Clinical significance of plasma candidate biomarkers of Alzheimer's Disease.

The number of patients with Alzheimer's Disease (AD) has increased rapidly in recent decades. AD is a complex progressive neurodegenerative disease affecting c.14 million patients in Europe and the United States. The hallmarks of this disease are neurotic plaques composed of the amyloid-ß (Aß) peptide and neurofibrillary tangles formed of hyperphosphorylated tau protein (pTau). To date, four CSF biomarkers: amyloid beta 42 (Aß42), Aß42/40 ratio, Tau protein, and Tau phosphorylated at threonine 181 (pTau181) have been validated as core neurochemical AD biomarkers. Imaging biomarkers are valuable for AD diagnosis, although they suffer from limitations in their cost and accessibility, while CSF biomarkers require lumbar puncture. Thus, there is an urgent need for alternative, less invasive and more cost-effective biomarkers capable of diagnosing and monitoring AD progression in a clinical context, as well as expediting the development of new therapeutic strategies. This review assesses the potential clinical significance of plasma candidate biomarkers in AD diagnosis. We conclude that these proteins might hold great promise in identifying the pathological features of AD. However, the future implementation process, and validation of the assays' accuracy using predefined cut-offs across more diverse patient populations, are crucial in establishing their utility in daily practice.

Plasma neurofilament light, glial fibrillary acid protein, and phosphorylated tau 181 as biomarkers for neuropsychiatric symptoms and related clinical disease progression.

BACKGROUND: Neuropsychiatric symptoms (NPS) are common in older people, may occur early in the development of dementia disorders, and have been associated with faster cognitive decline. Here, our objectives were to investigate whether plasma levels of neurofilament light chain (NfL), glial fibrillary acid protein (GFAP), and tau phosphorylated at threonine 181 (pTau181) are associated with current NPS and predict future NPS in non-demented older people. Furthermore, we tested whether the presence of NPS combined with plasma biomarkers are useful to predict Alzheimer's disease (AD) pathology and cognitive decline. METHODS: One hundred and fifty-one participants with normal cognition (n=76) or mild cognitive impairment (n=75) were examined in a longitudinal brain aging study at the Memory Centers, University Hospital of Lausanne, Switzerland. Plasma levels of NfL, GFAP, and pTau181 along with CSF biomarkers of AD pathology were measured at baseline. NPS were assessed through the Neuropsychiatric Inventory Questionnaire (NPI-Q), along with the cognitive and functional performance at baseline and follow-up (mean: 20 months). Linear regression and ROC analyses were used to address the associations of interest. RESULTS: Higher GFAP levels were associated with NPS at baseline (ß=0.23, p=.008). Higher NfL and GFAP levels were associated with the presence of NPS at follow-up (ß=0.29, p=.007 and ß=0.28, p=.007, respectively) and with an increase in the NPI-Q severity score over time (ß=0.23, p=.035 and ß=0.27, p=.011, respectively). Adding NPS and the plasma biomarkers to a reference model improved the prediction of future NPS (AUC 0.73 to 0.84, p=.007) and AD pathology (AUC 0.79 to 0.86, p=.006), but not of cognitive decline (AUC 0.79 to 0.84, p=.068). CONCLUSION: Plasma GFAP is associated with NPS while NfL and GFAP are both associated with future NPS and NPS severity. Considering the presence of NPS along with blood-based AD-biomarkers may improve diagnosis and prediction of clinical progression of NPS and inform clinical decision-making in non-demented older people.

The preliminary study suggests an association between NF-ĸB pathway activation and increased plasma 20S proteasome activity in intracranial aneurysm patients.

The significant role of increased activation of 20S proteasomes in the development of abdominal aortic aneurysms has been well-established in a mouse model. The available literature lacks similar studies concerning brain aneurysms. The aim of the study was to verify the hypothesis that patients with unruptured intracranial aneurysms (UIA) have increased 20S proteasome ChT-L activity compared to the control group of individuals without vascular lesions in the brain. In the next step, the relationship between the activity of 20S proteasomes ChT-L and precursor proteins from the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) family, namely NF-κB1 (p105), NF-κB2 (p100), NF-κB p65, and the inflammatory chemokine MCP-1, was examined. Patients with UIA had significantly higher 20S ChT-L proteasome activity compared to the control group. Patients with multiple aneurysms had significantly higher 20S proteasome ChT-L activity compared to those with single aneurysms. In patients with UIA, the activity of the 20S proteasome ChT-L negatively correlated with the concentration of NF-κB1 (p105) and NF-κB p65 precursor proteins and positively correlated with the concentration of the cerebrospinal fluid chemokine MCP-1. Our results may suggest that increased 20S proteasome ChT-L activity in UIA patients modulates inflammation in the cerebral arterial vessel via the MCP-1 chemokine as a result of activation of the canonical NF-κB pathway.

