American Journal of Respiratory and Critical Care Medicine

Background Chronic rhinosinusitis (CRS) and nasal polyps (NP) are closely related inflammatory airway diseases, and their co-occurrence is often associated with more persistent symptoms, frequent recurrence, and substantial respiratory morbidity. However, the extent to which CRS without and with NP (CRSsNP and CRSwNP) share genetic susceptibility-and which genetic mechanisms are disease-specific-remains poorly characterized. Methods We conducted cross-population genome-wide association meta-analyses of overall CRS (including both CRSwNP and CRSsNP) and NP (a proxy for CRSwNP) using data from six biobanks. We estimated genome-wide genetic correlations between overall CRS, CRSwNP, and a spectrum of respiratory diseases. We applied five complementary gene-prioritization strategies to nominate CRS- and CRSwNP-associated genes and performed pathway enrichment analyses to infer implicated biological processes. For CRSwNP, we integrated single-cell transcriptomic data to characterize cell-type-specific expression of prioritized genes and used stratified LD score regression to quantify heritability enrichment across immune and epithelial annotations. To delineate shared versus disease-specific genetic signals, we performed three comparative analyses-local genetic correlation, CRSwNP-CRS colocalization, and genomic structural equation modeling. Finally, we performed proteome-wide Mendelian randomization to identify circulating proteins with putative causal effects on CRS and CRSwNP. Results This GWAS meta-analysis identified 96 genome-wide significant loci for CRSwNP and 41 for overall CRS, prioritizing 92 and 39 candidate genes, respectively. CRSwNP and overall CRS showed shared genetic susceptibility (rg = 0.59; P = 6.8e-16), while CRS exhibited broader genetic correlations across multiple respiratory disorders. Pathway analyses consistently implicated immune signaling albeit with disease-specific emphases and lipid-metabolism networks. Single-cell analyses demonstrated distinct expression of CRSwNP-prioritized genes across nasal epithelial and immune cell clusters, and immune annotations explained more CRSwNP heritability (enrichment score = 4.1; P = 0.010) than epithelial annotations (2.5; P = 0.072). Comparative genetic analyses highlighted multiple shared loci-including BACH2, CD247, FADS2, FOXP1, FUT2, GPX4, IL7R, NDFIP1, RAB5B, RORA, SMAD3, TSLP - as well as 3 CRSwNP-specific and 6 CRS-specific loci. Proteome-wide MR identified 10 and 8 putatively causal circulating proteins for CRSwNP and overall CRS, respectively, with protein TNFSF11, IL2RB, and STX4 associated with both conditions. Conclusions This multi-population GWAS meta-analysis expanded genetic discovery for CRS and CRSwNP and showed substantial shared liability with distinct disease-specific components. Immune components explained a larger proportion of CRSwNP heritability than epithelial annotations, reinforcing the primacy of immune-driven mechanisms in polyp disease.

AbstractO_ST_ABSRationaleC_ST_ABSIdiopathic pulmonary fibrosis (IPF) is an age-related disorder with common and rare genetic risk factors. It is unknown if the effects of PF genetic risk factors differ by chronologic age. ObjectivesTo assess age-specific effects of genetic risk factors in PF patients and their relatives. MethodsWe identified common and rare genetic risk factors using a Columbia whole genome sequencing (WGS) cohort (777 IPF, 2905 controls) and replicated findings using Trans-Omics for Precision Medicine (TOPMed, 1148 IPF, 5202 controls). We assessed age-stratified genetic risk of IPF and assessed for interaction with age across a range of cutoffs. We analyzed 313 FPF pedigrees and compared age-specific prevalence of interstitial lung disease in relatives stratified by proband genetic risk factors. Measurements and Main ResultsAdjusted odds of disease from MUC5B SNP increase with age, while odds of disease from rare variants decrease with age. The magnitude of the interaction term between age and both genetic variables was greatest in younger individuals. There were significant interactions between age <55 and the MUC5B SNP (discovery pinteraction=0.01; replication pinteraction<0.0001) and rare variants (discovery pinteraction<0.0001; replication pinteraction=0.03). Pedigree analysis showed more prevalent disease especially in younger relatives in FPF families with rare variants versus without (p<0.0001). ConclusionsAge modifies the effects of genetic risk factors in IPF. Rare variants confer greater risk in younger individuals whereas the MUC5B SNP confers greater risk in older individuals. Relatives of FPF patients with rare variants exhibit earlier prevalent disease, which has implications for preclinical disease screening.

