From IgE to anti-IgE: where do we stand?

Omalizumab for the treatment of atopic dermatitis

Atopy is almost always associated with an elevated immunoglobulin (Ig) E production. Omalizumab is a monoclonal anti-IgE antibody that is currently indicated for the treatment of cases of asthma that satisfy certain criteria. A number of studies have been published on the usefulness of omalizumab in the treatment of atopic dermatitis, and the results have been variable. We present our experience in the treatment of 9 patients with severe atopic dermatitis refractory to at least 2 systemic drugs. All patients reported a decrease in pruritus and an improvement in quality of life. Good control of the skin disease was achieved with omalizumab in monotherapy in 2 patients, and there was a slight improvement in the eczematous lesions in 4 patients. Those patients who also had asthma achieved good control of their respiratory symptoms and did not require additional therapy. Omalizumab is a well-tolerated and safe drug that can be useful for the treatment of severe atopic dermatitis refractory to other systemic therapies. This monoclonal anti-IgE antibody is a major therapeutic advance as it opens the door to the management of atopic dermatitis using systemic immunomodulating therapies.

sICAM-1 and TNF-α in asthma and rhinitis: relationship with the presence of atopy

BACKGROUND

A genetically determined overproduction of specific immunoglobulin E (IgE) underlies many diseases like asthma or allergic rhinitis. IgE as well as tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule-1 (ICAM-1) play a critical role in the induction and maintenance of inflammation. While the correlation between IgE and atopy is inseparable, little is known about the correlation of atopy with markers of inflammation.

OBJECTIVE

We investigated the relationship between the serum concentrations of TNF-α, soluble ICAM-1 (sICAM-1), and the presence of atopy in patients with persistent rhinitis or asthma.

METHODS

Serum concentrations of sICAM-1, TNF-α, and total IgE were investigated in 64 adults with persistent allergic rhinitis, 17 subjects with nonatopic rhinitis, 90 patients with asthma, and 21 healthy individuals. Atopy was diagnosed on the basis of positive family history, skin prick tests, and serum IgE concentration.

RESULTS

Total IgE concentration was significantly higher in patients with atopic rhinitis or asthma when compared with nonatopic patients and healthy individuals and was the highest in patients suffering from severe atopic asthma who were not treated with systemic glucocorticosteroids. Although there were marked alterations in IgE in atopic and nonatopic patients, there were no significant differences between atopic and corresponding groups of nonatopic rhinitic and asthmatic patients in sICAM-1 and TNF-α concentrations. (sICAM-1 in rhinitis: atopic vs. nonatopic patients: 224.02 and 221.08 ng/ml, respectively, p > .05; in mild/moderate asthma: atopic vs. nonatopic: 306.22 and 326.39 ng/ml, respectively, p > .05; severe asthma without oral corticosteroids therapy: atopic vs. nonatopic: 418.03 and 468.09 ng/ml, respectively, p > .05; and severe asthma with oral corticosteroids therapy: atopic vs. nonatopic: 320.66 and 308.09 ng/ml, respectively, p > .05).

CONCLUSIONS

Concentrations of sICAM-1 and TNF-α are significantly higher in patients with asthma compared with those observed in patients with rhinitis, but they are independent of the presence of atopy.

Current and future applications of the anti-IgE antibody omalizumab

IgE antibodies are a pivotal factor in pathophysiology of allergic diseases, and the possibility of reducing their level by anti-IgE has long been envisioned. Following several attempts, an effective biologic agent was obtained with the recombinant humanized mono-clonal antibody (rhuMAb)-E25, known as omalizumab. A number of controlled clinical trials demonstrated its efficacy and safety in the treatment of severe allergic asthma uncontrolled by standard drug treatment with maximal recommended doses, and treatment with omalizumab is currently included in international guidelines on asthma management. Other studies reported a clear effectiveness also in allergic rhinitis, but the cost of the anti-IgE treatment suggests its use in patients with rhinitis concomitant with asthma. Other indications to be further investigated are skin disorders such as atopic dermatitis and IgE-mediated urticaria, as well as adverse reactions to foods, with a particularly important role in preventing food-induced anaphylaxis. Finally, there are data indicating the usefulness of omalizumab when used in combination with allergen specific immunotherapy, in terms of reducing the adverse reactions to treatment and increasing the clinical efficacy.

