PLoS ONE

Lyme disease is a multisystemic disorder caused by B. burgdorferi sl. The molecular basis for specific organ involvement is poorly understood. The skin plays a central role in the development of Lyme disease as the entry site of B. burgdorferi in which specific clones are selected before dissemination. We compared the skin inflammatory response (antimicrobial peptides, cytokines and chemokines) elicited by spirochete populations recovered from patients presenting different clinical manifestations. Remarkably, these spirochete populations induced different inflammatory profiles in the skin of C3H/HeN mice. As spirochete population transmitted into the host skin is heterogeneous, we isolated one bacterial clone from a population recovered from a patient with neuroborreliosis and compared its virulence to the parental population. This clone elicited a strong cutaneous inflammatory response characterized by MCP-1, IL-6 and antimicrobial peptides induction. Mass spectrometry of this clone revealed 110 overexpressed proteins when compared with the parental population. We further focused on the expression of nine bacterial surface proteins. bb0347 coding for a protein that interacts with host fibronectin, allowing bacterial adhesion to vascular endothelium and extracellular matrix, was found to be induced in host skin with another gene bb0213 coding for a hypothetical protein. These findings demonstrate the heterogeneity of the B. burgdorferi ss population and the complexity of the interaction involved early in the skin

Evolution of reproductive development in the volvocine algae

The evolution of multicellularity, the separation of germline cells from sterile somatic cells, and the generation of a male–female dichotomy are certainly among the greatest innovations of eukaryotes. Remarkably, phylogenetic analysis suggests that the shift from simple to complex, differentiated multicellularity was not a unique progression in the evolution of life, but in fact a quite frequent event. The spheroidal green alga Volvox and its close relatives, the volvocine algae, span the full range of organizational complexity, from unicellular and colonial genera to multicellular genera with a full germ–soma division of labor and male–female dichotomy; thus, these algae are ideal model organisms for addressing fundamental issues related to the transition to multicellularity and for discovering universal rules that characterize this transition. Of all living species, Volvox carteri represents the simplest version of an immortal germline producing specialized somatic cells. This cellular specialization involved the emergence of mortality and the production of the first dead ancestors in the evolution of this lineage. Volvocine algae therefore exemplify the evolution of cellular cooperation from cellular autonomy. They also serve as a prime example of the evolution of complex traits by a few successive, small steps. Thus, we learn from volvocine algae that the evolutionary transition to complex, multicellular life is probably much easier to achieve than is commonly believed

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Development of proteomic approaches for the study of Lyme borreliosis

La borréliose de Lyme est une maladie à transmission vectorielle en forte progression ces dernières années. Après une infection par la bactérie appartenant au complexe Borrelia burgdorferi sensu lato via une piqûre de tique, de multiples troubles (cardiaques, rhumatologiques…) peuvent apparaître. Il n’existe à l’heure actuelle aucun vaccin contre la maladie chez l’homme. De plus, les méthodes actuelles de diagnostic souffrent d’un manque de sensibilité, de spécificité ou de rapidité. Nous avons développé différentes approches protéomiques pour l’étude de cette maladie. Dans un premier temps, nous avons mis en évidence de nouveaux candidats vaccinaux par une approche Ge-LC-MS/MS de type label free. Dans un second temps, nous avons mis au point une méthode de détection de la bactérie dans des biopsies cutanées par spectrométrie de masse ciblée SRM. Nous avons également caractérisé les modifications post-traductionnelles d’une protéine identifiée dans les glandes salivaires de tique, et capable de lyser les fibroblastes. Un dernier volet a concerné l’évaluation de deux instruments et de l’apport de modes d’acquisition originaux pour l’analyse protéomiqueLyme borreliosis has been rising strongly for the last twenty years. After an infection by the bacterium belonging to the Borrelia burgdorferi sensu lato complex through a tick bite, multiple disorders (cardiac, rhumatological…) may appear. There is no current vaccine available for human being. Moreover, actual diagnosis methods lack of sensitivity, specificity and quickness. We developed various proteomic approaches to study the Lyme disease. Firstly, we discovered new vaccine candidates by using a Ge-LC-MS/MS label free approach. Secondly, we set up the detection of the bacteria in human cutaneous biopsies by targeted SRM mass spectrometry. We also characterized the post-translational modifications of a lytic protein present in tick salivary glands. Finally, we evaluated the performances of two instruments and the contribution of original acquisition modes for proteomic analyses

