Macrophage activation and histopathological findings in Calomys callosus and Swiss mice infected with several strains of Trypanosoma cruzi

Peritoneal macrophage activation as measured by H2O2 release and histopathology was compared between Swiss mice and Calomys callosus, a wild rodent, reservoir of Trypanosoma cruzi, during the course of infection with four strains of this parasite. In mice F and Y strain infections result in high parasitemia and mortality while with silvatic strains Costalimai and M226 parasitemia is sub-patent, with very low mortality. H2O2 release peaked at 33,6 and 59 nM/2 x 10(elevado a sexta potência) cells for strains Y and F, respectively, 48 and 50 nM/2 x 10 (elevado a sexta potência) for strains Costalimai and M226, at different days after infection. Histopathological findings of myositis, myocarditis, necrotizing artheritis and abscence of macrophage parasitism were foud for strains F and Costalimai. Y strain infection presented moderate myocarditis and myositis, with parasites multiplying within macrophages. In C. callosus all four strains resulted in patent parasitemia wich was eventually overcome, with scarce mortality. H2O2 release for strains Y or F was comparable to that of mice-peaks of 27 and 53 nM/2 x 10 (elevado a sexta potência) cells, with lower values for strains Costalimai and M226 - 16.5 and 4.6 nM/2 x 10(elevado a sexta potência)cells, respectively. Histopathological lesions with Y and F strain injected animals were comparable to those of mice at the onset of infections; they subsided completely at the later stages with Y strain and partially with F strain infected C. callosus. In Costalimai infected C. callosus practically no histopathological alterations were observed.

Phenotypes of lung mononuclear phagocytes in HIV seronegative tuberculosis patients: evidence for new recruitment and cell activation

Mycobacterium tuberculosis preferentially resides in mononuclear phagocytes. The mechanisms by which mononuclear phagocytes keep M. tuberculosis in check or by which the microbe evades control to cause disease remain poorly understood. As an initial effort to delineate these mechanisms, we examined by immunostaining the phenotype of mononuclear phagocytes obtained from lungs of patients with active tuberculosis. From August 1994 to March 1995, consecutive patients who had an abnormal chest X-ray, no demostrable acid-fast bacilli in sputum specimens and required a diagnostic bronchoalveolar lavage (BAL) were enrolled. Of the 39 patients enrolled, 21 had microbiologically diagnosed tuberculosis. Thirteen of the 21 tuberculosis patients were either HIV seronegative (n = 12) or had no risk factor for HIV and constituted the tuberculosis group. For comparison, M. tuberculosis negative patients who had BAL samples taken during this time (n = 9) or normal healthy volunteers (n = 3) served as control group. Compared to the control group, the tuberculosis group had significantly higher proportion of cells expressing markers of young monocytes (UCHM1) and RFD7, a marker for phagocytic cells, and increased expression of HLA-DR, a marker of cell activation. In addition, tuberculosis group had significantly higher proportion of cells expressing dendritic cell marker (RFD1) and epithelioid cell marker (RFD9). These data suggest that despite recruitment of monocytes probably from the peripheral blood and local cell activation, host defense of the resident lung cells is insufficient to control M. tuberculosis.

The Role of Protein Kinases in Antigen-activation of Peripheral Blood Mononuclear Cells of Schistosoma mansoni Infected Individuals

T cell recognition of antigens displayed on the surface of antigen presenting cell results in rapid activation of protein tyrosine kinases and kinase C. This process leads to second messengers, such as inositol phosphates and diacylgycerol, and phosphorylation of multiple proteins. The role of different protein kinases in the activation of peripheral blood mononuclear cells (PBMC) from Schistosoma mansoni infected individuals was evaluated using genistein and H-7, specific inhibitors of protein tyrosine kinase and kinase C, respectively. Our results showed that proliferation in response to soluble egg antigen or adult worm antigen preparation of S. mansoni was reduced when PBMC were cultured in presence of protein kinase inhibitors. Using these inhibitors on in vitro granuloma reaction, we also observed a marked reduction of granuloma index. Taken together, our results suggest that S. mansoni antigen activation of PBMC involves protein kinases activity

Signal transduction and activation of the NADPH oxidase in eosinophils

Activation of the eosinophil NADPH oxidase and the subsequent release of toxic oxygen radicals has been implicated in the mechanism of parasite killing and inflammation. At present, little is known of the signal transduction pathway that govern agonist-induced activation of the respiratory burst and is the subject of this review. In particular, we focus on the ability of leukotrine B4 to activate the NADPH oxidase in guinea-pig peritoneal eosinophils which can be obtained in sufficient number and purity for detailed biochemical experiments to be performed.

