Allergen-specific immunotherapy: update on immunological mechanisms

Immunogenicity of a novel anti-allergic vaccine based on house dust mite purified allergens and a combination adjuvant in a murine prophylactic model

The outer-membrane-derived proteoliposome (PL) of Neisseria meningitidis has been reported as a potent vaccine adjuvant, inducing a Th1-skewed response. This work aimed to assess the immunogenicity of a novel anti-allergic vaccine candidate based on allergens from Dermatophagoides siboney house dust mite and a combination adjuvant containing PL and Alum. In a preventative experimental setting, BALB/c mice were administered with three doses containing 2 µg of Der s1 and 0.4 µg Der s2 allergen, PL and Alum, at 7 days intervals, by subcutaneous route. Furthermore, mice were subjected to an allergen aerosol challenge for 6 consecutive days. Serum IgE, IgG1, and IgG2a allergen-specific antibodies were assessed by ELISA. Cytokine levels in supernatants of D. siboney stimulated lymphocyte cultures and in bronchoalveolar lavage (BAL) were measured by ELISA. Lung tissues were subjected to histological examination. The vaccine prevented the development of both, systemic (IgE) and local allergic responses (featuring lower IL-4, and IL-5 levels in BAL) upon allergen exposure by the inhalant route. Histological examination showed also a diminished allergic inflammatory response in the lungs. After the allergen challenge, cytokine levels in stimulated lymphocyte cultures showed lower values of IL-13 and augmented IFN-γ and IL-10. The vaccine induced a mixed IgG2a/IgG1 antibody response; although only IgG2a was PL-dependent. Both, IgG1/IgE and IgG2a/IgE ratios, showed significantly greater values in vaccinated mice. The findings support a preventative anti-allergic effect associated with the induction of a Th1-like IFN-γ/IL-10 response. IgG1/IgE and IgG2a/IgE ratios could be useful biomarkers for translation into clinical trials.

Protective effects of Surfacen® in allergen-induced asthma mice model

Airway obstruction with increased airway resistance in asthma, commonly caused by smooth muscle constriction, mucosal edema and fluid secretion into the airway lumen, may partly be due to a poor function of pulmonary surfactant. Surfacen®, a clinical pulmonary surfactant, has anti-inflammatory action, but its effect on asthma has not been studied. This work aimed to evaluate the effect of Surfacen® in a murine allergen-induced acute asthma model, using house dust mite allergens. In a therapeutic experimental setting, mice were first sensitized by being administered with two doses (sc) of Dermatophagoides siboney allergen in aluminum hydroxide followed by one intranasal administration of the allergen. Then, sensitized mice were administered with aerosol of hypertonic 3% NaCl, Salbutamol 0.15 mg/kg, or Surfacen® 16 mg in a whole-body chamber on days 22, 23, and 24. Further, mice were subjected to aerosol allergen challenge on day 25. Surfacen® showed bronchial dilation and inhibition of Th2 inflammation (lower levels of IL-5 and IL-13 in broncoalveolar lavage) which increased IFN-γ and unchanged IL-10 in BAL. Moreover, Sufacen® administration was associated with a marked inhibition of the serum specific IgE burst upon allergen exposure, as well as, IgG2a antibody increase, suggesting potential anti-allergy effects with inclination towards Th1. These results support also the effectiveness of the aerosol administration method to deliver the drug into lungs. Surfacen® induced a favorable pharmacological effect, with a bronchodilator outcome comparable to Salbutamol, consistent with its action as a lung surfactant, and with an advantageous anti-inflammatory and anti-allergic immunomodulatory effect.

Pistacia weinmannifolia root exerts a protective role in ovalbumin‑induced lung inflammation in a mouse allergic asthma model

Pistacia weinmannifolia (Anacardiaceae) has been used in herbal medicine for the treatment of influenza, dysentery and enteritis in China. It was recently observed that P. weinmannifolia root extract (PWRE) exerts anti‑inflammatory effects both in in vitro and in vivo models. Based on the results from previous studies, the present study investigated the protective effect of PWRE on airway inflammation and mucus hypersecretion. Treatment with PWRE significantly decreased the number of eosinophils and the levels of Th2 cytokines, such as interleukin (IL)‑4, IL‑5 and IL‑13, in the bronchoalveolar lavage fluid (BALF) of OVA‑exposed mice. PWRE decreased the high serum levels of total and OVA‑specific immunoglobulin E. PWRE also effectively inhibited the influx of inflammatory cells into the lung, as well as airway mucus hypersecretion. In addition, the increased level of monocyte chemoattractant protein‑1 was significantly decreased with the PWRE treatment in the BALF of OVA‑exposed mice and in lipopolysaccharide‑stimulated RAW264.7 macrophages. These protective effects of PWRE on OVA‑induced pulmonary inflammation were accompanied by the downregulation of mitogen associated protein kinases and nuclear factor‑κB activation. Thus, the results from the present study indicate that PWRE could be valuable adjuvant for the treatment of asthma.

