Exposure to PM2.5 modulate the pro-inflammatory and interferon responses against influenza virus infection in a human 3D bronchial epithelium model

Epidemiological studies showed a positive association between exposure to PM2.5 and the severity of influenza virus infection. However, the mechanisms by which PM2.5 can disrupt antiviral defence are still unclear. From this perspective, the objective of this study was to evaluate the effects of PM2.5 on antiviral signalling in the respiratory epithelium using the bronchial Calu-3 cell line grown at the air-liquid interface. Pre-exposure to PM2.5 before infection with the influenza virus was investigated, as well as a co-exposure. Although a physical interaction between the virus and the particles seems possible, no effect of PM2.5 on viral replication was observed during co-exposure, although a downregulation of IFN-β release was associated to PM2.5 exposure. However, pre-exposure slightly increased the viral nucleoprotein production and the pro-inflammatory response. Conversely, the level of the myxovirus resistance protein A (MxA), an interferon-stimulated gene (ISG) induced by IFN-β, was reduced. Therefore, these results suggest that pre-exposure to PM2.5 could alter the antiviral response of bronchial epithelial cells, increasing their susceptibility to viral infection.

Disruption of IL-17-mediated immunosurveillance in the respiratory mucosa results in invasive Streptococcus pyogenes infection

Introduction

Streptococcus pyogenes is a Gram-positive pathogen that causes a significant global burden of skin pyoderma and pharyngitis. In some cases, infection can lead to severe invasive streptococcal diseases. Previous studies have shown that IL-17 deficiency in mice (IL-17-/-) can reduce S. pyogenes clearance from the mucosal surfaces. However, the effect of IL-17 on the development of severe invasive streptococcal disease has not yet been assessed.

Methods

Here, we modeled single or repeated non-lethal intranasal (IN) S. pyogenes M1 strain infections in immunocompetent and IL-17-/- mice to assess bacterial colonization following a final IN or skin challenge.

Results

Immunocompetent mice that received a single S. pyogenes infection showed long-lasting immunity to subsequent IN infection, and no bacteria were detected in the lymph nodes or spleens. However, in the absence of IL-17, a single IN infection resulted in dissemination of S. pyogenes to the lymphoid organs, which was accentuated by repeated IN infections. In contrast to what was observed in the respiratory mucosa, skin immunity did not correlate with the systemic levels of IL-17. Instead, it was found to be associated with the activation of germinal center responses and accumulation of neutrophils in the spleen.

Discussion

Our results demonstrated that IL-17 plays a critical role in preventing invasive disease following S. pyogenes infection of the respiratory tract.

Diesel exhaust particle exposure exacerbates ciliary and epithelial barrier dysfunction in the multiciliated bronchial epithelium models

Airway epithelium, the first defense barrier of the respiratory system, facilitates mucociliary clearance against inflammatory stimuli, such as pathogens and particulates inhaled into the airway and lung. Inhaled particulate matter 2.5 (PM2.5) can penetrate the alveolar region of the lung, and it can develop and exacerbate respiratory diseases. Although the pathophysiological effects of PM2.5 in the respiratory system are well known, its impact on mucociliary clearance of airway epithelium has yet to be clearly defined. In this study, we used two different 3D in vitro airway models, namely the EpiAirway-full-thickness (FT) model and a normal human bronchial epithelial cell (NHBE)-based air-liquid interface (ALI) system, to investigate the effect of diesel exhaust particles (DEPs) belonging to PM2.5 on mucociliary clearance. RNA-sequencing (RNA-Seq) analyses of EpiAirway-FT exposed to DEPs indicated that DEP-induced differentially expressed genes (DEGs) are related to ciliary and microtubule function and inflammatory-related pathways. The exposure to DEPs significantly decreased the number of ciliated cells and shortened ciliary length. It reduced the expression of cilium-related genes such as acetylated α-tubulin, ARL13B, DNAH5, and DNAL1 in the NHBEs cultured in the ALI system. Furthermore, DEPs significantly increased the expression of MUC5AC, whereas they decreased the expression of epithelial junction proteins, namely, ZO1, Occludin, and E-cadherin. Impairment of mucociliary clearance by DEPs significantly improved the release of epithelial-derived inflammatory and fibrotic mediators such as IL-1β, IL-6, IL-8, GM-CSF, MMP-1, VEGF, and S100A9. Taken together, it can be speculated that DEPs can cause ciliary dysfunction, hyperplasia of goblet cells, and the disruption of the epithelial barrier, resulting in the hyperproduction of lung injury mediators. Our data strongly suggest that PM2.5 exposure is directly associated with ciliary and epithelial barrier dysfunction and may exacerbate lung injury.

Evaluation of Non-Vector Transmission of Usutu Virus in Domestic Canaries (Serinus canaria)

Usutu virus (USUV) is a flavivirus transmitted to avian species through mosquito bites that causes mass mortalities in wild and captive bird populations. However, several cases of positive dead birds have been recorded during the winter, a vector-free period. To explain how USUV "overwinters", the main hypothesis is bird-to-bird transmission, as shown for the closely related West Nile virus. To address this question, we experimentally challenged canaries with intranasal inoculation of USUV, which led to systemic dissemination of the virus, provided the inoculated dose was sufficient (>102 TCID50). We also highlighted the oronasal excretion of infectious viral particles in infected birds. Next, we co-housed infected birds with naive sentinels, to determine whether onward transmission could be reproduced experimentally. We failed to detect such transmission but demonstrated horizontal transmission by transferring sputum from an infected to a naive canary. In addition, we evaluated the cellular tropism of respiratory mucosa to USUV in vitro using a canary tracheal explant and observed only limited evidence of viral replication. Further research is then needed to assess if and how comparable bird-to-bird transmission occurs in the wild.

Progress and challenges in the clinical evaluation of immune responses to respiratory mucosal vaccines

INTRODUCTION

Following the coronavirus disease pandemic, respiratory mucosal vaccines that elicit both mucosal and systemic immune responses have garnered increasing attention. However, human physiological characteristics pose significant challenges in the evaluation of mucosal immunity, which directly impedes the development and application of respiratory mucosal vaccines.

AREAS COVERED

This study summarizes the characteristics of immune responses in the respiratory mucosa and reviews the current status and challenges in evaluating immune response to respiratory mucosal vaccines.

EXPERT OPINION

Secretory Immunoglobulin A (S-IgA) is a major effector molecule at mucosal sites and a commonly used indicator for evaluating respiratory mucosal vaccines. However, the unique physiological structure of the respiratory tract pose significant challenges for the clinical collection and detection of S-IgA. Therefore, it is imperative to develop a sampling method with high collection efficiency and acceptance, a sensitive detection method, reference materials for mucosal antibodies, and to establish a threshold for S-IgA that correlates with clinical protection. Sample collection is even more challenging when evaluating mucosal cell immunity. Therefore, a mucosal cell sampling method with high operability and high tolerance should be established. Targets of the circulatory system capable of reflecting mucosal cellular immunity should also be explored.

