Trypanosoma cruzi: parasite shed vesicles increase heart parasitism and generate an intense inflammatory response

Trypanosoma cruzi trypomastigotes continuously shed into the medium plasma membrane fragments sealed as vesicles enriched in glycoproteins of the gp85 and trans-sialidase (TS) superfamily and alpha-galactosyl-containing glycoconjugates. Injection of a vesicle fraction into BALB/c mice prior to T. cruzi infection led to 40% of deaths on the 16th day post-infection and 100% on day 20th whereas 20% of untreated animals survived for more than 30 clays. The vesicle-treated animals developed severe heart pathology, with intense inflammatory reaction and higher number of amastigote nests. Analysis of the inflammatory infiltrates 15 days after infection showed predominance of TCD4(+) lymphocytes and macrophages, but not of TCD8(+) cells, as well as a decrease of areas labeled with anti-iNOS antibodies as compared to the control. Higher levels of IL-4 and IL-10 mRNAs were found in the hearts and higher IL-10 and lower NO levels in splenocytes of vesicles pretreated animals. Treatment of mice with neutralizing anti-IL-10 or anti-IL-4 antibodies precluded the effects of pre-inoculation of membrane vesicles on infection. These results indicate that T. cruzi shed membrane components increase tissue parasitism and inflammation by stimulation of IL-4 and IL-10 synthesis and thus may play a central role in the pathogenesis of Chagas` disease acute phase. (c) 2008 Elsevier Masson SAS. All rights reserved.

Crucial cytokine interactions in nitric oxide production induced by Mycoplasma arthritidis superantigen

Mycoplasma arthritidis causes autoimmune arthritis in rodents. It produces a superantigen (MAM) that simultaneously activates antigen presenting cells and T cells inducing nitric oxide and cytokine release. Nitric oxide is a key inducer and regulator of the immune system activation. Here, we investigated nitric oxide and cytokine production and interactions of these molecules in MAM-stimulated co-cultures of macrophages (J774A.1 cell line) with spleen lymphocytes. We found that: a) MAM-induced nitric oxide, interferon-gamma, membrane-associated tumor necrosis factor and interleukin-2 production in co-cultures of macrophages with lymphocytes from BALB/c and C3H/HePas but not from C57B1/6 mice; b) production of nitric oxide was dependent on interferon-gamma whereas that of interferon-gamma was dependent on interleukin-2 and membrane-associated tumor necrosis factor; c) these cytokines up regulated MAM-induced nitric oxide production. Unraveling the mechanisms of cell activation induced by MAM might be helpful to design strategies to prevent immune system activation by superantigens and therefore in seeking amelioration of associated immunopathologies. (C) 2008 Elsevier Masson SAS. All rights reserved.

Identification and characterization of antigenic proteins potentially expressed during the infectious process of Paracoccidioides brasiliensis

Paracoccidioides brasiliensis causes paracoccidioidomycosis (PCM), a systemic mycosis presenting clinical manifestations ranging from mild to severe forms. A P. brasiliensis cDNA expression library was produced and screened with pooled sera from PCM patients adsorbed against antigens derived from in vitro-grown P. brasiliensis yeast cells. Sequencing DNA inserts from clones reactive with PCM patients sera indicated 35 open reading frames presenting homology to genes involved in metabolic pathways, transport, among other predicted functions. The complete cDNAs encoding aromatic-L-amino-acid decarboxylase (Pbddc), lumazine synthase (Pbls) and a homologue of the high affinity copper transporter (Pbctr3) were obtained. Recombinant proteins PbDDC and PbLS were obtained; a peptide was synthesized for PbCTR3. The proteins and the synthetic peptide were recognized by sera of patients with confirmed PCM and not by sera of healthy patients. Using the in vivo-induced antigen technology (IVIAT), we identified immunogenic proteins expressed at high levels during infection. Quantitative real time RTPCR demonstrated high transcript levels of Pbddc, Pbls and Pbctr3 in yeast cells infecting macrophages. Transcripts in yeast cells derived from spleen and liver of infected mice were also measured by qRT-PCR. Our results suggest a putative role for the immunogenic proteins in the infectious process of P. brasiliensis. (C) 2009 Elsevier Masson SAS. All rights reserved.

Species diversity of Leishmania (Viannia) parasites circulating in an endemic area for cutaneous leishmaniasis located in the Atlantic rainforest region of northeastern Brazil