RationaleThe association between immune-cell-specific transcriptomic profiles and Idiopathic Pulmonary Fibrosis (IPF) mortality is unknown. ObjectivesTo determine immune-cell-specific transcriptomic profiles associated with IPF mortality. MethodsWe profiled peripheral blood mononuclear cells (PBMC) in 18 participants [University of South Florida: IPF, COVID-19, post-COVID-19 Interstitial Lung Disease (Post-COVID-19 ILD), controls] by single-cell RNA sequencing (scRNA-seq) and identified 16 immune-cell-specific transcriptomic profiles. The Scoring Algorithm of Molecular Subphenotypes (SAMS) was used to calculate Up-scores based on these 16 gene profiles. Their association with outcomes was investigated in peripheral blood, Bronchoalveolar Lavage (BAL) and lung tissue of N=416 IPF patients from six cohorts. Findings were validated in an independent IPF, PBMC scRNA-seq dataset (N=38). Measurements and main resultsCox-regression models demonstrated that 230 genes from CD14+CD163-HLA-DRlow circulating monocytes predicted IPF mortality [Pittsburgh (p=0.02), Chicago (p=0.003)]. PBMC proportions of CD14+CD163-HLA-DRlow monocytes were higher in progressive versus stable IPF (Yale, 0.13{+/-}0.05 versus 0.09{+/-}0.05, p=0.034). Receiving operating characteristic identified a 230 gene, Up-score >41.84 (Pittsburgh) predictive of mortality in Chicago (HR: 6.58, 95%CI: 2.15-20.13, p=0.001) and in pooled analysis of BAL cohorts (HR: 2.20, 95%CI: 1.44-3.37, p=0.0003). High-risk patients had decreased expression of the T-cell co-stimulatory genes CD28, ICOS, ITK and LCK (Pittsburgh and Chicago, p<0.01). 230 gene-up-scores negatively correlated with Forced Vital Capacity (FVC) in IPF lung tissues (LGRC, rho=-0.2, p=0.02). Results were replicated using a subset of 13 genes from the 230-gene signature (pooled PBMC cohorts - HR: 5.34, 95%CI: 2.83-10.06, p<0.0001). ConclusionsThe transcriptome of CD14+CD163-HLA-DRlow monocytes is associated with increased IPF mortality.

ObjectiveAs our understanding of autoimmune laryngeal stenosis evolves, distinguishing patients who may benefit from systemic immunosuppression versus those needing only local treatment is increasingly important. In this study, we identify a distinct subset of autoimmune laryngeal stenosis characterized by edema of the inferior true vocal folds that extends to the superior aspect of the cricoid cartilage, termed "subcordal stenosis." The objective of this study is to characterize the clinical presentation and treatment outcomes of subcordal stenosis and compare it to typical autoimmune-related subglottic stenosis (AI-SGS). MethodsWe conducted a retrospective review of patients with laryngeal stenosis evaluated by both rheumatology and otolaryngology at our institution to identify two groups: patients with subcordal stenosis and those with typical AI-SGS. Data on immunosuppressive treatments and airway dilation procedures were collected. Time to first dilation was compared between groups. ResultsAmong 49 patients with laryngeal stenosis, 11 had subcordal involvement. Five of these also had subglottic disease, while six had isolated subcordal stenosis. Kaplan-Meier analysis showed significantly longer time to first dilation in patients with subcordal involvement (median 792 vs. 44 days; p = 0.048). They also underwent fewer dilations within two years (median 0 vs. 1; p = 0.05). ConclusionAmong laryngeal stenosis patients referred to rheumatology, those with subcordal involvement experienced fewer dilations and longer intervals before first dilation compared to those with typical AI-SGS. These findings suggest that subcordal stenosis may represent a distinct, glucocorticoid-responsive phenotype within autoimmune laryngeal stenosis, with implications for treatment selection and multidisciplinary care.

BackgroundThe pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH) is complex and multifactorial, with growing evidence indicating the involvement of hematologic disorders. Clonal hematopoiesis of indeterminate potential (CHIP) has recently been associated with increased risks of both hematologic malignancies and cardiovascular diseases. The CHIP in patients with CTEPH and its clinical relevance remain undetermined. MethodsWe performed a step-wise calling method on the next-generation sequencing data from 499 CTEPH patients referred to three centers between October 2006 and December 2021 to identify CHIP mutations. We associated CHIP with all-cause mortality in patients with CTEPH. To provide potential mechanistic insights, the associations between CHIP and inflammation characteristics reflected by circulating cytokines and IgG galactosylation, a hallmark of inflammatory state in diseases were also determined. ResultsTotal 51 (10.2%) patients with CTEPH carried at least one CHIP mutation at a variant allele frequency of [&ge;] 2%, and the most common mutations were among DNMT3A, RUN1 and STAG2. During a mean follow-up time of 55 months, deaths occurred in 21 patients (42.9%) in the CHIP group and 105 patients (24.3%) in the non-CHIP group, contributing to the 5-year survival rate of 65.3% in the CHIP group and 81.9% in the non-CHIP group (P < 0.001 for log-rank test). The association of CHIP with mortality remained robust in the fully adjusted model (HR: 3.447; 95% CI: 1.747 - 6.803; P < 0.001). Besides, patients in the CHIP group showed higher circulating IL-1beta and IL-6 and lower IL-4 and IgG galactosylation compared with the non-CHIP group. ConclusionsCHIP is enriched in CTEPH patients and is associated with a worse prognosis in CTEPH. Mechanically, patients in the CHIP group showed a more severe inflammatory state. Clinical Perspective What is new?O_LIClonal hematopoiesis of indeterminate potential (CHIP) mutations are enriched in chronic thromboembolic pulmonary hypertension (CTEPH) patients, with most common mutated genes being DNMT3A, RUN1 and STAG2. C_LIO_LICHIP is associated with worse clinical outcomes in CTEPH. C_LIO_LICHIP is associated with more severe inflammation state mediated by myeloid as well as lymphoid cells in patients with CTEPH. C_LI What are the clinical implications?O_LICHIP might be a risk factor for CTEPH, suggesting a relationship between CTEPH and hematopoietic disorders. C_LIO_LICHIP represented an additional disease component in CTEPH that independently impacts prognosis. C_LIO_LICHIP might be a potential target for personalized medicine and an indicator of benefit from anti-inflammatory therapies for CTEPH patients. C_LI