The role of anti-IgE therapy in combination with allergen specific immunotherapy for seasonal allergic rhinitis

Novel therapies that interfere specifically with immunologic mechanisms underlying allergen-induced pathology are currently in clinical evaluation. Among these is anti-IgE, which directly targets IgE serum antibodies, thus inhibiting the central mechanism of immediate-type hypersensitivity reactions. Application of anti-IgE antibodies effectively reduces IgE serum levels regardless of allergen specificity. Anti-IgE therapy has been successfully tested in patients with allergic rhinitis, asthma, and food allergy, showing significant efficacy in reducing symptom scores and the use of rescue medications. However, such therapy is limited by high costs and the requirements for permanent or every-season treatment. The advantage of specific immunotherapy (SIT) is the potential to alter the course of the disease, which has been demonstrated in patients with allergic rhinitis, insect venom allergy and, to a lesser degree, asthma. The broader application of SIT is restricted by sometimes life-threatening adverse effects. The combination of anti-IgE with SIT was suggested to be superior to each single treatment protocol in children and adolescents with allergic rhinitis. In a randomized, double-blind trial to assess the efficacy and safety of anti-IgE (omalizumab) or placebo in combination with SIT (birch pollen or grass pollen), the combination therapy reduced symptom load, the sum of daily symptom severity score plus rescue medication use, over the birch and grass pollen seasons by nearly 50% over SIT alone. These data show that the combination of anti-IgE plus SIT may be beneficial for the treatment of allergic diseases, offering improved efficacy, limited adverse effects, and potential immune-modifying effects.

The immuno cross-reactivity of gutta percha points

OBJECTIVE

The purpose of this study is to test the postulated immuno cross-reactivity between proteins derived from raw gutta percha (RGP), gutta percha point (GPP) and natural rubber latex (NRL).

METHODS

Antigenicity and cross-reactivity of proteins were determined by the FITkit (FITBiotech, Finland) and ELISA inhibition assays.

RESULTS

Antigenicity of proteins derived from RGP or GPP was not demonstrated. Except for NRL glove extracts, neither extracts from RGP or GPP were reactive in ELISA inhibition assay.

SIGNIFICANCE

There is no immunologic cross-reactivity in vitro between proteins derived from RGP or GPP, and from NRL gloves. Thus, therapeutic use of GPP is unlikely to initiate adverse immuno-reactivity in individuals previously sensitized to NRL proteins.

Omalizumab in asthma: approval and postapproval experience

Omalizumab is a humanized mouse monoclonal antibody that binds specifically to the constant region of the immunoglobulin (Ig)E heavy chain. Omalizumab exerts its effects by reducing free serum IgE levels and FcepsilonRI expression on several cell types. These effects have been shown to result in decreased airway inflammation and clinical improvement. In multiple studies, omalizumab has been shown to be efficacious in the treatment of moderate-to-severe persistent asthma and is currently approved by the US Food and Drug Administration for the treatment of moderate-to-severe allergic asthma in patients age 12 yr and older. Moreover, omalizumab has been demonstrated to be effective in the treatment of children and adults with seasonal and perennial allergic rhinitis. Postmarketing surveillance has shown omalizumab to be a relatively safe and well-tolerated medication.

The co-seasonal application of anti-IgE after preseasonal specific immunotherapy decreases ocular and nasal symptom scores and rescue medication use in grass pollen allergic children

BACKGROUND

Specific immunotherapy (SIT) and treatment with anti-immunoglobulin (Ig)E antibody are complementary approaches to treat allergic rhinoconjunctivitis, which may be used for single or combined treatment.

