Limits...
Fisetin inhibits hyperglycemia-induced proinflammatory cytokine production by epigenetic mechanisms.

Kim HJ, Kim SH, Yun JM - Evid Based Complement Alternat Med (2012)

Bottom Line: Fisetin, a flavonoid dietary ingredient found in the smoke tree (Cotinus coggygria), and is also widely distributed in fruits and vegetables.Fisetin is known to exert anti-inflammatory effects via inhibition of the NF-κB signaling pathway.These results suggest that fisetin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB.

View Article: PubMed Central - PubMed

Affiliation: Pharmacology Research Center, Korea Research Institute of Chemical Technology, Daejeon 305-600, Republic of Korea.

ABSTRACT
Diabetes is characterized by a proinflammatory state, and several inflammatory processes have been associated with both type 1 and type 2 diabetes and the resulting complications. High glucose levels induce the release of proinflammatory cytokines. Fisetin, a flavonoid dietary ingredient found in the smoke tree (Cotinus coggygria), and is also widely distributed in fruits and vegetables. Fisetin is known to exert anti-inflammatory effects via inhibition of the NF-κB signaling pathway. In this study, we analyzed the effects of fisetin on proinflammatory cytokine secretion and epigenetic regulation, in human monocytes cultured under hyperglycemic conditions. Human monocytic (THP-1) cells were cultured under control (14.5 mmol/L mannitol), normoglycemic (NG, 5.5 mmol/L glucose), or hyperglycemic (HG, 20 mmol/L glucose) conditions, in the absence or presence of fisetin. Fisetin was added (3-10 μM) for 48 h. While the HG condition significantly induced histone acetylation, NF-κB activation, and proinflammatory cytokine (IL-6 and TNF-α) release from THP-1 cells, fisetin suppressed NF-κB activity and cytokine release. Fisetin treatment also significantly reduced CBP/p300 gene expression, as well as the levels of acetylation and HAT activity of the CBP/p300 protein, which is a known NF-κB coactivator. These results suggest that fisetin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB. We therefore propose that fisetin supplementation be considered for diabetes prevention.

No MeSH data available.


Related in: MedlinePlus

Effect of fisetin on HAT and HDAC activity as well as p300 and acetylated CBP/p300 levels in HG-treated THP-1 cells. Cells were harvested after 48 h of fisetin treatment and nuclear lysates were prepared. Samples were analyzed for determination of HAT (a) and HDAC activity (b). Results are shown as mean ± SD for 3 different experiments. ††P < 0.01 compared to NG; *P < 0.05; **P < 0.01 compared to HG. (c) After nuclear protein extraction, p300 and acetylated CBP/p300 levels were evaluated by western blot. The immunoblots shown here are representative of 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3539716&req=5

fig3: Effect of fisetin on HAT and HDAC activity as well as p300 and acetylated CBP/p300 levels in HG-treated THP-1 cells. Cells were harvested after 48 h of fisetin treatment and nuclear lysates were prepared. Samples were analyzed for determination of HAT (a) and HDAC activity (b). Results are shown as mean ± SD for 3 different experiments. ††P < 0.01 compared to NG; *P < 0.05; **P < 0.01 compared to HG. (c) After nuclear protein extraction, p300 and acetylated CBP/p300 levels were evaluated by western blot. The immunoblots shown here are representative of 3 independent experiments.

Mentions: We next addressed the mechanism by which fisetin inhibits cytokine gene expression in monocytes. To obtain further insights into the mechanisms of fisetin-induced downregulation of inflammatory cytokines, we first examined whether fisetin treatment modulates HAT and HDAC activity, using ELISA. As shown in Figure 3, under hyperglycemic conditions, there was a significant increase in HAT activity and decrease in HDAC activity compared to normal glucose conditions (P < 0.01). Interestingly, fisetin treatment results in a significant downregulation of HAT and upregulation of HDAC activity (P < 0.01). High glucose levels activate transcription factors, such as NF-κB, by recruitment of transcriptional coactivator molecules CBP/p300, which possess intrinsic HAT activity. The resulting increase in histone acetylation and DNA unwinding allow RNA polymerase to access DNA, leading to proinflammatory gene expression. As shown in Figure 3(c), THP-1 cells cultured under hyperglycemic conditions showed marked upregulation of p300 as well as its acetylation levels, compared with cells cultured under normal glycemic conditions. d-mannitol had no effect on p300. As shown Figure 3(c), p300 activation was abolished by fisetin (10 μM) treatment. Fisetin also decreased the levels of acetylated CBP/p300 in high-glucose conditions, to levels comparable to those observed under normal glucose conditions. No effects were observed with DMSO (0.1%) vehicle control treatment.


