Impact of a long-term high-glucose environment on pro-inflammatory responses in macrophages stimulated with lipopolysaccharide
- 17 August 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Naunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie
- Vol. 394 (10), 2129-2139
- https://doi.org/10.1007/s00210-021-02137-8
Abstract
Cumulative evidence has established that macrophages orchestrate inflammatory responses that crucially contribute to the pathogenesis of insulin-resistant obesity and type 2 diabetes. In the present study, we examined the impact of hyperglycemia on macrophage pro-inflammatory responses under an inflammatory stimulus. To conduct this study, RAW264.7 macrophages were cultured under normal- (5.5 mM) or high-glucose (22 or 40 mM) conditions for 7 days and stimulated with lipopolysaccharide (LPS). Long-term exposure to high glucose significantly enhanced the increase in the production of pro-inflammatory cytokines, including tumor necrosis-α, interleukin (IL)-1β, and IL-6, when macrophages were stimulated with LPS. The LPS-induced increases in inducible nitric oxide (NO) synthase (iNOS) expression and NO production were also significantly enhanced by long-term exposure of macrophages to high glucose. Treatment with N-acetyl-l-cysteine, a widely used thiol-containing antioxidant, blunted the enhancement of the LPS-induced upregulation of pro-inflammatory cytokine production, iNOS expression, and NO production in macrophages. When intracellular reactive oxygen species (ROS) were visualized using the fluorescence dye 5-(and-6)-chloromethyl-2′,7′-dichlorofluorescein diacetate, acetyl ester, a significant increase in ROS generation was found after stimulation of macrophages with LPS, and this increased ROS generation was exacerbated under long-term high-glucose conditions. LPS-induced translocation of phosphorylated nuclear factor-κB (NF-κB), a transcription factor regulating many pro-inflammatory genes, into the nucleus was promoted under long-term high-glucose conditions. Altogether, the present results indicate that a long-term high-glucose environment can enhance activation of NF-κB in LPS-stimulated macrophages possibly due to excessive ROS production, thereby leading to increased macrophage pro-inflammatory responses.Keywords
Funding Information
- japan society for promotion of science (16K1905, 19H03757, 17K08586, 20K17776)
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