Advances in Emerging and Neglected Infectious Diseases

Univ Texas El Paso, Dept Biol Sci, El Paso, TX 79968 USAUniv Fed Sao Paulo, Dept Biociencias, Campus Baixada Santista, Santos, SP, BrazilDepartamento de Biociências, Universidade Federal de São Paulo, Campus Baixada Santista, Santos, SP, BrazilWeb of Scienc

Importance of CD8 T cell-mediated immune response during intracellular parasitic infections and its implications for the development of effective vaccines

Obligatory intracellular parasites such as Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii and Leishmania sp are responsible for the infection of hundreds of millions of individuals every year. These parasites can deliver antigens to the host cell cytoplasm that are presented through MHC class I molecules to protective CD8 T cells. The in vivo priming conditions of specific CD8 T cells during natural infection are largely unknown and remain as an area that has been poorly explored. The antiparasitic mechanisms mediated by CD8 T cells include both interferon-g-dependent and -independent pathways. The fact that CD8 T cells are potent inhibitors of parasitic development prompted many investigators to explore whether induction of these T cells can be a feasible strategy for the development of effective subunit vaccines against these parasitic diseases. Studies performed on experimental models supported the hypothesis that CD8 T cells induced by recombinant viral vectors or DNA vaccines could serve as the basis for human vaccination. Regimens of immunization consisting of two different vectors (heterologous prime-boost) are much more efficient in terms of expansion of protective CD8 T lymphocytes than immunization with a single vector. The results obtained using experimental models have led to clinical vaccination trials that are currently underway.Parasitas intracelulares obrigatórios como Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii e Leishmania sp são responsáveis pela infecção de milhões de indivíduos a cada ano. Estes parasitas são capazes de liberar antígenos no citoplasma de células infectadas do hospedeiro que são apresentados por moléculas de MHC classe I para células T CD8 protetoras. As condições de estímulo in vivo destas células T CD8 específicas durante a infecção natural são pouco conhecidas e constituem uma área pouco explorada. Os mecanismos anti-parasitários mediados por células T CD8 incluem vias dependentes e independentes do interferon-g. O fato que células T CD8 são potentes inibidores do desenvolvimento parasitário levou diversos investigadores a explorarem se a indução destes linfócitos T poderia constituir uma estratégia factível para o desenvolvimento de vacinas efetivas contra estas doenças parasitárias. Estudos feitos em modelos experimentais suportam a hipótese que células T CD8 induzidas por vetores recombinantes virais ou vacinas de DNA podem servir de base para a vacinação humana. Regimes de imunização consistindo de dois vetores distintos (prime-boost heterólogo) são muito mais eficientes em termos da expansão de linfócitos T CD8 protetores do que a imunização com um único vetor. Os resultados obtidos usando modelos experimentais levaram a vacinações clínicas que estão atualmente em curso.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Microbiologia, Imunologia e ParasitologiaUniversidade de São Paulo Faculdade de Ciências Farmacêuticas Departamento de Análises Clínicas e ToxicológicasUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

Genetic Vaccination against Experimental Infection with Myotropic Parasite Strains of Trypanosoma cruzi

In earlier studies, we reported that a heterologous prime-boost regimen using recombinant plasmid DNA followed by replication-defective adenovirus vector, both containing Trypanosoma cruzi genes encoding trans-sialidase (TS) and amastigote surface protein (ASP) 2, provided protective immunity against experimental infection with a reticulotropic strain of this human protozoan parasite. Herein, we tested the outcome of genetic vaccination of F1 (CB10XBALB/c) mice challenged with myotropic parasite strains (Brazil and Colombian). Initially, we determined that the coadministration during priming of a DNA plasmid containing the murine IL-12 gene improved the immune response and was essential for protective immunity elicited by the heterologous prime-boost regimen in susceptible male mice against acute lethal infections with these parasites. the prophylactic or therapeutic vaccination of resistant female mice led to a drastic reduction in the number of inflammatory infiltrates in cardiac and skeletal muscles during the chronic phase of infection with either strain. Analysis of the electrocardiographic parameters showed that prophylactic vaccination reduced the frequencies of sinus arrhythmia and atrioventricular block. Our results confirmed that prophylactic vaccination using the TS and ASP-2 genes benefits the host against acute and chronic pathologies caused by T. cruzi and should be further evaluated for the development of a veterinary or human vaccine against Chagas disease.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Escola Paulista Med, Ctr Terapia Celular & Mol CTCMol, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, BR-04044010 São Paulo, BrazilFiocruz MS, Inst Oswaldo Cruz, Lab Biol Celular, BR-21040360 Rio de Janeiro, RJ, BrazilFiocruz MS, Ctr Pesquisas Goncalo Moniz, BR-40296710 Salvador, BA, BrazilHosp Sao Rafael, BR-41253190 Salvador, BA, BrazilUNIFESP, Inst Saude Soc, Dept Biociencias, BR-11015020 Santos, SP, BrazilFiocruz MS, Ctr Pesquisas Rene Rachou, BR-30190002 Belo Horizonte, MG, BrazilUniv Fed Minas Gerais, Inst Ciencias Biol, Dept Bioquim & Imunol, BR-31270901 Belo Horizonte, MG, BrazilUniv Massachusetts, Sch Med, Dept Med, Div Infect Dis & Immunol, Worcester, MA 01655 USAUniv Fed Santa Catarina, Dept Microbiol Immunol & Parasitol, BR-88040900 Florianopolis, SC, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Terapia Celular & Mol CTCMol, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, BR-04044010 São Paulo, BrazilUNIFESP, Inst Saude Soc, Dept Biociencias, BR-11015020 Santos, SP, BrazilFAPESP: 2009/06820-4FAPESP: 2013/13668/0FAPESP: 2012/22514-3Web of Scienc

