Chisaki Mizumoto

Serum hepcidin level and erythropoietic activity after hematopoietic stem cell transplantation

In this study, an inverse relationship between erythroid activity and serum hepcidin was found after hematopoietic stem cell transplantation. The relationship between serum hepcidin, a key regulator of body iron homeostasis, and erythropoiesis was investigated before and after stem cell transplantation in 31 patients with hematopoietic malignancies. Serum hepcidin-25 was monitored using a liquid chromatography-tandem mass spectrometry-based assay system. Other iron- and erythropoiesis-related parameters and known hepcidin regulators, such as interleukin-6 and growth differentiation factor-15, were also monitored. The serum hepcidin level peaked one week after stem cell transplantation, followed by a gradual decrease with a parallel change in interleukin-6 and a reciprocal change in reticulocyte count. Multivariate regression analysis demonstrated that the serum hepcidin level at four weeks after stem cell transplantation showed significant inverse correlations with erythropoietic activity markers, such as the soluble transferrin receptor, but not with growth differentiation factor-15. These results indicate the existence of an unknown functional erythropoiesis-associated circulating factor, other than growth differentiation factor-15, that negatively regulates hepcidin production in stem cell transplantation settings.

Pretransplant serum ferritin and C-reactive protein as predictive factors for early bacterial infection after allogeneic hematopoietic cell transplantation.

Although fluoroquinolones or other antibiotics are commonly used to prevent bacterial infections after hematopoietic cell transplantation (HCT), because of the growing presence of multidrug-resistant microorganisms, it is important to identify patients who are more likely to benefit from antibacterial prophylaxis. To evaluate risk factors for early bacterial infection after allogeneic HCT, we retrospectively analyzed clinical data for 112 consecutive adult patients with hematological malignancies who received transplants without any antibacterial prophylaxis. The cumulative incidence of bacterial infection at 30 days after transplantation was 16%. Among various pre-transplant factors, only high serum ferritin (>700 ng/mL, 47 patients) and high C-reactive protein (CRP) (>0.3 mg/dL, 28 patients) levels were significantly associated with the development of bacterial infection in a multivariate analysis (hazard ratio (95% confidence interval): ferritin, 4.00 (1.32–12.17); CRP, 3.64 (1.44–9.20)). In addition, septic shock and sepsis with organ failure were exclusively observed in patients who had high ferritin and/or high CRP levels. These results suggest that pretransplant serum ferritin and CRP levels can be useful markers for predicting the risk of early bacterial infection after allogeneic HCT. It may be prudent to limit antibacterial prophylaxis to patients with predefined risk factors to ensure the safety of HCT with the use of fewer antibiotics.

Clinical Significance of Serum Hepcidin Levels on Early Infectious Complications in Allogeneic Hematopoietic Stem Cell Transplantation

The association of iron overload with complications of allogeneic hematopoietic stem cell transplantation (HSCT) has been suggested in previous studies. Because hepcidin plays a central role in the regulation of iron homeostasis, we analyzed the association between pretransplant serum hepcidin-25 levels and early infectious complications after allogeneic HSCT. We studied 55 consecutive adult patients with a median age of 47 years (range: 20-64 years) who underwent allogeneic HSCT for hematologic malignancies at our institution. Thirty-two patients had myelogenous malignancies; the remaining 23 had lymphogenous malignancies. The median pretransplant serum hepcidin level of patients in the study was 21.6 ng/mL (range: 1.4-371 ng/mL), which was comparable to that of healthy volunteers (median: 19.1 ng/mL [range: 2.3-37 ng/mL]; n = 17). When cumulative incidences of documented bacterial and cytomegalovirus (CMV) infections at day 100 were compared according to pretransplant hepcidin-25 levels, the incidence of bacterial, but not CMV, infection, was significantly higher in the high-hepcidin group (> or = 50 ng/mL; n = 17) than in the low-hepcidin group (<50 ng/mL; n = 38) (65% [95% confidence interval, 38%-82%] versus 11% [3%-23%]; P < .001). This finding was confirmed by multivariate Cox analysis adjusted for confounders, including pretransplant ferritin and C-reactive protein (CRP) levels. No fungal infection was documented in either group. These results suggest that the pretransplant serum hepcidin-25 level may be a useful marker for predicting the risk of early bacterial complications after allogeneic HSCT. Larger prospective studies are, however, warranted to confirm our findings.

