PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation.
OBJECTIVE
KPV is a tripeptide (Lys-Pro-Val), which possesses anti-inflammatory properties; however, its mechanisms of action still remain unknown. PepT1 is a di/tripeptide transporter normally expressed in the small intestine and induced in colon during inflammatory bowel disease (IBD). The aim of this study was to 1) investigate whether the KPV anti-inflammatory effect is PepT1-mediated in intestinal epithelian and immune cells, and 2) examine the anti-inflammatory effects in two models of mice colitis.


METHODS
Human intestinal epithelial cells Caco2-BBE, HT29-Cl.19A, and human T cells (Jurkat) were stimulated with pro-inflammatory cytokines in the present or absence of KPV. KPV anti-inflammatory effect was assessed using a NF-kappaB luciferase gene reporter, Western blot, real-time RT-PCR and ELISA. Uptake experiments were performed using cold KPV as a competitor for PepT1 radiolabelled substrate or using [(3)H]KPV to determine kinetic characteristics of KPV uptake. Anti-inflammatory effect of KPV was also investigated in DSS- and TNBS-induced colitis in mice. KPV was added to drinking water and inflammation was assessed at the histologic level and by proinflammatory cytokine mRNA expression.


RESULTS
Nanomolar concentrations of KPV inhibit the activation of NF-kappaB and MAP kinase inflammatory signaling pathways, and reduce pro-inflammatory cytokine secretion. We found that KPV acts via PepT1 expressed in immune and intestinal epithelial cells. Furthermore, oral administration of KPV reduces the incidence of DSS- and TNBS-induced colitis indicated by a decrease in pro-inflammatory cytokine expression.


CONCLUSIONS
This study indicates tht KPV is transported into cells by PepT1 and might be a new therapeutic agent for IBD.
Department of Medicine, Division of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia, USA.
Guillaume
G
Dalmasso
Laetitia
L
Charrier-Hisamuddin
Hang Thi Thu
HT
Nguyen
Yutao
Y
Yan
Shanthi
S
Sitaraman
Didier
D
Merlin
D000818:Animals; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D018925:Chemokines / Q000378:metabolism; D003092:Colitis / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000187:drug effects; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009074:Melanocyte-Stimulating Hormones / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D000074011:Peptide Transporter 1; D027981:Symporters / Q000378:metabolism*
D018925:Chemokines; D010446:Peptide Fragments; D000074011:Peptide Transporter 1; C489941:Slc15a1 protein, mouse; D027981:Symporters; C043156:MSH (11-13); D009074:Melanocyte-Stimulating Hormones