Expression of cyclooxygenase-2 in foetal rat hepatocytes stimulated with lipopolysaccharide and pro-inflammatory cytokines.
Cyclooxygenase-2 (COX-2) is involved in the biosynthesis of prostanoids in the course of inflammatory reactions. This isoenzyme is regulated at the transcription level and many cells express COX-2 upon challenge with lipopolysaccharide (LPS) or pro-inflammatory cytokines. Since hepatocytes respond to LPS and pro-inflammatory stimuli, we investigated the expression of COX-2 in foetal and adult hepatocytes upon challenge with these substances. COX-2 was expressed in foetal hepatocytes incubated with LPS, tumour necrosis factor-alpha and interleukin-1beta. This response rapidly decreased after birth and was absent in hepatocytes from animals aged 2 days or more and treated under identical conditions. The expression of COX-2 was determined at the mRNA, protein and enzyme activity levels using Northern and Western blot, and following the synthesis of prostaglandin E2, respectively. The use of NS 398, a specific pharmacological inhibitor of COX-2, confirmed the expression of this isoenzyme in activated foetal hepatocytes. Synergism in COX-2 expression was observed between LPS, tumour necrosis factor-alpha and interleukin-1beta. Interleukin-6 and permeant analogues of cyclic AMP failed to induce COX-2 or to synergize with LPS. Also, transforming growth factor-beta inhibited the LPS- and pro-inflammatory cytokines-dependent expression of COX-2. These results indicate that foetal hepatocytes are competent to express COX-2 upon challenge with pro-inflammatory stimuli, a process lost completely in hepatocytes isolated from animals aged 2 days.
Martín-Sanz
P
P
Instituto de Bioquímica (CSIC-UCM), Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
Callejas
N A
NA
Casado
M
M
Díaz-Guerra
M J
MJ
Boscá
L
L
D000375:Aging / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D016207:Cytokines / Q000494:pharmacology*; D005260:Female; D007527:Isoenzymes / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000196:embryology* / Q000201:enzymology*; D011247:Pregnancy; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical
D016207:Cytokines; D007527:Isoenzymes; D008070:Lipopolysaccharides; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases