Identification of sphingomyelinase on the surface of Chlamydia pneumoniae: possible role in the entry into its host cells

Peer reviewe

Liposomal Tumor Targeting in Drug Delivery Utilizing MMP-2- and MMP-9-Binding Ligands

Nanotechnology offers an alternative to conventional treatment options by enabling different drug delivery and controlled-release delivery strategies. Liposomes being especially biodegradable and in most cases essentially nontoxic offer a versatile platform for several different delivery approaches that can potentially enhance the delivery and targeting of therapies to tumors. Liposomes penetrate tumors spontaneously as a result of fenestrated blood vessels within tumors, leading to known enhanced permeability and subsequent drug retention effects. In addition, liposomes can be used to carry radioactive moieties, such as radiotracers, which can be bound at multiple locations within liposomes, making them attractive carriers for molecular imaging applications. Phage display is a technique that can deliver various high-affinity and selectivity peptides to different targets. In this study, gelatinase-binding peptides, found by phage display, were attached to liposomes by covalent peptide-PEG-PE anchor creating a targeted drug delivery vehicle. Gelatinases as extracellular targets for tumor targeting offer a viable alternative for tumor targeting. Our findings show that targeted drug delivery is more efficient than non-targeted drug delivery

Utilizing Sphingomyelinase Sensitizing Liposomes in Imaging Intestinal Inflammation in Dextran Sulfate Sodium-Induced Murine Colitis

Inflammatory bowel disease (IBD) is characterized by chronic inflammation in the gastrointestinal tract, resulting in severe symptoms. At the moment, the goal of medical treatments is to reduce inflammation. IBD is treated with systemic anti-inflammatory compounds, but they have serious side effects. The treatment that is most efficient and causes the fewest side effects would be the delivery of the drugs on the disease site. This study aimed to investigate the suitability of sphingomyelin (SM) containing liposomes to specifically target areas of inflammation in dextran sulfate sodium-induced murine colitis. Sphingomyelin is a substrate to the sphingomyelinase enzyme, which is only present outside cells in cell stress, like inflammation. When sphingomyelin consisting of liposomes is predisposed to the enzyme, it causes the weakening of the membrane structure. We demonstrated that SM-liposomes are efficiently taken up in intestinal macrophages, indicating their delivery potential. Furthermore, our studies showed that sphingomyelinase activity and release are increased in a dextran sulfate sodium-induced IBD mouse model. The enzyme appearance in IBD disease was also traced in intestine samples of the dextran sulfate sodium-treated mice and human tissue samples. The results from the IBD diseased animals, treated with fluorescently labeled SM-liposomes, demonstrated that the liposomes were taken up preferentially in the inflamed colon. This uptake efficiency correlated with sphingomyelinase activity

Universal membrane-labeling combined with expression of Katushka far-red fluorescent protein enables non-invasive dynamic and longitudinal quantitative 3D dual-color fluorescent imaging of multiple bacterial strains in mouse intestine

Background: The human gastrointestinal (GI) tract microbiota has been a subject of intense research throughout the 3rd Millennium. Now that a general picture about microbiota composition in health and disease is emerging, questions about factors determining development of microbiotas with specific community structures will be addressed. To this end, usage of murine models for colonization studies remains crucial. Optical in vivo imaging of either bioluminescent or fluorescent bacteria is the basis for non-invasive detection of intestinal colonization of bacteria. Although recent advances in in vivo fluorescence imaging have overcome many limitations encountered in bioluminescent imaging of intestinal bacteria, such as requirement for live cells, high signal attenuation and 2D imaging, the method is still restricted to bacteria for which molecular cloning tools are available. Results: Here, we present usage of a lipophilic fluorescent dye together with Katushka far-red fluorescent protein to establish a dual-color in vivo imaging system to monitor GI transit of different bacterial strains, suitable also for strains resistant to genetic labeling. Using this system, we were able to distinguish two different E. coli strains simultaneously and show their unique transit patterns. Combined with fluorescence molecular tomography, these distinct strains could be spatially and temporally resolved and quantified in 3D. Conclusions: Developed novel method for labeling microbes and identify their passage both temporally and spatially in vivo makes now possible to monitor all culturable bacterial strains, also those that are resistant to conventional genetic labeling.Peer reviewe

