Antigen-presenting cells in allergy

In Silico Design of a New Epitope-Based Vaccine against Grass Group 1 Allergens

Allergic diseases are a global public health problem that affects up to 30% of the population in industrialized societies. More than 40% of allergic patients suffer from grass pollen allergy. Grass pollen allergens of group 1 and group 5 are the major allergens, since they induce allergic reactions in patients at high rates. In this study, we used immunoinformatic approaches to design an effective epitope-based vaccine against the grass group 1 allergens. After the alignment of all known pollen T-cell and B-cell epitopes from pollen allergens available in the public databases, the epitope GTKSEVEDVIPEGWKADTSY was identified as the most suitable for further analyses. The target sequence was subjected to immunoinformatics analyses to predict antigenic T-cell and B-cell epitopes. Population coverage analysis was performed for CD8+ and CD4+ T-cell epitopes. The selected T-cell epitopes (VEDVIPEGW and TKSEVEDVIPEGWKA) covered 78.87% and 98.20% of the global population and 84.57% and 99.86% of the population of Europe. Selected CD8+, CD4+ T-cell and B-cell epitopes have been validated by molecular docking analysis. CD8+ and CD4+ T-cell epitopes showed a very strong binding affinity to major histocompatibility complex (MHC) class I (MHC I) molecules and MHC class II (MHC II) molecules with global energy scores of -72.1 kcal/mol and -89.59 kcal/mol, respectively. The human IgE-Fc (PDB ID 4J4P) showed a lower affinity with B-cell epitope (ΔG = -34.4 kcal/mol), while the Phl p 2-specific human IgE Fab (PDB ID 2VXQ) had the lowest binding with the B-cell epitope (ΔG = -29.9 kcal/mol). Our immunoinformatics results demonstrated that the peptide GTKSEVEDVIPEGWKADTSY could stimulate the immune system and we performed ex vivo tests showed that the investigated epitope activates T cells isolated from patients with grass pollen allergy, but it is not recognized by IgE antibodies specific for grass pollen allergens. This confirms the importance of such studies to establish universal epitopes to serve as a basis for developing an effective vaccine against a particular group of allergens. Further in vivo studies are needed to validate the effectiveness of such a vaccine against grass pollen allergens.

Mechanistic insights into silica nanoparticle-allergen interactions on antigen presenting cell function in the context of allergic reactions

The incorporation of nanomaterials into consumer products has substantially increased in recent years, raising concerns about their safety. The inherent physicochemical properties of nanoparticles allow them to cross epithelial barriers and gain access to immunocompetent cells. Nanoparticles in cosmetic products can potentially interact with environmental allergens, forming a protein corona, and together penetrate through damaged skin. Allergen-nanoparticle interactions may influence the immune response, eventually resulting in an adverse or beneficial outcome in terms of allergic reactivity. This study determines the impact of silica nanoparticle-allergen interactions on allergic sensitization by studying the major molecular mechanisms affecting allergic responses. The major birch pollen allergen Bet v 1 was chosen as a model allergen and the birch pollen extract as a comparator. Key events in immunotoxicity including allergen uptake, processing, presentation, expression of costimulatory molecules and cytokine release were studied in human monocyte-derived dendritic cells. Using an in vivo sensitization model, murine Bet v 1-specific IgG and IgE levels were monitored. Upon the interaction of allergens with silica nanoparticles, we observed an enhanced uptake of the allergen by macropinocytosis, improved proteolytic processing, and presentation concomitant with a propensity to increase allergen-specific IgG2a and decrease IgE antibody levels. Together, these events suggest that upon nanoparticle interactions the immune response is biased towards a type 1 inflammatory profile, characterized by the upregulation of T helper 1 (Th1) cells. In conclusion, the interaction of the birch pollen allergen with silica nanoparticles will not worsen allergic sensitization, a state of type 2-inflammation, but rather seems to decrease it by skewing towards a Th1-dominated immune response.

Cell-penetrating albumin enhances the sublingual delivery of antigens through macropinocytosis

Innovations in oral immunotherapy have greatly advanced the therapeutic control of allergies. However, these therapeutic effects suffer from the fact that the amount of antigen delivered to antigen-presenting cells is limited given the formulations that are currently available. We recently designed a cell-penetrating albumin and found that this modified albumin enters cells via the induction of macropinocytosis. Herein, we report on a novel system for delivering antigens based on cell-penetrating albumin-inducible macropinocytosis that allows larger amounts of antigens to be delivered to antigen-presenting cells. A treatment with cell-penetrating albumin significantly increased the permeability of ovalbumin (45 kDa) or dextran (2000 kDa) on monolayers derived from human oral squamous carcinoma cells. Flow cytometric analyses showed that the cell-penetrating albumin treatment resulted in a significant elevation in the amount of dextran that was delivered to two types of antigen-presenting cells. Finally, mice that had been sensitized by Japanese cedar pollen extract (JCPE) and cell-penetrating albumin showed a decline in the frequency of nose-rubbing against a subsequent intranasal administration of JCPE. These findings suggest that the sublingual administration of cell-penetrating albumin efficiently delivers antigens to antigen-presenting cells via the induction of macropinocytosis, resulting in an enhancement in the therapeutic effect of sublingual immunotherapy.

Granulocyte Macrophage-Colony Stimulating Factor Produces a Splenic Subset of Monocyte-Derived Dendritic Cells That Efficiently Polarize T Helper Type 2 Cells in Response to Blood-Borne Antigen

Dendritic cells (DCs) are key antigen-presenting cells that prime naive T cells and initiate adaptive immunity. Although the genetic deficiency and transgenic overexpression of granulocyte macrophage-colony stimulating factor (GM-CSF) signaling were reported to influence the homeostasis of DCs, the in vivo development of DC subsets following injection of GM-CSF has not been analyzed in detail. Among the treatment of mice with different hematopoietic cytokines, only GM-CSF generates a distinct subset of XCR1^-33D1^- DCs which make up the majority of DCs in the spleen after three daily injections. These GM-CSF-induced DCs (GMiDCs) are distinguished from classical DCs (cDCs) in the spleen by their expression of CD115 and CD301b and by their superior ability to present blood-borne antigen and thus to stimulate CD4⁺ T cells. Unlike cDCs in the spleen, GMiDCs are exceptionally effective to polarize and expand T helper type 2 (Th2) cells and able to induce allergic sensitization in response to blood-borne antigen. Single-cell RNA sequencing analysis and adoptive cell transfer assay reveal the sequential differentiation of classical monocytes into pre-GMiDCs and GMiDCs. Interestingly, mixed bone marrow chimeric mice of Csf2rb^+/+ and Csf2rb^-/- demonstrate that the generation of GMiDCs necessitates the cis expression of GM-CSF receptor. Besides the spleen, GMiDCs are generated in the CCR7-independent resident DCs of the LNs and in some peripheral tissues with GM-CSF treatment. Also, small but significant numbers of GMiDCs are generated in the spleen and other tissues during chronic allergic inflammation. Collectively, our present study identifies a splenic subset of CD115^hiCD301b⁺ GMiDCs that possess a strong capacity to promote Th2 polarization and allergic sensitization against blood-borne antigen.

