Epidemiologic studies suggest that dietary vitamin E is an important candidate intervention for asthma. Our group has shown that daily consumption of vitamin E (gamma tocopherol, γT) has anti-inflammatory actions in both rodent and human phase I studies. The objective of this study was to test whether γT supplementation could mitigate a model of neutrophilic airway inflammation in rats and in healthy human volunteers.
F344/N rats were randomized to oral gavage with γT versus placebo, followed by intranasal LPS (20 ug) challenge. Bronchoalveolar lavage fluid and lung histology were used to assess airway neutrophil recruitment. In a phase IIa clinical study, 13 nonasthmatic subjects completed a double-blinded, placebo controlled crossover study where they consumed either a γT-enriched capsule or a sunflower oil placebo capsule. After 7 days of daily supplementation, they underwent an inhaled LPS challenge. Induced sputum was assessed for neutrophils 6 hours after inhaled LPS. The effect of γT compared to placebo on airway neutrophils post-LPS was compared using a repeated measures analysis of variance.
In rats, oral γT supplementation significantly reduced tissue infiltration (p<0.05) and accumulation of airway neutrophils (p<0.05) that are elicited by intranasal LPS challenge compared to control rats. In human volunteers, γT treatment significantly decreased induced sputum neutrophils (p=0.03) compared to placebo.
Oral supplementation with γT reduced airway neutrophil recruitment in both rat and human models of inhaled LPS challenge. These results suggest that γT is a potential therapeutic candidate for prevention or treatment of neutrophilic airway inflammation in diseased populations.
Vitamin E; gamma-tocopherol; Endotoxin; Eosinophil; Neutrophil; Induced Sputum; Oxidative Stress; Nitrosative Stress; Rat; LPS
GSTM1null genotype; PMN responsiveness; ozone; innate immune phenotypes
Elevated inflammation and altered immune responses are features found in atopic asthmatic airways. Recent studies indicate gamma-tocopherol (GT) supplementation can suppress airway inflammation in allergic asthma. We studied the effects of in vitro GT supplementation on receptor-mediated phagocytosis and expression of cell surface molecules associated with innate and adaptive immunity on sputum-derived macrophages. Cells from non-smoking healthy (n = 6) and mild house dust mite-sensitive (HDM) allergic asthmatics (n = 6) were treated ex vivo with GT (300 μM) or saline (control). Phagocytosis of opsonized Zymosan A bioparticles (S. cerevisiae) and expression of surface molecules associated with innate and adaptive immunity were assessed using flow cytometry. GT caused significantly decreased (P < 0.05) internalization of attached Zymosan bioparticles and decreased (P < 0.05) macrophage expression of CD206, CD36 and CD86 in allergic asthmatics but not in controls. Overall, GT caused down-regulation of both innate and adaptive immune response elements and atopic status appears to be an important factor.
allergy; asthma; macrophages; phagocytosis; flow cytometry; gamma-tocopherol; host defense
In human airways diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD), host defense is compromised and airways inflammation and infection often result. Mucus clearance and trapping of inhaled pathogens constitute key elements of host defense. Clearance rates are governed by mucus viscous and elastic moduli at physiological driving frequencies, whereas transport of trapped pathogens in mucus layers is governed by diffusivity. There is a clear need for simple and effective clinical biomarkers of airways disease that correlate with these properties. We tested the hypothesis that mucus solids concentration, indexed as weight percent solids (wt%), is such a biomarker. Passive microbead rheology was employed to determine both diffusive and viscoelastic properties of mucus harvested from human bronchial epithelial (HBE) cultures. Guided by sputum from healthy (1.5–2.5 wt%) and diseased (COPD, CF; 5 wt%) subjects, mucus samples were generated in vitro to mimic in vivo physiology, including intermediate range wt% to represent disease progression. Analyses of microbead datasets showed mucus diffusive properties and viscoelastic moduli scale robustly with wt%. Importantly, prominent changes in both biophysical properties arose at ∼4 wt%, consistent with a gel transition (from a more viscous-dominated solution to a more elastic-dominated gel). These findings have significant implications for: (1) penetration of cilia into the mucus layer and effectiveness of mucus transport; and (2) diffusion vs. immobilization of micro-scale particles relevant to mucus barrier properties. These data provide compelling evidence for mucus solids concentration as a baseline clinical biomarker of mucus barrier and clearance functions.
