SLIT's Prevention of the Allergic March

PURPOSE OF REVIEW

The progression of atopic disorders from atopic dermatitis in infants to allergic rhinitis and asthma in children, adolescents, and adults defines the allergy march. Allergen immunotherapy is the only causal treatment altering the immunological mechanism underlying the allergic diseases. The sublingual administration route is more acceptable than the subcutaneous one in pediatric age.

RECENT FINDINGS

Several studies show the efficacy and safety profile of sublingual immunotherapy (SLIT) for the treatment of respiratory allergy diseases, but few data are available on its effect of primary and secondary prevention of allergic disease. The purpose of this manuscript is to review the latest studies addressing the effect of SLIT on the development of new sensitizations in not sensitized or already sensitized patients and progression of the allergy march.

Sublingual immunotherapy in patients with house dust mite allergic rhinitis: prospective study of clinical outcomes over a two-year period

BACKGROUND

Sublingual immunotherapy in patients with allergic rhinitis sensitised to house dust mites is safe, but its efficacy is controversial and sublingual immunotherapy with Blomia tropicalis has not yet been studied. This study sought to evaluate the efficacy of sublingual immunotherapy with house dust mite extract in children and adults with house dust mite allergic rhinitis over a period of two years.

METHODS

A prospective observational study was conducted of children and adults diagnosed with house dust mite allergic rhinitis who were treated with sublingual immunotherapy from 2008 to 2012. Total Nasal Symptom Scores, Mini Rhinoconjunctivitis Quality of Life scores and medication usage scores were assessed prospectively.

RESULTS

Thirty-nine patients, comprising 24 children and 15 adults, were studied. Total Nasal Symptom Scores and Mini Rhinoconjunctivitis Quality of Life scores dropped significantly at three months into therapy, and continued to improve. Medication usage scores improved at one year into immunotherapy.

CONCLUSION

Sublingual immunotherapy with house dust mite extracts, including B tropicalis, is efficacious as a treatment for patients with house dust mite allergic rhinitis.

Respiratory allergies: a general overview of remedies, delivery systems, and the need to progress

The spread of respiratory allergies is increasing in parallel with the alarm of the scientific community. Evidently, our knowledge of the onset mechanisms of these diseases and, as a consequence, of the available remedies is inadequate. This review provides a brief, general description of current therapeutic resources and the state of research with regard to both drugs and medical devices in order to highlight their limits and the urgent need for progress. Increasing the amount of basic biochemical research will improve our knowledge of such onset mechanisms and the potential efficacy of therapeutic preparations.

Sublingual immunotherapy efficacy in patients with atopic dermatitis and house dust mites sensitivity: a prospective pilot study

BACKGROUND

Specific subcutaneous immunotherapy (SCIT) with house dust mite (HDM) preparation has recently been shown to improve eczema in patients with atopic dermatitis (AD). So far, there is less data regarding efficacy and safety of specific sublingual immunotherapy (SLIT) in patients with AD.

STUDY AIM

To evaluate in an open non-controlled, non-randomized pilot trial the effect of SLIT with HDM allergen extracts preparation (SLITone, ALK Abellò Italy) on SCORAD in adult patients with mild-moderate AD.

PATIENTS AND METHODS

86 Subjects (53 females and 33 males) between 3 and 60 years of age with AD and IgE-proved (Class > 2) HDM sensitization were enrolled after their informed consent in the trial. Exclusion criteria were severe asthma and treatment with systemic or high potent topical corticosteroids or immunosuppressant agents. Patients were treated with SLIT (Dermatophagoides pteronyssinus and Dermatophagoides farinae extracts: SLITone, ALK-Abellò) for at least 12 months. SCORAD was evaluated at baseline and after 12 months of treatment.

RESULTS

Baseline SCORAD value, mean +/- SD, was 43.3 +/- 13.7 (range 15-84). After 1 year of SLIT, mean +/- SD, SCORAD value was reduced to 23.7 +/- 13.3 (range: 0-65) (p = 0.0001; unpaired t-test vs. baseline). This was a 46% reduction in SCORAD in comparison with baseline value. A significant improvement, defined as a SCORAD reduction of > 30%, was observed in 51 out of 86 patients (59%). In 5 patients (5.8%) SCORAD values did not change at the end of the observation period. In 30 patients (35%) the SCORAD reduction after SIT was <or= 30% in comparison with baseline. Total and specific IgE serum levels were significantly (p = 0.001) reduced after SLIT. No severe adverse events were observed during the trial.