CpG Oligodeoxynucleotides Attenuate OVA-Induced Allergic Airway Inflammation via Suppressing JNK-Mediated Endoplasmic Reticulum Stress

Purpose

CpG-ODN has been found to attenuate allergic airway inflammation in our previous study. Here, we aimed to further investigate whether CpG-ODN exerts such effect via regulating endoplasmic reticulum (ER) stress and revealed the underlying mechanism.

Methods

Five-week-old C57BL/6 mice were randomly grouped and treated with or without CpG-ODN or/and SP600125. Meantime, RAW264.7 cells were used to investigate the effect of CpG-ODN on OVA-induced ER stress in vitro. The cellularity of bronchoalveolar lavage fluid (BALF) was classified and counted after Wright-Giemsa staining. HE and PAS staining methods were applied to analyze airway inflammation. The protein levels of IL-4, IL-5, IL-13, p-JNK, JNK, CHOP, XBP1, ATF6α and GRP78 in lung tissues were detected by Western blotting. Correspondingly, the ER stress markers were detected by Western blotting and immunofluorescence in RAW264.7 cells.

Results

In OVA-induced allergic airway inflammation, CpG-ODN significantly suppressed inflammatory cells infiltration, goblet cell hyperplasia and the protein expression of Th2 cytokines. Moreover, OVA exposure strongly increased the activation of ER stress with higher protein expressions of CHOP, XBP1, ATF6α and GRP78. However, these OVA-induced increase of ER stress markers were markedly suppressed by CpG-ODN treatment. In addition, exposure to OVA significantly increased the phosphorylation of JNK, which was significantly reduced by CpG-ODN treatment. Remarkably, single treatment of SP600125, an antagonist of JNK, functioned similarly as CpG-ODN in mitigating allergic airway inflammation and suppressing OVA-induced activation of ER stress; however, no significant synergistic effect was evidenced by combined treatment of SP600125 and CpG-ODN. Furthermore, in OVA-stimulated RAW264.7 cells, we also found that OVA stimulation increased the expressions of ER stress markers, and CpG-ODN significantly reduced their expression levels via suppressing the phosphorylation of JNK.

Conclusion

These results indicated that CpG-ODN mitigates allergic airway inflammation via suppressing the activation of JNK-medicated ER stress.

Therapeutic efficacy of pulmonary live tuberculosis vaccines against established asthma by subverting local immune environment

Background

Substantial recent advances in the comprehension of the molecular and cellular mechanisms behind asthma have evidenced the importance of the lung immune environment for disease outcome, making modulation of local immune responses an attractive therapeutic target against this pathology. Live attenuated mycobacteria, such as the tuberculosis vaccine BCG, have been classically linked with a type 1 response, and proposed as possible modulators of the type 2 response usually associated with asthma.

Methods

In this study we used different acute and chronic murine models of asthma to investigate the therapeutic efficacy of intranasal delivery of the live tuberculosis vaccines BCG and MTBVAC by regulating the lung immune environment associated with airway hyperresponsiveness (AHR).

Findings

Intranasal administration of BCG, or the novel tuberculosis vaccine candidate MTBVAC, abrogated AHR-associated hallmarks, including eosinophilia and lung remodeling. This correlated with the re-polarization of allergen-induced M2 macrophages towards an M1 phenotype, as well as with the induction of a strong allergen-specific Th1 response. Importantly, vaccine treatment was effective in a scenario of established chronic asthma where a strong eosinophil infiltration was already present prior to immunization. We finally compared the nebulization efficiency of clinical formulations of MTBVAC and BCG using a standard commercial nebulizer for potential aerosol application.

Interpretation

Our results demonstrate that pulmonary live tuberculosis vaccines efficiently revert established asthma in mice. These data support the further exploration of this approach as potential therapy against asthma.

Funding

Spanish Ministry of Science [grant numbers: BIO2014-5258P, RTI2018-097625-B-I00], Instituto de Salud Carlos III, Gobierno de Aragón/Fondo Social Europeo, University of Zaragoza [grant number: JIUZ-2018-BIO-01].

Non-Reflex Defense Mechanisms of Upper Airway Mucosa: Possible Clinical Application

The sinonasal mucosa has an essential role in defense mechanisms of the upper respiratory tract. The innate immune system presents the primary defense against noxious microorganisms followed by induction of the adaptive immune mechanisms as a consequence of the presence of pathogens. This well-known activation of adaptive immune system in response to presence of the antigen on mucosal surfaces is now broadly applicated in vaccinology research. Prevention of infectious diseases belongs to substantial challenges in maintaining the population health. Non-invasive, easily applicable mucosal vaccination purposes various research opportunities that could be usable in daily practice. However, the existence of multiple limitations such as rapid clearance of vaccine from nasal mucosa by means of mucociliary transport represents a great challenge in development of safe and efficient vaccines. Here we give an updated view on nasal functions with focus on nasal mucosal immunity and its potential application in vaccination in nearly future.

DK-1108 exerts anti-inflammatory activity against phorbol 12-myristate 13-acetate-induced inflammation and protective effect against OVA-induced allergic asthma

There is an increasing interest in natural products and their derivatives with therapeutic benefits and less side effects compared to steroid therapy. Benzofuran derivatives display biological effects including anti-inflammatory effects. The present study aims to investigate whether (3-(7-methoxy-2-p-tolyl benzofuran-5-yl) propan-1-ol) (DK-1108), new synthetic benzofuran compound exerts anti-asthmatic effects in vitro and in vivo. DK-1108 strongly reduced the production of inflammatory mediators, cytokines and chemokines in RAW264.7 and A549 cells. DK-1108 significantly regulated the levels of AKT/MAPKs/c-Jun activation, AP-1 luciferase activity and ICAM-1 expression. Furthermore, DK-1108 effectively suppressed the adhesion of A549 and EOL-1 cells. In OVA-induced asthmatic mice, DK-1108 decreased the levels of IL-5/IL-13/IgE production, eosinophils/macrophages influx, ICAM-1/MCP-1 expression, mucus secretion and airway hyperresponsiveness (AHR). These effects of DK-1108 were accompanied by downregulation of MAPKs activation. Therefore, we suggest that DK-1108 exerts protective effect against airway inflammation and mucus overproduction, and therefore could be valuable therapeutic agent for treatment in asthma.

