Early Life Wildfire Smoke Exposure Is Associated with Immune Dysregulation and Lung Function Decrements in Adolescence.

The long-term health effects of wildfire smoke exposure in pediatric populations are not known. The objectives of this study were to determine if early life exposure to wildfire smoke can affect parameters of immunity and airway physiology that are detectable with maturity. We studied a mixed-sex cohort of rhesus macaque monkeys that were exposed as infants to ambient wood smoke from a series of Northern California wildfires in the summer of 2008. Peripheral blood mononuclear cells (PBMCs) and pulmonary function measures were obtained when animals were approximately 3 years of age. PBMCs were cultured with either LPS or flagellin, followed by measurement of secreted IL-8 and IL-6 protein. PBMCs from a subset of female animals were also evaluated by Toll-like receptor (TLR) pathway mRNA analysis. Induction of IL-8 protein synthesis with either LPS or flagellin was significantly reduced in PBMC cultures from wildfire smoke-exposed female monkeys. In contrast, LPS- or flagellin-induced IL-6 protein synthesis was significantly reduced in PBMC cultures from wildfire smoke-exposed male monkeys. Baseline and TLR ligand-induced expression of the transcription factor, RelB, was globally modulated in PBMCs from wildfire smoke-exposed monkeys, with additional TLR pathway genes affected in a ligand-dependent manner. Wildfire smoke-exposed monkeys displayed significantly reduced inspiratory capacity, residual volume, vital capacity, functional residual capacity, and total lung capacity per unit of body weight relative to control animals. Our findings suggest that ambient wildfire smoke exposure during infancy results in sex-dependent attenuation of systemic TLR responses and reduced lung volume in adolescence.

Early life allergen and air pollutant exposures alter longitudinal blood immune profiles in infant rhesus monkeys.

Early life is a critical period for the progressive establishment of immunity in response to environmental stimuli; the impact of airborne challenges on this process is not well defined. In a longitudinal fashion, we determined the effect of episodic house dust mite (HDM) aerosol and ozone inhalation, both separately and combined, on peripheral blood immune cell phenotypes and cytokine expression from 4 to 25weeks of age in an infant rhesus monkey model of childhood development. Immune profiles in peripheral blood were compared with lung lavage at 25weeks of age. Independent of exposure, peripheral blood cell counts fluctuated with chronologic age of animals, while IFNγ and IL-4 mRNA levels increased over time in a linear fashion. At 12weeks of age, total WBC, lymphocyte numbers, FoxP3 mRNA and IL-12 mRNA were dramatically reduced relative to earlier time points, but increased to a steady state with age. Exposure effects were observed for monocyte numbers, as well as CCR3, FoxP3, and IL-12 mRNA levels in peripheral blood. Significant differences in cell surface marker and cytokine expression were detected following in vitro HDM or PMA/ionomycin stimulation of PBMC isolated from animals exposed to either HDM or ozone. Lavage revealed a mixed immune phenotype of FoxP3, IFNγ and eosinophilia in association with combined HDM plus ozone exposure, which was not observed in blood. Collectively, our findings show that airborne challenges during postnatal development elicit measureable cell and cytokine changes in peripheral blood over time, but exposure-induced immune profiles are not mirrored in the lung.

SMAD Signaling in the Airways of Healthy Rhesus Macaques versus Rhesus Macaques with Asthma Highlights a Relationship Between Inflammation and Bone Morphogenetic Proteins.

