The role and pathophysiological relevance of membrane transporter PepT1 in intestinal inflammation and inflammatory bowel disease

Am J Physiol Gastrointest Liver Physiol. 2012 Mar 1;302(5):G484-92. doi: 10.1152/ajpgi.00477.2011. Epub 2011 Dec 22.

Abstract

Intestinal inflammation is characterized by epithelial disruption, leading to loss of barrier function and the recruitment of immune cells, including neutrophils. Although the mechanisms are not yet completely understood, interactions between environmental and immunological factors are thought to be critical in the initiation and progression of intestinal inflammation. In recent years, it has become apparent that the di/tripeptide transporter PepT1 may play an important role in the pathogenesis of such inflammation. In healthy individuals, PepT1 is primarily expressed in the small intestine and transports di/tripeptides for metabolic purposes. However, during chronic inflammation such as that associated with inflammatory bowel disease, PepT1 expression is upregulated in the colon, wherein the protein is normally expressed either minimally or not at all. Several recent studies have shown that PepT1 binds to and transports various bacterial di/tripeptides into colon cells, leading to activation of downstream proinflammatory responses via peptide interactions with innate immune receptors. In the present review, we examine the relationship between colonic PepT1-mediated peptide transport in the colon and activation of innate immune responses during disease. It is important to understand the mechanisms of PepT1 action during chronic intestinal inflammation to develop future therapies addressing inappropriate immune activation in the colon.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Animals
  • Colorectal Neoplasms / physiopathology
  • Gastroenteritis / drug therapy
  • Gastroenteritis / etiology*
  • Humans
  • Inflammatory Bowel Diseases / etiology*
  • Inflammatory Bowel Diseases / genetics
  • Inflammatory Bowel Diseases / physiopathology
  • Nod Signaling Adaptor Proteins / physiology
  • Oligopeptides / metabolism
  • Peptide Transporter 1
  • Symporters / genetics
  • Symporters / physiology*

Substances

  • Nod Signaling Adaptor Proteins
  • Oligopeptides
  • Peptide Transporter 1
  • SLC15A1 protein, human
  • Symporters