BACKGROUND:Allergic asthma (AA) and allergic rhinoconjunctivitis (ARC) are common comorbid environmentally triggered diseases. We hypothesized that severe AA/ARC reflects a maladaptive or unrestrained response to ubiquitous aeroallergens. METHODS:We performed provocation studies wherein six separate cohorts of persons (total n = 217) with ARC, with or without AA, were challenged once or more with fixed concentrations of seasonal or perennial aeroallergens in an aeroallergen challenge chamber (ACC). RESULTS:Aeroallergen challenges elicited fully or partially restrained vs. unrestrained evoked symptom responsiveness, corresponding to the resilient and adaptive vs. maladaptive AA/ARC phenotypes, respectively. The maladaptive phenotype was evoked more commonly during challenge with a non-endemic versus endemic seasonal aeroallergen. In an AA cohort, symptom responses evoked after house dust mite (HDM) challenges vs. recorded in the natural environment were more accurate and precise predictors of asthma severity and control, lung function (FEV1), and mechanistic correlates of maladaptation. Correlates included elevated levels of peripheral blood CD4+ and CD8+ T-cells, eosinophils, and T-cell activation, as well as gene expression proxies for ineffectual epithelial injury/repair responses. Evoked symptom severity after HDM challenge appeared to be more closely related to levels of CD4+ and CD8+ T-cells than eosinophils, neutrophils, or HDM-specific IgE. CONCLUSIONS:Provocation studies support the concept that resilience, adaptation, and maladaptation to environmental disease triggers calibrate AA/ARC severity. Despite the ubiquity of aeroallergens, in response to these disease triggers in controlled settings (ie, ACC), most atopic persons manifest the resilient or adaptive phenotype. Thus, ARC/AA disease progression may reflect the failure to preserve the resilient or adaptive phenotype. The triangulation of CD8+ T-cell activation, airway epithelial injury/repair processes and maladaptation in mediating AA disease severity needs more investigation.

BACKGROUND:Signifying the 2-compartments/1-disease paradigm, allergic rhinoconjunctivitis (ARC) and asthma (AA) are prevalent, comorbid conditions triggered by environmental factors (eg, house dust mites [HDMs]). However, despite the ubiquity of triggers, progression to severe ARC/AA is infrequent, suggesting either resilience or adaptation.OBJECTIVE:We sought to determine whether ARC/AA severity relates to maladaptive responses to disease triggers.METHODS:Adults with HDM-associated ARC were challenged repetitively with HDMs in an aeroallergen challenge chamber. Mechanistic traits associated with disease severity were identified.RESULTS:HDM challenges evoked maladaptive (persistently higher ARC symptoms), adaptive (progressive symptom reduction), and resilient (resistance to symptom induction) phenotypes. Symptom severity in the natural environment was an imprecise correlate of the phenotypes. Nasal airway traits, defined by low inflammation-effectual epithelial integrity, moderate inflammation-effectual epithelial integrity, and higher inflammation-ineffectual epithelial integrity, were hallmarks of the resilient, adaptive, and maladaptive evoked phenotypes, respectively. Highlighting a crosstalk mechanism, peripheral blood inflammatory tone calibrated these traits: ineffectual epithelial integrity associated with CD8+ T cells, whereas airway inflammation associated with both CD8+ T cells and eosinophils. Hallmark peripheral blood maladaptive traits were increased natural killer and CD8+ T cells, lower CD4+ mucosal-associated invariant T cells, and deficiencies along the TLR-IRF-IFN antiviral pathway. Maladaptive traits tracking HDM-associated ARC also contributed to AA risk and severity models.CONCLUSIONS:Repetitive challenges with HDMs revealed that maladaptation to disease triggers may underpin ARC/AA disease severity. A combinatorial therapeutic approach may involve reversal of loss-of-beneficial-function traits (ineffectual epithelial integrity, TLR-IRF-IFN deficiencies), mitigation of gain-of-adverse-function traits (inflammation), and blocking of a detrimental crosstalk between the peripheral blood and airway compartments.