Phthalate Exposure and Long-Term Epigenomic Consequences: A Review

Phthalates are esters of phthalic acid which are used in cosmetics and other daily personal care products. They are also used in polyvinyl chloride (PVC) plastics to increase durability and plasticity. Phthalates are not present in plastics by covalent bonds and thus can easily leach into the environment and enter the human body by dermal absorption, ingestion, or inhalation. Several in vitro and in vivo studies suggest that phthalates can act as endocrine disruptors and cause moderate reproductive and developmental toxicities. Furthermore, phthalates can pass through the placental barrier and affect the developing fetus. Thus, phthalates have ubiquitous presence in food and environment with potential adverse health effects in humans. This review focusses on studies conducted in the field of toxicogenomics of phthalates and discusses possible transgenerational and multigenerational effects caused by phthalate exposure during any point of the life-cycle.

The epigenetic face of lupus: Focus on antigen-presenting cells

In recent years, epigenetic mechanisms became widely known due to their ability to regulate and maintain physiological processes such as cell growth, development, differentiation and genomic stability. When dysregulated, epigenetic mechanisms, may introduce gene expression changes and disturbance in immune homeostasis leading to autoimmune diseases. Systemic lupus erythematosus (SLE), the most extensively studied autoimmune disorder, has already been correlated with epigenetic modifications, especially in T cells. Since these cell rely on antigen presentation, it may be assumed that erroneous activity of antigen-presenting cells (APCs), culminates in T cell abnormalities. In this review we summarize and discuss the epigenetic modifications in SLE affected APCs, with the focus on dendritic cells (DCs), B cells and monocytes. Unravelling this aspect of SLE pathogenesis, might result in identification of new disease biomarkers and putative therapeutic approaches.

Zerumbone from Zingiber zerumbet inhibits innate and adaptive immune responses in Balb/C mice

Zerumbone exhibited various biological properties including in vitro immunosuppressive effects. However, its modulatory activity on the immune responses in experimental animal model is largely unknown. This investigation was conducted to explore the effects of daily treatment of zerumbone (25, 50, and 100 mg/kg) isolated from Zingiber zerumbet rhizomes for 14 days on various cellular and humoral immune responses in Balb/C mice. For measurement of adaptive immunity, sheep red blood cells (sRBC) were used to immunize the mice on day 0 and orally fed with similar doses of zerumbone for 14 days. The effects of zerumbone on phagocytosis, nitric oxide (NO) release, myeloperoxidase (MPO) activity, proliferation of T and B cells, lymphocyte phenotyping, cytokines release in serum by activated T cells, delayed type hypersensitivity (DTH) and immunoglobulins production (IgG and IgM) were investigated. Zerumbone downregulated the engulfment of E. coli by peritoneal macrophages and the release of NO and MPO in a concentration-dependent manner. Zerumbone showed significant and concentration-dependent suppression of T and B lymphocytes proliferation and inhibition of the Th1 and Th2 cytokines release. At higher concentrations of zerumbone, the % expression of CD4⁺ and CD8⁺ in splenocytes was significantly inhibited. Zerumbone also concentration-dependently demonstrated strong suppression on sRBC-triggered swelling of mice paw in DTH. Substantial suppression of anti-sRBC immunoglobulins antibody titer was noted in immunized and zerumbone-treated mice in a concentration-dependent manner. The potent suppressive effects of zerumbone on the immune responses suggest that zerumbone can be a potential candidate for development of immunosuppressive agent.

PEGylated liposomes: immunological responses

A commonly held view is that nanocarriers conjugated to polyethylene glycol (PEG) are non-immunogenic. However, many studies have reported that unexpected immune responses have occurred against PEG-conjugated nanocarriers. One unanticipated response is the rapid clearance of PEGylated nanocarriers upon repeat administration, called the accelerated blood clearance (ABC) phenomenon. ABC involves the production of antibodies toward nanocarrier components, including PEG, which reduces the safety and effectiveness of encapsulated therapeutic agents. Another immune response is the hypersensitivity or infusion reaction referred to as complement (C) activation-related pseudoallergy (CARPA). Such immunogenicity and adverse reactivities of PEGylated nanocarriers may be of potential concern for the clinical use of PEGylated therapeutics. Accordingly, screening of the immunogenicity and CARPA reactogenicity of nanocarrier-based therapeutics should be a prerequisite before they can proceed into clinical studies. This review presents PEGylated liposomes, immunogenicity of PEG, the ABC phenomenon, C activation and lipid-induced CARPA from a toxicological point of view, and also addresses the factors that influence these adverse interactions with the immune system.

Immunosuppression in early postnatal days induces persistent and allergen-specific immune tolerance to asthma in adult mice

Bronchial asthma is a chronic airway inflammatory condition with high morbidity, and effective treatments for asthma are limited. Allergen-specific immunotherapy can only induce peripheral immune tolerance and is not sustainable. Exploring new therapeutic strategies is of great clinical importance. Recombinant adenovirus (rAdV) was used as a vector to make cells expressing cytotoxic T lymphocyte-associated antigen-4-immunoglobulin (CTLA4Ig) a soluble CTLA4 immunoglobulin fusion protein. Dendritic cells (DCs) were modified using the rAdVs together with allergens. Then these modified DCs were transplanted to mice before allergen sensitization. The persistence and specificity of immune tolerance were evaluated in mice challenged with asthma allergens at 3 and 7 months. DCs modified by CTLA4Ig showed increased IL-10 secretion, decreased IL-12 secretion, and T cell stimulation in vitro. Mice treated with these DCs in the early neonatal period developed tolerance against the allergens that were used to induce asthma in the adult stage. Asthma symptoms, lung damage, airway reactivity, and inflammatory response all improved. Humoral immunity indices showed that this therapeutic strategy strongly suppressed mice immune responses and was maintained for as long as 7 months. Furthermore, allergen cross-sensitization and challenge experiments demonstrated that this immune tolerance was allergen-specific. Treatment with CTLA4Ig modified DCs in the early neonatal period, inducing persistent and allergen-specific immune tolerance to asthma in adult mice. Our results suggest that it may be possible to develop a vaccine for asthma.

Basophils are not the key antigen-presenting cells in allergic patients

BACKGROUND

Recent data obtained in mouse models have initiated a controversy whether basophils are the key antigen-presenting cells (APCs) in allergy. Here, we investigate whether basophils are of importance for the presentation of allergen and the induction of T cell proliferation in allergic patients.

METHODS

T cells, basophils, and APCs depleted of basophils were purified from allergic patients. Co-culture systems based on purified major allergens were established to study allergen-specific T cell responses using proliferation assays.

RESULTS

Only co-cultures of T cells with APCs depleted of basophils but not with basophils proliferated in response to allergen. Even addition of IL-3 to T cell-basophil co-cultures failed to induce allergen-specific T cell proliferation.

