Tomonobu Sato

The clinical feature of invasive fungal infection in pediatric patients with hematologic and malignant diseases: a 10-year analysis at a single institution at Japan.

Invasive fungal infections (IFI) are an important complication in hematologic malignancies and stem-cell transplantation (SCT). However, there are limited data characterizing IFI in children. The clinical feature of IFI after chemotherapy and SCT were analyzed in 334 pediatric patients treated at Hokkaido University Hospital from 1997 to 2006. The cumulative incidence of IFI was 6.9%; this comprised cases of proven, probable and possible IFI at rates of 1.2%, 3.0%, and 2.7%, respectively. The infected lesions were lung in 14 patients, liver in 5 patients, brain in 3 patients, fungemia in 2 patients, kidney in 1 patient, and endophthalmitis in 1 patient. The mortality of IFI was 48.2%, excluding patients who died due to relapse and interstitial pneumonitis; in particular, 71.4% patients with a lung lesion (10/14) died due to IFI. Fifty-nine pediatric patients died in our institution over the 10-year period of the study and IFI was the direct cause of death in 18.6% (11/59) of the patients. Risk factors for IFI with chemotherapy and SCT were also analyzed. Univariate analysis showed that age at diagnosis older than 10 years, relapse of original disease, long-term administration of broad-spectrum antibiotics, and acute myelogenous leukemia (AML) were the risk factors for IFI. All patients with IFI received long-term antibiotic therapy. AML was most strongly associated using a multivariate analysis. The prognosis of IFI has been expected poor; therefore, prevention of this condition, especially for older patients with AML, would be important.

TRIM29 negatively regulates p53 via inhibition of Tip60

Ataxia-telangiectasia (AT) is an autosomal recessive genetic disease characterized by immunological deficiencies, neurological degeneration, developmental abnormalities and an increased risk of cancer. Ataxia-telangiectasia group D (ATDC) was initially described as a gene related to AT. Ataxia-telangiectasia group D, also known as TRIM29, is structurally a member of the tripartite motif (TRIM) family of proteins, some of which have been reported to be highly expressed in some human carcinomas, but the involvement of TRIM29 in carcinogenesis has not been fully elucidated. In this study, we found by using yeast two-hybrid screening that TRIM29 binds to Tip60, which has been reported as a cellular acetyltransferase protein. Overexpression of TRIM29 promoted degradation and changed localization of Tip60 and reduced acetylation of p53 at lysine 120 by Tip60, resulting in enhancement of cell growth and transforming activity. In addition, we found that TRIM29 suppresses apoptosis induced by UV irradiation in HCT116 cell lines. These findings suggest that TRIM29 functions as an oncogene that promotes tumor growth.

TRIM32 promotes neural differentiation through retinoic acid receptor-mediated transcription.

Retinoic acid (RA), a metabolite of vitamin A, plays versatile roles in development, differentiation, cell cycles and regulation of apoptosis by regulating gene transcription through nuclear receptor activation. Ubiquitinylation, which is one of the post-translational modifications, appears to be involved in the transcriptional activity of intranuclear receptors including retinoic acid receptor α (RARα). Mutations in the tripartite motif-containing protein 32 gene (TRIM32; also known as E3 ubiquitin-protein ligase) have been reported to be responsible for limb-girdle muscular dystrophy type 2H in humans, and its encoded protein has been shown to interact with several other important proteins. In this study, we found that TRIM32 interacts with RARα and enhances its transcriptional activity in the presence of RA. We also found that overexpression of TRIM32 in mouse neuroblastoma cells and embryonal carcinoma cells promoted stability of RARα, resulting in enhancement of neural differentiation. These findings suggest that TRIM32 functions as one of the co-activators for RARα-mediated transcription, and thereby TRIM32 is a potential therapeutic target for developmental disorders and RA-dependent leukemias.

Evaluation of risk factors for invasive fungal infection after allogeneic stem cell transplantation in pediatric patients.

Invasive fungal infections (IFIs) are a significant cause of morbidity and mortality after stem cell transplantation (SCT). The incidence, outcome, and risk factors for IFI after allogeneic SCT were analyzed in 149 pediatric patients treated at Hokkaido University hospital from 1988 to 2006. The cumulative incidence of IFI after allogeneic SCT was 8.1%; this comprised cases of proven, probable, and possible IFI at rates of 0.7%, 4.0%, and 3.4%, respectively. Only 1 patient complicated with IFI in the 100 days after SCT, excluding cases with rejection. Antifungal drugs were effective in 3 of the 12 patients with IFI, but the other 9 patients died because of IFI and relapse of original diseases. Nonrelapse mortality was markedly higher for patients with IFI than for those without IFI (60.0% vs. 20.0%, P=0.0204). Univariate analysis showed that age at transplant, chronic graft-versus-host disease (GVHD), and a corticosteroid dose >2 mg/kg or 60 mg/d for 10 days or longer were possible risk factors for IFI. Of these factors, chronic GVHD was the only factor associated with IFI in a multivariate analysis. Treatment of IFI is very difficult and, therefore, prevention of this condition is important, especially upon occurrence of chronic GVHD.

Stem cell transplantation in primary immunodeficiency disease patients

Background: Primary immunodeficiency diseases (PID) are rare but have a high associated risk of death from overwhelming infection in early childhood. Stem cell transplantation (SCT) can be curative for PID, but standardized protocols for each disease have not yet been established.

