Curcumin attenuates oxidative stress in RAW264.7 cells by increasing the activity of antioxidant enzymes and activating the Nrf2-Keap1 pathway.

Xinyu Lin,Ying Zhang,Yifan Huang,Zixi Wei,Hui Deng,Dingping Bai,Xiaohong Huang,Partha Mukhopadhyay

doi:10.1371/journal.pone.0216711

Xinyu Lin, Ying Zhang + Show 6 more

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https://doi.org/10.1371/journal.pone.0216711

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Abstract

Large-scale breeding environments often lead to oxidative stress. Macrophages play an important role in the immune system and are vulnerable to reactive oxygen species (ROS), which result in macrophage death. Curcumin is the main active component of turmeric and exerts antioxidant effects. Here, we measured the activity of some antioxidant enzymes and chose the Nrf2-Keap1 signaling pathway to study the protective effects of curcumin on macrophages under oxidative stress in vitro. We used RAW264.7 cells as a research model, and oxidative damage was induced by hydrogen peroxide (H2O2). Cell viability was measured by an MTT assay. Flow cytometry was used to measure cellular ROS and apoptosis. The effect of curcumin on Nrf2-Keap1 signaling pathway-related genes was analyzed by qRT-PCR. Furthermore, the translocation of Nrf2 protein was also investigated by Western blot analysis of total and nuclear proteins. All curcumin-treated groups exhibited increased activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX). Low- and middle-dose curcumin decreased malondialdehyde (MDA) and ROS levels, but high-dose curcumin increased MDA and ROS production. We found that low-dose curcumin protected cells from apoptosis, while apoptosis in the middle- and high-dose curcumin-treated groups were stagnant in the early stage. Furthermore, middle-dose curcumin upregulated Nrf2 expression after H2O2 treatment for 4 h. Low- and middle-dose curcumin could activate Nrf2 and promote it to migrate into nuclei. The translocation of Nrf2 to the nucleus to upregulate the expression of haemoxygenase-1 (HO-1) was promoted in the low- and middle-dose curcumin-treated groups. The middle-dose curcumin-treated group also exhibited enhanced expression of glutamate-cysteine ligase, a modifier subunit (GLCM), but inhibited transcription of glutamate-cysteine ligase, a catalytic subunit (GCLC). Curcumin resisted oxidants by increasing the activity of antioxidant enzymes and activating the Nrf2-Keap1 pathway, which could potentially promote cell survival.

Highlights

With improvements in economic and living standards, the demand for livestock products is growing, which has promoted the transformation of animal husbandry
When animals are under oxidative stress, reactive oxygen species (ROS) interfere with the balance of oxygen utilization by the body
Among the 8 h H2O2-treated groups, there was a significant increase in cell viability in the middle-dose group compared with the positive control group (P

Summary

Introduction

With improvements in economic and living standards, the demand for livestock products is growing, which has promoted the transformation of animal husbandry. Factory farming allows a larger number of animals to be produced more quickly and economically. This model improves the efficiency of farming but has some negative aspects, such as high-fat and high-energy density food consumption by animals and the high-temperature and high-humidity environment. All of these factors can lead to oxidative stress[1,2,3]. When animals are under oxidative stress, ROS interfere with the balance of oxygen utilization by the body. Maintaining and improving oxidative status, especially through natural products, are essential for normal physiological processes in animals

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