Surface Of Dendritic Cells Research Articles

TARGETING THE Plasmodium chabaudi MSP-1(19) PROTEIN TO THE DEC205 DENDRITIC CELL POPULATION INDUCES FASTER PARASITE CLEARANCE

Event Abstract Back to Event TARGETING THE Plasmodium chabaudi MSP-1(19) PROTEIN TO THE DEC205 DENDRITIC CELL POPULATION INDUCES FASTER PARASITE CLEARANCE Raquel H. Panatieri1*, Henrique B. Da Silva1, Marcio M. Yamamoto1, Maria Regina D. Lima1 and Silvia B. Boscardin1 1 Universidade de Sao Paulo, Brazil Malaria is an infectious disease distributed worldwide. It’s responsible for thousands of deaths every year, affecting mainly children. The acquired immune response during infection is partial and transitory. A membrane antigen of the merozoite is widely used as a vaccine target because of its immunogenic properties. This protein is expressed during schizogony as a precursor of 200kDa that undergoes successive cleavages, finally remaining anchored in the membrane as a portion of 19kDa named MSP-1(19), which has an important role in the reinvasion of the erythrocytes. Several studies have focused on the development of a vaccine against the parasite that leads to the maintenance of a protective memory response to different immunization schedules. A promising vaccine strategy is to target antigens directly to dendritic cells (DC) in vivo. This is accomplished by the administration of a monoclonal antibody that recognizes the endocytic receptor DEC205 present at the surface of DCs fused with an antigen of interest. Here we produced a hybrid αDEC205 coupled to the MSP-1(19) from Plasmodium chabaudi (AS) and used it to prime C57BL/6 mice that were subsequently boosted with the recombinant MSP-1(19) protein in the presence of Poly (I:C). Anti P. chabaudi MSP-1(19) antibodies were only detected in mice that received a boost with the recombinant MSP-1(19) protein. Protection against acute infection correlated with higher antibody titers. Adoptive transfer of blood from immunized and challenged mice showed a faster parasite clearance when MSP-1(19) was targeted to dendritic cells using the αDEC-MSP-1(19) antibody. Acknowledgements Supported by FAPESP, CNPq and INCTV. Keywords: Malaria, MSP1, Dendritic Cells, DEC205, clearence Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Host-pathogen interactions Citation: Panatieri RH, Da Silva HB, Yamamoto MM, Lima MD and Boscardin SB (2013). TARGETING THE Plasmodium chabaudi MSP-1(19) PROTEIN TO THE DEC205 DENDRITIC CELL POPULATION INDUCES FASTER PARASITE CLEARANCE. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00555 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 May 2013; Published Online: 22 Aug 2013. * Correspondence: Miss. Raquel H Panatieri, Universidade de Sao Paulo, Sao Paulo, Brazil, rachhpp@yahoo.com.br Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Raquel H Panatieri Henrique B Da Silva Marcio M Yamamoto Maria Regina D Lima Silvia B Boscardin Google Raquel H Panatieri Henrique B Da Silva Marcio M Yamamoto Maria Regina D Lima Silvia B Boscardin Google Scholar Raquel H Panatieri Henrique B Da Silva Marcio M Yamamoto Maria Regina D Lima Silvia B Boscardin PubMed Raquel H Panatieri Henrique B Da Silva Marcio M Yamamoto Maria Regina D Lima Silvia B Boscardin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Baicalin From Scutellaria baicalensis Impairs Th1 Polarization Through Inhibition of Dendritic Cell Maturation

Baicalin from Scutellaria baicalensis is a major flavonoid constituent found in the traditional Chinese medicinal herb Baikal skull cap. It has been widely used for the treatment of various diseases such as pneumonia, diarrhea, and hepatitis. Recent studies have demonstrated that baicalin possesses a wide range of pharmacological and biological activities, including anti-inflammatory, anti-microbial, anti-oxidant, and anti-tumor properties. Specifically, its antiinflammatory activity has been estimated in various animal models of acute and chronic inflammation; however, its effects on dendritic cells (DCs) maturation and immuno-stimulatory activities are still unknown. In this study, we attempted to determine whether baicalin could influence DC surface molecule expression, antigen uptake capacity, cytokine production, and capacity to induce T-cell differentiation. Baicalin was shown to significantly suppress the expression of surface molecules CD80, CD86, major histocompatibility complex (MHC) class I, and MHC class II as well as the levels of interleukin-12 production in lipopolysaccharide stimulated DCs. Moreover, baicalin-treated DCs showed an impaired induction of the T helper type 1 immune response and a normal cell-mediated immune response. These findings provide important understanding of the immunopharmacological functions of baicalin and have ramifications for the development of therapeutic adjuvants for the treatment of DCs-related acute and chronic diseases.

