Citations

Abstract Background We recently reported a strong association between CT markers of pulmonary artery (PA) dilation and mean PA pressure (mPAP) in subjects with World Symposium on Pulmonary Hypertension (WSPH) group 1 and 2 pulmonary hypertension (PH). The relationship between PA size and mPAP in subjects with WSPH group 3 PH, in which parenchymal changes may influence PA dilation, remains uncertain. We sought to investigate this relationship in subjects with and without PH who have significant parenchymal pulmonary disease or hypoxia. Methods We measured PA diameter and PA:aorta (PA:A) ratio on CT for all subjects with WSPH group 3 PH, matched disease comparators, and healthy controls in the Pulmonary Vascular Disease Phenomics (PVDOMICS) cohort. PH and comparator subjects were categorized by group 3 etiology into obstructive (including chronic obstructive pulmonary disease [COPD] and cystic fibrosis), interstitial (including idiopathic pulmonary fibrosis, unspecified interstitial lung disease, combined pulmonary fibrosis and emphysema, and chronic hypersensitivity pneumonitis), and non-parenchymal (including obesity hypoventilation syndrome, obstructive sleep apnea, and extrinsic restrictive disease) subgroups. Primary outcome was mPAP on right heart catheterization (RHC). Association with mPAP was evaluated using multivariable linear regression adjusted for age, sex, and BMI. Results 339 subjects met inclusion criteria (101 WSPH group 3 PH, 153 disease comparators, 85 healthy controls). 83 subjects had obstructive disease, 125 had interstitial disease, and 46 had non-parenchymal disease. PA diameter and PA:A were associated with mPAP in all subjects and in each subgroup (p < 0.001; see figure 1). The association was notably stronger in the non-parenchymal group (ρ = 0.707 for diameter, 0.750 for PA:A) compared to obstructive (ρ = 0.566 for diameter, 0.529 for PA:A) and interstitial (ρ = 0.432 for diameter, 0.373 for PA:A) groups. Change in PA size between 25th and 75th percentile mPAP was lower in the interstitial group (3.88 mm, ratio 0.12) than in the obstructive (4.88 mm, ratio 0.17) and non-parenchymal (4.80 mm, ratio 0.19) groups (see figure 1). Conclusions PA size on CT is associated with mPAP in subjects with chronic lung disease with and without PH. This association is strongest in subjects without parenchymal lung disease but with features of hypercarbia or hypoxia alone. These data suggest that features of parenchymal lung disease in certain patients may limit expected PA dilation in response to elevated PA pressures. Further study is needed regarding the implications of these findings for early identification of PH in patients with chronic lung disease. This abstract is funded by: The NHLBI and Pulmonary Hypertension Association

Abstract Background Single breath diffusing capacity of the lung for carbon monoxide (DLCO) remains the most widely used test to assess pulmonary gas exchange. GLI DLCO reference equations are based on a larger, more diverse dataset and offer age-specific and internally consistent reference values. However, their impact on interpretation in a real-world population remains uncertain. Research Question Describe the direction and magnitude of DLCO interpretation changes resulting from our multicenter PFT laboratory transition from Miller to GLI reference equations. Study Design and Methods In this multicenter cross-sectional study, we reanalyzed 88,060 DLCO measurements in a large pulmonary function laboratory database performed between 2016 and 2022 using GLI and Miller reference equations, stratified by self-reported race and ethnicity. Baseline patient characteristics and lung function measurements were summarized with continuous characteristics as median (IQR) and categorical variables as n (%). Kruskal-Wallis test was used to evaluate the difference between GLI and Miller DLCO % predicted difference between races, and two-by-two and four-by-four tables were generated to summarize the proportion of concordance and discordance of GLI to Miller severity levels. A repeated measures multivariable logistic regression was used to evaluate discordance between GLI and Miller severity and patient characteristics (age, sex, race, and BMI). Results We included 63,357 individuals with 88,060 PFT visits; 91.6% (58,076) identified as Caucasian, 5.2% (3,262) as Black, 1.4 % (895) as Asian, and 1.8% (1,113) as mixed/other race. Fifty-one percent were female with an median age of 64 years (range: 5- 85). 