Intestinal and Peripheral Fibrinogen-Like Protein 2 Expression in Inflammatory Bowel Disease

Fibrinogen-like protein 2 (FGL2), a new member of the fibrinogen-like family, has recently been identified as a novel immunosuppressive molecule. The purpose of this work was to investigate intestinal and peripheral expression of FGL2 in patients with inflammatory bowel disease (IBD), mainly ulcerative colitis (UC) and Crohn's disease (CD). FGL2 expression in mucosal biopsies from three groups (UC group (n = 61), CD group (n = 54), and controls group (n = 35)) was detected by immunohistochemistry. Concentrations of FGL2 in plasma from 50 UC patients, 45 CD patients, and 30 controls were analyzed by enzyme-linked immunosorbent assay. Western blot of FGL2 protein and real-time fluorescent quantitative PCR of FGL2 mRNA expression by peripheral mononuclear cells was performed. Correlations of FGL2 expression with disease type, activity, and location, and with measured laboratory data, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), were examined. Intestinal and peripheral FGL2 protein data showed that FGL2 expression was significantly up-regulated in both UC and CD patients compared with controls (P < 0.001). Expression of FGL2 was higher in UC and CD patients with active disease than in those with inactive disease (P < 0.001). Moreover, FGL2 mRNA expression was significantly higher in patients with active disease than in those with inactive disease (P < 0.050). Expression of FGL2 protein was correlated with disease activity indices, CRP levels, and ESR levels. Expression of FGL2 was up-regulated in IBD patients with active disease. Measurement of FGL2 may be used as a helpful biomarker for understanding immunopathogenesis and for assessment of IBD.