Immune tolerance in allergy

Analysis of heritability and environmental factors in preschool children with eczema: a case-control study

Eczema is common in children, and its onset is affected by both genetic and environmental factors. We investigated the effects of genetic and environmental factors on the incidence of eczema in preschool children. 515 preschool children with eczema and 515 children participating in the physical examination were enrolled. The study included the incidence of childhood eczema, the child's birth and feeding conditions, the history of eczema in the parents, and relevant environmental risk factors, and to comprehensively analyze the genetic and environmental factors influencing childhood eczema. Among 1030 children, 173 parents (8.4%) had eczema, with a heritability of 73.59% for boys' parents and 58.59% for girls' parents. Multivariate logistic regression results showed that premature infants, low birth weight, children who had used antibiotics before the age of 1 year the living environment between the first year of mother pregnancy and the first year of the child is humid, a father with a history of eczema, a mother with a history of eczema are risk factors for eczema in children. Actively preventing environmental factors related to eczema may be an effective means to reduce the risk of eczema in children.

Cationic liposomes bearing Bet v 1 by coiled coil-formation are hypo-allergenic and induce strong immunogenicity in mice

Although aluminum hydroxide (alum) is widely accepted and used as safe vaccine adjuvant, there is some concern about possible toxicity upon long-lasting repeated exposure during subcutaneous allergen immunotherapy (SCIT). Our objective was to evaluate allergen-bearing liposomes as possible alternative for alum-adsorption in SCIT. A self-assembling, coiled-coil forming peptide pair was used to anchor the major birch pollen allergen Bet v 1 to the surface of cationic liposomes. The resulting nanoparticulate liposomes were characterized with respect to their physicochemical, allergenic and immunological properties. Allergenicity was studied by ImmunoCAP inhibition and rat basophil leukemia (RBL) cell assays. Immunogenicity (immunoglobulin responses) and immune skewing (cytokine responses) were evaluated upon immunization of naïve mice, and compared to alum-adsorbed Bet v 1. Bet v 1-bearing cationic liposomes with a diameter of ∼200 nm showed a positive zeta potential. The coiled-coil conjugation of Bet v 1 to the surface of liposomes resulted in about a 15-fold lower allergenicity than soluble Bet v 1 as judged by RBL assays. Moreover, the nanoparticles induced Bet v 1-specific IgG1/IgG2a responses in mice that were several orders of magnitude higher than those induced by alum-adsorbed Bet v 1. This strong humoral response was accompanied by a relatively strong IL-10 induction upon PBMC stimulation with Bet v 1. In conclusion, their hypo-allergenic properties, combined with their capacity to induce a strong humoral immune response and a relatively strong IL-10 production, makes these allergen-covered cationic liposomes a promising alternative for aluminum salt-adsorption of allergen currently used in SCIT.

Miquelianin Inhibits Allergic Responses in Mice by Suppressing CD4+ T Cell Proliferation

Allergic diseases, including atopic dermatitis (AD), induce type 2 helper T (Th2) cell-dominant immune responses. Miquelianin (quercetin 3-O-glucuronide, MQL) is an active compound in Rosae multiflorae fructus extract with anti-allergic properties. Here, we investigate the anti-allergic effects of MQL in an ovalbumin (OVA)-induced Th2-dominant mouse model and the associated mechanisms. Oral MQL suppressed cytokine and IL-2 production and proliferation of Th2 cells and upregulated heme oxygenase-1 (HO-1) in splenocytes. Ex vivo MQL suppressed Th1- and Th2-related immune responses by inhibiting CD4⁺ T cell proliferation, and upregulated HO-1 in CD4⁺ T cells by activating C-Raf-ERK1/2-Nrf2 pathway via induction of reactive oxygen species generation. In a trimellitic anhydride-induced AD-like mouse model, both topical and oral MQL ameliorated AD symptoms by suppressing Th2 immune responses. Our results suggest that MQL is a potential therapeutic agent for CD4⁺ T cell-mediated diseases, including allergic diseases.

Exploiting Old Pathogens to Create New Therapeutics

Intestinal worms are well known for their potent immuno-modulatory capacity. In a recent study, Navarro et al. (2016) identify a secreted hookworm protein that can suppress allergic responses in both mice and humans. This represents an exciting strategy for treating chronic inflammatory disorders such as allergy.

Safety and pharmacodynamics of intranasal GSK2245035, a TLR7 agonist for allergic rhinitis: A randomized trial

BACKGROUND

Toll-like receptor 7 (TLR7) stimulation in the airways may reduce responses to aeroallergens by induction of type 1 interferons (IFNs). GSK2245035 is a novel selective TLR7 agonist in pharmaceutical development.

OBJECTIVE

Assessment of safety, pharmacodynamics and nasal allergic reactivity following repeated weekly intranasal (i.n.) GSK2245035.

METHODS

This randomized, double-blind, placebo-controlled study (TL7116958) was conducted over two pollen seasons (2013-2014) and follow-up study (204509) conducted 1 year later. Participants with allergic rhinitis (n=42) were randomized to receive eight weekly doses of i.n. GSK2245035 (20 ng [2014 Cohort; n=14] or 80 ng [2013 Cohort; n=14]) or placebo (n=14). Adverse events (AEs) including cytokine release syndrome AEs (CytoRS-AEs) and nasal symptoms were assessed. Nasal and serum IFN-inducible protein 10 (IP-10) were measured after doses 1 and 8, then 1 (follow-up visit [FUV] 1) and 3 (FUV2) weeks after final dose. Nasal allergen challenges (NACs) and allergic biomarker assessment (nasal, serum) were conducted at baseline, FUV1, FUV2 and at a FUV 1 year after final dose (FUV3; 2014 Cohort only). A Bayesian framework enabled probability statements for mean effect sizes.

RESULTS

GSK2245035 induced CytoRS-AEs (most commonly headache, median duration <1 day) in 93% of participants at 80 ng, while AE incidence at 20 ng was similar to placebo. There was no evidence of nasal inflammation. Dose-related increases in nasal and serum IP-10 were observed 24 hours after doses 1 and 8 (>95% certainty). Both doses showed a trend in reducing total nasal symptom score 15 minutes post-NAC at FUV1 and FUV2, but there was no reduction evident at FUV3. Nasal levels of selected allergic biomarkers demonstrated trends for reductions at FUV1, FUV2 and FUV3.

CONCLUSIONS AND CLINICAL RELEVANCE

Weekly i.n. GSK2245035 20 ng was well tolerated and reduced allergic reactivity to nasal challenge for 3 weeks post-treatment.

