Long-COVID improves in 50% of patients after a year in a Midwestern cohort.

Background: Many of those infected with COVID-19 experience long-term disability due to persistent symptoms known as Long-COVID, which include ongoing respiratory issues, loss of taste and smell, and impaired daily functioning. Research Question: This study aims to better understand the chronology of long-COVID symptoms. Study Design and Methods: We prospectively enrolled 403 adults from the University of Iowa long-COVID clinic (June 2020 to February 2022). Participants provided symptom data during acute illness, symptom progression, and other clinical characteristics. Patients in this registry received a survey containing questions including current symptoms and status since long-COVID diagnosis (sliding status scale, PHQ2, GAD2, MMRC). Those >12 months since acute-COVID diagnosis had chart review done to track their symptomology. Results: Of 403 participants contacted, 129 (32%) responded. The mean age (in years) was 50.17 +/-14.28, with 31.8% male and 68.2% female. Severity of acute covid treatment was stratified by treatment in the outpatient (70.5%), inpatient (16.3%), or ICU (13.2%) settings. 51.2% reported subjective improvement (sliding scale scores of 67-100) since long-COVID onset. Ages 18-29 reported significantly higher subjective status scores. Subjective status scores were unaffected by severity. 102 respondents were >12 months from their initial COVID-19 diagnosis and were tracked for longitudinal symptom persistence. All symptoms tracked had variance (mean fraction 0.58, range 0.34-0.75) in the reported symptoms at the time of long-COVID presentation when compared with patient survey report. 48 reported persistent dyspnea, 23 (48%) had resolved it at time of survey. For fatigue, 44 had persistence, 12 (27%) resolved. Interpretation: Overall, 51.2% respondents improved since their long-COVID began. Pulmonary symptoms were more persistent than neuromuscular symptoms (anosmia, dysgeusia, myalgias). Gender, time since acute COVID infection, and its severity didn't affect subjective status or symptoms. This study highlights recall bias that may be prevalent in other long-COVID research reliant on participant memory.

Gene-based association study of rare variants in children of diverse ancestries implicates TNFRSF21 in the development of allergic asthma.

BACKGROUND: Most genetic studies of asthma and allergy have focused on common variation in individuals primarily of European ancestry. Studying the role of rare variation in quantitative phenotypes and in asthma phenotypes in populations of diverse ancestries can provide additional, important insights into the development of these traits. OBJECTIVE: We sought to examine the contribution of rare variants to different asthma- or allergy-associated quantitative traits in children with diverse ancestries and explore their role in asthma phenotypes. METHODS: We examined whole-genome sequencing data from children participants in longitudinal studies of asthma (n = 1035; parent-identified as 67% Black and 25% Hispanic) to identify rare variants (minor allele frequency < 0.01). We assigned variants to genes and tested for associations using an omnibus variant-set test between each of 24,902 genes and 8 asthma-associated quantitative traits. On combining our results with external data on predicted gene expression in humans and mouse knockout studies, we identified 3 candidate genes. A burden of rare variants in each gene and in a combined 3-gene score was tested for its associations with clinical phenotypes of asthma. Finally, published single-cell gene expression data in lower airway mucosal cells after allergen challenge were used to assess transcriptional responses to allergen. RESULTS: Rare variants in USF1 were significantly associated with blood neutrophil count (P = 2.18 × 10-7); rare variants in TNFRSF21 with total IgE (P = 6.47 × 10-6) and PIK3R6 with eosinophil count (P = 4.10 × 10-5) reached suggestive significance. These 3 findings were supported by independent data from human and mouse studies. A burden of rare variants in TNFRSF21 and in a 3-gene score was associated with allergy-related phenotypes in cohorts of children with mild and severe asthma. Furthermore, TNFRSF21 was significantly upregulated in bronchial basal epithelial cells from adults with allergic asthma but not in adults with allergies (but not asthma) after allergen challenge. CONCLUSIONS: We report novel associations between rare variants in genes and allergic and inflammatory phenotypes in children with diverse ancestries, highlighting TNFRSF21 as contributing to the development of allergic asthma.

Tobacco smoke exposure recruits inflammatory airspace monocytes that establish permissive lung niches for Mycobacterium tuberculosis.

