CROSSTALK BETWEEN GASTROINTESTINAL EPITHELIAL CELLS AND RESIDENT MICROBIOTA PROMOTES IMMUNE HOMEOSTASIS

The gastrointestinal tract houses one of the most dense and diverse communities of bacteria on the planet. The mutualistic relationship between the host and commensal microbe permits the microbe an ideal environment to grow and provides the host with increased caloric intake, maturation of the adaptive immune system, and resistance against invading pathogens. To maintain a system in which both parties benefit, the epithelium has evolved numerous strategies to ensure epithelial cells respond to microbes appropriately and that potentially hazardous commensals remain distanced from the soma proper. Breakdown of these propitiating mechanisms elicits unchecked inflammation and can lead to pathology and reduction of host fitness. We show that oral and intestinal epithelial cells respond to the circulating hormone adiponectin in the presence of bacterial constituents, and that adiponectin has the potential to downregulate NF-κB signaling. We also show many commensal bacteria have no effect on TNF or IL-8 proinflammatory gene expression in intestinal cells. Commensals within the family Enterobacteriaceae can increase TNF and IL-8 expression, but also expression of the NF-κB regulator A20 and MAPK phosphatase MKP-1. Importantly, Enterobacteriaceae also increased expression of the IgA transporter pIgR. In the mouse model, we show pIgR expression along the intestinal epithelium is necessary for SIgA accumulation in the outer mucus layer where commensal bacteria reside. Loss of the mucus layer, but not pIgR is sufficient to allow direct bacterial-epithelial cell contact and induce spontaneous inflammation along the colon. Secretory IgA is supplied maternally through breast milk early in life to compensate for the neonate’s inability to produce sufficient endogenous amounts. By utilizing a breeding scheme in which mouse dams were unable to provide their offspring with SIgA, we show the necessity of maternally-supplied SIgA to control bacterial invasion to mesenteric lymph nodes before weaning. In addition, 8-10 week old adult offspring not receiving SIgA as neonates showed both a unique intestinal microbiota and different patterns of intestinal epithelial cell gene expression with and without chemically-induced acute colitis. In summary, we reveal new mechanisms the mammalian host utilizes in order to maintain peace between the commensal microbe and host immune system

Metabolic Evolution of a Deep-Branching Hyperthermophilic Chemoautotrophic Bacterium

Aquifex aeolicus is a deep-branching hyperthermophilic chemoautotrophic bacterium restricted to hydrothermal vents and hot springs. These characteristics make it an excellent model system for studying the early evolution of metabolism. Here we present the whole-genome metabolic network of this organism and examine in detail the driving forces that have shaped it. We make extensive use of phylometabolic analysis, a method we recently introduced that generates trees of metabolic phenotypes by integrating phylogenetic and metabolic constraints. We reconstruct the evolution of a range of metabolic sub-systems, including the reductive citric acid (rTCA) cycle, as well as the biosynthesis and functional roles of several amino acids and cofactors. We show that A. aeolicus uses the reconstructed ancestral pathways within many of these sub-systems, and highlight how the evolutionary interconnections between sub-systems facilitated several key innovations. Our analyses further highlight three general classes of driving forces in metabolic evolution. One is the duplication and divergence of genes for enzymes as these progress from lower to higher substrate specificity, improving the kinetics of certain sub-systems. A second is the kinetic optimization of established pathways through fusion of enzymes, or their organization into larger complexes. The third is the minimization of the ATP unit cost to synthesize biomass, improving thermodynamic efficiency. Quantifying the distribution of these classes of innovations across metabolic sub-systems and across the tree of life will allow us to assess how a tradeoff between maximizing growth rate and growth efficiency has shaped the long-term metabolic evolution of the biosphere.Comment: 25 pages, 5 figures, 5 tables, 2 supplementary file

A cluster or filament of galaxies at redshift z = 2.5?

We report the discovery of 56 new Lyα-emitting candidates (LECs) at redshift z ≈ 2.5 in a field of 8′ × 14′ around two previously known weak radio QSOs and a cosmic microwave background decrement (CMBD) that is plausibly due to the Sunyaev-Zeldovich effect. Broadband and medium-band imaging at the redshifted Lyα wavelength have allowed us to identify the LECs at the redshift of the QSOs. Three of the brightest LECs have been confirmed spectroscopically, with redshifts between z = 2.501 and z = 2.557; one of them is another QSO. Excluding the third QSO, the four spectroscopically confirmed objects form a 3′ filament with a rest-frame velocity dispersion of 1000 km s-1 lying adjacent to the CMBD, and there is a significant concentration of LECs at the northwest end of the filament around the brightest QSO. If confirmed, a velocity dispersion ~1000 km s-1 on a proper scale of ~1 Mpc at redshift z = 2.5 would, in and of itself, constrain the cosmological model to low Ω.Part of this work was supported by NASA grants AR-07551.01-96A (to AY), and GO-5985.01- 94A, GO-6610.01-95A, and GO.2684.03-94A (to RAW) from STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555.Peer Reviewe

