Critical role of TNF-α in cerebral aneurysm formation and progression to rupture.
BACKGROUND: Alterations in TNF-α expression have been associated with cerebral aneurysms, but a direct role in formation, progression, and rupture has not been established. METHODS: Cerebral aneurysms were induced through hypertension and a single stereotactic injection of elastase into the basal cistern in mice. To test the role of TNF-α in aneurysm formation, aneurysms were induced in TNF-α knockout mice and mice pretreated with the synthesized TNF-α inhibitor 3,6'dithiothalidomide (DTH). To assess the role of TNF-α in aneurysm progression and rupture, DTH was started 6 days after aneurysm induction. TNF-α expression was assessed through real-time PCR and immunofluorescence staining. RESULTS: TNF-α knockout mice and those pre-treated with DTH had significantly decreased incidence of aneurysm formation and rupture as compared to sham mice. As compared with sham mice, TNF-α protein and mRNA expression was not significantly different in TNF-α knockout mice or those pre-treated with DTH, but was elevated in unruptured and furthermore in ruptured aneurysms. Subarachnoid hemorrhage (SAH) occurred between 7 and 21 days following aneurysm induction. To ensure aneurysm formation preceded rupture, additional mice underwent induction and sacrifice after 7 days. Seventy-five percent had aneurysm formation without evidence of SAH. Initiation of DTH treatment 6 days after aneurysm induction did not alter the incidence of aneurysm formation, but resulted in aneurysmal stabilization and a significant decrease in rupture. CONCLUSIONS: These data suggest a critical role of TNF-α in the formation and rupture of aneurysms in a model of cerebral aneurysm formation. Inhibitors of TNF-α could be beneficial in preventing aneurysmal progression and rupture.
Starke, RM; Chalouhi, N; Jabbour, PM; Tjoumakaris, SI; Gonzalez, LF; Rosenwasser, RH; Wada, K; Shimada, K; Hasan, DM; Greig, NH; Owens, GK; Dumont, AS
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