Suppressive Effect of 4-Hydroxy-2-(4-Hydroxyphenethyl) Isoindoline-1,3-Dione on Ovalbumin-Induced Allergic Asthma

4-Hydroxy-2-(4-hydroxyphenethyl)isoindoline-1,3-dione (PD1) is a synthetic phthalimide derivative of a marine compound. PD1 has peroxisome proliferator-activated receptor (PPAR) γ agonistic and anti-inflammatory effects. This study aimed to investigate the effect of PD1 on allergic asthma using rat basophilic leukemia (RBL)-2H3 mast cells and an ovalbumin (OVA)-induced asthma mouse model. In vitro, PD1 suppressed β-hexosaminidase activity in RBL-2H3 cells. In the OVA-induced allergic asthma mouse model, increased inflammatory cells and elevated Th2 and Th1 cytokine levels were observed in bronchoalveolar lavage fluid (BALF) and lung tissue. PD1 administration decreased the numbers of inflammatory cells, especially eosinophils, and reduced the mRNA and protein levels of the Th2 cytokines including interleukin (IL)-4 and IL-13, in BALF and lung tissue. The severity of inflammation and mucin secretion in the lungs of PD1-treated mice was also less. These findings indicate that PD1 could be a potential compound for anti-allergic therapy.

Effects of anthraquinones from Cassia occidentalis L. on ovalbumin-induced airways inflammation in a mouse model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Cassia occidentalis Linn. is a traditional ayruvedic edible shrub containing anthraquinones (AQs) as the principle active constituents. In folk medicine, it has a variety of uses including treatment of whooping cough ('pertussis') and inflammatory diseases. Despite these applications, limited data are available to validate the effects of C. occidentalis AQs on airways inflammation in asthma.

AIM OF THE STUDY

To explore the anti-inflammatory potential of AQs extracted from C. occidentalis using an in vivo model of ovalbumin (OVA)-induced asthma.

MATERIALS AND METHODS

Extraction and optimization of AQs from C. occidentalis was performed by mechanochemistry. Allergic asthma in BALB/c mice was sensitized and challenged by OVA, and the effects of AQs investigated in a mouse model. OVA-specific IgE concentrations in serum, and Th1/Th2 cytokine (IL-4, IL-5, IL-13 and IFN-γ) concentrations, inflammatory cell counts and classification in bronchoalveolar lavage fluid (BALF) were determined. Histopathological evaluation of lung tissue was performed using hematoxylin and eosin (H&E), and periodic acid-schiff (PAS) staining. Th1/Th2 cytokine mRNA expression was analyzed using the 2^-ΔΔCt method.

RESULTS

Treatment with AQs decreased inflammatory cell counts and production of Th2 cytokines (IL-4, IL-5 and IL-13) in BALF, and OVA-specific IgE in serum. In contrast,Th1 cytokine IFN-γ production in BALF was promoted. AQs also decreased mRNA expression of Th1/Th2 cytokine in lung tissue. Histological studies demonstrated that AQs substantially inhibited OVA-induced cellular infiltration, mucus hypersecretion and goblet cell hyperplasia in the lung.

CONCLUSIONS

These findings demonstrated the inhibitory effects of AQs, derived from C. occidentalis, on OVA-induced allergic asthma in mice. The results suggest a promising ethnopharmacological use for AQs in patients with asthma.

Next generation immunotherapy for tree pollen allergies

Tree pollen induced allergies are one of the major medical and public health burdens in the industrialized world. Allergen-Specific Immunotherapy (AIT) through subcutaneous injection or sublingual delivery is the only approved therapy with curative potential to pollen induced allergies. AIT often is associated with severe side effects and requires long-term treatment. Safer, more effective and convenient allergen specific immunotherapies remain an unmet need. In this review article, we discuss the current progress in applying protein and peptide-based approaches and DNA vaccines to the clinical challenges posed by tree pollen allergies through the lens of preclinical animal models and clinical trials, with an emphasis on the birch and Japanese red cedar pollen induced allergies.

Effect of polymorphisms on TGFB1 on allergic asthma and helminth infection in an African admixed population

BACKGROUND

Allergic asthma is a complex disorder that results from a combination of genetic and environmental factors. Studies suggest that helminth infections can activate a regulatory network characterized by the production of regulatory cytokines, such as interleukin 10 and transforming growth factor β1 (TGF-β1) and subsequently protect against immune-mediated diseases, such as asthma. On the other hand, TGF-β1 is increased in the lungs of individuals with asthma and may modulate airway inflammation. The role of TGF- β 1 single-nucleotide polymorphisms (SNPs) in allergic disease remains inconclusive.

