Gonzales Amanda M, Wilde Shyra, Roland Kenneth L
Biodesign Institute, Arizona State University, Tempe, Arizona, USA.
Biodesign Institute, Arizona State University, Tempe, Arizona, USA
Infect Immun. 2017 Aug 18;85(9). doi: 10.1128/IAI.00172-17. Print 2017 Sep.
serovar Typhi causes the systemic disease typhoid fever. After ingestion, it adheres to and invades the host epithelium while evading the host innate immune response, causing little if any inflammation. Conversely, serovar Typhimurium causes gastroenteritis in humans and thrives in the inflamed gut. Upon entering the host, Typhimurium preferentially colonizes Peyer's patches, a lymphoid organ in which microfold cells (M cells) overlay an arrangement of B cells, T cells, and antigen-presenting cells. Both serovars can adhere to and invade M cells and enterocytes, and it has been assumed that Typhi also preferentially targets M cells. In this study, we present data supporting the alternative hypothesis that Typhi preferentially targets enterocytes. Using a tissue culture M cell model, we examined Typhi strains with a deletion in the fimbriae. The deletion resulted in increased adherence to M cells and, as expected, decreased adherence to Caco-2 cells. Adherence to M cells could be further enhanced by introduction of the long polar fimbriae (Lpf), which facilitate adherence of Typhimurium to M cells. Deletion of and/or introduction of enhanced M cell invasion as well, leading to significant increases in secretion of interleukin 8. These results suggest that Typhi may preferentially target enterocytes .
伤寒杆菌会引发全身性疾病伤寒热。摄入后，它会黏附并侵入宿主上皮细胞，同时逃避宿主的固有免疫反应，几乎不会引发炎症（即便有炎症也很轻微）。相反，鼠伤寒杆菌会导致人类患肠胃炎，并在发炎的肠道中大量繁殖。进入宿主后，鼠伤寒杆菌优先定殖于派尔集合淋巴结，这是一种淋巴器官，其中微褶细胞（M细胞）覆盖着B细胞、T细胞和抗原呈递细胞的排列结构。两种血清型都能黏附并侵入M细胞和肠上皮细胞，并且一直以来人们认为伤寒杆菌也优先靶向M细胞。在本研究中，我们提供的数据支持了另一种假说，即伤寒杆菌优先靶向肠上皮细胞。我们使用组织培养的M细胞模型，检测了菌毛缺失的伤寒杆菌菌株。这种缺失导致对M细胞的黏附增加，并且正如预期的那样，对Caco-2细胞的黏附减少。引入长极菌毛（Lpf）可进一步增强对M细胞的黏附，长极菌毛有助于鼠伤寒杆菌黏附于M细胞。菌毛的缺失和/或引入也增强了对M细胞的侵袭，导致白细胞介素8的分泌显著增加。这些结果表明，伤寒杆菌可能优先靶向肠上皮细胞。
