- Email: [email protected]
THE R47H TREM2 VARIANT MODIFIES ALZHEIMER'S DISEASE PATHOLOGY AND NEUROINFLAMMATION IN A NOVEL KNOCK-IN MOUSE MODEL
Podium Presentations: Monday, July 25, 2016 Davis, CA, USA; 4University of California, Davis, CA, USA; 5Emory University, Atlanta, GA, USA. Contact e-mail: [email protected] Background: Microglia and associated neuroinflammation play a sig-
nificant role in Alzheimer’s disease (AD). The voltage-gated potassium channel Kv1.3 (KCNA3) fine-tunes microglia activation by modulating Ca2+ signaling. Because selective pharmacological targeting of Kv1.3 in microglia in the brain is feasible and safe, we tested the effects of a selective Kv1.3 blocker PAP-1 in models of AD. Methods: Human AD brains drawn from the brain repositories of the University of California Davis and the Emory University were used for immunohistochemical analyses of Kv1.3. 5xFAD mice, which harbor three amyloid-b precursor protein (APP) and two presenilin-1 (PS1) mutations resulting in AD-like Ab amyloidosis and neuroinflammation, were used for behavioral, electrophysiological, biochemical and neuropathological analyses. Results: Kv1.3 immunoreactivities were localized exclusively to microglia in both human and mouse brains and were increased in human AD subjects and 5xFAD mice. Microglial Kv1.3 activity as measured by whole-cell patch-clamp was increased in young and middle-aged 5xFAD mice, but decreased in old (>13 months) 5xFAD mice compared to age- and gender-matched wildtype controls. Ab oligomers (AbO) were able to enhance microlgial Kv1.3 expression. PAP-1 treatment reduced AbO-induced microglial neurotoxicity in vitro and in vivo. A three-month oral regimen of PAP1 improved the hippocampus-dependent memory performance and rectified the hippocampal long-term potentiation of 5xFAD mice. Conclusions: Microglial Kv1.3 is a potential therapeutic target and oral dosing of PAP-1 is a promising anti-inflammatory approach for AD. 02-07-06
THE R47H TREM2 VARIANT MODIFIES ALZHEIMER’S DISEASE PATHOLOGY AND NEUROINFLAMMATION IN A NOVEL KNOCK-IN MOUSE MODEL
Paul Cheng-Hathaway1, Taylor Jay1, Erin Reed1, Shane Bemiller2, Shweta Puntambekar2, Guixiang Xu2, Colleen Carlo1, Richard Ransohoff3, Gary Landreth1, Bruce T. Lamb2, 1Case Western Reserve University, School of Medicine, Cleveland, OH, USA; 2Indiana University, Stark Neurosciences Research Institute, Indianapolis, IN, USA; 3BIogen, Cambridge, MA, USA. Contact e-mail: [email protected] Background: Genetic variants in TREM2 have been associated with
several neurodegenerative diseases. Recessive loss of function mutations in TREM2 results in Nasu-Hakola disease, characterized by bone cysts and a non-AD dementia while the heterozygous R47H variant in TREM2 confers increased risk for late onset AD. Several groups have postulated that the R47H variant is loss of function. However, in our previous study, we found that complete TREM2 deficiency in an AD mouse model resulted in a significant attenuation of AD-like pathology. It therefore becomes critical to determine whether the R47H variant in AD exhibits loss of function, gain of function, dominant negative function or a combination of functions on AD phenotypes. Methods: To examine the role of the R47H TREM2 variant in AD pathogenesis, genome edititing technology was utilized to introduce the R47H variant into the mouse Trem2 gene (Trem2R47H/+) and the resulting mice subsequently mated to the APPPS1 mouse model of AD. APPPS1;Trem2R47H/+, APPPS1;Trem2+/+, APPPS1;Trem2-/+, and APPPS1;Trem2-/- mice were aged to 4 months of age and examined for amyloid production and deposition, neuroinflammation and macrophage accuulation and proliferation. Results: Using CRISPR/Cas genome editing, we generated novel transgenic animals containing the AD risk allele, R47H. For the current studies, we compared APPPS1;Trem2R47H/+, APPPS1;Trem2+/+, APPP-