An oral commensal attenuates Pseudomonas aeruginosa-induced airway inflammation and modulates nitrite flux in respiratory epithelium

IMPORTANCE

Respiratory infections are a leading cause of morbidity and mortality in people with cystic fibrosis (CF). These infections are polymicrobial in nature with overt pathogens and other colonizing microbes present. Microbiome data have indicated that the presence of oral commensal bacteria in the lungs is correlated with improved outcomes. We hypothesize that one oral commensal, Streptococcus parasanguinis, inhibits CF pathogens and modulates the host immune response. One major CF pathogen is Pseudomonas aeruginosa, a Gram-negative, opportunistic bacterium with intrinsic drug resistance and an arsenal of virulence factors. We have previously shown that S. parasanguinis inhibits P. aeruginosa in vitro in a nitrite-dependent manner through the production of reactive nitrogen intermediates. In this study, we demonstrate that while this mechanism is evident in a cell culture model of the CF airway, an alternative mechanism by which S. parasanguinis may improve outcomes for people with CF is through immunomodulation.

Nasopharyngeal Respiratory Epithelial Adenomatoid Hamartoma-Master of Masquerade

OBJECTIVES

To highlight a case of nasopharyngeal Respiratory Epithelial Adenomatoid Hamartoma (REAH) in a female patient with chronic nasal block.

METHODS

A single case report of a female patient with the diagnosis of REAH, detailing her presenting symptoms, clinical findings, management and follow up.

RESULTS

Histopathological assessment of the excised nasopharyngeal polyp was consistent with a diagnosis of REAH with a discussion on the disease and its current literature reviews.

CONCLUSION

The incidence of REAH within the nasopharynx remain rare with only few cases described in literature, especially in females.

Respiratory mucosal immune memory to SARS-CoV-2 after infection and vaccination

Respiratory mucosal immunity induced by vaccination is vital for protection from coronavirus infection in animal models. In humans, the capacity of peripheral vaccination to generate sustained immunity in the lung mucosa, and how this is influenced by prior SARS-CoV-2 infection, is unknown. Here we show using bronchoalveolar lavage samples that donors with history of both infection and vaccination have more airway mucosal SARS-CoV-2 antibodies and memory B cells than those only vaccinated. Infection also induces populations of airway spike-specific memory CD4+ and CD8+ T cells that are not expanded by vaccination alone. Airway mucosal T cells induced by infection have a distinct hierarchy of antigen specificity compared to the periphery. Spike-specific T cells persist in the lung mucosa for 7 months after the last immunising event. Thus, peripheral vaccination alone does not appear to induce durable lung mucosal immunity against SARS-CoV-2, supporting an argument for the need for vaccines targeting the airways.

Omicron subvariants illustrate reduced respiratory tissue penetration, cell damage and inflammatory responses in human airway epithelia

Introduction

To explore whether the reported lower pathogenicity in infected individuals of variant of concern (VoC) Omicron and its current subvariants compared to VoC Delta may be related to fundamental differences in the initial virus-tissue interaction, we assessed their ability to penetrate, replicate and cause damage in a human 3D respiratory model.

Methods

For this, we used TEER measurements, real-time PCR, LDH, cytokine and complex confocal imaging analyses.

Results and discussion

We observed that Delta readily penetrated deep into the respiratory epithelium and this was associated with major tissue destruction, high LDH activity, high viral loads and pronounced innate immune activation as observed by intrinsic C3 activation and IL-6 release at infection sites. In contrast, Omicron subvariants BA.5, BQ.1.1 and BF7 remained superficially in the mucosal layer resulting merely in outward-directed destruction of cells, maintenance of epithelial integrity, minimal LDH activity and low basolateral release of virus at infection sites, as well as significantly smaller areas of complement activation and lower IL-6 secretion. Interestingly, also within Omicron subvariants differences were observed with newer Omicron subvariants BQ.1.1 and BF.7 illustrating significantly reduced viral loads, IL-6 release and LDH activity compared to BA.5. Our data indicate that earliest interaction events after SARS-CoV-2 transmission may have a role in shaping disease severity.

Inhibition of Urban Particulate Matter-Induced Airway Inflammation by RIPK3 through the Regulation of Tight Junction Protein Production

Urban particulate matter (UPM) is a high-hazard cause of various diseases in humans, including in the respiratory tract, skin, heart, and even brain. Unfortunately, there is no established treatment for the damage caused by UPM in the respiratory epithelium. In addition, although RIPK3 is known to induce necroptosis, its intracellular role as a negative regulator in human lungs and bronchial epithelia remains unclear. Here, the endogenous expression of RIPK3 was significantly decreased 6 h after exposure to UPM. In RIPK3-ovexpressed cells, RIPK3 was not moved to the cytoplasm from the nucleus. Interestingly, the overexpression of RIPK3 dramatically decreased TEER and F-actin formation. Its overexpression also decreased the expression of genes for pro-inflammatory cytokines (IL-6 and IL-8) and tight junctions (ZO-1, -2, -3, E-cadherin, and claudin) during UPM-induced airway inflammation. Importantly, overexpression of RIPK3 inhibited the UPM-induced ROS production by inhibiting the activation of iNOS and eNOS and by regulating mitochondrial fission processing. In addition, UPM-induced activation of the iκB and NF-κB signaling pathways was dramatically decreased by RIPK3, and the expression of pro-inflammatory cytokines was decreased by inhibiting the iκB signaling pathway. Our data indicated that RIPK3 is essential for the UPM-induced inflammatory microenvironment to maintain homeostasis. Therefore, we suggest that RIPK3 is a potential therapeutic candidate for UPM-induced pulmonary inflammation.

Early-life respiratory infections and developmental immunity determine lifelong lung health

Respiratory infections are common in infants and young children. However, the immune system develops and matures as the child grows, thus the effects of infection during this time of dynamic change may have long-term consequences. The infant immune system develops in conjunction with the seeding of the microbiome at the respiratory mucosal surface, at a time that the lungs themselves are maturing. We are now recognizing that any disturbance of this developmental trajectory can have implications for lifelong lung health. Here, we outline our current understanding of the molecular mechanisms underlying relationships between immune and structural cells in the lung with the local microorganisms. We highlight the importance of gaining greater clarity as to what constitutes a healthy respiratory ecosystem and how environmental exposures influencing this network will aid efforts to mitigate harmful effects and restore lung immune health.