Increased susceptibility of smokers to ambient PM may potentially promote development of COPD and accelerate already present disease.
To characterize the acute and subacute lung function response and inflammatory effects of controlled chamber exposure to concentrated ambient fine particles (CAFP) with MMAD ≤ 2.5 microns in ex-smokers and lifetime smokers.
Eleven subjects, aged 35–74 years, came to the laboratory 5 times; a training day and two exposure days separated by at least 3 weeks, each with a post-exposure visit 22 h later. Double-blind and counterbalanced exposures to “clean air” (mean 1.5 ± 0.6 μg/m3) or CAFP (mean 108.7 ± 24.8 μg/m3 ) lasted 2 h with subjects at rest.
At 3 h post-exposure subjects’ DTPA clearance half-time significantly increased by 6.3 min per 100 μg/m3 of CAFP relative to “clean air”. At 22 h post-exposure they showed significant reduction of 4.3% per 100 μg/m3 in FEV1 and a significant DLCO decrease by 11.1% per 100 μg/m3 of CAFP relative to “clean air”. At both 3 h and 22 h the HDL cholesterol level significantly decreased by 4.5% and 4.1%, respectively. Other blood chemistries and markers of lung injury, inflammation and procoagulant activity were within the normal range of values at any condition.
The results suggest that an acute 2 h resting exposure of smokers and ex-smokers to fine ambient particulate matter may transiently affect pulmonary function (spirometry and DLCO) and increase DTPA clearance half-time. Except for a post exposure decrease in HDL no other markers of pulmonary inflammation, prothrombotic activity and lung injury were significantly affected under the conditions of exposure.
CAFP; Chamber exposure; Spirometry; Older smokers; Ex-smokers; DTPA clearance half-time; Lung diffusing capacity; Blood chemistry
We have employed nasal challenge with lipopolysaccharide (LPS) followed by nasal lavage (NL) to experimentally induce and examine upper airway inflammation in human volunteers. It is unclear however whether adaptation within individuals occurs following repeated nasal challenge. This was a pilot study to determine if repeated nasal LPS challenge yields attenuation of markers of inflammation (primarily neutrophil response) in the NL fluid of healthy humans.
We employed a 3-day nasal LPS challenge protocol with NL using a “split nose” design. The control and LPS nares received two consecutive day saline (0.9% saline/day) and LPS (2 μg LPS/day) challenges, respectively followed by an LPS (2 μg/day) challenge to each nare on Day 3. NL was performed immediately pre Day 1 challenges and 6-h post nasal LPS challenges on both Days 1 and 3. Markers of inflammation (PMNs/mg, cytokines) were assessed in NL and the inflammatory response to LPS (measured as the difference between pre and post challenge) was evaluated in both nares on Day 3 and compared to Day 1.
Significant (p < 0.05) blunting of the LPS-induced polymorphonuclear leukocyte (PMN) response was observed in the nare that received repeated LPS challenges as compared to the control nare (67.60 ± 22.39 vs. 157.8 ± 76.04 PMN/mg) and initial LPS challenge on Day 1 (121 ± 32 PMN/mg). Decreased soluble CD14 and significantly decreased interleukin-8 were also found in the repeat LPS-treated nare. In the LPS-treated nare, the blunted PMN response on Day 3 correlated well with the observed PMN response on Day1 (r = 0.58, p = 0.02).
We show attenuation of PMN response to repeated LPS in the nasal airways in healthy humans. Effect of repeat endotoxin exposure prior to allergen delivery on local airway inflammation in both healthy and atopic subjects can be studied.