The Combined Deficiency of Immunoproteasome Subunits Affects Both the Magnitude and Quality of Pathogen- and Genetic Vaccination-Induced CD8+ T Cell Responses to the Human Protozoan Parasite Trypanosoma cruzi

The beta1i, beta2i and beta5i immunoproteasome subunits have an important role in defining the repertoire of MHC class I-restricted epitopes. However, the impact of combined deficiency of the three immunoproteasome subunits in the development of protective immunity to intracellular pathogens has not been investigated. Here, we demonstrate that immunoproteasomes play a key role in host resistance and genetic vaccination-induced protection against the human pathogen Trypanosoma cruzi (the causative agent of Chagas disease), immunity to which is dependent on CD8+ T cells and IFN-gamma (the classical immunoproteasome inducer). We observed that infection with T. cruzi triggers the transcription of immunoproteasome genes, both in mice and humans. Importantly, genetically vaccinated or T. cruzi-infected beta1i, beta2i and beta5i triple knockout (TKO) mice presented significantly lower frequencies and numbers of splenic CD8+ effector T cells (CD8+CD44highCD62Llow) specific for the previously characterized immunodominant (VNHRFTLV) H-2Kb-restricted T. cruzi epitope. Not only the quantity, but also the quality of parasite-specific CD8+ T cell responses was altered in TKO mice. Hence, the frequency of double-positive (IFN-gamma+/TNF+) or single-positive (IFN-gamma+) cells specific for the H-2Kb-restricted immunodominant as well as subdominant T. cruzi epitopes were higher in WT mice, whereas TNF single-positive cells prevailed among CD8+ T cells from TKO mice. Contrasting with their WT counterparts, TKO animals were also lethally susceptible to T. cruzi challenge, even after an otherwise protective vaccination with DNA and adenoviral vectors. We conclude that the immunoproteasome subunits are key determinants in host resistance to T. cruzi infection by influencing both the magnitude and quality of CD8+ T cell responses

Re-circulation of lymphocytes mediated by sphingosine-1-phosphate receptor-1 contributes to resistance against experimental infection with the protozoan parasite Trypanosoma cruzi

T-cell mediated immune responses are critical for acquired immunity against infection by the intracellular protozoan parasite Trypanosoma cruzi. Despite its importance, it is currently unknown where protective T cells are primed and whether they need to re-circulate in order to exert their anti-parasitic effector functions. Here, we show that after subcutaneous challenge, CD11c(+)-dependent specific CD8(+) T-cell immune response to immunodominant parasite epitopes arises almost simultaneously in the draining lymph node (LN) and the spleen. However, until day 10 after infection, we observed a clear upregulation of activation markers only on the surface of CD11C(+)PDCA1(+) cells present in the LN and not in the spleen. Therefore, we hypothesized that CD8(+) T cells re-circulated rapidly from the LN to the spleen. We investigated this phenomenon by administering FTY720 to T. cruzi-infected mice to prevent egress of T cells from the LN by interfering specifically with signalling through sphingosine-1-phosphate receptor-1. in T. cruzi-infected mice receiving FTY720, CD8 T-cell immune responses were higher in the draining LN and significantly reduced in their spleen. Most importantly, FTY720 increased susceptibility to infection, as indicated by elevated parasitemia and accelerated mortality. Similarly, administration of FTY720 to mice genetically vaccinated with an immunodominant parasite antigen significantly reduced their protective immunity, as observed by the parasitemia and survival of vaccinated mice.We concluded that re-circulation of lymphocytes mediated by sphingosine-1-phosphate receptor-1 greatly contributes to acquired and vaccine-induced protective immunity against experimental infection with a human protozoan parasite. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Millennium Institute for Gene Therapy (Brazil)Universidade Federal de São Paulo, Ctr Terapia Celular & Mol CTCMol, Escola Paulista Med, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, São Paulo, BrazilFiocruz MS, Ctr Pesquisas Rene Rachou, Belo Horizonte, MG, BrazilUniv Fed Minas Gerais, Inst Ciencias Biol, Dept Microbiol, Belo Horizonte, MG, BrazilUniversidade Federal de São Paulo, Ctr Terapia Celular & Mol CTCMol, Escola Paulista Med, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, São Paulo, BrazilFAPESP: 2009/06820-4CNPq: 420067/2005-1Web of Scienc

