{"@context":{"@language":"en","Affiliation":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","AggregatedSourceRepository":"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider","Citation":"https:\/\/open.library.ubc.ca\/terms#identifierCitation","Contributor":"http:\/\/purl.org\/dc\/terms\/contributor","Creator":"http:\/\/purl.org\/dc\/terms\/creator","DateAvailable":"http:\/\/purl.org\/dc\/terms\/issued","DateIssued":"http:\/\/purl.org\/dc\/terms\/issued","Description":"http:\/\/purl.org\/dc\/terms\/description","DigitalResourceOriginalRecord":"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO","FullText":"http:\/\/www.w3.org\/2009\/08\/skos-reference\/skos.html#note","Genre":"http:\/\/www.europeana.eu\/schemas\/edm\/hasType","IsShownAt":"http:\/\/www.europeana.eu\/schemas\/edm\/isShownAt","Language":"http:\/\/purl.org\/dc\/terms\/language","PeerReviewStatus":"https:\/\/open.library.ubc.ca\/terms#peerReviewStatus","Provider":"http:\/\/www.europeana.eu\/schemas\/edm\/provider","Publisher":"http:\/\/purl.org\/dc\/terms\/publisher","PublisherDOI":"https:\/\/open.library.ubc.ca\/terms#publisherDOI","Rights":"http:\/\/purl.org\/dc\/terms\/rights","RightsURI":"https:\/\/open.library.ubc.ca\/terms#rightsURI","ScholarlyLevel":"https:\/\/open.library.ubc.ca\/terms#scholarLevel","Subject":"http:\/\/purl.org\/dc\/terms\/subject","Title":"http:\/\/purl.org\/dc\/terms\/title","Type":"http:\/\/purl.org\/dc\/terms\/type","URI":"https:\/\/open.library.ubc.ca\/terms#identifierURI","SortDate":"http:\/\/purl.org\/dc\/terms\/date"},"Affiliation":[{"@value":"Medicine, Faculty of","@language":"en"},{"@value":"Non UBC","@language":"en"},{"@value":"Anesthesiology, Pharmacology and Therapeutics, Department of","@language":"en"}],"AggregatedSourceRepository":[{"@value":"DSpace","@language":"en"}],"Citation":[{"@value":"Journal of Clinical Medicine 13 (7): 2126 (2024)","@language":"en"}],"Contributor":[{"@value":"University of British Columbia. Centre for Heart Lung Innovation","@language":"en"}],"Creator":[{"@value":"Shahzad, Affan Mahmood","@language":"en"},{"@value":"Lu, Wenying","@language":"en"},{"@value":"Dey, Surajit","@language":"en"},{"@value":"Bhattarai, Prem","@language":"en"},{"@value":"Gaikwad, Archana Vijay","@language":"en"},{"@value":"Jaffar, Jade","@language":"en"},{"@value":"Westall, Glen","@language":"en"},{"@value":"Sutherland, Darren","@language":"en"},{"@value":"Singhera, Gurpreet K.","@language":"en"},{"@value":"Hackett, Tillie-Louise","@language":"en"},{"@value":"Eapen, Mathew Suji","@language":"en"},{"@value":"Sohal, Sukhwinder Singh","@language":"en"}],"DateAvailable":[{"@value":"2024-04-26T16:16:22Z","@language":"en"}],"DateIssued":[{"@value":"2024-04-06","@language":"en"}],"Description":[{"@value":"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\u20131) 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\u20131 expression is presented as a percentage in the small airway epithelium. Also, type 2 pneumocytes and alveolar macrophages were counted as cells per mm2 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\u20131 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\u20131 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.","@language":"en"}],"DigitalResourceOriginalRecord":[{"@value":"https:\/\/circle.library.ubc.ca\/rest\/handle\/2429\/88014?expand=metadata","@language":"en"}],"FullText":[{"@value":"Citation: Shahzad, A.M.; Lu, W.; Dey,S.; Bhattarai, P.; Gaikwad, A.V.; Jaffar,J.; Westall, G.; Sutherland, D.;Singhera, G.K.; Hackett, T.-L.; et al.Platelet Activating Factor Receptorand Intercellular AdhesionMolecule\u20131 Expression Increases inthe Small Airway Epithelium andParenchyma of Patients withIdiopathic Pulmonary Fibrosis:Implications for MicrobialPathogenesis. J. Clin. Med. 2024, 13,2126. https:\/\/doi.org\/10.3390\/jcm13072126Academic Editor: Hiroshi IshiiReceived: 5 March 2024Revised: 25 March 2024Accepted: 4 April 2024Published: 6 April 2024Copyright: \u00a9 2024 by the authors.Licensee MDPI, Basel, Switzerland.This article is an open access articledistributed under the terms andconditions of the Creative CommonsAttribution (CC BY) license (https:\/\/creativecommons.org\/licenses\/by\/4.0\/).Journal ofClinical MedicineArticlePlatelet Activating Factor Receptor and Intercellular AdhesionMolecule\u20131 Expression Increases in the Small AirwayEpithelium and Parenchyma of Patients with IdiopathicPulmonary Fibrosis: Implications for Microbial PathogenesisAffan Mahmood Shahzad 1,2,\u2020, Wenying Lu 1,3,\u2020 , Surajit Dey 1, Prem Bhattarai 1 , Archana Vijay Gaikwad 1,3,Jade Jaffar 4,5 , Glen Westall 4,5, Darren Sutherland 6,7, Gurpreet Kaur Singhera 6,7 , Tillie-Louise Hackett 6,7 ,Mathew Suji Eapen 1,3 and Sukhwinder Singh Sohal 1,3,*1 Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences,College of Health and Medicine, University of Tasmania, Launceston, TAS 7248, Australia2 Medical School, Oceania University of Medicine, Apia WS1330, Samoa3 National Health and Medical Research Council (NHMRC) Centre of Research Excellence (CRE) in PulmonaryFibrosis, Respiratory Medicine and Sleep Unit, Royal Prince Alfred Hospital,Camperdown, NSW 2050, Australia4 Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital,Melbourne, VIC 3004, Australia5 Department of Immunology and Pathology, Monash University, Melbourne, VIC 3800, Australia6 Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia,Vancouver, BC V6T 1Z4, Canada7 Centre for Heart Lung Innovation, St. Paul\u2019s Hospital, Vancouver, BC V6Z 1Y6, Canada* Correspondence: sukhwinder.sohal@utas.edu.au; Tel.: +61-3-6324-5434\u2020 These authors contributed equally to this work.Abstract: Background: Idiopathic pulmonary fibrosis (IPF) is an irreversible lung fibrotic disorderof unknown cause. It has been reported that bacterial and viral co-infections exacerbate diseasepathogenesis. These pathogens use adhesion molecules such as platelet activating factor receptor(PAFR) and intercellular adhesion molecule-1 (ICAM\u20131) 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\u20131 expression is presented as apercentage in the small airway epithelium. Also, type 2 pneumocytes and alveolar macrophages