Objectives: To differentiate invasive lepidic predominant adenocarcinoma (iLPA) from adenocarcinoma in situ (AIS)/minimally invasive adenocarcinoma (MIA) of lung utilizing visual semantic and computer-aided detection (CAD)-based texture features on subjects initially diagnosed as AIS or MIA with CT-guided biopsy. Materials and Methods: From 2011 to 2017, all patients with CT-guided biopsy results of AIS or MIA who subsequently underwent resection were identified. CT scan before the biopsy was used to assess visual semantic and CAD texture features, totaling 23 semantic and 95 CAD-based quantitative texture variables. The least absolute shrinkage and selection operator (LASSO) method or forward selection was used to select the most predictive feature and combination of semantic and texture features for detection of invasive lung adenocarcinoma. Results: Among the 33 core needle-biopsied patients with AIS/MIA pathology, 24 (72.7%) had invasive LPA and 9 (27.3%) had AIS/MIA on resection. On CT, visual semantic features included 21 (63.6%) part-solid, 5 (15.2%) pure ground glass, and 7 (21.2%) solid nodules. LASSO selected seven variables for the model, but all were not statistically significant. “Volume” was found to be statistically significant when assessing the correlation between independent variables using the backward selection technique. The LASSO selected “tumor_Perc95”, “nodule surround”, “small cyst-like spaces”, and “volume” when assessing the correlation between independent variables. Conclusions: Lung biopsy results showing noninvasive LPA underestimate invasiveness. Although statistically non-significant, some semantic features showed potential for predicting invasiveness, with septal stretching absent in all noninvasive cases, and solid consistency present in a significant portion of invasive cases.

: Lung cancer is the most common cause of cancer-related deaths worldwide. Early detection improves outcomes, however, existing sampling techniques are associated with suboptimal diagnostic yield and procedure-related complications. Autofluorescence-based fluorescence-lifetime imaging microscopy (FLIM), a technique which measures endogenous fluorophore decay rates, may aid identification of optimal biopsy sites in suspected lung cancer. Our fibre-based fluorescence-lifetime imaging system, utilising 488 nm excitation, which is deliverable via existing diagnostic platforms, enables real-time visualisation and lifetime analysis of distal alveolar lung structure. We evaluated the diagnostic accuracy of the fibre-based fluorescence-lifetime imaging system to detect changes in fluorescence lifetime in freshly resected ex vivo lung cancer and adjacent healthy tissue as a first step towards future translation. The study compares paired non-small cell lung cancer (NSCLC) and non-cancerous tissues with gold standard diagnostic pathology to assess the performance of the technique. Paired NSCLC and non-cancerous lung tissues were obtained from thoracic resection patients (N=21). A clinically compatible 488 nm fluorescence-lifetime endomicroscopy platform was used to acquire simultaneous fluorescence intensity and lifetime images. Fluorescence lifetimes were calculated using a computationally-lightweight, rapid lifetime determination method. Fluorescence lifetime was significantly reduced in ex vivo lung cancer, compared with non-cancerous lung tissue [mean ± standard deviation (SD), 1.79±0.40 vs. 2.15±0.26 ns, P<0.0001], and fluorescence intensity images demonstrated distortion of alveolar elastin autofluorescence structure. Fibre-based fluorescence-lifetime imaging demonstrated good performance characteristics for distinguishing lung cancer, from adjacent non-cancerous tissue, with 81.0% sensitivity and 71.4% specificity. Our novel fibre-based fluorescence-lifetime imaging system, which enables label-free imaging and quantitative lifetime analysis, discriminates ex vivo lung cancer from adjacent healthy tissue. This minimally invasive technique has potential to be translated as a real-time biopsy guidance tool, capable of optimising diagnostic accuracy in lung cancer.

