Imaging of chronic rhinosinusitis with nasal polyps in the era of biological therapies

PURPOSE OF REVIEW

Chronic rhinosinusitis (CRS) is a chronic inflammatory disorder of the sinonasal cavities classified into two major phenotypes: CRS with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP). The diagnosis of CRS is based on clinical symptoms associated with imaging and/or nasal endoscopy findings of mucosal inflammation.

RECENT FINDINGS

Recently, novel biological therapies have emerged as therapeutic options for CRSwNP. Imaging is helpful in deciding whether surgery is likely to be beneficial and in guiding surgery. It can also help demonstrate a clinical response to medical therapy. However, specific guidelines concerning the role of imaging in CRwNP are lacking.

SUMMARY

This article provides a comprehensive and critical multidisciplinary review of the role of conventional radiology, computed tomography (CT), and magnetic resonance imaging (MRI) in the diagnosis and characterization of CRSwNP. Since the complete characterization of nasal polyps on CT or MR images is very challenging, we provide a critical review of the best imaging methods and essential reporting elements used to assess nasal polyps.

Nasal and blood transcriptomic pathways underpinning the clinical response to grass pollen immunotherapy

BACKGROUND

Allergen immunotherapy (AIT) is a well-established disease-modifying therapy for allergic rhinitis, yet the fundamental mechanisms underlying its clinical effect remain inadequately understood. Gauging Response in Allergic Rhinitis to Sublingual and Subcutaneous Immunotherapy was a randomized, double-blind, placebo-controlled trial of individuals allergic to timothy grass who received 2 years of placebo (n = 30), subcutaneous immunotherapy (SCIT) (n = 27), or sublingual immunotherapy (SLIT) (n = 27) and were then followed for 1 additional year.

OBJECTIVE

We used yearly biospecimens from the Gauging Response in Allergic Rhinitis to Sublingual and Subcutaneous Immunotherapy study to identify molecular mechanisms of response.

METHODS

We used longitudinal transcriptomic profiling of nasal brush and PBMC samples after allergen provocation to uncover airway and systemic expression pathways mediating responsiveness to AIT.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01335139, EudraCT Number: 2010-023536-16.

RESULTS

SCIT and SLIT demonstrated similar changes in gene module expression over time. In nasal samples, alterations included downregulation of pathways of mucus hypersecretion, leukocyte migration/activation, and endoplasmic reticulum stress (log2 fold changes -0.133 to -0.640, false discovery rates [FDRs] <0.05). We observed upregulation of modules related to epithelial development, junction formation, and lipid metabolism (log2 fold changes 0.104 to 0.393, FDRs <0.05). In PBMCs, modules related to cellular stress response and type 2 cytokine signaling were reduced by immunotherapy (log2 fold changes -0.611 to -0.828, FDRs <0.05). Expression of these modules was also significantly associated with both Total Nasal Symptom Score and peak nasal inspiratory flow, indicating important links between treatment, module expression, and allergen response.

CONCLUSIONS

Our results identify specific molecular responses of the nasal airway impacting barrier function, leukocyte migration activation, and mucus secretion that are affected by both SCIT and SLIT, offering potential targets to guide novel strategies for AIT.

A Pilot Study to Evaluate the Dietary Intake of Adults Attending a Food Allergy Clinic, and Compare the Results Against the Final Diagnostic Outcome