BackgroundTracheostomies in children are associated with significant morbidity, poor quality of life, excess healthcare costs, and excess mortality. The underlying mechanisms facilitating adverse outcomes in tracheostomised children are poorly understood. We aimed to characterise airway host defence in tracheostomised children using serial molecular analyses. MethodsTracheal aspirates, tracheal cytology brushings, nasal swabs and stool samples were prospectively collected from children with a tracheostomy and controls. Transcriptomic, proteomic, and metabolomic methods were applied to characterise the impact of tracheostomy on host immune response and the airway microbiome. ResultsChildren followed up serially from the time of tracheostomy up to three months post-procedure (n=9) were studied. A validation cohort of children with a long-term tracheostomy was also enrolled (n=24). Controls (n=13) comprised children without a tracheostomy undergoing bronchoscopy. Tracheostomy was associated with new, rapidly emergent and sustained airway neutrophilic inflammation, superoxide production and evidence of proteolysis when compared with controls. In contrast, reduced airway microbial diversity was established pre-tracheostomy and sustained thereafter. ConclusionsChildhood tracheostomy is associated with rapidly emergent and persistent airway neutrophil recruitment and activation, with sustained proteolysis and superoxide generation. These findings suggest neutrophil recruitment and activation as potential exploratory targets in seeking to prevent recurrent airway complications in this vulnerable group of patients. Key messageThe effect tracheostomy has on children is not described. Tracheostomy in children results in persistent local airway neutrophilic inflammation, proteolysis, superoxide production and dysbiosis.

IntroductionPulmonary arterial hypertension (PAH) involves progressive cellular and molecular change within the pulmonary vasculature, leading to increased vascular resistance. Current therapies targeting nitric oxide (NO), endothelin, and prostacyclin pathways yield variable treatment responses. Patients with systemic sclerosis-associated PAH (SSc-PAH) often experience worse outcomes than those with idiopathic PAH (IPAH). MethodsLung tissue samples from four SSc-PAH, four IPAH, and four failed donor specimens were obtained from the Pulmonary Hypertension Breakthrough Initiative (PHBI) lung tissue bank. Single-cell RNA sequencing (scRNAseq) was performed using the 10X Genomics Chromium Flex platform. Data normalization, clustering, and differential expression analysis were conducted using Seurat. Additional analyses included gene set enrichment analysis (GSEA), transcription factor activity analysis, and ligand-receptor signaling. Pharmacotranscriptomic screening was performed using the Connectivity Map. ResultsSSc-PAH samples showed a higher proportion of fibroblasts and dendritic cells/macrophages compared to IPAH and donor samples. GSEA revealed enriched pathways related to epithelial-to-mesenchymal transition (EMT), apoptosis, and vascular remodeling in SSc-PAH samples. There was pronounced differential gene expression across diverse pulmonary vascular cell types and in various epithelial cell types in both IPAH and SSc-PAH, with epithelial to endothelial cell signaling observed. Macrophage to endothelial cell signaling was particularly pronounced in SSc-PAH. Pharmacotranscriptomic screening identified TIE2, GSK-3, and PKC inhibitors, among other compounds, as potential drug candidates for reversing SSc-PAH gene expression signatures. DiscussionOverlapping and distinct gene expression patterns exist in SSc-PAH versus IPAH, with significant molecular differences suggesting unique pathogenic mechanisms in SSc-PAH. These findings highlight the potential for precision-targeted therapies to improve SSc-PAH patient outcomes. Future studies should validate these targets clinically and explore their therapeutic efficacy.

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, and often fatal disorder. Two FDA approved anti-fibrotic drugs, nintedanib and pirfenidone, slow the rate of decline in lung function, but responses are variable and side effects are common. Using an in-silico data-driven approach, we identified a robust connection between the transcriptomic perturbations in IPF disease and those induced by saracatinib, a selective Src kinase inhibitor, originally developed for oncological indications. Based on these observations, we hypothesized that saracatinib would be effective at attenuating pulmonary fibrosis. We investigated the anti-fibrotic efficacy of saracatinib relative to nintedanib and pirfenidone in three preclinical models: (i) in vitro in normal human lung fibroblasts (NHLFs); (ii) in vivo in bleomycin and recombinant adenovirus transforming growth factor-beta (Ad-TGF-{beta}) murine models of pulmonary fibrosis; and (iii) ex vivo in precision cut lung slices from these mouse models. In each model, the effectiveness of saracatinib in blocking fibrogenic responses was equal or superior to nintedanib and pirfenidone.

