- Email: [email protected]
IMPROVING THE STATISTICAL ANALYSIS OF COGNITIVE OUTCOMES IN RANDOMISED CONTROLLED TRIALS: THE ‘OPTIMISING THE ANALYSIS OF COGNITION COLLABORATION’ (OA-COG)
Poster Presentations: Sunday, July 16, 2017 P1-021
IMPROVING THE STATISTICAL ANALYSIS OF COGNITIVE OUTCOMES IN RANDOMISED CONTROLLED TRIALS: THE ‘OPTIMISING THE ANALYSIS OF COGNITION COLLABORATION’ (OA-COG)
Polly Scutt, Alan Montgomery, Philip M. Bath, University of Nottingham, Nottingham, United Kingdom. Contact e-mail: polly.scutt@ nottingham.ac.uk Background: Over 800,000 people suffer with dementia in the UK. Despite being common, devastating to patients and their families, and costly in economic terms to society, the evidence base for the treatment of cognitive decline and dementia is small. One reason for this may be that the measures used to assess cognition in clinical trials are not sensitive to change and/or the analyses used are suboptimal. The ‘Optimising the analysis of cognition collaboration’ (OA-Cog) aims to identify the most efficient cognitive measurement and analysis technique for cognition data and dementia in randomised controlled trials including patients with or at risk of vascular dementia or Alzheimer’s disease. Methods: Chief investigators of randomised controlled trials with cognitive outcome assessments are asked to share individual patient data from their trials. Variables requested include baseline prognostic factors, treatment group, cognitive measures (e.g. Mini Mental State Examination (MMSE), Alzheimer’s Disease Assessment Scale cognitive sub-score (ADAS-cog)) and other outcome measures (e.g. death, dementia). Shared trial data are merged into a single dataset and analysed using various endpoints (e.g. mean MMSE score at end of trial, MMSE score as a gradient over time) and statistical methods (e.g. Wilcoxon rank-sum test, repeated measures ANOVA) in order to identify which is the most efficient approach. Methods for dealing with missing data and, in particular, the case of missing data due to death will be addressed; currently, such patients are often ignored from analyses. Results: As of 23rd December 2016, data from 32 clinical trials have been shared with the collaboration. Some of these trials have more than two treatment arms, so 50 datasets are available with a total of 120,576 participants. Conclusions: Optimising the design and analysis of cognition trials will allow future trials to detect smaller but still clinically important effects, and/or have smaller sample sizes than current trials.
P1-022
CHARACTERIZING THE EFFECTS OF MICROGLIAL ELIMINATION AND REPOPULATION ON ABETA AND TAU PATHOLOGY
Lindsay A. Hohsfield1, Kim N. Green1, Brian L. West2, 1University of California, Irvine, Irvine, CA, USA; 2Plexxikon Inc., Berkeley, CA, USA. Contact e-mail: [email protected] Background: Microglia are the primary immune cells of the brain
and provide maintenance for CNS homeostasis and synaptic integrity. However, microglial activation can lead to neurodegeneration and aggravation of AD pathogenesis, implicating microglia as important therapeutic targets for AD. Microglia are dependent on signaling through the colony stimulating factor-1 receptor (CSF1R). Using CSF1R inhibitors we can eliminate the majority of microglia, and upon inhibitor withdrawal, can rapidly replace this cellular compartment with new microglia. We sought to investigate whether microglial replacement could reset the inflammatory state of the AD brain or impact neuropathology. Methods: Eighteenmonth-old 3xTg-AD mice were treated for two weeks with a selective CSF1R inhibitor (PLX5622; 1200 mg/kg chow) and then returned to control diet for four weeks, allowing for microglial
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repopulation. Results: We achieved extensive microglial elimination and repopulation in 3xTg-AD mice, but observe that a subpopulation of plaque-associated microglia remain following elimination. Furthermore, elimination of microglia does not modulate plaque numbers or sizes. Microglial repopulation, on the other hand, reduces small Thioflavin S+ deposits, indicating repopulated microglia are capable of phagocytosing and clearing certain plaques. Furthermore, mRNA expression of phagocytosis-related genes is increased with repopulation, while overall inflammatory pathway signaling is decreased. These results indicate that replacing microglia may help stimulate amyloid phagocytosis and reduce pro-inflammatory signaling associated with a chronically activated disease state. Following microglial elimination, we also observe a significant increase in neuronal tau staining, Gallyas staining, and insoluble tau levels, which all become reduced after repopulation. Conclusions: These findings indicate that microglia have an important and dynamic role in the clearance of AD-associated pathologies, and that replacing microglia may provide a key to resetting the neuroinflammatory mileu and neurodegenerative disease state. P1-023
