Genetic and molecular evidence linking CTSH to Alzheimer's disease pathophysiology.

INTRODUCTION

Lysosomal dysfunction contributes to Alzheimer's disease (AD) by impairing protein clearance and promoting neuroinflammation. Cathepsin H (CTSH), a lysosomal protease, recently emerged as a protective AD locus. We investigated how CTSH is regulated and how it influences early AD pathophysiology.

METHODS

We analyzed genomic, transcriptomic, and proteomic data from cerebrospinal fluid (CSF) and brain tissue across three independent clinical and post mortem cohorts to assess CTSH regulation, expression, and disease associations.

RESULTS

The coding variant rs2289702 acts as a cis-regulatory variant, altering CTSH mRNA and protein levels. The T allele associates with better cognition and reduced amyloid plaque burden. CSF CTSH correlates with total tau, phosphorylated tau181, neuronal markers, and multiple glial and complement-related inflammatory proteins.

DISCUSSION: CTSH tracks early neurodegenerative, synaptic, and inflammatory changes, and co-expression analyses link it to broader immune-metabolic pathways. The findings position CTSH as a genetically regulated contributor to AD pathophysiology.