Background: The impact of poor diet on growth and development in children with a food allergy is well-recognized and researched. Food allergy is an increasing problem in adults, as are food intolerances. Another issue is the rising number of individuals adopting a vegetarian or vegan lifestyle. Studies evaluating the diet of adolescents and adults with food allergy against controls suggest their dietary intakes are similar. We wished to evaluate all patients attending a food allergy clinic to determine whether there were dietary and nutritional differences between those with a food allergy or a food intolerance. Methods: All adults newly referred to a secondary care food allergy clinic in a UK hospital, in a 1-month period, were included in the study. Prior to their appointment, those who consented to take part had their height and weight documented and an assessment made of their habitual food intake. Their subsequent diagnosis was reviewed, and results for those with a confirmed diagnosis of food allergy were compared to those with a food intolerance or where the cause of symptoms was unknown. Results: Thirty subjects were recruited, with full results available for 29 subjects, 15 of whom (52%) were diagnosed with a new/existing food allergy (FA). For the whole cohort, dietary intake was sufficient for protein, and most vitamins and minerals, whereas energy, carbohydrate, unsaturated fat and fiber intakes were well-below the reference range. Those with a FA had lower intakes of iron, zinc and vitamin B12 compared to those with no FA. In addition, iron and energy intakes were depleted in those avoiding nuts, and wheat avoidance was linked to a lower intake of riboflavin. Conclusion: The results from this small exploratory study suggest that whilst the majority of nutrients in the diet are sufficient in adults presenting to the food allergy clinic, intakes of energy and fiber may be below the reference range. Those with a food allergy are more likely to have a reduced intake of iron, zinc and vitamin B12. As others have demonstrated, the exclusion of specific food groups can also affect nutritional intakes.

Innate and adaptive immunity in allergic airway disease

PURPOSE OF REVIEW

This article explores recent findings on the involvement of innate immunity in allergic airways disease, concentrating on allergic rhinitis.

RECENT FINDINGS

We speculate on the ways in which environmental influences act to initiate inflammation and on how these may have altered in recent decades. Improved understanding of the mechanisms involved may reveal future possibilities for therapy.

SUMMARY

The complex nature of immunity - both innate and acquired - in airways disease has implications for prevention and for therapy and requires further elucidation.

Differential induction of allergen-specific IgA responses following timothy grass subcutaneous and sublingual immunotherapy

INTRODUCTION

There is no detailed comparison of allergen-specific immunoglobulin responses following sublingual immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT).

OBJECTIVE

We sought to compare nasal and systemic timothy grass pollen (TGP)-specific antibody responses during 2 years of SCIT and SLIT and 1 year after treatment discontinuation in a double-blind, double-dummy, placebo-controlled trial.

METHODS

Nasal fluid and serum were obtained yearly (per-protocol population, n = 84). TGP-specific IgA₁, IgA₂, IgG₄, IgG, and IgE were measured in nasal fluids by ELISA. TGP-specific IgA₁, IgA₂, and Phleum pratense (Phl p)1, 2, 4, 5b, 6, 7, 11, and 12 IgE and IgG₄ were measured in sera by ELISA and ImmunoCAP, respectively.

RESULTS

At years 2 and 3, TGP-IgA_1/2 levels in nasal fluid were elevated in SLIT compared with SCIT (4.2- and 3.0-fold for IgA₁, 2.0- and 1.8-fold for IgA₂, respectively; all P < .01). TGP-IgA₁ level in serum was elevated in SLIT compared with SCIT at years 1, 2, and 3 (4.6-, 5.1-, and 4.7-fold, respectively; all P < .001). Serum TGP-IgG level was higher in SCIT compared with SLIT (2.8-fold) at year 2. Serum TGP-IgG₄ level was higher in SCIT compared with SLIT at years 1, 2, and 3 (10.4-, 27.4-, and 5.1-fold, respectively; all P < .01). Serum IgG₄ levels to Phl p1, 2, 5b, and 6 were increased at years 1, 2, and 3 in SCIT and SLIT compared with placebo (Phl p1: 11.8- and 3.9-fold; Phl p2: 31.6- and 4.4-fold; Phl p5b: 135.5- and 5.3-fold; Phl p6: 145.4- and 14.7-fold, respectively, all at year 2 when levels peaked; P < .05). IgE to TGP in nasal fluid increased in the SLIT group at year 2 but not at year 3 compared with SCIT (2.8-fold; P = .04) and placebo (3.1-fold; P = .02). IgA to TGP and IgE and IgG₄ to TGP components stratified participants according to treatment group and clinical response.

CONCLUSIONS

The observed induction of IgA_1/2 in SLIT and IgG₄ in SCIT suggest key differences in the mechanisms of action.

Innate and Adaptive Immunity: ILC2 and Th2 Cells in Upper and Lower Airway Allergic Diseases

Advances in our understanding of the immune system, with the recent discovery of a parallel set of innate T lymphocytes, the innate lymphocytes (ILCs), have led to a reassessment of the pathogenesis of allergic and eosinophilic airway disorders, including allergic rhinitis (AR), asthma, and chronic rhinosinusitis with nasal polyps. We review current understanding of both elements of type-2 inflammatory responses and their relative influence in these common conditions and consider possible impacts of this on treatment selection.

Altered chromatin landscape in circulating T follicular helper and regulatory cells following grass pollen subcutaneous and sublingual immunotherapy

BACKGROUND

Allergen-specific immunotherapy is a disease-modifying treatment that induces long-term T-cell tolerance.

OBJECTIVE

We sought to evaluate the role of circulating CXCR5⁺PD-1⁺ T follicular helper (cT_FH) and T follicular regulatory (T_FR) cells following grass pollen subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) and the accompanying changes in their chromatin landscape.

METHODS

Phenotype and function of cT_FH cells were initially evaluated in the grass pollen-allergic (GPA) group (n = 28) and nonatopic healthy controls (NAC, n = 13) by mathematical algorithms developed to manage high-dimensional data and cell culture, respectively. cT_FH and T_FR cells were further enumerated in NAC (n = 12), GPA (n = 14), SCIT- (n = 10), and SLIT- (n = 8) treated groups. Chromatin accessibility in cT_FH and T_FR cells was assessed by assay for transposase-accessible chromatin sequencing (ATAC-seq) to investigate epigenetic mechanisms underlying the differences between NAC, GPA, SCIT, and SLIT groups.

RESULTS

cT_FH cells were shown to be distinct from T_H2- and T_H2A-cell subsets, capable of secreting IL-4 and IL-21. Both cytokines synergistically promoted B-cell class switching to IgE and plasma cell differentiation. Grass pollen allergen induced cT_FH-cell proliferation in the GPA group but not in the NAC group (P < .05). cT_FH cells were higher in the GPA group compared with the NAC group and were lower in the SCIT and SLIT groups (P < .01). Time-dependent induction of IL-4, IL-21, and IL-6 was observed in nasal mucosa following intranasal allergen challenge in the GPA group but not in SCIT and SLIT groups. T_FR and IL-10⁺ cT_FH cells were induced in SCIT and SLIT groups (all, P < .01). ATAC-seq analyses revealed differentially accessible chromatin regions in all groups.

CONCLUSIONS

For the first time, we showed dysregulation of cT_FH cells in the GPA group compared to NAC, SCIT, and SLIT groups and induction of T_FR and IL-10⁺ cT_FH cells following SCIT and SLIT. Changes in the chromatin landscape were observed following allergen-specific immunotherapy in cT_FH and T_FR cells.

Nasal allergen challenge and environmental exposure chamber challenge: A randomized trial comparing clinical and biological responses to cat allergen

BACKGROUND

The direct-instillation nasal allergen challenge (NAC) and the environmental exposure chamber (EEC) are 2 methods of conducting controlled allergen provocations. The clinical and biological comparability of these methods has not been thoroughly investigated.

OBJECTIVE

We sought to compare clinical and immunologic responses to cat allergen in NAC versus EEC.

METHODS

Twenty-four participants were randomized to receive either NAC followed by a 2-day challenge in an EEC or a 2-day challenge in an EEC followed by NAC. Challenges were separated by 28-day washout periods. We measured total nasal symptom scores, peak nasal inspiratory flow, nasal (0-8 hours) and serum cytokines, serum antibodies, peripheral blood antigen-specific T lymphocytes, and gene expression in nasal scrapings. The primary outcome was the total nasal symptom score area under the curve for the first 3 hours after allergen exposure in NAC or after initiation of exposure in EEC.