Tobacco smoking doubles the risk of active tuberculosis (TB) and accounts for up to 20% of all active TB cases globally. How smoking promotes lung microenvironments permissive to Mycobacterium tuberculosis (Mtb) growth remains incompletely understood. We investigated primary bronchoalveolar lavage cells from current and never smokers by performing single-cell RNA sequencing (scRNA-seq), flow cytometry, and functional assays. We observed the enrichment of immature inflammatory monocytes in the lungs of smokers compared with nonsmokers. These monocytes exhibited phenotypes consistent with recent recruitment from blood, ongoing differentiation, increased activation, and states similar to those with chronic obstructive pulmonary disease. Using integrative scRNA-seq and flow cytometry, we identified CD93 as a marker for a subset of these newly recruited smoking-associated lung monocytes and further provided evidence that the recruitment of monocytes into the lung was mediated by CCR2-binding chemokines, including CCL11. We also show that these cells exhibit elevated inflammatory responses upon exposure to Mtb and accelerated intracellular growth of Mtb compared with mature macrophages. This elevated Mtb growth could be inhibited by anti-inflammatory small molecules, providing a connection between smoking-induced pro-inflammatory states and permissiveness to Mtb growth. Our findings suggest a model in which smoking leads to the recruitment of immature inflammatory monocytes from the periphery to the lung, which results in the accumulation of these Mtb-permissive cells in the airway. This work defines how smoking may lead to increased susceptibility to Mtb and identifies host-directed therapies to reduce the burden of TB among those who smoke.

Sex Differences in Oxidative Stress-Mediated Reductions in Microvascular Endothelial Function in Young Adult e-Cigarette Users.

BACKGROUND: Chronic electronic-cigarette (EC) use is reported to decrease vascular endothelial function. However, the mechanism(s) mediating this reduction remain unclear. In this study, we examined endothelium- and NO-dependent dilation, and the role of oxidative stress in attenuating these responses, in healthy young EC users (n=20, 10 males/10 females) compared with healthy controls (n=20, 10 males/10 females). We hypothesized that EC would have reduced endothelium- and NO-dependent dilation and administration of the superoxide scavenger tempol would increase these responses in EC. We further hypothesized that female EC would have the greatest reductions in endothelium- and NO-dependent dilation. METHODS: We assessed microvascular endothelium-dependent vasodilator function in vivo by measurement of cutaneous vascular conductance (%CVCmax) responses to a standardized local heating protocol in control and 10 µM tempol-treated sites. After full expression of the local heating response, 15 mM NG-nitro-L-arginine methyl ester (NO synthase inhibition) was perfused. RESULTS: EC had significantly reduced endothelium- (73±15 versus 87±9%CVCmax; P<0.001) and NO-dependent (48±17% versus 62±15%; P=0.011) dilation. Tempol perfusion increased endothelium-dependent (84±12%CVCmax P=0.01) and NO-dependent (63±14% P=0.005) dilation in EC but had no effect in healthy control. Within female sex, EC had lower endothelium-dependent (71±13 versus 89±7%CVCmax; P=0.002) and NO-dependent (50±6 versus 69±11%; P=0.005) dilation compared with healthy control, and tempol augmented endothelium-dependent (83±13%CVCmax; P=0.002) and NO-dependent (62±13%; P=0.015) dilation. There were no group or treatment differences within male sex. CONCLUSION: Healthy young adult EC users have reduced microvascular endothelium-dependent and NO-dependent dilation, driven by greater reductions in female EC users, and mediated in part by superoxide.

A human model of asthma exacerbation reveals transcriptional programs and cell circuits specific to allergic asthma.

