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 [1]. Disturbed balance of collagen metabolism is a hallmark of interstitial lung disease (ILD) [2].

Objectives: Our study investigated whether matrix metalloproteinases-9-cleaved fragment of type III collagen (C3M) [3] and the amino-terminal propeptide of procollagen type III (PIIINP) [4] 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.

Disclosure of Interest: None declared

DOI: 10.1136/annrheumdis-2014-eular.1929