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Ninjurin1 is a homotypic adhesion molecule that contributes to leukocyte trafficking in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. However, in vivo gene deficiency animal studies have not yet been done. Here, we constructed Ninjurin1 knock-out (KO) mice and investigated the role of Ninjurin1 on leukocyte trafficking under inflammation conditions such as EAE and endotoxin-induced uveitis. Ninjurin1 KO mice attenuated EAE susceptibility by reducing leukocyte recruitment into the injury regions of the spinal cord and showed less adhesion of leukocytes on inflamed retinal vessels in endotoxin-induced uveitis mice. Moreover, the administration of a custom-made antibody (Ab26-37) targeting the Ninjurin1 binding domain ameliorated the EAE symptoms, showing the contribution of its adhesion activity to leukocyte trafficking. In addition, we addressed the transendothelial migration (TEM) activity of bone marrow-derived macrophages and Raw264.7 cells according to the expression level of Ninjurin1. TEM activity was decreased in Ninjurin1 KO bone marrow-derived macrophages and siNinj1 Raw264.7 cells. Consistent with this, GFP-tagged mNinj1-overexpressing Raw264.7 cells increased their TEM activity. Taken together, we have clarified the contribution of Ninjurin1 to leukocyte trafficking in vivo and delineated its direct functions to TEM, emphasizing Ninjurin1 as a beneficial therapeutic target against inflammatory diseases such as multiple sclerosis.

Objective Blocking agents targeting cell adhesion molecules have been developed to prevent cardiovascular diseases such as atherosclerosis, whereas relatively little attention has been paid to the therapeutic potential of vascular cell adhesion molecule (VCAM)-1 as an inflammatory disease target. Two novel, fully human antibodies, H6 and 7H, against human VCAM-1 (hVCAM-1) were developed and tested to validate the hypothesis that blocking VCAM-1 ameliorates atherosclerosis in apolipoprotein E-deficient (ApoE −/− ) mice. Methods and results Treatment with H6 or 7H effectively inhibited VCAM-1 adhesion to inflammatory cells, and reduced RhoA activation and the production of reactive oxygen species in human umbilical cord vascular endothelial cells. As 7H showed binding affinity to both murine VCAM-1 (mVCAM-1) and hVCAM-1, the therapeutic effects of 7H in ApoE −/− mice were tested. After confirming specific in vivo binding activity of 7H to mVCAM-1, we showed that administering 7H resulted in significantly ameliorated plaque formation compared to administering a control antibody in ApoE −/− mice fed a Western diet for 12 weeks. Also, 7H treatment significantly reduced infiltration of CD45 + cells into plaques and reduced inflammation and improved plaque stability. Conclusion These results indicate that the anti-VCAM-1 antibody attenuates atherosclerosis in ApoE −/− mice, improves plaque inflammation and stability as well as inhibiting the adhesion of inflammatory cell, and suggest that blocking VCAM-1 with a monoclonal antibody may be an effective means of anti-atherosclerotic therapy.