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S1;Trem2-/+, and APPPS1;Trem2-/- mice at 4 months of age via biochemical and histological studies. Strikingly, these studies demonstrated that APPPS1;Trem2R47H/+ mice exhibited both loss and gain of function(s) with regards to AD phenotypes, including amyloid deposition, neuroinflammation and macrophage accumulation when compared to the three other genotypes (APPPS1;Trem2+/+, APPPS1;Trem2-/+, and APPPS1;Trem2-/-). Conclusions: The current studies report on the generation of a unique mouse model of the R47H TREM2 risk allele via genome editing that was subsequently crossed to the APPPS1 mouse model of AD. These findings suggest that the R47H AD risk variant exhibits a variety of both loss and gain of function(s) depending upon the AD phenoytpe that is examined and also suggests that TREM2’s function(s) are likely pleiotropic in nature. Further experiments are needed to understand the mechanism via which the R47H TREM2 variant impacts myeloid cell function as well as other AD phenotypes (including neruonal function and tau pathology) that will ultimately assist in designing TREM2- focused therapies for AD. MONDAY, JULY 25, 2016 ORAL SESSIONS O2-08 NEUROIMAGING: CLINICAL STAGING AND DIAGNOSIS OF DEMENTIA USING NEUROIMAGING BIOMARKERS O2-08-01
AV1451 PET IMAGING IN THE SPECTRUM OF ALZHEIMER’S DISEASE FROM CLINICALLY NORMAL TO DEMENTIA
David S. Knopman, Heather J. Wiste, Clifford R. Jack Jr, Ronald C. Petersen, Bradley F. Boeve, Kejal Kantarci, David T. Jones, Michelle M. Mielke, Rosebud O. Roberts, Stephen D. Weigand, Jonathan Graff-Radford, Prashanthi Vemuri, Mary M. Machulda, Val J. Lowe, Mayo Clinic, Rochester, MN, USA. Contact e-mail: knopman@ mayo.edu Background: Tau (AV1451) PET has recently been introduced, and its ability to distinguish among clinically normal, mild cognitive impairment and dementia in the Alzheimer disease (AD) spectrum has not been established. Methods: We studied 121 clinically normal (CN) amyloid negative (A-), 54 CN amyloid positive (A+), 19 mild cognitively impaired (MCI) A-, 16 MCI A+ and 32 dementia with elevated amyloid (A+) (28 probable AD, 1 possible AD, 1 posterior cortical atrophy, and 2 logopenic PPA) (age range 52-94 yrs across entire group) with MR, 11C PIB PET and 18F-AV1451 PET imaging. Regional uptake of AV1451 was quantitated using the ratio uptake in each of 46 atlas regions scaled to the crus (SUVR). A+ was defined as PIB SUVR >1.4. Within each region of interest (ROI), we examined group-wise differences in AV1451 SUVR in CN A+ versus CN A-, MCI A+ versus CN A+, MCI A+ versus MCI A-, and dementia A+ versus MCI A+. The area under the receiver operating characteristic curve (AUROC) was calculated. Results: We created medial temporal (MT, from amygdala, entorhinal cortex, parahippocampal), lateral temporal (LT, from fusiform, lingual, inferior temporal, middle temporal) and lateral parietal (LP, from angular, supramarginal, inferior parietal) meta-ROIs to facilitate between-group comparisons. There were significant elevations in AV1451 SUVR in MT (AUROC¼0.66; p<0.001) and LT (AUROC¼0.63; p¼0.008) in CN A+ versus CN A-. There were significant elevations (all p0.001) in all 3 metaROIs in MCI A+ versus CN A+ (AUROCs: MT¼ 0.77, LT¼0. 87, LP¼0.81), MCI A+ versus MCI A- (AUROCs: MT¼0.88, LT¼0.94, LP¼0.84), and in dementia A+ versus MCI A+ (AUROCs: MT¼0.85, LT¼0.86, LP¼0.82). See Figure (PIB+¼
