The role of the endothelial glycocalyx in fibrotic interstitial lung disease

Background and Aims The interstitial lung diseases are a heterogenous group of conditions with varying degrees of inflammation and fibrosis of the lungs. Disruption of the endothelial glycocalyx (EG) and subsequent vascular remodelling has been implicated in the pathogenesis of organ fibrosis but its role in the pathogenesis of pulmonary fibrosis is unknown. We aimed to assess the acceptability of EG assessment using sublingual video-microscopy and compare EG health between patients with fibrotic-ILD and healthy controls.

Methods Patients with fibrotic-ILD and age and sex matched healthy controls were recruited to a prospective observational study (PREDICT-ILD NCT05609201). Participants with diabetes, renal disease (eGFR<60) or connective tissue disease were excluded. EG assessment was performed using sublingual side-stream darkfield video-microscopy (GlycoCheck^TM). GlycoCheck^TM measures perfused boundary region (PBR) in vessels 5–25μm in width, a surrogate for EG width. Acceptability was measured using a modified theoretical framework of acceptability questionnaire. Participants in the fibrotic-ILD arms underwent pulmonary function testing on the same day as EG assessment.