Accelerative effect of leflunomide on recovery from hepatic fibrosis involves TRAIL-mediated hepatic stellate cell apoptosis.
OBJECTIVE
Hepatic fibrosis is reversible, associated with apoptosis of activated hepatic stellate cells (HSCs) as injury subsides, thus providing potential targets for therapy. Little is known, however, about the course of this condition. The objective of this study was to elucidate the mechanism by which Kupffer cells regulate HSC biology during regression of hepatic fibrosis and the effect of leflunomide on this process.


METHODS
We harvested Kupffer cells from rats during spontaneous recovery from liver fibrosis induced by carbon tetrachloride (CCl4) and prepared recovery Kupffer cell conditioned medium (KCCM). Culture-activated HSCs were pretreated in the absence or presence of A771726, the active metabolite of leflunomide, and then stimulated with recovery KCCM.


RESULTS
Following stimulation with recovery KCCM, HSCs showed a decrease in proliferation and an increase in apoptosis by a caspase-dependent mechanism. Furthermore, pretreatment with A771726 markedly enhanced these effects. Real-time quantitative PCR (Q-PCR) analysis showed increased expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in Kupffer cells during the spontaneous recovery phase. The pro-apoptotic function of KCCM prepared from TRAIL siRNA-treated Kupffer cells was obviously decreased, suggesting that TRAIL played an important role in recovery from hepatic fibrosis. Moreover, A771726 enhanced recovery KCCM-induced apoptosis of HSCs by a mechanism involving the inhibition of nuclear factor-kappa B (NF-kappaB) activation.


CONCLUSIONS
Our results showed the role of TRAIL in the apoptosis of activated HSCs that is induced by Kupffer cells prepared from livers recovering from CCI4-induced fibrosis and provided insights into the resolution of fibrosis and the mechanisms by which leflunomide might act upon liver fibrosis.
Tang
Xiaoming
X
School of Pharmacy, Anhui Medical University, Hefei, Anhui Province 230032, China.
Yang
Juntao
J
Li
Jun
J
D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000276:immunology; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D017077:Culture Media, Conditioned; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D007555:Isoxazoles / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007728:Kupffer Cells / Q000166:cytology; D000077339:Leflunomide; D008106:Liver Cirrhosis, Experimental / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis*
D000276:Adjuvants, Immunologic; D017077:Culture Media, Conditioned; D007555:Isoxazoles; D016328:NF-kappa B; D053221:TNF-Related Apoptosis-Inducing Ligand; C505655:Tnfsf10 protein, rat; D000077339:Leflunomide