Asthma is a chronic disease most commonly associated with allergy and type 2 inflammation. However, the mechanisms that link airway inflammation to the structural changes that define asthma are incompletely understood. Using a human model of allergen-induced asthma exacerbation, we compared the lower airway mucosa in allergic asthmatics and allergic non-asthmatic controls using single-cell RNA sequencing. In response to allergen, the asthmatic airway epithelium was highly dynamic and up-regulated genes involved in matrix degradation, mucus metaplasia, and glycolysis while failing to induce injury-repair and antioxidant pathways observed in controls. IL9-expressing pathogenic TH2 cells were specific to asthmatic airways and were only observed after allergen challenge. Additionally, conventional type 2 dendritic cells (DC2 that express CD1C) and CCR2-expressing monocyte-derived cells (MCs) were uniquely enriched in asthmatics after allergen, with up-regulation of genes that sustain type 2 inflammation and promote pathologic airway remodeling. In contrast, allergic controls were enriched for macrophage-like MCs that up-regulated tissue repair programs after allergen challenge, suggesting that these populations may protect against asthmatic airway remodeling. Cellular interaction analyses revealed a TH2-mononuclear phagocyte-basal cell interactome unique to asthmatics. These pathogenic cellular circuits were characterized by type 2 programming of immune and structural cells and additional pathways that may sustain and amplify type 2 signals, including TNF family signaling, altered cellular metabolism, failure to engage antioxidant responses, and loss of growth factor signaling. Our findings therefore suggest that pathogenic effector circuits and the absence of proresolution programs drive structural airway disease in response to type 2 inflammation.

Advancing Lung Immunology Research: An Official American Thoracic Society Workshop Report.

The mammalian airways and lungs are exposed to a myriad of inhaled particulate matter, allergens, and pathogens. The immune system plays an essential role in protecting the host from respiratory pathogens, but a dysregulated immune response during respiratory infection can impair pathogen clearance and lead to immunopathology. Furthermore, inappropriate immunity to inhaled antigens can lead to pulmonary diseases. A complex network of epithelial, neural, stromal, and immune cells has evolved to sense and respond to inhaled antigens, including the decision to promote tolerance versus a rapid, robust, and targeted immune response. Although there has been great progress in understanding the mechanisms governing immunity to respiratory pathogens and aeroantigens, we are only beginning to develop an integrated understanding of the cellular networks governing tissue immunity within the lungs and how it changes after inflammation and over the human life course. An integrated model of airway and lung immunity will be necessary to improve mucosal vaccine design as well as prevent and treat acute and chronic inflammatory pulmonary diseases. Given the importance of immunology in pulmonary research, the American Thoracic Society convened a working group to highlight central areas of investigation to advance the science of lung immunology and improve human health.

Quantitative Chest CT Assessment of Small Airways Disease in Post-Acute SARS-CoV-2 Infection.

Background The long-term effects of SARS-CoV-2 infection on pulmonary structure and function remain incompletely characterized. Purpose To test whether SARS-CoV-2 infection leads to small airways disease in patients with persistent symptoms. Materials and Methods In this single-center study at a university teaching hospital, adults with confirmed COVID-19 who remained symptomatic more than 30 days following diagnosis were prospectively enrolled from June to December 2020 and compared with healthy participants (controls) prospectively enrolled from March to August 2018. Participants with post-acute sequelae of COVID-19 (PASC) were classified as ambulatory, hospitalized, or having required the intensive care unit (ICU) based on the highest level of care received during acute infection. Symptoms, pulmonary function tests, and chest CT images were collected. Quantitative CT analysis was performed using supervised machine learning to measure regional ground-glass opacity (GGO) and using inspiratory and expiratory image-matching to measure regional air trapping. Univariable analyses and multivariable linear regression were used to compare groups. Results Overall, 100 participants with PASC (median age, 48 years; 66 women) were evaluated and compared with 106 matched healthy controls; 67% (67 of 100) of the participants with PASC were classified as ambulatory, 17% (17 of 100) were hospitalized, and 16% (16 of 100) required the ICU. In the hospitalized and ICU groups, the mean percentage of total lung classified as GGO was 13.2% and 28.7%, respectively, and was higher than that in the ambulatory group (3.7%, P < .001 for both comparisons). The mean percentage of total lung affected by air trapping was 25.4%, 34.6%, and 27.3% in the ambulatory, hospitalized, and ICU groups, respectively, and 7.2% in healthy controls (P < .001). Air trapping correlated with the residual volume-to-total lung capacity ratio (ρ = 0.6, P < .001). Conclusion In survivors of COVID-19, small airways disease occurred independently of initial infection severity. The long-term consequences are unknown. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Elicker in this issue.

ATS Core Curriculum 2021. Adult Pulmonary Medicine: Thoracic Oncology.