Background: Controlled allergen challenge facilities (CACF), in disparate geographic regions with dissimilar engineering and base populations, have historically functioned as single, independent sites in clinical allergy trials. We aimed to demonstrate "between-unit reproducibility" to allow controlled challenge trials of participants using 2 CACFs. Objective: To compare and standardize 2 CACFs located in Kingston, Ontario, Canada, and San Antonio, Texas, by examining participant-reported symptom severity during qualifying and treatment visits and evaluating response to treatment, while using the same allergen. Methods: At 2 different CACFs, participants were enrolled in a double-blind, placebo-controlled, crossover intervention trial with cetirizine 10 mg. Different distribution devices delivered common short ragweed pollen via laminar air flow and maintained an airborne concentration of 3500 +/- 700 grains/m(3) in both facilities. A 1-hour "sham" run with no pollen release preceded a priming exposure of 3 hours and was followed 3 days later by a qualifying/treatment 5-hour exposure. At least 14 days later, another priming exposure was followed by the crossover exposure and treatment. Results: Forty-eight and 43 subjects completed the study at Kingston and San Antonio, respectively. Demographics were similar. Fewer than 10% exhibited symptoms with sham exposure. No significant differences were found between the 2 facilities in maximal total rhinoconjunctivitis symptom score, total nasal symptom score, and total ocular symptom score, nor in areas under the curve. In both facilities, no significant effects of cetirizine 10 mg over placebo were detected. Conclusion: The results were equivalent, demonstrating that the 2 CACFs can be used together in dual-center clinical trials and show the possibility of multicenter trials involving multiple CACFs. (C) 2019 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Controlled allergen challenge facilities(CACF), in disparate geographic regions with dissimilar engineering and base-populations, have historically functioned as single, independent sites in clinical allergy trials. Natural setting trials, involving multiple sites, introduce many uncontrolled variables. We aimed to demonstrate site equivalency, or “between-unit reproducibility” to allow controlled challenge trials of large numbers of participants, utilizing two CACFs, facilitating efficacy evaluations of novel interventions. At two different CACFs, participants were enrolled in a double-blind, placebo-controlled, crossover intervention trial with cetirizine. Different distribution devices delivered ragweed pollen at 3500 (±700) grains/m3 via laminar air flow at both sites. A series of Rotorod®s were utilized at site 1(S1) and the Allergenco cassette system at site 2(S2). A one hour “sham” run with no pollen release preceded a priming exposure of three hours followed 3 days later by a qualifying/treatment exposure of 5 hours. Another priming exposure at least 14 days later was followed in 3 days by the cross-over exposure and treatment. Forty-seven and 43 subjects completed the study at S1 and S2, respectively. Demographics were similar. Less than 10% exhibited symptoms with sham exposure. There were no significant differences between the two facilities in maximal total rhinoconjunctivitis symptom score, total nasal symptom score, and total ocular symptom score, nor in terms of the area under the curve for mean responses. Responses to cetirizine and placebo were statistically similar. Despite engineering differences between the two CACFs, there were equivalent results demonstrating that these facilities can be utilized with confidence for a single clinical trial.

Background: An emerging paradigm holds that resistance to the development of allergic diseases, including allergic rhinoconjunctivitis, relates to an intact epithelial/epidermal barrier during early childhood. Conceivably, the immunologic and genomic footprint of this resistance is preserved in nonatopic, nonallergic adults and is unmasked during exposure to an aeroallergen.Objective: The aim of this study was to obtain direct support of the epithelial/epidermal barrier model for allergic rhinoconjunctivitis.Methods: Twenty-three adults allergic to house dust mites (HDMs) (M+) and 15 nonsensitive, nonallergic (M-) participants completed 3-hour exposures to aerosolized HDM (Dermatophagoides pteronyssinus) powder on 4 consecutive days in an allergen challenge chamber. We analyzed: (1) peripheral blood leukocyte levels and immune responses; and (2) RNA sequencing-derived expression profiles of nasal cells, before and after HDM exposure.Results: On HDM challenge: (1) onlyM+ persons developed allergic rhinoconjunctivitis symptoms; and (2) peripheral blood leukocyte levels/responses and gene expression patterns in nasal cells were largely concordant between M+ and M- participants; gross differences in these parameters were not observed at baseline (pre-exposure). Two key differences were observed. First, peripheral blood CD4(+) and CD8(+) T-cell activation levels initially decreased in M- participants versus increased in M+ participants. Second, in M-compared with M+ participants, genes that promoted epidermal/epithelial barrier function (eg, filament- aggregating protein [filaggrin]) versus inflammation (eg, chemokines) and innate immunity (interferon) were upregulated versus muted, respectively.Conclusion: An imprint of resistance to HDM challenge in nonatopic, nonallergic adults was muted T-cell activation in the peripheral blood and inflammatory response in the nasal compartment, coupled with upregulation of genes that promote epidermal/epithelial cell barrier function.