Exploring the Usability of α-MSH-SM-Liposome as an Imaging Agent to Study Biodegradable Bone Implants In Vivo

Novel biodegradable metal alloys are increasingly used as implant materials. The implantation can be accompanied by an inflammatory response to a foreign object. For studying inflammation in the implantation area, non-invasive imaging methods are needed. In vivo imaging for the implanted area and its surroundings will provide beneficiary information to understand implant-related inflammation and help to monitor it. Therefore, inflammation-sensitive fluorescent liposomes in rats were tested in the presence of an implant to evaluate their usability in studying inflammation. The sphingomyelin-containing liposomes carrying alpha-melanocyte-stimulating hormone (α-MSH)-peptide were tested in a rat bone implant model. The liposome interaction with implant material (Mg-10Gd) was analyzed with Mg-based implant material (Mg-10Gd) in vitro. The liposome uptake process was studied in the bone-marrow-derived macrophages in vitro. Finally, this liposomal tracer was tested in vivo. It was found that α-MSH coupled sphingomyelin-containing liposomes and the Mg-10Gd implant did not have any disturbing influence on each other. The clearance of liposomes was observed in the presence of an inert and biodegradable implant. The degradable Mg-10Gd was used as an alloy example; however, the presented imaging system offers a new possible use of α-MSH-SM-liposomes as tools for investigating implant responses

Fluorine-labeled Dasatinib Nanoformulations as Targeted Molecular Imaging Probes in a PDGFB-driven Murine Glioblastoma Model

Dasatinib, a new-generation Src and platelet-derived growth factor receptor (PDGFR) inhibitor, is currently under evaluation in high-grade glioma clinical trials. To achieve optimum physicochemical and/or biologic properties, alternative drug delivery vehicles may be needed. We used a novel fluorinated dasatinib derivative (F-SKI249380), in combination with nanocarrier vehicles and metabolic imaging tools (microPET) to evaluate drug delivery and uptake in a platelet-derived growth factor B (PDGFB)-driven genetically engineered mouse model (GEMM) of high-grade glioma. We assessed dasatinib survival benefit on the basis of measured tumor volumes. Using brain tumor cells derived from PDGFB-driven gliomas, dose-dependent uptake and time-dependent inhibitory effects of F-SKI249380 on biologic activity were investigated and compared with the parent drug. PDGFR receptor status and tumor-specific targeting were non-invasively evaluated in vivo using 18F-SKI249380 and 18F-SKI249380-containing micellar and liposomal nanoformulations. A statistically significant survival benefit was found using dasatinib (95 mg/kg) versus saline vehicle (P < .001) in tumor volume-matched GEMM pairs. Competitive binding and treatment assays revealed comparable biologic properties for F-SKI249380 and the parent drug. In vivo, Significantly higher tumor uptake was observed for 18F-SKI249380-containing micelle formulations [4.9 percentage of the injected dose per gram tissue (%ID/g); P = .002] compared to control values (1.6%ID/g). Saturation studies using excess cold dasatinib showed marked reduction of tumor uptake values to levels in normal brain (1.5%ID/g), consistent with in vivo binding specificity. Using 18F-SKI249380-containing micelles as radiotracers to estimate therapeutic dosing requirements, we calculated intratumoral drug concentrations (24–60 nM) that were comparable to in vitro 50% inhibitory concentration values. 18F-SKI249380 is a PDGFR-selective tracer, which demonstrates improved delivery to PDGFB-driven high-grade gliomas and facilitates treatment planning when coupled with nanoformulations and quantitative PET imaging approaches