7.4% (6509) of DLCO results were discordant, with 0.5% (n = 439) abnormal by GLI only, and 6.9% (n = 6070) abnormal by Miller only. Compared to the Miller, GLI interpretations were associated with a greater shift toward normal interpretations. Younger age, lower BMI, female sex, and being of NE Asian, SE Asian, or Other/mixed race compared to Caucasian were associated with higher odds of discordance in DLCO severity/normal classification. Interpretation The use of GLI reference equations substantially alters the interpretation of DLCO results, shifting a meaningful subset of patients from abnormal to normal classification. While GLI reference equations offer more comprehensive, population-based approach, it is crucial to place these interpretations within the context of the patient presentation until further investigations more clearly define the clinical implications of these transitions. This abstract is funded by: none

Abstract Rationale The governing mechanisms of lung regeneration are still poorly understood. Studies have observed the lung’s regenerative capacity using the pneumonectomy (PNX) model, where removal of the left lung stimulates compensatory growth and neoalveolarization. However, this process is inhibited if a physical object is used to replace the extracted tissue, demonstrating that the lung can sense the available space and regenerate in response. The mechanism of this mechanosensing is unknown. As outermost tissue layer of the lung, the pulmonary mesothelium is well situated to sense the surrounding environment. We and others have hypothesized that the mesothelium can become activated in cases of injury or regeneration, but this has not been fully explored. Understanding the mechanisms controlling neoalveolarizaiton may be key to unlocking the lung’s natural regenerative capacity in humans. Methods & Results In this study, we examined the location and fate of the mesothelium during regeneration using fluorescent lineage tracing and the PNX model. Specifically, we used the mesothelial-specific Wt1CreERT2 crossed with a lox-stop-lox-RFP reporter (Wt1(CreERT2/+);LSL-RFP(+/-)). Following PNX, we collected the lineage-labeled cells along with the CD326+ and CD326-/CD45-/CD31- populations and performed scRNA-sequencing. As quantified by flow-cytometry, the number of RFP+ cells increased following PNX, indicating proliferation of the mesothelium. Clustering analysis elucidated the emergence of 3 activated clusters of mesothelium following PNX, representing 12.9% of the RFP+ population in Sham and 66% in PNX. These activated cells exhibited decreased expression of mesothelial hallmarks and increased expression of extracellular matrix and epithelial-to-mesenchymal transition genes. Using immunofluorescence and confocal microscopy, we observed lineage-labeled mesothelium deep within the parenchyma after PNX. We observed none or singular invaded mesothelium in no-procedure control animals and only minimal occurrence in animals exposed to Sham surgery. Compared to Sham controls, PNX post-surgical (D)ay 3, D7, and D14 had 8.5, 32.7, and 9.2-fold more cells, respectively, in the parenchyma. Moreover, in aged (18 month) mice, where regeneration is known to be significantly reduced, we likewise observed minimal mesothelial invasion following PNX. These cells were often found near or directly wrapping around progenitors of the alveolar epithelium, AT2 cells, whose proliferation is essential to neoalveolarization. Using time-lapse microscopy of precision cut lung slices, we observed the invading mesothelial cells to be highly dynamic, sending out multiple transient protrusions and interacting with neighboring cells. Conclusion Together these data support strong and potentially functional interactions between activated and invading mesothelial cells and lung regeneration following PNX. This abstract is funded by: NIH

Abstract Rationale Respiratory disease is a major cause of mortality in Down syndrome (DS; trisomy 21, T21). DS is considered a progeroid syndrome, with elevated cellular senescence (SEN) and oxidative stress. Because SEN shapes organogenesis, its dysregulation may impair lung morphogenesis. We previously found SEN/SASP (senescence-associated secretory phenotype) abnormalities in prenatal human T21 lungs. Here, we test whether these alterations persist and change after birth. Methods We analyzed human lung single-nuclear RNA (snRNA-seq) datasets (prenatal and postnatal) to quantify epithelial and mesenchymal SEN/SASP signatures. Sex- and age-matched T21 and non-T21 prenatal and postnatal lungs were studied; fibroblasts were isolated as prenatal human lung fibroblasts (HFLF) and postnatal human lung fibroblasts (HLF). SEN/SASP were measured by RT-qPCR and immunofluorescence (IF) in tissue and HFLF/HLF. HFLF/HLF were assayed for SA-β-gal, oxidative stress (CellROX/MitoSOX), and Ca²+ dynamics (Fura-2 AM). 