CDR3 spectratyping analysis of the TCR repertoire in myasthenia gravis.

Because myasthenia gravis (MG) is an autoimmune disease mediated by Abs specific for the acetylcholine receptor, helper T cells play a role in Ab production. In this study, we have performed large-scale cross-sectional and longitudinal TCR studies by CDR3 spectratyping using PBL and thymus tissues from MG patients. We found that there was no preferential usage of any particular TCR beta-chains that was identical among MG patients. However, the longitudinal study clearly demonstrated that one or more TCR Vbeta expansions persisted frequently in MG patients. Importantly, persistent TCR expansions correlated with clinical severity and high anti-acetylcholine receptor Ab titer. Finally, examinations of T cells expressing CXCR5, i.e., follicular B-helper T cells, revealed that spectratype expansions in MG patients were detected mainly in the CD4+ CXCR5+ T cell populations, whereas CD8+ T cells were the major source of clonal expansion in healthy subjects. These findings suggest that persistent clonal expansions of T cells in MG patients are associated with the development and maintenance of MG. Close examination of pathogenic T cells in MG provides useful information to elucidate the pathogenesis and to estimate the disease status.

[Case of CADASIL showing spontaneous subcortical hemorrhage with a novel mutation of Notch3 gene].

The case of a 72-year-old demented woman having episodes of strokes without any risk factors for cardiovascular disease is reported. Her elder brother and sister have also had stroke episodes since their middle age. She experienced hallucinations, delusions, and recurrent headaches since the age of 55. She has gradually developed gait disturbance and cognitive impairment. Brain MRI revealed extensive leukoaraiosis and multiple lacunar infarcts in the deep white matter and brainstem. Repeated MRI incidentally disclosed fresh hemorrhage in the dorsal subcortical temporal lobe, which appeared to be asymptomatic. Anti-platelet agents were not used during disease progression. We detected G975C mutation of the Notch3 gene and diagnosed our patient's disease as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This report suggests that arteriopathy of CADASIL could cause a hemorrhagic process, indicating that, in such a case, routine administration of anti-platelet agent to prevent recurrent ischemic stroke is not recommended.

[An elder case of neurosarcoidosis associated with brain infarction].

A 75-year-old woman with sarcoidosis developed sudden weakness of the left upper and lower limbs. Neurological examination revealed left-sided hemiplegia, hyperreflexia with pathological reflexes and hypesthesia. She was disoriented and euphoric. Diffusion-weighted brain MRI showed high intensity lesions in the right parietooccipital lobes. Electroencephalogram showed diffuse slowing of the background activity. Serum lysozyme increased to 18.4 mg/ml, CSF protein to 51 mg/dl. After admission, she presented psychotic manifestation followed by a progressive disturbance of consciousness. Epithelioid granulomas without caseous necrosis were present in the biopsied lymph node and specimens from the occipital cortex, indicating neurosarcoidosis. Necrosis was also present in the sampled brain tissue. The psychotic symptoms and consciousness disturbance rapidly ameliorated after the treatment with oral prednisolone, 40 mg/day. Neurosarcoidosis should be considered even in an elder case of sarcoidosis complicated with a stroke.

Genetic, clinical and pathological studies of CADASIL in Japan: a partial contribution of Notch3 mutations and implications of smooth muscle cell degeneration for the pathogenesis.

We have examined Notch3 mutations in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) whose samples were submitted to us in Japan. The subjects were composed of 21 Japanese, 1 Iranian, 1 Korean and 1 Canadian families. Mutations in the Notch3 gene were found in 7 of 24 families examined. These were R133C in two unrelated Japanese families, and R213K, C174F and R169C in each Japanese family. In addition, we have found R90C in an Iranian family and C174R in a Korean family. Thus, contribution of Notch3 gene mutations is less than one fourth of Japanese CADASIL families, suggesting the existence of other causative genes in CADASIL. It is also of interest to know that Notch3 mutant CADASIL exists in other Asian countries. We next examined the localization of Notch3 protein in the tissue by immunohistochemistry. It was restricted to the wall of arterioles in the brain and other organs. In the brain, there was no difference in the staining pattern among arterioles in the cortex, white matter and meninges. The staining was negative in the venule and capillaries as well as in neurons and glial cells. From the staining pattern, it was recognized to be expressed in the vascular smooth muscle cells in the adult tissue. In an autopsy case with R213K mutation, we could see numerous cerebral infarcts and arteriole wall degeneration with deposits of granular osmiophilic material (GOM). However, it is interesting to note that occlusion of arterioles was rarely observed and the GOM was negative for Notch3 staining. These findings suggest that hemodynamic abnormalities due to smooth muscle cell degeneration may be important in the pathogenesis of CADASIL.