Background Interstitial collagen types III is highly resistant to proteolytic attack, due to their triple helical structure. However, it can be cleaved by matrix metalloproteinase (MMP)-9 at a specific site, resulting in the generation of specific cleavage fragments . Disturbed balance of collagen metabolism is a hallmark of interstitial lung disease (ILD) .
Objectives Our study investigated whether matrix metalloproteinases-9-cleaved fragment of type III collagen (C3M)  and the amino-terminal propeptide of procollagen type III (PIIINP)  may be used as novel markers for ILD in polymyositis (PM) and dermatomyositis (DM).
Methods Serum concentrations of C3M and PIIINP were determined by enzyme-1inked immunosorbent assay in 46 adult PM/DM patients (31 with ILD, 15 without ILD) and 19 healthy controls. The correlations between serum C3M and PIIINP levels and clinical features or laboratory examinations of PM/DM patients were investigated.
Results The serum levels of C3M were 7.16±3.77ng/ml in PM/DM with ILD group, 4.56±0.84ng/ml in PM/DM without ILD group, and 4.63±0.85ng/ml, in healthy controls, respectively. Serum C3M level in ILD group was significantly higher than without ILD group and healthy controls (both P <0.01). Positive C3M was significantly associated with ILD in PM/DM (P<0.01). The sensitivity and specificity of positive C3M for ILD in PM/DM were 71.0% and 82.4%, respectively. The serum levels of PIIINP were 12.39±12.17ng/ml in PM/DM with ILD group, 9.57±5.67ng/ml in PM/DM without ILD group, and 8.28±4.95ng/ml, in healthy controls, respectively. Serum PIIINP level in ILD group was higher than in without ILD group and healthy controls but with no statistical significance (both P >0.05).
Conclusions C3M may be potential and useful serum marker for the diagnosis of ILD in PM/DM patients. Further investigation is needed to assess the role of PIIINP in these diseases.
Bigg HF, Rowan AD, Barker MD, Cawston TE: Activity of matrix metalloproteinase-9 against native collagen types I and III. FEBS J 2007, 274:1246-1255.
Dancer RC, Wood AM, Thickett DR: Metalloproteinases in idiopathic pulmonary fibrosis. Eur Respir J 2011, 38:1461-1467.
Segovia-Silvestre T, Reichenbach V, Fernandez-Varo G, Vassiliadis E, Barascuk N, Morales-Ruiz M, Karsdal MA, Jimenez W: Circulating CO3-610, a degradation product of collagen III, closely reflects liver collagen and portal pressure in rats with fibrosis. Fibrogenesis Tissue Repair 2011, 4:19.
Jensen LT: The aminoterminal propeptide of type III procollagen. Studies on physiology and pathophysiology. Dan Med Bull 1997, 44:70-78.
Disclosure of Interest None declared