The Transcriptome Landscape of the In Vitro Human Airway Epithelium Response to SARS-CoV-2

Airway-liquid interface cultures of primary epithelial cells and of induced pluripotent stem-cell-derived airway epithelial cells (ALI and iALI, respectively) are physiologically relevant models for respiratory virus infection studies because they can mimic the in vivo human bronchial epithelium. Here, we investigated gene expression profiles in human airway cultures (ALI and iALI models), infected or not with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), using our own and publicly available bulk and single-cell transcriptome datasets. SARS-CoV-2 infection significantly increased the expression of interferon-stimulated genes (IFI44, IFIT1, IFIT3, IFI35, IRF9, MX1, OAS1, OAS3 and ISG15) and inflammatory genes (NFKBIA, CSF1, FOSL1, IL32 and CXCL10) by day 4 post-infection, indicating activation of the interferon and immune responses to the virus. Extracellular matrix genes (ITGB6, ITGB1 and GJA1) were also altered in infected cells. Single-cell RNA sequencing data revealed that SARS-CoV-2 infection damaged the respiratory epithelium, particularly mature ciliated cells. The expression of genes encoding intercellular communication and adhesion proteins was also deregulated, suggesting a mechanism to promote shedding of infected epithelial cells. These data demonstrate that ALI/iALI models help to explain the airway epithelium response to SARS-CoV-2 infection and are a key tool for developing COVID-19 treatments.

Rhinovirus increases Moraxella catarrhalis adhesion to the respiratory epithelium

Rhinovirus causes many types of respiratory illnesses, ranging from minor colds to exacerbations of asthma. Moraxella catarrhalis is an opportunistic pathogen that is increased in abundance during rhinovirus illnesses and asthma exacerbations and is associated with increased severity of illness through mechanisms that are ill-defined. We used a co-infection model of human airway epithelium differentiated at the air-liquid interface to test the hypothesis that rhinovirus infection promotes M. catarrhalis adhesion and survival on the respiratory epithelium. Initial experiments showed that infection with M. catarrhalis alone did not damage the epithelium or induce cytokine production, but increased trans-epithelial electrical resistance, indicative of increased barrier function. In a co-infection model, infection with the more virulent rhinovirus-A and rhinovirus-C, but not the less virulent rhinovirus-B types, increased cell-associated M. catarrhalis. Immunofluorescent staining demonstrated that M. catarrhalis adhered to rhinovirus-infected ciliated epithelial cells and infected cells being extruded from the epithelium. Rhinovirus induced pronounced changes in gene expression and secretion of inflammatory cytokines. In contrast, M. catarrhalis caused minimal effects and did not enhance RV-induced responses. Our results indicate that rhinovirus-A or C infection increases M. catarrhalis survival and cell association while M. catarrhalis infection alone does not cause cytopathology or epithelial inflammation. Our findings suggest that rhinovirus and M. catarrhalis co-infection could promote epithelial damage and more severe illness by amplifying leukocyte inflammatory responses at the epithelial surface.

Role of Secondary Organic Matter on Soot Particle Toxicity in Reconstituted Human Bronchial Epithelia Exposed at the Air-Liquid Interface

Secondary organic matter (SOM) formed from gaseous precursors constitutes a major mass fraction of fine particulate matter. However, there is only limited evidence on its toxicological impact. In this study, air-liquid interface cultures of human bronchial epithelia were exposed to different series of fresh and aged soot particles generated by a miniCAST burner combined with a micro smog chamber (MSC). Soot cores with geometric mean mobility diameters of 30 and 90 nm were coated with increasing amounts of SOM, generated from the photo-oxidation of mesitylene and ozonolysis of α-pinene. At 24 h after exposure, the release of lactate dehydrogenase (LDH), indicating cell membrane damage, was measured and proteome analysis, i.e. the release of 102 cytokines and chemokines to assess the inflammatory response, was performed. The data indicate that the presence of the SOM coating and its bioavailability play an important role in cytotoxicity. In particular, LDH release increased with increasing SOM mass/total particle mass ratio, but only when SOM had condensed on the outer surface of the soot cores. Proteome analysis provided further evidence for substantial interference of coated particles with essential properties of the respiratory epithelium as a barrier as well as affecting cell remodeling and inflammatory activity.

The underappreciated role of resident epithelial cell populations in metastatic progression: contributions of the lung alveolar epithelium

Metastatic cancer is difficult to treat and is responsible for the majority of cancer-related deaths. After cancer cells initiate metastasis and successfully seed a distant site, resident cells in the tissue play a key role in determining how metastatic progression develops. The lung is the second most frequent site of metastatic spread, and the primary site of metastasis within the lung is alveoli. The most abundant cell type in the alveolar niche is the epithelium. This review will examine the potential contributions of the alveolar epithelium to metastatic progression. It will also provide insight into other ways in which alveolar epithelial cells, acting as immune sentinels within the lung, may influence metastatic progression through their various interactions with cells in the surrounding microenvironment.

New Insights into the Alveolar Epithelium as a Driver of Acute Respiratory Distress Syndrome

The alveolar epithelium serves as a barrier between the body and the external environment. To maintain efficient gas exchange, the alveolar epithelium has evolved to withstand and rapidly respond to an assortment of inhaled, injury-inducing stimuli. However, alveolar damage can lead to loss of alveolar fluid barrier function and exuberant, non-resolving inflammation that manifests clinically as acute respiratory distress syndrome (ARDS). This review discusses recent discoveries related to mechanisms of alveolar homeostasis, injury, repair, and regeneration, with a contemporary emphasis on virus-induced lung injury. In addition, we address new insights into how the alveolar epithelium coordinates injury-induced lung inflammation and review maladaptive lung responses to alveolar damage that drive ARDS and pathologic lung remodeling.

Tromethamine improves mucociliary clearance in cystic fibrosis pigs

In cystic fibrosis (CF), the loss of cystic fibrosis transmembrane conductance regulator (CFTR) mediated Cl-  and HCO3 -  secretion across the epithelium acidifies the airway surface liquid (ASL). Acidic ASL alters two key host defense mechanisms: Rapid ASL bacterial killing and mucociliary transport (MCT). Aerosolized tromethamine (Tham) increases ASL pH and restores the ability of ASL to rapidly kill bacteria in CF pigs. In CF pigs, clearance of insufflated microdisks is interrupted due to abnormal mucus causing microdisks to abruptly recoil. Aerosolizing a reducing agent to break disulfide bonds that link mucins improves MCT. Here, we are interested in restoring MCT in CF by aerosolizing Tham, a buffer with a pH of 8.4. Because Tham is hypertonic to serum, we use an acidified formulation as a control. We measure MCT by tracking the caudal movement of individual tantalum microdisks with serial chest computed tomography scans. Alkaline Tham improves microdisk clearance to within the range of that seen in non-CF pigs. It also partially reverses MCT defects, including reduced microdisk recoil and elapse time until they start moving after methacholine stimulation in CF pig airways. The effect is not due to hypertonicity, as it is not seen with acidified Tham or hypertonic saline. This finding indicates acidic ASL impairs CF MCT and suggests that alkalinization of ASL pH with inhaled Tham may improve CF airway disease.

