The immune space: a concept and template for rationalizing vaccine development.

Abstract Empirical testing of candidate vaccines has led to the successful development of a number of lifesaving vaccines. The advent of new tools to manipulate antigens and new methods and vectors for vaccine delivery has led to a veritable explosion of potential vaccine designs. As a result, selection of candidate vaccines suitable for large-scale efficacy testing has become more challenging. This is especially true for diseases such as dengue, HIV, and tuberculosis where there is no validated animal model or correlate of immune protection. Establishing guidelines for the selection of vaccine candidates for advanced testing has become a necessity. A number of factors could be considered in making these decisions, including, for example, safety in animal and human studies, immune profile, protection in animal studies, production processes with product quality and stability, availability of resources, and estimated cost of goods. The "immune space template" proposed here provides a standardized approach by which the quality, level, and durability of immune responses elicited in early human trials by a candidate vaccine can be described. The immune response profile will demonstrate if and how the candidate is unique relative to other candidates, especially those that have preceded it into efficacy testing and, thus, what new information concerning potential immune correlates could be learned from an efficacy trial. A thorough characterization of immune responses should also provide insight into a developer's rationale for the vaccine's proposed mechanism of action. HIV vaccine researchers plan to include this general approach in up-selecting candidates for the next large efficacy trial. This "immune space" approach may also be applicable to other vaccine development endeavors where correlates of vaccine-induced immune protection remain unknown.

Vaccination with a recombinant protein encoding the tumor-specific antigen NY-ESO-1 elicits an A2/157-165-specific CTL repertoire structurally distinct and of reduced tumor reactivity than that elicited by spontaneous immune responses to NY-ESO-1-expressing Tumors.

In a recent vaccination trial assessing the immunogenicity of an NY-ESO-1 (ESO) recombinant protein administered with Montanide and CpG, we have obtained evidence that this vaccine induces specific cytolytic T lymphocytes (CTL) in half of the patients. Most vaccine-induced CTLs were directed against epitopes located in the central part of the protein, between amino acids 81 and 110. This immunodominant region, however, is distinct from another ESO CTL region, 157-165, that is a frequent target of spontaneous CTL responses in A2+ patients bearing ESO tumors. In this study, we have investigated the CTL responses to ESO 157-165 in A2+ patients vaccinated with the recombinant protein. Our data indicate that after vaccination with the protein, CTL responses to ESO 157-165 are induced in some, but not all, A2+ patients. ESO 157-165-specific CTLs induced by vaccination with the ESO protein were functionally heterogeneous in terms of tumor recognition and often displayed decreased tumor reactivity as compared with ESO 157-165-specific CTLs isolated from patients with spontaneous immune responses to ESO. Remarkably, protein-induced CTLs used T-cell receptors similar to those previously isolated from patients vaccinated with synthetic ESO peptides (Vbeta4.1) and distinct from those used by highly tumor-reactive CTLs isolated from patients with spontaneous immune responses (Vbeta1.1, Vbeta8.1, and Vbeta13.1). Together, these results demonstrate that vaccination with the ESO protein elicits a repertoire of ESO 157-165-specific CTLs bearing T-cell receptors that are structurally distinct from those of CTLs found in spontaneous immune responses to the antigen and that are heterogeneous in terms of tumor reactivity, being often poorly tumor reactive.