Use of the atmospheric generators for capnophilic bacteria Genbag-CO2 for the evaluation of in vitro Plasmodium falciparum susceptibility to standard anti-malarial drugs

Background: The aim of this study was to evaluate the cultivation system in which the proper atmospheric conditions for growing Plasmodium falciparum parasites were maintained in a sealed bag. The Genbag (R) system associated with the atmospheric generators for capnophilic bacteria Genbag CO2 (R) was used for in vitro susceptibility test of nine standard anti-malarial drugs and compared to standard incubator conditions. Methods: The susceptibility of 36 pre-identified parasite strains from a wide panel of countries was assessed for nine standard anti-malarial drugs (chloroquine, quinine, mefloquine, monodesethylamodiaquine, lumefantrine, dihydroartemisinin, atovaquone and pyrimethamine) by the standard 42-hour H-3-hypoxanthine uptake inhibition method using the Genbag CO2 (R) system and compared to controlled incubator conditions (5% CO2 and 10% O-2). Results: The counts per minute values in the control wells in incubator atmospheric conditions (5% CO2 and 10% O-2) were significantly higher than those of Genbag (R) conditions (2738 cpm vs 2282 cpm, p < 0.0001). The geometric mean IC50 estimated under the incubator atmospheric conditions was significantly lower for atovaquone (1.2 vs 2.1 nM, p = 0.0011) and higher for the quinolines: chloroquine (127 vs 94 nM, p < 0.0001), quinine (580 vs 439 nM, p < 0.0001), monodesethylamodiaquine (41.4 vs 31.8 nM, p < 0.0001), mefloquine (57.5 vs 49.7 nM, p = 0.0011) and lumefantrine (23.8 vs 21.2 nM, p = 0.0044). There was no significant difference of IC50 between the 2 conditions for dihydroartemisinin, doxycycline and pyrimethamine. To reduce this difference in term of anti-malarial susceptibility, a specific cut-off was estimated for each drug under Genbag (R) conditions by regression. The cut-off was estimated at 77 nM for chloroquine (vs 100 nM in 10% O-2), 611 nM for quinine (vs 800 nM), 30 nM for mefloquine (vs 30 nM), 61 nM for monodesethylamodiaquine (vs 80 nM) and 1729 nM for pyrimethamine (vs 2000 nM). Conclusions: The atmospheric generators for capnophilic bacteria Genbag CO2 (R) is an appropriate technology that can be transferred to the field for epidemiological surveys of drug-resistant malaria. The present data suggest the importance of the gas mixture on in vitro microtest results for anti-malarial drugs and the importance of determining the microtest conditions before comparing and analysing the data from different laboratories and concluding on malaria resistance

Peptide receptor imaging of prostate cancer with radiolabelled bombesin analogues

Prostate Cancer (PC) is a type of cancer that is often diagnosed at very early stages due to improved detection among man in the Western world. Current imaging techniques are not optimal to determine extent of minimal early stage PC even though this is of great clinical importance. Human PC and high-grade PIN have shown high Gastrin-Releasing Peptide Receptor (GRPR) expression, while normal prostate tissue and BPH revealed to be predominantly GRPR-negative. Radiolabelled Gastrin-Releasing Peptide (GRP) or bombesin (BN) analogues targeting the GRPR can be used as non-invasive tools to diagnose, monitor and potentially treat PC. These BN analogues have already proven to be able to image PC in both tumour-bearing mice and clinical patients showing no important side effects. It's desirable that new peptides require fast-track standardised comparative testing in relevant PC models to select the best performing BN analogues for further evaluation in patients. Although knowledge about GRPR expression and development of new BN analogues can be extended, it is time to study performance of BN analogues for peptide receptor based imaging in patients validating results of PC imaging using histopathology as a golden standard

In vitro susceptibility to quinine and microsatellite variations of the Plasmodium falciparum Na+/H+ exchanger (Pfnhe-1) gene: the absence of association in clinical isolates from the Republic of Congo

