Rationale for new treatments aimed at IgE immunomodulation

Biomarkers and mechanisms of tolerance induction in food allergic patients drive new therapeutic approaches

Immunotherapy for food-allergic patients has been effective in inducing desensitization in some populations, but long-term tolerance has remained an elusive target. A challenge facing our field is how to differentiate immune markers that are impacted by immunotherapy from those that are critical biomarkers of tolerance. Data from recent clinical trials have identified several biomarkers and mechanisms for achieving tolerance. These biomarkers include younger age, lower food-specific IgE, lower food component-specific IgE, specific linear epitope profiles, and subsets of food-specific CD4+ T cells. Additional biomarkers under investigation for their relevance in tolerance induction include TCR repertoires, gastrointestinal and skin microbiome, and local tissue immunity. This mini-review highlights recent advances in understanding biomarkers and mechanisms of tolerance induction in food immunotherapy and how these are influencing clinical trial development.

Assessing the effect of 5-hydroxymethylfurfural on selected components of immune responses in mice immunised with ovalbumin

BACKGROUND

5-Hydroxymethylfurfural (5-HMF) is one of the most important products of the Maillard reaction. In recent years, many profitable biological effects of this compound have been demonstrated. This study sought to elucidate the anti-allergic effect of 5-HMF by investigating some selected components of the immune response in BALB/c mice immunised with ovalbumin (OVA).

RESULTS

Immunised animals had an increased level of serum total and OVA-specific antibodies when compared to the control (P < 0.01).We found that the OVA-induced increase in serum IgE and OVA-specific IgE were significantly suppressed in the groups treated with 5-HMF (P < 0.05). Moreover, interleukin-4 (IL-4) and interferon gamma (IFN-γ) were significantly reduced in a dose-independent manner when compared to the sensitised group (P < 0.05).

CONCLUSION

5-HMF inhibited the up-regulation of total and OVA-specific IgE through the suppression of the Th2-type immune response in immunised BALB/c mice. 5-HMF could therefore be a novel therapeutic approach for the prevention of IgE-mediated allergic diseases. © 2017 Society of Chemical Industry.

Zerumbone enhances the Th1 response and ameliorates ovalbumin-induced Th2 responses and airway inflammation in mice

Zerumbone is a sesquiterpene compound isolated from the rhizome of wild ginger, Zingiber zerumbet Smith. The rhizomes of the plant are used as a spice and traditional medicine. Zerumbone was shown to possess anticarcinogenic, anti-inflammatory, and antioxidant properties. However, the antiallergic activity and the underlying mechanism of zerumbone have not been reported. Herein, we investigated the immunomodulatory effects of zerumbone on antigen-presenting dendritic cells (DCs) in vitro and its potential therapeutic effects against ovalbumin (OVA)-induced T helper 2 (Th2)-mediated asthma in mice. In the presence of zerumbone, lipopolysaccharide-activated bone marrow-derived DCs enhanced T cell proliferation and Th1 cell polarization in an allogeneic mixed lymphocyte reaction. In animal experiments, mice were sensitized and challenged with OVA, and were orally treated with different doses of zerumbone after sensitization. Circulating titers of OVA-specific antibodies, airway hyperresponsiveness to methacholine, histological changes in lung tissues, the cell composition and cytokine levels in bronchoalveolar lavage fluid, and cytokine profiles of spleen cells were assessed. Compared to OVA-induced hallmarks of asthma, oral administration of zerumbone induced lower OVA-specific immunoglobulin E (IgE) and higher IgG2a antibody production, attenuated airway hyperresponsiveness, prevented eosinophilic pulmonary infiltration, and ameliorated mucus hypersecretion. Zerumbone treatment also reduced the production of eotaxin, keratinocyte-derived chemokine (KC), interleukin (IL)-4, IL-5, IL-10, and IL-13, and promoted Th1 cytokine interferon (IFN)-γ production in asthmatic mice. Taken together, these results suggest that zerumbone exhibits an antiallergic effect via modulation of Th1/Th2 cytokines in an asthmatic mouse model.