Dose-dependent immunomodulating effects of endotoxin in allergic airway inflammation

How very high exposure levels to endotoxin in a farming environment provide protection against respiratory allergic symptoms and low-to-moderate levels of endotoxin in urban homes promote allergic response is unclear. Dose-specific bacterial endotoxin or LPS-induced tolerance mechanisms can affect lung inflammations, coupled with the Th2 immune responses. Here, we explored the effects of intranasal exposure of LPS at two different doses (based on occupational exposures during handling of agricultural wastes) in OVA-sensitized allergic wild type (WT) and TLR4-KO mice, particularly, with respect to Th2 cytokines and Tregs level. Low-dose LPS (100 ng) exposure prohibited airway tolerance and failed to generate T-cell-dependent protection against lung inflammations in allergic mice. Furthermore, low Tregs at the inflammatory site and induced Th2 cytokines, as well as IL-6 and IL-25, suggested that low-dose LPS might be associated with the suppression of tolerance mechanisms. In contrast, high-dose LPS (20 µg) favored the suppression of Th2 cytokines, IL-6 and IL-25, but failed to induce Th1 cytokines (e.g. IFN-γ). Our results suggest that low-dose LPS can enhance airway allergic inflammation through failing of antigen-dependent immune regulatory homeostasis. The exposure levels of LPS can determine the generation of inflammatory responses in airway allergy.

Vitamin D3 improves the effects of low dose Der p 2 allergoid treatment in Der p 2 sensitized BALB/c mice

BACKGROUND

Airborne allergens can induce an immunological chronic disease characterized by airway hyper responsiveness and inflammation, mediated by exaggerated Th2 immune response. Allergen-specific immunotherapy (AIT) is effective for treating this condition because it is able to modify its natural course by opposing the underlying pathogenic mechanisms and determining immune suppression, immune deviation and tolerance. The rational for the present study was to investigate the possibility of improving allergoid-based IT in terms of efficacy and safety. Recently, 1α,25-dihydroxyvitamin D3 (VD3), the active metabolite of vitamin D3, was described to be a potent inducer of T regulatory cells and to be a good adjuvant in AIT settings.

METHODS

We investigated whether the co-administration of VD3 could potentiate the effect of AIT even when added to a low dose of chemically-modified monomeric allergoid of Der p 2 (d2-OID), in a Derp p 2 (d2)-sensitized BALB/c mice model. Control groups where treated with sham, VD3 alone or d2-OID only.

RESULTS

The d2-OID alone was not fully successful, as expected for a low dose. VD3 administration was associated with some valuable, although limited, changes in the immunological parameters in the lung. On the contrary, the VD3 adjuvated allergoid vaccine induced the most prominent reduction of airway eosinophilia and Th2 cytokines and concomitant increase of T regulatory cells and IL-10 in the lung and Der p 2-specific IgG2a in the serum.

CONCLUSIONS

The addition of VD3 to a conventional AIT protocol would allow the reduction of allergoid dose needed and therefore, the production costs. Moreover, beneficial immunomodulatory effects have been achieved by the oral administration which might favour the management of the therapy by the patients and their adherence, possibly enhancing the efficacy of the treatment.

Specific immunotherapy for rhinitis and asthma with a subcutaneous hypoallergenic high-dose house dust mite extract: results of a 9-month therapy

AIM

Effectiveness of a 9-month specific immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract to reduce allergic symptoms as perceived by patients and physicians was assessed.

PATIENTS & METHODS

An observational, retrospective, multicenter study was carried out in patients diagnosed with asthma and/or rhinitis caused by house dust mites having started specific immunotherapy with Acaroid(®). Primary end point was perceived effectiveness.

RESULTS

A total of 409 patients were included. According to physician-completed visual analogue scale, a 58.1% clinical improvement was observed. Patient-completed visual analogue scale showed a 69.8% clinical improvement. The need for unscheduled/emergency healthcare, as an indication of poor quality of life, showed a significant reduction.

CONCLUSION

Our results confirm in a real-world setting the findings from randomized clinical trials of high-dose house dust mites allergoid immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract.

Allergic Rhinitis and Chronic Daily Headaches: Is There a Link?

Allergic rhinitis and migraine remain on the list of the most common diseases affecting adults. Migraines and headaches due to allergic rhinitis are easily confused because the symptoms of both conditions often overlap. Both may occur with sinus headache, nasal congestion, and lacrimation and may worsen with weather changes and exposure to allergens. No precise clinical definition exists for what constitutes a sinus headache, which has always been a diagnostic dilemma. Contrary to popular belief, headache is not a typical symptom of rhinitis. Some studies have shown that up to 90 % of sinus headaches are actually migraines. Nevertheless, patients with self-diagnosed sinus headache self-treat or are treated by primary care physicians and/or otolaryngologists with medications for rhinosinusitis, ignoring the neurogenic causes of the symptoms when most of these patients fulfill diagnostic criteria for chronic migraine. Chronic migraine affects 2 % of the general population and has a significant socioeconomic impact on society, incurring health care costs and diminishing quality of life; therefore, the proper diagnosis and treatment of these headache patients should be a priority.

Natural clinical tolerance to peanut in African patients is caused by poor allergenic activity of peanut IgE

BACKGROUND

In Africa, peanuts are frequently consumed, but severe allergic reactions are rare. We investigated immunological patterns of clinical tolerance to peanut in peanut-sensitized but asymptomatic patients from central Africa compared to peanut-allergic and peanut-sensitized but asymptomatic patients from Sweden.

METHODS

Sera from allergic patients (n = 54) from Zimbabwe sensitized to peanut but without allergic symptoms to peanut, and sera from peanut-allergic (n = 25) and peanut-sensitized but asymptomatic (n = 25) patients from Sweden were analyzed toward peanut allergen components (Ara h 1-3, 6, 8-9) and other allergen molecules from important allergen sources using microarray. IgE to Ara h 2 peptide epitopes was analyzed, and allergenic activity was assessed by basophil activation assay.

RESULTS

Forty-six percent of the African and all peanut-allergic Swedish patients showed IgE toward one of the highly allergenic peanut allergens (Ara h 1-3, 6, 9). However, 48% of the African patients had IgE to cross-reactive carbohydrate determinants (CCDs) with low allergenic activity and 60% of the Swedish asymptomatic patients had IgE against the PR protein Ara h 8. IgG and IgG4 specificities and levels could not discriminate between the African asymptomatic and Swedish peanut-allergic patients. Asymptomatic patients almost lacked IgE to Ara h 2 peptides, which were recognized by peanut-allergic patients. Peanut IgE from peanut asymptomatic patients showed poor allergenic activity compared with IgE from peanut-allergic patients.

CONCLUSIONS

Natural clinical tolerance to peanut in the African patients can be caused by IgE to low allergenic peanut components and by poor allergenic activity of peanut-specific IgE.

Regulatory T cells in early life: comparative study of CD4+CD25high T cells from foals and adult horses

The immune system of mammals is subject to continuous development during the postnatal phase of life. Studies following the longitudinal development of the immune system in healthy children are limited both by ethical considerations and sample volumes. Horses represent a particular valuable large animal model for T regulatory (Treg) cells and allergy research. We have recently characterised Treg cells from horses, demonstrated their regulatory capability and showed both their expansion and induction in vitro. Insect bite hypersensitivity (IBH) is a common allergy in horses resembling atopic dermatitis and studies have shown that first exposure to allergens in adult life results in an increased incidence of IBH. The aim of the present study was to characterize circulating CD4⁺CD25^highFoxP3⁺cells in foals, evaluate their suppressive capability and their in vitro induction compared to adult horses. 19 foals (age range, 1–5 months), their adult mothers and six one-year-old horses (yearlings) were included in the study. The proportion of FoxP3⁺ cells within the circulating CD4⁺CD25^high population was significantly higher in foals (47%) compared to their mothers (18%) and to yearlings (26%). Treg cells from foals also displayed a higher suppressive capability. Furthermore, CD4⁺CD25^high cells in foals could be induced in vitro from CD4⁺CD25⁻ cells in a significantly higher proportion compared to mares. These cells also displayed a significantly enhanced suppressive capability. In summary these findings support the notion that exposure of horses to allergens during maturation of the immune system assists the establishment of induced (i)Treg driven tolerance.

