Distinct Regulation of Th17 and Th1 Cell Differentiation by Glutaminase-Dependent Metabolism.

Activated T cells differentiate into functional subsets with distinct metabolic programs. Glutaminase (GLS) converts glutamine to glutamate to support the tricarboxylic acid cycle and redox and epigenetic reactions. Here, we identify a key role for GLS in T cell activation and specification. Though GLS deficiency diminished initial T cell activation and proliferation and impaired differentiation of Th17 cells, loss of GLS also increased Tbet to promote differentiation and effector function of CD4 Th1 and CD8 CTL cells. This was associated with altered chromatin accessibility and gene expression, including decreased PIK3IP1 in Th1 cells that sensitized to IL-2-mediated mTORC1 signaling. In vivo, GLS null T cells failed to drive Th17-inflammatory diseases, and Th1 cells had initially elevated function but exhausted over time. Transient GLS inhibition, however, led to increased Th1 and CTL T cell numbers. Glutamine metabolism thus has distinct roles to promote Th17 but constrain Th1 and CTL effector cell differentiation.

Demographic Characteristics, Perinatal Smoking Patterns, and Risk for Neonatal Health Complications Among Pregnant Smokers in the United States Who Begin Using Electronic Cigarettes During Pregnancy: A Descriptive Study Using Population-Based Surveillance Data.

INTRODUCTION: Health agencies have called for research evaluating e-cigarette (EC) use in supporting prenatal smoking cessation. This study aimed to describe (1) the characteristics of smokers who begin using electronic cigarettes (ECs) during pregnancy, (2) how frequently smokers reduce or eliminate pre- and post-natal combustible cigarette (CC) use, and (3) the risk for neonatal health complications among smokers who initiate ECs during pregnancy. AIMS AND METHODS: Pregnant women using CCs exclusively during prepregnancy, who participated in a U.S. surveillance study, were classified by their reported late-pregnancy smoking behavior as CC-exclusive users, EC initiators, or quitters. EC initiators were further subclassified as dual users (used both ECs and CCs) or EC replacers (used ECs exclusively). RESULTS: Of 29 505 pregnant smokers, 1.5% reported using ECs during the last three pregnancy months. Among them, 29.7% became EC-exclusive users. EC initiators were disproportionately non-Hispanic White. Relative to quitters, EC initiators had lower income, were less likely to be married, have intended pregnancies, receive first-trimester prenatal care, and participate in a federal assistance program. Compared to CC-exclusive users, EC initiators overall, and dual users specifically, were more likely to reduce pre- and post-natal CC usage relative to prepregnancy levels. EC initiators' risk for neonatal health complications fell between quitters and CC-exclusive users, though the differences were not statistically significant. CONCLUSIONS: Although EC initiators reduced CC use more than CC-exclusive users, only 29.7% reported complete CC cessation, and there was insufficient evidence of reduction in neonatal health complications relative to CC-exclusive users. Currently, ECs should not be considered a viable gestational smoking cessation strategy. IMPLICATIONS: Health agencies have identified a critical need for research evaluating the use of e-cigarettes in supporting prenatal smoking cessation. Using the U.S. Pregnancy Risk Assessment Monitoring System surveillance study data, we provide real-world evidence that prenatal e-cigarette initiation as a smoking cessation tool is used infrequently among pregnant CCs smokers. Most using e-cigarettes in the last 3 months of pregnancy also used CCs.

Characterization of Immunopathology and Small Airway Remodeling in Constrictive Bronchiolitis.

