Abstract: The aim was to study the relationship between immunological and inflammatory reactions and matrix remodeling. Expression and distribution of immunological and inflammatory reactions were analyzed and compared between ruptured and unruptured saccular aneurysms by immunohistopathological stain. Immunological and inflammatory reactions commonly existed which were triggered mainly by T cells and monocyte/macrophages in aneurysm walls, which tended to be “patchy” pattern in ruptured aneurysms. The essence of matrix remodeling process in saccular aneurysms is a kind of immunological and inflammatory reaction which can accelerate enzymatic degradation of collagens by releasing proteinases, weakening aneurysm walls and may eventually lead to aneurysm rupture.

Key words: saccular aneurysm, immunological and inflammatory reaction, matrix remodeling