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Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-21T19:19:10Z No. of bitstreams: 1 AnaDias.pdf: 3102283 bytes, checksum: 6eb4c0bb2a542e274e68001ba7b1b766 (MD5) / Made available in DSpace on 2017-06-21T19:19:10Z (GMT). No. of bitstreams: 1 AnaDias.pdf: 3102283 bytes, checksum: 6eb4c0bb2a542e274e68001ba7b1b766 (MD5) Previous issue date: 2016-06-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Apoio à Pequisa (FUNAPE) / Leishmaniasis is a neglected and endemic disease in Brazil, especially in the Northeast, caused by over 20 species of the Leishmania protozoan. Diagnosis includes epidemiological, clinical, and laboratory aspects. Despite the existence of various diagnostic techniques that can be used, none has 100% sensitivity and specificity. Hence, this study aimed to validate three recombinant mimetic peptides (LC1, LC2, and LT) obtained by Phage display, for the development of a specific, sensitive, rapid low-cost immunological diagnosis. Sera for detection of IgG from 223 individuals were used (123 with visceral leishmaniasis (VL), 45 with cutaneous leishmaniasis (CL) and 55 with LV-HIV coinfection). For cross-reaction tests, we used samples of patients with Chagas' disease (n = 60) and Malaria (n=65), and control group (n= 75 sera from newborns). The peptides were also tested in saliva from patients with LV (n = 65), with LT (n = 40), and healthy individuals from an endemic area were used as control (n =35). Diagnostic tests using the mimetic LC1 and LC2 peptides were carried out in serum of 15 asymptomatic subjects; 13 healed individuals and 15 healthy subjects. To test the ability of the mimetic peptides to improve the immune response against Leishmania, murine macrophages C57BL/6 were treated in vitro with peptides LC1, LC2, and LT (0,6μM; 1,25μM; 2,5μM; 5μM, 10μM) and infected with L. infantum chagasi and L. amazonensis for invasion and multiplication assays. We also evaluated the potential protective action of mimetic peptide in mice infected with L. amazonensis. Therefore, animals were immunized and the parasite load, expression of cytokines, lesion size, and protein analysis binders were evaluated. The immunoassays showed that both serum and saliva of the patients exhibited a highly significant difference (p < 0.0001) compared to their controls, with 100% sensitivity and 100%specificity. Peptides were able to detect infection in asymptomatic subjects and showed no cross-reactivity to either Chagas’ disease or malaria, as well as co-infection LV-HIV did not interfere with responsiveness to LV antibodies, therefore being a promising tool for monitoring regions where these diseases occur. Tests using macrophages showed a highly significant reduction in the number of infected cells and of internalized parasites. A further reduction of parasites with increasing concentration of peptide was observed. Furthermore, it was observed that immunization of mice was able to induce high levels of IFN-γ, IL-12, GM-CSF and IL-10, while IL-4 did not change compared to the control. Additionally, immunized animals showed a reduction in parasitic load in all organs (spleen, lymph node, liver, and bone marrow), a decrease in paw lesion in which parasites were inoculated and phosphorylation of ERK1/2, JNK and p65/RelA. Western Blot assay identified two proteins to L. amazonensis (42 KDa) and two to Leishmania infantum chagasi (26 KDa). Thus, our results demonstrate that mimetic peptides act as antigens of L. infantum chagasi and L. amazonensis, being good immune markers for a simple and fast diagnosis with high sensitivity and specificity. Finally, data in murine macrophages in vitro and in vivo open perspectives for their use as a vaccine tool. / Leishmaniose é uma doença negligenciada e endêmica no Brasil, especialmente na região Nordeste, sendo causada por cerca de 20 espécies do protozoário Leishmania. O diagnóstico abrange aspectos epidemiológicos, clínicos e laboratoriais. Apesar de existir várias técnicas diagnósticas que podem ser utilizadas, nenhum dos testes disponíveis apresenta 100% de