BACKGROUND:There are few direct data concerning symptom dynamics of allergic conjunctivitis (AC) in an allergen challenge chamber (ACC).OBJECTIVE:To determine the AC dynamics on subsequent exposures to ragweed pollen (RW) in individuals with allergic rhinitis in an ACC. To determine whether consecutive exposures in an ACC have any persistent detrimental ocular physical effects.METHODS:Participants underwent 3 exposures to RW in an ACC. Ocular symptoms of itching and tearing were self-assessed. Ocular redness and lid swelling were assessed by trained ophthalmic technicians. Complete ophthalmic examinations (COEs) were performed by an ophthalmologist.RESULTS:A total of 188 of 201 participants (93%) developed an ocular redness score of 2 or more in each eye in ACC exposure 1. Reproducibility of redness occurred in approximately 70% of individuals completing ACC exposures 1 through 3. There were no significant changes between baseline COE and end of study COE. Phenotypes were identified by redness responses during and after exposure. Baseline total ocular symptom scores, at 24 hours after a priming exposure, were identified as late-phase reactions rather than enhanced sensitivity.CONCLUSION:When assessed by trained professionals, AC was present with a very high frequency in selected individuals allergic to RW monitored in an ACC. Intrasubject reproducibility of redness was consistent across 3 ACC allergen exposures. Phenotypes were identified as early-phase responses, protracted early-phase responses, dual responses, and late-phase responses.TRIAL REGISTRATION:clinicaltrials.gov Identifier: NCT02079649.

The proceedings of a National Institutes of Health workshop and a meeting of an Advisory Committee of the US Food and Drug Administration,1U.S. Food and Drug Administration Center for Biologics Evaluation and Research: Allergenic Products Advisory Committee, May 12, 2011. Available at: http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/BloodVaccinesandOtherBiologics/AllergenicProductsAdvisoryCommittee/UCM258587.pdf. Accessed May 28, 2014.Google Scholar, 2Togias A. Asthma, Allergy, and Inflammation Branch, Division of Allergy, Immunology and Transplantation, NIAID/NIHEnvironmental exposure units: clinical trial design for validation. National Institute for Allergy and Infectious Diseases/National Institutes of Health, Bethesda2010: 1-12Google Scholar as well as related commentaries,3Bernstein J.A. Correlation between a pollen challenge chamber and a natural allergen exposure study design for eliciting ocular and nasal symptoms: early evidence supporting a paradigm shift in drug investigation?.J Allergy Clin Immunol. 2012; 130: 128-129Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar, 4Devillier P. Le Gall M. Horak F. The allergen challenge chamber: a valuable tool for optimizing the clinical development of pollen immunotherapy.Allergy. 2011; 66: 163-169Crossref PubMed Scopus (48) Google Scholar highlight the utility of an allergen challenge chamber (ACC) for conducting clinical trials for allergic rhinoconjunctivitis (AR). Mitigation of factors that might confound the design, analysis, and interpretation of these trials requires a systematic comparison of symptoms present in the natural setting versus those elicited after exposure to aeroallergens in an ACC. In prior studies we conducted out-of-season challenges with 3 separate pollens in patients with seasonal allergy.5Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes.J Allergy Clin Immunol. 2012; 130: 122-127.e8Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar, 6Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure.J Allergy Clin Immunol. 2014; 133 (e1-7): 1340-1346Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar Although there was high correlation in symptom scores in the natural pollination seasons and ACC, competing environmental influences (eg, mold) in the natural setting blunted the responsiveness to these pollens, whereas this confounder was not present in the ACC.5Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes.J Allergy Clin Immunol. 2012; 130: 122-127.e8Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar, 6Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure.J Allergy Clin Immunol. 