Bone morphogenetic protein (BMP) signaling is important for correct lung morphogenesis, and there is evidence of BMP signaling reactivation in lung diseases. However, little is known about BMP signaling patterns in healthy airway homeostasis and inflammatory airway disease and during epithelial repair. In this study, a rhesus macaque (Macaca mulatta) model of allergic airway disease was used to investigate BMP signaling throughout the airways in health, disease, and regeneration. Stereologic quantification of immunofluorescent images was used to determine the expression of BMP receptor (BMPR) Ia and phosphorylated SMAD (pSMAD) 1/5/8 in the airway epithelium. A pSMAD 1/5/8 expression gradient was found along the airways of healthy juvenile rhesus macaques (n = 3, P < 0.005). Membrane-localized BMPRIa expression was also present in the epithelium of the healthy animals. After exposure to house dust mite allergen and ozone, significant down-regulation of nuclear pSMAD 1/5/8 occurs in the epithelium. When the animals were provided with a recovery period in filtered air, proliferating cell nuclear antigen, pSMAD 1/5/8, and membrane-localized BMPRIa expression were significantly increased in the epithelium of conducting airways (P < 0.005). Furthermore, in the asthmatic airways, altered BMPRIa localization was evident. Because of the elevated eosinophil presence in these airways, we investigated the effect of eosinophil-derived proteins on BMPRIa trafficking in epithelial cells. Eosinophil-derived proteins (eosinophil-derived neurotoxin, eosinophil peroxidase, and major basic protein) induced transient nuclear translocation of membrane-bound BMPRIa. This work mapping SMAD signaling in the airways of nonhuman primates highlights a potential mechanistic relationship between inflammatory mediators and BMP signaling and provides evidence that basal expression of the BMP signaling pathway may be important for maintaining healthy airways.

Persistence of serotonergic enhancement of airway response in a model of childhood asthma.

The persistence of airway hyperresponsiveness (AHR) and serotonergic enhancement of airway smooth muscle (ASM) contraction induced by ozone (O3) plus allergen has not been evaluated. If this mechanism persists after a prolonged recovery, it would indicate that early-life exposure to O3 plus allergen induces functional changes predisposing allergic individuals to asthma-related symptoms throughout life, even in the absence of environmental insult. A persistent serotonergic mechanism in asthma exacerbations may offer a novel therapeutic target, widening treatment options for patients with asthma. The objective of this study was to determine if previously documented AHR and serotonin-enhanced ASM contraction in allergic monkeys exposed to O3 plus house dust mite allergen (HDMA) persist after prolonged recovery. Infant rhesus monkeys sensitized to HDMA were exposed to filtered air (FA) (n = 6) or HDMA plus O3 (n = 6) for 5 months. Monkeys were then housed in a FA environment for 30 months. At 3 years, airway responsiveness was assessed. Airway rings were then harvested, and ASM contraction was evaluated using electrical field stimulation with and without exogenous serotonin and serotonin-subtype receptor antagonists. Animals exposed to O3 plus HDMA exhibited persistent AHR. Serotonin exacerbated the ASM contraction in the exposure group but not in the FA group. Serotonin subtype receptors 2, 3, and 4 appear to drive the response. Our study shows that AHR and serotonin-dependent exacerbation of cholinergic-mediated ASM contraction induced by early-life exposure to O3 plus allergen persist for at least 2.5 years and may contribute to a persistent asthma phenotype.

Ozone-induced airway epithelial cell death, the neurokinin-1 receptor pathway, and the postnatal developing lung.

Children are uniquely susceptible to ozone because airway and lung growth continue for an extensive period after birth. Early-life exposure of the rhesus monkey to repeated ozone cycles results in region-specific disrupted airway/lung growth, but the mediators and mechanisms are poorly understood. Substance P (SP), neurokinin-1 receptor (NK-1R); and nuclear receptor Nur77 (NR4A1) are signaling pathway components involved in ozone-induced cell death. We hypothesize that acute ozone (AO) exposure during postnatal airway development disrupts SP/NK-1R/Nur77 pathway expression and that these changes correlate with increased ozone-induced cell death. Our objectives were to 1) spatially define the normal development of the SP/NK-1R/Nur77 pathway in conducting airways; 2) compare how postnatal age modulates responses to AO exposure; and 3) determine how concomitant, episodic ozone exposure modifies age-specific acute responses. Male infant rhesus monkeys were assigned at age 1 mo to two age groups, 2 or 6 mo, and then to one of three exposure subgroups: filtered air (FA), FA+AO (AO: 8 h/day × 2 days), or episodic biweekly ozone exposure cycles (EAO: 8 h/day × 5 days/14-day cycle+AO). O3 = 0.5 ppm. We found that 1) ozone increases SP/NK-1R/Nur77 pathway expression in conducting airways, 2) an ozone exposure cycle (5 days/cycle) delivered early at age 2 mo resulted in an airway that was hypersensitive to AO exposure at the end of 2 mo, and 3) continued episodic exposure (11 cycles) resulted in an airway that was hyposensitive to AO exposure at 6 mo. These observations collectively associate with greater overall inflammation and epithelial cell death, particularly in early postnatal (2 mo), distal airways.

