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A number of species of the genus Trichilia (Meliaceae) exhibit anti-inflammatory effects. However, the effect of Trichilia martiana C. DC. (TM) on lipopolysaccharide (LPS)-induced inflammation has not, to the best of our knowledge, yet been determined. Therefore, in the present study, the antiinflammatory effect of TM on LPS-stimulated RAW264.7 macrophages was evaluated. The ethanol extract of TM (TMEE) significantly inhibited LPS-induced nitric oxide (NO), prostaglandin 2 (PGE 2), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). TMEE also reduced the levels of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and IL-6. The upregulation of mitogen-activated protein kinases (MAPKs) and NF-κB activation was revealed to be downregulated following TMEE pretreatment. Furthermore, TMEE was indicated to lead to the nucleus translocation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1). In H292 airway epithelial cells, the pretreatment of TMEE significantly downregulated the production of LPS-stimulated IL-1β, and TMEE was indicated to increase the expression of HO-1. In animal models exhibiting LPS-induced acute lung injury (ALI), treatment with TMEE reduced the levels of macrophages influx and TNF-α production in the bronchoalveolar lavage fluid (BALF) of ALI mice. Additionally, TMEE significantly downregulated the activation of ERK, JNK and IκB, and upregulated the expression of HO-1 in the lungs of ALI mice. In conclusion, the results of the current study demonstrated that TMEE could exert a regulatory role in the prevention or treatment of the endotoxin-mediated inflammatory response.

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Background: The type three secretion system (T3SS) is a major virulence system of Pseudomonas aeruginosa (P. aeruginosa). The effector protein Exotoxin S (ExoS) produced by P. aeruginosa is secreted into the host cells via the T3SS. For the purpose of screening the inhibitors with regard to ExoS secretion, we developed the sandwich-type enzyme-linked immunosorbent assay (ELISA) system. From the initial screening, quercetin was selected because it has the prominent effect of ExoS inhibition and also is known to have anti-inflammatory and antioxidant effects on mammalian cells.Results: In this study, we investigated the effects of quercetin on the expression and secretion of ExoS using the ELISA and Western blot analysis methods. The results showed that the secretion of ExoS was significantly decreased by 10, 20uM quercetin. Also, pscF and popD, which are composed of the T3SS needle, are reduced by quercetin at the mRNA level, and we confirmed the inhibitory effect of quercetin on cytokines in P. aeruginosa-infected H292 cells by real-time polymerase chain reaction (PCR). Conclusion: Collectively, quercetin inhibits the secretion of ExoS by reducing both ExoS production and the expression of the needle protein of T3SS. Furthermore, these results suggest that quercetin has the potential to be used as an anti-toxic treatment for the disease caused by P. aeruginosa infection.

Background The type three secretion system (T3SS) is a major virulence system of Pseudomonas aeruginosa (P. aeruginosa). The effector protein Exotoxin S (ExoS) produced by P. aeruginosa is secreted into the host cells via the T3SS. For the purpose of screening the inhibitors with regard to ExoS secretion, we developed the sandwich-type enzyme-linked immunosorbent assay (ELISA) system. From the initial screening, quercetin was selected because it has the prominent effect of ExoS inhibition and also is known to have anti-inflammatory and antioxidant effects on mammalian cells.Results In this study, we investigated the effects of quercetin on the expression and secretion of ExoS using the ELISA and Western blot analysis methods. The results showed that the secretion of ExoS was significantly decreased in a dose-dependent manner by quercetin. Also, pscF and popD, which are composed of the T3SS needle, are reduced by quercetin at the mRNA level, and we confirmed the inhibitory effect of quercetin on cytokines in P. aeruginosa-infected H292 cells by real-time polymerase chain reaction (PCR). Conclusion Collectively, quercetin inhibits the secretion of ExoS by reducing both ExoS production and the expression of the needle protein of T3SS. Furthermore, these results suggest that quercetin has the potential