Detection of Alzheimer's disease (AD) specific tau pathology with conformation-selective anti-tau monoclonal antibody in co-morbid frontotemporal lobar degeneration-tau (FTLD-tau).
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ABSTRACT: Pathological tau aggregates in Alzheimer's disease (AD) and frontotemporal lobar degeneration-tau (FTLD-tau) adopt distinct conformations differentiated by the AD-tau specific monoclonal antibody (mAb) GT-38 that are not readily visualized using phosphorylation-specific anti-tau mAbs. To determine the extent of co-morbid AD-tau pathology in FTLD-tau, we performed immunohistochemical (IHC) staining with GT-38 and assigned Braak stages of AD-tau in a cohort 180 FTLD-tau cases consisting of corticobasal degeneration (CBD; n?=?49), progressive supranuclear palsy (PSP; n?=?109), and Pick's disease (PiD; n?=?22). Nearly two-thirds of patients (n?=?115 of 180, 63.8%) with FTLD-tau had some degree of comorbid AD-tau pathology and 20.5% of the FTLD-tau cohort had Braak stage ?B2, consistent with medium-to-high-level AD neuropathological change (ADNPC). The PSP group had the highest frequency of medium-high AD-tau pathology compared to other tauopathies (PSP?=?31/109, 28.4%; Picks?=?2/22, 9.1%, CBD?=?4/49, 8.2%) but neuropathological diagnosis was not found to be a significant independent predictor of medium-high AD Braak stage in a multivariate model after accounting for age at death (OR?=?1.09; 95% CI?=?1.03-1.15; p?=?0.002) and CERAD plaque scores (OR?=?3.75, 95% CI?=?1.58-8.89; p?=?0.003), suggesting there is no predilection for a specific FTLD tauopathy to develop AD-tau co-pathology after accounting for age. Patients with FTLD-tau who had, clinically significant, medium-high AD-tau pathology had significantly higher antemortem CSF levels of both total-tau (t-tau; mean?=?89.98?pg/ml, SD?=?36.70?pg/ml) and phosphorylated-tau (p-tau; mean?=?20.45?pg/ml, SD?=?9.31?pg/ml) compared to patients with negligible-low AD-tau, t-tau (mean?=?43.04?pg/ml, SD?=?25.40?pg/ml) and p-tau (mean?=?11.90?pg/ml, SD?=?4.48?pg/ml) (p???0.001 both). Finally, in an exploratory analysis in our largest pathology group (PSP) we find an association of GT-38?AD-tau Braak stage with lower baseline MMSE (p?=?0.03). Together, these finding validate the use of GT-38 to selectively detect AD-tau pathology in the context of FTLD-tau and provides a novel tool to investigate associations of clinical phenotypes amongst co-morbid tauopathies.
SUBMITTER: Gibbons GS
PROVIDER: S-EPMC6399892 | biostudies-literature | 2019 Mar
REPOSITORIES: biostudies-literature
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