Airway transcriptome networks identify susceptibility to frequent asthma exacerbations in children.

BACKGROUND: Frequent asthma exacerbators, defined as those experiencing more than 1 hospitalization in a year for an asthma exacerbation, represent an important subgroup of individuals with asthma. However, this group remains poorly defined and understudied in children. OBJECTIVE: Our aim was to determine the molecular mechanisms underlying asthma pathogenesis and exacerbation frequency. METHODS: We performed RNA sequencing of upper airway cells from both frequent and nonfrequent exacerbators enrolled in the Ohio Pediatric Asthma Repository. RESULTS: Through molecular network analysis, we found that nonfrequent exacerbators display an increase in modules enriched for immune system processes, including type 2 inflammation and response to infection. In contrast, frequent exacerbators showed expression of modules enriched for nervous system processes, such as synaptic formation and axonal outgrowth. CONCLUSION: These data suggest that the upper airway of frequent exacerbators undergoes peripheral nervous system remodeling, representing a novel mechanism underlying pediatric asthma exacerbation.

Use of Fractional Exhaled Nitric Oxide to Guide the Treatment of Asthma: An Official American Thoracic Society Clinical Practice Guideline.

Background: The fractional exhaled nitric oxide (FENO) test is a point-of-care test that is used in the assessment of asthma. Objective: To provide evidence-based clinical guidance on whether FENO testing is indicated to optimize asthma treatment in patients with asthma in whom treatment is being considered. Methods: An international, multidisciplinary panel of experts was convened to form a consensus document regarding a single question relevant to the use of FENO. The question was selected from three potential questions based on the greatest perceived impact on clinical practice and the unmet need for evidence-based answers related to this question. The panel performed systematic reviews of published randomized controlled trials between 2004 and 2019 and followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) evidence-to-decision framework to develop recommendations. All panel members evaluated and approved the recommendations. Main Results: After considering the overall low quality of the evidence, the panel made a conditional recommendation for FENO-based care. In patients with asthma in whom treatment is being considered, we suggest that FENO is beneficial and should be used in addition to usual care. This judgment is based on a balance of effects that probably favors the intervention; the moderate costs and availability of resources, which probably favors the intervention; and the perceived acceptability and feasibility of the intervention in daily practice. Conclusions: Clinicians should consider this recommendation to measure FENO in patients with asthma in whom treatment is being considered based on current best available evidence.

Evidence for Exacerbation-Prone Asthma and Predictive Biomarkers of Exacerbation Frequency.

Rationale: Cross-sectional studies suggest an exacerbation-prone asthma (EPA) phenotype and the utility of blood eosinophils and plasma IL-6 as predictive biomarkers.Objectives: To prospectively test for EPA phenotype and utility of baseline blood measures of eosinophils and IL-6 as predictive biomarkers.Methods: Three-year asthma exacerbation data were analyzed in 406 adults in the Severe Asthma Research Program-3. Transition models were used to assess uninformed and informed probabilities of exacerbation in year 3. Binomial regression models were used to assess eosinophils and IL-6 as predictive biomarkers.Measurements and Main Results: Eighty-three participants (21%) had ≥1 exacerbation in each year (EPA) and 168 participants (41%) had no exacerbation in any year (exacerbation-resistant asthma). The uninformed probability of an exacerbation in Year 3 was 40%, but the informed probability increased to 63% with an exacerbation in Year 2 and 82% with an exacerbation in Years 1 and 2. The probability of a Year 3 exacerbation with no Year 1 or 2 exacerbations was 13%. Compared with exacerbation-resistant asthma, EPA was characterized by lower FEV1 and a higher prevalence of obesity, hypertension, and diabetes. High-plasma IL-6 occurred in EPA, and the incident rate ratio for exacerbation increased 10% for each 1-pg/µl increase in baseline IL-6 level. Although high blood eosinophils did not occur in EPA, the incident rate ratio for exacerbations increased 9% for each 100-cell/µl increase in baseline eosinophil number.Conclusions: Longitudinal analysis confirms an EPA phenotype characterized by features of metabolic dysfunction. Blood measures of IL-6, but not eosinophils, were significantly associated with EPA, and IL-6 and eosinophils predicted exacerbations in the sample as a whole.

Severe asthma during childhood and adolescence: A longitudinal study.

