Hypoxia-induced pulmonary arterial hypertension augments lung injury and airway reactivity caused by ozone exposure

Contribution of local and surrounding area anthropogenic emissions to a high ozone episode in Zhengzhou, China

This study analyzed an ozone pollution episode that occurred in the summer of 2020 in Zhengzhou, the provincial capital of Henan, China, and quantified the contribution of local and surrounding area anthropogenic emissions to this episode based on the Weather Research and Forecasting with Chemistry (WRF/Chem) model. Simulation results showed that the WRF/Chem model is well suited to simulate the ozone concentrations in this area. In addition, four simulation scenarios (removing the emissions from the northern Zhengzhou, southwestern Zhengzhou, Zhengzhou local and southeastern Zhengzhou) were conducted to explore the specific contributions of local emissions and emissions from surrounding areas within Henan to this ozone pollution episode. We found that contributions from the northern, local, southwestern, and southeastern regions were 6.1%, 5.9%, 1.7%, and 1.5%, respectively. The northern and local emissions of Zhengzhou (only emissions from Zhengzhou) were prominent contributors within the simulation areas. In other words, during this episode, most of the ozone pollution in Zhengzhou appeared to be transported in from regions outside Henan Province.

Long-range transport of ozone across the eastern China seas: A case study in coastal cities in southeastern China

Tropospheric ozone (O₃) can be transported influenced by large-scale circulation. In this study, an ozone pollution episode in 6 cities of southeastern coastal area of China (SCA) in autumn 2017 was investigated. Compared with the typical local ozone pollution, there was no significant diurnal variations in this pollution episode, the O₃ concentrations maintained a stable level of about 47 ppb continuously. The WRF-CMAQ model as well as the coupled process analysis (PA) and source apportionment modules were used to simulate the formation and transport and quantify the contributions to O₃. Besides, the HYSPLIT model was used to calculate the backward trajectories arriving in the cities. We find that this pollution was mainly caused by O₃ transport from the eastern China seas (ECS). Under the movement of the Mongolian high-pressure, the O₃ precursors emitted from Beijing-Tianjin-Hebei (BTH), Northeast China (NEC) and Japan-Korea (JK) were transported to ECS then generated O₃ through photochemical reactions. Due to the weak nitrogen oxide titration and the extremely weak ozone deposition on the water surface, O₃ concentrations maintained high during the movement of air masses over ECS and finally affected SCA after long-range transport. The contributions of horizontal advections were significant basically all the day with hourly contribution about 10 ppb hr^-1 and extended from surface to 500 m above the ground level. JK contributed the most, with multi-days averaged contribution about 5 ppb and peak up to 30 ppb. The contributions of BTH and NEC were comparable, with average about 2 ppb and hourly peak of 19 and 10 ppb, respectively. For the first time, this study clearly shows that the O₃ precursors emitted from northern China and Japan-Korea contribute to the O₃ pollution in SCA under certain weather conditions, which will help to better understand and predict the O₃ pollution in that area.

Rationale for ozone-therapy as an adjuvant therapy in COVID-19: a narrative review

Coronavirus disease 2019 (COVID-19) is the respiratory disease caused by the novel severe acute respiratory syndrome-coronavirus-2 and is characterized by clinical manifestations ranging from mild, flu-like symptoms to severe respiratory insufficiency and multi-organ failure. Patients with more severe symptoms may require intensive care treatments and face a high mortality risk. Also, thrombotic complications such as pulmonary embolisms and disseminated intravascular coagulation are frequent in these patients. Indeed, COVID-19 is characterized by an abnormal inflammatory response resembling a cytokine storm, which is associated to endothelial dysfunction and microvascular complications. To date, no specific treatments are available for COVID-19 and its life-threatening complication. Immunomodulatory drugs, such as hydroxychloroquine and interleukin-6 inhibitors, as well as antithrombotic drugs such as heparin and low molecular weight heparin, are currently being administered with some benefit. Ozone therapy consists in the administration of a mixture of ozone and oxygen, called medical ozone, which has been used for over a century as an unconventional medicine practice for several diseases. Medical ozone rationale in COVID-19 is the possibility of contrasting endothelial dysfunction, modulating the immune response and acting as a virustatic agent. Thus, medical ozone could help to decrease lung inflammation, slow down viral growth, regulate lung circulation and oxygenation and prevent microvascular thrombosis. Ozone-therapy could be considered a feasible, cost-effective and easy to administer adjuvant therapy while waiting for the synthesis of a therapy or the development of the vaccine.

