Atomic force microscopy based investigations of anti-inflammatory effects in lipopolysaccharide-stimulated macrophages
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A new method based on atomic force microscopy (AFM) was developed to investigate the anti-inflammatory effects of drugs on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The LPS-stimulated RAW264.7 macrophage cell line is a widely used in vitro cell model for the screening of anti-inflammatory drugs or the study of anti-inflammatory mechanisms. In this work, the inhibitory effects of dexamethasone and quercetin on LPS–CD14 receptor binding in RAW264.7 macrophages was probed by LPS-functionalized tips for the first time. Both dexamethasone and quercetin were found to inhibit LPS-induced NO production, iNOS expression, IκBα phosphorylation, and IKKα/β phosphorylation in RAW264.7 macrophages. The morphology and ultrastructure of RAW264.7 macrophages were determined by AFM, which indicated that dexamethasone and quercetin could inhibit LPS-induced cell surface particle size and roughness increase in RAW264.7 macrophages. The binding of LPS and its receptor in RAW264.7 macrophages was determined by LPS-functionalized AFM tips, which demonstrated that the binding force and binding probability between LPS and CD14 receptor on the surface of RAW264.7 macrophages were also inhibited by dexamethasone or quercetin treatment. The obtained results imply that AFM, which is very useful for the investigation of potential targets for anti-inflammatory drugs on native macrophages and the enhancement of our understanding of the anti-inflammatory effects of drugs, is expected to be developed into a promising tool for the study of anti-inflammatory drugs.
KeywordsAtomic force microscopy Anti-inflammatory Lipopolysaccharide Macrophages CD14 receptor
This work was financially supported by Macao Science and Technology Development
Fund (No. 028/2014/A1), the Overseas, Hong Kong & Macao Cooperative Research Funds of China (No. 31129002), and Jinan University’s Scientific Research Cultivation and Innovation Fund (No. 21612601).
Conflict of interest
The authors declare that they have no conflict of interest.
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