[HTML][HTML] MerTK receptor cleavage promotes plaque necrosis and defective resolution in atherosclerosis

B Cai, EB Thorp, AC Doran… - The Journal of …, 2017 - Am Soc Clin Investig
B Cai, EB Thorp, AC Doran, BE Sansbury, MJAP Daemen, B Dorweiler, M Spite, G Fredman
The Journal of clinical investigation, 2017Am Soc Clin Investig
Atherothrombotic vascular disease is often triggered by a distinct type of atherosclerotic
lesion that displays features of impaired inflammation resolution, notably a necrotic core and
thinning of a protective fibrous cap that overlies the core. A key cause of plaque necrosis is
defective clearance of apoptotic cells, or efferocytosis, by lesional macrophages, but the
mechanisms underlying defective efferocytosis and its possible links to impaired resolution
in atherosclerosis are incompletely understood. Here, we provide evidence that proteolytic …
Atherothrombotic vascular disease is often triggered by a distinct type of atherosclerotic lesion that displays features of impaired inflammation resolution, notably a necrotic core and thinning of a protective fibrous cap that overlies the core. A key cause of plaque necrosis is defective clearance of apoptotic cells, or efferocytosis, by lesional macrophages, but the mechanisms underlying defective efferocytosis and its possible links to impaired resolution in atherosclerosis are incompletely understood. Here, we provide evidence that proteolytic cleavage of the macrophage efferocytosis receptor c-Mer tyrosine kinase (MerTK) reduces efferocytosis and promotes plaque necrosis and defective resolution. In human carotid plaques, MerTK cleavage correlated with plaque necrosis and the presence of ischemic symptoms. Moreover, in fat-fed LDL receptor–deficient (Ldlr–/–) mice whose myeloid cells expressed a cleavage-resistant variant of MerTK, atherosclerotic lesions exhibited higher macrophage MerTK, lower levels of the cleavage product soluble Mer, improved efferocytosis, smaller necrotic cores, thicker fibrous caps, and increased ratio of proresolving versus proinflammatory lipid mediators. These findings provide a plausible molecular-cellular mechanism that contributes to defective efferocytosis, plaque necrosis, and impaired resolution during the progression of atherosclerosis.
The Journal of Clinical Investigation