MICA and CYTH4 as immunological biomarkers of intracranial aneurysm: a study integrating RNA sequencing, single-cell sequencing and Mendelian randomization.

Intracranial aneurysm (IA) is a common cerebral vascular malformation often leading to subarachnoid hemorrhage (SAH) with high mortality and disability rates. The molecular mechanisms underlying IA occurrence and rupture are poorly understood, highlighting the need for predictive molecular markers. Here, we employed bioinformatics and Mendelian randomization analysis to identify MICA and CYTH4 as molecular markers closely associated with arterial aneurysm rupture, offering new insights for IA prevention and treatment. We integrated five datasets (GSE15629, GSE26969, GSE54083, GSE13353, and GSE122897) to create a research cohort of 34 non-IA and 93 IA samples. Differential gene expression analysis was performed using single-cell sequencing data from IA mice, followed by KEGG enrichment analysis. Mendelian randomization analysis was conducted on two samples to determine the causal relationship between gene expression and IA risk. Receiver operating characteristic (ROC) and decision curve analysis (DCA) curves were constructed. We further conducted GSEA, immune microenvironment analysis, cell trajectory analysis, and intercellular communication research on single-cell data. Molecular biology experiments have confirmed that altered expression of MICA and CYTH4 can effectively regulate the proliferation of endothelial cells and their apoptosis under stress conditions. We identified 297 downregulated and 295 upregulated DEGs between IA and control groups. KEGG enrichment analysis implicated cytokines, NF-κB signaling, and TNF signaling in promoting IA onset, while cAMP signaling may inhibit it. Mendelian randomization analysis revealed MICA and CYTH4 as key genes related to IA prognosis, with CYTH4 as a risk factor, and MICA potentially protective. GSEA and GeneMANIA enrichment analysis indicated roles for CYTH4 and MICA in immune regulation of IA. Single-cell sequencing data linked CYTH4 to neutrophil degranulation during macrophage differentiation, with CellChat showing correlation between CYTH4 and CCL signaling. This study highlights MICA and CYTH4 as significant biomarkers for IA progression, particularly CYTH4's role in immune inflammatory response and prognosis. These findings contribute to understanding IA pathogenesis and advancing its diagnosis and treatment.