Serum progranulin levels are elevated in dermatomyositis patients with acute interstitial lung disease, predicting prognosis

INTRODUCTION: Progranulin (PGRN), a pleiotropic growth factor, has emerged as an immunoregulatory molecule. Because the roles of PGRN in dermatomyositis (DM) are still unknown, we investigated whether serum PGRN levels are associated with disease activity and prognosis in DM patients, particularly in those with DM complicated with interstitial lung disease (ILD). METHODS: The serum levels of PGRN were measured by enzyme-linked immunosorbent assay in patients with DM (n =57; acute/subacute interstitial pneumonia (A/SIP): n =17, chronic interstitial pneumonia (CIP): n =24, without ILD: n =16), polymyositis (PM, n =21; including 6 with ILD) and normal healthy controls (NHCs, n =60). We assessed the correlation between the serum PGRN levels and the activity indexes of ILD or prognosis in DM patients with ILD. RESULTS: Serum PGRN levels were significantly higher in DM patients than in PM patients (P =0.0025) and in NHCs (P <0.0001). In DM patients, the levels were significantly higher in patients with A/SIP than in those with CIP (P <0.0001) or without ILD (P =0.0003). The serum PGRN levels in DM patients with ILD significantly correlated with serum ferritin (r(S) =0.77, P <0.0001), lactate dehydrogenase (r(S) =0.54, P =0.0003) and C-reactive protein (r(S) =0.48, P =0.0015) levels. Moreover, in DM patients with ILD, the cumulative survival rate for 6 months was significantly lower in the group with serum PGRN levels ≥200 ng/ml (67%) than in the group with serum PGRN levels <200 ng/ml (100%) (P =0.0009). CONCLUSIONS: Serum PGRN is associated with disease activity and prognosis of DM with ILD. PGRN may play a role in the pathogenesis of DM and could be a useful biomarker.