werecounted as cells per mm2 of the parenchymal area and presented as a percentage. All image analysiswas done using Image Pro Plus 7.0 software. Results: PAFR expression significantly increased inthe 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\u20131 expression in thesmall 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 type2 pneumocytes and alveolar macrophages was higher in IPF than in normal control. Conclusions:This is the first study to show PAFR and ICAM\u20131 expression in small airway epithelium, type 2pneumocytes and alveolar macrophages in IPF. These findings could help intervene microbial impactand facilitate management of disease pathogenesis.Keywords: alveolar macrophages; ICAM\u20131; idiopathic pulmonary fibrosis; infections; PAFR; type2 pneumocytes1. IntroductionIdiopathic pulmonary fibrosis (IPF) is a rare, chronic interstitial lung disease (ILD)associated with irreversible lung fibrosis with an unknown cause [1\u20133]. IPF has a high mor-tality rate with a median survival of 2\u20135 years from diagnosis [1,2,4]. It is commonly seenJ. Clin. Med. 2024, 13, 2126. https:\/\/doi.org\/10.3390\/jcm13072126 https:\/\/www.mdpi.com\/journal\/jcmJ. Clin. Med. 2024, 13, 2126 2 of 14in the older demographic, particularly in individuals aged 50 and above [5,6]. Some typicalclinical characteristics are chronic cough, chronic exertional dyspnea, digital clubbing, andbibasilar inspiratory crackles [7,8]. Although unknown etiology, infectious agents, genetics,tobacco, and environmental factors are related to IPF pathogenesis [1,5,9]. When irritantspersist, the dysregulated repair mechanisms contribute to excess collagen deposition andfibrotic scar tissue formation [10\u201312]. As a result, the common histopathological feature ofIPF is fibrosis, including the characteristic honeycombing appearance [1,13,14].Studies over the years have discovered that IPF patients suffer from respiratory-associated infections that contribute to worsened disease pathogenesis [15\u201317]. It has beenreported that IPF patients have a higher bacterial load in bronchoalveolar lavage (BAL)fluid than healthy or chronic obstructive pulmonary disease (COPD) cohorts [15,16]. Themost common bacterial genus in IPF is Streptococcus, Hemophilus, Pseudomonas, Neisseria,and Veillonella [15,16]. Moreover, research has also found that some viruses, namely thehuman rhinovirus (HRV) and influenza virus, are involved in affecting patients [15,18]. Asynergy between bacteria and virus has been documented, detailing that it causes superin-fections that exacerbate IPF progression, reducing lung function and lowering the survivalrate compared to uninfected patients [15]. Similarly, SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) has been shown to upregulate in patients with IPF, increasingtheir susceptibility to COVID-19 [15,19]. With this knowledge, we wanted to investigate thepresence of other potential microbial receptors, such as platelet-activating factor receptor(PAFR) and intracellular adhesion molecule\u20131 (ICAM\u20131), and their possible involvement inmicrobial entry into host cells [20\u201323]. An increase in such microbial receptors is bound tomake the patients susceptible to infections that further drive unwarranted inflammationand remodeling changes [24,25].Platelet-activating factor (PAF) functions as a known mediator which causes plateletaggregation, blood vessel dilation, inflammation, allergic reactions, and shock [26,27]. PAFis produced by many cells, such as platelets, endothelial cells, fibroblasts, macrophages,monocytes, mast cells, and some immune cells, such as neutrophils and eosinophils [26,27].PAF is mainly involved in inflammatory responses [26]. Under normal conditions, PAFbinds to PAFR, a G-protein-coupled seven-transmembrane receptor that activates severalpathways and synthesis of some inflammatory mediators such as prostaglandins andcytokines [e.g., tumour necrosis factor alpha (TNF-alpha) and interleukin 8 (IL\u20138)] [26,28].However, in terms of bacterial involvement, a study on COPD found that upregulatedPAFR in epithelium helps Streptococcus pneumoniae to interact and colonize epithelial cellswith the help of phosphorylcholine (ChoP) [23,29,30]. The ChoP is a molecular mimic ofPAF found in S. pneumoniae walls and on some strains of Hemophilus influenzae, Pseudomonasaeruginosa, and Acinetobacter baumannii [23,31]. As a result, bacteria with ChoP binds toPAFR, outcompeting PAF (natural ligand), leading to bacterial transmigration across thehost cells [30].ICAM\u20131is a cell surface glycoprotein naturally expressed in low amounts in variouscells, including immune, endothelial, and epithelial cells [32,33]. ICAM\u20131is overexpressedduring an inflammatory response and cytokine upregulation [e.g., interferon beta (IFN-\u03b2),IL\u20138] [32,33]. The receptor has several roles, primarily regulating leukocyte movementand adhesion with blood vessels and inflammation [33,34]. It is expressed in inflammatorymacrophages tasked with phagocytosis [33,34]. However, recent research showed thatsome viruses, such as HRV, use ICAM\u20131as a receptor to release their RNA in the hostcells of patients [33,35,36]. The uncoating of viral RNA leads to genome replication in theepithelium, ultimately causing infection and exacerbating IPF pathogenesis [16,37,38].In COPD, we have previously reported significantly increased PAFR expression insmall airways and lung parenchyma, especially in smokers, compared to normal tissue [39].It indicates that irritants causing inflammation upregulates microbial receptors in sitessuch as small airways and lung parenchyma, enabling microbial attachment [26,32]. Wefound similar changes for ICAM\u20131too in smokers and patients with COPD [36]. Therefore,J. Clin. Med. 2024, 13, 2126 3 of 14we wanted to explore if this activity is evident in IPF and potentially provide a betterunderstanding of microbial implications in this disease.We hypothesize that PAFR and ICAM\u20131 expression is upregulated in IPF, whichact as adhesion sites for bacteria\/viruses, increasing the vulnerability to infection in IPFpatients. This study aims to determine the