RESULTS

Both challenges increased IL-5 and IL-13 in nasal fluids and serum and resulted in altered nasal cell expression of gene modules related to mucosal biology and transcriptional regulation. Changes in gene modules, more so than cytokine measurements, showed significant associations with total nasal symptom score and peak nasal inspiratory flow. Overall, EEC exposure generated larger responses and more early terminations compared with NAC. Although the 2 challenges did not correlate in symptom magnitude or temporality, striking correlations were observed in cytokine levels.

CONCLUSIONS

Although clinical outcomes of NAC and EEC were temporally different and nonequivalent in magnitude, immunologic responses were similar. Selection of a particular allergen challenge method should depend on considerations of study objectives and cost.

The Intriguing Role of Interleukin 13 in the Pathophysiology of Asthma

Approximately 5–10% of asthmatic patients worldwide suffer from severe asthma. Experimental and clinical studies have demonstrated that IL-13 is an important cytokine in chronic airways inflammation. IL-13 is involved in Th2 inflammation and has been identified as a possible therapeutic target in the treatment of asthma. Two different human monoclonal antibodies (mAbs) anti-IL-13 (tralokinumab and lebrikizumab) block binding and signaling of IL-13 to its receptors, IL-13Rα1 and IL-13Rα2. Several randomized, double-blind, placebo-controlled multicenter studies have evaluated the safety and efficacy of tralokinumab and lebrikizumab in the treatment of adult patients with severe asthma, but all have failed to meet their primary endpoints. No serious adverse events related to the treatment with these anti-IL-13 mAbs have been reported in these studies. These negative clinical results contrast with positive findings from blocking IL-13 signaling in experimental models of asthma, raising doubts about the transferrable value of some models. Interestingly, dupilumab, a mAb which blocks both IL-4 and IL-13 signaling reduces exacerbation rates and improves lung function in severe asthmatics. These results suggest that IL-4 and IL-13 share some, but not all functional activities in airway inflammation. Tralokinumab might show efficacy in a highly selected cohort of asthmatics characterized by overexpression of IL-13.

Duration of Allergen Immunotherapy for Long-Term Efficacy in Allergic Rhinoconjunctivitis

RATIONALE

Subcutaneous and sublingual immunotherapy are effective for allergic rhinitis. An important question is whether allergen immunotherapy provides a sustained clinical effect after treatment cessation. In view of potential side effects, cost and the necessary patient commitment, long-term benefit is an important consideration for the recommendation of immunotherapy over standard pharmacotherapy.

PURPOSE OF REVIEW

In this review, we analyse the existing evidence for long-term effects of both routes of administration in the context of double-blind, placebo-controlled, randomised clinical trials that included a follow-up phase of at least 1 year after treatment cessation.

RECENT FINDINGS

Overall, evidence suggests that 3 years of either subcutaneous or sublingual immunotherapy result in clinical benefit and immunological changes consistent with allergen-specific tolerance sustained for at least 2-3 years after treatment cessation.

SUMMARY

The data presented here support recommendations in international guidelines that both routes of administration should be continued for a minimum of 3 years. Gaps in the evidence remain regarding the long-term efficacy of immunotherapy for perennial rhinitis and studies performed in children.

Synchronous immune alterations mirror clinical response during allergen immunotherapy

BACKGROUND

Three years of treatment with either sublingual or subcutaneous allergen immunotherapy has been shown to be effective and to induce long-term tolerance. The Gauging Response in Allergic Rhinitis to Sublingual and Subcutaneous Immunotherapy (GRASS) trial demonstrated that 2 years of treatment through either route was effective in suppressing the response to nasal allergen challenge, although it was insufficient for inhibition 1 year after discontinuation.

OBJECTIVE

We sought to examine in the GRASS trial the time course of immunologic changes during 2 years of sublingual and subcutaneous immunotherapy and for 1 year after treatment discontinuation.

METHODS

We performed multimodal immunomonitoring to assess allergen-specific CD4 T-cell properties in parallel with analysis of local mucosal cytokine responses induced by nasal allergen exposure and humoral immune responses that included IgE-dependent basophil activation and measurement of serum inhibitory activity for allergen-IgE binding to B cells (IgE-facilitated allergen binding).

