Alnustone inhibits Streptococcus pneumoniae virulence by targeting pneumolysin and sortase A.

Streptococcus pneumoniae (S. pneumoniae) is a major Gram-positive opportunistic pathogen that causes pneumonia, bacteremia, and other fatal infections. This bacterium is responsible for more deaths than any other single pathogen in the world. Inexplicably, these symptoms persist despite the administration of effective antibiotics. Targeting pneumolysin (PLY) and sortase A (SrtA), the major virulence factors of S. pneumoniae, this study uncovered a novel resistance mechanism to S. pneumoniae infection. Using protein phenotype assays, we determined that the small molecule inhibitor alnustone is a potent drug that inhibits both PLY and SrtA. As essential virulence factors of S. pneumoniae, PLY and SrtA play a significant role in the occurrence of infection. Furthermore, evaluation using PLY-mediated hemolysis assay demonstrated alunstone had the potential to interrupt the haemolytic activity of PLY with treatment alunstone (4 µg/ml). Co-incubation of S. pneumoniae D39 SrtA with small-molecule inhibitors decreases cell wall-bound Nan A (pneumococcal-anchored surface protein SrtA), inhibits biofilm formation, and reduces biomass significantly. The protective effect of invasive pneumococcal disease (IPD) on murine S. pneumoniae was demonstrated further. Our study proposes a comprehensive bacteriostatic mechanism for S. pneumoniae and highlights the significant translational potential of targeting both PLY and SrtA to prevent pneumococcal infections. Our findings indicate that the antibacterial strategy of directly targeting PLY and SrtA with alnustone is a promising treatment option for S. pneumoniae and that alnustone is a potent inhibitor of PLY and SrtA.

Pretreatment with the compound asperuloside decreases acute lung injury via inhibiting MAPK and NF-κB signaling in a murine model.

Asperuloside, an iridoid glycoside found in Herba Paederiae, is a component from traditional Chinese herbal medicine. In this study, we aimed to investigate the protective effects and potential mechanisms of asperuloside action on inflammatory responses in lipopolysaccharide (LPS)-stimulated Raw 264.7 cells and an LPS-induced lung injury model. The pro-inflammatory cytokines and signaling pathways were measured by enzyme-linked immunosorbent assays (ELISA) and Western blotting to determine the effects of asperuloside. We found that asperuloside can significantly downregulate tumor necrosis factor alpha (TNF-α), interleukin (IL)-1ß, and IL-6 levels in vitro and in vivo, and treatment with asperuloside significantly reduced the lung wet-to-dry weight, histological alterations and myeloperoxidase activity in a murine model of LPS-induced acute lung injury (ALI). In addition, Western blot analysis that pretreatment with asperuloside remarkably blunted the phosphorylation of inhibitor of nuclear factor kappa-B (IκBα), extracellular signal-related kinases 1 and 2 (ERK1/2), c-Jun. N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK) in LPS-stimulated inflammation. These results indicate that asperuloside exerts its anti-inflammatory effect in correlation with inhibition of a pro-inflammatory mediator through suppressing nuclear factor kappa-B (NF-κB) nuclear translocation and MAPK phosphorylation in a dose-dependent manner.

D(-)-Salicin inhibits the LPS-induced inflammation in RAW264.7 cells and mouse models.

D(-)-Salicin is a traditional medicine which has been known to exhibit anti-inflammation and other therapeutic activities. The present study aimed to investigate whether D(-)-Salicin inhibited the LPS-induced inflammation in vivo and in vitro. We evaluated the effect of D(-)-Salicin on cytokines (TNF-α, IL-1ß, IL-6 and IL-10) in vivo and in vitro by enzyme-linked immunosorbent assay and signaling pathways (MAPKs and NF-κB) in vivo by Western blot. The results showed that D(-)-Salicin markedly decreased TNF-α, IL-1ß and IL-6 concentrations and increased IL-10 concentration. In addition, western blot analysis indicated that D(-)-Salicin suppressed the activation of MAPKs and NF-κB signaling pathways stimulated by LPS. To examine whether D(-)-Salicin ameliorated LPS-induced lung inflammation, inhibitors of MAPKs and NF-κB signaling pathways were administrated intraperitoneally to mice. Interference with specific inhibitors revealed that D(-)-Salicin-mediated cytokine suppression was through MAPKs and NF-κB pathways. In the mouse model of acute lung injury, histopathologic examination indicted that D(-)-Salicin suppressed edema induced by LPS. So it is suggest that D(-)-Salicin might be a potential therapeutic agent against inflammatory diseases.

Traditional medicine alpinetin inhibits the inflammatory response in Raw 264.7 cells and mouse models.

Alpinetin, one of the main constituents of the seeds of Alpinia katsumadai Hayata, belonging to flavonoids, has been known to exhibit antibacterial, anti-inflammatory and other important therapeutic activities. The purpose of this study was to investigate the protection of alpinetin on inflammation in Lipopolysaccharide (LPS) stimulated Raw 264.7 cells and LPS induced vivo lung injury model. The effects of alpinetin on pro-inflammatory cytokines and signaling pathways were analyzed by enzyme-linked immunosorbent assay and Western blot. The results showed that alpinetin markedly inhibited the LPS- induced TNF-α, IL-6 and IL-1ß production both in vitro and vivo. Furthermore, alpinetin blocked the phosphorylation of IκBα protein, p65, p38 and extracellular signal-regulated kinase (ERK) in LPS stimulated RAW 264.7 cells. From in vivo study, it was also observed that alpinetin attenuated lung histopathologic changes in mouse models. These results suggest that alpinetin potentially decreases the inflammation in vitro and vivo, and might be a therapeutic agent against inflammatory diseases.