Plasma neurofilament light, glial fibrillary acid protein, and phosphorylated tau 181 as biomarkers for neuropsychiatric symptoms and related clinical disease progression.

BACKGROUND: Neuropsychiatric symptoms (NPS) are common in older people, may occur early in the development of dementia disorders, and have been associated with faster cognitive decline. Here, our objectives were to investigate whether plasma levels of neurofilament light chain (NfL), glial fibrillary acid protein (GFAP), and tau phosphorylated at threonine 181 (pTau181) are associated with current NPS and predict future NPS in non-demented older people. Furthermore, we tested whether the presence of NPS combined with plasma biomarkers are useful to predict Alzheimer's disease (AD) pathology and cognitive decline. METHODS: One hundred and fifty-one participants with normal cognition (n = 76) or mild cognitive impairment (n = 75) were examined in a longitudinal brain aging study at the Memory Centers, University Hospital of Lausanne, Switzerland. Plasma levels of NfL, GFAP, and pTau181 along with CSF biomarkers of AD pathology were measured at baseline. NPS were assessed through the Neuropsychiatric Inventory Questionnaire (NPI-Q), along with the cognitive and functional performance at baseline and follow-up (mean: 20 months). Different regression and ROC analyses were used to address the associations of interest. RESULTS: None of the three plasma biomarker was associated with NPS at baseline. Higher GFAP levels were associated with the presence of NPS at follow-up (OR = 2.8, p = .002) and both, higher NfL and higher GFAP with an increase in the NPI-Q severity score over time (ß = 0.25, p = .034 and ß = 0.30, p = .013, respectively). Adding NPS and the plasma biomarkers to a reference model improved the prediction of future NPS (AUC 0.72 to 0.88, p = .002) and AD pathology (AUC 0.78 to 0.87, p = .010), but not of cognitive decline (AUC 0.79 to 0.85, p = .081). CONCLUSION: Plasma NfL and GFAP are both associated with future NPS and NPS severity change. Considering the presence of NPS along with blood-based AD-biomarkers may improve the prediction of clinical progression of NPS over time and inform clinical decision-making in non-demented older people.

Plasma p-tau212 antemortem diagnostic performance and prediction of autopsy verification of Alzheimer's disease neuropathology.

Blood phosphorylated tau (p-tau) biomarkers, including p-tau217, show high associations with Alzheimer's disease (AD) neuropathologic change and clinical stage. Certain plasma p-tau217 assays recognize tau forms phosphorylated additionally at threonine-212, but the contribution of p-tau212 alone to AD is unknown. We developed a blood-based immunoassay that is specific to p-tau212 without cross-reactivity to p-tau217. Here, we examined the diagnostic utility of plasma p-tau212. In five cohorts (n = 388 participants), plasma p-tau212 showed high performances for AD diagnosis and for the detection of both amyloid and tau pathology, including at autopsy as well as in memory clinic populations. The diagnostic accuracy and fold changes of plasma p-tau212 were similar to those for p-tau217 but higher than p-tau181 and p-tau231. Immunofluorescent staining of brain tissue slices showed prominent p-tau212 reactivity in neurofibrillary tangles that co-localized with p-tau217 and p-tau202/205. These findings support plasma p-tau212 as a peripherally accessible biomarker of AD pathophysiology.

Aß oligomers peak in early stages of Alzheimer's disease preceding tau pathology.

INTRODUCTION: Soluble amyloid beta (Aß) oligomers have been suggested as initiating Aß related neuropathologic change in Alzheimer's disease (AD) but their quantitative distribution and chronological sequence within the AD continuum remain unclear. METHODS: A total of 526 participants in early clinical stages of AD and controls from a longitudinal cohort were neurobiologically classified for amyloid and tau pathology applying the AT(N) system. Aß and tau oligomers in the quantified cerebrospinal fluid (CSF) were measured using surface-based fluorescence intensity distribution analysis (sFIDA) technology. RESULTS: Across groups, highest Aß oligomer levels were found in A+ with subjective cognitive decline and mild cognitive impairment. Aß oligomers were significantly higher in A+T- compared to A-T- and A+T+. APOE Îµ4 allele carriers showed significantly higher Aß oligomer levels. No differences in tau oligomers were detected. DISCUSSION: The accumulation of Aß oligomers in the CSF peaks early within the AD continuum, preceding tau pathology. Disease-modifying treatments targeting Aß oligomers might have the highest therapeutic effect in these disease stages. Highlights: Using surface-based fluorescence intensity distribution analysis (sFIDA) technology, we quantified Aß oligomers in cerebrospinal fluid (CSF) samples of the DZNE-Longitudinal Cognitive Impairment and Dementia (DELCODE) cohortAß oligomers were significantly elevated in mild cognitive impairment (MCI)Amyloid-positive subjects in the subjective cognitive decline (SCD) group increased compared to the amyloid-negative control groupInterestingly, levels of Aß oligomers decrease at advanced stages of the disease (A+T+), which might be explained by altered clearing mechanisms.