Airway inflammation; neutrophils; adaptation; lipopolysaccharide (LPS, endotoxin)
To determine if the GSTM1 null genotype is a risk factor for increased inflammatory response to inhaled endotoxin.
35 volunteers who had undergone inhalation challenge with a 20 000 endotoxin unit dose of Clinical Center Reference Endotoxin (CCRE) were genotyped for the GSTM1 null polymorphism. Parameters of airway and systemic inflammation observed before and after challenge were compared in GSTM1 null (n=17) and GSTM1 (n=18) sufficient volunteers.
GSTM1 null volunteers had significantly increased circulating white blood cells (WBCs), polymorphonuclear neutrophils (PMNs), platelets and sputum PMNs (% sputum PMNs and PMNs/mg sputum) after CCRE challenge. GSTM1 sufficient volunteers had significant, but lower increases in circulating WBCs, PMNs and % sputum PMNs, and no increase in platelets or PMNs/mg sputum. Linear regression analysis adjusted for baseline values of the entire cohort revealed that the GSTM1 null genotype significantly increased circulating WBCs, platelets and % sputum PMNs after challenge
These data support the hypothesis that the GSTM1 null genotype is a risk factor for increased acute respiratory and systemic inflammatory response to inhaled CCRE. These data are consistent with other observations that the GSTM1 null genotype is associated with increased respiratory, systemic and cardiovascular effects linked to ambient air particulate matter exposure and indicate that the GSTM1 null genotype should be considered a risk factor for adverse health effects associated with exposure to environmental endotoxin.
Atopic asthmatic patients are reported to be more sensitive to the effects of environmental endotoxin (LPS) than healthy volunteers (HVs). It is unknown whether this sensitivity is due to dysregulated inflammatory responses after LPS exposure in atopic asthmatic patients.
We sought to test the hypothesis that atopic asthmatic patients respond differentially to inhaled LPS challenge compared with HVs.
Thirteen allergic asthmatic (AA) patients and 18 nonallergic nonasthmatic subjects (healthy volunteers [HVs]) underwent an inhalation challenge to 20,000 endotoxin units of Clinical Center Reference Endotoxin (LPS). Induced sputum and peripheral blood were obtained at baseline and 6 hours after inhaled LPS challenge. Sputum and blood samples were assayed for changes in inflammatory cell numbers and cytokine and cell-surface marker levels on monocytes and macrophages.
The percentage of neutrophils in sputum (%PMN) in induced sputum similarly and significantly increased in both HVs and AA patients after inhaled LPS challenge. However, the absolute numbers of leukocytes and PMNs recruited to the airways were significantly lower in AA patients compared with those seen in HVs with inhaled LPS challenge. Sputum levels of IL-6 and TNF-α were significantly increased in both cohorts, but levels of IL-1β and IL-18 were only significantly increased in the HV group. Cell-surface expression of Toll-like receptors 4 and 2 were significantly enhanced only in the HV group.
The airway inflammatory response to inhaled LPS challenge is blunted in AA patients compared with that seen in HVs and accompanied by reductions in airway neutrophilia and inflammasome-dependent cytokine production. These factors might contribute to increased susceptibility to airway microbial infection or colonization in AA patients.
Asthma; LPS; induced sputum; inflammasome; innate immunity
Acute exacerbations in allergic asthmatics may lead to impaired ability to clear mucus from the airways, a key factor in asthma morbidity.
The purpose of this study was to determine the effect of inhaled house dust mite challenge on regional deposition of inhaled particles and mucociliary clearance (MCC) in allergic asthmatics.
We used gamma scintigraphy (inhalation of 99mTc -sulfur colloid particles) to measure regional particle deposition and MCC in allergic asthmatics (n=12) 4hr following an inhaled dust mite allergen challenge (Dermatophagoides farinae extract; PDmax = fall in FEV1 of 10%) for comparison to baseline non-challenge measures.