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine at the annual international conference. The 2021 Pulmonary Core Curriculum focuses on lung cancer and include risks and prevention, screening, nodules, therapeutics and associated pulmonary toxicities, and malignant pleural effusions. Although tobacco smoking remains the primary risk factor for developing lung cancer, exposure to other environmental and occupational substances, including asbestos, radon, and burned biomass, contribute to the global burden of disease. Randomized studies have demonstrated that routine screening of high-risk smokers with low-dose chest computed tomography results in detection at an earlier stage and reduction in lung cancer mortality. On the basis of these trials and other lung cancer risk tools, screening recommendations have been developed. When evaluating lung nodules, clinical and radiographic features are used to estimate the probability of cancer. Management guidelines take into account the nodule size and cancer risk estimates to provide recommendations at evaluation. Newer lung cancer therapies, including immune checkpoint inhibitors and molecular therapies, cause pulmonary toxicity more frequently than conventional chemotherapy. Treatment-related toxicity should be suspected in patients receiving these medications who present with respiratory symptoms. Evaluation is aimed at excluding other etiologies, and treatment is based on the severity of symptoms. Malignant pleural effusions can be debilitating. The diagnosis is made by using simple pleural drainage and/or pleural biopsies. Management depends on the clinical scenario and the patient's preferences and includes the use of serial thoracentesis, a tunneled pleural catheter, or pleurodesis.

Soluble Suppression of Tumorigenicity-2 Associates With Ventilator Dependence in Coronavirus Disease 2019 Respiratory Failure.

OBJECTIVES: We hypothesize that elevated soluble suppression of tumorigenicity-2 concentrations, a marker of pulmonary epithelial injury, reflect ongoing lung injury in acute hypoxemic respiratory failure due to coronavirus disease 2019 and associate with continued ventilator dependence. DESIGN: We associated serial plasma soluble suppression of tumorigenicity-2 levels and markers of systemic inflammation including d-dimer, C-reactive protein, and erythrocyte sedimentation rate with 30-day mortality and ventilator dependence. SETTING: Adult medical ICUs and general medicine wards at an academic teaching hospital in Boston, MA. PATIENTS: Adult patients with severe acute respiratory syndrome coronavirus 2 infection and acute hypoxemic respiratory failure admitted to the ICU (n = 72) and non-ICU patients managed with supplemental oxygen (n = 77). INTERVENTIONS: Observational study from April 25 to June 25, 2020. MEASUREMENTS AND MAIN RESULTS: ICU patients had a higher baseline body mass index and median soluble suppression of tumorigenicity-2, d-dimer, and C-reactive protein concentrations compared with non-ICU patients. Among ICU patients, elevated baseline modified Sequential Organ Failure Assessment score and log (soluble suppression of tumorigenicity-2) were associated with 30-day mortality, whereas initial Pao2/Fio2 and markers of systemic inflammation were similar between groups. Only log (soluble suppression of tumorigenicity-2) associated with ventilator dependence over time, with the last measured log (soluble suppression of tumorigenicity-2) concentration obtained on ICU day 11.5 (interquartile range [7-17]) higher in patients who required reintubation or tracheostomy placement compared with patients who were successfully extubated (2.10 [1.89-2.26] vs 1.87 ng/mL [1.72-2.13 ng/mL]; p = 0.03). Last measured systemic inflammatory markers, modified Sequential Organ Failure Assessment score, and Pao2/Fio2 were not different between patients who were successfully extubated compared with those with continued ventilator dependence. CONCLUSIONS: Plasma soluble suppression of tumorigenicity-2 is a biomarker readily measured in blood that can provide dynamic information about the degree of a patient's lung injury and real-time assessment of the likelihood of extubation success. Measures of systemic inflammation, illness severity, and oxygenation did not associate with ventilator outcomes.

Smoking and Human Immunodeficiency Virus 1 Infection Promote Retention of CD8+ T Cells in the Airway Mucosa.

