Smooth muscle cells-derived CXCL10 prevents endothelial healing through PI3Kγ-dependent T cells response.

AIMS: Defects in efficient endothelial healing have been associated with complication of atherosclerosis such as post-angioplasty neoatherosclerosis and plaque erosion leading to thrombus formation. However, current preventive strategies do not consider re-endothelialization in their design. Here, we investigate mechanisms linking immune processes and defect in re-endothelialization. We especially evaluate if targeting phosphoinositide 3-kinase γ immune processes could restore endothelial healing and identify immune mediators responsible for these defects. METHODS AND RESULTS: Using in vivo model of endovascular injury, we showed that both ubiquitous genetic inactivation of PI3Kγ and hematopoietic cell-specific PI3Kγ deletion improved re-endothelialization and that CD4+ T-cell population drives this effect. Accordingly, absence of PI3Kγ activity correlates with a decrease in local IFNγ secretion and its downstream interferon-inducible chemokine CXCL10. CXCL10 neutralization promoted re-endothelialization in vivo as the same level than those observed in absence of PI3Kγ suggesting a role of CXCL10 in re-endothelialization defect. Using a new established ex vivo model of carotid re-endothelialization, we showed that blocking CXCL10 restore the IFNγ-induced inhibition of endothelial healing and identify smooth muscle cells as the source of CXCL10 secretion in response to Th1 cytokine. CONCLUSION: Altogether, these findings expose an unforeseen cellular cross-talk within the arterial wall whereby a PI3Kγ-dependent T-cell response leads to CXCL10 production by smooth muscle cells which in turn inhibits endothelial healing. Therefore, both PI3Kγ and the IFNγ/CXCL10 axis provide novel strategies to promote endothelial healing.

Re-endothelialisation after Synergy stent and Absorb bioresorbable vascular scaffold implantation in acute myocardial infarction: COVER-AMI study.

BACKGROUND/AIMS: Drug eluting stent (DES) decrease the risk of restenosis by reducing the neointimal response. However, DES may impair strut coverage, and this has been associated with late stent/scaffold thrombosis. Bioresorbable vascular scaffold (BVS) may overcome the risk of stent/scaffold thrombosis when completely resorbed. The purpose of this randomised trial was to compare the arterial healing response in the short term, as a surrogate for safety and efficacy, between the metallic everolimus-eluting stent (Synergy; Boston Scientific, Marlborough, MA, USA) and the everolimus BVS (Absorb; Abbott Vascular, Santa Clara, CA, USA) in the particular setting of acute myocardial infarction (AMI). This pilot study sought to compare the neointimal response of metallic everolimus DES (Synergy) with polymeric everolimus BVS (Absorb) by optical coherence tomography (OCT) 3 months after an AMI. METHODS: COVER-AMI was a single-centre, single-blind, non-inferiority, randomised controlled trial. Patients with ST segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention were randomly allocated (1:1) to treatment with the Synergy DES or Absorb BVS. The primary endpoint was the 3-month neointimal response assessed as the percentage of uncovered struts, neointimal thickness, in-stent/scaffold area obstruction, and pattern of neointima. The main secondary endpoint included the device-oriented composite endpoint according to the Academic Research Consortium definition. RESULTS: Twenty patients without clinical and/or angiographic complications (Synergy (n = 10) or BVS (n = 10); mean age 59.0 years; 20% female) were enrolled in our centre. The stent diameter was higher in the Synergy group (3.7 ± 0.4 mm vs 3.4 ± 0.4 mm in the BVS group, p = 0.01). At 3 months, no significant differences in angiographic lumen loss were observed between the everolimus DES and everolimus BVS (0.04 mm (IQR 0.00-0.07) vs 0.11 mm (IQR 0.04-0.31), p = 0.165). OCT analysis of 420 cross-sections showed that the total neointimal area and in-stent obstruction were lower in the Synergy group, while OCT analysis at the strut level (n = 3942 struts) showed that the rate of uncovered struts was lower in the BVS group. CONCLUSIONS: Stenting of culprit lesions in the setting of STEMI resulted in a nearly complete arterial healing for both the Synergy and the BVS devices. Lower neointimal thickness and in-stent obstruction but a higher rate of uncovered struts were observed in the Synergy group. These findings provide the basis for further exploration in clinically oriented outcome trials.