Interactions between cells and functionalized nanoparticles

In this present thesis Superparamagnetic Iron Oxide Nanoparticles (SPIONs) with 9 nm in diameter were selected as nanocarriers in order to study their potential application as drug delivery systems. Therefore the aim of the study was to demonstrate the proof of concept by establishing an efficient system of drug delivery, which would be a valuable tool in biomedical applications, such as the treatement of cancer, by reducing the side effects due to administration of a high concentration of therapeutic agents. As demonstrated in a previous study, the uptake of SPIONs by tumoral human cells was enhanced by the presence of amino groups on their surface. The stabilization of SPIONs were then performed and optimized by the coating of poly(vinylalcohol) and poly(vinylalcohol/vinylamine). Such nanoparticles were known as aminoPVA-SPIONs. The toxicity and the inflammatory reaction of aminoPVA-SPIONs were evaluated in order to establish their potentiel use in the human body. The results demonstrated that the human cells were able to invaginate aminoPVA-SPIONS without revealing any toxicity and inflammatory reaction. The analysis by transmission electron microscopy (TEM), scanning electron microscopy (SEM), cryo-TEM, confocal microscopy and histological staining (i.e. Prussian Blue) showed that the iron oxide core of SPIONs were located in the cytoplasm of cells and concentrated in vesicles. The evaluation of the mechanism of uptake of aminoPVA-SPIONs revealed that their uptake by monolayer cell culture was performed via an active mechanism, which was achieved by a clathrin-mediated endocytosis. Consequently, it was suggested that aminoPVA-SPIONs were good candidates as nanocarriers in drug delivery systems, which were able to reach the cytoplasm of cells. Their incubation with three-dimensional models mimicing tissues, such as differentiated rat brain cell-derived aggregates and spheroids, revealed that aminoPVA-SPIONs were able to invade into deep cell layers according to the stage of growth of these models. In the view of these promising results, drug-SPIONs were prepared by the functionalization of aminoPVA-SPIONs via a biological labile chemical bond by one of these three antineoplastic agents, which are widely used in clinical practice: 5-fluorourdine (Fur) (an antimetabolite), or camptothecin (CPT) (a topoisomerase inhibitor) or doxorubicin (DOX) (an anthracycline which interfere with DNA). The results shown that drug-SPIONs were internalized by human melanoma cells, as it was expected due the previous results with aminoPVA-SPIONs, and in addition they were active as anticancer agents, suggesting the efficient release of the drug from the drug-SPIONs. The results with CPT-SPIONs were the most promising, whereas DOX- SPIONs did not demonstrate a prononced activity of DOX. In conclusion, the results demonstrated that functionalized iron oxide nanoparticles are a promising tool in order to deliver therapeutic agents. - Dans le cadre de ce travail de thèse, les nanoparticules superparamagnétiques d'oxyde de fer (SPIONs) ayant un diamètre de 9 nm ont été choisies, afin d'étudier leur éventuelle utilisation dans un système de délivrance d'agents thérapeutiques. Ainsi le but de la thèse est de démontrer la faisabilité de fabriquer un système efficace de délivrance d'agents thérapeutiques, qui serait un outil intéressant dans le cadre d'une utilisation biomédicale, par exemple lors du traitement du cancer, qui pourrait réduire les effets secondaires provoqués par le dosage trop élevé de médicaments. Comme il a été démontré dans une précédente étude, l'invagination des SPIONs par des cellules humaines cancéreuses est améliorée par la présence de groupes fonctionnels amino à leur surface. La stabilisation des SPIONs est ainsi effectuée et optimisée par l'enrobage de poly(vinylalcool) et de (poly(vinylalcool/vinylamine), qui sont connues sous le nom de aminoPVA-SPIONs. La toxicité et la réaction inflammatoire des aminoPVA-SPIONs ont été évaluées dans le but de déterminer leur potentielle utilisation dans le corps humain. Les résultats démontrèrent que les cellules humaines sont capables d'invaginer les aminoPVAS-SPIONs sans induire une réaction toxique ou inflammatoire. L'analyse par la microscopie électronique en transmission électronique (TEM), la microscopie électronique à balayage (SEM), le cryo-microscopie électronique (SEM), la microscopie confocale et la coloration histologique (par ex, le bleu de Prusse) a montré que l'oxyde de fer des SPIONs est localisé dans le cytoplasme des cellules et est concentré dans des vesicules. L'évaluation du méchanisme d'invagination des aminoPVA-SPIONs ont révélé que leur invagination par des monocultures de cellules est effectué par un méchanisme actif, contrôlé par une endocytose induite par les clathrins. Par conséquent, les aminoPVA-SPIONs sont de bons candidats en tant que transporteurs (nanocamers) dans un système de délivrance d'agents thérapeuthique, capable d'atteindre le cytoplasme des cellules. Leur incubation avec des modèles tridimenstionnels imitant les tissues, tels que les aggrégats de cellules de cerveau différenciées et les sphéroïdes, a montré que les aminoPVA-SPIONs sont capable de pénétrer dans les couches profondes des modèles, selon l'état d'avancement de leur croissance. En vue de ces résultats prometteurs, les drug-SPIONs ont été préparés en fonctionalisant les aminoPVA-SPIONs par le biai d'une liaison chimique labile par un des trois agents thérapeutiques, déjà utilisé en pratique : 5-fluorourdine (Fur) (un antimétabolite), or camptothecin (CPT) (un inhibiteur de la topoisomerase) or doxorubicin (DOX) (un anthracycline qui interfère avec le DNA). Les résultats ont montré que les drug-SPIONs sont capable d'être internalisés par les mélanomes, comme il a été attendu d'après les résultats obtenus précédemment avec les aminoPVA-SPIONs, et de plus, les drug-SPIONs sont actifs, ce qui suggère un relargage efficace de l'agent thérapeutique du drug-SPIONs. Les résultats obtenus avec les CPT-SPIONs sont les plus prometteurs, tandis que ceux avec les DOX-SPIONs, ce n'est pas le cas, dont l'activité thérapeutique de DOX n'a pas été aussi efficace. En conclusion, les résultats ont pu démontrer que les nanoparticules d'oxyde de fer fonctionnalisées sont un outil prometteur dans la délivrance d'agents thérapeutiques.

