Junctional Adhesion Molecules (JAM)-B and -C Contribute to Leukocyte Extravasation to the Skin and Mediate Cutaneous Inflammation

Leukocyte extravasation is a finely tuned process, in which transmigration is the final step. Transmigration depends on molecules located at borders of endothelial cells; e.g., junctional adhesion molecules (JAM-A, -B and -C). In vivo blockade of JAM-A lead to decreased migration of monocytes into the skin. In contrast, the role of JAM-B and -C in development of cutaneous inflammation is unknown. We therefore elicited an allergic contact dermatitis in mice using 2,4-dinitro-1-fluorobenzene. RT-PCR and immunofluorescent staining of healthy skin revealed a constitutive JAM-B (66.4%±6.7% of all vessels) and -C expression (88.6±13.2%), which remained constant after induction of contact dermatitis. Functional studies, in which either JAM-B or -C neutralizing antibodies were injected into sensitized mice prior to allergen challenge showed a concentration-dependent reduction of the contact dermatitis. Decreased ear swelling was accompanied by reduction of leukocyte infiltration as analyzed by hematoxylin and eosin (H&E) histology and enzyme activity. Combined antibody treatment at doses of 1.25 mg per kg bodyweight lead to additive inhibition of allergic contact dermatitis, indicating that JAM-B and -C may have distinct functions. In conclusion, interactions with JAM-B and -C are essential for development of cutaneous inflammation.