THU0409 Leucine-Rich Alpha2-Glycoprotein is A Useful Biomarker for Monitoring of Disease Activity in Patients with Adult-Onset Still's Disease

Abstract

Background Leucine-rich alpha2-glycoprotein (LRG) is a protein which contains leucine-rich repeats. Though physiologic functions of LRG have not been clearly defined, its expression was up-regulated during neutrophil differentiation and its levels were significantly elevated in some chronic inflammatory diseases such as inflammatory bowel disease. Objectives Our study aimed to investigate whether serum leucine-rich α2-glycoprotein (LRG) levels are elevated in patients with adult-onset Still's disease (AOSD) and determine their correlation with disease activity parameters. Methods We enrolled 39 patients with AOSD, 39 patients with rheumatoid arthritis (RA), and 39 controls. Forty-five serum samples from the patients with AOSD were assayed for LRG using enzyme-linked immunosorbent assay. Comprehensive AOSD activity was determined by modified Pouchot score. Results Serum LRG levels were significantly elevated in patients with AOSD (128.8±40.8 ng/mL) compared to those in patients with RA and in controls (35.9±15.7 ng/mL, p <0.001; 22.4±6.1 ng/mL, p <0.001, respectively). Patients with active AOSD had a significantly higher LRG level than those with inactive disease (141.4±31.3 ng/mL vs 79.8±37.1 ng/mL, p =0.002). Serum LRG levels were positively correlated with C-reactive protein (γ =0.387, p =0.015), lactate dehydrogenase (γ =0.370, p =0.026), and ferritin (γ =0.687, p <0.001) levels, and the modified Pouchot score (γ =0.756, p <0.001). Serum LRG levels decreased significantly after treatment in all 6 patients with active AOSD who had follow-up evaluations (p =0.007). The best cutoff value for LRG to distinguish AOSD from RA was 67.9 ng/mL, with a sensitivity of 92.3% and a specificity of 97.4%. Figure 1 Conclusions Serum LRG levels were increased in patients with AOSD and were well-correlated with disease activity measures. LRG may be a useful biomarker for distinguishing AOSD from RA and monitoring the disease activity of AOSD. References Takahashi N, Takahashi Y, Putnam FW. Periodicity of leucine and tandem repetition of a 24-amino acid segment in the primary structure of leucine-rich alpha 2-glycoprotein of human serum. Proc Natl Acad Sci U S A 1985;82:1906-10. Serada S, Fujimoto M, Terabe F, Iijima H, Shinzaki S, Matsuzaki S, et al. Serum leucine-rich alpha-2 glycoprotein is a disease activity biomarker in ulcerative colitis. Inflamm Bowel Dis 2012;18:2169-79. Disclosure of Interest : None declared DOI 10.1136/annrheumdis-2014-eular.2855

Leucine-rich α2-glycoprotein-1 upregulation in plasma and kidney of patients with lupus nephritis

“…In active LN, the inflammatory and autoimmune reactions were more serious. In previous study, serum LRG1 concentrations correlated with disease activity in SLE, rheumatoid arthritis, Crohn's disease, ulcerative colitis and adult-onset Still's disease [12,20,22,24,32].…”

“…The precise function of LRG1 remains unknown, but accumulating evidences showed that LRG1 is closely correlated with various types of cancers, such as lung, oral, ovarian, gastrict, pancreatic and biliary tract cancers [14][15][16][17][18]. Moreover, LRG1 is identified as an inflammatory protein in human serum and highly expressed in various kinds of benign inflammatory and autoimmune diseases, including suspected acute appendicitis of children [19], activated ulcerative colitis [12], rheumatoid arthritis [20,21], adultonset Still's disease [22] and asthma [23]. Especially, Ahn et al found serum LRG, namely LRG1, is elevated in patients with SLE and correlates with disease activity [24].…”

Leucine-rich α2-glycoprotein-1 upregulation in plasma and kidney of patients with lupus nephritis

“…Moreover, LRG1 is identified as an inflammatory protein in human serum and highly expressed in various kinds of benign inflammatory and autoimmune diseases, including suspected acute appendicitis of children [19], activated ulcerative colitis [12], rheumatoid arthritis [20,21], adultonset Still's disease [22] and asthma [23]. Especially, Ahn et al found serum LRG, namely LRG1, is elevated in patients with SLE and correlates with disease activity [24].…”

Leucine-rich α2-glycoprotein-1 upregulation in plasma and kidney of patients with lupus nephritis

“…In active LN, the inflammatory and autoimmune reactions were more serious. In previous study, serum LRG1 concentrations correlated with disease activity in rheumatoid arthritis, Crohn's disease, ulcerative colitis and adult-onset Still's disease [12,20,22,31].…”

“…Moreover, LRG1 is identified as an inflammatory protein in human serum and highly expressed in various kinds of benign inflammatory and autoimmune diseases, including suspected acute appendicitis of children [19], activated ulcerative colitis [12], rheumatoid arthritis [20,21], adultonset Still's disease [22] and asthma [23].…”