Navegando por Autor "Vaz, Leonardo Gomes"
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Item Lactobacillus delbrueckii UFV-H2b20 increases IFN-γ production and CD39+CD73+ Treg cell numbers in lungs, and protects mice against experimental allergic asthma.(2022) Andrade, Ana Clara Matoso Montuori de; Silva, Ana Elisa Nolasco e; Malacco, Nathalia Luisa Sousa de Oliveira; Vaz, Leonardo Gomes; Afonso, Luís Carlos Crocco; Russo, Remo de Castro; Vieira, Leda Quercia; Santos, Liliane Martins dosAsthma is a disorder characterized by airflow obstruction, inflammation, declining airway function, bronchial hyperresponsiveness and tissue remodelling. Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. The use of probiotics is becoming increasingly studied and recent evidence has suggested that it may provide therapeutic benefits in asthma and other diseases. Lactobacillus delbrueckii UFV-H2b20 fulfils all the requirements to be classified as probiotic. Previous studies have already shown the ability of L. delbrueckii UFV-H2b20 to stimulate the immune system. Our objective was to evaluate the protective effects of L. delbrueckii UFV-H2b20 in experimental allergic asthma. We used a murine model of ovalbumin-induced allergic airway inflammation to mimic allergic asthma. Oral treatment with L. delbrueckii UFV-H2b20 improves respiratory parameters and inhibits the inflammatory response in the lungs by decreasing the numbers of inflammatory monocytes, eosinophils and alveolar macrophages, as well as IgE levels. Treatment increased the IFN-γ/IL-4 cytokine ratio. Levels of IL-10 in the lungs were also increased in treated animals. Our results also showed that the probiotic administration increases the number of CD39+CD73+ T regulatory lymphocytes in the lung, suggesting a role for purinergic signals in the regulation of inflammation promoted by the treatment. Understanding the mechanisms of modulation of the immune system by probiotics could allow the development of probiotic preparations that are safe and have a direct action. Our results suggest that oral administration of L. delbrueckii UFV-H2b20 could be helpful to treat chronic inflammatory airway diseases, such as asthma.Item Obesity impairs resistance to Leishmania major infection in C57BL/6 mice.(2020) Martins, Vinicius Dantas; Campos, Franciele Carolina Silva; Moreira, Felipe Caixeta; Carneiro, Matheus Batista Heitor; Goes, Grazielle Ribeiro; Torres, Lícia; Barbosa, Sara Cândida; Vaz, Leonardo Gomes; Paiva, Nívia Carolina Nogueira de; Carneiro, Cláudia Martins; Vieira, Leda Quercia; Faria, Ana Maria Caetano de; Maioli, Tatiani UceliAn association between increased susceptibility to infectious diseases and obesity has been described as a result of impaired immunity in obese individuals. It is not clear whether a similar linkage can be drawn between obesity and parasitic diseases. To evaluate the effect of obesity in the immune response to cutaneous Leishmania major infection, we studied the ability of C57BL/6 mice fed a hypercaloric diet (HSB) to control leishmaniasis. Mice with diet-induced obesity presented thicker lesions with higher parasite burden and a more intense inflammatory infiltrate in the infected ear after infection with L. major. There was no difference between control and obese mice in IFN-gamma or IL-4 production by auricular draining lymph node cells, but obese mice produced higher levels of IgG1 and IL-17. Peritoneal macrophages from obese mice were less efficient to kill L. major when infected in vitro than macrophages from control mice. In vitro stimulation of macrophages with IL-17 decreased their capacity to kill the parasite. Moreover, macrophages from obese mice presented higher arginase activity. To confirm the role of IL-17 in the context of obesity and infection, we studied lesion development in obese IL-17R-/- mice infected with L. major and found no difference in skin lesions and the leukocyte accumulation in the draining lymph node is redcuced in knockout mice compared between obese and lean animals. Our results indicate that diet-induced obesity impairs resistance to L. major in C57BL/6 mice and that IL-17 is involved in lesion development.Item Regulation of macrophage subsets and cytokine production in leishmaniasis.(2021) Carneiro, Matheus Batista; Vaz, Leonardo Gomes; Afonso, Luís Carlos Crocco; Horta, Maria de Fátima Martins; Vieira, Leda QuerciaMacrophages are host cells for parasites of the genus Leishmania where they multiply inside parasitophorous vacuoles. Paradoxically, macrophages are also the cells responsible for killing or controlling parasite growth, if appropriately activated. In this review, we will cover the patterns of macrophage activation and the mechanisms used by the parasite to circumvent being killed. We will highlight the impacts of the vector bite on macrophage activation. Finally, we will discuss the ontogeny of macrophages that are infected by Leishmania spp.Item Short-term protection conferred by Leishvacin® against experimental Leishmania amazonensis infection in C57BL/6 mice.(2014) Carneiro, Matheus Batista Heitor; Sousa, Louisa Maria de Andrade e; Vaz, Leonardo Gomes; Santos, Liliane Martins dos; Vilela, Luciano; Souza, Carolina Carvalho de; Gonçalves, Ricardo; Tafuri, Wagner Luiz; Afonso, Luís Carlos Crocco; Côrtes, Denise Fonseca; Vieira, Leda QuerciaTo date, there is no vaccine available against human leishmaniasis. Although some vaccination protocols can induce immunity in murine models, they fail to induce protection in humans. The reasons for that remain unclear. The aimof the present study was to characterize the changes in the pattern of the immune response during subcutaneous vaccination with Leishvacin® in mice. We also investigated whether IFN-γ and nitric oxide synthase are indispensable for the protection elicited by the vaccine. C57BL/6 WT vaccinated mice showed smaller lesions and fewer numbers of parasites in footpads until 8 weeks post-infection. Up to this time, they produced higher levels of IFN-γ, IL-2, IL-4, IL-17A and IL-10 and higher specific antibody response than control non-vaccinated mice. Moreover, we showed that IFN-γ, most likely by induction of iNOS expression, is essential for immunity. However, after 12 weeks of infection, we observed loss of difference in lesion size and parasite burden between the groups. Loss of resistancewas associatedwith the disappearance of differences in cytokine patterns between vaccinated and control mice, but not of antibody response, which remained different until a later time of infection. The reversal of resistance to L. amazonensis could not be explained by upregulation of regulatory cytokines. Our data point to a subversion of the host immune response by L. amazonensis even when a protective response was previously induced.