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Biological sex, gender and race are important considerations in patients with interstitial lung diseases (ILD).Do patient's sex assigned at birth and race influence ILD treatment initiation?Patients with ILD from three longitudinal prospective registries were compared in this observational study. ILD-related medications included antifibrotics and immunomodulating medications. Race was dichotomized as "White" vs non-White". Time to treatment initiation was determined from the date of initial ILD registry visit to the date of first medication initiation. Proportions of treated patients were compared between groups using Chi2 test. Cox proportional analysis was used to determine how sex and race was associated with time to treatment initiation stratified by ILD diagnosis.A total of 4572 patients were included across all cohorts. The proportion of men who received treatment was higher than for women in the Canadian cohort (47 vs 40%, p,0.001), and the proportion of White patients who received treatment was also higher compared to non-Whites (46 vs 36%, p0.001). In contrast, the proportion of treated men in the Chicago cohort was lower compared to women (56 vs 64%, p=0.005), and that of White patients was lower compared to non-Whites (56 vs 69%, p0.001). No sex- or race-based differences in proportions of patients treated were found in the Australasian cohort. White race was significantly associated with earlier treatment initiation compared to non-White patients across diagnoses in the Canadian cohort, while the opposite association was found in the Australasian cohort.Sex- and racial-based differences exist in the initiation of ILD treatment, with variability across different cohorts in different countries. Reasons for these differences need to be further explored in future studies.

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SummaryInterstitial lung diseases (ILD) are heterogeneous conditions that may lead to progressive fibrosis and death of affected individuals. Despite diversity in clinical manifestations, enlargement of lung-associated lymph nodes (LLN) in fibrotic ILD patients predicts worse survival. Herein, we revealed a common adaptive immune landscape in LLNs of all ILD patients, characterized by highly activated germinal centers and antigen-activated T cells including regulatory T cells (Tregs). In support of these findings, we identified serum reactivity to 17 candidate auto-antigens in ILD patients through a proteome-wide screening using phage immunoprecipitation sequencing. Autoantibody responses to actin binding LIM protein 1 (ABLIM1), a protein highly expressed in aberrant basaloid cells of fibrotic lungs, were correlated with LLN frequencies of T follicular helper cells and Tregs in ILD patients. Together, we demonstrate that end-stage ILD patients have converging immune mechanisms, in part driven by antigen-specific immune responses, which may contribute to disease progression.

We highlight recent advances in the understanding of how environmental and occupational exposures increase the risk of developing interstitial lung disease (ILD), and how to evaluate a patient for potential exposures.A review of emerging literature suggests that environmental and occupational exposures can be directly causal, as in the case of the pneumoconioses and smoking-related ILDs, or one of many contributors to disease, as in the case of idiopathic pulmonary fibrosis (IPF). Regardless of the level of association, exposures are clearly prevalent across all ILD subtypes studied.Inhalational exposures are increasingly recognized as an important component in the development of ILDs, and novel exposure-disease associations continue to be discovered. These exposures represent potential opportunities for further understanding the pathobiology of disease and for the prevention of these often progressive and debilitating disorders. Prospective, comprehensive data collection regarding occupational and environmental exposures are needed in ILD patients to fully elucidate specific antigens and their relationships to disease incidence and outcomes. Systematically collected exposure information will also inform potential interventions to remediate exposures and thus mitigate the course of frequently progressive and fatal diseases.

Interstitial lung diseases (ILDs) are a heterogeneous group of disorders that can develop in patients with connective tissue diseases (CTD). Establishing autoimmunity in ILD impacts prognosis and treatment. ILD patients are screened for autoimmunity by assaying for anti-nuclear autoantibodies, rheumatoid factors and other non-specific tests. However, this approach has not been rigorously validated and may miss autoimmunity that manifests as autoantibodies to tissue antigens not previously defined in ILD. Here, we use Phage Immunoprecipitation-Sequencing (PhIP-Seq) to conduct a large, multi-center unbiased autoantibody discovery screen of ILD patients and controls. PhIP-Seq identified 17 novel autoreactive targets, and machine learning classifiers derived from these targets discriminated ILD serum from controls. Among these 17 candidates, we validated Cadherin Related Family Member 5 (CDHR5) as an autoantigen and found CDHR5 autoantibodies in patients with rheumatologic disorders and importantly, subjects not previously diagnosed with autoimmunity. Lung tissue of CDHR5 autoreactive patients showed transcriptional profiles consistent with activation of NFκB signaling and upregulation of chitotriosidase (CHIT1), a molecular pathway linked to fibrosis. Our study shows PhIP-Seq uncovers novel autoantibodies in ILD patients not revealed by standard clinical tests. Furthermore, CDHR5 autoantibodies may define a novel molecular endotype of ILD characterized by inflammation and fibrosis.

