Naomi Hino-Fukuyo

Human PTRF mutations cause secondary deficiency of caveolins resulting in muscular dystrophy with generalized lipodystrophy

Caveolae are invaginations of the plasma membrane involved in many cellular processes, including clathrin-independent endocytosis, cholesterol transport, and signal transduction. They are characterized by the presence of caveolin proteins. Mutations that cause deficiency in caveolin-3, which is expressed exclusively in skeletal and cardiac muscle, have been linked to muscular dystrophy. Polymerase I and transcript release factor (PTRF; also known as cavin) is a caveolar-associated protein suggested to play an essential role in the formation of caveolae and the stabilization of caveolins. Here, we identified PTRF mutations in 5 nonconsanguineous patients who presented with both generalized lipodystrophy and muscular dystrophy. Muscle hypertrophy, muscle mounding, mild metabolic complications, and elevated serum creatine kinase levels were observed in these patients. Skeletal muscle biopsies revealed chronic dystrophic changes, deficiency and mislocalization of all 3 caveolin family members, and reduction of caveolae structure. We generated expression constructs recapitulating the human mutations; upon overexpression in myoblasts, these mutations resulted in PTRF mislocalization and disrupted physical interaction with caveolins. Our data confirm that PTRF is essential for formation of caveolae and proper localization of caveolins in human cells and suggest that clinical features observed in the patients with PTRF mutations are associated with a secondary deficiency of caveolins.

Intramuscular renin–angiotensin system is activated in human muscular dystrophy

To investigate the role of the muscular renin-angiotensin system (RAS) in human muscular dystrophy, we used immunohistochemistry and Western blotting to examine the cellular localization of angiotensin-converting enzyme (ACE), the angiotensin II type 1 receptor (AT1) and the angiotensin II type 2 receptor (AT2) in muscle biopsies from patients with Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and congenital muscular dystrophy (CMD). In normal muscle, ACE was expressed in vascular endothelial cells and neuromuscular junctions (NMJs), whereas AT1 was immunolocalized to the smooth muscle cells of blood vessels and intramuscular nerve twigs. AT2 was immunolocalized in the smooth muscle cells of blood vessels. These findings suggest that the RAS has a functional role in peripheral nerves and NMJs. ACE and AT1, but AT2 immunoreactivity were increased markedly in dystrophic muscle as compared to controls. ACE and the AT1 were strongly expressed in the cytoplasm and nuclei of regenerating muscle fibers, fibroblasts, and in macrophages infiltrating necrotic fibers. Double immunolabeling revealed that activated fibroblasts in the endomysium and perimysium of DMD and CMD muscle were positive for ACE and AT1. Triple immunolabeling demonstrated that transforming growth factor-beta1 (TGF-beta1) and ACE were colocalized on the cytoplasm of activated fibroblasts in dystrophic muscle. Furthermore, Western blotting showed increases in the expression of AT1 and TGF-beta1 protein in dystrophic muscle, which coincided with our immunohistochemical results. The overexpression of ACE and AT1 in dystrophic muscle would likely result in the increased production of Ang II, which may act on these cells in an autocrine manner via AT1. The activation of AT1 may induce fibrous tissue formation through overexpression of TGF-beta1, which potently activates fibrogenesis and suppresses regeneration. In conclusion, our results imply that the intramuscular RAS-TGF-beta1 pathway is activated in human muscular dystrophy and plays a role at least partly in the pathophysiology of this disease.

De novo GABRA1 mutations in Ohtahara and West syndromes

GABRA1 mutations have been identified in patients with familial juvenile myoclonic epilepsy, sporadic childhood absence epilepsy, and idiopathic familial generalized epilepsy. In addition, de novo GABRA1 mutations were recently reported in a patient with infantile spasms and four patients with Dravet syndrome. Those reports suggest that GABRA1 mutations are associated with infantile epilepsy including early onset epileptic encephalopathies. In this study, we searched for GABRA1 mutations in patients with infantile epilepsy to investigate the phenotypic spectrum of GABRA1 mutations.