expression of PAFR and ICAM\u20131in small airwaysand lung parenchymal areas mainly in type 2 pneumocytes and alveolar macrophages ofpatients with IPF compared to normal lungs to explain if IPF patients are more susceptibleto infections.2. Materials and Methods2.1. Patient DemographicsSurgically resected human lung tissue from informed consent patients with end-stageIPF (n = 11) were obtained from Alfred Health (Ethics approval ID: 336-13) at the time oflung transplantation. Normal controls (NC, n = 12) were provided by James Hogg LungRegistry (Ethics approval ID: H00-50110). The NC lung tissues were from patients whohad died of a cause other than respiratory disease (Table 1).Table 1. Patient demographics and lung function parameters.Normal Control (NC) IPFFactors Values *Total Number (n) 12 11Age (Years) 39 \u00b1 16.5 63 \u00b1 4.85Gender (Female\/Male) 6\/6 5\/6Smoking status (n): Currentsmoker\/Ex-smoker\/Never Non-smoker 0\/5\/6Smoking Packs Per Year - 16.55 \u00b1 22.56Respiratory Function ParametersFEV1 (L) * NA 1.67 \u00b1 0.42FVC (L) \u2020 NA 1.89 \u00b1 0.45DLCO \u2021 (mL\/min\/mmHg) NA 5.98 \u00b1 3.12DLCO (%) NA 25.33 \u00b1 12.30Values * presented as mean \u00b1 standard deviation (SD); NA, not available; FEV1 *, forced expiratory volume1;FVC \u2020, forced vital capacity; DLCO \u2021, Diffusing capacity for carbon monoxide.2.2. Immunohistochemical StainingParaffin-embedded lung tissue was cut to 3 \u00b5m. Tissues were dewaxed in the fol-lowing reagents in order of two changes of xylene, two changes of absolute ethanol, 70%ethanol (v\/v) in deionized water. These tissue sections were treated with target antigenretrieval (pH 6) in a Decloaking Chamber\u2122 (Biocare Medical, Melbourne, VIC, Australia)at 110 \u25e6C for 15 min, followed by 3% hydrogen peroxide (v\/v) (H1009, Sigma-Aldrich,Bayswater, VIC, Australia) in deionized water for 18 to 20 min. A protein block solutionwas applied for 5 min to the tissues before applying PAFR primary antibody. The tissuesections were immunohistochemically stained using primary antibodies: PAFR monoclonalantibody (1:50, 160,600, Cayman Chemical Company, Redfern, NSW, Australia) and ICAM\u20131 monoclonal antibody (1:100, MA5407, Invitrogen, Melbourne, VIC, Australia). Negativecontrol antibody: mouse IgG1 monoclonal antibody (PAFR 1:50 and ICAM\u20131 1:100 dilution;X0931, Agilent Technologies, Mulgrave, VIC, Australia) incubated in an IHC humiditychamber for 90 min at ambient temperature, followed by peroxidase-conjugated polymerbackbone-carried secondary antibodies for 30 min and visualized by 3-3\u2032-diaminobenzidine(DAB) staining for 10 min (EnVisionTM Detection SystemsTM, K5007, Dako, Mulgrave,VIC, Australia), and hematoxylin stain was applied for nuclear staining.J. Clin. Med. 2024, 13, 2126 4 of 142.3. Small Airway and Lung Parenchyma QuantificationImages were taken using a Leica DM500 microscope and Leica ICC50W camera (Leica,Macquarie Park, NSW, Australia), and analysis was performed using Image Pro Plus 7.0software (Media Cybernetics, Rockville, MD, USA). The observer was blinded to patientsand diagnosis. Small airway epithelium and lung parenchyma areas were captured at40\u00d7 and 20\u00d7 magnification, respectively, and strictly avoiding any overlapping images.Then, eight images were randomly selected using online random generator software formeasurement. The quantification of PAFR and ICAM\u20131 expression on the small airwayepithelium is presented as a percentage of the epithelial layer. Also, type 2 pneumocytesand alveolar macrophages were counted as cells per mm2 of the parenchymal area andpresented as a percentage.2.4. Statistical AnalysisFollowing normality check, non-parametric analysis of variance were performed usingthe unpaired one-tailed Mann-Whitney Test; specific group differences without correctionfor multiple comparisons were assessed using a two-way ANOVA test with Fisher\u2019s LSDtest. The statistical analysis was completed using GraphPad Prism V9.1 (GraphPad SoftwareInc., La Jolla, CA, USA), with a p-value \u2264 0.05 considered statistically significant.3. Results3.1. Comparison between Primary Antibody and Negative Antibody Staining on NC and IPFLung TissuePAFR and ICAM\u20131 positive expression in small airways (SA) epithelium and lungparenchyma in IPF and NC are shown in Figures 1A and 2B. PAFR and ICAM\u20131 wereshowing strong positive expression in epithelium (in brown) in IPF compared to NC, andsimilarly more positive expression in type 2 pneumocytes and alveolar macrophages in IPFthan in NC. Negative control staining is shown in Figures 1B and 2B, which indicate thatthere is no false staining.J. Clin. Med. 2024, 13, x FOR PEER REVIEW 5 of 15    Figure 1. Human resected lung tissue showing positive staining (in brown) for (platelet activating factor, PAFR) (A) and negative mouse IgG1 antibody staining (B). (A i, v, ix) PAFR positive in small airway (SA) epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in normal control (NC), respectively and (A ii, vi, x) PAFR positive in SA epithelium, type 2 pneu-mocytes (green arrows), and alveolar macrophages (red arrows) in patients with idiopathic pulmo-nary fibrosis (IPF), respectively. (B iii, vii, xi) negative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in NC, respectively and (B iv, viii, xii) neg-ative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients with IPF, respectively. Magnification: SA epithelium (40\u00d7), lung parenchyma (20\u00d7) and insert image (60\u00d7).  