Earliest changes associated with ALS detected in serum EVs.

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease characterized by the deposition of mutated and misfolded proteins leading to the degradation of motor neurons and the motor cortex. Several ALS-associated proteins have been linked to small extracellular vesicles (EVs). However, the role of these EVs and their cargo in the early stages of ALS has not been investigated. This study aims to identify the earliest protein changes facilitated by EVs in ALS by examining the serum of newly diagnosed ALS patients. EVs were isolated from the serum of ALS (n = 15) and healthy control (HC, n = 15) patients, before undergoing mass spectrometry analysis resulting in the identification of a panel of proteins associated with the early changes of ALS. This panel consists of 9 statistically significantly up-regulated proteins and includes haptoglobin and hemoglobin subunits, complement, and afamin, which are involved in pathways including: heme homeostasis and autophagy. The identification of haptoglobin in the ALS serum EVs suggests it has potential as an early diagnostic biomarker whilst, activation of autophagy pathways suggests early recruitment of clearance pathways in ALS. Therefore, this study uncovers the processes and proteins being facilitated through small EVs in the initial stages of ALS.