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.

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Identification and functional prediction of long noncoding RNA and mRNA related to connective tissue disease-associated interstitial lung diseases

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