Smoking and human immunodeficiency virus 1 (HIV-1) infection are risk factors for chronic obstructive pulmonary disease (COPD), which is among the most common comorbid conditions in people living with HIV-1. HIV-1 infection leads to persistent expansion of CD8+ T cells, and CD8+ T cell-mediated inflammation has been implicated in COPD pathogenesis. In this study, we investigated the effects of HIV-1 infection and smoking on T-cell dynamics in patients at risk of COPD. BAL fluid, endobronchial brushings, and blood from HIV-1 infected and uninfected nonsmokers and smokers were analyzed by flow cytometry, and lungs were imaged by computed tomography. Chemokines were measured in BAL fluid, and CD8+ T-cell chemotaxis in the presence of cigarette smoke extract was assessed in vitro. HIV-1 infection increased CD8+ T cells in the BAL fluid, but this increase was abrogated by smoking. Smokers had reduced BAL fluid concentrations of the T cell-recruiting chemokines CXCL10 and CCL5, and cigarette smoke extract inhibited CXCL10 and CCL5 production by macrophages and CD8+ T-cell transmigration in vitro. In contrast to the T cells in BAL fluid, CD8+ T cells in endobronchial brushings were increased in HIV-1-infected smokers, which was driven by an accumulation of effector memory T cells in the airway mucosa and an increase in tissue-resident memory T cells. Mucosal CD8+ T-cell numbers inversely correlated with lung aeration, suggesting an association with inflammation and remodeling. HIV-1 infection and smoking lead to retention of CD8+ T cells within the airway mucosa.

T cell-tropic HIV efficiently infects alveolar macrophages through contact with infected CD4+ T cells.

Alveolar macrophages (AMs) are critical for defense against airborne pathogens and AM dysfunction is thought to contribute to the increased burden of pulmonary infections observed in individuals living with HIV-1 (HIV). While HIV nucleic acids have been detected in AMs early in infection, circulating HIV during acute and chronic infection is usually CCR5 T cell-tropic (T-tropic) and enters macrophages inefficiently in vitro. The mechanism by which T-tropic viruses infect AMs remains unknown. We collected AMs by bronchoscopy performed in HIV-infected, antiretroviral therapy (ART)-naive and uninfected subjects. We found that viral constructs made with primary HIV envelope sequences isolated from both AMs and plasma were T-tropic and inefficiently infected macrophages. However, these isolates productively infected macrophages when co-cultured with HIV-infected CD4+ T cells. In addition, we provide evidence that T-tropic HIV is transmitted from infected CD4+ T cells to the AM cytosol. We conclude that AM-derived HIV isolates are T-tropic and can enter macrophages through contact with an infected CD4+ T cell, which results in productive infection of AMs. CD4+ T cell-dependent entry of HIV into AMs helps explain the presence of HIV in AMs despite inefficient cell-free infection, and may contribute to AM dysfunction in people living with HIV.

Plasma Soluble Suppression of Tumorigenicity-2 Associates with Ventilator Liberation in Acute Hypoxemic Respiratory Failure.

Rationale: Standard physiologic assessments of extubation readiness in patients with acute hypoxemic respiratory failure (AHRF) may not reflect lung injury resolution and could adversely affect clinical decision-making and patient outcomes. Objectives: We hypothesized that elevations in inflammatory plasma biomarkers sST2 (soluble suppression of tumorigenicity-2) and IL-6 indicate ongoing lung injury in AHRF and better inform patient outcomes compared with standard clinical assessments. Methods: We measured daily plasma biomarkers and physiologic variables in 200 patients with AHRF for up to 9 days after intubation. We tested the associations of baseline values with the primary outcome of unassisted breathing at Day 29. We analyzed the ability of serial biomarker measurements to inform successful ventilator liberation. Measurements and Main Results: Baseline sST2 concentrations were higher in patients dead or mechanically ventilated versus breathing unassisted at Day 29 (491.7 ng/ml [interquartile range (IQR), 294.5-670.1 ng/ml] vs. 314.4 ng/ml [IQR, 127.5-550.1 ng/ml]; P = 0.0003). Higher sST2 concentrations over time were associated with a decreased probability of ventilator liberation (hazard ratio, 0.80 per log-unit increase; 95% confidence interval [CI], 0.75-0.83; P = 0.03). Patients with higher sST2 concentrations on the day of liberation were more likely to fail liberation compared with patients who remained successfully liberated (320.9 ng/ml [IQR, 181.1- 495.6 ng/ml] vs. 161.6 ng/ml [IQR, 95.8-292.5 ng/ml]; P = 0.002). Elevated sST2 concentrations on the day of liberation decreased the odds of successful liberation when adjusted for standard physiologic parameters (odds ratio, 0.325; 95% CI, 0.119-0.885; P = 0.03). IL-6 concentrations did not associate with outcomes. Conclusions: Using sST2 concentrations to guide ventilator management may more accurately reflect underlying lung injury and outperform traditional measures of readiness for ventilator liberation.

