MT4-MMP deficiency increases patrolling monocyte recruitment to early lesions and accelerates atherosclerosis

Matrix metalloproteinases are involved in vascular remodeling. Little is known about their immune regulatory role in atherosclerosis. Here we show that mice deficient for MT4-MMP have increased adherence of macrophages to inflamed peritonea, and larger lipid deposits and macrophage burden in atherosclerotic plaques. We also demonstrate that MT4-MMP deficiency results in higher numbers of patrolling monocytes crawling and adhered to inflamed endothelia, and the accumulation of Mafb+ apoptosis inhibitor of macrophage (AIM)+ macrophages at incipient atherosclerotic lesions in mice. Functionally, MT4-MMP-null Mafb+AIM+ peritoneal macrophages express higher AIM and scavenger receptor CD36, are more resistant to apoptosis, and bind acLDL avidly, all of which contribute to atherosclerosis. CCR5 inhibition alleviates these effects by hindering the enhanced recruitment of MT4-MMP-null patrolling monocytes to early atherosclerotic lesions, thus blocking Mafb+AIM+ macrophage accumulation and atherosclerosis acceleration. Our results suggest that MT4-MMP targeting may constitute a novel strategy to boost patrolling monocyte activity in early inflammation.This study was supported by grants from the Spanish Ministry of Economy, Industry and Competitiveness (MEIC; RD12/0042/0023 [FEDER cofunded] and SAF2014-52050R and SAF2017-83229R to A.G.A., SAF2015-64287R and SAF2015-71878-REDT to M.R., RD12/0042/0053 [FEDER cofunded] and SAF2015-64767-R to J.M-G., and SAF2016-79490-R and RD12/0042/0028 [FEDER cofunded] to V.A.) and from La Marató TV3 Foundation. C.C., M.M-A., and L.A-H. were funded by fellowships from the Spanish Ministry of Education, MEIC, and La Caixa-CNIC, respectively. C.R. was funded by a competitive postdoctoral contract grant FPDI-2013-17423 from MEIC. The CNIC is supported by the Spanish MEIC and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505).Peer reviewe