Alpha-Melanocyte Stimulating Hormone Protects against Cytokine-Induced Barrier Damage in Caco-2 Intestinal Epithelial Monolayers

PLoS One. 2017 Jan 19;12(1):e0170537. doi: 10.1371/journal.pone.0170537. eCollection 2017.

Abstract

Alpha-melanocyte-stimulating hormone (α-MSH) is a potent anti-inflammatory peptide with cytoprotective effect in various tissues. The present investigation demonstrates the ability of α-MSH to interact with intestinal epithelial cell monolayers and mitigate inflammatory processes of the epithelial barrier. The protective effect of α-MSH was studied on Caco-2 human intestinal epithelial monolayers, which were disrupted by exposure to tumor necrosis factor-α and interleukin-1β. The barrier integrity was assessed by measuring transepithelial electric resistance (TEER) and permeability for marker molecules. Caco-2 monolayers were evaluated by immunohistochemistry for expression of melanocortin-1 receptor and tight junction proteins ZO-1 and claudin-4. The activation of nuclear factor kappa beta (NF-κB) was detected by fluorescence microscopy and inflammatory cytokine expression was assessed by flow cytometric bead array cytokine assay. Exposure of Caco-2 monolayers to proinflammatory cytokines lowered TEER and increased permeability for fluorescein and albumin, which was accompanied by changes in ZO-1 and claudin-4 immunostaining. α-MSH was able to prevent inflammation-associated decrease of TEER in a dose-dependent manner and reduce the increased permeability for paracellular marker fluorescein. Further immunohistochemistry analysis revealed proinflammatory cytokine induced translocation of the NF-κB p65 subunit into Caco-2 cell nuclei, which was inhibited by α-MSH. As a result the IL-6 and IL-8 production of Caco-2 monolayers were also decreased with different patterns by the addition of α-MSH to the culture medium. In conclusion, Caco-2 cells showed a positive immunostaining for melanocortin-1 receptor and α-MSH protected Caco-2 cells against inflammatory barrier dysfunction and inflammatory activation induced by tumor necrosis factor-α and interleukin-1β cytokines.

MeSH terms

  • Caco-2 Cells
  • Claudin-4 / metabolism
  • Cytoprotection / drug effects
  • Electric Impedance
  • Humans
  • Inflammation / prevention & control
  • Interleukin-1beta / administration & dosage
  • Interleukin-6 / metabolism
  • Interleukin-8 / metabolism
  • Intestinal Mucosa / drug effects*
  • Intestinal Mucosa / injuries*
  • Intestinal Mucosa / metabolism
  • NF-kappa B / metabolism
  • Permeability / drug effects
  • Receptor, Melanocortin, Type 1 / metabolism
  • Tumor Necrosis Factor-alpha / administration & dosage
  • Zonula Occludens-1 Protein / metabolism
  • alpha-MSH / pharmacology*

Substances

  • CLDN4 protein, human
  • CXCL8 protein, human
  • Claudin-4
  • IL6 protein, human
  • Interleukin-1beta
  • Interleukin-6
  • Interleukin-8
  • NF-kappa B
  • Receptor, Melanocortin, Type 1
  • TJP1 protein, human
  • Tumor Necrosis Factor-alpha
  • Zonula Occludens-1 Protein
  • alpha-MSH

Grants and funding

FF was supported by János Bólyai Research Scolarship of the Hungarian Academy of Sciences (BO/00290/16/5). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.