Pirfenidone inhibits the induction of iNOS stimulated by interleukin-1beta at a step of NF-kappaB DNA binding in hepatocytes.
OBJECTIVE
Pirfenidone has antiinflammatory effects in animals with endotoxemia. We reported that pirfenidone inhibits the enhancement of inflammatory cytokines and inducible nitric oxide synthase (iNOS) in liver of endotoxin-treated rats, leading to the prevention of hepatic injury. However, the mechanisms involved in suppression of these gene inductions are obscure. Studies were performed to investigate whether pirfenidone directly influences iNOS induction in hepatocytes.


METHODS
Cultured hepatocytes were treated with interleukin-1beta (IL-1beta) in the presence and absence of pirfenidone, and iNOS induction and its signal including NF-kappaB were analyzed.


RESULTS
Pirfenidone inhibited the induction of iNOS mRNA and protein, resulting in the decrease of nitric oxide production. Gel shift assay demonstrated that pirfenidone inhibited the activation of NF-kappaB. Consistent with this observation, transfection experiments revealed that pirfenidone decreased transcriptional activation of iNOS gene promoter. In contrast, pirfenidone had no effect on the degradation of IkappaB, and could not prevent nuclear translocation of p50/p65. Finally, pirfenidone inhibited the activation of Akt and up-regulation of IL-1 receptor stimulated by IL-1beta.


CONCLUSIONS
Results indicate that pirfenidone inhibits the induction of iNOS gene expression at a step of NF-kappaB DNA binding, but not its nuclear translocation, partly through the inhibition of IL-1 receptor induction in hepatocytes.
Nakanishi
Hideki
H
The First Department of Surgery, Kansai Medical University, 10-15 Fumizonocho, Moriguchi, Osaka 570-8506, Japan.
Kaibori
Masaki
M
Teshima
Shigeru
S
Yoshida
Hideyuki
H
Kwon
A-Hon
AH
Kamiyama
Yasuo
Y
Nishizawa
Mikio
M
Ito
Seiji
S
Okumura
Tadayoshi
T
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011728:Pyridones / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017472:Receptors, Interleukin-1 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007375:Interleukin-1; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D011728:Pyridones; D017472:Receptors, Interleukin-1; C093844:pirfenidone; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt