Direct microscopic examination of imprints in patients undergoing cardiac valve replacement

BACKGROUND: Bacteriological analysis of cardiac valves might be indicated in patients with suspected endocarditis. METHODS: We report here a prospective study on fifty-three consecutive patients whose native valves were sent to the bacteriological and pathological laboratories, to investigate the performance of direct microscopic examination of imprints and valve culture. RESULTS: On the basis of a histopathological gold standard to classify the inflammatory valve process, the sensitivity, the specificity, the positive and the negative predictive values of direct microscopic examination of imprints and valve culture were 21%, 100%, 100%, 60%, and 21%, 72%, 38%, 52% respectively. This weak threshold of the direct microscopic examination of imprints could be due to antimicrobial therapy prescribed before cardiac surgery and the fact that the patients came from a tertiary hospital receiving patients with a prolonged history of endocarditis. CONCLUSION: Clinical context and histopathology are indispensable when analyzing the imprints and valve culture

Immunomodulatory effects of Amblyomma variegatum saliva on bovine cells: Characterization of cellular responses and identification of molecular determinants

The tropical bont tick, Amblyomma variegatum, is a tick species of veterinary importance and is considered as one of major pest of ruminants in Africa and in the Caribbean. It causes direct skin lesions, transmits heartwater, and reactivates bovine dermatophilosis. Tick saliva is reported to affect overall host responses through immunomodulatory and anti-inflammatory molecules, among other bioactive molecules. The general objective of this study was to better understand the role of saliva in interaction between the Amblyomma tick and the host using cellular biology approaches and proteomics, and to discuss its impact on disease transmission and/or activation. We first focused on the immuno-modulating effects of semi-fed A. variegatum female saliva on bovine peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages in vitro. We analyzed its immuno-suppressive properties by measuring the effect of saliva on PBMC proliferation, and observed a significant decrease in ConA-stimulated PBMC lymphoproliferation. We then studied the effect of saliva on bovine macrophages using flow cytometry to analyze the expression of MHC-II and co-stimulation molecules (CD40, CD80, and CD86) and by measuring the production of nitric oxide (NO) and pro- or anti-inflammatory cytokines. We observed a significant decrease in the expression of MHC-II, CD40, and CD80 molecules, associated with decreased levels of IL-12-p40 and TNF-α and increased level of IL-10, which could explain the saliva-induced modulation of NO. To elucidate these immunomodulatory effects, crude saliva proteins were analyzed using proteomics with an Orbitrap Elite mass spectrometer. Among the 336 proteins identified in A. variegatum saliva, we evidenced bioactive molecules exhibiting anti-inflammatory, immuno-modulatory, and anti-oxidant properties (e.g., serpins, phospholipases A2, heme lipoprotein). We also characterized an intriguing ubiquitination complex that could be involved in saliva-induced immune modulation of the host. We propose a model for the interaction between A. variegatum saliva and host immune cells that could have an effect during tick feeding by favoring pathogen dissemination or activation by reducing the efficiency of host immune response to the corresponding tick-borne diseases. (Résumé d'auteur

The genomic basis of color pattern polymorphism in the Harlequin ladybird

© 2018 The Authors Many animal species comprise discrete phenotypic forms. A common example in natural populations of insects is the occurrence of different color patterns, which has motivated a rich body of ecological and genetic research [1–6]. The occurrence of dark, i.e., melanic, forms displaying discrete color patterns is found across multiple taxa, but the underlying genomic basis remains poorly characterized. In numerous ladybird species (Coccinellidae), the spatial arrangement of black and red patches on adult elytra varies wildly within species, forming strikingly different complex color patterns [7, 8]. In the harlequin ladybird, Harmonia axyridis, more than 200 distinct color forms have been described, which classic genetic studies suggest result from allelic variation at a single, unknown, locus [9, 10]. Here, we combined whole-genome sequencing, population-based genome-wide association studies, gene expression, and functional analyses to establish that the transcription factor Pannier controls melanic pattern polymorphism in H. axyridis. We show that pannier is necessary for the formation of melanic elements on the elytra. Allelic variation in pannier leads to protein expression in distinct domains on the elytra and thus determines the distinct color patterns in H. axyridis. Recombination between pannier alleles may be reduced by a highly divergent sequence of ∼170 kb in the cis-regulatory regions of pannier, with a 50 kb inversion between color forms. This most likely helps maintain the distinct alleles found in natural populations. Thus, we propose that highly variable discrete color forms can arise in natural populations through cis-regulatory allelic variation of a single gene. More than 200 distinct color forms have been described in natural populations of the harlequin ladybird, Harmonia axyridis. Gautier et al. show that this variation is controlled by the transcription factor Pannier. Pannier is necessary to produce black pigment, and its expression pattern prefigures the coloration pattern in each color form

Nonsense-Mediated mRNA Decay Impacts MSI-Driven Carcinogenesis and Anti-Tumor Immunity in Colorectal Cancers

Nonsense-mediated mRNA Decay (NMD) degrades mutant mRNAs containing premature termination codon (PTC-mRNAs). Here we evaluate the consequence of NMD activity in colorectal cancers (CRCs) showing microsatellite instability (MSI) whose progression is associated with the accumulation of PTC-mRNAs encoding immunogenic proteins due to frameshift mutations in coding repeat sequences. Inhibition of UPF1, one of the major NMD factors, was achieved by siRNA in the HCT116 MSI CRC cell line and the resulting changes in gene expression were studied using expression microarrays. The impact of NMD activity was also investigated in primary MSI CRCs by quantifying the expression of several mRNAs relative to their mutational status and to endogenous UPF1 and UPF2 expression. Host immunity developed against MSI cancer cells was appreciated by quantifying the number of CD3ε-positive tumor-infiltrating lymphocytes (TILs). UPF1 silencing led to the up-regulation of 1251 genes in HCT116, among which a proportion of them (i.e. 38%) significantly higher than expected by chance contained a coding microsatellite (P<2×10−16). In MSI primary CRCs, UPF1 was significantly over-expressed compared to normal adjacent mucosa (P<0.002). Our data provided evidence for differential decay of PTC-mRNAs compared to wild-type that was positively correlated to UPF1 endogenous expression level (P = 0.02). A negative effect of UPF1 and UPF2 expression on the host's anti-tumor response was observed (P<0.01). Overall, our results show that NMD deeply influences MSI-driven tumorigenesis at the molecular level and indicate a functional negative impact of this system on anti-tumor immunity whose intensity has been recurrently shown to be an independent factor of favorable outcome in CRCs