The spleen is an important site of T cell activation during human hepatosplenic schistosomiasis

We have undertaken a comparative immunephenotypic study of spleen cells from hepatosplenic patients (HS) and uninfected individuals (NOR) using flow cytometry. Our data did not show any significant differences in the mean percentage of T-cells and B-cells between the two groups. Analysis of activated T-cells demonstrated that HS present an increased percentage of CD3+HLA-DR+ splenocytes in comparison to NOR. Analysis of T-cell subsets demonstrated a significant increase on the percentage of both activated CD4+ T-splenocytes and CD8+ cells in HS. We did not find any difference in the mean percentage of CD28+ T-cells. Analysis of the B-cell compartment did not show any difference on the percentage of B1-splenocytes. However, the spleen seems to be an important reservoir/source for B1 lymphocytes during hepatosplenic disease, since after splenectomy we found a decreased the percentage of circulating B1-lymphocytes. We observed an increase on the percentage of CD2+CD3- lymphocytes in the spleen of HS suggesting that the loss of CD3 by activated T-cells or the expansion of NK-cells might play a role in the development/maintenance of splenomegaly.

In vivo lymphocyte activation and apoptosis by lectins of the Diocleinae subtribe

This paper reports the overall effects of three lectins, extracted from Canavalia brasiliensis, Dioclea violacea, and D. grandiflora, on BALB/c mice popliteal draining lymph nodes. These lectins have presented high stimulatory capacity on lymph node T cells. Additionally, they were able to induce apoptosis and inflammation (frequently associated with high endothelial venule necrosis). The data presented here suggest that the Diocleinae lectins studied can stimulate in vivo T cell activation and apoptosis, as well as present important side effects.

Kinetics of T cell-activation molecules in response to Mycobacterium tuberculosis antigens

The phenotypic features acquired subsequent to antigen-specific stimulation in vitro were evaluated by means of the kinetic expressions of CD69 and CD25 activation molecules on T lymphocytes and assayed by flow cytometry in response to PPD, Ag85B, and ferritin in PPD-positive healthy control individuals. In response to PHA, CD69 staining on both CD4+ and CD8+ T cells became initially marked after 4 h, peaked at 24 h, and quickly decreased after 120 h. For CD25, a latter expression was detected around 8 h, having increased after 96 h. As expected, the response rate to the mycobacterial antigens was much lower than that to the mitogen. Positive staining was high after 96 h for CD25 and after 24 h for CD69. CD69 expression was significantly enhanced (p < 0.05) on CD8+ as compared to CD4+ T cells. High levels were also found between 96-120 h. Regarding Ag85B, CD25+ cells were mostly CD4+ instead of CD8+ T cells. Moreover, in response to ferritin, a lower CD25 expression was noted. The present data will allow further characterization of the immune response to new mycobacterial-specific antigens and their evaluation for possible inclusion in developing new diagnostic techniques for tuberculosis as well in a new vaccine to prevent the disease.

The pathogenesis of diabetic complications: the role of DNA injury and poly(ADP-ribose) polymerase activation in peroxynitrite-mediated cytotoxicity

Recent work has demonstrated that hyperglycemia-induced overproduction of superoxide by the mitochondrial electron-transport chain triggers several pathways of injury [(protein kinase C (PKC), hexosamine and polyol pathway fluxes, advanced glycation end product formation (AGE)] involved in the pathogenesis of diabetic complications by inhibiting glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. Increased oxidative and nitrosative stress activates the nuclear enzyme, poly(ADP-ribose) polymerase-1 (PARP). PARP activation, on one hand, depletes its substrate, NAD+, slowing the rate of glycolysis, electron transport and ATP formation. On the other hand, PARP activation results in inhibition of GAPDH by poly-ADP-ribosylation. These processes result in acute endothelial dysfunction in diabetic blood vessels, which importantly contributes to the development of various diabetic complications. Accordingly, hyperglycemia-induced activation of PKC and AGE formation are prevented by inhibition of PARP activity. Furthermore, inhibition of PARP protects against diabetic cardiovascular dysfunction in rodent models of cardiomyopathy, nephropathy, neuropathy, and retinopathy. PARP activation is also present in microvasculature of human diabetic subjects. The present review focuses on the role of PARP in diabetic complications and emphasizes the therapeutic potential of PARP inhibition in the prevention or reversal of diabetic complications.

