GLP-2 enhances barrier formation and attenuates TNFα-induced changes in a Caco-2 cell model of the intestinal barrier.

Abstract

INTRODUCTION:

Tight junctions are intercellular permeability seals that regulate paracellular transport across epithelia. Tight junction function, expression and localisation of constituent proteins are significantly altered by cytokines such as TNFα. Glucagon-like peptide-2 (GLP-2) is an intestinotrophic enteroendocrine peptide. It is not known whether GLP-2 regulates the barrier or tight junctions. The aim of this study was to investigate whether GLP-2 has an effect on tight junction function or protein expression, alone or in response to TNFα exposure.

METHODS:

Caco-2 cells were grown to confluence on filters in the presence or absence of GLP-2. The time course of transepithelial electrical resistance developing across the monolayer was measured; tight junction protein expression was quantified by immunoblotting. At day 20, TNFα in the presence or absence of GLP-2 was added. Changes in TEER and tight junction proteins expression were quantified. Both TNFα and GLP-2 were added on the basolateral side.

RESULTS:

GLP-2 exposed Caco-2 cell monolayers showed a significant increase in transepithelial electrical resistance compared to that in untreated control cells. At the same time, expression of the tight junction proteins occludin and zona occludens-1 (ZO-1) was increased at day 17 post-seeding (1.6-fold; p=0.037 and 4.7 fold; p=0.039 respectively). Subsequent TNFα exposure induced a significant 9.3-fold (p<0.001) decrease in transepithelial electrical resistance and a corresponding reduction in the expression of ZO-1 (5.3 fold; p<0.01). However, the TNFα-induced reduction in transepithelial electrical resistance in GLP-2-exposed cells was highly attenuated to 1.8-fold (p<0.01). No change in tight junction protein expression was noted in GLP-2 exposed cells after cytokine exposure.

CONCLUSION:

GLP-2 enhances formation of the epithelial barrier and its constituent proteins in Caco-2 cells, and diminishes the effects of TNFα. If these effects are replicated in vivo the GLP-2 receptor may present a therapeutic target in intestinal inflammation.

• Authors: G W Moran, C O'Neill, J T McLaughlin
• Journal: Regulatory peptides (Regul Pept) Vol. 178 Issue 1-3 Pg. 95-101 (Oct 10 2012) ISSN: 1873-1686 [Electronic] Netherlands
• PMID: 22809889 (Publication Type: Journal Article)
• Copyright: Copyright © 2012 Elsevier B.V. All rights reserved.

Chemical References

• CLDN1 protein, human
• CLDN4 protein, human
• Claudin-1
• Claudin-4
• Glucagon-Like Peptide 2
• OCLN protein, human
• Occludin
• TJP1 protein, human
• Tumor Necrosis Factor-alpha
• Zonula Occludens-1 Protein

Topics

• Caco-2 Cells
• Claudin-1 (metabolism)
• Claudin-4 (metabolism)
• Electric Impedance
• Glucagon-Like Peptide 2 (metabolism, physiology)
• Humans
• Intestinal Mucosa (cytology, metabolism, physiology)
• Occludin (metabolism)
• Tight Junctions (metabolism, physiology)
• Tumor Necrosis Factor-alpha (physiology)
• Zonula Occludens-1 Protein (metabolism)