Fingerprinting Alzheimer’s Disease by ¹H Nuclear Magnetic Resonance Spectroscopy of Cerebrospinal Fluid

Abstract

In this study, we sought for a cerebrospinal fluid (CSF) metabolomic fingerprint in Alzheimer's disease (AD) patients characterized, according to the clinical picture and CSF AD core biomarkers (Aβ 42 , p-tau, and t-tau), both at pre-dementia (mild cognitive impairment due to AD, MCI-AD) and dementia stages (ADdem) and in a group of patients with a normal CSF biomarker profile (non-AD) using untargeted 1 H nuclear magnetic resonance (NMR) spectroscopy-based metabolomics. This is a retrospective study based on two independent cohorts: a Dutch cohort, which comprises 20 ADdem, 20 MCI-AD, and 20 non-AD patients, and an Italian cohort, constituted by 14 ADdem and 12 non-AD patients. 1 H NMR CSF spectra were analyzed using OPLS-DA. Metabolomic fingerprinting in the Dutch cohort provides a significant discrimination (86.1% accuracy) between ADdem and non-AD. MCI-AD patients show a good discrimination with respect to ADdem (70.0% accuracy) but only slight differences when compared with non-AD (59.6% accuracy). Acetate, valine, and 3-hydroxyisovalerate result to be altered in ADdem patients. Valine correlates with cognitive decline at follow-up (R = 0.53, P = 0.0011). The discrimination between ADdem and non-AD was confirmed in the Italian cohort. The CSF metabolomic fingerprinting shows a signature characteristic of ADdem patients with respect to MCI-AD and non-AD patients.

Effects of Probiotics Administration on Human Metabolic Phenotype

“…One of the main findings of metabolomics is that systemic biofluids like blood, urine and saliva, contain a strong individual metabolic signature, called metabolic phenotype or metabotype, which is stable over time, allowing us to monitor individual status and response to different stimuli [ 22 , 23 , 24 , 25 , 26 , 27 ], as well as to fingerprint several different diseases [ 28 , 29 , 30 , 31 , 32 , 33 ]. The metabotype is a multifactorial entity; in fact, besides being a snapshot of the subject’s genotype and metabolism, it is also influenced by many other factors, like gut microbiota, diet, lifestyle, drugs, etc.…”

Pursuing Experimental Reproducibility: An Efficient Protocol for the Preparation of Cerebrospinal Fluid Samples for NMR-Based Metabolomics and Analysis of Sample Degradation

“…In the reviewed literature, we did not find general agreement about protocol (experimental conditions), or optimal pH values for NMR-based metabolomics studies of CSF. Some studies did not report or adjust sample pH [8,23,24,26,32,35], while others manually adjusted it by adding acid/base [4,7,19,28,29,35,37] or employed a phosphate buffer with varying buffer capacity [5,6,13,18,20,21,25,27,31,33,34,38,39]. Table 1.…”

“…Either adjusted with buffer solution [5,6,13,18,20,21,25,27,31,33,34,38,39], by adding HCl/NaOH solution [4,7,19,28,29,35,37], or ignored [8,23,24,26,32,36].…”

“…A phosphate buffer system H 2 PO 4 − /HPO 4 2− (pK a 6.8) with an ideal buffer capacity in the pH range of 5.8-7.8 is well suited for pH control in CSF samples-native human CSF has a pH of 7.3. Adjusting buffer pH to a slightly lower value, pH 7.2, compensates for inter-sample pH variability and keeps the pH of samples in the range of native CSF [33,48]. In Figure 1 the 1D 1 H NMR spectra of a CSF sample at pH 7.48 along with two spectra of the model solution at different pH values are shown demonstrating the impact of a pH increase (e.g., as a result of improper handling of a native CSF sample).…”

Resolving Metabolic Heterogeneity in Experimental Models of the Tumor Microenvironment from a Stable Isotope Resolved Metabolomics Perspective

“…Metabolic profiling of tissues and biofluids including blood plasma [80][81][82][83], urine [84][85][86], and cerebrospinal fluid (CSF) [86][87][88][89] using NMR and MS in the past decade has been shown to be very valuable for reporting disease states and drug responses. This is due to metabolic reprogramming in • C/5% CO 2 before fixing in 4% buffered formalin, embedded in paraffin block, and sectioned into 4 µm slices for H&E staining in (A) and IF staining for cancer cells (panCytokeratin or panCK), CD8 (cytotoxic T cells), and CD68 (Mφ) in (B).…”