Transcriptional Effects of Ozone and Impact on Airway Inflammation

Epidemiological and challenge studies in healthy subjects and in individuals with asthma highlight the health impact of environmental ozone even at levels considered safe. Acute ozone exposure in man results in sputum neutrophilia in 30% of subjects particularly young children, females, and those with ongoing cardiopulmonary disease. This may be associated with systemic inflammation although not in all cases. Chronic exposure amplifies these effects and can result in the formation of asthma-like symptoms and immunopathology. Asthmatic patients who respond to ozone (responders) induce a greater number of genes in bronchoalveolar (BAL) macrophages than healthy responders with up-regulation of inflammatory and immune pathways under the control of cytokines and chemokines and the enhanced expression of remodeling and repair programmes including those associated with protease imbalances and cell-cell adhesion. These pathways are under the control of several key transcription regulatory factors including nuclear factor (NF)-κB, anti-oxidant factors such as nuclear factor (erythroid-derived 2)-like 2 NRF2, the p38 mitogen activated protein kinase (MAPK), and priming of the immune system by up-regulating toll-like receptor (TLR) expression. Murine and cellular models of acute and chronic ozone exposure recapitulate the inflammatory effects seen in humans and enable the elucidation of key transcriptional pathways. These studies emphasize the importance of distinct transcriptional networks in driving the detrimental effects of ozone. Studies indicate the critical role of mediators including IL-1, IL-17, and IL-33 in driving ozone effects on airway inflammation, remodeling and hyperresponsiveness. Transcription analysis and proof of mechanisms studies will enable the development of drugs to ameliorate the effects of ozone exposure in susceptible individuals.

NOX4 expression and distal arteriolar remodeling correlate with pulmonary hypertension in COPD

Background

Pulmonary hypertension (PH) in chronic obstructive pulmonary disease (COPD) is suggested as the consequence of emphysematous destruction of vascular bed and hypoxia of pulmonary microenvironment, mechanisms underpinning its pathogenesis however remain elusive. The dysregulated expression of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidases and superoxide generation by pulmonary vasculatures have significant implications in the hypoxia-induced PH.

Methods

In this study, the involvement of NADPH oxidase subunit 4 (NOX4) in pulmonary arteriolar remodeling of PH in COPD was investigated by ascertaining the morphological alteration of pulmonary arteries and pulmonary blood flow using cardiac magnetic resonance imaging (cMRI), and the expression and correlation of NOX4 with pulmonary vascular remodeling and pulmonary functions in COPD lungs.

Results

Results demonstrated that an augmented expression of NOX4 was correlated with the increased volume of pulmonary vascular wall in COPD lung. While the volume of distal pulmonary arteries was inversely correlated with pulmonary functions, despite it was positively associated with the main pulmonary artery distensibility, right ventricular myocardial mass end-systolic and right ventricular myocardial mass end-diastolic in COPD. In addition, an increased malondialdehyde and a decreased superoxide dismutase were observed in sera of COPD patients. Mechanistically, the abundance of NOX4 and production of reactive oxygen species (ROS) in pulmonary artery smooth muscle cells could be dynamically induced by transforming growth factor-beta (TGF-β), which in turn led pulmonary arteriolar remodeling in COPD lungs.

Conclusion

These results suggest that the NOX4-derived ROS production may play a key role in the development of PH in COPD by promoting distal pulmonary vascular remodeling.

Increased neutrophil gelatinase-associated lipocalin (NGAL) promotes airway remodelling in chronic obstructive pulmonary disease

Airway remodelling is an important component of chronic obstructive pulmonary disease (COPD). Neutrophil gelatinase-associated lipocalin (NGAL) from neutrophils may drive COPD epithelial–mesenchymal transition (EMT). NGAL expression was quantified in the lungs of COPD patients and bronchoalveolar lavage fluid (BALF) of ozone-treated mice. Reticular basement membrane (RBM) thickness and E-cadherin and α-smooth muscle actin (α-SMA) expression were determined in mice airways. Effects of cigarette smoke extract (CSE) and inflammatory factors on NGAL expression in human neutrophils as well as the effects of NGAL on airway structural cells was assessed. NGAL was mainly distributed in neutrophils and enhanced in lung tissues of both COPD patients and BALF of ozone-treated mice. We showed decreased E-cadherin and increased α-SMA expression in bronchial epithelium and increased RBM thickness in ozone-treated animals. In vitro, CSE, IL-1β and IL-17 enhanced NGAL mRNA expression in human neutrophils. NGAL, in turn, down-regulated the expression of E-cadherin and up-regulated α-SMA expression in 16HBE cells via the WNT/glycogensynthase kinase-3β (GSK-3β) pathway. Furthermore, NGAL promoted the proliferation and migration of human bronchial smooth muscle cells (HASMCs). The present study suggests that elevated NGAL promotes COPD airway remodelling possibly through altered EMT. NGAL may be a potential target for reversing airway obstruction and remodelling in COPD.