First characterisation of the populations and immune-related activities of hemocytes from two edible gastropod species, the disk abalone, Haliotis discus discus and the spiny top shell, Turbo cornutus.

International audienceThe disk abalone Haliotis discus discus and the spiny top shell Turbo cornutus are edible gastropod species of high economic value, mainly in Asia. Mortality outbreaks and variations in worldwide stock abundance have been reported and suggested to be associated, at least in part, with pathogenic infections. Ecology, biology and immunology of both species are currently not well documented. The characterisation of the immune systems of these species is necessary to further assess the responses of H. discus discus and T. cornutus to environmental, chemical and disease stresses. In the present study, we investigated the morphology and immune-related activities of hemocytes in both species using light microscopy and flow cytometry. Two types of hemocytes were identified in the disk abalone hemolymph, blast-like cells and hyalinocytes; whereas four main hemocyte types were distinguished in the spiny top shell, blast-like cells, type I and II hyalinocytes, and granulocytes. Flow cytometric analysis also revealed differences between cell types in immune-related activities. Three subsets of hemocytes, defined by differing lysosomal characteristics, were observed in the hemolymph of the spiny top shell, and only one in the disk abalone. Phagocytic activity was higher in H. discus discus hemocytes than in T. cornutus hemocytes, and the kinetics of PMA-stimulated oxidative activity was different between hemocytes of the disk abalone and the spiny top shell. Finally our results suggest for the first time a predominant mitochondrial origin of oxidative activity in gastropod hemocytes

Impact du micro-environnement hépatique sur la réponse des cellules dendritiques à l'infection par Leishmania sp.

Au cours de la leishmaniose viscérale (LV), les parasites sont retrouvés au sein de différents organes dont la rate et le foie. Ces deux organes présentent un contrôle de la charge parasitaire différent. Les cellules dendritiques (DC) jouent un rôle primordial dans le développement et l'orientation de la réponse immune. Actuellement, la littérature ne fournit pas de données concernant l'impact du micro-environnement d'organe sur la réponse des DC à l'infection. Notre objectif était, à partir d'un modèle de différenciation de DC en micro-environnement hépatique, d'observer son impact sur la réponse anti-Leishmania donovani mise en place. Nous avons étudié les modifications phénotypiques et fonctionnelles des DC infectées ainsi que leurs capacités à initier et orienter une réponse immune. Nous nous sommes, de plus, intéressé à l'effet des antigènes excrétés-sécrétés des leishmanies sur les DC, ainsi qu'à des mécanismes immunomodulateurs intervenant lors de l'infection leishmanienne.During visceral leishmaniasis (VL), parasites spread into organs such as spleen and liver. Those two organs present differential control of parasite load. Dendritic cells (DC) play major role in initiation and orientation of immune response. Currently, no data is available about the impact of organ micro-environment on DC response to Leishmania infection. Using an in vitro model of DC differenciation in an hepatic micro-environment, our objective was to study its impact on the anti-Leishmania donovani response. We have focused on phenotypic and functional modifications of infected DCs and their ability to initiate and give orientation to immune response. Furthermore, we were interested in the effect of Leishmania excreted-secreted antigens on DCs, as well as immunomodulatory mechanisms induced during Leishmania infection.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Hemocytes of the carpet shell clam ( Ruditapes decussatus) and the Manila clam (Ruditapes philippinarum): Current knowledge and future prospects

International audienceHemocytes are the immune effectors in clams, directing cellular but also humoral defences. In the Manila clam (Ruditapes philippinarum) and the carpet shell clam (Ruditapes decussatus), two phenotypically similar venerid species, fishery and aquaculture importance motivated scientific studies to improve knowledge about the participation of hemocytes in immune response. Currently, gaps still persist concerning the classification of hemocyte sub-populations as well as their non-immune activities. This review summarizes current knowledge about hemocytes of the Manila clam and the carpet shell clam, suggests some probable misinterpretations arising from extrapolations from other bivalves and vertebrates, and suggests future research prospects. The susceptibility of hemocytes to environmental modifications as well as biological and chemical toxicants is also re-evaluated. Hemocytes of bivalves are not limited in function to immunity and should be considered in a wider scheme including the environment and whole-animal physiology

Membrane phospholipid composition of hemocytes in the Pacific oyster Crassostrea gigas and the Manila clam Ruditapes philippinarum