2014; 133 (e1-7): 1340-1346Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar However, most patients with allergy are polysensitized to outdoor (eg, pollens) and indoor (eg, house dust mite [HDM]) aeroallergens. HDM exposure is common, associated with perennial allergy, and a significant risk factor for AR and asthma. Here we compared the symptom dynamics in the natural setting versus the ACC in HDM-sensitive (M+) and nonsensitive (M−) participants meeting the inclusion/exclusion criteria shown in Table E1 in this article's Online Repository at www.jacionline.org. M− subjects lacked both a history of AR and skin prick test (SPT) wheal reactivity (≥5 mm) to 17 allergens, including HDM (see Table E2 in this article's Online Repository at www.jacionline.org). The study comprised 4 study phases: a 4-day run-in phase followed by 2 ACC exposure phases (ACC-I and ACC-II) with an intervening 38-day observation phase (Fig 1, A). This design allowed for evaluation of the reproducibility of symptom responses and factors that could potentially confound clinical trials in the ACC, including mediators of nocebo effects,7Bingel U. Avoiding nocebo effects to optimize treatment outcome.JAMA. 2014; 312: 693-694Crossref PubMed Scopus (141) Google Scholar as discussed in the Methods section in this article's Online Repository at www.jacionline.org. The study was conducted in the early fall, when only weed pollens were detected in San Antonio, Texas (Fig 1, A and B).6Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure.J Allergy Clin Immunol. 2014; 133 (e1-7): 1340-1346Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar To mitigate this confounding factor, we selected M+ participants with negative SPT responses for weed pollens (see Table E2). All participants were allergy drug free throughout the study (see Table E3 in this article's Online Repository at www.jacionline.org). Each ACC phase comprised exposure for 3 hours on 4 consecutive days to a purified mite body powder of Dermatophagoides pteronyssinus (Fig 1, A and B, and see the Methods section in this article's Online Repository). The end point we targeted was an increase in instantaneous total symptom scores (iTSSs) of at least 6 units in 50% of participants from baseline levels. To achieve this goal, the ACC was calibrated to deliver 70 to 110 ng/m3 HDM Der p 1 antigen, as measured by means of ELISA (see Table E4 and the Methods section in this article's Online Repository at www.jacionline.org). iTSSs in the ACC and reflective total symptom scores (rTSSs) in the natural setting were recorded by using a 5-point Likert scale (see Table E5 in this article's Online Repository at www.jacionline.org). Of the 40 participants meeting inclusion criteria, 35 (21 M+ and 14 M− participants) completed all 4 study phases, and of these, 13 M+ participants and 1 M− participant had detectable (≥0.35 kU/L) serum specific IgE (ssIgE) to D pteronyssinus. This dichotomy between SPT reactivity but undetectable ssIgE has been reported for many allergens (see the Discussion section in this article's Online Repository at www.jacionline.org).8de Vos G. Skin testing versus serum-specific IgE testing: which is better for diagnosing aeroallergen sensitization and predicting clinical allergy?.Curr Allergy Asthma Rep. 2014; 14: 430Crossref PubMed Scopus (50) Google Scholar There were no differences in the key demographic characteristics between M+ and M− participants (see Table E6 in this article's Online Repository at www.jacionline.org). Five participants withdrew from the study for nonmedical reasons. M− participants had minimal symptoms in the ACC (mean iTSS, <1; Fig 1, B). In contrast, M+ participants experienced a mean increase of 3 units in the iTSS within 30 minutes of HDM challenge, and iTSSs reached a plateau after approximately 120 minutes (Fig 1, B). There was a high degree of concordance in symptom responses in M+ participants in the ACC recorded by using the Likert and visual analog scales (see Fig E1 in this article's Online Repository at www.jacionline.org). Eleven episodes of bronchospasm occurred in 5 M+ participants, a rate consistent with prior findings.9Horak F. Toth J. Marks B. Stubner U.P. Berger U.E. Jager S. et al.Efficacy and safety relative to placebo of an oral formulation of cetirizine and sustained-release pseudoephedrine in the management of nasal congestion.Allergy. 