Fibrinogen-like protein 2 prothrombinase may contribute to the progression of inflammatory bowel disease by mediating immune coagulation.

Inflammation and coagulation are interdependent processes that enable each process to activate and propagate the other in inflammatory bowel disease (IBD). Thus, we investigated the role of a novel immune coagulant, fibrinogen-like protein 2 prothrombinase (FGL2), in patients and mice with IBD. 83 IBD patients and 40 normal controls were enrolled, and trinitro-benzene-sulfonic acid (TNBS)-induced colitis mice were used. Expression of FGL2 in the intestine was detected by immunohistochemistry. Using serial sections, staining was performed to detect tumor necrosis factor α (TNF-α) expression, and to demonstrate co-localization of FGL2 with macrophages and fibrin. Correlations between FGL2 expression with some common laboratory parameters were examined. FGL2 was seen primarily in inflammatory infiltrating cells, mainly macrophages, and microvascular vessels and had a strong co-localization with fibrin deposition. IBD patients and mice had increased expression of FGL2 compared with controls. Furthermore, FGL2 expression was correlated with intestinal and plasmatic TNF-α expression, mean platelet volume (MPV), platelet count (PLT), platelet-crit (PCT), and fibrinogen. Our data indicate that FGL2 may mediate immune coagulation in IBD patients. It may be considered as a novel molecule that contributes to the onset and development of IBD.