Peng, Zhongwei

Abstract Background Alzheimer’s disease (AD) is clinicopathologically heterogeneous. A proportion of patients living with AD present clinically at a younger onset of cognitive symptoms before 65 years old and/or non-amnestic clinical syndromes. Neuropathologically, corticolimbic distribution of neurofibrillary tangle pathology occurs on a continuum with some cases having greater cortical tau pathology relative to limbic regions and others with relatively restricted accumulation in limbic structures. These patterns of corticolimbic tangle distribution are associated with clinical presentation and age at onset. This study sought to examine protein expression differences across the spectrum of clinicopathologic heterogeneity using the NULISA targeted proteomics platform. Methods A series of thirteen neuropathologically diagnosed AD cases from Mayo Clinic prospectively followed research studies were selected to reflect heterogeneity of clinical syndromes and corticolimbic distribution of tangle pathology. Frozen postmortem brain tissue samples were isolated from inferior parietal cortex and homogenized in RIPA buffer for analysis using Alamar Biosciences’ NULISA CNS disease 120 panel. Applying a conservative detection threshold of 75% level of detection for the novel application of NULISA in human brain, we evaluated levels of 69 of 129 protein targets across samples. We examined associations between age at onset cognitive symptoms and corticolimbic distribution of tangles (CLix) separately with individual protein targets using linear regression analysis. Results AD cases with a younger age at onset had higher measured levels of ubiquitin, while older age was associated with higher levels of total tau, CRH, and NPTX2. Investigations of corticolimbic heterogeneity revealed AD cases with lower CLix score (i.e., cortical predominant distribution of tau) had higher measured p-tau181, p-tau231, ubiquitin, and p62. AD cases with higher CLix (i.e., relative cortical sparing) had higher levels of total tau, CRH, NPTX2, MDH1, and HBA1. Brain-derived total tau consistently showed a stronger association in both models. Conclusion This work demonstrates the utility of postmortem proteomics for investigating biomarkers associated with AD clinicopathologic heterogeneity. We observed proteomic differences in synapse integrity, tau post-translational modification, and ubiquitination associated with age at symptomatic onset and corticolimbic distribution of tangle pathology.

Abstract INTRODUCTION The locus coeruleus (LC) degenerates early in Alzheimer's disease (AD). However, the extent of rostrocaudal degeneration across clinicopathologic heterogeneity remains underexplored in AD. METHODS Using digital pathology, we quantified LC neuronal density and area at three neuroanatomic levels in a large AD series. RESULTS Analysis of neuropathologic AD subtypes revealed greater middle LC vulnerability in hippocampal sparing AD compared to typical and limbic predominant AD. Regression analyses identified distinct predictor variables associated with the degeneration of rostral and middle LC. Age at onset predicted 24% of the variability in rostral LC neuronal density, whereas Braak stage, brain weight, Lewy body disease, and age at onset accounted for 15% of the variability in middle LC. Analyses of clinical presentations revealed lower rostral LC neuronal density in non‐amnestic compared to amnestic AD cases. DISCUSSION These insights demonstrate greater LC degeneration in atypical clinicopathologic forms of AD, including hippocampal sparing, young‐onset, and non‐amnestic presentations.

Abstract Background Population aging is expected to increase the burden of Alzheimer's disease (AD) and related dementias (ADRD), yet up to 45% of ADRD risk may be modified. Disparities in ADRD burden among Hispanic/Latino and Black/African Americans suggests that socioeconomic deprivation and medical comorbidities may influence AD risk. The relationship between these factors, symptomatic age of onset, and neuropathologic findings in AD remains unclear. This study aims to investigate these associations in an ethnoracially diverse, neuropathologically diagnosed AD case series. Understanding these risk factors may help develop more effective AD risk reduction strategies. Method We queried the Florida Autopsied Multi‐Ethnic (FLAME) cohort database for neuropathologically‐diagnosed AD cases with available age onset of cognitive symptoms, who self‐identified as Hispanic/Latino ( n = 75) or Black/African American ( n = 22). Cases were matched to non‐Hispanic White decedents ( n = 101) by sex and year of birth. Medical records at the time of brain donation were retrospectively reviewed, assessing completeness for demographics, clinical characteristics, and medical comorbidities (Table 1). Result The table shows a comparative analysis stratified by young‐onset AD (YOAD, onset <65 years) and late‐onset AD (LOAD, onset ≥65 years). YOAD cases had a significantly higher level of education compared to LOAD ( p = 0.003). No differences were observed in sex , APOE ε4 carriership, or Area Deprivation Index between YOAD and LOAD. However, YOAD cases had a longer disease duration and were more likely to present with atypical clinical features compared to LOAD (both p <0.001). YOAD cases also showed a faster rate of decline on MMSE compared to LOAD ( p = 0.002), higher frequency of depression ( p = 0.018), and lower frequency of stroke/TIA ( p = 0.025). YOAD cases also had lower brain weight ( p = 0.041), less cerebrovascular disease burden ( p = 0.003) and higher neurofibrillary tangle density in association cortices ( p <0.001) compared to LOAD cases. Conclusion Socioeconomic deprivation and most medical comorbidities were not associated with AD symptomatic onset. Despite having higher education levels and lower cerebrovascular burden, YOAD decedents experienced faster cognitive decline but a longer disease course, with more frequent atypical clinical presentations and depression compared to LOAD. Further discussion will address the topographic distribution of tangle and plaque pathology.

