Action of tubercidin and other adenosine analogs on Schistosoma mansoni schistosomules

The incorporation of the radiolabeled adenosine analogs tubercidin, formycin A, 9-deaza-adenosine, and adenine arabinoside into nucleotides of Schistosoma mansoni schistosomules was studied in vitro. Of the four analogs, only tubercidin and formycin A were incorporated into the nucleotide pool, at rates respectively one-tenth and one-fiftieth the rate of adenosine incorporation. Tubercidin inhibited schistosomule motility in vitro with an approximate IC50 value of 1 microM, whereas formycin A exerted no visible effect even when more of it than of tubercidin was incorporated into the nucleotides and nucleic acids. Formycin A thus acts like a nontoxic adenosine analog. 7-Deaza-adenine, the purine base of tubercidin, was not incorporated into nucleotides. 7-Deaza-adenine, 9-deaza-adenosine, and adenine arabinoside all had no effect on schistosomule motility at concentrations up to 100 microM. Formycin A blocked the incorporation of tubercidin and of adenosine with equal effectiveness, as did p-nitrobenzyl-6-mercaptopurine ribonucleoside, a specific inhibitor of nucleoside transport in many mammalian cells. Thus, formycin A, tubercidin, and adenosine appear to have a common mechanism of cellular uptake. The significant levels of adenosine phosphorylase and adenine phosphoribosyl transferase activity found in schistosomule extracts suggests that most of the transported adenosine is converted to adenine before conversion to AMP. The levels of adenosine kinase and tubercidin kinase, while low, can more than account for the rate of tubercidin incorporated into intact schistosomules. The kinase(s) may also represent a minor pathway for direct adenosine incorporation. It may have a rather unusual substrate specificity because it is able to recognize adenosine, tubercidin, and formycin A as substrates, but not 9-deaza-adenosine or adenine arabinoside.     

A size-shrinkable matrix metallopeptidase-2-sensitive delivery nanosystem improves the penetration of human programmed death-ligand 1 siRNA into lung-tumor spheroids

Given the maturation of small-interfering RNA (siRNA) techniques with nanotechnology, and because overexpression of human programmed death-ligand 1 (PD-L1) is crucial for T cell inactivation and immunosuppression of the tumor microenvironment, application of siRNA–PD-L1 has demonstrated positive progress in preclinical studies; however, the limited penetration of this compound into solid tumors remains a challenge. To decrease PD-L1 expression and increase the penetration efficacy of solid tumors, we synthesized a novel tumor-microenvironment-sensitive delivery polymer by conjugating hyaluronic acid (HA) to polyethyleneimine (PEI), with a matrix metalloproteinase-2 (MMP-2)-sensitive peptide acting as the linker (HA-P-PEI), for use in delivery of PD-L1–siRNA. Concurrent synthesis of a linker-less HA-PEI compound allowed confirmation that negatively charged siRNA can be complexed onto the positively charged HA-PEI and HA-P-PEI compounds to form nanoparticles with the same particle size and uniform distribution with serum stability. We found that the size of the HA-P-PEI/siRNA nanoparticles decreased to <10 nm upon addition of MMP-2, and that H1975 cells overexpressing CD44, PD-L1, and MMP-2 aided confirmation of the delivery efficacy of the HA-P-PEI/siRNA nanocomplexes. Additionally, the use of HA-P-PEI caused less cytotoxicity than PEI alone, demonstrating its high cellular uptake. Moreover, pretreatment with MMP-2 increased nanocomplex tumor permeability, and western blot showed that HA-P-PEI/PD-L1–siRNA efficiently downregulated the PD-L1 expression in H1975 cells. These results demonstrated a novel approach for siRNA delivery and tumor penetration for future clinical applications in cancer treatment.     

