Correlation of increased serum leucine-rich α2-glycoprotein levels with disease prognosis, progression, and activity of interstitial pneumonia in patients with dermatomyositis: A retrospective study

OBJECTIVE: To investigate whether leucine-rich α2-glycoprotein (LRG) can be a biomarker for the disease activity, progression, and prognosis of interstitial pneumonia (IP) in patients with dermatomyositis (DM). METHODS: Correlations between the clinical findings and serum LRG levels were investigated in 46 patients with DM-IP (33 with acute/subacute IP [A/SIP] and 13 patients with chronic IP [CIP], including 10 fatal cases of IP). RESULTS: The median serum LRG level of 18.4 (14.6–25.2) μg/mL in DM-IP patients was higher than that in healthy control subjects. The median levels of serum LRG at baseline and at 2 and 4 weeks after the initiation of treatment in the patients who died were significantly higher than those in the surviving patients (P = 0.026, 0.029, and 0.008, respectively). The median level of serum LRG in the DM-A/SIP patients was significantly higher than that in the DM-CIP patients (P = 0.0004), and that in the anti-MDA5-Ab-positive group was slightly higher than that in the anti-ARS-Ab-positive group. The serum LRG levels correlated significantly with the serum levels of LDH, C-reactive protein, ferritin, AaDO(2), %DLco, and total ground-glass opacity score. The survival rate after 24 weeks in patients with an initial LRG level ≥ 17.6 μg/mL (survival rate: 40%) was significantly lower than that in patients with an initial LRG level < 17.6 μg/mL (100%) (P = 0.0009). CONCLUSION: The serum LRG level may be a promising marker of disease activity, progression, and prognosis in patients with DM-IP.