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Loss with ageing but preservation of frontal cortical capillary pericytes in post-stroke dementia, vascular dementia and Alzheimer’s disease
research-article
Author(s):
Ren Ding ,
Yoshiki Hase ,
Matthew Burke ,
Vincent Foster ,
William Stevenson ,
Tuomo Polvikoski ,
Raj N. Kalaria
Publication date (Electronic):
2 August 2021
Journal:
Acta Neuropathologica Communications
Publisher:
BioMed Central
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Abstract
Cerebral pericytes are an integral component of the neurovascular unit, which governs the blood–brain barrier. There is paucity of knowledge on cortical pericytes across different dementias. We quantified cortical pericytes in capillaries in 124 post-mortem brains from subjects with post-stroke dementia (PSD), vascular dementia (VaD), Alzheimer’s disease (AD) and AD-VaD (Mixed) and, post-stroke non-demented (PSND) stroke survivors as well as normal ageing controls. Collagen 4 (COL4)-positive nucleated pericyte soma were identified as protrusions on capillaries of the frontal cortex. The COL4-positive somata or nodule-like cell bodies were also verified by platelet derived growth factor receptor-β (PDGFR-β) immunohistochemistry. The mean (± SEM) pericyte somata in frontal cortical capillaries in normal young controls (46–65 years of age) was estimated as 5.2 ± 0.2 per mm capillary length. This number was reduced by 45% in older controls (> 78 years) to 2.9 ± 0.1 per mm capillary length ( P < 0.001). We further found that the numbers of pericyte cell bodies per COL4 mm 2 area or per mm capillary length were not decreased but rather preserved or increased in PSD, AD and Mixed dementia groups compared to similar age older controls ( P < 0.01). Consistent with this, we noted that capillary length densities identified by the endothelial marker glucose transporter 1 or COL4 were not different across the dementias compared to older controls. There was a negative correlation with age ( P < 0.001) suggesting fewer pericyte somata in older age, although the % COL4 immunoreactive capillary area was increased in older controls compared to young controls. Using a proven reliable method to quantify COL4-positive nucleated pericytes, our observations demonstrate ageing related loss but mostly preserved pericytes in the frontal cortex of vascular and AD dementias. We suggest there is differential regulation of capillary pericytes in the frontal lobe between the cortex and white matter in ageing-related dementias.
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Most cited references51
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Blood-brain barrier breakdown is an early biomarker of human cognitive dysfunction
Daniel Nation, Melanie D Sweeney, Axel Montagne … (2019)
Introduction Vascular contributions to cognitive impairment are increasingly recognized 1–5 as shown by neuropathological 6,7 , neuroimaging 4,8–11 , and cerebrospinal fluid (CSF) biomarker 4,12 studies. Moreover, small vessel disease of the brain has been estimated to contribute to approximately 50% of all dementias worldwide, including those caused by Alzheimer’s disease (AD) 3,4,13 . Vascular changes in AD have been typically attributed to vasoactive and/or vasculotoxic effects of amyloid-β (Aβ) 3,11,14 , and more recently tau 15 . Animal studies suggest that Aβ and tau lead to blood vessel abnormalities and blood-brain barrier (BBB) breakdown 14–16 . Although neurovascular dysfunction 3,11 and BBB breakdown develop early in AD 1,4,5,8–10,12,13 , how they relate to changes in AD classical biomarkers Aβ and tau, which also develop prior to dementia 17 , remains unknown. To address this question, here we studied brain capillary damage using a novel CSF biomarker of BBB-associated capillary mural cell pericyte, a soluble platelet-derived growth factor receptor-β (sPDGFRβ) 8,18 , and regional BBB permeability using dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) 8–10 . Our data show that individuals with early cognitive dysfunction develop brain capillary damage and BBB breakdown in the hippocampus irrespective of Alzheimer’s Aβ and/or tau biomarker changes, suggesting that BBB breakdown is an early biomarker of human cognitive dysfunction independent of Aβ and tau. We studied individuals who were cognitively normal as well as those with early cognitive dysfunction who were stratified upon CSF analysis as either Aβ-positive (Aβ1–42+, 190 pg/mL), or pTau-positive (pTau+, >78 pg/mL) or pTau-negative (pTau-, 0.5 > 0) (Figure 1a), suggesting progressive damage of pericytes 8,18 with cognitive dysfunction. There were no significant differences in CSF Aβ1–42 or pTau levels between CDR 0.5 and CDR 0 individuals, although we saw