Targeting a Plasmodium vivax merozoite surface protein 1 fragment to the DEC205+ dendritic cell population elicits strong antibody and T cell responses.

Event Abstract Back to Event Targeting a Plasmodium vivax merozoite surface protein 1 fragment to the DEC205+ dendritic cell population elicits strong antibody and T cell responses. Kelly N. Amorim1, Marcio M. Yamamoto1 and Silvia B. Boscardin1* 1 University of Sao Paulo, Brazil Dendritic cells (DCs) are critical in the interaction between the innate and adaptive immune systems, as they are able to process and present antigens to T and B cells. In the last decade, studies from several groups have shown that it is possible to target antigens directly to different DC populations using monoclonal antibodies (mAbs) to receptors present on the DC surface fused with the antigen of interest. An anti-DEC205 mAb has been used successfully to target antigens to the DEC205+CD8α+ DC population. The administration of low doses of the fusion mAb together with DC maturation stimuli is able to activate antigen-specific T cells and induce production of high antibody titers. Here we genetically fused the αDEC205 mAb with the 42kDa fragment derived from the Plasmodium vivax merozoite surface protein 1 (MSP1), a candidate vaccine for malaria. During Plasmodium invasion into the red blood cell, the 42kDa fragment is further cleaved into 33 and 19 kDa fragments. The 19kDa fragment is normally target for antibody response while the T cell epitopes are restricted to the 33kDa portion of the molecule. The administration of two doses of the αDEC-MSP1(42) fusion mAb in the presence of the TLR3 agonist poly I:C to either C57BL/6 or C57B10.A mice induced high anti-MSP1(19) antibody titers in the immunized mice. We also detected strong T cell immunity against a peptide present in the MSP1(33) sequence. Overall, our results indicate that targeting a Plasmodium vivax antigen to the DEC205+CD8α+ DC population improves B and T cell responses. Acknowledgements This work was supported by the Brazilian National Research Council (CNPq)/National Institutes of Science and Technology in Vaccines (INCTV, 15203*12), Sao Paulo State Research Funding Agency (FAPESP, 2007/08648-9) and by the BNP-Paribas Bank. K.N.S. Amorim received a fellowship from CNPq. Keywords: antigen targeting, Dendritic Cells, Merozoite Surface Protein 1, antibody response, T cell responses Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Translational immunology and immune intervention Citation: Amorim KN, Yamamoto MM and Boscardin SB (2013). Targeting a Plasmodium vivax merozoite surface protein 1 fragment to the DEC205+ dendritic cell population elicits strong antibody and T cell responses.. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00557 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 May 2013; Published Online: 22 Aug 2013. * Correspondence: Prof. Silvia B Boscardin, University of Sao Paulo, Sao Paulo, Brazil, sbboscardin@usp.br Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Kelly N Amorim Marcio M Yamamoto Silvia B Boscardin Google Kelly N Amorim Marcio M Yamamoto Silvia B Boscardin Google Scholar Kelly N Amorim Marcio M Yamamoto Silvia B Boscardin PubMed Kelly N Amorim Marcio M Yamamoto Silvia B Boscardin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Dendritic Cells: A Spot on Sialic Acid

