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Piperine inhibits ABCA1 degradation and promotes cholesterol efflux from THP-1-derived macrophages

View Article: PubMed Central - PubMed

ABSTRACT

Scope: Increased macrophage cholesterol efflux (ChE) is considered to have anti-atherosclerotic effect counteracting cardiovascular disease. The principle pungent ingredient of the fruits of Piper nigrum, piperine, is identified in this study as a ChE inducer in THP-1-derived macrophages, and mechanisms underlying this effect are explored.

Methods and results: Without affecting cell viability, piperine concentration-dependently enhances ChE in THP-1-derived macrophages from 25 to 100 μM. The expression level of the key cholesterol transporter protein ATP-binding cassette transporter A1 (ABCA1) is significantly upregulated by piperine, as revealed by western blot analyses. However, two other ChE-mediating transporter proteins, ATP-binding cassette transporter G1 (ABCG1) and scavenger receptor class B member 1 (SR-B1), remain unaffected. Piperine exerts no influence on ABCA1 mRNA levels, but significantly inhibits the degradation of ABCA1, as evident by an increased half-life of the protein in the presence of cycloheximide. Furthermore, it is found that piperine likely interferes with the calpain-mediated ABCA1 degradation pathway and exhibits significant inhibition of calpain activity.

Conclusion: Our findings suggest that piperine promotes ChE in THP-1-derived macrophages by upregulation of ABCA1, which might be mediated by inhibition of calpain activity. This novel bioactivity makes the dietary constituent piperine a good candidate to be further explored for therapeutic or preventive applications in the context of atherosclerosis.

No MeSH data available.


Related in: MedlinePlus

Effect of piperine on ChE in THP-1 macrophages. Differentiated THP-1 macrophages were loaded with [3H]-cholesterol together with solvent vehicle (DMSO), piperine (PIP, 5–100 µM), or the PPARγ agonist pioglitazone (PIO, 10 µM) as a positive control as indicated for 24 h. On the next day, cells were washed twice with PBS and incubated again with the same compounds in the presence or absence of 10 µg/mL apo A1 (A) or 1% human plasma (B) dissolved in serum-free medium, for 6 h. Extracellular as well as intracellular radioactivity were quantified by scintillation counting. All values are mean ± SD (n = 3) versus solvent vehicle control, *p < 0.05; ***p < 0.001; n.s., no significance (one-way ANOVA/Bonferroni).
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Figure 2: Effect of piperine on ChE in THP-1 macrophages. Differentiated THP-1 macrophages were loaded with [3H]-cholesterol together with solvent vehicle (DMSO), piperine (PIP, 5–100 µM), or the PPARγ agonist pioglitazone (PIO, 10 µM) as a positive control as indicated for 24 h. On the next day, cells were washed twice with PBS and incubated again with the same compounds in the presence or absence of 10 µg/mL apo A1 (A) or 1% human plasma (B) dissolved in serum-free medium, for 6 h. Extracellular as well as intracellular radioactivity were quantified by scintillation counting. All values are mean ± SD (n = 3) versus solvent vehicle control, *p < 0.05; ***p < 0.001; n.s., no significance (one-way ANOVA/Bonferroni).

Mentions: First we surveyed whether piperine (Fig. 1A), applied at concentrations that did not affect cell viability (Fig. 1B), can increase ChE in differentiated THP-1 macrophages. As evident in Fig. 2A, piperine enhances apo A1-mediated ChE concentration dependently (5–100 μM). Pioglitazone, a PPARγ agonist, applied at 10 μM was used as positive control since it is a well-known macrophage ChE inducer [29]. Furthermore, piperine also increased ChE mediated by human plasma (Fig. 2B), which is the acceptor with highest relevance to the ChE process happening in vivo.


Piperine inhibits ABCA1 degradation and promotes cholesterol efflux from THP-1-derived macrophages
Effect of piperine on ChE in THP-1 macrophages. Differentiated THP-1 macrophages were loaded with [3H]-cholesterol together with solvent vehicle (DMSO), piperine (PIP, 5–100 µM), or the PPARγ agonist pioglitazone (PIO, 10 µM) as a positive control as indicated for 24 h. On the next day, cells were washed twice with PBS and incubated again with the same compounds in the presence or absence of 10 µg/mL apo A1 (A) or 1% human plasma (B) dissolved in serum-free medium, for 6 h. Extracellular as well as intracellular radioactivity were quantified by scintillation counting. All values are mean ± SD (n = 3) versus solvent vehicle control, *p < 0.05; ***p < 0.001; n.s., no significance (one-way ANOVA/Bonferroni).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382977&req=5

Figure 2: Effect of piperine on ChE in THP-1 macrophages. Differentiated THP-1 macrophages were loaded with [3H]-cholesterol together with solvent vehicle (DMSO), piperine (PIP, 5–100 µM), or the PPARγ agonist pioglitazone (PIO, 10 µM) as a positive control as indicated for 24 h. On the next day, cells were washed twice with PBS and incubated again with the same compounds in the presence or absence of 10 µg/mL apo A1 (A) or 1% human plasma (B) dissolved in serum-free medium, for 6 h. Extracellular as well as intracellular radioactivity were quantified by scintillation counting. All values are mean ± SD (n = 3) versus solvent vehicle control, *p < 0.05; ***p < 0.001; n.s., no significance (one-way ANOVA/Bonferroni).
Mentions: First we surveyed whether piperine (Fig. 1A), applied at concentrations that did not affect cell viability (Fig. 1B), can increase ChE in differentiated THP-1 macrophages. As evident in Fig. 2A, piperine enhances apo A1-mediated ChE concentration dependently (5–100 μM). Pioglitazone, a PPARγ agonist, applied at 10 μM was used as positive control since it is a well-known macrophage ChE inducer [29]. Furthermore, piperine also increased ChE mediated by human plasma (Fig. 2B), which is the acceptor with highest relevance to the ChE process happening in vivo.

View Article: PubMed Central - PubMed

ABSTRACT

Scope: Increased macrophage cholesterol efflux (ChE) is considered to have anti-atherosclerotic effect counteracting cardiovascular disease. The principle pungent ingredient of the fruits of Piper nigrum, piperine, is identified in this study as a ChE inducer in THP-1-derived macrophages, and mechanisms underlying this effect are explored.

Methods and results: Without affecting cell viability, piperine concentration-dependently enhances ChE in THP-1-derived macrophages from 25 to 100 &mu;M. The expression level of the key cholesterol transporter protein ATP-binding cassette transporter A1 (ABCA1) is significantly upregulated by piperine, as revealed by western blot analyses. However, two other ChE-mediating transporter proteins, ATP-binding cassette transporter G1 (ABCG1) and scavenger receptor class B member 1 (SR-B1), remain unaffected. Piperine exerts no influence on ABCA1 mRNA levels, but significantly inhibits the degradation of ABCA1, as evident by an increased half-life of the protein in the presence of cycloheximide. Furthermore, it is found that piperine likely interferes with the calpain-mediated ABCA1 degradation pathway and exhibits significant inhibition of calpain activity.

Conclusion: Our findings suggest that piperine promotes ChE in THP-1-derived macrophages by upregulation of ABCA1, which might be mediated by inhibition of calpain activity. This novel bioactivity makes the dietary constituent piperine a good candidate to be further explored for therapeutic or preventive applications in the context of atherosclerosis.

No MeSH data available.


Related in: MedlinePlus