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Anti-inflammatory effect of chlorogenic acid in intestinal
epithelial cells
SHIN, Hee Soon (Korea Food Research Institute)
Chapter 1 Anti-inflammatory effect of chlorogenic aicd in vitro and in vivo
Section 1-1 Synergistic effect of tumor necrosis factor-alpha and hydrogen peroxide
on the induction of IL-8 production in human intestinal Caco-2 cells
Oxidative stress and inflammatory cytokines such as TNF- are thought to be involved in
mucosal inflammation. The intestinal epithelium may be concurrently stimulated by both
oxidative stress and inflammatory cytokines during the inflammation process in the intestines.
However, experimental models for intestinal inflammation still employ single stimulation, either
by an oxidative stress or inflammatory cytokine.
We therefore examined an in vitro
inflammation study using human intestinal epithelial Caco-2 cells, in which the cells were
stimulated both by hydrogen peroxide and TNF- and measured the IL-8 production as an
index of inflammation. The IL-8 production (secretion, mRNA expression, and transcriptional
activity) induced by both TNF- and H2O2 was significantly higher than that by single
stimulation. The synergistic effect of TNF- and H2O2 on the NF-B signaling pathway
(transcriptional activity and p65 nuclear translocation) was also observed. Oxidative stress and
TNF- may cooperatively enhance IL-8 production via NF-B in Caco-2 cells.
Section 1-2 Anti-inflammatory effects of chlorogenic acid and caffeic acid on the IL-8
production induced by combined stimuli of both tumor necrosis factor-alpha and
hydrogen peroxide in human intestinal Caco-2 cells and on the dextran sulfate
sodium-induced colitis in mice
Pro-inflammatory cytokines and oxidative stress have been shown to play a pivotal role in
the onset of inflammatory bowel diseases (IBDs).
We evaluated the effect of dietary
polyphenol, chlorogenic acid (CHA) and its metabolites caffeic acid (CA) and quinic acid (QA),
on the IL-8 production induced by combined stimuli of both tumor necrosis factor alpha
(TNF-) and hydrogen peroxide (H2O2) in human intestinal Caco-2 cells.
As a result, CHA
and its metabolite CA, but not QA, inhibited IL-8 production (secretion, mRNA expression, and
transcriptional activity) induced by TNF- and H2O2.
We also examined the effects of CHA
and CA on the dextran sulfate sodium (DSS)-induced colitis in mice. Female C57BL/6 mice
were treated as oral administration with 1mM (354 mg/kg diet, 3.54 mg/kg BW) CHA and 1mM
(180 mg/kg diet, 1.8 mg/kg BW) CA for 15 days, and given 3% DSS in drinking water during
for last 8 days to induce colitis.
Dietary CHA and CA attenuated DSS-induced body weight
loss, diarrhea, fetal bleeding, and shortening of the colon, and dramatically improved colitis
histological scores.
Further, DSS-induced increases in colonic MIP-2 and IL-1 mRNA
expression were significantly suppressed by CHA and CA supplementation. In conclusion, the
present study showed that dietary CHA and CA, its metabolite, inhibited both TNF- and
H2O2-induced IL-8 production in vitro, and attenuated DSS-induced colitis in vivo. These
indicate that CHA and CA can be important anti-inflammatory factors, and use of them may
lead to prevention of intestinal inflammation like IBDs.
Chapter 2 Anti-inflammatory mechanism of chlorogenic acid and caffeic acid in
intestinal epithelial cells
Section 2-1 Anti-inflammatory mechanism of chlorogenic acid and caffeic acid on the
hydrogen peroxide-induced IL-8 production through scavenging intracellular reactive
oxygen species (ROS) generation in human intestinal Caco-2 cells
Reactive oxygen species (ROS) generation induced by oxidative stress leads to serious
cellular injuries and the pathogenesis of several diseases.
In intestinal epithelial cells,
hydrogen peroxide (H2O2) induces the interleukine-8 (IL-8), pro-inflammatory cytokine, which
plays a key role in the pathogenesis of inflammatory bowel diseases (IBDs), encompassing
Crohn`s disease and ulcerative colitis.
Chlorogenic acid (CHA) its metabolite caffeic acid
(CA), antioxidants, often are exposed and absorbed in intestinal epithelial cells. We therefore
investigated the effects of CHA and CA on the H2O2-induced IL-8 production in human
intestinal epithelial Caco-2 cells.
CHA and CA inhibited the IL-8 transcriptional activity
induced by H2O2. They also significantly suppressed NF-B transcriptional activity, nuclear
translocation of p65 subunit, and phosphorylations of IB Kinase and protein kinase D,
up-stream signaling pathway of IL-8 production, induced by H2O2.
Also, we examined
intracellular ROS generation, and we found that CHA and CA scavenged H2O2-induced
intracellular ROS generation. We suggest that the anti-inflammatory effects of CHA and CA
were caused by scavenging capacity against H2O2-induced intracellular ROS generation in
human intestinal epithelial cells.
Section 2-2 Anti-inflammatory effect of chlorogenic acid and caffeic acid derivatives
on the hydrogen peroxide-induced IL-8 production in human intestinal Caco-2 cells:
Structure-activity relationships
The antioxidant activity of phenolic compounds has attracted much attention in relation to
their physiological functions such as prevention of coronary heart disease, cancer and
inflammation.
Our results showed that CHA and CA, phenolic compounds, inhibited
H2O2-induced IL-8 production through scavenging intracellular ROS generation. These results
mean that the anti-inflammatory effects of CHA and CA may be derived from their
anti-oxidative effects.
Generally, the radical scavenging activity of phenolic compounds has
been known to depend on their molecular structure. We investigated the functional moieties of
anti-inflammatory effects of CHA and CA using CA derivatives by structure-activity
relationships. We found that anti-inflammatory effects of CHA and CA depended on catechol
group through comparing phenolic compounds containing catechol group with them of
non-containing catechol group.
And also, the forces of inhibitory effect on the IL-8 production
were sequentially presented DCA ≦ CHA < CA < PCA.
We therefore suggest that although
the anti-inflammatory activities of phenolic acids did not completely conform to the role of
anti-oxidative activities, the capacities may be related lipid anti-oxidative activities, and CHA,
CA, PCA and DCA, phenolic acids containing catechol group, can act as anti-inflammatory
agents by inhibiting IL-8 production in human intestinal epithelial cells.
＜in vitro study＞
IL-8
Chlorogenic
acid
＜in vivo study＞
Oxidative stress
TNF-
DSS誘導大腸炎マウスモデル
membrane
cytosol
OH
O
P
HO
P
IKK
OH
β
α
P
O
C
HO
HC
OH
CH
O
OH
Chlorogenic acid
NFB
OH
O
P
C
P
HO
Chlorogenic acid
OH
O
C
HO
nuclear
C/EBP
AP-1
HC
CH
OH
O
OH
p50
P
p65
P
IL-8
S
DS
PKD
Catechol group
C
IL-8 mRNA
P
ROS
3％
P
IB
IL-1
mRNA
NFB
＜腸管におけるクロロゲン酸の抗炎症作用＞
inflammation
MIP-2
mRNA