Figure 2. Human resected lung tissue showing positive staining (in brown) for (intercellular adhe-sion molecule\u20131, ICAM\u20131) (A) and negative mouse IgG1 antibody staining (B). (A i, v, ix) ICAM\u20131 Figure 1. Human resected lung tissue showing positive staining (in brown) for (platelet activatingfactor reporter, PAFR) (A) and negative mouse IgG1 antibody staining (B). ((A) (i,v,ix)) PAFR positivein small airway (SA) epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (redJ. Clin. Med. 2024, 13, 2126 5 of 14arrows) in normal control (NC), respectively and ((A) (ii,vi,x)) PAFR positive in SA epithelium, type2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients with idiopathicpulmonary fibrosis (IPF), respectively. ((B) (iii,vii,xi)) negative IgG1 in SA epithelium, type 2 pneumo-cytes (green arrows), and alveolar macrophages (red arrows) in NC, respectively and ((B) (iv,viii,xii))negative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (redarrows) in patients with IPF, respectively. Magnification: SA epithelium (40\u00d7), lung parenchyma(20\u00d7) and insert image (60\u00d7).J. Clin. Med. 2024, 13, x FOR PEER REVIEW 5 of 15    Figure 1. Human resected lung tissue showing positive staining (in brown) for (platelet activating factor, PAFR) (A) and negative mouse IgG1 antibody staining (B). (A i, v, ix) PAFR positive in small airway (SA) epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in normal control (NC), respectively and (A ii, vi, x) PAFR positive in SA epithelium, type 2 pneu-mocytes (gre n arrows), and alveolar macrophages (red arrows) in patients with idiopathic pulmo-nary fibrosis (IPF), respectively. (B iii, vii, x ) negative IgG1 in SA epithelium, type 2 pn umocytes (green arrows), and alveolar macrophages (red arrows) in NC, respectively and (B iv, viii, xii) neg-ative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients with IPF, respectively. Magnification: SA epithelium (40\u00d7), lung parenchyma (20\u00d7) and insert image (60\u00d7).  Figure 2. Human resected lung tissue showing positive staining (in brown) for (intercellular adhesionmolecule\u20131, ICAM\u20131) (A) and negative mouse IgG1 antibody staining (B). ((A) (i,v,ix)) ICAM\u20131 posi-tive in small airway (SA) epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages(red arrows) in normal control (NC), respectively and ((A) (ii,vi,x)) ICAM\u20131positive in SA epithe-lium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients withidiopathic pulmonary fibrosis (IPF), respectively. ((B) (iii,vii,xi)) negative IgG1 in SA epithelium,type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in NC, respectively and((B) (iv,viii,xii)) negative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolarmacrophages (red arrows) in patients with IPF, respectively. Magnification: SA epithelium (40\u00d7),lung parenchyma (20\u00d7) and insert image (60\u00d7).3.2. Quantification of PAFR Expression in Small Airway (SA) Epithelium, Type 2 Pneumocytesand Alveolar MacrophagesPAFR expression was prominent on the apical surface of small airway epithelial cellsin IPF tissue, and mildly covering the whole perimeter of the cells (Figure 3A). There wasnegligible PAFR staining on the normal controls with patterns illustrated (Figure 3A). Wefurther observed the expression of PAFR in the lung parenchyma, which increased mainlyin type 2 pneumocytes and alveolar macrophages in IPF tissue compared to NC tissue(Figure 3A).J. Clin. Med. 2024, 13, 2126 6 of 14J. Clin. Med. 2024, 13, x FOR PEER REVIEW 6 of 15   positive in small airway (SA) epithelium, type 2 pneumocytes (green arrows), and alveolar macro-phages (red arrows) in normal control (NC), respectively and (A ii, vi, x) ICAM\u20131positive in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients with idiopathic pulmonary fibrosis (IPF), respectively. (B iii, vii, xi) negative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in NC, respectively and (B iv, viii, xii) negative IgG1 in SA epithelium, type 2 pneumocytes (green arrows), and alveolar macrophages (red arrows) in patients with IPF, respectively. Magnification: SA epithelium (40\u00d7), lung parenchyma (20\u00d7) and insert image (60\u00d7). 3.2. Quantification of PAFR Expression in Small Airway (SA) Epithelium, Type 2 Pneumocytes and Alveolar Macrophages PAFR expression was prominent on the apical surface of small airway epithelial cells in IPF tissue, and mildly covering the whole perimeter of the cells (Figure 3A). There was negligible PAFR staining on the normal controls with patterns illustrated (Figure 3A). We further observed the expression of PAFR in the lung parenchyma, which increased mainly in type 2 pneumocytes and alveolar macrophages in IPF tissue compared to NC tissue (Figure 3A).  Figure 3. (A) Immunohistochemical (IHC) staining with primary antibody PAFR of normal control (NC) and idiopathic pulmonary fibrosis (IPF) tissue. The IHC staining compares (A i, ii) small air-way (SA) epithelium in NC and IPF respectively, (A iii, iv) type 2 pneumocytes (positive\u2014red ar-rows, negative\u2014orange arrows) in NC and IPF respectively, and (A v, vi) alveolar macrophages (positive\u2014green arrows, negative\u2014bright pink arrows) in NC and IPF respectively. (B) Percentage Figure 3. (A) Immunohistochemical (IHC) staining with primary antibody PAFR of normal control(NC) and idiopathic pulmonary fibrosis (IPF) tissue. The IHC staining compares ((A) (i,ii)) smallairway (SA) epithelium in NC and IPF respectively, ((A) (iii,iv)) type 2 pneumocytes (positive\u2014redarrows, negative\u2014orange arrows) in NC and IPF respectively, and ((A) (v,vi)) alveolar macrophages(positive\u2014green arrows, negative\u2014bright pink arrows) in NC and IPF respectively. (B) Percentageexpression of PAFR in epithelium, type 2 pneumocytes, and alveolar macrophages. Elevated SAepithelium PAFR expression (p < 0.0001) in IPF compared to NC. Elevated PAFR expression in type2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) in IPF. (C) The number of PAFRpositively expressed type 2 pneumocytes (p = 0.0017) and alveolar macrophages (p = 0.0017) permm2 of alveolar area. (D) The number of PAFR negative type 2 pneumocytes (p = 0.0005) andalveolar macrophages (p = 0.0005) per mm2 of alveolar area. Magnification: SA epithelium and lungparenchyma (60\u00d7).The percentage expression of PAFR significantly upregulated in the small airwayepithelium in IPF lung tissue (median 8.33%, range 3.80\u201342.7%) compared to NC lungtissue (median 1.43%, range 0.352\u20135.85, p < 0.0001) (Figure 3B). In addition, the PAFRpositive expression in alveolar type 2 pneumocytes of IPF showed a significantly highpercentage (median 78.1%, range 61.2\u201396.0%) compared to NC (median 40.1%, range15.2\u201358.2%, p < 0.0001) (Figure 3B). The number of PAFR positive type 2 pneumocytes