A new instrument for kinetics and branching ratio studies of gas phase collisional processes at very low temperatures

A new instrument dedicated to the kinetic study of low-temperature gas phase neutral-neutral reactions, including clustering processes, is presented. It combines a supersonic flow reactor with vacuum ultra-violet synchrotron photoionization time-of-flight mass spectrometry. A photoion-photoelectron coincidence detection scheme has been adopted to optimize the particle counting efficiency. The characteristics of the instrument are detailed along with its capabilities illustrated through a few results obtained at low temperatures (<100 K) including a photoionization spectrum of n-butane, the detection of formic acid dimer formation, and the observation of diacetylene molecules formed by the reaction between the C₂H radical and C₂H₂.

AllergoOncology: ultra-low IgE, a potential novel biomarker in cancer-a Position Paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Elevated serum IgE levels are associated with allergic disorders, parasitosis and specific immunologic abnormalities. In addition, epidemiological and mechanistic evidence indicates an association between IgE-mediated immune surveillance and protection from tumour growth. Intriguingly, recent studies reveal a correlation between IgE deficiency and increased malignancy risk. This is the first review discussing IgE levels and links to pathological conditions, with special focus on the potential clinical significance of ultra-low serum IgE levels and risk of malignancy. In this Position Paper we discuss: (a) the utility of measuring total IgE levels in the management of allergies, parasitosis, and immunodeficiencies, (b) factors that may influence serum IgE levels, (c) IgE as a marker of different disorders, and d) the relationship between ultra-low IgE levels and malignancy susceptibility. While elevated serum IgE is generally associated with allergic/atopic conditions, very low or absent IgE may hamper anti-tumour surveillance, indicating the importance of a balanced IgE-mediated immune function. Ultra-low IgE may prove to be an unexpected biomarker for cancer risk. Nevertheless, given the early stage of investigations conducted mostly in patients with diseases that influence IgE levels, in-depth mechanistic studies and stratification of malignancy risk based on associated demographic, immunological and clinical co-factors are warranted.

Impact of allergy on phenotypic and endotypic profiles of nasal polyposis

OBJECTIVES

To assess the impact of allergy on clinical presentations (phenotypes) and inflammatory patterns (endotypes) of chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

A single-center prospective study was conducted over an 18-month period. Fifty-seven patients with refractory CRSwNP were included. The diagnosis of allergy was based on concordant skin prick tests and symptoms. Phenotypes were determined on symptom severity score, polyp size classification and Lund-Mackay CT staging. Inflammatory endotypes were determined on biomarker analysis (IgE, IgA, IL-5, IL-9, ECP, EDN) in blood and nasal secretions. Eosinophil counts were obtained in blood, nasal secretions and polyps.

RESULTS

Phenotype and endotype profiles were comparable in patients with (n=15) or without (n=42) allergy. Only asthma with high total IgE blood concentration showed association with allergy.

CONCLUSIONS

The present results suggest that allergy is not directly involved in the clinical expression and specific inflammatory pathways of CRSwNP. New therapies target inflammation signaling pathways, and identifying accurate blood and tissue biomarkers will be the line of research most likely to improve treatment of CRSwNP.

Preparation and investigation of P28GST-loaded PLGA microparticles for immunomodulation of experimental colitis

The aim of this work was to prepare and characterize (in vitro and in vivo) PLGA-based microparticles loaded with an enzymatic protein derived from the helminth parasite Schistosoma haematobium: glutathione S-transferase P28GST (P28GST). This protein is not only a promising candidate vaccine against schistosomiasis, it also exhibits interesting immunomodulating effects, which can be helpful for the regulation of inflammatory diseases. Helminths express a regulatory role on intestinal inflammation, and immunization by P28GST has recently been shown to be as efficient as infection to reduce inflammation in a murine colitis model. As an alternative to the combination with a classical adjuvant, long acting P28GST microparticles were prepared in order to induce colitis prevention. PLGA was used as biodegradable and biocompatible matrix former, and a W/O/W emulsion/solvent extraction technique applied to prepare different types of microparticles. The effects of key formulation and processing parameters (e.g., the polymer molecular weight, drug loading, W/O/W phase volumes and stirring rates of the primary/secondary emulsions) on the systems' performance were studied. Microparticles providing about constant P28GST release during several weeks were selected and their effects in an experimental model of colitis evaluated. Mice received P28GST-loaded or P28GST-free PLGA microparticles (s.c.) on Day 0, and optionally also on Days 14 and 28. Colitis was induced on Day 35, the animals were sacrificed on Day 37. Interestingly, the Wallace score (being a measure of the severity of the inflammation) was significantly lower in mice treated with P28GST microparticles compared to placebo after 1 or 3 injections. As immunogenicity markers, increased anti-P28GST IgG levels were detected after three P28GST PLGA microparticle injections, but not in the control groups. Thus, the proposed microparticles offer an interesting potential for the preventive treatment of experimental colitis, while the underlying mechanism of action is still to be investigated.

AllergoOncology - the impact of allergy in oncology: EAACI position paper

Th2 immunity and allergic immune surveillance play critical roles in host responses to pathogens, parasites and allergens. Numerous studies have reported significant links between Th2 responses and cancer, including insights into the functions of IgE antibodies and associated effector cells in both antitumour immune surveillance and therapy. The interdisciplinary field of AllergoOncology was given Task Force status by the European Academy of Allergy and Clinical Immunology in 2014. Affiliated expert groups focus on the interface between allergic responses and cancer, applied to immune surveillance, immunomodulation and the functions of IgE-mediated immune responses against cancer, to derive novel insights into more effective treatments. Coincident with rapid expansion in clinical application of cancer immunotherapies, here we review the current state-of-the-art and future translational opportunities, as well as challenges in this relatively new field. Recent developments include improved understanding of Th2 antibodies, intratumoral innate allergy effector cells and mediators, IgE-mediated tumour antigen cross-presentation by dendritic cells, as well as immunotherapeutic strategies such as vaccines and recombinant antibodies, and finally, the management of allergy in daily clinical oncology. Shedding light on the crosstalk between allergic response and cancer is paving the way for new avenues of treatment.

Periodontal manifestations of inflammatory bowel disease: emerging epidemiologic and biologic evidence

Inflammatory bowel disease and periodontitis are both described as a disproportionate mucosal inflammatory response to a microbial environment in susceptible patients. Moreover, these two conditions share major environmental and lifestyle-related risk factors. Despite this intriguing pathogenic parallel, large-scale studies and basic research have only recently considered periodontal outcomes as relevant data. There are mounting and consistent arguments, from recent epidemiologic studies and animal models, that these two conditions might be related. This article is a comprehensive and critical up-to-date review of the current evidence and future prospects in understanding the biologic and epidemiologic relationships between periodontal status and inflammatory bowel disease.

Low Temperature Kinetics of the First Steps of Water Cluster Formation

We present a combined experimental and theoretical low temperature kinetic study of water cluster formation. Water cluster growth takes place in low temperature (23-69 K) supersonic flows. The observed kinetics of formation of water clusters are reproduced with a kinetic model based on theoretical predictions for the first steps of clusterization. The temperature- and pressure-dependent association and dissociation rate coefficients are predicted with an ab initio transition state theory based master equation approach over a wide range of temperatures (20-100 K) and pressures (10^{-6}-10  bar).

Direct dehydration of 1,3-butanediol into butadiene over aluminosilicate catalysts

The catalytic dehydration of 1,3-butanediol into butadiene was investigated over various aluminosilicates with different SiO₂/Al₂O₃ ratios and pore architectures.

Performance of Ag/Al2O3 catalysts in the liquid phase oxidation of glycerol – effect of preparation method and reaction conditions

A series of silver supported catalysts have been developed and proposed for mild oxidation of glycerol in the liquid phase. High selectivity to glycolic acid, stability in both continuous-flow and periodic mode of reaction, and good resistance to crude glycerol impurities have been achieved.

From parasites to allergy: a second receptor for IgE

Human allergic responses are triggered when mast cells bind IgE antibodies. IgE production is also a regular feature of helminth infection and parasites can be killed by inflammatory cells such as macrophages, eosinophils and platelets sensitized by reaginic antibody. The IgE receptor they use has been identified only recently. Here André Capron and his colleagues discuss how it differs from the IgE receptor present on mast cells.

Gas flow in plant microfluidic networks controlled by capillary valves

The xylem vessels of trees constitute a model natural microfluidic system. In this work, we have studied the mechanism of air flow in the Populus xylem. The vessel microstructure was characterized by optical microscopy, transmission electronic microscopy (TEM), and atomic force microscopy (AFM) at different length scales. The xylem vessels have length ≈15 cm and diameter ≈20μm. Flow from one vessel to the next occurs through ∼102 pits, which are grouped together at the ends of the vessels. The pits contain a thin, porous pit membrane with a thickness of 310 nm. We have measured the Young's moduli of the vessel wall and of the pits (both water-saturated and after drying) by specific nanoindentation and nanoflexion experiments with AFM. We found that both the dried and water-saturated pit membranes have Young's modulus around 0.4 MPa, in agreement with values obtained by micromolding of pits deformed by an applied pressure difference. Air injection experiments reveal that air flows through the xylem vessels when the differential pressure across a sample is larger than a critical value ΔPc=1.8 MPa. In order to model the air flow rate for ΔP⩾ΔPc, we assumed the pit membrane to be a porous medium that is strained by the applied pressure difference. Water menisci in the pit pores play the role of capillary valves, which open at ΔP=ΔPc. From the point of view of the plant physiology, this work presents a basic understanding of the physics of bordered pits.

Formations of dumbbell C118 and C119 inside clusters of C60 molecules by collision with α particles

We report highly selective covalent bond modifications in collisions between keV alpha particles and van der Waals clusters of C(60) fullerenes. Surprisingly, C(119)(+) and C(118)(+) are the dominant molecular fusion products. We use molecular dynamics simulations to show that C(59)(+) and C(58)(+) ions--effectively produced in prompt knockout processes with He(2+)--react rapidly with C(60) to form dumbbell C(119)(+) and C(118)(+). Ion impact on molecular clusters in general is expected to lead to efficient secondary reactions of interest for astrophysics. These reactions are different from those induced by photons.

Effect of parasite infection on allergic disease

Vertebrates and helminths have co-evolved for 500 million years, developing mutual adaptation mechanisms between parasites and hosts. Today, however, helminth diseases are among the most neglected communicable diseases. Epidemiological evidence shows that exposure to helminth parasites is inversely correlated with allergy incidence, and helminths induce immune hyporeactivity in both the innate and adaptive systems. The mechanisms include parasite-derived regulatory molecules, the study of which opens new avenues for the control of allergic and autoimmune diseases.

Ions colliding with cold polycyclic aromatic hydrocarbon clusters

We report the first experimental study of ions interacting with clusters of polycyclic aromatic hydrocarbon (PAH) molecules. Collisions between 11.25 keV 3He+ or 360 keV 129Xe20+ and weakly bound clusters of one of the smallest PAH molecules, anthracene, show that C14H10 clusters have much higher tendencies to fragment in ion collisions than other weakly bound clusters. The ionization is dominated by peripheral collisions in which the clusters, very surprisingly, are more strongly heated by Xe20+ collisions than by He+ collisions. The appearance size is k=15 for [C ₁₄H₁₀](k)2+.

Antibody and cytokine responses in BALB/c mice immunized with the excreted/secreted proteins of Giardia intestinalis: the role of cysteine proteases

The mechanisms involved in the induction of the immune response in humans or experimental hosts infected with Giardia intestinalis are not well understood. The results of previous studies indicate that the parasite induces a mixed Th1/Th2 response and that, in experimentally infected mice, the parasite's excreted/secreted (E/S) proteins contain cysteine proteases that are recognised by the murine immune system. In the present study, the possible effects of the E/S proteases of G. intestinalis on the host's humoral and cellular immune responses were investigated in BALB/c mice immunized with the parasite's E/S proteins. High titres of specific IgG(1), IgG(2a) and IgE antibodies were detected after immunization with native E/S proteins. Spleen cells stimulated with such proteins in vitro showed a significant antigen-specific proliferative response accompanied by the production of high concentrations of interleukin-4 (IL-4), interleukin-5 (IL-5) and interleukin-10 (IL-10) but little secretion of interferon-gamma (IFN-gamma). When, before use, the proteases in the E/S proteins were inhibited, by heat treatment or the addition of E-64, they elicited much lower titres of specific IgG(1) and IgE in mice while, in splenocytes in vitro, they triggered much lower production of IL-4, IL-5 and IL-10 and reduced antigen-specific proliferation. Since E-64 only inhibits cysteine proteases, these results indicate that the excreted/secreted cysteine proteases of G. intestinalis may be involved in the induction and regulation of a specific immune response in the infected host.

AllergoOncology: the role of IgE-mediated allergy in cancer

Epidemiological studies have suggested inverse associations between allergic diseases and malignancies. As a proof of concept for the capability of immunoglobulin E (IgE) to destruct tumor cells, several experimental strategies have evolved to specifically target this antibody class towards relevant tumor antigens. It could be demonstrated that IgE antibodies specific to overexpressed tumor antigens have been superior to any other immunoglobulin class with respect to antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP) reactions. In an alternative approach, IgE nonspecifically attached to tumor cells proved to be a powerful adjuvant establishing tumor-specific immune memory. Active Th2 immunity could also be achieved by applying an oral immunization regimen using mimotopes, i.e. epitope mimics of tumor antigens. The induced IgE antibodies could be cross-linked by live tumor cells leading to tumoricidic mediator release. Thus, IgE antibodies may not only act in natural tumor surveillance, but could possibly also be exploited for tumor control in active and passive immunotherapy settings. Thereby, eosinophils, mast cells and macrophages can be armed with the cytophilic IgE and become potent anti-tumor effectors, able to trace viable tumor cells in the tissues. It is strongly suggested that the evolving new field AllergoOncology will give new insights into the role of IgE-mediated allergy in malignancies, possibly opening new avenues for tumor therapy.