RESULTS

All 3 of these distinct arms of the immune response displayed significant and coordinate alterations during 2 years of allergen desensitization, followed by reversal at 3 years, reflecting a lack of a durable immunologic effect. Although frequencies of antigen-specific T_H2 cells in peripheral blood determined by using HLA class II tetramer analysis most closely paralleled clinical outcomes, IgE antibody-dependent functional assays remained inhibited in part 1 year after discontinuation.

CONCLUSION

Two years of allergen immunotherapy were effective but insufficient for long-term tolerance. Allergen-specific T_H2 cells most closely paralleled the transient clinical outcome, and it is likely that recurrence of the T-cell drivers of allergic immunity abrogated the potential for durable tolerance. On the other hand, the persistence of IgE blocking antibody 1 year after discontinuation might be an early indicator of a protolerogenic mechanism.

Effect of 2 Years of Treatment With Sublingual Grass Pollen Immunotherapy on Nasal Response to Allergen Challenge at 3 Years Among Patients With Moderate to Severe Seasonal Allergic Rhinitis: The GRASS Randomized Clinical Trial

IMPORTANCE

Sublingual immunotherapy and subcutaneous immunotherapy are effective in seasonal allergic rhinitis. Three years of continuous treatment with subcutaneous immunotherapy and sublingual immunotherapy has been shown to improve symptoms for at least 2 years following discontinuation of treatment.

OBJECTIVE

To assess whether 2 years of treatment with grass pollen sublingual immunotherapy, compared with placebo, provides improved nasal response to allergen challenge at 3-year follow-up.

DESIGN, SETTING, AND PARTICIPANTS

A randomized double-blind, placebo-controlled, 3-parallel-group study performed in a single academic center, Imperial College London, of adult patients with moderate to severe seasonal allergic rhinitis (interfering with usual daily activities or sleep). First enrollment was March 2011, last follow-up was February 2015.

INTERVENTIONS

Thirty-six participants received 2 years of sublingual immunotherapy (daily tablets containing 15 µg of major allergen Phleum p 5 and monthly placebo injections), 36 received subcutaneous immunotherapy (monthly injections containing 20 µg of Phleum p 5 and daily placebo tablets) and 34 received matched double-placebo. Nasal allergen challenge was performed before treatment, at 1 and 2 years of treatment, and at 3 years (1 year after treatment discontinuation).

MAIN OUTCOMES AND MEASURES

Total nasal symptom scores (TNSS; range; 0 [best] to 12 [worst]) were recorded between 0 and 10 hours after challenge. The minimum clinically important difference for change in TNSS within an individual is 1.08. The primary outcome was TNSS comparing sublingual immunotherapy vs placebo at year 3. Subcutaneous immunotherapy was included as a positive control. The study was not powered to compare sublingual immunotherapy with subcutaneous immunotherapy.

RESULTS

Among 106 randomized participants (mean age, 33.5 years; 34 women [32.1%]), 92 completed the study at 3 years. In the intent-to-treat population, mean TNSS score for the sublingual immunotherapy group was 6.36 (95% CI, 5.76 to 6.96) at pretreatment and 4.73 (95% CI, 3.97 to 5.48) at 3 years, and for the placebo group, the score was 6.06 (95% CI, 5.23 to 6.88) at pretreatment and 4.81 (95% CI, 3.97 to 5.65) at 3 years. The between-group difference (adjusted for baseline) was -0.18 (95% CI, -1.25 to 0.90; [P = .75]).

CONCLUSIONS AND RELEVANCE

Among patients with moderate to severe seasonal allergic rhinitis, 2 years of sublingual grass pollen immunotherapy was not significantly different from placebo in improving the nasal response to allergen challenge at 3-year follow-up.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01335139; EudraCT Number: 2010-023536-16.

Diagnosing Allergic Rhinitis

Allergic rhinitis (AR) is the most common immunologic disease in industrialized societies and has a significant impact on quality of life. Most asthmatics also have rhinitis. AR may present with comorbidities, including chronic otitis media with effusion, cough, and pollen-food cross-reactivity. AR may occur in isolation or be part of a mixed rhinitis.

