Wildfires have surged in frequency and severity, and in 2022, they contributed to nearly 30% of the fine inhalable particulate matter (PM2.5) in the United States. Health effects from wildfire-induced wood smoke (WS) exposure include worsened pre-existing lung diseases and lung function, increased emergency room visits, and increased risk of premature death. Evidence suggests that males and females have unique responses to air pollutants, but sex-specific responses to WS remain understudied. To evaluate whether males and females differentially respond to WS, we analyzed induced sputum samples in humans following a controlled chamber exposure to WS. A total of 79 participants were exposed to 500 µg/m3 of WS for 2 h with intermittent exercise, and a subset of participants' samples were analyzed for cellularity and cytokine concentrations, and protein expression in the sputum supernatants. Cell differentials were compared between pre-, 6 h, and 24 h post-exposure, and proteomic and cytokine signatures were compared between pre- and 24 h post-exposure. A total of 368 proteins were significantly different in females, and 27 were significantly different in males post-exposure. Pathway analysis revealed inhibition of leukocyte extravasation signaling, phagosome formation, and macrophage nitric oxide and reactive oxygen species pathways in females versus males. Females had a lower percentage of iNOS+ and a higher percentage of CD301+ sputum macrophages versus males. Overall, this exploratory analysis suggests that in response to acute WS exposure, different pathways are affected in females compared with males. Future studies are needed to determine whether this confers an immune advantage and to understand the mechanisms of sex-specific WS-induced respiratory effects.

Controlled human exposure studies have provided strong evidence of decremental effects of ozone exposure in healthy adults. However, there have been few controlled exposure studies conducted at the level of the National Ambient Air Quality Standard (NAAQS). In this study, 38 healthy adults (19-34 yr) were exposed to clean air (CA) and 0.07 ppm ozone for 6.6 h with intermittent moderate exercise. Exposures were randomized and double-blind. Pulmonary function was measured immediately before and after exposure to CA and 0.07 ppm ozone. The percent polymorphonuclear neutrophils (%PMNs) in sputum were quantified in 14 participants approximately 16-18 h post-exposure. Respiratory and non-respiratory symptoms were assessed before and after each exposure, and at each 10-min break during exposure sessions. We report mean (±SEM) decrements in FEV1 immediately after exposure to 0.07 ppm ozone relative to CA (-1.24 ± 0.92% vs. 0.83 ± 0.50%; p = 0.017). Additionally, the mean decrement in FVC was greater after ozone relative to CA (-1.22 ± 0.29% vs. -0.44 ± 0.40%; p = 0.148). The mean (±SEM) %PMNs in sputum was greater after ozone relative to CA (33.4 ± 6.9% vs.18.6 ± 5.6%; p = 0.013) and respiratory symptoms were significantly elevated during hours 5.6 and 6.6 of the ozone exposure, relative to CA. In summary, this study demonstrates a loss of pulmonary function and an inflammatory response among healthy subjects exposed to ozone at the current NAAQS level of 0.07 ppm.

BACKGROUND:The National Institutes of Health initiated the Precision Medicine in Severe and/or Exacerbation Prone Asthma (PrecISE) program with the objective of implementing adaptive design strategies to test multiple new treatments in biomarker-identified patient subsets. OBJECTIVE:The PrecISE study sought to recruit a cohort of patients with severe asthma for a biomarker-stratified adaptive trial of 5 different interventions. METHODS:Patients aged 12 years and older with a clinical diagnosis of asthma who were adhering to a stable medical regimen consisting of at least medium-dose inhaled corticosteroids and a second controller were enrolled if their diagnosis could be confirmed by bronchodilator responsiveness on spirometry or airway hyperreactivity to methacholine. Protocol adaptations over the course of the study to biomarker sampling and enrichment, interventions studied, the statistical analysis plan, and sample size are described. The baseline characteristics of the cohort were analyzed. RESULTS:A total of 358 participants were randomized. The 4 predictive biomarkers used for intervention randomization assignments were blood eosinophil count (median = 180; interquartile range (IQR) = 100-290 cells/mL), fractional exhaled nitric oxide measurement (median = 18; IQR = 11-27 ppb); plasma IL-6 level (median = 2.5; IQR = 1.6-3.6 pg/mL), and ADH5 risk genotype (present in 253 participants [71%]). Blood eosinophil counts weakly correlated with fractional exhaled nitric oxide measures (Rs = 0.13; P = .02) and IL-6 levels (Rs = 0.17; P = .002); otherwise, these biomarkers were independent from each other. Specific intervention results will be reported separately. CONCLUSION:The PrecISE adaptive study design with multiperiod crossovers is an efficient and novel way to study multiple interventions simultaneously in a heterogeneous disease such as asthma.