Rationale: Constrictive bronchiolitis (ConB) is a relatively rare and understudied form of lung disease whose underlying immunopathology remains incompletely defined. Objectives: Our objectives were to quantify specific pathological features that differentiate ConB from other diseases that affect the small airways and to investigate the underlying immune and inflammatory phenotype present in ConB. Methods: We performed a comparative histomorphometric analysis of small airways in lung biopsy samples collected from 50 soldiers with postdeployment ConB, 8 patients with sporadic ConB, 55 patients with chronic obstructive pulmonary disease, and 25 nondiseased control subjects. We measured immune and inflammatory gene expression in lung tissue using the NanoString nCounter Immunology Panel from six control subjects, six soldiers with ConB, and six patients with sporadic ConB. Measurements and Main Results: Compared with control subjects, we found shared pathological changes in small airways from soldiers with postdeployment ConB and patients with sporadic ConB, including increased thickness of the smooth muscle layer, increased collagen deposition in the subepithelium, and lymphocyte infiltration. Using principal-component analysis, we showed that ConB pathology was clearly separable both from control lungs and from small airway disease associated with chronic obstructive pulmonary disease. NanoString gene expression analysis from lung tissue revealed T-cell activation in both groups of patients with ConB with upregulation of proinflammatory pathways, including cytokine-cytokine receptor interactions, NF-κB (nuclear factor-κB) signaling, TLR (Toll-like receptor) signaling, T-cell receptor signaling, and antigen processing and presentation. Conclusions: These findings indicate shared immunopathology among different forms of ConB and suggest that an ongoing T-helper cell type 1-type adaptive immune response underlies airway wall remodeling in ConB.

Mediator production and severity of aspirin-induced respiratory reactions: Impact of sampling site and body mass index.

BACKGROUND: Patients with aspirin-exacerbated respiratory disease can experience severe reactions during aspirin challenge that are associated with high levels of mast cell mediators. The tissue source and clinical factors contributing to systemic mediator levels are unknown. OBJECTIVE: We sought to determine the concordance between respiratory tract and systemic inflammatory mediator levels and identify clinical factors associated with these mediators. METHODS: We performed an oral aspirin challenge in 30 subjects with aspirin-exacerbated respiratory disease. Respiratory symptoms and function, nasal mucosal fluid, blood, and urine were collected at baseline, at the onset of a respiratory reaction, and over a 3-hour observation period. Changes in nasal and systemic mediator levels were compared. RESULTS: Neither tryptase nor leukotriene E4 levels in nasal fluid correlated with serum tryptase or urinary leukotriene E4 levels at baseline or during reactions. We observed no association between the baseline or aspirin-induced change in nasal versus urinary leukotriene E4 and serum tryptase levels. Body mass index inversely correlated with baseline and aspirin-induced urinary leukotriene E4, prostaglandin D2 metabolite, and serum tryptase levels, as well as with aspirin-induced symptoms and respiratory function, but not with nasal mediators. CONCLUSIONS: The levels of nasal and systemic aspirin-induced mast cell products are discordant in aspirin-exacerbated respiratory disease. Systemically detected levels are likely derived from mast cells outside of the sinonasal cavity and do not accurately reflect upper respiratory tract production. Increased body mass index decreases systemic mast cell mediator production and reaction severity, supporting a contribution of metabolic regulation in aspirin-induced systemic reactions.

Effectiveness of Booster and Influenza Vaccines against COVID-19 among Healthcare Workers, Taiwan.

Among previously uninfected healthcare workers in Taiwan, mRNA COVID-19 booster vaccine was associated with lower odds of COVID-19 after primary recombinant vaccine. Symptom-triggered testing revealed that tetravalent influenza vaccine was associated with higher odds of SARS-CoV-2 infection. COVID-19 vaccination continues to be most effective against SARS-CoV-2.

COX Inhibition Increases Alternaria-Induced Pulmonary Group 2 Innate Lymphoid Cell Responses and IL-33 Release in Mice.

