[Research progress on liposome and nanomicelle targeted drug delivery system across blood-brain barrier].

The blood-brain barrier(BBB), a protective barrier between brain tissues and brain capillaries, can prevent drugs from entering the brain tissues to exert the effect, which greatly increases the difficulty in treating brain diseases. The drug delivery system across the BBB can allow efficient drug delivery across the BBB by virtue of carriers and formulations, thereby enhancing the therapeutic effect of drugs on brain tissue diseases. Liposomes and micelles have been extensively studied with advances in the targeted therapy across the BBB for the brain due to their unique structures and drug delivery advantages. This study summarized the research status of liposome and micelle drug delivery systems across the BBB based on the literature in recent years and analyzed their application advantages and mechanism in terms of trans-BBB capability, targeting, and safety. Moreover, the problems and possible countermeasures in the research on trans-BBB liposomes and micelles were discussed according to the current clinical translation, which may provide refe-rences and ideas for the development of trans-BBB targeted nano-drugs.

CD-g-CS nanoparticles for enhanced antibiotic treatment of Staphylococcus xylosus infection.

Staphylococcus xylosus (S. xylosus)-induced cow mastitis is an extremely serious clinical problem. However, antibiotic therapy does not successfully treat S. xylosus infection because these bacteria possess a strong biofilm formation ability, which significantly reduces the efficacy of antibiotic treatments. In this study, we developed ceftiofur-loaded chitosan grafted with ß-cyclodextrins (CD-g-CS) nanoparticles (CT-NPs) using host-guest interaction. These positively charged nanoparticles improved bacterial internalization, thereby significantly improving the effectiveness of antibacterial treatments for planktonic S. xylosus. Moreover, CT-NPs effectively inhibited biofilm formation and eradicated mature biofilms. After mammary injection in a murine model of S. xylosus-induced mastitis, CT-NPs significantly reduced bacterial burden and alleviated inflammation, thereby achieving optimized therapeutic efficiency for S. xylosus infection. In conclusion, this treatment strategy could improve the efficiency of antibiotic therapeutics and shows great potential in the treatment of S. xylosus infections.

The Active Ingredients Identification and Antidiarrheal Mechanism Analysis of Plantago asiatica L. Superfine Powder.

Plantago asiatica L. is a natural medicinal plant that has been widely used for its various pharmacological effects such as antidiarrheal, anti-inflammatory, and wound healing. This study aims to explore the antidiarrheal active ingredients of Plantago asiatica L. that can be used as quality markers to evaluate P. asiatica L. superfine powder (PSP). Molecular docking experiment was performed to identify the effective components of P. asiatica L., which were further evaluated by an established mouse diarrhea model. Na+/K+-ATPase and creatine kinase (CK) activities and the Na+/K+ concentrations were determined. The gene expression of ckb and Atp1b3 was detected. PSP was prepared and evaluated in terms of the tap density and the angle of repose. The structures of PSPs of different sizes were measured by infrared spectra. The active ingredient contents of PSPs were determined by HPLC. The results indicated that the main antidiarrheal components of P. asiatica L. were luteolin and scutellarein that could increase the concentration of Na+ and K+ by upregulating the activity and gene level of CK and Na+/K+-ATPase. In addition, luteolin and scutellarein could also decrease the volume and weight of small intestinal contents to exert antidiarrheal activity. Moreover, as the PSP size decreased from 6.66 to 3.55 µm, the powder tended to be amorphous and homogenized and of good fluidity, the content of active compounds gradually increased, and the main structure of the molecule remained steady. The optimum particle size of PSP with the highest content of active components was 3.55 µm, and the lowest effective dose for antidiarrhea was 2,000 mg/kg. Therefore, the antidiarrheal active ingredients of PSP were identified as luteolin and scutellarein that exert antidiarrheal activity by binding with Na+/K+-ATPase. PSP was successfully prepared and could be used as a new dosage form for the diarrhea treatment.

Transcriptomic analysis reveals flavonoid biosynthesis of Syringa oblata Lindl. in response to different light intensity.