Rationale: Wood smoke exposure is increasing worldwide because of the increase in wildfire events. Various studies have associated exposure to wildfire-derived smoke with adverse respiratory conditions. However, the mechanism by which this occurs is unknown. Previous studies using wood smoke as a model of wildfire smoke have focused on the respiratory immune response and have reported increased neutrophil percentage and cytokine production in airway samples. The effect of wood smoke on the respiratory microbiome, however, has not been examined. Objectives: The objective of this study was to evaluate whether inhaled wood smoke exposure can alter the respiratory microbiome in humans. Methods: Healthy volunteers (N = 54) were subjected to controlled wood smoke exposure (500 μg/m3) for 2 hours, and induced sputum samples were collected and processed for microbiome analysis, immune mediators, and cell differentials at baseline and at 6 hours and 24 hours after exposure. A negative binomial mixed model analysis examined associations between microbiome components and inflammatory cells in sputum. Measurements and Main Results: After wood smoke exposure, although sputum microbiome diversity remained unchanged, the microbiome composition was altered, particularly the abundance of several low-abundance bacteria, including Fretibacterium and Selenomonas, indicating that this inhalational exposure can alter the composition of the sputum microbiome. In addition, a significant decrease in macrophage cells was observed at 24 hours without a significant change in neutrophils. We further found small but significant associations between different taxa and macrophages (per milligram of sputum), including a negative association with Fretibacterium. Conclusions: Together, these findings demonstrate that inhalational wood smoke exposure can modify several low-abundance bacteria within the respiratory microbiome and that these changes are associated with sputum inflammatory cell alterations, providing insights for future studies to focus on respiratory innate immune host-microbiome crosstalk in the context of environmental exposures.

Rationale: Epidemiologic studies on patients with asthma and in vitro data suggest a protective role of type 2 (T2) inflammation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Objectives: Using a large, multisite cohort, we studied clinical outcomes after SARS-CoV-2 infection in multiple asthma endotypes and examined the effects of T2-directed biologics in infected patients with asthma. Methods: The National COVID Cohort Collaborative Data Enclave was used to identify and stratify patients with asthma by endotype to include those with non-T2 and T2 asthma, as well as exposure to T2-directed biologic therapy. We evaluated the risk of hospitalization, invasive mechanical ventilation, and 90-day mortality by endotype and exposure to biologics. Results: For this study, 402,376 patients met the inclusion criteria, of whom 138,142 (34%) were characterized as having non-T2 asthma and 264,234 (66%) as having T2 asthma, a group further divided into 104,823 (26%) atopic, 84,440 (21%) eosinophilic, and 74,971 (19%) T2-high asthmatic endotypes. Compared with patients with non-T2 asthma, those with atopic and T2-high asthma experienced decreased odds of hospitalization and 90-day mortality. Conversely, patients with eosinophilic asthma experienced higher odds of hospitalization, intubation, and 90-day mortality. Exposure to T2-directed biologic therapies did not alter outcomes after propensity score matching. In contrast, maximum eosinophil count and recent systemic corticosteroid use were directly correlated with increased odds of all outcomes. Conclusions: Coronavirus disease (COVID-19) outcomes differ depending on asthma endotype, with patients with atopic asthma experiencing lower odds and those with eosinophilic asthma experiencing higher odds of deleterious outcomes. T2-directed biologic treatment did not alter these outcomes, but recent systemic corticosteroid use predisposes all patients with asthma to adverse outcomes.

