Loss of Caspase-Activated DNase Protects Against Atherosclerosis in Apolipoprotein E-Deficient Mice

Atherosclerosis is a chronic disease that is closely related to inflammation and macrophage apoptosis, which leads to secondary necrosis and proinflammatory responses in advanced lesions. Caspase-activated DNase (CAD) is a double-strand specific endonuclease that leads to the subsequent degradation of chromosome DNA during apoptosis. However, whether CAD is involved in the progression of atherosclerosis remains elusive.

CAD^-/-ApoE^-/- and ApoE^-/- littermates were fed a high-fat diet for 28 weeks to develop atherosclerosis. Human specimens were collected from coronary heart disease (CHD) patients who were not suitable for transplantation. CAD expression was increased in the atheromatous lesions of CHD patients and high-fat diet-treated ApoE-deficient mice. Further investigation demonstrated that CAD deficiency inhibited high-fat diet-induced atherosclerosis, as evidenced by decreased atherosclerotic plaques, inhibited inflammatory response, and macrophage apoptosis, as well as enhanced stability of plaques in CAD^-/-ApoE^-/- mice compared to the ApoE^-/- controls. Bone marrow transplantation verified the effect of CAD on atherosclerosis from macrophages. Mechanically, the decrease in the phosphorylated levels of mitogen-activated protein kinase (MAPK) kinase/extracellular signal-regulated kinase 1 and 2 (MEK-ERK1/2) that resulted from CAD knockout and the activation of nuclear factor kappa B signaling mediated by CAD stimulation that was suppressed by inhibiting ERK1/2 phosphorylation revealed the potential association between the role of CAD in atherosclerosis and the MAPK signaling pathway.

In conclusion, CAD deficiency protects against atherosclerosis through inhibiting inflammation and macrophage apoptosis, which is partially through inactivation of the MEK-ERK1/2 signaling pathway. This finding provides a promising therapeutic target for treating atherosclerosis.