OBJECTIVES To identify the aetiological agents of cutaneous leishmaniasis and to investigate the genetic polymorphism of Leishmania (Viannia) parasites circulating in an area with endemic cutaneous leishmaniasis (CL) in the Atlantic rainforest region of northeastern Brazil. METHODS Leishmania spp. isolates came from three sources: (i) patients diagnosed clinically and parasitologically with CL based on primary lesions, secondary lesions, clinical recidiva, mucocutaneous leishmaniasis and scars; (ii) sentinel hamsters, sylvatic or synanthropic small rodents; and (iii) the sand fly species Lutzomyia whitmani. Isolates were characterised using monoclonal antibodies, multilocus enzyme electrophoresis (MLEE) and polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer region rDNA locus. RESULTS Seventy-seven isolates were obtained and characterised. All isolates were identified as Leishmania (Viannia) braziliensis serodeme 1 based on reactivity to monoclonal antibodies. MLEE identified 10 zymodemes circulating in the study region. Most isolates were classified as zymodemes closely related to L. (V.) braziliensis, but five isolates were classified as Leishmania (Viannia) shawi. All but three of the identified zymodemes have so far been observed only in the study region. Enzootic transmission and multiclonal infection were observed. CONCLUSIONS Our results confirm that transmission cycle complexity and the co-existence of two or more species in the same area can affect the level of genetic polymorphism in a natural Leishmania population. Although it is not possible to make inferences as to the modes of genetic exchange, one can speculate that some of the zymodemes specific to the region are hybrids of L. (V.) braziliensis and L. (V.) shawi.

Additive effect of P10 immunization and chemotherapy in anergic mice challenged intratracheally with virulent yeasts of Paracoccidioides brasiliensis

Paracoccidioidomycosis is a systemic granulomatous disease manifested in the acute/subacute or chronic forms. The anergic cases of the acute/subacute form are most severe, leading to death threatening conditions. Drug treatment is required to control the disease but the response in anergic patients is generally poor. A 15-mer peptide from the major diagnostic antigen gp43, named P10, induces a T-CD4(+) helper-1 immune response in mice of different haplotypes and protects against intratracheal challenge with virulent P. brasiliensis. Presently, P10 immunization and chemotherapy were associated in an attempt to improve antifungal treatment in Balb/c mice made anergic by adding dexamethasone to the drinking water. The combined drug/peptide treatment significantly reduced the lung CFUs in infected anergic mice, largely preserved lung alveolar structure and prevented fungal dissemination to liver and spleen. Results recommend that a P10-based vaccine should be associated to chemotherapy for improved treatment of paracoccidioidomycosis aiming especially at anergic cases. (C) 2008 Elsevier Masson SAS. All rights reserved.

Bismuth germanate films prepared by Pechini method

Bismuth germanate films were prepared by dip coating and spin coating techniques and the dependence of the luminescent properties of the samples on the resin viscosity and deposition technique was investigated. The resin used for the preparation of the films was obtained via Pechini method, employing the precursors Bi(2)O(3) and GeO(2). Citric acid and ethylene glycol were used as chelating and cross-linking agents, respectively. Results from X-ray diffraction and Raman spectroscopy indicated that the films sintered at 700 degrees C for 10 h presented the single crystalline phase Bi(4)Ge(3)O(12). SEM images of the films have shown that homogeneous flat films can be produced by the two techniques investigated. All the samples presented the typical Bi(4)Ge(3)O(12) emission band centred at 505 nm. Films with 3.1 mu m average thickness presented 80% of the luminescence intensity registered for the single crystal at the maximum wavelength. Published by Elsevier B.V.

Nasal immunization of mice with Lactobacillus casei expressing the Pneumococcal Surface Protein A: induction of antibodies, complement deposition and partial protection against Streptococcus pneumoniae challenge

Strategies for the development of new vaccines against Streptococcus pneumoniae infections try to overcome problems such as serotype coverage and high costs, present in currently available vaccines. Formulations based on protein candidates that can induce protection in animal models have been pointed as good alternatives. Among them, the Pneumococcal Surface Protein A (PspA) plays an important role during systemic infection at least in part through the inhibition of complement deposition on the pneumococcal surface, a mechanism of evasion from the immune system. Antigen delivery systems based on live recombinant lactic acid bacteria (LAB) represents a promising strategy for mucosal vaccination, since they are generally regarded as safe bacteria able to elicit both systemic and mucosal immune responses. In this work, the N-terminal region of clade I PspA was constitutively expressed in Lactobacillus casei and the recombinant bacteria was tested as a mucosal vaccine in mice. Nasal immunization with L. casei-PspA 1 induced anti-PspA antibodies that were able to bind to pneumococcal strains carrying both clade 1 and clade 2 PspAs and to induce complement deposition on the surface of the bacteria. In addition, an increase in survival of immunized mice after a systemic challenge with a virulent pneumococcal strain was observed. (C) 2008 Elsevier Masson SAS. All rights reserved.

Cobalt catalysts derived from hydrotalcite-type precursors applied to steam reforming of ethanol

Catalysts derived from Co/Mg/Al hydrotalcite-type precursors modified with La and Ce were characterized by XANES and tested in ethanol steam reforming. The reaction data showed that, with a molar ratio of water: ethanol = 3:1 in the feed, addition of Ce and La favored acetaldehyde production. Increasing the water content (water:ethanol = 5:1) decreased the acetaldehyde formation by favoring the adsorption of water molecules on these samples, enhancing the acetaldehyde conversion. (C) 2011 Elsevier B.V. All rights reserved.