14-3-3 proteins sequester a pool of soluble TRIM32 ubiquitin ligase to repress autoubiquitylation and cytoplasmic body formation

Summary Deregulated expression of tripartite motif-containing protein 32 (TRIM32, an E3 ubiquitin-protein ligase) contributes to various diseases. Here we report, using quantitative proteomics and biochemistry, that 14-3-3 proteins bind to phosphorylated TRIM32 and prevent TRIM32 autoubiquitylation and the formation of TRIM32-containing cytoplasmic bodies, which are potential autoregulatory mechanisms that can reduce the concentration of soluble free TRIM32. The 14-3-3–TRIM32 interaction is dependent on protein-kinase-A-catalyzed phosphorylation of TRIM32 at Ser651. We found that the inhibitory effect of 14-3-3 is, in part, a consequence of disrupting the propensity of TRIM32 to undergo higher-order self-association without affecting its dimerization. Consequently, dimerized TRIM32 bound to 14-3-3 was sequestered in a distinct cytoplasmic pool away from the microtubule network, whereas a TRIM32 mutant that cannot bind 14-3-3 underwent multimerization and was unavailable to facilitate cell growth. Our results reveal a novel connection between ubiquitylation and phosphorylation pathways, which could modulate a variety of cell events by stimulating the formation of the 14-3-3–TRIM32 signaling complex.

TRIM45 negatively regulates NF-κB-mediated transcription and suppresses cell proliferation

The NF-κB signaling pathway plays an important role in cell survival, immunity, inflammation, carcinogenesis, and organogenesis. Activation of NF-κB is regulated by several posttranslational modifications including phosphorylation, neddylation and ubiquitination. The NF-κB signaling pathway is activated by two distinct signaling mechanisms and is strictly modulated by the ubiquitin-proteasome system. It has been reported that overexpression of TRIM45, one of the TRIM family ubiquitin ligases, suppresses transcriptional activities of Elk-1 and AP-1, which are targets of the MAPK signaling pathway. In this study, we showed that TRIM45 also negatively regulates TNFα-induced NF-κB-mediated transcription by a luciferase reporter assay and that TRIM45 lacking a RING domain also has an activity to inhibit the NF-κB signal. Moreover, we found that TRIM45 overexpression suppresses cell growth. These findings suggest that TRIM45 acts as a repressor for the NF-κB signal and regulates cell growth.

A prospective, randomized study comparing cefozopran with piperacillin–tazobactam plus ceftazidime as empirical therapy for febrile neutropenia in children with hematological disorders

The aim of this randomized study was to evaluate the efficacy of cefozopran monotherapy and piperacillin–tazobactam plus ceftazidime (PIPC/TAZ + CAZ) combination therapy in pediatric neutropenic patients.

Hyponatremia and syndrome of inappropriate antidiuretic hormone secretion complicating stem cell transplantation

Summary:Hyponatremia is a common electrolyte disorder in hospitalized patients. Although there are a few case reports of hyponatremia following stem cell transplantation (SCT), no reports concerning the incidence are currently available. We describe the occurrence of hyponatremia and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) following SCT. In a single center analysis of 140 patients, hyponatremia and SIADH were observed in 40 and 11.4% of patients, respectively, following SCT. Risk factors for SIADH included young age, transplantation from an HLA-mismatched or unrelated donor, cord blood transplantation, and graft-versus-host disease prophylaxis with methyl prednisolone. Multivariate analysis revealed that transplantation from an HLA-mismatched donor and performance of SCT in a child below 4 years of age were risk factors for SIADH. For patients who underwent SCT from an HLA-mismatched or unrelated donor, those with SIADH showed a significantly higher overall survival rate (90.9 vs 40.2%) and event-free survival rate (77.8 vs 33.8%) compared to those without SIADH. Overall, our data show that hyponatremia and SIADH are relatively common complications following SCT, especially in children below 4 years of age and after SCT from an HLA-mismatched donor.

Significance of eosinophilia after stem cell transplantation as a possible prognostic marker for favorable outcome

Summary:Although eosinophilia after stem cell transplantation (SCT) has been addressed in recent reports, the significance of eosinophilia in disease outcome after SCT has not been well studied. In this study, we investigate the frequency of eosinophilia after SCT to determine its prognostic value. The subjects were 113 patients with malignant or nonmalignant diseases who underwent SCT treatment. In these patients, eosinophilia was detected in 44 cases (38.9%), on average 67.5 days after transplantation, and the mean maximum absolute eosinophil count was 840.5 × 106/l. To study the basis of eosinophilia after SCT, various serum cytokine levels during SCT in patients both with and without eosinophilia were analyzed. Statistical analysis indicated that the overall patient survival rates improved in those with eosinophilia compared to those without eosinophilia (88.7 vs 43.0%, P=0.0034). In particular, in patients with malignant diseases, those with eosinophilia showed a higher event-free survival (81.1 vs 44.6%, P=0.0025) and a lower relapse rate (16.0 vs 43.0%, P=0.0287) than those without eosinophilia. In conclusion, we propose that eosinophilia after SCT could be a useful prognostic marker for determining favorable outcomes in patients with malignant diseases. The reasons for this good prognosis in SCT patients with eosinophilia are discussed.