Trinity College Dublin · Institute of Neuroscience
Oct 2011 - Oct 2014
Trinity College Dublin
Oct 2009 - Oct 2010
Trinity College Dublin
Background: BIOMARKAPD seeks to diminish the barriers associated with the clinical use of cerebrospinal fluid (CSF) biomarker analysis by reducing variation in CSF laboratory methodologies and generating consensus recommendations on their clinical interpretation and application for dementia diagnosis. Objective: To examine the disparity in practitioner attitudes and clinical practice relating to the use of CSF biomarkers for dementia diagnosis across Europe. Methods: Clinical dementia experts were surveyed on the prevalence of national consensus guidelines and analytical reimbursement across Europe; their biomarker platform preferences, lumbar puncture methodologies, and application of reference values and cut-offs for CSF analysis. Results: 74% of respondents (total n = 51) use CSF biomarkers in clinical practice and 69% performed lumbar punctures on an outpatient basis. Most use CSF biomarkers to diagnose atypical (84%) and early onset cases of cognitive impairment (71%) and for the differential diagnosis of other dementias (69%). 82% state they are sufficiently informed about CSF biomarkers yet 61% report a lack of national consensus guidelines on their use for dementia diagnosis. 48% of countries represented do not reimburse clinical CSF analysis. 43% report using normal reference ranges derived from publications. Conclusion: Variations in attitude and practice relating to CSF biomarkers, widely recognized as barriers to their clinical acceptance, remain evident within and between countries across Europe, even in expert centers. These shortcomings must be addressed by developing consensus guidelines on CSF-related methodologies and their clinical application to further their use for the diagnostic evaluation of dementia.
Aim: Neurofilament light (NfL) chain, a putative cerebrospinal fluid biomarker, can support neurodegenerative disease diagnosis and indicate disease severity and prognosis. Universal validation protocols when used to measure biomarkers can reduce pre and analytical laboratory variation, thus increasing end-user confidence in the consistency of validation data across sites. Methodology: Here, a commercially available NfL ELISA (UmanDiagnostics, Umeå, Sweden) was validated in a multicentered setting using comprehensive newly developed standard operating procedures. Results: The data showed good assay sensitivity and intra and interassay precision. Interlaboratory precision was, however, suboptimal. Conclusion: The UmanDiagnostics assay is suitable for the quantification of NfL in human cerebrospinal fluid. However, sources of interlaboratory variation in the data require further investigation.
EBI2 is a G protein-coupled receptor activated by oxysterol 7α, 25-dihydroxycholesterol (7α25HC) and regulates T cell-dependant antibody response and B cell migration. We recently found EBI2 is expressed in human astrocytes, regulates intracellular signalling and modulates astrocyte migration. Here, we report that LPS treatment of mouse astrocytes alters mRNA levels of EBI2 and oxysterols suggesting that the EBI2 signalling pathway is sensitive to LPS-mediated immune challenge. We also find that conditioned media obtained from LPS-stimulated mouse astrocytes induces macrophage migration, which is inhibited by the EBI2 antagonist NIBR189. These results demonstrate a role for the EBI2 signalling pathway in astrocytes as a sensor for immune challenge and for communication with innate immune cells such as macrophages.
Oxysterols are pleiotropic messengers interacting with multiple receptor systems. One of the cognate receptors for oxysterols is EBI2, a G protein-coupled receptor highly expressed in the cells of the immune system. Here we discuss the receptor's role in the adapted immunity and inflammation as well as the receptor's expression and function in the CNS with the focus on astrocytes. We also discuss expression and signalling of oxysterol-producing enzymes such as CH25H and CYP7B1 in the CNS and the immune system. These steps will help to elucidate a possible role for this pathway in the physiology of the central and peripheral nervous system and its possible link to human disease.
Background: The G protein-coupled receptor EBI2 (Epstein-Barr virus-induced gene 2) is activated by 7α, 25-dihydroxycholesterol (7α25HC) and plays a role in T cell-dependant antibody response and B cell migration. Abnormal EBI2 signaling is implicated in a range of autoimmune disorders; however, its role in the CNS remains poorly understood. Methods: Here we characterize the role of EBI2 in myelination under normal and pathophysiological conditions using organotypic cerebellar slice cultures and EBI2 knock-out (KO) animals. Results: We find that MBP expression in brains taken from EBI2 KO mice is delayed compared to those taken from wild type (WT) mice. In agreement with these in vivo findings, we show that antagonism of EBI2 reduces MBP expression in vitro. Importantly, we demonstrate that EBI2 activation attenuates lysolecithin (LPC)-induced demyelination in mouse organotypic slice cultures. Moreover, EBI2 activation also inhibits LPC-mediated release of pro-inflammatory cytokines such as IL6 and IL1β in cerebellar slices. Conclusions: These results, for the first time, display a role for EBI2 in myelin development and protection from demyelination under pathophysiological conditions and suggest that modulation of this receptor may be beneficial in neuroinflammatory and demyelinating disorders such as multiple sclerosis.