permm2 in alveolar area is significantly higher in IPF (median 498,525 cells per mm2, range189,449\u20131,463,564 cells per mm2) compared to NC (median 227,150 cells per mm2, rangeJ. Clin. Med. 2024, 13, 2126 7 of 1434,483\u2013463,444 cells per mm2, p = 0.0017) (Figure 3C), and in contrast, the number of PAFRnegative type 2 pneumocytes is significantly higher in NC (median 334,189 cells per mm2,range 158,333\u2013445,101 cells per mm2) compared to IPF (median 96,519 cells per mm2, range20,930\u2013825,189 cells per mm2, p = 0.0017) (Figure 3D).We also observed significant upregulation of PAFR expression in alveolar macrophages(median 98.3%, range 63.2\u2013100%) compared to NC (median 43.7%, range 27.8\u201370.2%,p < 0.0001) (Figure 3B). Similarly, the number of PAFR positive alveolar macrophages issignificantly higher in IPF (median 157,029 cells per mm2, range 25,707\u20131,432,457 cells permm2) compared to NC (median 74,713 cells per mm2, range 22,630\u2013150,741 cells per mm2,p = 0.0005) (Figure 3C). The number of PAFR negative alveolar macrophages is significantlyhigher in NC (median 72,072 cells per mm2, range 42,026\u2013169,141 cells per mm2) comparedto IPF (median 8048 cells per mm2, range 0\u201371,342 cells per mm2, p = 0.0005) (Figure 3D).3.3. Quantification of ICAM\u20131 Expression in Small Airway (SA) Epithelium, Type 2 Pneumocytesand Alveolar MacrophagesICAM\u20131 expression was prominent in the nucleus of small airway epithelial cells inIPF tissue, and moderate in cytoplasm (Figure 4A). There was mild ICAM\u20131 staining onthe normal controls with patterns illustrated (Figure 4A).J. Clin. Med. 2024, 13, x FOR PEER REVIEW 8 of 15    Figure 4. (A) Immunohistochemical (IHC) staining with primary antibody ICAM\u20131 of normal con-trol (NC) and idiopathic pulmonary fibrosis (IPF) tissue. The IHC staining compares: (A i, ii) small airway (SA) epithelium in NC and IPF respectively, (A iii, iv) type 2 pneumocytes (positive\u2014red arrows, negative\u2014orange arrows) in NC and IPF respectively, and (A v, vi) alveolar macrophages (positive\u2014green arrows, negative\u2014bright pink arrows) in NC and IPF respectively. (B) Percentage expression of ICAM\u20131 in epithelium, type 2 pneumocytes, and alveolar macrophages. Elevated SA epithelium ICAM\u20131 expression (p < 0.0001) in IPF compared to NC. Elevated ICAM\u20131 expression in type 2 pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) in IPF. (C) The number of ICAM\u20131 positively expressed type 2 pneumocytes (p = 0.0010) and alveolar macrophages (p = 0.0010) per mm2 of alveolar area. (D) The number of ICAM\u20131 negative type 2 pneumocytes (p = 0.0004) and alveolar macrophages (p = 0.0004) per mm2 of alveolar area. Magnification: SA epithelium and lung parenchyma (60\u00d7). The percentage expression of ICAM\u20131 significantly upregulated in the small airway epithelium in IPF lung tissue (median 16.3%, range 9.56% to 68.5%) compared to NC lung tissue (median 3.76%, range 1.17\u201314.1%, p < 0.0001) (Figure 4B). Compared to NC lung tissue (median 34.0%, range 25.6\u201351.7%), the ICAM\u20131 positive expression in type 2 pneu-mocytes of IPF alveolar tissue showed a significantly high percentage of type 2 cells in alveolar area (median 81.5%, range 56.3\u201398.8%, p < 0.0001) (Figure 4B). The number of ICAM\u20131 positive type 2 pneumocytes per mm2 in alveolar area is significantly higher in IPF (median 668,143 cells per mm2, range 168,350\u20132,253,902 cells per mm2) compared to NC (median 169,437 cells per mm2, range 28,250\u2013611,925 cells per mm2, p = 0.0010) (Figure 4C), and in contrast, the number of ICAM\u20131 negative type 2 pneumocytes is significantly higher in NC (median 307,286 cells per mm2, range 82,058\u2013713,380 cells per mm2) com-pared to IPF (median 69,772 cells per mm2, range 8858\u2013210,993 cells per mm2, p = 0.0010) (Figure 4D). i r . ( ) I nohistochemical (IHC) staining with primary antibody ICAM\u20131 of normal control(NC) and idiopathic pulmonary fibrosis (IPF) tissue. The IHC staining compares: ((A) (i,ii)) small airw y(SA) epithelium in NC and IPF respectively, ((A) (iii,iv)) type 2 pneumocytes (positive\u2014red arrows,negative\u2014orange arrows) in NC and IPF respectively, and ((A) (v,vi)) alveolar macrophages (positive\u2014green arrows, negative\u2014bright pink arrows) in NC and IPF respectively. (B) Percentage expression ofJ. Clin. Med. 2024, 13, 2126 8 of 14ICAM\u20131 in epithelium, type 2 pneumocytes, and alveolar macrophages. Elevated SA epitheliumICAM\u20131 expression (p < 0.0001) in IPF compared to NC. Elevated ICAM\u20131 expression in type 2pneumocytes (p < 0.0001) and alveolar macrophages (p < 0.0001) in IPF. (C) The number of ICAM\u20131positively expressed type 2 pneumocytes (p = 0.0010) and alveolar macrophages (p = 0.0010) permm2 of alveolar area. (D) The number of ICAM\u20131 negative type 2 pneumocytes (p = 0.0004) andalveolar macrophages (p = 0.0004) per mm2 of alveolar area. Magnification: SA epithelium and lungparenchyma (60\u00d7).The percentage expression of ICAM\u20131 significantly upregulated in the small airwayepithelium in IPF lung tissue (median 16.3%, range 9.56% to 68.5%) compared to NClung tissue (median 3.76%, range 1.17\u201314.1%, p < 0.0001) (Figure 4B). Compared to NClung tissue (median 34.0%, range 25.6\u201351.7%), the ICAM\u20131 positive expression in type 2pneumocytes of IPF alveolar tissue showed a significantly high percentage of type 2 cellsin alveolar area (median 81.5%, range 56.3\u201398.8%, p < 0.0001) (Figure 4B). The number ofICAM\u20131 positive type 2 pneumocytes per mm2 in alveolar area is significantly higher in IPF(median 668,143 cells per mm2, range 168,350\u20132,253,902 cells per mm2) compared to NC(median 169,437 cells per mm2, range 28,250\u2013611,925 cells per mm2, p = 0.0010) (Figure 4C),and in contrast, the number of ICAM\u20131 negative type 2 pneumocytes is significantly higherin NC (median 307,286 cells per mm2, range 82,058\u2013713,380 cells per mm2) compared to IPF(median 69,772 cells per mm2, range 8858\u2013210,993 cells per mm2, p = 0.0010) (Figure 4D).We also observed significant upregulation of