IgE and inflammatory cells

Extensive studies initiated in parasitic disease models have unequivocally established that IgE antibodies can directly interact with mononuclear phagocytes, eosinophils and platelets through specific surface receptors now identified as Fc epsilon RII. Genes coding for B cell and more recently eosinophil IgE receptors have been cloned. Studies on molecular structure indicate a close homology between Fc epsilon RII on inflammatory cells and on B cells but indications are emerging of some degree of heterogeneity among the second class of receptors for IgE. Recent studies performed in parallel on eosinophils indicate that their IgE receptors contain a sequence commonly involved in the primary structure of adhesion proteins. Interaction between antigen and cytophilically bound IgE antibodies results in the triggering of cell effector function and the release of a variety of pro-inflammatory or cytocidal mediators. Among others, one eosinophil granule protein (eosinophil peroxidase) is preferentially released by anaphylactic isotype-dependent stimuli. The main expression of IgE-dependent platelet activation appears related to the production of oxygen-derived free radicals (detected by chemoluminescence and electron magnetic resonance) together with their cytocidal properties. Taken together these findings confirm our current view that IgE receptors on inflammatory cells play a major role in the expression of cell effector function, both in defence mechanisms against several parasites and in allergic reactions.

A new experimental cell for in situ and operandoX-ray absorption measurements in heterogeneous catalysis

A new X-ray absorption cell dedicated to in situ and operando experiments in heterogeneous catalysis has been built and tested. The cell consists of several boron nitride and stainless steel plates linked together using graphite seals. It allows the measurement of XANES and EXAFS spectra of heterogeneous catalysts within a wide range of photon energies in transmission mode under the flow of various oxidative and reductive gas mixtures at elevated temperatures. The cell is compact and easy to build. Catalysts are loaded into the cell as powders. The use of boron nitride and a small beam pathlength in the cell result in a low absorption of the X-ray beam at lower energies. The cell was tested by in situ characterizing cobalt species during oxidative and reductive pre-treatments of a silica-supported Fischer-Tropsch catalyst. An operando study of methanol conversion over alumina-supported molybdenum catalysts was also carried out.

Schistosomiasis co-infection in humans influences inflammatory markers in uncomplicated Plasmodium falciparum malaria

Malaria and schistosomiasis are the two major parasite diseases present in developing countries. The epidemiological co-infection with schistosomiasis could influence the development of the physiological reaction associated with Plasmodium falciparum infection in human. Most studies have demonstrated the association of circulating levels of interferon-gamma (IFN-gamma), tumour necrosis factor-a (TNF-alpha), interleukin-10 (IL-10), transforming growth factor (TGF-beta) and soluble Tumour Necrosis Factor Receptors (sTNF-RI and sTNF-RII) with the morbidity of malaria. In the present study, we showed that Schistosoma haematobium co-infection influences, in an age-dependent manner, the unbalance between pro- and anti-inflammatory circulating cytokines that play a key role during malaria infection. Indeed, children co-infected by S. haematobium have higher levels of IFN-gamma and sTNF-RII than children infected only by P. falciparum. In contrast, co-infected adults presented a significant increase of IFN-gamma, IL-10, TGF-beta, sTNF-RI and sTNF-RII rates and IL-10/TNF-alpha ratio. Taken together, this study indicates that schistosomiasis co-infection can unbalance the regulation of inflammatory factors in uncomplicated P. falciparum malaria. The possible consequences of the schistosomiasis co-infection for age-dependent malaria morbidity are discussed.

CD28 and secretory immunoglobulin A-dependent activation of eosinophils: inhibition of mediator release by the anti-allergic drug, suplatast tosilate

BACKGROUND

Eosinophils are major effector cells in allergic diseases. After their recruitment to sites of inflammation, they contribute to the pathophysiology of the disease by releasing granule proteins and cytokines. Suplatast tosilate (IPD-1151T), a new anti-allergic agent, has shown beneficial effect in the treatment of asthma, associated with reduced bronchoalveolar lavage eosinophil infiltration and eosinophilic cationic protein (ECP) release in serum and sputum.

