Emerging Insights into Aortic Dissection: The Role of Endothelial Dysfunction and Immune Cell Infiltration

Aortic dissection, a critical and often fatal vascular emergency caused by a tear in the aortic wall, demands prompt diagnosis and treatment due to its potential to cause vascular collapse. Individuals with inherited connective tissue disorders such as Marfan syndrome are at heightened risk, often developing the condition at a younger age, emphasizing the necessity for effective prevention and therapy. Despite its severity, the molecular pathways leading to aortic dissection are not fully understood.

Recent research from the University of Tsukuba, published in Circulation Research, has shed light on the underlying mechanisms involving endothelial cell abnormalities and immune infiltration. The team developed a novel mouse model carrying a specific mutation in the fibrillin-1 (FBN1) gene, which was identified in familial cases of aortic dissection. This genetic alteration produces an abnormal fibrillin-1 protein, leading to structural weaknesses in the aortic wall.

The mutant mice exhibited tears in the intimal and medial layers of the ascending aorta, with progression to dissection and eventual rupture. Histological and gene expression analyses indicated that the dysfunction of vascular endothelial cells occurs prior to the physical manifestation of dissection. Endothelial abnormalities facilitate the infiltration of immune cells, particularly monocytes and macrophages, into the vessel wall. Interestingly, these macrophages display both inflammatory and anti-inflammatory phenotypes, suggesting a complex immune response.

Further investigation revealed that the FBN1 mutation interferes with fibrillin-1’s ability to bind to TGFβ-binding proteins, resulting in decreased TGFβ signaling. Since TGFβ plays a vital role in maintaining vascular integrity, its reduction contributes to the disease's progression. The interplay between dysfunctional endothelial cells and immune cells, compounded by diminished TGFβ activity, appears to be central to the development of aortic dissection.

This research underscores the importance of endothelial and immune cell interactions in vascular pathology and highlights the potential for new therapeutic strategies targeting these pathways. The mouse model offers a valuable tool for further exploration of molecular mechanisms and the testing of interventions.

Source: Medical Xpress