Efeito de metabólitos secretados por Cryptococcus neoformans na interação com macrófagos murinos

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, Pós-graduação em Medicina Tropical, 2017.Texto parcialmente liberado pelo autor. Conteúdo restrito: Capítulos 5,6,7 e 8.O fungo Cryptococcus neoformans é um agente causador da micose sistêmica criptococose, que tem levado a óbito cerca de 181 mil pessoas por ano ao redor do mundo. A doença atinge principalmente pessoas imunodeprimidas e adquiriu maior importância clínica a partir da década de 1980, com o aparecimento da AIDS. Como em outras doenças fúngicas, o diagnóstico e o tratamento dessa doença ainda não são ideais, reforçando a necessidade de estudar-se melhor a relação parasito-hospedeiro na busca por melhores estratégias para reverter esses problemas. Nos últimos anos tem se mostrado que pequenos metabólitos podem ter um importante papel na interação parasita-hospedeiro. Demonstrou-se previamente, que moléculas de baixo peso molecular (menor que 1 KDa) presentes no meio condicionado (CM) de culturas estacionários de C. neoformans da linhagem H99, afetavam o crescimento planctônico e em biofilmes desse fungo, bem como a produção de melanina e a secreção de polissacarídeos capsulares por esse fungo. Em continuidade a esses estudos, no presente trabalho analisou-se a influência dessas mesmas moléculas secretadas pelo fungo na sua interação com macrófagos murinos primários. Fungos e macrófagos foram co-incubados por períodos de 2h ou 24h em uma razão de infecção de 2:1 na presença ou não do CM e foram analisados os possíveis efeitos na fagocitose dos fungos, na sobrevivência fúngica pós-interação e na produção de citocinas por esses macrófagos (TNF-α, IL-12, IL-1β, IL-6 e MCP-1, e IL-10). Observou-se uma potencial atividade antifagocítica de metabólitos presentes no CM, uma vez que na presença do CM houve um menor percentual de fagocitose dos fungos. Além disso, o CM produziu um aumento significativo no número de unidades formadoras de colônia do fungo após a interação com os macrófagos por 24h, sugerindo, portanto, a possibilidade de existir nessas amostras, moléculas capazes de estimular o crescimento extra e/ou intracelular do fungo. Interessantemente, após 24 h de fagocitose, observa-se um número bem menor de fungos intracelulares nos macrófagos contendo fungo, do que nas amostras controle sem CM. A produção de citocinas só foi avaliada no período de 2h de interação e não foram observadas diferenças significativas na produção de TNF-α, IL-1β, IL-6, apenas uma diminuição da produção de MCP-1 na presença de CM indicando um potencial papel anti-inflamatório de moléculas presentes nessa amostra. Em resumo, foi possível constatar que os pequenos metabólitos presentes no CM podem afetar a viabilidade e/ou crescimento fúngico na sua interação com macrófagos, possivelmente inibindo a sua internalização por fagócitos e inibindo a produção de citocinas pró-inflamatórias. Dessa maneira, um maior conhecimento das moléculas presentes no CM bem com o melhor detalhamento de suas atividades podem ajudar no melhor entendimento das interações fungo-hospedeiro na criptococcose.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).The fungus Cryptococcus neoformans is a causative agent of the systemic mycosis cryptococcosis, a disease leading to about 181 thousand deaths per year worldwide. The disease affects mainly immunocompromised individuals and gained greater clinical importance from the 1980s, with the onset of AIDS. As in other fungal diseases, the diagnosis and treatment of this pathology is still far from ideal, reinforcing the need to better study the host-parasite interaction in the seek for best strategies to revert these problems. In the recent years, small metabolites were shown to play important roles in host-parasite interactions. It was previously demonstrated that low molecular weight molecules (lower than 1 KDa), present in conditioned medium (CM) from stationary cultures of C. neoformans strain H99, affected the planktonic and biofilm growth of this fungus, as well the production of melanin and secretion of capsular polysaccharides by this fungus. To further study the role of those molecules, in the present work we analyzed the influence of these secreted molecules, during fungal interaction with primary murine macrophages. Fungal cells and macrophages were co-incubated for periods of 2h or 24h in an infection ratio of 2:1, in the presence or absence of CM. Then we analyzed the possible effects of these molecules on fungal phagocytosis by macrophages, fungal survival, and macrophage cytokine production (TNF-α, IL-12, IL-1β, IL-6, MCP-1, and IL-10). We observed a potential anti-phagocytic activity of metabolites present in CM, which samples showed a lower percentage of fungal internalization. In addition, the CM produced a significant increase in the number of colony forming units of the fungus, obtained after 24h interaction with macrophages. This suggests that molecules capable to stimulate the extra and/or intracellular growth of the fungus might exist in these samples. Interestingly, after 24h phagocytosis, a significantly lower number of intracellular fungi were observed in fungus-containing macrophages when compared to control samples without CM. The production of cytokines was evaluated only within a period of 2h interaction and no significant differences were observed in the production of TNF-α, IL-1β, IL-6. Only a decrease in the production of MCP-1 in the presence of CM was detected, suggesting a potential anti-inflammatory role of the molecules present in this sample. In summary, it was possible to confirm that small metabolites present in CM might affect fungal viability and/or growth while interacting with macrophages, possibly inhibiting their internalization by these phagocytes and the production of pro-inflammatory cytokines. Thus, a better characterization of the molecules present in CM and of their activities could improve the understanding of fungus-host interactions in cryptococcosis

