Potential Role of Granulocyte-Monocyte Colony-Stimulating Factor in the Progression of Intracranial Aneurysms

Macrophages play a central role in the inflammatory response leading to aneurysm formation, progression, and rupture. The purpose of this study was to determine whether granulocyte-monocyte colony-stimulating factor (GM-CSF) plays a role in the progression of human intracranial aneurysms. Specifically, we investigated whether there was a correlation between the aneurysm size and the concentration of GM-CSF in the lumen of intracranial aneurysms. The concentrations of GM-CSF in blood samples drawn from the lumen of 15 human unruptured saccular intracranial aneurysms of 14 consecutive patients were compared. The aneurysm size was 10.3 +/- 9 mm on average. The mean plasma concentration of GM-CSF was 27.9 +/- 3.1 pg/mL in the lumen of intracranial aneurysms. The mean plasma concentration of GM-CSF was significantly higher in aneurysms larger than 7 mm (30.1 +/- 2.8 pg/mL) compared with aneurysms smaller than 7 mm (26.4 +/- 2.4 pg/mL; p=0.02). There was a significant positive correlation between the aneurysm size and the plasma concentration of GM-CSF (Spearman's rho=0.55; p=0.04). There is a significant positive correlation between the aneurysm size and the plasma concentration of GM-CSF in aneurysm lumens. This suggests that GM-CSF, through its stimulatory function on macrophages, may promote aneurysm progression and may be a possible therapeutic target.