Diverse forms of pulmonary hypertension remodel the arterial tree to a high shear phenotype.

Pulmonary hypertension (PH) is associated with progressive changes in arterial network complexity. An allometric model is derived that integrates diameter branching complexity between pulmonary arterioles of generation n and the main pulmonary artery (MPA) via a power-law exponent (X) in dn = dMPA2(-n/X) and the arterial area ratio ß = 2(1-2/X). Our hypothesis is that diverse forms of PH demonstrate early decrements in X independent of etiology and pathogenesis, which alters the arteriolar shear stress load from a low-shear stress (X > 2, ß > 1) to a high-shear stress phenotype (X < 2, ß < 1). Model assessment was accomplished by comparing theoretical predictions to retrospective morphometric and hemodynamic measurements made available from a total of 221 PH-free and PH subjects diagnosed with diverse forms (World Health Organization; WHO groups I-IV) of PH: mitral stenosis, congenital heart disease, chronic obstructive pulmonary lung disease, chronic thromboembolism, idiopathic pulmonary arterial hypertension (IPAH), familial (FPAH), collagen vascular disease, and methamphetamine exposure. X was calculated from pulmonary artery pressure (PPA), cardiac output (Q) and body weight (M), utilizing an allometric power-law prediction of X relative to a PH-free state. Comparisons of X between PAH-free and PAH subjects indicates a characteristic reduction in area that elevates arteriolar shear stress, which may contribute to mechanisms of endothelial dysfunction and injury before clinically defined thresholds of pulmonary vascular resistance and PH. We conclude that the evaluation of X may be of use in identifying reversible and irreversible phases of PH in the early course of the disease process.

Simvastatin inhibits smoke-induced airway epithelial injury: implications for COPD therapy.

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death. The statin drugs may have therapeutic potential in respiratory diseases such as COPD, but whether they prevent bronchial epithelial injury is unknown. We hypothesised that simvastatin attenuates acute tobacco smoke-induced neutrophilic lung inflammation and airway epithelial injury. Spontaneously hypertensive rats were given simvastatin (20 mg·kg(-1) i.p.) daily for either 7 days prior to tobacco smoke exposure and during 3 days of smoke exposure, or only during tobacco smoke exposure. Pretreatment with simvastatin prior to and continued throughout smoke exposure reduced the total influx of leukocytes, neutrophils and macrophages into the lung and airways. Simvastatin attenuated tobacco smoke-induced cellular infiltration into lung parenchymal and airway subepithelial and interstitial spaces. 1 week of simvastatin pretreatment almost completely prevented smoke-induced denudation of the airway epithelial layer, while simvastatin given only concurrently with the smoke exposure had no effect. Simvastatin may be a novel adjunctive therapy for smoke-induced lung diseases, such as COPD. Given the need for statin pretreatment there may be a critical process of conditioning that is necessary for statins' anti-inflammatory effects. Future work is needed to elucidate the mechanisms of this statin protective effect.

Exhaled breath condensate profiles of U.S. Navy divers following prolonged hyperbaric oxygen (HBO) and nitrogen-oxygen (Nitrox) chamber exposures.

