Anti-T-cell strategies in the treatment of allergic disease

A protective allergy vaccine based on CpG- and protamine-containing PLGA microparticles

PURPOSE

Allergen-specific immunotherapy (SIT) requires dozens of subcutaneous injections over 3 to 5 years in order to control IgE-mediated hypersensitivity, which is a T-helper 2 (Th2)-associated pathology. This study investigates the use of poly(lactide-co-glycolide) (PLGA) microparticles combined with immunostimulatory oligodeoxynucleotide (CpG), as well as protamine in SIT.

MATERIALS AND METHODS

We prepared microparticle formulations with the major allergen of bee venom, phospholipase A2 (PLA2), and analyzed the effect of co-encapsulated or admixed CpG in both naïve and bee venom allergic mice.

RESULTS

Mice immunized with microparticles containing only PLA2 induced weak antibody responses. In contrast, the combination with CpG resulted in strong PLA2-specific antibody responses. The presence of CpG was required for the induction of the Th1-associated isotype IgG2a, and the titers of IgG2a in sensitized mice correlated with a better protection against an allergen challenge. The effect of CpG was further strengthened when protamine was co-encapsulated for complexation of CpG.

CONCLUSIONS

This study shows that allergen-specific immunotherapy with a PLGA-based allergen-delivery system in combination with CpG enhanced the induction of protective IgG2a immune responses. This may improve SIT compliance and shorten its duration.

Biological assay using T cell response for Cry-consensus peptide designed for the peptide-based immunotherapy of Japanese cedar pollinosis

INTRODUCTION

Cry-consensus peptide is a linearly linked peptide of T-cell epitopes for the management of Japanese cedar (JC) pollinosis and is expected to become a new drug for immunotherapy. However, the mechanism of T-cell epitopes in allergic diseases is not well understood, and thus, a simple in vitro procedure for evaluation of its biological activity is desired.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from 27 JC pollinosis patients and 10 healthy subjects, and cultured in vitro for 4 days in the presence of Cry-consensus peptide and (3)H-thymidine. The relationship between growth stimulation (stimulation index; SI) and antigen-specific IgE levels in serum was also investigated in JC pollinosis patients. Moreover, to confirm the importance of the primary sequence in Cry-consensus peptide, heat-treated Cry-consensus peptide and a mixture of the amino acids of which Cry-consensus peptide is composed, and their (3)H-thymidine uptake was compared with Cry-consensus peptide. Finally, whether Cry-consensus peptide stimulates PBMCs from healthy subjects was investigated.

RESULTS

The mean SI of JC patients showed a good correlation with Cry-consensus peptide concentration in the culture medium; however, the SI was independent of the anti-Cry j 1 IgE level. Heat-denatured Cry-consensus peptide retained a PBMC proliferation stimulatory effect comparable to the original Cry-consensus peptide, while the mixture of amino acids constituting Cry-consensus peptide did not stimulate PBMC proliferation. PBMCs from healthy subjects did not respond to Cry-consensus peptide at all.

DISCUSSION

These data indicate that the PBMC response of patients suffering from JC pollinosis to Cry-consensus peptide is specific for the sequence of T cell epitopes thereof and may be useful for the evaluation of the efficacy of Cry-consensus peptide in vivo.

Is Genetic Vaccination against Allergy Possible?

Genetic immunization has proven a powerful method to induce antiallergic immune responses. The underlying functional principle has been described to be based on the recruitment of allergen-specific Th1 cells, CD8+ cells and the establishment of a Th1 cytokine milieu, which prevent the development of a Th2-biased response in a protective setup and can balance an ongoing Th2-type response in a therapeutic situation. Genetic immunization with plasmid DNA offers innovative solutions to the major problems associated with protein immunization, such as crosslinking of pre-existing immunoglobulin E on mast cells/basophils or induction of de novo synthesis of immunoglobulin E by the protein immunization itself. It easily enables the routine production of hypoallergenic vaccines, which do not translate native allergens, thus avoiding potential anaphylactic side effects. DNA vaccines can also be applied as mixtures of single vaccines, making them interesting candidates for treatment based on component-resolved diagnosis, followed by an individualized therapy with the relevant allergens. In addition to the description of up-to-date allergen gene vaccine approaches, this review gives an overview of animal studies dealing with the following topics: danger signals as the inherent adjuvant properties, methods to optimize the vaccine immunogenicity, modulation of the immune response, nonparenteral applications and low-dose vaccination strategies.

