NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
J Pathol. 2011 Oct;225(2):276-84. doi: 10.1002/path.2917. Epub 2011 Jun 1.
The intestinal microbiota is increasingly acknowledged to play a crucial role in the development of obesity. A shift in intestinal microbiota composition favouring the presence of Firmicutes over Bacteroidetes has been observed in obese subjects. A similar shift has been reported in mice with deficiency of active Paneth cell α-defensins. We aimed at investigating changes in Paneth cell antimicrobial levels in the gut of obese subjects. Next, we studied activation of the unfolded protein response (UPR) as a possible mechanism involved in altered Paneth cell function. Paneth cell numbers were counted in jejunal sections of 15 severely obese (BMI > 35) and 15 normal weight subjects. Expression of Paneth cell antimicrobials human α-defensin 5 (HD5) and lysozyme were investigated using immunohistochemistry, qPCR, and western blot. Activation of the UPR was assessed with western blot. Severely obese subjects showed decreased protein levels of both HD5 and lysozyme, while Paneth cell numbers were unchanged. Lysozyme protein levels correlated inversely with BMI. Increased expression of HD5 (DEFA5) and lysozyme (LYZ) transcripts in the intestine of obese subjects prompted us to investigate a possible translational block caused by UPR activation. Binding protein (BiP) and activating transcription factor 4 (ATF4) levels were increased, confirming activation of the UPR in the gut of obese subjects. Furthermore, levels of both proteins correlated with BMI. Involvement of the UPR in the lowered antimicrobial protein levels in obese subjects was strongly suggested by a negative correlation between BiP levels and lysozyme levels. Additionally, indications of ER stress were apparent in Paneth cells of obese subjects. Our findings provide the first evidence for altered Paneth cell function in obesity, which may have important implications for the obesity-associated shift in microbiota composition. In addition, we show activation of the UPR in the intestine of obese subjects, which may underlie the observed Paneth cell compromise.
肠道微生物群越来越被认为在肥胖的发展中起着关键作用。在肥胖患者中观察到肠道微生物群组成向有利于厚壁菌门而不是拟杆菌门的转变。在缺乏活性潘氏细胞α-防御素的小鼠中也报道了类似的转变。我们旨在研究肥胖患者肠道中潘氏细胞抗菌水平的变化。接下来，我们研究了未折叠蛋白反应 (UPR) 的激活作为参与改变潘氏细胞功能的可能机制。在 15 名严重肥胖（BMI>35）和 15 名正常体重的受试者的空肠切片中计数潘氏细胞数量。使用免疫组织化学、qPCR 和 Western blot 研究了潘氏细胞抗菌物质人α-防御素 5 (HD5) 和溶菌酶的表达。通过 Western blot 评估 UPR 的激活。严重肥胖的患者表现出 HD5 和溶菌酶的蛋白水平均降低，而潘氏细胞数量不变。溶菌酶蛋白水平与 BMI 呈负相关。肥胖患者肠道中 HD5 (DEFA5) 和溶菌酶 (LYZ) 转录本的表达增加促使我们研究 UPR 激活可能引起的翻译受阻。结合蛋白 (BiP) 和激活转录因子 4 (ATF4) 的水平增加，证实了肥胖患者肠道中 UPR 的激活。此外，这两种蛋白质的水平与 BMI 相关。BiP 水平与溶菌酶水平之间的负相关强烈表明 UPR 参与了肥胖患者抗菌蛋白水平的降低。此外，肥胖患者的潘氏细胞中出现了内质网应激的迹象。我们的研究结果首次提供了肥胖患者中潘氏细胞功能改变的证据，这可能对与肥胖相关的微生物群组成变化具有重要意义。此外，我们显示了肥胖患者肠道中 UPR 的激活，这可能是观察到的潘氏细胞受损的基础。