ICAM\u20131 expression in alveolar macrophages(median 96.8%, range 91.7\u2013100%) compared to NC (median 72.5%, range 32.7\u201383.1%,p < 0.0001) (Figure 4B). The number of ICAM\u20131 positively expressed alveolar macrophagesis significantly higher in IPF (median 167,813 cells per mm2, range 56,157\u20131,209,594 cellsper mm2) compared to NC (median 71,714 cells per mm2, range 29,595\u201356,157 cells permm2, p = 0.0004) (Figure 4C). The number of ICAM\u20131 negative alveolar macrophagesis significantly higher in NC (median 42,969 cells per mm2, range 14,497\u2013150,936 cellsper mm2) compared to IPF (median 2891 cells per mm2, range 0\u201339,443 cells per mm2,p = 0.0004) (Figure 4D).3.4. Proportion of PAFR and ICAM\u20131 Expression in IPF and NC in the Alveolar AreaPAFR positive expression in type 2 pneumocytes in IPF elevated to 78.0% comparedto 40.4% in NC. On the other hand, PAFR negative expression in type 2 pneumocytes inIPF (22.0%) was lower than in NC (59.6%) (Figure 5A). Similarly, PAFR positive expressionin alveolar macrophages was higher in IPF (98.3%) compared to in NC (43.7%), whereasnegative PAFR expression in IPF (1.70%) was lower than in NC (56.3%) (Figure 5B). ICAM\u20131positive expression in type 2 pneumocytes in IPF elevated to 81.5% compared to 34.0%in NC. On the other hand, ICAM\u20131 negative in type 2 pneumocytes in IPF (18.5%) waslower than in NC (66.0%) (Figure 5C). Similarly, ICAM\u20131 positive expression in alveolarmacrophages was higher in IPF (96.8%) compared to in NC (71.3%), whereas negativeICAM\u20131 expression in IPF (3.20%) was lower than in NC (28.7%) (Figure 5D).J. Clin. Med. 2024, 13, 2126 9 of 14J. Clin. Med. 2024, 13, x FOR PEER REVIEW 9 of 15   We also observed significant upregulation of ICAM\u20131 expression in alveolar macro-phages (median 96.8%, range 91.7\u2013100%) compared to NC (median 72.5%, range 32.7\u201383.1%, p < 0.0001) (Figure 4B). The number of ICAM\u20131 positively expressed alveolar mac-rophages is significantly higher in IPF (median 167,813 cells per mm2, range 56,157\u20131,209,594 cells per mm2) compared to NC (median 71,714 cells per mm2, range 29,595\u201356,157 cells per mm2, p = 0.0004) (Figure 4C). The number of ICAM\u20131 negative alveolar macrophages is significantly higher in NC (median 42,969 cells per mm2, range 14,497\u2013150,936 cells per mm2) compared to IPF (median 2891 cells per mm2, range 0\u201339,443 cells per mm2, p = 0.0004) (Figure 4D). 3.4. Proportion of PAFR and ICAM\u20131 Expression in IPF and NC in the Alveolar Area PAFR positive expression in type 2 pneumocytes in IPF elevated to 78.0% compared to 40.4% in NC. On the other hand, PAFR negative expression in type 2 pneumocytes in IPF (22.0%) was lower than in NC (59.6%) (Figure 5A). Similarly, PAFR positive expression in alveolar macrophages was higher in IPF (98.3%) compared to in NC (43.7%), whereas negative PAFR expression in IPF (1.70%) was lower than in NC (56.3%) (Figure 5B). ICAM\u20131 positive expression in type 2 pneumocytes in IPF elevated to 81.5% compared to 34.0% in NC. On the other hand, ICAM\u20131 negative in type 2 pneumocytes in IPF (18.5%) was lower than in NC (66.0%) (Figure 5C). Similarly, ICAM\u20131 positive expression in alve-olar macrophages was higher in IPF (96.8%) compared to in NC (71.3%), whereas negative ICAM\u20131 expression in IPF (3.20%) was lower than in NC (28.7%) (Figure 5D).  Figure 5. Proportion of PAFR and ICAM\u20131 expression in type 2 pneumocytes and alveolar macro-phages in lung parenchyma. Elevated PAFR expression in IPF, (A) type 2 pneumocytes and (B) al-veolar macrophages. Elevated ICAM\u20131 expression in IPF, (C) type 2 pneumocytes and (D) alveolar macrophages. Figure 5. Proportion of PAFR and ICAM\u20131 expression in type 2 pneumocytes and alveolarmacrophages in lung parenchyma. Elevated PAFR expression in IPF, (A) type 2 pneumocytesand (B) alveolar macrophages. Elevated ICAM\u20131 expression in IPF, (C) type 2 pneumocytes and(D) alveolar macrophages.4. DiscussionThis is the first study reporting PAFR and ICAM\u20131 adhesion molecules in the smallairway epithelium and lung parenchyma of patients with IPF. We found that PAFR andICAM\u20131 expression increased in the small airway epithelium in IPF compared to normaltissues. In the lung parenchyma of IPF patients, we found elevated levels of PAFR andICAM\u20131 positive type 2 pneumocytes and alveolar macrophages. Furthermore, the pro-portions of positively and negatively expressed cells showed more positively expressedtype 2 pneumocytes and alveolar macrophages in IPF and fewer negatively expressed cellsin normal tissue. It could imply that although alveolar macrophages innately recognizepathogens but, cell activation and molecular receptor expression may provide shelter tomicrobes against inflammatory molecules, contributing to increased infection [39] Theabove results suggest that high molecule expression in IPF could be a significant link tomicrobes \u2018anchoring\u2019 and gaining cellular entry, increasing the risk of infection. As IPFis a chronic pulmonary disease, postulated risk factors involved in disease pathogenesisinclude environmental factors, tobacco, genetics, and infectious agents [1,5]. These irritantsresult in a chronic injury, and inflammation affecting the molecular and cellular mech-anisms [3,40]. In chronic disease, microbes infiltrate the exacerbated inflammation andfibroblast hyperproliferation, leading to excess collagen deposition [40,41].Phosphorylcholine (ChoP, a molecular mimic of PAF) is an important element ex-pressed on the outer surface of various microorganisms; the most commonly seen bacterialgenus in the respiratory tract is S. pneumoniae [42,43], H. influenzae [44] and P. aeruginosaand A. baumannii, which can direct interaction with host cells through ChoP [23,29,39,45].J. Clin. Med. 2024, 13, 2126 10 of 14The attachment of bacteria that express ChoP to the PAFR facilitates their adhesion to andinvasion into human cells [46,47]. The general mechanism of chronic bacterial colonizationhas been well documented in COPD but under-researched in IPF [39]. In our study, withincreased expression of PAFR