Abstract Lung cancer is the leading cause of cancer-related death. The five year survival rate had remained stagnant for decades, but more effective screening protocols using low-dose computed tomographic screening for high-risk individuals, along with progress in treatment for advanced-stage lung cancer with targeted therapy and immunotherapy, have helped decrease lung cancer mortality. However, improved approaches to lung cancer prevention and early detection are still urgently needed. Adenocarcinoma (LUAD) is the most common form of lung cancer. Following surgical resection of pre-invasive adenocarcinoma in situ, the five-year survival rate approaches 100%. This emphasizes the need for improved understanding of characteristics of aggressive premalignant lesions that would benefit from early interventions. In contrast to the well-characterized histopathologic sequence of lung squamous cell carcinoma, atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS) are the only known precursors in the sequence of LUAD pathogenesis. The features of AAH and AIS that lead to invasive LUAD are poorly characterized. The relationship of AIS and AAH to the histologically diverse subtypes of LUAD, ranging from the typically slow growing lepidic to aggressive solid subtypes, are also unclear. We hypothesized that transcriptomic changes in subsets of premalignant lesions are linked to distinct genomic and clinicopathologic features of malignant disease. To investigate this hypothesis, we performed exome sequencing and bulk RNA sequencing of laser capture microdissected tissue from tumor margins that included premalignant lesions, invasive tumor, and adjacent normal tissues. With our analysis, we discovered de novo subtypes of LUAD premalignant lesions based on gene expression. One of these subtypes had gene expression alterations similar to aggressive invasive LUAD solid tumors. This molecular adenomatous premalignant lesion subtype was also associated with an increased accumulation of cancer driver mutations. This subtype was further characterized by altered expression of immune-related pathways. Molecular signatures measured in adenomatous PML may thus enhance our understanding of pathway dysregulation and mutational heterogeneity occurring during LUAD carcinogenesis, and implicate immunotherapeutic strategies to prevent their progression to cancer. Citation Format: Kelley Anderson, Linh Tran, Kostyantyn Krysan, William Wallace, Gregory Fishbein, Emily Green, Gang Liu, Hanqiao Liu, Erin Kane, Sarah Mazzilli, Steven Dubinett, Avrum Spira, Marc Lenburg, Jennifer Beane. Molecular subtyping of lung adenocarcinoma premalignant lesions identifies features associated with aggressive disease [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr PR007.

SESSION TITLE: Disorders of Pleura Case Report Posters 6 SESSION TYPE: Case Report Posters PRESENTED ON: 10/10/2023 09:40 am - 10:25 am INTRODUCTION: Among the occupational lung diseases, asbestos and silica are two of the most common inhalational culprits. However, unlike asbestosis where pleural disease is commonly described, pleural effusions are rarely found in silicosis, accounting for less than 11% of cases found on autopsy.1 Here, we present a unique case of a patient with long-standing silicosis who had an exudative pleural effusion that was highly concerning for malignancy and impeding his lung transplant workup. Due to repeated nondiagnostic thoracenteses, a medical thoracoscopy was performed which confirmed an inflammatory pleuritis due to silica implants in the parietal and visceral pleura. CASE PRESENTATION: A 52-year-old male with a history of end-stage silicosis diagnosed by EBUS and transbronchial biopsy in the past presented with gradual development of concurrent bilateral pleural effusions of unclear etiology. Multiple repeat thoracenteses revealed an exudative effusion notable for atypical plasma cells and an elevated adenosine deaminase (ADA). Microbiology was negative for organisms. Cytology, and flow cytometry revealed rare atypical cells, but was ultimately insufficient for diagnosis of a hematologic malignancy. Due to the development of pancytopenia, a bone marrow biopsy was also obtained which was negative for lymphoma. PET scan showed no FDG-avid sites to target for biopsy. Since the patient's lung transplant candidacy was in limbo, a medical thoracoscopy was pursued and demonstrated innumerable 5-10mm raised, round, gray, nodules diffusely spread out along both the parietal and visceral pleura. Under direct visualization, forceps biopsies were obtained and revealed pleural nodular silicosis with an exuberant, reactive lymphoplasmacytic infiltrate, with no evidence of malignancy or acid-fast organisms. Given these findings, the effusions were attributed to an extensive plasmacytic response to silica pearls studding the pleura. DISCUSSION: Given the rarity of pleural effusions associated with silicosis, there is limited data on what to expect on chemical analysis of the fluid. As in our patient, a few case reports have similarly demonstrated a lymphocytic predominant, exudative effusion, with an elevation in ADA.2-4 None of these publications have actually proven the link between the silica and the effusion with a tissue biopsy, however. Due to the patient's transplant candidacy, we ultimately pursued medical thoracoscopy to definitively diagnose the etiology of the effusion and rule out hematolymphoid malignancy. Not only did the tissue biopsy prove that the effusions were from a robust inflammatory response surrounding silica pearls, but this approach also allowed us to photograph what silica studding looks like in the pleural space, which is something that has not been described in the literature before. CONCLUSIONS: To our knowledge, this is the first case report describing the gross visual appearance of pleural silicosis from within the chest wall cavity. In addition to reconfirming the exudative, high ADA nature of the effusion, it also highlights the fact that significant plasmacytosis may be seen in a select population of patients with silica pleuritis. REFERENCE #1: Arakawa H, Honma K, Saito Y, et al. Pleural Disease in Silicosis: Pleural Thickening, Effusion, and Invagination. Radiology. 2005;236:685-693. doi:10.1148/radiol.2362041363 REFERENCE #2: Rashid A and Green F. Pleural pearls following silicosis: a histological and electron microscopic study. Histopathology. 1995;26(1):84-87. doi:10.1111/J.1365-2559.1995.TB00627.X REFERENCE #3: Salih M, Aljarod T, Ayan M, Jeffrey M, Shah BH. Pulmonary Silicosis Presents with Pleural Effusion. Case Rep Med. 2015;2015. doi:10.1155/2015/543070 DISCLOSURES: No relevant relationships by Ching-Fei Chang No relevant relationships by Rodrigo Garcia Tome No relevant relationships by Chongiin Kim No relevant relationships by Brett Lindgren No relevant relationships by Maria Vergara-Lluri No relevant relationships by William Wallace No disclosure on file for Cleandra Williams

