Up-regulated intragraft gene expression, ICAM-1 and IL-2R molecules, and apoptotic epithelial cells during rejection of rat small intestine allografts

Objective To investigate the kinetics and the magnitude of intragraft gene expression of interleukin-2 (IL-2), interferon-gamma (IFN-gamma), perforin and granzyme B, and intragraft expression of interleukin-2 receptor (IL-213 ) and intercellular adhesion molecule-1 (ICAM-1) during acute rejection epi sodes, and to analyze the changes in apoptosis in small intestinal allograf t rejection. Methods Heterotopic small intestine transplantation was performed with inbr ed rats F344/N (RT1(1)) and Wistar/A (RT1-A(k), RT1-E-d). All recipients we re divided into four groups: group 1: Wistar, native control; group 2: Wist ar --> Wistar; group 3: F344 --> Wistar and group 4: F344 --> Wistar + cycl osporine A (6 mg . kg(-1) . d(-1) I. M.). The grafts were harvested on post operative days (PODs) 3, 5 and 7. All samples were examined pathologically. Intragraft mRNA expression of IL-2, IFN-gamma, perforin and granzyme B wer e detected with reverse transcriptase polymerase chain reaction (RT-PCR) an d intragraft expression of IL-213 and ICAM-1 were stained using immunohisto chemistry. We also analyzed the change in apoptosis rejection with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). Results Mild acute rejection occurred on POD 3 in the allograft group, mode rate acute rejection on POD 5, and severe acute rejection on POD 7, while n one of the isografts had histological evidence of acute rejection. Cyclospo rine A could effectively control rejection. Gene expression was virtually n egative in the native control. Only on POD 5 was IL-2 mRNA expression of al lografts significantly higher than that of isografts ( P < 0.05). IFN-gamma mRNA expression was significantly higher than that of the control groups ( P< 0.01) on PODs 3, 5 and 7, and the level of perforin and granzyme B mRNA expression reached significantly higher levels than in the other two contr ol groups on POD 5 and POD 7. Intragraft IL-2R expression of the allograft was significantly higher than that of the other three control groups. Only on POD 3 was intragraft ICAM-1 expression of allografts significantly highe r than isografts. The number of apoptotic cells per crypt of allografts was significantly higher than that of the other three control groups on POD 3 and POD 5 (P <less than> 0.01). Conclusion Transcription of IL-2, IFN-,gamma, perforin and granzyme B, and expression of IL-213 and ICAM-1 as well as apoptosis of epithelial cells of the grafts play an important role in small intestine allograft rejection. Intragraft gene expression of IFN-gamma and intragraft expression of IL-2R as well as apoptotic epitheliall cells may become a specific and sensitive diagnostic method of clinical value. Furthermore, therapeutic strategies to alter these molecules in small intestine transplantation may improve the o utcome of current antirejection therapy.