An association between lavage fibronectin and type 3 procollagen peptide was also noted by Begin et al in patients with asbestosis. Fibronectin, which is produced by the alveolar macrophage, can act as a chemoattractant and competence factor for fibroblasts, drawing them to the site of tissue injury and priming them for proliferation. It is suggested that the combined action of fibronectin and other fibroblast growth factors produced by the alveolar macrophage may play a role in the development of fibrosis in sarcoidosis. Cantin et al observed an association between lavage type 3 procollagen peptide and the ability of lavage fluids to stimulate fibroblast proliferation in patients with idiopathic pulmonary fibrosis. mycanadianfamilypharmacy.net
In light of these observations, the association between fibronectin and type 3 procollagen peptide levels noted in the present study might be interpreted as reflecting promising conditions for the development of fibrosis in patients with elevated type 3 procollagen peptide levels. In this regard, Bjermer et al reported an inverse correlation between pulmonary function and lavage type 3 procollagen peptide levels and suggested that elevated lavage type 3 procollagen peptide levels may reflect increased fibrotic activity associated with interstitial fibrosis. However, we found no association between lavage type 3 procollagen levels and physiologic evidence of lung impairment as assessed by pulmonary function tests. Other groups of workers have also failed to demonstrate a relationship between lavage type 3 procollagen peptide levels and pulmonary function. Thus, if elevated lavage type 3 procollagen peptide levels reflect fibrotic activity in the lung, it would appear that the severity of fibrosis is not sufficient to cause functional impairment in many patients. Follow-up monitoring of patients indicated that those with high lavage type 3 procollagen peptide levels were no more likely to deteriorate than those with low type 3 procollagen peptide levels.