1998; 53: 849-856Crossref PubMed Scopus (43) Google Scholar These participants exhibited slightly higher total symptom scores (TSSs; see Fig E2 in this article's Online Repository at www.jacionline.org), had greater than 15% improvement in FEV1.0 after treatment with nebulized albuterol, and returned to the ACC without additional exacerbations (see the Discussion section in this article's Online Repository). These findings suggest that M+ participants with mild intermittent asthma can be safely evaluated within ACCs. The concordance in symptom responses during and between ACC-I and ACC-II was high (Fig 1, C, and see Table E7 in this article's Online Repository at www.jacionline.org). In contrast, the correlations between rTSSs recorded in the run-in versus observation phases or between rTSSs versus iTSSs were much lower (see Fig E3 in this article's Online Repository at www.jacionline.org). During ACC-I and ACC-II, an increase in iTSSs of 6 or greater from baseline (pre-exposure) was experienced in greater than 55% of participants (Fig 1, D). While less than 10% of participants had iTSSs of 15 or greater at baseline, 67% and 57% of M+ participants achieved iTSSs of 15 or greater in ACC-I and ACC-II, respectively (Fig 1, E). Substantial data indicate that ssIgE levels to allergens might serve as biomarkers for symptom severity.10Ciprandi G. Tosca M.A. Silvestri M. The practical role of serum allergen-specific IgE as potential biomarker for predicting responder to allergen immunotherapy.Expert Rev Clin Immunol. 2014; 10: 321-324Crossref PubMed Scopus (11) Google Scholar Accordingly, TSSs were greater in M+ participants with a detectable ssIgE level for D pteronyssinus in the ACC (Fig 2, A and B). The failure to detect such an association in the natural setting (Fig 2, A and B) might relate to variable HDM levels measured in dust from mattresses in the participants' homes (see Fig E4 and the Methods section in this article's Online Repository at www.jacionline.org). Pollen SPT reactivity (P+) stratified TSSs, with M+P+ participants having higher rTSSs and iTSSs when compared with those of M+P− participants (Fig 2, C). Levels of T-cell activation were greater in M+P+ participants compared with those seen in M+P− participants before and during ACCs (Fig 2, D, and see Fig E5 and the Methods section in this article's Online Repository at www.jacionline.org). Notably, T-cell activation has been associated with symptom responses during allergy.11Majori M. Piccoli M.L. Melej R. Pileggi V. Pesci A. Lymphocyte activation markers in peripheral blood before and after natural exposure to allergen in asthmatic patients.Respiration. 1997; 64: 45-49Crossref PubMed Scopus (7) Google Scholar Thus exposure to pollens in the months preceding the ACC exposures might have rendered M+P+ participants constitutively "primed," serving as a basis for the higher T-cell activation and symptoms in the natural and ACC settings (Fig 2, C and D). In the ACC phases the effects of pollen sensitization and ssIgE status were additive, with M+IgE+P+ participants manifesting maximal responsiveness after HDM exposure (Fig 2, E). The trigger for the constitutive priming could be winter and spring tree pollens because all M+P+ participants were reactive based on SPT reactivity to tree pollens (see Table E2). Moreover, the extended tree pollination season, which terminated a few months before the start of the ACC exposures, is typically associated with intense symptoms.6Jacobs R.L. Harper N. He W. Andrews C.P. Rather C.G. Ramirez D.A. et al.Effect of confounding cofactors on responses to pollens during natural season versus pollen challenge chamber exposure.J Allergy Clin Immunol. 2014; 133 (e1-7): 1340-1346Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar At the 2 transition points from the natural settings to the ACC (run-in → ACC-I and observation phase → ACC-II), there was a decrease in TSSs (Fig 1, Fig 2, A). This decrease was greater in those with more symptoms (ie, higher in M+P+ participants than in M+P− participants [Fig 2, F] and higher in M+IgE+ participants than in M+IgE− participants [data not shown]). This decrease might relate to (1) differences in how TSSs were recorded in the natural versus ACC settings (reflective vs instantaneous scoring, respectively); (2) learned responses secondary to increased emphasis/education by research staff in the ACC on how to accurately record TSSs; and (3) the controlled environment in the ACC (see the Discussion in this article's Online Repository). Inspection of the overall TSS trajectory indicated that after initiation of ACC exposures, there was a downward shift in the TSS (Fig 1, B). The baseline (pre-ACC) iTSS recorded before commencing challenge 1 was higher than the baseline iTSS recorded before challenges 2 and 3, and the baseline iTSS before challenges 4 through 8 were similar (Fig 1, B). Furthermore, the rTSS in the observation phase was lower than the rTSS in the run-in phase (Fig 1, B). This downward shift in baseline iTSS would give the mistaken impression that responsiveness was greater in challenges 2 and 3 and lower thereafter, when in fact the responsiveness in exposures 1 and 4 through 8 was similar (Fig 2, G). These downward shifts in TSSs did not differ by pollen SPT or ssIgE status (data not shown), and we surmise this might relate to a combination of factors: learned responses (secondary to education in the ACC) and partial clinical tolerance akin to what has been observed after repetitive exposure to allergens, including HDM (see the Discussion section in this article's Online Repository).12Woodfolk J.A. High-dose allergen exposure leads to tolerance.Clin Rev Allergy Immunol. 