In responders (n=9 PDmax dose), lung function returned to pre-challenge values by 3 hours but was significantly decreased at 6 and 24 hours in 3 of the responders (i.e. late phase response) and induced sputum eosinophils were increased at 24 hours post-challenge (p < 0.05). Responders showed enhanced bronchial airway deposition of inhaled particles (p < 0.05) and slowed clearance from the central lung zone (p < 0.01) at 4 hrs post-challenge compared to baseline (no allergen challenge) that was predicted by the PDmax allergen concentration (r = − 0.70, p < 0.05). The fall in lung function at 24 hours post challenge correlated with reduced MCC from the central lung zone (r = − 0.78, p < 0.02) and PDmax. Non-responders (n=3) had no change in lung function, regional deposition or MCC post-challenge vs. baseline.
Conclusions and clinical relevance
These data suggest that regional deposition and clearance of inhaled particles may be sensitive for detecting mild airway obstruction associated with early and late-phase allergen-induced effects on mucus secretions. The study was listed on clinicaltrials.gov (NCT00448851).
dust-mite allergen; particle inhalation; airway deposition; mucus
The effects of low-level ozone exposure (0.08 ppm) on pulmonary function in healthy young adults are well known; however, much less is known about the inflammatory and immunomodulatory effects of low-level ozone in the airways. Techniques such as induced sputum and flow cytometry make it possible to examine airways inflammatory responses and changes in immune cell surface phenotypes following low-level ozone exposure. The purpose of this study was to determine if exposure to 0.08 parts per million ozone for 6.6 h induces inflammation and modifies immune cell surface phenotypes in the airways of healthy adult subjects. Fifteen normal volunteers underwent an established 0.08 part per million ozone exposure protocol to characterize the effect of ozone on airways inflammation and immune cell surface phenotypes. Induced sputum and flow cytometry were used to assess these endpoints 24 h before and 18 h after exposure. The results showed that exposure to 0.08 ppm ozone for 6.6 h induced increased airway neutrophils, monocytes, and dendritic cells and modified the expression of CD14, HLA-DR, CD80, and CD86 on monocytes 18 h following exposure. Exposure to 0.08 parts per million ozone is associated with increased airways inflammation and promotion of antigen-presenting cell phenotypes 18 hours following exposure. These findings need to be replicated in a similar experiment that includes a control air exposure.
Antigen-presenting cells; dendritic cell; inflammation; macrophage; ozone; pollution; polymorphonu-clear neutrophil
The evaluation of sputum leukocytes by flow cytometry is an opportunity to assess characteristics of cells residing in the central airways, yet it is hampered by certain inherent properties of sputum including mucus and large amounts of contaminating cells and debris.
To develop a gating strategy based on specific antibody panels in combination with light scatter properties for flow cytometric evaluation of sputum cells.
Healthy and mild asthmatic volunteers underwent sputum induction. Manually selected mucus “plug” material was treated with dithiothrietol, filtered and total leukocytes acquired. Multicolor flow cytometry was performed using specific gating strategies based on light scatter properties, differential expression of CD45 and cell lineage markers to discriminate leukocytes from squamous epithelial cells and debris.
The combination of forward scatter and CD45 expression reliably segregated sputum leukocytes from contaminating squamous epithelial cells and debris. Overlap of major leukocyte populations (neutrophils, macrophages/monocytes) required the use of specific antibodies (e.g. CD16, CD64, CD14, HLA-DR) that differentiated granulocytes from monocytes and macrophages. These gating strategies allowed identification of small populations of eosinophils, CD11c+ myeloid dendritic cells, B cells and NK cells.
