Japanese patients with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: In vitro functional analysis of five novel HMGCS2 mutations.

Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS2) deficiency is a metabolic disorder caused by mutations in the HMGCS2 gene. The present study describes the identification of four cases of HMGCS2 deficiency in Japan. Hepatomegaly and severe metabolic acidosis were observed in all cases. Fatty liver was identified in three cases, which suggested the unavailability of fatty acids. All patients presented with a high C2/C0 ratio, suggesting that the fatty acid oxidation pathway was normal during metabolic crisis. Genetic analyses revealed five rare, novel variants (p.G219E, p.M235T, p.V253A, p.S392L and p.R500C) in HMGCS2. To confirm their pathogenicity, a eukaryotic expression system and a bacterial expression system was adopted that was successfully used to obtain affinity-purified HMGCS2 protein with measurable activity. Purified M235T, S392L and R500C proteins did not retain any residual activity, whilst the V253A variant showed some residual enzymatic activity. Judging from the transient expression experiment in 293T cells, the G219E variant appeared to be unstable. In conclusion, the present study identified five novel variants of HMGCS2 that were indicated to be pathogenic in four patients affected by HMGCS2 deficiency.

Non-myeloablative preconditioning with ACK2 (anti-c-kit antibody) is efficient in bone marrow transplantation for murine models of mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disease caused by the deficient activity of iduronate 2-sulfatase (IDS), which is involved in the lysosomal catabolism of the glycosaminoglycans (GAGs) dermatan and heparan sulfate. Such a deficiency leads to the accumulation of undegraded GAGs in some organs. Although enzyme replacement therapy is available as a treatment of MPS II, there are some limitations, such as the requirement of weekly administration for whole life. To avoid such limitations, hematopoietic cell transplantation (HSCT) is a possible alternative. In fact, some report suggested positive effects of HSCT for MPS II. However, HSCT has also some limitations. Strong conditioning regimens can cause severe side effects. For overcome this obstacle, we studied the efficacy of ACK2, an antibody that blocks KIT, followed by low-dose irradiation as a preconditioning regimen for HSCT using a murine model of MPS II. This protocol achieves 58.7±4.92% donor chimerism at 16weeks after transplantation in the peripheral blood of recipient mice. GAG levels were significantly reduced in liver, spleen, heart and intestine. These results indicated that ACK2-based preconditioning might be one of the choices for MPS II patients who receive HSCT.

A method for measuring disease-specific iduronic acid from the non-reducing end of glycosaminoglycan in mucopolysaccharidosis type II mice.

Mucopolysaccharidosis type II (MPS II) is an X-linked lysosomal storage disorder arising from deficiency of iduronate-2-sulfatase (IDS), which results in progressive accumulation of glycosaminoglycans (GAGs) in multiple tissues. Accumulated GAGs are generally measured as the amount of total GAGs. However, we recently demonstrated that GAG accumulation in the brain of MPS II model mice cannot be reliably detected by conventional dye-binding assay measuring total GAGs. Here we developed a novel quantitative method for measurement of disease-specific GAGs based on the analysis of 2-sulfoiduronic acid levels derived from the non-reducing terminal end of the polysaccharides by using recombinant human IDS (rhIDS) and recombinant human iduronidase (rhIDUA). This method was evaluated on GAGs obtained from the liver and brain of MPS II mice. The GAGs were purified from tissue homogenates and then digested with rhIDS and rhIDUA to generate a desulfated iduronic acid from their non-reducing terminal end. HPLC analysis revealed that the generated iduronic acid levels were markedly increased in the liver and cerebrum of the MPS II mice, whereas the uronic acid was not detected in wild-type mice. These results indicate that this assay clearly detects the disease-specific GAGs in tissues from MPS II mice.

Hematopoietic Stem Cell Gene Therapy Corrects Neuropathic Phenotype in Murine Model of Mucopolysaccharidosis Type II.

Mucopolysaccharidosis type II (MPS II) is a neuropathic lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS), which leads to the accumulation of glycosaminoglycans (GAGs). We demonstrated that biochemical alterations in the brains of MPS II mice are not corrected by bone marrow transplantation (BMT) or enzyme replacement therapy, although BMT has been shown to be effective for other neurodegenerative MPSs, such as Hurler syndrome. In this study, we demonstrated that lentiviral isogeneic hematopoietic stem cell (HSC) gene therapy corrected neuronal manifestations by ameliorating lysosomal storage and autophagic dysfunction in the brains of MPS II mice. IDS-transduced HSCs increased enzyme activity both in various visceral organs and the CNS. Decreased levels of GAGs were observed in many organs, including cerebra, after transplantation of IDS-transduced HSCs. In addition, lentiviral HSC gene therapy normalized the secondary accumulation of autophagic substrates, such as p62 and ubiquitin-protein conjugates, in cerebra. Furthermore, in contrast to naive MPS II mice, there was no deterioration of neuronal function observed in transplant recipients. These results indicated that lentiviral HSC gene therapy is a promising approach for the treatment of CNS lesions in MPS II.

Effect of donor chimerism to reduce the level of glycosaminoglycans following bone marrow transplantation in a murine model of mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder caused by deficient activity of the iduronate-2-sulfatase. This leads to accumulation of glycosaminoglycans (GAGs) in the lysosomes of various cells. Although it has been proposed that bone marrow transplantation (BMT) may have a beneficial effect for patients with MPS II, the requirement for donor-cell chimerism to reduce GAG levels is unknown. To address this issue, we transplanted various ratios of normal and MPS II bone marrow cells in a mouse model of MPS II and analyzed GAG accumulation in various tissues. Chimerism of whole leukocytes and each lineage of BMT recipients' peripheral blood was similar to infusion ratios. GAGs were significantly reduced in the liver, spleen, and heart of recipients. The level of GAG reduction in these tissues depends on the percentage of normal-cell chimerism. In contrast to these tissues, a reduction in GAGs was not observed in the kidney and brain, even if 100 % donor chimerism was achieved. These observations suggest that a high degree of chimerism is necessary to achieve the maximum effect of BMT, and donor lymphocyte infusion or enzyme replacement therapy might be considered options in cases of low-level chimerism in MPS II patients.