BACKGROUND: Morbidity and mortality associated with childhood asthma are driven disproportionately by children with severe asthma. However, it is not known from longitudinal studies whether children outgrow severe asthma. OBJECTIVE: We sought to study prospectively whether well-characterized children with severe asthma outgrow their asthma during adolescence. METHODS: Children with asthma were assessed at baseline with detailed questionnaires, allergy tests, and lung function tests and were reassessed annually for 3 years. The population was enriched for children with severe asthma, as assessed by the American Thoracic Society/European Respiratory Society guidelines, and subject classification was reassessed annually. RESULTS: At baseline, 111 (59%) children had severe asthma. Year to year, there was a decrease in the proportion meeting the criteria for severe asthma. After 3 years, only 30% of subjects met the criteria for severe asthma (P < .001 compared with enrollment). Subjects experienced improvements in most indices of severity, including symptom scores, exacerbations, and controller medication requirements, but not lung function. Surprisingly, boys and girls were equally likely to has resolved asthma (33% vs 29%). The odds ratio in favor of resolution of severe asthma was 2.75 (95% CI, 1.02-7.43) for those with a peripheral eosinophil count of greater than 436 cells/µL. CONCLUSIONS: In longitudinal analysis of this well-characterized cohort, half of the children with severe asthma no longer had severe asthma after 3 years; there was a stepwise decrease in the proportion meeting severe asthma criteria. Surprisingly, asthma severity decreased equally in male and female subjects. Peripheral eosinophilia predicted resolution. These data will be important for planning clinical trials in this population.

Development and initial validation of the Asthma Severity Scoring System (ASSESS).

BACKGROUND: Tools for quantification of asthma severity are limited. OBJECTIVE: We sought to develop a continuous measure of asthma severity, the Asthma Severity Scoring System (ASSESS), for adolescents and adults, incorporating domains of asthma control, lung function, medications, and exacerbations. METHODS: Baseline and 36-month longitudinal data from participants in phase 3 of the Severe Asthma Research Program (NCT01606826) were used. Scale properties, responsiveness, and a minimally important difference were determined. External replication was performed in participants enrolled in the Severe Asthma Research Program phase 1/2. The utility of ASSESS for detecting treatment response was explored in participants undergoing corticosteroid responsiveness testing with intramuscular triamcinolone and participants receiving biologics. RESULTS: ASSESS scores ranged from 0 to 20 (8.78 ± 3.9; greater scores reflect worse severity) and differed among 5 phenotypic groups. Measurement properties were acceptable. ASSESS was responsive to changes in quality of life with a minimally important difference of 2, with good specificity for outcomes of asthma improvement and worsening but poor sensitivity. Replication analyses yielded similar results, with a 2-point decrease (improvement) associated with improvements in quality of life. Participants with a 2-point or greater decrease (improvement) in ASSESS scores also had greater improvement in lung function and asthma control after triamcinolone, but these differences were limited to phenotypic clusters 3, 4, and 5. Participants treated with biologics also had a 2-point or greater decrease (improvement) in ASSESS scores overall. CONCLUSIONS: The ASSESS tool is an objective measure that might be useful in epidemiologic and clinical research studies for quantification of treatment response in individual patients and phenotypic groups. However, validation studies are warranted.

Weighing in on asthma: Insights on BMI, magnesium, and hospitalizations from the Ohio Pediatric Asthma Repository.

Objective: Little is known about weight status and its effects on clinical course during hospitalization for asthma exacerbation. We sought to evaluate associations between weight status, specifically body mass index (BMI), with inpatient clinical course and clinical history.Methods: We retrospectively analyzed data from 2012 to 2013 on children hospitalized for asthma exacerbation in a state-wide longitudinal cohort, the Ohio Pediatric Asthma Repository. We examined BMI continuously (z scores) and categorically, comparing overweight and obese (Ov/Ob) to non-overweight and non-obese (nOv/nOb) children. We used linear mixed models controlling for site effects to determine if BMI was related to length of stay, as determined by physiologic readiness for discharge (PRD), defined as time to albuterol spaced every 4 h, need for nonstandard care or clinical history.Results: Across six hospitals, 874 children were included in analyses. BMI was positively associated with PRD (p=.008) but this increase was unlikely to be clinically significant. Ov/Ob children were more likely than nOv/nOb to require nonstandard care with repeat magnesium dosing in intensive care after dosing in the emergency department (OR = 3.23, 95%CI 1.39-7.78). Hospitalization in the year prior to enrollment was positively associated with BMI percentile (73.3 vs. 66.0, p=.028). Sleep disordered breathing was also associated with higher BMI percentile (78.2 vs. 65.9; p=.0013).Conclusions: Ov/Ob children had similar PRD to nOv/nOb children and were prone to repeat magnesium dosing. Previous hospitalization for exacerbation was positively associated with increasing BMI percentile. Additional research should investigate differential magnesium use by weight status, quantifying risks and benefits.