Adenovirus Vector-Induced CD8(+) T Effector Memory Cell Differentiation and Recirculation, But Not Proliferation, Are Important for Protective Immunity Against Experimental Trypanosoma cruzi Infection

Heterologous prime-boost vaccination using plasmid DNA followed by replication-defective adenovirus vector generates a large number of specific CD8(+) T effector memory (TEM) cells that provide long-term immunity against a variety of pathogens. in the present study, we initially characterized the frequency, phenotype, and function of these T cells in vaccinated mice that were subjected to infectious challenge with the human protozoan parasite Trypanosoma cruzi. We observed that the frequency of the specific CD8(+) T cells in the spleens of the vaccinated mice increased after challenge. Specific TEM cells differentiated into cells with a KLRG1(High) CD27(Low) CD43(Low) CD183(Low)T-bet(High)Eomes(Low) phenotype and capable to produce simultaneously the antiparasitic mediators IFN and TNF. Using the gzmBCreERT2/ROSA26EYFP transgenic mouse line, in which the cells that express Granzyme B after immunization, are indelibly labeled with enhanced yellow fluorescent protein, we confirmed that CD8(+) T cells present after challenge were indeed TEM cells that had been induced by vaccination. Subsequently, we observed that the in vivo increase in the frequency of the specific CD8(+) T cells was not because of an anamnestic immune response. Most importantly, after challenge, the increase in the frequency of specific cells and the protective immunity they mediate were insensitive to treatment with the cytostatic toxic agent hydroxyurea. We have previously described that the administration of the drug FTY720, which reduces lymphocyte recirculation, severely impairs protective immunity, and our evidence supports the model that when large amounts of antigen-experienced CD8(+) TEM cells are present after heterologous prime-boost vaccination, differentiation, and recirculation, rather than proliferation, are key for the resultant protective immunity.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, CTCMol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Inst Saude & Soc, Dept Biociencias, BR-11015020 Santos, SP, BrazilUniv Fed Minas Gerais, Inst Ciencias Biol, Dept Bioquim & Imunol, BR-31270901 Belo Horizonte, MG, BrazilFiocruz MS, Ctr Pesquisas Rene Rachou, BR-30190002 Belo Horizonte, MG, BrazilUniv Fed Santa Catarina, Dept Microbiol Imunol & Parasitol, BR-88040900 Florianopolis, SC, BrazilUniv Massachusetts, Div Infect Dis & Immunol, Dept Med, Sch Med, Worcester, MA 01655 USAUniversidade Federal de São Paulo, CTCMol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Inst Saude & Soc, Dept Biociencias, BR-11015020 Santos, SP, BrazilFAPESP: 2009/06820-4FAPESP: 2013/13668/0FAPESP: 2012/22514-3Web of Scienc

Biogeochemical processes in canga ecosystems: armoring of iron ore against erosion and importance in iron duricrust restoration in Brazil

Supergene enriched iron ore deposits in Brazil are typically blanketed by goethite-cemented breccias that form a protective duricrust known as canga. Moderately hard, well consolidated, permeable and resistant to erosion and chemical weathering, the canga blanket protects the relatively friable iron ore below. The protective canga horizons in the Carajás and Quadrilátero Ferrífero mineral provinces represent some of the longest-lived, continuously exposed land surfaces on Earth, and their formation is essential to supergene iron ore enrichment and preservation. Remarkably, the iron-rich duricrusts that have developed in Brazilian tropical rainforest environments, i.e, Carajás, yield geochronological results that indicate that these ancient erosion-resistant surfaces continue to evolve today. Active biogeochemical iron cycling is essential for the ‘self-healing’ cementation/re-cementation occurring in canga, suggesting that recurrent iron reduction and subsequent oxidation are responsible for canga evolution. Macroscopic biological features in canga including ferruginised plant roots and termite tracks have been linked to the biogeochemical cycling of iron. The ‘organic’ textures in canga can be traced to the microscopic scale, preserving fossilised bacterial cell envelopes and permineralised biofilms. At the canga surface, naturally rare and endemic rupestrian plant species carve out an existence, commonly in the absence of soil. Growth of grasses also promotes metal cycling highlighting that the rhizosphere contributes to canga evolution. The fossilisation of microbial biofilms and rhizosphere horizons consolidates canga, affecting its permeability, limiting water transport and enhancing biogeochemical cycling. The development of canga has been essential for the formation, preservation, and discovery of iron ore deposits, and its restoration will ultimately be required for mined land remediation of these unique ecosystems