Neutrophil-Derived Cathelicidin Protects from Neointimal Hyperplasia

Abstract

Percutaneous transluminal angioplasty with stent implantation is used to dilate of arteries narrowed by atherosclerotic plaques and to revascularize coronary arteries occluded by atherothrombosis in myocardial infarction. Commonly applied drug-eluting stents release antiproliferative or anti-inflammatory agents to reduce the incidence of in-stent stenosis. However, these stents may lead to in-stent stenosis and increase the rate late stent thrombosis, an obstacle to Correspondence: Oliver Soehnlein, MD, PhD or Christian Weber, MD, Institute for Cardiovascular Prevention, Pettenkoferstr. 9, 80336 Munich, Phone +49-(0)89-5160-4350, Fax +49-(0)89-5160-4352, oliver.soehnlein@med.uni-muenchen.de or christian.weber@med.uni-muenchen.de. * These authors contributed equally. Competing interests:The authors do not declare any competing financial interests. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript optimal revascularization possibly related to endothelial recovery. Here we examined the contribution of neutrophils and neutrophilic granule proteins to arterial healing after injury. We found that neutrophil-born cathelicidin (mouse CRAMP, human LL-37) promoted reendothelization and thereby limited neointima formation after stent implantation. We then translated these findings, generating a neutrophil-instructing biofunctionalized miniaturized Nitinol stent coated with LL-37. This stent reduced in-stent stenosis in a mouse model of atherosclerosis, suggesting that LL-37 may promote vascular healing after interventional therapy.

Lack of Neutrophil-Derived CRAMP Reduces Atherosclerosis in Mice

“…In addition, neutrophil depletion clearly reduced the number of immobilized beads to a level close to what was found in Cramp Ϫ/Ϫ Apoe Ϫ/Ϫ mice ( Figure 2C), suggesting that CRAMP is released by activated neutrophils and immobilized on the endothelium, a circumstance likely favored by its cationicity. 13 Finally, no CRAMP was detected in B and T lymphocytes of spleens and inguinal lymph nodes (Online Figure IB, IC).…”

“…The interstitial location of CRAMP is in line with previous reports showing that cathelicidins interact with extracellular matrix proteins. 13 To evaluate the possibility of endothelial CRAMP expression, we injected Apoe Ϫ/Ϫ mice with microbeads conjugated to an antibody against CRAMP. The immobilization of these beads along the carotid artery was evident in Apoe Ϫ/Ϫ mice after 4 weeks of high-fat diet ( Figure 2C).…”

Molecular Biology of Atherosclerosis

“…Furthermore, proteins released from neutrophil granules, such as proteinase 3, directly activate chemokine production by endothelial cells and appear capable of greatly increasing the affinity of certain chemokines for their receptors on monocytes. Neutrophil cathelicidin (LL37) promotes differentiation of monocytes into more inflammatory macrophages (1846); surprisingly, LL37 also promoted endothelial recovery after injury and limited neointimal hyperplasia (1650). Neutrophils also help promote macrophage activation by secreting TNF-␣, IL-8, and IFN-␥ as well as myeloperoxidase (444).…”

Endogenous cannabinoid receptor CB1 activation promotes vascular smooth-muscle cell proliferation and neointima formation

“…We may speculate that neutrophils are rarely recruited to neointimal lesions, although their presence in neointimal lesions and their pathophysiological role has been previously evidenced ( 26,27 ). In particular, neutrophil-derived granule proteins were shown to play a protective role by promoting reendothelialization ( 27 ). As opposed to potential effects on immune cells, our data suggest that the protective effect of CB 1 antagonism on neointima formation is largely attributable to inhibition of SMC proliferation.…”

“…Interestingly, the reduction of 2-AG levels was found in both apoE Ϫ / Ϫ and apoE and 28 days after injury (data not shown). We may speculate that neutrophils are rarely recruited to neointimal lesions, although their presence in neointimal lesions and their pathophysiological role has been previously evidenced ( 26,27 ). In particular, neutrophil-derived granule proteins were shown to play a protective role by promoting reendothelialization ( 27 ).…”