The Flavonol Quercetin Improves Endometrial Barrier Function through the Expression of Tight Junction Proteins

Abstract

Quercetin, the most abundant dietary flavonoid, shows the promotive and protective effects on intestinal tight junction (TJ) barrier function; however, little has been known about its effects in endometrium. The present study aims to investigate the potential effect of quercetin on endometrial TJ barrier function using the immortalized porcine glandular endometrial epithelial cell culture. The TJ barrier function was determined by transepithelial electrical resistance (TER) and fluorescein isothiocyanate‐dextran flux (FD‐4 and FD‐40) across the monolayer. The mRNA expression of TJ proteins, claudin‐2, ‐4, ‐5 and cytoskeletal zona occludens‐1 (ZO‐1) was evaluated by real‐time reverse transcription‐polymerase chain reaction. Quercetin (1, 10 and 100 μM) showed a concentration‐dependent increase in TER with markedly observed in the first 1–2 h. However, treatment with quercetin for 48 h had no significant change in the TER but a markedly decrease in FD4 and FD40 fluxes. Treatment with quercetin (10 μM) for 48 h also increased claudin‐2, ‐4 ‐5 and ZO‐1 mRNA whereas higher concentration only increased the ZO‐1 expression. Thus the increased claudin‐4, ‐5 and ZO‐1 appeared to promote the TJ assembly leading to decreased paracellular permeability. The present results indicate the promotive effects of quercetin on endometrial barrier function and possibly innate immune defense protecting against invading pathogens.Support or Funding InformationThis work was supported by Srinakharinwirot University Research Grant.