Probing The Link Between Indolent Aneurysm Dome Infection And Brain Aneurysm Growth And Rupture.

Abstract

Background: Vascular inflammation and immune activation play important roles in intracranial aneurysm (IA) pathology. From mycotic aneurysms it is apparent that fulminant microbial infection can drive aneurysm formation and rupture. Recently microbial DNA has also been discovered in aneurysm domes with no clinical signs of infection. This suggests that low level microbial infections may also influence aneurysm pathology. However, more comprehensive analyses are required to test this hypothesis. To this end, we explored the possibility that IA progression is related to indolent, subclinical infection of the aneurysm dome by microorganisms originating from commensal or pathogenic populations existing elsewhere in the host. Methods: IA dome samples originating from one of three patient populations (stable, growing or ruptured IAs) were collected along with controls from patients undergoing IA clipping surgeries. DNA was extracted from each sample for 16S rRNA analysis using Illumina MySeq. Microbial populations in each sample were identified and analyzed to determine differences microbial populations between IA pathologies. Results and Discussion: 84 different operational taxonomic units were identified in patient samples, with 19 found only in IA tissues. No differences were seen between IA patient populations. However, IA tissues contained higher bacterial load, species number, and Bifidobacterium adolescentis and Desulovibrio count when compared to controls. In addition, a number of opportunistic pathogens were also found in IA tissues. Based on our findings it is unclear whether microorganisms pay a role in IA progression, but they may suggest a possible microbial influence in aneurysmal disease as a whole.