OBJECTIVE

To evaluate the effects of genetic variations in the TGF-β1 on allergy and helminths infections in children.

METHODS

We tested for association among 4 TGF-β1 SNPs and allergic asthma, specific IgE, skin prick test result, and IL-10 production in 1,335 Brazilians. In addition, we analyzed the association with markers of helminth infection (parasite burden, anti-Ascaris IgE, and worm specific IgG4). The polymorphisms were genotyped using Taq Man probes.

RESULTS

We found an association between rs1800470 (C allele) and atopic wheezing (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.37-0.95) and markers of allergy (OR, 0.41; 95% CI, 0.22-0.79). In contrast, a positive association was observed between the haplotype ACCA and Trichuris trichiura infection (OR, 1.85; P = .003) and Ascaris lumbricoides infection (OR, 2.01; P < .001). This haplotype was also associated with increased IL-10 production (β = 50.7; P < .001).

CONCLUSION

Individuals with TGF-β1 polymorphisms have an increased susceptibility to helminth infections and a lower risk of developing allergy. These studies suggest that immune modulation of allergic disease results not only from environmental factors but also from genetic susceptibility and IL-10 production.

Evidence in immunotherapy for paediatric respiratory allergy: Advances and recommendations

Allergic respiratory diseases are major health problems in paediatric population due their high level of prevalence and chronicity, and to their relevance in the costs and quality of life. One of the most important risk factors for the development of airway diseases in children and adolescents is atopy. The mainstays for the treatment of these diseases are avoiding allergens, controlling symptoms, and preventing them through sustained desensitization by allergen immunotherapy (AIT). AIT is a treatment option that consists in the administration of increasing amounts of allergens to modify the biological response to them, inducing long-term tolerance even after treatment has ended. This treatment approach has shown to decrease symptoms and improve quality of life, becoming cost effective for a large number of patients. In addition, it is considered the only treatment that can influence the natural course of the disease by targeting the cause of the allergic inflammatory response. The aim of this publication is to reflect the advances of AIT in the diagnosis and treatment of allergic respiratory diseases in children and adolescents reviewing articles published since 2000, establishing evidence categories to support the strength of the recommendations based on evidence. The first part of the article covers the prerequisite issues to understand how AIT is effective, such as the correct etiologic and clinical diagnosis of allergic respiratory diseases. Following this, the article outlines the advancements in understanding the mechanisms by which AIT achieve immune tolerance to allergens. Administration routes, treatment regimens, dose and duration, efficacy, safety, and factors associated with adherence are also reviewed. Finally, the article reviews future advances in the research of AIT.

The Use of Adjuvants for Enhancing Allergen Immunotherapy Efficacy

One key approach to increase the efficacy and the safety of immunotherapy is the use of adjuvants. However, many of the adjuvants currently in use can cause adverse events, raising concerns regarding their clinical use, and are geared toward productive immune responses but not necessarily tolerogenic responses. Thus, novel adjuvants for immunotherapy are needed and are being developed. Essential is their potential to boost appropriate tolerogenic adaptive immune responses to allergens while limiting side effects. This review provides an overview of adjuvants currently in clinical use or under development and discusses their therapeutic effect in enhancing allergen-induced tolerance.

Optimum treatment strategies for polyallergic patients - analysis of a large observational trial

OBJECTIVES

To document the effectiveness and safety of sublingual allergen immunotherapy (SLIT) with a five-grass pollen tablet (Oralair ) and compare different treatment options in a broad, non-selected population of patients in a real-world clinical setting.

RESEARCH DESIGN AND METHODS

This was a 2 year, open, prospective, multicenter, single-arm, non-interventional study. Patients with a history of clinically relevant allergic symptoms caused by grass pollen, confirmed by skin prick testing, received treatment with the five-grass pollen tablet. Concomitant treatment with symptomatic medication and/or additional SLIT or subcutaneous immunotherapy (SCIT) was permitted. Twelve-month data are presented here. Effectiveness was assessed comparing a combined rhinoconjunctivitis (RC) score derived from the severity of rhinitis and conjunctivitis symptoms under treatment with retrospective data of the previous year.