Glycans decorating cell surface and secreted proteins and lipids occupy the juncture where critical host–host and host-pathogen interactions occur. The role of glycan epitopes in cell–cell and cell-pathogen adhesive events is already well-established, and cell surface glycan structures change rapidly in response to stimulus and inflammatory cues. Despite the wide acceptance that glycans are centrally implicated in immunity, exactly how glycans and their changes contribute to the overall immune response remains poorly defined. Sialic acids are unique sugars that usually occupy the terminal position of the glycan chains and may be modified by external factors, such as pathogens, or upon specific physiological cellular events. At cell surface, sialic acid-modified structures form the key fundamental determinants for a number of receptors with known involvement in cellular adhesiveness and cell trafficking, such as the Selectins and the Siglec families of carbohydrate recognizing receptors. Dendritic cells (DCs) preside over the transition from innate to the adaptive immune repertoires, and no other cell has such relevant role in antigen screening, uptake, and its presentation to lymphocytes, ultimately triggering the adaptive immune response. Interestingly, sialic acid-modified structures are involved in all DC functions, such as antigen uptake, DC migration, and capacity to prime T cell responses. Sialic acid content changes along DC differentiation and activation and, while, not yet fully understood, these changes have important implications in DC functions. This review focuses on the developmental regulation of DC surface sialic acids and how manipulation of DC surface sialic acids can affect immune-critical DC functions by altering antigen endocytosis, pathogen and tumor cell recognition, cell recruitment, and capacity for T cell priming. The existing evidence points to a potential of DC surface sialylation as a therapeutic target to improve and diversify DC-based therapies.

Identification of Lineage Relationships and Novel Markers of Blood and Skin Human Dendritic Cells

The lineage relationships and fate of human dendritic cells (DCs) have significance for a number of diseases including HIV where both blood and tissue DCs may be infected. We used gene expression profiling of human monocyte and DC subpopulations sorted directly from blood and skin to define the lineage relationships. We also compared these with monocyte-derived DCs (MDDCs) and MUTZ3 Langerhans cells (LCs) to investigate their relevance as model skin DCs. Hierarchical clustering analysis showed that myeloid DCs clustered according to anatomical origin rather than putative lineage. Plasmacytoid DCs formed the most discrete cluster, but ex vivo myeloid cells formed separate clusters of cells both in blood and in skin. Separate and specific DC populations could be determined within skin, and the proportion of CD14(+) dermal DCs (DDCs) was reduced and CD1a(+) DDCs increased during culture, suggesting conversion to CD1a(+)-expressing cells in situ. This is consistent with origin of the CD1a(+) DDCs from a local precursor rather than directly from circulating blood DCs or monocyte precursors. Consistent with their use as model skin DCs, the in vitro-derived MDDC and MUTZ3 LC populations grouped within the skin DC cluster. MDDCs clustered most closely to CD14(+) DDCs; furthermore, common unique patterns of C-type lectin receptor expression were identified between these two cell types. MUTZ3 LCs, however, did not cluster closely with ex vivo-derived LCs. We identified differential expression of novel genes in monocyte and DC subsets including genes related to DC surface receptors (including C-type lectin receptors, TLRs, and galectins).

Resveratrol Prevents Dendritic Cell Maturation in Response to Advanced Glycation End Products

Advanced glycation end products (AGEs), generated through nonenzymatic glycosylation of proteins, lipids, and nucleic acids, accumulate in the body by age thus being considered as biomarkers of senescence. Senescence is characterized by a breakdown of immunological self-tolerance, resulting in increased reactivity to self-antigens. Previous findings suggest that AGE and its receptor RAGE may be involved in the pathogenesis of autoimmune reactions through dendritic cell (DC) activation. The aim of this study was to investigate whether resveratrol, a polyphenolic antioxidant compound with tolerogenic effects on DCs, was able to counteract the mechanisms triggered by AGE/RAGE interaction on DCs. By immunochemical and cytofluorimetric assays, we demonstrated that in vitro pretreatment of human monocyte-derived DCs with resveratrol prevents DC activation in response to glucose-treated albumin (AGE-albumin). We found that resveratrol exerts an inhibitory effect on DC surface maturation marker and RAGE up-regulation in response to AGE-albumin. It also inhibited proinflammatory cytokine expression, allostimulatory ability upregulation, mitogen-activated protein (MAP) kinases, and NF-κB activation in AGE-albumin-stimulated DCs. We suggest that resveratrol, by dismantling AGE/RAGE signaling on DCs may prevent or reduce increased reactivity to self-molecules in aging.

