Noninjection routes for immunotherapy

Immune mechanisms of allergen-specific sublingual immunotherapy

Sublingual immunotherapy has been shown in some clinical studies to modulate allergen-specific antibody responses [with a decrease in the immunoglobulin E/immunoglobulin G4 (IgE/IgG4) ratio] and to reduce the recruitment and activation of proinflammatory cells in target mucosa. Whereas a central paradigm for successful immunotherapy has been to reorient the pattern of allergen-specific T-cell responses in atopic patients from a T helper (Th)2 to Th1 profile, there is currently a growing interest in eliciting regulatory T cells, capable of downregulating both Th1 and Th2 responses through the production of interleukin (IL)-10 and/or transforming growth factor (TGF)-beta. We discuss herein immune mechanisms involved during allergen-specific sublingual immunotherapy (SLIT), in comparison with subcutaneous immunotherapy. During SLIT, the allergen is captured within the oral mucosa by Langerhans-like dendritic cells expressing high-affinity IgE receptors, producing IL-10 and TGF-beta, and upregulating indoleamine dioxygenase (IDO), suggesting that such cells are prone to induce tolerance. The oral mucosa contains limited number of proinflammatory cells, such as mast cells, thereby explaining the well-established safety profile of SLIT. In this context, second-generation vaccines based on recombinant allergens in a native conformation formulated with adjuvants are designed to target Langerhans-like cells in the sublingual mucosa, with the aim to induce allergen-specific regulatory T cells. Importantly, such recombinant vaccines should facilitate the identification of biological markers of SLIT efficacy in humans.

Comparative analysis of nasal and oral mucosa dendritic cells

BACKGROUND

Mucosal dendritic cells (DC) play a crucial role in tolerance induction as seen in mucosal immunotherapy of atopic diseases. Nevertheless little is known about the phenotypical differences of oral and nasal mucosal DC (nmDC). Recently, we could show that oral mucosal myeloid CD1a(+) DC (omDC) differ from their skin counterparts especially by the expression of high affinity receptor for immunoglobulin E (IgE; FcepsilonRI). However, expression pattern of FcepsilonRI and phenotypical characteristics of CD1a(+) nmDC have not been elucidated in detailed yet.

METHODS

We performed detailed phenotypical comparison of nmDC and omDC of atopic and nonatopic individuals.

RESULTS

As reported for omDC, FcepsilonRI on nmDC of atopic donors was elevated and mostly occupied by IgE while FcepsilonRI was present only in low amounts on nmDC of nonatopic donors. Nevertheless, the highest FcepsilonRI expression has been observed on omDC. Furthermore, significant amounts of costimulatory molecules CD40, CD80 and CD86 could be detected on nmDC that expressed more CD80 compared with omDC. Moreover, nmDC displayed less major histocompatability complex (MHC) class I and II molecules than omDC. In addition, nmDC expressed more C-type lectins CD205, CD206 as well as myeloid marker CD11b while omDC displayed increased expression of CD207 and lipopolysaccharide (LPS) receptor CD14.

CONCLUSION

Together these data imply that nmDC phenotypical differ from omDC which might result in diverse functional properties and might be of relevance for selecting routes for immunotherapy of atopic diseases. Moreover these data provide a basis for further studies investigating immunological mechanisms underlying mucosal immunotherapy.

Effect of ingestion of cow's milk protein hydrolysate formulas on alpha-casein-specific immunoglobulin E and G1 antibody responses in naïve and sensitized mice

OBJECTIVES

Cow's milk protein hydrolysate formulas are widely used for genetically predisposed atopic infants. Whether hydrolysate formulas can induce oral tolerance to alpha-casein was studied for the first time in naive and sensitized mice.

METHODS

Using immunoblotting, residual antigenicity to alpha-casein was examined for in animals fed hydrolysate formulas. Naïve mice fed hydrolysate formulas for 1 to 4 weeks were later sensitized with alpha-casein. Another group of mice sensitized first with alpha-casein were then fed hydrolysate formulas continually for 12 weeks.