Molecular evolution of hypoallergenic hybrid proteins for vaccination against grass pollen allergy

More than 10% of the population in Europe and North America suffer from IgE-associated allergy to grass pollen. In this article, we describe the development of a vaccine for grass pollen allergen-specific immunotherapy based on two recombinant hypoallergenic mosaic molecules, designated P and Q, which were constructed out of elements derived from the four major timothy grass pollen allergens: Phl p 1, Phl p 2, Phl p 5, and Phl p 6. Seventeen recombinant mosaic molecules were expressed and purified in Escherichia coli using synthetic genes, characterized regarding biochemical properties, structural fold, and IgE reactivity. We found that depending on the arrangement of allergen fragments, mosaic molecules with strongly varying IgE reactivity were obtained. Based on an extensive screening with sera and basophils from allergic patients, two hypoallergenic mosaic molecules, P and Q, incorporating the primary sequence elements of the four grass pollen allergens were identified. As shown by lymphoproliferation experiments, they contained allergen-specific T cell epitopes required for tolerance induction, and upon immunization of animals induced higher allergen-specific IgG Abs than the wild-type allergens and a registered monophosphoryl lipid A-adjuvanted vaccine based on natural grass pollen allergen extract. Moreover, IgG Abs induced by immunization with P and Q inhibited the binding of patients' IgE to natural allergens from five grasses better than IgG induced with the wild-type allergens or an extract-based vaccine. Our results suggest that vaccines based on the hypoallergenic grass pollen mosaics can be used for immunotherapy of grass pollen allergy.

An update on allergen immunotherapy and asthma

PURPOSE OF REVIEW

The aim is to review recent literature up to July 2013 concerning the effect of allergen-specific immunotherapy (AIT) on asthma. AIT, effective in combined allergic rhinitis and asthma, was previously described as a convenient approach able to improve clinical outcomes and reduce bronchial hyperresponsiveness. In addition, long-term and preventive effects on the onset of new sensitizations and progression from allergic rhinitis to asthma have been shown.

RECENT FINDINGS

Recent investigations, mainly based on observational or small open trials, confirmed previous findings, showing improvement in asthma control, symptoms and medication usage and steroid-sparing effects, sometimes inconsistent with changes in lung function. Some meta-analyses support the clinical benefit on adult and paediatric asthma. Only few trials, however, were specifically designed to explore asthma endpoints.

SUMMARY

Clinical studies primarily have focused on AIT, and research on asthma endpoints is scarce; however, the evidence of beneficial effect of AIT for the treatment of adults and children affected by allergic rhinitis with or without asthma suggests that this treatment can favourably affect asthma. In children, sublingual AIT has been more extensively investigated than injective. Confirmatory, adequately powered trials are needed to reinforce the evidence of efficacy for individual AIT products. The main drawback in using injective AIT for asthma is the risk of serious adverse reactions and uncontrolled asthma. The sublingual route is better tolerated and does not appear inferior. As standard controller pharmacotherapy seems unable to affect the natural course of asthma, the potentially disease-modifying effect of AIT represents an appealing perspective that requires further investigation.

Interplay of T Helper 17 Cells with CD4(+)CD25(high) FOXP3(+) Tregs in Regulation of Allergic Asthma in Pediatric Patients

Background. There is evidence that Tregs are important to prevent allergic diseases like asthma but limited literature exists on role of T_H17 cells in allergic diseases. Methods. Fifty children with asthma and respiratory allergy (study group) and twenty healthy children (control group) were recruited in this study. Total IgE levels and pulmonary function tests were assessed. The expression of Tregs and cytokines was determined by flow cytometry. Results. The average level of total IgE in study group (316.8 ± 189.8 IU/mL) was significantly higher than controls (50 ± 17.5 IU/mL, P < 0.0001). The frequency of T_H17 cells and culture supernatant level of IL-17 in study group (12.09 ± 8.67 pg/mL) was significantly higher than control group (2.01 ± 1.27 pg/mL, P < 0.001). Alternatively, the frequency of FOXP3 level was significantly lower in study group [(49.00 ± 13.47)%] than in control group [(95.91 ± 2.63)%] and CD4⁺CD25⁺FOXP3⁺ to CD4⁺CD25⁺ ratio was also significantly decreased in study group [(6.33 ± 2.18)%] compared to control group [(38.61 ± 11.04)%]. The total serum IgE level is negatively correlated with FOXP3 level (r = −0.5273, P < 0.0001). The FOXP3 expression is negatively correlated with the IL-17 levels (r = −0.5631, P < 0.0001) and IL-4 levels (r = −0.2836, P = 0.0460). Conclusions. Imbalance in T_H17/Tregs, elevated IL-17, and IL-4 response and downregulation of FOXP3 were associated with allergic asthma.

Kimura's disease or IgG4-related disease? A case-based review

Kimura's disease usually presents with benign painless soft tissue swelling around the head and neck areas with eosinophilia and high immunoglobulin E (IgE) levels. IgG4-related disease is characterized by fibrosis and sclerosis of the involved organs, with infiltration of IgG4-positive plasma cells. There are some similar clinical manifestations of these two diseases, with eosinophilia or high IgE levels often found in patients with IgG4-related disease. However, the relation between these two diseases is not well known. We report a 23-year-old man who had multiple neck lumps for longer than 1 year. He had remarkable eosinophilia and elevated serum IgE levels. Biopsy of his lymph nodes suggested the diagnosis of both Kimura's disease and IgG4-related disease. In this article, we discuss the relationship between Kimura's disease and IgG4-related disease. We also suggest a possible model ("allergen-specific immunotherapy") to illustrate our view that an increase in IgG4-positive plasma cells is an epiphenomenon of Kimura's disease.

Potential of immunoglobulin A to prevent allergic asthma

Allergic asthma is characterized by bronchial hyperresponsiveness, a defective barrier function, and eosinophilic lower airway inflammation in response to allergens. The inflammation is dominated by Th2 cells and IgE molecules and supplemented with Th17 cells in severe asthma. In contrast, in healthy individuals, allergen-specific IgA and IgG4 molecules are found but no IgE, and their T cells fail to proliferate in response to allergens, probably because of the development of regulatory processes that actively suppress responses to allergens. The presence of allergen-specific secretory IgA has drawn little attention so far, although a few epidemiological studies point at a reverse association between IgA levels and the incidence of allergic airway disease. This review highlights the latest literature on the role of mucosal IgA in protection against allergic airway disease, the mechanisms described to induce secretory IgA, and the role of (mucosal) dendritic cells in this process. Finally, we discuss how this information can be used to translate into the development of new therapies for allergic diseases based on, or supplemented with, IgA boosting strategies.

