Department of Pathology and Laboratory Medicine.
Department of Medicine Section of Gastroenterology, Hepatology and Nutrition and the Ertan Digestive Diseases Center of Excellence, The University of Texas Health Science Center at Houston McGovern Medical School, and Memorial-Hermann Hospital-TMC, Houston, TX, USA.
Ann Clin Lab Sci. 2020 Jul;50(4):447-449.
Aquaporin-5 (AQP5) is a member of a family of water channel proteins involved in the bidirectional transfer of water across cell membranes. Lymphocytic colitis (LC) and collagenous colitis (CC) are clinically similar diseases characterized by chronic watery diarrhea in patients with usually unremarkable colonic mucosa on colonoscopy. The aim of this study was to determine whether AQP5 expression in colonic epithelium is altered in LC and CC.
Sections of formalin-fixed and paraffin-embedded colorectal biopsies from three control patients (CTL), 8 patients with chronic non-bloody diarrhea with biopsies negative for active inflammation or significant distortion (CTL-D), 8 patients with LC, and 5 with CC were stained for AQP5 using immunohistochemistry. The staining intensity was scored as 3 (strong), 2 (intermediate), 1 (weak), or 0 (no staining). Statistical analysis was performed using Prism 7 Statistical Soft-ware.
AQP5 was strongly expressed (score 3) in the epithelial cells in all three CTL cases and all 8 CTL-D cases. In the 5 cases of CC, 3(60%) had score 3 and 2(40%) had score 2, but none had a score of 1 or 0. Of the 8 LC cases, 2(25%) had score 3, 3 had score 2(37.5%), and 3 had score 1(37.5%) (=0.0031). In the three cases of LC with markedly reduced AQP5 (score 1), enteric steroid treatment did not lead to significant improvement in diarrhea.
Colorectal AQP5 expression is reduced in most cases of LC. Markedly reduced AQP5 expression in LC may identify a subset of patients with suboptimal response to enteric steroid treatment. Additional larger studies are needed to confirm these findings.This abstract was presented in part at Digestive Diseases Week in San Diego, CA, May 2019.
水通道蛋白-5（AQP5）是一组参与跨细胞膜双向水转运的水通道蛋白家族的成员。淋巴细胞性结肠炎（LC）和胶原性结肠炎（CC）是两种临床上相似的疾病，其特征是患者慢性水样腹泻，结肠镜检查结肠黏膜通常无明显异常。本研究旨在确定在 LC 和 CC 中结肠上皮的 AQP5 表达是否改变。
使用免疫组织化学法对来自 3 例对照患者（CTL）、8 例慢性非血性腹泻且活检无活动性炎症或明显变形的患者（CTL-D）、8 例 LC 患者和 5 例 CC 患者的福尔马林固定和石蜡包埋的结直肠活检组织进行 AQP5 染色。染色强度评分为 3（强）、2（中等）、1（弱）或 0（无染色）。使用 Prism 7 统计软件进行统计分析。
在所有 3 例 CTL 病例和所有 8 例 CTL-D 病例中，AQP5 在所有上皮细胞中均强烈表达（评分 3）。在 5 例 CC 病例中，3 例（60%）评分 3，2 例（40%）评分 2，但均无评分 1 或 0。在 8 例 LC 病例中，2 例（25%）评分 3，3 例（37.5%）评分 2，3 例（37.5%）评分 1（=0.0031）。在 3 例 LC 病例中，AQP5 表达明显减少（评分 1），肠内类固醇治疗并未导致腹泻显著改善。
大多数 LC 病例的结肠 AQP5 表达减少。LC 中 AQP5 表达明显减少可能会识别出对肠内类固醇治疗反应不佳的亚组患者。需要更大规模的研究来证实这些发现。本摘要部分在加利福尼亚州圣地亚哥举行的消化疾病周上发表。
