A multiplex assay for the simultaneous detection of antibodies against 15 Plasmodium falciparum and Anopheles gambiae saliva antigens

<p>Abstract</p> <p>Background</p> <p>Assessment exposure and immunity to malaria is an important step in the fight against the disease. Increased malaria infection in non-immune travellers under anti-malarial chemoprophylaxis, as well as the implementation of malaria elimination programmes in endemic countries, raises new issues that pertain to these processes. Notably, monitoring malaria immunity has become more difficult in individuals showing low antibody (Ab) responses or taking medications against the <it>Plasmodium </it><it>falciparum </it>blood stages. Commonly available techniques in malaria seroepidemiology have limited sensitivity, both against pre-erythrocytic, as against blood stages of the parasite. Thus, the aim of this study was to develop a sensitive tool to assess the exposure to malaria or to bites from the vector <it>Anopheles gambiae</it>, despite anti-malarial prophylactic treatment.</p> <p>Methods</p> <p>Ab responses to 13 pre-erythrocytic <it>P. falciparum</it>-specific peptides derived from the proteins Lsa1, Lsa3, Glurp, Salsa, Trap, Starp, CSP and Pf11.1, and to 2 peptides specific for the <it>Anopheles gambiae </it>saliva protein gSG6 were tested. In this study, 253 individuals from three Senegalese areas with different transmission intensities and 124 European travellers exposed to malaria during a short period of time were included.</p> <p>Results</p> <p>The multiplex assay was optimized for most but not all of the antigens. It was rapid, reproducible and required a small volume of serum. Proportions of Ab-positive individuals, Ab levels and the mean number of antigens (Ags) recognized by each individual increased significantly with increases in the level of malaria exposure.</p> <p>Conclusion</p> <p>The multiplex assay developed here provides a useful tool to evaluate immune responses to multiple Ags in large populations, even when only small amounts of serum are available, or Ab titres are low, as in case of travellers. Finally, the relationship of Ab responses with malaria endemicity levels provides a way to monitor exposure in differentially exposed autochthonous individuals from various endemicity areas, as well as in travellers who are not immune, thus indirectly assessing the parasite transmission and malaria risk in the new eradication era.</p

Natural Killer Cells Exhibit a Peculiar Phenotypic Profile in Systemic Sclerosis and Are Potent Inducers of Endothelial Microparticles Release

The pathophysiology of systemic sclerosis (SSc) involves early endothelial and immune activation, both preceding the onset of fibrosis. We previously identified soluble fractalkine and circulating endothelial microparticles (EMPs) as biomarkers of endothelial inflammatory activation in SSc. Fractalkine plays a dual role as a membrane-bound adhesion molecule expressed in inflamed endothelial cells (ECs) and as a chemokine involved in the recruitment, transmigration, and cytotoxic activation of immune cells that express CX3CR1, the receptor of fractalkine, namely CD8 and γδ T cells and natural killer (NK) cells. We aimed to quantify circulating cytotoxic immune cells and their expression of CX3CR1. We further investigated the expression profile of NK cells chemokine receptors and activation markers and the potential of NK cells to induce EC activation in SSc. We performed a monocentric study (NCT 02636127) enrolling 15 SSc patients [15 females, median age of 55 years (39–63), 11 limited cutaneous form and 4 diffuse] and 15 healthy controls. Serum fractalkine levels were significantly increased in SSc patients. Circulating CD8 T cells numbers were decreased in SSc patients with no difference in their CX3CR1 expression. Circulating γδ T cells and NK cells numbers were preserved. CX3CR1 expression in CD8 and γδ T cells did not differ between SSc patients and controls. The percentage and level of CX3CR1 expression in NK cells were significantly lowered in SSc patients. Percentages of CXCR4, NKG2D, CD69-expressing NK cells, and their expression levels were decreased in NK cells. Conversely, CD16 level expression and percentages of CD16+ NK cells were preserved. The exposure of human microvascular dermic EC line (HMVEC-d) to peripheral blood mononuclear cells resulted in similar NK cells degranulation activity in SSc patients and controls. We further showed that NK cells purified from the blood of SSc patients induced enhanced release of EMPs than NK cells from controls. This study evidenced a peculiar NK cells phenotype in SSc characterized by decreased chemokine and activation receptors expression, that might reflect NK cells involvement in the pathogenic process. It also highlighted the role of NK cells as a potent mechanism inducing endothelial activation through enhanced EMPs release

Mechanism of amyloid fibril formation by human lysozyme and VHHs

Etude du mécanisme moléculaire de la formation de fibres amyloïdes à l'aide de fragments d'anticorps à chaînes lourdes comme protéines modèle

VHHs as model proteins to investigate amyloid fibril formation: aggregation kinetics and fibril stability

Etude du mécanisme moléculaire de la formation de fibres amyloïdes à l'aide de fragments d'anticorps à chaînes lourdes comme protéines modèle

VHHs as model proteins to investigate amyloid fibril formation: effect of seeding and cross-seeding on aggregation kinetics and stability of fibrils