Prolonged exposure to hyperbaric hyperoxia can lead to pulmonary oxygen toxicity (PO2tox). PO2tox is a mission limiting factor for special operations forces divers using closed-circuit rebreathing apparatus and a potential side effect for patients undergoing hyperbaric oxygen (HBO) treatment. In this study, we aim to determine if there is a specific breath profile of compounds in exhaled breath condensate (EBC) that is indicative of the early stages of pulmonary hyperoxic stress/PO2tox. Using a double-blind, randomized 'sham' controlled, cross-over design 14 U.S. Navy trained diver volunteers breathed two different gas mixtures at an ambient pressure of 2 ATA (33 fsw, 10 msw) for 6.5 h. One test gas consisted of 100% O2(HBO) and the other was a gas mixture containing 30.6% O2with the balance N2(Nitrox). The high O2stress dive (HBO) and low O2stress dive (Nitrox) were separated by at least seven days and were conducted dry and at rest inside a hyperbaric chamber. EBC samples were taken immediately before and after each dive and subsequently underwent a targeted and untargeted metabolomics analysis using liquid chromatography coupled to mass spectrometry (LC-MS). Following the HBO dive, 10 out of 14 subjects reported symptoms of the early stages of PO2tox and one subject terminated the dive early due to severe symptoms of PO2tox. No symptoms of PO2tox were reported following the nitrox dive. A partial least-squares discriminant analysis of the normalized (relative to pre-dive) untargeted data gave good classification abilities between the HBO and nitrox EBC with an AUC of 0.99 (±2%) and sensitivity and specificity of 0.93 (±10%) and 0.94 (±10%), respectively. The resulting classifications identified specific biomarkers that included human metabolites and lipids and their derivatives from different metabolic pathways that may explain metabolomic changes resulting from prolonged HBO exposure.

Postnatal exposure history and airways: oxidant stress responses in airway explants.

Postnatally, the lung continues to grow and differentiate while interacting with the environment. Exposure to ozone (O(3)) and allergens during postnatal lung development alters structural elements of conducting airways, including innervation and neurokinin abundance. These changes have been linked with development of asthma in a rhesus monkey model. We hypothesized that O(3) exposure resets the ability of the airways to respond to oxidant stress and that this is mediated by changes in the neurokinin-1 receptor (NK-1R). Infant rhesus monkeys received episodic exposure to O(3) biweekly with or without house dust mite antigen (HDMA) from 6 to 12 months of age. Age-matched monkeys were exposed to filtered air (FA). Microdissected airway explants from midlevel airways (intrapulmonary generations 5-8) for four to six animals in each of four groups (FA, O(3), HDMA, and HDMA+O(3)) were tested for NK-1R gene responses to acute oxidant stress using exposure to hydrogen peroxide (1.2 mM), a lipid ozonide (10 µM), or sham treatment for 4 hours in vitro. Airway responses were measured using real-time quantitative RT-PCR of NK-1R and IL-8 gene expression. Basal NK-1R gene expression levels were not different between the exposure groups. Treatment with ozonide or hydrogen peroxide did not change NK-1R gene expression in animals exposed to FA, HDMA, or HDMA+O(3). However, treatment in vitro with lipid ozonide significantly increased NK-1R gene expression in explants from O(3)-exposed animals. We conclude that a history of prior O(3) exposure resets the steady state of the airways to increase the NK-1R response to subsequent acute oxidant stresses.

Lung gene expression in a rhesus allergic asthma model correlates with physiologic parameters of disease and exhibits common and distinct pathways with human asthma and a mouse asthma model.

