QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Online Supporting Material Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Amasheh, M. Articles by Schulzke, J. D. Search for Related Content PubMed PubMed Citation Articles by Amasheh, M. Articles by Schulzke, J. D. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Medline Plus Health Information Antioxidants Hazardous Substances DB QUERCETIN

---

Nutrition and Disease

Quercetin Enhances Epithelial Barrier Function and Increases Claudin-4 Expression in Caco-2 Cells^1–3,

⁴ Department of Gastroenterology and ⁵ Institute of Clinical Physiology, Charité Campus Benjamin Franklin, 12200 Berlin, Germany

^* To whom correspondence should be addressed. E-mail: joerg.schulzke{at}charite.de.

Quercetin is the most abundant flavonoid and is assumed to have positive effects on the gastrointestinal mucosa after dietary intake. The aim of the study was to analyze the influence of quercetin on intestinal barrier function using the human colonic epithelial cell line Caco-2. Transepithelial resistance (R^t), tracer fluxes of [³H]-mannitol, ²²Na⁺, and ³⁶Cl^– as well as electrogenic ion transport were determined in Ussing chambers. Expression of tight junction (TJ) proteins and mRNA was analyzed in Western blots and quantitative RT-PCR, respectively. Regulation of transcription was analyzed by reporter gene assay. Cellular distribution of TJ proteins was examined by confocal laser scanning microscopy (LSM). Apoptotic rate was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. Quercetin induced a dose-dependent increase of R^t persisting for >2 d. Daily addition of quercetin was able to perpetuate the effect, which was seen whether quercetin was added apically or to the basolateral compartment. Parallel to the R^t increase, quercetin induced a strong increase of the TJ protein claudin-4 but not of other claudins. Confocal LSM showed a localization of claudin-4 in TJ. Apoptotic rate was not affected by quercetin. Consistent with these changes, fluxes of Na⁺ and Cl^–, but not of mannitol, were reduced. Reporter gene assays revealed a stimulatory effect of quercetin on claudin-4 transcription. The flavonoid quercetin enhances barrier function via transcriptional expression regulation of the TJ protein claudin-4, which represents an important protective effect of this food component against barrier disturbance in intestinal inflammation.

This article has been cited by other articles:

				T. Suzuki and H. Hara Quercetin Enhances Intestinal Barrier Function through the Assembly of Zonnula Occludens-2, Occludin, and Claudin-1 and the Expression of Claudin-4 in Caco-2 Cells J. Nutr., May 1, 2009; 139(5): 965 - 974. [Abstract] [Full Text] [PDF]