Objective: To determine the role of the endothelial cell adhesion molecules E- and P-selectin in the development and severity of adjuvant-induced arthritis (AIA) in the rat.
Methods: Lewis rats were immunized subcutaneously with Mycobacterium butyricum (Mb), and blocking monoclonal antibodies (mAb) to rat E- and P-selectin were administered. Clinical score, radiolabeled (51Cr and 111In) blood polymorphonuclear leukocyte (PMN) and monocyte migration to joints, and histologic features were monitored.
Results: When mAb treatment was started on day 5 postimmunization with Mb (preclinical stage), development of AIA was significantly (P < 0.01) inhibited by mAb to E- but not to P-selectin (mean score on day 14 control 10.2, anti-E 2.8, anti-P 9.1). This was associated with markedly decreased migration (by 66-94%) of PMN and monocytes to arthritic joints and diminished cartilage degradation. When treatment was delayed until animals showed signs of arthritis (day 10 postimmunization), only a marginal and variable effect was observed as compared with blockade during the preclinical (day 5) stage. E-selectin blockade on day 5 and day 7 postimmunization resulted in inhibition of antigen-dependent T cell-mediated inflammation, since it decreased T cell migration to sites of dermal-delayed hypersensitivity induced by Mb without affecting migration to concanavalin A or cytokines. The proliferative response of T cells to Mb in vitro was not altered.
Conclusion: E-selectin plays an important role early in the development of AIA. This adhesion molecule may contribute to the migration of antigen-reactive T cells to peripheral tissues, including the joints where T cells initiate the arthritis.