2005; 28: 43-58Crossref PubMed Google Scholar, 13Liu L.Y. Swenson C.A. Kelly E.A. Kita H. Jarjour N.N. Busse W.W. Comparison of the effects of repetitive low-dose and single-dose antigen challenge on airway inflammation.J Allergy Clin Immunol. 2003; 111: 818-825Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar In this study exposure to HDM concentrations used in the ACC was associated with reliable and reproducible elicitation of symptoms. SPT reactivity to pollen, which was associated with increased inflammatory status, and ssIgE levels to HDM were biological markers that correlated with symptom responses in the ACC. These 2 biomarkers stratified M+ participants as higher versus lower responders in the ACC, whereas this stratification is obscured in the natural settings. Therefore we suggest that out-of-pollination season challenges with HDM in the ACC might help mitigate the confounding of factors present in the natural setting: variable or low exposure to HDM, lack of association of ssIgE levels with rTSSs, and effects of competing environmental influences in a primed polysensitized subject. We also suggest that the other factors that could potentially confound clinical trials in an ACC (and natural setting) are nocebo7Bingel U. Avoiding nocebo effects to optimize treatment outcome.JAMA. 2014; 312: 693-694Crossref PubMed Scopus (141) Google Scholar and placebo14Enck P. Bingel U. Schedlowski M. Rief W. The placebo response in medicine: minimize, maximize or personalize?.Nat Rev Drug Discov. 2013; 12: 191-204Crossref PubMed Scopus (476) Google Scholar effects (expectations, learning process, and participant-physician communication). Confounding could occur by (1) misattribution of positive therapy effects to decrease symptom scores related to more precise symptom scoring (because of learned behavior) and/or partial clinical tolerance (because of repetitive exposure) and (2) imbalance in the proportion of high versus low responders in the treatment versus placebo arms. An example that highlights the potential for this imbalance is the observation that the effectiveness of anti-IgE therapy for asthma differed by the overall sensitization status of the trial participants.15Busse W.W. Morgan W.J. Gergen P.J. Mitchell H.E. Gern J.E. Liu A.H. et al.Randomized trial of omalizumab (anti-IgE) for asthma in inner-city children.N Engl J Med. 2011; 364: 1005-1015Crossref PubMed Scopus (732) Google Scholar Therapies might be more effective in patients with greater responsiveness to allergen exposure, a trait that can be readily identified in an ACC. Thus we surmise that mindfulness of the abovementioned confounders and use of an ACC might together facilitate detection of differences in the effects of placebo versus therapy in clinical trials, especially in exploratory studies with novel therapeutic agents when both the participant numbers and therapy effect sizes might be modest. Download .docx (.23 MB) Help with docx files Online Repository Data Download .pdf (.39 MB) Help with pdf files Fig E1 Download .pdf (.16 MB) Help with pdf files Fig E2 Download .pdf (.4 MB) Help with pdf files Fig E3 Download .pdf (.37 MB) Help with pdf files Fig E4 Download .pdf (.68 MB) Help with pdf files Fig E5

BACKGROUND:Modifiers of symptom severity in patients with allergic rhinoconjunctivitis (AR) are imprecisely characterized. The hygiene hypothesis implicates childhood microbial exposure as a protective factor. Cockroach sensitization (C+) might be a proxy for microbial exposure. OBJECTIVE:We sought to determine whether C+ assayed by means of skin prick tests influenced AR symptom severity in controlled and natural settings. METHODS:Total symptom scores (TSSs) were recorded by 21 participants with house dust mite allergy (M+) in the natural setting and during repeated exposures of 3 hours per day to house dust mite allergen in an allergen challenge chamber (ACC). In M+ participants the peripheral blood and nasal cells were assayed for T-cell activation and transcriptomic profiles (by using RNA sequencing), respectively. Participants allergic to mountain cedar (n = 21), oak (n = 34), and ragweed (n = 23) recorded TSSs during separate out-of-season