Response of Cytokines and Hydrogen Peroxide to Sporothrix schenckii Exoantigen in Systemic Experimental Infection.

The response of hydrogen peroxide (H2O2) and cytokines during an experimental sporotrichosis in male Swiss mice was assessed over a period of 10 weeks by monitoring macrophage activation challenged with exoantigen (ExoAg) from the fungus Sporothrix schenckii. The studied endpoints were: H2O2 production, fungal burden at spleen, apoptosis in peritoneal macrophages, and IL-1ß, IL-6, IL-2, IL-10 production. During the two first weeks of infection was observed low burden of yeast in spleen and high response of H2O2, IL-2, and IL-1ß. The weeks of highest fungal burden (fourth-sixth) coincided with major apoptosis in peritoneal macrophages, normal production of IL-6 and lower production of H2O2, IL-2, and IL-1ß, suggesting a role for these three last in the early control of infection. On the other hand, IL-1ß (but not IL-6) was recovered since the sixth week, suggesting a possible role in the late phase of infection, contributing to the fungal clearance in conjunction with the specific mechanisms. The IL-10 was elevated until the sixth, principally in the second week. These results evidences that ExoAg is involved in the host immune modulation, influencing the S. Schenckii virulence, and its role is related with the time of the infection in the model used.

Involvement of major components from Sporothrix schenckii cell wall in the caspase-1 activation, nitric oxide and cytokines production during experimental sporotrichosis.

Sporotrichosis is a chronic infection caused by the dimorphic fungus Sporothrix schenckii, involving all layers of skin and the subcutaneous tissue. The role of innate immune toll-like receptors 2 and 4 in the defense against this fungus has been reported, but so far, there were no studies on the effect of cell wall major components over the cytosolic oligo-merization domain (NOD)-like receptors, important regulators of inflammation and responsible for the maturation of IL-1ß and IL-18, whose functions are dependents of the caspase-1 activation, that can participate of inflammasome. It was evaluated the percentage of activation of caspase-1, the production of IL-1ß, IL-18, IL-17, IFN-γ and nitric oxide in a Balb/c model of S. schenckii infection. It was observed a decreased activity of caspase-1 during the fourth and sixth weeks of infection accompanied by reduced secretion of the cytokines IL-1ß, IL-18 and IL-17 and high production of nitric oxide. IFN-γ levels were elevated during the entire time course of infection. This temporal reduction in caspase-1 activity coincides exactly with the reported period of fungal burden associated with a transitory immunosuppression induced by this fungus and detected in similar infection models. These results indicate the importance of interaction between caspase-1, cytokines IL-1ß and IL-18 in the host defense against S. schenckii infection, suggesting a participation the inflammasome in this response.

The predominance of alternatively activated macrophages following challenge with cell wall peptide-polysaccharide after prior infection with Sporothrix schenckii.

Sporotrichosis is a subcutaneous mycosis that is caused by the dimorphic fungus Sporothrix schenckii. This disease generally occurs within the skin and subcutaneous tissues, causing lesions that can spread through adjacent lymphatic vessels and sometimes leading to systemic diseases in immunocompromised patients. Macrophages are crucial for proper immune responses against a variety of pathogens. Furthermore, macrophages can play different roles in response to different microorganisms and forms of activation, and they can be divided into "classic" or "alternatively" activated populations, as also known as M1 and M2 macrophages. M1 cells can lead to tissue injury and contribute to pathogenesis, whereas M2 cells promote angiogenesis, tissue remodeling, and repair. The aim of this study was to investigate the roles of M1 and M2 macrophages in a sporotrichosis model. Toward this end, we performed phenotyping of peritoneal exudate cells and evaluated the concomitant production of several immunomediators, including IL-12, IL-10, TGF-ß, nitric oxide, and arginase-I activity, which were stimulated ex vivo with cell wall peptide-polysaccharide. Our results showed the predominance of the M2 macrophage population, indicated by peaks of arginase-I activity as well as IL-10 and TGF-ß production during the 6th and 8th weeks after infection. These results were consistent with cellular phenotyping that revealed increases in CD206-positive cells over this period. This is the first report of the participation of M2 macrophages in sporotrichosis infections.

Current research on the immune response to experimental sporotrichosis.

