Mechanisms of specific immunotherapy of allergic diseases

In silico structural analysis of group 3, 6 and 9 allergens from Dermatophagoides farinae

Dermatophagoides farinae (Hughes; Acari: Pyroglyphidae) are the predominant source of dust mite allergens, which provoke allergic diseases, such as rhinitis, asthma and eczema. Of the 30 allergen groups produced by D. farinae, the Der f 3, Der f 6 and Der f 9 allergens are all trypsin‑associated proteins, however little else is currently known about them. The present study used in silico tools to compare the amino acid sequences, and predict the secondary and tertiary structures of Der f 3, Der f 6 and Der f 9 allergens. Protein sequence alignment detected ~46% identity between Der f 3, Der f 6 and Der f 9. Furthermore, each protein was shown to contain three active sites and two highly conserved trypsin functional domains. Predictions of the secondary and tertiary structure identified α‑helices, β‑sheets and random coils. The active sites of the three proteins appeared to fold onto each other in a three‑dimensional model, constituting the active site of the enzyme. Epitope analysis demonstrated that Der f 3, Der f 6 and Der f 9 have 4‑5 potential epitopes located in random coils, and the epitope sequences of Der f 3, Der f 6 and Der f 9 were shown to overlap in two domains (at amino acids 83‑87 and 179‑180); however the residues in these two domains were not identical. The present study aimed to conduct a biochemical and genetic analysis of these three allergens, and to potentially contribute to the development of vaccines for allergen‑specific immunotherapy.

Allergen-specific IgG antibodies purified from mite-allergic patients sera block the IgE recognition of Dermatophagoides pteronyssinus antigens: an in vitro study

One of the purposes of specific immunotherapy (SIT) is to modulate humoral immune response against allergens with significant increases in allergen-specific IgG levels, commonly associated with blocking activity. The present study investigated in vitro blocking activity of allergen-specific IgG antibodies on IgE reactivity to Dermatophagoides pteronyssinus (Dpt) in sera from atopic patients. Dpt-specific IgG antibodies were purified by ammonium sulfate precipitation followed by protein-G affinity chromatography. Purity was checked by SDS-PAGE and immunoreactivity by slot-blot and immunoblot assays. The blocking activity was evaluated by inhibition ELISA. The electrophoretic profile of the ammonium sulfate precipitated fraction showed strongly stained bands in ligand fraction after chromatography, compatible with molecular weight of human whole IgG molecule. The purity degree was confirmed by detecting strong immunoreactivity to IgG, negligible to IgA, and no reactivity to IgE and IgM. Dpt-specific IgG fraction was capable of significantly reducing levels of IgE anti-Dpt, resulting in 35%–51% inhibition of IgE reactivity to Dpt in atopic patients sera. This study showed that allergen-specific IgG antibodies purified from mite-allergic patients sera block the IgE recognition of Dermatophagoides pteronyssinus antigens. This approach reinforces that intermittent measurement of serum allergen-specific IgG antibodies will be an important objective laboratorial parameter that will help specialists to follow their patients under SIT.

Allergen-specific subcutaneous immunotherapy in allergic asthma: immunologic mechanisms and improvement

Allergic asthma is a disease characterized by persistent allergen-driven airway inflammation, remodeling, and airway hyperresponsiveness. CD4(+) T-cells, especially T-helper type 2 cells, play a critical role in orchestrating the disease process through the release of the cytokines IL-4, IL-5, and IL-13. Allergen-specific immunotherapy (SIT) is currently the only treatment with a long-term effect via modifying the natural course of allergy by interfering with the underlying immunological mechanisms. However, although SIT is effective in allergic rhinitis and insect venom allergy, in allergic asthma it seldom results in complete alleviation of the symptoms. Improvement of SIT is needed to enhance its efficacy in asthmatic patients. Herein, the immunoregulatory mechanisms underlying the beneficial effects of SIT are discussed with the ultimate aim to improve its treatment efficacy.