The term "amyloidosis" covers a group of diseases associated with the deposition of protein aggregates organized into amyloid fibrils in different organs. About forty amyloidosis are known so far, amongst which Alzheimer's disease, type II diabetes and immunoglobulin amyloidosis [1]. Although the mechanism of amyloid fibrils formation at the molecular level is not yet completely understood, it has been shown that the capacity to form amyloid fibrils in vitro is an intrinsic property of all polypeptide chains [1]. The choice of model proteins to investigate the aggregation process in vitro is therefore no more restrained to proteins involved in amyloidosis but can be settled on a wide variety of proteins. In this study, we have chosen to investigate the mechanism of amyloid fibrils formation by two variable domains of camelid heavy-chain antibodies (referred to as VHHs or nanobodies), cAb-HuL6 and cAb-BcII10, and this choice was motivated by the following reasons: - First, VHHs are small monomeric proteins (~14 kDa) presenting a high stability and a high solubility [2], which permits their expression with a high yield (5-20 mg.L-1). - Second, a wide range of stable mutants of these two VHHs is available. Mutations located at the disulfide bond [3,4] and the CDRs [3] have been introduced. Characterisation of the aggregating properties of these mutants will allow the investigation of the impact of these structural elements on the process of fibril formation. In order to determine conditions in which cAb-HuL6 and cAb-BcII10 are more susceptible to form intermediates and thus amyloid fibrils, heat-induced unfolding experiments at pHs comprised in a range from 2,5 to 9,5 have been monitored by intrinsic fluorescence, ANS binding and far-UV circular dichroism. Then, aggregation experiments have been performed in the selected conditions and the presence of amyloid fibrils has been observed by thioflavin T fluorescence experiments and electron microscopy. The kinetics of aggregation obtained in the absence and the presence of seeding/cross-seeding allowed to identify the regions of the protein which could be involved in the formation of fibrils. [1] Chiti and Dobson, Annu. Rev. Biochem., 75, 2006, 333-366. [2] Dumoulin et al., Protein Sci., 11, 2002, 500-515. [3] Saerens et al., J. Mol. Biol., 352, 2005, 597-607. [4] Saerens et al., J. Mol. Biol., 377, 2008, 478-488.Etude du mécanisme moléculaire de la formation de fibres amyloïdes à l'aide de fragments d'anticorps à chaînes lourdes comme protéines modèle

Challenges of complying with both food value chain specifications and agroecology principles in vegetable crop protection

To meet the challenges of sustainability in agricultural system design, reducing the dependency on synthetic plant protection products has become a core issue. There are currently two major reasons for farmers' decision to reduce their use of synthetic products: public policies, and the extralegal requirements of food supply chains. To reduce or eliminate synthetic plant protection products, agroecological crop protection (ACP) relying on the development of agroecology science and practices is a promising holistic approach focused on crop health overall. ACP requires a consistent combination of various agronomic practices at different spatiotemporal and trophic levels. Vegetable crops are minor crops facing the major challenges of producing high-quality produce and of controlling sanitary pressure on yields. Thus, agroecological vegetable systems must not only be adapted to official regulations and environmental parameters but must also comply with the specifications of the targeted food value chains (FVC), which are variable: marketing standards regarding cosmetic issues are very strict in long value chains, whereas they are more flexible in local short chains. Whereas fresh vegetable production is strongly challenged by the reduction of synthetic plant protection products, there are few studies that show how to design, manage and assess agroecological crop protection strategies for such systems, considering the main specifications and criteria of the FVC as a whole. This article reports on the challenges of complying with both FVC specifications and agroecology principles in protected vegetable crop protection. This study relies on four cropping systems implemented in an experimental station for 4.5 years, each of which had a specific strategy of crop protection management and was devoted to a particular FVC. The four FVCs are "local direct sale in lowpesticide farming", "local direct sale in organic farming", "super- and hypermarket value chain in low-pesticide farming" and "super- and hypermarkets value chain in organic farming". Results consist in the description of combination of agronomic practices used, as well as the corresponding decision-making processes. They then present the performance of the four systems tested, showing that agroecological crop protection strategies are successful in reducing or eliminating synthetic plant protection products. We then discuss failure and success factors highlighted by this multi-year experiment. It illustrates that agroecological crop protection and compliance with the FVC's expectations can be compatible but involve specific trade-offs, depending on the targeted food value chain. We finally stress key areas to investigate further in order to achieve still challenging objectives in vegetable systems

Design, experimentation and assessment of four protected vegetable cropping systems adapted to different food systems

Design, experimentation and assessment of four protected vegetable cropping systems adapted to different food systems. 5. International Symposium for Farming Systems Design (AGRO2015

Participatory design of innovative intercropping systems in protected market gardening production

Participatory design of innovative intercropping systems in protected market gardening production. Innovation in Integrated & Organic Horticulture, INNOHORT 201

Design and assessment of protected market gardening cropping systems suited to contrasted food systems

Design and assessment of protected market gardening cropping systems suited to contrasted food systems. Innovation in Integrated & Organic Horticulture, INNOHORT 201

: Regards croisés en sciences humaines et sociales.

International audienceCet ouvrage interroge : qu’est-ce que savoir, apprendre et éduquer dans notre modernité ? Cette question, actuelle en raison de transformations sociales vives, fait l’objet d’un intérêt partagé. Dans ce contexte, le caractère ontologique de la notion d’agency semble offrir diverses modalités de réflexion, notamment en sciences humaines et sociales. Interaction, action, acte, acteur, agent, mouvement, transaction : autant de termes qui parcourent cet ouvrage, pour contribuer à définir cette notion et à penser l’éducation, en croisant les regards