CONCLUSIONS

Our data demonstrate by classical in vitro proliferation assays that basophils are not key antigen-presenting cells that promote T cell proliferation in secondary immune responses to allergen in allergic patients.

Dendritic cells with lymphocyte-stimulating activity differentiate from human CD133 positive precursors

CD133 is a hallmark of primitive myeloid progenitors. We have addressed whether human cord blood cells selected for CD133 can generate dendritic cells, and Langerhans cells in particular, in conditions that promote that generation from CD34(+) progenitors. Transforming growth factor-β1 (TGF-β1) and anti-TGF-β1 antibody, respectively, were added in some experiments. With TGF-β, monocytoid cells were recognized after 7 days. Immunophenotypically immature dendritic cells were present at day 14. After 4 more days, the cells expressed CD54, CD80, CD83, and CD86 and were potent stimulators in mixed lymphocyte reaction; part of the cells expressed CD1a and langerin, but not Birbeck granules. Without TGF-β, only a small fraction of cells acquired a dendritic shape and expressed the maturation-related antigens, and lymphocytes were poorly stimulated. With anti-TGF-β, the cell growth was greatly hampered, CD54 and langerin were never expressed, and lymphocytes were stimulated weakly. In conclusion, CD133(+) progenitors can give rise in vitro, through definite steps, to mature, immunostimulatory dendritic cells with molecular features of Langerhans cells, although without Birbeck granules. Addition of TGF-β1 helps to stimulate cell growth and promotes the acquisition of mature immunophenotypical and functional features. Neither langerin nor Birbeck granules proved indispensable for lymphocyte stimulation.

Natural killer cells in atopic and autoimmune diseases of the skin

Natural killer (NK) cells are best known for their ability to recognize and kill tumor cells and virally infected cells and for their ability to produce large amounts of some cytokines, such as IFN-gamma. Recent research has substantially expanded our view on the function of NK cells in the immune system in health and disease. In addition to the better-studied functions in cancer and autoimmunity, contributions from NK cells to allergies and various skin diseases have emerged. We briefly recount the traditional NK cell functions before focusing on their roles in atopic dermatitis, psoriasis, alopecia areata, and pemphigus vulgaris. Although this field is still developing, strong data are available that indicate NK cell involvement. In patients with allergic diseases, the production of T(H)2 cytokines by NK cells contributes to the known immune deviation. In patients with psoriasis, their pathophysiologic role seems to be especially the production of IFN-gamma. NK cell overactivation can be found in patients with alopecia areata and pemphigus vulgaris. Many details are still unclear; however, we believe that there is solid evidence that NK cells actively participate in a number of diseases that have not been traditionally linked to this type of lymphocyte.

Innate immunity in the paranasal sinuses: a review of nasal host defenses

BACKGROUND

Chronic rhinosinusitis (CRS) is a common inflammatory disorder of the paranasal sinuses. An abnormal host response to common bacterial or fungal pathogens is thought to be an important factor in the disease process. Host sinonasal epithelium plays an important role in initially recognizing the presence of microbes and responding by increasing production of antimicrobial peptides and cytokines, with recruitment of phagocytes and lymphocytes of the adaptive immune system, to eliminate the infection. Recently, the innate immune system and its complex interplay with the adaptive immune system are increasingly being recognized as important in the pathogenesis of chronic inflammatory diseases such as asthma and CRS.

METHODS

Review of recent findings on innate immunity in the pathogenesis of CRS.

RESULTS

New areas of research into potentially novel therapies for CRS are highlighted in this review, with emphasis on toll-like receptors, antimicrobial peptides (cathelicidins and defensins), and surfactant proteins.

CONCLUSION

This review provides an overview of innate immunity in the sinonasal tract and discusses potential use of innate immune peptides as treatments against fungi, biofilms, and superantigens in CRS.

Dendritic cells, but not macrophages or B cells, activate major histocompatibility complex class II-restricted CD4+ T cells upon immune-complex uptake in vivo

Professional antigen-presenting cells (APC) are able to process and present exogenous antigen leading to the activation of T cells. Antigen-immunoglobulin (Ig)G complexes (IC) are much more efficiently processed and presented than soluble antigen. Dendritic cells (DC) are known for their ability to take up and process immune complex (IC) via FcgammaR, and they have been shown to play a crucial role in IC-processing onto major histocompatibility complex (MHC) class I as they contain a specialized cross-presenting transport system required for MHC class I antigen-processing. However, the MHC class II-antigen-processing pathway is distinct. Therefore various other professional APC, like macrophages and B cells, all displaying FcgammaR, are thought to present IC-delivered antigen in MHC class II. Nonetheless, the relative contribution of these APC in IC-facilitated antigen-presentation for MHC class II in vivo is not known. Here we show that, in mice, both macrophages and DC, but not B cells, efficiently capture IC. However, only DC, but not macrophages, efficiently activate antigen-specific MHC class II restricted CD4(+) T cells. These results indicate that mainly DC and not other professional APC, despite expressing FcgammaR and MHC class II, contribute significantly to IC-facilitated T cell activation in vivo under steady-state conditions.

Functional and transcriptional profiling of MUTZ-3, a myeloid cell line acting as a model for dendritic cells

The incidence of allergy is steadily increasing, but the molecular mechanisms involved in the allergic immune response are still not fully understood. In particular, further investigations focusing on dendritic cells, which are central in orchestrating the immune response, are needed. The objective of this study was to investigate the ability of myeloid leukaemia-derived cell lines, such as KG-1, THP-1 and MUTZ-3, to serve as in vitro models for dendritic cells. The ability of these cell lines to mature into functional dendritic cells, expressing costimulatory molecules, was assessed by functional and transcriptional profiling and compared with that of monocyte-derived dendritic cells, which are now used as a standard source of dendritic cells. High-density microarray analysis was utilized to study the transcriptional activity and kinetics of activation of the differentiated MUTZ-3 cell line, in response to a cocktail of inflammatory cytokines. The data obtained clearly demonstrate that MUTZ-3 cells have the ability to induce antigen-independent proliferation in CD4(+) CD45RA(+) T cells, whereas KG-1 and THP-1 only induced a marginal response. Furthermore, MUTZ-3 displayed the phenotypic and transcriptional profiles of immature dendritic cells, after differentiation with granulocyte-macrophage colony-stimulating factor and interleukin-4. Upon activation with inflammatory cytokines, MUTZ-3 matured phenotypically and exhibited a gene induction similar to that of monocyte-derived dendritic cells. This delineation of the cellular and transcriptional activity of MUTZ-3, in response to maturational stimuli, demonstrates the significance of this cell line as a model for functional studies of inflammatory responses.

