ESPEN 2013 - Late breaking abstract submission
Late Breaking Abstract
ESPEN13-1830
INFLUENCE OF LIPOPOLYSACCHARIDES ON THE EXPRESSION OF HUMAN PEPTIDE TRANSPORTER (PEPT1) IN INTESTINAL CACO-2 CELL MONOLAYERS
T. Shiraga 1,*Y. Inoue 1
1Department of Foods and Human Nutrition, Faculty of Human Life Sciences, NOTRE DAME SEISHIN UNIVERSITY, Okayama, Japan
Rationale: The intestinal oligopeptide transporter, PEPT1, is upregulated both in the distal colon in patients with inflammatory bowel disease (IBD); it is also upregulated in the distal colon and downregulated in the distal small intestine in colitis rats. Although the detailed mechanism regulating these effects remains unclear, it was reported that one transcription factor, Nuclear Factor-kappa B (NF-κB), is activated in the intestinal tissue of patients, suggesting the possibility that this activated signal is associated with the onset of IBD. Therefore, the aim of this study was to investigate the influence of lipopolysaccharides (LPS), which are known NF-κB activators, on human PEPT1 expression in intestinal Caco-2 cell monolayers.
Methods: Caco-2 cells were cultured on 6-well Transwell permeable membranes for two weeks. LPS was then added in the culture medium on the apical or basolateral side of the cell monolayer at 100 ng/ml, and the cells were further incubated for 24 or 48 h. For NF-kB inhibition studies, the cells were pretreated with 10μM BAY-11 1 h before the addition of LPS. The expression levels of human PEPT1 were evaluated by real-time RT-PCR and Western blot analyses.
Results: Although no changes were observed in mRNA levels, PEPT1 protein levels were significantly decreased by the addition of LPS to the basolateral side of Caco-2 cell monolayers for 48 h. Furthermore, PEPT1 protein levels were restored by pre-treatment with basolateral BAY-11.
Conclusion: These findings suggest that PEPT1 protein expression specifically responds to LPS stimuli from the basolateral membrane. This effect may be due to a reduction in protein synthesis and/or an increase in proteolysis downstream of NF-κB signaling. Further study is required to elucidate the regulatory mechanisms controlling PEPT1 expression in greater detail.
Disclosure of Interest: None Declared
Keywords: LIPOPOLYSACCHARIDESPEPT1