Time-resolved characterization of the innate immune response in the respiratory epithelium of human, porcine, and bovine during influenza virus infection

Viral cross-species transmission is recognized to be a major threat to both human and animal health, however detailed information on determinants underlying virus host tropism and susceptibility is missing. Influenza C and D viruses (ICV, IDV) are two respiratory viruses that share up to 50% genetic similarity, and both employ 9-O-acetylated sialic acids to enter a host cell. While ICV infections are mainly restricted to humans, IDV possesses a much broader host tropism and has shown to have a zoonotic potential. This suggests that additional virus–host interactions play an important role in the distinct host spectrum of ICV and IDV. In this study, we aimed to characterize the innate immune response of the respiratory epithelium of biologically relevant host species during influenza virus infection to identify possible determinants involved in viral cross-species transmission. To this end, we performed a detailed characterization of ICV and IDV infection in primary airway epithelial cell (AEC) cultures from human, porcine, and bovine origin. We monitored virus replication kinetics, cellular and host tropism, as well as the host transcriptional response over time at distinct ambient temperatures. We observed that both ICV and IDV predominantly infect ciliated cells, independently from host and temperature. Interestingly, temperature had a profound influence on ICV replication in both porcine and bovine AEC cultures, while IDV replicated efficiently irrespective of temperature and host. Detailed time-resolved transcriptome analysis revealed both species-specific and species uniform host responses and highlighted 34 innate immune-related genes with clear virus-specific and temperature-dependent profiles. These data provide the first comprehensive insights into important common and species-specific virus-host dynamics underlying the distinct host tropism of ICV and IDV, as well as possible determinants involved in viral cross-species transmission.

Clinical validation and utility of Percepta GSC for the evaluation of lung cancer

The Percepta Genomic Sequencing Classifier (GSC) was developed to up-classify as well as down-classify the risk of malignancy for lung lesions when bronchoscopy is non-diagnostic. We evaluated the performance of Percepta GSC in risk re-classification of indeterminate lung lesions. This multicenter study included individuals who currently or formerly smoked undergoing bronchoscopy for suspected lung cancer from the AEGIS I/ II cohorts and the Percepta Registry. The classifier was measured in normal-appearing bronchial epithelium from bronchial brushings. The sensitivity, specificity, and predictive values were calculated using predefined thresholds. The ability of the classifier to decrease unnecessary invasive procedures was estimated. A set of 412 patients were included in the validation (prevalence of malignancy was 39.6%). Overall, 29% of intermediate-risk lung lesions were down-classified to low-risk with a 91.0% negative predictive value (NPV) and 12.2% of intermediate-risk lesions were up-classified to high-risk with a 65.4% positive predictive value (PPV). In addition, 54.5% of low-risk lesions were down-classified to very low risk with >99% NPV and 27.3% of high-risk lesions were up-classified to very high risk with a 91.5% PPV. If the classifier results were used in nodule management, 50% of patients with benign lesions and 29% of patients with malignant lesions undergoing additional invasive procedures could have avoided these procedures. The Percepta GSC is highly accurate as both a rule-out and rule-in test. This high accuracy of risk re-classification may lead to improved management of lung lesions.

Ferrets are valuable models for SARS-CoV-2 research

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulted in an ongoing pandemic with millions of deaths worldwide. Infection of humans can be asymptomatic or result in fever, fatigue, dry cough, dyspnea, and acute respiratory distress syndrome with multiorgan failure in severe cases. The pathogenesis of COVID-19 is not fully understood, and various models employing different species are currently applied. Ferrets can be infected with SARS-CoV-2 and efficiently transmit the virus to contact animals. In contrast to hamsters, ferrets usually show mild disease and viral replication restricted to the upper airways. Most reports have used the intranasal inoculation route, while the intratracheal infection model is not well characterized. Herein, we present clinical, virological, and pathological data from young ferrets intratracheally inoculated with SARS-CoV-2. Infected animals showed no significant clinical signs, and had transient infection with peak viral RNA loads at 4 days postinfection, mild to moderate rhinitis, and pulmonary endothelialitis/vasculitis. Viral antigen was exclusively found in the respiratory epithelium of the nasal cavity, indicating a particular tropism for cells in this location. Viral antigen was associated with epithelial damage and influx of inflammatory cells, including activated neutrophils releasing neutrophil extracellular traps. Scanning electron microscopy of the nasal respiratory mucosa revealed loss of cilia, shedding, and rupture of epithelial cells. The currently established ferret SARS-CoV-2 infection models are comparatively discussed with SARS-CoV-2 pathogenesis in mink, and the advantages and disadvantages of both species as research models for zoonotic betacoronaviruses are highlighted.

Early Th2 inflammation in the upper respiratory mucosa as a predictor of severe COVID-19 and modulation by early treatment with inhaled corticosteroids: a mechanistic analysis

BACKGROUND

Community-based clinical trials of the inhaled corticosteroid budesonide in early COVID-19 have shown improved patient outcomes. We aimed to understand the inflammatory mechanism of budesonide in the treatment of early COVID-19.

METHODS

The STOIC trial was a randomised, open label, parallel group, phase 2 clinical intervention trial where patients were randomly assigned (1:1) to receive usual care (as needed antipyretics were only available treatment) or inhaled budesonide at a dose of 800 μg twice a day plus usual care. For this experimental analysis, we investigated the nasal mucosal inflammatory response in patients recruited to the STOIC trial and in a cohort of SARS-CoV-2-negative healthy controls, recruited from a long-term observational data collection study at the University of Oxford. In patients with SARS-CoV-2 who entered the STOIC study, nasal epithelial lining fluid was sampled at day of randomisation (day 0) and at day 14 following randomisation, blood samples were also collected at day 28 after randomisation. Nasal epithelial lining fluid and blood samples were collected from the SARS-CoV-2 negative control cohort. Inflammatory mediators in the nasal epithelial lining fluid and blood were assessed for a range of viral response proteins, and innate and adaptive response markers using Meso Scale Discovery enzyme linked immunoassay panels. These samples were used to investigate the evolution of inflammation in the early COVID-19 disease course and assess the effect of budesonide on inflammation.

FINDINGS

146 participants were recruited in the STOIC trial (n=73 in the usual care group; n=73 in the budesonide group). 140 nasal mucosal samples were available at day 0 (randomisation) and 122 samples at day 14. At day 28, whole blood was collected from 123 participants (62 in the budesonide group and 61 in the usual care group). 20 blood or nasal samples were collected from healthy controls. In early COVID-19 disease, there was an enhanced inflammatory airway response with the induction of an anti-viral and T-helper 1 and 2 (Th1/2) inflammatory response compared with healthy individuals. Individuals with COVID-19 who clinically deteriorated (ie, who met the primary outcome) showed an early blunted respiratory interferon response and pronounced and persistent Th2 inflammation, mediated by CC chemokine ligand (CCL)-24, compared with those with COVID-19 who did not clinically deteriorate. Over time, the natural course of COVID-19 showed persistently high respiratory interferon concentrations and elevated concentrations of the eosinophil chemokine, CCL-11, despite clinical symptom improvement. There was persistent systemic inflammation after 28 days following COVID-19, including elevated concentrations of interleukin (IL)-6, tumour necrosis factor-α, and CCL-11. Budesonide treatment modulated inflammation in the nose and blood and was shown to decrease IL-33 and increase CCL17. The STOIC trial was registered with ClinicalTrials.gov, NCT04416399.