N-acetylcysteine Administration is Associated with Reduced Activation of NF-kB and Preserves Lung Dendritic Cells Function in a Zymosan-Induced Generalized Inflammation Model

In severe sepsis, functional impairment and decreased numbers of dendritic cells (DCs) are essential reasons for immune function paralysis, secondary organ infection, and organ failure. We investigated the effects of N-acetylcysteine (NAC) administration on protecting lung DCs function in a zymosan-induced generalized inflammation (ZIGI) model. ZIGI was initiated in 80 Balb/c mice by intraperitoneal injection of zymosan (ZYM; 900mg/kg). Mice were divided into 4 groups: (1) SHAM+Vehicle; (2) SHAM+NAC; (3) ZYM+Vehicle; and (4) ZYM+NAC. NAC (100mg/kg) was administered at different time after ZYM injection. After 48h, we assessed: lung tissue pathological changes; arterial blood gas values; purified lung DCs surface expressions of MHC-II/I-A(d) and co-stimulatory molecules CD80, CD83, and CD86; lung DCs mRNA levels of chemokine receptors CCR5 and CCR7; lung DCs apoptosis; lung DCs ultrastructure by transmission electron microscopy; lung DCs NF-kB transcription factor activity; and LPS-stimulated lung DCs in vitro production of IL-12 and IL-10 were examined. NAC treatment resulted in: significant improvements in ZYM-induced lung tissue damage and impaired lung function; inhibited lung DCs ZYM-induced increased expression of MHC-II/I-A(d), CD83, and CD86, but not CD80; reduced lung DCs ZYM-induced CCR5 and CCR7 mRNA levels; suppressed ZYM-induced lung DCs apoptosis; ameliorated ZYM-induced lung DCs ultrastructural abnormalities; inhibited ZYM-induced lung DCs NF-κB activity; and enhanced lung DCs production of IL-12 and inhibited their production of IL-10. Repeated injections of NAC during the early stage of severe sepsis effectively inhibited lung DCs activation and their apoptosis, which could preserve DCs function.

Adenosine Deaminase Enhances the Immunogenicity of Human Dendritic Cells from Healthy and HIV-Infected Individuals

ADA is an enzyme implicated in purine metabolism, and is critical to ensure normal immune function. Its congenital deficit leads to severe combined immunodeficiency (SCID). ADA binding to adenosine receptors on dendritic cell surface enables T-cell costimulation through CD26 crosslinking, which enhances T-cell activation and proliferation. Despite a large body of work on the actions of the ecto-enzyme ADA on T-cell activation, questions arise on whether ADA can also modulate dendritic cell maturation. To this end we investigated the effects of ADA on human monocyte derived dendritic cell biology. Our results show that both the enzymatic and non-enzymatic activities of ADA are implicated in the enhancement of CD80, CD83, CD86, CD40 and CCR7 expression on immature dendritic cells from healthy and HIV-infected individuals. These ADA-mediated increases in CD83 and costimulatory molecule expression is concomitant to an enhanced IL-12, IL-6, TNF-α, CXCL8(IL-8), CCL3(MIP1-α), CCL4(MIP-1β) and CCL5(RANTES) cytokine/chemokine secretion both in healthy and HIV-infected individuals and to an altered apoptotic death in cells from HIV-infected individuals. Consistently, ADA-mediated actions on iDCs are able to enhance allogeneic CD4 and CD8-T-cell proliferation, globally yielding increased iDC immunogenicity. Taken together, these findings suggest that ADA would promote enhanced and correctly polarized T-cell responses in strategies targeting asymptomatic HIV-infected individuals.

Immunological effect of high mobility group box-1 protein on regulatory dendritic cells and corresponding mechanism

