Naoko Matsui

Increasing incidence of elderly onset patients with myasthenia gravis in a local area of Japan

Objective: As the number of elderly patients with myasthenia gravis (MG) has recently increased in Europe and the USA, a retrospective survey of Japanese MG patients was conducted in a single neurological centre over several decades. Methods: The study consisted of 112 consecutive MG patients with onset of the disease from 1971 to 2006 from an area of approximately 0.8 million inhabitants in Japan. Patients were classified into three subgroups according to age at onset: young onset (39 years old), middle aged onset (40–59 years old) and elderly onset (60 years old). The trends in incidence rate and clinical features were examined: disease severity, seropositivity for antiacetylcholine receptor antibody, occurrence of other autoimmune diseases, occurrence of thymoma and therapeutic response. Results: The onset adjusted age specific average annual incidence per 100 000 of the elderly onset MG patients increased 20-fold from 1981–1990 (0.06; 95% CI 0.00 to 0.36) to 2001–2006 (1.30; 95% CI 0.77 to 2.05). Clinical features of the elderly onset MG patients included low antiacetylcholine receptor antibody titres (mean 24.6 nmol/l), less frequent autoimmune overlaps (8.0%) and nearly no complete stable remission with or without thymectomy. Conclusion: The increasing incidence of elderly onset MG in Japanese patients similar to that reported in Caucasians has been confirmed. The clinical features suggest different immunological backgrounds between young onset and elderly onset MG patients, irrespective of the ethnic background.

UNDIMINISHED REGULATORY T CELLS IN THE THYMUS OF PATIENTS WITH MYASTHENIA GRAVIS

Objective: The thymus has been implicated as a possible site of origin that triggers autoimmunity in myasthenia gravis (MG). Although several groups have suggested that the decrease in the number of regulatory T (Treg) cells contributes to the onset of MG, the exact role of Treg cells in MG remains unclear. To address this point, we examined the number and distribution of Treg cells in a large number of patients with MG. Methods: Immunohistofluorescence analysis of Foxp3 along with CD4 and CD8 was performed in thymic sections of MG (+) (n = 24) and MG (−) patients (n = 27). Circulating CD4+CD25+ cells in the peripheral blood of patients with MG (n = 15) and age-matched healthy subjects (n = 15) were also analyzed. Results: Foxp3+CD4+CD8− cells were predominantly found in the thymic medulla and their number declined with age. There was no significant difference in the number or the distribution of Foxp3+CD4+CD8− cells in the thymus between MG (+) and MG (−) patients. The number of circulating CD4+CD25+ cells in the peripheral blood of patients with MG was not significantly altered compared to that in healthy subjects. Conclusion: The cellularity of Treg cells in the thymus and circulation is not diminished in patients with myasthenia gravis.

Prenylation Enhances Quercetin Uptake and Reduces Efflux in Caco-2 Cells and Enhances Tissue Accumulation in Mice Fed Long Term

Prenyl flavonoids are widely distributed in plant foods and have attracted appreciable attention in relation to their potential benefits for human health. Prenylation may enhance the biological functions of flavonoids by introducing hydrophobic properties in their basic structures. Previously, we found that 8-prenyl naringenin exerted a greater preventive effect on muscle atrophy than nonprenylated naringenin in a mouse model. Here, we aimed to estimate the effect of prenylation on the bioavailability of dietary quercetin (Q). The cellular uptake of 8-prenyl quercetin (PQ) and Q in Caco-2 cells and C2C12 myotube cells was examined. Prenylation significantly enhanced the cellular uptake by increasing the lipophilicity in both cell types. In Caco-2 cells, efflux of PQ to the basolateral side was <15% of that of Q, suggesting that prenylation attenuates transport from the intestine to the circulation. After intragastric administration of PQ or Q to mice or rats, the area under the concentration-time curve for PQ in plasma and lymph was 52.5% and 37.5% lower than that of Q, respectively. PQ and its O-methylated form (MePQ) accumulated at much higher amounts than Q and O-methylated Q in the liver (Q: 3400%; MePQ: 7570%) and kidney (Q: 385%; MePQ: 736%) of mice after 18 d of feeding. These data suggest that prenylation enhances the accumulation of Q in tissues during long-term feeding, even though prenylation per se lowers its intestinal absorption from the diet.

