Gut Liver.  2018 Nov;12(6):682-693. 10.5009/gnl18221.

Effects of 17β-Estradiol on Colonic Permeability and Inflammation in an Azoxymethane/Dextran Sulfate Sodium-Induced Colitis Mouse Model

• Song CH
• Kim N
• Sohn SH
• Lee SM
• Nam RH
• Na HY
• Lee DH
• Surh YJ

• KMID: 2427459
• DOI: http://doi.org/10.5009/gnl18221

Abstract

BACKGROUND/AIMS
Intestinal barrier dysfunction is a hallmark of inflammatory bowel diseases (IBDs) such as ulcerative colitis. This dysfunction is caused by increased permeability and the loss of tight junctions in intestinal epithelial cells. The aim of this study was to investigate whether estradiol treatment reduces colonic permeability, tight junction disruption, and inflammation in an azoxymethane (AOM)/dextran sodium sulfate (DSS) colon cancer mouse model.
METHODS
The effects of 17β-estradiol (E2) were evaluated in ICR male mice 4 weeks after AOM/DSS treatment. Histological damage was scored by hematoxylin and eosin staining and the levels of the colonic mucosal cytokine myeloperoxidase (MPO) were assessed by enzyme-linked immunosorbent assay (ELISA). To evaluate the effects of E2 on intestinal permeability, tight junctions, and inflammation, we performed quantitative real-time polymerase chain reaction and Western blot analysis. Furthermore, the expression levels of mucin 2 (MUC2) and mucin 4 (MUC4) were measured as target genes for intestinal permeability, whereas zonula occludens 1 (ZO-1), occludin (OCLN), and claudin 4 (CLDN4) served as target genes for the tight junctions.
RESULTS
The colitis-mediated induced damage score and MPO activity were reduced by E2 treatment (p < 0.05). In addition, the mRNA expression levels of intestinal barrier-related molecules (i.e., MUC2, ZO-1, OCLN, and CLDN4) were decreased by AOM/DSS-treatment; furthermore, this inhibition was rescued by E2 supplementation. The mRNA and protein expression of inflammation-related genes (i.e., KLF4, NF-κB, iNOS, and COX-2) was increased by AOM/DSS-treatment and ameliorated by E2.
CONCLUSIONS
E2 acts through the estrogen receptor β signaling pathway to elicit anti-inflammatory effects on intestinal barrier by inducing the expression of MUC2 and tight junction molecules and inhibiting pro-inflammatory cytokines.

Keyword

AOM/DSS colitis mouse model; Permeability; Tight junction; Inflammation; Estrogen

MeSH Terms

Animals
Azoxymethane
Blotting, Western
Claudin-4
Colitis*
Colitis, Ulcerative
Colon*
Colonic Neoplasms
Cytokines
Enzyme-Linked Immunosorbent Assay
Eosine Yellowish-(YS)
Epithelial Cells
Estradiol
Estrogens
Hematoxylin
Humans
Inflammation*
Inflammatory Bowel Diseases
Male
Mice*
Mucin-2
Mucin-4
Occludin
Permeability*
Peroxidase
Real-Time Polymerase Chain Reaction
RNA, Messenger
Sodium
Tight Junctions
Azoxymethane
Claudin-4
Cytokines
Eosine Yellowish-(YS)
Estradiol
Estrogens
Hematoxylin
Mucin-2
Mucin-4
Occludin
Peroxidase
RNA, Messenger
Sodium