<p>Abstract</p> <p>Background</p> <p>Quinine is still recommended as an effective therapy for severe cases of <it>Plasmodium falciparum </it>malaria, but the parasite has developed resistance to the drug in some cases. Investigations into the genetic basis for quinine resistance (QNR) suggest that QNR is complex and involves several genes, with either an additive or a pairwise effect. The results obtained when assessing one of these genes, the plasmodial Na⁺/H⁺exchanger, <it>Pfnhe-1</it>, were found to depend upon the geographic origin of the parasite strain. Most of the associations identified have been made in Asian strains; in contrast, in African strains, the influence of <it>Pfnhe </it>on QNR is not apparent. However, a recent study carried out in Kenya did show a significant association between a <it>Pfnhe </it>polymorphism and QNR. As genetic differences may exist across the African continent, more field data are needed to determine if this association exists in other African regions. In the present study, association between <it>Pfnhe </it>and QNR is investigated in a series of isolates from central Africa.</p> <p>Methods</p> <p>The sequence analysis of the polymorphisms at the <it>Pfnhe-1 </it>ms4760 microsatellite and the evaluation of <it>in vitro </it>quinine susceptibility (by isotopic assay) were conducted in 74 <it>P. falciparum </it>isolates from the Republic of Congo.</p> <p>Results</p> <p>Polymorphisms in the number of DNNND or NHNDNHNNDDD repeats in the <it>Pfnhe-1 </it>ms4760 microsatellite were not associated with quinine susceptibility.</p> <p>Conclusions</p> <p>The polymorphism in the microsatellite ms4760 in <it>Pfnhe-1 </it>that cannot be used to monitor quinine response in the regions of the Republic of Congo, where the isolates came from. This finding suggests that there exists a genetic background associated with geographic area for the association that will prevent the use of <it>Pfnhe </it>as a molecular marker for QNR. The contribution of <it>Pfnhe </it>to the <it>in vitro </it>response to quinine remains to be assessed in other regions, including in countries with different levels of drug pressure.</p

Atorvastatin treatment is effective when used in combination with mefloquine in an experimental cerebral malaria murine model

<p>Abstract</p> <p>Background</p> <p>One of the major complications of <it>Plasmodium falciparum </it>infection is cerebral malaria (CM), which causes one million deaths worldwide each year, results in long-term neurological sequelae and the treatment for which is only partially effective. Statins are recognized to have an immunomodulatory action, attenuate sepsis and have a neuroprotective effect. Atorvastatin (AVA) has shown in vitro anti-malarial activity and has improved the activity of mefloquine (MQ) and quinine.</p> <p>Methods</p> <p>The efficiency of 40 mg/kg intraperitoneal AVA, alone or in association with MQ, was assessed in an experimental <it>Plasmodium berghei </it>ANKA rodent parasite model of CM and performed according to different therapeutic schemes. The effects on experimental CM were assessed through the evaluation of brain histopathological changes and neuronal apoptosis by TUNEL staining.</p> <p>Results</p> <p>AVA alone in the therapeutic scheme show no effect on survival, but the prophylactic scheme employing AVA associated with MQ, rather than MQ alone, led to a significant delay in mouse death and had an effect on the onset of CM symptoms and on the level of parasitaemia. Histopathological findings show a correlation between brain lesions and CM onset. A neuronal anti-apoptotic effect of AVA in the AVA + MQ combination was not shown.</p> <p>Conclusions</p> <p>The combination of AVA and MQ therapy led to a significant delay in mouse mortality. There were differences in the incidence, time to cerebral malaria and the level of parasitaemia when the drug combination was administered to mice. When used in combination with MQ, AVA had a relevant effect on the in vivo growth inhibition and clinical outcome of <it>P. berghei </it>ANKA-infected mice.</p

Perception of Social Cues of Danger in Autism Spectrum Disorders

Intuitive grasping of the meaning of subtle social cues is particularly affected in autism spectrum disorders (ASD). Despite their relevance in social communication, the effect of averted gaze in fearful faces in conveying a signal of environmental threat has not been investigated using real face stimuli in adults with ASD. Here, using functional MRI, we show that briefly presented fearful faces with averted gaze, previously shown to be a strong communicative signal of environmental danger, produce different patterns of brain activation than fearful faces with direct gaze in a group of 26 normally intelligent adults with ASD compared with 26 matched controls. While implicit cue of threat produces brain activation in attention, emotion processing and mental state attribution networks in controls, this effect is absent in individuals with ASD. Instead, individuals with ASD show activation in the subcortical face-processing system in response to direct eye contact. An effect of differences in looking behavior was excluded in a separate eye tracking experiment. Our data suggest that individuals with ASD are more sensitive to direct eye contact than to social signals of danger conveyed by averted fearful gaze