Interferon-γ increases expression of the di/tri-peptide transporter, h-PEPT1, and dipeptide transport in cultured human intestinal monolayers

David R. Foster, Christopher P. Landowski, Xiaomei Zheng, Gordon L. Amidon, Lynda S Welage

Research output: Contribution to journalArticlepeer-review


The di/tri-peptide transporter h-PEPT1 plays an important role in the oral absorption of di/tri-peptides and numerous drugs. Inflammatory conditions may influence intestinal xenobiotic transporter function; however, the effects of inflammation on h-PEPT1 have not been well described. This study was conducted to determine the effects of the inflammatory cytokine interferon-γ (IFN-γ) on h-PEPT1 mediated dipeptide absorption. Caco-2 monolayers were grown on permeable supports. The effective apical-to-basolateral permeability (Peff) of glycylsarcosine (Gly-Sar) was measured following incubation with IFN-γ or control media. Additional experiments were conducted at 4 °C, and with escalating concentrations of Gly-Sar. h-PEPT1 expression was determined using semiquantitative RT-PCR. IFN-γ 50 ng/ml increased Gly-Sar Peff 28.6% compared to controls (p = 0.03). In experiments conducted at 4 °C, Gly-Sar Peff decreased 39.6% in IFN-γ treated cells (p = 0.003) and 28.4% in controls (p = 0.006). In controls and IFN-γ treated cells, concentration dependent transport was seen with escalating concentrations of Gly-Sar. Compared to controls, IFN-γ 50 and 100 ng/ml increased h-PEPT1 mRNA expression by 14.2% and 11.5%, respectively (p = 0.019). In summary, IFN-γ increases h-PEPT1 expression and permeation of the dipeptide Gly-Sar in Caco-2 monolayers. These findings imply that intestinal absorption of peptides and peptidomimetic drugs may be increased in certain inflammatory conditions.

Original languageEnglish (US)
Pages (from-to)215-220
Number of pages6
JournalPharmacological Research
Issue number3
StatePublished - Mar 2009
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported in part by the University of Michigan College of Pharmacy and NIH/NIGMS 5 R01 GM37188.


  • Caco-2 cells
  • h-PEPT1
  • Interferon-γ

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