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Tarr J.M.,Universities of Exeter and Plymouth | Ding N.,Universities of Exeter and Plymouth | Ding N.,Capital Medical University | Kaul K.,Universities of Exeter and Plymouth | And 4 more authors.
Cellular Signalling | Year: 2012

Increasing evidence suggests that chronic, sub-clinical inflammation plays an important role in the pathogenesis of diabetic retinopathy. We have established the potential role of the inflammatory enzyme, core 2 β-1, 6-N-acetylglucosaminyltransferase (C2GNT) in diabetic retinopathy. The present study was designed to explore the NADPH oxidase signaling pathway in the tumor necrosis factor-alpha (TNF-α)-induced activity of C2GNT in leukocytes. Human leukocytes (U937 cells) and an Epstein-Barr-transformed lymphoblastoid cell line deficient in p47phox (F10007 cells) were used for the study. Cells were exposed to TNF-α for 24. h in the presence and absence of 1) NADPH oxidase inhibitors (apocynin and scrambled and unscrambled gp91ds-tat), 2) LY379196 (specific protein kinase C β1/2 (PKCβ1/2) inhibitor), and 3) the antioxidant tiron. Subsequent C2GNT and NADPH activity was measured and the adhesion of U937 and F10007 cells to endothelial cells was assessed. TNF-α-induced C2GNT activity (1813 ± 326. pmol/h/mg protein) (mean ± SEM) in human leukocytes was significantly reversed with apocynin (153 ± 82. pmol/h/mg protein), unscrambled gp91ds-tat (244 ± 122. pmol/h/mg protein) and tiron (756 ± 87. pmol/h/mg protein). We further supported this C2GNT-NADPH oxidase link using p47phox-deficient leukocytes. The deficiency in p47phox prevented TNF-α-induced NADPH oxidase and C2GNT activity and adherence to endothelial cells. The response to TNF-α was restored by transfection with an expression plasmid containing a p47phox cDNA inserted in the sense direction. Our results demonstrate for the first time a novel signaling crosstalk between TNF-α, NADPH oxidase, PKCβ1/2 and C2GNT in leukocytes. © 2011 Elsevier Inc.

Lancaster E.,University of Pennsylvania | Lai M.,University of Pennsylvania | Peng X.,University of Pennsylvania | Hughes E.,University of Pennsylvania | And 13 more authors.
The Lancet Neurology | Year: 2010

Background: Some encephalitides or seizure disorders once thought idiopathic now seem to be immune mediated. We aimed to describe the clinical features of one such disorder and to identify the autoantigen involved. Methods: 15 patients who were suspected to have paraneoplastic or immune-mediated limbic encephalitis were clinically assessed. Confocal microscopy, immunoprecipitation, and mass spectrometry were used to characterise the autoantigen. An assay of HEK293 cells transfected with rodent GABAB1 or GABAB2 receptor subunits was used as a serological test. 91 patients with encephalitis suspected to be paraneoplastic or immune mediated and 13 individuals with syndromes associated with antibodies to glutamic acid decarboxylase 65 were used as controls. Findings: All patients presented with early or prominent seizures; other symptoms, MRI, and electroencephalography findings were consistent with predominant limbic dysfunction. All patients had antibodies (mainly IgG1) against a neuronal cell-surface antigen; in three patients antibodies were detected only in CSF. Immunoprecipitation and mass spectrometry showed that the antibodies recognise the B1 subunit of the GABAB receptor, an inhibitory receptor that has been associated with seizures and memory dysfunction when disrupted. Confocal microscopy showed colocalisation of the antibody with GABAB receptors. Seven of 15 patients had tumours, five of which were small-cell lung cancer, and seven patients had non-neuronal autoantibodies. Although nine of ten patients who received immunotherapy and cancer treatment (when a tumour was found) showed neurological improvement, none of the four patients who were not similarly treated improved (p=0·005). Low levels of GABAB1 receptor antibodies were identified in two of 104 controls (p<0·0001). Interpretation: GABAB receptor autoimmune encephalitis is a potentially treatable disorder characterised by seizures and, in some patients, associated with small-cell lung cancer and with other autoantibodies. Funding: National Institutes of Health. © 2010 Elsevier Ltd. All rights reserved.