BACKGROUND: Hazy weather significantly increase air pollution and affect light intensity which may also affect medicinal plants growth. Syringa oblata Lindl. (S. oblata), an effective anti-biofilm medicinal plants, is also vulnerable to changes in plant photoperiods and other abiotic stress responses. Rutin, one of the flavonoids, is the main bioactive ingredient in S. oblata that inhibits Streptococcus suis biofilm formation. Thus, the present study aims to explore the biosynthesis and molecular basis of flavonoids in S. oblata in response to different light intensity. RESULTS: In this study, it was shown that compared with natural (Z0) and 25% ~ 35% (Z2) light intensities, the rutin content of S. oblata under 50% ~ 60% (Z1) light intensity increased significantly. In addition, an integrated analysis of metabolome and transcriptome was performed using light intensity stress conditions from two kinds of light intensities which S. oblata was subjected to: Z0 and Z1. The results revealed that differential metabolites and genes were mainly related to the flavonoid biosynthetic pathway. We found out that 13 putative structural genes and a transcription factor bHLH were significantly up-regulated in Z1. Among them, integration analysis showed that 3 putative structural genes including 4CL1, CYP73A and CYP75B1 significantly up-regulated the rutin biosynthesis, suggesting that these putative genes may be involved in regulating the flavonoid biosynthetic pathway, thereby making them key target genes in the whole metabolic process. CONCLUSIONS: The present study provided helpful information to search for the novel putative genes that are potential targets for S. oblata in response to light intensity.

Process optimization of Syringa oblata Lindl. by response surface methodology and its effect on Staphylococcus xylosus biofilm.

Syringa oblata Lindl. (S. oblata) is a medicinal plant with effective broad-spectrum antibacterial activity, which can also inhibit Streptococcus suis biofilm formation. The processing of herbal medicine can purify medicinal materials, provide acceptable taste, reduce toxicity, enhance efficacy, influence performance and facilitate preparation. Thus, the aim of this study was to enhance the biofilm inhibition activity of S. oblata toward Staphylococcus xylosus (S. xylosus) using the best processing method. The content of rutin and flavonoids and the ability to inhibit the biofilm formation by S. oblata were examined using four processing methods. One of the best methods, the process of stir-frying S. oblata with vinegar, was optimized based on the best rutin content by response surface methodology. The histidine content and hisB gene expression of S. xylosus biofilm in vitro, resulting from stir-frying S. oblata with vinegar, were evaluated and were found to be significantly decreased and down-regulated, respectively. The results show that S. oblata stir-fried with vinegar can be used to effectively treat diseases resulting from S. xylosus infection. This is because it significantly inhibited S. xylosus biofilm formation by interfering with the biosynthesis of histidine; thus, its mechanism of action is decreasing histidine synthesis.

Spectrum-Effect Relationships Between the Bioactive Ingredient of Syringa oblata Lindl. Leaves and Its Role in Inhibiting the Biofilm Formation of Streptococcus suis.

Syringa oblata Lindl. (S. oblata) has been used in herbal medicines for treating bacterial diseases. It is also thought to inhibit Streptococcus suis (S. suis) biofilm formation. However, due to the inherent nature of the complexity in its chemical properties, it is difficult to understand the possible bioactive ingredients of S. oblata. The spectrum-effect relationships method was applied to screen the main active ingredients in S. oblata obtained from Heilongjiang Province based on gray relational analysis. The results revealed that Sub-MICs obtained from 10 batches of S. oblata could inhibit biofilm formation by S. suis. Gray relational analysis revealed variations in the contents of 15 main peaks and rutin was discovered to be the main active ingredient. Then, the function of rutin was further verified by inhibiting S. suis biofilm formation using crystal violet staining. Computational studies revealed that rutin may target the chloramphenicol acetyltransferase protein in the biofilm formation of S. suis. In conclusion, this study revealed that the spectrum-effect relationships and computational studies are useful tools to associate the active ingredient with the potential anti-biofilm effects of S. oblata. Here, our findings would provide foundation for the further understanding of the mechanism of S. oblata intervention in biofilm formation.

