Active synthesis of collagen (I) homotrimer and matrisomal proteins in Dupuytren’s fibrosis

Dupuytren’s disease is a common fibroproliferative disease of the palmar fascia of the hand with severe cases treated surgically. The rate of disease recurrence following treatment is high and a continual production of matrisomal proteins could lead to disease recurrence. There is no animal model for Dupuytren’s disease, but analysis of the surgically excised tissue provides an accessible means to study the mechanisms of human tissue fibrosis. Here we sought to determine how new synthesis and the composition of matrisomal proteins in Dupuytren’s differs from normal palmar fascia samples, using metabolic labelling approaches and proteomics. Model non-fibrotic, but fibrous connective tissues, equine flexor tendon and canine cranial cruciate ligament, were used to analyse active collagen-1 protein synthesis in development, ageing and degenerative disease, where it was restricted to early development and ruptured tissue. Dupuytren’s tissue was shown to actively synthesise type I collagen, a proportion of which comprised abnormal collagen (I) homotrimer (mean 14.3% ± 14.4), as well as fibronectin, matrix metalloproteinases (MMP2, MMP3) and their inhibitors; Tissue Inhibitor of Metalloproteinases 2 (TIMP2). Insulin-Like Growth Factor Binding Protein 7 (IGFBP7) was actively synthesised by Dupuytren’s as well as control tissue. Label-free analysis implicated the TGFβ pathway in the matrisomal profile of Dupuytren’s tissue whilst myocilin, a Wnt-pathway regulator, was noticeably more abundant in control samples. No collagen (I) neopeptides representing the major collagenase cleavage site were identified, however periostin neopeptides were abundant in Dupuytren’s tissue and gelatin neopeptides in both tissue types. Synthesis of MMP-resistant collagen-1 homotrimer, together with altered TGFβ and Wnt signalling environments, could contribute to the persistence of the fibrotic tissue and disease recurrence following treatment.