To characterize systemic response to rupture of an intracranial aneurysm (IA) through analysis of small RNAs in peripheral blood cells.

Sixty-nine patients were included into the study: 19 patients in the acute phase of IA rupture (RAA, first 72 hours), 20 – in the chronic phase (RAC, 3-15 months), and 20 controls. Using deep transcriptome sequencing we analyzed expression of small RNAs. Functional analysis to determine over-represented ontological groups among gene expression profiles was performed. Potential interactions between regulatory RNAs and target genes were investigated. We also measured levels of 4 proteins which expression is regulated by miRs showing differential expression after IA rupture.  

Comparing RAA, RAC and controls we found 491 differentially expressed transcripts (226 were down-regulated, 177 upregulated in RAA patients). Functional analysis revealed that the miRNAs upregulated after IA rupture can regulate T-lymphocytes-related mRNAs, whereas downregulated miRNAs are associated with IL1- and IL4-related pathways. Among studied inflammatory-related proteins, Fas, FasL, and HMGB1, showed significantly decreased levels in RAA patients, whereas CD40 levels did not change significantly.

IA rupture in the acute phase strongly influences the transcription profiles of peripheral blood cells. Altered pattern of small RNAs expression in response to IA rupture indicates molecular mechanisms that control the inflammatory response.