INTERPRETATION

An initial blunted interferon response and heightened T-helper 2 inflammatory response in the respiratory tract following SARS-CoV-2 infection could be a biomarker for predicting the development of severe COVID-19 disease. The clinical benefit of inhaled budesonide in early COVID-19 is likely to be as a consequence of its inflammatory modulatory effect, suggesting efficacy by reducing epithelial damage and an improved T-cell response.

FUNDING

Oxford National Institute of Health Research Biomedical Research Centre and AstraZeneca.

Elastic mucus strands impair mucociliary clearance in cystic fibrosis pigs

SignificanceIn many lung diseases, increased amounts of and/or abnormal mucus impair mucociliary clearance, a key defense against inhaled and aspirated material. Submucosal glands lining cartilaginous airways secrete mucus strands that are pulled by cilia until they break free from the duct and sweep upward toward the larynx, carrying particulates. In cystic fibrosis (CF) pigs, progressive clearance of insufflated microdisks was repeatedly interrupted as microdisks abruptly recoiled. Aerosolizing a reducing agent to break disulfide bonds linking mucins ruptured mucus strands, freeing them from submucosal gland ducts and allowing cilia to propel them up the airways. These findings highlight the abnormally increased elasticity of CF mucus and suggest that agents that break disulfide bonds might have value in lung diseases with increased mucus.

Mucus-producing epithelial models for investigating the activity of gene delivery systems in the lung

Inhaled transfection particles have to penetrate the mucus layer lining the airways to successfully deliver their therapeutic nucleic acid payload to target cells in the underlying epithelium. However, the in vitro models used for evaluating gene carrier efficiency often disregard this viscous defensive barrier. In this study, the two mucus-secreting cell lines NCI-H292 and Calu-3 were selected to develop a series of epithelial models displaying gradual mucus production. In NCI-H292 models, a gradual increase in the MUC5AC mucin was obtained after cell exposure to inducers. In Calu-3 models, MUC5AC production increased as a function of culture duration (3, 7, 14 days) at the air-liquid interface (ALI). Six DOPC-derived cationic lipids were designed and their pDNA delivery activity was evaluated to validate these cellular models. The strongest impairment of the lipid delivery activity was observed in the Calu-3 14-d ALI model. The MUC5AC production in this model was the greatest and the mucus layer was 20 µm thick. The mucus exhibited a solid viscoelastic behaviour, and represented a major hindrance to lipoplex diffusion. The Calu-3 14-d ALI model will be highly useful for accurate evaluation of gene carriers intended for airway administration and characterization of their interactions with the mucus.

Regulation of airway immunity by epithelial miRNAs

The airway epithelium is essential to protect the host from inhaled pathogens and particles. It maintains immune homeostasis and mediates tissue repair after injury. Inflammatory diseases of the airways are associated with failure of epithelial functions, including loss of barrier integrity that results in increased tissue permeability and immune activation; excessive mucus secretion and impaired mucociliary clearance that leads to airflow obstruction and microbial overgrowth; and dysregulation of cellular signals that promotes inflammation and alters tissue structure and airway reactivity. MicroRNAs play crucial roles in mounting appropriate cellular responses to environmental stimuli and preventing disease, using a common machinery and mechanism to regulate gene expression in epithelial cells, immune cells of hematopoietic origin, and other cellular components of the airways. Respiratory diseases are accompanied by dramatic changes in epithelial miRNA expression that drive persistent immune dysregulation. In this review, we discuss responses of the epithelium that promote airway immunopathology, with a focus on miRNAs that contribute to the breakdown of essential epithelial functions. We emphasize the emerging role of miRNAs in regulation of epithelial responses in respiratory health and their value as diagnostic and therapeutic targets.

OCT particle tracking velocimetry of biofluids in a microparallel plate strain induction chamber

SIGNIFICANCE

Imaging biofluid flow under physiologic conditions aids in understanding disease processes and health complications. We present a method employing a microparallel plate strain induction chamber (MPPSIC) amenable to optical coherence tomography to track depth-resolved lateral displacement in fluids in real time while under constant and sinusoidal shear.

AIM

Our objective is to track biofluid motion under shearing conditions found in the respiratory epithelium, first validating methods in Newtonian fluids and subsequently assessing the capability of motion-tracking in bronchial mucus.

APPROACH

The motion of polystyrene microspheres in aqueous glycerol is tracked under constant and sinusoidal applied shear rates in the MPPSIC and is compared with theory. Then 1.5 wt. % bronchial mucus samples considered to be in a normal hydrated state are studied under sinusoidal shear rates of amplitudes 0.7 to 3.2  s  -  1.

RESULTS

Newtonian fluids under low Reynolds conditions (Re  ∼  10  -  4) exhibit velocity decreases directly proportional to the distance from the plate driven at both constant and oscillating velocities, consistent with Navier-Stokes's first and second problems at finite depths. A 1.5 wt. % mucus sample also exhibits a uniform shear strain profile.

CONCLUSIONS

The MPPSIC provides a new capability for studying biofluids, such as mucus, to assess potentially non-linear or strain-rate-dependent properties in a regime that is relevant to the mucus layer in the lung epithelium.

Molecular mapping of interstitial lung disease reveals a phenotypically distinct senescent basal epithelial cell population

Compromised regenerative capacity of lung epithelial cells can lead to cellular senescence, which may precipitate fibrosis. While increased markers of senescence have been reported in idiopathic pulmonary fibrosis (IPF), the origin and identity of these senescent cells remain unclear, and tools to characterize context-specific cellular senescence in human lung are lacking. We observed that the senescent marker p16 is predominantly localized to bronchiolized epithelial structures in scarred regions of IPF and systemic sclerosis-associated interstitial lung disease (SSc-ILD) lung tissue, overlapping with the basal epithelial markers Keratin 5 and Keratin 17. Using in vitro models, we derived transcriptional signatures of senescence programming specific to different types of lung epithelial cells and interrogated these signatures in a single-cell RNA-Seq data set derived from control, IPF, and SSc-ILD lung tissue. We identified a population of basal epithelial cells defined by, and enriched for, markers of cellular senescence and identified candidate markers specific to senescent basal epithelial cells in ILD that can enable future functional studies. Notably, gene expression of these cells significantly overlaps with terminally differentiating cells in stratified epithelia, where it is driven by p53 activation as part of the senescence program.