Fisetin inhibits hyperglycemia-induced proinflammatory cytokine production by epigenetic mechanisms.

Kim HJ, Kim SH, Yun JM - Evid Based Complement Alternat Med (2012)

Effect of fisetin on HAT and HDAC activity as well as p300 and acetylated CBP/p300 levels in HG-treated THP-1 cells. Cells were harvested after 48 h of fisetin treatment and nuclear lysates were prepared. Samples were analyzed for determination of HAT (a) and HDAC activity (b). Results are shown as mean ± SD for 3 different experiments. ††P < 0.01 compared to NG; *P < 0.05; **P < 0.01 compared to HG. (c) After nuclear protein extraction, p300 and acetylated CBP/p300 levels were evaluated by western blot. The immunoblots shown here are representative of 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539716&req=5

fig3: Effect of fisetin on HAT and HDAC activity as well as p300 and acetylated CBP/p300 levels in HG-treated THP-1 cells. Cells were harvested after 48 h of fisetin treatment and nuclear lysates were prepared. Samples were analyzed for determination of HAT (a) and HDAC activity (b). Results are shown as mean ± SD for 3 different experiments. ††P < 0.01 compared to NG; *P < 0.05; **P < 0.01 compared to HG. (c) After nuclear protein extraction, p300 and acetylated CBP/p300 levels were evaluated by western blot. The immunoblots shown here are representative of 3 independent experiments.
Mentions: We next addressed the mechanism by which fisetin inhibits cytokine gene expression in monocytes. To obtain further insights into the mechanisms of fisetin-induced downregulation of inflammatory cytokines, we first examined whether fisetin treatment modulates HAT and HDAC activity, using ELISA. As shown in Figure 3, under hyperglycemic conditions, there was a significant increase in HAT activity and decrease in HDAC activity compared to normal glucose conditions (P < 0.01). Interestingly, fisetin treatment results in a significant downregulation of HAT and upregulation of HDAC activity (P < 0.01). High glucose levels activate transcription factors, such as NF-κB, by recruitment of transcriptional coactivator molecules CBP/p300, which possess intrinsic HAT activity. The resulting increase in histone acetylation and DNA unwinding allow RNA polymerase to access DNA, leading to proinflammatory gene expression. As shown in Figure 3(c), THP-1 cells cultured under hyperglycemic conditions showed marked upregulation of p300 as well as its acetylation levels, compared with cells cultured under normal glycemic conditions. d-mannitol had no effect on p300. As shown Figure 3(c), p300 activation was abolished by fisetin (10 μM) treatment. Fisetin also decreased the levels of acetylated CBP/p300 in high-glucose conditions, to levels comparable to those observed under normal glucose conditions. No effects were observed with DMSO (0.1%) vehicle control treatment.

Bottom Line: Fisetin, a flavonoid dietary ingredient found in the smoke tree (Cotinus coggygria), and is also widely distributed in fruits and vegetables.Fisetin is known to exert anti-inflammatory effects via inhibition of the NF-κB signaling pathway.These results suggest that fisetin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB.

View Article: PubMed Central - PubMed

Affiliation: Pharmacology Research Center, Korea Research Institute of Chemical Technology, Daejeon 305-600, Republic of Korea.

ABSTRACT
Diabetes is characterized by a proinflammatory state, and several inflammatory processes have been associated with both type 1 and type 2 diabetes and the resulting complications. High glucose levels induce the release of proinflammatory cytokines. Fisetin, a flavonoid dietary ingredient found in the smoke tree (Cotinus coggygria), and is also widely distributed in fruits and vegetables. Fisetin is known to exert anti-inflammatory effects via inhibition of the NF-κB signaling pathway. In this study, we analyzed the effects of fisetin on proinflammatory cytokine secretion and epigenetic regulation, in human monocytes cultured under hyperglycemic conditions. Human monocytic (THP-1) cells were cultured under control (14.5 mmol/L mannitol), normoglycemic (NG, 5.5 mmol/L glucose), or hyperglycemic (HG, 20 mmol/L glucose) conditions, in the absence or presence of fisetin. Fisetin was added (3-10 μM) for 48 h. While the HG condition significantly induced histone acetylation, NF-κB activation, and proinflammatory cytokine (IL-6 and TNF-α) release from THP-1 cells, fisetin suppressed NF-κB activity and cytokine release. Fisetin treatment also significantly reduced CBP/p300 gene expression, as well as the levels of acetylation and HAT activity of the CBP/p300 protein, which is a known NF-κB coactivator. These results suggest that fisetin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB. We therefore propose that fisetin supplementation be considered for diabetes prevention.

No MeSH data available.


Related in: MedlinePlus