OBJECTIVE

We investigated whether suplatast tosilate could exert direct effects on human eosinophil activation.

METHODS

Eosinophils from hypereosinophilic patients or normal donors were purified by Percoll gradient and the magnetic cell separation system. Chemotaxis was studied using the Boyden chamber technique using three chemoattractants, formyl-methionine-leucine-phenylalanine (fMLP), IL-5 and eotaxin. Oxidative metabolism was determined by a luminol-dependent chemiluminescence assay after activation with eotaxin or secretory IgA (sIgA). The release of ECP and eosinophil derived neurotoxin (EDN) was measured by radioimmunoassay and cytokine production was determined by ELISA following activation with sIgA or anti-CD28.

RESULTS

The chemotactic response to fMLP, IL-5 and eotaxin was significantly inhibited by IPD-1151T. Suplatast tosilate was partially inhibiting the release of reactive oxygen species (ROS) induced by eotaxin and sIgA. Activation by sIgA and CD28 ligation resulted in the release of ECP and EDN, which was inhibited by IPD-1151T. Upon activation by anti-CD28, only IL-13 production was inhibited by IPD-1151T, whereas release of IL-2 and IFN-gamma was not affected. IL-10 release induced by sIgA was also inhibited by IPD-1151T. Additionally, the pro-inflammatory cytokine IL-6, which was secreted following anti-CD28 and sIgA stimulation, was strongly inhibited by IPD-1151T.

CONCLUSION

Through inhibition of chemotaxis, IPD-1151T might limit the number of eosinophils at the inflammation site. Furthermore, it could reduce the pathological potential of eosinophils by inhibiting the release of ROS and cationic proteins, main inflammatory mediators produced by eosinophils. Moreover, the inhibition of immunoregulatory cytokines released by eosinophils could locally modify the immune response.

Methylated CpG-Containing Plasmid Activates the Immune System

Bacterial DNA differs from mammalian DNA by the presence of unmethylated cytosine-phosphate-guanosine (CpG) motifs. The immunostimulatory properties of a DNA vaccine have been suspected to be associated with these motifs. The aim of this study was to assess the inactivation of the immunostimulatory potential of a plasmid after methylation of its CpG motifs. We constructed two identical non-coding plasmids, and one of these was de novo methylated on its CG sequences. A single administration of recombinant antigen with methylated or unmethylated CpG-containing plasmid was performed in mice. As expected, only unmethylated CpG-containing plasmid enhanced the specific immune response. However, a study of in vivo activation of Langerhans' cells and analysis of mRNA synthesis indicated that both the plasmids promoted cell emigration and cytokine induction. These data highlight that a methylated CpG-containing plasmid is not inert and carries immunomodulatory properties. The results further emphasize the necessity to definitively identify the mode of action of plasmids used for DNA vaccination.

Hypereosinophilia with abnormal T cells, trisomy 7 and elevated TARC serum level

The idiopathic hypereosinophilic syndrome (HES) is a rare heterogeneous disorder, characterized by persistent blood eosinophilia with possible organ involvement. We describe here the case of a 20-year-old atopic male presenting chronic hypereosinophilia and eczema since childhood. Biological findings included hypereosinophilia (9.5 x 10(9)/L), hyperlymphocytosis (10.9 x 10(9)/L), polyclonal hypergammaglobulinemia and elevated IgE serum level. Flow cytometric analysis of blood lymphoid cells showed a population of CD2+CD3-CD4+TCRab-TCRgd- lymphocytes. These cells displayed a Th0/Th2 cytokine profile, and a clonal TCR rearrangement pattern. A high serum TARC level was observed. Karyotype studies on blood stimulated culture or lymph nodes revealed a cellular hyperdiploïd clone 47, XY, +7. To our knowledge, this chromosomal aberration has never been reported in such case.

Inhibitory effects of ketotifen on eotaxin-dependent activation of eosinophils: consequences for allergic eye diseases

BACKGROUND

The aim of this study was to investigate the effects of ketotifen on different parameters of human eosinophil functions, namely chemotaxis, oxidative metabolism and mediator release, induced after activation.

METHODS

Eosinophils from hypereosinophilic patients or normal donors were purified by Percoll gradient and the magnetic cell separation system. Chemotaxis was studied using the Boyden chamber technique using three potent chemoattractants: formyl-methionine-leucine-phenylalanine (fMLP), interleukin (IL)-5 and eotaxin. Oxidative metabolism was determined by a luminol-dependent chemiluminescence assay after activation with eotaxin or secretory immunoglobulin A (sIgA). The release of eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) was measured by radioimmunoassay after activation with sIgA.