Dengue-2 and yellow fever 17DD viruses infect human dendritic cells, resulting in an induction of activation markers, cytokines and chemokines and secretion of different TNF-α and IFN-α profiles

Flaviviruses cause severe acute febrile and haemorrhagic infections, including dengue and yellow fever and the pathogenesis of these infections is caused by an exacerbated immune response. Dendritic cells (DCs) are targets for dengue virus (DENV) and yellow fever virus (YF) replication and are the first cell population to interact with these viruses during a natural infection, which leads to an induction of protective immunity in humans. We studied the infectivity of DENV2 (strain 16681), a YF vaccine (YF17DD) and a chimeric YF17D/DENV2 vaccine in monocyte-derived DCs in vitro with regard to cell maturation, activation and cytokine production. Higher viral antigen positive cell frequencies were observed for DENV2 when compared with both vaccine viruses. Flavivirus-infected cultures exhibited dendritic cell activation and maturation molecules. CD38 expression on DCs was enhanced for both DENV2 and YF17DD, whereas OX40L expression was decreased as compared to mock-stimulated cells, suggesting that a T helper 1 profile is favoured. Tumor necrosis factor (TNF)-α production in cell cultures was significantly higher in DENV2-infected cultures than in cultures infected with YF17DD or YF17D/DENV. In contrast, the vaccines induced higher IFN-α levels than DENV2. The differential cytokine production indicates that DENV2 results in TNF induction, which discriminates it from vaccine viruses that preferentially stimulate interferon expression. These differential response profiles may influence the pathogenic infection outcome.

Recognition of enteroinvasive Escherichia coli and Shigella flexneri by dendritic cells: distinct dendritic cell activation states

The innate and adaptive immune responses of dendritic cells (DCs) to enteroinvasive Escherichia coli (EIEC) infection were compared with DC responses to Shigella flexneri infection. EIEC triggered DCs to produce interleukin (IL)-10, IL-12 and tumour necrosis factor (TNF)-α, whereas S. flexneri induced only the production of TNF-α. Unlike S. flexneri, EIEC strongly increased the expression of toll like receptor (TLR)-4 and TLR-5 in DCs and diminished the expression of co-stimulatory molecules that may cooperate to inhibit CD4+ T-lymphocyte proliferation. The inflammation elicited by EIEC seems to be related to innate immunity both because of the aforementioned results and because only EIEC were able to stimulate DC transmigration across polarised Caco-2 cell monolayers, a mechanism likely to be associated with the secretion of CC chemokine ligands (CCL)20 and TNF-α. Understanding intestinal DC biology is critical to unravelling the infection strategies of EIEC and may aid in the design of treatments for infectious diseases.

Enhanced T cell activation in Plasmodium falciparum malaria-infected human immunodeficiency virus-1 patients from Mozambique

Human immunodeficiency virus (HIV)-1 infection has an important impact on malaria. Plasmodium falciparum and HIV-1 co-infected patients (Pf/HIV) present with a high degree of anaemia, enhanced parasitaemia and decreased CD4+ T cell counts, which increase the risk of developing severe malaria. In addition, infection with either Pf or HIV-1 alone causes extensive immune activation. Our hypothesis was that lymphocyte activation is potentiated in Pf/HIV co-infected patients, consequently worsening their immunosuppressed state. To test this hypothesis, 22 Pf/HIV patients, 34 malaria patients, 29 HIV/AIDS patients and 10 healthy controls without malaria or HIV/acquired immune deficiency syndrome (AIDS) from Maputo/Mozambique were recruited for this study. As expected, anaemia was most prevalent in the Pf/HIV group. A significant variation in parasite density was observed in the Pf/HIV co-infected group (110-75,000 parasites/µL), although the median values were similar to those of the malaria only patients. The CD4+ T cell counts were significantly lower in the Pf/HIV group than in the HIV/AIDS only or malaria only patients. Lymphocyte activation was evaluated by the percentage of activation-associated molecules [CD38 expression on CD8+ and human leukocyte antigen-DR expression on CD3+ T cells]. The highest CD38 expression was detected in the Pf/HIV co-infected patients (median = 78.2%). The malaria only (median = 50%) and HIV/AIDS only (median = 52%) patients also exhibited elevated levels of these molecules, although the values were lower than those of the Pf/HIV co-infected cases. Our findings suggest that enhanced T-cell activation in co-infected patients can worsen the immune response to both diseases.