Plasma p-tau212: antemortem diagnostic performance and prediction of autopsy verification of Alzheimer's disease neuropathology.

Blood phosphorylated tau (p-tau) biomarkers, including p-tau217, show high associations with Alzheimer's disease (AD) neuropathologic change and clinical stage. Certain plasma p-tau217 assays recognize tau forms phosphorylated additionally at threonine-212, but the contribution of p-tau212 alone to AD is unknown. We developed a blood-based immunoassay that is specific to p-tau212 without cross-reactivity to p-tau217. Thereafter, we examined the diagnostic utility of plasma p-tau212. In five cohorts (n=388 participants), plasma p-tau212 showed high performances for AD diagnosis and for the detection of both amyloid and tau pathology, including at autopsy as well as in memory clinic populations. The diagnostic accuracy and fold changes of plasma p-tau212 were similar to those for p-tau217 but higher than p-tau181 and p-tau231. Immunofluorescent staining of brain tissue slices showed prominent p-tau212 reactivity in neurofibrillary tangles that co-localized with p-tau217 and p-tau202/205. These findings support plasma p-tau212 as a novel peripherally accessible biomarker of AD pathophysiology.

sICAM-1 intrathecal synthesis and release during the acute phase in children suffering from Coxsackie A9 and S. pneumoniae meningoencephalitis / Sintesis intratecal de sICAM-1 y liberación durante la fase aguda en niños con meningoencefalitis por Coxsackie A9 y S pneumoniae

The intercellular adhesion molecule is a transmembrane glycoprotein belonging to the immunoglobulin superfamily. Serum and cerebrospinal fluid (CSF) soluble intercellular adhesion molecule 1 (sICAM-1) from normal control children as well as from children with Guillain-Barré syndrome (GBS), with Coxsackie A9 virus meningoencephalitis and with Streptococcus pneumoniae meningoencephalitis were studied. sICAM-1 was quantified using an immunoenzimatic assay and albumin using the immunodiffusion technique in both biological fluids. Increased sICAM-1 values in CSF in patients with GBS correspond to an increase of the albumin CSF/serum quotient. In contrast, in inflammatory diseases like S. pneumoniae and Coxsackie A9 virus meningoencephalitis an increased brain-derived fraction was observed. In particular cases these values are 60-65 percent and 70-75 percent respectively. The results indicate an additional synthesis of sICAM-1 in subarachnoidal space during central nervous system (CNS) inflammatory process. An important role of sICAM-1 in the transmigration of different cell types into CSF during CNS inflammation in children with S. pneumoniae and Coxsackie A9 meningoencephalitis may be suggested.

La molécula de adhesión intercelular es una glicoproteína que pertenece a la superfamilia de las inmunoglobulinas. Se estudiaron los niveles de molécula de adhesión intercelular tipo 1 soluble (sICAM-1) en suero y líquido cefalorraquídeo (LCR) de niños con meningoencefalitis por Streptococcus pneumoniae y por Coxsackie A9 al igual que en niños con sindrome de Guillain-Barré (SGB). sICAM-1 fue cuantificado por ensayo inmunoenzimático y la albúmina por inmunodifusión en ambos líquidos biológicos. Los valores incrementados de sICAM-1 en LCR en los pacientes con GBS corresponden a valores aumentados de razón LCR/suero de albúmina. En contraste, en las enfermedades inflamatorias como las meningoencefalitis por S. pneumoniae y por Coxsackie A9 se observa un incremento en la fracción derivada del cerebro. En casos particulares los valores se incrementan hasta un 60-65 por ciento y 70-75 por ciento respectivamente. Los resultados indican una síntesis adicional de sICAM-1 en el espacio subaracnoideo durante el proceso inflamatorio del sistema nervioso central (SNC). Esto puede sugerir un importante papel del sICAM-1 en la transmigración de diferentes tipos celulares en el LCR durante la inflamación del SNC en niños con meningoencefalitis por S pneumoniae y coxsackie A9.