RESULTS

Oral tolerance measured by immunoglobulin (Ig)E and IgG1 antibody responses to alpha-casein was induced in naïve mice fed NAN for 1 week or NAN-HA for 4 weeks. IgE responses to alpha-casein were suppressed in mice fed NAN-HA for 1 week or Neoangelac FL for 4 weeks. In contrast, mice fed Alfare, Pepti-Junior, or Pregestimil for 1 to 4 weeks did not develop tolerance to alpha-casein. Antibody responses to alpha-casein were not significantly suppressed in sensitized mice fed NAN or hydrolysate formulas for 12 weeks.

CONCLUSIONS

Primary IgE responses to alpha-casein are readily suppressed in naïve mice first fed cow's milk formula or partially hydrolyzed formula for 1 week. Conversely, ongoing IgE, IgG1, and IgG antibody responses to alpha-casein are poorly suppressed in previously sensitized mice even after prolonged feeding of cow's milk formula or hydrolysate formulas.

Post-marketing survey on the safety of sublingual immunotherapy in children below the age of 5 years

BACKGROUND

The age below 5 years is considered a prudential limit for immunotherapy in view of the possible severity of side-effects. Sublingual immunotherapy (SLIT) seems to be safe, but no study in very young children is available. We performed a safety post-marketing surveillance study in children below 5 years.

METHODS

Children aged 3-5 years with respiratory allergy receiving SLIT were followed-up for at least 2 years. A diary card for side-effects was filled by parents at each dose given. Local and systemic side-effects were graded as: mild (no intervention, no dose adjustment), moderate (medical treatment and/or dose reduction), severe (life-threatening/hospitalization/emergency care). The comparative safety of different allergens and regimens was also assessed.

RESULTS

One hundred and twenty-six children (mean age 4.2 years, 67 male) were included. Seventy-six (60%) had rhinitis with asthma, 34 (27%) rhinitis only and 16 (13%) only asthma. Immunotherapy was prescribed for mites (62%), grasses (22.2%), Parietaria (11.9%), Alternaria (2.4%) and olive (1.5%). Eighteen children underwent an accelerated build-up. The total number of doses was about 39,000. Nine side-effects were reported in seven children (5.6% patients and 0.2/1000 doses). Two episodes of oral itching and one of abdominal pain were mild. Six gastrointestinal side-effects were controlled by reducing the dose. All side-effects occurred during up-dosing phase. No difference in terms of safety among the allergens used was observed.

CONCLUSION

SLIT is safe also in children under the age of 5 years.

The safety of sublingual-swallow immunotherapy: an analysis of published studies

BACKGROUND

As the main target of sublingual immunotherapy (SLIT) is to reduce at most the occurrence of adverse events (AE), safety represents a critical issue. This aspect deserves particular mention when a higher dose of allergen extract than traditional subcutaneous immunotherapy (SCIT) is required to be effective: that may be up to 500 times that employed for SCIT.

OBJECTIVE

All published controlled studies concerning SLIT-swallow were analysed to evaluate AE rates.

METHODS

Studies were subdivided in two groups: (i) studies using low allergen dose (LAD), i.e. ranging from 1 to 50 times the dose commonly administered with SCIT, and (ii) studies with high allergen dose (HAD), i.e. ranging from 50 to 500 times the dose administered with SCIT.

RESULTS

Twenty-five studies were altogether analysed: 13 studies belonged to the low-dose group, 12 belonged to the high-dose group. We considered all patients with at least one AE. Local reactions were significantly more frequent in the LAD group than in the HAD group (P<0.0001), while there was no difference in the rate of systemic reactions. Severe systemic reactions were never reported.

CONCLUSION

This study represents the first analysis of the safety of SLIT concerning the allergen dose employed in the treatment. There is evidence that AE occurrence is substantially not dose-dependent. This fact highlights two main clinical aspects: the elevated tolerability of SLIT in general and the safety of HAD regimen.

Induction of interleukin 10 by sublingual immunotherapy for house dust mites: a preliminary report

BACKGROUND

Subcutaneous specific immunotherapy has been demonstrated to be capable of inducing T-cell regulatory response. Interleukin 10 (IL-10) plays a crucial role in inducing allergen-specific tolerance; however, no previous studies have examined IL-10 production after sublingual immunotherapy (SLIT).