Low serum IgA and increased expression of CD23 on B lymphocytes in peripheral blood in children with regressive autism aged 3-6 years old

INTRODUCTION

Immune system dysfunction is considered to be one of many medical disorders found in children with autism. The primary objective of the study was to assess if blood tests reflecting humoral immunity (IgA, IgG, IgM, IgE) are useful in identifying children with regressive autism. The secondary objective was to evaluate a part of the cellular arm of immunity (CD4/CD25 Tregs, CD4/CD23 cells) in those children.

MATERIAL AND METHODS

Using a clinical case-control design, the systemic levels of immunoglobulins and lymphocyte subpopulations analysed by flow cytometry were compared in children aged 3-6 years old with a new diagnosis of regressive autism (n = 24; mean age: 4.25 ±1.70 years; male 23/24) and in sex- and age-matched healthy children (n = 24; aged 4.25 ±2.20 years; male 23/24).

RESULTS

The humoral immunity profile, described by three binary variables, IgA < 0.97 g/l, IgE > 36 IU/ml, and IgG > 6.3 g/l, with a sensitivity of 79% and a specificity of 83% (p < 0.0001), was able to identify children with autism. The highest risk of autism diagnosis was associated with IgA < 0.97g/l (OR - 23.0; p < 0.001). A higher number of CD19/CD23 was found in children diagnosed with autism than in the control group (36.82 ±6.72% vs. 18.20 ±3.95%; p < 0.02). No correlation between the number of CD23-positive cells and serum IgE levels was observed.

CONCLUSIONS

A subtle shift of serum immunoglobulins consisting of low-normal IgA and B cell activation expressed by an increase of CD23-positive cells may characterize children with regressive autism aged 3-6 years old.

Natural killer T cells regulate the development of asthma

Studies in mice, monkeys and humans suggest that invariant natural killer (iNK) T cells play a very important role in the pathogenesis of asthma, a heterogeneous disease associated with airway inflammation and airway hyper-reactivity. The requirement for iNK T cells in multiple mouse models of asthma is novel and surprising, challenging the prevailing dogma that CD4(+) T cells responding to environmental allergens are the key cell type in asthma. In this article, we examine the recent studies of iNK T cells and asthma, and discuss how different subsets of NK T cells function in different forms of asthma, including forms that are independent of adaptive immunity and Th2 cells. Together, these studies suggest that iNK T cells, which can interact with many other cell types including Th2 cells, eosinophils and neutrophils, provide a unifying pathogenic mechanism for many distinct forms of asthma.

Genetic variability of the high-affinity IgE receptor alpha-subunit (FcepsilonRIalpha)

Our knowledge on the variability of FCER1A gene encoding for alpha-subunit of the high-affinity immunoglobulin E receptor (FcepsilonRI) that plays a central role in the pathogenesis of allergy and related disorders, has been recently much extended. Last findings from FCER1A mutational screening and genetic association studies, followed by functional analyses of the polymorphisms, are briefly summarized in this mini-review. The association between FCER1A gene variants and total serum IgE levels seems especially interesting and, supported by functional analyses of polymorphisms, may provide a rationale for pharmacogenetic studies on anti-IgE therapy that indirectly suppresses FcepsilonRI expression.

Efficacy and safety of omalizumab in an Asian population with moderate-to-severe persistent asthma

BACKGROUND AND OBJECTIVE

The efficacy and safety of the anti-IgE antibody, omalizumab, has been widely studied in patients with asthma. However to date, no large studies have been performed in Asian populations. The aim of this study was to compare the efficacy and safety of omalizumab with placebo, as add-on therapy in Asian patients with moderate-to-severe persistent asthma.

METHODS

Japanese patients (20-75 years of age) with uncontrolled asthma, despite receiving high-dose inhaled corticosteroids and other standard therapies, were randomized to receive add-on treatment with omalizumab or placebo in a 16-week, double-blind, parallel-group, multicentre study.

RESULTS

Altogether, 315 treated patients were included in the efficacy and safety analyses. The change from baseline in morning PEF was 15.45 L/min (least squares mean) with omalizumab versus 2.25 L/min with placebo, a statistically significant difference of 13.19 L/min (P = 0.0004). Clinically significant asthma exacerbations occurred in six patients (4.0%) treated with omalizumab and in 18 patients (11.0%) treated with placebo. The odds ratio for the risk of experiencing an asthma exacerbation was 0.32 in favour of omalizumab (P = 0.0192). Changes in asthma symptom scores, daily life activity scores, sleep scores and rescue medication use were in favour of omalizumab, but group differences did not reach statistical significance. Adverse event rates were similar between omalizumab and placebo, except for injection site reactions, which were more frequently observed in the omalizumab group.

CONCLUSIONS

Add-on treatment with omalizumab improved asthma control without significant adverse events in Japanese patients with moderate-to-severe persistent asthma.

Inhibitory effect of DA-9201, an extract of Oryza sativa L., on airway inflammation and bronchial hyperresponsiveness in mouse asthma model

Asthma is one of the major public health problems worldwide and the morbidity and mortality of asthma has increased in the past two decades. Accumulating data suggest that unnecessary immune responses and inflammation should be suppressed to treat asthma. The purpose of this study is to investigate the anti-asthmatic effects of DA-9201, an ethanolic extract of black rice (Oryza sativa L. var japonica), on an ovalbumin (OVA)-induced mouse model of asthma. Balb/c mice immunized with OVA were administered with DA-9201 (30, 100 or 300 mg/kg, p.o.) or dexamethasone (3 mg/kg, p.o.) and challenged with 1% aerosolized OVA for 30 min. The effects on airway inflammation, airway hyperresponsiveness (AHR), antibody profiles and cytokines were evaluated. DA-9201 treatment significantly reduced the number of eosinophils in bronchoalveolar lavage fluid (BALF) and ameliorated the AHR. Lung histological features also showed that DA-9201 reduced airway inflammation. Furthermore, DA-9201 treatment decreased IFN-gamma as well as IL-4, IL-5 and IL-13 levels in the supernatant of cultured splenocytes, and suppressed the level of OVA-specific IgG, IgG2a, IgG1 and total IgE in plasma. DA-9201 showed anti-asthmatic effects by suppressing unnecessary immune responses, airway inflammation, eosinophilia, AHR and IgE level. These results suggest DA-9201 might be beneficial for the treatment of asthma.

Production of interleukin-10 in asthmatic children after Beta-1-3-glucan

BACKGROUND

Beta-1-3 Glucan is a polysaccharide extracted from Saccharomyces cerevisiae with a possible immunomodulating action that may have a favourable action on asthma symptoms and other allergic diseases. An experimental study carried out using a murine respiratory model detected a decrease in pulmonary tissue eosinophilia, as well as an increase in Interleukin-10 (IL-10) after glucan use.

METHODS

This open, exploratory study with blind outcome evaluation included asthmatic children between 6 and 12 years of age with mild to moderate persistent asthma and inadequate disease control (rescue medication needed more than twice a week) in spite of inhaled budesonide 400 microg/day. After a four week run-in period, subcutaneous Beta-1-3-glucan injections were given weekly for the first four weeks and then every two weeks for the last four weeks. IL-10 levels, measured by the immunoenzymatic method (ELISA), were compared before and after glucan administration.

RESULTS

Twenty patients (14 male and 6 female) were included. Mean IL-10 levels were 6.4 pg/ml and 11.3 pg/ml before and after glucan, respectively (p = 0.02). There was also a reduction of asthmatic symptoms score at the end of study.

CONCLUSIONS

This is the first study which shows that subcutaneous particulate Beta-1-3-glucan increases serum IL-10 levels in asthmatics. The possibility of glucan being able to modulate allergic sensitisation and having a beneficial action in restoring Th2 function should be assessed by means of properly planned controlled clinical trials, as it may represent a new therapeutic strategy.

