Eicosapentaenoic acid enhances heat stress-impaired intestinal epithelial barrier function in Caco-2 cells.
OBJECTIVE
Dysfunction of the intestinal epithelial tight junction (TJ) barrier is known to have an important etiologic role in the pathophysiology of heat stroke. N-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), play a role in maintaining and protecting the TJ structure and function. This study is aimed at investigating whether n-3 PUFAs could alleviate heat stress-induced dysfunction of intestinal tight junction.


METHODS
Human intestinal epithelial Caco-2 cells were pre-incubated with EPA, DHA or arachidonic acid (AA) and then exposed to heat stress. Transepithelial electrical resistance (TEER) and Horseradish Peroxidase (HRP) permeability were measured to analyze barrier integrity. Levels of TJ proteins, including occludin, ZO-1 and claudin-2, were analyzed by Western blot and localized by immunofluorescence microscopy. Messenger RNA levels were determined by quantitative real time polymerase chain reaction (Q-PCR). TJ morphology was observed by transmission electron microscopy.


RESULTS
EPA effectively attenuated the decrease in TEER and impairment of intestinal permeability in HRP flux induced by heat exposure. EPA significantly elevated the expression of occludin and ZO-1, while DHA was less effective and AA was not at all effective. The distortion and redistribution of TJ proteins, and disruption of morphology were also effectively prevented by pretreatment with EPA.


CONCLUSIONS
This study indicates for the first time that EPA is more potent than DHA in protecting against heat-induced permeability dysfunction and epithelial barrier damage of tight junction.
Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Guizhen
G
Xiao
Liqun
L
Tang
Fangfang
F
Yuan
Wei
W
Zhu
Shaoheng
S
Zhang
Zhifeng
Z
Liu
Yan
Y
Geng
Xiaowen
X
Qiu
Yali
Y
Zhang
Lei
L
Su
D016718:Arachidonic Acid / Q000494:pharmacology; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects; D004281:Docosahexaenoic Acids / Q000494:pharmacology; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D006735:Horseradish Peroxidase / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007422:Intestines / Q000187:drug effects*; D046529:Microscopy, Electron, Transmission; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism
D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D015118:Eicosapentaenoic Acid; D006735:Horseradish Peroxidase