Original Article

Digestive Diseases and Sciences

, Volume 58, Issue 1, pp 77-87

First online:

Zinc Supplementation Modifies Tight Junctions and Alters Barrier Function of CACO-2 Human Intestinal Epithelial Layers

  • Xuexuan WangAffiliated withLankenau Institute for Medical Research
  • , Mary Carmen ValenzanoAffiliated withLankenau Institute for Medical Research
  • , Joanna M. MercadoAffiliated withLankenau Institute for Medical Research
  • , E. Peter ZurbachAffiliated withDepartment of Chemistry, Saint Joseph’s University
  • , James M. MullinAffiliated withLankenau Institute for Medical ResearchDivision of Gastroenterology, Lankenau Medical Center Email author 

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Abstract

Background

Zinc deficiency is known to result in epithelial barrier leak in the GI tract. Precise effects of zinc on epithelial tight junctions (TJs) are only beginning to be described and understood. Along with nutritional regimens like methionine-restriction and compounds such as berberine, quercetin, indole, glutamine and rapamycin, zinc has the potential to function as a TJ modifier and selective enhancer of epithelial barrier function.

Aims

The purpose of this study was to determine the effects of zinc-supplementation on the TJs of a well-studied in vitro GI model, CACO-2 cells.

Methods

Barrier function was assessed electrophysiologically by measuring transepithelial electrical resistance (Rt), and radiochemically, by measuring transepithelial (paracellular) diffusion of 14C-D-mannitol and 14C-polyethyleneglycol. TJ composition was studied by Western immunoblot analyses of occludin, tricellulin and claudins-1 to -5 and -7.

Results

Fifty- and 100-μM zinc concentrations (control medium is 2 μM) significantly increase Rt but simultaneously increase paracellular leak to D-mannitol. Claudins 2 and 7 are downregulated in total cell lysates, while occludin, tricellulin and claudins-1, -3, -4 and -5 are unchanged. Claudins-2 and -7 as well as tricellulin exhibit decreased cytosolic content as a result of zinc supplementation.

Conclusions

Zinc alters CACO-2 TJ composition and modifies TJ barrier function selectively. Zinc is one of a growing number of “nutraceutical” substances capable of enhancing epithelial barrier function, and may find use in countering TJ leakiness induced in various disease states.

Keywords

Zinc CACO-2 Tight junction Claudins Paracellular Nutrition Claudin Differentiation Metallothionein