Abstract Neurofibrillary tangles are dynamic neuropathologic hallmarks of Alzheimer’s disease with a hypothesized lifespan morphologically-defined by three maturity levels: pretangles, mature tangles, and ghost tangles. To better understand the progression of tangle pathophysiology, we characterized tangle maturity level predilection of 15 tau antibodies recognizing a broad range of linear, phosphorylation, conformational, and truncation epitopes in the hippocampus of 24 postmortem brains. We developed the tangle maturity scoring system to semi-quantitatively evaluate each tangle maturity level. Based on proportions of tangle maturity levels, we classified antibodies as “early” (mostly pretangles and mature tangles), “middling” (mature tangles with pretangles and ghost tangles), and “advanced” (mostly ghost tangles and mature tangles) tangle maturity markers. To summarize tangle maturity predilection, we developed the tangle maturity scale to integrate individual tangle maturity scores. Correlations showed stronger relationships between tangle maturity scale and subsector thickness for more advanced tangle maturity markers in CA1 and subiculum, whereas Braak tangle stage remained consistently correlated throughout markers of the tangle lifespan. To aid in scoring hippocampi, we used machine learning to recognize tangle maturity levels, which performed comparably to a domain expert and showed similar relationships by Spearman correlation. Pattern recognition software was used to assess tangle and neuritic tau burden separately, which generally correlated with Braak stage and neuronal counts. However, tangle-derived tau burden more consistently correlated with hippocampal subsector thickness. In conclusion, we developed manual and automated scoring systems to evaluate tangle maturity levels, demonstrating early 4R, phosphorylated, and oligomeric tau accumulation preceding more advanced 3R and truncated tau. Our study provides supportive evidence of disease-relevant ordering of tau posttranslational modifications in the brain, which may have implications for theragnostic development. These findings underscore the promise of computerized quantitative analyses (i.e., pathomics) for high-throughput feature extraction from whole-slide images to enhance our understanding of microscopically observed morphologic changes.

