Tf-lipoplex-mediated c-Jun silencing improves neuronal survival following excitotoxic damage in vivo.

Excitotoxicity is one of the main features responsible for neuronal cell death after acute brain injury and in several neurodegenerative disorders, for which only few therapeutic options are currently available. In this work, RNA interference was employed to identify and validate a potential target for successful treatment of excitotoxic brain injury, the transcription factor c-Jun. The nuclear translocation of c-Jun and its upregulation are early events following glutamate-induced excitotoxic damage in primary neuronal cultures. We present evidence for the efficient knockdown of this transcription factor using a non-viral vector consisting of cationic liposomes associated to transferrin (Tf-lipoplexes). Tf-lipoplexes were able to deliver anti-c-Jun siRNAs to neuronal cells in culture, resulting in efficient silencing of c-Jun mRNA and protein and in a significant decrease of cell death following glutamate-induced damage or oxygen-glucose deprivation. This formulation also leads to a significant c-Jun knockdown in the mouse hippocampus in vivo, resulting in the attenuation of both neuronal death and inflammation following kainic acid-mediated lesion of this region. Furthermore, a strong reduction of seizure activity and cytokine production was observed in animals treated with anti-c-Jun siRNAs. These findings demonstrate the efficient delivery of therapeutic siRNAs to the brain by Tf-lipoplexes and validate c-Jun as a promising therapeutic target in neurodegenerative disorders involving excitotoxic lesions.

Tf-lipoplexes for neuronal siRNA delivery: a promising system to mediate gene silencing in the CNS.

Although RNAi-based gene silencing holds a great potential for treatment of neurological disorders, its application to the CNS has been restricted by low levels of tissue distribution and cellular uptake. In this work we report that cationic lipid-based vectors can enhance siRNA delivery to neurons both in vitro and in vivo. DOTAP:Chol liposomes associated with transferrin (Tf) and complexed with siRNAs (Tf-lipoplexes) were delivered to primary cultures of luciferase-expressing cortical neurons. Confocal microscopy studies revealed efficient cellular uptake of Cy3-labelled siRNAs after Tf-lipoplex delivery, which was reduced but not completely inhibited by blocking the Tf-receptor with excess Tf. Gene silencing was also evaluated after delivery of anti-luciferase or anti-c-Jun siRNAs. Our results demonstrate that Tf-lipoplexes achieve up to 50% luciferase and c-Jun knockdown, 48 h after transfection, without significant cytotoxicity. Similar results were observed in vivo, where a 40% reduction of luciferase activity was found in the striatum of luciferase mice. In addition, fluorescence microscopy studies showed extensive local distribution and internalization of Tf-lipoplex-associated Cy3-siRNAs without tissue toxicity. Overall, our results demonstrate that Tf-lipoplexes can mediate efficient gene silencing in neuronal cells, both in vitro an in vivo, which may prove useful in therapeutic approaches to neuronal protection and repair.

siRNA delivery by a transferrin-associated lipid-based vector: a non-viral strategy to mediate gene silencing.

BACKGROUND: RNA interference provides a powerful technology for specific gene silencing. Therapeutic applications of small interfering RNA (siRNA) however require efficient vehicles for stable complexation, protection, and extra- and intracellular delivery of these nucleic acids. Here, we evaluated the potential of transferrin (Tf)-associated liposomes for siRNA complexation and gene silencing. METHODS: Cationic liposomes composed of DOTAP : Cholesterol associated with or without transferrin (Tf) were complexed with siRNA at different lipid/siRNA charge ratios. Complexation and protection of siRNA from enzymatic degradation was assessed with the PicoGreen intercalation assay and gel electrophoresis. Cellular internalization of these siRNA Tf-lipoplexes was detected by confocal microscopy. Luciferase assay, immunoblot and fluorescence-activated cell sorting (FACS) analysis were used to evaluate reporter gene silencing in Huh-7 hepatocarcinoma and U-373 glioma cells. c-Jun knockdown in HT-22 cells was evaluated by quantitative real-time polymerase chain reaction (RT-PCR). Cytotoxicity of the siRNA complexes was assessed by Alamar blue, lactate dehydrogenase and MTT assays. RESULTS: Complexation of siRNA with the cationic liposomes in the presence of Tf results in the formation of stable particles and prevents serum-mediated degradation. Confocal microscopy showed fast cellular internalization of the Tf-lipoplexes via endocytosis. In the GFP glioma cells Tf-lipoplexes showed enhanced gene silencing at minimum toxicity in comparison to Tf-free lipoplexes. Targeting luciferase in the hepatocarcinoma cell line resulted in more than 70% reduction of luciferase activity, while in HT-22 cells 50% knockdown of endogenous c-Jun resulted in a significant protection from glutamate-mediated toxicity. CONCLUSIONS: Cationic liposomes associated with Tf form stable siRNA lipoplexes with reduced toxicity and enhanced specific gene knockdown activity compared to conventional lipoplexes. Thus, such formulations may constitute efficient delivery systems for therapeutic siRNA applications.