OBJECTIVE

To evaluate T-cell proliferation and IL-10 production in patients successfully treated with SLIT for house dust mites (HDMs).

METHODS

Peripheral blood mononuclear cells were isolated from patients after at least 3 years of successful HDM SLIT and from matched untreated allergic patients and healthy control subjects. After 3 and 6 days of in vitro stimulation with phytohemagglutinin (PHA), Candida albicans, and Dermatophagoides farinae, proliferation and production of IL-10 were measured.

RESULTS

Patients treated with SLIT showed a significant reduction of proliferation induced by C albicans compared with untreated atopic patients (P < .001), but a significant reduction was also demonstrated in healthy controls compared with untreated atopic patients (P < .001). Patients treated with SLIT also showed a significant increase of IL-10 production after Candida and PHA stimuli compared with patients with untreated rhinitis (P < .001 for both). Patients with untreated rhinitis did not produce IL-10.

CONCLUSION

This preliminary study confirms reduced T-cell proliferation and preliminarily provides the first evidence, to our knowledge, of peripheral IL-10 production in allergic patients successfully treated with HDM SLIT.

Three-year follow-up of clinical and inflammation parameters in children monosensitized to mites undergoing sub-lingual immunotherapy

Parallel follow-up of clinical and inflammatory markers during sub-lingual immunotherapy (SLIT) is highly beneficial. Twenty-four children (age 4-16) monosensitized to house dust mite were randomized to receive either active or placebo SLIT for 1 yr in a double-blind placebo controlled design (Marcucci et al., Allergy 2003: 58: 657-62). Thereafter, for 2 yr they all received active treatment. Symptom scores for rhinitis, asthma, and drug usage were daily recorded. Eosinophil cationic protein (ECP) and tryptase in sputum and nasal secretions, serum and nasal mite-specific immunoglobulin E (IgE) were recorded before treatment and at 10-12 months intervals. Nasal ECP and nasal tryptase after specific nasal provocation tests were significantly reduced as compared to baseline values (p = 0.0043 and 0.0195, respectively) in the third year of active treatment. None of the other inflammatory parameters was increased. In placebo treated patients all these parameters tended to decrease only after switching to active treatment. Clinical scores did not improve in treated vs. placebo patients in the double-blind placebo-controlled phase of the study. In both cohorts a clinical benefit was observed as intra-group score reduction as compared to baseline. A significant difference was reached in patients treated for 2 yr for rhinitis and asthma (p = 0.0009 and 0.0019, respectively) but not for drug usage and in patients treated for 3 yr for rhinitis, asthma, and drug usage (p = 0.0105, 0.0048, and 0.02, respectively). SLIT in children monosensitized to mites reverted the spontaneous increase in nasal IgE and in local parameters of allergic inflammation. These outcomes were followed by a consolidated clinical improvement in the second and third year of treatment.

Targeting memory Th2 cells for the treatment of allergic asthma

Th2 memory cells play an important role in the pathogenesis of allergic asthma. Evidence from patients and experimental models indicates that memory Th2 cells reside in the lungs during disease remission and, upon allergen exposure, become activated effectors involved in disease exacerbation. The inhibition of memory Th2 cells or their effector functions in allergic asthma influence disease progression, suggesting their importance as therapeutic targets. They are allergen specific and can potentially be suppressed or eliminated using this specificity. They have distinct activation, differentiation, cell surface phenotype, migration capacity, and effector functions that can be targeted singularly or in combination. Furthermore, memory Th2 cells residing in the lungs can be treated locally. Capitalizing on these unique attributes is important for drug development for allergic asthma. The aim of this review is to present an overview of therapeutic strategies targeting Th2 memory cells in allergic asthma, emphasizing Th2 generation, differentiation, activation, migration, effector function, and survival.

Pharmacokinetics of radiolabelled Par j 1 administered intranasally to allergic and healthy subjects

BACKGROUND

Local nasal immunotherapy is accepted as an alternative to the injection route for allergic rhinitis. Despite this, little is known about the kinetics of the allergen after nasal delivery in allergic subjects.

