ICAM-1 regulates macrophage polarization by suppressing MCP-1 expression via miR-124 upregulation ICAM-1 regulates macrophage polarization by suppressing MCP-1 expression via miR-124 upregulation

The vascular endothelial (VE)‐cadherin functions as an endothelial barrier protein controlling endothelial permeability and leukocyte transmigration. Developmental studies indicate that VE‐cadherin also plays a vital role in angiogenesis. MicroRNA‐22 plays important roles in cardiovascular diseases including cardiac hypertrophy and heart failure. We identified that miR‐22 interacts with VE‐cadherin mRNA. Overexpression of miR‐22 in endothelial cells increases the synthesis of proinflammatory cytokines. Injection of miR‐22 results in increased myeloperoxidase activity in the mouse lungs. Moreover, miR‐22 injection into the fluorescent‐labeled transgenic zebrafish Tg(fli1:EGFP) embryos caused defective vascular development in the dorsal and intersegmental vessels, and vascular markers were significantly suppressed in these embryos. Our studies demonstrate that the conserved targeting of VE‐cadherin by miR‐22 regulates endothelial inflammation, tissue injury, and angiogenesis.

Intercellular adhesion molecule‐1 (ICAM‐1) mediates the firm adhesion of leukocytes to endothelial cells and initiates subsequent signaling that promotes their transendothelial migration (TEM). Vascular endothelial (VE)‐cadherin plays a critical role in endothelial cell–cell adhesion, thereby controlling endothelial permeability and leukocyte transmigration. This study aimed to determine the molecular signaling events that originate from the ICAM‐1–mediated firm adhesion of neutrophils that regulate VE‐cadherin’s role as a negative regulator of leukocyte transmigration. We observed that ICAM‐1 interacts with Src homology domain 2–containing phosphatase‐2 (SHP‐2), and SHP‐2 down‐regulation via silencing of small interfering RNA in endothelial cells enhanced neutrophil adhesion to endothelial cells but inhibited neutrophil transmigration. We also found that VE‐cadherin associated with the ICAM‐1–SHP‐2 complex. Moreover, whereas the activation of ICAM‐1 leads to VE‐cadherin dissociation from ICAM‐1 and VE‐cadherin association with actin, SHP‐2 down‐regulation prevented ICAM‐1–VE‐cadherin association and promoted VE‐cadherin–actin association. Furthermore, SHP‐2 down‐regulation in vivo promoted LPS‐induced neutrophil recruitment in mouse lung but delayed neutrophil extravasation. These results suggest that SHP‐2— via association with ICAM‐1— mediates ICAM‐1–induced Src activation and modulates VE‐cadherin switching association with ICAM‐1 or actin, thereby negatively regulating neutrophil adhesion to endothelial cells and enhancing their TEM.—Yan, M., Zhang, X., Chen, A., Gu, W., Liu, J., Ren, X., Zhang, J., Wu, X., Place, A.T., Minshall, R.D., Liu, G. Endothelial cell SHP‐2 negatively regulates neutrophil adhesion and promotes transmigration by enhancing ICAM‐1–VE‐cadherin interaction. FASEB J. 31, 4759–4769 (2017). www.fasebj.org