Circulating CD23+ B cell subset correlates with the development of resistance to Schistosoma mansoni reinfection in occupationally exposed adults who have undergone multiple treatments

BACKGROUND

Elevated immunoglobulin E (IgE) levels are often associated with resistance to reinfection in human schistosomiasis. However, Although B cells are the source of schistosome-specific IgE, little is known about B cell subsets or their functions in this infection. We evaluated B cells and their expression of the low-affinity IgE receptor (CD23) in a unique cohort of men occupationally exposed to Schistosoma mansoni and longitudinally followed up through multiple treatments with praziquantel, cures, and reinfections.

METHODS

Resistance levels were calculated on the basis of documented water exposure and reinfection data over many years. The CD23(+) B cell subset was evaluated in whole blood by flow cytometry. Serum antibody isotype and soluble CD23 (sCD23) concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Expression of membrane CD23 (mCD23) on B cells correlated with the development of resistance against S. mansoni. Higher levels of plasma sCD23, the cleaved form of mCD23, also correlated with resistance and other markers of resistance to reinfection, such as eosinophilia.

CONCLUSIONS

CD23 may be involved in the development of resistance to schistosome infection through its role in IgE regulation. Understanding these complex host-parasite interactions may lead to insights into the development, mechanisms, and regulation of resistance to reinfection with S. mansoni.

Levocetirizine modulates lymphocyte activation in patients with allergic rhinitis

Levocetirizine, a second generation non-sedating antihistamine that blocks the H(1) histamine receptor, may exhibit immunoregulatory properties that augment its primary pharmacological mechanism. To investigate this possibility, 13 Kuwaiti seasonal allergic rhinitis (SAR) patients were treated with levocetirizine for four weeks in comparison with a 7-member placebo-treated control group, followed by clinical evaluation and flow cytometric analysis of peripheral venous blood for inflammatory cell and lymphocyte subpopulation profiles. Relative to the controls, levocetirizine-treated patients exhibited an expected reduction in early phase allergic symptoms, including sneezing (P<0.001), nasal itching (P<0.01), nasal congestion, and running nose (P<0.001); reduced percentages of eosinophils (P<0.05); and three subpopulations of activated T lymphocytes: CD4+CD29+, CD4+CD212+, and CD4+CD54+ (P<0.05). Levocetirizine treatment also correlated with a significant increase in the percentage of CD4+CD25+ T cells (P<0.001). The ability of levocetirizine to reduce percentage representation of cell phenotypes known to contribute to inflammatory tissue damage (eosinophils, CD4+CD29+, CD4+CD212+, and CD4+CD54+) and expand percentages of CD4+CD25+, which may include protective immunoregulatory (Treg) cells, indicates that the drug has pharmacological potential beyond the immediate effects of H(1) histamine-receptor inhibition. Although the present data does not define a therapeutic mechanism, the results reported here establish important trends that may be used to guide future mechanistic examination of immunoregulatory capacity of H(1) inhibitors.

Eosinophils in bronchial mucosa of asthmatics after allergen challenge: effect of anti-IgE treatment

BACKGROUND

Anti-IgE, omalizumab, inhibits the allergen response in patients with asthma. This has not been directly related to changes in inflammatory conditions. We hypothesized that anti-IgE exerts its effects by reducing airway inflammation. To that end, the effect of anti-IgE on allergen-induced inflammation in bronchial biopsies in 25 patients with asthma was investigated in a randomized, double-blind, placebo-controlled study.

METHODS

Allergen challenge followed by a bronchoscopy at 24 h was performed at baseline and after 12 weeks of treatment with anti-IgE or placebo. Provocative concentration that causes a 20% fall in forced expiratory volume in 1 s (PC(20)) methacholine and induced sputum was performed at baseline, 8 and 12 weeks of treatment. Changes in the early and late responses to allergen, PC(20), inflammatory cells in biopsies and sputum were assessed.