Mechanisms of peripheral tolerance to allergens

The immune system is regulated to protect the host from exaggerated stimulatory signals establishing a state of tolerance in healthy individuals. The disequilibrium in immune regulatory vs effector mechanisms results in allergic or autoimmune disorders in genetically predisposed subjects under certain environmental conditions. As demonstrated in allergen-specific immunotherapy and in the healthy immune response to high-dose allergen exposure models in humans, T regulatory cells are essential in the suppression of Th2-mediated inflammation, maintenance of immune tolerance, induction of the two suppressive cytokines interleukin-10 and transforming growth factor-β, inhibition of allergen-specific IgE, and enhancement of IgG4 and IgA. Also, suppression of dendritic cells, mast cells, and eosinophils contributes to the construction of peripheral tolerance to allergens. This review focuses on mechanisms of peripheral tolerance to allergens with special emphasis on recent developments in the area of immune regulation.

CD8⁺CXCR5⁺ T cells regulate pathology in the genital tract

We have identified a CD8⁺CXCR5⁺ T cell that prevents the development of oviduct dilation following C. muridarum genital infection. Phenotypic studies show that CD8⁺CXCR5⁺ cells express markers of T regulatory cells (FoxP3, CD25, and GITR) but do not express a necessary component of cytotoxic cells (perforin). Cxcr5⁻/⁻ mice have significantly lower numbers of CD8⁺ cells and lack the CD8⁺CXCR5⁺ population while the total number of CD4⁺ cells is equivalent between mouse strains. The transfer of CD8⁺ splenocytes from WT mice reduces the oviduct dilation seen in Cxcr5⁻/⁻ mice following C. muridarum infection. Future studies will investigate the mechanism by which this cell type regulates genital tract pathology.

Human schistosome infection and allergic sensitisation

Several field studies have reported an inverse relationship between the prevalence of helminth infections and that of allergic sensitisation/atopy. Recent studies show that immune responses induced by helminth parasites are, to an extent, comparable to allergic sensitisation. However, helminth products induce regulatory responses capable of inhibiting not only antiparasite immune responses, but also allergic sensitisation. The relative effects of this immunomodulation on the development of protective schistosome-specific responses in humans has yet to be demonstrated at population level, and the clinical significance of immunomodulation of allergic disease is still controversial. Nonetheless, similarities in immune responses against helminths and allergens pose interesting mechanistic and evolutionary questions. This paper examines the epidemiology, biology and immunology of allergic sensitisation/atopy, and schistosome infection in human populations.

Oral immunotherapy for treatment of egg allergy in children

BACKGROUND

For egg allergy, dietary avoidance is the only currently approved treatment. We evaluated oral immunotherapy using egg-white powder for the treatment of children with egg allergy.

METHODS

In this double-blind, randomized, placebo-controlled study, 55 children, 5 to 11 years of age, with egg allergy received oral immunotherapy (40 children) or placebo (15). Initial dose-escalation, build-up, and maintenance phases were followed by an oral food challenge with egg-white powder at 10 months and at 22 months. Children who successfully passed the challenge at 22 months discontinued oral immunotherapy and avoided all egg consumption for 4 to 6 weeks. At 24 months, these children underwent an oral food challenge with egg-white powder and a cooked egg to test for sustained unresponsiveness. Children who passed this challenge at 24 months were placed on a diet with ad libitum egg consumption and were evaluated for continuation of sustained unresponsiveness at 30 months and 36 months.

RESULTS

After 10 months of therapy, none of the children who received placebo and 55% of those who received oral immunotherapy passed the oral food challenge and were considered to be desensitized; after 22 months, 75% of children in the oral-immunotherapy group were desensitized. In the oral-immunotherapy group, 28% (11 of 40 children) passed the oral food challenge at 24 months and were considered to have sustained unresponsiveness. At 30 months and 36 months, all children who had passed the oral food challenge at 24 months were consuming egg. Of the immune markers measured, small wheal diameters on skin-prick testing and increases in egg-specific IgG4 antibody levels were associated with passing the oral food challenge at 24 months.

CONCLUSIONS

These results show that oral immunotherapy can desensitize a high proportion of children with egg allergy and induce sustained unresponsiveness in a clinically significant subset. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00461097.).

House dust mite-specific immunotherapy alters the basal expression of T regulatory and FcεRI pathway genes

BACKGROUND

Regulatory T (Treg) cells and IgE-mediated signaling pathways could play important roles in the induction of allergen tolerance during house dust mite-specific subcutaneous immunotherapy (HDM-SCIT). Our aim was to compare the basal expression levels of Treg, T helper 1 (Th1) and Th2 transcription factors and components involved in IgE-mediated signaling in healthy subjects with those in HDM-allergic patients both untreated and successfully treated with HDM-SCIT.

METHODS

Thirty-nine HDM-allergic patients who completed a 3- to 5-year course of mite extract SCIT, 20 mite-allergic controls and 25 healthy controls participated in this study. The efficacy of SCIT was monitored using skin-prick tests (SPTs), total immunoglobulin E (tIgE), specific IgE (sIgE), sIgG(4), nasal challenge and visual analog scale (VAS) scores at several time points. The mRNA levels of forkhead box protein 3 (FOXP3), T-BET, GATA-3, FcεRI, spleen tyrosine kinase (Syk), phosphatidylinositol 3 kinase (PI3K) and SH2 domain-containing inositol phosphatase (SHIP) were quantified by real-time RT-PCR using nonstimulated whole blood samples.

RESULTS

Decreased wheal sizes and VAS scores, negative challenges and increased sIgG(4) levels indicated that SCIT was effective in the treated patients. Basal expression levels of FOXP3 and GATA-3 decreased and T-BET levels increased in both treated patients and in healthy controls compared to untreated patients. The IgE-mediated pathway kinases Syk and PI3K exhibited reduced expression, whereas SHIP phosphatase levels were elevated in both treated patients and healthy controls relative to untreated patients. The expression levels of FcεRI were not significantly altered.

CONCLUSIONS

Immunotherapy using HDM extracts results in a modification of the basal expression levels of several IgE-related signaling factors and induces a highly significant upregulation of Th1-response and downregulation of Th2-response transcription factors. Interestingly, this therapy also appears to reduce the basal expression of FOXP3.

μ-opioid receptor-mediated alterations of allergen-induced immune responses of bronchial lymph node cells in a murine model of stress asthma

BACKGROUND

Psychological stress has a recognized association with asthma symptoms. Using a murine model of allergic asthma, we recently demonstrated the involvement of μ-opioid receptors (MORs) in the central nervous system in the stress-induced exacerbation of airway inflammation. However, the involvement of MORs on neurons and immunological alterations in the stress asthma model remain unclear.

METHODS

MOR-knockout (MORKO) mice that express MORs only on noradrenergic and adrenergic neurons (MORKO/Tg mice) were produced and characterized for stress responses. Sensitized mice inhaled antigen and were then subjected to restraint stress. After a second antigen inhalation, bronchoalveolar lavage cells were counted. Before the second inhalation, bronchial lymph node (BLN) cells and splenocytes from stressed and non-stressed mice were cultured with antigen, and cytokine levels and the proportions of T cell subsets were measured.

