NF-κB mediates apoptosis through FAS/FASL transcriptional activation in kupffer cells

Abstract

Introduction. NF-κB is a key transcriptional factor for cell survival, inflammation, and immune response. We demonstrated Kupffer cell-derived FasL plays a critical role in pancreatitis-induced liver 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. Methods. Tissue cultures of rat Kupffer cells were treated with elastase (1 U/L) to mimic pancreatitis before and after transfection with AdIκB, which blocks activation of NF-κB. Transfection with AdLuc served as control. TNF (ELISA), Fas/FasL, and caspase-3 (Western), TNF and Fas/FasL mRNA (RT-PCR), and NF-κB DNA binding activity (EMSA) were determined. Apoptosis was measured by TUNEL and DNA fragmentation. Gels were quantified by densitometry. Data ( n = 3) are mean ± SEM; Student’s t-test was used for statistical analysis. Results. Transfection with AdIκB attenuated the elastase-induced up regulation of Fas/FasL (Table, ∗all P < 0.01 versus elastase) and the activation of NF-κB (Figure) but did not affect elastase-induced up regulation of TNF (data not shown). In addition, AdIκB attenuated elastase-induced cleavage of caspase-3 (Figure), DNA fragmentation, and TUNEL staining (Table, ∗all P < 0.01 versus elastase). Conclusions. Inhibition of NF-κB 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.