Nuclear Factor-κB Mediates Kupffer Cell Apoptosis Through Transcriptional Activation of Fas/FasL1,212

IntroductionNuclear factor (NF)-κB is a key transcriptional factor for cell survival, inflammation, and stress response. We demonstrated that Kupffer cell-derived FasL plays a central role in pancreatitis-induced hepatocyte injury. The aim of this study was to determine the role of NF-κB in regulating death ligand/receptor pathway in Kupffer cells during conditions that mimic acute pancreatitis.Materials and methodsTissue cultures of rat Kupffer cells were treated with elastase (1 U/L) to mimic pancreatitis before and after infection with AdIκB to block activation of NF-κB. Tumor necrosis factor (enzyme-linked immunoassay), Fas/FasL, and caspase-3 (Western), tumor necrosis factor and Fas/FasL mRNA (reverse-transcription polymerase chain reaction), and NF-κB DNA binding (electrophoretic mobility shift assay) were determined. Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) and DNA fragmentation. Gels were quantified by densitometry. Data (n = 3) are mean ± SEM; student’s t test was used for statistical analysis.ResultsAdIκB infection up-regulated mutated IκBα that maintained its binding properties to NF-κB. Promoter–reporter assay demonstrated that FasL gene promoter was regulated by NF-κB. Infection with AdIκB attenuated the elastase-induced up-regulation of Fas/FasL (all P < 0.01 versus elastase) and NF-κB DNA binding but did not affect elastase-induced up-regulation of TNF. AdIκB attenuated elastase-induced cleavage of caspase-3, DNA fragmentation and TUNEL staining (all P < 0.01 versus elastase).ConclusionsInhibition of NF-κB DNA binding down-regulates Fas/FasL and attenuates elastase-induced apoptosis; however, it has no effect on TNF production, suggesting that regulation of Fas/FasL and TNF may occur via different pathways. The ability of Kupffer cells to autoregulate their stress response by up-regulating their death ligand/receptor and apoptosis warrants further investigation.