Experimental nonhuman primate models of asthma exhibit multiple features that are characteristic of an eosinophilic/T helper 2 (Th2)-high asthma subtype, characterized by the increased expression of Th2 cytokines and responsive genes, in humans. Here, we determine the molecular pathways that are present in a house dust mite-induced rhesus asthma model by analyzing the genomewide lung gene expression profile of the rhesus model and comparing it with that of human Th2-high asthma. We find that a prespecified human Th2 inflammation gene set from human Th2-high asthma is also present in rhesus asthma and that the expression of the genes comprising this gene set is positively correlated in human and rhesus asthma. In addition, as in human Th2-high asthma, the Th2 gene set correlates with physiologic markers of allergic inflammation and disease in rhesus asthma. Comparison of lung gene expression profiles from human Th2-high asthma, the rhesus asthma model, and a common mouse asthma model indicates that genes associated with Th2 inflammation are shared by all three species. However, some pathophysiologic aspects of human asthma (ie, subepithelial fibrosis, angiogenesis, neural biology, and immune host defense biology) are better represented in the gene expression profile of the rhesus model than in the mouse model. Further study of the rhesus asthma model may yield novel insights into the pathogenesis of human Th2-high asthma.

Allergen and ozone exacerbate serotonin-induced increases in airway smooth muscle contraction in a model of childhood asthma.

BACKGROUND: Serotonin (5-HT) modulates cholinergic neurotransmission and exacerbates airway smooth muscle (ASM) contraction in normal animal and nonasthmatic human tissue. Exposure to house dust mite allergen (HDMA) and ozone (O(3)) leads to airway hyperreactivity and 5-HT-positive cells in the airway epithelium of infant rhesus monkeys. Research shows that concomitant exposure in allergic animals has an additive effect on airway hyperreactivity. OBJECTIVES: In this study, the hypothesis is that the exposure of allergic infant rhesus monkeys to HDMA, O(3) and in combination, acting through 5-HT receptors, enhances 5-HT modulation of postganglionic cholinergic ASM contraction. METHODS: Twenty-four HDMA-sensitized infant monkeys were split into 4 groups at the age of 1 month, and were exposed to filtered air (FA), HDMA, O(3) or in combination (HDMA+O(3)). At the age of 6 months, airway rings were harvested and postganglionic, and parasympathetic-mediated ASM contraction was evaluated using electrical-field stimulation (EFS). RESULTS: 5-HT exacerbated the EFS response within all exposure groups, but had no effect in the FA group. 5-HT(2), 5-HT(3) and 5-HT(4) receptor agonists exacerbated the response. 5-HT concentration-response curves performed after incubation with specific receptor antagonists confirmed the involvement of 5-HT(2), 5-HT(3) and 5-HT(4) receptors. Conversely, a 5-HT(1) receptor agonist attenuated the tension across all groups during EFS, and in ASM contracted via exogenous acetylcholine. CONCLUSIONS: HDMA, O(3) and HDMA+O(3) exposure in a model of childhood allergic asthma enhances 5-HT exacerbation of EFS-induced ASM contraction through 5-HT(2), 5-HT(3) and 5-HT(4) receptors. A nonneurogenic inhibitory pathway exists, unaffected by exposure, mediated by 5-HT(1) receptors located on ASM.

Modelling of individual subject ozone exposure response kinetics.

CONTEXT: A better understanding of individual subject ozone (O(3)) exposure response kinetics will provide insight into how to improve models used in the risk assessment of ambient ozone exposure. OBJECTIVE: To develop a simple two compartment exposure-response model that describes individual subject decrements in forced expiratory volume in one second (FEV(1)) induced by the acute inhalation of O(3) lasting up to 8 h. METHODS: FEV(1) measurements of 220 subjects who participated in 14 previously completed studies were fit to the model using both particle swarm and nonlinear least squares optimization techniques to identify three subject-specific coefficients producing minimum "global" and local errors, respectively. Observed and predicted decrements in FEV(1) of the 220 subjects were used for validation of the model. Further validation was provided by comparing the observed O(3)-induced FEV(1) decrements in an additional eight studies with predicted values obtained using model coefficients estimated from the 220 subjects used in cross validation. RESULTS: Overall the individual subject measured and modeled FEV(1) decrements were highly correlated (mean R(2) of 0.69 ± 0.24). In addition, it was shown that a matrix of individual subject model coefficients can be used to predict the mean and variance of group decrements in FEV(1). CONCLUSION: This modeling approach provides insight into individual subject O(3) exposure response kinetics and provides a potential starting point for improving the risk assessment of environmental O(3) exposure.