sensibilidade e especificidade. Baseado nisto, este trabalho se propôs a validar três peptídeos recombinantes miméticos (LC1, LC2 e LT) obtidos por Phage display, para o desenvolvimento de um diagnóstico imunológico rápido, específico, sensível e de baixo custo. Foram utilizados soros para detecção de IgG em 223 indivíduos, sendo 123 com leishmaniose visceral (LV), 45 com leishmaniose tegumentar (LT) e 55 com coinfecção LV-HIV. Para testes de reação cruzada, foram utilizadas amostras de pacientes com Doença de Chagas (n = 60) e com Malária (n = 65) e, como grupo controle, foram utilizados soros de 75 de recém-nascidos. Os peptídeos também foram testados em amostras de saliva de 65 pacientes com LV e 40 pacientes com LT, tendo como grupo controle 35 indivíduos saudáveis de área endêmica. Foram realizados também testes diagnósticos utilizando os peptídeos miméticos LC1 e LC2 em soro de 15 indivíduos assintomáticos; 13 indivíduos curados e 15 indivíduos sadios. Com a finalidade vacinal, macrófagos murinos C57BL/6 foram tratados in vitro com peptídeos LC1, LC2 e LT (0,6μM; 1,25μM; 2,5μM; 5μM; 10μM) e infectados com L. infantum chagasi e L. amazonensis para ensaio de invasão e multiplicação. Foram também realizados ensaios para testar o potencial protetor do peptídeo mimético em camundongos infectados por L. amazonensis. Para tanto, os animais foram imunizados e avaliada a carga parasitária, expressão de citocinas, tamanho da lesão, e análise protéica de ligantes. Os ensaios imunoenzimáticos mostraram que tanto soro quanto saliva dos pacientes apresentaram diferença altamente significativa (p < 0,0001) em relação a seus controles, apresentando sensibilidade de 100% e especificidade de 100% para todos os peptídeos, tanto em soro quanto em saliva. Os peptídeos foram capazes de detectar infecção em indivíduos assintomáticos e não apresentaram reação cruzada com Doença de Chagas e Malária, bem como a coinfecção com HIV não interfere na reatividade com os anticorpos para L. infantum chagasi, sendo, portanto, uma promissora ferramenta para monitoramento da infecção em regiões endêmicas. Os ensaios com macrófagos mostraram uma redução altamente significativa no número de células infectadas e do número de parasitas internalizados. Observou-se maior redução de parasitas com o aumento da concentração dos peptídeos. Foi observado que a imunização de camundongos foi capaz de induzir níveis elevados de IFN-γ, IL-12 e GM-CSF, enquanto os níveis de IL-4 e IL-10 foram reduzidos. Além disso, os animais imunizados apresentaram uma redução da carga parasitária em todos os órgãos (baço, linfonodo, fígado e medula óssea), uma diminuição da lesão da pata na qual os parasitas foram inoculados e fosforilação das proteínas ERK1/2, JNK e p65/RelA. O ensaio Western Blot identificou duas proteínas de L. amazonensis (42 kDa) e duas para Leishmania infantum chagasi (26 kDa). Assim, os resultados demonstram que os peptídeos sintéticos mimetizam antígenos de L. amazonensis e L. infantum chagasi, revelando-se bons marcadores para diagnóstico imunológico de uso rápido, simples e, principalmente, com alta sensibilidade e especificidade. Finalmente, os dados em macrófagos murinos in vitro e in vivo abrem perspectivas para o uso desses peptídeos como ferramenta vacinal.

The conflict between HIV-1 and the host immune system plays out over a time-scale of months and years, and on a grander scale in the co-evolution of lentiviruses and the immune systems of their host species. Directed evolution of HIV-1 entry inhibitors using controlled randomization together with a display system offers a means of recapitulating one side of this conflict in vitro on an accelerated time-scale. To address limitations in existing display systems, we constructed a vector (pDQ1) integrating phage-display and mammalian-expression systems. This vector displays on phage when expressed in bacteria, and as an Fc-fusion when expressed in tissue culture, thus accelerating the iterative process of randomization, display, and characterization. We demonstrated the utility of this vector in the evolution of a CD4-mimetic peptide.

