Transcriptomic Evidence of MAS1 Receptor Dysregulation and a Failed Compensatory State in Human Vascular Cognitive Impairment.

Background: Vascular contributions to cognitive impairment and dementia (VCID) are thought to arise from distributed neurovascular unit (NVU) dysfunction rather than focal pathology, yet the transcriptional architecture of human VCID brain tissue and the status of endogenous counter-regulatory signaling within it remain incompletely characterized. Defining whether protective pathways are engaged and why they may be insufficient is critical for identifying therapeutic entry points in a disease lacking approved treatments. Methods: We performed differential gene expression analysis (DESeq2 v1.38.0) and pre-ranked gene set enrichment analysis (fgsea v1.24.0) on bulk RNA-sequencing data from superior parietal lobe tissue (GEO:GSE303449; n = 40; 19 VCID, 21 controls; model: age_scaled + Sex + condition), followed by Spearman correlation analysis, PI3K-Akt pathway level, leading-edge decomposition, and single-nucleus RNA-seq endothelial cell characterization (GEO:GSE282111). Results: No individual gene reached FDR < 0.05 for differential expression between VCID and control across 51,962 genes tested. Gene set enrichment analysis nonetheless identified eight significantly enriched pathway programs (all FDR < 0.05) that were upregulated, encompassing inflammatory, stress-response, cytoskeletal, and apoptotic signaling, consistent with distributed network-level dysregulation rather than dominant single-gene effects. The MAS1/ANG1-7 associated signaling gene set (54 genes) was the only counter-regulatory pathway achieving significance (NES = 1.381, FDR = 0.0127). MAS1 receptor expression was strongly (absolute Spearman's rho ≥ 0.64) and inversely associated with NF-κB pathway drivers TLR4 (Spearman's rho = -0.804) and IKBKB (Spearman's rho = -0.797; both FDR = 4.73 × 10^-9). Further, 9 of 12 correlations between MAS1 downstream effectors and endothelial activation markers were FDR-significant and positive, indicating that the downstream protective effector program is co-activated by inflammatory stress rather than directed by its receptor. Single-nucleus RNA-seq supports endothelial enrichment of the MAS1 pathway enrichment signal in VCID brain tissue. PI3K-Akt leading-edge decomposition revealed 96% gene-level non-overlap between inflammatory and vasoprotective arms. Conclusions: Human VCID brain tissue exhibits coordinated pathway-level dysregulation in the absence of dominant individual-gene effects, consistent with a disease driven by distributed transcriptional network stress. The MAS1/ANG1-7 vasoprotective axis is transcriptionally engaged and endothelially enriched, yet receptor expression is inversely associated with inflammatory signaling while downstream effectors remain transcriptionally engaged. This pattern suggests a failed compensatory state in the VCID superior parietal lobe. This architecture is consistent with a transcriptionally primed but receptor-constrained protective program. These findings suggest that therapeutic strategies restoring MAS1 receptor-level input to an already engaged downstream program may represent a plausible therapeutic strategy for VCID, pending experimental validation.