OBJECTIVE

We aimed at assessing the biodistribution of 123I-radiolabelled Par j 1 in Parietaria-allergic subjects, in comparison with healthy volunteers.

METHODS

Purified Par j 1 was radiolabelled with 123I and sprayed into the nostrils of three control subjects and three Parietaria-allergic volunteers. Dynamic and static scintigraphic images of the head were recorded at serial times and blood samples were obtained to measure the plasma radioactivity, and to assess the presence of circulating radiolabelled species by gel chromatography.

RESULTS

In Parietaria-sensitized subjects, the radiolabelled allergen was rapidly cleared from the nasal cavity and transported to pharynx, and little local persistence was seen. This differed from healthy subjects where nasal clearance of the tracer was slower and nasal radioactivity persisted up to 24 h. The increase in plasma radioactivity paralleled swallowing of the allergen in both groups, and plasma chromatographic profile did not differ between allergic and healthy volunteers.

CONCLUSIONS

Sensitization to the allergen affects its local biodistribution. Gastrointestinal absorption is relevant also for the intranasal route.

Allergic rhinitis in children : diagnosis and management strategies

The incidence of allergic rhinitis has been increasing for the last few decades, in keeping with the rising incidence of atopy worldwide. Allergic rhinitis has a prevalence of up to 40% in children, although it frequently goes unrecognized and untreated. This can have enormous negative consequences, particularly in children, since it is associated with numerous complications and comorbidities that have a significant health impact on quality of life. In fact, allergic rhinitis is considered to be a risk factor for asthma. There are numerous signs of allergic rhinitis, particularly in children, that can alert an observant clinician to its presence. Children with severe allergic rhinitis often have facial manifestations of itching and obstructed breathing, including a gaping mouth, chapped lips, evidence of sleep deprivation, a long face, dental malloclusions, and the allergic shiner, allergic salute, or allergic crease. The medical history is extremely important as it can reveal information regarding a family history of atopy and the progression of atopy in the child. It is also important to identify the specific triggers of allergic rhinitis, because one of the keys to successful management is the avoidance of triggers. A tripartite treatment strategy that embraces environmental control, immunotherapy, and pharmacologic treatment is the most comprehensive approach. Immunotherapy has come to be viewed as potentially prophylactic, capable of altering the course of allergic rhinitis. The most recent guidelines for the management of allergic rhinitis issued by the WHO recommend a tiered approach that integrates diagnosis and treatment, in which allergic rhinitis is subclassified both by frequency, as either intermittent or persistent, and by severity, as either mild or moderate to severe. Oral or topical antihistamines and intranasal corticosteroids are the mainstay of pharmacologic therapy for allergic rhinitis, depending upon its severity, and several agents have been approved for use in children aged 5 years old and younger.

Effect of Oral Immunotherapy on Nasal Blockage in Experimental Allergic Rhinitis

We previously reported that when Japanese cedar pollen was prophylactically p.o. administered before a sensitization stage in a guinea-pig model of allergic rhinitis, pollen-induced nasal blockage was suppressed. In this study, we evaluated whether the oral immunotherapy is also effective when the pollen extract was administered starting from the day when the nasal blockage was clearly induced and whether the effectiveness continued after cessation of the immunotherapy. Sensitized animals were repeatedly challenged by pollen inhalation once every week. After the 7th challenge, the extract was orally administered twice a week until the 30th challenge. At the 11th challenge, the oral immunotherapy showed inhibition of the biphasic nasal blockage. The effectiveness was consistently observed during the immunotherapy until the 30th challenge. Furthermore, the increased nasal responsiveness to intranasal application of leukotriene D4 was markedly suppressed by the immunotherapy. Interestingly, even after cessation of the therapy, inhibition of the nasal blockage was sustained for more than 2 months. Nevertheless, neither sneezing nor antigen-specific IgE antibody production was substantially influenced by the immunotherapy. In conclusion, Oral immunotherapy may be clinically useful for allergic nasal blockage. Mechanisms underlying the effectiveness may be associated with the hyporesponsiveness of the nasal mucosa to released mediators.

