Janex-1, a JAK3 Inhibitor, Ameliorates Tumor Necrosis Factor-α-induced Expression of Cell Adhesion Molecules and Improves Myocardial Vascular Permeability in Endotoxemic Mice

Vascular endothelial cells play an important role in leukocyte trafficking during the inflammatory process. Proinflammatory cytokines activate the expression of cell adhesion molecules in endothelial cells. Janus kinase (JAK) and signal transducer and activator of transcription (STAT) are important intracellular cytokine signaling molecules that are involved in immune responses. The purpose of this study was to investigate the effect of JAK3 inhibition on the expression of tumor necrosis factor (TNF)-α-induced cell adhesion molecules in vascular endothelial cells and to evaluate the therapeutic potential of JAK3 for myocardial vascular permeability in endotoxemic mice. A JAK3 inhibitor, JANEX-1, decreased the TNF-α-induced expression of intercellular adhesion molecule (ICAM)-1, VCAM (vascular cell adhesion molecule)-1 and fractalkine in human umbilical vein endothelial cells (HUVECs). The downregulation of the expression of these cell adhesion molecules by JANEX-1 was mediated via suppression of STAT3 phosphorylation and nuclear factor-κB (NF-κB) activation. In endotoxemic mice, pretreatment with JANEX-1 prevented not only an increase in the cardiac ICAM-1 expression by LPS in the arteriolar and capillary endothelial cells, but also myocardial vascular leakage. These results suggest that inhibition of the JAK/STAT pathway by JANEX-1 ameliorates the expression of TNF-α-induced cell adhesion molecules in HUVECs and improves myocardial vascular permeability.