Effects of a calcineurin inhibitor, FK506, and a CCR5/CXCR3 antagonist, TAK-779, in a rat small intestinal transplantation model

The effects of FK506, and TAK-779, antagonists of CCR5 and CXCR3, were investigated using a rat intestinal transplantation model. Small intestines from DA rats were heterotopically transplanted into LEW rats. The recipients were treated with FK506 (1mg/kg/day, day 0-5) and TAK-779 (10mg/kg/day, day 0-10). Graft survival and immunological responses to these Materials were estimated by mixed lymphocyte reactions and IFN-γ production. The expression of chemokine receptors on lymphocytes was also examined. The average duration of survival was 7.0±0.3, 12.0±1.0, 9.8±0.5 and 18.0±1.5days in the allogeneic, FK506, TAK-779 and the two-drug combined groups, respectively. Cell proliferative responses and IFN-γ production were suppressed to a significant extent in the FK506 group compared with the TAK-779 group. In addition, the two-drug combination showed a tendency for stronger suppression than FK506 alone, correlated with in vivo and histopathological data. The numbers of both CD4(+) and CD8(+) cells were significantly suppressed in the blood of the recipients of both the FK506 and the TAK-779 groups, and in Peyer's patches of the graft of the TAK-779 group, but the FK506 group was not, as evidenced by FACS analysis. In addition, double-staining of graft-infiltrating lymphocytes showed a significant reduction in lymphocyte numbers, expressing CCR5 and CXCR3 in the TAK-779 group, but not evident in the FK506 group, compared to the allogeneic group. While FK506 suppresses cell proliferation and effecter function, it has less effect on the expression of CCR5 and CXCR3 in lymphocytes. Further exploration of the effects of a combined therapy with TAK-779 could represent a novel treatment for intestinal transplantation.