Sublingual and oral immunotherapy

Sublingual immunotherapy (SLIT) is a viable alternative to the subcutaneous route for the treatment of respiratory allergy, whereas the pure oral route has been abandoned because of its lack of efficacy. The main distinctive feature of SLIT is its optimal safety profile, which has been demonstrated in adults and children. The indications for SLIT are similar to those for the subcutaneous route. A long-lasting effect has been demonstrated for the sublingual route, but data are needed to determine the optimal dose and the preventive effect in asthma.

Canadian trial of sublingual swallow immunotherapy for ragweed rhinoconjunctivitis

BACKGROUND

Sublingual swallow immunotherapy has been increasingly recognized as a safe and efficacious alternative to parenteral specific immunotherapy.

OBJECTIVE

To determine the safety and efficacy of sublingual swallow immunotherapy ragweed allergen extract for rhinoconjunctivitis treatment starting just before and continuing through the ragweed pollen season.

METHODS

This randomized, double-blind, placebo-controlled study was performed in children and adults with a documented history of allergic rhinoconjunctivitis during ragweed season at 9 Canadian allergy centers. Active treatment was standardized extract of ragweed allergen administered as sublingual swallow drops at increasing doses starting shortly before the pollen season and maintenance doses continued daily during the season. Primary efficacy variables were symptom and medication scores, and secondary variables included global evaluation of efficacy and immunologic measurements.

RESULTS

Eighty-three patients were included in the safety analysis; 76 patients were included in the intent-to-treat analysis. Nine placebo recipients and 1 treatment recipient withdrew for lack of efficacy (P = .004). Nine patients in the treatment group withdrew because of adverse events, none serious (P = .003). Investigator evaluation of efficacy showed that significantly more patients improved and fewer deteriorated in the treatment group vs the placebo group (P = .047). Ragweed IgE and IgG4 levels increased significantly in treatment recipients vs placebo users (P < .001). Sneezing and nasal pruritus approached significant improvement in the treatment group vs the placebo group (P = .09 and .06, respectively). Quebec City experienced low pollen counts. Excluding Quebec City, significant improvement was seen for these 2 symptoms (P = .04).

CONCLUSION

Sublingual swallow immunotherapy seems to be safe and efficacious for ragweed rhinoconjunctivitis even when started immediately before the ragweed pollen season.

A prospective, randomized, double-blind, placebo-controlled multi-centre study on the efficacy and safety of sublingual immunotherapy (SLIT) in children with seasonal allergic rhinoconjunctivitis to grass pollen

BACKGROUND

Especially in childhood, sublingual immunotherapy (SLIT) could offer advantages over subcutaneous therapy. However, limited data on its efficacy is available.

METHODS

In four German centres 97 children (age 3-14 years) with allergic rhinoconjunctivitis to grass pollen were enrolled in a prospective, double-blind trial comparing SLIT (Pangramin SLIT; ALK-SCHERAX, 0.5 microg major allergens, three times per week, 32 months) with placebo. Primary endpoint was a multiple symptom-medication score for changes in seasonal diary entries between the first and third year of the study (SLIT n=39; placebo n=38).

RESULTS

The multiple symptom-medication score was significantly reduced by SLIT to 77.3% of the placebo group (P=0.0498). The subsequent analysis of the single endpoints did not reveal significant differences for symptom scores in favour of SLIT (85.1% of placebo group; P=0.22). However, the medication score improved significantly (67.1% of placebo group; P=0.0025). Furthermore, secondary endpoints assessing in vivo immune responses did not differ significantly between the groups. However, retrospective analysis showed some inhomogeneity for clinical and in vitro parameters at the beginning of the study. Allergic side effects with possible relation to the study drug were reported in both groups (SLIT 49%, placebo 27%, P=0.026).

CONCLUSION

Our study indicates that SLIT had a positive effect on the reduction of a multiple symptom-medication score, mainly by significantly reducing rescue medication use, but had no significant effect on symptoms alone in children with rhinoconjunctivitis to grass pollen compared with a placebo.