reduced CSF Aβ1–42 in CDR 1 relative to CDR 0.5 participants (Figure 1b-c; for site-specific analysis see Extended Data Figure 2a-b). sPDGFRβ was increased in participants with CDR 0.5 relative to CDR 0 regardless of CSF Aβ1–42 (Figure 1d) or pTau (Figure 1e) status, i.e., irrespective of Aβ+ or Aβ-, or pTau+ or pTau-, as confirmed by site-specific analyses (Extended Data Figure 2c-d). Higher CSF sPDGFRβ remained a significant predictor of cognitive impairment after statistically controlling for CSF Aβ1–42 and pTau, as shown by estimated marginal means from ANCOVA models (Figure 1f) indicating medium-to-large incremental effect sizes with η2 partial range = .10–.12, which has been confirmed by logistic regression models (Supplementary Table 3a-c). There was a significant positive correlation between CSF sPDGFRβ with classical biomarkers of BBB breakdown including CSF/plasma albumin ratio and CSF fibrinogen (Extended Data Fig. 2e-f). Among the subset of 35 participants who underwent Pittsburgh compound B (PiB)-positron emission tomography (PET), those with CDR 0.5 exhibited increased CSF sPDGFRβ relative to those with CDR 0, after statistically controlling for amyloid levels (Extended Data Figure 2g), consistent with CSF Aβ findings (Figure 1d). Additionally, we found no differences in CSF Aβ and tau oligomers levels between CDR 0 and CDR 0.5 groups (Extended Data Figure 2h-i). CSF sPDGFRβ remained significantly elevated in CDR analysis after statistically controlling for CSF tau oligomers in ANCOVA models (Extended Data Figure 2j), suggesting that sPDGFRβ increase is not dependent on oligomer levels. Increased CSF sPDGFRβ in impaired individuals was independent of vascular factors, as indicated by VRF burden analysis for the entire sample and confirmed by site-specific analysis (Extended Data Figure 3a-c). Of note, there were no differences in CSF biomarkers of glial and inflammatory response, or neuronal degeneration 28,29 between impaired and unimpaired individuals on CDR exams, as illustrated with a few representative biomarkers out of 20 studied (see online Methods) (Extended Data Figure 4a); also confirmed by site-specific analysis (Extended Data Figure 4b-c). Collectively, our findings indicate that damage to brain capillary pericytes, which critically maintain the BBB integrity 22,30,31 , develops early in older adults with cognitive dysfunction, which is independent of Aβ and tau biomarker changes, is not influenced by VRFs, and is not associated with glial and/or inflammatory response, or detectable neuronal degeneration. The DCE-MRI analysis of regional BBB permeability in a subset of 73 participants with CDR 0.5 compared to those with CDR 0, indicated increased BBB permeability to gadolinium-based contrast agent in the hippocampus (HC) and its CA1, CA3 and dentate gyrus subfields, and parahippocampal gyrus (PHC), but not in other studied brain regions including frontal and temporal cortex, subcortical white matter, corpus callosum, and internal capsule, and deep gray matter regions including thalamus, and striatum (Extended Data Figure 5a-b). These findings are consistent with a recent report demonstrating that BBB breakdown during normal aging and MCI starts in the HC 8 . Surprisingly, we also found that individuals with CDR 0.5 compared to those who were cognitively normal (CDR 0) exhibited BBB breakdown in the HC, PHC and HC subfields regardless of CSF Aβ1–42 (Figure 1g-h), and pTau (Figure 1i-j) status. Increased regional BBB permeability in HC, PHC and HC subfields remained a significant predictor of cognitive impairment after statistically controlling for CSF Aβ1–42 and pTau, as shown by estimated marginal means from ANCOVA models (Figure 1k) indicating medium-to-large incremental effect sizes (η2 partial range = .09–.28), also confirmed by logistic regression models (Supplementary Table 3d-h). The regional BBB analysis indicated that Aβ and tau status does not affect BBB integrity in other studied brain regions (Extended Data Figure 5c-d). Similar to sPDGFRβ findings, the VRF burden did not influence BBB permeability changes in the HC and PHC in individuals with CDR 0.5 compared to CDR 0, and also had no effect on BBB integrity in other studied brain regions (Extended Data Figure 5e-f). Consistent with previous findings 8 , in the present cohort we also observed a significant positive correlation between increases in CSF sPDGFRβ and DCE-MRI measures of BBB permeability in the HC and PHC in all studied participants (Extended Data Figure 5g-h), which was not the case for other studied brain regions, as illustrated here for the white matter regions (Extended Data Figure 5i-j). As the present study sample excluded participants with vascular dementia and vascular cognitive impairment