Prediction of lung function response for populations exposed to a wide range of ozone conditions.

CONTEXT: A human exposure-response (E-R) model previously demonstrated to accurately predict population mean FEV1 response to ozone exposure has been proposed as the foundation for future risk assessments for ambient ozone. OBJECTIVE: Fit the original and related models to a larger data set with a wider range of exposure conditions and assess agreement between observed and population mean predicted values. MATERIALS AND METHODS: Existing individual E-R data for 23 human controlled ozone exposure studies with a wide range of concentrations, activity levels, and exposure patterns have been obtained. The data were fit to the original model and to a version of the model that contains a threshold below which no response occurs using a statistical program for fitting nonlinear mixed models. RESULTS: Mean predicted FEV1 responses and the predicted proportions of individuals experiencing FEV1 responses greater than 10, 15, and 20% were found to be in agreement with observed responses across a wide range of exposure conditions for both models. The threshold model, however, provided a better fit to the data than the original, particularly at the lowest levels of exposure. CONCLUSION: The models identified in this manuscript predict population FEV1 response characteristics for 18-35-year-old individuals exposed to ozone over a wide range of conditions and represent a substantial improvement over earlier E-R models. Because of its better fit to the data, particularly at low levels of exposure, the threshold model is likely to provide more accurate estimates of risk in future risk assessments of ozone-induced FEV1 effects.

Behavioral inhibition is associated with airway hyperresponsiveness but not atopy in a monkey model of asthma.

OBJECTIVE: To determine whether indicators of behavioral inhibition and cortisol responses to stressful situations, obtained in infancy, were associated with asthma-related measures (atopy and airway hyperresponsiveness [AHR]) approximately 2 years later. METHODS: Measures reflecting inhibited temperament and cortisol response after a 25-hour separation from mother and relocation to a novel room were obtained for 21 rhesus monkeys (mean age, 109 days; range, 91-122 days). Inhibited temperament was measured by reduced emotionality and increased vigilance. Atopy and AHR were assessed after 2 years (age range, 19-35 months) using skin tests to common aeroallergens and inhaled methacholine challenge, respectively. RESULTS: No associations were found between atopy and either behavioral inhibition or cortisol levels (p > .56). Low emotionality was associated with AHR (r = 0.47, p = .03), and a trend was found for blunted cortisol responsiveness and AHR (r = 0.42, p = .06). CONCLUSIONS: Inhibited temperament and blunted cortisol responsiveness may be related to the development of AHR that is common to both nonatopic and atopic asthma phenotypes and may indicate risk for nonatopic asthma specifically.

Increased CCL24/eotaxin-2 with postnatal ozone exposure in allergen-sensitized infant monkeys is not associated with recruitment of eosinophils to airway mucosa.