Efficacy of idebenone for respiratory failure in a patient with Leigh syndrome: A long-term follow-up study

Respiratory failure can be the direct cause of death in patients with Leigh syndrome. Unfortunately, no effective treatment strategy is available. Here, we report successful treatment of a patient with Leigh syndrome using idebenone, a derivative of coenzyme Q-10. The patients brainstem function, especially respiratory function, improved after idebenone treatment. Idebenone may be worth trying in patients with Leigh syndrome.

Reduced levels of interleukin-1 receptor antagonist in the cerebrospinal fluid in patients with West syndrome.

We measured the levels of pro- and anti-inflammatory cytokines in the cerebrospinal fluid (CSF) of 24 patients with West syndrome to clarify whether inflammatory cytokines were involved in the pathophysiology of West syndrome. There was no significant elevation of any of the three pro-inflammatory cytokines, interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha, in patients with West syndrome as compared with those in controls. However, level of anti-inflammatory cytokine, IL-1 receptor antagonist was significantly decreased in the CSF of patients with West syndrome. Further study is needed to elucidate whether an immune system disturbance is involved in the pathophysiology of West syndrome.

Utility of subtraction ictal SPECT images in detecting focal leading activity and understanding the pathophysiology of spasms in patients with West syndrome

PURPOSES The aims of the study were to evaluate the detectability of focal leading activity in three cases of West syndrome having focal abnormal activity on EEG by comparing subtraction ictal images and raw ictal images, and to interpret the results in 16 cases. METHODS Subtraction images were constructed using iNeurostat (revision 2). RESULTS In three cases with focal abnormal activity on EEG, subtraction ictal images reflected the EEG findings; in contrast, raw ictal images did not. Diverse degrees of cortical hyperperfusion, ranging from zero to 10 sites, seen in the other 13 cases seemed to reflect spasm pathophysiology and rapid spasm propagation. Subtraction ictal images also allowed the ready detection of hyperperfusion of subcortical structures and of a tight cortico-subcortical relationship in a subset of cases. CONCLUSIONS We showed the superiority of subtraction ictal images in detecting the focal epileptic region and in showing propagation pathways from the cortex to subcortical structures. A subset of spasms in WS may be focal cortical-onset secondarily generalized seizures. We believe that subtraction analysis is valuable in patients with complex WS who have partial seizures and spasms simultaneously along with focal epileptic EEG activity, as they will likely be candidates for epilepsy surgery.

Clinical features and long-term outcome of a group of Japanese children with inflammatory central nervous system disorders and seropositivity to myelin-oligodendrocyte glycoprotein antibodies

BACKGROUND Myelin-oligodendrocyte glycoprotein and aquaporin-4 have been extensively analyzed as targets for humoral immune reactions in central nervous system (CNS) demyelinating diseases, and the results indicated a possible role of these antibodies in the pathogenesis of various demyelinating diseases. OBJECTIVE To investigate the antibody titer levels against myelin-oligodendrocyte glycoprotein and aquaporin-4 in pediatric patients with inflammatory CNS disorders, and to evaluate clinical significance to study anti-myelin-oligodendrocyte glycoprotein antibodies. METHODS Sera at onset from patients with acute disseminated encephalomyelitis (ADEM) in 7, optic neuritis (ON) in 5, pediatric MS in 4 and neuromyelitis optica in one were tested for myelin-oligodendrocyte glycoprotein and aquaporin-4 antibodies using cell-based assays with live transfected cells. The duration of the observation periods ranged from 1 to 21 years (median, 10 years). We also described clinical course of patients with positive anti-myelin-oligodendrocyte glycoprotein antibodies. RESULTS Among 17 patients diagnosed with inflammatory CNS demyelinating diseases nine (52%) were positive to anti-myelin-oligodendrocyte glycoprotein antibodies. Of note, all cases with positive anti-myelin-oligodendrocyte glycoprotein antibodies showed seronegativity against anti-aquaporin-4 antibodies and had a favorable prognosis. CONCLUSIONS This preliminary report showed that anti-myelin-oligodendrocyte glycoprotein antibodies testing at onset could be a useful tool predicting clinical outcome of children with ADEM, ON, and MS.

