Elimination of apoptotic neurons without inflammation is crucial for brain tissue homeostasis, but the molecular mechanism has not been firmly established. Triggering receptor expressed on myeloid cells-2 (TREM2) is a recently identified innate immune receptor. Here, we show expression of TREM2 in microglia. TREM2 stimulation induced DAP12 phosphorylation, extracellular signal–regulated kinase phosphorylation, and cytoskeleton reorganization and increased phagocytosis. Knockdown of TREM2 in microglia inhibited phagocytosis of apoptotic neurons and increased gene transcription of tumor necrosis factor α and nitric oxide synthase-2, whereas overexpression of TREM2 increased phagocytosis and decreased microglial proinflammatory responses. Thus, TREM2 deficiency results in impaired clearance of apoptotic neurons and inflammation that might be responsible for the brain degeneration observed in patients with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy/Nasu-Hakola disease.

BackgroundIn multiple sclerosis, inflammation can successfully be prevented, while promoting repair is still a major challenge. Microglial cells, the resident phagocytes of the central nervous system (CNS), are hematopoietic-derived myeloid cells and express the triggering receptor expressed on myeloid cells 2 (TREM2), an innate immune receptor. Myeloid cells are an accessible source for ex vivo gene therapy. We investigated whether myeloid precursor cells genetically modified to express TREM2 affect the disease course of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis.Methods and FindingsEAE was induced in mice by immunization with a myelin autoantigen. Intravenous application of TREM2-transduced bone marrow–derived myeloid precursor cells at the EAE peak led to an amelioration of clinical symptoms, reduction in axonal damage, and prevention of further demyelination. TREM2-transduced myeloid cells applied intravenously migrated into the inflammatory spinal cord lesions of EAE-diseased mice, showed increased lysosomal and phagocytic activity, cleared degenerated myelin, and created an anti-inflammatory cytokine milieu within the CNS.ConclusionsIntravenously applied bone marrow–derived and TREM2-tranduced myeloid precursor cells limit tissue destruction and facilitate repair within the murine CNS by clearance of cellular debris during EAE. TREM2 is a new attractive target for promotion of repair and resolution of inflammation in multiple sclerosis and other neuroinflammatory diseases.

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Although metal intoxication after arthroplasty causes various symptoms, polyneuropathy has never been the focus of clinical investigation. We report the case of a 56‐year‐old woman with metal neuropathy. She had metallosis after hip arthroplasty with a cobalt–chromium alloy prosthesis. She developed progressive sensory disturbance, hearing loss, and hypothyroidism. Sural nerve biopsy indicated axonopathy. After exchange arthroplasty, blood levels of cobalt and chromium decreased, and her symptoms improved. Cobalt or chromium can cause axonopathy. Muscle Nerve, 2010

Multiple sclerosis is a chronic demyelinating disease of presumed autoimmune pathogenesis. The patients with multiple sclerosis typically shows alternating relapse and remission in the early stage of illness. We previously found that in the majority of multiple sclerosis patients in a state of remission, natural killer (NK) cells contain unusually high frequencies of the cells expressing CD95 (Fas) on their surface (>36.0%). Here we report that in such 'CD95+ NK-high' patients, NK cells may actively suppress potentially pathogenic autoimmune T cells that can mediate the inflammatory responses in the CNS. Using peripheral blood mononuclear cells (PBMCs) derived from 'CD95+ NK-high' or 'CD95+ NK-low' multiple sclerosis in a state of remission, we studied the effect of NK cell depletion on the memory T cell response to myelin basic protein (MBP), a major target antigen of multiple sclerosis. When we stimulated PBMCs of the 'CD95+ NK-high' multiple sclerosis after depleting CD56+ NK cells, a significant proportion of CD4+ T cells (1/2000 to 1/200) responded rapidly to MBP by secreting interferon (IFN)-gamma, whereas such a rapid T cell response to MBP could not be detected in the presence of NK cells. Nor did we detect the memory response to MBP in the 'CD95+ NK-low' multiple sclerosis patients in remission or healthy subjects, regardless of whether NK cells were depleted or not. Depletion of cells expressing CD16, another NK cell marker, also caused IFN-gamma secretion from MBP-reactive CD4+ T cells in the PBMCs from 'CD95+ NK-high' multiple sclerosis. Moreover, we showed that NK cells from 'CD95+ NK-high' multiple sclerosis could inhibit the antigen-driven secretion of IFN-gamma by autologous MBP-specific T cell clones in vitro. These results indicate that NK cells may regulate activation of autoimmune memory T cells in an antigen non-specific fashion to maintain the clinical remission in 'CD95(+) NK-high' multiple sclerosis patients.

In the ageing society, sarcopenia, in which muscle strength and motor function decline with age, has attracted attention, and many researchers have investigated different testing and treatment methods. 1-6 Aspiration resulting from reduced swallowing function is a problem in the elderly, and aspiration pneumonia significantly deteriorates the life prognosis and QOL. 7 These disorders associated with reduced swallowing function were dysphagia. As sarcopenia is involved in the onset of dysphagia, 8,9 the relationship between sarcopenia and dysphagia has attracted attention. AbstractBackground: Sarcopenia in the oral region, including the tongue, leads to declined swallowing function and dysphagia. Muscle mass and strength, and motor function in the oral region have not been examined together, and the relationship between generalised and oral sarcopenia remains unclear. Objective(s):The purpose of this study is to clarify the relationship between generalised sarcopenia and oral sarcopenia in the elderly in order to facilitate the establishment of a method for assessing oral sarcopenia. Methods:A total of 54 elderly persons participated in this study. We examined the skeletal muscle mass index (SMI), grip strength (GS) and walking speed (WS) as the index of generalised sarcopenia, and the cross-sectional area of the geniohyoid muscle (CSG), tongue pressure (TP) and oral diadochokinesis (ODK) as the index of oral sarcopenia. Results:We found a moderate correlation between CSG and SMI, a weak correlation between GS and TP, and a moderate correlation between WS and ODK. CSG, TP and ODK were significantly smaller in the sarcopenia group than in the non-sarcopenia group. By multiple regression analysis, SMI and TP were significantly associated with CSG. ODK, BMI and CSG were significantly associated with TP. WS and SMI were significantly associated with ODK.Conclusion: CSG, TP and ODK were confirmed as endpoints of oral sarcopenia. All endpoints of oral sarcopenia were influenced by those of generalised sarcopenia. K E Y W O R D Sgeniohyoid muscle, oral diadochokinesis, oral sarcopenia, sarcopenia, tongue pressure | 637 KOBUCHI et al.

Axonal transport of mitochondria and synaptic vesicle precursors via kinesin motor proteins is essential to keep integrity of axons and synapses. Disturbance of axonal transport is an early sign of neuroinflammatory and neurodegenerative diseases. Treatment of cultured neurons by the inflammatory cytokine tumor necrosis factor-alpha (TNF) stimulated phosphorylation of c-Jun N-terminal kinase (JNK) in neurites. TNF treatment induced dissociation of the heavy chain kinesin family-5B (KIF5B) protein from tubulin in axons but not cell bodies as determined by lifetime-based Förster resonance energy transfer (FRET) analysis. Dissociation of KIF5B from tubulin after TNF treatment was dependent on JNK activity. Furthermore, TNF inhibited axonal transport of mitochondria and synaptophysin by reducing the mobile fraction via JNK. Thus, TNF produced by activated glial cells in inflammatory or degenerative neurological diseases acts on neurites by acting on the kinesin-tubulin complex and inhibits axonal mitochondria and synaptophysin transport via JNK.