Silver Nanoparticles–Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media

The use of face masks and air purification systems has been key to curbing the transmission of SARS-CoV-2 aerosols in the context of the current COVID-19 pandemic. However, some masks or air conditioning filtration systems are designed to remove large airborne particles or bacteria from the air, being limited their effectiveness against SARS-CoV-2. Continuous research has been aimed at improving the performance of filter materials through nanotechnology. This article presents a new low-cost method based on electrostatic forces and coordination complex formation to generate antiviral coatings on filter materials using silver nanoparticles and polyethyleneimine. Initially, the AgNPs synthesis procedure was optimized until reaching a particle size of 6.2 ± 2.6 nm, promoting a fast ionic silver release due to its reduced size, obtaining a stable colloid over time and having reduced size polydispersity. The stability of the binding of the AgNPs to the fibers was corroborated using polypropylene, polyester-viscose, and polypropylene-glass spunbond mats as substrates, obtaining very low amounts of detached AgNPs in all cases. Under simulated operational conditions, a material loss less than 1% of nanostructured silver was measured. SEM micrographs demonstrated high silver distribution homogeneity on the polymer fibers. The antiviral coatings were tested against SARS-CoV-2, obtaining inactivation yields greater than 99.9%. We believe our results will be beneficial in the fight against the current COVID-19 pandemic and in controlling other infectious airborne pathogens.     

Phosphorothioated antisense oligodeoxynucleotide suppressing interleukin-10 is a safe and potent vaccine adjuvant

While vaccination is highly effective for the prevention of many infectious diseases, the number of adjuvants licensed for human use is currently very limited. The aim of this study was to evaluate the safety, efficacy, and to clarify the mechanism of a phosphorothioated interleukin (IL)-10-targeted antisense oligonucleotide (ASO) as an immune adjuvant in intradermal vaccination. The cytotoxicity of IL-10 ASO and its ability to promote T cell proliferation were assessed by Cell Counting Kit-8 (CCK-8) assay. The contents of IL-6, IL-8, TNF-α, IL-1β, and IL-10 in inoculated local tissue and the antigen-specific antibody titers in mouse serum samples were determined by ELISA. The target cells of IL-10 ASO were observed using immunofluorescent staining. The results showed that the specific antibody titer of ovalbumin (OVA), a model antigen, was increased 100-fold upon addition of IL-10 ASO as an adjuvant compared to that of OVA alone. IL-10 ASO showed an immunopotentiation efficacy similar to that of Freund’s incomplete adjuvant, with no detectable cell or tissue toxicity. In vitro and in vivo experiments confirmed that IL-10 ASO enhances immune responses by temporarily suppressing IL-10 expression from local dendritic cells and consequently promoting T cell proliferation. In conclusion, IL-10 ASO significantly enhances immune responses against co-delivered vaccine antigens with high efficacy and low toxicity. It has the potential to be developed into a safe and efficient immune adjuvant.     

Polyamine-Promoted Growth of One-Dimensional Nanostructure-Based Silica and Its Feature in Catalyst Design

Crystalline linear polyethyleneimine (LPEI) is a fascinating polymer that can be used as a catalyst, template and scaffold in order to direct the formation of silica with controllable compositions and spatial structures under mild conditions. Considering the crystallization and assembly of LPEI is temperature-dependent, we adopted different accelerated cooling processes of a hot aqueous solution of LPEI in order to modulate the LPEI crystalline aggregates. We then used them in the hydrolytic condensation of alkoxysilane. A series of silica with nanofibrils, nanotubes and nanowire-based structures were achieved simply by the LPEI aggregates which were pre-formed in defined cooling processes. These specific one-dimensional nanoscale structures assembled into microscale fibers-, sheet- and platelet-like coalescences. Furthermore, the deposition kinetics was also researched by the combination of other characterizations (e.g., pH measurement, ²⁹Si MAS NMR). As a preliminary application, the hybrids of LPEI@SiO₂ were used not only as an agent for reducing PtCl₄²⁻ into Pt but also as host for loading Pt nanoparticles. The Pt-loaded silica showed good catalytic properties in the reduction of Rhodamine B by dimethylaminoborane (DMAB).     

