Dengue and Chikungunya Coinfection – The Emergence of an Underestimated Threat

Both Dengue (DENV) and Chikungunya (CHIKV) viruses can be transmitted by Aedes mosquito species and the diseases that they cause have several clinical symptoms in common. Co-circulation of DENV and CHIKV is increasing around the world and must therefore be considered as an emerging threat with an important public health concern. At present, very little is known about the clinical manifestations and biological consequences of coinfection by both viruses. Thus, numerous questions such as clinical severity and dynamics of viral replication of DENV and CHIKV coinfections, as well as vectorial competence, have yet to be addressed in this important and challenging research area. The ensuring knowledge will enhance the clinical surveillance and the development of diagnostic tools able to differentiate DENV and CHIKV in order to early detect virus invasion and local transmission, as well as to improve patient care and timely control measures. In this review, we highlight the current knowledge on DENV and CHIKV coinfections. We also discuss research perspectives and challenges in order to further understand the ecology and biology of this phenomenon

Identification of an osteoclastogenic CD4+ T cell population producing IL-17 and TNFα

Poster presentationInternational audienc

Polarized Th2 like cells, in the absence of Th0 cells, are responsible for lymphocyte produced IL-4 in high IgE-producer schistosomiasis patients

BACKGROUND: Human resistance to re-infection with S. mansoni is correlated with high levels of anti-soluble adult worm antigens (SWAP) IgE. Although it has been shown that IL-4 and IL-5 are crucial in establishing IgE responses in vitro, the active in vivo production of these cytokines by T cells, and the degree of polarization of Th2 vs. Th0 in human schistosomiasis is not known. To address this question, we determined the frequency of IL-4 and IFN-γ or IL-5 and IL-2 producing lymphocytes from schistosomiasis patients with high or low levels of IgE anti-SWAP. RESULTS: Our analysis showed that high and low IgE-producers responded equally to schistosomiasis antigens as determined by proliferation. Moreover, patients from both groups displayed similar percentages of circulating lymphocytes. However, high IgE-producers had an increased percentage of activated CD4+ T cells as compared to the low IgE-producers. Moreover, intracellular cytokine analysis, after short-term stimulation with anti-CD3/CD28 mAbs, showed that IgE high-producers display an increase in the percentage of T lymphocytes expressing IL-4 and IL-5 as compared to IgE low-responders. A coordinate control of the frequency of IL-4 and IL-5 producing lymphocytes in IgE high, but not IgE low-responders, was observed. CONCLUSIONS: High IgE phenotype human schistosomiasis patients exhibit a coordinate regulation of IL-4 and IL-5 producing cells and the lymphocyte derived IL-4 comes from true polarized Th2 like cells, in the absence of measurable Th0 cells as measured by co-production of IL-4 and IFN-γ

Induction of a Peptide with Activity against a Broad Spectrum of Pathogens in the Aedes aegypti Salivary Gland, following Infection with Dengue Virus

The ultimate stage of the transmission of Dengue Virus (DENV) to man is strongly dependent on crosstalk between the virus and the immune system of its vector Aedes aegypti (Ae. aegypti). Infection of the mosquito's salivary glands by DENV is the final step prior to viral transmission. Therefore, in the present study, we have determined the modulatory effects of DENV infection on the immune response in this organ by carrying out a functional genomic analysis of uninfected salivary glands and salivary glands of female Ae. aegypti mosquitoes infected with DENV. We have shown that DENV infection of salivary glands strongly up-regulates the expression of genes that encode proteins involved in the vector's innate immune response, including the immune deficiency (IMD) and Toll signalling pathways, and that it induces the expression of the gene encoding a putative anti-bacterial, cecropin-like, peptide (AAEL000598). Both the chemically synthesized non-cleaved, signal peptide-containing gene product of AAEL000598, and the cleaved, mature form, were found to exert, in addition to antibacterial activity, anti-DENV and anti-Chikungunya viral activity. However, in contrast to the mature form, the immature cecropin peptide was far more effective against Chikungunya virus (CHIKV) and, furthermore, had strong anti-parasite activity as shown by its ability to kill Leishmania spp. Results from circular dichroism analysis showed that the immature form more readily adopts a helical conformation which would help it to cause membrane permeabilization, thus permitting its transfer across hydrophobic cell surfaces, which may explain the difference in the anti-pathogenic activity between the two forms. The present study underscores not only the importance of DENV-induced cecropin in the innate immune response of Ae. aegypti, but also emphasizes the broad-spectrum anti-pathogenic activity of the immature, signal peptide-containing form of this peptide

Ultrasensitive serum interferon-α quantification during SLE remission identifies patients at risk for relapse

