Santos R L, Tsolis R M, Zhang S, Ficht T A, Bäumler A J, Adams L G
Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA.
Infect Immun. 2001 Jul;69(7):4610-7. doi: 10.1128/IAI.69.7.4610-4617.2001.
Salmonella enterica serovar Typhimurium causes cell death in bovine monocyte-derived and murine macrophages in vitro by a sipB-dependent mechanism. During this process, SipB binds and activates caspase-1, which in turn activates the proinflammatory cytokine interleukin-1beta through cleavage. We used bovine ileal ligated loops to address the role of serovar Typhimurium-induced cell death in induction of fluid accumulation and inflammation in this diarrhea model. Twelve perinatal calves had 6- to 9-cm loops prepared in the terminal ileum. They were divided into three groups: one group received an intralumen injection of Luria-Bertani broth as a control in 12 loops. The other two groups (four calves each) were inoculated with 0.75 x 10(9) CFU of either wild-type serovar Typhimurium (strain IR715) or a sopB mutant per loop in 12 loops. Hematoxylin and eosin-stained sections were scored for inflammation, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were detected in situ. Fluid accumulation began at 3 h postinfection (PI). Inflammation was detected in all infected loops at 1 h PI. The area of TUNEL-labeled cells in the wild-type infected loops was significantly higher than that of the controls at 12 h PI, when a severe inflammatory response and tissue damage had already developed. The sopB mutant induced the same amount of TUNEL-positive cells as the wild type, but it was attenuated for induction of fluid secretion and inflammation. Our results indicate that serovar Typhimurium-induced cell death is not required to trigger an early inflammatory response and fluid accumulation in the ileum.
肠炎沙门氏菌鼠伤寒血清型通过一种依赖SipB的机制在体外导致牛单核细胞来源的巨噬细胞和小鼠巨噬细胞死亡。在此过程中，SipB结合并激活半胱天冬酶-1，半胱天冬酶-1继而通过切割激活促炎细胞因子白细胞介素-1β。我们使用牛回肠结扎环来研究鼠伤寒血清型诱导的细胞死亡在这种腹泻模型中液体蓄积和炎症诱导中的作用。12头围产期小牛在回肠末端制备了6至9厘米的肠环。它们被分为三组：一组在12个肠环中进行肠腔内注射Luria-Bertani肉汤作为对照。另外两组（每组4头小牛）在12个肠环中每个肠环接种0.75×10⁹CFU的野生型鼠伤寒血清型（菌株IR715）或sopB突变体。对苏木精和伊红染色切片进行炎症评分，并原位检测末端脱氧核苷酸转移酶介导的dUTP-生物素缺口末端标记（TUNEL）阳性细胞。感染后3小时（PI）开始出现液体蓄积。感染后1小时在所有感染的肠环中检测到炎症。在感染后12小时，当严重的炎症反应和组织损伤已经发展时，野生型感染肠环中TUNEL标记细胞的面积显著高于对照组。sopB突变体诱导的TUNEL阳性细胞数量与野生型相同，但在液体分泌和炎症诱导方面减弱。我们的结果表明，鼠伤寒血清型诱导的细胞死亡并非引发回肠早期炎症反应和液体蓄积所必需的。
