Clinical significance of Anti-neutrophil Cytoplasmic Antibodies to Proteinase-3 (PR3-ANCA) in Patients With Ulcerative Colitis

Abstract

BACKGROUND: Recently, many reports have been made on diagnostic value of anti-neutrophil cytoplasmic antibodies (ANCA) in patients with ulcerative colitis (UC). However, clinical significance of PR3-ANCA for UC is not well understood yet. We aim to analyze the clinical significance of PR3-ANCA in patients with UC. METHODS: 74 patients with UC evaluated to proteinase-3-ANCA (PR3-ANCA) and myeloperoxidase-ANCA (MPO-ANCA) from July 2013 to July 2017 in our hospital were analyzed. Clinical remission was defined as less than 5 points of Lichtiger index, and endoscopic mucosal healing (MH) was defined as Mayo endoscopic score 0 or 1, respectively. We evaluated the ratio of positive for PR3- and MPO-ANCA in UC patients, and also evaluated the differences of clinical features between ANCA-positive and ANCA-negative groups. RESULTS: Out of 74 UC-patients, 46 (62.1%) and 8 (10.8%) were positive for PR3-ANCA and MPO-ANCA, respectively. All cases positive for MPO-ANCA were also positive for PR3-ANCA. The ratio of patients with extensive colitis in the PR3-ANCA-positive group was significantly higher than that in the PR3-ANCA-negative group (71.7% and 46.6%, respectively; P=0.03). Moreover, the disease activity and MH rate of PR3-ANCA positive group was significantly higher and lower than those of PR3-ANCA negative group, respectively (disease activity: P=0.015, and MH rate: P<0.01). On the other hand, there was no significant difference in clinical characteristics, such as gender, age, serum level of C-reactive protein (CRP) and albumin levels, between the PR3-ANCA-positive and PR3-ANCA-negative group. However, regression analysis demonstrated that the titer of PR3-ANCA was significantly related with the serum level of albumin (r=0.396, P<0.01) and C-reactive protein (r=0.156, P<0.01), although there was no relationship between the titer of PR3-ANCA and Lichtiger index. In the sequent clinical course, the ratio of UC-patients requiring infliximab in the PR3-ANCA-positive group was also higher than that in the PR3-ANCA-negative group (17.4% and 0%, respectively; P=0.013). On the other hand, there was no significant difference in the ratio of UC-patients requiring surgery between the PR3-ANCA-positive and the PR3-ANCA-negative group (12.2% vs 0%, respectively; P>0.05). CONCLUSION(S): PR3-ANCA may be the prognostic factor for refractory UC requiring intensive therapies, because there is less rate of MH in the group of PR3-ANCA positive, apparently.