and substantial cerebrovascular pathology, it is probably not surprising that BBB dysfunction in the present analysis was independent of traditional systemic VRFs. The possibility of interactive or synergistic effects of traditional VRFs and BBB dysfunction in populations with more severe vascular lesions, vascular dementia and vascular cognitive impairment is not ruled out, however, by the present findings. Nevertheless, the fact that brain capillary mural cell damage and BBB breakdown is independent of traditional VRFs, as we show, is critical information that underscores the heterogeneity of vascular pathologies in the aging brain. In order to address whether changes in CSF sPDGFRβ and DCE-MRI BBB permeability measures depend on HC volume, we conducted ANCOVA analyses and hierarchical logistic regression correcting for FreeSurfer-derived HC and/or PHC volumes (Figure 2a). In participants with CDR 0.5 vs. CDR 0, we found no significant changes in HC volume, but a significant decrease in PHC volume (Figure 2b). HC or PHC volumes did not statistically differ between participants that were CSF Aβ+ vs. Aβ- (Figure 2c) or pTau+ vs. pTau- (Figure 2d) in either CDR 0 or CDR 0.5 groups. Importantly, CSF sPDGFRβ increases remained significant after controlling for HC and PHC volumes (estimated as marginal means from ANCOVA models) (Figure 2e), and remained increased when stratifying by CSF Aβ1–42 and pTau status (Figure 2f-g). Similarly, HC and PHC BBB permeability increases remained significant after controlling for HC and PHC volumes, respectively (Figure 2h), and when stratifying by Aβ1–42 and pTau status (Figure 2i-j). All findings exhibited medium-to-large incremental effect sizes after controlling for HC and PHC volume (η2 partial range = .09–.31) and were corroborated by logistic regression models (Supplementary Table 4a-c). Collectively, these data suggest that BBB-impairment that is represented by CSF sPDGFRβ and DCE-MRI measures is not only independent of CSF AD biomarkers, but is also not correlated to HC volume. To determine whether our findings hold when cognitive dysfunction was evaluated by neuropsychological performance, we analyzed CSF biomarkers and BBB integrity using normalized scores from 10 neuropsychological tests used to evaluate impairment in memory, attention/executive function and language, and global cognition, as described in online Methods. This analysis indicated elevated CSF sPDGFRβ in participants with one cognitive domain impaired relative to those with no domains impaired (Figure 3a; see Extended Data Figure 6a-b for site-specific analyses). There was no difference, however, in CSF Aβ1–42 between participants with one domain impaired and those with no domains impaired (Figure 3b). Participants with one domain impaired showed, however, increased CSF pTau relative to those with no domains impaired (Figure 3c). Stratification of participants into those with and without classic AD biomarker abnormalities revealed increased CSF sPDGFRβ in participants with one or more domain impaired regardless of CSF Aβ1–42 (Figure 3d) or pTau (Figure 3e) status (see Extended Data Figure 6c-d for site-specific analyses), or VRFs burden, as shown in the entire sample and confirmed by site-specific analysis (Extended Data Figure 6e-g). Higher CSF sPDGFRβ levels remained a significant predictor of cognitive impairment after statistically controlling for CSF Aβ1–42 and pTau, as shown by estimated marginal means from ANCOVA models (Figure 3f) indicating medium-to-large incremental effect sizes (η2 partial range = .07–.14), which has been confirmed by logistic regression models at both sites (Supplementary Table 5a-c). Similar as for CDR analysis, in the subset of participants who underwent PiB-PET scans, participants with domain impairment exhibited increased CSF sPDGFRβ relative to those without impairment, after statistically controlling for amyloid levels (Extended Data Figure 7a) corroborating CSF Aβ data (Figure 3d). There was no difference in CSF Aβ and tau oligomers between participants with impairment in 1 or more cognitive domains and those without cognitive impairment (Extended Data Figure 7b-c). CSF sPDGFRβ remained significantly increased in domain analysis after statistically controlling for CSF tau oligomers in ANCOVA models (Extended Data Figure 7d). There were no differences in CSF markers of glial and/or inflammatory response, or neuronal degeneration 28,29 between impaired and unimpaired participants on neuropsychological exams, as illustrated with a few examples (Extended Data Figure 8a; also confirmed by site-specific analysis in Extended Data Figure 8b-c). Among participants undergoing DCE-MRI scans, those with domain impairment relative to those without impairment