Serum anti-proteinase 3 antineutrophil cytoplasmic antibody (PR3-ANCA) is a disease-specific antibody against granulomatosis with polyangiitis. PR3-ANCA is a useful serological marker for disease severity in ulcerative colitis (UC). The purpose of this study was to investigate whether PR3-ANCA levels could also predict the success of induction therapy and to compare its performance against other markers, including serum CRP and fecal hemoglobin. This was a multicenter retrospective study. In total, 159 patients with active-phase UC underwent colonoscopy. Disease activity was measured using the Mayo endoscopic subscore (MES). PR3-ANCA positivity and the response to induction therapy, either 5-aminosalicylic acid or steroid, were assessed. PR3-ANCA, CRP, and fecal hemoglobin were measured during the active phase, and during clinical remission. Eighty-five (53.5%) of 159 patients with active UC were positive for PR3-ANCA. PR3-ANCA titers were significantly higher in the group of patients with MES 3 compared to patients with MES 1 (P = 0.002) or MES 2 (P = 0.035). Steroid therapy was administered to 56 patients with a median partial Mayo score of 7 (5–9), which is equivalent to moderate-to-severe disease activity. PR3-ANCA positivity of non-responders to steroid therapy was significantly higher than that of responders (71.9% vs, 41.7%, P = 0.030), whereas CRP and fecal hemoglobin were not predictive of steroid response. Multivariate analysis demonstrated that PR3-ANCA positivity was associated with non-response to steroid therapy (odds ratio 5.19; 95% confidence interval, 1.54–17.5; P = 0.008). Of the 37 patients treated to clinical remission who were also positive for PR3-ANCA during the active phase, 27 had an MES of ≥ 1, and 10 patients had an MES of 0. In clinical remission, the proportion of patients with MES 0 in 17 patients whose PR3-ANCA became negative was significantly higher than that in 20 patients whose PR3-ANCA remained positive (47.1% vs. 10.0%, P = 0.023). PR3-ANCA not only serves as a marker of disease activity, but also predicts the failure of steroid therapy in moderate-to-severe UC. Trial registration: This study was retrospectively registered in the UMIN Clinical Trials Registry System (000039174) on January 16, 2020.

中文翻译：

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抗蛋白酶 3 抗中性粒细胞胞质抗体反映疾病活动性并预测溃疡性结肠炎中类固醇治疗的反应

血清抗蛋白酶 3 抗中性粒细胞胞浆抗体 (PR3-ANCA) 是一种针对肉芽肿性多血管炎的疾病特异性抗体。PR3-ANCA 是溃疡性结肠炎 (UC) 疾病严重程度的有用血清学标志物。本研究的目的是调查 PR3-ANCA 水平是否也可以预测诱导治疗的成功，并将其性能与其他标志物（包括血清 CRP 和粪便血红蛋白）进行比较。这是一项多中心回顾性研究。总共有 159 名活动期 UC 患者接受了结肠镜检查。使用梅奥内窥镜评分 (MES) 测量疾病活动度。评估了 PR3-ANCA 阳性和对 5-氨基水杨酸或类固醇诱导治疗的反应。在活动期和临床缓解期测量 PR3-ANCA、CRP 和粪便血红蛋白。159 名活动性 UC 患者中有 85 名 (53.5%) PR3-ANCA 呈阳性。与 MES 1 (P = 0.002) 或 MES 2 (P = 0.035) 患者相比，MES 3 组的 PR3-ANCA 滴度显着更高。对 56 名患者进行了类固醇治疗，梅奥部分评分中位数为 7 (5-9)，相当于中度至重度疾病活动度。对类固醇治疗无应答者的 PR3-ANCA 阳性显着高于应答者（71.9% 对 41.7%，P = 0.030），而 CRP 和粪便血红蛋白不能预测类固醇反应。多变量分析表明 PR3-ANCA 阳性与类固醇治疗无反应相关（优势比 5.19；95% 置信区间，1.54-17.5；P = 0.008）。在治疗达到临床缓解且在活动期 PR3-ANCA 也呈阳性的 37 名患者中，27 名患者的 MES ≥ 1，10 名患者的 MES 为 0。在临床缓解中，MES 0 患者的比例为PR3-ANCA 转阴的 17 名患者明显高于 PR3-ANCA 保持阳性的 20 名患者（47.1% vs. 10.0%，P = 0.023）。PR3-ANCA 不仅可以作为疾病活动的标志物，而且可以预测中重度 UC 中类固醇治疗的失败。试验注册：本研究于2020年1月16日在UMIN临床试验注册系统（000039174）进行回顾性注册。PR3-ANCA转阴的17例患者中MES 0的比例明显高于PR3-ANCA保持阳性的20例（47.1% vs. 10.0%，P=0.023）。PR3-ANCA 不仅可以作为疾病活动的标志物，而且可以预测中重度 UC 中类固醇治疗的失败。试验注册：本研究于2020年1月16日在UMIN临床试验注册系统（000039174）进行回顾性注册。PR3-ANCA转阴的17例患者中MES 0的比例明显高于PR3-ANCA保持阳性的20例（47.1% vs. 10.0%，P=0.023）。PR3-ANCA 不仅可以作为疾病活动的标志物，而且可以预测中重度 UC 中类固醇治疗的失败。试验注册：本研究于2020年1月16日在UMIN临床试验注册系统（000039174）进行回顾性注册。