Macrophage-pathogen interactions in infectious diseases: new therapeutic insights from the zebrafish host model

Studying macrophage biology in the context of a whole living organism provides unique possibilities to understand the contribution of this extremely dynamic cell subset in the reaction to infections, and has revealed the relevance of cellular and molecular processes that are fundamental to the cell-mediated innate immune response. In particular, various recently established zebrafish infectious disease models are contributing substantially to our understanding of the mechanisms by which different pathogens interact with macrophages and evade host innate immunity. Transgenic zebrafish lines with fluorescently labeled macrophages and other leukocyte populations enable non-invasive imaging at the optically transparent early life stages. Furthermore, there is a continuously expanding availability of vital reporters for subcellular compartments and for probing activation of immune defense mechanisms. These are powerful tools to visualize the activity of phagocytic cells in real time and shed light on the intriguing paradoxical roles of these cells in both limiting infection and supporting the dissemination of intracellular pathogens. This Review will discuss how several bacterial and fungal infection models in zebrafish embryos have led to new insights into the dynamic molecular and cellular mechanisms at play when pathogens encounter host macrophages. We also describe how these insights are inspiring novel therapeutic strategies for infectious disease treatment

Analysis tools to quantify dissemination of pathology in zebrafish larvae

We describe new open source software called QuantiFish for rapid quantitation of fluorescent foci in zebrafish larvae, to support infection research in this animal model. QuantiFish extends the conventional measurements of bacterial load and number of bacterial foci to include measures for dissemination of infection. These are represented by the proportions of bacteria between foci and their spatial distribution. We showcase these measures by comparison of intravenous and hindbrain routes of Mycobacterium marinum infection, which are indistinguishable by measurement of bacterial load and not consistently differentiated by the number of bacterial foci. The intravenous route showed dose dependent dissemination of infection, reflected by increased spatial dispersion of bacteria and lower proportions of bacteria distributed across many foci. In contrast, hindbrain infection resulted in localised disease, limited to a smaller area and higher proportions of bacteria distributed across fewer foci. The application of QuantiFish may extend beyond models of infection, to study other pathologies such as metastatic cancer

Body composition and cardiovascular risk factors in pretransplant hemodialysis patients

BACKGROUND: Obesity, hyperlipemia and cardiovascular complications contribute to a significant proportion of morbidity and mortality of renal transplant patients and have negative effects on renal survival. Aim of the present study was to evaluate the main abnormalities in body composition and the prevalence of some cardiovascular risk factors in a population of hemodialyzed (HD) patients awaiting renal transplantation. METHODS: We studied 151 HD patients, all included in a waiting list for renal transplantation, 97 males and 54 females, with mean age 47.4+/-12 years. Patients were divided into three groups according to their body mass index (BMI) (kg/m2): 18.5 to 24.9 (normoweight, NW); 25.0 to 29.9 (overweight, OW); > or =30 (obese, OB). The body composition measurements were obtained the day after the mid-week HD session using bioelectrical impedance analysis (BIA). RESULTS: We found that 47 patients were NW (31%), while 56 were OW (37%), and 48 were OB (32%). BIA-measured body cell mass was (BCM) significantly increased in the OW as compared with the NW group (P<0.001), but, of note, no significant difference was found in OB group in comparison with the OW. Total cholesterol and triglycerides plasma levels were significantly elevated in OW and OB patients with respect to NW (P<0.05) and an increased prevalence of diabetes was seen in OB patients (NW: 6%, OW: 5%, OB: 12%). CONCLUSIONS: These data show that a large proportion of patients awaiting renal transplant are overweight or obese and a consistent part of them have other cardiovascular risk factors associated. Furthermore, obese HD patients have a BCM lower than predicted on the basis of BMI and show an altered metabolic profile. A better understanding of the characteristics of patients included in the renal transplant waiting list is crucial in order to design prospective studies that aim to define the proper risk profile for the selection of patients

Transcriptional profiling of zebrafish identifies host factors controlling susceptibility to Shigella flexneri