Immune activation alters cellular and humoral responses to yellow fever 17D vaccine.

Background. Defining the parameters that modulate vaccine responses in African populations will be imperative to design effective vaccines for protection against HIV, malaria, tuberculosis, and dengue virus infections. This study aimed to evaluate the contribution of the patient-specific immune microenvironment to the response to the licensed yellow fever vaccine 17D (YF-17D) in an African cohort. Methods. We compared responses to YF-17D in 50 volunteers in Entebbe, Uganda, and 50 volunteers in Lausanne, Switzerland. We measured the CD8+ T cell and B cell responses induced by YF-17D and correlated them with immune parameters analyzed by flow cytometry prior to vaccination. Results. We showed that YF-17D-induced CD8+ T cell and B cell responses were substantially lower in immunized individuals from Entebbe compared with immunized individuals from Lausanne. The impaired vaccine response in the Entebbe cohort associated with reduced YF-17D replication. Prior to vaccination, we observed higher frequencies of exhausted and activated NK cells, differentiated T and B cell subsets and proinflammatory monocytes, suggesting an activated immune microenvironment in the Entebbe volunteers. Interestingly, activation of CD8+ T cells and B cells as well as proinflammatory monocytes at baseline negatively correlated with YF-17D-neutralizing antibody titers after vaccination. Additionally, memory T and B cell responses in preimmunized volunteers exhibited reduced persistence in the Entebbe cohort but were boosted by a second vaccination. Conclusion. Together, these results demonstrate that an activated immune microenvironment prior to vaccination impedes efficacy of the YF-17D vaccine in an African cohort and suggest that vaccine regimens may need to be boosted in African populations to achieve efficient immunity. Trial registration. Registration is not required for observational studies. Funding. This study was funded by Canada's Global Health Research Initiative, Defense Threat Reduction Agency, National Institute of Allergy and Infectious Diseases, Bill & Melinda Gates Foundation, and United States Agency for International Development.

Early dyadic patterns of mother-infant interactions and outcomes of prematurity at 18 months.

