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Samuel James Brake,1 Mathew Suji Eapen,1 Kielan Darcy McAlinden,1 James Markos,1,2 Greg Haug,1,2 Josie Larby,1,2 Collin Chia,1,2 Ashutosh Hardikar,1,3 Gurpreet Kaur Singhera,4,5 Tillie L Hackett,4,5 Wenying Lu,1 Sukhwinder Singh Sohal1 1Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS, 7248, Australia; 2Department of Respiratory Medicine, Launceston General Hospital, Launceston, TAS, 7250, Australia; 3Department of Cardiothoracic Surgery, Royal Hobart Hospital, Hobart, TAS, 7000, Australia; 4Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada; 5Department of Medicine, University of British Columbia Centre for Heart Lung Innovation, St. Paul’s Hospital, Vancouver, BC, CanadaCorrespondence: Sukhwinder Singh SohalRespiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Locked Bag – 1322, Newnham Drive, Launceston, TAS, 7248, AustraliaTel +61 3 6324 5434Email sssohal@utas.edu.auBackground: Smokers and patients with COPD are highly susceptible to SARS-CoV-2 infection, leading to severe COVID-19.Methods: This cross-sectional study involved resected lung tissues from 16 patients with GOLD stage I or II COPD; of which 8 were current smokers COPD (COPD-CS), and 8 ex-smokers COPD (COPD-ES), 7 normal lung function smokers (NLFS), 9 patients with small airways disease (SAD), and 10 were never-smoking normal controls (NC). Immunostaining for ACE2, Furin, and TMPRSS2 was performed and analysed for percent expression in small airway epithelium (SAE) and counts for positively and negatively stained type 2 pneumocytes and alveolar macrophages (AMs) were done using Image ProPlus V7.0. Furthermore, primary small airway epithelial cells (pSAEC) were analysed by immunofluorescence after exposure to cigarette smoke extract (CSE).Results: ACE2, Furin, and TMPRSS2 expression significantly increased in SAE and type 2 pneumocytes in all the subjects (except Furin for NLFS) compared to NC (p < 0.001). Similar significance was observed for ACE2 positive AM (p < 0.002), except COPD-ES, which decreased in ACE2 positive AMs (p < 0.003). Total type 2 pneumocytes and AMs significantly increased in the pathological groups compared to NC (p < 0.01), except SAD (p = 0.08). However, AMs are significantly reduced in COPD-ES (p < 0.003). Significant changes were observed for tissue co-expression of Furin and TMPRSS2 with ACE2 in SAE, type 2 pneumocytes and AMs. These markers also negatively correlated with lung function parameters, such as FEV1/FVC % predicted, FEF25-75%, DLCO% predicted. A strong co-localisation and expression for ACE2 (p < 0.0001), Furin (p < 0.01), and TMPRSS2 (p < 0.0001) was observed in pSAEC treated with 1% CSE than controls.Discussion: The increased expression of ACE2, TMPRSS2 and Furin, in the SAE, type 2 pneumocytes and AMs of smokers and COPD are detrimental to lung function and proves that these patient groups could be more susceptible to severe COVID-19 infection. Increased type 2 pneumocytes suggest that these patients are vulnerable to developing post-COVID-19 interstitial pulmonary fibrosis or fibrosis in general. There could be a silently developing interstitial pathology in smokers and patients with COPD. This is the first comprehensive study to report such changes.Keywords: COVID-19, SARS-CoV-2, smoking, COPD, ACE2, type 2 pneumocytes, alveolar macrophages, epithelium