Multicolor flow cytometry can be successfully applied to sputum samples to identify and characterize leukocyte populations residing on the surfaces of the central airways.
induced sputum; flow cytometry; immunophenotype; methods; human
Climate change is a constant and ongoing process. It is postulated that human activities have reached a point at which we are producing global climate change. This article provides suggestions to help the allergist/environmental physician integrate recommendations about improvements in outdoor and indoor air quality and the likely response to predicted alterations in the earth’s environment into their patient’s treatment plan. Many changes that affect respiratory disease are anticipated. Examples of responses to climate change include energy reduction retrofits in homes that could potentially affect exposure to allergens and irritants, more hot sunny days that increase ozone-related difficulties, and rises in sea level or altered rainfall patterns that increase exposure to damp indoor environments. Climate changes can also affect ecosystems, manifested as the appearance of stinging and biting arthropods in new areas. Higher ambient carbon dioxide concentrations, warmer temperatures, and changes in floristic zones could potentially increase exposure to ragweed and other outdoor allergens, whereas green practices such as composting can increase allergen and irritant exposure. Finally, increased energy costs may result in urban crowding and human source pollution, leading to changes in patterns of infectious respiratory illnesses. Improved governmental controls on airborne pollutants could lead to cleaner air and reduced respiratory diseases but will meet strong opposition because of their effect on business productivity. The allergy community must therefore adapt, as physician and research scientists always have, by anticipating the needs of patients and by adopting practices and research methods to meet changing environmental conditions.
Exposure to ozone activates innate immune function and causes neutrophilic (PMN) airway inflammation that in some individuals is robustly elevated. The interplay between immuno-inflammatory function and genomic signaling in those with heightened inflammatory responsiveness to ozone is not well understood.
Determine baseline predictors and post exposure discriminators for the immuno-inflammatory response to ozone in inflammatory responsive adult volunteers.
Sputum induction was performed on 27 individuals before and after a two hour chamber exposure to 0.4 ppm ozone. Subjects were classified as inflammatory responders or non-responders to ozone based on their PMN response. Innate immune function, inflammatory cell and cytokine modulation and transcriptional signaling pathways were measured in sputum.
Post exposure, responders showed activated innate immune function (CD16: 31,004 MFI vs 8988 MFI; CD11b: 44,986 MFI vs 24,770 MFI; CD80: 2236 MFI vs 1506 MFI; IL-8: 37,603 pg/ml vs 2828 pg/ml; and IL-1β: 1380 pg/ml vs 318 pg/ml) with muted signaling of immune cell trafficking pathways. In contrast, non-responders displayed decreased innate immune activity (CD16, CD80; phagocytosis: 2 particles/PMN vs 4 particles/PMN) post exposure that was accompanied by a heightened signaling of immune cell trafficking pathways.
Inflammatory responsive and non responsive individuals to ozone show an inverse relationship between immune cell trafficking and immuno-inflammatory functional responses to ozone. These distinct genomic signatures may further our understanding about ozone-induced morbidity in individuals with different levels of inflammatory responsiveness.
Air pollution; Environment; Ozone; Gene expression; Human sputum; Immune response; Innate immunity; Systems biology
Deficits in inflammasomes, a key element of innate immunity, confer increased susceptibility to infection. We report that sputum cells from asthmatics have decreased expression of inflammasome factors, consistent with reports of increased infection risk in asthmatics.
Innate Immunity; Asthma; Atopy; Inflammasome; IL-1β
Rationale: Exposure to ozone causes a decrease in spirometric lung function and an increase in airway inflammation in healthy young adults at concentrations as low as 0.08 ppm, close to the National Ambient Air Quality Standard for ground level ozone.
Objectives: To test whether airway effects occur below the current ozone standard and if they are more pronounced in potentially susceptible individuals, such as those deficient in the antioxidant gene glutathione S-transferase mu 1 (GSTM1).
Methods: Pulmonary function and subjective symptoms were measured in 59 healthy young adults (19–35 yr) immediately before and after exposure to 0.0 (clean air, CA) and 0.06 ppm ozone for 6.6 hours in a chamber while undergoing intermittent moderate exercise. The polymorphonuclear neutrophil (PMN) influx was measured in 24 subjects 16 to 18 hours postexposure.