Role of staphylococcal superantigen in atopic dermatitis: influence on keratinocytes

Staphylococcus aureus may perform an crucial function in atopic dermatitis (AD), via the secretion of superantigens, including staphylococcal enterotoxins (SE) A or B, and toxic shock syndrome toxin-1 (TSST-1). Dysregulated cytokine production by keratinocytes (KCs) upon exposure to staphylococcal superantigens (SsAgs) may be principally involved in the pathophysiology of AD. We hypothesized that lesional KCs from AD may react differently to SsAgs compared to nonlesional skin or normal skin from nonatopics. We conducted a comparison of HLA-DR or CD1a expression in lesional skin as opposed to that in nonlesional or normal skin by immunohistochemistry (IHC). We also compared, using ELISA, the levels of IL-1alpha, IL-1beta, and TNF-alpha secreted by cultured KCs from lesional, nonlesional, and normal skin, after the addition of SEA, SEB and TSST-1. IHC revealed that both HLA-DR and CD1a expression increased significantly in the epidermis of lesional skin versus nonlesional or normal skin in quite a similar manner. IL-1alpha, IL-1beta, and TNF-alpha secretion was also significantly elevated in the cultured KCs from lesional skin after the addition of SsAgs. Our results indicated that KCs from lesional skin appear to react differently to SsAgs and increased proinflammatory cytokine production in response to SsAgs may contribute to the pathogenesis of AD.

Anti-P-selectin lectin-EGF domain monoclonal antibody inhibits the maturation of human immature dendritic cells

Dendritic cells (DCs) are professional antigen-presenting cells with the ability to initiate primary T cell responses. While it is well known that inflammatory stimuli induce the functional maturation of immature DCs, whether adhesion molecule selectins regulate DC maturation is poorly understood. Using anti-P-selectin lectin-EGF domain monoclonal antibody (PsL-EGFmAb) that blocks the adhesion of P-, E-, and L-selectin, we demonstrate herein that selectins play important role in stimulating functional maturation of immature DCs. Immature DCs are generated from human cord blood CD34+ hematopoietic stem/progenitor cells that were cultured in the presence of stem cell factor, Fms-like tyrosine-kinase-3 ligand, granulocyte-macrophage colony stimulating factor, and transform growth factor-beta1. When stimulated with tumor necrosis factor-alpha (TNF-alpha), immature DCs differentiated into mature DCs, producing increased levels of costimulatory molecules and interleukin (IL)-12 and obtaining the ability to potently activate naïve T cells. Interestingly, in contrast to mature DCs derived from TNF-alpha-induced immature DC cultures without PsL-EGFmAb, immature DCs treated with PsL-EGFmAb for 7 days were completely blocked their maturation, as evidenced by decreased expression of costimulatory molecules CD80, CD86, and CD83, inhibited production of IL-12, and inability to activate naïve T cells in vitro. Thus, blockade of selectins using PsL-EGFmAb will prove to be a valuable tool for the study of the molecular mechanisms of DC maturation, as well as for the prevention and treatment of DC-mediated autoimmunity.

The role of immunoglobulin E and immune inflammation: implications in allergic rhinitis

Immunoglobulin E (IgE) plays a critical role in the allergic inflammatory process in diseases such as allergic rhinitis. Cross-linking IgE bound to its receptor on cells by multivalent allergens initiates a chain of events resulting in allergic immune responses. Mast cells and basophils are involved in the early, immediate response, which is marked by cellular degranulation and the release of proinflammatory mediators, including histamine. Antigen-presenting cells are also activated by allergen-loaded IgE, resulting in immunomodulation of T-cell responses. The IgE molecule binds to two types of receptors, the high-affinity (Fc epsilonRI) and low-affinity (Fc epsilonRII or CD23) receptors, that have differing properties important in mediating allergen-induced responses. New therapies targeting the IgE molecule reduce allergen-stimulated immune responses and improve the clinical symptoms in subjects with allergic rhinitis. Understanding the role of the IgE molecule is necessary to appreciate the development and use of novel therapies targeting its actions.

Atopic dermatitis--more than a simple skin disorder

PURPOSE

To describe atopic dermatitis (AD) in relation to a case study, the diagnostic criteria, complications, prevalence, future implications, and management for the primary care provider.

DATA SOURCES

Extensive literature review on the condition, supplemented with an actual case study.

CONCLUSIONS

Although there are many scientific studies done on AD, the exact pathogenesis and cure for this condition are still to be discovered. It is usually chronic and has some fatal sequelae in those who have been exposed to viral infections. Asthma, allergic rhinitis (AR), and AD are considered the atopic triad. Further studies that may help improve medical providers' understanding of AD are going on and offer hope to those afflicted by this disorder.

IMPLICATIONS FOR PRACTICE

Children over 5 years old may have outgrown their symptoms, so it is best to diagnose this condition at an early age to provide better management outcomes. Because it is part of an atopic triad, the nurse practitioner must think beyond the presenting skin condition to consider possible respiratory system conditions. AD may herald the onset of asthma and AR.

Cytokine and Antibody Responses in Birch-Pollen-Allergic Patients Treated with Genetically Modified Derivatives of the Major Birch Pollen Allergen Bet v 1

BACKGROUND

Recently, recombinant hypoallergenic derivatives of the major birch pollen allergen, Bet v 1, were used to treat birch-pollen-allergic patients in a double-blind, placebo-controlled, multi-centre immunotherapy study. The aim of this study was to evaluate the effects of vaccination with aluminium-hydroxide-adsorbed recombinant Bet v 1 derivatives versus placebo on T-cell, cytokine and antibody responses in a subgroup of patients.

METHODS

Blood was drawn from patients of the Swedish centre (n = 27; rBet v 1 fragments: n = 10; rBet v 1 trimer: n = 8, and placebo-aluminium hydroxide: n = 9) before the start and after completion of the treatment. PBMC were stimulated with rBet v 1 and analysed for cytokine (IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-gamma)-secreting cells by ELISpot. Bet v 1-specific antibody levels in serum (IgG(1-4), IgE and IgA) were measured by ELISA. Skin prick tests with defined Bet v 1 concentrations were performed before and 10-11 months after the beginning of the study.

RESULTS

Bet v 1-specific IgG levels, consisting of IgG(1), IgG(2) and IgG(4), were significantly increased after treatment with recombinant allergen derivatives. Treatment with rBet v 1 trimer led to a significant (p < 0.05) reduction of Bet v 1-reactive IL-5- and IL-13-producing cells, reflecting a reduced Th2 response. In addition, a decreased number of Bet v 1-reactive IL-4 producing (p = 0.07) and an increase of IL-12-producing (p = 0.06) cells was noted in the trimer-treated patients. In contrast to placebo, active treatment resulted in significantly reduced immediate-type skin reactions to Bet v 1 even 10-11 months after treatment.

