Objectives: To investigate the associations between serum levels of matrix metalloproteinase 7 (MMP7), surfactant protein D (SPD), interleukin 18 (IL-18) and chemokine ligand 18 (CCL18) with dermatomyositis and polymyositis-associated interstitial lung disease (DM/PM-ILD) and evaluate their prognostic values in the disease.
Methods: Seventy-eight patients with multiple disciplinary team diagnosis of DM/PM-ILD were enrolled and classified as anti-melanoma differentiation-associated protein 5 antibody (MDA5)-ILD, anti-synthetase antibodies (ARS)-ILD and other antibodies-ILD upon autoantibodies profiles. Clinical data were collected and serum levels of four biomarkers were analysed. The primary endpoint was 3-month mortality. The cut-off values of biomarkers for mortality were figured out by receiver operating characteristic (ROC) analysis. Cox regression was performed to evaluate predictive values.
Results: Serum levels of MMP7 (p=0.036), SPD (p<0.001), IL-18 (p<0.001) and CCL18 (p<0.001) in patients with DM/PM-ILD were significantly higher than healthy controls with levels of MMP7 (p=0.029) and SPD (p=0.029) in patients with MDA5-ILD significantly lower than patients with ARS-ILD. The 3-month mortality in MDA5-ILD was 54.5% (12/22). Multivariate analysis showed that age (p=0.001, HR 1.151, 95% CI 1.063-1.247) and an increased level of SPD (>75.90ng/ml, p=0.005, HR 16.411, 95% CI 2.369-113.711) were significant predictors for 3-month mortality in patients with MDA5-ILD.
Conclusions: Elevated serum biomarkers were associated with DM/PM-ILD with differential levels between MDA5-ILD and ARS-ILD. Age and an increased SPD had prognostic values for predicting short-term mortality in patients with MDA5-ILD. Our study was important in providing a clue for understanding the classification and prognosis of DM/PM-ILD.