Clarke Lane L, Gawenis Lara R, Bradford Emily M, Judd Louise M, Boyle Kathryn T, Simpson Janet E, Shull Gary E, Tanabe Hiroki, Ouellette Andre J, Franklin Craig L, Walker Nancy M
Dalton Cardiovascular Research Center and Departmentof Biomedical Sciences, University of Missouri, Columbia, 65211, USA.
Am J Physiol Gastrointest Liver Physiol. 2004 Jun;286(6):G1050-8. doi: 10.1152/ajpgi.00393.2003. Epub 2004 Jan 8.
Paneth cells of intestinal crypts contribute to host defense by producing antimicrobial peptides that are packaged as granules for secretion into the crypt lumen. Here, we provide evidence using light and electron microscopy that postsecretory Paneth cell granules undergo limited dissolution and accumulate within the intestinal crypts of cystic fibrosis (CF) mice. On the basis of this finding, we evaluated bacterial colonization and expression of two major constituents of Paneth cells, i.e., alpha-defensins (cryptdins) and lysozyme, in CF murine intestine. Paneth cell granules accumulated in intestinal crypt lumens in both untreated CF mice with impending intestinal obstruction and in CF mice treated with an osmotic laxative that prevented overt clinical symptoms and mucus accretion. Ultrastructure studies indicated little change in granule morphology within mucus casts, whereas granules in laxative-treated mice appear to undergo limited dissolution. Protein extracts from CF intestine had increased levels of processed cryptdins compared with those from wild-type (WT) littermates. Nonetheless, colonization with aerobic bacteria species was not diminished in the CF intestine and oral challenge with a cryptdin-sensitive enteric pathogen, Salmonella typhimurium, resulted in greater colonization of CF compared with WT intestine. Modest downregulation of cryptdin and lysozyme mRNA in CF intestine was shown by microarray analysis, real-time quantitative PCR, and Northern blot analysis. Based on these findings, we conclude that antimicrobial peptide activity in CF mouse intestine is compromised by inadequate dissolution of Paneth cell granules within the crypt lumens.
肠道隐窝的潘氏细胞通过产生抗菌肽来促进宿主防御，这些抗菌肽被包装成颗粒分泌到隐窝腔中。在此，我们利用光学显微镜和电子显微镜提供证据表明，分泌后的潘氏细胞颗粒发生有限溶解，并在囊性纤维化（CF）小鼠的肠道隐窝中积累。基于这一发现，我们评估了CF小鼠肠道中细菌定植情况以及潘氏细胞的两种主要成分即α-防御素（隐窝素）和溶菌酶的表达。在即将发生肠梗阻的未经治疗的CF小鼠以及用渗透性泻药治疗以预防明显临床症状和黏液积聚的CF小鼠中，潘氏细胞颗粒都在肠道隐窝腔中积累。超微结构研究表明，黏液铸型内颗粒形态变化不大，而用泻药治疗的小鼠中的颗粒似乎发生了有限溶解。与野生型（WT）同窝小鼠相比，CF小鼠肠道的蛋白质提取物中加工后的隐窝素水平有所增加。尽管如此，CF小鼠肠道中需氧菌的定植并未减少，用对隐窝素敏感的肠道病原体鼠伤寒沙门氏菌进行口服攻击时，与WT小鼠肠道相比，CF小鼠肠道中的定植情况更严重。通过微阵列分析、实时定量PCR和Northern印迹分析表明，CF小鼠肠道中隐窝素和溶菌酶mRNA有适度下调。基于这些发现，我们得出结论，CF小鼠肠道中的抗菌肽活性因隐窝腔内潘氏细胞颗粒溶解不足而受损。