OBJECTIVE: With the increased survival of very preterm infants, there is a growing concern for their developmental and socioemotional outcomes. The quality of the early mother-infant relationship has been noted as 1 of the factors that may exacerbate or soften the potentially adverse impact of preterm birth, particularly concerning the infant's later competencies and development. The first purpose of the study was to identify at 6 months of corrected age whether there were specific dyadic mother-infant patterns of interaction in preterm as compared with term mother-infant dyads. The second purpose was to examine the potential impact of these dyadic patterns on the infant's behavioral and developmental outcomes at 18 months of corrected age. METHODS: During a 12-month period (January-December 1998), all preterm infants who were <34 weeks of gestational age and hospitalized at the NICU of the Lausanne University Hospital were considered for inclusion in this longitudinal prospective follow-up study. Control healthy term infants were recruited during the same period from the maternity ward of our hospital. Mother-infant dyads with preterm infants (n = 47) and term infants (n = 25) were assessed at 6 months of corrected age during a mother-infant play interaction and coded according to the Care Index. This instrument evaluates the mother's interactional behavior according to 3 scales (sensitivity, control, and unresponsiveness) and the child's interactional behavior according to 4 scales (cooperation, compliance, difficult, and passivity). At 18 months, behavioral outcomes of the children were assessed on the basis of a semistructured interview of the mother, the Symptom Check List. The Symptom Check List explores 4 groups of behavioral symptoms: sleeping problems, eating problems, psychosomatic symptoms, and behavioral and emotional disorders. At the same age, developmental outcomes were evaluated using the Griffiths Developmental Scales. Five areas were evaluated: locomotor, personal-social, hearing and speech, eye-hand coordination, and performance. RESULTS: Among the possible dyadic patterns of interaction, 2 patterns emerge recurrently in mother-infant preterm dyads: a "cooperative pattern" with a sensitive mother and a cooperative-responsive infant (28%) and a "controlling pattern" with a controlling mother and a compulsive-compliant infant (28%). The remaining 44% form a heterogeneous group that gathers all of the other preterm dyads and is composed of 1 sensitive mother-passive infant; 10 controlling mothers with a cooperative, difficult, or passive infant; and 10 unresponsive mothers with a cooperative, difficult, or passive infant. Among the term control subjects, 68% of the dyads are categorized as cooperative pattern dyads, 12% as controlling pattern dyads, and the 20% remaining as heterogeneous dyads. At 18 months, preterm infants of cooperative pattern dyads have similar outcomes as the term control infants. Preterm infants of controlling pattern dyads have significantly fewer positive outcomes as compared with preterm infants of cooperative pattern dyads, as well as compared with term control infants. They display significantly more behavioral symptoms than term infants, including more eating problems than term infants as well as infants from cooperative preterm dyads. Infants of the controlling preterm dyads do not differ significantly for the total development quotient but have worse personal-social development than term infants and worse hearing-speech development than infants from cooperative preterm dyads. The preterm infants of the heterogeneous group have outcomes that can be considered as intermediate with no significant differences compared with preterm infants from the cooperative pattern or the controlling pattern dyads. CONCLUSION: Among mother-preterm infant dyads, we identified 2 specific patterns of interaction that could play either a protective (cooperative pattern) or a risk-precipitating (controlling pattern) role on developmental and behavioral outcome, independent of perinatal risk factors and of the family's socioeconomic background. The controlling pattern is much more prevalent among preterm than term dyads and is related to a less favorable infant outcome. However, the cooperative pattern still represents almost 30% of the preterm dyads, with infants' outcome comparable to the ones of term infants. These results point out the impact of the quality of mother-infant relationship on the infant's outcome. The most important clinical implication should be to support a healthy parent-infant relationship already in the NICU but also in the first months of the infant's life. Early individualized family-based interventions during neonatal hospitalization and transition to home have been shown to reduce maternal stress and depression and increase maternal self-esteem and to improve positive early parent-preterm infant interactions.

Origin-related, environmental, sex, and age determinants of immunocompetence, susceptibility to ectoparasites, and disease symptoms in the barn owl

Knowledge of the role of origin-related, environmental, sex, and age factors on host defence mechanisms is important to understand variation in parasite intensity. Because alternative components of parasite defence may be differently sensitive to various factors, they may not necessarily covary. Many components should therefore be considered to tackle the evolution of host-parasite interactions. In a population of barn owls (Tyto alba), we investigated the role of origin-related, environmental (i.e. year, season, nest of rearing, and body condition), sex, and age factors on 12 traits linked to immune responses [humoral immune responses towards sheep red blood cells (SRBC), human serum albumin (HSA) and toxoid toxin TT, T-cell mediated immune response towards the mitogen phytohemagglutinin (PHA)], susceptibility to ectoparasites (number and fecundity of Carnus haemapterus, number of Ixodes ricinus), and disease symptoms (size of the bursa of Fabricius and spleen, proportion of proteins that are immunoglobulins, haematocrit and blood concentration in leucocytes). Cross-fostering experiments allowed us to detect a heritable component of variation in only four out of nine immune and parasitic parameters (i.e. SRBC- and HSA-responses, haematocrit, and number of C. haemapterus). However, because nestlings were not always cross-fostered just after hatching, the finding that 44% of the immune and parasitic parameters were heritable is probably an overestimation. These experiments also showed that five out of these nine parameters were sensitive to the nest environment (i.e. SRBC- and PHA-responses, number of C. haemapterus, haematocrit and blood concentration in leucocytes). Female nestlings were more infested by the blood-sucking fly C. haemapterus than their male nestmates, and their blood was less concentrated in leucocytes. The effect of year, season, age (i.e. reflecting the degree of maturation of the immune system), brood size, position in the within-brood age hierarchy, and body mass strongly differed between the 12 parameters. Different components of host defence mechanisms are therefore not equally heritable and sensitive to environmental, sex, and age factors, potentially explaining why most of these components did not covary.

