Daniel Adams

Nasal allergen challenge studies of allergic rhinitis: a guide for the practicing clinician

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Lack of effect of Grastek® on birch pollen-induced allergic rhinoconjunctivitis in the Environmental Exposure Unit

BACKGROUND Timothy grass pollen allergen extract tablets (Grastek) are standardized sublingual immunotherapy tablets (SLIT-T) approved for the treatment of grass pollen-induced allergic rhinitis (AR) and conjunctivitis. Many grass allergic patients are also cosensitized to birch pollen. Whether Timothy grass SLIT-T can confer symptomatic benefits for birch pollen-induced AR symptoms is unknown. OBJECTIVE To evaluate the treatment effect of Timothy grass SLIT-T for birch pollen-induced AR in participants sensitized to both grass and birch pollen using an environmental exposure unit (EEU). METHODS This study was a phase 4, randomized, double-blind, placebo-controlled, parallel-group study that enrolled participants aged 18 to 65 years allergic to both timothy grass and birch pollen. After a baseline EEU birch pollen challenge, in which a minimum total nasal symptom score (TNSS) of 6 of 12 was required for enrollment, participants were randomized to receive Timothy grass SLIT-T or placebo taken once daily for 4 months. No confirmatory grass pollen challenge was performed. The primary end point was the change in TNSS averaged from assessments from hours 2 to 5 during the posttreatment birch pollen challenge compared with baseline. The secondary and exploratory end points included temporally identical changes in total ocular symptom score (TOSS), total rhinoconjunctivitis symptom score (TRSS), and individual symptom scores. RESULTS The difference in TNSS reduction after 4 months of therapy between the Timothy grass SLIT-T and placebo group was not significant (P = .83). Reductions in TOSS (P = .19) and TRSS (P = .67) were also comparable between groups. Findings between groups for individual symptom scores were similar (all P > .40), except for watery eyes, in which symptom reduction was slightly better in the placebo arm (P = .01). Timothy grass SLIT-T was well tolerated, and no serious adverse effects occurred. CONCLUSION A bystander effect of grass SLIT-T on birch pollen-induced AR symptoms was not detected. Symptomatic benefits of grass SLIT-T are likely allergen specific. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02394600.

Repeatability of nasal allergen challenge results – further validation of the allergic rhinitis clinical investigator collaborative (AR-CIC) protocols

BACKGROUND Nasal allergen challenge (NAC) models have been used to study allergic rhinitis and new therapies. Symptoms and biological samples can be evaluated at time points after allergen exposure. OBJECTIVE To verify protocol repeatability and adequate interval between allergen exposures. METHODS Ten ragweed allergic participants were exposed to incrementally increasing dosages of ragweed allergen intranasally until they achieved a total nasal symptom score (TNSS) of 8 of 12 and a peak nasal inspiratory flow (PNIF) of 50% reduction or more from baseline. Three weeks later, participants were challenged with a cumulative dose equal to the sum of all the allergen doses received at screening. TNSS and PNIF were recorded at regular intervals, including a 24-hour assessment. A subsequent visit was conducted after a further 3 weeks. Nasal secretion samples were collected for cytokine and eosinophil quantification. RESULTS Nine participants completed all visits. TNSS and PNIF responses followed previous patterns, with an initial peak at 30 minutes followed by a gradual decline. Most participants reported similar patterns at both NAC visits, although some did not demonstrate the same phenotype at both visits. Some experienced a secondary symptom increase 24 hours after NAC. Eosinophil and cytokine sections followed a similar pattern at both NAC visits. CONCLUSION NAC is an adequate method for modeling AR in humans, demonstrating appropriate repeatability of symptoms, nasal mucosal eosinophil, and cytokines. The 24-hour time point, previously not studied in our model, may be beneficial in evaluation of long-acting medications. This three-week interval NAC model will be beneficial for studies in which before and after treatment comparisons are desired.

Peripheral group 2 innate lymphoid cells are decreased following nasal allergen challenge in allergic rhinitis