exhibited BBB breakdown in the HC, PHC and HC subfields, but not in other studied brain regions (Extended Data Figure 9a-b) regardless of CSF Aβ1–42 (Figure 3g-h; Extended Data Figure 9c) or pTau (Figure 3i-j; Extended Data Figure 9d) status, or VRF status (Extended Data Figure 9e-f). Increased regional BBB permeability in HC, PHC and HC subfields remained a significant predictor of cognitive impairment after statistically controlling for CSF Aβ1–42 and pTau, as shown by estimated marginal means from ANCOVA models (Figure 1k) indicating medium-to-large incremental effect sizes (η2 partial range = .07–.18), also confirmed by logistic regression analysis (Supplementary Table 5d-h). An increase in DCE-MRI BBB permeability in several medial temporal lobe structures that sub serve episodic memory (e.g., HC, PHC, and CA1, CA3 and dentate gyrus HC subfields) was associated with worse CDR scores (CDR 0 vs. 0.5) and with impairment in multiple cognitive domains (impairment in 0 vs. one or more domains) (Figure 1g-k; Figure 3g-k). Although this provides a perfect anatomical substrate for episodic memory impairment, it is less clear whether BBB pathology in HC and medial temporal lobe can contribute to changes seen in other domains in participants with CDR 0.5 or with impairment in multiple domains, which involves areas of the brain outside the medial temporal lobe that we found were not affected by BBB breakdown in the present cohort (Extended Data Figure 5a-b and 9a-b). Numerous studies, however, have linked HC structure and function to each of the cognitive domains and subdomains investigated in the present study. For example, experimental studies in animals and observational human studies have found that attention, working memory and executive function can become dysfunctional as a result of HC-prefrontal pathway disruption 32–35 . HC functional activation has been found to underpin normal performance on semantic fluency tasks 36 , and neuroimaging-based markers of HC structure and function correlate with performance on semantic fluency and confrontation naming tasks in both normal and pathological human aging 37 . Thus, BBB breakdown within the HC and medial temporal regions may disrupt the ability of these structures and their connecting pathways to support an array of cognitive functions. Additionally, we noted increased BBB permeability in the caudate nucleus (Extended Data Figure 5a-b and 9a-b), a structure known to support frontal-subcortical processes involved in attention/executive functions and verbal fluency 38,39 . Although less salient than the HC and PHC findings, it is possible that BBB breakdown within the caudate may contribute to the observed deficits in domains beyond memory. As with CDR analysis, there were no significant changes in HC volume, but a significant decrease in PHC volume, in participants with 1+ cognitive domains impaired compared to 0 domains impaired, which did not statistically differ between participants that were CSF Aβ+ vs. Aβ- or pTau+ vs. pTau- (Figure 4a-c). CSF sPDGFRβ increases remained significant after controlling for HC and PHC volumes (Figure 4d), and also remained increased when stratifying by CSF Aβ1–42 and pTau status (Figure 4e-f). HC and PHC BBB permeability increases remained significant after controlling for HC and PHC volumes (Figure 4g), respectively, and when stratifying by Aβ1–42 and pTau status (Figure 4h-i). These findings exhibited medium-to-large incremental effect sizes after controlling for HC and PHC volume (η2 partial range = .19–.25) and were corroborated by logistic regression models (Supplementary Table 6a-c). Finally, we asked did CSF sPDGFRβ and DCE-MRI BBB increases correlate with age? Neither CSF sPDGFRβ (Extended Data Figure 10a-b) nor regional BBB permeability HC and PHC values (Extended Data Figure 10c-f) were correlated with age in either the CDR 0 or CDR 0.5 groups. Since all CDR and domain impairment group differences in CSF sPDGFRβ and in HC and PHC BBB permeability values were significant after age-corrections (Figure 1; Figure 3), these data indicate that CSF sPDGFRβ and HC and PHC BBB measures reflect cognitive impairment independent of normal aging, and therefore may be good biomarkers of early cognitive dysfunction. In summary, we show that older adults with early cognitive dysfunction develop brain capillary damage associated with mural cell pericyte injury and BBB breakdown in the HC irrespective of Aβ and/or tau changes, suggesting that BBB breakdown is an independent, early biomarker of cognitive impairment unrelated to Aβ and tau. The independence of the BBB breakdown pathway from Aβ/tau pathway in predicting cognitive impairment is further supported by logistic regression models indicating that BBB breakdown