RESULTS

Both the early and late asthmatic responses were suppressed to 15.3% and 4.7% following anti-IgE treatment as compared with placebo (P < 0.002). This was paralleled by a decrease in eosinophil counts in sputum (4-0.5%) and postallergen biopsies (15-2 cells/0.1 mm(2)) (P < 0.03). Furthermore, biopsy IgE+ cells were significantly reduced between both the groups, whereas high-affinity IgE receptor and CD4+ cells were decreased within the anti-IgE group. There were no significant differences for PC(20) methacholine.

CONCLUSION

The response to inhaled allergen in asthma is diminished by anti-IgE, which in bronchial mucosa is paralleled by a reduction in eosinophils and a decline in IgE-bearing cells postallergen without changing PC(20) methacholine. This suggests that the benefits of anti-IgE in asthma may be explained by a decrease in eosinophilic inflammation and IgE-bearing cells.

Cysteinyl-leukotrienes and their receptors in asthma and other inflammatory diseases: critical update and emerging trends

Cysteinyl-leukotrienes (cysteinyl-LTs), that is, LTC4, LTD4, and LTE4, trigger contractile and inflammatory responses through the specific interaction with G protein-coupled receptors (GPCRs) belonging to the purine receptor cluster of the rhodopsin family, and identified as CysLT receptors (CysLTRs). Cysteinyl-LTs have a clear role in pathophysiological conditions such as asthma and allergic rhinitis (AR), and have been implicated in other inflammatory conditions including cardiovascular diseases, cancer, atopic dermatitis, and urticaria. Molecular cloning of human CysLT1R and CysLT2R subtypes has confirmed most of the previous pharmacological characterization and identified distinct expression patterns only partially overlapping. Interestingly, recent data provide evidence for the immunomodulation of CysLTR expression, the existence of additional receptor subtypes, and of an intracellular pool of CysLTRs that may have roles different from those of plasma membrane receptors. Furthermore, genetic variants have been identified for the CysLTRs that may interact to confer risk for atopy. Finally, a crosstalk between the cysteinyl-LT and the purine systems is being delineated. This review will summarize and attempt to integrate recent data derived from studies on the molecular pharmacology and pharmacogenetics of CysLTRs, and will consider the therapeutic opportunities arising from the new roles suggested for cysteinyl-LTs and their receptors.

Role of vitamin A elimination or supplementation diets during postnatal development on the allergic sensitisation in mice

Vitamin A (VA) and its derivatives, the retinoids, are important factors for the development of the immune system. It has been shown in adult animals that proliferation of lymphocyte populations and antibody secretion are retinoid dependent, while little is known about the effects of retinoids during postnatal development. The aim of this study was to investigate the role of VA on allergic sensitisation during lactation and after weaning using an in vivo system for postnatal allergic sensitisation in mice. Different VA diets (basal/VA elimination/VA (as retinyl palmitate) supplemented) were fed to the dams throughout lactation and directly to the pups after weaning. Allergic sensitisation was induced with a single peritoneal ovalbumin (OVA) injection at day 28 after weaning. The phenotype of lymphocytes was analysed by flow cytometry and functional data were obtained by analysis of (IL-4/IFN-gamma) cytokine production and antibody production (OVA-specific IgG1 and IgE) in the offspring. VA/retinyl palmitate supplementation during lactation and after weaning decreased CD3+, CD4+, CD8+ and B220+ populations in splenic lymphocytes but also significantly enhanced IL-4 production and OVA-specific IgE after sensitisation. In contrast, mice fed VA-elimination diet displayed no significant alteration of lymphocyte numbers and a slightly increased IL-4 production. Our results showed that a single allergen injection during postnatal development induces allergic sensitisation whose degree is modified by the VA content of the maternal diet during lactation and the diet of the pups after weaning, indicating an important role of VA on the severity of the allergic sensitisation.