Background: Data on severity of food allergy across nations are lacking. Building on the World Allergy Organization (WAO) DEFASE (Definition of Food Allergy Severity) score, we aim to explore its global applicability as a grading system for IgE-mediated food allergy (FA) severity. Methods: An international survey (WAO FASE Project) was conducted using an online questionnaire distributed to WAO members. The survey collected detailed data on diagnostic practices, therapeutic options, characteristics of FA patients, severity of reactions (including anaphylaxis), and eliciting doses of allergenic foods. In addition, FA management costs were examined (medical expenses, medication costs, and impact on quality of life and productivity). Results: We obtained information from 157 centers in 50 countries. FA management varied significantly across regions. Oral immunotherapy and omalizumab are widely used in Europe and North America. The use of advanced diagnostic tests (molecular diagnostics) vary widely between these regions. Thirty-five percent of patients with anaphylaxis exhibited severe symptoms (respiratory or cardiovascular compromise), with marked regional differences: more frequent in Western Asia (55.83%), Southern Africa (50%), and less frequent in South-Eastern Asia (12.5%) and Central America (21.72%). Approximately 1 in 4 patients reacted to less than half an age-appropriate portion of the allergenic food. Depending on the region, peanut, milk, egg, wheat, hazelnut, and peach allergies varied considerably. Economic resources and healthcare systems play an important role in determining access to diagnostic tests and therapeutic options, which have a direct impact on the severity and management of FA. Conclusions: With wide global disparities in access to diagnostic and therapeutic tools for food allergies, this condition entails a vast healthcare and economic commitment. The percentage of patients receiving a high severity diagnosis using DEFASE could be around 3%, similar to that of asthma patients diagnosed with severe refractory asthma.

The twenty-first century has seen a fundamental shift in disease epidemiology with anthropogenic environmental change emerging as the likely dominant factor affecting the distribution and severity of current and future human disease. This is especially true of allergic diseases and asthma with their intimate relationship with the natural environment. Climate change-related variables including increased ambient temperature, heat waves, extreme weather events, air pollution, and rainfall distribution, all can directly affect asthma in children, but each of these variables also indirectly affects asthma via alterations in pollen production and release, outdoor allergen exposure or the microbiome. Air pollution, with its many and varied respiratory consequences, is likely to have the greatest effect, as it has increased globally due to rapid increases in fossil fuel combustion, global population, crowding, and megacities, as well as forest burning and trees succumbing to an increasingly hostile environment. Human activities have also caused substantial deterioration of the global microbiome with reductions in biodiversity for molds, bacteria, and viruses. Reduced microbiome diversity has, in turn, been associated with increases in Th2 allergic responses and allergic disease. The collective effect of these changes has already shifted allergy and asthma disease patterns. Given that changes in climate have been relatively small to date, the unavoidable, much greater shifts in climate in the future are concerning. Determining the relative scale of the direct versus indirect effects of climate change variables is needed if effective avoidance and adaptive measures are to be implemented. This would also require much more basic, epidemiological, and clinical research to understand the causal mechanisms, the most relevant climate factors involved, the regions most affected and, most importantly, effective and actionable adaptation measures. We suggest that allergy and respiratory health workers should follow current guidance to reduce present risks related to climate change and watch for new recommendations to reduce future risks. Since the respiratory system is the one most affected by climate change, they also need to call for more research in this area and show strong leadership in advocating for urgent action to protect children by reducing or reversing factors that have led to our deteriorating climate.

Objective: The gram-negative bacterial cell wall component endotoxin (lipopolysaccharide, LPS) is a key component of particulate matter (PM). PM exposure is associated with cardiovascular morbidity and mortality. However, the contribution of individual components of PM to acute and chronic cardiovascular measures is not clear. This study examines whether systemic inflammation induced by LPS inhalation causes acute changes in cardiovascular physiology measures. Materials and Methods: In this double blinded, placebo-controlled crossover study, fifteen adult volunteers underwent inhalation exposure to 20,000 EU Clinical Center Reference Endotoxin (CCRE). Peripheral blood and induced sputum neutrophils were obtained at baseline and six hours post-exposure. Blood pressure, measures of left ventricular function (ejection fraction (LVEF) and global longitudinal strain (LVGLS)), and indices of endothelial function (flow mediated dilation (FMD) and velocity time integral during hyperemia (VTIhyp)) were measured before and after treatment. Wilcoxon sign-rank tests and linear mixed models were used for statistical analysis. Results: In comparison with normal saline, LPS inhalation resulted in significant increases in peripheral blood and sputum neutrophils but was not associated with significant alterations in blood pressure, LVGLS, LVEF, FMD, or VTIhyp. Discussion and Conclusions: In healthy adults, systemic inflammation after LPS inhalation was not associated with acute changes in cardiovascular physiology. Larger studies are needed to investigate the effects of other PM components on inflammation induced cardiovascular dysfunction.