Injection and sublingual immunotherapy in the management of allergies affecting the unified airway

The spectrum of allergic disease involves both the upper and lower airways. Immunotherapy has been shown to produce immunologic changes that can result in the improvement of allergic diseases. Numerous clinical trials have demonstrated the effectiveness of injection and sublingual immunotherapy in the treatment of rhinitis and asthma. Recent data suggest that immunotherapy may have a role in preventing the development of new sensitizations or in decreasing the progression of allergic disease from rhinitis to asthma. Models of immunotherapy may therefore transition from symptom-relieving treatments to preventive methodologies for the management of allergic disease.

Induction of tolerance after establishment of peanut allergy by the food allergy herbal formula-2 is associated with up-regulation of interferon-?

BACKGROUND

Peanut (PN)-anaphylaxis is potentially life threatening. We previously reported that a Chinese herbal medicine preparation, food allergy herbal formula-2 (FAHF-2), prevented peanut allergy (PNA) in mice when administered during sensitization.

OBJECTIVE

To investigate whether FAHF-2 also can prevent anaphylactic reactions when administered to mice with established PNA and, if so, whether protection would persist after cessation of therapy.

METHODS

C3H/HeJ mice sensitized and boosted over 8 weeks with a standard protocol known to establish PN hypersensitivity received seven weeks of FAHF-2 treatment or water as a sham treatment. Mice were subsequently challenged with PN at week 14 (1-day post-therapy) and week 18 (4-week post-therapy) to evaluate the efficacy and persistence of FAHF-2 treatment by assessing anaphylactic scores, core body temperatures and plasma histamine levels. Serum PN-specific antibody levels and cytokine profiles from splenocytes and mesenteric lymph node (MLN) cells were also determined.

RESULTS

All sham-treated mice challenged at weeks 14 and 18 showed anaphylactic symptoms. In contrast, FAHF-2-treated mice showed no sign of anaphylactic reactions. PN-specific IgE levels in FAHF-2-treated mice also were reduced whereas IgG2a levels were increased. Furthermore, MLN cells from FAHF-2-treated mice produced markedly less IL-4 and IL-5, but more IFN-gamma, and contained increased numbers of IFN-gamma-producing CD8+ cells as compared with sham-treated mice.

CONCLUSION

FAHF-2 treatment established PN tolerance in this model, which persisted for at least 4-week post-treatment. This result was associated with modulation of intestinal T helper type 1 cell (Th1) and Th2 cytokine production, and with increased numbers of mesenteric IFN-gamma-producing CD8+ cells.

Allergenic characteristics of a modified peanut allergen

Attempts to treat peanut allergy using traditional methods of allergen desensitization are accompanied by a high risk of anaphylaxis. The aim of this study was to determine if modifications to the IgE-binding epitopes of a major peanut allergen would result in a safer immunotherapeutic agent for the treatment of peanut-allergic patients. IgE-binding epitopes on the Ara h 2 allergen were modified, and modified Ara h 2 (mAra h 2) protein was produced. Wild-type (wAra h 2) and mAra h 2 proteins were analyzed for their ability to interact with T-cells, their ability to bind IgE, and their ability to release mediators from a passively sensitized RBL-2H3 cell line. Multiple T-cell epitopes were identified on the major peanut allergen, Ara h 2. Ara h 2 amino acid regions 11-35, 86-125, and 121-155 contained the majority of peptides that interact with T-cells from most patients. The wAra h 2 and mAra h 2 proteins stimulated proliferation of T-cells from peanut-allergic patients to similar levels. In contrast, the mAra h 2 protein exhibited greatly reduced IgE-binding capacity compared to the wild-type allergen. In addition, the modified allergen released significantly lower amounts of beta-hexosaminidase, a marker for IgE-mediated RBL-2H3 degranulation, compared to the wild-type allergen.

Tolerance and short-term effect of a cluster schedule with pollen-extracts quantified in mass-units