Genetic and non-genetic factors affecting the expression of COVID-19-relevant genes in the large airway epithelium

BACKGROUND

The large airway epithelial barrier provides one of the first lines of defense against respiratory viruses, including SARS-CoV-2 that causes COVID-19. Substantial inter-individual variability in individual disease courses is hypothesized to be partially mediated by the differential regulation of the genes that interact with the SARS-CoV-2 virus or are involved in the subsequent host response. Here, we comprehensively investigated non-genetic and genetic factors influencing COVID-19-relevant bronchial epithelial gene expression.

METHODS

We analyzed RNA-sequencing data from bronchial epithelial brushings obtained from uninfected individuals. We related ACE2 gene expression to host and environmental factors in the SPIROMICS cohort of smokers with and without chronic obstructive pulmonary disease (COPD) and replicated these associations in two asthma cohorts, SARP and MAST. To identify airway biology beyond ACE2 binding that may contribute to increased susceptibility, we used gene set enrichment analyses to determine if gene expression changes indicative of a suppressed airway immune response observed early in SARS-CoV-2 infection are also observed in association with host factors. To identify host genetic variants affecting COVID-19 susceptibility in SPIROMICS, we performed expression quantitative trait (eQTL) mapping and investigated the phenotypic associations of the eQTL variants.

RESULTS

We found that ACE2 expression was higher in relation to active smoking, obesity, and hypertension that are known risk factors of COVID-19 severity, while an association with interferon-related inflammation was driven by the truncated, non-binding ACE2 isoform. We discovered that expression patterns of a suppressed airway immune response to early SARS-CoV-2 infection, compared to other viruses, are similar to patterns associated with obesity, hypertension, and cardiovascular disease, which may thus contribute to a COVID-19-susceptible airway environment. eQTL mapping identified regulatory variants for genes implicated in COVID-19, some of which had pheWAS evidence for their potential role in respiratory infections.

CONCLUSIONS

These data provide evidence that clinically relevant variation in the expression of COVID-19-related genes is associated with host factors, environmental exposures, and likely host genetic variation.

Airway Telomere Length in Lung Transplant Recipients

Introduction

Chronic lung allograft dysfunction (CLAD) represents the major impediment to long term survival following lung transplantation. Donor and recipient telomere length have been shown to associate with lung transplant outcomes, including CLAD. In this study we aimed to measure the telomere lengths of bronchial and bronchiolar airway cells in lung allografts early after transplantation and to investigate associations with CLAD and all-cause mortality.

Methods

This prospective, longitudinal study was performed at The Prince Charles Hospital, Australia. Airway cells were collected via bronchial and bronchiolar airway brushings at post-transplant bronchoscopies. The relative telomere length in airway cells was determined by quantitative PCR based on the T/S ratio. All patients were censored for CLAD and all-cause mortality in August 2020.

Results

In total 231 bronchoscopies incorporating transbronchial brush and bronchial brush were performed in 120 patients. At the time of censoring, 43% and 35% of patients, respectively, had developed CLAD and had died. Airway bronchiolar and bronchial telomere lengths were strongly correlated (r=0.78, p<0.001), confirming conservation of telomere length with airway branch generation. Both the bronchiolar (r = -0.34, p<0.001) and bronchial (r = -0.31, p<0.001) telomere length decreased with age. Shorter airway telomere length was associated with older donor age and higher donor pack-year smoking history. Neither the bronchiolar nor the bronchial airway telomere length were associated with the development of CLAD (HR 0.39 (0.06-2.3), p=0.30; HR 0.66 (0.2-1.7), p=0.39, respectively) or all-cause mortality (HR 0.92 (0.2-4.5), p=0.92; HR 0.47 (0.1-1.9), p=0.28, respectively).

Conclusions

In this cohort, airway telomere length was associated with donor age and smoking history but was not associated with the future development of CLAD or all-cause mortality.

Fiberoptic Bronchoscopic Submucosal Injection of Mitomycin C for Recurrent Bening Tracheal Stenosis: A Case Series

BACKGROUND

Benign tracheal stenosis has emerged as a therapeutic challenge for physicians involved in the care of survivors of critical care units. Although the traditional mainstay of open surgical reconstructive treatment is still considered the gold standard, endoscopic therapies such as laser re-canalization, balloon dilation, or stenting are commonly practiced in invasive bronchology. Recurrent obstructing granulomas pose a challenge for bronchoscopists. Mitomycin C (MyC) is a cytotoxic agent that is isolated from Streptomyces caespitosus and acts by inhibiting DNA and RNA synthesis through alkylation and cross-linkages. Topical MyC is commonly used in indirect laryngoscopies for the treatment of granulation tissue in the trachea by using saturated pledgets.

OBJECTIVES

To describe fiberoptic bronchoscopic submucosal injection of MyC as a treatment for recurrent bening tracheal stenosis.

METHODS

The authors report their successful experience with submucosal intralesional injection of MyC in the management of recurrent obstructing granulomas/stenosis using the flexible fiberoptic bronchoscope in a series of 10 patients between 2005 and 2019.

RESULTS

The results suggest that intralesional injection of MyC using the flexible bronchoscope after the endoscopic treatment of the stenotic lesion may reduce the rate of subsequent formation of granulation tissue and scarring without side effects.

CONCLUSIONS

The efficacy of MyC injection should be studied prospectively.

Rhinovirus and Innate Immune Function of Airway Epithelium

Airway epithelial cells, which lines the respiratory mucosa is in direct contact with the environment. Airway epithelial cells are the primary target for rhinovirus and other inhaled pathogens. In response to rhinovirus infection, airway epithelial cells mount both pro-inflammatory responses and antiviral innate immune responses to clear the virus efficiently. Some of the antiviral responses include the expression of IFNs, endoplasmic reticulum stress induced unfolded protein response and autophagy. Airway epithelial cells also recruits other innate immune cells to establish antiviral state and resolve the inflammation in the lungs. In patients with chronic lung disease, these responses may be either defective or induced in excess leading to deficient clearing of virus and sustained inflammation. In this review, we will discuss the mechanisms underlying antiviral innate immunity and the dysregulation of some of these mechanisms in patients with chronic lung diseases.

Bioengineered airway epithelial grafts with mucociliary function based on collagen IV- and laminin-containing extracellular matrix scaffolds

Current methods to replace damaged upper airway epithelium with exogenous cells are limited. Existing strategies use grafts that lack mucociliary function, leading to infection and the retention of secretions and keratin debris. Strategies that regenerate airway epithelium with mucociliary function are clearly desirable and would enable new treatments for complex airway disease.Here, we investigated the influence of the extracellular matrix (ECM) on airway epithelial cell adherence, proliferation and mucociliary function in the context of bioengineered mucosal grafts. In vitro, primary human bronchial epithelial cells (HBECs) adhered most readily to collagen IV. Biological, biomimetic and synthetic scaffolds were compared in terms of their ECM protein content and airway epithelial cell adherence.Collagen IV and laminin were preserved on the surface of decellularised dermis and epithelial cell attachment to decellularised dermis was greater than to the biomimetic or synthetic alternatives tested. Blocking epithelial integrin α2 led to decreased adherence to collagen IV and to decellularised dermis scaffolds. At air-liquid interface (ALI), bronchial epithelial cells cultured on decellularised dermis scaffolds formed a differentiated respiratory epithelium with mucociliary function. Using in vivo chick chorioallantoic membrane (CAM), rabbit airway and immunocompromised mouse models, we showed short-term preservation of the cell layer following transplantation.Our results demonstrate the feasibility of generating HBEC grafts on clinically applicable decellularised dermis scaffolds and identify matrix proteins and integrins important for this process. The long-term survivability of pre-differentiated epithelia and the relative merits of this approach against transplanting basal cells should be assessed further in pre-clinical airway transplantation models.