Background Inhalation of biomass smoke is associated with adverse respiratory effects in those with chronic pulmonary conditions. There are few published data regarding the effects of anti-inflammatory interventions on these outcomes. Objective Our aim was to assess the effects of postexposure prednisone on woodsmoke (WS)-induced sputum neutrophilia. Methods We carried out a randomized, placebo-controlled, crossover pilot study assessing the effect of a postexposure dose of 60 mg prednisone on induced sputum inflammation after controlled exposure to WS (500 μg/m3 for 2 hours) in healthy adults who had been identified in a separate screening protocol as being “PMN responsive” to WS. Secondary end points were sputum cytokine level and mucociliary clearance as measured by γ-scintigraphy. Results A total of 11 subjects yielded complete data for the primary analysis. At 24 hours after WS exposure, there was a significant increase in sputum percentage of PMNs (%PMN) versus at baseline after placebo (median = 42% [IQR = 31%-53%]) (P = .02) but not after prednisone (median = 32% [IQR = 18%-40%]) (P = .09). Prednisone reduced Δ%PMN at 24 hours, but this difference did not reach statistical significance. However, for the 8 of 11 subjects who were PMN responsive after placebo, prednisone reduced Δ%PMN significantly (P = .05). Prednisone had no significant effects on sputum levels of IL-1β, IL-6, IL-8, or TNF-α. WS exposure tended to reduce mucociliary clearance in the placebo arm but not in the prednisone arm. Conclusions Prednisone taken immediately after exposure to WS mitigated short-term increase in sputum %PMN among healthy volunteers selected for their underlying inflammatory responsiveness to WS. Our data support future studies assessing anti-inflammatory interventions and the role of mucus clearance in WS-induced respiratory health effects.

Air pollution is a risk factor for asthma and respiratory infection. Avoidance of air pollution is the best approach to mitigating the impacts of pollution. Personal preventive strategies are possible, but policy interventions are the most effective ways to prevent pollution and its effect on asthma and respiratory infection.

Background: Air pollutants, including particulates from wood smoke, are a significant cause of exacerbation of lung disease. y-Tocopherol is an anti-inflammatory isoform of vitamin E that has been shown to reduce allergen-, ozone-, and endotoxininduced inflammation. Objective: The objective of this study was to determine whether y-tocopherol would prevent experimental wood smoke-induced airway inflammation in humans. Methods: This was a randomized, placebo-controlled clinical trial testing the effect of a short course of y-tocopherol- enriched supplementation on airway inflammation following a controlled exposure to wood smoke particulates. Results: Short-course y-tocopherol intervention did not reduce wood smoke-induced neutrophilic airway inflammation, but it did prevent wood smoke-induced eosinophilic airway inflammation. Conclusion: y-Tocopherol is a potential intervention for exacerbation of allergic airway inflammation, but further study examining longer dosing periods is required. (J Allergy Clin

Background: Thymic stromal lymphopoietin (TSLP) has been shown to play a central role in the initiation and persistence of allergic responses.Objective: We evaluated whether tezepelumab, a human monoclonal anti-TSLP antibody, improved the efficacy of subcutaneous allergen immunotherapy (SCIT) and promoted the development of tolerance in patients with allergic rhinitis.Methods: We conducted a double-blind parallel design trial in patients with cat allergy. A total of 121 patients were randomized to receive either intravenous tezepelumab plus subcutaneous cat SCIT, cat SCIT alone, tezepelumab alone, or placebo for 52 weeks, followed by 52 weeks of observation. Nasal allergen challenge (NAC), skin testing, and blood and nasal samples were obtained throughout the study.Results: At week 52, the NAC-induced total nasal symptom scores (TNSS) (calculated as area under the curve [AUC0-1h] and as peak score [Peak0-1h] during the first hour after NAC) were significantly reduced in patients receiving tezepelumab/SCIT compared to SCIT alone. At week 104, one year after stopping treatment, the primary end point TNSS AUC0-1h was not significantly different in the tezepelumab/SCIT group compared to SCIT alone, while TNSS Peak0-1h was significantly lower in those receiving combination treatment versus SCIT. Transcriptomic analysis of nasal epithelial samples demonstrated that treatment with the combination of SCIT/tezepelumab, but neither monotherapy, caused persistent downregulation of a gene network related to type 2 inflammation that was associated with improvement in NAC responses.Conclusions: Inhibition of TSLP augments the efficacy of SCIT during therapy and may promote tolerance after a 1-year course of treatment. (ClinicalTrials.gov NCT02237196). (J Allergy Clin Immunol 2023;151:192-201.)