Shigella flexneri is a human-adapted pathovar of Escherichia coli that can invade the intestinal epithelium, causing inflammation and bacillary dysentery. Although an important human pathogen, the host response to S. flexneri has not been fully described. Zebrafish larvae represent a valuable model to study human infections in vivo. Here we use a Shigella-zebrafish infection model to generate mRNA expression profiles of host response to Shigella infection at the whole animal level. Immune response-related processes dominate the signature of early Shigella infection (6 hours post-infection). Consistent with its clearance from the host, the signature of late Shigella infection (24 hours post-infection) is significantly changed, and only a small set of immune-related genes remain differentially expressed, including acod1 and gpr84. Using mutant lines generated by ENU, CRISPR mutagenesis and F0 Crispants, we show that acod1- and gpr84-deficient larvae are more susceptible to Shigella infection. Together, these results highlight the power of zebrafish to model infection by bacterial pathogens and reveal the mRNA expression of the early (acutely infected) and late (clearing) host response to Shigella infection

Shigella serotypes associated with carriage in humans establish persistent infection in zebrafish

Shigella represents a paraphyletic group of enteroinvasive Escherichia coli. More than 40 Shigella serotypes have been reported. However, most cases within the MSM (men who have sex with men) community are attributed to three serotypes: Shigella sonnei unique serotype and Shigella flexneri 2a and 3a serotypes. Using the zebrafish model, we demonstrate that Shigella can establish persistent infection in vivo. Bacteria are not cleared by the immune system and become antibiotic-tolerant. Persistence depends on O-Antigen, a key constituent of the bacterial surface and serotype determinant. Representative isolates associated with MSM transmission persist in zebrafish, while representative isolates of a serotype not associated with MSM transmission do not. Isolates of a Shigella serotype establishing persistent infections elicited significantly less macrophage death in vivo than isolates of a serotype unable to establish persistence. We conclude that zebrafish are a valuable platform to illuminate factors underlying establishment of Shigella persistent infection in humans

Does silicon and salicylic acid contribute in the morphophysiology of Schinus terebinthifolia seedlings under flooding?

Abstract Flooding can damage the photosynthetic apparatus and initial growth of Schinus terebinthifolia. We aimed this study evaluates the potential of silicon (Si) and salicylic acid (SA) as mitigating agents on the ecophysiological responses and initial growth of S. terebinthifolia subjected to flooding periods. Seedlings were grown under the following conditions: 1) control (non-flooded): daily irrigation, 2) Flooded (F): storage of seedlings in a 500 L plastic pool, keeping the water depth at ± 2.0 cm above the substrate level, 3) F + 1.0 mM Si, 4) F + 2.0 mM Si, 5) F + 1.5 mM SA, and 6) F + 3.0 mM SA, and evaluated to 15 and 30 days. We observed that flooded seedlings formed hypertrophied lenticels on the stem on the 7th day as a stress adjustment strategy. S. terebinthifolia is sensitive to flooding, although it maintains a stable gas exchange for up to 15 days in this condition. The applications of 1.0 mM Si mitigated the pronounced decrease of gas exchange by 30 days. Using 1.0 mM Si and 3.0 mM SA contributed for integrity of the photosynthetic apparatus and to photochemical activities in the reaction centers, in addition favors to higher seedling biomass and quality under flooding. Foliar application of Si and SA is promising practice for photosynthetic metabolic and initial growth of S. terebinthifolia seedlings under flooded stress

Shigella sonnei infection of zebrafish reveals that O-antigen mediates neutrophil tolerance and dysentery incidence.

Funder: Lister Institute of Preventive Medicine; funder-id: http://dx.doi.org/10.13039/501100001255Shigella flexneri is historically regarded as the primary agent of bacillary dysentery, yet the closely-related Shigella sonnei is replacing S. flexneri, especially in developing countries. The underlying reasons for this dramatic shift are mostly unknown. Using a zebrafish (Danio rerio) model of Shigella infection, we discover that S. sonnei is more virulent than S. flexneri in vivo. Whole animal dual-RNAseq and testing of bacterial mutants suggest that S. sonnei virulence depends on its O-antigen oligosaccharide (which is unique among Shigella species). We show in vivo using zebrafish and ex vivo using human neutrophils that S. sonnei O-antigen can mediate neutrophil tolerance. Consistent with this, we demonstrate that O-antigen enables S. sonnei to resist phagolysosome acidification and promotes neutrophil cell death. Chemical inhibition or promotion of phagolysosome maturation respectively decreases and increases neutrophil control of S. sonnei and zebrafish survival. Strikingly, larvae primed with a sublethal dose of S. sonnei are protected against a secondary lethal dose of S. sonnei in an O-antigen-dependent manner, indicating that exposure to O-antigen can train the innate immune system against S. sonnei. Collectively, these findings reveal O-antigen as an important therapeutic target against bacillary dysentery, and may explain the rapidly increasing S. sonnei burden in developing countries

