Abnormal deposition of collagen/elastic vascular fibres and prognostic significance in idiopathic interstitial pneumonias
- Edwin Roger Parra1,
- Ronaldo Adib Kairalla2,
- Carlos Roberto Ribeiro de Carvalho2,
- Vera Luiza Capelozzi1
- 1Department of Pathology, University of São Paulo Medical School, São Paulo, Brazil
- 2Pulmonary Division, University of São Paulo Medical School, São Paulo, Brazil
- Correspondence to:
V L Capelozzi
Department of Pathology, Sao Paulo Medical School, University of São Paulo, Dr Arnaldo Avenue 455, São Paulo 01246-903, Brazil;
- Received 20 March 2006
- Accepted 2 November 2006
- Published Online First 24 January 2007
Background: Vascular remodelling has recently been shown to be a promising pathogenetic indicator in idiopathic interstitial pneumonias (IIPs).
Aim: To validate the importance of the collagen/elastic system in vascular remodelling and to study the relationships between the collagen/elastic system, survival and the major histological patterns of IIPs.
Methods: Collagen/elastic system fibres were studied in 25 patients with acute interstitial pneumonia/diffuse alveolar damage, 22 with non-specific interstitial pneumonia/non-specific interstitial pneumonia and 55 with idiopathic pulmonary fibrosis/usual interstitial pneumonia. The Picrosirius polarisation method and Weigert’s resorcin–fuchsin histochemistry and morphometric analysis were used to evaluate the amount of vascular collagen/elastic system fibres and their association with the histological pattern of IIPs. The association between vascular remodelling and the degree of parenchymal fibrosis in usual interstitial pneumonia (UIP) was also considered.
Results: The vascular measurement of collagen/elastic fibres was significantly higher in UIP than in the lungs of controls, and in those with diffuse alveolar damage and those with non-specific interstitial pneumonia. In addition, the increment of collagen/elastic fibres in UIP varied according to the degree and activity of the parenchymal fibrosis. The most important predictors of survival in UIP were vascular remodelling classification and vascular collagen deposition.
Conclusion: A progressive vascular fibroelastosis occurs in IIP histological patterns, probably indicating evolutionarily adapted responses to parenchymal injury. The vascular remodelling classification and the increase in vascular collagen were related to survival in IIP and possibly play a role in its pathogenesis. Further studies are needed to determine whether this relationship is causal or consequential.
- AIP, acute interstitial pneumonia
- DAD, diffuse alveolar damage
- ECM, extracellular matrix
- FEV1, forced expiratory volume in 1 s
- FVC, forced vital capacity
- HRCT, high-resolution computed tomography
- IIP, idiopathic interstitial pneumonia
- IPF, idiopathic pulmonary fibrosis
- NSIP, non-specific interstitial pneumonia
- UIP, usual interstitial pneumonia
- VECM, vascular extracellular matrix
Funding: This study was supported by the following Brazilian agencies: the National Council for Scientific and Technological Development (CNPq); the Foundation for the Support of Research of the State of São Paulo (FAPESP 2001/14566-9); and the Laboratories for Medical Research (LIM 05) Clinicas Hospital, School of Medicine, University of São Paulo, São Paulo, Brazil.
Competing interests: None declared.