THE PREDICTION METHOD OF DELETERIOUS VARIANTS FOR ALZHEIMER’S DISEASE USING CHROMATIN HIGHER-ORDER STRUCTURE
Masataka Kikuchi1, Norikazu Hara2, Mai Hasegawa3, Akinori Miyashita2, Ryozo Kuwano2, Takeshi Ikeuchi2, Akihiro Nakaya1, 1Graduate School of Medicine, Osaka University, Osaka, Japan; 2Brain Research Institute, Niigata University, Niigata, Japan; 3Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Chiba, Japan. Contact e-mail: kikuchi@ gi.med.osaka-u.ac.jp Background: The most common cause of dementia is late-onset Alz-
heimer’s disease (AD), which occurs in individuals aged >65 years and leads to neuronal death. The heritability of AD was reported as approximately 60-80%, indicating that the genetic factors are strongly associated with the pathogenesis of AD. To identify the genetic variants associated with AD, genome-wide association studies (GWAS) and whole-exome sequencing have been performed across some cohorts and ethnic groups. However most of these loci are located within introns and intergenic regions. In this study, we explored whether AD-associated variants are in functional non-coding regions such as enhancers, and predicted a deleterious effect of AD-associated variants. Given that enhancers participate in longrange interactions via chromatin loops, we determined these longrange chromatin interactions for AD-associated variants in candidate regions of enhancers and searched for genes in the neighborhood of AD-associated variants. Methods: We collected 208 AD-associated variants from the GWAS catalog database and defined enhancers by transcription factor binding motifs, DNase-peaks and ChiP-seq data of enhancer marks (H3K4me3 and H3K27ac). We explored AD-associated variants close to the enhancers. To identify longrange chromatin interactions for AD-associated variants, we performed tethered conformation capture (TCC) in the human neuroblastoma SK-N-SH and human astrocytoma U-251 MG cell lines. Results: We found that 19 AD-associated variants lying in non-coding regions were localized in the proximity of regulatory elements. These variants are predicted to work as enhancers/silencers and may have a deleterious effect on the transcription of distant genes. For instance, 2 variants in the APOE gene cluster, which includes APOE, a strong risk factor for AD, were localized in transcription factor binding regions. Furthermore, analysis of the chromatin
IMPROVING THE STATISTICAL ANALYSIS OF COGNITIVE OUTCOMES IN RANDOMISED CONTROLLED TRIALS: THE ‘OPTIMISING THE ANALYSIS OF COGNITION COLLABORATION’ (OA-COG)
Polly Scutt, Alan Montgomery, Philip M. Bath, University of Nottingham, Nottingham, United Kingdom. Contact e-mail: polly.scutt@ nottingham.ac.uk Background: Over 800,000 people suffer with dementia in the UK. Despite being common, devastating to patients and their families, and costly in economic terms to society, the evidence base for the treatment of cognitive decline and dementia is small. One reason for this may be that the measures used to assess cognition in clinical trials are not sensitive to change and/or the analyses used are suboptimal. The ‘Optimising the analysis of cognition collaboration’ (OA-Cog) aims to identify the most efficient cognitive measurement and analysis technique for cognition data and dementia in randomised controlled trials including patients with or at risk of vascular dementia or Alzheimer’s disease. Methods: Chief investigators of randomised controlled trials with cognitive outcome assessments are asked to share individual patient data from their trials. Variables requested include baseline prognostic factors, treatment group, cognitive measures (e.g. Mini Mental State Examination (MMSE), Alzheimer’s Disease Assessment Scale cognitive sub-score (ADAS-cog)) and other outcome measures (e.g. death, dementia). Shared trial data are merged into a single dataset and analysed using various endpoints (e.g. mean MMSE score at end of trial, MMSE score as a gradient over time) and statistical methods (e.g. Wilcoxon rank-sum test, repeated measures ANOVA) in order to identify which is the most efficient approach. Methods for dealing with missing data and, in particular, the case of missing data due to death will be addressed; currently, such patients are often ignored from analyses. Results: As of 23rd December 2016, data from 32 clinical trials have been shared with the collaboration. Some of these trials have more than two treatment arms, so 50 datasets are available with a total of 120,576 participants. Conclusions: Optimising the design and analysis of cognition trials will allow future trials to detect smaller but still clinically important effects, and/or have smaller sample sizes than current trials.