CSF cytokine profile distinguishes multifocal motor neuropathy from progressive muscular atrophy

Objective: We aimed to compare the cytokine and chemokine profiles of patients with multifocal motor neuropathy (MMN) with those of patients with progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS) to investigate immunologic differences in the CNS. Methods: CSF from 12 patients with MMN, 8 with PMA, 26 with sporadic ALS, and 10 with other noninflammatory neurologic disorders was analyzed for 27 cytokines and chemokines using the multiplex bead array assay. Cytokine titers of the 4 groups were compared, and correlations between the titers of relevant cytokines and clinical parameters were evaluated. Results: There were no obvious intrathecal changes except for interleukin (IL)-1 receptor antagonist in patients with MMN. In contrast, IL-4, IL-7, IL-17, eotaxin/CCL11, fibroblast growth factor-2 (FGF-2), granulocyte colony-stimulating factor (G-CSF), and platelet-derived growth factor BB titers were significantly elevated in patients with PMA and ALS; of these, FGF-2 and G-CSF titers were elevated compared with those in patients with MMN. IL-4 and IL-10 titers were high in patients with ALS, particularly patients with possible ALS presenting with a slowly progressive course or mild symptoms. Conclusions: The CSF cytokine profile of patients with MMN is distinct from that of patients with PMA and ALS. The similarity of the cytokine profiles between patients with PMA and ALS suggests that PMA shares common immunologic features with ALS in the CNS, even without clinical evidence of upper motor neuron involvement.

Are multifocal motor neuropathy patients underdiagnosed? An epidemiological survey in Japan.

Introduction: Our objective was to do an epidemiologic survey of patients with multifocal motor neuropathy (MMN) in comparison with those with amyotrophic lateral sclerosis (ALS) in Japan. Methods: In this retrospective study, we examined 46 patients with MMN and 1,051 patients with ALS from major neuromuscular centers in Japan from 2005 to 2009. Diagnosis was based on the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) and the revised El Escorial criteria. The efficacy of intravenous immunoglobulin (IVIg) was also taken into consideration in the diagnosis of MMN. Results: The ratio of MMN to ALS patients (0–0.10) varied among the centers, but mostly converged to 0.05. The prevalence was estimated to be 0.29 MMN patients and 6.63 ALS patients per 100,000 population. Conclusions: The frequency of MMN patients was around 1 out of 20 ALS patients, and MMN was possibly underdiagnosed in some centers. Muscle Nerve 49:357–361, 2014

Increased proinflammatory cytokines in sera of patients with multifocal motor neuropathy

BACKGROUND Multifocal motor neuropathy (MMN) is characterized by clinical improvement with intravenous immunoglobulin and the frequent detection of anti-ganglioside antibodies. However, the immunological background of the neuronal damage in MMN is still unclear. OBJECTIVE The aim of this study is to investigate abnormalities in the cytokine and chemokine profiles of MMN patients. METHODS Sera from 16 patients with MMN, 16 patients with sporadic amyotrophic lateral sclerosis (ALS), and 15 patients with other non-inflammatory neurological diseases (ONDs) were analyzed for 27 cytokines and chemokines using a multiplex bead array. We also checked whether the altered cytokine/chemokine profile in the MMN group differed significantly in the presence or absence of abnormal electrophysiological findings. RESULTS Serum IL-1Ra, IL-2, G-CSF, TNF-α, and TNFR1 levels were significantly higher in the MMN group than in the ONDs group. Of these, G-CSF and TNF-α also showed significant increases compared to the ALS group. Serum G-CSF and TNF-α levels were significantly higher in MMN patients presenting with focal demyelination including conduction block than in patients without any focal demyelination. CONCLUSIONS Proinflammatory cytokines may contribute to peripheral nerve demyelination in MMN.