48h treatments with tunicamycin (1µM, SEN inducer), 4-phenylbutyrate (4-PBA, 2 mM, ER Stress inhibitor), or pyrroloquinoline quinone (PQQ, 20 μM, antioxidant) were performed on T21 and non-T21 HFLF/HLF. Conditioned media (CM) were collected after 48h from untreated cultures and then applied to cells of the opposite genotype for 24, 48, and 72h. Results Overall SEN profile was similar in epithelium and mesenchyme across ages, but pathway signatures differed. Epithelium shows an inflammatory SASP, while mesenchyme shows a less-inflammatory, remodeling/growth-factor SASP. These lineage patterns were more evident postnatally. Whole-tissue IF showed increased γ-H2AX and p21 in T21 vs non-T21 both prenatally and postnatally (p < 0.05). At baseline, T21 HFLF/HLF had higher CDKN1A, CDKN2A, TP53, CDKN2B, and SERPINE1 (p < 0.05; n = 5-6), with increased γ-H2AX/p21 IF (p < 0.01; n = 6), SA-β-gal (p < 0.05; n = 5-6), and ER/mitochondrial stress (p < 0.05; n = 5-6). Fura-2 AM showed greater Ca²+ release in T21 HFLF/HLF at baseline and after acetylcholine (10 μM, p < 0.01; n = 5). Mitochondrial-morphology genes (FIS1, DNM1L, MFN1) were elevated in T21 HFLF/HLF (p < 0.05; n = 6). In T21 HFLF, 4-PBA and PQQ each reduced SA-β-gal (p < 0.01; n = 6). In postnatal HLF, PQQ had the stronger effect (p < 0.05; n = 5). T21 CM induced progressively greater SEN/SASP over 24/48/72h in non-T21 cells (p < 0.05; n = 5-6), while non-T21 CM partially rescued T21-HLF phenotypes at 24h only (p < 0.05; n = 5-6). Conclusion These data indicate that lung senescence in T21 initiates in utero and intensifies after birth and reflects lineage-specific pathways. ER-stress-related mechanisms are more prominent prenatally, while mitochondrial/redox mechanisms are predominant postnatally. This evidence suggests age and lineage-dependent drivers of senescence that may help explain DS lung disease and highlight potential new mechanistic targets. This abstract is funded by: NIH/NHLBI

Abstract Respiratory viral infections such as influenza and SARS-CoV-2 can lead to the development of chronic lung disease and impaired pulmonary function long after the recovery from acute illness. However, the mechanisms underlying these post-acute sequelae remain poorly understood. Using human lung samples from patients with post-acute sequelae of COVID-19 with pulmonary fibrosis (PASC-PF) and an aged mouse model of chronic lung disease following acute viral infection, we found that CD4+ T cells were enriched near the dysplastic Krt8Hi epithelial regions of the lung. Similarly, in aged mice, CD4+ T cells localized to Krt8Hi areas, and their spatial distribution correlated positively with the extent of epithelial dysplasia. Further analysis of bronchoalveolar lavage (BAL) fluid from COVID-19 convalescent individuals revealed a distinct population of FoxP3−PD-1HiCD4+ T cells highly expressing ICOS, CD69, and CD103 - markers characteristic of both T follicular helper (TFH) and tissue-resident memory (TRM) cells, which we have defined as tissue-resident helper (TRH) cells previously. Notably, the frequency of these TRH-like cells correlated positively with the extent of reticulate or consolidated regions on chest CT scans, indicative of lung fibrosis. Furthermore, the frequency of these cells was negatively associated with lung functional parameters including forced vital capacity (FVC). These findings suggest that PD-1HiCD4+ TRH-like cells expand in PASC and may contribute to chronic lung sequelae. Given that Bcl6 is required for TRH differentiation, we employed an aged, CD4-specific, inducible Bcl6-deficient (Bcl6iΔCD4) mouse model to evaluate the functional contribution of these cells to post viral lung fibrosis. Bcl6 deficiency led to a marked reduction in total and antigen-specific PD-1HiCD4+ TRH cells, as confirmed by flow cytometry and immunofluorescence. Strikingly, Bcl6 iΔCD4 mice displayed significantly decreased inflammatory and fibrotic lesions in the lung compared to wild-type controls. Moreover, Bcl6 iΔCD4 mice exhibited enhanced lung regeneration, evidenced by increased AT1 and AT2 epithelial cells and improved pulmonary function. Together, these findings identify Bcl6-dependent CD4+ TRH responses as key drivers of post-viral chronic lung sequelae. This study reveals a novel immunopathogenic mechanism linking persistent tissue helper memory T-cell responses to impaired lung repair and fibrosis, providing new insight into the development of post-viral lung disease and potential therapeutic targets for conditions such as respiratory long COVID. This abstract is funded by: American Lung Association, NIH