FDG-PET study of patients with Leigh syndrome

We conducted a [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) study in five patients (median age 11 (range 4-13) years) with Leigh syndrome to evaluate its usefulness for understanding the functional brain dysfunction in this disease and in future drug trials. Four patients were found to have reported mitochondrial DNA gene mutations. The brain T2-weighted magnetic resonance imaging (MRI) showed high-intensity areas in the putamen bilaterally in five patients, caudate bilaterally in four, thalamus bilaterally in two, and brainstem in one. Cerebellar atrophy was observed in older two patients. For disease control, seven age-matched epilepsy patients who had normal MRI and FDG-PET studies were selected. For semiquantitative analysis of the lesions with decreased (18)F-FDG uptake, the mean standard uptake value (SUV) was calculated in regions of interest (ROIs) placed in each brain structure. We compared the SUV of nine segments (the frontal, temporal, parietal, and occipital lobes, thalami, basal ganglia, mid-brain, pons, and cerebellum) between patients with Leigh syndrome and controls. The glucose uptake was decreased significantly in the cerebellum and basal ganglia, which could explain the ataxia and dystonia in patients with Leigh syndrome. Although this study had some limitations, FDG-PET might be useful for evaluating the brain dysfunction and treatment efficacy of new drugs in patients with Leigh syndrome. Further study with more patients using advanced methods to quantify glucose uptake is needed before drawing a conclusion.

Hypoperfusion in caudate nuclei in patients with brain–lung–thyroid syndrome

Mutations in NKX2-1 cause neurological, pulmonary, and thyroid hormone impairment. Recently, the disease was named brain-lung-thyroid syndrome. Here, we report three patients with brain-lung-thyroid syndrome. All patients were unable to walk until 24 months of age, and still have a staggering gait, without mental retardation. They have also had choreoathetosis since early infancy. Genetic analysis of NKX2-1 revealed a novel missense mutation (p.Val205Phe) in two patients who were cousins and their maternal families, and a novel 2.6-Mb deletion including NKX2-1 on chromosome 14 in the other patient. Congenital hypothyroidism was not detected on neonatal screening in the patient with the missense mutation, and frequent respiratory infections were observed in the patient with the deletion in NKX2-1. Oral levodopa did not improve the gait disturbance or involuntary movement. The results of (99m)Tc-ECD single-photon emission computed tomography (ECD-SPECT) analyzed using the easy Z-score imaging system showed decreased cerebral blood flow in the bilateral basal ganglia, especially in the caudate nuclei, in all three patients, but no brain magnetic resonance imaging (MRI) abnormalities. These brain nuclear image findings indicate that NKX2-1 haploinsufficiency causes dysfunction of the basal ganglia, especially the caudate nuclei, resulting in choreoathetosis and gait disturbance in this disease.

Elevated serum levels of neutrophil elastase in patients with influenza virus-associated encephalopathy

We examined serum levels of various cytokines, chemokines, growth factors, and adhesion molecules in patients with uncomplicated influenza (n=20) and influenza virus-associated encephalopathy (IE) (n=18) to understand the underlying mechanism of IE. We found that IL-1β, IL-2, IL-5, IL-6, IL-7, IL-8, IL-10, IL-13, G-CSF, GM-CSF, TNF-α, TIMP-1, MMP-9, sE-selectin, and neutrophil elastase were elevated significantly in sera from patients with uncomplicated influenza and those with IE, compared with normal controls (n=20). Of note, neutrophil elastase, sE-selectin, IL-8, and IL-13 were elevated significantly in IE as compared with uncomplicated influenza. In the present study, for the first time, we found that serum levels of neutrophil elastase were increased in patients with IE compared with uncomplicated influenza, which suggested that cerebral endothelial damage in the development of IE was mediated by neutrophil elastase. The present study implied that anti-elastase agents are possibly an effective therapeutic protocol for IE, but this needs further elucidation.