Development of proteomic approaches for the study of Lyme borreliosis

La borréliose de Lyme est une maladie à transmission vectorielle en forte progression ces dernières années. Après une infection par la bactérie appartenant au complexe Borrelia burgdorferi sensu lato via une piqûre de tique, de multiples troubles (cardiaques, rhumatologiques…) peuvent apparaître. Il n’existe à l’heure actuelle aucun vaccin contre la maladie chez l’homme. De plus, les méthodes actuelles de diagnostic souffrent d’un manque de sensibilité, de spécificité ou de rapidité. Nous avons développé différentes approches protéomiques pour l’étude de cette maladie. Dans un premier temps, nous avons mis en évidence de nouveaux candidats vaccinaux par une approche Ge-LC-MS/MS de type label free. Dans un second temps, nous avons mis au point une méthode de détection de la bactérie dans des biopsies cutanées par spectrométrie de masse ciblée SRM. Nous avons également caractérisé les modifications post-traductionnelles d’une protéine identifiée dans les glandes salivaires de tique, et capable de lyser les fibroblastes. Un dernier volet a concerné l’évaluation de deux instruments et de l’apport de modes d’acquisition originaux pour l’analyse protéomiqueLyme borreliosis has been rising strongly for the last twenty years. After an infection by the bacterium belonging to the Borrelia burgdorferi sensu lato complex through a tick bite, multiple disorders (cardiac, rhumatological…) may appear. There is no current vaccine available for human being. Moreover, actual diagnosis methods lack of sensitivity, specificity and quickness. We developed various proteomic approaches to study the Lyme disease. Firstly, we discovered new vaccine candidates by using a Ge-LC-MS/MS label free approach. Secondly, we set up the detection of the bacteria in human cutaneous biopsies by targeted SRM mass spectrometry. We also characterized the post-translational modifications of a lytic protein present in tick salivary glands. Finally, we evaluated the performances of two instruments and the contribution of original acquisition modes for proteomic analyses

Urban fabric and measures of variability: neighborhood effects on proximity pollution

International audienceThis paper reflects the work achieved for demonstrating potential influences of geometric features on atmospheric polluant distribution over metropolitan's area. (...

Discovery and targeted proteomics on cutaneous biopsies: a promising work toward an early diagnosis of Lyme disease.

Lyme disease is the most important vector-borne disease in the Northern hemisphere and represents a major public health challenge with insufficient means of reliable diagnosis. Skin is rarely investigated in proteomics but constitutes in the case of Lyme disease the key interface where the pathogens can enter, persist, and multiply. Therefore, we investigated proteomics on skin samples to detect Borrelia proteins directly in cutaneous biopsies in a robust and specific way. We first set up a discovery gel prefractionation-LC-MS/MS approach on a murine model infected by Borrelia burgdorferi sensu stricto that allowed the identification of 25 Borrelia proteins among more than 1300 mouse proteins. Then we developed a targeted gel prefractionation-LC-selected reaction monitoring (SRM) assay to detect 9/33 Borrelia proteins/peptides in mouse skin tissue samples using heavy labeled synthetic peptides. We successfully transferred this assay from the mouse model to human skin biopsies (naturally infected by Borrelia), and we were able to detect two Borrelia proteins: OspC and flagellin. Considering the extreme variability of OspC, we developed an extended SRM assay to target a large set of variants. This assay afforded the detection of nine peptides belonging to either OspC or flagellin in human skin biopsies. We further shortened the sample preparation and showed that Borrelia is detectable in mouse and human skin biopsies by directly using a liquid digestion followed by LC-SRM analysis without any prefractionation. This study thus shows that a targeted SRM approach is a promising tool for the early direct diagnosis of Lyme disease with high sensitivity (<10 fmol of OspC/mg of human skin biopsy)

Proteomic analysis of three Borrelia burgdorferi sensu lato native species and disseminating clones

Lyme borreliosis is the most important vector-borne disease in the Northern hemisphere. It is caused by Borrelia burgdorferi sensu lato bacteria transmitted to humans by the bite of hard ticks, Ixodes spp. Although antibiotic treatments are efficient in the early stage of the infection, a significant number of patients develop disseminated manifestations (articular, neurological and cutaneous) due to unnoticed or absence of erythema migrans, or to inappropriate treatment. Vaccine could be an efficient approach to decrease Lyme disease incidence. We have developed a proteomic approach based on a Ge-LC-MS/MS strategy to identify new vaccine candidates. We analyzed a disseminating clone and the associated wild type strain for each major pathogenic Borrelia species: B. burgdorferi sensu stricto, B. garinii and B. afzelii. We identified specific proteins and common proteins to the disseminating clones of the three main species. In parallel, we used a spectral counting strategy to identify up-regulated proteins common to the clones. Finally, 40 proteins were found that could potentially be involved in bacterial virulence and of interest in the development of a new vaccine. We selected the three proteins specifically detected in the disseminating clones of the three Borrelia species and checked by RT-PCR whether they are expressed in mouse skin upon B. burgdorferi ss inoculation. Interestingly, BB0566 appears as a potential vaccine candidate. This article is protected by copyright. All rights reserved

Dissociating effect of salivary gland extract from Ixodes ricinus on human fibroblasts: Potential impact on Borrelia transmission

International audienceUnderstanding the mechanism of pathogen transmission is essential for the development of strategies to reduce arthropod-borne diseases. The pharmaco- and immunomodulatory properties of insect and acarine saliva play an essential role in the efficiency of pathogen transmission. The skin as the site where arthropod saliva and pathogens are inoculated - represents the key interface in vector-borne diseases. We identified tick molecules potentially involved in pathogen transmission, using micro-HPLC and mass spectrometry, followed by in vitro assays on human skin cells. Histone H4 isolated from Ixodes ricinus salivary gland extract was identified as a molecule with a dissociating effect on human primary fibroblasts. This histone might be involved in the formation of the feeding pool formed around the tick mouthparts and responsible of tissue necrosis in the vertebrate host. Thanks to its selective antimicrobial activity, it may also sterilize the feeding pool and facilitate transmission of pathogens such as Borrelia burgdorferi sensu lato