Measurements and Main Results: Subjects experienced a significantly greater (P = 0.008) change in FEV1 (± SE) immediately after exposure to 0.06 ppm ozone compared with CA (−1.71 ± 0.50% vs. −0.002 ± 0.46%). The decrement in FVC was also greater (P = 0.02) after ozone versus CA (−2.32 ± 0.41% vs. −1.13 ± 0.34%). Similarly, changes in %PMN were greater after ozone (54.0 ± 4.6%) than CA (38.3 ± 3.7%) exposure (P < 0.001). Symptom scores were not different between ozone versus CA. There were no significant differences in changes in FEV1, FVC, and %PMN between subjects with GSTM1-positive and GSTM1-null genotypes.
Conclusions: Exposure of healthy young adults to 0.06 ppm ozone for 6.6 hours causes a significant decrement of FEV1 and an increase in neutrophilic inflammation in the airways. GSTM1 genotype alone appears to have no significant role in modifying the effects.
pulmonary function; airway inflammation; polymorphism; ozone exposure; exercise
Ozone exposure triggers airway inflammatory responses that may be influenced by biologically active purine metabolites.
Examine the relationships between airway purine metabolites and established inflammatory markers of ozone exposure, and determine if these relationships are altered in individuals with atopy or asthma.
Materials and Methods
Mass spectrometry was utilized to measure concentrations of purine metabolites (AMP, adenosine, hypoxanthine, uric acid) and non-purine metabolites (taurine, urea, phenylalanine, tyrosine) in induced sputum obtained from 31 subjects with normal lung function (13 healthy controls, 8 atopic non-asthmatics, and 10 atopic asthmatic) before and four hours after ozone exposure.
At baseline, the purines AMP and hypoxanthine correlated with multiple inflammatory markers including neutrophil counts and the cytokines IL-6, IL-8, TNF-α, and IL-1β (r ranged from 0.41–0.66, all p<0.05). Following ozone exposure, these purines remained correlated with IL-6, IL-8, and TNF-α (r=0.37-0.68). However, AMP and hypoxanthine increased significantly post ozone exposure in atopic nonasthmatics but not atopic asthmatics. In contrast, the non-purine metabolite taurine correlated with baseline neutrophil counts (r=0.56) and IL-6 (r=0.53) and was elevated post exposure in both atopic cohorts.
Discussion and Conclusions
The purine metabolites AMP and hypoxanthine are correlated with multiple inflammatory markers at baseline and after ozone exposure. However, changes in these purine metabolites after ozone appear to differ from other inflammatory markers, with less response in atopic asthmatics relative to atopic nonasthmatics. Purine metabolites may play a role in the signaling responses to ozone, but these responses may be altered in subjects with asthma.
Induced sputum; adenosine; adenosine monophosphate; hypoxanthine; taurine
Oxidative stress plays a significant role in allergic airway inflammation. Supplementation with alpha-tocopherol (alone or combined with ascorbate/vitamin C) has been assessed as an intervention for allergic airway diseases with conflicting results. Enhancing levels of airway antioxidants with oral supplements has been suggested as an intervention to protect individuals from the effect of inhaled oxidants, although it is unclear whether supplementation changes tocopherol or vitamin C levels in both serum and airway fluids. Our objective was to obtain pilot safety and dosing data from 14 allergic asthmatic volunteers examining the effect of daily combination oral therapy with 500 mg alpha-tocopherol (αT) and 2 g vitamin C for 12 wk. We examined serum and airway fluid and cellular levels of alpha- and gamma-tocopherol (γT) and vitamin C to plan for future studies of these agents in asthma and allergic rhinitis. Six volunteers completed 12 wk of active treatment with αT and vitamin C and 8 completed placebo. Blood and sputum samples were obtained at baseline and at 6 wk and 12 wk of therapy and were analyzed for αT, γT, and vitamin C levels in the serum, sputum supernatant, and sputum cells. Combination treatment increased serum vitamin C and significantly decreased sputum αT and serum γT levels. No changes were found in sputum supernatant or sputum cell vitamin C or serum αT levels in the active treatment group. In conclusion, supplementation with αT and high-dose vitamin C does not augment vitamin C levels in the respiratory-tract lining fluid.