RESULTS

Stress-induced worsening of allergic airway inflammation was observed in wild-type and MORKO/Tg mice but not MORKO mice. In wild-type stressed mice, IFN-γ/IL-4 ratios in cell culture supernatants and the proportion of regulatory T cells in BLN cell populations were significantly lower than those in non-stressed mice. These differences in BLN cells were not observed between the stressed and non-stressed MORKO mice. Restraint stress had no effect on cytokine production or T cell subsets in splenocytes.

CONCLUSIONS

Restraint stress aggravated allergic airway inflammation in association with alterations in local immunity characterized by greater Th2-associated cytokine production and a reduced development of regulatory T cells, mediated by MORs.

Environmental biodiversity, human microbiota, and allergy are interrelated

Rapidly declining biodiversity may be a contributing factor to another global megatrend--the rapidly increasing prevalence of allergies and other chronic inflammatory diseases among urban populations worldwide. According to the "biodiversity hypothesis," reduced contact of people with natural environmental features and biodiversity may adversely affect the human commensal microbiota and its immunomodulatory capacity. Analyzing atopic sensitization (i.e., allergic disposition) in a random sample of adolescents living in a heterogeneous region of 100 × 150 km, we show that environmental biodiversity in the surroundings of the study subjects' homes influenced the composition of the bacterial classes on their skin. Compared with healthy individuals, atopic individuals had lower environmental biodiversity in the surroundings of their homes and significantly lower generic diversity of gammaproteobacteria on their skin. The functional role of the gram-negative gammaproteobacteria is supported by in vitro measurements of expression of IL-10, a key anti-inflammatory cytokine in immunologic tolerance, in peripheral blood mononuclear cells. In healthy, but not in atopic, individuals, IL-10 expression was positively correlated with the abundance of the gammaproteobacterial genus Acinetobacter on the skin. These results raise fundamental questions about the consequences of biodiversity loss for both allergic conditions and public health in general.

Equine insect bite hypersensitivity: what do we know?

Insect bite hypersensitivity (IBH) is an allergic dermatitis of the horse caused by bites of insects of the genus Culicoides and is currently the best characterized allergic disease of horses. This article reviews knowledge of the immunopathogenesis of IBH, with a particular focus on the causative allergens. Whereas so far hardly any research has been done on the role of antigen presenting cells in the pathogenesis of IBH, recent studies suggest that IBH is characterized by an imbalance between a T helper 2 (Th2) and regulatory T cell (T(reg)) immune response, as shown both locally in the skin and with stimulated peripheral blood mononuclear cells. Various studies have shown IBH to be associated with IgE-mediated reactions against salivary antigens from Culicoides spp. However, until recently, the causative allergens had not been characterized at the molecular level. A major advance has now been made, as 11 Culicoides salivary gland proteins have been identified as relevant allergens for IBH. Currently, there is no satisfactory treatment of IBH. Characterization of the main allergens for IBH and understanding what mechanisms induce a healthy or allergic immune response towards these allergens may help to develop new treatment strategies, such as immunotherapy.

Lactobacillus paracasei Lp6 favors immune modulation induced by allergoid treatment in ragweed sensitized mice

It has been hypothesized that lactic acid bacteria (LAB) could be used as adjuvant for specific immunotherapy (SIT), as various studies conducted on humans and animals converge to define LAB as anti-Th2 modulators and Treg inducers. In the present study we evaluated the effects of LAB, in particular Lactobacillus paracasei Lp6 (Lp6), in a mouse model of ragweed (RW) allergy. Groups of Balb/c mice, experimentally sensitized towards ragweed, were treated by viable Lp6 or by RWallergoid with or without co-administration of Lp6. A control group was sham-sensitized with PBS and sham-treated with water and a group was sensitized with RW and treated with water. Serum IgE, RW-induced release of IFN-gamma, IL-4 and IL-10 from splenocytes and the frequency of CD4CD25 regulatory T cells (Tregs) expressing Foxp3 or IL-10 were evaluated in various groups. RW-allergoid treatment induced a reduction of serum IgE, with a decrease in RW-induced release of IL-4, and an increase in IL-10 and IFN-gamma, along with a significant change in the frequency of Tregs, both CD25+ and -. The joint RWallergoid+ Lp6 treatment induced the highest degree of suppression of allergen-driven IL-4, the greatest reduction of IL-4/IFN-gamma and IL-4/IL-10 ratios and the most significant increase of Foxp3 and IL-10 expressing Tregs. The study shows that Lp6 strengthens the immune modulation induced by allergoid-SIT in RW-sensitized mice, essentially characterized by a differential induction of Tregs associated to a reduction of IL-4; data converge to define a role of SIT adjuvant for Lp6.

A comparative in vitro study of the effects of separate and combined products of Citrus e fructibus and Cydonia e fructibus on immunological parameters of seasonal allergic rhinitis

This paper examined the effects of the combined product, Citrus e fructibus/Cydonia e fructibus (Citrus/Cydonia; Citrus and Cydonia: each 0.01 g/mL), and separate products of Citrus (0.01 g/mL) and Cydonia (0.01 g/mL) on the immunological pathways involved in seasonal allergic rhinitis (SAR). Peripheral blood mononuclear cells (PBMCs) from five healthy and five grass pollen-allergic donors were isolated and analyzed in vitro after polyclonal and allergen-specific stimulation of T cells in the presence of the three extracts. The analyses demonstrated acceptable cell survival with no signs of toxicity. Citrus mainly had a selective effect on reducing allergen-specific chronic inflammatory (TNF-α; Citrus compared to Cydonia and Citrus/Cydonia: −87.4 (P < 0.001) and −68.0 (P < 0.05), resp.) and Th2 pathway activity (IL-5; Citrus compared to Cydonia: −217.8 (P < 0.01); while, both Cydonia and Citrus/Cydonia mainly affected the induction of the allergen-specific Th1 pathway (IFN-γ; Cydonia and Citrus/Cydonia compared to Citrus: 3.8 (P < 0.01) and 3.0 (P < 0.01), resp.). Citrus and Cydonia demonstrated different working mechanisms in the treatment of SAR and the combination product did not demonstrate larger effects than the separate preparations. Further effectiveness and efficacy studies comparing the effects of the products on SAR in vivo are indicated.

Regulatory T-cells: diverse phenotypes integral to immune homeostasis and suppression

Regulatory T-cells (T(REG)) are diverse populations of lymphocytes that regulate the adaptive immune response in higher vertebrates. T(REG) delete autoreactive T-cells, induce tolerance, and dampen inflammation. T(REG) cell deficiency in humans (i.e., IPEX [Immunodysregulation, Polyendocrinopathy and Enteropathy, X-linked syndrome]) and animal models (e.g., "Scurfy" mouse) is associated with multisystemic autoimmune disease. T(REG) in humans and laboratory animal species are similar in type and regulatory function. A molecular marker of and the cell lineage specification factor for T(REG) is FOXP3, a forkhead box transcription factor. CD4(+) T(REG) are either natural (nT(REG)), which are thymus-derived CD4(+)CD25(+)FOXP3(+) T-cells, or inducible (i.e., Tr1 cells that secrete IL-10, Th3 cells that secrete TGF-β and IL-10, and Foxp3(+) Treg). The proinflammatory Th17 subset has been a major focus of research. T(H)17 CD4(+) effector T-cells secrete IL-17, IL-21, and IL-22 in autoimmune and inflammatory disease, and are dynamically balanced with T(REG) cell development. Other lymphocyte subsets with regulatory function include: inducible CD8(+) T(REG), CD3(+)CD4(-)CD8(-) T(REG) (double-negative), CD4(+)Vα14(+) (NKT(REG)), and γδ T-cells. T(REG) have four regulatory modes of action: secretion of inhibitory cytokines (e.g., IL-10 and TGF-β), granzyme-perforin-induced apoptosis of effector lymphocytes, depriving effector T-cells of cytokines leading to apoptosis, or inhibition of dendritic cell function. The role of T(REG) in mucosal sites, inflammation/infection, pregnancy, and cancer as well as a review of T(REG) as a modulatory target in drug development will be covered.

