Correlation between Transforming Growth Factor-beta and Procollagen III with Regenerative Activity in Acute Liver Injury, and the Effect of Prostaglandin E2

Cho, Nam Hoon; Park, Chan Il

Abstract

Transforming growth factor-beta (TGF-beta) plays an important role in hepatic fibrogenesis. It is thought to inhibit regeneration of the hepatocytes. The aim of this present study was to clarify the correlation of TGF-beta, collagen type III (PIIINP) and the regenerating activity of hepatocytes, and the effect of prostaglandin E2 (PgE2) on them in acute liver injury. Two hundred and sixteen male Sprague-Dawley rats, weighing 200g on average, were divided into six experimental groups and two control groups; group I-CCl4 only administration, group II-partial hepatectomy(PH) only, group III-PH following CCl4 administration, group IV-olive oil only administration, group V-sham operation, group VI-CCl4 administration with pretreatment of PgE2, group VII- PH with pretreatment of PgE2, and group VIII- PH following CCl4 administration with pretreatment of PgE2. Five rats were sacrificed at 12, 24, 36, 48, 96 and 168 hours after the administration of CCl4 or PH in each experimental group. The liver was tested with immunohistochemical stain for proliferating cell nuclear antigen (PCNA) and in situ hybridization for TGF-beta. Radioimmunoassay for serum PIIINP was also performed. The results were as follows: TGF-beta was expressed mainly in the perisinusoidal cells and periportal mesenchymal cells. The TGF-beta positive cells were most numerous in the combined group of CCl4 plus PH. TGF-beta expression tended to have an inverse relation, with the PCNA index in all experimental groups. The PCNA index was highest in the CCl4 only group and lowest in the combined group of CCl4 plus PH. The PH only group showed a peak PCNA index at 48 hours. In the CCl4 only group and the combined group of CCl4 plus PH, serum PIIINP appeared to increase at 12 hours or more after the expression of hepatic TGF-beta. Pretreatment of PgE2 revealed that TGF-beta precipitously disappeared at 48-96 hours after insult. PgE2 influenced the vanishing period, not the emerging time of TGF-beta and had a remarkable effect on the amount of TGF-beta especially in the PH following CCl4 administration group, which resulted in significant accentuation of PCNA indices. In conclusion, PH of the prior injured liver induces a marked increase of TGF-beta followed by a significant suppression of regeneration of the remaining liver, and PgE2 overtly suppresses the expression of TGF-beta.