A cytosolic heat shock protein 90 and co-chaperone p23 complex activates RIPK3/MLKL during necroptosis of endothelial cells in acute respiratory distress syndrome

Necrosis with inflammation plays a crucial role in acute respiratory distress syndrome (ARDS). Receptor-interacting protein 3 (RIPK3) regulates a newly discovered programmed form of necrosis called necroptosis. However, the underlying mechanism of necroptosis in ARDS remains unknown. Thus, the purpose of this study was to examine the possible involvement of RIPK3 in ARDS-associated necroptosis. RIPK3 protein levels were found to be significantly elevated in the plasma and bronchoalveolar lavage fluid of ARDS patients. Next, we utilised a mouse model of severe ARDS induced with high-dose lipopolysaccharide and found that lung injury was mainly due to RIPK3-mixed lineage kinase domain-like pseudokinase (MLKL)-mediated necroptosis and endothelial dysfunction. The activation of RIPK3-MLKL by tumour necrosis factor receptor 1 (TNFR1) and TNFR1-associated death domain protein (TRADD) required catalytically active RIPK1 and the inhibition of Fas-associated protein with death domain (FADD)/caspase-8 catalytic activity. We further showed that the molecular chaperone heat shock protein 90 (Hsp90)/p23, as a novel RIPK3- and MLKL-interacting complex, played an important role in RIP-MLKL-mediated necroptosis, inflammation and endothelial dysfunction in the pulmonary vasculature, which resulted in ARDS. Collectively, the results of our study indicate that necroptosis is an important mechanism of cell death in ARDS and the inhibition of necroptosis may be a therapeutic intervention for ARDS. KEY MESSAGES: Lung injury in high-dose LPS-induced severe ARDS is mainly due to RIP3-MLKL-mediated necroptosis and endothelial dysfunction. Chaperone HSP90/p23 is a novel RIP3- and MLKL-interacting complex in HPAECs. HSP90/p23 is a novel RIP3- and MLKL-interacting complex in RIP-MLKL-mediated necroptosis, inflammation and endothelial dysfunction.

Regulation of cilia abundance in multiciliated cells

Multiciliated cells (MCC) contain hundreds of motile cilia used to propel fluid over their surface. To template these cilia, each MCC produces between 100-600 centrioles by a process termed centriole amplification. Yet, how MCC regulate the precise number of centrioles and cilia remains unknown. Airway progenitor cells contain two parental centrioles (PC) and form structures called deuterosomes that nucleate centrioles during amplification. Using an ex vivo airway culture model, we show that ablation of PC does not perturb deuterosome formation and centriole amplification. In contrast, loss of PC caused an increase in deuterosome and centriole abundance, highlighting the presence of a compensatory mechanism. Quantification of centriole abundance in vitro and in vivo identified a linear relationship between surface area and centriole number. By manipulating cell size, we discovered that centriole number scales with surface area. Our results demonstrate that a cell-intrinsic surface area-dependent mechanism controls centriole and cilia abundance in multiciliated cells.

[THE CELLULAR MECHANISMS OF LUNG EDEMA CLEARANCE: DOES THE ALVEOLAR EPITHELIUM PLAY A ROLE?]

Pulmonary edema develops as a result of either alteration in the hydrostatic and oncotic pressure gradients across the pulmonary circulation and the lung interstitium or due to increased lung permeability. Alveolar fluid clearance is important in keeping the airspaces free of edema. This process is carried out via the alveolar epithelial active transport of Na+ across the alveolo-capillary barrier mostly by apical Na+ channels and basolateral Na,K-ATPases. Several pharmacologic agents such as catecholamines, vasopressin and gene therapy interventions have currently been found to stimulate the active Na+ transport and lung edema clearance. While others such as amiloride, ouabain, high tidal volume ventilation, hyperoxia and sepsis decrease the rate of alveolar fluid clearance. In conclusion, this review discusses the mechanisms and signal pathways by which the alveolar epithelium impacts lung edema clearance.

Functional vascularized lung grafts for lung bioengineering

End-stage lung disease is the third leading cause of death worldwide, accounting for 400,000 deaths per year in the United States alone. To reduce the morbidity and mortality associated with lung disease, new therapeutic strategies aimed at promoting lung repair and increasing the number of donor lungs available for transplantation are being explored. Because of the extreme complexity of this organ, previous attempts at bioengineering functional lungs from fully decellularized or synthetic scaffolds lacking functional vasculature have been largely unsuccessful. An intact vascular network is critical not only for maintaining the blood-gas barrier and allowing for proper graft function but also for supporting the regenerative cells. We therefore developed an airway-specific approach to removing the pulmonary epithelium, while maintaining the viability and function of the vascular endothelium, using a rat model. The resulting vascularized lung grafts supported the attachment and growth of human adult pulmonary cells and stem cell-derived lung-specified epithelial cells. We propose that de-epithelialization of the lung with preservation of intact vasculature could facilitate cell therapy of pulmonary epithelium and enable bioengineering of functional lungs for transplantation.

Nasal, pharyngeal, and laryngeal pemphigus vulgaris successfully treated with rituximab

Pemphigus vulgaris is a potentially fatal autoimmune blistering disease that can involve the nasopharyngeal and laryngeal tissues. The disease can be recalcitrant to conventional oral treatments, and treatment alternatives are limited. This retrospective study evaluated the efficacy of rituximab as a rescue agent in 5 patients with recalcitrant pemphigus vulgaris involving nasopharyngeal and laryngeal mucosa. All 5 patients were unresponsive to systemic steroids and at least one conventional oral immunosuppressive agent. The patients received rituximab infusions as a rescue agent because of recalcitrant disease. All 5 patients had a complete clinical response to rituximab and could discontinue systemic steroids and reduce the dosage of their initial immunosuppressive agent. No major adverse reactions were observed or reported with rituximab. Rituximab can be used as an effective rescue agent in the treatment of severe pemphigus vulgaris with nasopharyngeal and laryngeal involvement.