International audienceThe detailed sterol (free sterol proportions and compositions) and phospholipid (PL) compositions (relative proportions of PL classes and subclasses and their respective fatty acid (FA) compositions) of hemocyte membranes were investigated in two bivalve mollusks: the Pacific oyster Crassostrea gigas and the Manila clam Ruditapes philippinarum. Hemocyte membrane lipids of both species revealed similar general composition: i) their free sterol/PL ratio was above 0.4 and ii) their PL were predominated by the diacyl + alkyl forms of glycerophosphatidylcholine (PC), the plasmalogen form of glycerophosphatidylethanolamine (PE) and ceramide aminoethylphosphonate (CAEP). Free sterols were predominated by cholesterol in both species. Plasmalogen forms of PE and glycerophosphatidylserine (PS) represented 82-83% and 46-55% of total PE and PS, respectively. When compared to their respective diacyl + alkyl forms, plasmalogen forms of PE and PS were specifically enriched in non-methylene-interrupted (NMI) FA and 20:1n-11, suggesting a functional significance of these PL molecular species in bivalve hemocytes. Lysoglycerophosphatidylcholine (LysoPC) levels were found to be fairly high in hemocytes, accounting for about 8% of the PL Some species-specific features were also found. LysoPC and glycerophosphatidylinositol (PI) FA compositions differed between Ruditapes philippinarum and Crassostrea gigas. CAEP proportion was higher in R. philippinarum than in C. gigas (14.5% and 27.9% of the PL respectively). Hemolymph cell monolayer observations and flow-cytometric analyses revealed species-specific hemocyte morphology and sub-populations which could account for some of the observed species-specific membrane lipid compositions

Comparison of the immunomodulatory effects of L. donovani and L. major excreted-secreted antigens, particulate and soluble extracts and viable parasites on human dendritic cells.

International audienceIn an experimental model of human monocyte-derived dendritic cells (DCs), the immunophenotype of mature DCs infected with Leishmania donovani and Leishmania major showed a weak decrease in the cell surface expression of CD40, CD86, HLA-DR and DC-SIGN compared with uninfected control DCs. This immunomodulatory effect was more pronounced after stimulation with excreted-secreted antigens (ESA) of both species but absent after stimulation with particulate and soluble extracts. Infection with viable promastigotes, as well as stimulation with ESA from L. donovani and L. major, decreased IL-10 and IL-12p70 secretion. To our knowledge, this is the first direct demonstration that ESA from Leishmania promastigotes can stimulate DCs in the same manner as viable promastigotes

Application of Flow Cytometry to Assess Deepwater Horizon Oil Toxicity on the Eastern Oyster Crassostrea virginica Spermatozoa

International audienceThe Deepwater Horizon (DWH) oil spill in 2010 resulted in the release of millions of liters of oil into the Gulf of Mexico. Dispersants such as Corexit 9500A were used to disperse oil both at the well-head and at the surface. Polycyclic aromatic hydrocarbons and dispersants have been shown to deleteriously affect early life stages of organisms including oysters. This study examined the impacts of chemically enhanced water-accommodated fractions [CEWAF; 1.29–26.14 µg/l tPAH50 (a sum of 50 different polycyclic aromatic hydrocarbons)], high-energy water-accommodated fractions (HEWAF; 16.53–248.89 µg/l tPAH50), and dispersants (0.625–10 mg/l) on the cellular functions (viability, mitochondrial membrane potential (MMP), reactive oxygen species production (ROS), and acrosomal integrity) and resulting fertilization success of eastern oyster Crassostrea virginica spermatozoa. While viability of spermatozoa was not affected by CEWAF and HEWAF at concentrations tested, dispersant exposure caused significant decrease in viability at the highest concentration tested. Fertilization success as well as MMP and ROS production were significantly decreased upon exposure to CEWAF, HEWAF, and dispersants. Also, although not affected by HEWAF exposure, acrosomal integrity decreased upon exposure to CEWAF and dispersants at concentrations tested. The results of this study suggest that impaired fertilization and reduced viability observed after exposure to DWH oil spill contaminants may result, at least partially, from alterations of cellular functions of spermatozoa and contribute to negative effects on oyster populations, and thus the ecology and economy of the Gulf of Mexico