Digestive Diseases and Sciences

, Volume 58, Issue 1, pp 77–87

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

  • Xuexuan Wang
  • Mary Carmen Valenzano
  • Joanna M. Mercado
  • E. Peter Zurbach
  • James M. Mullin
Original Article

DOI: 10.1007/s10620-012-2328-8

Cite this article as:
Wang, X., Valenzano, M.C., Mercado, J.M. et al. Dig Dis Sci (2013) 58: 77. doi:10.1007/s10620-012-2328-8

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

ZincCACO-2Tight junctionClaudinsParacellularNutritionClaudinDifferentiationMetallothionein

Abbreviations

TJ

Tight junction

PD

Potential difference

Iscc

Short circuit current

Rt

Transepithelial electrical resistance

MT 1/2

Metallothionein 1/2

GI

Gastrointestinal

FBS

Fetal bovine serum

PBS

Phosphate buffered saline

RDA

Recommended daily allowance

SEM

Standard error of the mean

LDH

Lactate dehydrogenase

XTT

Tetrazolium dye, sodium 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl-5-[(phenylamino)-carbonyl]-2H-tetrazolium)

LSC

Liquid scintillation counting

PEG

Polyethyleneglycol

Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Xuexuan Wang
    • 1
  • Mary Carmen Valenzano
    • 1
  • Joanna M. Mercado
    • 1
  • E. Peter Zurbach
    • 2
  • James M. Mullin
    • 1
    • 3
  1. 1.Lankenau Institute for Medical ResearchWynnewoodUSA
  2. 2.Department of ChemistrySaint Joseph’s UniversityPhiladelphiaUSA
  3. 3.Division of GastroenterologyLankenau Medical CenterWynnewoodUSA