CONCLUSION

Vaccination with recombinant hypoallergenic Bet v 1 derivatives induces a Bet v 1-specific IgG response and leads to reduced skin reactivity in allergic patients. A reduction of Bet v 1-specific Th2 responses was observed in trimer-treated patients, which may reflect the intrinsic property of this allergen derivative.

CD34+ cells in the peripheral blood transport herpes simplex virus DNA fragments to the skin of patients with erythema multiforme (HAEM)

Herpes simplex virus (HSV)-associated erythema multiforme (HAEM) is a recurrent disease characterized by the presence and expression of HSV DNA fragments in lesional skin. Our studies examined the mechanism of viral DNA transport to the skin of HAEM patients. CD34+ cells were isolated from the blood of normal subjects and HSV and HAEM patients during acute lesions and at quiescence. They were cultured with cytokines that favor their differentiation into Langerhans cells (LC) precursors (CD1a+/CD14-) and examined for HSV replication, HSV-induced cellular alterations, viral DNA fragmentation, and clearance. CD34+ cells from all study groups were non-permissive for HSV replication but infection favored their differentiation into CD1a+/CD14- LC precursors and upregulated E-cadherin expression, thereby assisting LC targeting to the skin. Only HAEM patients had CD34+ cells that retained viral DNA fragments, notably polymerase DNA, for at least 7 d of in vitro culture. The percentages of circulating CD34+ (and CD34+/CLA+) cells were significantly higher in HAEM patients at the time of acute lesions. A similar increase was not seen for HSV patients. The data are the first report implicating CD34+ cells in HAEM pathogenesis, likely by transporting HSV DNA fragments to lesional skin.

Production of large numbers of Langerhans' cells with intraepithelial migration ability in vitro

Langerhans' cells (LCs) are a subset of immature dendritic cells (DCs) and play a key role in the initiation and regulation of immune responses. Functional studies of these cells have been hampered by difficulties in generating a large number of LCs in vitro. We describe a new method to efficiently generate immature DCs exhibiting morphological, immunohistochemical, and ultrastructural features of LCs (CD1a+, Birbeck Granules+, CD207+, E-cadherin+, cutaneous lymphocyte-associated antigen+, and CCR6+) from a limited number of CD34+ cord blood progenitors. This method is based on a two-step procedure consisting of an amplification phase followed by a terminal differentiation induction. The amplification step is initiated with a combination of hematopoietic growth factors (thrombopoietin/stem cell factor/fetal liver tyrosine kinase-3 ligand), cytokines (granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and interleukin-4), and 5 ng/ml of transforming growth factor (TGF)-beta1. The differentiation is induced by increasing the concentration of TGF-beta1 to 12.5 ng/ml. These culture conditions were efficient for generating a large number of immature LCs (8.74 x 10(6) +/- 3.2) from 15 x 10(4) CD34+ progenitor cells. In addition, these LCs were shown to be able to infiltrate an in vitro reconstructed epithelium. Because LCs play an important role in the mucosal immunity, this technique could be useful to study their interactions with epithelial pathogenic agents and to perform pharmacological, toxicological, and clinical research.

Ovalbumin-specific IgE modulates ovalbumin-specific T-cell response after repetitive oral antigen administration

BACKGROUND

Some patients outgrow their food allergies even though their serum antigen-specific IgE levels remain high.

OBJECTIVE

To elucidate the role of T cells in outgrowing food allergies in the presence of antigen-specific IgE, we tracked antigen-specific T-cell responses after oral antigen administration.

METHODS

Ovalbumin (OVA)-specific T-cell receptor (TCR) and OVA-specific IgE transgenic (Tg) mice (OVA-TCR/IgE-Tg) and OVA-specific TCR Tg (OVA-TCR-Tg) mice were fed with high doses of OVA or PBS every other day. After 7 administrations, OVA-specific proliferation and cytokine production of mononuclear cells of the spleen, mesenteric lymph nodes, and Peyer's patches and the number of splenic CD4 + CD25 + T cells were analyzed.

RESULTS

Without OVA administration, the splenocytes from OVA-TCR/IgE-Tg mice exhibited a higher proliferative response and produced more IL-4 and IL-10 and less IFN-gamma than those from OVA-TCR-Tg mice. The proliferative responses of the splenocytes from either OVA-TCR/IgE-Tg mice or OVA-TCR-Tg mice fed with OVA were significantly reduced compared with those from PBS-fed mice. The number of OVA-specific TCR + T cells decreased in the spleen from OVA-fed mice, whereas the number of CD4 + CD25 + T cells increased. The suppressed proliferation of splenocytes of OVA-fed mice was partially resumed by neutralization of TGF-beta1, but not of IL-10.

CONCLUSION

The presence of OVA-specific IgE modulated the OVA-specific responses of the splenocytes. Irrespective of the presence of OVA-specific IgE, repetitive oral administration of OVA induced tolerance, which seems to be composed of clonal deletion/anergy and TGF-beta1-mediated active suppression.

Atopy patch test with house dust mite allergen--an IgE-mediated reaction?

BACKGROUND

The eczema reaction in the atopy patch test (APT) is proposed to be immunoglobulin (Ig)E mediated, but can take place also in individuals lacking allergen-specific IgE in serum. The purpose of this study was to evaluate the importance of allergen-specific serum IgE for the APT reaction.

METHODS

Ten patients with reproducible positive APT to extract of Dermatophagoides pteronyssinus, five patients with (group A) and five patients without (group B) detectable serum-IgE to D. pteronyssinus, were tested with extract of D. pteronyssinus on normal skin for 6, 24, 48 and 72 h. Skin biopsies were taken and analysed for cell infiltrates, eosinophils (EG2), IgE, FcepsilonRI, CD1a, CD4, CD8 and metalloproteinase 9 (MMP9).

RESULTS

The number of IgE+, CD4+, EG2+ and MMP9+ cells increased with time in group A. FcepsilonRI+ cells and CD8+ cells increased with time in both groups. A correlation was found between the levels of D. pteronyssinus-specific serum-IgE and the score of dermal cell infiltrates at 72 h. The three patients with the highest values of allergen-specific IgE also had the highest expression of EG2+ cells and the highest APT scores.

CONCLUSIONS

Our study strengthens the hypothesis that the IgE molecule has a key role, at least as an amplifier, in the APT reaction.

