Background: Recently, vascular remodelling has shown to be promising as pathogenetic indicator in Idiopathic Interstitial Pneumonias (IIPs). In this study, we sought to validate the importance of the collagen/elastic system in the vascular remodelling and to study the relationships between collagen/elastic system, survival and the major histological pattern of IIPs.
Methods: We examined collagen/elastic system fibres in 25 acute interstitial pneumonia/diffuse alveolar damage, 22 non-specific interstitial pneumonia/non-specific interstitial pneumonia and 55 idiopathic pulmonary fibrosis/usual interstitial pneumonia cases. We used the Picrosirius-polarization method and Weigert's resorcin-fuchsin histochemistry and morphometric analysis to evaluate the amount of vascular collagen/elastic system fibres, and their association with IIPs histological pattern. In usual interstitial pneumonia (UIP) we also considered the association between vascular remodelling and parenchymal fibrosis degree.
Results: The vascular measurement of collagen/elastic fibres content was significantly higher in UIP than lungs of control, diffuse alveolar damage and non-specific interstitial pneumonia. In addition, the increment of collagen/elastic fibres in UIP varied according to the parenchymal fibrosis degree and activity. The most important predictors of survival in UIP were vascular remodelling classification (p=0.0004) and vascular collagen deposition (p=0.005).
Conclusion: We concluded that a progressive vascular fibroelastosis occurs in IIP histological patterns, probably indicating evolutionary adapted responses to parenchymal injury. The vascular remodeling classification and the increased of the vascular collagen were related with survival in the idiopathic interstitial pneumonia and possibly play a role in its pathogenesis. Further studies are needed to determine whether this relationship is causal or consequential.
- Idiopathic interstitial pneumonias
- collagen/elastic system fibres
- vascular remodelling