Zuliani L.,Ospedale CaFoncello | Zuliani L.,University of Oxford | Graus F.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS | Giometto B.,Ospedale CaFoncello | And 2 more authors.
Journal of Neurology, Neurosurgery and Psychiatry | Year: 2012

The concept of antibody mediated CNS disorders is relatively recent. The classical CNS paraneoplastic neurological syndromes are thought to be T cell mediated, and the onconeural antibodies merely biomarkers for the presence of the tumour. Thus it was thought that antibodies rarely, if ever, cause CNS disease. Over the past 10 years, identification of autoimmune forms of encephalitis with antibodies against neuronal surface antigens, particularly the voltage gated potassium channel complex proteins or the glutamate N-methyl-D-aspartate receptor, have shown that CNS disorders, often without associated tumours, can be antibody mediated and benefit from immunomodulatory therapies. The clinical spectrum of these diseases is not yet fully explored, there may be others yet to be discovered and some types of more common disorders (eg, epilepsy or psychosis) may prove to have an autoimmune basis. Here, the known conditions associated with neuronal surface antibodies are briefly reviewed, some general aspects of these syndromes are considered and guidelines that could help in the recognition of further disorders are suggested.

Boronat A.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS | Sabater L.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS | Saiz A.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS | Dalmau J.,University of Pennsylvania | Graus F.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS
Neurology | Year: 2011

Background: γ-Aminobutyric acid-B receptor antibodies (GABABR-ab) were recently described in 15 patients with limbic encephalitis (LE), associated with small-cell lung cancer (SCLC) or with concurrent glutamic acid decarboxylase (GAD) antibodies. We analyzed the frequency of GABABR-ab in 147 patients with LE or neurologic syndromes associated with GAD-ab. Methods: We examined the presence of GABABR-ab in 70 patients with LE (33 paraneoplastic with onconeural antibodies, 18 paraneoplastic without onconeural antibodies [5 with Gad-ab], and 19 idiopathic with either GAD-ab [5 patients] or seronegative) and 77 patients with GAD-ab-associated neurologic syndromes other than LE (29 stiff-person syndrome, 28 cerebellar ataxia, 14 epilepsy, and 6 with diverse paraneoplastic neurologic syndromes). GABABR-ab were analyzed in serum or CSF by indirect immunofluorescence on HEK293 cells transfected with GABAB1 and GABAB2 receptor subunits. Results: GABABR-ab were detected in 10 of the 70 patients with LE (14%). Eight had SCLC and 2 were idiopathic. One of the 8 patients with LE with SCLC had an additional onconeural antibody (Hu) and 2 GAD-ab. GABA BR-ab were identified in 7 (70%) of the 10 patients with LE and SCLC without onconeural antibodies. GABABR-ab antibodies were not found in patients with GAD-ab and stiff-person syndrome, idiopathic cerebellar ataxia, or epilepsy. However, one patient with GAD-ab, paraneoplastic cerebellar ataxia, and anaplastic carcinoid of the thymus also presented GABABR-ab. Conclusions: GABABR-ab are the most common antibodies found in LE associated with SCLC previously considered "seronegative." In patients with GAD-ab, the frequency of GABABR-ab is low and only observed in the context of cancer. Copyright © 2011 by AAN Enterprises, Inc. All rights reserved.

Linnoila J.J.,Massachusetts General Hospital | Rosenfeld M.R.,Institute dInvestigacio Biomedica August Pi i Sunyer IDIBAPS | Rosenfeld M.R.,Cellex, Inc. | Rosenfeld M.R.,University of Pennsylvania | And 3 more authors.
Seminars in Neurology | Year: 2014

In the past few years, many autoimmune encephalitides have been identified, with specific clinical syndromes and associated antibodies against neuronal surface antigens. There is compelling evidence that many of these antibodies are pathogenic and most of these encephalitides are highly responsive to immunotherapies. The clinical spectra of some of these antibody-mediated syndromes, especially those reported in only a few patients, are evolving. Others, such as anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, are well characterized. Diagnosis involves recognizing the specific syndromes and identifying the antibody in a patient's cerebrospinal fluid (CSF) and/or serum. These syndromes are associated with variable abnormalities in CSF, magnetic resonance imaging, and electroencephalography. Treatment is often multidisciplinary and should be focused upon neutralizing the effects of antibodies and eliminating their source. Overlapping disorders have been noted, with some patients having more than one neurologic autoimmune disease. In other patients, viral infections such as herpes simplex virus encephalitis trigger robust antineuronal autoimmune responses. © 2014 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York.

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