CD14, a co-receptor for endotoxin, plays a significant role in the inflammatory response to this environmentally important pollutant. The C-159T single nucleotide polymorphism (SNP) in the CD14 gene promoter is reported to affect expression of CD14, with TT homozygous persons having higher CD14 expression. This SNP has been linked to pathogenesis of asthma and with cardiovascular diseases in smokers. We hypothesize that CD14 also plays a role in development of COPD in smokers who are exposed to inhaled endotoxin by cigarette smoking and to endotoxin released from Gram-negative microbes colonizing their airways. To assess the effect of the C-159T SNP of the CD14 gene promoter on lung function and GOLD score in smokers with COPD, we recruited 246 smokers with COPD with a range of 10–156 pack-year smoking exposures. We found that the C-159T single gene polymorphism of the CD14 gene promoter may play a role in modulating severity of obstructive impairment in smokers with COPD: The TT genotype was associated with lower lung function in smokers with a moderate smoking history. However, the CC genotype was associated with decreased lung function in heavy smokers (>56 pack-years). The result on CC genotype in risk for COPD is analogous with the effect of this genotype in risk for asthma. CD14 may be a factor in the pathophysiology of COPD, as it is in asthma and smoking-related cardiovascular diseases.
Asthma is a known risk factor for acute ozone-associated respiratory disease. Ozone (O3) causes an immediate decrease in lung function and increased airway inflammation. The role of atopy and asthma in modulation of O3-induced inflammation has not been determined.
To determine if atopic status modulates O3 response phenotypes in humans.
Fifty volunteers (25 normal volunteers, 14 atopic non-asthmatics, 11 atopic asthmatics not requiring maintenance therapy) underwent a 0.4 ppm O3 exposure protocol. Ozone response was determined by changes in lung function and induced sputum composition, including airway inflammatory cell concentration, cell surface markers, cytokine and hyaluronic acid concentration.
All cohorts experienced similar decreases in lung function post O3. Atopics and atopic asthmatics had increased sputum neutrophils and IL-8 after O3 exposure; levels did not significantly change in normal volunteers. Following O3 exposure, atopic asthmatics had significantly increased sputum IL-6 and IL-1 β, and airway macrophage TLR4, FceRI, and CD23 expression; levels in normal volunteers and atopic non-asthmatics showed no significant change. Atopic asthmatics had significantly decreased IL-10 at baseline compared to normal volunteers: IL-10 did not significantly change in any group with O3. All groups had similar levels of hyaluronic acid at baseline, with increased levels after O3 exposure in atopics and atopic asthmatics.
Atopic asthmatics have increased airway inflammatory responses to O3. Elevated TLR4 expression suggests a potential pathway through which O3 generates the inflammatory response in allergic asthmatics but not in atopics without asthma.
These observations suggest that mild atopic asthma confers increased risk for exacerbation of O3-induced lung disease through promoting an enhanced innate immune inflammatory response to O3.
ozone; innate immunity; asthma; atopy; hyaluronic acid; environmental airways disease; interleukin-1 beta; interleukin-10
Ozone and lipopolysaccharide (LPS) are environmental pollutants with adverse health effects noted in both healthy and asthmatic individuals. The authors and others have shown that inhalation of ozone and LPS both induce airway neutrophilia. Based on these similarities, the authors tested the hypothesis that common biological factors determine response to these two different agents. Fifteen healthy, nonasthmatic volunteers underwent a 0.4 part per million ozone exposure for 2 h while performing intermittent moderate exercise. These same subjects underwent an inhaled LPS challenge with 20,000 LPS units of Clinical Center Reference LPS, with a minimum of 1 month separating these two challenge sessions. Induced sputum was obtained 24 h before and 4–6 h after each exposure session. Sputum was assessed for total and differential cell counts and expression of cell surface proteins as measured by flow cytometry. Sputum supernatants were assayed for cytokine concentration. Both ozone and LPS challenge augmented sputum neutrophils and subjects’ responses were significantly correlated (R = .73) with each other. Ozone had greater overall influence on cell surface proteins by modifying both monocytes (CD14, human leukocyte antigen [HLA]-DR, CD11b) and macrophages (CD11b, HLA-DR) versus LPS where CD14 and HLA-DR were modified only on monocytes. However, LPS significantly increased interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, with no significant increases seen after ozone challenge. Ozone and LPS exposure in healthy volunteers induce similar neutrophil responses in the airways; however, downstream activation of innate immune responses differ, suggesting that oxidant versus bacterial air pollutants may be mediated by different mechanisms.