PET Imaging Reveals Early Pulmonary Perfusion Abnormalities in HIV Infection Similar to Smoking.

Chronic obstructive pulmonary disease (COPD) is the most common noninfectious pulmonary disease among people living with HIV, independent of smoking. However, the cause for this enhanced susceptibility remains unclear, and the effects of HIV on pulmonary perfusion and ventilation are unknown. Methods: We used PET/CT in 46 smokers and nonsmokers, 23 of whom had documented HIV infection. Emphysema was assessed by CT and perfusion by 13N (13NN) PET scans. After removal of image noise, vertical and axial gradients in perfusion were calculated. We tested for differences in the total spatial heterogeneity of perfusion (CV2Qtotal) and its components (CV2Qtotal = CV2Qvgrad [vertical gradient] + CV2Qzgrad [axial gradient] + CV2Qr [residual heterogeneity]) among groups. Results: There were no significant differences in demographic parameters among groups, and all subjects had minimal radiographic evidence of emphysema. Compared with controls, nonsmokers living with HIV had a significantly greater CV2Qr/CV2Qtotal (0.48 vs. 0.36, P = 0.05) and reduced CV2Qvgrad/CV2Qtotal (0.46 vs. 0.65, P = 0.038). Smokers also had a reduced CV2Qvgrad/CV2Qtotal, however, there was no significant difference in CV2Qvgrad/CV2Qtotal between smokers living with and without HIV (0.39 vs. 0.34, P = 0.58), despite a decreased vertical perfusion gradient (Qvgrad) in smokers living with HIV. Conclusion: In nonsmokers living with well-controlled HIV and minimal radiographic emphysema, HIV infection contributes to pulmonary perfusion abnormalities similar to smokers. These data indicate the onset of subclinical pulmonary perfusion abnormalities that could herald the development of significant lung disease in these susceptible individuals.

Interleukin-33 activates regulatory T cells to suppress innate γδ T cell responses in the lung.

Foxp3+ regulatory T (Treg) cells expressing the interleukin (IL)-33 receptor ST2 mediate tissue repair in response to IL-33. Whether Treg cells also respond to the alarmin IL-33 to regulate specific aspects of the immune response is not known. Here we describe an unexpected function of ST2+ Treg cells in suppressing the innate immune response in the lung to environmental allergens without altering the adaptive immune response. Following allergen exposure, ST2+ Treg cells were activated by IL-33 to suppress IL-17-producing γδ T cells. ST2 signaling in Treg cells induced Ebi3, a component of the heterodimeric cytokine IL-35 that was required for Treg cell-mediated suppression of γδ T cells. This response resulted in fewer eosinophil-attracting chemokines and reduced eosinophil recruitment into the lung, which was beneficial to the host in reducing allergen-induced inflammation. Thus, we define a fundamental role for ST2+ Treg cells in the lung as a negative regulator of the early innate γδ T cell response to mucosal injury.

Quantitative assessment of airway remodelling and response to allergen in asthma.

BACKGROUND AND OBJECTIVE: In vivo evaluation of the microstructural differences between asthmatic and non-asthmatic airways and their functional consequences is relevant to understanding and, potentially, treating asthma. In this study, we use endobronchial optical coherence tomography to investigate how allergic airways with asthma differ from allergic non-asthmatic airways in baseline microstructure and in response to allergen challenge. METHODS: A total of 45 subjects completed the study, including 20 allergic, mildly asthmatic individuals, 22 non-asthmatic allergic controls and 3 healthy controls. A 3-cm airway segment in the right middle and right upper lobe were imaged in each subject immediately before and 24 h following segmental allergen challenge to the right middle lobe. Relationships between optical airway measurements (epithelial and mucosal thicknesses, mucosal buckling and mucus) and airway obstruction (FEV1 /FVC (forced expiratory volume in 1 s/forced vital capacity) and FEV1 % (FEV1 as a percentage of predictive value)) were investigated. RESULTS: Significant increases at baseline and in response to allergen were observed for all four of our imaging metrics in the asthmatic airways compared to the non-asthmatic airways. Epithelial thickness and mucosal buckling exhibited a significant relationship to FEV1 /FVC in the asthmatic group. CONCLUSION: Simultaneous assessments of airway microstructure, buckling and mucus revealed both structural and functional differences between the mildly asthmatic and control groups, with airway buckling seeming to be the most relevant factor. The results of this study demonstrate that a comprehensive, microstructural approach to assessing the airways may be important in future asthma studies as well as in the monitoring and treatment of asthma.