Leukemic and meningeal relapse of CD5+ intravascular large B-cell lymphoma with down-modulation of CD20 after rituximab therapy

Although CD20- relapses of B-cell lymphoma following rituximab therapy have increasingly been reported recently, coexistence of both the original and selected clones on relapse in a single patient have not been described. We experienced such a case with rare CD5+ intravascular lymphomatosis (IVL). A 46-year-old woman was admitted because of IVL complicated with cauda equina syndrome and pulmonary infarction. Complete remission was successfully achieved with multidrug chemotherapy in combination with rituximab. However, the disease recurred after 8 months with leukemic progression and meningeal involvement. The phenotype of the abnormal lymphocytes in the peripheral blood was fundamentally the same (CD20+CD5+CD10-CD19+CD23-sIgλ+) as that of the cells in the cerebrospinal fluid (CSF). However, CD20 expression was decreased remarkably compared with that in the CSF and that in the bone marrow before therapy. The targeting of CD20 molecules on the tumor cell surface by rituximab may have provided a selective pressure on lymphoma cells. The escape phenomenon of the lymphoma cells from rituximab was observed by simultaneously comparing the CD20 expression of cells in the peripheral blood and in a site of sanctuary from rituximab, the CSF.

H-Ferritin Is Preferentially Incorporated by Human Erythroid Cells through Transferrin Receptor 1 in a Threshold-Dependent Manner.

Ferritin is an iron-storage protein composed of different ratios of 24 light (L) and heavy (H) subunits. The serum level of ferritin is a clinical marker of the body’s iron level. Transferrin receptor (TFR)1 is the receptor not only for transferrin but also for H-ferritin, but how it binds two different ligands and the blood cell types that preferentially incorporate H-ferritin remain unknown. To address these questions, we investigated hematopoietic cell-specific ferritin uptake by flow cytometry. Alexa Fluor 488-labeled H-ferritin was preferentially incorporated by erythroid cells among various hematopoietic cell lines examined, and was almost exclusively incorporated by bone marrow erythroblasts among human primary hematopoietic cells of various lineages. H-ferritin uptake by erythroid cells was strongly inhibited by unlabeled H-ferritin but was only partially inhibited by a large excess of holo-transferrin. On the other hand, internalization of labeled holo-transferrin by these cells was not inhibited by H-ferritin. Chinese hamster ovary cells lacking functional endogenous TFR1 but expressing human TFR1 with a mutated RGD sequence, which is required for transferrin binding, efficiently incorporated H-ferritin, indicating that TFR1 has distinct binding sites for H-ferritin and holo-transferrin. H-ferritin uptake by these cells required a threshold level of cell surface TFR1 expression, whereas there was no threshold for holo-transferrin uptake. The requirement for a threshold level of TFR1 expression can explain why among primary human hematopoietic cells, only erythroblasts efficiently take up H-ferritin.

MALT lymphoma of the thymus with Sjögren’s syndrome: biphasic changes in serological abnormalities over a 4-year period following thymectomy

Thymic mucosa-associated lymphoid tissue (MALT) lymphoma shows distinct immunological characteristics, such as the expression of the IgA isotype, the frequent presence of immunoglobulin abnormalities, and a strong association with autoimmune disease, especially Sjögren’s syndrome (SjS). We report a case of thymic MALT lymphoma, who exhibited biphasic changes in her clinical characteristics during the 4-year observation period after thymectomy. A 71-year-old woman was admitted because of suspected SjS. A diagnosis of primary thymic MALT lymphoma was made, and SjS was confirmed. Serological abnormalities such as polyclonal hypergammaglobulinemia, IgA M protein, and elevated levels of rheumatoid factor were noted. These abnormalities improved rapidly after the thymectomy, but did not completely disappear. Interestingly, the remaining abnormalities, which can be ascribed to the proliferation of B cells throughout the body under the influence of SjS, have been improving slowly but steadily during the 4-year observation period. It is suspected that the removal of the tumor by thymectomy has more or less normalized the immunological environment and alleviated the SjS disease activity.

