Sex‐specific CSF proteomic profiling of amyloid/tau positivity identifies distinctive sex‐specific alternation of multiple proteins involved in Alzheimer’s disease

Abstract

AbstractBackgroundSporadic Alzheimer’s disease (AD) is a highly heterogeneous multifactorial disease in which females have a higher risk. Among 5.3 million senior Americans diagnosed with AD, over 60% are female. Despite the well‐established sex differences, sex‐specific molecular findings in AD are still limited. We therefore examined the role of sex in the proteomic alterations due to AD to elucidate potential protein markers of AD heterogeneity.MethodIn the discovery cohort, 599 preclinical AD and 435 controls underwent lumbar puncture. Over 7,000 proteins in cerebrospinal fluid (CSF) were measured using SomaLogic assay. Amyloid/tau positivity (AT classification) was determined using ELISA Aβ42 and pTau181 levels in CSF. Proteins with sex‐specific effects were identified through linear models focusing on the interaction term between AT classification and sex. Results were tested in the independent cohort (N = 732) using the identical approaches. We analyzed brain proteomics and transcriptomics data to validate the replicated sex‐specific proteins. We performed pathway enrichment, interaction network using ConsensusPathDB and drug‐target prediction.ResultWe identified 594 proteins with sex‐specific effects in discovery (P<0.05 and permutation FDR <0.05). Among them, 36 were validated in replication (P<0.05 and consistent direction). These proteins were found to be involved in neurologic disorders and highly enriched in axon regeneration (fold enrichment = 9.38 and FDR = 2.8×10−4). Among the 36 proteins identified, 13 were classified as female‐specific and 23 as male‐specific. These 36 proteins strongly predicted amyloid/tau positivity (AUC = 0.926) for all individuals as well as 13 female‐specific proteins for females (AUC = 0.929). The interaction network identified CCN2 as a hub and contained 10 additional proteins including JAG1 and DLL4 of Notch signaling pathway and CTSB, an amyloid precursor protein secretase, among others. The results of 36 proteins in brain proteomics and transcriptomics confirmed the sex‐specific effect of CCN2 and others on AD in different tissues. Drug target prediction suggests minocycline and etoposide as potential treatments for females as well amitriptyline and verteporfin for males.ConclusionWe robustly identified 36 proteins that showed significant sex‐specific alterations by preclinical AD. Several proteins involved in AD and neurodegeneration were highlighted. Our findings facilitate mechanistic understanding of sex differences for AD risk and progression.