CARMA3 Mediates Allergic Lung Inflammation in Response to Alternaria alternata.

The airway epithelial cell (AEC) response to allergens helps initiate and propagate allergic inflammation in asthma. CARMA3 is a scaffold protein that mediates G protein-coupled receptor-induced NF-κB activation in airway epithelium. In this study, we demonstrate that mice with CARMA3-deficient AECs have reduced airway inflammation, as well as reduced type 2 cytokine levels in response to Alternaria alternata. These mice also have reduced production of IL-33 and IL-25, and reduced numbers of innate lymphoid cells in the lung. We also show that CARMA3-deficient human AECs have decreased production of proasthmatic mediators in response to A. alternata. Finally, we show that CARMA3 interacts with inositol 1,4,5-trisphosphate receptors in AECs, and that inhibition of CARMA3 signaling reduces A. alternata-induced intracellular calcium release. In conclusion, we show that CARMA3 signaling in AECs helps mediate A. alternata-induced allergic airway inflammation, and that CARMA3 is an important signaling molecule for type 2 immune responses in the lung.

Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography.

We propose a novel suite of algorithms for automatically segmenting the airway lumen and mucus in endobronchial optical coherence tomography (OCT) data sets, as well as a novel approach for quantifying the contents of the mucus. Mucus and lumen were segmented using a robust, multi-stage algorithm that requires only minimal input regarding sheath geometry. The algorithm performance was highly accurate in a wide range of airway and noise conditions. Mucus was classified using mean backscattering intensity and grey level co-occurrence matrix (GLCM) statistics. We evaluated our techniques in vivo in asthmatic and non-asthmatic volunteers.

Birefringence microscopy platform for assessing airway smooth muscle structure and function in vivo.

The inability to visualize airway smooth muscle (ASM) cells in vivo is a major obstacle in understanding their role in normal physiology and diseases. At present, there is no imaging modality available to assess ASM in vivo. Confocal endomicroscopy lacks the penetration depth and field of view, and conventional optical coherence tomography (OCT) does not have sufficient contrast to differentiate ASM from surrounding tissues. We have developed a birefringence microscopy platform that leverages the micro-organization of tissue to add further dimension to traditional OCT. We have used this technology to validate ASM measurements in ex vivo swine and canine studies, visualize and characterize volumetric representations of ASM in vivo, and quantify and predict ASM contractile force as a function of optical retardation. We provide in vivo images and volumetric assessments of ASM in living humans and document structural disease variations in subjects with mild asthma. The opportunity to link inflammatory responses to ASM responses and to link ASM responses to clinical responses and outcomes could lead to an increased understanding of diseases of the airway and, ultimately, to improved patient outcomes.

Allergic asthma is distinguished by sensitivity of allergen-specific CD4+ T cells and airway structural cells to type 2 inflammation.

Despite systemic sensitization, not all allergic individuals develop asthma symptoms upon airborne allergen exposure. Determination of the factors that lead to the asthma phenotype in allergic individuals could guide treatment and identify novel therapeutic targets. We used segmental allergen challenge of allergic asthmatics (AA) and allergic nonasthmatic controls (AC) to determine whether there are differences in the airway immune response or airway structural cells that could drive the development of asthma. Both groups developed prominent allergic airway inflammation in response to allergen. However, asthmatic subjects had markedly higher levels of innate type 2 receptors on allergen-specific CD4+ T cells recruited into the airway. There were also increased levels of type 2 cytokines, increased total mucin, and increased mucin MUC5AC in response to allergen in the airways of AA subjects. Furthermore, type 2 cytokine levels correlated with the mucin response in AA but not AC subjects, suggesting differences in the airway epithelial response to inflammation. Finally, AA subjects had increased airway smooth muscle mass at baseline measured in vivo using novel orientation-resolved optical coherence tomography. Our data demonstrate that the development of allergic asthma is dependent on the responsiveness of allergen-specific CD4+ T cells to innate type 2 mediators as well as increased sensitivity of airway epithelial cells and smooth muscle to type 2 inflammation.