Purva Asrani,1 Afzal Hussain,2 Khalida Nasreen,3 Mohamed Fahad AlAjmi,2 Samira Amir,4 Sukhwinder Singh Sohal,5 Md Imtaiyaz Hassan3 1Molecular Biology and Biotechnology, ICAR- National Institute for Plant Biotechnology, New Delhi, 110012, India; 2Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia; 3Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, 110025, India; 4Department of Chemistry, College of Science and General Studies, Alfaisal University, Riyadh, Kingdom of Saudi Arabia; 5Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, Tasmania, AustraliaCorrespondence: Md Imtaiyaz HassanCentre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, IndiaEmail mihassan@jmi.ac.inAbstract: Coronavirus disease 2019 (COVID-19) is an emerging challenging area for the researchers to buckle up against the spread and control of the virus. Since earlier times, the diagnosis has been an important procedure in estimating the fate of epidemics by indicating the extent to which disease has been spread and to the extent, further disease prognosis would occur. The absence of anti-viral therapies and vaccines for COVID-19 at present suggests early diagnosis and isolation of the patients as the only smart approach available as of now. Presently, the increasing death rates, faster rates of transmission, non-availability of vaccines, and treatment have over-pressurized the researchers, health professionals, and government officials to develop effective clinical strategies in diagnosis and to come up with guidelines to be followed during conduction of each diagnostic procedure for maintaining healthcare systems. Since the incubation period of this virus is 2– 14 days, a patient can transmit the infection without showing symptoms. Therefore, early diagnosis and isolation of susceptible individuals are the only way to limit the spread of the virus. Significance of diagnosis and triaging, information on specimen collection, safety considerations while handling, transport, and storage of samples have been highlighted in this paper to make people more aware and develop better clinical strategies in the future.Keywords: COVID-19, diagnosis guidelines, specimen collection, safety consideration, SARS-COV-2

Mathew Suji Eapen,1 Pawan Sharma,1–3 Archana Vijay Gaikwad,1 Wenying Lu,1 Stephen Myers,1 Philip M Hansbro4,5, Sukhwinder Singh Sohal11Respiratory Translational Research Group, Department of Laboratory Medicine, College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia; 2Medical Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; 3Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW 2037, Australia; 4Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute and the University of Newcastle, Newcastle, NSW 2308, Australia; 5Centre for Inflammation, Centenary Institute and University of Technology Sydney, Sydney, NSW 2007, AustraliaAbstract: COPD is a common and highly destructive disease with huge impacts on people and health services throughout the world. It is mainly caused by cigarette smoking though environmental pollution is also significant. There are no current treatments that affect the overall course of COPD; current drugs focus on symptomatic relief and to some extent reducing exacerbation rates. There is an urgent need for in-depth studies of the fundamental pathogenic mechanisms that underpin COPD. This is vital, given the fact that nearly 40%–60% of the small airway and alveolar damage occurs in COPD well before the first measurable changes in lung function are detected. These individuals are also at a high risk of lung cancer. Current COPD research is mostly centered around late disease and/or innate immune activation within the airway lumen, but the actual damage to the airway wall has early onset. COPD is the end result of complex mechanisms, possibly triggered through initial epithelial activation. To change the disease trajectory, it is crucial to understand the mechanisms in the epithelium that are switched on early in smokers. One such mechanism we believe is the process of epithelial to mesenchymal transition. This article highlights the importance of this profound epithelial cell plasticity in COPD and also its regulation. We consider that understanding early changes in COPD will open new windows for therapy.Keywords: epithelial-to-mesenchymal transition, EMT, cancer, fibrosis, inflammation, HuR, EGFR, MMP, TGFβ

Sukhwinder Singh SohalDiscipline of Laboratory Medicine, School of Health Sciences, Faculty of Health, University of Tasmania, Launceston, AustraliaIt was with great interest that I read the recent comprehensive review by Christer Janson et al1 published in the International Journal of COPD, where authors discussed the possible mechanisms behind the increased risk of pneumonia in COPD patients using inhaled corticosteroids (ICSs), especially with fluticasone propionate (FP), where the risk was highest.1 It is an important area, and it is encouraging and reassuring that leading clinical journals are recognizing this. Understanding the fundamental mechanisms behind pneumococcal infections is critical.2 I would like to suggest that a broader discussion of new insights into the potential mechanisms contributing to the increased adherence of pneumococcus to airway wall and particularly in response to FP might has been appropriate with this opportunity.Authors’ replyChrister Janson,1 Georgios Stratelis,1,2 Anna Miller-Larsson,3 Tim W Harrison,4 Kjell Larsson51Respiratory, Allergy and Sleep Research Unit, Department of Medical Sciences, Uppsala University, Uppsala, 2Respiratory, Inflammation and Autoimmunity, AstraZeneca Nordic, Södertälje, 3Respiratory GMed, AstraZeneca Gothenburg, Mölndal, Sweden; 4Nottingham Respiratory Research Unit, City Hospital Campus, University of Nottingham, Nottingham, UK; 5Lung and Airway Research, National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, SwedenWe thank Dr Sohal for his interest in our recently published manuscript discussing the scientific rationale for the possible inhaled corticosteroid (ICS) intraclass difference in the risk of pneumonia in COPD. His own work on platelet-activating factor receptor (PAFR) expression on airway epithelial cells in COPD patients shows a trend toward increased expression of PAFR by 6-month treatment with fluticasone propionate (FP), suggesting an increased rate of pneumococcal adhesion with FP, and hence the possible development of infection or pneumonia.1 This supports in part the work by Heijink et al2 that we cited in our paper.2View the original article by Janson et al

