Veldhuizen Edwin J A, Koomen Ingrid, Ultee Ton, van Dijk Albert, Haagsman Henk P
Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands.
Vet Microbiol. 2009 Apr 14;136(1-2):69-75. doi: 10.1016/j.vetmic.2008.09.072. Epub 2008 Sep 30.
Defensins are important antimicrobial effector peptides of the innate immune system, which provides protection against bacterial infections in the intestine. Salmonella Choleraesuis and Salmonella Typhimurium are the most commonly isolated serovars in pig, but disease outcome is dependent on the Salmonella serovar. These infections are a serious problem for the swine industry and are also posing a major threat to public health because of Salmonella-related food-borne illnesses in human. To understand the innate immune response of pigs upon Salmonella infections, we studied the effect of these Salmonella serovars on defensin gene expression in the porcine ileal epithelial cell line IPEC-J2. With the use of scanning electron microscopy, we first visualized the surface characteristics of this cell line, and captured the invasion of Salmonella into the epithelial cell. Gene expression levels of porcine beta-defensin 1 and 2 were both induced upon S. Typhimurium infection but S. Choleraesuis had no effect. Invasion, adhesion and defensin susceptibility of both serovars were similar, which could not explain the observed difference in host response to these Salmonellae. In addition, induction of defensins was dependent on viability of S. Typhimurium, since Salmonella cell- or secreted components had no effect on defensin gene expression. These results provide further insight into the porcine innate immune response towards Salmonella infections, and could partially explain the different epidemiology of Salmonella infections in pig.
防御素是天然免疫系统中重要的抗菌效应肽，可保护肠道免受细菌感染。猪霍乱沙门氏菌和鼠伤寒沙门氏菌是猪中最常分离出的血清型，但疾病的结果取决于沙门氏菌血清型。这些感染对养猪业来说是一个严重问题，并且由于人类中与沙门氏菌相关的食源性疾病，也对公共卫生构成重大威胁。为了解猪在感染沙门氏菌后的天然免疫反应，我们研究了这些沙门氏菌血清型对猪回肠上皮细胞系IPEC-J2中防御素基因表达的影响。通过使用扫描电子显微镜，我们首先观察了该细胞系的表面特征，并捕捉到了沙门氏菌侵入上皮细胞的过程。猪β-防御素1和2的基因表达水平在鼠伤寒沙门氏菌感染后均被诱导，但猪霍乱沙门氏菌没有影响。两种血清型的侵袭、黏附及对防御素的敏感性相似，这无法解释观察到的宿主对这些沙门氏菌反应的差异。此外，防御素的诱导依赖于鼠伤寒沙门氏菌的活力，因为沙门氏菌细胞或分泌成分对防御素基因表达没有影响。这些结果为猪对沙门氏菌感染的天然免疫反应提供了进一步的见解，并可以部分解释猪中沙门氏菌感染不同的流行病学情况。