The cyclooxygenase (COX) metabolic pathway regulates immune responses and inflammation. The effect of the COX pathway on innate pulmonary inflammation induced by protease-containing fungal allergens, such as Alternaria alternata, is not fully defined. In this study, we tested the hypothesis that COX inhibition augments Alternaria-induced pulmonary group 2 innate lymphoid cell (ILC2) responses and IL-33 release. Mice were treated with the COX inhibitors indomethacin, flurbiprofen, or vehicle and challenged intranasally with Alternaria extract for four consecutive days to induce innate lung inflammation. We found that indomethacin and flurbiprofen significantly increased the numbers of ILC2 and IL-5 and IL-13 expression by ILC2 in the lung. Indomethacin also increased ILC2 proliferation, the percentages of eosinophils, and mucus production in the lung. Both indomethacin and flurbiprofen augmented the release of IL-33 in bronchoalveolar lavage fluid after Alternaria challenge, suggesting that more IL-33 was available for ILC2 activation and that a COX product(s) inhibited IL-33 release. This is supported by the in vitro finding that the COX product PGE2 and the PGI2 analogs cicaprost decreased Alternaria extract-induced IL-33 release by human bronchial epithelial cells. Although contrasting effects of PGD2, PGE2, and PGI2 on ILC2 responses have been previously reported, the overall effect of the COX pathway on ILC2 function is inhibitory in Alternaria-induced innate airway inflammation.

Association between asthma status and prenatal antibiotic prescription fills among women in a Medicaid population.

OBJECTIVE: Pregnant women with asthma have increased frequency of respiratory viral infections and exacerbations. Because of these risks, women with asthma may be subject to increased surveillance during pregnancy and may, therefore, be at increased risk of antibiotic receipt. The objective of this study was to assess the relationship between maternal asthma and outpatient prenatal antibiotic prescription fills to inform antibiotic stewardship. METHODS: We included women who delivered a singleton, term, non-low birthweight, and otherwise healthy infant enrolled in the Tennessee Medicaid Program. Maternal asthma and prenatal antibiotic fills were ascertained from healthcare encounters and outpatient pharmacy claims. We examined the association between maternal asthma and prenatal antibiotic fills using modified Poisson regression. RESULTS: Our study population included 168354 pregnant women, 4% of whom had asthma. Women with asthma had an increased risk of filling at least one prenatal antibiotic prescription (adjusted risk ratio [aRR] 1.27, 95% confidence interval [CI] 1.25-1.28) and had an increased number of fills during pregnancy (aRR 1.54, 95% CI 1.51-1.57) compared to women without asthma. Among those who filled at least one antibiotic prescription, women with asthma had earlier first prenatal antibiotic prescription fill and increased likelihood of filling at least one course of broad-spectrum antibiotics during pregnancy (versus narrow-spectrum). CONCLUSIONS: Pregnant women with asthma had more outpatient antibiotic prescription fills than pregnant women without asthma. These findings highlight that pregnant women with asthma disproportionately fill more antibiotic prescriptions during pregnancy, providing data that may inform antibiotic stewardship.

Dose, Timing, and Spectrum of Prenatal Antibiotic Exposure and Risk of Childhood Asthma.

BACKGROUND: The potential for prenatal antibiotic exposure to influence asthma risk is not clear. We aimed to determine the effect of timing, dose, and spectrum of prenatal antibiotic exposure on the risk of childhood asthma. METHODS: We conducted a population-based cohort study of 84 214 mother-child dyads to examine the association of prenatal antibiotic exposure and childhood asthma using multivariable logistic regression models. RESULTS: Sixty-four percent of pregnant women received antibiotics. Prenatal antibiotic exposure was associated dose-dependently with increased odds of childhood asthma (adjusted odds ratio [aOR] for interquartile increase of 2 courses [interquartile range, 0-2], 1.26 [95% confidence interval {CI}, 1.20-1.33]). Among children exposed to at least 1 course in utero, the effect of timing at the first course was moderated by total maternal courses. Among pregnant women receiving a single antibiotic course, timing of exposure had no effect on childhood asthma risk. Among women receiving > 1 course, early exposure of the first course was associated with greater childhood asthma risk. Compared to narrow spectrum-only antibiotic use, broad spectrum-only antibiotic exposure was associated with increased odds of asthma (aOR, 1.14 [95% CI, 1.05-1.24]). There were effect modifications (P < .001) by maternal asthma on total courses, and on timing of the first course, significant only among those without maternal asthma. CONCLUSIONS: Increased cumulative dose, early pregnancy first course, and broad-spectrum antibiotic exposure were associated with childhood asthma risk. Our study provides important evidence supporting judicious prenatal antibiotic use, particularly timing of use and choice of antibiotics, in preventing subsequent childhood asthma.