Comparison of the clinical efficacy and safety of subcutaneous and sublingual immunotherapy: methodological approaches and experimental results

PURPOSE OF REVIEW

Sublingual immunotherapy has been documented as clinically effective in controlled studies. Some concerns about the magnitude of disease severity reduction in relation to standard subcutaneous immunotherapy have been raised. The comparison with subcutaneous immunotherapy is important for giving recommendations on the use of sublingual immunotherapy in daily clinical practice.

RECENT FINDINGS

Only three controlled comparative studies of sublingual and subcutaneous immunotherapy have been published. The methodology of the studies indicated that some study design deficiencies limited the interpretation of efficacy. Only one study used an optimal placebo-controlled, double-blind, double-dummy and randomized design. The studies are assessed with respect to a sufficient number of patients to detect statistically possible differences, the inclusion of patients, clearly defined outcome measures, doses of extract administered, and duration of treatment. In all three studies the reduction in disease severity was of the order of 50% with no significant difference between the two treatments.

SUMMARY

The clinical efficacy of sublingual immunotherapy is based on three studies only, and a limited number of patients equal to the efficacy obtained by subcutaneous immunotherapy. Only limited information on long-term efficacy and preventative capacity are available. More data on these aspects are needed, but the restraint in using sublingual immunotherapy in the treatment strategy of allergic diseases does not seem to be evidence based. Future research should also focus on identifying which subsets of patients would most benefit from either of the two routes of immunotherapy administration.

Sublingual immunotherapy: an update

PURPOSE OF REVIEW

Sublingual immunotherapy is now officially accepted as a viable alternative to the traditional subcutaneous route, and it is widely used especially in European countries. Despite the large amount of experimental evidence on the safety and efficacy of the method, some concerns still exist, and several aspects need to be clarified: magnitude of the efficacy, adherence, long-lasting effect and others. Recently published studies have provided answers to some of these points.

RECENT FINDINGS

The most recent studies have shown that sublingual immunotherapy exerts a long-lasting effect up to 5 years after discontinuation and that it is able to prevent the onset of new sensitizations. Moreover, when systematically assessed, the adherence to treatment is quite satisfactory, despite the treatment being self-administered. In addition, evidence has been provided that sublingual immunotherapy is effective in treating allergic conjunctivitis, and a metaanalysis has confirmed its efficacy in rhinitis. Moreover, some studies have addressed the possibility of simplifying the schedule of administration by shortening the build-up phase.

SUMMARY

More and more new data on sublingual immunotherapy are rapidly appearing in the international literature. These data confirm the clinical value of this treatment and show that it is comparable to subcutaneous immunotherapy from several points of view.

Randomized controlled open study of sublingual immunotherapy for respiratory allergy in real-life: clinical efficacy and more

BACKGROUND

Some aspects of sublingual immunotherapy (SLIT) still need to be addressed: magnitude of the clinical efficacy, effect on the bronchial hyperreactivity adherence to treatment, preventive effect. We attempted to clarify these points in a randomized open, controlled, two parallel group study in a real-life setting.

METHODS

Five hundred and eleven patients with allergic rhinitis with or without intermittent asthma were randomized to drugs only or drugs + SLIT (rate 2 : 3) for 3 years. The clinical score (symptoms + drug intake) was measured each year during the allergen exposure. Pulmonary function test, methacholine challenge and skin tests were performed at the beginning and at the end of the study. Adherence to treatment was assessed by measuring the consumed extract.

RESULTS

Three hundred and nineteen patients received SLIT and 192 drugs only. Dropouts were 15% in the SLIT group and 12% in the controls. There was a significant improvement of clinical scores in the SLIT group: baseline 147 +/- 3.3, first year 72.9 +/- 1.3, second year 68.3 +/- 1.8, third year 54.7 +/- 2.8 (P < 0.0001 vs baseline).

CONTROL GROUP

baseline 138 +/- 2.3, first year 124.1 +/- 3.7, second year 111 +/- 3.3, third year 121 +/- 3.8 (P = NS). Only four patients reported systemic itching. Adherence was >80% in 72% and >60% in 18% of patients. The number of patients with a positive MCh challenge decreased significantly after 3 years only in the SLIT group. New skin sensitizations appeared in 38% of the controls and in 5.9% of the SLIT patients (P = 0.01).

CONCLUSION

Sublingual immunotherapy approximately halved the clinical scores and significantly reduced the bronchial hyperreactivity. Similarly to subcutaneous immunotherapy, SLIT displayed a preventive effect on the onset of new skin sensitizations. The adherence rate was quantitatively satisfactory.

Efficacy and safety of sublingual immunotherapy

OBJECTIVE

To review the available published data concerning the use of sublingual immunotherapy (SLIT) in respiratory allergy to primarily evaluate the clinical efficacy and safety of the treatment and to secondarily consider the mechanisms of action and any unresolved questions.

DATA SOURCES

Articles in the medical literature (starting from 1986 up to November 2003) derived from searching the MEDLINE database with the keywords sublingual immunotherapy, respiratory allergy, asthma, and rhinitis. Sources included review articles, randomized controlled clinical trials, postmarketing surveillance studies, and relevant reports from meeting proceedings.

STUDY SELECTION

Articles concerning safety, efficacy, and mechanisms of SLIT published in English-language, peer-reviewed journals.

RESULTS

SLIT proved effective and safe in adults and children. As with traditional subcutaneous immunotherapy, SLIT has long-lasting efficacy and a preventive effect on new sensitizations.

CONCLUSION

SLIT is a viable alternative to subcutaneous immunotherapy. Its use in pediatric patients seems to be particularly promising.

Sublingual immunotherapy abrogates seasonal bronchial hyperresponsiveness in children with Parietaria-induced respiratory allergy: a randomized controlled trial

BACKGROUND

The use of immunotherapy in asthmatic children is still controversial. Sublingual immunotherapy (SLIT) may represent an advance, due to the good safety profile, but little is known about its effects on lung function and nonspecific bronchial responsiveness.

OBJECTIVE

The aim of this study was to assess the effects of SLIT on these parameters, in children with Parietaria pollen-induced asthma.

METHODS

Thirty children with asthma solely due to Parietaria who participated in a previous randomized, placebo-controlled trial with SLIT were studied: pulmonary function test and methacholine challenge were carried out at baseline in winter 1999 (out season), during the 1999 season (before randomization), and during the 2001 season.

RESULTS

Before randomization, there was a significant fall in methacholine provocation concentration during the pollen season vs baseline in both groups (SLIT group 9.78 +/- 5.95 mg/ml vs 3.37 +/- 2.99 mg/ml; placebo 8.70 +/- 6.25 mg/ml vs 2.44 +/- 2.25 mg/ml; P =.005). In the second pollen season, the response to methacholine returned to baseline values in the active group (9.10 +/- 7.7 mg/ml; P = NS vs baseline), whereas in the placebo group a significant increase in reactivity was still present (2.46 +/- 2.26; P = 0.008 vs baseline). No significant difference in FEV(1) and FEF(25-75) between the two groups was observed at all times.

CONCLUSIONS

Our data show that SLIT abrogates the seasonal bronchial hyperreactivity in children with asthma due to Parietaria. This may be regarded as an indirect evidence of the effect on bronchial inflammation.

[Specific immunotherapy. Hyposensitization with allergens]

Successful allergen-specific immunotherapy (SIT) induces complex immunologic chan-ges resulting in reduced allergic inflammatory reactions. SIT has long-term effects in mild forms of inhalant allergies and is effective even when standard pharmacotherapy fails. Moreover, the risk to develop additional allergic sensitizations and the development of asthma is significantly reduced in children with allergic rhinitis. SIT is the treatment of choice in patients with systemic reactions to hymenoptera venoms. Although the exact effector mechanisms of SIT still have to be clarified, the most probable effect is a modulation of regulatory T cells associated with a switch of allergen-specific B-cells towards IgG4 production. The critical point to insure efficacy and safety is the selection of patients and allergens, task best performed by a specialist trained in allergology. Further details are available in the position papers of the German allergy societies - DGAI(Deutsche Gesellschaft fiir Allergologie und Klinische Immunologie) and ADA (Arzte-verband Deutscher Allergologen) - which can be found at www.dgaki.de.