in small airways indicates that these bacterial pathogens canadhere to small airway epithelium because the ChoP outcompetes the PAF (natural ligandto PAFR) and anchoring to PAFR may increase the risk of infection [15,16] (Figure 6A).J. Clin. Med. 2024, 13, x FOR PEER REVIEW 11 of 15    Figure 6. (A) S. pneumoniae and H. influenzae express phosphorylcholine (Chop) which binds to platelet acting factor receptor (PAFR), facilitating the adhesion, colonization and eventual transmi-gration into the human airway epithelial cells and type 2 pneumocytes, increasing the risk of infec-tion in patients. (B) Human Rhinovirus (HRV) uses intercellular adhesion molecule\u20131 (ICAM\u20131) as a receptor to anchor onto the airway epithelial cells and type 2 pneumocytes followed by uncoating of cell-invading virus, worsening disease pathogenesis. MAC\u20131; macrophage\u20131 antigen and LFA\u20131; leukocyte function-associated antigen. HRVs contribute to over 50% of upper respiratory tract infections [48], and HRV in-fections can lead to life-threatening effects worsen chronic respiratory disease, such as COPD, asthma, or cystic fibrosis [49]. The major signaling pathway for HRV cellular access occurs because pathogens use ICAM\u20131 as a receptor [32,50]. Specifically, the pathogen binds to leukocyte function-associated antigen 1 (LFA\u20131) or the macrophage\u20131 antigen (Mac\u20131), natural adhesion ligands [32,50] (Figure 6B). ICAM\u20131 becomes a major catalyst for the eventual uncoating of the cell-invading virus, potentially exacerbating IPF patho-genesis [16,32]. The role of ICAM\u20131 in COPD has been investigated by our research group and we have showed that the receptor was highly expressed in COPD smoking cohort [36]. The expression patterns were prominent in the airways, especially on goblet cells and sub-mucosal glands, and could be a potential risk factor of infection by common respira-tory viral and bacterial pathogens [36]. These biochemical mechanisms documented in other diseases shine a light on our findings as we believe our data bridges the gap in this area by demonstrating the abovementioned microbial activity in IPF, but this warrants further research. Furthermore, our research group previously reported that ACE2, Furin and Trans-membrane protease serine 2 (TMPRSS2) receptors are upregulated in IPF facilitating Figure 6. (A) S. pneumoniae and H. influenzae express phosphorylcholine (Chop) which binds to plateletacting factor receptor (PAFR), facilitating the adhesion, colonization and eventual transmigrationinto the human airway epithelial cells and type 2 pneumocytes, increasing the risk of infectionin patients. (B) Human Rhinovirus (HRV) uses intercellular adhesion molecule\u20131 (ICAM\u20131) as areceptor to anchor onto the airway epithelial cells a d type 2 pneu ocytes followed by uncoating ofcell-invading virus, worsening diseas pathogenesis. MAC\u20131; macrophage\u20131 antigen and LFA\u20131;leukocyte function-associated antigen.HRVs contribute to over 50% of upper respiratory tract infections [48], and HRV in-fections can lead to life-threatening effects that worsen chronic respiratory disease, suchas COPD, asthma, or cystic fibrosis [49]. The major signaling pathway for HRV cellu-lar access occurs because pathogens use ICAM\u20131 as a receptor [32,50]. Specifically, thepathogen binds to leukocyte function-associated antigen 1 (LFA\u20131) or the macrophage\u20131antigen (Mac\u20131), natural adhesion ligands [32,50] (Figure 6B). ICAM\u20131 becomes a majorcatalyst for the eventual uncoating of the cell-invading virus, potentially exacerbating IPFpathogenesis [16,32]. The role of ICAM\u20131 in COPD has been investigated by our researchgroup and we have showed that the receptor was highly expressed in COPD smokingcohort [36]. The expression patterns were prominent in the airways, especially on gobletJ. Clin. Med. 2024, 13, 2126 11 of 14cells and sub-mucosal glands, and could be a potential risk factor of infection by commonrespiratory viral and bacterial pathogens [36]. These biochemical mechanisms documentedin other diseases shine a light on our findings as we believe our data bridges the gap inthis area by demonstrating the abovementioned microbial activity in IPF, but this warrantsfurther research.Furthermore, our research group previously reported that ACE2, Furin and Trans-membrane protease serine 2 (TMPRSS2) receptors are upregulated in IPF facilitating SARS\u2013CoV\u20132 infection [19]. We have reported similar findings in smokers and patients withCOPD. Small airway epithelium, type 2 pneumocytes and alveolar macrophages werehighly positive for these markers [51]. Subsequently the expression patterns of variousmicrobial receptors discussed above could suggest that IPF patients are at a higher risk ofinfections compared to healthy people.Further, Moghoofiel et al. & Mostafaei et al. investigated bacterial coinfection in IPFand its possible role in disease progression. Their results demonstrated that coinfections(bacterial and viral) significantly exacerbate disease progression, enhancing the risk of deathin IPF patients [15,16]. This investigation served potential usefulness in understanding theunderlying mechanisms in IPF infections and could provide insights in future therapeutics.Similar views shared by Santos et al. that if interventions can decrease or prevent pathogenadherence to the epithelium, it could protect high-risk populations before the disease hasprogressed [52].Moreover, an animal model study by Iovino et al. investigated the role of PAFR inpneumococcal disease. The study demonstrated that although the absence of the PAFRgene (Pafr-\/-) mice had higher bacterial (S. pneumoniae) growth in the lungs at 24 h post-inoculation, the wild-type (WT) mice had higher bacteremia after 48 h [53]. In WT, bacteriadispersed throughout the body and the central nervous system (CNS) compared to re-stricted local infection in the pulmonary area of Pafr-\/- mice [30,54].Associated animal model research on the role of PAFR in pneumococcal pneumoniafound that all WT mice died earlier after infection [53]. At the same time, the mortality ratewas delayed and