Mycobacterium tuberculosis recall antigens suppress HIV-1 replication in anergic donor cells via CD8+ T cell expansion and increased IL-10 levels

Mycobacterium tuberculosis (MTb) is the leading cause of death in the setting of AIDS. MTb enhances the pathogenicity and accelerates the course of HIV disease and, furthermore, infection with HIV-1 increases the risk of reactivation or reinfection with MTb. In this study, we show that host-specific recall responses to one pathogen, MTb, has a direct effect upon the regulation of a second pathogen, HIV-1. Using cells from immunocompetent former tuberculosis (TB) patients who displayed either a persistently positive (responsive) or negative (anergic), delayed-type hypersensitivity (DTH) reaction to intradermal injection of purified protein derivative (PPD), we investigated the effect of recall Ags to MTb upon the replication of HIV-1 primary isolates in vitro. We show that HIV-1 replication of a T cell-tropic isolate was significantly impaired in MTb-stimulated PBMC from PPD-anergic donors. Furthermore, these donors displayed a significant increase in CD8(+) T cells and IL-10 levels and lower levels of IL-2 and TNF-alpha relative to PPD-responsive donors in response to PPD stimulation. Strikingly, CD8(+) T cell depletion and blocking of IL-10 significantly increased HIV-1 replication in these PPD-anergic donors, indicating that an immunosuppressive response to MTb recall Ags inhibits HIV-1 replication in PPD-anergic individuals. Therefore, immunotherapeutic approaches aimed at recapitulating Ag-specific MTb anergy in vivo could result in novel and effective approaches to inhibit HIV-1 disease progression in MTb/HIV-1 coinfection.     

Molecular,quantitative and abiotic variables for the delineation of evolutionary significant units: case of sandalwood (<Emphasis Type="Italic">Santalum austrocaledonicum</Emphasis> Vieillard) in New Caledonia

Various approaches have been developed to define conservation units for plant and animal species. In this study we combined nuclear microsatellites (from a previous published study) and chloroplast microsatellites (assessed in the present study), leaf and seed morphology traits and abiotic variables (climate and soil) to define evolutionary significant units (ESU) of Santalum austrocaledonicum, a tree species growing in New Caledonia. Results for chloroplast microsatellites showed that the total population heterozygosity was␣high, (H _cp = 0.84) but varied between islands. Differentiation was strong in the total population (F _stcp = 0.66) but also within the main island Grande Terre (F _stcp = 0.73) and within Iles Loyauté (F _stcp = 0.52), highlighting a limited gene flow between populations. These results confirmed those obtained with nuclear microsatellites. The cluster analysis on molecular markers discriminated two main groups constituted by the populations of Grande Terre and the populations of Iles Loyauté. A principal component analysis of leaf and seed morphology traits singled out the populations of Iles Loyauté and the western populations of Grande Terre. Quantitative genetic analyses showed that the variation between populations was under genetic control (broad sense heritability close to 80%). A high correlation between rainfall and morphological traits suggested an impact of climate on this variation. The integration of these results allows to define two ESUs, one corresponding to Grande Terre and Ile des Pins and the other the Iles Loyauté archipelago. This study stresses the need to restore some populations of Grande Terre that are currently threatened by their small size.     

Gender affects liver desaturase expression in a rat model of n−3 fatty acid repletion

Dietary n?3 polyunsaturated fatty acids (PUFA) are major components of cell membranes and have beneficial effects on human health. Docosahexaenoic acid (DHA; 22:6n?3) is the most biologically important n?3 PUFA and can be synthesized from its dietary essential precursor, α-linolenic acid (ALA; 18:3n?3). Gender differences in the efficiency of DHA bioconversion have been reported, but underlying molecular mechanisms are unknown. We compared the capacity for DHA synthesis from ALA and the expression of related enzymes in the liver and cerebral cortex between male and female rats. Wistar rats, born with a low-DHA status, were supplied with a suboptimal amount of ALA from weaning to 8 weeks of age. Fatty acid composition was determined by gas chromatography, the mRNA expression of different genes involved in PUFA metabolism was determined by RT-PCR (low-density array) and the expression of proteins was determined by Western blot analysis. At 8 weeks, DHA content was higher (+20 to +40%) in each phospholipid class of female livers compared to male livers. The “Δ4,” Δ5 and Δ6 desaturation indexes were 1.2–3 times higher in females than in males. The mRNA expression of Δ5- and Δ6-desaturase genes was 3.8 and 2.5 times greater, respectively, and the Δ5-desaturase protein was higher in female livers (+50%). No gender difference was observed in the cerebral cortex. We conclude that female rats replete their DHA status more readily than males, probably due to a higher expression of liver desaturases. Our results support the hypothesis on hormonal regulation of PUFA metabolism, which should be taken into account for specific nutritional recommendations.     

Coprolites as a source of information on the genome and diet of the cave hyena

We performed high-throughput sequencing of DNA from fossilized faeces to evaluate this material as a source of information on the genome and diet of Pleistocene carnivores. We analysed coprolites derived from the extinct cave hyena (Crocuta crocuta spelaea), and sequenced 90 million DNA fragments from two specimens. The DNA reads enabled a reconstruction of the cave hyena mitochondrial genome with up to a 158-fold coverage. This genome, and those sequenced from extant spotted (Crocuta crocuta) and striped (Hyaena hyaena) hyena specimens, allows for the establishment of a robust phylogeny that supports a close relationship between the cave and the spotted hyena. We also demonstrate that high-throughput sequencing yields data for cave hyena multi-copy and single-copy nuclear genes, and that about 50 per cent of the coprolite DNA can be ascribed to this species. Analysing the data for additional species to indicate the cave hyena diet, we retrieved abundant sequences for the red deer (Cervus elaphus), and characterized its mitochondrial genome with up to a 3.8-fold coverage. In conclusion, we have demonstrated the presence of abundant ancient DNA in the coprolites surveyed. Shotgun sequencing of this material yielded a wealth of DNA sequences for a Pleistocene carnivore and allowed unbiased identification of diet.     