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with limited treatment options. Interleukin-33 (IL-33) is proposed to play a role in the development of IPF however the exclusive use of prophylactic dosing regimens means that the therapeutic benefit of targeting this cytokine in IPF is unclear. IL-33 expression was assessed in ILD lung sections and human lung fibroblasts (HLFs) by immunohistochemistry and gene/protein expression and responses of HLFs to IL-33 stimulation measured by qPCR. In vivo, the fibrotic potential of IL-33:ST2 signalling was assessed using a murine model of bleomycin (BLM)-induced pulmonary fibrosis and therapeutic dosing with an ST2-Fc fusion protein. Lung and bronchoalveolar lavage fluid were collected for measurement of inflammatory and fibrotic endpoints. Human precision-cut lung slices (PCLS) were stimulated with transforming growth factor-β (TGFβ) or IL-33 and fibrotic readouts assessed. IL-33 was expressed by fibrotic fibroblasts in situ and was increased by TGFβ treatment in vitro. IL-33 treatment of HLFs did not induce IL6, CXCL8, ACTA2 and COL1A1 mRNA expression with these cells found to lack the IL-33 receptor ST2. Similarly, IL-33 stimulation had no effect on ACTA2, COL1A1, FN1 and fibronectin expression by PCLS. Despite having effects on inflammation suggestive of target engagement, therapeutic dosing with the ST2-Fc fusion protein failed to reduce BLM-induced fibrosis measured by hydroxyproline content or Ashcroft score. Together these findings suggest the IL-33:ST2 axis does not play a central fibrogenic role in the lungs with therapeutic blockade of this pathway unlikely to surpass the current standard of care for IPF.

Rationale: Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by limited treatment options and high mortality. Novel therapies and prognostic biomarkers are needed. Objective: To identify and validate molecular determinants of IPF survival. Methods: A staged genome-wide association study (GWAS) was performed using paired genomic and survival data. Stage I cases were drawn from centers across the US and Europe and stage II cases from Vanderbilt University. Cox proportional hazards regression was used to identify gene variants associated with differential transplant-free survival (TFS). Stage I variants with nominal significance (p<5x10-5) were advanced for stage II testing and meta-analyzed to identify those reaching genome-wide significance (p<5x10-8). Downstream analyses were performed for genes and proteins associated with variants reaching genome-wide significance. Main Results: After quality controls, 1481 stage I cases and 397 stage II cases were included in the analysis. After filtering, 9,075,629 variants were tested in stage I, with 158 meeting advancement criteria. Four variants associated with TFS with consistent effect direction were identified in stage II, including one in an intron of proprotein convertase subtilisin/kexin type 6 (PCSK6) reaching genome-wide significance (HR 4.11; 95%CI 2.54-6.67; p=9.45x10-9). PCSK6 protein was highly expressed in IPF lung parenchyma and negatively correlated with survival. Peripheral blood PCSK6 gene expression and plasma concentration were associated with reduced transplant-free survival. Conclusions: We identified four novel variants associated with IPF survival, including one in PCSK6 that reached genome-wide significance. Downstream analyses suggested that PCSK6 protein may serve as prognostic biomarker in IPF and potential therapeutic target.