nificant role in Alzheimer’s disease (AD). The voltage-gated potassium channel Kv1.3 (KCNA3) fine-tunes microglia activation by modulating Ca2+ signaling. Because selective pharmacological targeting of Kv1.3 in microglia in the brain is feasible and safe, we tested the effects of a selective Kv1.3 blocker PAP-1 in models of AD. Methods: Human AD brains drawn from the brain repositories of the University of California Davis and the Emory University were used for immunohistochemical analyses of Kv1.3. 5xFAD mice, which harbor three amyloid-b precursor protein (APP) and two presenilin-1 (PS1) mutations resulting in AD-like Ab amyloidosis and neuroinflammation, were used for behavioral, electrophysiological, biochemical and neuropathological analyses. Results: Kv1.3 immunoreactivities were localized exclusively to microglia in both human and mouse brains and were increased in human AD subjects and 5xFAD mice. Microglial Kv1.3 activity as measured by whole-cell patch-clamp was increased in young and middle-aged 5xFAD mice, but decreased in old (>13 months) 5xFAD mice compared to age- and gender-matched wildtype controls. Ab oligomers (AbO) were able to enhance microlgial Kv1.3 expression. PAP-1 treatment reduced AbO-induced microglial neurotoxicity in vitro and in vivo. A three-month oral regimen of PAP1 improved the hippocampus-dependent memory performance and rectified the hippocampal long-term potentiation of 5xFAD mice. Conclusions: Microglial Kv1.3 is a potential therapeutic target and oral dosing of PAP-1 is a promising anti-inflammatory approach for AD. 02-07-06
THE R47H TREM2 VARIANT MODIFIES ALZHEIMER’S DISEASE PATHOLOGY AND NEUROINFLAMMATION IN A NOVEL KNOCK-IN MOUSE MODEL
Paul Cheng-Hathaway1, Taylor Jay1, Erin Reed1, Shane Bemiller2, Shweta Puntambekar2, Guixiang Xu2, Colleen Carlo1, Richard Ransohoff3, Gary Landreth1, Bruce T. Lamb2, 1Case Western Reserve University, School of Medicine, Cleveland, OH, USA; 2Indiana University, Stark Neurosciences Research Institute, Indianapolis, IN, USA; 3BIogen, Cambridge, MA, USA. Contact e-mail: [email protected] Background: Genetic variants in TREM2 have been associated with
several neurodegenerative diseases. Recessive loss of function mutations in TREM2 results in Nasu-Hakola disease, characterized by bone cysts and a non-AD dementia while the heterozygous R47H variant in TREM2 confers increased risk for late onset AD. Several groups have postulated that the R47H variant is loss of function. However, in our previous study, we found that complete TREM2 deficiency in an AD mouse model resulted in a significant attenuation of AD-like pathology. It therefore becomes critical to determine whether the R47H variant in AD exhibits loss of function, gain of function, dominant negative function or a combination of functions on AD phenotypes. Methods: To examine the role of the R47H TREM2 variant in AD pathogenesis, genome edititing technology was utilized to introduce the R47H variant into the mouse Trem2 gene (Trem2R47H/+) and the resulting mice subsequently mated to the APPPS1 mouse model of AD. APPPS1;Trem2R47H/+, APPPS1;Trem2+/+, APPPS1;Trem2-/+, and APPPS1;Trem2-/- mice were aged to 4 months of age and examined for amyloid production and deposition, neuroinflammation and macrophage accuulation and proliferation. Results: Using CRISPR/Cas genome editing, we generated novel transgenic animals containing the AD risk allele, R47H. For the current studies, we compared APPPS1;Trem2R47H/+, APPPS1;Trem2+/+, APPP-
