Myofibroblast keratinocyte growth factor reduces tight junctional integrity and increases claudin-2 levels in polarized Caco-2 cells

Abstract

The colonic epithelium is composed of a polarized monolayer sheathed by a layer of pericryptal myofibroblasts (PCMFs). We mimicked these cellular compartments in vitro to assess the effects of paracrine-acting PCMF-derived factors on tight junction (TJ) integrity, as measured by transepithelial electrical resistance (TER). Coculture with 18Co PCMFs, or basolateral administration of 18Co conditioned medium, significantly reduced TER of polarized Caco-2 cells. Among candidate paracrine factors, only keratinocyte growth factor (KGF) reduced Caco-2 TER; basolateral KGF treatment led to time- and concentration-dependent increases in claudin-2 levels. We also demonstrate that amphiregulin (AREG), produced largely by Caco-2 cells, increased claudin-2 levels, leading to epidermal growth factor receptor-mediated TER reduction. We propose that colonic epithelial TJ integrity can be modulated by paracrine KGF and autocrine AREG through increased claudin-2 levels. KGF-regulated claudin-2 induction may have implications for inflammatory bowel disease, where both KGF and claudin-2 are upregulated.

Keywords::

• Tight junction
• pericryptal myofibroblasts
• keratinocyte growth factor
• amphiregulin
• claudin-2

Acknowledgements

This work was supported by the National Cancer Institute CA151566 and CA46413, Gastrointestinal Specialized Program of Research Excellence P50CA095103 to R.J.C., and T32GM008554 to E.J.P. Cell imaging was carried out in part through the VUMC Cell Imaging Shared Resource (supported by NIH grant CA68485, DK20593, DK58404, HD15052, DK59637, and EY08126).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.