Small Airway Susceptibility to Chemical and Particle Injury

Small airways (SA) in humans are commonly defined as those conducting airways <2 mm in diameter. They are susceptible to particle- and chemical-induced injury and play a major role in the development of airway disease such as COPD and asthma. Susceptibility to injury can be attributed in part to structural features including airflow dynamics and tissue architecture, but recent evidence may indicate a more prominent role for cellular composition in directing toxicological responses. Animal studies support the hypothesis that inherent cellular differences across the tracheobronchial tree, including metabolic CYP450 expression in the distal conducting airways, can influence SA susceptibility to injury. Currently, there is insufficient information in humans to make similar conclusions, prompting further necessary work in this area. An understanding of why the SA are more susceptible to certain chemical and particle exposures than other airway regions is fundamental to our ability to identify hazardous materials, their properties, and accompanying exposure scenarios that compromise lung function. It is also important for the ability to develop appropriate models for toxicity testing. Moreover, it is central to our understanding of SA disease aetiology and how interventional strategies for treatment may be developed. In this review, we will document the structural and cellular airway regional differences that are likely to influence airway susceptibility to injury, including the role of secretory club cells. We will also describe recent advances in single-cell sequencing of human airways, which have provided unprecedented details of cell phenotype, likely to impact airway chemical and particle injury.

Pulmonary adenocarcinoma in a captive ocelot (Leopardus pardalis): morphologic and immunophenotypic characterization - case report

ABSTRACT Pulmonary adenocarcinoma is a malignant epithelial neoplasia that usually arises from conducting airways or alveolar parenchyma. It has rarely been described in wild felids, with no previous reports in ocelots. In domestic cats it is a very aggressive neoplasm with a high metastatic rate that usually evolves to death. This report aimed to describe a pulmonary adenocarcinoma in a captive and senile ocelot (Leopardus pardalis), with a thorough morphologic and immunophenotypically characterization, evidencing the epithelial-mesenchymal transition (EMT) phenomenon in a high metastatic carcinoma, an important feature rarely described in veterinary medicine, even in domestic cats.

Metabolomics of lung microdissections reveals region- and sex-specific metabolic effects of acute naphthalene exposure in mice

Naphthalene is a ubiquitous environmental contaminant produced by combustion of fossil fuels and is a primary constituent of both mainstream and side stream tobacco smoke. Naphthalene elicits region-specific toxicity in airway club cells through cytochrome P450 (P450)-mediated bioactivation, resulting in depletion of glutathione and subsequent cytotoxicity. While effects of naphthalene in mice have been extensively studied, few experiments have characterized global metabolomic changes in the lung. In individual lung regions, we found metabolomic changes in microdissected mouse lung conducting airways and parenchyma obtained from animals sacrificed at three timepoints following naphthalene treatment. Data on 577 unique identified metabolites were acquired by accurate mass spectrometry-based assays focusing on lipidomics and non-targeted metabolomics of hydrophilic compounds. Statistical analyses revealed distinct metabolite profiles between the two lung regions. Additionally, the number and magnitude of statistically significant exposure-induced changes in metabolite abundance were different between airways and parenchyma for unsaturated lysophosphatidylcholines (LPCs), dipeptides, purines, pyrimidines, and amino acids. Importantly, temporal changes were found to be highly distinct for male and female mice, with males exhibiting predominant treatment-specific changes only at two hours post-exposure. In females, metabolomic changes persisted until six hours post-naphthalene treatment, which may explain the previously characterized higher susceptibility of female mice to naphthalene toxicity. In both males and females, treatment-specific changes corresponding to lung remodeling, oxidative stress response, and DNA damage were observed. Overall, this study provides insights into potential mechanisms contributing to naphthalene toxicity and presents a novel approach for lung metabolomic analysis that distinguishes responses of major lung regions.

Cellular tropism of SARS-CoV-2 in the respiratory tract of Syrian hamsters and B6.Cg-Tg(K18-ACE2)2Prlmn/J transgenic mice

Several animal models have been developed to study the pathophysiology of SARS-CoV-2 infection and to evaluate vaccines and therapeutic agents for this emerging disease. Similar to infection with SARS-CoV-1, infection of Syrian hamsters with SARS-CoV-2 results in moderate respiratory disease involving the airways and lung parenchyma but does not lead to increased mortality. Using a combination of immunohistochemistry and transmission electron microscopy, we showed that the epithelium of the conducting airways of hamsters was the primary target for viral infection within the first 5 days of infection, with little evidence of productive infection of pneumocytes. At 6 days postinfection, antigen was cleared but parenchymal damage persisted, and the major pathological changes resolved by day 14. These findings are similar to those previously reported for hamsters with SARS-CoV-1 infection. In contrast, infection of K18-hACE2 transgenic mice resulted in pneumocyte damage, with viral particles and replication complexes in both type I and type II pneumocytes together with the presence of convoluted or cubic membranes; however, there was no evidence of virus replication in the conducting airways. The Syrian hamster is a useful model for the study of SARS-CoV-2 transmission and vaccination strategies, whereas infection of the K18-hCE2 transgenic mouse results in lethal disease with fatal neuroinvasion but with sparing of conducting airways.