Effects of endogenous sex hormones on lung function and symptom control in adolescents with asthma.

BACKGROUND: Although pre-puberty asthma is more prevalent in males, after puberty through middle-age, asthma is more prevalent in females. The surge of sex hormones with puberty might explain this gender switch. METHODS: To examine the effects of sex hormones on lung function and symptoms with puberty, Tanner stage was assessed in 187 children 6-18 years of age (59% severe) enrolled in the NIH/NHLBI Severe Asthma Research Program (SARP). The effects of circulating sex hormones (n = 68; testosterone, dehydroepiandrosterone sulfate (DHEA-S), estrogen, and progesterone) on lung function and 4 week symptom control (ACQ6) in cross-section were tested by linear regression. RESULTS: From pre-/early to late puberty, lung function did not change significantly but ACQ6 scores improved in males with severe asthma. By contrast females had lower post-BD FEV1% and FVC% and worse ACQ6 scores with late puberty assessed by breast development. In males log DHEA-S levels, which increased by Tanner stage, associated positively with pre- and post-BD FEV1%, pre-BD FVC %, and negatively (improved) with ACQ6. Patients treated with high-dose inhaled corticosteroids had similar levels of circulating DHEA-S. In females, estradiol levels increased by Tanner stage, and associated negatively with pre-BD FEV1% and FVC %. CONCLUSIONS: These results support beneficial effects of androgens on lung function and symptom control and weak deleterious effects of estradiol on lung function in children with asthma. Longitudinal data are necessary to confirm these cross-sectional findings and to further elucidate hormonal mechanisms informing sex differences in asthma features with puberty. TRIAL REGISTRATION: ClinicalTrials.gov registration number: NCT01748175 .

How Schools Can Help Address Social Determinants of Health in Asthma Management.

Schools are in a unique position to address social determinants of health (SDOHs) in pediatric asthma management because of their potential to provide resources and facilitate collaboration with health care providers and services for children at risk within their community. SDOHs include economic factors, educational attainment and health literacy, neighborhood factors and the built environment, social and community aspects including discrimination and racism, and health care access and quality. These factors have a significant impact on asthma health in children, and certain populations such as minoritzed populations and those living in high-poverty environments have been shown to be at greater risk for adverse effects of SDOHs on asthma outcomes. School-based asthma programs address several SDOHs including health literacy, the built environment, and health care quality and access and have been shown to improve asthma outcomes. Key components include connection between the school and the health care team, self-management education, and directly observed therapy. School nurses play a key role in directing and managing effective programs because they can evaluate and support a student's health while considering the effect of SDOHs at interpersonal, institutional, community, and policy levels.

Impact of Lung Function on Asthma Exacerbation Rates in Children Treated with Dupilumab: The VOYAGE Study.

Background: Severe, uncontrolled asthma and asthma exacerbations in children are associated with abnormal lung function and airway development, and increased risk of chronic obstructive lung disease in adulthood. The rationale for this post hoc analysis was to explore the relationship between changes in asthma exacerbation rates and lung function in children treated with dupilumab. Methods: This post hoc analysis included children aged 6 to 11 years with uncontrolled, moderate-to-severe type 2 asthma (blood eosinophils ≥150 cells/µL or fractional exhaled nitric oxide ≥20 ppb) who received dupilumab or placebo in the phase 3 LIBERTY ASTHMA VOYAGE study (NCT02948959). Endpoints were the proportion of patients achieving clinically meaningful improvements (≥5% or ≥10%) in pre-bronchodilator percent-predicted forced expiratory volume in 1 second (ppFEV1) by Week 12, annualized severe asthma exacerbation rates from Week 12-52, and mean change from baseline in ppFEV1 to Week 12. Results: At Week 12 of VOYAGE, 141/236 (60%) of children treated with dupilumab and 57/114 (50%) of children receiving placebo showed improvements of ≥5% in ppFEV1; 106/236 (45%) children receiving dupilumab and 36/114 (32%) receiving placebo achieved improvements in ppFEV1 ≥10%. During the Week 12-52 treatment period, dupilumab vs placebo significantly reduced severe exacerbation rates in all subgroups by 52-60% (all P<0.05). Dupilumab treatment resulted in rapid and sustained improvements in ppFEV1 (Week 12 least squares mean difference [95% CI] vs placebo: 3.54 [0.30, 6.78] percentage points; P=0.03) in children who achieved improvements of ≥5%. Conclusion: Dupilumab vs placebo significantly improved pre-bronchodilator ppFEV1, with a higher proportion of patients achieving a clinically meaningful response at Week 12. Dupilumab also significantly reduced severe exacerbation rates, independent of pre-bronchodilator ppFEV1 response at Week 12. Trial Registration: NCT02948959.

