KPV tripeptide reduces intestinal inflammation via PepT1 transporter in colitis models
Background
Inflammatory bowel disease (IBD) involves dysregulated mucosal immune signaling that current therapies incompletely control, leaving many patients without adequate remission. The tripeptide KPV (Lys-Pro-Val) carries known anti-inflammatory properties, yet its cellular mechanism of action had not been established. PepT1, a di/tripeptide transporter ordinarily confined to the small intestine, is upregulated in colonic epithelium during active IBD — a feature that creates a disease-specific uptake route. Understanding whether KPV's effects depend on PepT1-mediated intracellular entry could explain its potency and inform targeted delivery strategies for colitis.
Study Design
Human intestinal epithelial lines Caco2-BBE and HT29-Cl.19A, plus human Jurkat T cells, were stimulated with pro-inflammatory cytokines with or without KPV. Anti-inflammatory endpoints included a NF-κB luciferase reporter, Western blot, real-time RT-PCR, and ELISA for cytokine secretion. Uptake kinetics were measured using cold KPV as a competitor for a PepT1 radiolabelled substrate and with [³H]KPV directly. In vivo, KPV was added to drinking water in DSS- and TNBS-induced mouse colitis models; inflammation was assessed histologically and by proinflammatory cytokine mRNA expression.
Results
Nanomolar concentrations of KPV suppressed activation of the NF-κB and MAP kinase inflammatory signaling pathways in intestinal epithelial and T cells. KPV also reduced pro-inflammatory cytokine secretion as measured by ELISA. Uptake competition and [³H]KPV kinetic experiments confirmed that KPV enters cells through PepT1 expressed on both intestinal epithelial and immune cells. Oral KPV administration decreased the incidence of both DSS- and TNBS-induced colitis in mice, evidenced by reduced histologic inflammation scores and lower proinflammatory cytokine mRNA expression.
Nanomolar KPV concentrations were sufficient to inhibit NF-κB and MAP kinase pathway activation, with anti-inflammatory efficacy confirmed across two independent mouse colitis models via PepT1-mediated uptake.
Key Findings
- Nanomolar KPV concentrations inhibit NF-κB and MAP kinase inflammatory signaling pathways
- KPV uptake into intestinal epithelial and immune cells is mediated by the PepT1 transporter
- Oral KPV in drinking water reduced DSS-induced colitis incidence in mice
- Oral KPV in drinking water reduced TNBS-induced colitis incidence in mice
- PepT1 is expressed in both intestinal epithelial cells and immune (Jurkat T) cells
Why It Matters
KPV's activity at nanomolar concentrations via an endogenous transporter (PepT1) that is upregulated specifically during intestinal inflammation creates a self-amplifying targeting mechanism — diseased tissue concentrates the peptide precisely where it is needed. Clinicians and researchers studying IBD interventions should note the oral-route feasibility already demonstrated in mice, lowering the translational barrier compared with injectable biologics. For those tracking peptide stacks, the PepT1 dependence means that co-administration of other di/tripeptide substrates could create competition at the transporter and potentially reduce KPV bioavailability. Full dose-ranging, pharmacokinetic, and safety profiling in humans remains absent, so clinical protocols cannot yet be defined.