Advances in upper airway diseases and allergen immunotherapy

Evidence for one airway continues to accumulate. Nasal allergen challenges increase lower airway inflammation, and nasal corticosteroid treatment reduces lower airway inflammation. Allergic respiratory inflammation might even spread systemically to involve nonrespiratory organs. Eosinophilic enteritis and eosinophilic esophagitis are reported during pollen seasons in patients with seasonal allergic rhinitis. Chronic hypertrophic sinusitis (CHS) is found in the majority of patients with asthma. Like asthma, the histology of CHS is characterized by epithelial damage, basement membrane thickening, and eosinophilic inflammation. The damaged epithelium might explain the acute bacterial exacerbations seen in patients with CHS. Studies have extended evidence of the safety and efficacy of the second- and third-generation antihistamines to younger children and to patients with perennial rhinitis but continue to show improvement of symptom scores over that seen with placebo of less than 20%. Studies on antihistamine use in the first trimester in nearly 500 women (65% taking loratadine) revealed no increase in the complications of pregnancy or congenital anomalies. Positive skin prick test responses to birch in asymptomatic young adults predicted later development of clinical allergic rhinitis. A dose response was demonstrated for immunotherapy with cat dander extract. The best results were in subjects receiving a dose containing 15 microg of the major cat allergen Fel d 1 (equivalent to approximately 2500 bioequivalent allergen units). Both topical intranasal immunotherapy and high-dose sublingual immunotherapy have been repeatedly proved to be safe and effective in double-blind, placebo-controlled studies. CD4+CD25+ regulatory T cells secreting IL-10, TGF-beta, or both appear important in normal individuals and in patients treated with allergen immunotherapy in maintaining or restoring normal T(H)1/T(H)2 balance and overall suppression of both phenotypes.

The potential role of allergen-specific sublingual immunotherapy in atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease associated with increasing prevalence, morbidity, and cost in developed Western countries. Frequently associated with respiratory allergy during adulthood, atopic dermatitis often represents the first phenotypic appearance of atopy in early childhood when the allergic 'march' starts and progressively moves toward food allergy, asthma, and rhinitis. At present, a consistent body of evidence supports the view that atopic dermatitis may represent the skin compartmentalization of a systemic allergic inflammation. Lymphocytes infiltrating early lesional skin express a T helper (Th) 2 pattern of cytokine secretion (increased levels of interleukin [IL]-4 and/or IL-13 and decreased levels of interferon-gamma) as well as the typical Th2-type chemokine receptor CCR4, specific to the thymus and activation-regulated chemokines. Keratinocytes from patients with atopic dermatitis produce thymic stromal lymphopoietin, a novel cytokine that supports the early lymphocyte development in mouse models, and activates dendritic cells involved in the pathogenesis of allergic diseases in humans. Increased levels of circulating hemopoietic precursor cells have been reported in atopic dermatitis, as in allergic asthma and rhinitis. Furthermore, the recognition of CD34+ hemopoietic precursor cells, and evidence for cellular differentiation/maturational events occurring within atopic dermatitis skin lesion infiltrates, are consistent with the recent reinterpretation of the Th2/Th1 paradigm, where Th2 cells appear to belong to the early stages and Th1 to the ultimate stages of a linear, rather than divergent, pattern of lymphoid differentiation. This more detailed understanding of the immunologic derangements contributing to the atopic dermatitis pathogenesis has led to growing interest in allergen-specific immunotherapy for the disease. Due to the complexity intrinsic to atopic dermatitis and the lack of consensus-based guidelines for standardized outcome measure, only eight studies are available in the literature for a qualitative evaluation of this treatment approach. Two of these studies were double blind and placebo controlled, and six were cohort studies. Immunotherapy was found to be effective in one controlled study and five observational reports. Uncertain results were provided by one low-powered, controlled study, and negative outcomes were raised by a unique study performed with oral immunotherapy, which is not an effective route of mucosal allergen administration. Thus, more efficacy studies are required before immunotherapy could be recommended for the routine treatment of atopic dermatitis. Allergen-specific sublingual immunotherapy, given its excellent safety profile and ability to interfere with the systemic aspects of allergic inflammation, appears a good potential candidate for the pathogenetic treatment of the disease.