Translocation of Functionalized Multi-Walled Carbon Nanotubes across Human Pulmonary Alveolar Epithelium: Dominant Role of Epithelial Type 1 Cells

Uptake and translocation of short functionalized multi-walled carbon nanotubes (short-fMWCNTs) through the pulmonary respiratory epithelial barrier depend on physicochemical property and cell type. Two monoculture models, immortalized human alveolar epithelial type 1 (TT1) cells and primary human alveolar epithelial type 2 cells (AT2), which constitute the alveolar epithelial barrier, were employed to investigate the uptake and transport of 300 and 700 nm in length, poly(4-vinylpyridine)-functionalized, multi-walled carbon nanotubes (p(4VP)-MWCNTs) using quantitative imaging and spectroscopy techniques. The p(4VP)-MWCNT exhibited no toxicity on TT1 and AT2 cells, but significantly decreased barrier integrity (*p < 0.01). Uptake of p(4VP)-MWCNTs was observed in 70% of TT1 cells, correlating with compromised barrier integrity and basolateral p(4VP)-MWCNT translocation. There was a small but significantly greater uptake of 300 nm p(4VP)-MWCNTs than 700 nm p(4VP)-MWCNTs by TT1 cells. Up to 3% of both the 300 and 700 nm p(4VP)-MWCNTs reach the basal chamber; this relatively low amount arose because the supporting transwell membrane minimized the amount of p(4VP)-MWCNT translocating to the basal chamber, seen trapped between the basolateral cell membrane and the membrane. Only 8% of AT2 cells internalized p(4VP)-MWCNT, accounting for 17% of applied p(4VP)-MWCNT), with transient effects on barrier function, which initially fell then returned to normal; there was no MWCNT basolateral translocation. The transport rate was MWCNT length modulated. The comparatively lower p(4VP)-MWCNT uptake by AT2 cells is proposed to reflect a primary barrier effect of type 2 cell secretions and the functional differences between the type 1 and type 2 alveolar epithelial cells.

Nine-year-old girl with a respiratory epithelial cyst of the orbit

OBJECTIVE

Here we describe the clinical and histopathological characteristics of a nine-year-old girl with an intraorbital mass of the left orbit, and review the relevant literature.

RESULTS

Imaging data and surgical biopsy revealed an intraconal cystic lesion in the medial-inferior quadrant of the left orbit. The cyst was lined with ciliated pseudostratified epithelium, consistent with a respiratory epithelial cyst of the orbit. Cyst marsupialisation and partial mass removal alleviated symptoms, and no cyst recurrence was observed during follow-up. The literature suggests that this is an uncommon cause of a cystic orbital mass.

CONCLUSION

Respiratory epithelial cysts of the orbit should be considered in the differential diagnosis of intraorbital masses. Surgical excision of such a lesion should be limited to avoid damaging orbital structures. Respiratory epithelial cysts of the orbit generally follow a benign course, and recurrence of ocular symptoms is rare.

Early events in the pathogenesis of chronic obstructive pulmonary disease. Smoking-induced reprogramming of airway epithelial basal progenitor cells

The airway epithelium is the primary site of the earliest pathologic changes induced by smoking, contributing to the development of chronic obstructive pulmonary disease (COPD). The normal human airway epithelium is composed of several major cell types, including differentiated ciliated and secretory cells, intermediate undifferentiated cells, and basal cells (BC). BC contain the stem/progenitor cell population responsible for maintenance of the normally differentiated airway epithelium. Although inflammatory and immune processes play a significant role in the pathogenesis of COPD, the earliest lesions include hyperplasia of the BC population, suggesting that the disease may start with this cell type. Apart from BC hyperplasia, smoking induces a number of COPD-relevant airway epithelial remodeling phenotypes that are likely initiated in the BC population, including mucous cell hyperplasia, squamous cell metaplasia, epithelial-mesenchymal transition, altered ciliated and nonmucous secretory cell differentiation, and suppression of junctional barrier integrity. Significant progress has been recently made in understanding the biology of human airway BC, including gene expression features, stem/progenitor, and other functions, including interaction with other airway cell types. Accumulating evidence suggests that human airway BC function as both sensors and cellular sources of various cytokines and growth factors relevant to smoking-associated airway injury, as well as the origin of various molecular and histological phenotypes relevant to the pathogenesis of COPD. In the context of these considerations, we suggest that early BC-specific smoking-induced molecular changes are critical to the pathogenesis of COPD, and these represent a candidate target for novel therapeutic approaches to prevent COPD progression in susceptible individuals.

Effect of cold-water cooling of tonsillar fossa and pharyngeal mucosa on post-tonsillectomy pain

PURPOSE

Post-tonsillectomy pain is a notable concern and thermal injury produced by electric surgical devices is considered a main cause. Intraoperative cooling of the tonsillar fossa and pharyngeal mucosa with cold water has effectively reduced postoperative pain, but no studies have fully evaluated the effects of this technique with a proper study design. We assessed mucosal cooling in two groups of patients undergoing the same surgical technique by a single surgeon, with one group receiving cold-water cooling and the other group as a control.

METHODS

Forty patients who underwent monopolar electrocautery tonsillectomy were randomly assigned to two groups (n = 20 for each group). Group 1 received cooling of the tonsillar fossa and pharyngeal mucosa with 4 °C saline just after removal of each tonsil whereas Group 2 did not receive cooling. Postoperative pain was recorded on operation day and 1, 2, 4, 7, and 10 days postoperatively. Post-tonsillectomy pain, return to normal diet, and incidence of postoperative bleeding were compared between the groups.

RESULTS

Post-tonsillectomy pain on 6 selected days and overall pain during the 10-day follow-up period were significantly lower in Group 1. However, return to normal diet and incidence of postoperative bleeding did not differ significantly between the groups.

CONCLUSIONS

Intraoperative application of cold water after tonsillectomy significantly reduced postoperative pain. We recommend cooling the tonsillar fossa and pharyngeal mucosa with cold water during tonsillectomy to easily and effectively reduce post-tonsillectomy pain.

Cryptic respiratory epithelial cyst of the lateral orbit in a 3 year old with strabismus and amblyopia

Although choristomatous cystic orbital lesions are not uncommon in the pediatric population, these lesions rarely cause strabismus without being clinically obvious. Common choristomas, such as dermoid cysts and epidermoid cysts, usually cause vision loss through amblyopia or changes in refractive error. A 3-year-old girl with a history of esotropia and presumed lipodermoid who subsequently developed an abduction deficit and worsening of her visual acuity to 20/70 from a baseline of 20/50 is described. Magnetic resonance imaging of the orbits was performed, which showed a large cyst of the lateral orbit. On surgical removal, a developmental cyst lined with respiratory epithelium was identified and, based on its temporal location and history, characterized as a choristomatous lesion. Subsequently, the patient's visual acuity improved to 20/25 without patching. This patient had a larger than expected developmental cyst of respiratory epithelium that was originally thought to be a lipodermoid, contributing to her strabismus and amblyopia. Although orbital imaging is not routine management prior to strabismus surgery in the presence of a lipodermoid, it may be useful in cases when an abduction deficit is present or amblyopia treatment fails, because an underlying process may be responsible.