Epithelial apoptosis as a clinical marker in idiopathic interstitial pneumonia

Epithelial cell apoptosis plays an important role in the pathogenesis of idiopathic interstitial pneumonia (IIP).

Serum levels of caspase-cleaved cytokeratin-18 (M30) were measured in 55 patients with IIP and 34 healthy controls using enzyme-linked immunosorbent assays. The IIP cases included usual interstitial pneumonia (UIP; n = 30), nonspecific interstitial pneumonia (NSIP; n = 15), and cryptogenic organizing pneumonia (COP; n = 10). The radiological scoring was performed based on high-resolution computed tomography (HRCT) findings.

Patients with IIP had higher serum M30 levels than did the control group (178.6 ± 91.5 vs. 113.7 ± 46.8 U/L, p < 0.05). Among IIP patients, COP patients had higher serum M30 levels than did UIP or NSIP patients (264.9 ± 132.7, 139.2 ± 49.7, and 201.2 ± 81.1 U/L, respectively; COP vs. UIP, p < 0.01). Serum M30 levels were negatively correlated with forced vital capacity (FVC; r(s) = -0.31), percent-predicted FVC (FVC%; r(s) = -0.38), and percent-predicted forced expiratory volume in 1 s (FEV(1)%; r(s) = -0.36). Serum M30 levels were correlated with radiological ground-glass opacity scores (r(s) = 0.61).

The epithelial apoptosis marker serum level was correlated with IIP clinical status and is a potential marker to assess IIP.