Amir Soltani,1 Eugene Haydn Walters,1,* David W Reid,1,2 Shakti Dhar Shukla,1 Kaosia Nowrin,1 Chris Ward,3 H Konrad Muller,1 Sukhwinder Singh Sohal1,4,* 1NHMRC Center of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, TAS, Australia; 2Iron Metabolism Laboratory, Queensland Institute of Medical Research, Brisbane, QLD, Australia; 3Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK; 4School of Health Sciences, University of Tasmania, Launceston, TAS, Australia *These authors contributed equally to this work Background: This study assessed the effects of inhaled corticosteroid (ICS) on airway vascular remodeling in chronic obstructive pulmonary disease (COPD). Methods: Thirty-four subjects with mild-to-moderate COPD were randomly allocated 2:1 to ICS or placebo treatment in a double-blinded clinical trial over 6 months. Available tissue was compared before and after treatment for vessel density, and expression of VEGF, TGF-β1, and TGF-β1-related phosphorylated transcription factors p-SMAD 2/3. This clinical trial has been registered and allocated with the Australian New Zealand Clinical Trials Registry (ANZCTR) on 17/10/2012 with reference number ACTRN12612001111864. Results: There were no significant baseline differences between treatment groups. With ICS, vessels and angiogenic factors did not change in hypervascular reticular basement membrane, but in the hypovascular lamina propria (LP), vessels increased and this had a proportionate effect on lung air trapping. There was modest evidence for a reduction in LP vessels staining for VEGF with ICS treatment, but a marked and significant reduction in p-SMAD 2/3 expression. Conclusion: Six-month high-dose ICS treatment had little effect on hypervascularity or angiogenic growth factors in the reticular basement membrane in COPD, but normalized hypovascularity in the LP, and this was physiologically relevant, though accompanied by a paradoxical reduction in growth factor expression. Keywords: airway remodeling, bronchial biopsy, COPD, inhaled corticosteroid, vascular remodeling

Shakti D Shukla,1,* Rory L Fairbairn,1,* David A Gell,1 Roger D Latham,1 Sukhwinder S Sohal,1,2 Eugene H Walters,1 Ronan F O’Toole11Breathe Well Centre, School of Medicine, Faculty of Health, University of Tasmania, Hobart, TAS, Australia; 2School of Health Sciences, Faculty of Health, University of Tasmania, Launceston, TAS, Australia*These authors contributed equally to this workBackground: COPD is emerging as the third largest cause of human mortality worldwide after heart disease and stroke. Tobacco smoking, the primary risk factor for the development of COPD, induces increased expression of platelet-activating factor receptor (PAFr) in the lung epithelium. Nontypeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae adhere to PAFr on the luminal surface of human respiratory tract epithelial cells.Objective: To investigate PAFr as a potential drug target for the prevention of infections caused by the main bacterial drivers of acute exacerbations in COPD patients, NTHi and S. pneumoniae.Methods: Human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract (CSE). PAFr expression levels were determined using immunocytochemistry and quantitative polymerase chain reaction. The epithelial cells were challenged with either NTHi or S. pneumoniae labeled with fluorescein isothiocyanate, and bacterial adhesion was measured using immunofluorescence. The effect of a well-evaluated antagonist of PAFr, WEB-2086, on binding of the bacterial pathogens to BEAS-2B cells was then assessed. In silico studies of the tertiary structure of PAFr and the binding pocket for PAF and its antagonist WEB-2086 were undertaken.Results: PAFr expression by bronchial epithelial cells was upregulated by CSE, and significantly associated with increased bacterial adhesion. WEB-2086 reduced the epithelial adhesion by both NTHi and S. pneumoniae to levels observed for non-CSE-exposed cells. Furthermore, it was nontoxic toward the bronchial epithelial cells. In silico analyses identified a binding pocket for PAF/WEB-2086 in the predicted PAFr structure.Conclusion: WEB-2086 represents an innovative class of candidate drugs for inhibiting PAFr-dependent lung infections caused by the main bacterial drivers of smoking-related COPD. Keywords: airway epithelium, NTHi, pneumococci, WEB-2086, platelet-activating factor receptor, PAFr antagonist

