Cincinnati Children's Hospital Medical Center, OH 45229-3039, USA.
Am J Physiol Gastrointest Liver Physiol. 2011 Oct;301(4):G612-22. doi: 10.1152/ajpgi.00531.2010. Epub 2011 Jul 28.
Alanyl-glutamine (Ala-Gln) has recently been shown to enhance catch-up growth and gut integrity in undernourished children from Northeast Brazil. We hypothesized that the intestinal epithelial effects of Ala-Gln in malnourished weanling mice and mouse small intestinal epithelial (MSIE) cells would include modulation of barrier function, proliferation, and apoptosis. Dams of 10-day-old suckling C57BL/6 pups were randomized to a standard diet or an isocaloric Northeast Brazil "regional basic diet," moderately deficient in protein, fat, and minerals. Upon weaning to their dam's diet on day of life 21, pups were randomized to Ala-Gln solution or water. At 6 wk of age, mice were killed, and jejunal tissue was collected for morphology, immunohistochemistry, and Ussing chamber analysis of transmucosal resistance and permeability. Proliferation of MSIE cells in the presence or absence of Ala-Gln was measured by MTS and bromodeoxyuridine assays. MSIE apoptosis was assessed by annexin and 7-amino-actinomycin D staining. Pups of regional basic diet-fed dams exhibited failure to thrive. Jejunal specimens from undernourished weanlings showed decreased villous height and crypt depth, decreased transmucosal resistance, increased permeability to FITC-dextran, increased claudin-3 expression, and decreased epithelial proliferation and increased epithelial apoptosis (as measured by bromodeoxyuridine and cleaved caspase-3 staining, respectively). Undernourished weanlings supplemented with Ala-Gln showed improvements in weight velocity, villous height, crypt depth, transmucosal resistance, and epithelial proliferation/apoptosis compared with unsupplemented controls. Similarly, Ala-Gln increased proliferation and reduced apoptosis in MSIE cells. In summary, Ala-Gln promotes intestinal epithelial homeostasis in a mouse model of malnutrition-associated enteropathy, mimicking key features of the human disease.
丙氨酰-谷氨酰胺（Ala-Gln）最近被证明可以促进巴西东北部营养不良儿童的追赶性生长和肠道完整性。我们假设丙氨酰-谷氨酰胺对营养不良的断奶小鼠和小鼠小肠上皮（MSIE）细胞的肠上皮作用将包括调节屏障功能、增殖和凋亡。10 天大的哺乳 C57BL/6 幼鼠的母鼠被随机分配到标准饮食或能量相同的巴西东北部“区域基础饮食”，该饮食在蛋白质、脂肪和矿物质方面都存在中度缺乏。在出生后第 21 天，幼鼠断奶并随机分配到丙氨酰-谷氨酰胺溶液或水。在 6 周龄时，处死小鼠，收集空肠组织进行形态学、免疫组织化学和 Ussing 室分析，以评估跨黏膜阻力和通透性。通过 MTS 和溴脱氧尿苷测定来测量 MSIE 细胞在存在或不存在丙氨酰-谷氨酰胺时的增殖。通过 Annexin 和 7-氨基放线菌素 D 染色评估 MSIE 细胞凋亡。区域基础饮食喂养的母鼠所产的幼鼠生长不良。营养不良的断奶幼鼠空肠标本显示绒毛高度和隐窝深度降低、跨黏膜阻力降低、FITC-右旋糖酐通透性增加、claudin-3 表达增加、上皮细胞增殖减少和上皮细胞凋亡增加（分别通过溴脱氧尿苷和 cleaved caspase-3 染色测量）。与未补充对照组相比，补充丙氨酰-谷氨酰胺的断奶幼鼠体重增长率、绒毛高度、隐窝深度、跨黏膜阻力和上皮细胞增殖/凋亡均有所改善。同样，丙氨酰-谷氨酰胺增加了 MSIE 细胞的增殖并减少了凋亡。总之，丙氨酰-谷氨酰胺促进了营养不良相关肠病小鼠模型中的肠上皮稳态，模拟了人类疾病的关键特征。