To the Editor, Allergic rhinitis (AR) is an upper airway inflammatory disorder involving IgE‐mediated inflammation of the nasal mucosa. Inflammatory responses are triggered following inhalation of sensitized aeroallergens and are characterized by Th2 inflammation and the rapid migration of eosinophils into the nasal cavity. Group 2 innate lymphoid cells (ILC2s) represent an alternative source of Th2 cytokines, potentially augmenting pre‐existing Th2‐driven inflammation seen in AR. Lacking a specific antigen receptor and lineage surface markers for B and T cells, ILC2s are activated by IL‐25, IL‐33, and TSLP and can drive Th2 inflammation via production of IL‐5, IL‐13, and modest amounts of IL‐4. In AR patients, elevated levels of peripheral blood ILC2s were reported during the grass pollen season and following a nasal allergen challenge (NAC) with cat allergen extract. This suggests a possible role for these cells in driving allergic symptoms. However, participants from these studies may have been primed (reversible increase in reactivity of the nasal tissue) due to repeated low‐dose allergenic stimulation during pollen season or at home (ie, owning a cat). Sensitized individuals who are also primed can experience more severe allergic symptoms and changes in systemic immunity after allergen exposure. To date, few studies have assessed the effects of acute allergen exposure on circulating ILC2s in non‐primed AR individuals. Thus, the aim of the current study was to evaluate the frequency of peripheral blood ILC2s in AR individuals after a NAC performed outside of the local birch pollen season. We also evaluated ILC2 frequencies in nasal lavage (NL) samples collected pre‐ and post‐challenge. Eleven individuals with birch pollen–induced AR and eight non‐ allergics were recruited into the study (Table S1). The study was reviewed and granted ethical clearance by the Queens University and Affiliated Teaching Hospitals Research Ethics Board, and all participants provided written informed consent. All participants underwent a NAC with a pre‐titrated dose of birch pollen extract (ALK‐Abello) (Figure S1A). Total nasal symptom score (TNSS; sum of rhinorrhea, nasal congestion, sneezing, and nasal itching) and peak nasal inspiratory flow (PNIF) were recorded during the challenge. Peripheral blood and NL samples were collected at baseline and 4 hours post‐challenge. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation and cryopreserved. The 4‐hour time point was selected to remain consistent with the cat‐NAC study. Details of the NAC methodology can be found in the Methods S1 section. Thawed PBMCs and freshly obtained NL samples were stained with a fixable viability dye (PBMCs only, eBioscience), a lineage cocktail (CD3, CD14, CD16, CD19, CD20, CD56; BD Biosciences), and antibodies to CD4, CD11b, CD235a, FcεRI, CD45, CRTH2, and CD127 (all from eBioscience). ILC2s were identified as CD45 lymphocytes that were also lineage negative and expressed CRTH2 and CD127 (Figure 1A). Compared to non‐allergics, birch‐allergic participants experienced a significantly higher TNSS at 15 minutes (P < 0.0001) through 8 hours (P = 0.0048) and a larger PNIF reduction at 15 (P = 0.0016) and 30 minutes (P = 0.0004) post‐allergen challenge (Figure S1B,C). The mean frequency of peripheral blood CD45 cells remained unchanged after allergen challenge in both groups (Figure 1B). The mean frequency (±SEM) of peripheral blood ILC2s at baseline (0.019 ± 0.003% vs 0.018 ± 0.006%, P = 0.60) and post‐challenge (0.014 ± 0.002% vs 0.015 ± 0.004%, P = 0.90) was comparable between birch‐allergic and non‐allergic participants. Contrasting previous studies, peripheral blood ILC2s were significantly decreased following allergen challenge in birch‐allergic participants (P = 0.0344) (Figure 1C). This was not detected in non‐allergic participants (P = 0.25). A reduction in ILC2s was noted in this group; however, it was likely driven by one non‐allergic participant. In birch‐allergic participants, percentage changes in peripheral blood ILC2s after challenge significantly correlated with TNSS at 4 hours (r = 0.73, P = 0.01) (Figure 1D). This was not observed for 4‐ hour percentage PNIF reduction (r = −0.28, P = 0.41) (Figure 1E). In contrast, peripheral ILC2s at 4 hours alone did not correlate with 4‐ hour TNSS (r = −0.16, P = 0.63) and 4‐hour percentage PNIF reduction (r = −0.13, P = 0.70) (Figure 1F,G). A borderline correlation was observed between percentage changes in peripheral ILC2s and percentage PNIF reduction at 8 hours (late‐phase response, r = 0.61, P = 0.0491) (Table S2). Finally, correlations were not observed for 15‐minute (peak symptom severity) symptom scores (Table S2). These findings suggest that in pollen‐sensitized asymptomatic individuals, the change in peripheral ILC2s after a high‐dose pollen challenge may better reflect symptom severity compared to post‐challenge measurements alone, as observed in symptomatic individuals during pollen season. To investigate local ILC2 responses following allergen challenge, a similar gating strategy was used. We were unable to detect nasal ILC2s in NL samples collected pre‐ and post‐NAC (Figure 2A). Only a very small proportion of NL cells expressed CD45 (median frequency, 3.2%‐6.5% of all cells), which remained unchanged after allergen challenge (Figure 2B). The nasal lymphocyte population was also less defined, with 15/19 participants having less than 100 DOI: 10.1111/all.13614

An overview of the advanced data collection techniques in the environmental exposure unit (EEU)

Methods Advanced scanning technologies are used with a customized two-step quality assurance data collection process. Optical Mark Recognition (OMR) and Optical Character Recognition (OCR) capture data from paper symptom diary cards into the EEU’s clinical data management system (CDMS). A template is configured to read the static diary card format and assign zones where the specific diary card data are located. The user configures field requirements within the zones to validate data captured. Cards that do not meet a predefined confidence level for any particular zone will be flagged for a quality check. The quality checking process involves one user visually confirming all data captured and a second user inputting all values from the card to ensure accuracy. Invalid data are rejected from the batch and returned to the participant for correction. Corrected cards are scanned again and all valid data are transferred into the CDMS.