Sukhwinder Singh Sohal, Eugene Haydn Walters School of Health Sciences, University of Tasmania, Launceston, TAS, Australia We read with interest the recent comprehensive review by Sowmya P Lakshmi et al on potential new therapies for COPD in the International Journal of Chronic Obstructive Pulmonary Disease.1 The review says that only by understanding the core pathological processes, new therapeutics emerge, and it encourages that leading respiratory journals are recognizing this. However, we would suggest that, in this review, the overall view of the pathology of COPD airway disease does not reflect the current literature. In particular, the airway wall in at least mild to moderate COPD is hypo-cellular and hypo-vascular, with markedly active epithelial–mesenchymal transition (EMT)2 as part of epithelial activation and reprogramming.3 This process is closely related to small airway fibrosis and airflow obstruction. Inhaled corticosteroids (ICSs) affect these key epithelial cellular activation and vascular aspects of COPD,2 and more research on alternatives to corticosteroid on these aspects is urgently needed. It is of interest that the peroxisome proliferator-activated receptor system that the reviewers mention has implication for EMT induction,1 as has the TGF/Activin family and the Wnt system; these pathways are replete with potential drug targets. View the original paper by Lakshimi and colleagues.

Malik Quasir Mahmood,1,* Sukhwinder Singh Sohal,1,2,* Shakti Dhar Shukla,1 Chris Ward,3 Ashutosh Hardikar,4 Wan Danial Noor,1 Hans Konrad Muller,1 Darryl A Knight,5 Eugene Haydn Walters1 1NHMRC Centre of Research Excellence for Chronic Respiratory Disease and Lung Ageing, School of Medicine, University of Tasmania, Hobart, TAS, Australia; 2School of Health Sciences, Faculty of Health, University of Tasmania, Launceston, TAS, Australia; 3Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK; 4Royal Hobart Hospital, Hobart, TAS, Australia; 5School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia *These authors contributed equally to this work Background: Small airway fibrosis is the main contributor in airflow obstruction in chronic obstructive pulmonary disease. Epithelial mesenchymal transition (EMT) has been implicated in this process, and in large airways, is associated with angiogenesis, ie, Type-3, which is classically promalignant. Objective: In this study we have investigated whether EMT biomarkers are expressed in small airways compared to large airways in subjects with chronic airflow limitation (CAL) and what type of EMT is present on the basis of vascularity. Methods: We evaluated epithelial activation, reticular basement membrane fragmentation (core structural EMT marker) and EMT-related mesenchymal biomarkers in small and large airways from resected lung tissue from 18 lung cancer patients with CAL and 9 normal controls. Tissues were immunostained for epidermal growth factor receptor (EGFR; epithelial activation marker), vimentin (mesenchymal marker), and S100A4 (fibroblast epitope). Type-IV collagen was stained to demonstrate vessels. Results: There was increased expression of EMT-related markers in CAL small airways compared to controls: EGFR (P

The WHO recently published a Tobacco Knowledge Summary (TKS) synthesizing current evidence on tobacco and COPD, aiming to raise awareness among a broad audience of health care professionals. Furthermore, it can be used as an advocacy tool in the fight for tobacco control and prevention of tobacco-related disease. This article builds on the evidence presented in the TKS, with a greater level of detail intended for a lung-specialist audience. Pulmonologists have a vital role to play in advocating for the health of their patients and the wider population by sharing five key messages: (1) Smoking is the leading cause of COPD in high-income countries, contributing to approximately 70% of cases. Quitting tobacco is an essential step toward better lung health. (2) People with COPD face a significantly higher risk of developing lung cancer. Smoking cessation is a powerful measure to reduce cancer risk. (3) Cardiovascular disease, lung cancer and type-2 diabetes are common comorbidities in people with COPD. Quitting smoking not only improves COPD management, but also reduces the risk of developing these coexisting conditions. (4) Tobacco smoke also significantly impacts children's lung growth and development, increasing the risk of respiratory infections, asthma and up to ten other conditions, and COPD later in life. Governments should implement effective tobacco control measures to protect vulnerable populations. (5) The tobacco industry's aggressive strategies in the marketing of nicotine delivery systems and all tobacco products specifically target children, adolescents, and young adults. Protecting our youth from these harmful tactics is a top priority., (© 2024. The Author(s).)