We performed a prospective, multicenter study to assess the tolerance and possible short-term effects of allergen vaccines administered according to a cluster schedule in the months immediately preceding the onset of the pollen season. The study was carried out in eight centers and included 191 patients (children and adults) with allergic respiratory disease due to sensitization to olive tree and/or grass pollen. Of these, 34 patients acted as controls and the remaining patients received immunotherapy administered in the initiation phase according to a cluster schedule of eight doses injected on four visits. After 3 months of treatment, significant differences were found between the two groups in medication consumption (antihistamines in drops and oral formulations: p = 0.045 and p = 0.001, respectively; short-acting beta2-agonist treatments: p = 0.004) and respiratory symptoms (wheezing and coughing: p = 0.035 and 0.014, respectively). The cytokine profile (interleukin [IL]-4, 5, 10 and 2, interferon [IFN-gamma], and tumor necrosis factor [TNF-alpha]) was determined before the start of treatment and at the end of follow-up (4-5 months). Levels of IL-4, 5 and 10 (Th2 profile) decreased while those of IL-2, IFN-gamma, and TNF-alpha (Th1 profile) decreased. These differences were more marked in the active group than in the control group but were not statistically significant. No severe adverse effects were recorded. This study shows that the schedule tested had an acceptable tolerance profile and produced significant changes in symptom and medication scores after a few months of treatment. A double-blind, placebo-controlled study is needed to confirm these results.

Persistent protective effect of heat-killed Escherichia coli producing "engineered," recombinant peanut proteins in a murine model of peanut allergy

BACKGROUND

Peanut allergy (PNA) is a life-threatening food allergy for which there is no definitive treatment.

OBJECTIVE

We investigated the long-term immunomodulatory effect of heat-killed Escherichia coli producing engineered (mutated) Ara h1, 2, and 3 (HKE-MP123) administered rectally (pr) in a murine model of PNA.

METHODS

Peanut-allergic C3H/HeJ mice received 0.9 (low dose), 9 (medium dose), or 90 (high dose) microg HKE-MP123 pr, HKE-containing vector (HKE-V) alone, or vehicle alone (sham) weekly for 3 weeks. Mice were challenged 2 weeks later. A second and third challenge were performed at 4-week intervals.

RESULTS

After the first challenge, all 3 HKE-MP123 and HKE-V-treated groups exhibited reduced symptom scores (P <.01,.01,.05,.05, respectively) compared with the sham-treated group. Interestingly, only the medium- and high-dose HKE-MP123-treated mice remained protected for up to 10 weeks after treatment accompanied by a significant reduction of plasma histamine levels compared with sham-treated mice (P <.05 and.01, respectively). IgE levels were significantly lower in all HKE-MP123-treated groups (P <.001), being most reduced in the high-dose HKE-MP123-treated group at the time of each challenge. IL-4, IL-13, IL-5, and IL-10 production by splenocytes of high-dose HKE-MP123-treated mice were significantly decreased (P <.01;.001,.001, and.001, respectively), and IFN-gamma and TGF-beta production were significantly increased (P <.001 and.01, respectively) compared with sham-treated mice at the time of the last challenge.

CONCLUSIONS

Treatment with pr HKE-MP123 can induce long-term "downregulation" of peanut hypersensitivity, which might be secondary to decreased antigen-specific T(H)2 and increased T(H)1 and T regulatory cytokine production.

Engineered recombinant peanut protein and heat-killed Listeria monocytogenes coadministration protects against peanut-induced anaphylaxis in a murine model

Peanut allergy (PNA) is the major cause of fatal and near-fatal anaphylactic reactions to foods. Traditional immunotherapy using peanut (PN) protein is not an option for PNA therapy because of the high incidence of adverse reactions. We investigated the effects of s.c. injections of engineered (modified) recombinant PN proteins and heat-killed Listeria monocytogenes (HKLM) as an adjuvant on anaphylactic reactions in a mouse model of PN allergy. PN-allergic C3H/HeJ mice were treated s.c. with a mixture of the three major PN allergens and HKLM (modified (m)Ara h 1-3 plus HKLM). The effects on anaphylactic reactions following PN challenge and the association with Ab levels and cytokine profiles were determined. Although all mice in the sham-treated groups exhibited anaphylactic symptoms with a median symptom score of 3, only 31% of mice in the mAra h 1-3 plus HKLM group developed mild anaphylaxis, with a low median symptom score of 0.5. Alterations in core body temperature, bronchial constriction, plasma histamine, and PN-specific IgE levels were all significantly reduced. This protective effect was markedly more potent than in the mAra h 1-3 protein alone-treated group. HKLM alone did not have any protective effect. Reduced IL-5 and IL-13, and increased IFN-gamma levels were observed only in splenocytes cultures from mAra h 1-3 plus HKLM-treated mice. These results show that immunotherapy with modified PN proteins and HKLM is effective for treating PN allergy in this model, and may be a potential approach for treating PNA.