Epidémiologie de la psychiatrie de consultation-liaison du Centre Psychosocial Neuchâtelois dans le service de Médecine interne de l'Hôpital de la Chaux-de-Fonds en 1994 et 1998 : Interactions et régulations

Résumé La psychiatrie de consultation-liaison (CL) connaît depuis une décennie un essor majeur en Europe sous l'impulsion des recherches multicentriques du groupe European Consultation Liaison Psychiatry - ECLVV (Huyse). En Suisse, la discipline reste à développer par manque de consultants spécialisés selon le rapport 2000 de l'Association des professeurs titulaires de chaires. Néanmoins une harmonisation progressive des standards européens de documentation et d'évaluation apparaît progressivement, notamment dans les travaux du Service de Psychiatrie de Liaison du Centre Hospitalier Universitaire Vaudois. Afin d'améliorer sa pratique de consultation-liaison qui restait jusqu'alors frustrante par un sentiment de débordement et d'absence de feed-back des interventions, le Centre Psychosocial Neuchâtelois de La Chaux-de-Fonds (CPS) a constitué une base de données informatisée de CL à des fins de recherche-action selon les recommandations du groupe ECLVV. Nous avons comparé les valeurs de prévalence de notre activité de CL dans le service de médecine interne de l'Hôpital de La Chaux-de-Fonds en 1994, année du début de l'informatisation des données du CPS, et en 1998, année des plus récents résultats exploitables. La taille de l'échantillon était de 78 cas pour 1994 et de 108 cas pour 1998. Les résultats de notre étude épidémiologique rétrospective et descriptive montraient une augmentation en volume des demandes de CL, une diversification et une complexification des cas. Cette charge croissante sur la psychiatrie de consultation-liaison s'observait également dans les données de la littérature. La réponse psychiatrique du CPS montrait une modestie de moyens et du pragmatisme dans le style des interventions. Ces dernières étaient essentiellement de nature de psychiatrie générale et d'urgence, focalisée sur les tentatives de suicides. Les tentamens, ici comme ailleurs, restent le noyau dur de toute pratique de psychiatrie à l'hôpital général. L'état de lieu de notre pratique de consultation-liaison issu de ce travail a permis de créer une base de données simplifée étendue à l'ensemble des demandes de consultation au CPS afin de réguler le flux de toutes ses interventions face aux demandes toujours croissantes. Dans ce sens, notre étude a montré la nécessité de formaliser les demandes de consultation psychiatrique à l'hôpital général afin d'optimaliser les réponses des consultants.

Plant species distributions along environmental gradients: do belowground interactions with fungi matter?

The distribution of plants along environmental gradients is constrained by abiotic and biotic factors. Cumulative evidence attests of the impact of biotic factors on plant distributions, but only few studies discuss the role of belowground communities. Soil fungi, in particular, are thought to play an important role in how plant species assemble locally into communities. We first review existing evidence, and then test the effect of the number of soil fungal operational taxonomic units (OTUs) on plant species distributions using a recently collected dataset of plant and metagenomic information on soil fungi in the Western Swiss Alps. Using species distribution models (SDMs), we investigated whether the distribution of individual plant species is correlated to the number of OTUs of two important soil fungal classes known to interact with plants: the Glomeromycetes, that are obligatory symbionts of plants, and the Agaricomycetes, that may be facultative plant symbionts, pathogens, or wood decayers. We show that including the fungal richness information in the models of plant species distributions improves predictive accuracy. Number of fungal OTUs is especially correlated to the distribution of high elevation plant species. We suggest that high elevation soil show greater variation in fungal assemblages that may in turn impact plant turnover among communities. We finally discuss how to move beyond correlative analyses, through the design of field experiments manipulating plant and fungal communities along environmental gradients.