Exposure of humans to air pollutants such as ozone and particulate matter (PM) may result in airway and systemic inflammation and altered immune function. One putative mechanism may be through modification of cell-surface costimulatory molecules.
We examined whether changes in expression of costimulatory molecules on circulating cells are associated with ambient levels of fine PM [aerodynamic diameter ≤ 2.5 μm (PM2.5)] in a susceptible population of diabetic individuals.
Twenty subjects were studied for 4 consecutive days. Daily measurements of PM2.5 and meteorologic data were acquired on the rooftop of the exam site. Circulating cell-surface markers that mediate innate immune and inflammatory responses were assessed by flow cytometry on each day. Sensitivity analysis was conducted on glutathione S-transferase M1 (GSTM1) genotype, body mass index, and glycosylated hemoglobin A1c (HbA1c) levels to determine their role as effect modifiers. Data were analyzed using random effects models adjusting for season, weekday, and meteorology.
We found significantly increased monocyte expression (mean fluorescent intensity) of CD80, CD40, CD86, HLA-DR, and CD23 per 10-μg/m3 increase in PM2.5 at 2- to 4-day lag times after exposure. These findings were significantly higher in obese individuals, in individuals with HbA1c > 7%, and in participants who were GSTM1 null.
Exposure to PM2.5 can enhance antigen-presenting cell phenotypes on circulating cells, which may have consequences in the development of allergic or autoimmune diseases. These effects are amplified in diabetic individuals with characteristics that are associated with insulin resistance or with oxidative stress.
air pollution; costimulatory receptors; diabetes; inflammation; flow cytometry; particulate matter
The Glutathione-S-Transferase Mu 1 null genotype has been reported to be a risk factor for acute respiratory disease associated with increases in ambient air ozone. Ozone is known to cause an immediate decrease in lung function and increased airway inflammation. However, it is not known if GSTM1 modulates these ozone responses in vivo in humans
The purpose of this study was to determine if the GSTM1 null genotype modulates ozone responses in humans.
Thirty-five normal volunteers were genotyped for the GSTM1 null mutation and underwent a standard ozone exposure protocol to determine if lung function and inflammatory responses to ozone were different between the 19 GSTM1 normal and 16 GSTM1 null volunteers.
GSTM1 did not modulate lung function responses to acute ozone. Granulocyte influx 4 hours after challenge was similar between GSTM1 normal and null volunteers. However, GSTM1 null volunteers had significantly increased airway neutrophils 24 hours after challenge, as well as increased expression of HLA-DR on airway macrophages and dendritic cells.
The GSTM1 null genotype is associated with increased airways inflammation 24 hours following ozone exposure, consistent with the lag time observed between increased ambient air ozone exposure and exacerbations of lung disease.
These observations suggest that the GSTM1 null genotype likely confers increased risk for exacerbation of ozone-induced lung disease through promoting an enhanced neutrophilic and monocytic inflammatory response to ozone.
The GSTM1 null genotype is associated with increased risk for ozone-induced lung disease. We report the GSTM1 genotype modulates ozone-induced inflammation but not lung function, and may predict persons at risk for environmental lung disease.
Glutathione-S-Transferase Mu 1; Ozone; Pollution; Inflammation; Polymorphonuclear Neutrophil; Macrophage; Dendritic cell