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( − )-Epigallocatechin Gallate Targets Notch to Attenuate the Inflammatory Response in the Immediate Early Stage in Human Macrophages

View Article: PubMed Central - PubMed

ABSTRACT

Inflammation plays important roles at different stages of diabetes mellitus, tumorigenesis, and cardiovascular diseases. (−)-Epigallocatechin gallate (EGCG) can attenuate inflammatory responses effectively. However, the immediate early mechanism of EGCG in inflammation remains unclear. Here, we showed that EGCG attenuated the inflammatory response in the immediate early stage of EGCG treatment by shutting off Notch signaling and that the effect did not involve the 67-kDa laminin receptor, the common receptor for EGCG. EGCG eliminated mature Notch from the cell membrane and the nuclear Notch intercellular domain, the active form of Notch, within 2 min by rapid degradation via the proteasome pathway. Transcription of the Notch target gene was downregulated simultaneously. Knockdown of Notch 1/2 expression by RNA interference impaired the downregulation of the inflammatory response elicited by EGCG. Further study showed that EGCG inhibited lipopolysaccharide-induced inflammation and turned off Notch signaling in human primary macrophages. Taken together, our results show that EGCG targets Notch to regulate the inflammatory response in the immediate early stage.

No MeSH data available.


(−)-Epigallocatechin gallate (EGCG) attenuated inflammation not involved in the classical immune pathway. THP-1-derived macrophages were treated with lipopolysaccharide (LPS) (200 EU/mL) for 30, 60, and 90 min by pretreated EGCG (50 μg/mL, 30 min). The major immunological pathways nuclear factor-kappa B (NF-κB) (A) and MAPK [p38, p42/44, and c-Jun-N-terminal kinase (JNK)] (B) were detected. n.s., not significant.
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Figure 2: (−)-Epigallocatechin gallate (EGCG) attenuated inflammation not involved in the classical immune pathway. THP-1-derived macrophages were treated with lipopolysaccharide (LPS) (200 EU/mL) for 30, 60, and 90 min by pretreated EGCG (50 μg/mL, 30 min). The major immunological pathways nuclear factor-kappa B (NF-κB) (A) and MAPK [p38, p42/44, and c-Jun-N-terminal kinase (JNK)] (B) were detected. n.s., not significant.

Mentions: The phosphorylation of NFκB and MAPK (i.e., p42/44, p38, and JNK) in THP-1-derived human macrophages was detected by western blotting after LPS treatment for 30, 60, and 90 min. EGCG was added 30 min before LPS. In contrast to the mechanisms described for EGCG upon inflammation, the phosphorylation of NFκB (Figure 2A), p42/44, and JNK (Figure 2B) was not inhibited by EGCG within the first 60 min, and the phosphorylation of p38 increased upon EGCG addition (Figure 2B). Sixty minutes after EGCG addition, NFκB phosphorylation remained unchanged. Moreover, the phosphorylation of ERK (p42/44) (Figure 2B) also increased upon EGCG addition. Increased phosphorylation has been shown to enhance the inflammatory response, and so the increased phosphorylation of MAPK induced by EGCG could not explain the attenuated inflammatory effects of EGCG and nor could NF-κB.


( − )-Epigallocatechin Gallate Targets Notch to Attenuate the Inflammatory Response in the Immediate Early Stage in Human Macrophages
(−)-Epigallocatechin gallate (EGCG) attenuated inflammation not involved in the classical immune pathway. THP-1-derived macrophages were treated with lipopolysaccharide (LPS) (200 EU/mL) for 30, 60, and 90 min by pretreated EGCG (50 μg/mL, 30 min). The major immunological pathways nuclear factor-kappa B (NF-κB) (A) and MAPK [p38, p42/44, and c-Jun-N-terminal kinase (JNK)] (B) were detected. n.s., not significant.
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Related In: Results  -  Collection

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Figure 2: (−)-Epigallocatechin gallate (EGCG) attenuated inflammation not involved in the classical immune pathway. THP-1-derived macrophages were treated with lipopolysaccharide (LPS) (200 EU/mL) for 30, 60, and 90 min by pretreated EGCG (50 μg/mL, 30 min). The major immunological pathways nuclear factor-kappa B (NF-κB) (A) and MAPK [p38, p42/44, and c-Jun-N-terminal kinase (JNK)] (B) were detected. n.s., not significant.
Mentions: The phosphorylation of NFκB and MAPK (i.e., p42/44, p38, and JNK) in THP-1-derived human macrophages was detected by western blotting after LPS treatment for 30, 60, and 90 min. EGCG was added 30 min before LPS. In contrast to the mechanisms described for EGCG upon inflammation, the phosphorylation of NFκB (Figure 2A), p42/44, and JNK (Figure 2B) was not inhibited by EGCG within the first 60 min, and the phosphorylation of p38 increased upon EGCG addition (Figure 2B). Sixty minutes after EGCG addition, NFκB phosphorylation remained unchanged. Moreover, the phosphorylation of ERK (p42/44) (Figure 2B) also increased upon EGCG addition. Increased phosphorylation has been shown to enhance the inflammatory response, and so the increased phosphorylation of MAPK induced by EGCG could not explain the attenuated inflammatory effects of EGCG and nor could NF-κB.

View Article: PubMed Central - PubMed

ABSTRACT

Inflammation plays important roles at different stages of diabetes mellitus, tumorigenesis, and cardiovascular diseases. (−)-Epigallocatechin gallate (EGCG) can attenuate inflammatory responses effectively. However, the immediate early mechanism of EGCG in inflammation remains unclear. Here, we showed that EGCG attenuated the inflammatory response in the immediate early stage of EGCG treatment by shutting off Notch signaling and that the effect did not involve the 67-kDa laminin receptor, the common receptor for EGCG. EGCG eliminated mature Notch from the cell membrane and the nuclear Notch intercellular domain, the active form of Notch, within 2 min by rapid degradation via the proteasome pathway. Transcription of the Notch target gene was downregulated simultaneously. Knockdown of Notch 1/2 expression by RNA interference impaired the downregulation of the inflammatory response elicited by EGCG. Further study showed that EGCG inhibited lipopolysaccharide-induced inflammation and turned off Notch signaling in human primary macrophages. Taken together, our results show that EGCG targets Notch to regulate the inflammatory response in the immediate early stage.

No MeSH data available.