Indoleamine 2,3-dioxygenase–expressing antigen-presenting cells and peripheral T-cell tolerance

There is growing evidence that dendritic cells, the major antigen-presenting cells and T-cell activators, have a broad effect on peripheral T-cell tolerance and regulation of immunity. Very recently, a new feature of regulatory antigen-presenting cells was observed. Certain dendritic cells, monocytes, and macrophages express the enzyme indoleamine 2,3-dioxygenase, and thus because of enhanced degradation of the essential amino acid tryptophan, they modulate T-cell activity in specific local tissue environments. In this review we discuss the various and apparently disparate effects of indoleamine 2,3-dioxygenase induction in cells of the immune system. We place current knowledge about this mechanism in the context of atopy. We introduce the hypothesis that tryptophan degradation might add to the ability to control and downregulate allergen-specific T-cell responses in atopic individuals.

Differences in circulating dendritic cell subtypes in cord blood and peripheral blood of healthy and allergic children

BACKGROUND

Different types of circulating dendritic cells have been described. Dendritic cells influence differentiation of naive T lymphocytes into T helper type 1 (Th1) and Th2 effector cells.

OBJECTIVE

The purpose of this study was to evaluate the number of circulating DC subtypes in peripheral blood of allergic and healthy children and in cord blood of neonates from allergic and non-allergic parents.

METHODS

Circulating dendritic cells were flow cytometrically identified in whole blood samples as lineage (CD3, CD14, CD16, CD19, CD20, CD56) negative, CD34 negative and HLA-DR-positive cells. According to the expression of CD123 and CD11c, different DC subtypes were identified.

RESULTS

Apart from DC1 (CD11c+ CD123dim+) and DC2 (CD11c- CD123high+), a third DC population was described with less differentiated phenotypic characteristics, namely CD11c- CD123dim+, and therefore defined here as less differentiated DC (ldDC). These ldDC represented the major DC population in cord blood and showed an age-depended decrease. The highest level of ldDC was detected in children with atopic dermatitis, whereas asthmatic children showed the lowest ldDC counts. Furthermore, high-dose inhaled corticosteroid treatment in asthmatic children was related to a decreased ldDC number. The number of circulating DC2 was significantly lower in allergic children, especially in asthmatics, compared to healthy children. In cord blood, no differences in DC subtypes were detectable between neonates at low and high risk for allergic disorders.

CONCLUSION

These results indicate that, apart from DC1 and DC2, a third population of dendritic cells, identified as CD11c- CD123dim+ cells and defined as less differentiated DC, must be considered in the evaluation of circulating DC. Furthermore, DC2 counts were decreased in allergic children, especially in asthmatics, which might be the consequence of an increased recruitment to the target organs.

Large-scale isolation of immature dendritic cells with features of Langerhans cells by sorting CD34+ cord blood stem cells cultured in the presence of TGF-beta1 for cutaneous leukocyte antigen (CLA)

Epidermal Langerhans cells (LCs) are a subset of immature dendritic cells (DCs) and play a key role in the initiation and regulation of T cell responses. Upon antigenic stimulation, LCs differentiate into mature DCs undergoing profound morphologic and functional changes. Studies of the biological details of this conversion process have been hampered by difficulties in generating immature dendritic cells of a defined lineage. We propose a new method of purifying homogenous immature DCs in large numbers by sorting for CLA (Langerhans-like cells) from cord-blood-derived haematopoietic progenitor cells (HPCs). Established protocols describe the generation of LCs from CD34(+) HPCs by sorting for CD1a after 5 days of culture in the presence of GM-CSF and TNF-alpha. However, the numbers of LCs obtained by this method remain within the low range. Furthermore, CD1a is also expressed on interstitial DCs. LCs but not interstitial DCs express the cutaneous leukocyte antigen (CLA). The expression of CLA by cells stimulated with TNF-alpha and GM-CSF peaks on day 10. This expression can be raised further by stimulating the cells with TGF-beta1 and omitting TNF-alpha from day 6 onwards. CLA(+) cells were isolated on day 10 by AutoMACS. Their LC phenotype was established by the presence CD207. The immaturity of Langerhans-like cells was shown by the lack of CD83 and CD208 expression as well as their lower ability to activate allogeneic naive T cells as compared to maturing dendritic cells. However, CLA(+) cells cannot be termed Langerhans cells as they do not express Birbeck granules. Compared to sorting for CD1a (on day 6), sorting for CLA (on day 10) results in isolates of higher purity (80% vs. 50%) and a yield eight times higher (4.9x10(6) vs. 6.5x10(5) cells) when using identical numbers of input cells (5x10(5) cells). This novel method guarantees large numbers of pure and functionally active immature dendritic cells.

Advances in allergic skin diseases

During the past year there have been significant advances in our understanding of the mechanisms underlying allergic skin diseases. This article reviews some of these advances in atopic dermatitis and urticaria. The introduction of a new class of topical anti-inflammatory medications, topical calcineurin inhibitors, has significantly increased our treatment options and led to a rethinking of potential management approaches in atopic dermatitis.

2. Cytokines and chemokines

Cytokines and chemokines are redundant secreted proteins with growth, differentiation, and activation functions that regulate and determine the nature of immune responses and control immune cell trafficking and the cellular arrangement of immune organs. Which cytokines are produced in response to an immune insult determines initially whether an immune response develops and subsequently whether that response is cytotoxic, humoral, cell-mediated, or allergic. A cascade of responses can be seen in response to cytokines, and often several cytokines are required to synergize to express optimal function. An additional confounding variable in dissecting cytokine function is that each cytokine may have a completely different function, depending on the cellular source, target, and, most important, specific phase of the immune response during which it is presented. Numerous cytokines have both proinflammatory and anti-inflammatory potential; which activity is observed depends on the immune cells present and their state of responsiveness to the cytokine. For this chapter, cytokines are grouped according to those that are mononuclear phagocytic-derived or T-lymphocytic-derived; that mediate cytotoxic (antiviral and anticancer), humoral, cell-mediated, or allergic immunity; and that are immunosuppressive. The biology of chemokines are then reviewed, grouped by family.

Atopic dermatitis

Atopic dermatitis is a highly pruritic chronic inflammatory skin disorder affecting 10-20% of children worldwide. Symptoms can persist or begin in adulthood. It is also the most common cause of occupational skin disease in adults. This disease results from an interaction between susceptibility genes, the host's environment, pharmacological abnormalities, skin barrier defects, and immunological factors. New management approaches have evolved from advances in our understanding of the pathobiology of this common skin disorder.

