The difference of neovascularization in early intra‐alveolar fibrosis between nonspecific interstitial pneumonia and usual interstitial pneumonia

Abstract

Of the idiopathic interstitial pneumonias (IIPs), usual interstitial pneumonia (UIP) and diffuse alveolar damage (DAD) usually have poor prognoses. The prognoses of cryptogenic organizing pneumonia (COP) and nonspecific interstitial pneumonia (NSIP) are usually more favorable. Although several reports have described neovascularization in COP and UIP, this aspect of UIP has not been compared with NSIP. In this study, we evaluated neovascularization in intra-alveolar fibrotic lesion of cases of fibrosing NSIP (f-NSIP) (n = 26) and UIP (n = 25). In the f-NSIP group, a considerable degree of neovascularization was observed compared to the UIP group and bud type intra-alveolar fibrosis showed a greater degree of neovascularization compared to the mural-incorporation and obliterative types of intra-alveolar fibrosis. Real-time reverse transcription polymerase chain reaction revealed a significantly greater expression of VEGF-A mRNA in f-NSIP than in UIP. The expression of matrix metalloproteinase-2 (MMP-2) mRNA also showed significantly higher in f-NSIP than UIP. The greater VEGF-A and MMP-2 expression may play a role in the pathogenesis of neovascularization in early intra-alveolar fibrotic lesions in f-NSIP.