ORCID Profile
0000-0002-4713-575X
Current Organisation
Universidade Federal de Minas Gerais
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Publisher: Public Library of Science (PLoS)
Date: 27-01-2016
Publisher: American Society for Microbiology
Date: 12-2008
DOI: 10.1128/IAI.00419-08
Abstract: The impact of the interaction between excreted and/or secreted (ES) Necator americanus products and NK cells from Necator -infected in iduals was analyzed. We investigated the binding of ES products to NK cells, the expression of NK cell receptors (CD56, CD159a/NKG2A, CD314/NKG2D, CD335/NKp46, and KLRF1/NKp80), the frequency of gamma interferon (IFN-γ)-producing NK cells after whole-blood in vitro stimulation, and the capacity of N. americanus ES products to induce NK cell chemotaxis. In contrast to those from noninfected in iduals, NK cells from Necator -infected in iduals demonstrated no binding with N. americanus ES products. This phenomenon was not due to alterations in NK cell receptor expression in infected subjects and could not be reproduced with NK cells from uninfected in iduals by incubation with immunoregulatory cytokines (interleukin-10/transforming growth factor β). Further, we found that a significantly greater percentage of NK cells from infected subjects than NK cells from uninfected in iduals spontaneously produced IFN-γ upon ex vivo culture. Our findings support a model whereby NK cells from Necator -infected in iduals may interact with ES products, making these cells refractory to binding with exogenous ES products. During N. americanus infection, human NK cells are attracted to the site of infection by chemotactic ES products produced by adult Necator worms in the gut mucosa. Binding of ES products causes the NK cells to become activated and secrete IFN-γ locally, thereby contributing to the adult hookworm's ability to evade host immune responses.
Publisher: Elsevier BV
Date: 23-01-2006
DOI: 10.1016/J.VACCINE.2005.07.091
Abstract: While X-irradiated live parasites are not an acceptable proposition for human vaccination, they offer a ready experimental system to explore mechanisms by which immunity against hookworm infection may be induced in humans. As such, we sought to further elucidate the details of this highly protective immune response induced by the irradiated vaccine in canids, with special emphasis on the cellular aspects of the response. Vaccination with irradiated L3 induced high production of antibodies and strong PBMCs proliferation to crude L3 antigen preparation. Elevated IL-4 production was also observed in vaccinated dogs, especially in relation to IFN-gamma production (IL-4/IFN-gamma ratio). Serum from vaccinated animals inhibited penetration of L3 through canine skin in vitro by 60%. Finally, vaccinated animals had a strong antibody response to ASP-2, a promising vaccine antigen that is an excretory-secretory product of L3. These results add further support the idea that the Th2 immune response is required to generate protective immunity against hookworm larvae and that ES molecules released during this developmental stage are likely targets of this response.
Publisher: Elsevier BV
Date: 09-2005
DOI: 10.1016/J.VACCINE.2005.04.040
Abstract: The ASP-2 protein secreted by infective larvae of the human hookworm, Necator americanus, is under development as a recombinant vaccine. Recombinant Na-ASP-2 was expressed in Pichia pastoris, and the purified protein was characterized. At the 60 L scale, the 21.3 kDa recombinant protein was produced at a yield of 0.4 g/L. When formulated with Alhydrogel and injected into rats to determine immunological potency, three 50 microg doses of the formulated recombinant protein elicited geometric mean antibody titers up to 1:234,881. Rat anti-Na-ASP-2 antibody recognized larval-derived ASP-2 and also inhibited larval migration through skin in vitro. The processes developed and tested for the high yield production of recombinant Na-ASP-2 provide a foundation for clinical vaccine development.