Local and systemic effects of cat allergen nasal provocation

Background

Cat allergen is widely distributed in homes and schools; allergic sensitization is common.

Objective

To develop a model of cat allergen nasal challenge to establish dose–response and time–course characteristics and investigate local and systemic biomarkers of allergic inflammation.

Methods

Nineteen cat‐allergic individuals underwent titrated nasal challenge, range 0.243 to 14.6 μg/mL Fel d1, and matched diluent‐only provocation. Clinical response to 8 h was assessed by symptom scores and peak nasal inspiratory flow (PNIF). Nasal fluid was collected using polyurethane sponges and analysed by ImmunoCAP and multiplex assays. Whole blood flow cytometry for basophil surface CD63, CD107a, and CD203c was carried out at baseline and 6 h post‐challenge.

Results

A dose–response to allergen was seen in symptom scores and PNIF, maximal at 10 000 BU/mL (4.87 μg/mL Fel d1), P < 0.0001 vs. diluent. Nasal fluid tryptase was elevated at 5 min after challenge (P < 0.05 vs. diluent); eotaxin, IL‐4, ‐5, ‐9, and ‐13 were increased at 8 h (P < 0.05 to P < 0.0001 vs. diluent); TSLP was undetectable; IL‐10, IL‐17A, and IL‐33 were unchanged compared to diluent challenge. Nasal fluid IL‐5 and IL‐13 correlated inversely with PNIF after challenge (IL‐5, r = −0.79, P < 0.0001; IL‐13, r = −0.60, P = 0.006). Surface expression of CD63 and CD107a was greater at 6 h than at baseline, both in the presence (both P < 0.05) and absence (CD63, P < 0.01; CD107a, P < 0.05) of in vitro allergen stimulation; no changes were seen on diluent challenge day.

Conclusions

Cat allergen nasal challenge produces local and systemic Th2‐driven inflammatory responses and has potential as a surrogate outcome measure in clinical trials.

Short-term subcutaneous grass pollen immunotherapy under the umbrella of anti-IL-4: A randomized controlled trial

BACKGROUND

Allergen immunotherapy is currently the only disease-modifying treatment available for allergic rhinitis and allergic asthma.

OBJECTIVES

We sought to evaluate the induction of sustained tolerance to allergen when anti-IL-4 was combined with a suboptimal course of grass pollen subcutaneous immunotherapy (SCIT) using the allergen-induced skin late-phase response (LPR) and exploratory immune monitoring as surrogate markers of therapeutic response.

METHODS

In this randomized, double-blind, 3-group parallel design trial, 37 participants with seasonal allergic rhinitis received suboptimal SCIT (30,000 standardized quality units) in combination with anti-IL-4 (VAK694) and suboptimal SCIT (30,000 standardized quality units) plus placebo antibody or double placebo (placebo SCIT and placebo antibody) restricted to 13 weeks before the grass pollen season. The primary end point was the size of the LPR at 12 months. Exploratory end points included measures of the immunomodulatory activity of treatment by using IL-4 and IL-10 FluoroSpot assays, flow cytometry of T cells, and measurement of IgE, IgG4, and facilitated antigen binding.

RESULTS

Both active treatment arms led to a substantial and sustained reduction of the LPR with no additional suppression with addition of anti-IL-4. Treatment with anti-IL-4 and SCIT compared with SCIT alone led to a sustained reduction in allergen-specific IL-4-producing cell counts (P < .01). Both active treatment arms led to induction of dual IL-4/IL-10-producing cells during the pollen season.

CONCLUSION

The combination of anti-IL-4 with SCIT provided no additional benefit over SCIT alone in suppressing the allergen-induced skin LPR. A larger trial is needed to assess whether the observed ex vivo downregulation of TH2 responses might translate into clinical benefit.

Basophil expression of diamine oxidase: a novel biomarker of allergen immunotherapy response

BACKGROUND

Immunotherapy inhibits basophil histamine release, but the assay is cumbersome, and no one has studied the effects of immunotherapy withdrawal.