Kinetics of gene induction after FcepsilonRI ligation of atopic monocytes identified by suppression subtractive hybridization

The high-affinity receptor for IgE, FcepsilonRI, on APCs plays an important role in the initiation and chronicity of inflammatory atopic diseases. To understand the molecular regulation of FcepsilonRI-mediated processes, differentially expressed genes are of great interest to be identified. Suppression subtractive cDNA hybridization has been used to identify genes induced after FcepsilonRI stimulation on atopic monocytes. Overexpression of the identified genes was determined by semiquantitative RT-PCR analysis of transcripts from the tester (stimulated) and driver (unstimulated) monocytes. Results were confirmed and kinetics of the transcripts established using blood cells from additional atopics at 4 and 24 h of FcepsilonRI induction. The following sequences were identified: monocyte chemoattractant protein 1, macrophage-inflammatory protein 1beta, IL-6, beta(A) subunit of inhibin/activin, IFN-stimulated gene of 54 kDa, IL-1R antagonist, and kynurenine 3-monooxygenase. Chemokines are highly expressed during the early and late phase after FcepsilonRI cross-linking, whereas proinflammatory and differentiation stimuli rapidly decline after an initial overexpression. Kynurenine 3-monooxygenase, an enzyme involved in the degradation of the amino acid tryptophan, is significantly up-regulated during the late phase after 24 h of FcepsilonRI induction. These results demonstrate that the analysis of the profile of gene induction following activation of FcepsilonRI on atopic monocytes may reveal how these cells might participate in the regulation of atopic disorders.

Smallpox vaccination: Risk considerations for patients with atopic dermatitis

As the threat of bioterrorism with pathogenic microbes such as smallpox virus (Variola major) increases, the question of widespread voluntary vaccination with smallpox (vaccinia) vaccines is being carefully considered. A major challenge lies in the ability to protect the population from the disease while minimizing the considerable side effects from the vaccine. Individuals with active or quiescent atopic dermatitis are at increased risk for vaccinia complications. The nature of these complications and other considerations are summarized in this rostrum.

Recognition of pathogenically relevant house dust mite hypersensitivity in adults with atopic dermatitis: a new approach?

BACKGROUND

The pathogenic importance of the ubiquitous house dust mite, Dermatophagoides pteronyssinus (Dp), in atopic dermatitis is unclear.

OBJECTIVE

We aimed to explore the relevance of Dp hypersensitivity in adult patients with atopic dermatitis by using an in vivo topical challenge method and in vitro assays for T-cell reactivity.

METHODS

Dp and control skin prick test solutions were applied to the cubital fossae of 20 patients twice daily for 4 days; the severity of dermatitis and pruritus in the challenge sites were determined before and after testing. The same solutions were used in PBMC proliferation assays that included 10% fresh, autologous serum, the latter aimed at maximizing IgE facilitated allergen presentation.

RESULTS

Although most patients had markedly elevated Dp-specific serum IgE levels, only 6 of 20 patients developed increases in cubital fossa dermatitis severity and pruritus scores that were greater at sites of application of Dp solution than at control sites. In addition, PBMC proliferation in response to Dp solution in the presence of autologous serum was significantly greater in the in vivo challenge-positive patients than in those who did not respond to challenge. A subgroup of patients (7/20) also developed transient but pronounced contact urticaria at sites of Dp application.

CONCLUSION

These findings suggest that hypersensitivity to Dp might be clinically relevant in approximately one third of the adult atopic dermatitis population studied. They also point to methods of identifying patients who might respond to house dust avoidance measures.

Targeting epidermal Langerhans cells by epidermal powder immunization

Immune reactions to foreign or self-antigens lead to protective immunity and, sometimes, immune disorders such as allergies and autoimmune diseases. Antigen presenting cells (APC) including epidermal Langerhans cells (LCs) play an important role in the course and outcome of the immune reactions. Epidermal powder immunization (EPI) is a technology that offers a tool to manipulate the LCs and the potential to harness the immune reactions towards prevention and treatment of infectious diseases and immune disorders.

Transduction of dendritic cells by antigen-encoding lentiviral vectors permits antigen processing and MHC class I-dependent presentation

BACKGROUND

Because antigen-presenting dendritic cells (DCs) play a major role in the polarization of T cells, including T(H)2 cells involved in allergy, strategies to modify DCs genetically are required.

OBJECTIVE

The purpose of this investigation was to transduce murine bone marrow-derived DCs with lentiviral vectors encoding antigen to demonstrate antigen processing and MHC class I-dependent presentation.

METHODS

Bone marrow leukocytes were incubated with antigen-encoding lentiviral constructs and cultured with GM-CSF, IL-4, and Flt-3 ligand. The capacity of the resulting DCs to express, process, and present antigen was tested in vitro.

RESULTS

An average of 40% of DCs expressed antigen after 1 week of culture when antigen encoded by the lentiviral vector construct was green fluorescent protein. To demonstrate that transduced antigen can be presented by DCs on MHC class I, we chose the lymphocytic choriomeningitis virus glycoprotein (gp) as a model antigen, inasmuch as it is recognized by CD8 T cells from transgenic mice expressing an MHC class I-restricted T-cell receptor specific for the epitope of positions 33 through 41 of gp. DCs transduced with lentiviral construct encoding gp and matured with LPS activated transgenic T cells in an antigen-specific fashion. Using transporter associated with antigen presentation (TAP)-deficient mice, we show that presentation of the gp33-41 epitope is TAP-dependent, confirming processing of gp by the endogenous pathway.

CONCLUSIONS

These results demonstrate that CD8 T cells can recognize MHC class I epitopes processed from antigen in DCs transduced with lentiviral vectors. Lentiviral transduction of DCs and antigen presentation to CD8 T cells could be exploited for immunotherapy, because allergen-specific CD8 T cells have been shown to be suppressive in IgE-dependent allergy models.

CD4+ T helper cell-independent antitumor response mediated by murine IFN-beta gene delivery in immunocompetent mice

Previously, we provided evidence that adenovirus-mediated interferon-beta (IFN-beta) gene therapy inhibits tumor formation and causes dramatic regression of established tumors in immunodeficient mice. We suggested that local IFN-beta gene therapy with adenoviral vectors could be an effective treatment for cancer. In this report, the actions of murine IFN-beta (MuIFN-beta) gene delivery on both subcutaneous and metastatic tumors were evaluated in syngeneic immunocompetent mice. We found that the antitumor response mediated by MuIFN-beta gene delivery relied on CD8(+) T cells but was completely independent of CD4(+) T cells. In fact, depletion of CD4(+) T cells appeared to enhance the effect on tumor inhibition and animal survival induced by adenovirus-MuIFN-beta gene delivery. Therefore, adenovirus-MuIFN-beta gene therapy can bypass CD4(+) T helper (Th) cells and activate an effective CD8(+) T cell-dependent antitumor immunity in immunocompetent mice. Furthermore, we found that depletion of macrophages but not natural killer (NK) cells suppressed the antitumor response induced by MuIFN-beta gene therapy. These data, together with our previous results, suggest that in the clinical setting, local adenovirus-mediated IFN-beta gene therapy may lead to an efficient and long-lasting eradication of tumors by a direct antitumor effect and via activation of the innate and the adoptive immune systems.