Mast cells get straight As

It is characterized by a dilated aorta and if allowed to develop unchecked it can rupture, an event with a high rate of mortality.

In a new study, Guo-Ping Shi and colleagues at, Harvard Medical School, Boston, have demonstrated a role for immune cells known as mast cells in the development of disease in a mouse model of AAA.

Mast cells were shown to accumulate in AAA lesions in mice and mice lacking mast cells failed to develop AAA lesions. AAA lesion development could be restored in mast cell--deficient mice by reconstituting the mice with normal mast cells but not mast cells lacking either IL-6 or IFN-gamma.

The authors therefore suggest that mast cells participate in AAA by releasing the pro-inflammatory cytokines IL-6 and IFN-gamma, which induce the degradation of extracellular matrix in the wall of the aorta and the death of smooth muscle cells in the wall of the aorta, events that weaken the wall of the aorta, allowing it to dilate. Preventing mast cell release of cytokines and proteases might therefore provide a new approach to controlling AAA in humans.

Article:  Mast cells modulate the pathogenesis of elastase-induced abdominal aortic aneurysms in mice, Journal of Clinical Investigation, October 11, 2007.