BackgroundPost-tuberculosis (TB) lung disease (PTLD) affects approximately 50% of persons with pulmonary TB. We recently discovered whole blood transcriptional signatures associated with PTLD. We examined whether a minimum gene signature predicts PTLD as a clinically useful biomarker. MethodsWe prospectively enrolled 301 treatment naive adults with newly diagnosed pulmonary TB (PTB) (cohort A). We collected whole blood at 0 and 6-month visits, isolated RNA, and measured a modified MTB Host Response (HR) signature (mHR) based on expression of DUSP3, GBP5, and TMBIM6. We recorded spirometry at 6 (n=216) and 12 months (n=210) after treatment initiation and examined the association of the mHR score with PTLD and Mtb aerosolization. We recruited household contacts of cohort A to compare mHR score with non-PTB participants (cohort B). FindingsmHR was associated with TB (p=4.15e-66) when compared to HHCs, treatment response (p=1.07e-53), and characteristics including CD4 count (p=0.003), bacillary load (p=3.02e-05), lung cavities (p=1.59e-04), and lung quadrants involved (p=3.87e-06). The mHR score was not associated with Mtb aerosolization. In total, 105 (50%) participants had PTLD at 12 months including 61 with restriction, 26 with obstruction, and 18 with mixed obstruction and restriction. Baseline mHR was associated with obstructive PTLD at both 6 (p=0.003) and 12 months (p=0.012) in bivariate and multivariate analyses. The mHR score was not associated with restrictive lung disease. InterpretationBaseline mHR was associated with obstructive PTLD at 6 and 12 months and may have applications in targeting treatment and prognostication.

RationaleAccelerated decline in lung function contributes to the development of chronic respiratory disease. Despite evidence for a genetic component, few genetic associations with lung function decline have been identified. ObjectivesTo evaluate genome-wide associations and putative downstream functionality of genetic variants with lung function decline in diverse general population cohorts. MethodsWe conducted genome-wide association study (GWAS) analyses of decline in the forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), and their ratio (FEV1/FVC) in participants across six cohorts in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium and the UK Biobank. Genotypes were imputed to TOPMed (CHARGE cohorts) or Haplotype Reference Consortium (HRC) (UK Biobank) reference panels, and GWAS analyses used generalized estimating equation models with robust standard error. Models were stratified by cohort, ancestry, and sex, and adjusted for important lung function confounders and genotype principal components. Results were combined in cross-ancestry and ancestry-specific meta-analyses. Selected top variants were tested for replication in two independent COPD-enriched cohorts. Measurements and Main ResultsOur discovery analyses included 52,056 self-reported White (N=44,988), Black (N=5,788), Hispanic (N=550), and Chinese American (N=730) participants with a mean of 2.3 spirometry measurements and 8.6 years of follow-up. Functional mapping of GWAS meta-analysis results identified 361 distinct genome-wide significant (p<5E-08) variants in one or more of the FEV1, FVC, and FEV1/FVC decline phenotypes, which overlapped with previously reported genetic signals for several related pulmonary traits. Of these, 8 variants, or 20.5% of the variant set available for replication testing, were nominally associated (p<0.05) with at least one decline phenotype in COPD-enriched cohorts (White [N=4,778] and Black [N=1,118]). Using the GWAS results, gene-level analysis implicated 38 genes, including eight (XIRP2, GRIN2D, SATB1, MARCHF4, SIPA1L2, ANO5, H2BC10, and FAF2) with consistent associations across ancestries or decline phenotypes. Annotation class analysis revealed significant enrichment of several regulatory processes for corticosteroid biosynthesis and metabolism. Drug repurposing analysis identified 43 approved compounds targeting eight of the implicated 38 genes. ConclusionsOur multi-ancestry GWAS meta-analyses identified numerous genetic loci associated with lung function decline. These findings contribute knowledge to the genetic architecture of lung function decline, provide evidence for a role of endogenous corticosteroids in the etiology of lung function decline, and identify drug targets that merit further study for potential repurposing to slow lung function decline and treat lung disease.