exposures to these pollens (any pollen sensitization [P+]) in the ACC; a subset recorded TSSs in the pollination seasons. RESULTS:The hierarchy of TSSs (highest to lowest) among M+ participants tracked the following skin prick test sensitization statuses: M+P+C- > M+P+C+ > M+P-C- > M+P-C+. In nasal cells and peripheral blood the immune/inflammatory responses were rapidly resolved in M+P+C+ compared with M+P+C- participants. Among those allergic to pollen, C+ was associated with a lower TSS during pollen challenges and the pollination season. After aggregated analysis of all 4 ACC studies, C+ status was associated with a 2.8-fold greater likelihood of a lower TSS compared with C- status (odds ratio, 2.78; 95% CI, 1.18-6.67; P = .02). CONCLUSIONS:C+ status is associated with mitigation of AR symptom severity in adults with AR.

Background: The responsiveness to a nonendemic grass species is unknown and cannot be research without an allergen challenge chamber.Objective: To determine the clinical responsiveness to timothy grass pollen (TGP) in participants without known natural exposure in an allergen challenge chamber (ACC).Methods: Of the 26 screened participants, 22 met screening criteria and completed the 2 chamber exposures. The study consisted of an initial screening visit that included a blood draw for serum specific IgE (ssIGE) to Bermuda grass pollen and TGP followed by a 41/2-day run-in phase and two 3-hour ACC exposure visits. This study was performed early in the first week of December 2013, when no seasonal pollens were detected in San Antonio, Texas. Symptom scores were recorded at baseline and every 30 minutes.Results: Of the 26 screened participants, 22 met the screening criteria and completed the 2 chamber exposures. Thirteen participants had always lived in South Texas without natural exposure, and 9 had previously lived in areas with TGP exposure. All participants tested positive to TGP and Bermuda grass pollen. Twelve and 13 of 22 had positive ssIgE test results to Timothy and Bermuda allergens, respectively, with 11 having positive results for both allergens. There were strong correlations among skin prick test size, a positive ssIgE test result, and high symptoms from TGP exposure. There was little difference in symptoms between those who had lived their entire lives in South Texas and those who had lived elsewhere.Conclusion: In Texas, where exposure to TGP is minimal, strongly positive SPT and ssIgE test results were predictors of high symptoms to TGP exposure. Never exposed participants in South Texas reacted to TGP similar to those who had previous natural exposure, suggesting that in vivo cross-reactivity may be higher than predicted by prior in vitro data and may allow the use in clinical trials of allergens not endemic to the locale of an ACC. (C) 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Background: The severity of allergic rhinoconjunctivitis (AR) symptomatology elicited after exposure to pollen in the absence versus the presence of confounding cofactors, such as in a pollen challenge chamber (PCC) and the natural pollinating season, respectively, might differ.Objective: We sought to determine the correlation of AR severity in the natural season versus out-of-season PCC exposures.Methods: Twenty-four Virginia live oak (VLO)-positive, 14 VLO-negative, 16 mountain cedar (MC) 2 positive, 8 MCnegative, and 26 ragweed-positive participants recorded AR symptoms (total symptom score [TSS]) during the VLO, MC, and ragweed pollinating seasons and during 2 consecutive PCC exposures of 3 hours each to these pollens separately.Results: The TSSs recorded before the natural season were higher than the pre-PCC values. This prepriming was greater among VLO 1 than MC 1 participants, and it blunted further increases in TSSs during the VLO natural season. Nonatopic participants were nonreactive in the PCC. There was wide variation in the level of AR symptomatology after exposure to VLO, MC, or ragweed pollen in the PCC. Prepriming formed the basis for higher AR responses observed in the natural season than in the PCC, resulting in the identification of distinct PCC/natural season endophenotypes and a partial correlation between the TSSs recorded in the natural season versus those recorded in the PCC (r = 5 0.34, 0.54, and 0.65 for VLO+, MC+, and ragweed-positive participants, respectively).Conclusions: Prepriming in the natural pollinating season might obscure the true correlation between AR severity in the natural season versus the PCC. By mitigating confounding cofactors, PCC exposures have utility for evaluation of novel AR therapeutics.

