Navegando por Autor "Farias, Leonardo Paiva"
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Item Characterization of phosphodiesterase-5 as a surface protein in the tegument of Schistosoma mansoni.(2009) Rofatto, Henrique Krambeck; Tararam, Cibele Aparecida; Borges, William de Castro; Wilson, R. Alan; Leite, Luciana Cesar de Cerqueira; Farias, Leonardo PaivaSchistosoma mansoni is a major causative agent of schistosomiasis, an important parasitic disease that constitutes a severe health problem in developing countries. Even though an effective treatment exists, it does not prevent re-infection and the development of an effective vaccine still remains the most desirable means of control for this disease. In thisworkwe describe the cloning and characterization of a S. mansoni nucleotidepyrophosphatase/phosphosdiesterase type 5(SmNPP-5), previously identifiedinthe tegument by proteomic studies. In silico analysis predicts an N-terminal signal peptide, three N-glycosylation sites and a C-terminal transmembrane domain similar to that described for mammalian isoforms. Real-time quantitative RT-PCR andWestern blot analyses determined that SmNPP-5 is significantly upregulated in the transition from free-living cercaria to schistosomulum and adult worm parasitic stages; additionally, the native protein was demonstrated to be N-glycosylated. Immunolocalization experiments and tegument surface membrane preparations confirm the protein as a tegument surface protein. Furthermore, the ectolocalization of this enzyme was corroborated through the hydrolysis of the phosphodiesterase specific substrate (_-Nph-5_-TMP) by living adult and 21-day-old worms. Interestingly, pre-incubation of adult and 21-day-old worms with anti-rSmNPP-5 antibody was able to reduce by 50–60% the enzyme activity. These results suggest that SmNPP-5 is closely associated with the new tegument surface generation after cercarial penetration, and being located at the host–parasite interface, is a potential target for immune intervention.Item Development and in vitro characterization of polymeric nanoparticles containing recombinant adrenomedullin-2 intended for therapeutic angiogenesis.(2019) Quadros, Helenita Costa; Santos, Laís de Macêdo Ferreira; Meira, Cássio Santana; Khouri, Mariana Ivo; Mattei, Bruno; Soares, Milena Botelho Pereira; Borges, William de Castro; Farias, Leonardo Paiva; Formiga, Fabio RochaCardiovascular diseases (CVD) are the leading cause of death worldwide. Growth factor therapy has emerged as novel therapeutic strategy under investigation for CVD. In this sense, adrenomedullin-2 (ADM-2) has been recently identified as a new angiogenic factor able to regulate the regional blood flow and cardiovascular function. However, the therapeutic value of ADM-2 is limited by its short biological half-life and low plasma stability. Poly (lactic-co-glycolic acid) (PLGA) micro- and nanoparticles have been investigated as growth factor delivery systems for cardiac repair. In this study, we aimed to develop PLGA nanoparticles containing ADM-2 intended for therapeutic angiogenesis. PLGA nanoparticles containing ADM-2 were prepared by a double emulsion modified method, resulting in 300 nm-sized stable particles with zeta potential around – 30 mV. Electron microscopy analysis by SEM and TEM revealed spherical particles with a smooth surface. High encapsulation efficiency was reached (ca.70%), as quantified by ELISA. ADM-2 associated to polymer nanoparticles was also determined by EDS elemental composition analysis, SDS-PAGE and LC-MS/MS for peptide identification. In vitro release assays showed the sustained release of ADM-2 from polymer nanoparticles for 21 days. Cell viability experiments were performed in J774 macrophages and H9c2 cardiomyocyte cells, about which PLGA nanoparticles loaded with ADM-2 did not cause toxicity in the range 0.01–1 mg/ml. Of note, encapsulated ADM-2 significantly induced cell proliferation in EA.hy926 endothelial cells, indicating the ADM-2 bioactivity was preserved after the encapsulation process. Collectively, these results demonstrate the feasibility of using PLGA nanoparticles as delivery systems for the angiogenic peptide ADM-2, which could represent a novel approach for therapeutic angiogenesis in CVD using growth factor therapy.Item Epitope mapping of exposed tegument and alimentary tract proteins identifies putative antigenic targets of the attenuated schistosome vaccine.(2020) Farias, Leonardo Paiva; Vance, Gillian M.; Coulson, Patricia S.; Souza, Juliana Vitoriano de; Silva Neto, Almiro Pires da; Wangwiwatsin, Arporn; Neves, Leandro Xavier; Borges, William de Castro; McNicholas, Stuart; Wilson, Keith Sanderson; Leite, Luciana Cezar de Cerqueira; Wilson, R. AlanThe radiation-attenuated cercarial vaccine remains the gold standard for the induction of protective immunity against Schistosoma mansoni. Furthermore, the protection can be passively transferred to naïve recipient mice from multiply vaccinated donors, especially IFNgR KO mice. We have used such sera versus day 28 infection serum, to screen peptide arrays and identify likely epitopes that mediate the protection. The arrays encompassed 55 secreted or exposed proteins from the alimentary tract and tegument, the principal interfaces with the host bloodstream. The proteins were printed onto glass slides as overlapping 15mer peptides, reacted with primary and secondary antibodies, and reactive regions detected using an Agilent array scanner. Pep Slide Analyzer software provided a numerical value above background for each peptide from which an aggregate score could be derived for a putative epitope. The reactive regions of 26 proteins were mapped onto crystal structures using the CCP4 molecular graphics, to aid selection of peptides with the greatest accessibility and reactivity, prioritizing vaccine over infection serum. A further eight MEG proteins were mapped to regions conserved between family members. The result is a list of priority peptides from 44 proteins for further investigation in multiepitope vaccine constructs and as targets of monoclonal antibodies.