Small airway determinants of airflow limitation in chronic obstructive pulmonary disease.

BACKGROUND: Although a variety of pathological changes have been described in small airways of patients with COPD, the critical anatomic features determining airflow limitation remain incompletely characterised. METHODS: We examined lung tissue specimens from 18 non-smokers without chronic lung disease and 55 former smokers with COPD for pathological features of small airways that could contribute to airflow limitation. Morphometric evaluation was performed for epithelial and subepithelial tissue thickness, collagen and elastin content, luminal mucus and radial alveolar attachments. Immune/inflammatory cells were enumerated in airway walls. Quantitative emphysema scoring was performed on chest CT scans. RESULTS: Small airways from patients with COPD showed thickening of epithelial and subepithelial tissue, mucus plugging and reduced collagen density in the airway wall (in severe COPD). In patients with COPD, we also observed a striking loss of alveolar attachments, which are connective tissue septa that insert radially into the small airway adventitia. While each of these parameters correlated with reduced airflow (FEV1), multivariable regression analysis indicated that loss of alveolar attachments was the major determinant of airflow limitation related to small airways. Neutrophilic infiltration of airway walls and collagen degradation in airway adventitia correlated with loss of alveolar attachments. In addition, quantitative analysis of CT scans identified an association between the extent of emphysema and loss of alveolar attachments. CONCLUSION: In COPD, loss of radial alveolar attachments in small airways is the pathological feature most closely related to airflow limitation. Destruction of alveolar attachments may be mediated by neutrophilic inflammation.

Week-by-week alcohol consumption in early pregnancy and spontaneous abortion risk: a prospective cohort study.

BACKGROUND: Half of women use alcohol in the first weeks of gestation, but most stop once pregnancy is detected. The relationship between timing of alcohol use cessation in early pregnancy and spontaneous abortion risk has not been determined. OBJECTIVE: This study aimed to evaluate the association between week-by-week alcohol consumption in early pregnancy and spontaneous abortion. STUDY DESIGN: Participants in Right from the Start, a community-based prospective pregnancy cohort, were recruited from 8 metropolitan areas in the United States (2000-2012). In the first trimester, participants provided information about alcohol consumed in the prior 4 months, including whether they altered alcohol use; date of change in use; and frequency, amount, and type of alcohol consumed before and after change. We assessed the association between spontaneous abortion and week of alcohol use, cumulative weeks exposed, number of drinks per week, beverage type, and binge drinking. RESULTS: Among 5353 participants, 49.7% reported using alcohol during early pregnancy and 12.0% miscarried. Median gestational age at change in alcohol use was 29 days (interquartile range, 15-35 days). Alcohol use during weeks 5 through 10 from last menstrual period was associated with increased spontaneous abortion risk, with risk peaking for use in week 9. Each successive week of alcohol use was associated with an 8% increase in spontaneous abortion relative to those who did not drink (adjusted hazard ratio, 1.08; 95% confidence interval, 1.04-1.12). This risk is cumulative. In addition, risk was not related to number of drinks per week, beverage type, or binge drinking. CONCLUSION: Each additional week of alcohol exposure during the first trimester increases risk of spontaneous abortion, even at low levels of consumption and when excluding binge drinking.

Development and Progression of Radiologic Abnormalities in Individuals at Risk for Familial Interstitial Lung Disease.