is not mediating the relationship between AD biomarkers and cognitive impairment (Supplementary Tables 7–10). Biomarker-based diagnostic approaches, including the recent research recommendations for AD 17 , mention vascular biomarkers, but suggest that CSF Aβ1–42 and pTau and amyloid PET and tau PET are the key biomarkers defining AD pathology, although they may not be causal to the disease process 5,17,40 . Our present findings support that neurovascular dysfunction may represent a previously underappreciated factor contributing to cognitive and functional decline, independent of the classic pathophysiological hallmarks of AD. Moreover, our findings point to the brain vasculature as an important new biomarker of cognitive dysfunction in both individuals without and with Aβ or pTau positivity, the latter indicating individuals in the Alzheimer’s continuum 17 . Online Methods Study Participants Participants were recruited from two sites, including the University of Southern California (USC), Los Angeles, CA, and Washington University, St. Louis, MO. At the USC site, participants were recruited through the USC Alzheimer’s Disease Research Center (ADRC): combined USC and the Huntington Medical Research Institutes (HMRI), Pasadena, CA. At the Washington University site, participants were recruited through the Washington University Knight ADRC. The study and procedures were approved by the Institutional Review Board of USC ADRC and Washington University Knight ADRC indicating compliance with all ethical regulations, and informed consent was obtained from all participants prior to study enrollment. Participants from both sites were included in cerebrospinal fluid (CSF) biomarker studies. All participants underwent neurological and neuropsychological evaluations performed using the Uniform Data Set (UDS), and additional neuropsychological tests, as described below. Participants from the USC ADRC were included in dynamic contrast-enhanced (DCE)-MRI studies for assessment of blood-brain barrier (BBB) permeability if they had no contraindications for contrast injection or MRI. We included 161 participants for CSF biomarker studies (74 from USC/HMRI and 87 from Washington University). A group of 35 participants from the Washington University Knight ADRC underwent Pittsburgh compound B (PiB)-positron emission tomography (PET) imaging for amyloid. A group of 73 participants recruited from the USC ADRC underwent DCE-MRI. All biomarker assays and quantitative MRI scans were conducted by investigators blinded to the clinical status of the participant. Inclusion/Exclusion Criteria Included participants (≥45 years of age) with neuropsychologically-confirmed no cognitive dysfunction and/or early cognitive dysfunction had no current or prior history of any neurological or psychiatric conditions that might better account for any observed cognitive impairment, including organ failure, brain tumors, epilepsy, hydrocephalus, schizophrenia, major depression. Participants were stratified based on CSF analysis as either Aβ1–42-positive (Aβ1–42+, 190 pg/mL), or pTau181-positive (pTau+, >78 pg/mL) or pTau181-negative (pTau-, 1 standard deviation (SD) below norm-referenced values on two or more tests within a domain 41 . Multiple domain impairment (2+) was assigned when more than one domain fit the impairment criteria, or three or more tests were impaired across domains 21,41 . Prior studies have established improved sensitivity and specificity of these criteria relative to those employing a single test score, as well as adaptability of this diagnostic approach to various neuropsychological batteries 21,41,42 . Cognition was presumed normal unless multiple impaired tests were identified as specified by the criteria. Individuals with low Mini Mental State Exam (MMSE) or Montreal Cognitive Assessment (MOCA) scores ( 100 μm diameter) as described and characterized as reported 18 . SMCs were >98% positive for α-smooth muscle actin (SMA), myosin heavy chain, calponin and SM22 and negative for von Willebrand factor (endothelial cells), GFAP (astrocytes) and CD11b (microglia). Cells were cultured in smooth muscle cell medium (Cat. No. 1101, ScienCell) in 5% CO2 at 37°C. Early passage (P5-P6) cultures were used in the present study. Primary human brain microvascular pericytes were isolated from cortical brain tissue after removal of leptomeninges as previously described 18,48 . Pericytes were derived from intraparenchymal microvessels that were completely free from leptomeningeal vessel contamination. Purified microvessels were largely brain capillaries (>97%) with diameter 90% of participants had complete data). Given the large number of analyses, false discovery rate (FDR)-correction was applied to all ANCOVA omnibus p-values