Proteomic analysis in usual and nonspecific interstitial pneumonia

Differentiating nonspecific interstitial pneumonia (NSIP) from usual interstitial pneumonia (UIP) is important for the determination of both treatment and prognosis. Using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), we examined 8 UIPs, 8 NSIPs, and 30 normal lung tissues. Comparisons with control in 2D-DIGE showed that (a) in UIP, nine protein spots were significantly upregulated and seven were significantly downregulated, (b) in NSIP, four protein spots were significantly upregulated and nine were significantly downregulated. The detected proteins were analyzed by MALDI-TOF mass spectrometry, allowing qualitative differences in vimentin subtypes to be characterized. One vimentin subtype was upregulated in UIP, while another one was downregulated in NSIP (vs. control). These different characteristics were partially supported by the results of Western blot analysis. Our immunohistochemistry revealed vimentin expression within fibroblasts (a) in fibroblastic foci in UIP and (b) in fibrotic alveolar walls in NSIP. Differences in vimentin subtypes may provide useful biomarkers for separating NSIP from UIP, alongside differences in histological characteristics.