Involvement of Antioxidant Defenses and NF-κB/ERK Signaling in Anti-Inflammatory Effects of Pterostilbene, a Natural Analogue of Resveratrol

Thanasekaran Jayakumar,Periyakali Saravana Bhavan,Joen-Rong Sheu,Chi-Li Chung,Chih-Hsuan Hsia,Chih-Wei Hsia,Ming-Ping Wu,Manjunath Manubolu

doi:10.3390/app11104666

Abstract

Pterostilbene (PTE), a natural stilbenoid occurring in grapes and berries, is recognized as a dimethylated analogue of resveratrol. This compound shows numerous notable pharmacological activities, including antiaging, anticancer, antidiabetes, antioxidant, and neuroprotection. This study investigates the anti-inflammatory properties of PTE in macrophage cells (RAW 264.7) against the lipoteichoic acid (LTA) stimulation. The expression of inflammatory tumor necrosis factor (TNF-α), interleukin-1β (IL-1 β), and inducible nitric oxide synthase (iNOS) and the content of nitric oxide (NO) were detected in LTA-induced cells. In addition, a Western blot assay was used to detect mitogen-activated protein kinases: extracellular signal-regulated kinase (ERK)1/2, p38 MAPK, and c-Jun N-terminal kinase (JNK). The phosphorylation of IκB and p65 and translocation of nuclear factor kappa B (NF-κB) were assessed by Western blot and immuno-fluorescence staining. The results showed that PTE significantly attenuated NO production and TNF-α, IL-1 β, and iNOS expression in LTA stimulated cells. Among the activation of ERK, JNK, and p38 in cells treated with LTA, PTE at higher concentration had only inhibited ERK activation. However, PTE blocked IκB phosphorylation, phosphorylation and nuclear translocation of p65NF-κB. Fascinatingly, PTE enhanced antioxidant defense molecules as verified by the enhanced heme oxygenase-1 (HO-1) expression, catalase (CAT) antioxidant enzyme, and non-enzymatic antioxidant, and reduced glutathione (GSH) in LTA-induced RAW 264.7 cells. These results suggest that PTE exerts an anti-inflammatory property via attenuating NF-κB/ERK signaling pathways as well as enriching antioxidant defense mechanisms.

Highlights

Inflammation is a major influence on the host defense against pathogenic encounters and the repair of normal tissue construction [1]
A previous study showed that lipoteichoic acid (LTA) induced tumor necrosis factor-α (TNF-α) and IL-6 expressions via stimulating phosphorylation of ERK1/2 in macrophages; it triggered translocation of nuclear factor (NF)-κB from the cytoplasm to nuclei and its transactivation activity [8]
The antibodies against TNF-α, phospho-p38 mitogenactivated protein kinases (MAPKs) Thr180/Tyr182, phospho-c-Jun N-terminal kinase (JNK) (Thr183/Tyr185), phospho-p44/p42 extracellular signal-regulated kinase (ERK) (Thr202/Tyr204), phospho-IκBα Ser32/36, phospho-NF-κB p65 (Ser536) polycloncal antibody (pAb) were all purchased from Cell Signaling (Beverly, MA, USA)

Summary

Introduction

Inflammation is a major influence on the host defense against pathogenic encounters and the repair of normal tissue construction [1]. The main pro-inflammatory cells, macrophages, protect the body from external invaders by producing pro-inflammatory mediators and cytokines such as nitric oxide (NO), inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), and IL-1β [2]. These mediators and cytokines induce cell and tissue damage, which are involved in chronic inflammatory diseases such as hepatitis, rheumatoid arthritis, and atherosclerosis [3,4]. Investigating the mechanisms that control LTA-mediated cell activation is crucial for diagnosis and treatment of lung inflammatory diseases. A previous study showed that LTA induced TNF-α and IL-6 expressions via stimulating phosphorylation of ERK1/2 in macrophages; it triggered translocation of nuclear factor (NF)-κB from the cytoplasm to nuclei and its transactivation activity [8]

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Discussion

Conclusion