Epidemiology supports a causal link between air pollutant exposure and childhood asthma, but the mechanisms are unknown. We have previously reported that ozone exposure can alter the anatomic distribution of CD25+ lymphocytes in airways of allergen-sensitized infant rhesus monkeys. Here, we hypothesized that ozone may also affect eosinophil trafficking to allergen-sensitized infant airways. To test this hypothesis, we measured blood, lavage, and airway mucosa eosinophils in 3-month old monkeys following cyclical ozone and house dust mite (HDM) aerosol exposures. We also determined if eotaxin family members (CCL11, CCL24, CCL26) are associated with eosinophil location in response to exposures. In lavage, eosinophil numbers increased in animals exposed to ozone and/or HDM. Ozone+HDM animals showed significantly increased CCL24 and CCL26 protein in lavage, but the concentration of CCL11, CCL24, and CCL26 was independent of eosinophil number for all exposure groups. In airway mucosa, eosinophils increased with exposure to HDM alone; comparatively, ozone and ozone+HDM resulted in reduced eosinophils. CCL26 mRNA and immunofluorescence staining increased in airway mucosa of HDM alone animals and correlated with eosinophil volume. In ozone+HDM animal groups, CCL24 mRNA and immunofluorescence increased along with CCR3 mRNA, but did not correlate with airway mucosa eosinophils. Cumulatively, our data indicate that ozone exposure results in a profile of airway eosinophil migration that is distinct from HDM mediated pathways. CCL24 was found to be induced only by combined ozone and HDM exposure, however expression was not associated with the presence of eosinophils within the airway mucosa.

Novel LC-MS-TOF method to detect and quantify ascorbic and uric acid simultaneously in different biological matrices.

Ascorbic acid (AA) and uric acid (UA) are known as two of the major antioxidants in biological fluids. We report a novel liquid chromatography-mass spectrometry with time-of-flight (LC-MS-TOF) method for the simultaneous quantification of ascorbic and uric acids using MPA, antioxidant solution and acetonitrile as a protein precipitating agent. Both compounds were separated from interferences using a reverse phase C18 column with water and acetonitrile gradient elution (both with formic acid) and identified and quantified by MS in the negative ESI mode. Isotope labeled internal standards were also added to ensure the accuracy of the measures. The method was validated for exhaled breath condensate (EBC), nasal lavage (NL) and plasma samples by assessing selectivity, linearity, accuracy and precision, recovery and matrix effect and stability. Sample volumes below 250 µL were used and linear ranges were determined between 1 - 25 and 1 - 40 µg/mL for ascorbic and uric acid, respectively, for plasma samples, and between 0.05 - 5 (AA) and 0.05 - 7.5 (UA) µg/mL for EBC and NL samples. The new method was successfully applied to real samples from subjects that provided each of the studied matrices. Results showed higher amounts determined in plasma samples, with similar profiles for AA and UA in EBC and NL but at much lower concentrations.

In vivo blockade of OX40 ligand inhibits thymic stromal lymphopoietin driven atopic inflammation.

Thymic stromal lymphopoietin (TSLP) potently induces deregulation of Th2 responses, a hallmark feature of allergic inflammatory diseases such as asthma, atopic dermatitis, and allergic rhinitis. However, direct downstream in vivo mediators in the TSLP-induced atopic immune cascade have not been identified. In our current study, we have shown that OX40 ligand (OX40L) is a critical in vivo mediator of TSLP-mediated Th2 responses. Treating mice with OX40L-blocking antibodies substantially inhibited immune responses induced by TSLP in the lung and skin, including Th2 inflammatory cell infiltration, cytokine secretion, and IgE production. OX40L-blocking antibodies also inhibited antigen-driven Th2 inflammation in mouse and nonhuman primate models of asthma. This treatment resulted in both blockade of the OX40-OX40L receptor-ligand interaction and depletion of OX40L-positive cells. The use of a blocking, OX40L-specific mAb thus presents a promising strategy for the treatment of allergic diseases associated with pathologic Th2 immune responses.

6.6-hour inhalation of ozone concentrations from 60 to 87 parts per billion in healthy humans.