We previously reported pulmonary arterial remodelling and active endothelial-to-mesenchymal transition (EndMT) in smokers and patients with early chronic obstructive pulmonary disease (COPD). In the present study, we aimed to evaluate the role of different drivers of EndMT. Immunohistochemical staining for EndMT drivers, TGF-β1, pSMAD-2/3, SMAD-7, and β-catenin, was performed on lung resections from 46 subjects. Twelve were non-smoker-controls (NC), six normal lung function smokers (NLFS), nine patients with small-airway diseases (SAD), nine mild-moderate COPD-current smokers (COPD-CS) and ten COPD-ex-smokers (COPD-ES). Histopathological measurements were done using Image ProPlus softwarev7.0. We observed lower levels of total TGF-β1 (P<0.05) in all smoking groups than in the non-smoking control (NC). Across arterial sizes, smoking groups exhibited significantly higher (P<0.05) total and individual layer pSMAD-2/3 and SMAD-7 than in the NC group. The ratio of SAMD-7 to pSMAD-2/3 was higher in COPD patients compared with NC. Total β-catenin expression was significantly higher in smoking groups across arterial sizes (P<0.05), except for COPD-ES and NLFS groups in small and medium arteries, respectively. Increased total β-catenin was positively correlated with total S100A4 in small and medium arteries (r = 0.35, 0.50; P=0.02, 0.01, respectively), with Vimentin in medium arteries (r = 0.42, P=0.07), and with arterial thickness of medium and large arteries (r = 0.34, 0.41, P=0.02, 0.01, respectively). This is the first study uncovering active endothelial SMAD pathway independent of TGF-β1 in smokers, SAD, and COPD patients. Increased expression of β-catenin indicates its potential interaction with SMAD pathway, warranting further research to identify the deviation of this classical pathway., (© 2024 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Large airway wall lamina propria in patients with asthma-COPD overlap is hypovascular with an increase in reticular basement membrane neoangiogenesis, reflecting smoking-related COPD-like pathology and potential epithelial-to-mesenchymal transition https://bit.ly/49DeoFX., Competing Interests: Conflict of interest: S.S. Sohal reports an honorarium for lectures from Chiesi, travel support from Chiesi, AstraZeneca and GSK, and research grants from Boehringer Ingelheim and Lung Therapeutics, outside the submitted work; and has served on the Small Airway Advisory Board for Chiesi Australia for which an honorarium has been received, all disclosures made outside the submitted work. Conflict of interest: The remaining authors have nothing to disclose., (Copyright ©The authors 2024.)

Background : Idiopathic pulmonary fibrosis (IPF) is an irreversible lung fibrotic disorder of unknown cause. It has been reported that bacterial and viral co-infections exacerbate disease pathogenesis. These pathogens use adhesion molecules such as platelet activating factor receptor (PAFR) and intercellular adhesion molecule-1 (ICAM-1) to gain cellular entry, causing infections. Methods : Immunohistochemical staining was carried out for lung resections from IPF patients (n = 11) and normal controls (n = 12). The quantification of PAFR and ICAM-1 expression is presented as a percentage in the small airway epithelium. Also, type 2 pneumocytes and alveolar macrophages were counted as cells per mm 2 of the parenchymal area and presented as a percentage. All image analysis was done using Image Pro Plus 7.0 software. Results : PAFR expression significantly increased in the small airway epithelium ( p < 0.0001), type 2 pneumocytes ( p < 0.0001) and alveolar macrophages ( p < 0.0001) compared to normal controls. Similar trend was observed for ICAM-1 expression in the small airway epithelium ( p < 0.0001), type 2 pneumocytes ( p < 0.0001) and alveolar macrophages ( p < 0.0001) compared to normal controls. Furthermore, the proportion of positively expressed type 2 pneumocytes and alveolar macrophages was higher in IPF than in normal control. Conclusions : This is the first study to show PAFR and ICAM-1 expression in small airway epithelium, type 2 pneumocytes and alveolar macrophages in IPF. These findings could help intervene microbial impact and facilitate management of disease pathogenesis.

