Caragana rosea Turcz Methanol Extract Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Suppressing the TLR4/NF-κB/IRF3 Signaling Pathways.

Ankita Mitra,Laily Rahmawati,Byoung Young Woo,Zhiyun Zhang,Jongsung Lee,Han Gyung Kim,Yong Deog Hong,Jong-Hoon Kim,Akash Ahuja,Mohammad Amjad Hossain,Soo-Yong Kim,Jae Youl Cho

doi:10.3390/molecules26216660

Abstract

Caragana rosea Turcz, which belongs to the Leguminosae family, is a small shrub found in Northern and Eastern China that is known to possess anti-inflammatory properties and is used to treat fever, asthma, and cough. However, the underlying molecular mechanisms of its anti-inflammatory effects are unknown. Therefore, we used lipopolysaccharide (LPS) in RAW264.7 macrophages to investigate the molecular mechanisms that underlie the anti-inflammatory activities of a methanol extract of Caragana rosea (Cr-ME). We showed that Cr-ME reduced the production of nitric oxide (NO) and mRNA levels of iNOS, TNF-α, and IL-6 in a concentration-dependent manner. We also found that Cr-ME blocked MyD88- and TBK1-induced NF-κB and IRF3 promoter activity, suggesting that it affects multiple targets. Moreover, Cr-ME reduced the phosphorylation levels of IκBα, IKKα/β and IRF3 in a time-dependent manner and regulated the upstream NF-κB proteins Syk and Src, and the IRF3 protein TBK1. Upon overexpression of Src and TBK1, Cr-ME stimulation attenuated the phosphorylation of the NF-κB subunits p50 and p65 and IRF3 signaling. Together, our results suggest that the anti-inflammatory activity of Cr-ME occurs by inhibiting the NF-κB and IRF3 signaling pathways.

Highlights

The immune system comprises many types of cells, such as macrophages, fibroblasts, dendritic cells, and mast cells, to identify invading pathogens using intracellular or surfaceexpressed pattern recognition receptors (PRRs) [1]
To evaluate whether Caragana rosea methanol extract (Cr-ME) suppresses secreted inflammatory mediators during an inflammatory response, we examined nitric oxide (NO) production in RAW264.7 macrophages treated with different concentrations of Cr-ME in the presence or absence of LPS, poly(I:C), and pam3csk for 24 h
Our results show that Cr-ME dose-dependently diminishes the NO production induced in macrophages by LPS, pam3CSK, and poly(I:C) stimulation without influencing cell viability (Figure 1a,e)

Summary

Introduction

The immune system comprises many types of cells, such as macrophages, fibroblasts, dendritic cells, and mast cells, to identify invading pathogens using intracellular or surfaceexpressed pattern recognition receptors (PRRs) [1]. These PRRs, such as toll-like receptors (TLRs), are important for proper functioning of the innate immune response. Studies have shown the NF-κB and IRF3 signaling pathways involve the IκB kinase [7,8]. The NF-κB and IRF3 signaling pathways interact with genes at the promotor level [5]. The functionality of the innate immune response relies on cooperation between the NF-κB and IRF3 signaling pathways, which are highly interconnected [9]

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Results

Discussion

Conclusion