Suppressed pro-inflammatory properties of circulating B cells in patients with multiple sclerosis treated with fingolimod, based on altered proportions of B-cell subpopulations.

The chief therapeutic mechanism of fingolimod in multiple sclerosis (MS) is considered to be sequestration of pathogenic lymphocytes into secondary lymphoid tissues. B cells have recently been recognized as important immune regulators in MS. In this study, the effects of fingolimod on B cells in MS patients were analyzed. MS patients treated with fingolimod (MS-F) had a significantly lower number of B cells in the circulation. The remaining B cells in the blood of MS-F had a reduced proportion of memory B cells and an increased proportion of naïve B cells, expressed lower levels of the costimulatory molecule CD80, and produced less tumor necrosis factor-α and more interleukin-10. These observations in MS-F were based on an increased proportion of the transitional B-cell subpopulation within the naïve B-cell compartment. The observed findings in B cells of MS-F might be related to the therapeutic effect of this drug in MS.

[A case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) complicated by chronic intestinal pseudo-obstruction].

A 42-year-old woman presented at our hospital with acute paraphasia and word finding difficulty. She was not paralyzed or ataxic. Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) was diagnosed based on brain MRI finding of edematous lesions in bilateral temporal lobe cortexes that did not match the vascular territory, elevated lactate and pyruvate levels in blood and cerebrospinal fluid, and the presence of a mtDNA 3243A>G mutation. From six months before her visit, she had persistent anorexia, bloating, nausea and vomiting, and weight loss to 25 kg. We diagnosed her condition as chronic intestinal pseudo-obstruction (CIPO) associated with MELAS, because a gastroenterologist had previously diagnosed her with megacolon associated with colonic dysfunction. Usually, CIPO is often associated with the chronic phase of MELAS. However, since CIPO complication from the early stage of the disease is occasionally encountered, it is necessary to include mitochondrial disease in differential diagnosis of CIPO of unknown cause.

[Morvan syndrome associated with unresectable thymoma responsive to chemotherapy: a case report].

A 51-year-old Japanese man presenting with a several-month history of parasomnia, orthostatic hypotension and generalized myokymia was admitted to our hospital. He had a past medical history of unresectable recurrent thymoma, but chemotherapy for thymoma was discontinued according to the patient's decision four years before this hospitalization, and the thymoma had enlarged. He exhibited symptoms of the peripheral nervous system (myokymia), central nervous system (parasomnia, short-term memory impairment), and autonomic nervous system (orthostatic hypotension), and his serum was positive for voltage-gated potassium channel (VGKC)-complex antibodies. Based on the above findings, Morvan syndrome was diagnosed. Resumption of chemotherapy for thymoma resulted in shrinkage of the thymoma accompanied by remission of Morvan syndrome. Subsequently, discontinuation of chemotherapy led to aggravation of thymoma with recurrence of Morvan syndrome. This clinical course suggests a strong correlation between the disease activity of thymoma and Morvan syndrome. In the present case of Morvan syndrome associated with unresectable thymoma, chemotherapy contributed to the remission of Morvan syndrome. Our patient suggests a possibility that chemotherapy for thymoma is a useful treatment for Morvan syndrome.

Usefulness of 11C-methionine-positron emission tomography for the diagnosis of progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating disease of the brain caused by the JC virus that occurs mainly in immunocompromised patients. The prognosis is very poor. As the lesion looks like non- specific leukoencephalopathy, making a diagnosis at the early stage is very difficult. We report three PML cases in which there was a mismatch between (11)C-methionine-positron emission tomography (MET-PET) uptake and (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) uptake. All three cases demonstrated the hyper-uptake of MET around the white matter lesions and hypo-uptake of FDG inside the lesions. We speculate that the infection had ended inside the white matter lesions of these patients, while JC virus infection was ongoing around the lesions, resulting in the increase of methionine metabolism, and the glucose metabolism was reduced or intermediate because inflammatory cells infiltrate PML lesions rarely. Two patients who were diagnosed and treated with mefloquine while the JC virus was at a low level in the cerebrospinal fluid are still alive. We suggest the usefulness of MET-PET for the early diagnosis of PML and early treatment with mefloquine.