Objective To observe the effects of high mobility group box-1 protein ( HMGB1 ) on function of murine spleen IL-10-producing dendritic cells (DCs) subset CD11clowCD45RBhighDCs.Methods Splenic CD11clowCD45RBhighDCs and CD4 +T cells in Balb/c mice were purified by magnetic beads sorting.CD11clowCD45RBhighDCs were treated with various doses of HMGB1 (0,20,100,500ng/ml).Flow cytometry was used to determine expressions of CD11clowCD45RBhighDC surface molecules including CD40,CD80,CD86,Ⅰ-a/e and Toll-like receptor (TLR) 4.IL-10 level in CD11clow CD45RBhighDC culture supernatants was determined by ELISA method.The CD4+ T cells were divided into four groups: control group (without only treatment),untreated group (HMGB1-untreated CD11clow CD45RBhigh DCs plus CD4+T cells),high-dose HMGB1-treated group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus CD4 +T cells),high-dose HMGB1-treated + antibody 1 group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus IL-10 antibody and CD4+T cells),high-dose HMGB1-treated + antibody 2 group (500 ng/ml HMGB1-treated CD11clow CD45RBhigh DCs plus homotype IL-10 antibody and CD4 +T cells).IL-4 as well as interferon( IFN-γ) contents in CD4 + T cell culture supernatants were determined by flow cytometry.Results HMGB1 could markedly enhance the expressions of CD40,CD86 and TLR4 on CD11clowCD45RBhigh DC surface as well as level of IL-10 secreted by CD11clow CD45RBhigh DCs as compared with the non-HMGB1 treatment.Meantime,the secretion of IL-10 was HMGB1 concentration dependent.IFN-γ level in high-dose HMGB1-treated group was (279 ± 17) pg/ml,which was markedly lower than that in the untreated group [ (963 ± 11 ) pg/ml,P ＜ 0.05 ].IL-4 level in high-dose HMGB1-treated group was (372 ± 14) pg/ml,which was significantly higher than that in the untreated group [ (213 ± 10) pg/ml,P ＜0.05) \].Conclusions HMGB1 promotes IL-10 production in CD11clowCD45RBhighDCs,induces the differentiation of CD4 +T cells to Th2 cells and downregulates the immune response via activating CD11clowCD45RBhigh DCs. Key words: High mobility group proteins; T-lymphocytes, regulatory; Immunity

Induction of protective immunity against Mycobacterium tuberculosis by delivery of ESX antigens into airway dendritic cells.

As the Bacillus Calmette-Guérin (BCG) vaccine does not confer long-lasting protection against lung Mycobacterium tuberculosis infection, the development of more efficient vaccines is greatly needed. Here, we used mycobacterial low-molecular weight proteins of the 6-kDa Early Secreted Antigenic Target (ESAT-6) protein family (ESX) antigens for the evaluation of a novel vaccine delivery strategy that enables versatile in vivo targeting of antigens into specialized dendritic cell (DC) subsets. ESX antigens were genetically fused to the tetramerizing core of streptavidin (SA) to form high-affinity complexes with biotin (biot)-conjugated antibodies recognizing DC surface receptors. When directed through the CD11b or CD11c β2-integrins or diverse C-type lectins, the ESX-SA:biot-antibody complexes were efficiently captured and presented on major histocompatibility complex molecules of DCs to specific T-cell receptors. Robust ESX-specific T-cell responses were induced by immunization with as little as several picomoles of ESX-SA targeted to DC subsets. Moreover, directing of TB10.4-SA to airway CD205(+) cells enabled the induction of mucosal T-cell responses and provided significant protection against virulent M. tuberculosis.

The Neck Region of the C-type Lectin DC-SIGN Regulates Its Surface Spatiotemporal Organization and Virus-binding Capacity on Antigen-presenting Cells

The C-type lectin DC-SIGN expressed on dendritic cells (DCs) facilitates capture and internalization of a plethora of different pathogens. Although it is known that DC-SIGN organizes in nanoclusters at the surface of DCs, the molecular mechanisms responsible for this well defined nanopatterning and role in viral binding remain enigmatic. By combining biochemical and advanced biophysical techniques, including optical superresolution and single particle tracking, we demonstrate that DC-SIGN intrinsic nanoclustering strictly depends on its molecular structure. DC-SIGN nanoclusters exhibited free, Brownian diffusion on the cell membrane. Truncation of the extracellular neck region, known to abrogate tetramerization, significantly reduced nanoclustering and concomitantly increased lateral diffusion. Importantly, DC-SIGN nanocluster dissolution exclusively compromised binding to nanoscale size pathogens. Monte Carlo simulations revealed that heterogeneity on nanocluster density and spatial distribution confers broader binding capabilities to DC-SIGN. As such, our results underscore a direct relationship between spatial nanopatterning, driven by intermolecular interactions between the neck regions, and receptor diffusion to provide DC-SIGN with the exquisite ability to dock pathogens at the virus length scale. Insight into how virus receptors are organized prior to virus binding and how they assemble into functional platforms for virus docking is helpful to develop novel strategies to prevent virus entry and infection.

