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Cytokine. 2019 Mar;115:64-75. doi: 10.1016/j.cyto.2018.12.009. Epub 2019 Jan 11.

Tea polyphenols protect gingival keratinocytes against TNF-α-induced tight junction barrier dysfunction and attenuate the inflammatory response of monocytes/macrophages.

Author information

1
Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, QC, Canada.
2
Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, QC, Canada. Electronic address: Daniel.Grenier@greb.ulaval.ca.

Abstract

Tea, an aromatic beverage prepared with the leaves of the Camellia sinensis plant, is well known to contain bioactive polyphenols. Green tea contains mainly catechins such as epigallocatechin-3-gallate (EGCG), while black tea is characterized by the presence of theaflavins. TNF-α, which is a pro-inflammatory cytokine that activates the endogenous inflammatory cascade, plays a key role in periodontitis. In the present study, we investigated the ability of tea compounds to attenuate TNF-α-mediated activation of the host inflammatory response in monocytes/macrophages as well as the protective effect of green and black tea polyphenols on gingival keratinocyte barrier dysfunction induced by TNF-α. Tea compounds inhibited both the activation of NF-κB and caspase-1 as well as IL-1β secretion by monocytes/macrophages. TNF-α time-dependently damaged keratinocyte tight junction barrier integrity, as determined by changes in transepithelial electrical resistance and FITC-dextran transport. Green tea extract, EGCG, theaflavins, and to a lesser extent, black tea extract protected keratinocytes against the TNF-α-mediated breakdown of barrier integrity. The treatment of keratinocytes with tea polyphenols markedly mitigated the morphological changes of tight junction proteins such as zonula occludens-1 and occludin compared to cells exposed only to TNF-α, as determined by immunofluorescence. Tea polyphenols also time-dependently decreased the paracellular flux of TNF-α-treated keratinocytes. In conclusion, the ability of tea polyphenols to exert an anti-inflammatory effect and to attenuate the gingival epithelial barrier dysfunction induced by TNF-α supports their potential for the prevention and treatment of periodontal disease.

KEYWORDS:

Epithelial barrier; Keratinocytes; Macrophages; Periodontal disease; TNF-α

PMID:
30640129
DOI:
10.1016/j.cyto.2018.12.009

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