Anti-IgE antibodies for the treatment of IgE-mediated allergic diseases

The pharmacological purposes of the anti-IgE therapy are to neutralize IgE and to inhibit its production to attenuate type I hypersensitivity reactions. The therapy is based on humanized IgG1 antibodies that bind to free IgE and to membrane-bound IgE on B cells, but not to IgE bound by the high-affinity IgE.Fc receptors on basophils and mast cells or by the low-affinity IgE.Fc receptors on B cells. After nearly 20 years since inception, therapeutic anti-IgE antibodies (anti-IgE) have been studied in about 30 Phase II and III clinical trials in many allergy indications, and a lead antibody, omalizumab, has been approved for treating patients (12 years and older) with moderate-to-severe allergic asthma. Anti-IgE has confirmed the roles of IgE in the pathogenesis of asthma and helped define the concept "allergic asthma" in clinical practice. It has been shown to be safe and efficacious in treating pediatric allergic asthma and treating allergic rhinitis and is being investigated for treating peanut allergy, atopic dermatitis, latex allergy, and others. It has potential for use to combine with specific and rush immunotherapy for increased safety and efficacy. Anti-IgE thus appears to provide a prophylactic and therapeutic option for moderate to severe cases of many allergic diseases and conditions in which IgE plays a significant role. This chapter reviews the evolution of the anti-IgE concept and the clinical studies of anti-IgE on various disease indications, and presents a comprehensive analysis on the multiple intricate immunoregulatory pharmacological effects of anti-IgE. Finally, it reviews other approaches that target IgE or IgE-expressing B cells.

Cost-Efficacy Comparison among Three Antiretroviral Regimens in??HIV-1 Infected, Treatment-Experienced Patients

BACKGROUND AND OBJECTIVE

In the face of increasing antiretroviral (ARV) treatment options and costs, payers are progressively challenged with prioritising resources. The cost effectiveness of the ARV agent enfuvirtide has been shown to be comparable to that of other available HIV treatment strategies, based on Markov modeling. However, an evaluation of enfuvirtide treatment costs that considers the impact of virological and immunological responses to therapy may provide a more clinically meaningful perspective for primary HIV healthcare providers. The aim of this study was to assess the cost per unit change in efficacy (HIV RNA decreases and CD4 count increases) of three different ARV regimens for triple class-experienced HIV-1 infected patients using actual drug costs and data from randomised, controlled clinical trials.

STUDY DESIGN

The analysis included three steps. First, re-analysis of 48-week clinical trial data (T-20 vs Optimized Regimen Only [TORO]) to allow for a more direct comparison of enfuvirtide versus other commonly used ARV agents. All patients included in the re-analysis received a common optimised background (COB) regimen of three drugs: two nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) and a ritonavir-boosted protease inhibitor (PI), lopinavir. HIV RNA levels and CD4 count changes were determined for three patient groups according to the treatment received - group 1: COB + enfuvirtide; group 2: COB + PI; group 3: COB + NRTI + PI. The second step of the analysis involved calculating the annualised regimen costs ($US wholesaler acquisition cost) for each patient group. In the third step, cost-efficacy ratios were calculated and compared between groups: (a) the annualised regimen cost ($US)/change in viral load from baseline, and (b) the annualised regimen cost ($US)/change in CD4+ cell count from baseline.

RESULTS

One hundred and fifty-seven patients were included in this previously unplanned secondary analysis (group 1: 79 patients; group 2: 42 patients; group 3: 36 patients). HIV RNA and CD4 count changes from baseline to week 48 were -1.80, -0.89 and -0.61 log(10) copies/mL (p < 0.001 for enfuvirtide vs each non-enfuvirtide group) and +102, +57 and +52 cells/mm(3) (p < 0.05 for enfuvirtide versus each non-enfuvirtide subgroup) for groups 1, 2 and 3, respectively. The annualised costs of the combination therapies were $US 35,624, $US 27,549 and $US 30,624; and the costs per 0.50 log(10) copies/mL HIV RNA decrease were $US 9,872, $US 15,542 and $US 24,907 (p < 0.05 for enfuvirtide vs each non-enfuvirtide subgroup) for groups 1, 2 and 3, respectively. The costs per 25 cells/mm(3) CD4 count increase were $US 8,722, $US 12,127 and $US 14,636 for subgroups 1, 2 and 3, respectively. Similar patterns in regimen cost per unit change were achieved after adjusting for baseline prognostic variables. The incremental cost-efficacy ratios for group 1 versus the combination of groups 2 and 3 were $US 3,124 for HIV RNA reduction and $US 3,239 for CD4 count increase.