BODIPY-Labeled DC-SIGN-Targeting Glycodendrons Efficiently Internalize and Route to Lysosomes in Human Dendritic Cells

Glycodendrons bearing nine copies of mannoses or fucoses have been prepared by an efficient convergent strategy based on Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC). These glycodendrons present a well-defined structure and have an adequate size and shape to interact efficiently with the C-type lectin DC-SIGN. We have selected a BODIPY derivative to label these glycodendrons due to its interesting physical and chemical properties as chromophore. These BODIPY-labeled glycodendrons were internalized into dendritic cells by mean of DC-SIGN. The internalized mannosylated and fucosylated dendrons are colocalized with LAMP1, which suggests routing to lysosomes. The interaction of these glycodendrons with DC-SIGN at the surface of dendritic cells did not induce maturation of the cells. Signaling analysis by checking different cytokines indicated also the lack of induction the expression of inflammatory and noninflammatory cytokines by these second generation glycodendrons.

520. Preoperative Imaging is Concordant with Intraoperative Sentinel Node Localization and a Reduction in Missed Disease When Utilizing Receptor Targeted (CD206) Tc 99m Tilmanocept in Breast Cancer and Melanoma Patients

Background: Tc 99m tilmanocept is a fully synthetic intraoperative lymphatic mapping agent that accumulates in lymphatic tissue by binding to a mannose binding receptor (CD206) on the surface of lymph node-resident dendritic cells and macrophages. Tilmanocept is a macromolecule consisting of multiple units of DTPA and mannose, each synthetically attached to a 10 kDa dextran backbone. Tilmanocept has a diameter of about 7 nm, which is substantially smaller than current radiolabeled agents used for targeting lymphoid tissue.

An alternative allergen:adjuvant formulation potentiates the immunogenicity and reduces allergenicity of a novel subcutaneous immunotherapy product for treatment of grass‐pollen allergy

Subcutaneous specific immunotherapy (SCIT) has proven sustained clinical efficacy against allergy. The recommended regimen for SCIT is a gradual updosing over a period of weeks. Commonly, in commercial products for SCIT, the specific allergen is formulated with an adjuvant, most often in the form of aluminium hydroxide (AlOH). It has been shown that allergen-specific IgG antibodies are induced as a result of successful SIT. To investigate the possibility of optimizing the formulation of AlOH-based grass-pollen allergy vaccines for SCIT in a way that allows for shorter updosing regimens while maintaining the immunogenicity of the vaccine. Mice were immunized with various concentrations of Phleum pratense (Phl p) allergen extract and AlOH or a fixed dilution of the maintenance doses of one conventional and one alternatively formulated vaccine. The kinetics of Phl p-specific IgG antibody responses in serum and spleen T cell responses were determined. Allergenicity, measured as the ability of the formulations to activate human basophils, was also determined. In addition, human T cell responses and the expression of dendritic cell surface markers after vaccine challenge in vitro were analysed. Specific IgG antibody responses were shown to depend on the AlOH concentration, but not on the allergen concentrations. The immunogenicity of the conventional formulation and the alternative formulation was shown to be similar with regard to the in vivo-induced IgG and T cell responses. In contrast, the allergenicity of the alternative formulation was significantly reduced compared with the conventional formulation. The optimization of the formulation allows for administration of a lower dose of allergen while maintaining the immunogenicity of the product and at the same time reducing allergenicity. This study indicates that the optimization of the allergen and the adjuvant formulation could benefit the safety/efficacy profile and allow for shorter updosing.

DC-SIGN, C1q, and gC1qR form a trimolecular receptor complex on the surface of monocyte-derived immature dendritic cells

AbstractC1q modulates the differentiation and function of cells committed to the monocyte-derived dendritic cell (DC) lineage. Because the 2 C1q receptors found on the DC surface—gC1qR and cC1qR—lack a direct conduit into intracellular elements, we postulated that the receptors must form complexes with transmembrane partners. In the present study, we show that DC-SIGN, a C-type lectin expressed on DCs, binds directly to C1q, as assessed by ELISA, flow cytometry, and immunoprecipitation experiments. Surface plasmon resonance analysis revealed that the interaction was specific, and both intact C1q and the globular portion of C1q bound to DC-SIGN. Whereas IgG reduced this binding significantly, the Arg residues (162-163) of the C1q-A chain, which are thought to contribute to the C1q-IgG interaction, were not required for C1q binding to DC-SIGN. Binding was reduced significantly in the absence of Ca2+ and by preincubation of DC-SIGN with mannan, suggesting that C1q binds to DC-SIGN at its principal Ca2+-binding pocket, which has increased affinity for mannose residues. Antigen-capture ELISA and immunofluorescence microscopy revealed that C1q and gC1qR associate with DC-SIGN on blood DC precursors and immature DCs. The results of the present study suggest that C1q/gC1qR may regulate DC differentiation and function through the DC-SIGN–mediated induction of cell-signaling pathways.

