Effects of JBP485 on the expression and function of PEPT1 in indomethacin-induced intestinal injury in rats and damage in Caco-2 cells.

To investigate the effect of JBP485 (an anti-inflammatory dipeptide) on PEPT1 in indomethacin-induced intestinal injury in rats and damage in Caco-2 cells, the activity and expression of PEPT1 were examined. The effects of treatment with indomethacin and co-treatment with JBP485 were examined in terms of intestinal histological changes, MDA and MPO levels in rats; as well as LDH-release and oxidative stress in Caco-2 cells. Uptake of glycylsarcosine (Gly-Sar) by PEPT1 was determined by in vivo, in vitro and in situ studies. RT-PCR and Western blot were used to assess the expression of PEPT1 in rat intestine and Caco-2 cells. JBP485 caused a significant decrease in MDA and MPO levels, and improved the pathological condition of rat intestine, while attenuating Caco-2 cells damage induced by indomethacin. Uptake of Gly-Sar by PEPT1 was decreased by indomethacin treatment, whereas the Gly-Sar plasma concentration was markedly increased in JBP485 co-treated rats. Indomethacin down-regulated the expression of PEPT1 mRNA and protein in rat intestine and Caco-2 cells, and the effects were reversed after administration of JBP485. These results indicated that JBP485 not only improved intestinal injury and cell damage but also partially blocked the down-regulation of PEPT1 expression and function induced by indomethacin.