Comparison of Caregiver- and Child-Reported Quality of Life in Children With Sleep-Disordered Breathing.

OBJECTIVE: Caregivers frequently report poor quality of life (QOL) in children with sleep-disordered breathing (SDB). Our objective is to assess the correlation between caregiver- and child-reported QOL in children with mild SDB and identify factors associated with differences between caregiver and child report. STUDY DESIGN: Analysis of baseline data from a multi-institutional randomized trial SETTING: Pediatric Adenotonsillectomy Trial for Snoring, where children with mild SDB (obstructive apnea-hypopnea index <3) were randomized to observation or adenotonsillectomy. METHODS: The Pediatric Quality of Life Inventory (PedsQL) assessed baseline global QOL in participating children 5 to 12 years old and their caregivers. Caregiver and child scores were compared. Multivariable regression assessed whether clinical factors were associated with differences between caregiver and child report. RESULTS: PedsQL scores were available for 309 families (mean child age, 7.0 years). The mean caregiver-reported PedsQL score was higher at 75.2 (indicating better QOL) than the mean child-reported score of 67.9 (P < .001). The agreement between caregiver and child total PedsQL scores was poor, with intraclass correlation coefficients of 0.03 (95% CI, -0.09 to 0.15) for children 5 to 7 years old and 0.21 (95% CI, 0.03-0.38) for children 8 to 12 years old. Higher child age and health literacy were associated with closer agreement between caregiver and child report. CONCLUSION: Caregiver- and child-reported global QOL in children with SDB was weakly correlated, more so for young children. In pediatric SDB, child-perceived QOL may be poorer than that reported by caregivers. Further research is needed to assess whether similar trends exist for disease-specific QOL metrics.

Sleep-disordered breathing is associated with asthma severity in children.

OBJECTIVE: To examine the relationships among obesity, sleep-disordered breathing (SDB, defined as intermittent nocturnal hypoxia and habitual snoring), and asthma severity in children. We hypothesized that obesity and SDB are associated with severe asthma at a 1- year follow-up. STUDY DESIGN: Children aged 4-18 years were recruited sequentially from a specialty asthma clinic and underwent physiological, anthropometric, and biochemical assessment at enrollment. Asthma severity was determined after 1 year of follow-up and guideline-based treatment, using a composite measure of level of controller medication, symptom burden, and health care utilization. Multivariate logistic regression was used to examine adjusted associations of SDB and obesity with asthma severity at 12-month follow-up. RESULTS: Among 108 subjects (mean age, 9.1±3.4 years; 45.4% African-American; 67.6% male), obesity and SDB were common, affecting 42.6% and 29.6% of subjects, respectively. After adjusting for obesity, race, and sex, children with SDB had a 3.62-fold increased odds of having severe asthma at follow-up (95% CI, 1.26-10.40). Obesity was not associated with asthma severity. CONCLUSION: SDB is a modifiable risk factor for severe asthma after 1 year of specialty asthma care. Further studies are needed to determine whether treating SDB improves asthma morbidity.

Improving Surveillance and Epidemic Response in Ohio Childcare Settings.

