Abstract 3652: Selective NF-KappaB Blockade in Endothelial Cells Impairs Collateral Growth Due to Poor Monocyte Recruitment
Background. Arteriogenesis, the growth of collateral arteries, plays a significant role in effective restoration of blood flow following occlusion of a major artery. The primary signal behind the induction of collateral growth is thought to be endothelial cell-dependent recruitment of blood-derived mononuclear cells due to shear-stress-dependent activation of nuclear factor (NF) κB. We propose using inducible transgenic approach; to selective inactivate NFκB in endothelial cells and to examine the effect of this manipulation on collateral growth.
Methods. We employed a double-transgenic approach using a Tet-OFF system to express an IκBα super-repressor mutant (NFκB-DN) specific in endothelium under Tie-2 promoter. The extent and the time course of arteriogenesis following right femoral artery ligation was evaluated in control and NFκB-DN mice. Distal limb perfusion was measured by laser-Doppler imaging (LDI) while micro CT to assess vascular growth. Leucocyte recruitment in adductor and gastrocnemius muscles was assesed by immunohistology and flow cytometry (FSC/SSC) analysis.
Results. Following femoral artery ligation serial LDI demonstrated a significantly reduced blood flow restoration in NFκB-DN compared to control mice (day 21: 0.26 vs. 0.83, n=4 mice/group, p<0.05). Interestigly, at day 21, quantitative micro CT analysis of NFκB-DN mice, confirmed an increased growth of small arterioles (≤ 40 μm diameter) interconnected in a dense meshwork. Three days after femoral artery ligation there was a less recruitment of CD45+ leukocytes in NFκB-DN. However,among different types of leucocytes we found similar proportion of monocytes (CD11b+ F4/80−), macrophages (CD11b+F4/80+) and dendritic cells (CD11b+CD11c+). Differently, we found in NFκB-DN a highly represented leukocyte population “look like myeloid cells” CD11b−F4/80−CD11c−CD3−B220−.
Conclusion. Endothelial specific inhibition of NFκB signaling pathway results in reduced leukocyte recruitment in ischemic hindlimb, and formation of disorganized arteriole network that impairs the blood flow recovery.
This research has received full or partial funding support from the American Heart Association, AHA National Center.