Unmasking Hidden Systemic Effects of Neurodegenerative Diseases: A Two-Pronged Approach to Biomarker Discovery

Abstract

Neurodegenerative Diseases (NDs) are a major health challenge. Thus, finding reliable blood biomarkers for them has been of pivotal importance in translational/clinical research. However, conventional omics struggle with the complexity of blood samples making it difficult to achieve the desired goal. To address this, the potential of High Molecular Weight (HMW) serum fractionation under non-denaturing conditions as a complementary approach to the direct analysis of whole serum proteomics was explored in this work. To achieve this, a total of 58 serum samples of Alzheimer’s disease (AD), Parkinson’s disease (PD) patients and control individuals underwent both strategies: i) direct analysis of whole serum and ii) non-denaturing fractionation using 300 kDa cut-off filters (HMW serum). As expected, each approach was able to capture different sets of differentially regulated proteins since most of the altered proteins were not shared between them. More importantly, it was possible to create a discriminant model using the altered proteins from both datasets capable of successfully distinguishing the three groups (AUC = 0.999 and, median sensitivity and specificity of 97.4% and 91.7%, respectively). Among the 10 proteins included in the model (5 from each strategy), a clear evidence for the contribution of proteins from the apolipoprotein family for the diagnosis of NDs was revealed. Furthermore, HMW fractionation exposed potential changes within the organization of macromolecules and their complexes, thereby uncovering hidden effects in serum. Altogether, this work demonstrated that HMW fractionation can be a valuable complementary method to direct serum analysis and could enhance biomarker discovery.