P243
S1;Trem2-/+, and APPPS1;Trem2-/- mice at 4 months of age via biochemical and histological studies. Strikingly, these studies demonstrated that APPPS1;Trem2R47H/+ mice exhibited both loss and gain of function(s) with regards to AD phenotypes, including amyloid deposition, neuroinflammation and macrophage accumulation when compared to the three other genotypes (APPPS1;Trem2+/+, APPPS1;Trem2-/+, and APPPS1;Trem2-/-). Conclusions: The current studies report on the generation of a unique mouse model of the R47H TREM2 risk allele via genome editing that was subsequently crossed to the APPPS1 mouse model of AD. These findings suggest that the R47H AD risk variant exhibits a variety of both loss and gain of function(s) depending upon the AD phenoytpe that is examined and also suggests that TREM2’s function(s) are likely pleiotropic in nature. Further experiments are needed to understand the mechanism via which the R47H TREM2 variant impacts myeloid cell function as well as other AD phenotypes (including neruonal function and tau pathology) that will ultimately assist in designing TREM2- focused therapies for AD. MONDAY, JULY 25, 2016 ORAL SESSIONS O2-08 NEUROIMAGING: CLINICAL STAGING AND DIAGNOSIS OF DEMENTIA USING NEUROIMAGING BIOMARKERS O2-08-01
AV1451 PET IMAGING IN THE SPECTRUM OF ALZHEIMER’S DISEASE FROM CLINICALLY NORMAL TO DEMENTIA
David S. Knopman, Heather J. Wiste, Clifford R. Jack Jr, Ronald C. Petersen, Bradley F. Boeve, Kejal Kantarci, David T. Jones, Michelle M. Mielke, Rosebud O. Roberts, Stephen D. Weigand, Jonathan Graff-Radford, Prashanthi Vemuri, Mary M. Machulda, Val J. Lowe, Mayo Clinic, Rochester, MN, USA. Contact e-mail: knopman@ mayo.edu Background: Tau (AV1451) PET has recently been introduced, and its ability to distinguish among clinically normal, mild cognitive impairment and dementia in the Alzheimer disease (AD) spectrum has not been established. Methods: We studied 121 clinically normal (CN) amyloid negative (A-), 54 CN amyloid positive (A+), 19 mild cognitively impaired (MCI) A-, 16 MCI A+ and 32 dementia with elevated amyloid (A+) (28 probable AD, 1 possible AD, 1 posterior cortical atrophy, and 2 logopenic PPA) (age range 52-94 yrs across entire group) with MR, 11C PIB PET and 18F-AV1451 PET imaging. Regional uptake of AV1451 was quantitated using the ratio uptake in each of 46 atlas regions scaled to the crus (SUVR). A+ was defined as PIB SUVR >1.4. Within each region of interest (ROI), we examined group-wise differences in AV1451 SUVR in CN A+ versus CN A-, MCI A+ versus CN A+, MCI A+ versus MCI A-, and dementia A+ versus MCI A+. The area under the receiver operating characteristic curve (AUROC) was calculated. Results: We created medial temporal (MT, from amygdala, entorhinal cortex, parahippocampal), lateral temporal (LT, from fusiform, lingual, inferior temporal, middle temporal) and lateral parietal (LP, from angular, supramarginal, inferior parietal) meta-ROIs to facilitate between-group comparisons. There were significant elevations in AV1451 SUVR in MT (AUROC¼0.66; p<0.001) and LT (AUROC¼0.63; p¼0.008) in CN A+ versus CN A-. There were significant elevations (all p0.001) in all 3 metaROIs in MCI A+ versus CN A+ (AUROCs: MT¼ 0.77, LT¼0. 87, LP¼0.81), MCI A+ versus MCI A- (AUROCs: MT¼0.88, LT¼0.94, LP¼0.84), and in dementia A+ versus MCI A+ (AUROCs: MT¼0.85, LT¼0.86, LP¼0.82). See Figure (PIB+¼