Abstract Rationale Rural populations in the US experience a higher lung cancer burden compared to urban residents, potentially due to differences in risk factors and access to preventative care and early detection. We sought to characterize tobacco use, smoking cessation, and lung cancer screening patterns by rurality to identify modifiable gaps in the lung cancer care continuum. Methods We analyzed data from current and former smoking adults in the Southern Community Cohort Study, a large prospective cohort recruited from community health centers across 12 southeastern states. Participants aged 65-80 years with at least 9 months of Medicare Part A/B and less than 3 months of Part C coverage between 2014 and 2020 were included. Data were linked with the National Death Index and Medicare claims for outcome ascertainment. Rurality was defined using Rural-Urban Commuting Area (RUCA) codes. We compared demographic characteristics, smoking patterns, use of smoking cessation interventions, and receipt of low-dose computed tomography (LDCT) screening between rural and urban participants over time. Results Among 10,114 adults included (56% urban; 46% rural), 54% were female, 55% identified as Black/African American, about a third reported less than a high school education, and 45% lived in areas in the highest quartile of deprivation. Urban residents were of similar age (66 vs 67 years), and more likely to currently smoke (42% vs 35%), but had fewer baseline smoking pack-years (27 vs 30 pack-years) than rural residents. Approximately 2% died of lung cancer during follow-up. Using the USPSTF 2013 lung cancer screening criteria, 27% of urban and 26% of rural residents were eligible. This increased unevenly to 38% urban and 35% rural under the USPSTF 2021 criteria. LDCT uptake was low, increasing from 0% in 2014 to 6% in 2020 among screening-eligible participants. Use of cessation interventions was similarly low. Among current smoking participants, 7% received smoking cessation counseling, and 3% had a varenicline prescription. These patterns remained relatively stable over time, with no significant rural-urban differences in LDCT and cessation intervention use. Conclusion Despite modest differences in smoking prevalence and screening eligibility, we found comparable lung cancer mortality and similarly low utilization of LDCT and cessation interventions among rural and urban residents. Our findings suggest that, among people in lower socioeconomic groups, shared socioeconomic constraints may extend beyond the rural-urban divide. Further research is needed to understand how social determinants of health may be addressed to improve lung cancer outcomes across the screening continuum. This abstract is funded by: NIH

Abstract Introduction Minimally invasive surgical techniques including Robotic-Assisted thoracoscopic surgery (RATS) have advanced the treatment of lung cancer and enhanced patient outcomes from early recovery to improved quality of life. The “July effect” hypothesizes that morbidity and mortality outcomes worsen during the beginning of academic year when new residents and fellows begin training. We investigated the impact of the same on outcomes of RATS among lung cancer patients. Methods Using the National Inpatient Sample (2016-2019), we identified adults(ages≥18 years) with lung cancer who underwent RATS(lobectomy/sublobar resection) at urban teaching centers(UTC). Patients were stratified by surgical timing: July-September versus other months. Multivariable logistic regression compared perioperative outcomes between groups, adjusting for confounders. Results We analyzed 25,480 RATS procedures, with 25.59% performed during July-September. Baseline characteristics were comparable between groups regarding sex, race (White, Hispanic), insurance type, comorbidity burden, and age; however, fewer Black patients underwent surgery during July-September (Table 1a). Multivariable logistic regression revealed no significant differences in perioperative outcomes between the July-September and other months of the year. Evaluated outcomes included thoracic complications like pneumonia (aOR 0.89, 95% CI 0.62-1.28, p = 0.526), pneumothorax (aOR 1.07, 95% CI 0.85-1.34, p = 0.583), air leak (aOR 0.98, 95% CI 0.79- 1.22, p = 0.873), respiratory failure (aOR 0.9, 95% CI 0.50-1.63, p = 0.729) , atelectasis (aOR 1.12, 95% CI 0.88-1.42, p = 0.372), thromboembolic events like