Publisher: American Society for Microbiology
Date: 17-02-2022
DOI: 10.1128/IAI.00595-21
Abstract: Ascariasis is a neglected tropical disease that is widespread in the world and has important socioeconomic impacts. The presence of various stages of worm development in the pulmonary and intestinal mucosae induces a humoral and cellular immune response. However, although there is much evidence of the protective role of mucosal immunity against various pathogens, including helminths, there is still a gap in the knowledge about the immune response and the mechanisms of action that are involved in protection against diseases, especially in the initial phase of ascariasis. Thus, the aim of this study was to evaluate the kinetic aspects of the immune parasitological parameters in intestinal and pulmonary mucosae in male mice with early ascariasis.
Publisher: Public Library of Science (PLoS)
Date: 04-10-2005
Publisher: Public Library of Science (PLoS)
Date: 16-11-2021
DOI: 10.1371/JOURNAL.PPAT.1010067
Abstract: Human ascariasis is the most prevalent but neglected tropical disease in the world, affecting approximately 450 million people. The initial phase of Ascaris infection is marked by larval migration from the host’s organs, causing mechanical injuries followed by an intense local inflammatory response, which is characterized mainly by neutrophil and eosinophil infiltration, especially in the lungs. During the pulmonary phase, the lesions induced by larval migration and excessive immune responses contribute to tissue remodeling marked by fibrosis and lung dysfunction. In this study, we investigated the relationship between SIgA levels and eosinophils. We found that TLR2 and TLR4 signaling induces eosinophils and promotes SIgA production during Ascaris suum infection. Therefore, control of parasite burden during the pulmonary phase of ascariasis involves eosinophil influx and subsequent promotion of SIgA levels. In addition, we also demonstrate that eosinophils also participate in the process of tissue remodeling after lung injury caused by larval migration, contributing to pulmonary fibrosis and dysfunction in re-infected mice. In conclusion, we postulate that eosinophils play a central role in mediating host innate and humoral immune responses by controlling parasite burden, tissue inflammation, and remodeling during Ascaris suum infection. Furthermore, we suggest that the use of probiotics can induce eosinophilia and SIgA production and contribute to controlling parasite burden and morbidity of helminthic diseases with pulmonary cycles.
Publisher: American Society for Microbiology
Date: 03-2007
DOI: 10.1128/CVI.00404-06
Abstract: Hookworm infection is one of most important parasitic infection of humans, occurring in 740 million people. Here we report the protective vaccination of dogs with Ac -16, an immunodominant surface antigen from the hookworm Ancylostoma caninum . We show that immunization with Ac -16 formulated with AS03 elicited specific humoral and cellular immune responses and provided partial protection against hookworm infection and morbidity as evidenced by a significant reduction of hookworm egg counts (64% reduction P = 0.0078) and worm-induced blood loss ( P 0.05). Moreover, specific anti- Ac -16 antibodies recognized the native protein on the surface of third-stage larvae and blocked their migration through tissue in vitro. Our data support the use of Ac -16 as a potential candidate for vaccination against hookworm infection.
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.IJPARA.2013.02.009
Abstract: Studies related to the immunobiological aspects of an Ascaris spp. infection are still scarce, especially those that aim to elucidate the early events of the immune response. In this study, we demonstrated a novel standardized method for early experimental Ascaris infection, providing additional information about the infectivity of eggs embryonated in vitro as well as the influence of host age on development of the infection. Finally, we characterised the immunopathology of early infection, focusing on the tissue and systemic cytokine profiles and the histopathology of infection in the lungs of BALB/c mice. Our results demonstrated that the highest egg infectivity occurred on the 100th and 200th days of in vitro embryonation and that 8 week-old BALB/c mice were more susceptible to infection than 16 week-old mice. Ascaris-infected mice showed an early, significant level of IL-5 production in the lungs 4 days p.i., followed by an increase in the level of neutrophils in the inflammatory infiltrate at 8 days p.i, which was correlated with the peak of larval migration in the tissue and a significant level of IL-6 production. The inflammatory infiltrate in the lungs was gradually replaced by mononuclear cells and eosinophils on the 10th and 12th days p.i., respectively, and an increase in TNF levels was observed. The downmodulation of systemic TCD4(+) cell numbers might suggest that T cell hyporesponsiveness was induced by the Ascaris spp. larvae, contributing to safeguarding parasite survival during larval migration. Taken together, the novel aspects of Ascaris infection presented here enabled a better understanding of the immunopathological events during larval migration, providing insight for further studies focused on immunisation and immunoprophylatic assays.
