Mitogen-activated Protein Kinase Pathways In Macrophages Research Articles

Selenium-enriched oolong tea (Camellia sinensis) extract exerts anti-inflammatory potential via targeting NF-κB and MAPK pathways in macrophages

Both tea polyphenols and selenium (Se) have been suggested to exert the health benefits via the regulatory capacities of chronic inflammation, which make Se-enriched oolong tea a promising beverage as an anti-inflammatory diet. The aim of this study is to investigate the anti-inflammatory effects of Se-enriched oolong tea extract (Se-TE) and underlying mechanism in lipopolysaccharide (LPS)-induced RAW264.7 cells. Se-TE treatments (50 and 150 μg/mL) significantly suppressed the over-production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated macrophages via downregulating the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, Se-TEs also effectively inhibited the productions of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). Furthermore, Se-TE could block mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways through the inhibition of the phosphorylation of key proteins (IκB-α, p65, p38, ERK, and JNK) and the translocation of the p65 subunit into the nucleus. Collectively, our results indicated that Se-TE may have the potential to be used as a novel food ingredient for the development of various anti-inflammatory foods and the treatment and prevention of chronic inflammation-related diseases.

Expression of NLRC4 in children with septicaemia and mechanisms of NLRC4 in invitro cytokine secretion.

Septicaemia, a systemic bacterial infection, frequently leads to morbidity and mortality in children. The NOD-like receptor (NLR) family, CARD domain containing4 (NLRC4) is involved in the control of infections. The aim of the present study was to detect the expression of NLRC4 in the blood samples of children with septicaemia, in addition to investigating the importance of NLRC4 in cytokine production, and the signaling pathways that regulate NLRC4 expression in lipopolysaccharide (LPS)-stimulated macrophages. It was determined that when compared with the control, the mRNA and protein expression levels of NLRC4 were significantly increased in the blood samples of children with septicaemia, as demonstrated by the reverse transcription‑quantitative polymerase chain reaction and western blot analysis. The results from the western blotting indicated that treatment with LPS induced NLRC4 expression in a time‑ and dose‑dependent manner in RAW264.7 cells. A knockdown of NLRC4 by siRNA transfection enhanced the effect of LPS on interleukin (IL)‑1β and IL‑18 production, as determined by enzyme‑linked immunosorbent assay. Inhibitors of extracellular regulated protein kinases, c‑Jun N‑terminal kinases and p38 were used in the present study to block the mitogen‑activated protein kinase (MAPK) signaling pathway, and it was determined that LPS‑induced NLRC4 expression was reversed by the suppression of the MAPK signaling pathway. To the best of our knowledge, this is the first report regarding the expression of NLRC4 in children with septicaemia. Furthermore, a novel molecular mechanism for NLRC4 regulation in LPS‑induced RAW264.7 macrophage cells has been elucidated. The data in the present study supports the hypothesis that LPS activates the MAPK pathway in macrophages, thus resulting in the upregulation of NLRC4; however, NLRC4 inhibits IL‑1β and IL‑18 production, contributing to the anti-inflammatory response.

Glucosylceramide attenuates the inflammatory mediator expression in lipopolysaccharide-stimulated RAW264.7 cells

The positive effect of glucosylceramide (GlcCer) on skin conditions is well known. Recently, there has been increasing interest in the potential antiinflammatory effects of GlcCer due to its efficacy in relieving atopic skin symptoms. However, the role of GlcCer in inflammation has not been investigated completely. Thus, we hypothesized that GlcCer might exhibit the antiinflammatory effects through the inhibition of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling. To test this hypothesis, the antiinflammatory effects and signaling mechanisms of GlcCer were investigated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. We report that GlcCer inhibited messenger RNA and protein expression of tissue necrosis factor α and interleukin 1β without cytotoxicity. However, it did not affect interleukin 6 production in LPS-stimulated RAW 264.7 macrophages. Glucosylceramide also suppressed prostaglandin E2 but not nitric oxide production, consistent with its inhibition of cyclooxygenase 2 but not of inducible nitric oxide synthase expression. The molecular mechanism of GlcCer-mediated inhibition of LPS-induced inflammation in RAW 264.7 cells is closely related to suppression of NF-κB p65 subunit nuclear translocation as well as to phosphorylation of extracellular signal-regulated kinase and, in particular, p38 MAPK. In addition, GlcCer did not affect c-Jun N-terminal kinase phosphorylation. In conclusion, GlcCer inhibits LPS-induced inflammation by blocking the nuclear translocation of NF-κB and inhibiting the phosphorylation of extracellular signal-regulated kinase/p38 MAPK pathways in macrophages, suggesting that it might be a promising potential drug candidate for various inflammatory diseases.

Anti-inflammatory effects of trans-1,3-diphenyl-2,3-epoxypropane-1-one mediated by suppression of inflammatory mediators in LPS-stimulated RAW 264.7 macrophages

To assess the potential therapeutic properties of trans-1,3-diphenyl-2,3-epoxypropane-1-one (DPEP), its anti-inflammatory effects were investigated in lipopolysaccharide (LPS)-stimulated mouse macrophage (RAW 264.7) cells. DPEP induced dose-dependent reduction of the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and concomitant reduction in the production of NO and prostaglandin E(2) (PGE(2)). Additionally, DPEP suppressed the production of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. We investigated the mechanism by which DPEP inhibits NO and PGE(2) by examining the level of nuclear factor-κB (NF-κB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation-induced signaling pathway in RAW 264.7 cells. DPEP inhibited LPS-induced phosphorylation of ERK, JNK, and p38. Furthermore, DPEP inhibited the LPS-induced phosphorylation of inhibitor κB (IκB)-α and NF-κB p50. Taken together, the results of this study demonstrate that DPEP inhibits LPS-stimulated inflammation by blocking the NF-κB and MAPK pathways in macrophages.