Rationale: The preclinical natural history of progressive lung fibrosis is poorly understood.Objectives: Our goals were to identify risk factors for interstitial lung abnormalities (ILA) on high-resolution computed tomography (HRCT) scans and to determine progression toward clinical interstitial lung disease (ILD) among subjects in a longitudinal cohort of self-reported unaffected first-degree relatives of patients with familial interstitial pneumonia.Methods: Enrollment evaluation included a health history and exposure questionnaire and HRCT scans, which were categorized by visual assessment as no ILA, early/mild ILA, or extensive ILA. The study endpoint was met when ILA were extensive or when ILD was diagnosed clinically. Among subjects with adequate study time to complete 5-year follow-up HRCT, the proportion with ILD events (endpoint met or radiographic ILA progression) was calculated.Measurements and Main Results: Among 336 subjects, the mean age was 53.1 (SD, 9.9) years. Those with ILA (early/mild [n = 74] or extensive [n = 3]) were older, were more likely to be ever smokers, had shorter peripheral blood mononuclear cell telomeres, and were more likely to carry the MUC5B risk allele. Self-reported occupational or environmental exposures, including aluminum smelting, lead, birds, and mold, were independently associated with ILA. Among 129 subjects with sufficient study time, 25 (19.4%) had an ILD event by 5 years after enrollment; of these, 12 met the study endpoint and another 13 had radiologic progression of ILA. ILD events were more common among those with early/mild ILA at enrollment (63.3% vs. 6.1%; P < 0.0001).Conclusions: Rare and common environmental exposures are independent risk factors for radiologic abnormalities. In 5 years, progression of ILA occurred in most individuals with early ILA detected at enrollment.

Infant Respiratory Syncytial Virus Bronchiolitis and Subsequent Risk of Pneumonia, Otitis Media, and Antibiotic Utilization.

Infant respiratory syncytial virus (RSV) bronchiolitis in the first 6 months of life was associated with increased odds of pneumonia, otitis media, and antibiotic prescription fills in the second 6 months of life. These data suggest a potential value of future RSV vaccination programs on subsequent respiratory health.

Dose, Timing, and Type of Infant Antibiotic Use and the Risk of Childhood Asthma.

BACKGROUND: Aspects of infant antibiotic exposure and its association with asthma development have been variably explored. We aimed to evaluate comprehensively and simultaneously the impact of dose, timing, and type of infant antibiotic use on the risk of childhood asthma. METHODS: Singleton, term-birth, non-low-birth-weight, and otherwise healthy children enrolled in the Tennessee Medicaid Program were included. Infant antibiotic use and childhood asthma diagnosis were ascertained from prescription fills and healthcare encounter claims. We examined the association using multivariable logistic regression models. RESULTS: Among 152 622 children, 79% had at least 1 antibiotic prescription fill during infancy. Infant antibiotic use was associated with increased odds of childhood asthma in a dose-dependent manner, with a 20% increase in odds (adjusted odds ratio [aOR], 1.20 [95% confidence interval {CI}, 1.19-1.20]) for each additional antibiotic prescription filled. This significant dose-dependent relationship persisted after additionally controlling for timing and type of the antibiotics. Infants who had broad-spectrum-only antibiotic fills had increased odds of developing asthma compared with infants who had narrow-spectrum-only fills (aOR, 1.10 [95% CI, 1.05-1.19]). There was no significant association between timing, formulation, anaerobic coverage, and class of antibiotics and childhood asthma. CONCLUSIONS: We found a consistent dose-dependent association between antibiotic prescription fills during infancy and subsequent development of childhood asthma. Our study adds important insights into specific aspects of infant antibiotic exposure. Clinical decision making regarding antibiotic stewardship and prevention of adverse effects should be critically assessed prior to use during infancy.

Gestational Age at Arrest of Development: An Alternative Approach for Assigning Time at Risk in Studies of Time-Varying Exposures and Miscarriage.