Levantamento quantitativo de microrganismos solubilizadores de fosfatos na rizosfera de gramíneas e leguminosas forrageiras na Amazônia

After choosing a selective enrichment medium suitable for most phosphate solubilizing microorganisms, a quantitative survey of these was made in the rhizosphere of: Brachiaria decumbens, B. humidicola. Andropogon gayanus, Paspalum plicatum, Hyparrhenia rufa, Panicum maximum, Desmodium ovalifolium, Pueraria phaseoloides, Zornia sp., Stylosanthes capitata, S. guianensis (CIAT 136). and S. guianensis (IKE 1022, with and without fertilisers. The largest numbers of phosphate solubilizing bacteria (above 1 x 107/g rhizosphere) occurred in the rhizosphere of the leguminous species a nd small numbers (Belw 1 x 107/g rhizosphere) in grasses without fertilisers, except H. rufa and P. maximum. From all the fodder plants analysed, Zornia sp. (Leguminosae) with fertilizer, had the greatest number as phosphate solubilizers. The total number of microorganisms was greater in the treatments without fertilizer in all grasses analysed; but for the leguminous species it was greater for treatments with fertilizer except in S. capitata. Phosphore solubilizing fungi were not considered in this study because they present only in small numbers.Após a escolha de um meio de enriquecimento seletivo a um maior número de microrganismos solubilizadores de fosfatos, foi feito um levantamento quantitativo dessas bactérias na rizosfera de Brachiaria decumbens, B. humidicola; Andropogon gayanus, Paspalum plicatum, Hyparrhenia rufa, Panicum maximum, Desmodium ovalifolium, Pueraria phaseoloides, Zornia sp. Stylosanthes capitata, S. guianensis (ClAT 136) e S. guianensis (IRI 1022), adubadas e não adubadas. De um modo geral, números maiores de bactérias solubilizadoras de fosfatos (superior a 1 x 107/g rizosfera) ocorreram na rizosfera de leguminosas. adubadas e não adubadas, e os números mais baixos nas gramíneas (inferior a 1 x 107/g rizosfera). com exceção de H. rufa e P. maximum, sem adubação. De todas as forrageiras analisadas, a rizosfera de Zornia sp. adubada, foi a que melhor se apresentou tanto em número quanto em porcentagem de bactérias solubilizadoras. O número total de microrganismos foi maior nos tratamentos não adubados para todas as gramíneas analisadas e maior nos tratamentos adubados para todas as leguminosas com exceção de S. capitata. Os fungos solubilizadores de fosfatos, não foram considerados, uma vez que estavam presentes em quantidades bem pequenas

Acid hydrolysis of barley straw: study of lignocellulosic pretreatment conditions and batch reactor / Hidrólise ácida da palha de cevada: estudo das condições de pré-tratamento lignocelulósico e do reator de lote

O cultivo da cevada cresceu no Brasil nos últimos anos, atingindo uma produção anual de 1,5 milhão de toneladas. Este estudo teve como objetivo projetar e construir um reator para hidrólise ácida de materiais lignocelulósicos e investigar a liberação de açúcares fermentáveis da palha da cevada. Para orientar o desenvolvimento de um reator viável, foi realizado um planejamento experimental para investigar as condições de pré-tratamento com ácido sulfúrico. As variáveis independentes foram a relação palha de cevada / solução (5,0: 10, 1,0: 10, 1,5: 10 e 2,0: 10% p / v) e concentração de ácido sulfúrico (0,5, 0,8, 1,0, 1,5, 2,0, 2,5 e 3,0 % v / v). O pré-tratamento foi realizado por 40 min em autoclave vertical a 121 ° C e 1 kgf / cm2. As variáveis de resposta foram sólidos solúveis (° Bx) e o rendimento de glicose (razão em peso de glicose liberada para biomassa inicial de palha de cevada). Os resultados mostraram que as condições ótimas para a liberação de glicose e sólidos solúveis foram uma relação palha de cevada / solução de 7:10 (p / v) e 2,6% (% v / v) de ácido sulfúrico