P1-022
CHARACTERIZING THE EFFECTS OF MICROGLIAL ELIMINATION AND REPOPULATION ON ABETA AND TAU PATHOLOGY
Lindsay A. Hohsfield1, Kim N. Green1, Brian L. West2, 1University of California, Irvine, Irvine, CA, USA; 2Plexxikon Inc., Berkeley, CA, USA. Contact e-mail: [email protected] Background: Microglia are the primary immune cells of the brain
and provide maintenance for CNS homeostasis and synaptic integrity. However, microglial activation can lead to neurodegeneration and aggravation of AD pathogenesis, implicating microglia as important therapeutic targets for AD. Microglia are dependent on signaling through the colony stimulating factor-1 receptor (CSF1R). Using CSF1R inhibitors we can eliminate the majority of microglia, and upon inhibitor withdrawal, can rapidly replace this cellular compartment with new microglia. We sought to investigate whether microglial replacement could reset the inflammatory state of the AD brain or impact neuropathology. Methods: Eighteenmonth-old 3xTg-AD mice were treated for two weeks with a selective CSF1R inhibitor (PLX5622; 1200 mg/kg chow) and then returned to control diet for four weeks, allowing for microglial
P241
repopulation. Results: We achieved extensive microglial elimination and repopulation in 3xTg-AD mice, but observe that a subpopulation of plaque-associated microglia remain following elimination. Furthermore, elimination of microglia does not modulate plaque numbers or sizes. Microglial repopulation, on the other hand, reduces small Thioflavin S+ deposits, indicating repopulated microglia are capable of phagocytosing and clearing certain plaques. Furthermore, mRNA expression of phagocytosis-related genes is increased with repopulation, while overall inflammatory pathway signaling is decreased. These results indicate that replacing microglia may help stimulate amyloid phagocytosis and reduce pro-inflammatory signaling associated with a chronically activated disease state. Following microglial elimination, we also observe a significant increase in neuronal tau staining, Gallyas staining, and insoluble tau levels, which all become reduced after repopulation. Conclusions: These findings indicate that microglia have an important and dynamic role in the clearance of AD-associated pathologies, and that replacing microglia may provide a key to resetting the neuroinflammatory mileu and neurodegenerative disease state. P1-023
THE PREDICTION METHOD OF DELETERIOUS VARIANTS FOR ALZHEIMER’S DISEASE USING CHROMATIN HIGHER-ORDER STRUCTURE
Masataka Kikuchi1, Norikazu Hara2, Mai Hasegawa3, Akinori Miyashita2, Ryozo Kuwano2, Takeshi Ikeuchi2, Akihiro Nakaya1, 1Graduate School of Medicine, Osaka University, Osaka, Japan; 2Brain Research Institute, Niigata University, Niigata, Japan; 3Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Chiba, Japan. Contact e-mail: kikuchi@ gi.med.osaka-u.ac.jp Background: The most common cause of dementia is late-onset Alz-
heimer’s disease (AD), which occurs in individuals aged >65 years and leads to neuronal death. The heritability of AD was reported as approximately 60-80%, indicating that the genetic factors are strongly associated with the pathogenesis of AD. To identify the genetic variants associated with AD, genome-wide association studies (GWAS) and whole-exome sequencing have been performed across some cohorts and ethnic groups. However most of these loci are located within introns and intergenic regions. In this study, we explored whether AD-associated variants are in functional non-coding regions such as enhancers, and predicted a deleterious effect of AD-associated variants. Given that enhancers participate in longrange interactions via chromatin loops, we determined these longrange chromatin interactions for AD-associated variants in candidate regions of enhancers and searched for genes in the neighborhood of AD-associated variants. Methods: We collected 208 AD-associated variants from the GWAS catalog database and defined enhancers by transcription factor binding motifs, DNase-peaks and ChiP-seq data of enhancer marks (H3K4me3 and H3K27ac). We explored AD-associated variants close to the enhancers. To identify longrange chromatin interactions for AD-associated variants, we performed tethered conformation capture (TCC) in the human neuroblastoma SK-N-SH and human astrocytoma U-251 MG cell lines. Results: We found that 19 AD-associated variants lying in non-coding regions were localized in the proximity of regulatory elements. These variants are predicted to work as enhancers/silencers and may have a deleterious effect on the transcription of distant genes. For instance, 2 variants in the APOE gene cluster, which includes APOE, a strong risk factor for AD, were localized in transcription factor binding regions. Furthermore, analysis of the chromatin