The time between arrest of pregnancy development and miscarriage represents a window in which the pregnancy is nonviable and not developing. In effect, the pregnancy loss has already occurred, and additional exposure cannot influence its outcome. However, epidemiologic studies of miscarriage traditionally use gestational age at miscarriage (GAM) to assign time in survival analyses, which overestimates duration of exposure and time at risk. In Right From the Start, a pregnancy cohort study (2000-2012), we characterized the gap between estimated gestational age at arrest of development (GAAD) and miscarriage using transvaginal ultrasound in 500 women recruited from 3 states (North Carolina, Tennessee, and Texas). We compared effect estimates from models using GAAD with GAM to assign time at risk through a simulation study of several exposure patterns with varying effect sizes. The median gap between GAAD and miscarriage was 23 days (interquartile range, 15-32). Use of GAAD decreased the bias and variance of the estimated association for time-varying exposures, whereas half the time using GAM led to estimates that differed from the true effect by more than 20%. Using GAAD to assign time at risk should result in more accurate and consistent characterization of miscarriage risk associated with time-varying exposures.

Estimating seasonal onsets and peaks of bronchiolitis with spatially and temporally uncertain data.

RSV bronchiolitis (an acute lower respiratory tract viral infection in infants) is the most common cause of infant hospitalizations in the United States (US). The only preventive intervention currently available is monthly injections of immunoprophylaxis. However, this treatment is expensive and needs to be administered simultaneously with seasonal bronchiolitis cycles in order to be effective. To increase our understanding of bronchiolitis timing, this research focuses on identifying seasonal bronchiolitis cycles (start times, peaks, and declinations) throughout the continental US using data on infant bronchiolitis cases from the US Military Health System Data Repository. Because this data involved highly personal information, the bronchiolitis dates in the dataset were "jittered" in the sense that the recorded dates were randomized within a time window of the true date. Hence, we develop a statistical change point model that estimates spatially varying seasonal bronchiolitis cycles while accounting for the purposefully introduced jittering in the data. Additionally, by including temperature and humidity data as regressors, we identify a relationship between bronchiolitis seasonality and climate. We found that, in general, bronchiolitis seasons begin earlier and are longer in the southeastern states compared to the western states with peak times lasting approximately 1 month nationwide.

Effectiveness of Respiratory Syncytial Virus Immunoprophylaxis in Reducing Bronchiolitis Hospitalizations Among High-Risk Infants.

We sought to determine the real-world effectiveness of respiratory syncytial virus (RSV) immunoprophylaxis in a population-based cohort to inform policy. The study population included infants born during 1996-2008 and enrolled in the Kaiser Permanente Northern California integrated health-care delivery system. During the RSV season (November-March), the date of RSV immunoprophylaxis administration and the following 30 days were defined as RSV immunoprophylaxis protected period(s), and all other days were defined as unprotected period(s). Numbers of bronchiolitis hospitalizations were determined using International Classification of Diseases, Ninth Revision, codes during RSV season. We used a proportional hazards model to estimate risk of bronchiolitis hospitalization when comparing infants' protected period(s) with unprotected period(s). Infants who had ever received RSV immunoprophylaxis had a 32% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.68, 95% confidence interval: 0.46, 1.00) when protected periods were compared with unprotected periods. Infants with chronic lung disease (CLD) had a 52% decreased risk of bronchiolitis hospitalization (adjusted hazard ratio = 0.48, 95% confidence interval: 0.25, 0.94) when protected periods were compared with unprotected periods. Under the new 2014 American Academy of Pediatrics (AAP) guidelines, 48% of infants eligible for RSV immunoprophylaxis on the basis of AAP guidelines in place at birth would no longer be eligible, but nearly all infants with CLD would remain eligible. RSV immunoprophylaxis is effective in decreasing hospitalization. This association is greatest for infants with CLD, a group still recommended for receipt of RSV immunoprophylaxis under the new AAP guidelines.

Effects of Triple-Mutated Hypoxia-Inducible Factor-1α on Angiogenesis and Cardiac Function Improvement in Rats with Myocardial Infarction.