Canine atopic dermatitis: a retrospective study of 169 cases examined at the University of California, Davis, 1992-1998. Part II. Response to hyposensitization

One hundred and sixty-nine dogs were diagnosed with atopic dermatitis, and treated with hyposensitization for at least 1 year based on the results of either intradermal skin tests (IDST) or enzyme-linked immunosorbant serum assays (ELISA). Excellent (i.e. hyposensitization alone controlled clinical signs), good (> 50% improvement), moderate (< 50% improvement) and no (clinical signs were unchanged) responses were seen in 19.5, 32.5, 20.1 and 27.8%, respectively. Age of onset, age when treatment was initiated or the duration of clinical signs had no influence on response to hyposensitization. Dogs having concurrent flea allergy dermatitis were statistically more likely to respond better than dogs with concurrent food allergies. Although not statistically significant, there were trends for Golden Retriever and male dogs to respond better than other breeds and female dogs, respectively. Dogs having more than 21 positive reactions in allergy tests and treated with more than 21 allergens had lower response scores, and a longer time course before achieving beneficial response. Lower response scores were seen in dogs having positive reactions to cultivated plants, grasses, trees or insects. There was no difference in response to hyposensitization whether based on IDST or ELISA results.

Mycobacterial infection inhibits established allergic inflammatory responses via alteration of cytokine production and vascular cell adhesion molecule-1 expression

Our previous studies, as well as those of others, have demonstrated that local or systemic Mycobacterium bovis bacille Calmette-Guérin (BCG) infection can inhibit de novo allergen-induced asthma-like reactions, but the effect of this infection on established allergic responses is unknown. The aim of this study was therefore to examine the effect of mycobacterial infection on established allergy in a murine model of asthma-like reaction. Mice were sensitized with ovalbumin (OVA) in alum followed by infection with BCG and subsequent intranasal challenge with the same allergen. In some experiments, mice were sensitized with OVA followed by intranasal challenge with OVA and then given BCG infection with subsequent rechallenge with OVA. Mice without BCG infection but treated with OVA in the same manner, were used as a control. The mice were examined for immunoglobulin E (IgE) response and eosinophilic inflammation, mucus production, cytokine/chemokine patterns and adhesion molecule expression in the lung. The results showed that postallergen BCG infection suppressed the established airway eosinophilia and mucus overproduction, but not IgE responses. The inhibition of asthma-like reactions by BCG infection was correlated with a shift of allergen-driven cytokine production pattern and, more interestingly, with a dramatic decrease of vascular cell adhesion molecule-1 (VCAM-1) expression in the lung. These findings suggest that intracellular bacterial infection can inhibit established allergic responses via alteration of local cytokine production and the expression of adhesion molecules.

Does allergen immunotherapy alter the natural course of allergic disorders?

Allergy in patients with atopy is caused by clinical adverse reactions to environmental antigen, which is often associated with allergen-specific immunoglobulin (Ig)E production. Since allergy reflects an inappropriate immunological reaction, a therapeutic approach related to immunology is likely to actively alter the natural course of allergic disorders. Allergen immunotherapy, known at various times as desensitisation or hyposensitisation, is very recently defined by the World Health Organization as therapeutic vaccines for allergic diseases. At present, it has become a common clinical practice in selected patients for the treatment and prevention of the recurrence of allergic disorders caused by insect venoms and has proven to be effective in changing the course of allergic responses induced by grass and tree pollen, animal hair and dander, house dust mite and mold, as demonstrated by improvement in clinical symptoms, skin prick test and medication scores. Reported effects of allergen immunotherapy on the natural course of allergic disorders include (i) prevention of reaction following re-sting in insect venom allergy; (ii) prevention or decrease the rate of the natural progress of allergic rhinitis to asthma; and (iii) inhibition of new sensitisation in monosensitised children. Many aspects of the immune responses associated with allergic disorders, including antibody production, cytokine secretion, T cell activation and local inflammatory reactions, are found to be significantly altered during and/or after immunotherapy. Specifically, the ratio of allergen-specific IgG4 to IgG1 correlates well with positive clinical outcome caused by allergen immunotherapy in patients with pollen-allergy. Allergen immunotherapy affects the cytokine profile of allergen-specific T cells and switches T(H)2 type immune responses in patients with atopy towards T(H)0 or T(H)1 type responses. Although the changes in the absolute value of T(H)1 or T(H)2 cytokines appear quite variable, the increase in the ratio of T(H)1/T(H)2 cytokines is very consistent among published reports, especially in the late stage of treatment. Accumulating evidence indicates that appropriate immunotherapy prevents the onset of new sensitisation and prevents the progress of allergic rhinitis to asthma. Although the changes in B cell and T cell responses, especially IgG antibodies and T(H)1/T(H)2 cytokine production, may be the major mechanism underlying the clinical efficacy of allergen immunotherapy and the prevention of the development of allergic phenotypic changes, multiple mechanisms may be involved in the outcome of alteration of the natural course of allergic disorders.