Current American Thoracic Society (ATS) standards promote the use of race and ethnicity-specific reference equations for pulmonary function test (PFT) interpretation. There is rising concern that the use of race and ethnicity in PFT interpretation contributes to a false view of fixed differences between races and may mask the effects of differential exposures. This use of race and ethnicity may contribute to health disparities by norming differences in pulmonary function. In the United States and globally, race serves as a social construct that is based on appearance and reflects social values, structures, and practices. Classification of people into racial and ethnic groups differs geographically and temporally. These considerations challenge the notion that racial and ethnic categories have biological meaning and question the use of race in PFT interpretation. The ATS convened a diverse group of clinicians and investigators for a workshop in 2021 to evaluate the use of race and ethnicity in PFT interpretation. Review of evidence published since then that challenges current practice and continued discussion concluded with a recommendation to replace race and ethnicity-specific equations with race-neutral average reference equations, which must be accompanied with a broader re-evaluation of how PFTs are used to make clinical, employment, and insurance decisions. There was also a call to engage key stakeholders not represented in this workshop and a statement of caution regarding the uncertain effects and potential harms of this change. Other recommendations include continued research and education to understand the impact of the change, to improve the evidence for the use of PFTs in general, and to identify modifiable risk factors for reduced pulmonary function.

Pulmonary fibrosis (PF) is characterized by profound scarring and poor survival. We investigated the association of leukocyte telomere length (LTL) with chronological age and mortality across racially diverse PF cohorts. LTL measurements among participants with PF stratified by race/ethnicity were assessed in relation to age and all-cause mortality, and compared to controls. Generalized linear models were used to evaluate the age-LTL relationship, Cox proportional hazards models were used for hazard ratio estimation, and the Cochran–Armitage test was used to assess quartiles of LTL. Standardized LTL shortened with increasing chronological age; this association in controls was strengthened in PF (R = −0.28; P

RATIONALE: Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by limited treatment options and high mortality. A better understanding of the molecular drivers of IPF progression is 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

RATIONALE: Criteria for progressive pulmonary fibrosis (PPF) have been proposed, but their prognostic value beyond categorical decline in forced vital capacity (FVC) remains unclear. OBJECTIVE: To determine whether proposed PPF criteria predict transplant-free survival (TFS) in patients with non-idiopathic pulmonary fibrosis (IPF) forms of interstitial lung disease (ILD). METHODS: A retrospective, multi-center cohort analysis was performed. Patients diagnosed with fibrotic connective tissue disease associated ILD, fibrotic hypersensitivity pneumonitis and non-IPF idiopathic interstitial pneumonia from three US centers and one UK center comprised test and validation cohorts, respectively. Cox proportional hazards regression was used to test the association between five-year TFS and 10% FVC decline, followed by thirteen additional PPF criteria satisfied in the absence of >=10% FVC decline. MAIN RESULTS: One thousand three hundred forty-one patients met inclusion criteria. A >=10% relative FVC decline was the strongest predictor of reduced TFS and showed consistent TFS association across cohorts, ILD subtypes and treatment groups, resulting in a phenotype that closely resembled IPF. Ten additional PPF criteria satisfied in the absence of >=10% relative FVC decline were also associated with reduced TFS in the US test cohort, with six maintaining TFS association in the UK validation cohort. Validated PPF criteria requiring a combination of physiologic, radiologic, and symptomatic worsening performed similarly to their stand-alone components but captured a smaller number of patients. CONCLUSIONS: An FVC decline of >=10% and six additional PPF criteria satisfied in the absence of such decline identify non-IPF ILD patients at increased risk of death or lung transplant.

RationaleIdiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by limited treatment options and high mortality. Novel therapies and prognostic biomarkers are needed.ObjectiveTo identify and validate molecular determinants of IPF survival.MethodsA 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−5) were advanced for stage II testing and meta-analyzed to identify those reaching genome-wide significance (p−8). Downstream analyses were performed for genes and proteins associated with variants reaching genome-wide significance.Main ResultsAfter 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=9.45×10−9). 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.ConclusionsWe 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.

