TNFa alter cholesterol metabolism in human macrophages via PKC-θ-dependent pathway

A Zhi Sha Ma,Qian Zhang,Zhi Yuan Song

doi:10.1186/1471-2091-14-20

A Zhi Sha Ma, Qian Zhang + Show 1 more

Open Access

https://doi.org/10.1186/1471-2091-14-20

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Abstract

BackgroundStudies have shown that inflammation promoted atherosclerotic progression; however, it remains unclear whether inflammation promoted atherosclerotic progression properties by altering cholesterol metabolism in human macrophages. In the present study, we evaluated a potential mechanism of inflammation on atherogenic effects. We evaluated the ability of TNFa to affect Reverse cholesterol transport (RCT) and cholesterol uptake and its mechanism(s) of action in human macrophages.ResultsWe initially determined the potential effects of TNFa on cholesterol efflux in the human macrophages. We also determined alterations in mRNA and protein levels of ABCA1, ABCG1, LXRa, CD-36, SR-A in human macrophages using quantitative real-time polymerase chain reaction (PCR) and Western immunoblot analyses. The cholesterol efflux rate and protein expression of ABCA1, ABCG1, LXRa, CD-36, SR-A were quantified in human macrophages under PKC-θ inhibition using PKC-θ siRNA. Our results showed that TNFa inhibited the rate of cholesterol efflux and down-regulation the expression levels of ABCA1, ABCG1 and LXRa and up-regulation the expression levels of CD-36, SR-A in human macrophages; PKC-θ inhibition by PKC-θ siRNA attenuated the effect of TNFa on ABCA1, ABCG1, LXRa, SR-A, CD-36 expression.ConclusionsOur results suggest TNFa alter cholesterol metabolism in human macrophages through the inhibition of Reverse cholesterol transport and enhancing cholesterol uptake via PKC-θ-dependent pathway, implicating a potential mechanism of inflammation on atherogenic effects.

Highlights

Studies have shown that inflammation promoted atherosclerotic progression; it remains unclear whether inflammation promoted atherosclerotic progression properties by altering cholesterol metabolism in human macrophages
Tumour necrosis factor alpha (TNFa) inhibited cholesterol efflux in human macrophages We initially examined the effect of TNFa on cholesterol efflux in human macrophages using liquid scintillation counting assays
TNFa down-regulated the mRNA and protein expression of ABCA1, ABCG1, LXRa in human macrophages To further explore the effects of TNFa on human marcophage-mediated Reverse cholesterol transport (RCT), we examined the effects of TNFa on ABCA1, ABCG1 and LXRa expression in human macrophages using real-time quantitative polymerase chain reaction (PCR) and Western immunoblot analyses

Summary

Introduction

Studies have shown that inflammation promoted atherosclerotic progression; it remains unclear whether inflammation promoted atherosclerotic progression properties by altering cholesterol metabolism in human macrophages. We evaluated the ability of TNFa to affect Reverse cholesterol transport (RCT) and cholesterol uptake and its mechanism(s) of action in human macrophages. Three main mechanisms are known to be anti-atherosclerotic: Endothelial progenitor cells, plaque neovascularization and reverse cholesterol transport (RCT). Human studies and animal models implicate TNFa in atherosclerotic plaque formation [6]. It is still unclear that TNFa promote atherosclerotic plaque formation whether related to alter cholesterol metabolism in human macrophages. We set out to investigate the effect of TNFa treatment on Reverse cholesterol transport function and the expression of CD-36, SR-A in human macrophages

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