At the start of the Coronavirus Disease of 2019 (COVID-19) pandemic, the risk of cases in childcare programs was unknown. Thus, a rapid-response research approach was launched in Ohio childcare settings. Passive surveillance data from a state-operated incident reporting system were evaluated to estimate the number of COVID-19 cases from 15 August 2020 to 1 January 2021. Additionally, active surveillance with self-administered reverse transcriptase-polymerase chain reaction (RT-PCR) tests were conducted among staff at 46 childcare programs. Finally, six zoom-based focus groups with program administrators were used to gain feedback. Staff and children in childcare settings contributed 0.38% and 0.15% of the COVID-19 cases in Ohio during this timeframe, respectively. RT-PCR testing identified 3 unrecognized cases (0.88% of tests), and all occurred when the statewide positivity rate was >5%. Focus groups revealed that access to affordable cleaning supplies, masks, and reliable staffing were critical. Perhaps most importantly, we conclude that expanding the incident reporting system to include a childcare census would allow for the tracking of future health problems with highly valuable incidence rate estimations.

Neurobehavioral morbidity of pediatric mild sleep-disordered breathing and obstructive sleep apnea.

STUDY OBJECTIVES: Obstructive sleep apnea is associated with neurobehavioral dysfunction, but the relationship between disease severity as measured by the apnea-hypopnea index and neurobehavioral morbidity is unclear. The objective of our study is to compare the neurobehavioral morbidity of mild sleep-disordered breathing versus obstructive sleep apnea. METHODS: Children 3-12 years old recruited for mild sleep-disordered breathing (snoring with obstructive apnea-hypopnea index < 3) into the Pediatric Adenotonsillectomy Trial for Snoring were compared to children 5-9 years old recruited for obstructive sleep apnea (obstructive apnea-hypopnea 2-30) into the Childhood Adenotonsillectomy Trial. Baseline demographic, polysomnographic, and neurobehavioral outcomes were compared using univariable and multivariable analysis. RESULTS: The sample included 453 participants with obstructive sleep apnea (median obstructive apnea-hypopnea index 5.7) and 459 participants with mild sleep-disordered breathing (median obstructive apnea-hypopnea index 0.5). By polysomnography, participants with obstructive sleep apnea had poorer sleep efficiency and more arousals. Children with mild sleep-disordered breathing had more abnormal executive function scores (adjusted odds ratio 1.96, 95% CI 1.30-2.94) compared to children with obstructive sleep apnea. There were also elevated Conners scores for inattention (adjusted odds ratio 3.16, CI 1.98-5.02) and hyperactivity (adjusted odds ratio 2.82, CI 1.83-4.34) in children recruited for mild sleep-disordered breathing. CONCLUSIONS: Abnormal executive function, inattention, and hyperactivity were more common in symptomatic children recruited into a trial for mild sleep-disordered breathing compared to children recruited into a trial for obstructive sleep apnea. Young, snoring children with only minimally elevated apnea-hypopnea levels may still be at risk for deficits in executive function and attention. TRIAL REGISTRATION: Pediatric Adenotonsillectomy for Snoring (PATS), NCT02562040; Childhood Adenotonsillectomy Trial (CHAT), NCT00560859.

Burden of prematurity-associated recurrent wheezing: caregiver missed work in the D-Wheeze trial.

OBJECTIVE: This study describes the burden of prematurity-associated wheezing in black infants with respect to caregiver missed work. STUDY DESIGN: We analyzed data from the D-Wheeze trial (ClinicalTrials.gov identifier NCT01601847). Black infants between 28-0/7 to 36-6/7 weeks' gestational age at birth receiving <28 days of supplemental oxygen were enrolled. The primary outcome was missed work to care for the infant in the first year. RESULTS: 147/277 (53.1%) infants had caregivers who reported time off. In an adjusted model, vitamin D supplementation (OR 0.52 [95% CI 0.30-0.89]; P = 0.018), recurrent wheeze (OR 2.26 [95% CI, 1.15-4.44]; P = 0.018), and other children in the household <5 years old (OR 0.45 [95% CI 0.26-0.78]; P = 0.004) were significantly associated with caregiver missed work. CONCLUSIONS: Black premature infants had a significant burden of caregiver missed work, emphasizing the impact of prematurity-associated wheezing.

The role of inhaled corticosteroids in the management of cystic fibrosis.

The lung disease of cystic fibrosis (CF) is characterized by a vicious cycle of airway obstruction, chronic bacterial infection, and vigorous inflammation, which ultimately results in bronchiectasis. Recognition that excessive and persistent inflammation is a key factor in lung destruction has prompted investigation into anti-inflammatory therapies. Although effective, the use of systemic corticosteroids has been limited by the unacceptable adverse effect profile. Inhaled corticosteroids (ICS) are a widely prescribed anti-inflammatory agent in CF, likely as a result of clinicians' familiarity with these agents and their excellent safety profile at low doses in asthmatic patients. However, while multiple studies are limited by small sample size and short duration, they consistently failed to demonstrate statistically or clinically significant benefits of ICS use in CF. This review provides an overview of the inflammatory response in CF, the mechanisms of action of corticosteroids, the safety of ICS, and the literature relevant to the use of ICS in CF.