Inhalational exposures are a known cause of interstitial lung disease (ILD), but little is understood about their prevalence across ILD subtypes and their relationship with pulmonary function and survival.Patients with fibrotic ILD were identified from the multicentre Canadian Registry for Pulmonary Fibrosis. Patients completed questionnaires regarding ILD-related occupational and environmental exposures. The relationship between exposures and the outcomes of baseline age, gender, family history, pulmonary function and survival was analysed using linear and logistic regression models, linear mixed-effect regression models and survival analysis using multivariable Cox proportional hazards along with the log-rank test.There were 3820 patients included in this study, with 2385 (62%) having ILD-related inhalational exposure. Exposed patients were younger, particularly in the idiopathic pulmonary fibrosis subgroup. Inhalational exposure was associated with male gender (adjusted OR 1.46, 95% CI 1.28-1.68, p 0.001) and family history of pulmonary fibrosis (adjusted OR 1.73, 95% CI 1.40-2.15, p 0.001). Patients with any inhalational exposure had improved transplant-free survival (hazard ratio 0.81, 95% CI 0.71-0.92, p = 0.001); this effect persisted across diagnostic subtypes. The relationship between exposures and annual change in forced vital capacity varied by ILD subtype.Patients with fibrotic ILD report high prevalence of inhalational exposures across ILD subtypes. These exposures were associated with younger age at diagnosis, male gender and family history of pulmonary fibrosis. Identification of an inhalational exposure was associated with a survival benefit. These findings suggest that inhaled exposures may impact clinical outcomes in patients with ILD, and future work should characterize the mechanisms underlying these relationships.

ImportancePulmonary fibrosis (PF) is characterized by progressive scarring of lung tissue and poor survival. Racial and ethnic minority populations face the greatest risk of morbidity and mortality from disparities impacting respiratory health, but the pattern of age at clinically relevant outcomes across diverse racial and ethnic populations with PF is unknown.ObjectiveTo compare the age at PF-related outcomes and the heterogeneity in survival patterns among Hispanic, non-Hispanic Black, and non-Hispanic White participants.Design, Setting, and ParticipantsThis cohort study included adult patients with a PF diagnosis and used data from prospective clinical registries: the Pulmonary Fibrosis Foundation Registry (PFFR) for the primary cohort and registries from 4 geographically distinct tertiary hospitals in the US for the external multicenter validation (EMV) cohort. Patients were followed between January 2003 and April 2021.ExposuresRace and ethnicity comparisons between Black, Hispanic, and White participants with PF.Main Outcomes and MeasuresAge and sex distribution of participants were measured at the time of study enrollment. All-cause mortality and age at PF diagnosis, hospitalization, lung transplant, and death were assessed in participants over 14 389 person-years. Differences between racial and ethnic groups were compared using Wilcoxon rank sum tests, Bartlett 1-way analysis of variance, and χ2 tests, and crude mortality rates and rate ratios were assessed across racial and ethnic categories using Cox proportional hazards regression models.ResultsIn total, 4792 participants with PF were assessed (mean [SD] age, 66.1 [11.2] years; 2779 [58.0%] male; 488 [10.2%] Black, 319 [6.7%] Hispanic, and 3985 [83.2%] White); 1904 were in the PFFR and 2888 in the EMV cohort. Black patients with PF were consistently younger than White patients (mean [SD] age at baseline, 57.9 [12.0] vs 68.6 [9.6] years; P P P P P Conclusions and RelevanceIn this cohort study of participants with PF, racial and ethnic disparities, especially among Black patients, were found in PF-related outcomes, including earlier onset of death. Further research is essential to identify and mitigate the underlying responsible factors.

Interstitial lung disease (ILD), a group of disorders characterized by scarring of the lungs, often leads to fatal impairment of respiratory function. While some patients exhibit features of autoimmunity, the role of the immune system within this heterogeneous group of disorders remains a matter of debate. We previously reported the enlargement of lung-draining lymph nodes (LLN) correlates with decreased survival in ILD patients, suggesting that activation of the adaptive immune system may contribute to pathophysiology. To investigate the composition and functional state of cells in the enlarged LLN, we performed flow cytometry analysis of LLN cells from endstage ILD patients undergoing transplantation (n=53) and control organ donors (n=36). We found that T cells from the ILD LLN exhibit effector memory phenotypes and significantly upregulate activation molecules including HLA-DR, CD38, CD154 and CD137, which are indicative of an ongoing immune response. Analyses of CD4 T cells revealed that Foxp3+CD25− regulatory T cells are specifically increased in ILD LLN. Moreover, follicular helper T cells and germinal center (GC) B cells are highly enriched, suggesting that antibody responses are activated in ILD LLN. To test the hypothesis that autoantigens may drive the augmented GC response, we screened circulating antibodies from ILD patients at two medical centers against the entire human peptidome using phage immunoprecipitation sequencing. We defined novel and shared autoantigens and experimentally validated antibody bindings to 5 protein antigens. Collectively, our findings suggest that antigen-specific immune responses may be involved in the pathophysiology and identify novel autoantigens for subsets of ILD.