Expression of MUC2 and MUC4 proteins and cytokines: Early markers of intestinal graft rejection

Background. Histopathologic examination (HP) is the primary method of monitoring intestinal graft rejection. Alterations in mucin levels have been demonstrated in bowel diseases. The aim of this study was to detect early markers of intestinal graft rejection based on mucin and cytokine levels. Methods. Allogeneic and syngeneic orthotopic intestinal transplantations were performed in untreated Lewis strain recipient rats from Dark Agouti and Lewis strain donors, respectively (unmodified rejection and nonrejection groups). Similarly, allogeneic and syngeneic orthotopic intestinal transplantations were performed in tacrolimus (immunosuppression)-treated groups. HP was performed on hematoxylineosin and periodic acid Schiff-stained sections. Expression of MUC2 and MUC4 proteins and of mRNA was detected by immunohistochemistry and Northern analysis, respectively. Interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and transforming growth factor-β₁ were measured by reverse transcription-polymerase chain reaction. Results. HP revealed early or mild rejection on day 3, moderate rejection on day 5, and severe rejection on day 7 posttransplantation (posttx) in the unmodified rejection group. A significant (P<0.01) increase in MUC2 and MUC4 expression was observed on day 3 posttx in the allogeneic rejection group compared with syngeneic controls; the levels decreased by day 7. Goblet cells were significantly more frequent on day 3 compared with days 5 and 7 posttx (P<0.01). IFN-γ and TNF-α expression were also higher in the rejection group. Conclusions. Early transplant rejection is associated with increased MUC2, MUC4, IFN-γ, and TNF-α expression. These markers combined with HP may assist in the diagnosis of early intestinal graft rejection.