Intramuscular dissociation of echogenicity in the triceps surae characterizes sporadic inclusion body myositis

Differential diagnosis of sporadic inclusion body myositis (s‐IBM) and polymyositis (PM)/dermatomyositis (DM) is difficult and can affect proper disease management. Detection of heterogeneous muscular involvement in s‐IBM by muscle sonography could be a unique diagnostic feature.

Preventive effect of dietary quercetin on disuse muscle atrophy by targeting mitochondria in denervated mice.

Quercetin is a major dietary flavonoid in fruits and vegetables. We aimed to clarify the preventive effect of dietary quercetin on disuse muscle atrophy and the underlying mechanisms. We established a mouse denervation model by cutting the sciatic nerve in the right leg (SNX surgery) to lack of mobilization in hind-limb. Preintake of a quercetin-mixed diet for 14days before SNX surgery prevented loss of muscle mass and atrophy of muscle fibers in the gastrocnemius muscle (GM). Phosphorylation of Akt, a key phosphorylation pathway of suppression of protein degradation, was activated in the quercetin-mixed diet group with and without SNX surgery. Intake of a quercetin-mixed diet suppressed the generation of hydrogen peroxide originating from mitochondria and elevated mitochondrial peroxisome proliferator-activated receptor-γ coactivator 1α mRNA expression as well as NADH dehydrogenase 4 expression in the GM with SNX surgery. Quercetin and its conjugated metabolites reduced hydrogen peroxide production in the mitochondrial fraction obtained from atrophied muscle. In C2C12 myotubes, quercetin reached the mitochondrial fraction. These findings suggest that dietary quercetin can prevent disuse muscle atrophy by targeting mitochondria in skeletal muscle tissue through protecting mitochondria from decreased biogenesis and reducing mitochondrial hydrogen peroxide release, which can be related to decreased hydrogen peroxide production and/or improvements on antioxidant capacity of mitochondria.

Increased number of Hassall's corpuscles in myasthenia gravis patients with thymic hyperplasia

The thymus is implicated as an organ that contributes to autoimmunity in myasthenia gravis (MG) patients. Hassalls corpuscles (HCs) are assumed to represent the terminally differentiated stage of medullary thymic epithelial cells (mTECs). By using multicolor immunohistofluorescence analysis, we examined HCs in thymuses that were therapeutically excised from MG (+) and MG (-) patients. We found that the number of HCs per unit area of the thymic medulla was significantly elevated in the thymuses of MG (+) patients with thymic hyperplasia. CCL21 expression increased in the hyperplastic MG thymuses. We speculate that the altered differentiation of mTECs is associated with the thymic hyperplasia and the onset of MG.

抗利尿ホルモン分泌異常症候群で発症し，橋中心・橋外髄鞘崩壊症を合併した視神経脊髄炎関連疾患の1例

A 36-year-old woman complained of general malaise. She presented with hyponatremia and plasma osmotic pressure was lower than urinary osmotic pressure. In addition, serum antidiuretic hormone level was higher than the measurement sensitivity. She was diagnosed with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). She fell into a coma despite correction of serum sodium level. Brain magnetic resonance imaging (MRI) revealed high signal intensities in the cerebral cortex, striatum, thalamus, hypothalamus, midbrain, and pons in fluid-attenuated inversion recovery images. Spinal MRI revealed a longitudinally extending lesion in the cervical cord. Serum sample was positive for anti-aquaporin-4 antibody, supporting the diagnosis of neuromyelitis optica spectrum disorder (NMOSD) combined with central pontine and extrapontine myelinolysis. In patients with NMOSD, the immune reaction can gradually cause destructive changes of the hypothalamus and lead to unstable ADH secretion in the absence of immunomodulatory treatment.