Sporotrichosis is often manifested as a chronic granulomatous infection and the monocytes/macrophages play a central role in the host defense system. Surface components of Sporothrix schenckii have been characterized and suggestions have been made as to their possible role in pathogenicity. Ergosterol peroxide, cell-wall compounds (alkali-insoluble fraction-F1 and lipid extract-LEY), and exoantigen from the yeast form of the fungus have been characterized as virulence factors, activating both innate, by cytotoxins linked to the activation of reactive oxygen and nitrogen species (H2O2 and NO), and adaptive immune response to produce cytokines Th1 and Th2 profile. In this study, preliminary results have demonstrated that, in systemic sporotrichosis, TLR-4 triggers the innate immune response, activating an oxidative burst. These data represent the first report of the participation of TLR-4 in murine sporotrichosis, in the presence of lipids from the cell wall of S. schenckii. These results taken together may open new perspectives of study leading to an antifungal agent that could be used to benefit the entire population.

Optimal clearance of Sporothrix schenckii requires an intact Th17 response in a mouse model of systemic infection.

The discovery of Th17 cells, along with many other Th cell subsets in the recent years, has expanded the Th1/Th2 paradigm that had persisted since its proposition by Mosmann in 1986. Defined by the characteristic expression of the transcription factor retinoic-related orphan receptor γt (RORγt) and production of IL-17A (IL-17), Th17 cells are powerful inducers of tissue inflammation with a recognized role against extracellular bacteria and fungi. Despite this, the interest in their study came from the pivotal role they play in the development and maintenance of major chronic inflammatory conditions such as multiple sclerosis, rheumatoid arthritis and Crohn's disease, hence they have been the target of promising new anti-Th17 therapies. Accordingly, the identification of opportunistic pathogens whose clearance relies on the Th17 response is of huge prophylactic importance. As shown here for the first time, this applies to Sporothrix schenckii, a thermo-dimorphic fungus and the causative agent of sporotrichosis. Our results show that both Th17 and Th1/Th17 mixed cells are developed during the S. schenckii systemic mice infection, which also leads to augmented production of IL-17 and IL-22. Also, by using an antibody-mediated IL-23 depletion model, we further demonstrate that optimal fungal clearance, but not survival, depends on an intact Th17 response.

A soy-based product fermented by Enterococcus faecium and Lactobacillus helveticus inhibits the development of murine breast adenocarcinoma.

PURPOSE: Soy and its fermented products are considered functional foods. The study objective was to assess three functional food - a non-fermented soy product (NFP), fermented soy product (FSP), fermented soy product enriched with isoflavones (FI) - in terms of their ability to reduce the development of adenocarcinoma in mice, as well their ability on modulating immune system. METHODS: It was observed tumor volume and to verify correlations with the immune system it was measured levels of the cytokines IL-1ß and TNF-α produced by macrophages as well as IFN-γ produced by lymphocytes using ELISA test, and nitric oxide production by macrophages using Griess reagent. RESULTS: All products showed immunological activity, but FSP showed the most effective tumor containment, resulting in smallest tumor volumes. FI animals expressed larger amounts of nitric oxide and IL-1ß and exhibited larger tumor sizes than FSP and NFP animals. CONCLUSIONS: The results suggested that the ingestion of FSP was most efficient in tumor containment, possibly due to a positive modulation of the immune system by when Enterococcus faecium and Lactobacillus helveticus are added to the soy product.

Avaliação preliminar da associação entre anfotericina e hesperina com oxidantes e células huvec / Preliminary assessment of the association between amphotericin and hesperetin with oxididants and huvec cells

A anfotericina B (AmB) é fármaco o “padrão ouro” para o tratamento de infecções fúngicas invasivas desde 1960, Entretanto, a anfotericina B apresenta elevada toxicidade, a qual manifesta-se mais frequentemente nos rins e no fígado, Sabe-se, desde 1985, que a auto-oxidação da AmB origina diferentes formas de espécies reativas oxidativas e estas, por serem tóxicas para a célula, seriam responsáveis, em parte, pela toxicidade, Diferentes estudos indicam que a hesperidina contribui por meio do decréscimo do estresse oxidativo, para a proteção renal e contra a injúria gerada pela isquemia, Tal fato e o envolvimento da AmB na geração de radicais livres tornam interessante a avaliação preliminar do efeito da hesperidina e AmB (isoladamente ou associadas) frente a espécies reativas do oxigênio e radicais livres, bem como o estudo das mesmas em modelos de citoxicidade, Frente ao ABTS•+, a AmB apresentou IC50 igual a 0,0124mg/mL, mas quando associada à hesperidina este valor caiu para 0,0003mg/mL, Frente ao HOCl, a Amb apresentou IC50 igual a 0,0056, mas quando associada à hesperidina este valor caiu para 0,0023mg/mL, No ensaio com DPPH• e radical ânion superóxido as amostras não foram efetivas, No ensaio com células endoteliais em cultivo (HUVEC), as associações reduziram a viabilidade celular, Estes resultados preliminares evidenciam a interação dos compostos com espécies reativas bem como indicam possibilidade de exacerbação do dano pela AmB na presença dos antioxidantes em um modelo in vitro...