Dysanapsis in men and women with obesity

Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in women than in men when matched for lung size. We examined whether differences in pulmonary mechanics with obesity and sex were associated with the dysanapsis ratio (DR), an estimate of airway size when expiratory flow is maximal, in men and women with and without obesity. Additionally, we examined the ability to estimate DR using predicted versus measured static recoil pressure at 50%FVC (Pst50FVC). Participants completed pulmonary function testing and measurements of pulmonary mechanics. Flow, volume, and transpulmonary pressure were recorded while completing forced vital capacity (FVC) maneuvers in a body plethysmograph. Static compliance curves were collected using the occlusion technique. DR was calculated using measured values of forced mid-expiratory flow and Pst50FVC. DR was also calculated using Pst predicted from previously reported data. There was no significant group (lean vs. obese) by sex interaction or main effect of group on DR. However, women displayed significantly larger DR compared with men. Predicted Pst50FVC was significantly greater than measured Pst50FVC. DR calculated from measured Pst was significantly greater than when using predicted Pst. In conclusion, while obesity does not appear to alter airway size, women may have larger airways compared with men when mid-expiratory flow is maximal. Additionally, DR estimated using predicted Pst should be used with caution.

Metabolomics of lung microdissections reveals region- and sex-specific metabolic effects of acute naphthalene exposure in mice

Naphthalene is a ubiquitous environmental contaminant produced by combustion of fossil fuels and is a primary constituent of both mainstream and side stream tobacco smoke. Naphthalene elicits region-specific toxicity in airway club cells through cytochrome P450 (P450)-mediated bioactivation, resulting in depletion of glutathione and subsequent cytotoxicity. While effects of naphthalene in mice have been extensively studied, few experiments have characterized global metabolomic changes in the lung. In individual lung regions, we found metabolomic changes in microdissected mouse lung conducting airways and parenchyma obtained from animals sacrificed 2, 6, and 24 hours following naphthalene treatment. Data on 577 unique identified metabolites were acquired by accurate mass spectrometry-based assays focusing on lipidomics and non-targeted metabolomics of hydrophilic compounds. Statistical analyses revealed distinct metabolite profiles between the two major lung regions. In addition, the number and magnitude of statistically significant exposure-induced changes in metabolite abundance were different between lung airways and parenchyma for unsaturated lysophosphatidylcholines (LPCs), dipeptides, purines, pyrimidines, and amino acids. Importantly, temporal changes were found to be highly distinct for male and female mice, with males exhibiting predominant treatment-specific changes only at two hours post-exposure. In females, metabolomic changes persisted until six hours post-naphthalene treatment, which may explain the previously characterized higher susceptibility of female mice to naphthalene toxicity. In both males and females, treatment-specific changes corresponding to lung remodeling, oxidative stress response, and DNA damage were observed, which may provide insights into potential mechanisms contributing to the previously reported effects of naphthalene exposure in the lung.

PAR-2-activated secretion by airway gland serous cells: role for CFTR and inhibition by Pseudomonas aeruginosa

Airway submucosal gland serous cells are important sites of fluid secretion in conducting airways. Serous cells also express the cystic fibrosis (CF) transmembrane conductance regulator (CFTR). Protease-activated receptor 2 (PAR-2) is a G protein-coupled receptor that activates secretion from intact airway glands. We tested if and how human nasal serous cells secrete fluid in response to PAR-2 stimulation using Ca2+ imaging and simultaneous differential interference contrast imaging to track isosmotic cell shrinking and swelling reflecting activation of solute efflux and influx pathways, respectively. During stimulation of PAR-2, serous cells exhibited dose-dependent increases in intracellular Ca2+. At stimulation levels >EC50 for Ca2+, serous cells simultaneously shrank ∼20% over ∼90 s due to KCl efflux reflecting Ca2+-activated Cl− channel (CaCC, likely TMEM16A)-dependent secretion. At lower levels of PAR-2 stimulation (<EC50 for Ca2+), shrinkage was not evident due to failure to activate CaCC. Low levels of cAMP-elevating VIP receptor (VIPR) stimulation, also insufficient to activate secretion alone, synergized with low-level PAR-2 stimulation to elicit fluid secretion dependent on both cAMP and Ca2+ to activate CFTR and K+ channels, respectively. Polarized cultures of primary serous cells also exhibited synergistic fluid secretion. Pre-exposure to Pseudomonas aeruginosa conditioned media inhibited PAR-2 activation by proteases but not peptide agonists in primary nasal serous cells, Calu-3 bronchial cells, and primary nasal ciliated cells. Disruption of synergistic CFTR-dependent PAR-2/VIPR secretion may contribute to reduced airway surface liquid in CF. Further disruption of the CFTR-independent component of PAR-2-activated secretion by P. aeruginosa may also be important to CF pathophysiology.

Demographic and statistical study of covid-19: Transmission and drug susceptibility pattern in India

Corona virus is a novel virus, causes severe acute respiratory syndrome (SARS) and spreading worldwide from person to person via communicable disease. It was first identified in the Wuhan City, Hubei Province, China in December 2019 hence it got the name COVID-19. In India, COVID-19 cases are reported severe as compared with other countries and it is standing in second position in the world after United State of America. The pathogenesis of COVID-19 is more risk in elder age as compared to young ones due to immune response. The pathogenesis of COVID-19 is recorded in three steps 1) asymptomatic state, 2) upper airways and conducting airways response and 3) hypoxia. The drugs viz., hydroxychloroquine, paracetamol, and antibiotics are mostly used for the treatment of SARS but no single drug is effective for disease. Hence, treatment of this disease is required. In this review, the correlation of confirmed and death cases due to COVID-19 in India and China are analysed by statistical methods (one-way ANOVA and t-Test). This study will give a clear picture of COVID-19 disease scenario and also helped in identifying and preventing the disease.