Abstract Background The current definition, prognosis, and optimal treatment (tx) for oligometastatic breast cancer (OMBC) are not fully known. With advances in multimodality breast cancer (BC) tx and overall improvement in patient (pt) outcomes, it is important to identify baseline pt factors that confer better prognosis in OMBC and assess the impact of local/regional tx and metastasis (mets)-directed tx on survival outcomes. Methods We reviewed 105 Mayo Clinic pts with OMBC (up to 5 mets) from 2003 to 2021. Pts were excluded from analysis if they were misidentified as having OMBC (n=6), did not have a primary breast mass (n=1), developed de novo BC during tx (n=1), or were lost to follow up (n=2). Categorical variables were summarized as counts. Continuous variables were reported as medians. Kaplan-Meier method was used to estimate survival and the time from diagnosis to next tx at 1, 3, and 5 years. Log-rank test was used to compare survival rates between baseline factors. Univariate Cox proportional hazards models were performed on both baseline and time-dependent factors. All tests were two-sided with p-value &lt; 0.05 considered statistically significant. Results Total pts included were 95. Median age was 49 (range, 26-86), most (93.6%) pts were White, and 46.8% were postmenopausal. Invasive ductal carcinoma (89.5%) was the most common BC type. Median survival was 10.8 years; 1-, 3-, and 5-year survival rates were 98.9%, 87.7%, and 81%, respectively. 58 pts (61.1%) required a change in tx due to disease progression. No significant survival difference was observed in pre- vs. postmenopausal pts (p=0.71) or in groups based on hormone receptor and/or human epidermal growth factor receptor 2 status. 47 pts (49.5%) received local/regional tx; no significant difference in survival (HR 0.57, 95% CI 0.23-1.40; p=0.217) or time to next tx (HR 0.67, 95% CI 0.39-1.15; p=0.144) was seen in this subgroup. Of these pts, 36 (76.6%) received neoadjuvant chemotherapy and/or immunotherapy, 5 of whom (10.6%) also started endocrine tx preoperatively. Overall, 11/47 pts (23.4%) received neoadjuvant endocrine tx. 20 pts received systemic tx without eventual surgery, and 5 pts got palliative radiation (RT). Biopsy-confirmed mets were noted in 76 pts (80%), with bone-only mets in 50%, 30 pts (31.6%) with viscera-only mets and 7 pts (7.4%) with both bone and visceral mets. 18 pts had suspected mets on imaging but did not undergo biopsy. The hazard of death was 6.34 times higher in pts with both bone and visceral mets than those with bone-only mets (p=0.008). Pts with viscera-only mets had higher survival at 2 and 3 years than pts with bone-only or both bone and visceral mets (p=0.093). Pts with 3 mets (7/76, 7.4%) had decreased survival at 1, 2, and 3 years compared to pts with 1-2 (65/76, 85.5%) mets (p=0.6). 67 pts (70.5%) received mets-directed tx; RT alone was the most common modality (52/67, 77.6%), followed by surgery (6/67, 9%), RT plus surgery (5/67, 7.5%), and ablation alone (3/67, 4.5%). There was no significant difference in survival (HR 1.27, 95% CI (0.53, 3.07), p=0.589) or time to next tx (HR 0.95, 95% CI (0.56, 1.63), p=0.856) in pts who received mets-directed tx. Multivariate analysis was not performed because most findings were not statistically significant in univariate analysis. Conclusions We did not find any significant differences in survival based on characteristics like menopausal status or site or number of mets in pts with OMBC. There was a trend toward improved survival in pts with viscera-only mets, but this finding requires validation. Local/regional and mets-directed tx did not improve survival; however, survival at 1, 3, and 5 years was excellent in this OMBC pt population. Our study was limited by low pt numbers and heterogeneity in the pt population. Findings need validation in larger studies. Citation Format: Tanmayi Pai, Raza Zarrar, Zhongwei Peng, Zhuo Li, Lauren Cornell, Kostandinos Sideras, Rohit Rao, Alvaro Moreno-Aspitia, Saranya Chumsri, Sarah McLaughlin, James Jakub, Emmanuel gabriel, Sanjay Bagaria, Laura Vallow, Santo Maimone, Pooja Advani. Clinical Features and Survival Outcomes of Oligometastatic Breast Cancer Patients: The Mayo Clinic Experience [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-06-04.

Importance Factors associated with clinical heterogeneity in Alzheimer disease (AD) lay along a continuum hypothesized to associate with tangle distribution and are relevant for understanding glial activation considerations in therapeutic advancement. Objectives To examine clinicopathologic and neuroimaging characteristics of disease heterogeneity in AD along a quantitative continuum using the corticolimbic index (CLix) to account for individuality of spatially distributed tangles found at autopsy. Design, Setting, and Participants This cross-sectional study was a retrospective medical record review performed on the Florida Autopsied Multiethnic (FLAME) cohort accessioned from 1991 to 2020. Data were analyzed from December 2022 to December 2023. Structural magnetic resonance imaging (MRI) and tau positron emission tomography (PET) were evaluated in an independent neuroimaging group. The FLAME cohort includes 2809 autopsied individuals; included in this study were neuropathologically diagnosed AD cases (FLAME-AD). A digital pathology subgroup of FLAME-AD cases was derived for glial activation analyses. Main Outcomes and Measures Clinicopathologic factors of heterogeneity that inform patient history and neuropathologic evaluation of AD; CLix score (lower, relative cortical predominance/hippocampal sparing vs higher, relative cortical sparing/limbic predominant cases); neuroimaging measures (ie, structural MRI and tau-PET). Results Of the 2809 autopsied individuals in the FLAME cohort, 1361 neuropathologically diagnosed AD cases were evaluated. A digital pathology subgroup included 60 FLAME-AD cases. The independent neuroimaging group included 93 cases. Among the 1361 FLAME-AD cases, 633 were male (47%; median [range] age at death, 81 [54-96] years) and 728 were female (53%; median [range] age at death, 81 [53-102] years). A younger symptomatic onset (Spearman ρ = 0.39, P &amp;lt; .001) and faster decline on the Mini-Mental State Examination (Spearman ρ = 0.27; P &amp;lt; .001) correlated with a lower CLix score in FLAME-AD series. Cases with a nonamnestic syndrome had lower CLix scores (median [IQR], 13 [9-18]) vs not (median [IQR], 21 [15-27]; P &amp;lt; .001). Hippocampal MRI volume (Spearman ρ = −0.45; P &amp;lt; .001) and flortaucipir tau-PET uptake in posterior cingulate and precuneus cortex (Spearman ρ = −0.74; P &amp;lt; .001) inversely correlated with CLix score. Although AD cases with a CLix score less than 10 had higher cortical tangle count, we found lower percentage of CD68-activated microglia/macrophage burden (median [IQR], 0.46% [0.32%-0.75%]) compared with cases with a CLix score of 10 to 30 (median [IQR], 0.75% [0.51%-0.98%]) and on par with a CLix score of 30 or greater (median [IQR], 0.40% [0.32%-0.57%]; P = .02). Conclusions and Relevance Findings show that AD heterogeneity exists along a continuum of corticolimbic tangle distribution. Reduced CD68 burden may signify an underappreciated association between tau accumulation and microglia/macrophages activation that should be considered in personalized therapy for immune dysregulation.