OBJECTIVE

A randomized, double-blind, placebo-controlled trial was conducted to compare the efficacy of single and combined treatment with SIT and anti-IgE (Omalizumab) in reducing symptom severity and rescue medication use.

METHODS

A total of 221 subjects with birch and grass pollen allergic rhinoconjunctivitis aged 6-17 years were analysed during the grass pollen season. Group A (SITbirch + placebo) served as a reference group obtaining no effective treatment for grass pollen allergy. Group B received anti-IgE monotherapy during grass pollen season, group C SIT grass pollen monotherapy, and group D the combined treatment of SIT and Omalizumab.

RESULTS

Preseasonal treatment with grass pollen SIT alone compared with SIT with the nonrelated allergen did not reduce symptoms or rescue medication use. Anti-IgE monotherapy significantly diminished rescue medication use and number of symptomatic days. The combined treatment with SIT and anti-IgE showed superior efficacy on symptom severity compared with anti-IgE alone.

CONCLUSIONS

Co-seasonal Omalizumab therapy showed considerable effects in children with seasonal allergic rhinitis. The combination of SIT plus Omalizumab was clinically superior to each treatment alone during the first year of observation.

Is there a role for anti-IgE in combination with specific allergen immunotherapy?

PURPOSE OF REVIEW

A line of novel therapeutic approaches that try to interfere more specifically with the immunological mechanisms underlying allergen-induced pathology are currently undergoing clinical evaluation. The most advanced of these is anti-IgE, which directly targets IgE serum antibodies, thus inhibiting the central mechanism of immediate type hypersensitivity reactions. In addition, a lot of interest has recently been focused on allergen-specific immunotherapy due to its potential to cure allergic diseases. In the present review, state-of-the-art treatment of allergic diseases with anti-IgE and allergen-specific immunotherapy is summarized, and the potential of combination therapy with both treatment options is discussed.

RECENT FINDINGS

Application of anti-IgE antibodies effectively reduces IgE serum levels regardless of allergen specificity. This treatment has been successfully tested in patients with allergic rhinitis, asthma and food allergy, showing significant efficacy in reducing symptom scores and rescue medication use. Anti-IgE therapy is limited by high costs and the necessity for permanent or every-season treatment. The strongest argument in favor of allergen-specific immunotherapy is the potential to cure allergic diseases, which has been demonstrated in patients with allergic rhinitis, insect venom allergy and, to a lesser degree, asthma. The broader application of allergen-specific immunotherapy is restricted by sometimes life-threatening side effects. A combination of anti-IgE and allergen-specific immunotherapy was shown to be superior to each single treatment protocol in children and adolescents with allergic rhinitis, as demonstrated by efficacy of symptom scores and rescue medication use.

SUMMARY

There are strong arguments for a combination of anti-IgE plus allergen-specific immunotherapy for treatment of allergic diseases: improved efficacy, limited side effects, and potential curative effects.

Molecular Mechanisms of Allergic Disease

Interaction of allergen with T-cells is associated with patterns of cytokine release by immunocompetent cells characterized as T-helper Th1 or Th2 T-immune responses. The Th2 pattern of inflammation induced by this cytokine release is associated with allergic diseases. The molecular mechanisms underlying allergic inflammation are the signals for immunoglobulin (Ig) E production and the activation of mast cells and eosinophils. Data suggesting that environmental exposure may play a role in the induction of the Th2 pattern of inflammation has led to the development of the "hygiene hypothesis." Knowledge of the mechanisms of allergic inflammation has allowed the development of specific pharmacologic intervention to include 1) antibodies to IgE, 2) therapy tailored to regulate IgE production, and 3) modulation of cytokine release and function. Knowledge of the role of transcription factors in regulating gene activity as it relates to allergic inflammation is expanding and may also provide future targets for pharmacologic intervention.