Project description:Rationale: The diagnosis of idiopathic pulmonary fibrosis (IPF) requires exclusion of an underlying autoimmune disease, as present in interstitial lung diseases associated with connective tissue diseases (CTD-ILD). The prevalence of autoantibodies in IPF patients is currently unknown. Objectives: An unbiased assay for de novo discovery of autoantigens can help characterizing autoreactivities in IPF patients beyond clinically established autoimmune panels. Methods: We developed the proteomic Differential Antigen Capture (DAC) assay, capturing patient antibodies from plasma, followed by affinity purification coupled to mass spectrometry (AP-MS). The DAC assay quantifies the binding capacity of patient antibodies to proteins in a pooled native extract from lung explants (ILD explants n=41; donor controls n=12). Plasma antibodies from patients with IPF (n=35), CTD-ILD (n=24) and age-matched controls (n=32) were analyzed and validated in an independent cohort (IPF: n=40; CTD-ILD: n=20). Plasma antibody binding profiles were associated with clinical meta-data including diagnosis, lung function and transplant free survival. Measurements and Main Results: We identified 586 putative autoantigens in both study cohorts with a broad heterogeneity among disease entities and cohorts. On average, in IPF a mean±SD of 16±40 autoantigens and in CTD-ILD a mean±SD of 9±15 autoantigens were identified per patient. We identified 18 IPF-specific autoantigens validated in the second cohort. Interestingly, there was also a high number of shared autoantigens in IPF and CTD-ILD patients, with 17 being present in IPF and CTD-ILD of both cohorts. Presence of antibodies to Thrombospondin 1 (THBS1) and tubulin beta-1 chain (TUBB1) was associated with a significantly reduced survival in patients with IPF (p=0.002 and p=0.019, respectively). This signature was often associated with autoreactivity against talin-1 (TLN1), latent-transforming growth factor beta-binding protein 1 (LTBP1), epididymis secretory protein Li 112 (HEL-S-112), zyxin (ZYX), the LIM and senescent cell antigen-like-containing domain protein 1 (LIMS1) and caldesmon (CALD1). Conclusions: Unbiased proteomic profiling reveals that the overall prevalence of autoantibodies is similar in IPF and CTD-ILD patients and identifies novel IPF specific autoantigens associated with patient survival.

Project description:The Rationale: Molecular markers of disease activity that are predictive of forced vital capacity (FVC) progression in idiopathic pulmonary fibrosis are needed. Objectives: Develop a predictor using longitudinal within-patient gene expression differences (ΔGE) in peripheral blood mononuclear cells (PBMC) to predict of FVC progression. Methods: Patients in the training cohort (n=74) experiencing ≥10% relative reduction in FVC% of predicted over 12 months were categorized as progressors in contrast to the remaining stable patients. Baseline to 4-month within-patient ΔGE were correlated with FVC status. FVC-predictor genes were prioritized by two-group comparison with FDR<5%, logistic LASSO regression with p<0.05, and 10-Fold Cross-Validation with ≥50% support. Receiver operating characteristic with area under the curve (AUC) analyses were conducted in training subsets and independent validation cohorts from UChicago (n=27), UPMC (n=35), and Imperial (n=24) where different transcriptome assay platforms and varying transcriptome sampling times were used to derive ΔGE. Results: Intra-subject Compared to cross-sectional analysis of baseline GE, our longitudinal ΔGE variation approach demonstratedlargely reduced within-group sample variation and increased statistic power fin progressor and stable groups for prediction model development. A 25-gene FVC-predictor separated “progressors” from “stable” by Principal Component Analysis in the training and subsets of the training cohort. The resulting FVC-predictor consistently demonstrated high discriminatory performance independent of transcriptome assay platforms and varying sampling times in validation cohorts (AUC= 0.77-0.80). TGF beta was the highest-ranking canonical pathway by Gene Set Enrichment Analysis. Conclusions: Our novel short-term longitudinal within-patient ΔGE approach identified a FVC-predictor which may reflect disease activity and prove to be a reliable biomarker predictive of future FVC decline.

Project description:BackgroundGiven the plethora of pathophysiologic mechanisms described in idiopathic pulmonary fibrosis (IPF), we hypothesize that the mechanisms driving fibrosis in IPF may be different from one patient to another.Research questionDo IPF endotypes exist and are they associated with outcome?Study design and methodsUsing a publicly available gene expression dataset retrieved from BAL samples of patients with IPF and control participants (GSE70867), we clustered IPF samples based on a dimension reduction algorithm specifically designed for -omics data, called DDR Tree. After clustering, gene set enrichment analysis was performed for functional annotation, associations with clinical variables and prognosis were investigated, and differences in transcriptional regulation were determined using motif enrichment analysis. The findings were validated in three independent publicly available gene expression datasets retrieved from IPF blood samples.ResultsOne hundred seventy-six IPF samples from three centers were clustered in six IPF clusters, with distinct functional enrichment. Although clinical characteristics did not differ between the clusters, one cluster conferred worse sex-age-physiology score-corrected survival, whereas another showed a numeric trend toward worse survival (P = .08). The first was enriched for increased epithelial and innate and adaptive immunity signatures, whereas the other showed important telomere and mitochondrial dysfunction, loss of proteostasis, and increased myofibroblast signatures. The existence of these two endotypes, including the impact on survival of the immune endotype, was validated in three independent validation cohorts. Finally, we identified transcription factors regulating the expression of endotype-specific survival-associated genes.InterpretationGene expression-based endotyping in IPF is feasible and can inform clinical evolution. As endotype-specific pathways and survival-associated transcription factors are identified, endotyping may open up the possibility of endotype-tailored therapy.

Dataset Information

Impact of Idiopathic Pulmonary Fibrosis on Longitudinal Health-care Utilization in a Community-Based Cohort of Patients.

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