线粒体靶向聚合物TPP-PEI-LND的构建及其特性

以低相对分子质量聚乙烯亚胺(PEI)为骨架,将线粒体靶向基团三苯基膦(TPP)和化疗药物氯尼达明(LND)以酰胺键接枝到PEI上,构建线粒体靶向聚合物TPP-PEI-LND。TPP-PEI-LND经¹H NMR确证。采用透析法考察TPP-PEI-LND的体外释放。采用HeLa细胞研究TPP-PEI-LND的线粒体靶向能力和细胞毒性。结果显示,TPP-PEI-LND线粒体靶向聚合物制备成功,其释药行为呈现缓释特点,并可以靶向递送药物到达线粒体,显著增强药物对肿瘤细胞的疗效。     

CA/PEI亲和膜去除肝硬化腹水中内毒素及胆红素的研究

目的研究CA/PEI亲和膜对肝硬化腹水中内毒素及胆红素的去除效果。方法以醋酸纤维素（CA）为亲和基质,交联聚乙烯基亚胺（PEI）,制备CA/PEI亲和膜;采用动态吸附法,比较吸附前后肝硬化腹水中内毒素、胆红素、白蛋白、免疫球蛋白（IgG、IgA、IgM）及离子（K^＋、Na^＋、Cl^-）浓度的变化。结果CA/PEI亲和膜吸附前后腹水中的内毒素及胆红素浓度显著降低（P（0.01）;腹水中的白蛋白、免疫球蛋白、电解质浓度过膜前后无明显变化。结论CA/PEI亲和膜能有效吸附肝硬化腹水中的内毒素及胆红素,对腹水中的白蛋白、免疫球蛋白、电解质无明显截留,可应用于肝硬化自体腹水回输治疗。     

Polyethyleneimine-Based Lipopolyplexes as Carriers in Anticancer Gene Therapies

Recent years have witnessed rapidly growing interest in application of gene therapies for cancer treatment. However, this strategy requires nucleic acid carriers that are both effective and safe. In this context, non-viral vectors have advantages over their viral counterparts. In particular, lipopolyplexes—nanocomplexes consisting of nucleic acids condensed with polyvalent molecules and enclosed in lipid vesicles—currently offer great promise. In this article, we briefly review the major aspects of developing such non-viral vectors based on polyethyleneimine and outline their properties in light of anticancer therapeutic strategies. Finally, examples of current in vivo studies involving such lipopolyplexes and possibilities for their future development are presented.     

Detection of anionic sites and immunoglobulin A deposits in the glomerular capillary walls from patients with IgA nephropathy

A study of anionic sites in the glomerular basement membrane (GBM) from patients with immunoglobulin A (IgA) nephropathy is described. The relationship between the deposition of IgA and the detection of glomerular extracellular components, i.e., noncollagenous (NC-1) domain of Type IV collagen, in the glomerular capillary walls was examined by double immunofluorescence. Renal biopsy specimens from patients with IgA nephropathy were immersed in polyethyleneimine (PEI) as a cationic probe and then examined by electron microscopy. Renal specimens were also incubated with mouse monoclonal anti-NC-1 domain of Type IV collagen and then stained with fluorescein isothiocyanate (FITC)-labelled goat antimouse Ig antiserum. After these reactions, sections were stained with rhodamine-labelled rabbit antihuman IgA antiserum. GBM subepithelial anionic sites marked by PEI were altered by the deposition of electron-dense deposits (EDD) in patients with IgA nephropathy and there was a significant correlation between the levels of proteinuria and the incidence of EDD in the GBM in such patients. Marked proteinuria was observed in patients who showed loss of anionic sites in the GBM by electron microscopy. By double immunofluorescence, IgA was shown to be focally deposited outside the NC-1 domain of Type IV collagen-detected regions in the same patients. The authors concluded that high levels of proteinuria might be due to alterations of the size barrier and/or anionic sites of GBM in the moderate stage of IgA nephropathy.     

肾小球基膜负电荷的检测方法及病理改变

以胶体铁、核固红为染料,阳离子多聚体-PEI为示踪剂。通过组化染色,光镜和电镜下观察大白鼠、正常人及肾炎患者肾脏负电荷的分布及其病理改变。结果表明:1.本检测方法先进,结果可靠。既可应用于肾脏负电荷,尤其是基膜负电荷的宏观定性分析和微观定量分析,又可用于多种肾脏疾病的病理诊断。2.肾小球基膜负电荷的减少和/或消失与免疫复合物的沉积有关;大量蛋白尿与基膜负电荷的减少和/或消失有关。