Equine CD4(+) CD25(high) T cells exhibit regulatory activity by close contact and cytokine-dependent mechanisms in vitro

Horses are particularly prone to allergic and autoimmune diseases, but little information about equine regulatory T cells (Treg) is currently available. The aim of this study therefore was to investigate the existence of CD4(+) Treg cells in horses, determine their suppressive function as well as their mechanism of action. Freshly isolated peripheral blood mononuclear cells (PBMC) from healthy horses were examined for CD4, CD25 and forkhead box P3 (FoxP3) expression. We show that equine FoxP3 is expressed constitutively by a population of CD4(+) CD25(+) T cells, mainly in the CD4(+) CD25(high) subpopulation. Proliferation of CD4(+) CD25(-) sorted cells stimulated with irradiated allogenic PBMC was significantly suppressed in co-culture with CD4(+) CD25(high) sorted cells in a dose-dependent manner. The mechanism of suppression by the CD4(+) CD25(high) cell population is mediated by close contact as well as interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) and probably other factors. In addition, we studied the in vitro induction of CD4(+) Treg and their characteristics compared to those of freshly isolated CD4(+) Treg cells. Upon stimulation with a combination of concanavalin A, TGF-β1 and IL-2, CD4(+) CD25(+) T cells which express FoxP3 and have suppressive capability were induced from CD4(+) CD25(-) cells. The induced CD4(+) CD25(high) express higher levels of IL-10 and TGF-β1 mRNA compared to the freshly isolated ones. Thus, in horses as in man, the circulating CD4(+) CD25(high) subpopulation contains natural Treg cells and functional Treg can be induced in vitro upon appropriate stimulation. Our study provides the first evidence of the regulatory function of CD4(+) CD25(+) cells in horses and offers insights into ex vivo manipulation of Treg cells.

Mechanisms of subcutaneous allergen immunotherapy

Allergen-specific immunotherapy (SIT) is the only curative approach in the treatment of allergic diseases defined up-to-date. Peripheral T-cell tolerance to allergens, the goal of successful allergen-SIT, is the primary mechanism in healthy immune responses to allergens. By repeated administration of increased doses of the causative allergen, allergen-SIT induces a state of immune tolerance to allergens through the constitution of T regulatory (Treg) cells, including allergen-specific interleukin (IL)-10-secreting Treg type 1 cells and CD4(+)CD25(+)Treg cells; induction of suppressive cytokines, such as IL-10 and transforming growth factor β; suppression of allergen-specific IgE and induction of IgG4 and IgA; and suppression of mast cells, basophils, eosinophils, and inflammatory dendritic cells. This review summarizes the current knowledge on the mechanisms of allergen-SIT with emphasis on the roles of Treg cells in allergen-SIT.

Clinical tolerance in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) has been a curative therapeutic option for a wide range of immune hematologic malignant and non-malignant disorders including genetic diseases and inborn errors. Once in the host, allogeneic transplanted cells have not only to ensure myeloid repopulation and immunological reconstitution but also to acquire tolerance to host human leukocyte antigens via central or peripheral mechanisms. Peripheral tolerance after allogeneic HSCT depends on several regulatory mechanisms aimed at blocking alloimmune reactivity while preserving immune responses to pathogens and tumor antigens. Patients transplanted with HSCT represent an ideal model system in humans to identify and characterize the key cellular and molecular players underlying these mechanisms. The knowledge gained from these studies has allowed the development of novel therapeutic strategies aimed at inducing long-term peripheral tolerance, which can be applicable not only in allogeneic HSCT but also in autoimmune diseases and solid-organ transplantation. In the present review, we describe Type 1 regulatory T cells, initially discovered and characterized in chimeric patients transplanted with human leukocyte antigen-mismatched HSCT, and how their presence correlates to tolerance induction and maintenance. Furthermore, we summarize different cell therapy approaches with regulatory T cells, designed to facilitate tolerance induction, minimizing pharmaceutical interventions.

Mechanisms of immunotherapy to wasp and bee venom

Hymenoptera venoms are important allergens that can elicit both local and systemic allergic reactions, including life-threatening anaphylaxis. Venom immunotherapy (VIT) remains the most effective treatment, reducing the risk of systemic reactions in individuals with Hymenoptera venom allergy. VIT can restore normal immunity against venom allergens and provide patients with a lifetime of tolerance to venoms. During VIT, peripheral tolerance is induced by the generation of allergen-specific regulatory T (Treg) cells, which suppress proliferative and cytokine responses against the venom allergens. Treg cells are characterized by IL-10 secretion that directly or indirectly influence effector cells of allergic inflammation, such as mast cells, basophils and eosinophils. Treg cells also have influence on B cells, suppressing IgE production and inducing the production of blocking type IgG4 antibodies against venom allergens. An accumulating body of evidence suggests that Treg cells may affect allergen sensitization and methods for enhancing this cell population may eventually improve the efficacy of VIT. In this article, immune mechanisms enrolled in bee and wasp VIT are reviewed.

Specific immunotherapy and turning off the T cell: how does it work?

OBJECTIVE

To examine T-regulatory (Treg) cell functions in allergic immune responses and their roles during allergen specific immunotherapy based on recent developments and current understanding of immune regulation.

DATA SOURCES

PubMed search of English-language articles regarding Treg cells and allergen specific immunotherapy.

STUDY SELECTION

Articles on the subject matter were selected and reviewed.

RESULTS

Allergen specific immunotherapy is the ultimate treatment modality targeting the immunopathogenic mechanisms of allergic disorders. A diminished allergen-specific T-cell proliferation and suppressed secretion of T(H)1- and T(H)2-type cytokines are the characteristic hallmarks. In addition, Treg cells inhibit the development of allergen-specific T(H)2 and T(H)1 cell responses and therefore exert key roles in healthy immune response to allergens. Treg cells potently suppress IgE production and directly or indirectly control the activity of effector cells of allergic inflammation, such as eosinophils, basophils, and mast cells.

CONCLUSION

As advancements in the field of allergen specific immunotherapy ensue, they may provide novel progression of more rational and safer approaches for the prevention and treatment of allergic disorders. Currently, the Treg cell field is an open research area to increase our understanding in mechanisms of peripheral tolerance to allergens.

