Augmented regeneration of partial liver allograft induced by nuclear factor-kappaB decoy oligodeoxynucleotides-modified dendritic cells.

AIM: To investigate the effect of NF-kappaB decoy oligodeoxynuleotides (ODNs) - modified dendritic cells (DCs) on regeneration of partial liver allograft.

METHODS: Bone marrow (BM)- derived DCs from SD rats were propagated in the presence of GM-CSF or GM-CSF+IL-4 to obtain immature DCs or mature DCs, respectively. GM-CSF-propagated DCs were treated with double-strand NF-kappaB decoy ODNs containing two NF-kappaB binding sites or scrambled ODNs. Allogeneic (SD rat to LEW rat) 50% partial liver transplantation was performed. Normal saline (group A), GM-CSF -propagated DCs (group B), GM-CSF+IL-4 - propagated DCs (group C), and GM-CSF+NF-kappaB decoy ODNs (group D) or scrambled ODNs -propagated DCs (group E) were injected intravenously into recipient LEW rats 7 days prior to liver transplantation and immediately after transplantation. DNA synthesis (BrdU labeling) and apoptosis of hepatocytes were detected with immunostaining and TUNEL staining postoperative 24 h, 48 h, 72 h and 84 h, respectively. Liver graft-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma level at the time of the maximal liver allograft regeneration were measured with (51)Cr release assay, semiquantitative RT-PCR and ELISA, respectively.

RESULTS: Regeneration of liver allograft was markedly promoted by NF-kappaB decoy ODNs-modified immature DCs but was significantly suppressed by mature DCs, the DNA synthesis of hepatocytes peaked at postoperative 72 h in group A, group B and group E rats, whereas the DNA synthesis of hepatocytes peaked at postoperative 84 h in group C rats and 48 h in group D rats, respectively. The maximal BrdU labeling index of hepatocytes in group D rats was significantly higher than that in the other groups rats. NF-kappaB decoy ODNs-modified immature DCs markedly suppressed but mature DCs markedly promoted apoptosis of hepatocytes, liver-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma production. At the time of the maximal regeneration of liver allograft, the minimal apoptosis of hepatocytes, the minimal activity of liver-resident NK cells, the minimal hepatic IFN-gamma mRNA expression and serum IFN-gamma production were detected in group D rats. The apoptotic index of hepatocytes, the activity of liver- resident NK cells, the hepatic IFN-gamma mRNA expression level and the serum IFN-gamma level in group D rats were significantly lower than that in the other groups rats at the time of the maximal regeneration of liver allograft.

CONCLUSION: The data suggest that the augmented regeneration of partial liver allograft induced by NF-kappaB decoy ODNs-modified DCs may be attributable to the reduced apoptotic hepatocytes, the suppressed activity of liver-resident NK cells and the reduced IFN-gamma production.