INTRODUCTION: Despite the incidence of about 2/100.000 with decrease in recent decades, silicosis is still a major pneumoconiosis in the US.Majority of patients have simple chronic silicosis, some have complicated, progressive massive fibrosis (PMF) and only on a level of case reports and series, acute silicosis is described.Because of its rarity, radiological findings are not well described, and in-vivo histological diagnosis rarely done (1). CASE PRESENTATION:A 43-year-old man, with situs inversus, hearing loss and intellectual difficulties, presented to the pulmonary clinic following multiple hospitalizations for acute on chronic hypoxemic respiratory failure.His symptoms progressed over the last 10 months with a chronic dry cough and 40 lbs weight loss.He has worked as a marble cutter for the past 20 years, though reports consistent use of respiratory protective equipment.During his multiple hospitalizations, he tested positive for influenza B, SARS-CoV-2, and Bordetella pertussis.Chest computed tomography (CT) demonstrated predominantly upper lobes ground-glass opacities (GGO) and consolidations with traction and varicose bronchiectasis, as well as pleural sparing.Autoimmune serologies were negative.Laboratory studies demonstrated an elevated C-reactive protein, ESR, ACE level, calcium, as well as high immunoglobulins and multiple positive findings on skin allergy testing.He underwent four bronchoscopies with bronchoalveolar lavage (BAL), three separate forceps transbronchial biopsies (TBBx) and one bronchial brush, with findings showing signs of nonspecific fibrosis without evidence of granulomas or silicosis based on reports.BAL studies were monocytes predominant and one result showed 16% eosinophils.He was treated for the infections stated above, but continued to have unexplained progressive respiratory failure.On our evaluation, given the previous work-up and upper lobe predominant disease, differential included ciliary motility disorders, hypersensitivity pneumonitis, sarcoidosis, and pulmonary silicosis despite the previous negative evaluation.We performed bronchoscopy with BAL, linear endobronchial ultrasound (EBUS)-guided transbronchial lymph node aspiration (TBNA) using a 19-G needle and radial EBUS-guided right lower lobe transbronchial cryobiopsy using a 2.4 mm cryoprobe.BAL was monocyte predominant.The EBUS-TBNA from lymph node station 7 demonstrated fragments of fibrotic nodules with anthracosis and polarizable silica particles, consistent with silicotic nodules.Cryobiopsy showed alveolar lipoproteinosis and abundant polarizable silica particles consistent with acute silicoproteinosis.DISCUSSION: Chronic silica exposure leads to well described clinical and radiological entities, with progressive dyspnea and upper-lobe-predominant pulmonary nodules that get coalesced in complicated silicosis and can lead to fibrosis like in our patient.Acute silicoproteinosis, however, is a separate, rare, often undiagnosed entity occurring after a very high acute exposure to silica particles, often leading to rapidly progressive respiratory failure and death.It does not have well described radiological findings, mainly with GGO related to the alveolar filling with dust.(2) Histological diagnosis is rare and, unfortunately, often on autopsy (3).Prompt diagnosis and immediate removal from exposure is imperative and therapeutic options are scarce.CONCLUSIONS: This case demonstrates the importance and non-dismissable role of cryobiopsy in diagnosing the acute silicosis, and should be considered early on, to avoid delay in treatment of this deadly disease.