RationaleRestrictive allograft syndrome (RAS) is a major cause of mortality in patients following lung transplantation due to rapid progressive fibrosis in the pulmonary graft. We have only limited knowledge of the cellular and molecular mechanisms that characterize the fibrosis in the RAS lung. ObjectiveTo elucidate cellularly-resolved transcriptomic and histologic characteristics of the structural cells in human RAS lungs. MethodsSingle-nuclei RNA-sequencing was performed in peripheral lung tissues from 15 RAS patients undergoing lung re-transplantation, and from 9 healthy control lungs. Findings were validated and complemented by various histologic techniques, including immunofluorescence, RNAscope, combined Elastica van Gieson-immunohistochemistry stains, and micro-CT scans. Measurement and Main resultsDifferential gene expression analysis of our single-nuclei RNA-sequencing data revealed in human RAS lungs previously undescribed and uniquely distributed aberrant basaloid cells, ectopic COL15A1+ vascular endothelial cells, and CTHRC1+ fibrotic fibroblasts, all first characterized in idiopathic pulmonary fibrosis (IPF). In contrast to IPF, RAS lacks the cellular equivalent of bronchiolization. Histologic stains confirmed our transcriptomic discoveries and disclosed distinctive distribution patterns: Aberrant basaloid cells are primarily localized at the edge of the fibrotic pushing border, forming together with the juxtaposed CTHRC1+ fibrotic fibroblasts the fibrotic niche of alveolar fibroelastosis (AFE), the histopathological hallmark in RAS lungs. On the endothelial side, PRX+ alveolar microvasculature is lost in AFE areas. Micro-CT scans revealed that blood supply, now facilitated by expanded and ectopic COL15A1+ VE cells, changes from pulmonary to systemic perfusion. Last, our data reveals potential therapeutically-modifiable expression patterns in RAS, including genes coding for the integrin subunits v{beta}6, activators of TGF{beta}. ConclusionConsidering the marked clinical, histologic and etiologic dissimilarities of RAS and IPF, our snRNAseq study revealed a surprising general principle of cellular and molecular pathogenesis in the fibrosing lung: the entity-spanning composition of the fibrotic niche by a) aberrant basaloid cells localized at the fibrotic pushing border, b) ectopic COL15A1+ vascular ECs and c) effector CTHRC1+ fibrotic fibroblasts. This general principle justifies a flexible but cellular pathogenesis-guided transferability of potential therapeutic approaches between progressive fibrotic lung diseases.

BackgroundMutations are found in 10-20% of idiopathic PAH (IPAH) patients, but none are consistently identified in connective tissue disease-associated PAH (APAH), which accounts for [~]45% of PAH cases. TET2 mutations, a cause of clonal hematopoiesis of indeterminant potential (CHIP), predispose to an inflammatory type of PAH. We now examine mutations in another CHIP gene, DNMT3A, in PAH. MethodsWe assessed DNMT3A mutation prevalence in PAH Biobank subjects as compared with controls, first using whole exome sequencing (WES)-derived CHIP calls in 1832 PAH Biobank patients versus 7509 age-and sex-matched gnomAD controls. We then performed deep, targeted panel sequencing of CHIP genes on a subset of 710 PAH Biobank patients and compared the prevalence of DNMT3A mutations therein to an independent pooled control cohort (N = 3645). In another cohort of 80 PAH patients and 41 controls, DNMT3A mRNA expression was studied in peripheral blood mononuclear cells (PBMCs). Finally, we evaluated the development of PAH in a conditional, hematopoietic, Dnmt3a knockout mouse model. ResultsDNMT3A mutations were more frequent in PAH cases versus control subjects in the WES dataset (OR 2.60, 95% CI: 1.71-4.27). Among PAH patients, 33 had DNMT3A variants, most of whom had APAH (21/33). While 21/33 had somatic mutations (female:male 17:4), germline variants occurred in 12/33 (female:male 11:1). Hemodynamics were comparable with and without DNMT3A mutations (mPAP=58{+/-}21 vs. 52{+/-}18 mmHg); however, patients with DNMT3A mutations were unresponsive to acute vasodilator testing. Targeted panel sequencing identified that 14.6% of PAH patients had CHIP mutations (104/710), with DNMT3A accounting for 49/104. There was a significant association between all CHIP mutations and PAH in analyses adjusted for age and sex (OR 1.40, 95% CI: 1.09-1.80), though DNMT3A CHIP alone was not significantly enriched (OR:1.15, 0.82-1.61). DNMT3A expression was reduced in patient-derived versus control PAH-PBMCs. Spontaneous PAH developed in Dnmt3a-/- mice, and it was exacerbated by 3 weeks of hypoxia. Dnmt3a-/- mice had increased lung macrophages and elevated plasma IL-13. The IL-1{beta} antibody canakinumab attenuated PAH in Dnmt3a-/- mice. ConclusionsGermline and acquired DNMT3A variants predispose to PAH in humans. DNMT3A mRNA expression is reduced in human PAH PBMCs. Hematopoietic depletion of Dnmt3a causes inflammatory PAH in mice. DNMT3A is a novel APAH gene and may be a biomarker and therapeutic target.

