Mutations in

Atherosclerosis is considered to be a chronic inflammatory disease characterized by enhanced expression of proinflammatory cytokines, chemokines, and adhesion molecules (1-3). The cross-talk between cytokines, chemokines, and infiltrating immune cells amplifies the inflammatory cascade in the vessel wall, resulting in atherogenesis (1-3).Interleukin-18 (IL-18) 3 is a proinflammatory and proatherogenic cytokine that induces the expression of other proinflammatory cytokines and adhesion molecules (4). IL-18 has been localized to human atherosclerotic lesions (5, 6), and circulating IL-18, which is increased in acute coronary syndromes (7), has been shown to predict future cardiovascular events (7). A positive correlation between serum IL-18 levels and carotid intima-media thickness has been demonstrated (8). Administration of IL-18 aggravates atherosclerosis in mice (9). Moreover, atherogenesis is reduced in IL-18-deficient apoE knock-out mice (10), suggesting a causal role for IL-18 in the development and progression of atherosclerosis.Recently, we demonstrated that IL-18 induces human aortic smooth muscle cell (SMC) proliferation (11). However, it is not known whether IL-18 induces SMC migration. Both migration and proliferation play a role in normal and diseased vessels (1-3). SMC migration contributes to normal angiogenesis. However, SMC migration also plays a causal role in pathological remodeling of the vessel walls during atherosclerosis, arteriosclerosis, and restenosis following angioplasty (1-3).Vessel wall remodeling is characterized by a disruption in the delicate balance between extracellular matrix (ECM) deposition and degradation, with matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of matrix metalloproteinases (TIMPs)) playing a prominent role. MMPs are zinc-dependent proteases and are classified as collagenases, stromelysins, elastases, and gelatinases based on substrate specificity. Their expression is regulated at both the transcriptional and post-transcriptional levels. They are synthesized as proenzymes and are activated following proteolytic cleavage. SMCs express MMP2 (gelatinase A) and MMP9 (gelatinase B), the two gelatinases described so far (12). Excess activation of MMP2 and MMP9, without alteration of TIMP expression and activation, results in destruction of the ECM and can lead to pathological remodeling and vascular restenosis (12-15). Because increased matrix degradation promotes SMC migration (15), we hypothesized that IL-18 induces SMC migration via induction of MMP9. Our novel findings demonstrate that IL-18 promotes SMC

This study identified multiple novel c-Abl–mediated nmMLCK phosphorylation sites by mass spectroscopy and examined their influence on nmMLCK function and human lung endothelial barrier regulation. The data indicate an essential role for Abl kinase in vascular barrier regulation via phosphorylation of nmMLCK and the actin-binding protein cortactin.

No abstract