Influence of the dipolar interactions in the magnetization reversal asymmetry of hard-soft magnetic ribbons

Partial crystallization of the metallic glass Co66Si16B12Fe4Mo2 was performed by annealing at temperatures between 500 and 540°C for 10-20 min, resulting in crystallite volume fractions of (0.7-5)×10¿3 and sizes of 50-100 nm. This two-phase alloy presents a remarkable feature: a hysteresis loop shift that can be tailored by simply premagnetizing the sample in the adequate magnetic field. Shifts as large as five times the coercive field have been obtained which make them interesting for application as magnetic cores in dc pulse transformers. The asymetrical magnetic reversal is explained in terms of the magnetic dipolar field interaction and the observed hysteresis loops have been satisfactorily simulated by a modification of Stoner-Wohlfarth¿s model of coherent rotations.

Blocking Junctional Adhesion Molecule C Enhances Dendritic Cell Migration and Boosts the Immune Responses against Leishmania major.

The recruitment of dendritic cells to sites of infections and their migration to lymph nodes is fundamental for antigen processing and presentation to T cells. In the present study, we showed that antibody blockade of junctional adhesion molecule C (JAM-C) on endothelial cells removed JAM-C away from junctions and increased vascular permeability after L. major infection. This has multiple consequences on the output of the immune response. In resistant C57BL/6 and susceptible BALB/c mice, we found higher numbers of innate immune cells migrating from blood to the site of infection. The subsequent migration of dendritic cells (DCs) from the skin to the draining lymph node was also improved, thereby boosting the induction of the adaptive immune response. In C57BL/6 mice, JAM-C blockade after L. major injection led to an enhanced IFN-γ dominated T helper 1 (Th1) response with reduced skin lesions and parasite burden. Conversely, anti JAM-C treatment increased the IL-4-driven T helper 2 (Th2) response in BALB/c mice with disease exacerbation. Overall, our results show that JAM-C blockade can finely-tune the innate cell migration and accelerate the consequent immune response to L. major without changing the type of the T helper cell response.

Coherent Stranski-Krastanov growth in 1+1 dimensions with anharmonic interactions: An equilibrium study

The formation of coherently strained three-dimensional (3D) islands on top of the wetting layer in the Stranski-Krastanov mode of growth is considered in a model in 1 + 1 dimensions accounting for the anharmonicity and nonconvexity of the real interatomic forces. It is shown that coherent 3D islands can be expected to form in compressed rather than expanded overlayers beyond a critical lattice misfit. In expanded overlayers the classical Stranski-Krastanov growth is expected to occur because the misfit dislocations can become energetically favored at smaller island sizes. The thermodynamic reason for coherent 3D islanding is incomplete wetting owing to the weaker adhesion of the edge atoms. Monolayer height islands with a critical size appear as necessary precursors of the 3D islands. This explains the experimentally observed narrow size distribution of the 3D islands. The 2D-3D transformation takes place by consecutive rearrangements of mono- to bilayer, bi- to trilayer islands, etc., after the corresponding critical sizes have been exceeded. The rearrangements are initiated by nucleation events, each one needing to overcome a lower energetic barrier than the one before. The model is in good qualitative agreement with available experimental observations.

Heat transfer between nanoparticles: Thermal conductance for near-field interactions

We analyze the heat transfer between two nanoparticles separated by a distance lying in the near-field domain in which energy interchange is due to the Coulomb interactions. The thermal conductance is computed by assuming that the particles have charge distributions characterized by fluctuating multipole moments in equilibrium with heat baths at two different temperatures. This quantity follows from the fluctuation-dissipation theorem for the fluctuations of the multipolar moments. We compare the behavior of the conductance as a function of the distance between the particles with the result obtained by means of molecular dynamics simulations. The formalism proposed enables us to provide a comprehensive explanation of the marked growth of the conductance when decreasing the distance between the nanoparticles.