RESULTS

At pharmacologically active concentrations and in a dose-dependent manner, ketotifen significantly inhibited the chemotaxis of eosinophils to fMLP, IL-5 and eotaxin. The production of reactive oxygen species induced by eotaxin and sIgA was decreased by ketotifen, showing a more pronounced effect when cells were activated by eotaxin. Activation by sIgA resulted in ECP and EDN release, which was partially inhibited by ketotifen.

CONCLUSIONS

Through inhibition of chemotaxis, ketotifen might limit the number of eosinophils at the inflammation site during allergic reaction. Furthermore, inhibition by ketotifen of main inflammatory mediators release suggests a potential role of the drug in limiting the pathological potential of eosinophils.

Malaria co-infection in children influences antibody response to schistosome antigens and inflammatory markers associated with morbidity

The epidemiological coexistence of schistosomiasis and malaria is frequently observed in developing countries. Co-infection with malaria in children could influence the development of acquired immunity associated with the resistance or the pathology of schistosomiasis. In the present study, performed during May to June 1996 in Senegal, the humoral immune response to Schistosoma haematobium 28 kDa glutathione S-transferase (Sh28GST) vaccinal antigen and to soluble egg antigens (SEA) has been evaluated in individuals infected by S. haematobium. Specific immunoglobulin G3 (IgG3) and IgE responses were significantly higher in co-infected children with Plasmodium falciparum compared with children infected with S. haematobium only. In addition, circulating levels of interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and soluble tumor necrosis factor receptor II (sTNF-RII), 3 parameters associated with schistosomiasis morbidity, were significantly increased in co-infected children. Taken together, this study indicated that malaria co-infection can both influence the acquired specific immune response to schistosome antigens and unbalance the regulation of inflammatory factors closely involved in schistosomiasis pathology.

Morphogenesis during division and griseofulvin-induced changes of the microtubular cytoskeleton in the parasitic protist, Trichomonas vaginalis

The behavior of microtubular structures during division was followed by immunofluorescence in Trichomonas vaginalis using an anti-alpha-tubulin monoclonal antibody together with nuclear staining by DAPI, allowing us to describe successive mitotic stages. In contrast to recent reports, we showed that: (1) the microtubular axostyle-pelta complex depolymerized during division, (2) the flagella were assembled during mitosis, and (3) the flagellar number was restored in each daughter kinetid before cytokinesis. Observation of griseofulvin-treated T. vaginalis cells revealed that the elongation of the mitotic spindle or paradesmosis was not the main motile force separating the daughter kinetids to opposite poles during division, suggesting the existence of other mechanisms and/or molecules involved in this morphogenetic event. Examination of treated cells re-incubated in fresh medium showed the nucleation of microtubules radiating from the perinuclear area, the origin of which is discussed. Finally, we confirm the effectiveness of griseofulvin against T. vaginalis and propose that this antifungal drug could be a promising antitrichomonal agent.

Inflammatory responses in Ebola virus-infected patients

Ebola virus subtype Zaire (Ebo-Z) induces acute haemorrhagic fever and a 60-80% mortality rate in humans. Inflammatory responses were monitored in victims and survivors of Ebo-Z haemorrhagic fever during two recent outbreaks in Gabon. Survivors were characterized by a transient release in plasma of interleukin-1beta (IL-1beta), IL-6, tumour necrosis factor-alpha (TNFalpha), macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta early in the disease, followed by circulation of IL-1 receptor antagonist (IL-1RA) and soluble receptors for TNFalpha (sTNF-R) and IL-6 (sIL-6R) towards the end of the symptomatic phase and after recovery. Fatal infection was associated with moderate levels of TNFalpha and IL-6, and high levels of IL-10, IL-1RA and sTNF-R, in the days before death, while IL-1beta was not detected and MIP-1alpha and MIP-1beta concentrations were similar to those of endemic controls. Simultaneous massive activation of monocytes/macrophages, the main target of Ebo-Z, was suggested in fatal infection by elevated neopterin levels. Thus, presence of IL-1beta and of elevated concentrations of IL-6 in plasma during the symptomatic phase can be used as markers of non-fatal infection, while release of IL-10 and of high levels of neopterin and IL-1RA in plasma as soon as a few days after the disease onset is indicative of a fatal outcome. In conclusion, recovery from Ebo-Z infection is associated with early and well-regulated inflammatory responses, which may be crucial in controlling viral replication and inducing specific immunity. In contrast, defective inflammatory responses and massive monocyte/macrophage activation were associated with fatal outcome.

