RESUMO
BACKGROUND: The lack of effective treatments for methicillin-resistant Staphylococcus aureus (MRSA) infection, which often leads to severe acute lung injury (ALI), poses a grave threat to human life. Sophoricoside (SOP), an isoflavone glycoside abundant in the fruit of traditional Chinese herbal Sophora japonica l., showed anti-inflammatory effects against atopic dermatitis, allergic inflammation, and lipopolysaccharide-induced ALI. However, its effect and underlying mechanism on MRSA-induced ALI remain unclear. PURPOSE: The aim of this study is to assess the protective effect of SOP in MRSA-induced ALI and elucidate its underlying molecular mechanisms. METHODS: In vivo experiments were conducted using wild-type mice to establish MRSA-induced ALI mouse model, and the effects of SOP on ALI were evaluated by hematoxylin-eosin staining, flow cytometry, quantitative real-time polymerase chain reaction, and several biochemical indicators. Adoptive transfer experiments and BTB and CNC homology 1 knockout (Bach1-/-) mice were also utilized in this study. In vitro studies employed murine macrophages RAW264.7 cells, primary bone marrow-derived macrophages (BMDMs), and primary lung macrophages to explore the underlying molecular mechanisms. RESULTS: The administration of SOP ameliorated MRSA-induced ALI by improving pulmonary histological damages, reducing neutrophil infiltration, suppressing oxidative stress levels, and decreasing the expression of inflammatory cytokines. In isolation experiments with ALI mouse lung macrophages and macrophage adoptive transfer experiments, SOP prevented macrophage activation, thereby reducing the production of proinflammatory cytokines. In vitro experiments demonstrated that SOP decreased the expression of inflammatory mediators in lipoteichoic acid (LTA)-stimulated RAW264.7 cells, BMDMs, and primary lung macrophages. Additionally, SOP inhibited protein kinase B (Akt) phosphorylation and treatment with MK2206-a specific inhibitor of Akt-eliminated SOP's ability to suppress LTA-stimulated macrophage inflammation. Furthermore, stimulation with LTA or MRSA up-regulated Bach1 expression; however, deletion of Bach1 abolished the inhibitory effect of SOP on p-Akt activation as well as inflammation and ALI development. CONCLUSION: This study provides the first evidence that SOP effectively mitigates MRSA-induced ALI via suppressing macrophage activation through the inhibition of Bach1/Akt pathway. These findings highlight the potential of SOP as a novel therapeutic agent for treating MRSA-induced ALI.
RESUMO
The exploration of light-matter interactions at the sub-wavelength scale requires advanced nano-patterning tools with low cost and high flexibility. Plasmonic lithography as a promising candidate receives much attention owing to its ability to confine ultraviolet light sources into an extremely tiny volume. To date, most plasmonic patterning schemes utilize metallic nano-structures to achieve tight focusing. The drawback is that the plasmonic structures need, however, to be pre-defined, usually accompanied with the expense of complex fabrication processes. Here we numerically and experimentally report an antenna-free plasmonic lithography technique using high numerical aperture (NA) objectives as the scanning head. Minimum feature sizes of 0.36λ/NA and 0.46λ/NA are numerically and experimentally demonstrated, respectively, under the linearly polarized continuous-wave illumination at 457 nm with no involvement of nonlinear effects. Back-focal-plane imaging is used to visualize surface-plasmon excitations, acting as a viable way of adjusting focus precisely. Our method can serve as a candidate for laser processing at the sub-wavelength scale, and offers a truly convenient and economical way of nano-patterning.
