Wogonin suppresses inflammatory response and maintains intestinal barrier function via TLR4-MyD88-TAK1-mediated NF-κB pathway in vitro.
OBJECTIVE
Wogonin has multiple pharmacological effects, including anti-inflammatory effects. Here, we hypothesize that wogonin can protect intestinal barrier function in lipopolysaccharide (LPS)-induced Caco-2 cells, which is an in vitro model of intestinal inflammation.


METHODS
We measured intestinal barrier function in LPS-induced Caco-2 cells by using transepithelial electrical resistance (TEER) and transport of fluorescent markers. A quantitative (q) RT-PCR and immunofluorescent staining analysis was used to detect the expression of tight junction proteins (claudin-1 and ZO-1) in LPS-induced Caco-2 cells. We measured inflammatory molecules in LPS-induced Caco-2 cells using ELISA and qRT-PCR. In addition, the expression of TLR4, MyD88 and TAK1 and their interaction, and NF-κB activity in LPS-induced Caco-2 cells were investigated by western blot analysis and immune-precipitation.


RESULTS
We found that exposing Caco-2 cells to wogonin (10 and 50 μM for 24 h) attenuated the LPS-induced changes in TEER and transport of fluorescent markers. In addition, wogonin suppressed LPS-induced down-regulation of tight junction proteins (claudin-1 and ZO-1). Furthermore, LPS-induced up-regulation of inflammatory mediators, including interleukin (IL)-1β, IL-6 and IL-8, cyclooxygenase-2 (COX-2), inducible nitric oxide synthases (iNOS) were reduced after being pre-treated with wogonin. Moreover, wogonin not only inhibited the expression of TLR4, MyD88 and TAK1 and the interaction between these molecules, but also reduced NF-κB translocation to nucleus and its DNA-binding activity in LPS-induced Caco-2 cells.


CONCLUSIONS
Our results suggested that pre-treatment with wogonin could attenuate the TLR4-mediated inflammatory response and maintain intestinal barrier function in LPS-induced Caco-2 cells, thus might be a potential therapy for treating IBD.
Department of Gastroenterology, The Affiliated Jiangyin Hospital of Southeast University Medical College, Jiangsu, 214400, People's Republic of China.
Wenping
W
Wang
Tingsong
T
Xia
Xinpu
X
Yu
D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001693:Biological Transport, Active / Q000187:drug effects; D018938:Caco-2 Cells; D062445:Claudin-1 / Q000096:biosynthesis / Q000235:genetics; D017097:Electric Impedance; D044950:Flavanones / Q000494:pharmacology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007378:Interleukins / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D020930:MAP Kinase Kinase Kinases / Q000187:drug effects*; D053594:Myeloid Differentiation Factor 88 / Q000187:drug effects*; D016328:NF-kappa B / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D051197:Toll-Like Receptor 4 / Q000187:drug effects*; D000099151:MAP Kinase Kinase Kinase 7
D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D062445:Claudin-1; D044950:Flavanones; D018836:Inflammation Mediators; D007378:Interleukins; D020930:MAP Kinase Kinase Kinases; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D000099151:MAP Kinase Kinase Kinase 7; C507779:MYD88 protein, human; C495345:TLR4 protein, human; C085514:wogonin