[Contribution of experimental models to the understanding of immunity to schistosomiasis]

The discovery of a functional division in T helper cells on the basis of their cytokine secretion patterns has changed our vision of immunological responses. This dichotomy has equally shown the complexity of immune responses since there is a well orchestrated cross-regulation of cytokine production induced by viral, bacterial or parasitic pathogens. In the context of type 1-type 2 cytokine pattern, mice has been universally and extensively used to associate an infectious disease according to each category in order to better understand human infections. However, with respect to schistosomiasis, immunological observations in mice have not been confirmed in humans and particularly the nature of the protective immune response. This report will consider the relevance of extrapolating from immunological studies on schistosome in experimentally infected rats to studies on naturally infected humans.

Eosinophils, allergy and parasites

Recently, known eosinophil functions have been extended considerably: previously the cells were thought to have an exclusive role in the release of cytotoxic mediators; now they are known to have roles in antigen presentation and immunoregulation through the release of cytokines. Although questionable, animal models indicate a rather beneficial role of eosinophils in parasitic infections but a detrimental one, together with other cells, in allergy.

Cloning of the rat IL-5Ralpha gene: analysis of 5'-upstream region and expression by B cells

Although rats are widely used for the analysis of allergic reactions and parasitic infections where IL-5 is involved, nothing is currently known of the expression of IL-5 receptor in this species. In this study, the cDNA sequence, genomic structure and the transcriptional regulation of the rat IL-5Ralpha were analyzed. The rat IL-5Ralpha gene, which we localized to chromosome 4q34-q41, spans more than 25 kb and consists of 12 exons. Promoter activity was seen in different cell lines and analysis by deletion experiments allowed to identify two negative regulatory regions which did not differ when tested either with IL-5Ralpha-negative or positive cells. Finally, the investigation of the expression of IL-5Ralpha showed that it is expressed in lung, spleen, liver, and purified rat B cells from normal rat. This can provide an explanation for the role of rat IL-5 as B-cell growth factor and a relevant model in order to better understand the activity of IL-5 on human B cells.

Schistosoma mansoni induces the synthesis of IL-6 in pulmonary microvascular endothelial cells: role of IL-6 in the control of lung eosinophilia during infection

The nature of the interactions between the intravascular parasite Schistosoma mansoni and the host pulmonary vasculature is critical in determining the outcome of infection. In this report, we show that lung schistosomula selectively induce the synthesis of IL-6 mRNA and protein in cultured human and mouse lung microvascular endothelial cells (EC) and that parasite excretory/secretory lipophilic compounds, particularly prostaglandin E(2), are responsible for this effect. In vivo, a striking increase of IL-6 expression is observed in the pulmonary microvasculature of S. mansoni-infected C57BL/6 mice suggesting that, in vivo, parasites also induce the synthesis of IL-6 in lung EC. In infected mice, IL-6 deficiency results in an accelerated mobilization of eosinophils into the lung tissue and in a dramatic increased number of recruited leukocytes, particularly eosinophils, in the airway. This effect is associated with an enhanced production of eotaxin (CCL11) and IL-5 in the lungs of IL-6 knockout (KO) animals. Finally, compared to wild-type mice, we detect a dramatic increased level of parasite mortality in the lungs of IL-6 KO mice. Taken together, we suggest that parasite larvae activate EC to produce IL-6 to escape the inflammatory reaction that develops in the lungs of infected hosts. Finally, we show that the parasite-induced IL-6 synthesis is mediated by a protein kinase A-dependent pathway that principally targets the cAMP-response element and the nuclear factor-kappaB sites from the -256/+20 region of the IL-6 promoter.

Human eosinophils and human high affinity IgE receptor transgenic mouse eosinophils express low levels of high affinity IgE receptor, but release IL-10 upon receptor activation