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Various methods for extraction and analysis of high value minor proteins (lactoferrin, lactoperoxidase and immunoglobulins) directly from raw milk were explored. Extraction, purification and analysis of high-value minor proteins directly from milk without pre-treatment are major challenges for dairy industry, largely due to the complexity of milk and the presence of colloidal solids (casein micelles and milk fat globules). To overcome some of these challenges, this work focused on three main objectives: 1) characterization of cryogel monolith chromatography for purification of lactoferrin (LF) and lactoperoxidase (LP) directly from raw milk in single step, 2) identification and characterization of Protein A Mimetic affinity ligands for purification of immunoglobulins (Igs) from milk and 3) development and validation of a surface plasmon resonance method for simultaneous quantification of five whey proteins in multiple samples. Results portrayed the possibility of 40–50 column volumes of various milk samples (whole milk, skim milk and acid whey) to pass through a 5 mL cryogel monolith chromatography column at 525 cm hr⁻¹ without exceeding its pressure limits if the processing temperature is maintained around 35–37°C. Ideally, this should be the milk secretion temperature. The dynamic binding capacity obtained for the cryogel matrix (2.1 mg mL⁻¹) was similar to that of the binding capacity (2.01 mg mL⁻¹) at equilibrium with 0.1 mg mL⁻¹ of lactoferrin in the feed samples. Lactoferrin and lactoperoxidase was selectively bound to the cryogel column with trivial leakage in flowthrough fractions. Lactoferrin was recovered from elution fractions with a yield of 85% and a purity of 90%. These results, together with the ease of manufacture, low cost and versatile surface chemistry of cryogels suggest that they may be a good alternative to packed-bed chromatography for direct capture of proteins from milk, provided that the binding capacity can be increased. A Protein A Mimetic (PAM) hexapeptide (HWRGWV) peptide ligand that binds to the Fc portion of antibody molecules was explored for affinity purification of immunoglobulins from milk. The peptide has the ability to purify IgG from various milk and whey samples with a purity of greater than 85% in single step. More than 90% bound IgG was recovered with 0.2 M acetate buffer at pH 4.0 and total column regeneration was successfully achieved by 2.0 M guanidine-HCl. At 9.0 mg mL⁻¹ of IgG feed concentration, an equilibrium binding capacity of 21.7 mg mL⁻¹ and dynamic binding capacity of approximately 12.0 mg mL⁻¹ of resin was obtained. Recoveries and yields of IgG were significantly influenced by the feed IgG concentration. PAM hexamer ligand also contributed a significant amount of cross-reactivity with casein, glycomacropeptides and β-lactoglobulin proteins, however majority of these proteins were recovered in the regeneration step, except β-lactoglobulin, which co-eluted with IgG. Higher IgG concentration in feed vastly reduced the amount of cross-reactivity whilst increasing the recoveries and purities in the final product. PAM affinity ligands also showed interactions towards other classes of bovine immunoglobulins. These findings established the possibility of using PAM hexamer peptide as an alternative to conventional Protein A/G affinity chromatography for the isolation of Igs from milk in single step process. A surface plasmon resonance (SPR) method was developed for simultaneous, quantitative determination of commercially important whey proteins in raw and processed milk samples, whey fractions and various milk-derived products, with six samples per assay. Immobilized antibody stability and reproducibility of analyses were studied over time for 25 independent runs (n=300), giving a relative standard deviation (RSD) of <4%. Immobilized antibodies showed negligible non-specific interactions (<2–4 SPR response units (RU)) and no cross-reactivity towards other milk components (<1 RU). Regeneration of immobilised antibodies with glycine at pH 1.75 was determined to be optimal for maintaining the SPR response between samples. This method compared and validated well with reversed phase high performance liquid chromatography (RP-HPLC) and standard enzyme-linked immunosorbent assays (ELISA).