The G protein-coupled receptor EBI2 (Epstein–Barr virus-induced gene 2) is activated by 7α, 25-dihydroxycholesterol (7α25HC) and plays a role in T cell-dependant antibody response and B cell migration. Aberrant EBI2 signaling is implicated in a range of autoimmune disorders however its role in the CNS remains unknown. Here we characterize the functional role of EBI2 in GLIA cells using primary human astrocytes and EBI2 knockout animals. We find human and mouse astrocytes express EBI2 and the enzymes necessary for synthesis and degradation of 7α25HC. In astrocytes, EBI2 activation stimulates ERK phosphorylation, Ca2+ signaling and induces cellular migration. These results, for the first time, demonstrate a role for EBI2 in astrocyte function and suggest that modulation of this receptor may be beneficial in neuroinflammatory disorders. GLIA 2014
The family of interleukin 17 receptors (IL17Rs), subtypes IL17RA-IL17RE, is targeted by the group of pro-inflammatory IL17 cytokines (IL17A-F) and moreover the newly developed anti-IL17A antibody secukinumab (AIN457) has shown promise in Phase II trials in multiple sclerosis. Here, we show that human astrocytes, isolated from a fetal cerebral cortex, express IL17RA and IL17RC and in vitro treatment with IL17A increases protein levels of IL6 in human astrocytes, which is enhanced in the presence of TNFα, as determined by homogeneous time resolved fluorescence. Studies on acutely isolated mouse astrocytes are comparable to human astrocytes although the protein levels of IL6 are lower in mouse astrocytes, which also show a lower response to IL17F and IL1β in promoting IL6 levels. In human astrocytes, IL17A and TNFα also induce mRNA expression of IL6, IL8 and the Th17 cytokines CXCL1, CXCL2, and CCL20, with little effect on Th1 cytokines CXCL9, CXCL10, and CXCL11. The effects of IL17A are associated with nuclear translocation of the NF-κB transcription factor, as determined by immunocytochemistry, where treatment of human astrocytes with the inhibitors of the NF-κB pathway and with secukinumab inhibits the IL17A and IL17A/TNFα-induced increase in nuclear translocation of NF-κB and levels of IL6. Taken together the data shows that IL17A signaling plays a key role in regulating the levels of cytokines, such as IL6, in human astrocytes via a mechanism that involves NF-κB signaling and that selective inhibition of IL17A signaling attenuates levels of pro-inflammatory molecules in astrocytes. GLIA 2014
Objective Smoking cessation is crucial for patients with coronary heart disease (CHD), yet depression may impede cessation success. We systematically reviewed the prospective association between depression and subsequent smoking cessation in individuals with CHD to quantify this effect.Methods Electronic databases (PsychInfo, PubMed, CINAHL) were searched for prospective studies of patients with CHD that measured depression at baseline (scales, diagnostic interview, or antidepressant prescription) and reported smoking continuation/cessation at follow-up. Inclusive dates were January 1, 1990, to May 22, 2013. Standardized mean differences (SMDs) and associated 95% confidence intervals were estimated using random-effects meta-analysis. Sensitivity analysis explored the impact of limiting meta-analysis to studies using different depression measures (validated scales, diagnostic interviews, antidepressant prescription), different durations of follow-up, or higher-quality studies.ResultsFrom 1185 citations retrieved, 28 relevant articles were identified. Meta-analysis of all available data from 20 unique data sets found that depressed patients with CHD were significantly less likely to quit smoking at follow-up (SMD = -0.39, 95% confidence interval = -0.50 to -0.29; I(2) = 51.2%, p = .005). Estimates remained largely unchanged for each sensitivity analysis, except for two studies that used antidepressants, which showed a much larger effect (SMD = -0.94, -1.38 to -0.51; I(2) = 57.7%, p = .124).Conclusions Patients with CHD and depressive symptoms are significantly less likely to quit smoking than their nondepressed counterparts. This may have implications for cardiovascular prognosis, and CHD smokers may require aggressive depression treatment to enhance their chances of quitting.
The sphingosine 1-phosphate receptor subtype 1 (S1P1R) is modulated by phosphorylated FTY720 (pFTY720), which causes S1P1R internalization preventing lymphocyte migration thus limiting autoimmune response. Studies indicate that internalized S1P1Rs continue to signal, maintaining an inhibition of cAMP, thus raising question whether the effects of pFTY720 are due to transient initial agonism, functional antagonism and/or continued signalling. To further investigate this, the current study first determined if continued S1P1R activation is pathway specific. Using human and rat astrocyte cultures, the effects of S1P1R activation on cAMP, pERK and Ca2+ signalling was investigated. In addition, to examine the role of S1P1R redistribution on these events, a novel biologic (MNP301) that prevented pFTY720-mediated S1P1R redistribution was engineered. The data showed that pFTY720 induced long-lasting S1P1R redistribution and continued cAMP signalling in rat astrocytes. In contrast, pFTY720 induced a transient increase of Ca2+ in astrocytes and subsequent antagonism of Ca2+ signalling. Notably, while leaving pFTY720-induced cAMP signalling intact, the novel MNP301 peptide attenuated S1P1R-mediated Ca2+ and pERK signalling in cultured rat astrocytes. These findings suggested that pFTY720 causes continued cAMP signalling that is not dependent on S1P1R redistribution and induces functional antagonism of Ca2+ signalling after transient stimulation. To our knowledge, this is the first report demonstrating that pFTY720 causes continued signalling in one pathway (cAMP) versus functional antagonism of another pathway (Ca2+) and which also suggests that redistributed S1P1Rs may have differing signalling properties from those expressed at the surface.
Objectives : Depression and vital exhaustion are associated with poor cardiovascular prognosis, but there is substantial overlap between these constructs. Factor analytic studies have been inconclusive, and may not be the optimal analytic strategy to assess dimensionality. We assessed whether exhaustion and depression formed a single, hierarchical dimension using a form of nonparametric item response theory. Methods : Patients with acute coronary syndrome (n = 430) completed questionnaires assessing depression and vital exhaustion. Mokken scaling was used to assess dimensionality. Results : Mokken scaling formed a strong unidimensional scale, ordered in a hierarchy reflecting prevalence: fatigue (common), depression (less common) and hopelessness (rare). Conclusions : Depressive symptoms form a clear hierarchy in cardiac patients, from fatigue to hopelessness. Vital exhaustion may be considered a less severe form of depression. Use of hierarchical scales may allow clinicians to better determine clinical significance and target interventions.