OBJECTIVE

Intracellular fluorochrome-labeled diamine oxidase (DAO) was used as a novel functional readout of basophil histamine release after immunotherapy. Results were compared with conventional basophil surface expression of activation markers.

METHODS

Subcutaneous immunotherapy (SCIT)-treated patients (n = 14), sublingual immunotherapy (SLIT)-treated patients (n = 12), participants who completed 3 years of treatment with grass pollen sublingual immunotherapy (the SLIT-TOL group; n = 6), patients with untreated seasonal allergic rhinitis (SAR; n = 24), and nonatopic control subjects (n = 12) were studied. Intracellularly labeled DAO(+) and surface expression of CD203c(bright), CD63(+), and CD107a(+) on chemoattractant receptor-homologous molecule expressed on TH2 lymphocytes (CRTh2)-positive basophils were measured by means of flow cytometry. Serum IgG4 levels and serum inhibitory activity for IgE-allergen complex binding to B cells (IgE-FAB) and basophil histamine release were also determined.

RESULTS

Proportions of allergen-stimulated DAO(+)CRTh2(+) basophils were higher in participants in the SCIT, SLIT, and SLIT-TOL groups (all P < .0001) compared with those in patients in the SAR group. Similarly, there were lower proportions of CRTh2(+) basophils expressing surface CD203c(bright) (all P < .001), CD63 (all P < .001), and CD107a (all P < .01). Rhinitis symptoms were lower in the SCIT, SLIT, and SLIT-TOL groups (P < .001) compared with those in the SAR group. Serum inhibitory activity for IgE-FAB and basophil histamine release were also significantly greater in all immunotherapy groups (P < .05) compared with the SAR group.

CONCLUSION

These results support long-term clinical and immunologic tolerance during and after grass pollen immunotherapy. Intracellularly labeled DAO expression by basophils merits further investigation as a surrogate biomarker for monitoring efficacy and tolerance after immunotherapy.

Sublingual grass pollen immunotherapy is associated with increases in sublingual Foxp3-expressing cells and elevated allergen-specific immunoglobulin G4, immunoglobulin A and serum inhibitory activity for immunoglobulin E-facilitated allergen binding to B cells

BACKGROUND

The mechanisms of sublingual immunotherapy (SLIT) are less well understood than those of subcutaneous immunotherapy (SCIT).

OBJECTIVES

To determine the effects of grass-pollen SLIT on oral mucosal immune cells, local regulatory cytokines, serum allergen-specific antibody subclasses and B cell IgE-facilitated allergen binding (IgE-FAB).

METHODS

Biopsies from the sublingual mucosa of up to 14 SLIT-treated atopics, nine placebo-treated atopics and eight normal controls were examined for myeloid dendritic cells (mDCs) (CD1c), plasmacytoid dendritic cells (CD303), mast cells (AA1), T cells (CD3) and Foxp3 using immunofluorescence microscopy. IL-10 and TGF-beta mRNA expression were identified by in situ hybridization. Allergen-specific IgG and IgA subclasses and serum inhibitory activity for binding of allergen-IgE complexes to B cells (IgE-FAB) were measured before, during and on the completion of SLIT.

RESULTS

Foxp3(+) cells were increased in the oral epithelium of SLIT- vs. placebo-treated atopics (P=0.04). Greater numbers of subepithelial mDCs were present in placebo-treated, but not in SLIT-treated, atopics compared with normal controls (P=0.05). There were fewer subepithelial mast cells and greater epithelial T cells in SLIT- compared with placebo-treated atopics (P=0.1 for both). IgG(1) and IgG(4) were increased following SLIT (P<0.001). Peak seasonal IgA(1) and IgA(2) were increased during SLIT (P<0.05). There was a time-dependent increase in serum inhibitory activity for IgE-FAB in SLIT-treated atopics.

CONCLUSIONS

SLIT with grass pollen extract is associated with increased Foxp3(+) cells in the sublingual epithelium and systemic humoral changes as observed previously for SCIT.