A novel technique for selective NF-κB inhibition in Kupffer cells: contrary effects in fulminant hepatitis and ischaemia-reperfusion

Background and aims: The transcription factor nuclear factor kappa B (NF-kappa B) has risen as a promising target for anti-inflammatory therapeutics. In the liver, however, NF-kappa B inhibition mediates both damaging and protective effects. The outcome is deemed to depend on the liver cell type addressed. Recent gene knock-out studies focused on the role of NF-kappa B in hepatocytes, whereas the role of NF-kappa B in Kupffer cells has not yet been investigated in vivo. Here we present a novel approach, which may be suitable for clinical application, to selectively target NF-kappa B in Kupffer cells and analyse the effects in experimental models of liver injury. Methods: NF-kappa B inhibiting decoy oligodeoxynucleotides were loaded upon gelatin nanoparticles (D-NPs) and their in vivo distribution was determined by confocal microscopy. Liver damage, NF-kappa B activity, cytokine levels and apoptotic protein expression were evaluated after lipopolysaccharide (LPS), D-galactosamine (GalN)/LPS, or concanavalin A (ConA) challenge and partial warm ischaemia and subsequent reperfusion, respectively. Results: D-NPs were selectively taken up by Kupffer cells and inhibited NF-kappa B activation. Inhibition of NF-kappa B in Kupffer cells improved survival and reduced liver injury after GalN/LPS as well as after ConA challenge. While anti-apoptotic protein expression in liver tissue was not reduced, pro-apoptotic players such as cJun N-terminal kinase (JNK) were inhibited. In contrast, selective inhibition of NF-kappa B augmented reperfusion injury. Conclusions: NF-kappa B inhibiting decoy oligodeoxynucleotide-loaded gelatin nanoparticles is a novel tool to selectively inhibit NF-kappa B activation in Kupffer cells in vivo. Thus, liver injury can be reduced in experimental fulminant hepatitis, but increased at ischaemia-reperfusion.