Extracellular vesicle-associated proteomic changes from autism patients before and after metabolic stimulation with long-term L-serine treatment

The oral medication of L-serine decreased clinical global impression-severity (CGI-S) and clinical global impression-improvement (CGI-I). Behavioral scores, including communication, daily living skills, socialization, and adaptive behavior composite standardized scores, were estimated by distribution based MCID (Minimal clinically important difference) and all scores showed a trend of improvement. Since L-serine naturally cannot bypass the blood-brain barrier, we assumed L-serine could alter systemic molecular profiles, including protein expression in immune cells. In this study, we conducted plasma extracellular vesicle (EV) proteomic analysis to gain insight about immune changes in L-serine treated ASD patients. In order to study proteomic changes of EVs in plasma after oral medication for the ASD patients, we extracted EVs from the ASD patient’s plasma. In a study of nine ASD patients, we used LC-MS/MS to analyze changes in the proteome profile of plasma EVs before and after oral L-serine treatment. In each analysis, EVs were isolated, treated with trypsin for LC-MS/MS analysis, and processed through the PD software and several R packages.