Ergosta-7,9(11),22-trien-3β-ol Attenuates Inflammatory Responses via Inhibiting MAPK/AP-1 Induced IL-6/JAK/STAT Pathways and Activating Nrf2/HO-1 Signaling in LPS-Stimulated Macrophage-like Cells.

Yi-Ping Huang,Yu-Hsien Lin,Te-Chun Hsia,Wen-Tsong Hsieh,Jing-Gung Chung,Jiann-Yeu Chen,Yueh-Hsiung Kuo,Wen-Jen Lin,Dar-Ren Chen

doi:10.3390/antiox10091430

Abstract

Chronic inflammation induces autoimmune disorders and chronic diseases. Several natural products activate nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, attenuating inflammatory responses. Ergosta-7,9(11),22-trien-3β-ol (EK100) isolated from Cordyceps militaris showed anti-inflammatory and antioxidative activity, but those mechanisms are still unclear. This study is the first to investigate EK100 on antioxidant Nrf2 relative genes expression in LPS-stimulated macrophage-like cell lines. The results showed that EK100 reduced IL-6 (interleukin-6) and tumor necrosis factor-α production. EK100 also attenuated a mitogen-activated protein kinase/activator protein-1 (MAPK/AP-1) pathway and interleukin-6/Janus kinase/signal transducer and activator of transcription (IL-6/JAK/STAT) pathway in LPS-stimulated cells. Toll-like receptor 4 (TLR4) inhibitor CLI-095 and MAPK inhibitors can synergize the anti-inflammatory response of EK100 in LPS-stimulated cells. Moreover, EK100 activated Nrf2/HO-1 (heme oxygenase-1) signaling in LPS-stimulated murine macrophage-like RAW 264.7 cells, murine microglial BV2 cells, and human monocytic leukemia THP-1 cells. However, Nrf2 small interfering RNA (Nrf2 siRNA) reversed EK100-induced antioxidative proteins expressions. In conclusion, EK100 showed anti-inflammatory responses via activating the antioxidative Nrf2/HO-1 signaling and inhibiting TLR4 related MAPK/AP-1 induced IL-6/JAK/STAT pathways in the LPS-stimulated cells in vitro. The results suggest EK100 acts as a novel antioxidant with multiple therapeutic targets that can potentially be developed to treat chronic inflammation-related diseases.

Highlights

Chronic inflammation primes several autoimmune diseases and neurodegenerative disorders, leading to cause disability and mortality worldwide [1]
IL-6 binding to the transmembrane IL-6 receptor and subsequent activation of Janus kinase (JAK), which is following the phosphorylation of the signal transducer and activator of transcription (STAT) 1/3 and the activated STAT complex will translocate from the cytoplasm to the cellular nucleus initiating transcription of STAT3 target genes [6]
The results indicated that LPS induced the production of IL-6 and tumor necrosis factor-α (TNF-α) in RAW

Summary

Introduction

Chronic inflammation primes several autoimmune diseases and neurodegenerative disorders, leading to cause disability and mortality worldwide [1]. The other studies described the Kelch-like ECH-associated protein/nuclear factor erythroid 2-related factor. 2/antioxidant responsive element (Keap1/Nrf2/ARE) signaling pathways to regulate antioxidant gene expression and inhibit the progression of inflammation [2]. Nrf suppresses pro-inflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6) by blocking the transcription factor nuclear factor-kappa B (NF-κB) inflammatory response in macrophage cells [3]. MAPK signaling induced the release of tumor necrosis factor-α (TNF-α) and interleukin (IL-6) [5]. IL-6 binding to the transmembrane IL-6 receptor and subsequent activation of Janus kinase (JAK), which is following the phosphorylation of the signal transducer and activator of transcription (STAT) 1/3 and the activated STAT complex will translocate from the cytoplasm to the cellular nucleus initiating transcription of STAT3 target genes [6]

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