reduced in Pafr-\/- mice [30,53]. These models show that Pafr-\/- mice hada lower chance of developing an infection, especially when using PAFR antagonism [30,53].Further, heavy inflammation was detected in WT mice lungs compared to Pafr-\/- [53]. Theresults highlight that PAFR influences disease severity and could support the idea thatmolecule antagonisms could intervene in microbial activity, but further research in humansubjects is warranted. This study\u2019s strengths include using resected human lung tissuesto show expression, providing new information on disease pathogenesis, and assistingwith future treatment or management strategies. This research has a few limitations,with the main challenge being the small number of IPF disease tissues available but theyare rare human IPF tissue. Future investigation should aim for large sample sizes forbetter distribution and correlation with measured parameters. Secondly, the age of thenormal control group is relatively younger than that of the IPF group due to the limitedaccessibility of obtaining the tissue. Further, comparing our data with previous researchwas challenging as very little human clinical work is done on these receptors in IPF, hencethis is a novel study in IPF. The future applications for this study include performing cellcultures to understand the cellular activity between IPF and NC. Finally, need to furtherinvestigate microbial adherence to the respiratory epithelium and inflammatory cells aswell as molecular analysis to study the role of genetics and proteins in relation to diseasepathogenesis and treatment.5. ConclusionsIn conclusion, this is the first study to show PAFR and ICAM\u20131 expression in smallairway epithelium, type 2 pneumocytes and alveolar macrophages in IPF patients comparedto normal controls. Following previous research in COPD and IPF, high expression of theseadhesion molecules could bridge the gap on inflammation and microbial activity in IPF.The clinical significance of these expression patterns suggests that microbes (bacteriaJ. Clin. Med. 2024, 13, 2126 12 of 14and viruses) use these molecules as a mode of \u2018anchor\u2019 to gain cellular entry duringinflammatory response, exacerbating disease pathogenesis. These findings can potentiallyhelp with future therapeutic development that can halt the disease progression, increasingthe survival rate and reducing the global burden.Author Contributions: Conceptualization, S.S.S.; Data curation, A.M.S.; Formal analysis, A.M.S.;Funding acquisition, S.S.S.; Investigation, W.L., S.D. and S.S.S.; Methodology, A.M.S., W.L., S.D., P.B.,A.V.G. and M.S.E.; Project administration, S.S.S.; Resources, J.J., G.W., D.S., G.K.S., T.-L.H. and S.S.S.;Supervision, S.S.S.; Validation, S.S.S.; Writing\u2014original draft, A.M.S.; Writing\u2014review & editing,W.L., P.B., A.V.G., J.J., G.W., D.S., G.K.S., T.-L.H., M.S.E. and S.S.S. All authors have read and agreedto the published version of the manuscript.Funding: This research was supported by grants from Clifford Craig Foundation Launceston Gen-eral Hospital.Institutional Review Board Statement: The tissue was provided with approvals from the EthicsCommittee of The Alfred Health Biobank in Melbourne (Alfred Health Biobank Melbourne, ethicsID:336-13) and The James Hogg Lung Registry (ethics ID: H00-50110) at the University of BritishColumbia.Informed Consent Statement: Informed consent was obtained from all subjects prior to collection ofthe tissue.Data Availability Statement: The data that support the findings of this study are available from thecorresponding author upon reasonable request.Conflicts of Interest: S. S. Sohal reports honorarium for lectures from Chiesi, travel support fromChiesi, 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 Australiafor which an honorarium has been received. All the other authors do not have any conflict of interestto declare.References1. Gaikwad, A.V.; Lu, W.; Dey, S.; Bhattarai, P.; Chia, C.; Larby, J.; Haug, G.; Myers, S.; Jaffar, J.; Westall, G.; et al. Vascularremodelling in idiopathic pulmonary fibrosis patients and its detrimental effect on lung physiology: Potential role of endothelial-to-mesenchymal transition. ERJ Open Res. 2022, 8, 00571\u20132021. [CrossRef] [PubMed]2. Suri, G.S.; Kaur, G.; Jha, C.K.; Tiwari, M. Understanding idiopathic pulmonary fibrosis\u2014Clinical features, molecular mechanismand therapies. Exp. Gerontol. 2021, 153, 111473. [CrossRef] [PubMed]3. 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MDPI and\/or the editor(s) disclaim responsibility for any injury topeople or property resulting from any ideas, methods, instructions or products referred to in the content.","@language":"en"}],"Genre":[{"@value":"Article","@language":"en"}],"IsShownAt":[{"@value":"10.14288\/1.0441964","@language":"en"}],"Language":[{"@value":"eng","@language":"en"}],"PeerReviewStatus":[{"@value":"Reviewed","@language":"en"}],"Provider":[{"@value":"Vancouver : University of British Columbia Library","@language":"en"}],"Publisher":[{"@value":"Multidisciplinary Digital Publishing Institute","@language":"en"}],"PublisherDOI":[{"@value":"10.3390\/jcm13072126","@language":"en"}],"Rights":[{"@value":"CC BY 4.0","@language":"en"}],"RightsURI":[{"@value":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/","@language":"en"}],"ScholarlyLevel":[{"@value":"Faculty","@language":"en"},{"@value":"Researcher","@language":"en"}],"Subject":[{"@value":"alveolar macrophages","@language":"en"},{"@value":"ICAM\u20131","@language":"en"},{"@value":"idiopathic pulmonary fibrosis","@language":"en"},{"@value":"infections","@language":"en"},{"@value":"PAFR","@language":"en"},{"@value":"type 2 pneumocytes","@language":"en"}],"Title":[{"@value":"Platelet Activating Factor Receptor and Intercellular Adhesion Molecule\u20131 Expression Increases in the Small Airway Epithelium and Parenchyma of Patients with Idiopathic Pulmonary Fibrosis : Implications for Microbial Pathogenesis","@language":"en"}],"Type":[{"@value":"Text","@language":"en"}],"URI":[{"@value":"http:\/\/hdl.handle.net\/2429\/88014","@language":"en"}],"SortDate":[{"@value":"2024-04-06 AD","@language":"en"}],"@id":"doi:10.14288\/1.0441964"}