Severe Asthma in Childhood.

Severe asthma is broadly defined as asthma requiring a high level of therapy, usually high doses of inhaled corticosteroids, to bring under control. Children who remain symptomatic despite such treatment are a heterogeneous population, and bear a high burden of disease and require high resource utilization. Children with severe asthma require a comprehensive evaluation, careful consideration of alternative diagnoses and comorbid conditions, assessment of medication adherence and environmental conditions, and frequent disease monitoring.

Life Cycle of Childhood Asthma: Prenatal, Infancy and Preschool, Childhood, and Adolescence.

Asthma is a heterogeneous developmental disorder influenced by complex interactions between genetic susceptibility and exposures. Wheezing in infancy and early childhood is highly prevalent, with a substantial minority of children progressing to established asthma by school age, most of whom are atopic. Adolescence is a time of remission of symptoms with persistent lung function deficits. The transition to asthma in adulthood is not well understood.

Prenatal particulate air pollution exposure and sleep disruption in preschoolers: Windows of susceptibility.

BACKGROUND: The programming of sleep architecture begins in pregnancy and depends upon optimal in utero formation and maturation of the neural connectivity of the brain. Particulate air pollution exposure can disrupt fetal brain development but associations between fine particulate matter (PM2.5) exposure during pregnancy and child sleep outcomes have not been previously explored. METHODS: Analyses included 397 mother-child pairs enrolled in a pregnancy cohort in Mexico City. Daily ambient prenatal PM2.5 exposure was estimated using a validated satellite-based spatio-temporally resolved prediction model. Child sleep periods were estimated objectively using wrist-worn, continuous actigraphy over a 1-week period at age 4-5 years. Data-driven advanced statistical methods (distributed lag models (DLMs)) were employed to identify sensitive windows whereby PM2.5 exposure during gestation was significantly associated with changes in sleep duration or efficiency. Models were adjusted for maternal education, season, child's age, sex, and BMI z-score. RESULTS: Mother's average age was 27.7 years, with 59% having at least a high school education. Children slept an average of 7.7 h at night, with mean 80.1% efficiency. The adjusted DLM identified windows of PM2.5 exposure between 31 and 35 weeks gestation that were significantly associated with decreased sleep duration in children. In addition, increased PM2.5 during weeks 1-8 was associated with decreased sleep efficiency. In other exposure windows (weeks 39-40), PM2.5 was associated with increased sleep duration. CONCLUSION: Prenatal PM2.5 exposure is associated with altered sleep in preschool-aged children in Mexico City. Pollutant exposure during sensitive windows of pregnancy may have critical influence upon sleep programming.

SMAD3 expression is regulated by mitogen-activated protein kinase kinase-1 in epithelial and smooth muscle cells.

SMAD3 is a transcription factor that mediates TGF-beta1 signaling and is known to be important in many of the cellular processes that regulate fibrosis and inflammation. Although several studies have examined SMAD3 activation, little is known about the control of SMAD3 expression. It is well established that the mitogen-activated protein kinase (MAPK) pathway is responsive to TGF-beta1 stimulation and coordinates with SMAD signaling in many cases; therefore, the hypothesis of this study is that the MAPK pathway will be involved in the regulation of SMAD3 expression. Using a SMAD3 promoter construct, we demonstrate that inhibition of either c-Jun-N-terminal kinase (JNK) or p38 activity has little effect on SMAD3 promoter function. Inhibition of mitogen-activated protein kinase kinase-1 (MEK1) with either PD98059 or UO126, however, results in a substantial dose-dependent inhibition of SMAD3 promoter activity. Further studies confirm that promoter activity correlates with protein expression by demonstrating reduced SMAD3 protein expression in A549 cells and airway smooth muscle cells after treatment with MEK1 inhibitors. Positive regulation of SMAD3 expression is also demonstrated by expression of a constitutively active (ca)-MEK1 construct, where the presence of ca-MEK1 resulted in increased SMAD3 protein expression. These data lead to the conclusion that MEK1 is an important regulator of SMAD3 expression.