Background: Patients with thoracic aortopathy are at increased risk of catastrophic aortic dissection, carrying with it substantial mortality and morbidity. Although granular medial calcinosis (medial microcalcification) has been associated with thoracic aortopathy, its relationship to disease severity has yet to be established. Methods: One hundred one thoracic aortic specimens were collected from 57 patients with thoracic aortopathy and 18 control subjects. Standardized histopathologic scores, immunohistochemistry, and nanoindentation (tissue elastic modulus) were compared with the extent of microcalcification on von Kossa histology and 18F-sodium fluoride autoradiography. Results: Microcalcification content was higher in thoracic aortopathy samples with mild (n=28; 6.17 [2.71–10.39]; P ≤0.00010) or moderate histopathologic degeneration (n=30; 3.74 [0.87–11.80]; P <0.042) compared with control samples (n=18; 0.79 [0.36–1.90]). Alkaline phosphatase (n=26; P =0.0019) and OPN (osteopontin; n=26; P =0.0045) staining were increased in tissue with early aortopathy. Increasingly severe histopathologic degeneration was related to reduced microcalcification (n=82; Spearman ρ, −0.51; P <0.0001)—a process closely linked with elastin loss (n=82; Spearman ρ, −0.43; P <0.0001) and lower tissue elastic modulus (n=28; Spearman ρ, 0.43; P =0.026). 18 F-sodium fluoride autoradiography demonstrated good correlation with histologically quantified microcalcification (n=66; r=0.76; P <0.001) and identified areas of focal weakness in vivo. Conclusions: Medial microcalcification is a marker of aortopathy, although progression to severe aortopathy is associated with loss of both elastin fibers and microcalcification. 18 F-sodium fluoride positron emission tomography quantifies medial microcalcification and is a feasible noninvasive imaging modality for identifying aortic wall disruption with major translational promise.

Immunopathology occurs in the lung and spleen in fatal coronavirus disease (COVID-19), involving monocytes/macrophages and plasma cells. Antiinflammatory therapy reduces mortality, but additional therapeutic targets are required. We aimed to gain mechanistic insight into COVID-19 immunopathology by targeted proteomic analysis of pulmonary and splenic tissues. Lung parenchymal and splenic tissue was obtained from 13 postmortem examinations of patients with fatal COVID-19. Control tissue was obtained from cancer resection samples (lung) and deceased organ donors (spleen). Protein was extracted from tissue by phenol extraction. Olink multiplex immunoassay panels were used for protein detection and quantification. Proteins with increased abundance in the lung included MCP-3, antiviral TRIM21, and prothrombotic TYMP. OSM and EN-RAGE/S100A12 abundance was correlated and associated with inflammation severity. Unsupervised clustering identified “early viral” and “late inflammatory” clusters with distinct protein abundance profiles, and differences in illness duration before death and presence of viral RNA. In the spleen, lymphocyte chemotactic factors and CD8A were decreased in abundance, and proapoptotic factors were increased. B-cell receptor signaling pathway components and macrophage colony stimulating factor (CSF-1) were also increased. Additional evidence for a subset of host factors (including DDX58, OSM, TYMP, IL-18, MCP-3, and CSF-1) was provided by overlap between 1) differential abundance in spleen and lung tissue; 2) meta-analysis of existing datasets; and 3) plasma proteomic data. This proteomic analysis of lung parenchymal and splenic tissue from fatal COVID-19 provides mechanistic insight into tissue antiviral responses, inflammation and disease stages, macrophage involvement, pulmonary thrombosis, splenic B-cell activation, and lymphocyte depletion.

