Type I and III procollagen propeptides in sarcoidosis, fibrosing alveolitis and asbestos-related lung diseases
1University of Oulu, Faculty of Medicine, Department of Internal Medicine
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|Persistent link:|| http://urn.fi/urn:isbn:9514253728
|Publish Date:|| 1999-09-06
|Thesis type:||Doctoral Dissertation
|Defence Note:||Academic Dissertation to be presented with the assent of the Faculty of Medicine, University of Oulu, for public discussion in Auditorium 10 of the University Hospital of Oulu, on October 22nd, 1999, at 12 noon.
Docent Pekka Klemi
Docent Onni Niemelä
The most threatening outcome of interstitial lung diseases is death caused by progressive pulmonary fibrosis characterised by increased collagen deposition, although the clinical course is highly variable. The aim of this study was to evaluate the role of procollagen I and III propeptides in estimating collagen metabolism and its relationship to disease activity and prognosis in patients with sarcoidosis, fibrosing alveolitis and asbestos-related lung diseases.
The study included 160 patients. The levels of procollagen I carboxyterminal propeptide (PICP) and procollagen III aminoterminal propeptide (PIIINP) in serum, bronchoalveolar lavage fluid (BALF) and epithelial lining fluid (ELF) were assessed from 137 patients employing human antigens. There were 60 patients with sarcoidosis, 18 with fibrosing alveolitis and 5 with asbestosis and 17 controls. Thirty-seven patients had been exposed to asbestos, but did not show parenchymal involvement. Twenty-five of them had pleural plaques, while 12 had normal chest radiographs. Immunohistochemical stainings for procollagen I aminoterminal (PINP) and III aminoterminal propeptide were carried out on open lung biopsies of the remaining 23 of the 160 patients, of whom 13 had sarcoidosis and 10 fibrosing alveolitis. Antibodies to these procollagen peptides react with the aminoterminal domains of the corresponding propeptides intracellularly and with the respective pN-collagen in collagen fibres in the extracellular space.
Procollagen III aminoterminal propeptide was elevated in the sera of the patients with sarcoidosis and fibrosing alveolitis, but not in the asbestosis or asbestos-exposed patients as compared to the controls. The level of PIIINP in BALF was highest in sarcoidosis and second highest in fibrosing alveolitis, but hardly detectable in the other groups. BALF-PICP was higher in the patients with fibrosing alveolitis, sarcoidosis and asbestosis than in the controls. PIIINP in BALF correlated with BALF-PICP, serum angiotensin-converting enzyme (S-ACE), interleukin 2-receptor, BALF-albumin and BALF-lymphocytes and BALF-PICP had a significant correlation with BALF-albumin and BALF-lymphocytes in sarcoidosis. BALF/ELF-PICP had an inverse correlation with the specific diffusion coefficient (DLCO/VA) in fibrosing alveolitis. Both PIIINP and PICP were higher in ELF than in serum in sarcoidosis and fibrosing alveolitis and PICP was higher in ELF compared to serum in asbestosis, suggesting active local synthesis in the lower respiratory tract. The levels of PIIINP in BALF were significantly elevated in sarcoidosis patients with parenchymal involvement compared to those without. Detectable PIIINP in BALF also predicted a poor outcome in fibrosing alveolitis. BALF-PIIINP reflected the disease activity based on chest radiographs in sarcoidosis and a poor prognosis in fibrosing alveolitis, whereas BALF-PICP marked the development of fibrosis.
In lung biopsy specimens, type I and III pN-collagens were increased in fibrosing alveolitis and sarcoidosis. Type I pN-collagen was expressed in areas with damaged or deficient alveolar epithelium. Type III pN-collagen was present underneath regenerative, metaplastic alveolar and bronchiolar type epithelium and was accumulated both in the loose, newly formed fibrosis and in the denser old fibrosis. Type I procollagen was present in intracellular spots in newly formed fibrosis. In sarcoidosis, type I procollagen was present intracellularly in granulomas, whereas type III pN-collagen was expressed extracellularly around granulomas.
Acta Universitatis Ouluensis. D, Medica
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