CSF proteomic profiling with amyloid and tau pathology identifies distinctive sex‐specific alteration of multiple proteins involved in Alzheimer's disease

INTRODUCTION: In Alzheimer's disease (AD), females have higher prevalence and faster progression, but sex-specific molecular findings in AD are limited. METHODS: We comprehensively examined 6162 proteins in cerebrospinal fluid (CSF) from 2496 participants to identify sex-specific proteomic alteration by CSF amyloid beta (Aβ)42 and phosphorylated tau (p-tau) levels. RESULTS: We identified and replicated 68 male-specific and 116 female-specific proteins associated with Aβ42 and/or p-tau levels. Apolipoprotein E ε4 carrier status modified sex-specific alterations of multiple proteins including S100A9 and NEFL for Aβ42 and MAPK9 and MAPKAPK2 for p-tau. Male-specific proteins, enriched in microglia, were involved in activating innate immune response. The male network exhibited direct connections among 30 proteins and highlighted MAPKAPK2 as a hub. Female-specific proteins, enriched in endothelial cells, were involved in regulating protein metabolic process. The female network exhibited direct connections among 43 proteins and highlighted CSNK2A2 and PRKCA as hubs. DISCUSSION: Our findings provide insights into mechanistic understanding of sex differences in AD risk. HIGHLIGHTS: Our proteomic study of 6162 proteins (targeted by 7006 aptamers) in cerebrospinal fluid (CSF) from 2496 participants identified and replicated 68 male-specific and 116 female-specific proteins associated with cerebrospinal fluid amyloid beta 42 and/or phosphorylated tau levels. Male-specific proteins, enriched in microglia, were involved in activation of innate immune response. The male network highlighted MAPKAPK2 involved in chronic neuronal neuroinflammation as a hub. Female-specific proteins, enriched in endothelial cells, were involved in regulation of protein metabolic process and response to external stimuli. The female network highlighted PRKCA regulating synaptic plasticity and CSNK2A2 protein involved in neuroplasticity as hubs.