Serum amyloid beta 42 levels correlated with metabolic syndrome and its components.

Introduction: Beta-amyloid accumulation in the brain appears to be a key initiating event in Alzheimer's disease (AD), and factors associated with increased deposition of beta-amyloid are of great interest. Enhanced deposition of amyloid-ß peptides is due to an imbalance between their production and elimination. Previous studies show that diminished levels of CSF amyloid beta 42 (Aß42) is a biomarker in AD; however, the role of serum Aß42 in AD is contradictory. BMI and obesity have been reported to be related to increased serum Aß42 levels. Therefore, we aimed to investigate the relation between metabolic syndrome (MetS), its clinical measures (abdominal obesity, high glucose, high triglyceride, low high-density lipoprotein cholesterol level, and hypertension), and serum Aß42 levels. Methods: A total of 1261 subjects, aged 18-89 years in Chengdu, China, were enrolled from January 2020 to January 2021 to explore the correlation of serum Aß42 levels with body mass index (BMI), blood lipids, and blood pressure. Furthermore, as the risk of MetS is closely related to age, 1,212 participants (N = 49 with age ≥ 80 years old were excluded) were analyzed for the correlation of serum Aß42 level and MetS clinical measures. Results: The results showed that log-transformed serum Aß42 level was positively correlated with BMI (R = 0.29; p < 0.001), log-transformed triglyceride (R = 0.14; p < 0.001), and diastolic blood pressure (DBP) (R = 0.12; p < 0.001) and negatively correlated with high-density lipoprotein (HDL-c) (R = -0.18; p < 0.001). After adjusting for age, sex, and other covariates, elevated serum Aß42 level was correlated with higher values of BMI (ßmodel1 = 2.694, ßmodel2 = 2.703) and DBP (ßmodel1 = 0.541, ßmodel2 = 0.546) but a lower level of HDL-c (ßmodel2 = -1.741). Furthermore, serum Aß42 level was positively correlated with MetS and its clinical measures, including BMI and DBP, and negatively correlated with HDL-c level in the Han Chinese population. However, the level of serum Aß42 did not show a significant correlation with high glucose or high triglyceride. Discussion: These observations indicate that MetS and its components are associated with higher levels of serum Aß42 and hence limit the potential of serum Aß42 as a suitable diagnostic biomarker for AD. As such, we recommend serum Aß42 serve as a direct risk biomarker for MetS rather than for AD.

Three-Dimensional Biohybrid StarPEG-Heparin Hydrogel Cultures for Modeling Human Neuronal Development and Alzheimer's Disease Pathology.

In this chapter, we present the methodology currently used in our laboratory to generate a starPEG-MMP (starPEG)- and heparin maleimide HM06 (heparin)-based 3D cell culture system, in a hydrogel, that can be used to study human neuronal development and Alzheimer's disease (AD) pathology. A 3D cell culture system can mimic the in vivo cellular environment better than a 2D format, in which these cells exhibit neural network formation, electrophysiological activity, tissue-specific extracellular matrix (ECM) deposition, and neurotransmitter responsiveness. When treated with amyloid beta-42 (Aß42) peptides, this system recapitulates many of the pathological effects of AD, including reduced neural stem cell proliferation, impaired neuronal network formation, dystrophic axonal ends, synaptic loss, failure to deposit ECM, elevated tau hyperphosphorylation, and formation of neurofibrillary tangles. Culturing human primary cortical astrocyte (pHA)- or induced pluripotent stem cell (iPSC)-derived human neural stem cells in this biohybrid hydrogel system has led to the discovery of novel regulatory pathways underlying neurodegenerative pathology in different phases of AD.