Background The level of concordance between allergic symptoms induced on exposure to pollen in a pollen challenge chamber (PCC) versus the natural season is unknown. Objective We sought to test the hypothesis that the symptom levels of allergic rhinoconjunctivitis elicited after out-of-season exposure to short ragweed in a PCC and during the natural season for giant ragweed pollen are highly correlated. Methods Thirty-one ragweed-sensitive participants recorded symptoms for 15 days during the natural giant ragweed season in San Antonio, Texas. Twenty-six of these participants were challenged to short ragweed pollen in a PCC for 3 hours per day for up to 4 days. Results In the PCC participants were dichotomized into those in whom low versus high levels of symptoms developed slowly or rapidly (ie, slow/low vs rapid/high). Each successive exposure visit associated with a progressive increase in symptom levels that approximated those experienced during the natural season. Hierarchic clustering identified 3 endotypes: endotypes I and II reflected concordantly low (n = 7) versus high (n = 14) total symptom scores (TSSs) in both the natural season and the PCC, respectively. Accordingly, the correlation between the TSSs recorded in the natural season and in the PCC for these 21 participants was very high. Although participants with endotype III (n = 5) had greater TSSs in the natural season than in the PCC, the degree of correlation between the TSSs remained high. Conclusions Our findings affirm our hypothesis, underscore the high cross-reactivity between distinct pollens, and highlight the utility of the PCC to identify novel allergy endotypes that might have contrasting mechanistic underpinnings and potentially therapeutic responses.

Background: Pollen challenge chambers have been used to evaluate medication in allergic rhinoconjunctivitis under controlled conditions.Objective: To validate a facility for the study of subjects' responses to inhalational challenges with Juniperus ashei (mountain cedar) pollen.Methods: Two chambers, 307 m(3) and 188 m(3), seating 50 and 25 individuals, respectively, were constructed with clean room materials. The computer-controlled air handler used powered diffusers and exhausts to maintain a laminar flow. Pollen was delivered by a feeder into a vortex created by an eductor through a series of stainless steel tubes. Nonprimed mountain cedar sensitive and healthy control subjects were exposed to a masked sham air run and increasing increments of pollen during a 5-hour period outside the natural season. These individuals were then exposed for 2-hour periods for up to 4 sequential days at fixed pollen counts to demonstrate effects of priming.Results: Airflow from diffusers and exhausts maintained 12 exchange cycles per hour. Pollen counts ranged from 1,300 to 12,000 grains/m(3). None of the subjects responded during the masked sham run. Healthy controls did not respond. Nonprimed subjects had an inadequate response. Primed subjects responded symptomatically within a period adequate for entry into studies. There were no serious adverse responses.Conclusions: The chambers functioned within the parameters for which they were designed. Subjects did not respond to a sham run. Priming runs were required to stimulate symptoms at levels in a timeframe sufficient for pharmacologic studies. Pollen counts 3 to 4 times the average seasonal counts were required to elicit significant symptoms. Ann Allergy Asthma Immunol. 2011;107:133-138.

Though not widely recognized, food hypersensitivity by inhalation can cause major morbidity in affected individuals. The exposure is usually more obvious and often substantial in occupational environments but frequently occurs in non-occupational settings, such as homes, schools, restaurants, grocery stores, and commercial flights. The exposure can be trivial, as in mere smelling or being in the vicinity of the food. The clinical manifestations can vary from a benign respiratory or cutaneous reaction to a systemic one that can be life-threatening. In addition to strict avoidance, such highly-sensitive subjects should carry self-injectable epinephrine and wear MedicAlert® identification. Asthma is a strong predisposing factor and should be well-controlled. It is of great significance that food inhalation can cause de novo sensitization.