Characterization of the T-cell epitopes of a major peanut allergen, Ara h 2

BACKGROUND

The development of safe and effective immunotherapy for peanut allergy has been complicated by the high anaphylactic potential of native peanut extracts. We sought to map the T-cell epitopes of the major peanut allergen, Ara h 2 in order to develop T-cell targeted vaccines.

METHODS

A panel of eight peanut-specific CD4+ T-cell lines (TCL) was derived from eight peanut-allergic subjects and proliferative and cytokine responses to stimulation with a set of overlapping 20-mer peptides representing the entire sequence of Ara h 2 determined. Proliferation was assessed in 72 h assays via tritiated thymidine incorporation, while interleukin (IL)-5 and interferon (IFN)-gamma production were assessed via sandwich enzyme-linked immunosorbent assay (ELISA) of cell culture supernatants.

RESULTS

Eight of the 17 Ara h 2 peptides were recognized by one or more subjects, with the two peptides showing highest reactivity [Ara h 2 (19-38) and Ara h 2 (73-92)] being recognized by three subjects each. Adjoining peptides Ara h 2 (28-47) and Ara h 2 (100-119) induced proliferative responses in two subjects. Each of these peptides was associated with a Th2-type cytokine response.

CONCLUSION

Two highly immunogenic T-cell reactive regions of Ara h 2 have been identified, Ara h 2 (19-47) and Ara h 2 (73-119), providing scope for the development of safe forms of immunotherapy for peanut allergy.

New advances and potential therapies for the treatment of asthma

Asthma is a disease of the airways with an underlying inflammatory component. The prevalence and healthcare burden of asthma is still rising and is predicted to continue to rise in the current century. Inhaled beta(2)-adrenoceptor agonists and corticosteroids form the basis of the treatments available to alleviate the symptoms of asthma. There is a need for novel, safe treatments to tackle the underlying inflammation that characterizes asthma pathology. Furthermore, there is a requirement for new treatments to be developed as oral therapy in order to alleviate patient compliance issues, especially in children. A multitude of new approaches and new targets are being investigated, which may provide opportunities for novel therapeutic interventions in this debilitating disease. For simplicity, these approaches can be divided into two categories. The first comprises therapies directed against specific components or steps seen in allergic asthma. By 'components' we mean the key inflammatory cells (T cells [in particular T(h)2], B cells, eosinophils, mast cells, basophils and antigen presenting cells [APC]) and mediators (immunoglobulin E [IgE], cytokines, histamines, leukotrienes and prostanoids) believed to be involved in the chronic inflammation seen in asthma. By 'steps' we mean the allergic response, such as antigen processing and presentation, T(h)2-cell activation, B-cell isotype switching, mast cell involvement and airway remodeling. The other category of novel approaches to disease modification in asthma encompasses general anti-inflammatory therapies including phosphodiesterase 4 (PDE4) inhibitors, p38 mitogen-activated protein kinase (MAPK) inhibitors, peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists, and lipoxins.

Novel therapies for the treatment of inflammatory airway disease

Asthma and chronic obstructive pulmonary disease (COPD) are diseases of the airways with an underlying inflammatory component. The prevalence and healthcare burden of asthma and COPD is still rising and is predicted to continue to rise in the current century. The beta-agonists and corticosteroids form the basis of the treatments available to alleviate the symptoms of asthma, whereas the treatments available for COPD have been shown to have a limited effect on slowing the progression of the disease. Asthma and COPD are both in need of novel, safe treatments to tackle the underlying inflammation that characterises their pathology. The inflammatory processes inherent in asthma and COPD provide the opportunity for innovative drug research. This review will outline the new approaches and targets being investigated, which may provide opportunities for novel therapeutic interventions in these debilitating diseases.