CONCLUSION

Enfuvirtide-containing regimens are associated with higher cost as well as improved virological and immunological outcomes when compared with alternative four- and five-drug regimens. When costs and outcomes are considered jointly, an enfuvirtide-based regimen is more cost efficacious than alternative regimens in this patient population.

Lead and immune function

The heavy metal lead is a widely deposited environmental toxicant known to impact numerous physiological systems, including the reproductive, neurological, hepatic, renal, and immune systems. Studies illustrating the capacity of lead to impair immune function and/or host resistance to disease date back to at least the 1960s. However, it has only been in recent years that lead has been recognized among a new category of immunotoxicants-those that dramatically shift immune functional capacity while producing only modest changes to immune cell populations and lymphoid organs. These relatively noncytotoxic immunomodulating chemicals and drugs represent the immunotoxic hazards most difficult to identify and problematic for risk assessment using historic approaches. As a result, such environmental factors are also among the most likely to contribute to chronic immune-related disease at relevant exposure levels. This review considers the animal and human evidence that lead exposure can produce a stark shift in immune functional capacity with a skewing predicted to elevate the risk of atopic and certain autoimmune diseases. At the same time, host defenses against infectious agents and cancer may be reduced. Age-based exposure studies also suggest that levels of blood lead previously thought to be safe, that is, below 10 microg/dl, may be associated with later life immune alterations.

B-cell targeting in rheumatoid arthritis and other autoimmune diseases

B-cell-targeted therapy for autoimmune disease emerged from theoretical proposition to practical reality between 1997 and 1998, with the availability of the B-cell-depleting monoclonal antibody rituximab. Since then, a score of autoantibody-associated disorders have been treated, with most convincing evidence of efficacy seen in subjects with rheumatoid arthritis. Several classes of B-cell-targeted agent are now under investigation. From the outset, a major goal of B-cell targeting has been the re-establishment of some form of immunological tolerance. In some subjects, the observed improvement of disease for years following therapy fuels hope that this goal might ultimately be achievable.

Design, synthesis, and structure-activity relationships of 1-,3-,8-, and 9-substituted-9-deazaxanthines at the human A2B adenosine receptor

Over two hundred 1-, 3-, 8-, and 9-substituted-9-deazaxanthines were prepared and evaluated for their binding affinity at the recombinant human adenosine receptors, in particular at the hA(2B) and hA(2A) subtypes. Several ligands endowed with sub-micromolar to low nanomolar binding affinity at hA(2B) receptors, good selectivity over hA(2A) and hA(3), but a relatively poor selectivity over hA(1) were obtained. Good antagonistic potencies and efficacies, with pA(2) values close to the corresponding pK(i)s, were observed in functional assays in vitro performed on a selected series of compounds. 1,3-Dimethyl-8-phenoxy-(N-p-halogenophenyl)-acetamido-9-deazaxanthine derivatives appeared as the most interesting leads, some of them showing outstanding hA(2B) affinities, high selectivity over hA(2A) and hA(3), but low selectivity over hA(1). Structure-affinity relationships suggested that the binding potency at the hA(2B) receptor was mainly modulated by the steric (lipophilic) properties of the substituents at positions 1 and 3 and by the electronic and lipophilic characteristics of the substituents at position 8. A comparison among affinity and selectivity profiles of 9-deazaxanthines with the corresponding xanthines suggested some possible differences in their binding mode.