International audienceObjectives Maintenance of remission has become central in the management of systemic lupus erythematosus (SLE). The importance of interferon-alpha (IFN-α) in the pathogenesis of SLE notwithstanding, its expression in remission has been poorly studied as yet. To study its expression in remission and its prognostic value in the prediction of a disease relapse, serum IFN-α levels were determined using an ultrasensitive single-molecule array digital immunoassay which enables the measurement of cytokines at physiological concentrations.Methods A total of 254 SLE patients in remission, according to the Definition of Remission in SLE classification, were included in the study. Serum IFN-α concentrations were determined at baseline and patients were followed up for 1 year. Lupus flares were defined according to the Safety of Estrogens in Lupus Erythematosus: National Assessment version of the Systemic Lupus Erythematosus Disease Activity Index Flare Index, whereas the Kaplan-Meier analysis and Cox regression analysis were used to estimate the time to relapse and to identify baseline factors associated with time to relapse, respectively.Results Of all patients in remission, 26% displayed abnormally high IFN-α serum levels that were associated with the presence of antibodies specific for ribonucleoprotein (RNP), double stranded (ds)DNA and Ro/SSA60, as well as young age. Importantly, elevated-baseline IFN-α serum levels and remission duration were associated in an independent fashion, with shorter time to relapse, while low serum levels of complement component 3 and anti-dsDNA Abs were not.Conclusion Direct serum IFN-α assessment with highly sensitive digital immunoassay permits clinicians to identify a subgroup of SLE patients, clinically in remission, but at higher risk of relapse

Etude de la régulation de l'expression de CXCR4 à la surface des lymphocytes T humains

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Generation and maintenance of cloned human T cell lines

This unit describes protocols for the generation of human (allo-) antigen-specific T cell lines, and T lymphocyte subpopulations with distinct cytokine production profiles from purified peripheral or cord blood CD4+ T cells, respectively. Methods for the cloning and maintenance of these cell lines are given, as well as a protocol for freeze/thaw procedure

Caractérisation phénotypique et fonctionnelle des lymphocytes T auxiliaires humains, producteurs d'IL-10 (Th2 et T régulateurs (Tr))

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Les lymphocytes Th17 humains (modulation de leur fonction effectrice par les cellules souches mésenchymateuses et caractérisation de leurs propriétés migratoires)

Les lymphocytes Th17 forment une population de cellules T CD4+ pro-inflammatoires, impliqués non seulement dans l'élimination d'agents pathogènes, mais ayant aussi un rôle délétère dans l'induction de maladies inflammatoires chroniques. Ils expriment spécifiquement le récepteur de chimiokines CCR6, qui a pour ligand le CCL20 mais aussi les b-defensine-1, 2 et 3, peptides ayant une activité antimicrobienne. Les cellules souches mésenchymateuses (CSMs) représentent une population cellulaire hétérogène exerçant diverses propriétés immunomodulatrices.Les résultats obtenus dans ce travail de thèse montrent que l'environnement inflammatoire contribue à augmenter l'adhésion des lymphocytes Th17 aux CSMs, et qu'elle est régulée par l'interaction du CCR6 avec ses ligands ; que les CSMs exercent, en partie via la sécrétion de PGE2, des effets anti-inflammatoires en faisant acquérir un phénotype régulateur aux lymphocytes Th17 différenciés, soulignant ainsi la plasticité de ces derniers.De plus, nous avons montré que les lymphocytes Th17 activés par l'antigène produisent du CCL20 et induisent, via la production de l'IL-17 et de l'IL-22, la sécrétion d'hBD-2, mais pas celle des hBD-1 et 3, par des kératinocytes épidermiques humains et de la peau reconstituée; que le CCL20, ainsi que la hBD-2, induisent l'arrêt de ces cellules sur l'endothélium enflammé in vitro en conditions de cisaillement. Finalement, l'activation spécifique d'antigène des lymphocytes Th17 entraîne une perte de l'expression de CCR6, ce qui provoque ainsi un état transitoire de non réponse à une nouvelle stimulation de ces cellules avec les ligands de CCR6, permettant leur migration ultérieure hors du tissu enflammé.Th17 cells form a population CD4+ T cells with strong pro-inflammatory properties that are not only involved in the clearance of pathogens, but also play a deleterious role of in the pathogenesis of inflammatory disease. Th17 cells specifically express CCR6, a chemokine receptor that binds to its unique chemokine ligand, CCL20, as well as to human b-defensin (hBD)-1, 2 and 3, peptides with anti-microbial activity. Mesenchymal stem cells (MSC) represent a heterogenous population that exert broad immunomodulatory effects.The results from the studies carried out during this thesis show that the inflammatory environment contributes to increased adhesion of Th17 cells to MSCs, which is mediated via the interaction of CCR6 with its ligands, and that MSCs exert, in part via the secretion of PGE2, anti-inflammatory effects through the induction of a T regulatory cell phenotype in fully differentiated tissue-infiltrating Th17 cells, thereby underscoring the plasticity of the latter cells.Furthermore, the results show that antigen-activated Th17 cells produce CCL20 and induce, via the production of both IL-17 and IL-22, the secretion of hBD-2, but not 1 and 3, by normal human epidermal keratinocytes and reconstituted skin, and that CCL20, as well as hBD-2, induce arrest of these cells onto inflamed endothelium in vitro under conditions of shear stress. Finally, antigen-specific activation of Th17 cells also causes a loss of CCR6 expression from their cell surface and thus results in a transitory state of non-responsiveness to further stimulation of these cells with CCR6 ligands, which is likely to permit their subsequent migration out of inflamed tissue.MONTPELLIER-BU Médecine UPM (341722108) / SudocSudocFranceF