using the Benjamini-Hochberg method 60 . Where significant CSF sPDGFRβ and BBB Ktrans findings were identified (CDR 0.5 vs. 0 and domain impairment 1+ vs. 0), separate post-hoc analyses of CSF sPDGFRβ and BBB Ktrans differences controlling for CSF Aβ1–42 and pTau, PiB-PET amyloid deposition, pTau oligomers, and HC and PHC volumes also utilized ANCOVA models. In addition, separate hierarchical logistic regression analyses evaluated whether CSF sPDGFRβ and BBB Ktrans predicted cognitive impairment (CDR 0.5 vs. 0 and domain impairment 1+ vs. 0) after controlling for CSF Aβ1–42 and pTau, PiB-PET amyloid deposition, pTau oligomers, and HC and PHC volumes. For both ANCOVA and logistic regression analyses, covariates were entered into the model in the first block and in the second block either CSF sPDGFRβ or specific regional BBB Ktrans values were entered. Additional demographics and APOE4 carrier status were included in overall models correcting for CSF Aβ1–42 and pTau, and models correcting for HC and PHC volumes. Extended Data Extended Data Figure 1. ADAM10 mediates soluble PDGFRβ (sPDGFRβ) shedding in human brain pericytes in vitro. (a) Primary human brain vascular smooth muscle cells (SMCs) and pericytes were subjected to treatment with ionomycin (IM) (2.5 μM), a calcium ionophore that activates ADAM10, or control treatment (media only), and media was immunoprecipitated (IP) to measure sPDGFRβ by quantitative Western immunoblot. Compared to pericytes, SMCs shed extremely low levels of sPDGFRβ, which was not significantly increased by IM. Pericytes shed high basal levels of sPDGFRβ that was significantly increased by > 5-fold by treatment with IM, which activated ADAM10. To further determine ADAM10’s involvement, IM treatment was conducted in the presence of ADAM10 pharmacological inhibition with marimastat (MM, 4 μM) that inhibits ADAM10 by binding to active site zinc, and genetic siRNA knockdown of ADAM10. Both pharmacologic (MM) and genetic (siRNA) inhibition of ADAM10 significantly reduced sPDGFRβ shedding activated by IM by > 90% and 75%, respectively. (b) The siRNA ADAM10 knockdown efficiency in this study was 85% as shown by Western analysis. Data generated from n=3–6 independent culture experiments and plotted as means ± SEM. Statistical analyses: Panel a: SMC data by two-tailed Student’s t-test; pericyte data by ANOVA with Tukey post-hoc test. Panel b: Two-tailed Student’s t-test. Significance at α=0.05 for all analyses. Extended Data Figure 2. CSF sPDGFRβ increases with CDR impairment, independent of Aβ and tau, and reflects blood-brain barrier (BBB) breakdown. (a-b) Site-specific analysis of CSF sPDGFRβ and standard AD biomarkers, Aβ42 and pTau, indicates an early increase in sPDGFRβ with increasing CDR in both independent clinical sites, USC (a) and Washington University (b). There were no changes in Aβ42 and pTau at USC site (a), whereas Aβ42, but not pTau, was altered at Washington University site; supports Figure 1 a-c. (c-d) Site-specific analysis of CSF sPDGFRβ increases with CDR, independent of CSF Aβ42 and pTau status in two independent sites, USC (c) and Washington University (d); supports Figure 1 d-f. (e-f) CSF sPDGFRβ is associated with blood-brain barrier (BBB) breakdown. CSF sPDGFRβ positively correlates with conventional biochemical biomarkers of BBB breakdown including CSF:plasma albumin ratio (Qalb) (e) and CSF fibrinogen (f); supports Figures 1 and 3. (g) CSF sPDGFRβ is increased with CDR, independent of amyloid positivity by (11)C-Pittsburgh compound B positron emission tomography (PiB-PET); supports Figure 1 d and f. (h-i) No differences were observed in CSF Aβ oligomer levels (h) and tau oligomer levels (i) in individuals with CDR 0 vs. CDR 0.5; supports Figure 1 d-f. (j-k) Increases in CSF sPDGFRβ (j) and regional BBB K trans in the hippocampus (HC) and parahippocampal gyrus (PHC) (k) of individuals with CDR 0.5 vs. CDR 0 remain significant after statistically controlling for the impact of CSF tau oligomers; supports Figure 1 d-f. Panels a-d, g-i: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Panels a-d, g: significance tests from ANCOVAs. Panels e-f: Statistical significance determined by Pearson correlation; r = Pearson correlation coefficient. Panels h-i: Significance by two-tailed Student’s t-test at α=0.05. Panels j-k: ANCOVA models representing estimated marginal means ± SEM. Brackets denote sample size (n) in each analysis. Extended Data Figure 3. sPDGFRβ increases with CDR independent of vascular risk factors (VRFs), and no change in other neurovascular unit biomarkers. (a-c) CSF sPDGFRβ is increased with CDR, independent of VRFs burden in the combined site analysis (a) and in two independent clinical sites from USC (b) and Washington University (c). VRFs 0–1: no or 1 vascular risk factor. VRFs 2+: 2 or more vascular risk factors. See Supplementary Table 1 for the list of VRFs; supports Figure 1 a-f. Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests from ANCOVAs. Brackets denote sample size (n) in each analysis. Extended Data Figure 4. Other CSF biomarkers of the neurovascular unit are not altered with CDR cognitive impairment. (a-c) CSF markers of glial, inflammatory, or neuronal injury exhibited no significant differences between unimpaired and impaired individuals on CDR, including S100 calcium-binding protein B (S100B), interleukin-6 (IL-6), tumor necrosis factor-α (TNFα), or neuron-specific enolase (NSE) in the combined site analysis (a) and similarly in site-specific analysis of individuals from USC (b) and from Washington University (c); supports Figure 1 a-c. Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests from ANCOVAs. Brackets denote sample size (n) in each analysis. Extended Data Figure 5. Regional blood-brain barrier (BBB) breakdown Ktrans increases with CDR independent of CSF Aβ and tau and vascular risk factors (VRFs), and relates to sPDGFRβ only in hippocampal gray matter regions. (a-b) An increase in Ktrans values in the hippocampus (HC), parahippocampal gyrus (PHC) and CA1, CA3 and dentate gyrus (DG) hippocampus subfields, with increasing CDR (a), but not in other brain regions including superior frontal cortical gyrus (Sup Front) and inferior temporal cortical gyrus (Inf Temp), white matter regions including subcortical white matter fibers (white matter, WM), corpus callosum (CC), and internal capsule (IC), and deep gray matter regions including thalamus (Thal), caudate nucleus (Caud) and striatum (b). (c-d) Additional brain regions showed no significant differences in Ktrans BBB permeability values in individuals with CDR 0 and CDR 0.5, regardless of CSF Aβ42 (c) or pTau (d) status. (e-f) VRFs burden does not influence an increase in the Ktrans BBB permeability values with increasing CDR in the HC, PHC, and hippocampus subfields (i.e., CA1, CA3, DG) (e), and no change in the Ktrans BBB permeability values in other brain regions (f). See Supplementary Table 1 for the list of VRFs. Panels a-f support Figure 1 g-k. (g-j) CSF sPDGFRβ is associated with BBB breakdown measured by neuroimaging in hippocampal gray matter regions (g-h), but not in WM regions (i-j); supports Figures 1 and 3. Panels a-f: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests after FDR correction from ANCOVAs. Panels g-j: Statistical significance determined by Pearson correlation; r = Pearson correlation coefficient. Brackets denote sample size (n) in each analysis; applies to all regions within each panel. Extended Data Figure 6. CSF sPDGFRβ increases with CDR impairment, independent of Aβ, tau, and vascular risk factors (VRFs). (a-b) Site-specific analysis of CSF sPDGFRβ and standard AD biomarkers, Aβ42 and pTau, indicates an early increase in sPDGFRβ with increasing domains impaired in both independent clinical sites, USC (a) and Washington University (b); supports Figure 3 a-c. (c-d) Site-specific analysis of CSF sPDGFRβ indicates increases with the number of cognitive domains impaired, independent of CSF Aβ42 and pTau status in two independent sites, USC (c) and Washington University (d); supports Figure 3 d-f. (e-g) CSF sPDGFRβ is increased with increasing number of cognitive domains impaired, independent of VRFs burden in the combined site analysis (e) and in two independent clinical sites, USC (f) and Washington University (g). VRFs 0–1: no or 1 vascular risk factor. VRFs 2+: 2 or more vascular risk factors. See Supplementary Table 2 for the list of VRFs. Supports Figure 3 a-f. Panels a-g: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests from ANCOVAs. Brackets denote sample size (n) in each analysis. Extended Data Figure 7. BBB breakdown is independent of amyloid and tau oligomers. (a) CSF sPDGFRβ is increased with cognitive domains impaired, independent of amyloid positivity by (11)C-Pittsburgh compound B positron emission tomography (PiB-PET); supports Figure 3 d and f. (b-c) No differences were observed in CSF Aβ oligomer levels (b) and tau oligomer levels (c) in individuals with 0 or 1+ cognitive domains impaired. (d-e) Increases in CSF sPDGFRβ (d) and regional blood-brain barrier (BBB) K trans in the hippocampus (HC) and parahippocampal gyrus (PHC) (e) of individuals with 1+ versus 0 cognitive domain impairment remain significant after statistically controlling for the impact of CSF tau oligomers; supports Figure 3 d-f. Panels a-c: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Panel a: significance tests from ANCOVAs. Panels b-c: Significance by two-tailed Student’s t-test at α=0.05. Panels d-e: ANCOVA