BACKGROUND/AIMS: The effects of hypoxia-inducible factor-1α (HIF-1α) on angiogenesis and cardiac function improvement in rats with myocardial infarction (MI) is unknown and our current study was to evaluate whether HIF-1α would be beneficial for angiogenesis and cardiac function improvement in MI rats. METHODS: A mutant of adenovirus HIF-1α (Ad-HIF-1α-Trip) was constructed by three sites mutation (Pro402, Pro564 and Asn803) in HIF-1α. The rat MI model was produced by permanent ligation of left anterior descending artery and 1×109 PFU adenovirus (Ad) vector particles of Ad-Null, Ad- HIF-1a-564/402, Ad- HIF-1a-Trip, 250ng vascular endothelial growth factor (VEGF) in 0.5ml saline or only 0.5 ml saline were injected intramuscularly around the infarct border zone. Real-time PCR, ELISA and western blotting were used to evaluate angiogenesis factors expression. Capillary density and necrotic areas were detected by immunohistochemistry staining and TTC staining, respectively. Cardiac function assessment was done by echocardiography before operation and on day 7, 14 and 28 after MI. Blood samples were drawn for the measurement of cardiac biomarkers, liver function and kidney function. RESULTS: On day 7, compared to the other groups, the expressions of HIF-1α and angiogenesis factors, and the capillary density were all significantly higher in the Ad-HIF-1α-Trip group. However, on day 28, no significant between-group differences were observed. After 72 hours of MI, serum level of cardiac biomarkers and the necrotic areas were significantly lower in the Ad-HIF-1a-Trip group compared to the other groups. Echocardiography showed that on day 7, cardiac functions were significantly reduced in all groups compared to the baseline. Cardiac function in the Ad-HIF-1α-Trip group was decreased less profoundly through day 7 to day 28 compared to the other groups. Importantly, no significant differences in liver and renal function were observed. CONCLUSION: Mutation of Pro402, Pro564 and Asn803 are beneficial for enhancement of the efficacy of HIF-1α. Ad-HIF-1α-Trip is able to improve angiogenesis and cardiac function, which may be a promising avenue for treatment of ischemic heart disease in the future.

Prostaglandin I2 Suppresses Proinflammatory Chemokine Expression, CD4 T Cell Activation, and STAT6-Independent Allergic Lung Inflammation.

Allergic airway diseases are immune disorders associated with heightened type 2 immune responses and IL-5 and IL-13 production at the site of inflammation. We have previously reported that cyclooxygenase (COX) inhibition by indomethacin augmented allergic airway inflammation in a STAT6-independent manner. However, the key COX product(s) responsible for restraining indomethacin-mediated STAT6-independent allergic inflammation is unknown. In this study, using the mouse model of OVA-induced allergic airway inflammation, we identified that PGI2 receptor (IP) signaling was critical for indomethacin-induced, STAT6-independent proallergic effects. We demonstrated that IP deficiency increased inflammatory cell infiltration, eosinophilia, and IL-5 and IL-13 expression in the lung in a STAT6-independent manner. The augmented STAT6-independent allergic inflammation correlated with enhanced primary immune responses to allergic sensitization and elevated production of multiple inflammatory chemokines (CCL11, CCL17, CCL22, and CXCL12) in the lung after allergen challenge. We also showed that the PGI2 analogue cicaprost inhibited CD4 T cell proliferation and IL-5 and IL-13 expression in vitro, and IP deficiency diminished the stimulatory effect of indomethacin on STAT6-independent IL-5 and IL-13 responses in vivo. The inhibitory effects of PGI2 and the IP signaling pathway on CD4 T cell activation, inflammatory chemokine production, and allergic sensitization and airway inflammation suggest that PGI2 and its analogue iloprost, both Food and Drug Administration-approved drugs, may be useful in treating allergic diseases and asthma. In addition, inhibiting PGI2 signaling by drugs that either block PGI2 production or restrain IP signaling may augment STAT6-independent pathways of allergic inflammation.