Synthesis of Novel Mannoside Glycolipid Conjugates for Inhibition of HIV-1 Trans-Infection

Mannose-binding lectins, such as dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN), are expressed at the surface of human dendritic cells (DCs) that capture and transmit human immunodeficiency virus type-1 (HIV-1) to CD4(+) cells. With the goal of reducing viral trans-infection by targeting DC-SIGN, we have designed a new class of mannoside glycolipid conjugates. We report the synthesis of amphiphiles composed of a mannose head, a hydrophilic linker essential for solubility in aqueous media, and a lipid chain of variable length. These conjugates presented unusual properties based on a cooperation between the mannoside head and the lipid chain, which enhanced the affinity and decreased the need for multivalency. With an optimal lipid length, they exhibited strong binding affinity for DC-SIGN (K(d) in the micromolar range) as assessed by surface plasmon resonance. The most active molecules were branched trimannoside conjugates, able to inhibit the interaction of the HIV-1 envelope with DCs, and to drastically reduce trans-infection of HIV-1 mediated by DCs (IC(50s) in the low micromolar range). This new class of compounds may be of potential use for prevention of HIV-1 dissemination, and also of infection by other DC-SIGN-binding human pathogens.

Human monocyte-derived dendritic cells from leukoreduction system chambers after plateletpheresis are functional in an in vitro co-culture assay with intestinal epithelial cells

The dendritic cells (DC) found in the intestine are involved both in the maintenance of tolerance towards commensal microbiota, and in the generation of protective immune responses against pathogens, thus contributing to gut immune homeostasis.There is an increasing interest in the use of lactic acid bacteria (LAB) as probiotics; among their beneficial effects we highlight the modulation of the immune system which is one of their fundamental properties. As these effects are strain-dependent, it is important to have in vitro systems that include DC and intestinal epithelial cells (IEC), which are crucial for intestinal homeostasis, to identify candidates by means of bacterial screening. Obtaining enough human cells, necessary to simultaneously test several bacteria, is a major challenge for researchers. In this study we analyzed the usefulness of the cellular fraction retained in leukoreduction system chambers following plateletpheresis (PP) as a source of DC. We compared the capacity of peripheral blood mononuclear cells (PBMC) from buffy coats (BC) or PP to generate DC using a short differentiation protocol. The functionality of the DC obtained was analyzed in co-cultures together with intestinal epithelial HT-29 cells, stimulating with LPS alone or with two LAB commonly used in the food industry, Streptococcus thermophilus and Lactobacillus delbrueckii. DC surface markers CD86, HLA-DR and cytokine production were measured. The behavior of DC derived from PP was similar to the behavior observed for DC derived from BC. When we tested the response of DC to bacteria, we found significant differences in cytokine secretion, especially for IL-10, suggesting that the system has the ability to discriminate LAB with different immunomodulatory properties. We also found that DC derived from both sources displayed a similar ability to phagocyte bacteria.In conclusion, we hereby propose a modification of the two-day protocol for obtaining human DC previously described, using PP as an alternative source of PBMC, to be used in co-culture systems with IEC. The novelty of this protocol is the combination of the blood monocyte source with a simple and fast differentiation method to obtain DC, and their use in a combined culture with IEC and LAB to model microbial-host interaction. Since the initial PP volume is ten times lower than that of BC, the use of PP minimizes biological residue generation and reagent consumption. In addition, monocyte-derived DC from PP were suitable for use in co-culture assays as a first screening step to study the immunomodulatory properties of LAB.