Enzyme augmentation therapy enhances the therapeutic efficacy of bone marrow transplantation in mucopolysaccharidosis type II mice.

Before the availability of an enzyme replacement therapy (ERT) for mucopolysaccharidosis type II (MPS II), patients were treated by bone marrow transplantation (BMT). However, the effectiveness of BMT for MPS II was equivocal, particularly at addressing the CNS manifestations. To study this further, we subjected a murine model of MPS II to BMT and evaluated the effect at correcting the biochemical and pathological aberrations in the viscera and CNS. Our results indicated that BMT reduced the accumulation of glycosaminoglycans (GAGs) in a variety of visceral organs, but not in the CNS. With the availability of an approved ERT for MPS II, we investigated and compared the relative merits of the two strategies either as a mono or combination therapy. We showed that the combination of BMT and ERT was additive at reducing tissue levels of GAGs in the heart, kidney and lung. Moreover, ERT conferred greater efficacy if the immunological response against the infused recombinant enzyme was low. Finally, we showed that pathologic GAGs might potentially represent a sensitive biomarker to monitor the therapeutic efficacy of therapies for MPS II.

Corticosteroid pulse combination therapy for refractory Kawasaki disease: a randomized trial.

OBJECTIVE: This study examined the clinical efficacy and safety of intravenous methylprednisolone-pulse plus intravenous immunoglobulin (IVIG) combination therapy (IVMP+IVIG) for the initial treatment of patients predicted to have refractory Kawasaki disease (KD). METHODS: One hundred twenty-two patients with KD were studied at Kitasato University. Refractory KD was predicted at diagnosis using the Egami score, and the patients were randomly divided to receive either IVMP+IVIG or IVIG alone. The Egami score is used to predict refractory KD patients before treatment using the patient's age, days of illness, platelet count, C-reactive protein, and alanine aminotransferase level (cutoff: ≥3 points; 78% sensitivity and 76% specificity). RESULTS: Forty-eight patients (39.3%) were predicted to have refractory KD on the basis of the Egami score. The predicted IVIG responders (n = 74) received the standard therapy. The 48 predicted refractory KD patients were randomly assigned to a single-IVIG group (n = 26) or an IVMP+IVIG group (n = 22). Nineteen of the 22 patients (86.4%) in the IVMP+IVIG group had a prompt defervescence compared with 6 of the 26 patients (23.1%) in the single-IVIG group. The number of patients who had a z score ≥2.5 at 1 month was significantly higher in the single-IVIG group than in the IVMP+IVIG group. No serious adverse events were observed in either treatment group. CONCLUSION: This study demonstrated that IVMP+IVIG therapy is safe and effective for KD patients predicted as refractory.

Noninvasive assessment of pulmonary vascular resistance and pressure in patients with congenital heart disease: a new method using M-mode echocardiography.

BACKGROUND: The accurate evaluation of pulmonary vascular resistance (PVR) and mean pulmonary artery pressure is important to determine the optimal management and therapeutic strategy for patients with congenital heart disease (CHD). We evaluated the PVR and mean pulmonary artery pressure in 46 patients with several CHD types using the interventricular septum (IVS) motion determined by M-mode echocardiography. METHODS: We divided the patients into 2 groups according to the different IVS motions. We measured the maximum anterior displacement from the baseline during early systole (a) and the maximum posterior displacement from the baseline during early diastole (b). We defined type A to be a/b greater than or equal to 1.0, and type B to be a/b less than 1.0. RESULTS: The PVR and mean pulmonary artery pressure in type A patients were significantly higher than those in type B patients (p < 0.05). Type A IVS motion predicted patients with high PVR (>2.5 unit/m(2)) and high mean pulmonary artery pressure (>25 mmHg) (sensitivity 89%, specificity 89% and sensitivity 70%, specificity 91%, respectively). CONCLUSIONS: Our method can noninvasively separate high and low PVR among patients with CHD. This noninvasive method is therefore considered to be useful in the management of patients with CHD in a clinical setting.

Clinical score and transcript abundance patterns identify Kawasaki disease patients who may benefit from addition of methylprednisolone.

Intravenous immunoglobulin (IVIG) treatment-resistant patients are high risk of developing coronary artery lesions with Kawasaki disease. The IVIG-responsive (Group A; n = 6) and IVIG-resistant patients (Group B) were predicted before starting the initial treatment using the Egami scoring system and randomly allocated as a single-IVIG treatment group (group B1; n = 6) or as a IVIG-plus-methylprednisolone (IVMP) combined therapy group (group B2; n = 5). We investigated the transcript abundance in the leukocytes of those patients using a microarray analysis. Five patients in group A and one patient in group B1 responded to initial IVIG treatment. All group B2 patients responded to IVIG-plus-IVMP combined therapy. Before performing these treatments, those transcripts related to IVIG resistance and to the development of coronary artery lesions, such as IL1R, IL18R, oncostatin M, suppressor of cytokine signaling-3, S100A12 protein, carcinoembryonic antigen-related cell adhesion molecule-1, matrix metallopeptidase-9, and polycythemia rubra vera-1, were more abundant in group B patients in comparison with group A patients. Moreover, those transcripts in group B2 patients were more profoundly and broadly suppressed than group B1 patients after treatment. This study elucidated the molecular mechanism of the effectiveness of IVIG-plus-IVMP combined therapy.