BACKGROUND:Acute aortic syndrome is associated with aortic medial degeneration. 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) detects microscopic tissue calcification as a marker of disease activity. OBJECTIVES:In a proof-of-concept study, this investigation aimed to establish whether 18F-NaF PET combined with computed tomography (CT) angiography could identify aortic medial disease activity in patients with acute aortic syndrome. METHODS:Patients with aortic dissection or intramural hematomas and control subjects underwent 18F-NaF PET/CT angiography of the aorta. Aortic 18F-NaF uptake was measured at the most diseased segment, and the maximum value was corrected for background blood pool activity (maximum tissue-to-background ratio [TBRmax]). Radiotracer uptake was compared with change in aortic size and major adverse aortic events (aortic rupture, aorta-related death, or aortic repair) over 45 ± 13 months. RESULTS:Aortic 18F-NaF uptake co-localized with histologically defined regions of microcalcification and elastin disruption. Compared with control subjects, patients with acute aortic syndrome had increased 18F-NaF uptake (TBRmax: 1.36 ± 0.39 [n = 20] vs 2.02 ± 0.42 [n = 47] respectively; P < 0.001) with enhanced uptake at the site of intimal disruption (+27.5%; P < 0.001). 18F-NaF uptake in the false lumen was associated with aortic growth (+7.1 mm/year; P = 0.011), and uptake in the outer aortic wall was associated with major adverse aortic events (HR: 8.5 [95% CI: 1.4-50.4]; P = 0.019). CONCLUSIONS:In patients with acute aortic syndrome, 18F-NaF uptake was enhanced at sites of disease activity and was associated with aortic growth and clinical events. 18F-NaF PET/CT holds promise as a noninvasive marker of disease severity and future risk in patients with acute aortic syndrome. (18F Sodium Fluoride PET/CT in Acute Aortic Syndrome [FAASt]; NCT03647566).

Background: Tissue inflammation in fatal COVID-19 is concentrated in the lung and spleen. Anti-inflammatory therapy reduces mortality but knowledge on the host response at the level of inflamed tissues is incomplete. Methods: We performed targeted proteomic analysis of pulmonary and splenic tissues from 13 fatal cases of COVID-19 that underwent rapid autopsy, and compared to control tissues from cancer resection (lung) and deceased organ donors (spleen). Viral RNA presence was determined by multiplex PCR, and protein was isolated from tissue by phenol extraction. Targeted multiplex immunoassay panels were used for protein detection and quantification. Findings: Pulmonary proteins with increased abundance in COVID-19 included the monocyte/macrophage chemoattractant MCP-3, antiviral TRIM21 and pro-thrombotic TYMP. The lung injury markers OSM and EN-RAGE/S100A12 were highly correlated and associated with tissue inflammation severity. Unsupervised clustering of lung proteomes clearly defined two COVID-19 clusters; these differed by viral presence, tissue inflammation severity and illness duration and were annotated 'early viral' and 'late inflammatory' groups. In the spleen, lymphocyte chemotactic factors and CD8A were decreased in COVID-19, with pro-apoptotic factors, B-cell signalling components and macrophage colony stimulating factor (CSF-1) all increased. To contextualise our findings, we cross-referenced an existing meta-analysis of host factors in COVID-19 (MAIC). Overlap with a substantial sub-set of factors (including DDX58, OSM, TYMP, IL-18, MCP-3 and CSF-1) was found, with numerous additional proteins also identified by our study. Interpretation: Tissue proteomes from fatal COVID-19 identify disease subsets and dissect host immunopathologic signatures. In doing so, this may afford unique opportunities for therapeutic intervention.Funding Information: This work was funded by UK Research and Innovation (UKRI) (Coronavirus Disease [COVID-19] Rapid Response Initiative; MR/V028790/1 to C.D.L., D.A.D., and J.A.H.), LifeArc (through the University of Edinburgh STOPCOVID funding award, to K.D, D.A.D, C.D.L), The Chief Scientist Office (RARC-19 Funding Call, 'Inflammation in Covid-19: Exploration of Critical Aspects of Pathogenesis; COV/EDI/20/10' to D.A.D, C.D.L, C.D.R, J.K.B and D.J.H), and Medical Research Scotland (CVG-1722-2020 to DAD, CDL, CDR, JKB, and DJH). C.D.L is funded by a Wellcome Trust Clinical Career Development Fellowship (206566/Z/17/Z). J.K.B. and C.D.R. are supported by the Medical Research Council (grant MC_PC_19059) as part of the ISARIC Coronavirus Clinical Characterisation Consortium (ISARIC-4C). C.D.R. is supported by an Edinburgh Clinical Academic Track (ECAT)/Wellcome Trust PhD Training Fellowship for Clinicians award (214178/Z/18/Z). J.A.H. is supported by the U.S. Food and Drug Administration (contract 75F40120C00085, Characterization of severe coronavirus infection in humans and model systems for medical countermeasure development and evaluation'). G.C.O is funded by an NRS Clinician award. N.N.G. is funded by a Pathological Society Award. A.R.A. is supported by a Cancer Research UK Clinician Scientist Fellowship award (A24867).Declaration of Interests: All authors have declared that no competing interests exist.Ethics Approval Statement: Written informed consent to undertake postmortem examinations was obtained from next-of-kin. Ethical approval was granted by the East of Scotland Research Ethics Service (16/ES/0084).