NK cell tolerance to TLR agonists mediated by regulatory T cells after polymicrobial sepsis

As sensors of infection, innate immune cells are able to recognize pathogen-associated molecular patterns by receptors such as TLRs. NK cells present in many tissues contribute to inflammatory processes, particularly through the production of IFN-γ. They may display a protective role during infection but also a detrimental role during sterile or infectious systemic inflammatory response syndrome. Nevertheless, the exact status of NK cells during bacterial sepsis and their capacity directly to respond to TLR agonists remain unclear. The expression of TLRs in NK cells has been widely studied by analyzing the mRNA of these receptors. The aim of this study was to gain insight into TLR2/TLR4/TLR9 expression on/in murine NK cells at the protein level and determine if their agonists were able to induce cytokine production. We show, by flow cytometry, a strong intracellular expression of TLR2 and a low of TLR4 in freshly isolated murine spleen NK cells, similar to that of TLR9. In vitro, purified NK cells respond to TLR2, TLR4, and TLR9 agonists, in synergy with activating cytokines (IL-2, IL-15, and/or IL-18), and produce proinflammatory cytokines (IFN-γ and GM-CSF). Finally, we explored the possible tolerance of NK cells to TLR agonists after a polymicrobial sepsis (experimental peritonitis). For the first time, to our knowledge, NK cells are shown to become tolerant in terms of proinflammatory cytokines production after sepsis. We show that this tolerance is associated with a reduction of the CD27(+)CD11b(-) subset in the spleen related to the presence of regulatory T cells and mainly mediated by TGF-β.     

Lack of Liver X Receptors Leads to Cell Proliferation in a Model of Mouse Dorsal Prostate Epithelial Cell

Recent studies underline the implication of Liver X Receptors (LXRs) in several prostate diseases such as benign prostatic hyperplasia (BPH) and prostate cancer. In order to understand the molecular mechanisms involved, we derived epithelial cells from dorsal prostate (MPECs) of wild type (WT) or Lxrαβ−/− mice. In the WT MPECs, our results show that LXR activation reduces proliferation and correlates with the modification of the AKT-survival pathway. Moreover, LXRs regulate lipid homeostasis with the regulation of Abca1, Abcg1 and Idol, and, in a lesser extent, Srebp1, Fas and Acc. Conversely cells derived from Lxrαβ−/− mice show a higher basal phosphorylation and consequently activation of the survival/proliferation transduction pathways AKT and MAPK. Altogether, our data point out that the cell model we developed allows deciphering the molecular mechanisms inducing the cell cycle arrest. Besides, we show that activated LXRs regulate AKT and MAPK transduction pathways and demonstrate that LXRs could be good pharmacological targets in prostate disease such as cancer.     

Antibody responses to NY-ESO-1 in primary breast cancer identify a subtype target for immunotherapy

The highly immunogenic human tumor antigen NY-ESO-1 (ESO) is a target of choice for anti-cancer immune therapy. In this study, we assessed spontaneous antibody (Ab) responses to ESO in a large cohort of patients with primary breast cancer (BC) and addressed the correlation between the presence of anti-ESO Ab, the expression of ESO in the tumors and their characteristics. We found detectable Ab responses to ESO in 1% of the patients. Tumors from patients with circulating Ab to ESO exhibited common characteristics, being mainly hormone receptor (HR)⁻ invasive ductal carcinomas of high grade, including both HER2⁻ and HER2⁺ tumors. In line with these results, we detected ESO expression in 20% of primary HR⁻ BC, including both ESO Ab⁺ and Ab⁻ patients, but not in HR⁺ BC. Interestingly, whereas expression levels in ESO⁺ BC were not significantly different between ESO Ab⁺ and Ab⁻ patients, the former had, in average, significantly higher numbers of tumor-infiltrated lymph nodes, indicating that lymph node invasion may be required for the development of spontaneous anti-tumor immune responses. Thus, the presence of ESO Ab identifies a tumor subtype of HR⁻ (HER2⁻ or HER2⁺) primary BC with frequent ESO expression and, together with the assessment of antigen expression in the tumor, may be instrumental for the selection of patients for whom ESO-based immunotherapy may complement standard therapy.     

Influence of zeaxanthin and echinenone binding on the activity of the Orange Carotenoid Protein

In most cyanobacteria high irradiance induces a photoprotective mechanism that downregulates photosynthesis by increasing thermal dissipation of the energy absorbed by the phycobilisome, the water-soluble antenna. The light activation of a soluble carotenoid protein, the Orange-Carotenoid-Protein (OCP), binding hydroxyechinenone, a keto carotenoid, is the key inducer of this mechanism. Light causes structural changes within the carotenoid and the protein, leading to the conversion of a dark orange form into a red active form. Here, we tested whether echinenone or zeaxanthin can replace hydroxyechinenone in a study in which the nature of the carotenoid bound to the OCP was genetically changed. In a mutant lacking hydroxyechinenone and echinenone, the OCP was found to bind zeaxanthin but the stability of the binding appeared to be lower and light was unable to photoconvert the dark form into a red active form. Moreover, in the strains containing zeaxanthin-OCP, blue-green light did not induce the photoprotective mechanism. In contrast, in mutants in which echinenone is bound to the OCP, the protein is photoactivated and photoprotection is induced. Our results strongly suggest that the presence of the carotenoid carbonyl group that distinguishes echinenone and hydroxyechinenone from zeaxanthin is essential for the OCP activity.