CONCLUSION

In this open non-controlled trial SLIT with HDM extracts in patients with mild to moderate AD was effective in reducing the SCORAD after 1 year of SLIT treatment. In addition the treatment was very well tolerated. Treatment with SLIT, furthermore, has allowed a gradual and relevant reduction of concomitant therapies with topical corticosteroids or immunosuppressants. Present results require further controlled trials in order to confirm the potential clinical benefit of SLIT in this clinical setting.

Sublingual immunotherapy induces IL-10-producing T regulatory cells, allergen-specific T-cell tolerance, and immune deviation

BACKGROUND

The immunologic mechanisms underlying sublingual immunotherapy (SLIT) are still unclear, particularly the role of regulatory T cells.

OBJECTIVE

We sought to characterize allergen-specific T-cell responses during successful birch pollen SLIT.

METHODS

Proliferation of PBMCs and PBMCs depleted of CD25(+) cells obtained from 9 patients before, after 4 weeks, and after 52 weeks of SLIT was assessed in response to the major birch pollen allergen Bet v 1, the homologous apple allergen Mal d 1, or tetanus toxoid. Allergen-induced cytokine responses and FoxP3 expression of T cells were analyzed by using real-time PCR. The role of IL-10 for regulatory activity of T cells was investigated.

RESULTS

After 4 weeks, higher frequencies of circulating CD4(+)CD25(+) T cells were detected together with increased FoxP3 and IL-10 and reduced IL-4 and IFN-gamma mRNA expression levels compared with those before SLIT. Proliferation to all 3 antigens was markedly reduced but increased significantly after depletion of CD25(+) cells or addition of anti-IL-10 antibodies. After 52 weeks, proliferation in response to Mal d 1 or tetanus toxoid returned to pre-SLIT levels, whereas Bet v 1-induced proliferation remained significantly suppressed and was enhanced by neither depletion of CD25(+) cells nor addition of anti-IL-10 antibodies. In parallel, increased IFN-gamma and reduced IL-4, IL-10, and FoxP3 mRNA expression was detected. Neither TGF-beta levels nor cell-cell contact-mediated suppression of CD4(+)CD25(+) cells changed during the course of SLIT.

CONCLUSION

SLIT induces regulatory T-cell suppression through IL-10 during the early phase and specific nonreactivity and immune deviation of allergen-specific T cells during the later phase of therapy.

CLINICAL IMPLICATIONS

SLIT induces immune mechanisms comparable with subcutaneous specific immunotherapy.

Successful sublingual immunotherapy with birch pollen has limited effects on concomitant food allergy to apple and the immune response to the Bet v 1 homolog Mal d 1

BACKGROUND

Cross-reactivity between the major birch pollen allergen, Bet v 1, and the apple protein, Mal d 1, frequently causes food allergy.

OBJECTIVE

To investigate the effects of successful sublingual immunotherapy (SLIT) with birch pollen extract on apple allergy and the immune response to Bet v 1 and Mal d 1.

METHODS

Before and after 1 year of SLIT, Bet v 1-sensitized patients with oral allergy syndrome to apple underwent nasal challenges with birch pollen and double-blind placebo-controlled food challenges with apple. Bet v 1-specific and Mal d 1-specific serum antibody levels and proliferation in PBMCs and allergen-specific T-cell lines (TCLs) were determined. Bet v 1-specific TCLs were mapped for T-cell epitopes.

RESULTS

In 9 patients with improved nasal provocation scores to birch pollen, apple-induced oral allergy syndrome was not significantly reduced. Bet v 1-specific IgE and IgG(4) levels significantly increased. Bet v 1-specific T-cell responses to all epitopes and those cross-reactive with Mal d 1 significantly decreased. However, neither Mal d 1-specific IgE and IgG(4) levels nor Mal d 1-induced T-cell proliferation changed significantly. In contrast, Mal d 1-specific TCLs showed increased responses to Mal d 1 after 1 year of SLIT.

CONCLUSION

This longitudinal study indicates that pollen SLIT does not efficiently alter the immune response to pollen-related food allergens, which may explain why pollen-associated food allergy is frequently not ameliorated by pollen immunotherapy even if respiratory symptoms significantly improve.

CLINICAL IMPLICATIONS

SLIT with birch pollen may have no clinical effect on associated apple allergy.