AbstractBackgroundThere is a gap in knowledge concerning which tangle maturity levels (Moloney, Alzheimers Dement, 2021) are associated with antemortem measures (tau‐PET, MRI, cognitive testing). We hypothesized antemortem measures would be more strongly correlated with markers recognizing middling to advanced tangle maturity. We additionally sought to assess the strength of the relationship with tangle and neuritic pathology recognized by tangle maturity markers.MethodPosterior hippocampi from n = 30 cases with antemortem measures ≤3 years prior to death were cut (5µm) and immunostained with tau antibodies to evaluate early (AT8), middling (PHF‐1), or advanced (2E9) tangle maturity. GENIE (pattern recognition software) separated tangle from neuritic burden (Figure). Hippocampus, parahippocampus, and fusiform were analyzed to correlate digital pathology with flortaucipir tau‐PET standard uptake value ratio (SUVr, cerebellar crus normalization), MRI volume/thickness, and cognitive measures which included Auditory Verbal Learning Test (AVLT) delayed recall, Mini‐Mental State Exam (MMSE), and Clinical Dementia Rating (CDR).ResultThe strongest relationships observed with flortaucipir were with PHF‐1 and 2E9 burden (Table). AT8 tangle and neuritic burden correlations with flortaucipir were relatively similar in the hippocampus but were stronger with neuritic pathology in parahippocampus and fusiform. PHF‐1 tangle and neuritic burden correlations were relatively similar with flortaucipir. 2E9 correlations were stronger with neuritic pathology in hippocampus. MRI measures were more strongly correlated with PHF‐1 and 2E9 burden. AT8 tangle and neuritic burden were correlated with fusiform thickness. The correlations between MRI measures and 2E9 tangle and neuritic burden were similar. Correlations between cognitive measures were similar between tangle maturity markers. AVLT delayed recall correlated with all tangle maturity markers, but neuritic burden was stronger for AT8 and 2E9 in hippocampus compared to tangle burden. MMSE correlated with neuritic burden for all tangle maturity markers. CDR remained statistically non‐significant.ConclusionInterpretation of the strength of the relationship between tau burden and antemortem measures differed across tangle maturity markers. Neuroimaging measures may be more sensitive to middle/advanced maturity markers with limited differences between tangle and neuritic pathology. These findings may be biologically relevant and imply either a limited recognition of tangles depending on antibody epitope, and/or may represent the clinicoradiologic impact of increasing neuritic burden.

