Inhibition of p110δ PI3K prevents inflammatory response and restenosis after artery injury

Inflammatory cells play key roles in restenosis upon vascular surgical procedures such as bypass grafts, angioplasty and stent deployment but the molecular mechanisms by which these cells affect restenosis remain unclear. The p110 delta isoform of phosphoinositide 3-kinase (PI3K) is mainly expressed in white blood cells. Here, we have investigated whether p110 delta PI3K is involved in the pathogenesis of restenosis in a mouse model of carotid injury, which mimics the damage following arterial grafts. We used mice in which p110 delta kinase activity has been disabled by a knockin (KI) point mutation in its ATP-binding site (p110 delta(D910A/D910A) PI3K mice). Wild-type (WT) and p110 delta(D910A/D910A) mice were subjected to longitudinal carotid injury. At 14 and 30 days after carotid injury, mice with inactive p110 delta showed strongly decreased infiltration of inflammatory cells (including T lymphocytes and macrophages) and vascular smooth muscle cells (VSMCs), compared with WT mice. Likewise, PI-3065, a p110 delta-selective PI3K inhibitor, almost completely prevented restenosis after artery injury. Our data showed that p110 delta PI3K plays a main role in promoting neointimal thickening and inflammatory processes during vascular stenosis, with its inhibition providing significant reduction in restenosis following carotid injury. p110 delta-selective inhibitors, recently approved for the treatment of human B-cell malignancies, therefore, present a new therapeutic opportunity to prevent the restenosis upon artery injury.