FOXP3, IL-10, and TGF-β genes expression in children with IgE-dependent food allergy

BACKGROUND

Regulatory T cells (Tregs) have an essential role in tolerance and immune regulation. However, few and controversial data have been published to date on the role and number of these cells in food allergic children. The forkhead/winged-helix transcription factor box protein 3 (FOXP3) is considered the most reliable marker for Tregs.

OBJECTIVE

This study aims to investigate the FOXP3, interleukin (IL)-10, and transforming growth factor (TGF-β) genes expression in children with IgE-dependent food allergy.

MATERIAL AND METHODS

The study group consisted of 54 children with IgE-dependent food allergy (FA) and a control group of 26 non-atopic healthy children. The diagnosis of FA was established using questionnaires, clinical criteria, skin prick tests, serum sIgE antibodies (UniCAP 100 Pharmacia Upjohn), and a double-blind placebo control food challenge. In order to assess gene expression, the isolation of nucleated cells was performed using Histopaque-1077 (Sigma-Aldrich, Germany). The concentration of RNA obtained was measured using a super-sensitive NanoDrop ND1000 spectrophotometer (Thermo Scientific, USA). A reverse transcription reaction was performed using a commercially available set of High Capacity cDNA Archive Kit (Applied Biosystems, USA). Analysis have been carried out in the genetic analyzer 7900HT Real-Time PCR (Applied Biosystems, USA).

RESULTS

The average level of the FOXP3 gene expression in the studied group was 2.19 ± 1.16 and in the control group 2.88 ± 1.66 (p = 0.03). The average level of IL10 mRNA expression in the study group was 13.6 ± 1.07 and was significantly lower than corresponding values in the control group 14.3 ± 1.1 (p = 0.01). There were no significant differences in the average level of the TGF-β mRNA expression in the study group (3.4 ± 0.4) and controls (3.5 ± 0.3; p > 0.05). The FOXP3 gene expression was the highest in children who acquired tolerance to food (3.54 ± 0.75), lower in heated allergen-tolerant children (2.43 ± 0.81), and the lowest in heated allergen-reactive children (1.18 ± 0.5; p = 0.001 control vs heated allergen reactive; p = 0.005 heated allergen tolerant vs heated allergen reactive; p = 0.001 outgrown vs heated allergen reactive). The significant tendency toward lower total IgE levels with a higher FOXP3 mRNA expression was detected (n = 54; Pearson r = -0.4393; p = 0.001).

CONCLUSIONS

Children with FA showed statistically significant lower level of the FOXP3 and IL10 gene expression than healthy children. Children acquiring tolerance to the food show significantly higher levels of the FOXP3 gene expression than children with active FA. The correlation between the level of FOXP3 and total IgE was detected.

Modulation of human immune responses by bovine interleukin-10

Cytokines can be functionally active across species barriers. Bovine IL-10 has an amino acid sequence identity with human IL-10 of 76.8%. Therefore, the aim of this study was to evaluate whether bovine IL-10 has immunomodulatory activities on human monocytes and dendritic cells. Peripheral blood monocytes were isolated from healthy donors, and used directly or allowed to differentiate to dendritic cells under the influence of IL-4 and GM-CSF. Recombinant bovine IL-10 inhibited TLR induced activation of monocytes, and dose-dependently inhibited LPS-induced activation of monocyte-derived DCs comparable to human IL-10. By using blocking antibodies to either bovine IL-10 or the human IL-10 receptor it was demonstrated that inhibition of monocyte activation by bovine IL-10 was dependent on binding of bovine IL-10 to the human IL-10R. These data demonstrate that bovine IL-10 potently inhibits the activation of human myeloid cells in response to TLR activation. Bovine IL-10 present in dairy products may thus potentially contribute to the prevention of necrotizing enterocolitis and allergy, enhance mucosal tolerance induction and decrease intestinal inflammation and may therefore be applicable in infant foods and in immunomodulatory diets.

Clinical practice: Allergen-specific immunotherapy in children: facts and FAQs

Allergen-specific immunotherapy (SIT) in its various application forms represents the main treatment approach of IgE-mediated allergic diseases in adults and children. Despite this clear recommendation, many particularities of products, patient characteristics, and product availability in different countries hamper the use of allergen-specific immunotherapy in particular in children. The frequently asked questions by parents, patients, and physicians are the backbone of this review. Thus, the potentials and limitations of allergen-specific immunotherapy in children and adolescents will be highlighted. IgE-mediated allergic diseases are affecting about 20% of the population. They manifest commonly early in life, and hence, the use of SIT should be considered also early in the course of the disease.

SQ-standardized house dust mite immunotherapy as an immunomodulatory treatment in patients with asthma

BACKGROUND

  Specific immunotherapy is the only treatment with the potential to prevent progression of the allergic disease and the potential to cure patients. The immunomodulatory ability of SQ-standardized house dust mite (HDM) subcutaneous immunotherapy (SCIT) was investigated in patients with allergic asthma.

METHODS

Fifty-four adults with HDM-allergic asthma were randomized 1:1 to receive SQ-standardized HDM SCIT (ALK) or placebo for 3 years. At baseline, and after 1, 2 and 3 years of treatment, the lowest possible inhaled corticosteroid dose required to maintain asthma control was determined, followed by determinations of nonspecific and HDM-allergen-specific bronchial hyperresponsiveness, late asthmatic reaction (LAR), immediate and late-phase skin reactions, and immunological response.

RESULTS

  SQ-standardized HDM SCIT provided a statistically significantly higher HDM-allergen tolerance (P<0.05 vs placebo) in terms of a 1.6-fold increase in PD(20) (HDM-allergen inhalation challenge), a 60-fold increase in skin test histamine equivalent HDM-allergen concentrations, reduced immediate- and reduced or abolished late-phase skin reactions, as well as fewer patients with LAR. PD(20) (methacholine inhalation challenge) increased initially and was similar between groups. House dust mite SCIT induced an initial increase in serum HDM-allergen-specific IgE (P=0.028 vs placebo), which then declined to baseline value. House dust mite SCIT induced an increase in components blocking IgE binding to allergen [ΔIgE-blocking factor: 0.31; 95% CI of (0.26; 0.37)] after 1 year that remained constant after 2 and 3 years (P < 0.0001 vs placebo).

CONCLUSION

  SQ-standardized HDM SCIT induced a consistent immunomodulatory effect in adults with HDM-allergic asthma; the humoral immune response was changed and the HDM-allergen tolerance in lung and skin increased.

What's new in asthma pathophysiology and immunopathology?