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.MOLBIOPARA.2008.04.008
Abstract: mRNAs encoding cathepsin B-like cysteine proteases (CatBs) are abundantly expressed in the genomes of blood-feeding nematodes. Recombinant CatBs have been partially efficacious in vaccine trials in animal models of hookworm infection, supporting further investigation of these enzymes as new control tools. We recently described a family of four distinct CatBs (Na-CP-2, -3, -4, -5) from the human hookworm, Necator americanus. Here we show that these N. americanus CatBs form a robust clade with other hookworm CatBs and are most similar to intestinal CatBs from Haemonchus contortus. All four mRNAs (Na-cp-2, -3, -4 and -5) are up-regulated during the transition from a free-living larva to a blood-feeding adult worm and are also expressed in gut tissue of adult N. americanus that was dissected using laser microdissection microscopy. Recombinant Na-CP-3 was expressed in soluble, secreted form in the yeast Pichia pastoris, while Na-CP-2, -4 and -5 were expressed in insoluble inclusion bodies in Escherichia coli. Recombinant Na-CP-3 was not catalytically active when secreted by yeast but underwent auto-activation to an active enzyme at low pH in the presence of dextran sulphate. Activated Na-CP-3 digested gelatin and cleaved the fluorogenic substrate Z-Phe-Arg-aminomethylcoumarin (AMC) but not Z-Arg-Arg-AMC. Recombinant Na-CP-3 did not digest intact hemoglobin but digested globin fragments generated by prior hydrolysis with N. americanus aspartic hemoglobinases. Antibodies raised in mice to all four recombinant proteins showed minimal cross-reactivity with each other, and each antiserum bound to the intestine of adult N. americanus, supporting the intestinal expression of their mRNAs. These data show that N. americanus expresses a family of intestinal CatBs, many of which are likely to be involved in nutrient acquisition and therefore are potential targets for chemotherapies and vaccines.
Publisher: American Society for Microbiology
Date: 10-2005
DOI: 10.1128/IAI.73.10.6903-6911.2005
Abstract: We report the cloning and expression of Ac -GST-1, a novel glutathione S -transferase from the adult hookworm Ancylostoma caninum , and its possible role in parasite blood feeding and as a vaccine target. The predicted Ac -GST-1 open reading frame contains 207 amino acids (mass, 24 kDa) and exhibited up to 65% amino acid identity with other nematode GSTs. mRNA encoding Ac -GST-1 was detected in adults, eggs, and larval stages, but the protein was detected only in adult hookworm somatic extracts and excretory/secretory products. Using antiserum to the recombinant protein, Ac -GST-1 was immunolocalized to the parasite hypodermis and muscle tissue and weakly to the intestine. Recombinant Ac -GST-1 was enzymatically active, as determined by conjugation of glutathione to a model substrate, and exhibited a novel high-affinity binding site for hematin. The possible role of Ac -GST-1 in parasite heme detoxification during hemoglobin digestion or heme uptake prompted interest in evaluating it as a potential vaccine antigen. Vaccination of dogs with Ac -GST-1 resulted in a 39.4% reduction in the mean worm burden and 32.3% reduction in egg counts compared to control dogs following larval challenge, although the reductions were not statistically significant. However, hamsters vaccinated with Ac -GST-1 exhibited statistically significant worm reduction (53.7%) following challenge with heterologous Necator americanus larvae. These studies suggest that Ac -GST-1 is a possible drug and vaccine target for hookworm infection.
Location: Brazil
No related grants have been discovered for Ricardo Fujiwara.