An Insight about Neurofilaments and Alzheimer's Disease

Abstract

Background: Neurofilaments (NFs) are intermediate filaments with a diameter of 10 nm, similar to that of neurons. Although they are present in perikarya and dendrites, neurofilaments are particularly abundant in axons where they are essential for the radial growth of axons during development, the maintenance of axon caliber, and the transmission of electrical impulses along axons. Neurofilaments are composed of polypeptide chains or subunits that belong to the same protein family as the intermediate filaments of other tissues, such as keratin subunits, which make 10 nm filaments expressed specifically in epithelia. The family of proteins making intermediate filaments is divided into 5 major classes, The keratins form Classes I and II, and Class III contains the proteins vimentin, desmin, peripherin, and glial fibrillary acidic protein (GFAP). Biomarkers can be used as a diagnostic tool, allowing earlier and more specific identification of pathology, predicting disease progression, deepening our understanding of pathogenesis, guiding the selection of patients with evidence of disease pathologies to treatment trials, and acting as surrogate endpoints in clinical trials. The new studies search for additional CSF biomarkers for other aspects of AD pathophysiology, e.g. neurofilament light chain (NFL) reflecting neuroaxonal injury. By its role as a neurodegenerative biomarker, NFL has consistently been shown to correlate positively with CSF T-tau and P-tau, whereas associations between NFL and CSF Aβ42 have been weak, negative, or non-existent. The level of NFL is elevated in many neurodegenerative diseases and is not disease-specific, so it is not suitable to be used as a diagnostic marker of AD, but its value in judging the severity of the disease and predicting disease progression and prognosis cannot be ignored.