RESULTS

A total of 1408 patients participated in the study, of whom 434 were children/adolescents and 962 polyallergic. Compared with the grass pollen season preceding five-grass pollen tablet treatment, a statistically significant reduction of 49.9% was achieved in RC score for the total population (p < 0.001), and an improvement in overall health was perceived by 90.9% of patients. The overall population of polyallergic patients derived similar benefits from treatment with the five-grass pollen tablet as monoallergic patients. The percentage reduction in RC score was larger in polyallergic patients taking no additional therapy (60.2%) than in those taking concomitant symptomatic medication (38.1%) or allergen immunotherapy (AIT) (50.8%). Within the last of these groups, RC score improved by 47.6% among patients receiving additional SCIT, versus 54.8% with additional SLIT. Adverse drug reactions, reported in 15.3% of study participants, were mostly local in nature and mild or moderate in intensity.

CONCLUSIONS

After 1 year of treatment, polyallergic patients responded similarly to the five-grass pollen tablet as monoallergic patients. For polyallergic patients in whom additional treatment was needed, a second SLIT may be more beneficial than a SCIT or symptomatic co-medication.

The natural compound nujiangexanthone A suppresses mast cell activation and allergic asthma

Mast cells play an important role in allergic diseases such as asthma, allergic rhinitis and atopic dermatitis. The genus Garcinia of the family Guttiferae is well known as a prolific source of polycyclic polyprenylated acylphloroglucinols and bioactive prenylated xanthones, which exhibit various biological activities including antibacterial, antifungal, anti-inflammatory, antioxidant, and cytotoxic effects. Nujiangexanthone A (N7) is a novel compound isolated from the leaves of Garcinia nujiangensis. In this paper, we sought to determine the anti-allergic and anti-inflammation activity of N7 in vivo and its mechanism in vitro. We found N7 suppressed IgE/Ag induced mast cell activiation, including degranulation and production of cytokines and eicosanoids, through inhibiting Src kinase activity and Syk dependent pathways. N7 inhibited histamine release, prostaglandin D2 and leukotriene C4 generation in mast cell dependent passive cutaneous anaphylaxis animal model. We also found N7 inhibited the IL-4, IL-5, IL-13 and IgE levels in ovalbumin-induced asthma model. Histological studies demonstrated that N7 substantially inhibited OVA-induced cellular infiltration and increased mucus production in the lung tissue. Our study reveals the anti-allergic function of N7, thereby suggesting the utility of this compound as a possible novel agent for preventing mast cell-related immediate and delayed allergic diseases.

IgG anti-IgA antibodies in paediatric antibody-deficient patients receiving intravenous immunoglobulin

BACKGROUND

Immunoglobulin replacement therapy is an effective route of management for both infections and non-infectious complications in predominantly antibody deficiency (PAD). Trace levels of IgA (ranged from 0.4 to 2500 mg/ml), which exist in all immunoglobulin products, could lead to an increased susceptibility for adverse reactions in PAD patients. Furthermore, the exact mechanism which stimulates the anti-IgA antibody production in PAD is still unknown. The aim of this study was to evaluate IgG anti-IgA antibodies in PAD patients receiving intravenous immunoglobulin (IVIg) and its predisposing factors.

METHODS

Available patients with confirmed diagnosis of PAD, who underwent regular IVIg replacement therapy in our centre, were enrolled in the study. Control group included 24 healthy individuals as the negative control and eight symptomatic patients with IgA deficiency as the positive control groups. IgG anti-IgA antibodies level was measured by the ELISA method.

RESULTS

A significant difference was observed between Anti-IgA level of common variable immunodeficiency (CVID) and other PAD groups (p=0.02). Moreover, six CVID patients were seropositive for the IgG anti-IgA antibody, with higher susceptibility to the adverse reactions (p<0.001). IgG anti-IgA level has a negative relationship with serum IgA level (r=-0.06) and IVIg treatment duration (r=-0.006).

CONCLUSION

Our data suggested that there was a significant association between anti-IgA antibody presence and the adverse reactions, especially in CVID patients with higher susceptibility to produce this constitutional antibody.

A Phase I clinical trial with subcutaneous immunotherapy vaccine of Timothy grass pollen extract according to EMA guidelines

Aim: A double-blind placebo-controlled study was conducted according to EMA guidelines, to evaluate safety, tolerability and short-term treatment effects of three up-dosing regimens of Phleum pratense subcutaneous immunotherapy. Materials & methods: Forty-two patients were randomized to groups: A (6 weekly doses), B (8 weekly doses) or C (eight doses, two clustered increasing doses over 3 weeks). Results: The most frequent adverse events were local reactions. No serious adverse events were found. Higher number and more severe systemic reactions were reported in group C. A decrease in cutaneous responses and an increase of specific antibodies was shown in all active groups even at very short-term. Conclusion: Phleum pratense subcutaneous immunotherapy in depot presentation exhibited good safety and tolerability. Group A seemed to show the best profile.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.