Production of biologically active recombinant human soluble CD23 and its effect on PBMCs isolated from hyper-IgE blood

A recombinant form of human soluble CD23 (sCD23), the low affinity receptor for IgE (FcepsilonRII), was produced by PCR cloning the lectin-binding domain sequence into a bacterial expression vector. After renaturation and purification, the sCD23 bound IgE and divalent metal ions, indicating its activity. The recombinant human sCD23 exhibited similar proinflammatory properties as the native protein. Although interleukin-1beta, tumour necrosis factor-alpha, and nuclear factor-kappaB appeared not to be enhanced significantly in unstimulated RPMI 8866 B-lymphoblastoid and U937 promonocytic cell lines with 24 h incubation of recombinant sCD23, they were produced in both healthy and hyper-IgE-derived peripheral blood mononuclear cells, especially tumour necrosis factor-alpha. This study concludes that while recombinant and chimeric sCD23 may be useful in blocking IgE binding to immune cells and decreasing IgE synthesis by B-lymphocytes, the production of proinflammatory cytokines, particularly tumour necrosis factor-alpha will enhance immune responses in cases of asthma, allergy, and hyper-IgE syndrome.

Antigen-specific targeting and elimination of EBV-transformed B cells by allergen toxins

BACKGROUND

With the exception of antigen-specific immunotherapy, current treatments for atopic diseases provide only symptomatic relief. Because of the increasing incidence of such diseases, the development of novel strategies and concepts for the treatment of allergies is urgently needed.

OBJECTIVE

Here we present a new approach for the treatment of atopic diseases. The strategy is comparable to the application of immunotoxins in cancer therapy, in which a cytotoxic peptide is coupled to a cancer cell-specific antibody fragment or ligand. In the case of so-called allergen toxins (ATs), the target cell-specific moiety is an allergen or allergen-derived fragment, which should be bound only by allergen-reactive cells. After receptor-mediated internalization, allergen-specific cells are killed, and the allergic pathogenesis is interrupted.

METHODS

Proof of the AT principle was shown by using a human ex vivo system in which EBV was used to transform human B cells specific for the timothy grass pollen allergen Phl p 5b. The AT is composed of the major B-cell and T-cell epitopes of the Phl p 5b (P5) allergen fused to a truncated form of the highly toxic Pseudomonas aeruginosa exotoxin A (ETA').

RESULTS

Allergen-specific and nonspecific B cells were challenged with P5-ETA', but only the Phl p 5b-reactive B cells showed selective binding and cytotoxicity.

CONCLUSION

This approach represents an initial step toward a novel therapeutic strategy in the treatment of atopic diseases.

Leptin promotes differentiation and survival of human dendritic cells and licenses them for Th1 priming

Leptin is an adipocyte-derived hormone/cytokine that links nutrition, metabolism, and immune homeostasis. Leptin is capable of modulating several immune responses. However, the effect of leptin on dendritic cells (DCs) has not yet been recognized. Because DCs are instrumental in the development of immune responses, in this study, we evaluated the impact of leptin on DC activation. We demonstrated the presence of leptin receptor in human immature and mature DCs both at mRNA and protein level and its capacity to transduce leptin signaling leading to STAT-3 phosphorylation. We found no consistent modulation of DC surface molecules known to be critical for their APC function in response to leptin. In contrast, we found that leptin induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. At a functional level, leptin up-regulates the IL-1beta, IL-6, IL-12, TNF-alpha, and MIP-1alpha production. Coincident with this, leptin-treated DCs stimulate stronger heterologous T cell responses. Furthermore, we found that leptin down-regulates IL-10 production by DCs and drives naive T cell polarization toward Th1 phenotype. Finally, we found that leptin partly protects DCs from spontaneous and UVB-induced apoptosis. Consistent with the antiapoptotic effect of leptin, we observed the activation of NF-kappaB and a parallel up-regulation of bcl-2 and bcl-x(L) gene expression. These results provide new insights on the immunoregulatory function of leptin demonstrating its ability to improve DC functions and to promote DC survival. This is of relevance considering a potential application of leptin in immunotherapeutic approaches and its possible use as adjuvant in vaccination protocols.