Tf-lipoplex-mediated NGF gene transfer to the CNS: neuronal protection and recovery in an excitotoxic model of brain injury.

The development of efficient systems for in vivo gene transfer to the central nervous system (CNS) may provide a useful therapeutic strategy for the alleviation of several neurological disorders. In this study, we evaluated the feasibility of nonviral gene therapy to the CNS mediated by cationic liposomes. We present evidence of the successful delivery and expression of both a reporter and a therapeutic gene in the rodent brain, as evaluated by immunohistochemical assays. Our results indicate that transferrin-associated cationic liposome/DNA complexes (Tf-lipoplexes) allow a significant enhancement of transfection activity as compared to plain complexes, and that 8/1 (+/-) Tf-lipoplexes constitute the best formulation to mediate in vivo gene transfer. We demonstrated that Tf-lipoplex-mediated nerve growth factor transgene expression attenuates the morphological damages of the kainic acid-induced lesion as assessed by 2,3,5-triphenyltetrazolium chloride (TTC) vital staining. These findings suggest the usefulness of these lipid-based vectors in mediating the delivery of therapeutic genes to the CNS.

Neuroprotective effect of a CNTF-expressing lentiviral vector in the quinolinic acid rat model of Huntington's disease.

Neurodegenerative diseases represent promising targets for gene therapy approaches provided effective transfer vectors. In the present study, we evaluated the effectiveness of LacZ-expressing lentiviral vectors with two different internal promoters, the mouse phosphoglycerate kinase 1 (PGK) and cytomegalovirus (CMV), to infect striatal cells. The intrastriatal injection of lenti-beta-Gal vectors lead to 207, 400 +/- 11,500 and 303,100 +/- 4,300 infected cells in adult rats, respectively. Importantly, the beta-galactosidase activity was higher in striatal extracts from PGK-LacZ-injected animals as compared to CMV-LacZ animals. The efficacy of the system was further examined with a potential therapeutic gene for the treatment of Huntington's disease, the human ciliary neurotrophic factor (CNTF). PGK-LacZ- or PGK-CNTF-expressing viruses were stereotaxically injected into the striatum of rats, 3 weeks later the animals were unilaterally lesioned with 180 nmol of quinolinic acid (QA). Control animals displayed 148 +/- 43 apomorphine-induced rotations ipsilateral to the lesion 5 days postlesion as compared to 26 +/- 22 turns/45 min in the CNTF-treated group. The extent of the striatal damage was significantly diminished in the CNTF-treated rats as indicated by the 52 +/- 9.7% decrease of the lesion volume and the sparing of DARPP-32, ChAT and NADPH-d neuronal populations. These results further establish that lentiviruses may represent an efficient gene delivery system for the screening of therapeutic molecules in Huntington's disease.

Neuroprotective effect of interleukin-6 and IL6/IL6R chimera in the quinolinic acid rat model of Huntington's syndrome.

Ciliary neurotrophic factor prevents behavioural deficits and striatal degeneration in rat and primate models of Huntington's disease. Interleukin-6, another member of the cytokine family, and the chimeric molecule (IL6/IL6R) in which interleukin-6 and its soluble receptor are fused, have been shown to exert trophic action on various neuronal populations in the central nervous system. Therefore, we investigated the neuroprotective effect of these two molecules in the quinolinic acid model of Huntington's disease. LacZ-, interleukin-6- and IL6/IL6R-expressing lentiviral vectors were stereotaxically injected into the striatum of Wistar rats. Three weeks later the animals were lesioned through the intrastriatal injection of 180 nmol of quinolinic acid. The extent of the striatal damage was significantly diminished in the rats that had been treated with interleukin-6 or IL6/IL6R. The neuroprotective effect was, however, more pronounced with the IL6/IL6R chimera than with interleukin-6 as indicated by the volume of the lesions (38.6 +/- 10% in the IL6/IL6R group, 63.3 +/- 3.6% in the IL-6 group and 84.3 +/-2.9% in the control group). Quantitative analysis of striatal interneurons further demonstrated that the IL6/IL6R chimera is more neuroprotective than IL-6 on ChAT- and NADPH-d-immunoreactive neurons. These results suggest that the IL6/IL6R chimera is a potential treatment for Huntington's disease.