Amphotericin B (AmB) is drug “gold standard” for the treatment of invasive fungal infections since 1960. However, amphotericin B has high toxicity, which manifests itself most often in the kidneys and in the liver. It is known, since 1985, that self-oxidation of AmB gives different forms of reactive oxidative species and these, being toxic to the cell, would be responsible, in part, by its toxicity. Different studies indicate that hesperidin contributes, through the reduction of oxidative stress, to protect against renal injury generated by ischemia. This fact and the involvement of AmB in the generation of free radicals make it interesting the preliminary evaluation of the effect of hesperidin and AmB (alone or associated) against reactive oxygen species and free radicals, as well as the study on models of cytotoxicity. Front ABTS•+, AmB presented IC50 equal to 0.0124 mg/mL, but when it was associated to hesperidin this value has decreased to 0.0003 mg/mL. Front HOCl, Amb presented IC50 equal to 0.0056, but when it was associated to hesperidin this value has decreased to 0.0023 mg/mL. In the trials with DPPH• and the superoxide anion radical samples were not effective. In the assay with endotelial cell culture (HUVEC cells), the association has decreased cell viability. These preliminary results demonstrate the interaction of the compounds with reactive species as well as indicate the possibility of damage exacerbation by AmB in the presence of antioxidants in an in vitro model...

Influence of Th1/Th2 cytokines and nitric oxide in murine systemic infection induced by Sporothrix schenckii.

In an attempt to elucidate the effects of Sporothrix schenckii infection on the immune response, our laboratory has developed a murine model of disseminated sporotrichosis. Helper T cells can be further subdivided into Th1 and Th2 phenotypes. The differentiation of two subsets of T lymphocytes is driven by IL-12 and IL-4 cytokines, respectively. Th1 cells produce IFN-gamma that activate macrophages and promote cell-mediated immunity. In addition, we found low levels of iNOS and NO production in the initial (1st and 2nd weeks) and final (9th and 10th weeks) periods of the infection, in contrast with the period of week 4 to 7 of elevated values. The determination of IFN-gamma and IL-12 are in agreement with NO/iNOS detection, showing the presence of cellular immune response throughout the infectious process. However, the production of IL-4 shows an increase in levels after the 5th and 6th weeks suggesting a participation of Th2 response in this period as well. Regarding these results, the study demonstrated that in experimental sporotrichosis infection the cellular immune response participated throughout the period analyzed as a nitric oxide dependent mechanism. In contrast, the presence of Th2 response began in the 5th week, suggesting the participation of humoral immune response in advanced stages of sporotrichosis.

Liberaçäo de óxido nítrico e TNF alfa em macrófagos peritoneais na presença de Melampodium divaricatum (Asteraceae) / Release of nitric oxide and tumor necrosis factor alfa by peritoneal macrophages in the presence of Melampodium divaricatum (Asteraceae)

As respostas imunes säo mediadas por uma variedade de células e por moléculas que estas células secretam. Macrófagos säo as primeiras células a participarem da resposta imunológica, e quando säo ativados liberam mais de cem compostos no meio extracelular, entre eles várias citocinas(TNF-alfa) e compostos reativos intermediários de nitrogênio (NO). Neste trabalho, determinou-se a liberaçäo de óxido nítrico e TNF-alfa em culturas de macrófagos peritoneais de camundongos em presença de extrato etanólico 70 por cento bruto obtido a partir de flores de Melampodium divaricatum (Asteraceae) nas concentraçöes de 20, 10 e 5mg/ml. O extrato etanólico 70 por cento bruto de Melampodium divaricatum (flores) induziu grande liberaçäo de NO e TNF-alfa na concentraçäo de 20 mg/ml quando comparado com LPS. Concluiu-se que esse extrato é um potente estimulador de macrófagos, podendo apresentar atividade imunomoduladora.