The launch of JACI: Global is an exciting time for the AAAAI and the allergy/immunology (A/I) community. Academy leadership felt very strongly that a true “Gold Open Access” journal would be an important expansion of the family of journals the AAAAI offers. There were a number of reasons it was felt JACI: Global needed to be developed. First, JACI and JACI: In Practice have achieved tremendous success. However, their focus has been to communicate well-developed translational research or clinical advances that can be immediately employed by our practitioners. The success of our A/I research community has resulted in so much publishable research that it can be frustratingly difficult for investigators who report formative and developmental studies to be prioritized by JACI and JACI: In Practice. These early studies are often the building blocks upon which well-developed studies are built. Additionally, the focus on translational studies resulted in even more competition for publication in AAAAI journals by those focused on basic science and animal model studies. One important goal for JACI: Global is to provide a publication opportunity for early-stage and bench research. We will also welcome informative case reports, systemic and narrative reviews, and are eager to publish articles across the expanse of A/I research. In essence, to be “Global” with regard to the type of research we publish. The AAAAI also embraces the international A/I community. Like the AAAAI, JACI: Global strives to reach out to the international A/I community. However, studies from many regions focus on more focused local A/I issues or are in more formative stages. Thus, these investigators often face stiff competition for acceptance in our sister journals. Additionally, many funding agencies now require work they fund to be presented in fully open access publications. To increase our international reach, JACI: Global will serve as a fully open access journal and will meet the open access requirements of any funding agency. Additionally, by being open access, articles published in JACI: Global will be accessible by anybody with Internet access. We are a fully online journal, a format which provides publication flexibility and allows articles to be immediately available after acceptance. Journal operations began in July 2021 with the selection of the Editor-in-Chief and proceeding with several fundamental early decisions. Our first article submissions were received in September 2021. Initially we are receiving submissions in 2 ways: one is direct submission to JACI: Global. The second is the transfer of sound articles that are not quite a fit for JACI and JACI: In Practice to JACI: Global. We are pleased to report that even prior to formally publishing our first issue (coincident with the 2022 AAAAI Annual Meeting), we have received over 60 manuscripts and have currently accepted 9, which are available online. We have received submissions from Ethiopia, South Africa, India, Japan, Australia, New Zealand, Austria, France, Germany, Ireland, The Netherlands, Spain, Sweden, Turkey, Brazil, Canada, and the United States. Or put another way, we have received submissions from every continent except Antarctica; another way in which we are being “Global.” The next step for JACI: Global is to be formally indexed. As an open access journal, we can apply to PubMed Central after publishing 25 articles. By being listed in PubMed Central, our articles will also be findable in PubMed, rapidly increasing visibility of our published research to the research community. This is an initial step in obtaining an official Impact Factor. However, as important as Impact Factor is to a journal, our guiding vision is to publish methodologically sound research from the A/I community, be it totally developed phase III studies or initial phase I or bench studies. We envision working with our sister journals and the AAAAI to develop programs to increase visibility of our authors and citations of their work to enhance their H factor. I am honored and grateful to be selected to serve as the inaugural Editor-in-Chief for JACI: Global. I am also grateful to have been joined by Drs Lanny Rosenwasser and Mimi Tang as Associate Editors, and to benefit from the outstanding collaboration from Zuhair Ballas, MD, and Michael Schatz, MD, editors-in-chief of JACI and JACI: In Practice, and the AAAAI Board of Directors. As we approach the national meeting, we plan on expanding our Associate Editor corps and convening our Editorial Board. This is an exciting time for JACI: Global. We hope you will join us on this inaugural flight and all the flights to come. JACI: Global is now ready for boarding!

Allergic asthma (AA) is a common asthma phenotype, and its diagnosis requires both the demonstration of IgE‐sensitization to aeroallergens and the causative role of this sensitization as a major driver of asthma symptoms. Therefore, a bronchial allergen challenge (BAC) would be occasionally required to identify AA patients among atopic asthmatics. Nevertheless, BAC is usually considered a research tool only, with existing protocols being tailored to mild asthmatics and research needs (eg long washout period for inhaled corticosteroids). Consequently, existing BAC protocols are not designed to be performed in moderate‐to‐severe asthmatics or in clinical practice. The correct diagnosis of AA might help select patients for immunomodulatory therapies. Allergen sublingual immunotherapy is now registered and recommended for controlled or partially controlled patients with house dust mite‐driven AA and with FEV1 ≥ 70%. Allergen avoidance is costly and difficult to implement for the management of AA, so the proper selection of patients is also beneficial. In this position paper, the EAACI Task Force proposes a methodology for clinical BAC that would need to be validated in future studies. The clinical implementation of BAC could ultimately translate into a better phenotyping of asthmatics in real life, and into a more accurate selection of patients for long‐term and costly management pathways.