Background: COPD patients suffer from dysregulated and suppressed immune functionality, determined by their loss of degranulating capacity. Here we provide crucial information on the presence of degranulated mast cells (MCs) in COPD airways and demonstrate their relationship to lung physiology and airway remodelling., Methods: Small airway lung resections from non-smoking controls (NC), normal lung function smokers (NLFS), small airway disease (SAD), and mild-to-moderate COPD current smokers (COPD-CS) and ex-smokers (COPD-ES) were dual immuno-stained with MC tryptase and degranulation marker lysosome-associated membrane protein (LAMP)-1. Total MCs, degranulating MCs and non-MCs were enumerated in small airway epithelium and subepithelium, and in alveolar septa., Results: In the small airway wall subepithelial areas, COPD-CS and COPD-ES patients had significantly lower MCs than the NC group (p<0.05), although the numbers were considerably higher in the small airway epithelium (p<0.01). Degranulating non-MCs were higher in SAD (p<0.05) than in COPD in the small airway subepithelium. In contrast, there were significant increases in total MCs (degranulated and non-degranulated) and degranulated non-MCs in the alveolar septum of COPD patients compared with the NC group (p<001). The lower numbers of MCs in the subepithelium correlated with lower forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) and forced expiratory flow at 25-75% of FVC (FEF 25-75% ), higher smoking rates in COPD patients, and increased small airway wall thickness and extracellular matrix. The increase in MCs in the alveolar septum negatively correlated with FEF 25-75 % ., Conclusions: This study is the first to assess the differential pattern of MC, degranulating MC and non-MC populations in the small airways and alveoli of COPD patients. The spatial positioning of the MCs within the airways showed variable correlations with lung function., Competing Interests: Conflict of interest: M.S. Eapen is currently a full-time employee in Mucpharm Pty Ltd; the work presented was not carried out as part of his employment with Mucpharm Pty Ltd. Conflict of interest: S.S. Sohal has served on the Small Airway Advisory Board for Chiesi Australia and has received the honorarium, outside the submitted work; reports travel support from Chiesi, GSK and AstraZeneca, outside the submitted work; reports a lecture honorarium from Chiesi, outside the submitted work; and has received a research grant from Lung Therapeutics, outside the submitted work. Conflict of interest: All the other authors do not have any conflict of interest to declare., (Copyright ©The authors 2024.)

Background: We have previously reported that endothelial-to-mesenchymal transition (EndMT) is an active process in patients with idiopathic pulmonary fibrosis (IPF) contributing to arterial remodelling. Here, we aim to quantify drivers of EndMT in IPF patients compared to normal controls (NCs). Methods: Lung resections from thirteen IPF patients and eleven NCs were immunohistochemically stained for EndMT drivers, including TGF-β1, pSmad-2/3, Smad-7, and β-catenin. Intima, media, and adventitia were analysed for expression of each EndMT driver in pulmonary arteries. Computer- and microscope-assisted Image ProPlus7.0 image analysis software was used for quantifications. Results: Significant TGF-β1, pSmad-2/3, Smad-7, and β-catenin expression was apparent across all arterial sizes in IPF ( p < 0.05). Intimal TGF-β1, pSmad-2/3, Smad-7, and β-catenin were augmented in the arterial range of 100-1000 μm ( p < 0.001) compared to NC. Intimal TGF-β1 and β-catenin percentage expression showed a strong correlation with the percentage expression of intimal vimentin (r' = 0.54, p = 0.05 and r' = 0.61, p = 0.02, respectively) and intimal N-cadherin (r' = 0.62, p = 0.03 and r' = 0.70, p = 0.001, respectively). Intimal TGF-β1 and β-catenin expression were significantly correlated with increased intimal thickness as well (r' = 0.52, p = 0.04; r' = 0.052, p = 0.04, respectively). Moreover, intimal TGF-β1 expression was also significantly associated with increased intimal elastin deposition (r' = 0.79, p = 0.002). Furthermore, total TGF-β1 expression significantly impacted the percentage of DLCO (r' = -0.61, p = 0.03). Conclusions: This is the first study to illustrate the involvement of active TGF-β/Smad-2/3-dependent and β-catenin-dependent Wnt signalling pathways in driving EndMT and resultant pulmonary arterial remodelling in patients with IPF. EndMT is a potential therapeutic target for vascular remodelling and fibrosis in general in patients with IPF.