Inhibition of Streptococcus suis Adhesion and Biofilm Formation in Vitro by Water Extracts of Rhizoma Coptidis.

Streptococcus suis is difficult to treat and responsible for various infections in humans and pigs. It can also form biofilms and induce persistent infections. Rhizoma Coptidis is a medicinal plant widely used in Traditional Chinese Medicine. Although the inhibitory effects of Rhizoma Coptidis on biofilm formation have been investigated in several studies, the ability of Rhizoma Coptidis to inhibit S. suis biofilm formation and the underlying mechanisms have not yet been reported. In this study, we showed that sub-minimal inhibitory concentrations (25 and 50 µg mL-1) of water extracts of Rhizoma Coptidis (Coptis deltoidea C.Y.Cheng & P.K.Hsiao, obtained from Sichuan Province) were sufficient to inhibit biofilm formation, as shown in the tissue culture plate (TCP) method and scanning electron microscopy. Real-time PCR and iTRAQ were used to measure gene and protein expression in S. suis. Sub-minimum inhibitory concentrations (25 and 50 µg mL-1) of Rhizoma Coptidis water extracts inhibited S. suis adhesion significantly in an anti-adherence assay. Some genes, such as gapdh, sly, and mrp, and proteins, such as antigen-like protein, CPS16V, and methyltransferase H, involved in adhesion were significantly modulated in cells treated with 50 µg mL-1 of Rhizoma Coptidis water extracts compared to untreated cells. The results from this study suggest that compounds in Rhizoma Coptidis water extracts play an important role in inhibiting adhesion of S. suis cells and, therefore, biofilm formation.

Histidine Metabolism and IGPD Play a Key Role in Cefquinome Inhibiting Biofilm Formation of Staphylococcus xylosus.

Staphylococcus xylosus (S. xylosus) is an AT-rich and coagulase-negative Staphylococcus (CNS). It is normally regarded as non-pathogenic, however, recent studies have demonstrated that it is related to human opportunistic infections and bovine mastitis. In addition, S. xylosus strains have the ability to form biofilm. Biofilms are also involved in chronic infections and antibiotic resistance, there are only a few reports about cefquinome inhibiting S. xylosus biofilm formation and the protein targets of cefquinome. In our study, we found that sub-MICs of cefquinome were sufficient to inhibit biofilm formation. To investigate the potential protein targets of cefquinome, we used iTRAQ for the analyses of cells at two different conditions: 1/2-MIC (0.125 µg/mL) cefquinome treatment and no treatment. Using iTRAQ technique and KEGG database analysis, we found that proteins differently expression in histidine metabolism pathway may play a role in the process by which 1/2-MIC (0.125 µg/mL) cefquinome inhibits S. xylosus biofilm formation. Interestingly, we found a sharply down-regulated enzyme [A0A068E9J3 imidazoleglycerol-phosphate dehydratase (IGPD)] involved in histidine metabolism pathway in cefquinome-treated cells. We demonstrated the important role of IGPD in sub-MICs cefquinome inhibiting biofilm formation of S. xylosus by gene (hisB) knockout, IGPD enzyme activity and histidine content assays. Thus, our data sheds light on important role of histidine metabolism in S. xylosus biofilm formation; especially, IGPD involved in histidine metabolism might play a crucial role in sub-MICs cefquinome inhibition of biofilm formation of S. xylosus, and we propose IGPD as an attractive protein target of cefquinome.

Chitosan Grafted With ß-Cyclodextrin: Synthesis, Characterization, Antimicrobial Activity, and Role as Absorbefacient and Solubilizer.