Allergic rhinitis (AR), a chronic inflammatory disease, significantly impacts quality of life and socioeconomic burden. AR inflammation is driven by environmental allergens as well as indoor and outdoor pollutants, with increased prevalence and symptoms associated with increasing levels of ambient pollutants. This real-world study investigated associations between AR symptoms, patient activity, and levels of environmental allergens and pollutants. Adult patients living in the US, who experienced moderate/severe seasonal/perennial allergies in the past year (Allergic Rhinitis Impact on Asthma [ARIA] criteria) and used a Fitbit® wearable and accelerometer were included. Patients completed twice-daily allergy questionnaires for 16 weeks during spring 2020. Real time air quality data and pollen counts were collected. Endpoints included changes in total nasal symptom score, pollen Index, CO, NO2, O3, particulate matter (PM) <10μm/ <2.5μm, SO2, and activity-tracking. Regression models estimated associations between AR symptoms or wearable data and pollutant levels. Of 1,559 participants, mean age was 38.6 (SD 9.9) years, 64.3% were female and nearly half had a college education (48.9%). More severe AR symptoms correlated with warmer and drier days, higher barometric pressure, higher pollen (tree & grass), higher PM10 and NO2, lower CO, SO2 and PM2.5, higher daily steps, higher heart rate and heart rate variability, and lower sleep duration and quality. This large study confirmed that increased allergen and pollutant exposure is associated with increased AR symptoms. The associations between Fitbit-derived activity data and AR symptoms support the use of wearable devices for passive monitoring of AR symptoms and behaviour.

Biomass fuel smoke, secondhand smoke, and oxides of nitrogen are common causes of household air pollution (HAP). Almost 2.4 billion people worldwide use solid fuels for cooking and heating, mostly in low-and middle-income countries. Wood combustion for household heating is also common in many areas of high-income countries, and minorities are particularly vulnerable. HAP in low-and middle-income countries is associated with asthma, acute respiratory tract infections in adults and children, chronic obstructive pulmonary disease, lung cancer, tuberculosis, and respiratory mortality. Although wood smoke exposure levels in high-income countries are typically lower than in lower-income countries, it is similarly associated with accelerated lung function decline, higher prevalence of airflow obstruction and chronic bronchitis, and higher all-cause and respiratory cause -specific mortality. Household air cleaners with high-efficiency particle filters have mixed effects on asthma and chronic obstructive pulmonary disease outcomes. Biomass fuel interventions in low-income countries include adding chimneys to cookstoves, improving biomass fuel combustion stoves, and switching fuel to liquid petroleum gas. Still, the impact on health outcomes is inconsistent. In high-income countries, strategies for reducing biomass fuel -related HAP are centered on community-level woodstove changeout pro-grams, although the results are again inconsistent. In addi-tion, initiatives to encourage home smoking bans have mixed success in households with children. Environmental solutions to reduce HAP have varying success in reducing pollutants and health problems. Improved understanding of indoor air quality factors and actions that prevent degradation or improve polluted indoor air may lead to enhanced environ-mental health policies, but health outcomes must be rigor-ously examined. (c) 2022 American Academy of Allergy, Asthma & Immunology (J Allergy Clin Immunol Pract