Studies on the acid activation of Brazilian smectitic clays

Fuller's earth and acid activated smectitic clays are largely used as bleaching earth for the industrial processing of vegetable, animal and mineral oils and waxes. The paper comments about the nomenclature used for these materials, the nature of the acid activation of smectitic clays (bentonites), activation laboratory procedures and presents a review of the acid activation of bentonites from 20 deposits from several regions of Brazil. The activated clays were tested and show good decolorizing power for soybean, castor, cottonseed, corn and sunflower oils.

MICROWAVE ACTIVATION OF IMMOBILIZED LIPASE FOR TRANSESTERIFICATION OF VEGETABLE OILS

This work investigated the effect of microwave irradiation (MW) on the ethanolysis rate of soybean and sunflower oils catalyzed by supported Novozyme 435 (Candida antarctica). The effects of tert-butanol, water addition and oil:ethanol molar ratio on transesterification were evaluated under conventional heating (CH), and under optimum reaction conditions (with no added water in the system, 10% tert-butanol and 3:1 ethanol-to-oil molar ratio). The reactions were monitored up to 24 h to determine the conditions of initial reaction velocity. The investigated variables under MW (50 W) were: reaction time (5.0-180 min) and mode of reactor operation (fixed power, dynamic and cycles) in the absence and presence of tert-butanol (10% (w/w). The measured response was the reaction conversion in ethyl esters, which was linked to the enzyme catalytic activity. The results indicated that the use of microwave improved the activity at fixed power mode. A positive effect of the association of tert-butanol and MW irradiation on the catalytic activity was observed. The reaction rate improved in the order of approximately 1.5 fold compared to that under CH with soybean oil. Using soybean oil, the enzymatic transesterification under MW for conversion to FAEE (fatty acid ethyl esters) reached >99% in 3h, while with the use of CH the conversions were about 57% under similar conditions.

Avaliação da proteína acídica fibrilar glial como marcador da injúria por isquemia-reperfusão hepática

OBJETIVO: Avaliar a expressão da Proteína Acídica Fibrilar Glial após a injúria por isquemia-reperfusão. MÉTODOS: vinte e quatro ratos foram distribuídos em quatro grupos: Controle, submetidos à anestesia e biópsia hepática; Simulação, injeção de heparina através da veia cava e dissecção do pedículo hepático superior, biópsia após 24 horas; Isquemia 30 minutos, mesmo procedimento do grupo Simulação, acrescido de clampeamento do pedículo hepático superior por 30 minutos; Isquemia 90 minutos, mesmo procedimento do grupo Isquemia 30 minutos, porém com período de clampeamento de 90 minutos. Após 24 horas de observação, os animais foram submetidos à laparotomia e seus fígados avaliados macroscopicamente, microscopicamente, por coloração de Hematoxilina-Eosina (HE) e submetidos à análise da expressão da GFAP por Western Blotting. RESULTADOS: Não se observou diferença no aspecto macroscópico dos fígados entre os diferentes grupos experimentais, tendo todos evidenciado morfologia normal. A análise por HE não evidenciou diferenças significativas, no que diz respeito à morfologia lobular. Por outro lado, nos grupos isquemia, foram encontrados infiltrados neutrofílicos e pequenas áreas de necrose. A expressão de GFAP foi semelhante em todos os grupos, seja qualitativamente quanto quantitativamente. CONCLUSÃO: A expressão da Proteína Acídica Fibrilar Glial não se alterou em nosso modelo de isquemia-reperfusão.