We synthesized chitosan grafted with ß-cyclodextrin (CD-g-CS) from mono-6-deoxy-6-(p-toluenesulfonyl)-ß-cyclodextrin and chitosan. Two different amounts of immobilized ß-cyclodextrin (ß-CD) on CD-g-CS (QCD: 0.643 × 103 and 0.6 × 102 µmol/g) were investigated. The results showed that the amino contents of CD-g-CS with QCD = 0.643 × 103 and 0.6 × 102 µmol/g were 6.34 ± 0.072 and 9.41 ± 0.055%, respectively. Agar diffusion bioassay revealed that CD-g-CS (QCD = 0.6 × 102 µmol/g) was more active against Staphylococcus xylosus and Escherichia coli than CD-g-CS (QCD = 0.643 × 103 µmol/g). Cell membrane integrity tests and scanning electron microscopy observation revealed that the antimicrobial activity of CD-g-CS was attributed to membrane disruption and cell lysis. Uptake tests showed that CD-g-CS promoted the uptake of doxorubicin hydrochloride by S. xylosus, particularly for CD-g-CS with QCD = 0.6 × 102 µmol/g, and the effect was concentration dependent. CD-g-CS (QCD = 0.6 × 102 and 0.643 × 103 µmol/g) also improved the aqueous solubilities of sulfadiazine, sulfamonomethoxine, and sulfamethoxazole. These findings provide a clear understanding of CD-g-CS and are of great importance for reducing the dosage of antibiotics and antibiotic residues in animal-derived foods. The results also provide a reliable, direct, and scientific theoretical basis for its wide application in the livestock industry.

Sub-Minimum Inhibitory Concentrations of Rhubarb Water Extracts Inhibit Streptococcus suis Biofilm Formation.

Streptococcus suis is one of the most important swine pathogens, which can cause persistent infection by forming biofilms. In this study, sub-minimum inhibitory concentration (sub-MIC) of rhubarb water extracts were found to inhibit biofilm formation. Two-component signal transduction systems (TCSs), transcriptional regulators, and DNA binding proteins were compared under two conditions: (1) cells treated with sub-MIC rhubarb water extracts and (2) untreated cells. Using an isobaric tags for relative and absolute quantitation (iTRAQ) strategy, we found that TCSs constituent proteins of histidine kinase and response regulator were significantly down-regulated. This down-regulation can affect the transfer of information during biofilm formation. The transcriptional regulators and DNA binding proteins that can interact with TCSs and interrupt gene transcription were also significantly altered. For these reasons, the levels of protein expressions varied in different parts of the treated vs. untreated cells. In summary, rhubarb water extracts might serve as potential inhibitor for the control of S. suis biofilm formation. The change in TCSs, transcriptional regulators, and DNA binding proteins may be important factors in S. suis biofilm inhibition.

Sub-MICs of Azithromycin Decrease Biofilm Formation of Streptococcus suis and Increase Capsular Polysaccharide Content of S. suis.

Streptococcus suis (S. suis) caused serious disease symptoms in humans and pigs. S. suis is able to form thick biofilms and this increases the difficulty of treatment. After growth with 1/2 minimal inhibitory concentration (MIC) of azithromycin, 1/4 MIC of azithromycin, or 1/8 MIC of azithromycin, biofilm formation of S. suis dose-dependently decreased in the present study. Furthermore, scanning electron microscopy analysis revealed the obvious effect of azithromycin against biofilm formation of S. suis. Especially, at two different conditions (1/2 MIC of azithromycin non-treated cells and treated cells), we carried out comparative proteomic analyses of cells by using iTRAQ technology. Finally, the results revealed the existence of 19 proteins of varying amounts. Interestingly, several cell surface proteins (such as ATP-binding cassette superfamily ATP-binding cassette transporter (G7SD52), CpsR (K0FG35), Cps1/2H (G8DTL7), CPS16F (E9NQ13), putative uncharacterized protein (G7SER0), NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (G5L259), putative uncharacterized protein (G7S2D6), amino acid permease (B0M0G6), and NsuB (G5L351)) were found to be implicated in biofilm formation. More importantly, we also found that azithromycin affected expression of the genes cps1/2H, cpsR and cps16F. Especially, after growth with 1/2 MIC of azithromycin and 1/4 MIC of azithromycin, the capsular polysaccharide content of S. suis was significantly higher.