Research on asthma pathophysiology over the past decade has expanded the complex repertoire involved in the pathophysiology of asthma to include inflammatory, immune and structural cells, as well as a wide range of mediators. Studies have identified a role for connective and other mesenchymal tissues involved in airway remodeling. Recent findings have implicated the innate immune response in asthma and have revealed interesting patterns of interaction between the innate and adaptive immune response and the associated complex chronic inflammatory reaction. New immune cell populations have also been added to this repertoire, including Tregs, natural killer T cells and Th17 cells. The role of the eosinophil, a prominent pathological feature in most asthma phenotypes, has also been expanding to include roles such as tissue modifiers and immune regulators via a number of fascinating and hitherto unexplored mechanistic pathways. In addition, new and significant roles have been proposed for airway smooth muscle cells, fibroblasts, epithelial and endothelial cells. Tissue remodeling is now considered an integral element of asthma pathophysiology. Finally, an intricate network of mediators, released from both immune and inflammatory cells, including thymus stromal lymphopoietin and matrix metalloproteinases, have added to the complex milieu of asthma immunity and inflammation. These findings have implications for therapy and the search for novel strategies towards better disease management. Sadly, and perhaps due to the complex nature of asthma, advances in therapeutic discoveries and developments have been limited. Thus, understanding the precise roles played by the numerous dramatis personae in this odyssey, both individually and collectively within the context of asthma pathophysiology, continues to pose new challenges. It is clear that the next stage in this saga is to embark on studies that transcend reductionist approaches to involve system analysis of the complex and multiple variables involved in asthma, including the need to narrow down the phenotypes of this condition based on careful analysis of the organs (lung and airways), cells, mediators and other factors involved in bronchial asthma.

Ara h 2 peptides containing dominant CD4+ T-cell epitopes: candidates for a peanut allergy therapeutic

BACKGROUND

Peanut allergy is a life-threatening condition; there is currently no cure. Although whole allergen extracts are used for specific immunotherapy for many allergies, they can cause severe reactions, and even fatalities, in peanut allergy.

OBJECTIVE

This study aimed to identify short, T-cell epitope-based peptides that target allergen-specific CD4(+) T cells but do not bind IgE as candidates for safe peanut-specific immunotherapy.

METHODS

Multiple CD4(+) T-cell lines specific for the major peanut allergen Ara h 2 were generated from PBMCs of 16 HLA-diverse subjects with peanut allergy by using 5,6-carboxyfluorescein diacetate succinimidylester-based methodology. Proliferation and ELISPOT assays were used to identify dominant epitopes recognized by T-cell lines and to confirm recognition by peripheral blood T cells of epitope-based peptides modified for therapeutic production. HLA restriction of core epitope recognition was investigated by using anti-HLA blocking antibodies and HLA genotyping. Serum-IgE peptide-binding was assessed by dot-blot.

RESULTS

Five dominant CD4(+) T-cell epitopes were identified in Ara h 2. In combination, these were presented by HLA-DR, HLA-DP, and HLA-DQ molecules and recognized by T cells from all 16 subjects. Three short peptide variants containing these T-cell epitopes were designed with cysteine-to-serine substitutions to facilitate stability and therapeutic production. Variant peptides showed HLA-binding degeneracy, did not bind peanut-specific serum IgE, and could directly target T(H)2-type T cells in peripheral blood of subjects with allergy.

CONCLUSION

Short CD4(+) T-cell epitope-based Ara h 2 peptides were identified as novel candidates for a T-cell-targeted peanut-specific immunotherapy for an HLA-diverse population.

Fusion protein of TLR5-ligand and allergen potentiates activation and IL-10 secretion in murine myeloid DC

Toll-like receptor ligands are immune-modulatory components linking innate and adaptive immune responses and are considered to be promising vaccine components. Objective of this study was to investigate the adjuvant activity of Listeria monocytogenesis-derived TLR5-ligand flagellin A (flaA) genetically fused to ovalbumin (Ova, major chicken white egg allergen) in a murine in vitro system. Recombinant flaA, rOva, and a fusion protein of rflaA and rOva (rflaA:Ova) were over-expressed in Escherchia coli and purified by FPLC. LPS depletion was confirmed by LAL test. TLR5-binding was evaluated by human and murine TLR5-transgenic HEK 293 cells. The immune-modulatory effect of rflaA:Ova and rflaA:Ova modified by reduction and alkylation on purified BALB/c bone marrow-derived myeloid (mDC) and plasmacytoid dendritic cells (pDC) was investigated by flow cytometry and intracellular cytokine staining (ICS). Dose-dependent IL-8 secretion from transgenic HEK 293 cells confirmed binding of rflaA and rflaA:Ova molecules to human and murine TLR5. Recombinant flaA showed similar biological reactivity to TLR5-ligand fliC derived from Salmonella typhimurium applied as positive control. Compared to rflaA, both rflaA:Ova preparations induced higher expression of maturation markers (CD40, CD69, CD80, and CD86) on mDC, whereas only CD69 and CD40 were upregulated on pDC. Moreover, IL-6 and IL-10 production by mDC was enhanced upon stimulation with rflaA:Ova constructs in comparison to an equimolar mixture of both proteins whereas pDC did not show secretion of the investigated cytokines. Any immunological effects of LPS can be excluded by depletion of endotoxins and the lack of IL-10 production upon proteinase K digestion of rflaA:Ova. In summary, the rflaA:Ova fusion proteins showed an enhanced immune modulating capacity in comparison to rflaA or the mixture of rflaA and antigen. Since the rflaA:Ova fusion proteins induce strong IL-10 induction they are considered as potential vaccine candidates to improve allergen-specific immunotherapy.

Chronic helminth infections protect against allergic diseases by active regulatory processes

Developed countries are suffering from an epidemic rise in immunologic disorders, such as allergy-related diseases and certain autoimmunities. Several studies have demonstrated a negative association between helminth infections and inflammatory diseases (eg, allergy), providing a strong case for the involvement of helminth infections in this respect. However, some studies point in the opposite direction. The discrepancy may be explained by differences in frequency, dose, time, and type of helminth. In this review, new studies are discussed that may support the concept that chronic helminth infections in particular—but not acute infections—are associated with the expression of regulatory networks necessary for downmodulating allergic immune responses to harmless antigens. Furthermore, different components of regulatory networks are highlighted, such as the role of regulatory T and B cells, modulation of dendritic cells, early innate signals from structural cells (eg, epithelial cells), and their individual contributions to protection against allergic diseases. It is of great interest to define and characterize specific helminth molecules that have profound immunomodulatory capacities as targets for therapeutic application in the treatment or prophylaxis of allergic manifestations.

CD25 appears non essential for human peripheral T(reg) maintenance in vivo

Background

IL-2 has been reported to be critical for peripheral T_reg survival in mouse models. Here, we examined T_reg maintenance in a series of paediatric liver transplant recipients who received basiliximab, a therapeutic anti-CD25 monoclonal antibody.

Methodology/Principal Findings

FoxP3⁺ CD4 T cells were analyzed by flow cytometry before liver grafting and more than 9 months later. We found that in vivo CD25 blockade did not lead to T_reg depletion: the proportion of FoxP3⁺ cells among CD4 T cells and the level of FoxP3 expression were both unchanged. IL-2Rβ expression was enhanced in FoxP3⁺ cells both before and after basiliximab treatment, while the level of IL-2Rγ expression was similar in T_regs and non-T_regs. No significant change in the weak or absent expression of IL-7Rα and IL-15Rα expression on FoxP3⁺ cells was observed. Although the proportion of FoxP3⁺ cells among CD4 T cells did not vary, food allergies occurred more rapidly after liver grafting in patients who received basiliximab, raising questions as to T_reg functionality in vivo in the absence of functional CD25.

Conclusions

CD25 appears non essential for human T_reg peripheral maintenance in vivo. However, our results raise questions as to T_reg functionality after therapeutic CD25 targeting.