Attenuation of inflammatory responses by (+)-syringaresinol via MAP-Kinase-mediated suppression of NF-\u03baB signaling in vitro and in vivo

Vivek K Bajpai,Sang Han Lee,Shruti Shukla,Minkyun Na,Md Badrul Alam,Young-Kyu Han,Khong Trong Quan,Yun Suk Huh,Rajib Majumder,Mi-Kyoung Ju

doi:10.1038/s41598-018-27585-w

Abstract

We examined the anti-inflammatory effects of (+)-syringaresinol (SGRS), a lignan isolated from Rubia philippinensis, in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells using enzyme-based immuno assay, Western blotting, and RT-PCR analyses. Additionally, in vivo effects of SGRS in the acute inflammatory state were examined by using the carrageenan-induced hind paw edema assay in experimental mice. As a result, treatment with SGRS (25, 50, and 100 μM) inhibited protein expression of lipopolysaccharide-stimulated inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa B (NF-κB) as well as production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-6 (IL-6) induced by LPS. Moreover, SGRS also reduced LPS-induced mRNA expression levels of iNOS and COX-2, including NO, PGE2, TNF-α, IL-1β, and IL-6 cytokines in a dose-dependent fashion. Furthermore, carrageenan-induced paw edema assay validated the in vivo anti-edema effect of SGRS. Interestingly, SGRS (30 mg/kg) suppressed carrageenan-induced elevation of iNOS, COX-2, TNF-α, IL-1β, and IL-6 mRNA levels as well as COX-2 and NF-κB protein levels, suggesting SGRS may possess anti-inflammatory activities.

Highlights

The inflammatory response, a physiological reaction to infection or damage, plays a vital role in the natural defense mechanisms of the body to maintain immune homeostasis[1]
As a part of prior research examining the biological potential of effective phytochemicals and to minimize the side effects of commercial anti-inflammatory drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), a lignan, (+)-syringaresinol (SGRS) isolated in this study from R. philippinensis was assessed for its potent anti-inflammatory effects both in vitro and in vivo
To confirm whether or not inhibition of NF-κB activation is mediated through Mitogen-activated protein kinases (MAPKs) pathways, we examined the effect of SGRS on LPS-stimulated phosphorylation of ERK1/2, Jun NH2-terminal kinase (JNK), and p38 MAPK in RAW264.7 cells

Summary

Introduction

The inflammatory response, a physiological reaction to infection or damage, plays a vital role in the natural defense mechanisms of the body to maintain immune homeostasis[1]. To investigate whether or not the inhibitory effect of SGRS on NO and PGE2 production was due to inhibition of corresponding gene expression, mRNA and protein expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were evaluated by RT-PCR and Western blot assays. We investigated whether or not SGRS inhibits production of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 in LPS-stimulated RAW 264.7 cells by enzyme immunoassay.

Results

Conclusion