Actuellement, il est largement reconnu que la décision des cellules souches de maintenir leur caractère souche ou se différencier vers une lignée spécialisée dépend particulièrement de la nature de leur microenvironnement, appelé niche cellulaire. Une des composantes essentielles de cette niche cellulaire est la matrice extracellulaire (MEC), qui au-delà de sa fonction de support cellulaire, détermine le devenir des cellules souches en fonction de sa composition biochimique, sa structure et sa localisation. D’un point de vue rationnel, un biomatériau destiné à remplacer la fonction d’un tissu endommagé doit non seulement jouer le rôle d’échafaudage cellulaire mais également mimer les propriétés de la MEC dans son ensemble. Malheureusement, il est extrêmement difficile de concevoir des biomatériaux mimétiques de la MEC naturelle tenant compte de sa complexité structurelle et fonctionnelle. Pour pallier à cette problématique, il semble nécessaire d’effectuer un travail en amont de déconstruction/reconstruction de la complexité de la MEC en étudiant l’effet individuel puis combiné de ses propriétés sur la différenciation des cellules souches. Ce projet de doctorat rentre dans le cadre de ce travail et vise à déterminer le rôle spécifique ou concomitant de différentes propriétés inhérentes à la MEC sur la différenciation ostéoblastique des cellules souches mésenchymateuses humaines (hCSMs). En effet, nous avons évalué l’effet de la composition biochimique de la MEC et la distribution spatiale des ligands sur la différenciation des hCSMs, en fonctionnalisant la surface d’un matériau modèle avec les peptides RGD et/ou BMP-2, distribués d’une manière aléatoire ou structurée. / Actually, it is well-established that maintaining the stemness character of stem cells or eliciting their lineage-specific differentiation is closely related to the nature of their microenvironment, known as stem cell niche. The extracellular matrix (ECM), a key component of stem cell niche, not only provides a support function for stem cells but also dictates their fate decision. From a rational point of view, a biomaterial intended to replace a damaged tissue should mimic the natural ECM in all its aspects, including its biochemistry, 3D structure, topography, porosity, rigidity…. etc. Unfortunately, the design of biomaterials that fully mimic the natural ECM is still a big challenge, due to its high structural and functional complexity. Towards the development of finely-tuned biomaterials, it seems important to start by deconstructing and then reconstructing the complexity of the ECM. In this context, the thesis project, herein, seeks to evaluate both the individual and the synergistic effect of different properties inherent to the natural ECM on human mesenchymal stem cells (hMSCs) osteogenic differentiation. Indeed, we investigated whether the biochemical composition of the ECM and the spatial distribution of its components modulate hMSCs osteogenesis. This was achieved by creating different artificial ECMs, in vitro, containing RGD and/or BMP-2 mimetic peptides, distributed randomly or as specific micropatterns on the surface of a model material.

Nonviral gene delivery, though limited by inefficiency, has extensive utility in cell therapy, tissue engineering, and diagnostics. Substrate-mediated gene delivery (SMD) increases efficiency and allows transfection at a cell-biomaterial interface, by immobilizing and concentrating nucleic acid complexes on a surface. Efficient SMD generally requires substrates to be coated with serum or other protein coatings to mediate nucleic acid complex immobilization, as well as cell adhesion and growth; however, this strategy limits reproducibility and may be difficult to translate for clinical applications. As an alternative, we screened a chemically defined combinatorial library of 20 different extracellular matrix mimetic substrates containing combinations of (1) different sulfated polysaccharides that are essential extracellular matrix glycosaminoglycans (GAGs), with (2) mimetic peptides derived from adhesion proteins, growth factors, and cell-penetrating domains, for use as SMD coatings. We identified optimal substrates for DNA lipoplex and polyplex SMD transfection of fibroblasts and human mesenchymal stem cells. Optimal extracellular matrix mimetic substrates varied between cell type, donor source, and transfection reagent, but typically contained Heparin GAG and an adhesion peptide. Multiple substrates significantly increased transgene expression (i.e. 2- to 20-fold) over standard protein coatings. Considering previous research of similar ligands, we hypothesize extracellular matrix mimetic substrates modulate cell adhesion, proliferation, and survival, as well as plasmid internalization and trafficking. Our results demonstrate the utility of screening combinatorial extracellular matrix mimetic substrates for optimal SMD transfection towards application- and patient-specific technologies.