FcepsilonRI expressed by human eosinophils is involved in IgE-mediated cytotoxicity reactions toward the parasite Schistosoma mansoni in vitro. However, because receptor expression is low on these cells, its functional role is still controversial. In this study, we have measured surface and intracellular expression of FcepsilonRI by blood eosinophils from hypereosinophilic patients and normal donors. The number of unoccupied receptors corresponded to approximately 4,500 Ab binding sites per cell, whereas 50,000 Ab binding sites per cell were detected intracellularly. Eosinophils from patients displayed significantly more unoccupied receptors than cells from normal donors. This number correlated to both serum IgE concentrations and to membrane-bound IgE. The lack of FcepsilonRI expression by mouse eosinophils has hampered further studies. To overcome this fact and experimentally confirm our findings on human eosinophils, we engineered IL-5 x hFcepsilonRIalpha double-transgenic mice, whose bone marrow, blood, spleen, and peritoneal eosinophils expressed FcepsilonRI levels similar to levels of human eosinophils, after 4 days culture with IgE in the presence of IL-5. Both human and mouse eosinophils were able to secrete IL-10 upon FcepsilonRI engagement. Thus, comparative analysis of cells from patients and from a relevant animal model allowed us to clearly demonstrate that FcepsilonRI-mediated eosinophil activation leads to IL-10 secretion. Through FcepsilonRI expression, these cells are able to contribute to both the regulation of the immune response and to its effector mechanisms.

Vaccine strategies against schistosomiasis: from concepts to clinical trials

Schistosomiasis, the second major parasitic disease in the world after malaria, affects 200 million people. Vaccine strategies represent an essential component of the control of this chronic debilitating disease where the deposition of millions of eggs in the tissues is the main cause of pathology. Research developed in our laboratory over the last 20 years has led to the identification of novel effector mechanisms, pointing for the first time to the protective role of Th2 responses and of IgE antibodies now supported by seven studies in human populations. The identification and molecular cloning of a target antigen, a glutathione S-transferase (GST), has made it possible to demonstrate its vaccine potential in several animal species (rodents, cattle, primates) and to establish consistently the capacity of vaccination to reduce female worm fecundity and egg viability through the production of neutralizing antibodies (IgA and IgG). Following promising preclinical studies, clinical trials (phase I and II) have been undertaken using Schistosoma haematobium GST, Sh28GST. High titers of neutralizing antibodies were produced (IgG3 and IgA) together with Th2 cytokines, consistently with the concepts developed from experimental models. With these results we are on the way towards a feasible approach of vaccine development against a major human parasitic disease.

Peroxisome proliferator-activated receptor gamma activators inhibit interleukin-12 production in murine dendritic cells

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily. They are divided into three subtypes (alpha, beta or delta, and gamma) and are involved in lipid and glucose homeostasis and in the control of inflammation. In this study, we analyzed the expression of PPARs in murine dendritic cells (DCs), the most potent antigen presenting cells. We find that immature as well as mature spleen-derived DCs express PPARgamma, but not PPARalpha, mRNA and protein. We also show that the PPARgamma activator rosiglitazone does not interfere with the maturation of DCs in vitro nor modifies their ability to activate naive T lymphocytes in vivo. Finally, we present evidence that PPARgamma activators down-modulate the CD40-induced secretion of interleukin-12, a potent Th1-driving factor. These data suggest a possible role for PPARgamma in the regulation of immune responses.

Mechanisms of resistance to S. mansoni infection: the rat model

Human schistosomiasis is associated with IgE and eosinophilia, feature of a type 2 response. In experimental investigations, murine model has been widely used in order to dissect the immune responses involved in the expression of protective immunity or disease in Schistosoma mansoni infection. Collectively, observations made in this model and in humans demonstrated a strong contrast since a Th2 response in infected mice is involved in the expression of pathology, however, in infected humans the same type of response is rather beneficial for the host. This review will consider the relevance of extrapolating studies of immune responses from experimentally infected rats a semi-permissive host, to studies on S. mansoni infected humans.

Enhanced production of IL-8 in chronic but not in early ileal lesions of Crohn's disease (CD)

Distinct Th1/Th2 patterns have been observed during the evolution of CD. The aim of this study was to compare neutrophil involvement and IL-8 mRNA and protein expression during early recurrent lesions and chronic phases of CD. Twenty-nine patients with CD having ileocolonic resection with anastomosis were studied. Biopsies were obtained during surgery from the non-inflamed ileal mucosa and from chronic ileal lesions. Endoscopic ileal biopsies were also taken from early recurrent ileal lesions occurring 3 months after surgery. Neutrophil counts were performed and mucosal IL-8 levels were evaluated by competitive reverse transcriptase-polymerase chain reaction and immunohistochemistry. Early recurrent ileal lesions were characterized by low neutrophil counts and IL-8 production at the mRNA and protein levels compared with the ileal chronic lesions. The main cellular sources of IL-8 in the early recurrent lesions were neutrophils, while in chronic lesions the majority of IL-8-stained cells were CD3+ T cells and macrophages. These results confirmed that the nature of the inflammatory infiltrate and the expression of cytokine profiles may differ between the acute and chronic phases of CD.