pulmonary embolism (aOR 0.63, 95% CI 0.13-2.97, p = 0.557), deep venous thrombosis (aOR 1.01, 95% CI 0.65-1.57, p = 0.952), bleeding complications like transfusion (aOR 0.95, 95% CI 0.55-1.64, p = 0.866), hemothorax/hemoperitoneum/hematoma (aOR 0.58, 95% CI 0.22-1.52, p = 0.264), renal complications (aOR 1.00, 95% CI 0.32-3.17, p = 0.994), conversion to open surgery (aOR 0.53, 95% CI 0.11-2.47, p = 0.417), extended length of stay (>7 days) (aOR 0.96, 95% CI 0.78-1.17, p = 0.667), and in-hospital mortality (aOR 0.57, 95% CI 0.21-1.50, p = 0.250)(Table 1b). Conclusions Our study suggested no “July effect” in the perioperative outcomes of RATS. This demonstrates the robust hospital support systems ensuring the safe transition of resident classes without affecting the patient care negatively. This abstract is funded by: None

Abstract Rationale American Indians and Alaska Native (AI/AN) people have the highest prevalence of tobacco use of any US racial or ethnic minoritized group, though this varies regionally. Smoking, and smoking-related cancers including lung cancer are more common in AI/AN people than non-Hispanic whites in the Pacific Northwest. Lung cancer screening (LCS) is effective but broadly under-utilized in AI/AN eligible adults. This study’s objective was to evaluate a AI/AN community co-designed patient navigation intervention to bridge community healthcare settings to a LDCT-capable LCS program. Methods We conducted a single-arm pilot study of the patient navigation intervention, grounded in community-based participatory research principles. The intervention was formalized in a living handbook, co-created with input from patients and providers at an AI/AN Urban Indian Organization and primary care clinic, Seattle Indian Health Board. Two community health workers served as navigators to deliver culturally sensitive support, link to shared decision-making with a nurse practitioner at the academic LCS program, coordinate transportation, interface with insurance and provide other barrier-directed activities. Patients eligible for LCS (n = 44) were recruited from the AI/AN clinic setting through on-site outreach. Enrolled participants completed pre-navigation surveys which assessed baseline knowledge, attitudes, experiences and barriers. Those who engaged with the central program completed an additional post-navigation survey (n = 15). Electronic health records were reviewed for all navigation and LCS-related data. Results Between July 2023 - November 2024, 44 participants were enrolled in the study. The median age of the participants was 65 (IQR 58-70), 66% reported current smoking, and 76% reported an annual household income <$30,000. All participants reported at least one barrier that delayed care in the past 12 months. On review, two participants were up-to-date on LCS prior to enrollment. Within 6 months, 13 participants completed a shared decision-making appointment and 11 went forward with LDCT. On post-intervention surveys, barriers most commonly addressed were: scheduling (100%), transportation (80%), explaining LCS (80%) and cost/insurance (73%). Participants reported high acceptability, measured by Acceptability of Intervention Measure (AIM median 5.0, IQR 5-5) and patient satisfaction measured by Patient Navigation Satisfaction Measured-Instrument (PNS-I median 45, IQR 42-45). Conclusion A culturally tailored patient navigation program for LCS was feasible and highly acceptable among urban AI/AN adults. Navigation addressed multiple barriers and successfully connected some patient participants from a community clinic to tertiary screening centers for shared decision-making and/or screening. These findings support the effectiveness of academic-community partnered navigation to increase LCS uptake in AI/AN clinic settings. This abstract is funded by: ATS/ALA/Chest Foundation: Respiratory Health Equity Research Award (Triplette)

Abstract Background Despite the reported benefits, lung cancer screening (LCS) uptake remains alarmingly low in comparison to other cancer screening programs. Objective To develop and evaluate an automated, electronic health record (EHR)-embedded LCS outreach program designed to increase screening uptake while minimizing workload for referring providers and schedulers. Methods We developed an automated outreach and referral program at two Mayo Clinic campuses (Rochester [RST] and northwest Wisconsin [NWW]) coupled with a streamlined virtual care delivery process. Eligible patients were identified based on the information in the EHR regarding US Preventive Services Task Force guidelines for screening and