Background Acute aortic syndrome is a catastrophic condition characterised by medial degeneration and cellular destruction within the aortic wall. 18F-Sodium fluoride (18F-NaF) positron emission tomography (PET) detects microscopic calcification as a marker of disease activity. This proof-of-concept study aims characterise 18F-NaF PET in patients with acute aortic syndrome. Methods Aortic tissue obtained from patients with acute aortic syndrome was stained using von Kossa’s stain for calcium-phosphate complexes and then exposed to 18F-sodium fluoride to confirm radiotracer binding to microcalcification. Next, patients with aortic dissection or intramural haematomas and healthy controls underwent 18F-NaF PET/CT and CT angiography of the aorta. A threshold of 12 weeks since diagnosis was used to classify patients to ‘recent’ or ‘prior’ acute aortic syndrome groups. Peak aortic 18F-NaF uptake was corrected for background blood pool activity to obtain a most-diseased segment tissue-to-background ratio (MDS TBRmax). Radiotracer binding was compared with aortic size in a linear regression model and major adverse aortic events (aortic rupture, aorta-related death or aortic repair) in a proportional hazards Cox survival analysis. Results Aortic 18F-NaF uptake co-localized with histologically defined regions of microcalcification (n=15). Patients with acute aortic syndrome had increased 18F-NaF binding compared to healthy controls (TBRmax 2.02±0.42 (n=47) vs 1.36±0.39 (n=20) respectively, p<0.001). Peak radiotracer uptake occurred at the site of intimal disruption (+27.5% compared to the proximal aorta, p<0.001). 18F-NaF binding to the false lumen was associated with aortic growth (+7.1 mm/yr, p=0.011) and uptake in the outer aortic wall was associated with major adverse aortic events (hazard ratio 8.6 [95% CI, 1.1-68.1], p=0.041) in patients with recent acute aortic syndrome. Conclusion 18F-NaF PET/CT uptake was increased in patients with acute aortic syndrome at sites of disease activity. Radiotracer binding was associated with aortic growth and clinical events. 18F-NaF PET-CT holds promise as a non-invasive marker of disease severity and future risk in patients with acute aortic syndrome. Conflict of Interest None

The success of immune checkpoint therapy shows tumor-reactive T cells can eliminate cancer cells but are restrained by immunosuppression within the tumor micro-environment (TME). Cancer associated fibroblasts (CAFs) are the dominant stromal cell in the TME and co-localize with T cells in non-small cell lung cancer. We demonstrate the bidirectional nature of CAF/T cell interactions; T cells promote expression of co-inhibitory ligands, MHC molecules and CD73 on CAFs, increasing their production of IL-6 and eliciting production of IL-27. In turn CAFs upregulate co-inhibitory receptors on T cells including the ectonucleotidase CD39 promoting development of an exhausted but highly cytotoxic phenotype. Our results highlight the bidirectional interaction between T cells and CAFs in promoting components of the immunosuppressive CD39, CD73 adenosine pathway and demonstrate IL-27 production can be induced in CAF by activated T cells.

