Research Papers:

TLR2 activation induces antioxidant defence in human monocyte-macrophage cell line models

Iwona Karwaciak, Michal Gorzkiewicz, Grzegorz Bartosz and Lukasz Pulaski _

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Oncotarget. 2017; 8:54243-54264. https://doi.org/10.18632/oncotarget.17342

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Iwona Karwaciak1, Michal Gorzkiewicz1,3, Grzegorz Bartosz2 and Lukasz Pulaski1,2

1Laboratory of Transcriptional Regulation, Institute of Medical Biology PAS, Lodz, Poland

2Department of Molecular Biophysics, Faculty of Biology and Environmental Sciences, University of Lodz, Lodz, Poland

3Department of General Biophysics, Faculty of Biology and Environmental Sciences, University of Lodz, Lodz, Poland

Correspondence to:

Lukasz Pulaski, email: [email protected]

Keywords: monocyte, macrophage, redox homeostasis, differentiation, pattern recognition receptor

Received: June 14, 2016     Accepted: April 10, 2017     Published: April 21, 2017


When monocytes are recruited to inflammation/infection sites, extravasate and differentiate into macrophages, they encounter increasing levels of oxidative stress, both from exogenous and endogenous sources. In this study, we aimed to determine whether there are specific biochemical mechanisms responsible for an increase in oxidative stress resistance in differentiating macrophages. We performed experiments on in vitro cell line models of the monocyte-macrophage differentiation axis (less differentiated THP-1 cells and more differentiated Mono Mac 6 cells). At the same time, we verified the hypothesis that activating monocyte/macrophage innate immune response by pathogens (exemplified by stimulating the TLR2 pattern recognition receptor) would further strengthen cellular antioxidant defences. We found that resistance to exogenous oxidative stress increased substantially both during differentiation and upon activation of TLR2. This increase in antioxidant resistance was accompanied by decrease in free radical damage to cellular proteins. On the molecular level, this resistance was mediated especially by increased levels and activity of glutathione, glutathione-related antioxidant enzymes and Mn superoxide dismutase, as shown by gene expression assays, Western blotting and enzyme activity assays. Moreover, upon TLR2 activation additional molecular mechanisms came into play, conferring additional resistance levels even upon differentiated macrophage-like cells, mainly related to thioredoxin-linked antioxidant enzymes.

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