Background We are currently screening human volunteers to determine their sputum polymorphonuclear neutrophil (PMN) response 6- and 24-hours following initiation of exposure to wood smoke particles (WSP). Inflammatory responders (>= 10% increase in %PMN) are identified for their subsequent participation in mitigation studies against WSP-induced airways inflammation. In this report we compared responder status (N = 52) at both 6 and 24 hr time points to refine/expand its classification, assessed the impact of the GSTM1 genotype, asthma status and sex on responder status, and explored whether sputum soluble phase markers of inflammation correlate with PMN responsiveness to WSP. Results Six-hour responders tended to be 24-hour responders and vice versa, but 24-hour responders also had significantly increased IL-1beta, IL-6, IL-8 at 24 hours post WSP exposure. The GSTM1 null genotype significantly (p < 0.05) enhanced the %PMN response by 24% in the 24-hour responders and not at all in the 6 hours responders. Asthma status enhanced the 24 hour %PMN response in the 6- and 24-hour responders. In the entire cohort (not stratified by responder status), we found a significant, but very small decrease in FVC and systolic blood pressure immediately following WSP exposure and sputum %PMNs were significantly increased and associated with sputum inflammatory markers (IL-1beta, IL-6, IL-8, and PMN/mg) at 24 but not 6 hours post exposure. Blood endpoints in the entire cohort showed a significant increase in %PMN and PMN/mg at 6 but not 24 hours. Sex had no effect on %PMN response. Conclusions The 24-hour time point was more informative than the 6-hour time point in optimally and expansively defining airway inflammatory responsiveness to WSP exposure. GSTM1 and asthma status are significant effect modifiers of this response. These study design and subject parameters should be considered before enrolling volunteers for proof-of-concept WSP mitigation studies.

Rationale: Ozone is a common pollutant known to cause airway inflammation and airway hyperresponsiveness (AHR). The inflammatory response to acute ozone exposure is predominantly neutrophilic, with IL-1 implicated as a key cytokine, however, the mechanisms remain uncertain. We tested the hypothesis that caspase-1-dependent inflammasome activation is required for neutrophilic inflammation in response to ozone using in vivo exposure in a mouse model. Methods: Wild type (WT), Nlrp3−/−, Nlrp1b−/−, Casp1−/−, Asc−/−, and Il1b−/−mice were exposed to ozone at a concentration of 2.0 ppm for 3 hours. Twenty-four hours post-ozone exposure, bronchoalveolar lavage (BAL) was collected to record total and differential cell counts. AHR and airway resistance to inhaled methacholine was assessed at 24 hours after ozone exposure. WT groups were compared to KO strains in independent experiments, and statistical testing was performed using student’s t-test. Results: Ozone-induced inflammation in BAL was attenuated in Il1b−/− mice. Significant reductions were observed in total cell counts (p=0.0009) and neutrophils (p=0.0112) in Il1b−/− compared to WT. In contrast, there was no significant different in total inflammatory cells or neutrophils in BAL after ozone exposure in Nlrp3−/−, Nlrp1b−/−, Casp1−/−, or Asc−/− mice. There was no difference in ozone-induced AHR between WT and Il1b, Nlrp3, Nlrp1b, Caspase-1, or Asc-deficient mice. Conclusions: These results support a model in which ozone-induced neutrophilic inflammation is driven by IL-1β, independent of caspase-1-dependent inflammasome activation. Further investigation into the mechanisms controlling IL-1β production after ozone exposure is warranted.

Background : We are currently screening human volunteers to determine their sputum polymorphonuclear neutrophil (PMN) response 6 and 24 hours following initiation of exposure to wood smoke particles (WSP). Inflammatory responders ( > 10% increase in %PMN) are identified for their subsequent participation in mitigation studies against WSP-induced airways inflammation. In this report we compared responder status (N=52) at both 6 and 24hr time points to refine/expand its classification, assessed the impact of the GSTM1 genotype, asthma status and sex on responder status, and explored whether sputum soluble phase markers of inflammation correlate with PMN responsiveness to WSP. Results : In the entire cohort, we found a significant, but very small, decrease in FVC and systolic blood pressure immediately following WSP exposure and sputum %PMNs were significantly increased at 24 hours post exposure, the latter finding was also significantly correlated with sputum IL-1b, IL-6, IL-8, and PMN/mg; a similar response was not found at the 6 hour %PMN response. Blood endpoints in the entire cohort showed a significant increase in %PMN and PMN/mg at 6 but not 24 hours. Six-hour responders tended to be 24-hour responders and vice versa, but 24-hour responders also had significantly increased IL-1b, IL-6, IL-8 at 24 hours post WSP exposure. The GSTM1 null genotype significantly (p<0.05) enhanced the %PMN response at 6 hours in the entire cohort, by 24% in the 24-hour responders and not at all in the 6 hours responders. Asthma status enhanced the 24 hour %PMN response in the entire cohort and in the 6- and 24-hour responders. Sex had no effect on %PMN response. Conclusions : The 24 hour time point was more informative than the 6 hour time point in optimally defining airway inflammatory responsiveness to WSP exposure. GSTM1 and asthma status are significant effect modifiers of this response. These study design and subject parameters should be considered before enrolling volunteers for proof-of-concept WSP mitigation studies.