Evolutionary distances and identification of Candida species in clinical isolates by randomly amplified polymorphic DNA (RAPD).

Fast and reliable identification of different species of the genus Candida is important to define adequate therapeutic decisions, because the different species have highly variable susceptibilities to antifungal drugs; azoles and amphothericin B. Accurate statistical records on case history and epidemiological studies also depend on effective identification. To address this problem we established a RAPD method that enabled direct identification of five very common species of Candida. Initially, reference band patterns were established for C. albicans, C. tropicalis, C. parapsilosis, C. glabrata and C. krusei. One of the primers, M2, showed remarkably conserved intra-specific patterns of approximately 10 bands each, ranging in size from 2.0 to 0.1 kb. These patterns were significantly different and species-specific. Few bands were conserved between different species of Candida, which was assumed to be consistent with their phylogenetic relatedness. In addition, band patterns were constant and reproducible and DNA isolated from single colonies yielded sufficient DNA for identification. The reference band patterns were then used, in blind experiments, to identify species of Candida in 50 randomly chosen samples, including clinical isolates and ATCC strains. RAPD results were 100% consistent with results obtained by conventional diagnostic methods and were achieved in one day instead of several days taken by conventional methods. Because ideal identification methods should be consistent with phylogeny and taxonomy we tested whether RAPD could be used to calculate genetic distances. Comparison of RAPD phylogenetic trees with 18S rRNA trees showed significant differences in tree topologies which indicated that RAPD data could not accurately measure the relative distances between different species. Also, computer simulations of RAPD random patterns were used to test whether the observed degree of RAPD band pattern similarities could occur at random. These simulations suggested that the level of inter-specific band pattern similarities observed in our data could be obtained at random, while intraspecific pattern similarities could not. RAPD would be helpful to discriminate between isolates but not to quantitate the differences. We suggest that the inaccurate estimate of genetic distances from RAPD is a general limitation of the technique and not a specific problem of our identification method. Because of the repetitive character of the target sequences, genetic distances calculated from RAPD could be affected by paralogy, namely, recombination and duplication events not parallel with speciation events.

Modeling dissolution of sparingly soluble multisized powders.

The dissolution of powder drugs, besides being a topic of utmost importance, especially for the sparingly soluble ones, is far from being well-explained. The purpose of the present study is, on the one hand, to obtain experimental dissolution profiles and, on the other hand, to analyze and process the data for dissolution modeling. Three different size fractions of a widely used sparingly soluble drug--ibuprofen--were fully characterized with regard to its particle size distribution, specific surface area, density, solubility, and diffusion coefficient. The dissolution profiles were obtained making use of a technique that counts and sizes particles--the Coulter counter technique--which is capable of following the number and size of the particles in suspension throughout time. The knowledge of these parameters allowed a critical study of the assumptions associated with the models currently used to describe the dissolution process. It was concluded that most of the assumptions were not valid for the present experimental conditions. This motivated the proposal of a new methodology, which uses the experimentally determined characteristics of the drug and takes into account the polydisperse nature of the powder. By applying an adequate dissolution equation to each of the many size classes in which the primary particle size distribution was divided, it was possible to obtain a large agreement between the simulated and the experimental dissolution profile.

[Seroepidemiologic survey of leptospirosis among environmental sanitation workers in an urban locality in the southern region of Brazil]. / Levantamento soroepidemiológico de leptospirose em trabalhadores do serviço de saneamento ambiental em localidade urbana da região sul do Brasil.

Sera from 386 environmental sanitation workers, concerned with water supply, drains and drainage galleries, sewers, garbage collection and road sweepers, were examined for leptospiral agglutinins by the microscopic agglutination test. Altogether 40 of the 386 workers (10.4%) were positive to one or more serovars; however, the difference in seropositivity between the professional categories was not significant (p < 0.05). Twelve serovars were recorded among the seropositive workers with predominance of L. castelonis and L. australis; but the difference between the serovars was not statistically significant (p > 0.05). Of the seropositive workers, 86.9% had agglutination titres > or = 100 and < or = 400; the rates for titres 100 and 400 were higher than 800, 1,600 and 3,200 (p < 0.05).