Background. The aim of the study was to derive and compare metabolic parameters relating to benign and malignant pulmonary nodules using dynamic 2-deoxy-2-[fluorine-18]fluoro-D-glucose ( 18 F-FDG) PET/CT, and nodule perfusion parameters derived through perfusion computed tomography (CT). Patients and methods. Twenty patients with 21 pulmonary nodules incidentally detected on CT underwent a dynamic 18 F-FDG PET/CT and a perfusion CT. The maximum standardized uptake value (SUV max ) was measured on conventional 18 F-FDG PET/CT images. The influx constant ( K i ) was calculated from the dynamic 18 F-FDG PET/CT data using Patlak model. Arterial flow (AF) using the maximum slope model and blood volume (BV) using the Patlak plot method for each nodule were calculated from the perfusion CT data. All nodules were characterized as malignant or benign based on histopathology or 2 year follow up CT. All parameters were statistically compared between the two groups using the nonparametric Mann-Whitney test. Results. Twelve malignant and 9 benign lung nodules were analysed (median size 20.1 mm, 9–29 mm) in 21 patients (male/female = 11/9; mean age ± SD: 65.3 ± 7.4; age range: 50–76 years). The average SUV max values ± SD of the benign and malignant nodules were 2.2 ± 1.7 vs . 7.0 ± 4.5, respectively (p = 0.0148). Average K i values in benign and malignant nodules were 0.0057 ± 0.0071 and 0.0230 ± 0.0155 min -1 , respectively (p = 0.0311). Average BV for the benign and malignant nodules were 11.6857 ± 6.7347 and 28.3400 ± 15.9672 ml/100 ml, respectively (p = 0.0250). Average AF for the benign and malignant nodules were 74.4571 ± 89.0321 and 89.200 ± 49.8883 ml/100g/min, respectively (p = 0.1613). Conclusions. Dynamic 18 F-FDG PET/CT and perfusion CT derived blood volume had similar capability to differentiate benign from malignant lung nodules.

Patients with chronic lung disease (CLD) have an increased risk for severe coronavirus disease-19 (COVID-19) and poor outcomes. Here, we analyze the transcriptomes of 611,398 single cells isolated from healthy and CLD lungs to identify molecular characteristics of lung cells that may account for worse COVID-19 outcomes in patients with chronic lung diseases. We observe a similar cellular distribution and relative expression of SARS-CoV-2 entry factors in control and CLD lungs. CLD AT2 cells express higher levels of genes linked directly to the efficiency of viral replication and the innate immune response. Additionally, we identify basal differences in inflammatory gene expression programs that highlight how CLD alters the inflammatory microenvironment encountered upon viral exposure to the peripheral lung. Our study indicates that CLD is accompanied by changes in cell-type-specific gene expression programs that prime the lung epithelium for and influence the innate and adaptive immune responses to SARS-CoV-2 infection.

Abstract Background The aim of the study was to derive and compare metabolic parameters relating to benign and malignant pulmonary nodules using dynamic 2-deoxy-2-[fluorine-18]fluoro-D-glucose (18F-FDG) PET/CT, and nodule perfusion parameters derived through perfusion computed tomography (CT). Patients and methods Twenty patients with 21 pulmonary nodules incidentally detected on CT underwent a dynamic 18F-FDG PET/CT and a perfusion CT. The maximum standardized uptake value (SUVmax) was measured on conventional 18F-FDG PET/CT images. The influx constant (Ki ) was calculated from the dynamic 18F-FDG PET/CT data using Patlak model. Arterial flow (AF) using the maximum slope model and blood volume (BV) using the Patlak plot method for each nodule were calculated from the perfusion CT data. All nodules were characterized as malignant or benign based on histopathology or 2 year follow up CT. All parameters were statistically compared between the two groups using the nonparametric Mann-Whitney test. Results Twelve malignant and 9 benign lung nodules were analysed (median size 20.1 mm, 9–29 mm) in 21 patients (male/female = 11/9; mean age ± SD: 65.3 ± 7.4; age range: 50–76 years). The average SUVmax values ± SD of the benign and malignant nodules were 2.2 ± 1.7 vs. 7.0 ± 4.5, respectively (p = 0.0148). Average Ki values in benign and malignant nodules were 0.0057 ± 0.0071 and 0.0230 ± 0.0155 min-1, respectively (p = 0.0311). Average BV for the benign and malignant nodules were 11.6857 ± 6.7347 and 28.3400 ± 15.9672 ml/100 ml, respectively (p = 0.0250). Average AF for the benign and malignant nodules were 74.4571 ± 89.0321 and 89.200 ± 49.8883 ml/100g/min, respectively (p = 0.1613). Conclusions Dynamic 18F-FDG PET/CT and perfusion CT derived blood volume had similar capability to differentiate benign from malignant lung nodules.