Neisseria gonorrhoeae Suppresses Dendritic Cell-Induced, Antigen-Dependent CD4 T Cell Proliferation

Neisseria gonorrhoeae is the second most common sexually transmitted bacterial pathogen worldwide. Diseases associated with N. gonorrhoeae cause localized inflammation of the urethra and cervix. Despite this inflammatory response, infected individuals do not develop protective adaptive immune responses to N. gonorrhoeae. N. gonorrhoeae is a highly adapted pathogen that has acquired multiple mechanisms to evade its host's immune system, including the ability to manipulate multiple immune signaling pathways. N. gonorrhoeae has previously been shown to engage immunosuppressive signaling pathways in B and T lymphocytes. We have now found that N. gonorrhoeae also suppresses adaptive immune responses through effects on antigen presenting cells. Using primary, murine bone marrow-derived dendritic cells and lymphocytes, we show that N. gonorrhoeae-exposed dendritic cells fail to elicit antigen-induced CD4+ T lymphocyte proliferation. N. gonorrhoeae exposure leads to upregulation of a number of secreted and dendritic cell surface proteins with immunosuppressive properties, particularly Interleukin 10 (IL-10) and Programmed Death Ligand 1 (PD-L1). We also show that N. gonorrhoeae is able to inhibit dendritic cell- induced proliferation of human T-cells and that human dendritic cells upregulate similar immunosuppressive molecules. Our data suggest that, in addition to being able to directly influence host lymphocytes, N. gonorrhoeae also suppresses development of adaptive immune responses through interactions with host antigen presenting cells. These findings suggest that gonococcal factors involved in host immune suppression may be useful targets in developing vaccines that induce protective adaptive immune responses to this pathogen.

A Theory of Germinal Center B Cell Selection, Division, and Exit

High-affinity antibodies are generated in germinal centers in a process involving mutation and selection of B cells. Information processing in germinal center reactions has been investigated in a number of recent experiments. These have revealed cell migration patterns, asymmetric cell divisions, and cell-cell interaction characteristics, used here to develop a theory of germinal center B cell selection, division, and exit (the LEDA model). According to this model, B cells selected by T follicular helper cells on the basis of successful antigen processing always return to the dark zone for asymmetric division, and acquired antigen is inherited by one daughter cell only. Antigen-retaining B cells differentiate to plasma cells and leave the germinal center through the dark zone. This theory has implications for the functioning of germinal centers because compared to previous models, high-affinity antibodies appear one day earlier and the amount of derived plasma cells is considerably larger.

IgG keeps virulent Salmonella from evading dendritic cell uptake

Dendritic cells (DCs) are phagocytic professional antigen-presenting cells that can prime naive T cells and initiate anti-bacterial immunity. However, several pathogenic bacteria have developed virulence mechanisms to impair DC function. For instance, Salmonella enterica serovar Typhimurium can prevent DCs from activating antigen-specific T cells. In addition, it has been described that the Salmonella Pathogenicity Island 1 (SPI-1), which promotes phagocytosis of bacteria in non-phagocytic cells, can suppress this process in DCs in a phosphatidylinositol 3-kinase (PI3K) -dependent manner. Both mechanisms allow Salmonella to evade host adaptive immunity. Recent studies have shown that IgG-opsonization of Salmonella can restore the capacity of DCs to present antigenic peptide-MHC complexes and prime T cells. Interestingly, T-cell activation requires Fcγ receptor III (FcγRIII) expression over the DC surface, suggesting that this receptor could counteract both antigen presentation and phagocytosis evasion by bacteria. We show that, despite IgG-coated Salmonella retaining its capacity to secrete anti-capture proteins, DCs are efficiently capable of engulfing a large number of IgG-coated bacteria. These results suggest that DCs employ another mechanism to engulf IgG-coated Salmonella, different from that used for free bacteria. In this context, we noted that DCs do not employ PI3K, actin cytoskeleton or dynamin to capture IgG-coated bacteria. Likewise, we observed that the capture is an FcγR-independent mechanism. Interestingly, these internalized bacteria were rapidly targeted for degradation within lysosomal compartments. Hence, our results suggest a novel mechanism in DCs that does not employ PI3K/actin cytoskeleton/dynamin/FcγRs to engulf IgG-coated Salmonella, is not affected by anti-capture SPI-1-derived effectors and enhances DC immunogenicity, bacterial degradation and antigen presentation.