RATIONALE: Identification of the minimal ozone (O(3)) concentration and/or dose that induces measurable lung function decrements in humans is considered in the risk assessment leading to establishing an appropriate National Ambient Air Quality Standard for O(3) that protects public health. OBJECTIVES: To identify and/or predict the minimal mean O(3) concentration that produces a decrement in FEV(1) and symptoms in healthy individuals completing 6.6-hour exposure protocols. METHODS: Pulmonary function and subjective symptoms were measured in 31 healthy adults (18-25 yr, male and female, nonsmokers) who completed five 6.6-hour chamber exposures: filtered air and four variable hourly patterns with mean O(3) concentrations of 60, 70, 80, and 87 parts per billion (ppb). MEASUREMENTS AND MAIN RESULTS: Compared with filtered air, statistically significant decrements in FEV(1) and increases in total subjective symptoms scores (P < 0.05) were measured after exposure to mean concentrations of 70, 80, and 87 ppb O(3). The mean percent change in FEV(1) (+/-standard error) at the end of each protocol was 0.80 +/- 0.90, -2.72 +/- 1.48, -5.34 +/- 1.42, -7.02 +/- 1.60, and -11.42 +/- 2.20% for exposure to filtered air and 60, 70, 80, and 87 ppb O(3), respectively. CONCLUSIONS: Inhalation of 70 ppb O(3) for 6.6 hours, a concentration below the current 8-hour National Ambient Air Quality Standard of 75 ppb, is sufficient to induce statistically significant decrements in FEV(1) in healthy young adults.

Comparison of nonparametric and parametric methods for time-frequency heart rate variability analysis in a rodent model of cardiovascular disease.

The aim of time-varying heart rate variability spectral analysis is to detect and quantify changes in the heart rate variability spectrum components during nonstationary events. Of the methods available, the nonparametric short-time Fourier Transform and parametric time-varying autoregressive modeling are the most commonly employed. The current study (1) compares short-time Fourier Transform and autoregressive modeling methods influence on heart rate variability spectral characteristics over time and during an experimental ozone exposure in mature adult spontaneously hypertensive rats, (2) evaluates the agreement between short-time Fourier Transform and autoregressive modeling method results, and (3) describes the advantages and disadvantages of each method. Although similar trends were detected during ozone exposure, statistical comparisons identified significant differences between short-time Fourier Transform and autoregressive modeling analysis results. Significant differences were observed between methods for LF power (p ≤ 0.014); HF power (p ≤ 0.011); total power (p ≤ 0.027); and normalized HF power (p = 0.05). Furthermore, inconsistencies between exposure-related observations accentuated the lack of agreement between short-time Fourier Transform and autoregressive modeling overall. Thus, the short-time Fourier Transform and autoregressive modeling methods for time-varying heart rate variability analysis could not be considered interchangeable for evaluations with or without interventions that are known to affect cardio-autonomic activity.

Ozone and allergen exposure during postnatal development alters the frequency and airway distribution of CD25+ cells in infant rhesus monkeys.

The epidemiologic link between air pollutant exposure and asthma has been supported by experimental findings, but the mechanisms are not understood. In this study, we evaluated the impact of combined ozone and house dust mite (HDM) exposure on the immunophenotype of peripheral blood and airway lymphocytes from rhesus macaque monkeys during the postnatal period of development. Starting at 30 days of age, monkeys were exposed to 11 cycles of filtered air, ozone, HDM aerosol, or ozone+HDM aerosol. Each cycle consisted of ozone delivered at 0.5 ppm for 5 days (8 h/day), followed by 9 days of filtered air; animals received HDM aerosol during the last 3 days of each ozone exposure period. Between 2-3 months of age, animals co-exposed to ozone+HDM exhibited a decline in total circulating leukocyte numbers and increased total circulating lymphocyte frequency. At 3 months of age, blood CD4+/CD25+ lymphocytes were increased with ozone+HDM. At 6 months of age, CD4+/CD25+ and CD8+/CD25+ lymphocyte populations increased in both blood and lavage of ozone+HDM animals. Overall volume of CD25+ cells within airway mucosa increased with HDM exposure. Ozone did not have an additive effect on volume of mucosal CD25+ cells in HDM-exposed animals, but did alter the anatomical distribution of this cell type throughout the proximal and distal airways. We conclude that a window of postnatal development is sensitive to air pollutant and allergen exposure, resulting in immunomodulation of peripheral blood and airway lymphocyte frequency and trafficking.