models representing estimated marginal means ± SEM. Brackets denote sample size (n) in each analysis. Extended Data Figure 8. Other CSF biomarkers of the neurovascular unit are not altered with cognitive domain impairment. (a-c) CSF markers of glial, inflammatory, or neuronal injury exhibited no significant differences between unimpaired and impaired individuals on neuropsychological exams, including S100 calcium-binding protein B (S100B), interleukin-6* (IL-6), tumor necrosis factor-α† (TNFα), or neuron-specific enolase† (NSE) in the combined site analysis (a) or in the site-specific analysis of individuals from USC (b) or from Washington University (c). Panels a-c: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests after FDR correction from ANCOVAs with post-hoc Bonferroni comparisons. Brackets denote sample size (n) in each analysis. *Analysis did not survive significance after FDR correction. †Individual group comparison p values reported because omnibus test was p < 0.05 but post-hoc group comparisons were null. Supports Figure 3 a-c. Extended Data Figure 9. Regional blood-brain barrier (BBB) breakdown Ktrans increases with cognitive domain impairment, independent of CSF Aβ and tau and vascular risk factors (VRFs). (a-b) An increase in K trans values in the hippocampus (HC), parahippocampal gyrus (PHC), and CA1, CA3 and dentate gyrus (DG) hippocampal subfields with increasing cognitive impairment measured by the number of cognitive domains impaired (a), but not in other brain regions including superior frontal cortical gyrus (Sup Front) and inferior temporal cortical gyrus (Inf Temp), white matter regions including subcortical white matter fibers (white matter), corpus callosum (CC), and internal capsule (IC), and deep gray matter regions including thalamus (Thal), caudate nucleus (Caud) and striatum (b). (c-d) Additional brain regions showed no significance difference in K trans BBB permeability in individuals with 0 and 1+ cognitive domains impaired, regardless of CSF Aβ42 (c) and pTau (d) status. (e-f) K trans BBB permeability is increased with increasing cognitive domain impairment in the HC, PHC, and hippocampal subfields (i.e., CA1, CA3, DG), independent of VRFs burden (e), but not in other brain regions (f). VRFs 0–1: no or 1 vascular risk factor; VRFs 2+: 2 or more vascular risk factors. See Supplementary Table 2 for the list of VRFs. Panels a-f: Box-and-whisker plot lines indicate median values, boxes indicate interquartile range and whiskers indicate minimum and maximum values. Significance tests after FDR correction from ANCOVAs. Brackets denote sample size (n) in each analysis; applies to all regions within each panel. Supports Figure 3 g-k. Extended Data Figure 10. CSF sPDGFRβ and medial temporal BBB permeability Ktrans values are not correlated with age, indicating that changes in CSF sPDGFRβ and Ktrans capture processes relating to cognitive impairment independent of normal aging. In CDR 0 individuals, age does not correlate with CSF sPDGFRβ. (a) or regional Ktrans in the hippocampus (HC) (c) and parahippocampal gyrus (PHC) (e). Similarly, in CDR 0.5 individuals, age does not correlate with CSF sPDGFRβ (a) or regional Ktrans in the hippocampus (HC) (c) and parahippocampal gyrus (PHC) (e). Statistical significance determined by Pearson correlation; r = Pearson correlation coefficient. Brackets denote sample size (n) in each analysis. Supports Figures 1 and 3. Supplementary Material 1 Statistics Tables
Author and article information
Contributors
Yoshiki Hase:
ORCID: https://orcid.org/0000-0002-9538-905X
yoshiki.hase@ncl.ac.uk
Raj N. Kalaria:
ORCID: http://orcid.org/0000-0001-7907-4923
raj.kalaria@ncl.ac.uk
Journal
Journal ID (nlm-ta): Acta Neuropathol Commun
Journal ID (iso-abbrev): Acta Neuropathol Commun
Title:
Acta Neuropathologica Communications
Publisher:
BioMed Central
(London
)
ISSN
(Electronic):
2051-5960
Publication date
(Electronic):
2
August
2021
Publication date PMC-release: 2
August
2021
Publication date Collection: 2021
Volume: 9
Electronic Location Identifier: 130
Affiliations
Author information
Yoshiki Hase
https://orcid.org/0000-0002-9538-905X
Raj N. Kalaria
http://orcid.org/0000-0001-7907-4923
Article
Publisher ID: 1230DOI: 10.1186/s40478-021-01230-6
PMC ID: 8330023
PubMed ID: 34340718
SO-VID: d0a2755a-3ba1-4cae-bdc5-b088705564da
Copyright © © The Author(s) 2021
License:
Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
History
Date
received
: 22
February
2021
Date
accepted
: 16
July
2021
Funding
Funded by: FundRef http://dx.doi.org/10.13039/501100002283, Alzheimer’s Research UK;
Award ID: ARUK-PG2013-22
Award Recipient
:
Raj N. Kalaria
Categories
Subject:
Research
Custom metadata
issue-copyright-statement © The Author(s) 2021
Data availability: