Clinical significance of serum hyaluronan in chronic fibrotic interstitial pneumonia

Hyaluronan is an important constituent of the extracellular matrix in lungs, and growing evidence demonstrates its important biological properties in the lung. However, its role in interstitial pneumonia remains to be fully clarified. The goal of this study was to clarify the role of hyaluronan in interstitial pneumonia.

Hyaluronan in serum and bronchoalveolar lavage (BAL) fluid of chronic interstitial pneumonia (CIP) patients was measured, and the correlation with clinical parameters was determined. In addition, the correlation between hyaluronan in serum and clinical parameters was analysed in patients with acute exacerbation of interstitial pneumonia (IP‐AE).

When compared with healthy controls, serum hyaluronan was significantly greater in patients with CIP and was positively correlated with serum biomarkers of inflammation and fibrosis, such as C‐reactive protein and surfactant protein‐D. In BAL fluid, the amount of hyaluronan was positively correlated with the percentage of inflammatory cells and the amount of CXCL8. When compared with CIP patients, patients with IP‐AE had significantly greater amounts of serum hyaluronan, and patients with the highest serum hyaluronan had the worst 60‐day outcomes.

This work suggests that serum hyaluronan may be a clinically useful biomarker of interstitial pneumonia and suggests the possibility that hyaluronan is involved in the pathogenesis of interstitial pneumonia by recruiting inflammatory cells into the lungs.