AbstractBackgroundGlial activation plays a critical role in Alzheimer’s disease (AD) pathogenesis and is associated with amyloid‐β plaques and neurofibrillary tangles composed of phosphorylated tau (phospho‐tau). With approximately 40%‐60% of AD cases having limbic‐predominant age‐related TDP‐43 encephalopathy neuropathologic change (LATE‐NC), TDP‐43 pathology has become more the rule than the exception in AD brains. However, the effect of LATE‐NC in AD‐related glial activation is unknown.MethodWe analyzed the effect of TDP‐43 pathology on glial activation in three AD subtypes: hippocampal sparing (HpSp) AD, typical AD, and limbic predominant AD. Twenty cases of each subtype (n = 60 total) were selected from the FLorida Autopsied Multi‐Ethnic (FLAME) cohort. Cases were immunohistochemically evaluated on serial sections of the hippocampus in the CA1 and subiculum subsectors, and superior temporal, inferior parietal, and mid‐frontal cortices with antibodies to CD68 (phagocytosis), GFAP (astrogliosis), GT‐38 (conformation‐specific AD‐type tau), 6F/3D (amyloid‐β), and phospho‐Serine 409/410 of TDP‐43 (pTDP‐43). Digital pathology was employed to quantify immunohistochemical staining. Multivariable regression modeling was utilized to understand the relationship between glial activation and AD pathologies.ResultThe level of glial activation, defined as % of immunoreactive surface area for CD68 and GFAP, was lowest in HpSp AD (0.54%, 13%), whereas typical AD (1.3%, 33%) and limbic predominant AD (1.3%, 30%) had similar levels suggesting a ceiling effect, or plateau, of gliosis levels (both p<0.001). HpSp AD was more often male (p<0.001) and younger at disease onset (p<0.001) compared to both typical AD and limbic predominant AD. Multivariable regression modeling of CD68 (subiculum R2 = 0.60) identified advanced tau to be a significant predictor of CD68 in all brain regions. LATE‐NC stage predicted increased CD68 levels in limbic brain regions. Multivariable regression modeling of GFAP (CA1 R2 = 0.60) showed that Aβ was the strongest predictor of astrogliosis in CA1 and subiculum (p<0.001). Advanced tau in CA1 and parietal cortex, LATE‐NC in subiculum and temporal cortex, and APOE4 genotype in CA1 predicted a significant increase in GFAP.ConclusionThese findings highlight the significant role TDP‐43 pathology plays in affecting the microenvironment and interplay between neuroinflammation and neurodegeneration and have important implications for therapeutic strategies in AD with co‐morbid LATE‐NC.

AbstractBackgroundThe coarse‐grained plaque is a biochemically and morphologically distinct amyloid‐β (Aβ) deposit that was discovered in clinically‐defined atypical Alzheimer’s disease (AD). Unlike other Aβ deposits, this plaque is not observed in cognitively normal people. This study investigates the hypothesis that the coarse‐grained plaque is distinctly associated with AD neuropathologic change and glial activation within the context of AD subtypes.MethodSixty AD cases from the FLorida Autopsied Multi‐Ethnic (FLAME) cohort were assessed. We included 20 hippocampal sparing (HpSp) AD, 20 typical AD, and 20 limbic predominant AD. Immunohistochemistry was performed on the middle frontal, inferior temporal, and inferior parietal cortex for AD neuropathology (Aβ [6F/3D], phospho‐tau [AT8], tau [GT38]) and glial activation (CD68 [KP1] and GFAP). Digital pathology was used to quantify burden. Thioflavin‐S tangle counts were performed at time of neuropathologic diagnosis. Distinct deposit types, including classic cored plaques, coarse‐grained plaques, cerebral amyloid angiopathy (CAA)‐Type 1, and CAA‐Type 2, were semi‐quantitatively scored on Aβ (Fig. 1). Correlations between demographic, clinical, and neuropathologic characteristics were assessed using Spearman rho analysis and reported if p<0.05. An independent cohort of ∼100 HpSp AD cases will be assessed to validate initial findings.ResultIn the frontal cortex of HpSp AD, higher scores of classic cored plaques correlated with older age at onset and death, non‐APOE ε4 carriership, and less CAA‐Type 1 and Type 2 (Fig. 2). On the contrary, the severity of coarse‐grained plaques correlated with a younger age at onset and death, APOE ε4 carriership, higher scores for CAA‐Type 1, CAA‐Type 2, and increased burden of Aβ, GFAP, and CD68. Classic cored plaques correlated negatively with phospho‐tau and tau, whereas coarse‐grained plaques correlated positively with phospho‐tau, tau, and tangles. The two deposit types were negatively correlated with each other. Correlations were weaker but showed similar trends in other AD subtypes (Fig. 2) and regions.ConclusionWithin HpSp AD, classic cored and coarse‐grained plaques show distinct correlations with glial activation, (phospho‐)tau, and tangles. These results suggest opposite directions of association for these deposits on AD neuropathologic change that may impact clinical symptoms. These findings are relevant to therapies targeting overall Aβ pathology.