Selectin Inhibitor Bimosiamose Prolongs Survival of Kidney Allografts by Reduction in Intragraft Production of Cytokines and Chemokines

Binding of the P-, L-, and E-selectins to sialyl Lewis x (sLe x ) retards circulating leukocytes, thereby facilitating their attachment to the blood vessels of allografts. Whether the selectin inhibitor bimosiamose (BIMO; C46H54O16 0.25 H2O (867.4 mo- lecular weight)) inhibits the rejection process of kidney allografts in a rat model was examined. Rat recipients acutely rejected kidney allografts at a mean survival time of 8.8 0.75 d. An intravenous 7-d infusion by osmotic pump of 2.5, 5, 10, or 20 mg/kg BIMO extended kidney allograft survival to 11.5 2.2 d (P 0.03), 25.4 11.4 d (P 0.006), 37.4 13.6 d (P 0.001), and 39.8 34.5 d (P 0.01), respectively. Combination of BIMO with cyclosporine produced synergistic interactions, as documented by the combination index (CI) values of 0.34 to 0.43 (CI 1 is synergistic; CI 1 is additive; and CI 1 is antago- nistic). Similarly, BIMO interacted synergistically with sirolimus (CI 0.64) and FTY720 (CI 0.22). While the mechanism of immunosuppression was being analyzed, decreased infiltration of CD4, CD8, and macrophages on day 7 after grafting was observed. Multiple cytokines were also expressed, including IL- 1, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12, IL-18, TNF-, and IFN- in kidney allografts on days 3, 5, and 7 after grafting, as measured by a ribonuclease protection assay. Furthermore, at similar time points, BIMO treatment reduced intragraft expression of P-selectin glycoprotein ligand-1, CX3CL1, CCL19, CCL20, and CCL2. Thus, BIMO blocks allograft rejection by reduction of intragraft expression of cytokines and chemokines.