BackgroundInterstitial lung disease (ILD) affects >40% of patients with systemic sclerosis (SSc/scleroderma) and is the leading cause of disease-related mortality. Although therapies may slow progression, outcomes remain poor, partly because ILD is often detected after irreversible lung injury has occurred. Although chest computed tomography (CT) is a sensitive tool for ILD detection and is recommended at SSc diagnosis, it is oftentimes not performed and even less often performed serially. We sought to develop tools to predict ILD and mortality in patients with SSc using data routinely available in the electronic health record (EHR) to inform medical decision-making. MethodsWe analyzed longitudinal EHR data from two SSc cohorts: Northwestern University (1,169 participants; derivation cohort) and Yale University (376 participants; validation cohort). We identified clinical features from existing cohort-linked EHR queries composing a convenience sample of data from participants spanning decades rather than employing a single unified data collection effort. Three ILD experts independently reviewed CT reports and classified each as having or lacking ILD. To explore derivation cohort data structure, patients with >=3 forced vital capacity (FVC) results available were identified and stratified according to prevalent or absent ILD. Using unsupervised trajectory-based clustering exploratory analyses, we determined standardized patterns across groups. ML models were then developed using clinical EHR data as predictor variables and prevalent ILD and all-cause mortality as outcome variables. Model performance was assessed using area under the receiver operating characteristic curve (AUC). ResultsSeventy-four clinical features with low missingness, including demographic, vital sign, laboratory, and pulmonary function test data, were utilized for analyses. Four robust PFT trajectory clusters were identified that were associated with ILD prevalence and mortality in exploratory analyses. A ML model for ILD detection achieved an AUC of 0.832 and retained performance in the Yale cohort (AUC 0.754). In addition to established predictors such as autoantibodies and pulmonary function, the model identified routine laboratory measurements, including red cell distribution width (RDW), white blood cell count, and serum chloride, as important contributors. One-year mortality prediction achieved AUCs of 0.904 in the North-western cohort and 0.910 in the Yale cohort. Among patients with SSc-ILD, one-year mortality was predicted with AUCs of 0.744 and 0.902 in the Northwestern and Yale cohorts, respectively. Unexpectedly, we found that subtle laboratory abnormalities (such as change in RDW) contributed to predicting mortality. ConclusionsOur prediction models comprised of widely available EHR data are useful tools to identify SSc patients at high risk for prevalent ILD and all-cause mortality. Integration of these models into clinical practice could enable scalable risk stratification and inform individualized ILD screening and monitoring strategies for SSc patients.

RationaleLung mucins are an understudied component of the mucosal immune response and may influence tuberculosis pathogenesis and outcomes. ObjectivesTo assess if variants in lung mucins MUC5B and MUC5AC are associated with Mycobacterium tuberculosis immune responses, susceptibility, and outcomes. MethodsWe characterized four haplotype tagging single nucleotide polymorphisms (SNPs) in MUC5B and MUC5AC for association with log2 TNF concentrations in cerebral spinal fluid (CSF) from TBM patients. SNPs associated with CSF TNF concentrations were carried forward for analyses of pulmonary and meningeal TB susceptibility and TBM mortality. Measurements and Main ResultsMUC5AC SNP rs28737416 T allele was associated with lower CSF concentrations of TNF(p=1.8*10-8) and IFN{gamma}(p=2.3*10-6), and higher TBM, but not pulmonary TB, susceptibility (OR 1.24, 95% confidence interval 1.03, 1.49; p=0.021). Mortality from TBM was higher among participants with the rs28737416 T/T and T/C genotype (35/119, 30.4%) versus the C/C genotype (11/89, 12.4%; log-rank p=0.005) in a Vietnamese cohort (N=211). This finding was confirmed in an independent Vietnamese validation cohort (N=87; 9/87, 19.1% vs 1/20, 2.5%; log-rank p=0.02) and an Indonesian validation cohort (N=468, 127/287, 44.3% vs 65/181, 35.9%, log-rank p=0.06). ConclusionsThe MUC5AC rs28737416 T/T and T/C genotypes were associated with higher susceptibility and mortality from TBM and lower CSF concentrations of TNF and IFN{gamma} compared to the C/C genotype, suggesting that MUC5AC contributes to immune changes that influence TBM outcomes.

BackgroundPleuroparenchymal fibroelastosis (PPFE) is a progressive interstitial lung disease with higher prevalence in females, histologically characterized by intra-alveolar fibrosis with septal elastosis (AFE). Effective treatments are lacking, highlighting the need to dissect its pathogenesis at single-cell resolution. MethodsWe performed single-nucleus RNA sequencing (snRNAseq) on explanted lungs from a German (n=23) and a French cohort (n=17) of PPFE patients, and controls (n=16). Identified cell populations were localized by immunofluorescence and multiplex RNA in-situ hybridization. Hierarchical phase-contrast computed tomography (HiP-CT) and micro-CT provided 3D spatial context. Reanalyzed snRNAseq data from a Belgian IPF cohort (n=9) served as disease comparator. FindingsWe present the first snRNAseq atlas of PPFEs cellular and structural landscape based on a European multinational cohort. 24 PPFE patients were female (60.0%), while 34 were non-smokers (85.0%). 519,920 nuclear transcriptomes from PPFE and IPF patients, and controls were profiled. We identified PPFE-specific accumulations of MFAP5+PI16+SFRP2+ adventitial and LEPR+ITGA8+SFRP2+DIO2+ elastofibrotic fibroblasts as main drivers of elastotic remodeling in PPFE. Multiple PPFE fibroblast subsets acquire an inflammatory activation state as highlighted by the expression of CXCL12 and CXCL14. This is accompanied by a marked increase in lymphocytes and the formation of tertiary lymphoid structures (TLS) in a disease that was previously considered to be purely elastofibrotic. We identified CTHRC1+ fibrotic fibroblasts and Aberrant Basaloid cells in PPFE as well, forming the "Usual Fibrotic Niche". 3D reconstruction of the pronounced COL15A1+ vascular conglomerate at the border of the elastofibrotic and subpleural fibrosis indicates communication with interlobar veins. Last, we observed a zonation of the PPFE lesion, constructed by the above-mentioned PPFE-associated cell types. InterpretationOur unprecedented cellular and molecular survey uncovers previously unobserved PPFE-specific inflammatory and elastogenic fibroblast populations, as well as the presence of CTHRC1+ fibroblasts and Aberrant Basaloid cells common to other fibrotic ILDs. These findings provide the foundation for including PPFE patients in current antifibrotic trials, as well as development of PPFE-specific therapies. FundingSupported mainly by the Else Kroner-Fresenius Foundation, the German Center for Lung Research and the Fondation du Souffle.

