling molecule in cytokine signaling cascades.

The role of Tyk2, Stat1 and Stat4 in LPS-induced endotoxin signals.

Mice lacking Tyk2, Stat1 or Stat4, which are members of the Jak-Stat signaling cascade, were resistant to LPS-induced endotoxin shock. Interestingly, Tyk2-deficient mice had higher resistance to LPS challenge than mice lacking either Stat1 or Stat4. The activation of MAPK and NF-kappaB by LPS, and the production of TNF-alpha and IL-12 after LPS injection, were not abrogated by the absence of Tyk2, Stat1 or Stat4. In Stat1-deficient mice, the induction of IFN-beta by LPS in macrophages was severely reduced, although the serum level of IFN-gamma was elevated after LPS injection. In contrast, in Stat-4 deficient mice, the induction of IFN-beta by LPS was normal, but the serum level of IFN-gamma remained low after LPS injection. Interestingly, the induction of both IFN-beta and IFN-gamma by LPS was severely reduced in Tyk2-deficient mice. Therefore, Stat1 and Stat4 independently play substantial roles in the susceptibility to LPS. Tyk2 is essential for LPS-induced endotoxin shock, and this signaling pathway is transduced by the activation of Stat1 and Stat4.

Limitin, an interferon-like cytokine, transduces inhibitory signals on B-cell growth through activation of Tyk2, but not Stat1, followed by induction and nuclear translocation of Daxx.

OBJECTIVE: Limitin, an interferon-like cytokine, suppresses B lymphopoiesis through ligation of the interferon-alpha/beta (IFN-alpha/beta) receptor. The aim of this study was to examine the intracellular signal transduction pathways activated by limitin. MATERIALS AND METHODS: The effects of limitin on cell growth, the activation of Jak kinase and Stat proteins, and the induction of interferon regulatory factor-1 (IRF-1) and Daxx were examined using the mouse pre-B-cell line 18.81, wild-type, and Tyk2-deficient mouse bone marrow cells. In addition, the change of localization of the Daxx protein after limitin treatment in wild-type and Tyk2-deficient mice was examined. RESULTS: Limitin phosphorylates Tyk2, Jak1, Stat1, and Stat2 and rapidly induces IRF-1 mRNA production. Phosphorylation of Stat1 by limitin is partially dependent on Tyk2. Suppression of B-cell growth by limitin, however, is severely impaired in the absence of Tyk2, whereas it is unaffected by the absence of Stat1. Limitin also induces the expression and nuclear translocation of Daxx, which is essential for IFN-alpha-induced inhibition of B-lymphocyte development. The absence of Tyk2 abrogates this induction of Daxx expression and nuclear translocation. CONCLUSIONS: Limitin suppresses B-cell growth through activation of Tyk2, resulting in the up-regulation and nuclear translocation of Daxx. This limitin-mediated signaling pathway does not require Stat1.

Intracellular signal transduction of interferon on the suppression of haematopoietic progenitor cell growth.

Interferon (IFN)-alpha and IFN-gamma suppress the growth of haematopoietic progenitor cells. IFN-alpha activates Janus kinase-1 (Jak1) and Tyrosine kinase-2 (Tyk2), followed by the phosphorylation of the signal transducers and activators of transcription, Stat1 and Stat2. IFN-gamma activates Jak1 and Jak2, followed by the activation of Stat1. Activated Stats bind the promoter regions of IFN-inducible genes. We evaluated the role of Tyk2 and Stat1 in the IFN-mediated inhibition of haematopoietic progenitor cell growth. While IFN-alpha (1000 U/ml) suppressed the number of granulocyte-macrophage colony-forming units (CFU-GM) or erythroid burst-forming units (BFU-E) from wild-type mouse bone marrow cells, this suppression was partially inhibited by a deficiency in Tyk2 and completely inhibited by a deficiency in Stat1. High levels of IFN-alpha (10,000 U/ml) suppressed the CFU-GM or BFU-E obtained from Stat1-deficient mice, but did not suppress this growth in cells from Tyk2-deficient mice. Stat1 was phosphorylated by IFN-alpha in Tyk2-deficient cells, although the level of phosphorylation was weaker than that observed in wild type mice. Thus, the inhibitory signal on haematopoietic progenitor cells mediated by IFN-alpha may be transduced by two signalling pathways, one regulated by Tyk2 and the other dependent on Stat1. IFN-gamma also suppressed the number of CFU-GM or BFU-E, and this pathway was mediated by IFN-gamma in a Stat1-dependent manner, independently of Tyk2.

The lipocalin 24p3, which is an essential molecule in IL-3 withdrawal-induced apoptosis, is not involved in the G-CSF withdrawal-induced apoptosis.

Many hematopoietic cells undergo apoptosis when deprived of specific cytokines. Lipocalin 24p3, reported to be induced in hematopoietic cells by interleukin 3 (IL-3) depletion, induces hematopoietic cell apoptosis despite the presence of IL-3. As granulocyte colony stimulating factor (G-CSF) depletion also induces the apoptosis of G-CSF-dependent cell line cells, we examined the effect of 24p3 on the apoptotic function induced by G-CSF depletion. 24p3 was induced by the depletion of IL-3, but not G-CSF, in cytokine-dependent cell lines. Although 24p3 suppressed growth induced by IL-3, it did not influence G-CSF-dependent cell growth. These observations show that 24p3 is not involved in the G-CSF withdrawal-induced apoptosis, although it is essential in IL-3 withdrawal-induced apoptosis.