Mycophenolate mofetil combined with tacrolimus and minidose methotrexate after unrelated donor bone marrow transplantation with reduced-intensity conditioning

We evaluated the efficacy of a post-grafting immunosuppressive regimen consisting of tacrolimus, methotrexate, and mycophenolate mofetil (MMF) in 21 adults (median age, 55 years) with poor-risk hematologic malignancy who underwent unrelated bone marrow transplantation after fludarabine-based reduced-intensity conditioning (RIC). In combination with intravenous tacrolimus and minidose methotrexate (5 mg/m2 on days 1, 3, and 6), MMF was orally administered at 30 mg/kg daily in three divided doses between days 7 and 27. All patients achieved neutrophil recovery with donor-type chimerism at a median of 19 days (range, 13–35). Cumulative incidences of grades II–IV and III–IV acute graft-versus-host disease (GVHD) were 33% (95% CI, 15–53%) and 5% (95% CI, 0.3–20%), respectively. Five of 20 evaluable patients developed extensive chronic GVHD. Toxicities associated with the use of MMF were acceptable, although one patient experienced intractable GVHD immediately after the cessation of MMF. With a median follow-up of 24 months, overall survival at 3 years was 38% (95% CI, 14–63%). No late graft failure was observed. In conclusion, post-transplant MMF combined with tacrolimus and methotrexate was well tolerated and conferred stable donor cell engraftment, low risk of severe acute GVHD, and encouraging overall survival in unrelated donor marrow transplantation after RIC regimens.

Acidic milieu augments the expression of hepcidin, the central regulator of iron homeostasis

Hepcidin is the central regulator of body iron homeostasis, and dysregulation of hepcidin expression causes various clinical disorders, such as anemia and hemochromatosis. Various stimuli, including iron load and interleukin-6, are involved in the regulation of hepcidin expression. We previously reported that serum hepcidin levels were high in patients with end-stage renal disease, compared with healthy subjects. Since metabolic acidosis is commonly observed in these patients, we hypothesized that acidic milieu might augment hepcidin expression. In this study, we investigated the effect of changes in the pH of the microenvironment on hepcidin expression in human hepatoma and leukemia cell lines. We found that hepcidin expression in these cells was augmented by the acidic milieu created with lactic acid, hydrochloric acid and excess carbon dioxide. Acidic milieu did not clearly enhance hepcidin promoter activity, but rather stabilized hepcidin transcript in the hepatoma cells. We speculate that metabolic acidosis may contribute in part to the elevation of serum hepcidin levels in patients with end-stage chronic kidney disease. Further studies are needed to elucidate the association between acidosis and hepcidin expression in various clinical settings.

High pretransplant hepcidin levels are associated with poor overall survival and delayed platelet engraftment after allogeneic hematopoietic stem cell transplantation

Iron overload is considered a risk factor for mortality in patients with hematopoietic malignancies. Hepcidin is a key regulator of systemic iron balance. We previously reported dynamic changes of serum hepcidin‐25 levels in patients with hematologic malignancies after allogeneic hematopoietic stem cell transplantation (allo‐HSCT). In this study, we retrospectively analyzed the association of pretransplant hepcidin‐25 levels with overall survival (OS), engraftment, and other clinical outcomes of allo‐HSCT in patients with hematologic malignancies. A total of 166 patients were divided into two groups depending on their pretransplant serum hepcidin‐25 levels; their median age was 49.5 years, and the median follow‐up time was 46.8 months. At 3 years, the patients in the high‐hepcidin group had a significantly lower OS than those in the low‐hepcidin group (49.2 vs. 69.0%, respectively; P = 0.006). Multivariate analysis revealed that pretransplant serum hepcidin‐25 level, sex, and disease status were independently associated with OS. The incidence of platelet engraftment was significantly lower in the high‐hepcidin group than in the low‐hepcidin group, whereas no significant differences were observed in neutrophil and reticulocyte engraftments between these groups. Hence, pretransplant serum hepcidin levels can be a marker for predicting delayed platelet recovery after allo‐HSCT.

Concurrent Autoimmune Neutropenia and Idiopathic Thrombocytopenic Purpura Associated with IgG4-related Diease

IgG4-related disease (IgG4RD) is a multi-organ disorder characterized by an elevated serum IgG4 level and IgG4-positive plasma cell infiltration of the affected organs, accompanied by tissue fibrosis and sclerosis. Although it can affect any organ, to our knowledge, no cases involving concurrent autoimmune neutropenia and thrombocytopenia have been reported. A 62-year-old man visited our hospital and was diagnosed with IgG4RD accompanied by interstitial pneumonitis, lymphadenopathy, and interstitial nephritis. During his clinical course, he developed autoimmune neutropenia and idiopathic thrombocytopenic purpura. Our case, invoving multiple hematological abnormalities, might help deepen our understanding of the pathophysiology of IgG4RD.