RationaleHypersensitivity pneumonitis (HP) is an immunologically mediated form of lung disease resulting from inhalational exposure to various antigens. While there is growing understanding of the immune cells involved in HP, the relationship between clinical outcomes and circulating cell types in HP is not well established. MethodsSingle-cell RNA sequencing was performed on peripheral blood mononuclear cells (PBMCs) from 40 patients with fibrotic hypersensitivity pneumonitis (fHP) in a clinical trial of pirfenidone (NCT02958917). After quality control, we compared data from 33 fHP patients with 36 sex-matched healthy controls (GSE196735). Using Seurat v5, we harmonized the data, formed clusters, and reduced dimensionality through UMAP. Cell type identities were assigned based on a published reference (GSE271789), with clusters annotated for predominant cell type(s) present in at least 30% of the cells. We compared cell type proportions between fHP and HC using the chi-squared test and performed differential expression analysis with DESeq2 on pseudobulk counts, adjusting for sex. Genes significantly upregulated in fHP versus HC at an FDR-adjusted p-value of 0.01 were used to create a multivariate predictive signature for clinical outcomes in fHP participants. Performance was assessed through leave-one-out cross-validation for prediction accuracy. ResultsCompared to HC, fHP has an increased proportion of non-classical CD16+ monocytes (4.2% fHP vs. 1.5% HC), C14+ monocytes with a myeloid-derived dendritic phenotype (2.1% fHP vs. 0.1% HC), platelets (1.0% fHP vs. 0.3% HC), plasmacytoid dendritic cells (0.5% fHP vs. 0.1% HC) and predominantly classical CD14+ monocytes (29.5% fHP vs. 3.4% HC, adjusted-p<0.001). In patients with fHP, cell clusters were associated with the presence of baseline chest CT honeycombing, increased extent of CT lung fibrosis, and worse progression-free survival. CD14+ monocytes consistently demonstrated a high prediction accuracy (>0.90) for these clinical metrics. ConclusionsPeripheral monocyte clusters may be valuable prognostic markers, potentially helping identify at-risk fHP patients.

RationaleDisruption of respiratory bacterial communities predicts poor clinical outcomes in critical illness; however, the role of respiratory fungal communities (mycobiome) is poorly understood. ObjectivesWe investigated whether mycobiota variation in the respiratory tract is associated with host-response and clinical outcomes in critically ill patients. MethodsTo characterize the upper and lower respiratory tract mycobiota, we performed rRNA gene sequencing (internal transcribed spacer) of oral swabs and endotracheal aspirates (ETA) from 316 mechanically-ventilated patients. We examined associations of mycobiome profiles (diversity and composition) with clinical variables, host-response biomarkers, and outcomes. Measurements and Main ResultsETA samples with >50% relative abundance for C. albicans (51%) were associated with elevated plasma IL-8 and pentraxin-3 (p=0.05), longer time-to-liberation from mechanical ventilation (p=0.04) and worse 30-day survival (adjusted hazards ratio (adjHR): 1.96 [1.04-3.81], p=0.05). Using unsupervised clustering, we derived two clusters in ETA samples, with Cluster 2 (39%) showing lower alpha diversity (p<0.001) and higher abundance of C. albicans (p<0.001). Cluster 2 was significantly associated with the prognostically adverse hyperinflammatory subphenotype (odds ratio 2.07 [1.03-4.18], p=0.04) and predicted worse survival (adjHR: 1.81 [1.03-3.19], p=0.03). C. albicans abundance in oral swabs was also associated with the hyper-inflammatory subphenotype and mortality. ConclusionsVariation in respiratory mycobiota was significantly associated with systemic inflammation and clinical outcomes. C. albicans abundance emerged as a negative predictor in both the upper and lower respiratory tract. The lung mycobiome may play an important role in the biological and clinical heterogeneity among critically ill patients and represent a potential therapeutic target for lung injury in critical illness.

RationaleProgressive fibrosing interstitial lung disease features "advancing fronts" where new matrix is deposited, but the signals sustaining these propagating niches remain incompletely defined. ObjectivesTo determine the spatial and temporal compartments in which HIF-1 operates during fibrotic progression and to test whether myeloid HIF-1 is a tractable driver of lesion propagation. MethodsWe integrated human IPF datasets, clinical severity profiling, sarcoidosis peripheral blood immune phenotyping, multiplex immunofluorescence and spatial mapping in human lung tissue, single-cell transcriptomic analyses, and temporally staged bleomycin lung injury with genetic and lung-directed therapeutic perturbations. Measurements and Main ResultsIn the Lung Genome Research Consortium cohort, HIF1A expression was increased in IPF lungs and correlated with higher GAP scores. In sarcoidosis, circulating monocytes from patients with progressive disease exhibited increased HIF-1 compared with those with resolving disease. In IPF lungs, nuclear HIF-1 localized predominantly to CD68 macrophages and PDGFR fibroblasts concentrated within collagen-rich, SMA advancing fronts, and single-cell analyses demonstrated enrichment of HIF-1-linked transcriptional programs consistent with macrophage-fibroblast crosstalk (including pro-fibrotic growth factors, chemokines, and matrix-regulatory pathways). In bleomycin-induced fibrosis, HIF-1 activity emerged first in macrophages and subsequently in fibroblasts within pimonidazole-marked hypoxic rims bordering nascent SMA foci. Myeloid-specific Hif1a deletion reduced front-associated macrophage persistence, attenuated fibroblast activation, and decreased collagen deposition. Two lung-directed strategies, inhaled liposomal echinomycin and inhaled shHif1a lipid nanoparticles, phenocopied these effects, demonstrating therapeutic tractability. ConclusionsThese findings define a hypoxic front-zone niche in which myeloid HIF-1 sustains macrophage persistence and promotes fibroblast activation and matrix remodeling. By linking spatial compartmentalization to causal genetics and lung-directed intervention, our work identifies myeloid HIF-1 as a mechanism-anchored, locally targetable driver of fibrotic lesion propagation.

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive, fatal disease characterised by excessive extracellular matrix deposition within the lung. Recent advances in single-cell RNA sequencing have identified distinct fibrotic populations, yet their origins and spatial relationships remain incompletely understood. MethodsUsing spatial transcriptomics and Hyperion imaging mass cytometry we compared the cellular composition in formalin fixed paraffin embedded fibrotic lesions (n=9 patients) with control lung (n=9), and cellular interactions were inferred using CellChat V2 ligand-receptor analysis. Monolayers of airway epithelial cells were used to identify changes in keratin (KRT) expression following cell detachment and cyclical mechanical stretch. ResultsSpatial multiomics profiling of human lung cells confirmed the in situ localisation of previously described IPF-enriched populations, and identified a previously unrecognized KRT5low/KRT17 epithelial population derived from airway basal cells that progressively acquiring molecular features of aberrant basaloid cells, forming a unique fibrotic niche enriched with the Secreted Phosphoprotein 1 (SPP1) positive macrophages. Functional studies demonstrated that epithelial detachment and cyclical mechanical stretch drive KRT5 reduction, providing a mechanism for the emergence of this transitional state. In addition, we also identified distinct immune-stromal niches enriched in lymphocytes and alveolar fibroblasts. ConclusionThese findings delineate distinct fibrotic epithelial niches in IPF and support a model in which epithelial loss induces aberrant basaloid differentiation and fibroblast activation, with subsequent airway traction and epithelial detachment generating a secondary niche enriched in basal-derived KRT5low/KRT17 cells and SPP1 macrophages.

BackgroundIdiopathic pulmonary fibrosis is a fatal lung disease of progressive lung parenchymal scarring caused by the aberrant response of an alveolar epithelium repeatedly exposed to injury. Understanding epithelial dysfunction has been hampered by the lack of physiological alveolar type 2 (AT2) cell models and defined disease triggers. Monogenic forms of familial pulmonary fibrosis (FPF) caused by toxic gain-of-function variants provide an opportunity to investigate early pathogenic events. One such variant, surfactant protein C (SFTPC)-I73T, abnormally localises within AT2 cells and causes their dysfunction. MethodsWe used base editing of fetal lung-derived AT2 (fdAT2) organoids to create a heterozygous disease model of endogenous SFTPC-I73T expression. We also created an inducible overexpression system to interrogate temporal changes associated with SFTPC-I73T expression. We cultured fdAT2 both in 3D culture and at air-liquid interface to understand the importance of polarity cues and air exposure on disease phenotypes. ResultsIn our heterozygous endogenous expression system, we found that fdAT2 expressing SFTPC-I73T grew without a lumen and were unable to correctly polarise. SFTPC-I73T accumulated with time and caused gross enlargement of early endosomes, preventing correct apico-basal trafficking of multiple endosomally trafficked cargoes including polarity markers and cell adhesion proteins. This phenotype was exacerbated by air exposure and led to loss of epithelial monolayer integrity and abnormal wound healing after injury. ConclusionUsing endogenous gene editing for the first time in differentiated alveolar organoids, we have demonstrated that the pathogenic effects of SFTPC-I73T are mediated through endosomal dysfunction and abnormal epithelial organisation. This has important implications for AT2 function in vivo.