Integrative Transcriptomics and Mendelian Randomization Identify RGS1 as a Causal Immune Regulator in Alzheimer's Disease.

Alzheimer's disease (AD) has a complex pathogenesis, involving molecular and neuroimmune dysregulation, but the causal drivers linking transcriptomic changes to immune remodeling are not yet clear. In a discovery cohort, differential expression analysis was performed, and it was independently validated in two external cohorts. Key genes were prioritized via LASSO/logistic regression, functionally annotated, and causally linked to AD using two-sample MR. The neuroimmune landscape was mapped by ssGSEA, and top candidates were validated in vitro. RGS1 is a key node in neuroinflammation and cytoskeletal dynamics, which is prioritized by the algorithmic intersection. MR analysis suggested a potential causal association between genetically predicted RGS1 expression and AD risk. RGS1 was consistently upregulated in both discovery and validation cohorts (AUC: 0.61-0.67) and was confirmed in vitro. Immune deconvolution showed that AD-specific enrichment profiles occur, and RGS1 is strongly correlated with activated CD4+ T cells and pro-inflammatory chemokines. RGS1 is identified as a robust key gene that may contribute to immune microenvironment dysregulation in AD, and combining discovery-validation transcriptomics, causal inference, and experimental validation, we find that RGS1 is a potential immunomodulatory target.