Clinical and immunologic changes after allergen immunotherapy with Hop Japanese pollen

BACKGROUND AND OBJECTIVE

Hop Japanese (Hop J) pollen has been reported as one of the major causative pollen allergens in the autumn season. There have been no published data regarding the clinical and immunologic effects of Hop J pollen immunotherapy in sensitized patients. In this study, we evaluated clinical and immunologic effects of Hop J immunotherapy.

PATIENTS AND METHODS

Pollens were collected in our area, and "Depo-Hop J" was prepared in the laboratory of Allergopharma (Reinbek, Germany). Fifteen asthmatic patients who had Hop J immunotherapy for > 1 year were enrolled. Their clinical parameters, such as asthma symptom scores, were monitored. Skin reactivity to Hop J and degree of airway hyperresponsiveness to methacholine were measured before and 1 year after the immunotherapy. Sera were collected before the immunotherapy, at the end of initial therapy, and 1 year after the therapy. Serum total IgE levels were compared by radioimmunoassay. Serum-specific IgE, IgG1, and IgG4 levels to Hop J were compared by ELISA. To evaluate the changes of cellular mechanisms, soluble CD30 (sCD30), soluble interleukin (IL)-2 receptor (sIL-2R), soluble CD23 (sCD23), and IL-10 levels were measured by ELISA.

RESULTS

Specific IgG1 and IgG4 levels began to increase at the end of the initial therapy (P < 0.05) with significant decreases in symptom scores (P < 0.05), whereas total and specific IgE levels showed variable responses during the immunotherapy with no statistical significance (P > 0.05). Serum sIL-2R and sCD30 levels decreased significantly (P < 0.05) 1 year after immunotherapy. No significant changes were noted in sCD23, IL-10, skin reactivity to Hop J, or airway responsiveness to methacholine (P > 0.05).

CONCLUSIONS

We are certain that Hop J allergen immunotherapy, if carried out properly according to suitable indications, can favorably influence asthma. Thus, an increase in specific IgG4 and IgG1 antibodies and reduction of a possible Th2 lymphocyte marker (sCD30) may be associated with symptomatic improvements.

Altered allergen binding capacities of Amb a 1-specific IgE and IgG4 from ragweed-sensitive patients receiving immunotherapy

BACKGROUND

The mechanisms for the effectiveness of allergen immunotherapy (IT) are not well understood. The binding potential for immunoglobulins is a function of both antibody concentration and affinity (K(A)).

PURPOSE

The purpose was to perform a cross-sectional preliminary study to investigate any differences in allergen-specific antibody affinity and concentration following ragweed immunotherapy by introducing a new concept of antibody binding capacity ([Ig] X K(A)).

METHODS

The binding capacity of allergen-specific IgE and IgG4 was determined for ragweed-allergic individuals undergoing ragweed immunotherapy and compared with the capacity of ragweed-specific IgE and IgG4 for allergic individuals not receiving immunotherapy.

RESULTS

The mean binding capacity for IgG4 after long-term immunotherapy was 1.6 log units higher (P < .0001) than for individuals not receiving IT. The binding capacity for allergen-specific IgE was 1.2 log units lower following long-term immunotherapy (P < .0001) compared with individuals not receiving ragweed IT.

CONCLUSIONS

We hypothesize that a primary effect of immunotherapy is to increase IgG4 binding capacity and concomitantly decrease IgE binding capacity.