Assessment of the current climate and expected climate changes in the Metropolitan Region of Santiago de Chile

This report describes the methodology and results from the analysis of climate scenarios and their impact on hydrometeorological variables in the Metropolitan Region of Santiago de Chile (MRS). Using a downscaling methodology for future scenarios A2 and B1, according to IPCC, temperature, precipitation and secondary variable trends were estimated for the time-window 2045-2065. The main results predict that Santiago will be a dryer and hotter city in the near future, with a high number of days with extreme temperatures. Due to lower precipitation rates, decreasing magnitudes in the streamflow of the two main rivers, Maipo and Mapocho, are expected. The presented data provide a basis for the ClimateAdaptationSantiago (CAS) project as the aim of that project is to elaborate, evaluate and prioritize adaptation measures to the climate change in the MRS

CMIP5 Projected Changes in the Annual Cycle of Precipitation in Monsoon Regions

Analyses of phase 5 of the Coupled Model Intercomparison Project (CMIP5) experiments show that the global monsoon is expected to increase in area, precipitation, and intensity as the climate system responds to anthropogenic forcing. Concurrently, detailed analyses for several individual monsoons indicate a redistribution of rainfall from early to late in the rainy season. This analysis examines CMIP5 projected changes in the annual cycle of precipitation in monsoon regions, using a moist static energy framework to evaluate competing mechanisms identified to be important in precipitation changes over land. In the presence of sufficient surface moisture, the local response to the increase in downwelling energy is characterized by increased evaporation, increased low-level moist static energy, and decreased stability with consequent increases in precipitation. A remote mechanism begins with warmer oceans and operates on land regions via a warmer tropical troposphere, increased stability, and decreased precipitation. The remote mechanism controls the projected changes during winter, and the local mechanism controls the switch to increased precipitation during summer in most monsoon regions. During the early summer transition, regions where boundary layer moisture availability is reduced owing to decreases in evaporation and moisture convergence experience an enhanced convective barrier. Regions characterized by adequate evaporation and moisture convergence do not experience reductions in early summer precipitation.This enhanced convective barrier leads to a redistribution of rainfall from early to late summer, and is robust in the American and African monsoons but muddled in Asia. As described here, viewing monsoons from their inherent ties to the annual cycle could help to fingerprint changes as they evolve

Monsoon Responses to Climate Changes—Connecting Past, Present and Future

Purpose of Review: Knowledge of how monsoons will respond to external forcings through the twenty-first century has been confounded by incomplete theories of tropical climate and insufficient representation in climate models. This review highlights recent insights from past warm climates and historical trends that can inform our understanding of monsoon evolution in the context of an emerging energetic framework. Recent Findings: Projections consistent with paleoclimate evidence and theory indicate expanded/wetter monsoons in Africa and Asia, with continued uncertainty in the Americas. Twentieth century observations are not congruent with expectations of monsoon responses to radiative forcing from greenhouse gases, due to the confounding effect of aerosols. Lines of evidence from warm climate analogues indicate that while monsoons respond in globally coherent and predictable ways to orbital forcing and inter-hemispheric thermal gradients, there are differences in response to these forcings and also between land and ocean. Summary: Further understanding of monsoon responses to climate change will require refinement of the energetic framework to incorporate zonal asymmetries and the use of model hierarchies

Climate change affects rainfall patterns in crop-producing regions: Findings from the study “Emergence of robust precipitation changes across crop production areas in the 21st century"

Rain-fed agriculture currently constitutes 60–95% of farmed land across the developing world. Changing rainfall patterns could have a large impact on agriculture in developing countries. Using over 20 different climate models, researchers have projected how precipitation could be affected by climate change. Key takeaways include: 1) unless emissions are curbed soon, by 2040, the rainfall patterns in many major wheat, soybean, rice and maize regions will have changed outside their natural boundaries; 2) emissions reductions in accordance with the Paris Agreement would result in far less crop-producing areas experiencing novel rainfall patterns; and 3) targeting adaptation efforts remains a major challenge, but region specific results can now enable investment and action

Emergence of robust precipitation changes across crop production areas in the 21st century

A warming climate will affect regional precipitation and hence food supply. However, only a few regions around the world are currently undergoing precipitation changes that can be attributed to climate change. Knowing when such changes are projected to emerge outside natural variability—the time of emergence (TOE)—is critical for taking effective adaptation measures. Using ensemble climate projections, we determine the TOE of regional precipitation changes globally and in particular for the growing areas of four major crops. We find relatively early (<2040) emergence of precipitation trends for all four crops. Reduced (increased) precipitation trends encompass 1–14% (3–31%) of global production of maize, wheat, rice, and soybean. Comparing results for RCP8.5 and RCP2.6 clearly shows that emissions compatible with the Paris Agreement result in far less cropped land experiencing novel climates. However, the existence of a TOE, even under the lowest emission scenario, and a small probability for early emergence emphasize the urgent need for adaptation measures. We also show how both the urgency of adaptation and the extent of mitigation vary geographically