were contacted through either a patient portal message, letter, or both. Outreach included LCS educational materials and self-scheduling instructions for a telephone or video shared decision-making (SDM) visit. During the visit, a licensed care team member discussed the risks and benefits of a low dose computed tomography (LDCT) scan with patients who could choose to enroll in the Lung Cancer Screening Program or decline. Results During the study period, 8,845 eligible patients (RST: 2201, NWW: 6644) were contacted using automated portal messages, letters, or both. Among the RST cohort, 2,156 portal messages and 1,060 letters were distributed in comparison to 7,642 portal messages, 6,441 letters, and 618 text messages in the NWWI cohort. The study showed increase in shared decision-making visits completion and screenings for eligible patients across both groups. Portal engagement was higher among the RST group 75.4% than 55.8% in the NWWI group, as was digital brochure access (14.1% vs 6.5%). Scheduling for share-decision-making visits was noted to be higher among the RST group (22% vs 13.6%), though visit completion rates were similar across sites (12.6 vs 13.6%). A lower opt-out rate was noted among the RST group (12.6% vs. 14.3%). Collectively, both campuses demonstrated meaningful patient engagement. Conclusion The automated outreach program effectively increased lung cancer screening engagement and uptake for eligible patients without adding significant administrative burden on primary care providers and clinical staff. Observed differences in engagement between sites, as well as relatively low completion rates highlight the need for further investigation into contextual and operational factors influencing program performance. This abstract is funded by: none

Abstract Introduction The diagnosis of fungal lung infections remains challenging as standard tests, such as bronchoalveolar lavage (BAL) antigen testing, often yield variable or inconclusive results. These limitations can delay appropriate therapy and may require additional tissue sampling for definitive diagnosis. Robotic-assisted bronchoscopy (RAB) biopsy has been primarily used as a minimally invasive technique for assessing suspicious peripheral pulmonary lesions (PPL). This case series highlights the diagnostic utility of RAB for identifying fungal infections within PPL when conventional BAL antigen analysis is non-diagnostic. Case Description Four patients with suspected infectious or malignant PPL underwent RAB-guided biopsy for diagnostic clarification, all yielding histopathologic confirmation of fungal disease. The first, a 73-year-old bilateral lung-transplant recipient with hemoptysis, had a negative BAL Aspergillus antigen despite RAB biopsy confirming Aspergillus infection. Similarly, a second 73-year-old man with chronic obstructive pulmonary disease (COPD) and esophageal adenocarcinoma had a negative BAL antigen, while RAB biopsy of bilateral cavitary lesions confirmed Aspergillus. Additionally, a 39-year-old woman with a nodule being evaluated for malignancy, had negative BAL Histoplasma antigen and PCR, whereas RAB biopsy confirmed Histoplasma capsulatum. In contrast, a 56-year-old woman with a right-lower-lobe nodule had a positive BAL Aspergillus antigen that aligned with the histopathologic biopsy findings. Discussion BAL-based antigen testing demonstrates variable diagnostic accuracy in fungal lung disease. Reported sensitivities for Aspergillus detection are typically high in meta-analysis, approximately 80%-90%, but clinical performance in the immunocompromised or high-risk patients is often substantially lower. Similarly, while BAL antigen testing for Histoplasma performs well in disseminated infections, it often fails to detect localized pulmonary disease. In this series, three out of four patients had negative BAL results in the presence of histopathologic confirmation of fungal infection. While current guidelines consider BAL positivity supportive of a “probable” diagnosis, tissue histopathology remains the gold standard for a “proven” infection. These findings emphasize the value and capability of RAB in obtaining direct tissue confirmation when conventional testing, such as BAL antigen analysis, is non-diagnostic. Conclusion RAB-guided biopsy of PPLs offers the opportunity for histopathologic confirmation of fungal infection when BAL testing is non-diagnostic. This approach can enhance upfront diagnostic yield in patients with suspected fungal pulmonary infections, avoiding delays in diagnosis and treatment initiation. This abstract is funded by: None