Wells C L, VandeWesterlo E M, Jechorek R P, Erlandsen S L
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, 55455-0374, USA.
Crit Care Med. 1996 Jun;24(6):985-91. doi: 10.1097/00003246-199606000-00019.
To clarify the effect of hypoxia on bacteria-enterocyte interactions.
Randomized.
Research laboratory.
Enteric bacterial and cultured human intestinal epithelial cells, HT-29 cells.
The effect of hypoxia on bacterial internalization and intracellular survival was studied, using enterocytes cultured for 21 days in either 20%, 10%, or 5% oxygen. The effect of bacterial growth conditions on bacterial internalization by enterocytes was studied, using bacterial cells in either the log phase or stationary phase of aerobic growth, and using bacterial cells in stationary phase, grown either under low oxygen conditions or under anaerobic conditions.
Individual strains of enteric bacteria were incubated with HT-29 cells for 1 hr. Numbers of internalized bacteria were subsequently quantified after enterocyte lysis. Bacterial growth conditions (anaerobic vs. aerobic and log-phase vs. stationary-phase bacterial cells) had no noticeable effect on the numbers of Salmonella typhimurium, Proteus mirabilis, and Escherichia coli internalized by enterocytes. Enterocytes cultivated in 20%, 10%, or 5% oxygen were >95% viable. Enterocytes cultivated in 20% oxygen were confluent, but those enterocytes cultivated in hypoxia were not confluent and were fewer in number compared with enterocytes cultivated in normoxia. Compared with enterocytes grown in normoxia, enterocytes cultivated in 5% and 10% oxygen internalized greater numbers of each of seven strains of enteric bacteria, including Listeria monocytogenes (two strains), Enterococcus faecalis (two strains), and P. mirabilis, E. coli (two strains), with statistically significant increases noted for five of these seven bacterial strains. Intracellular survival of L. monocytogenes and P. mirabilis was assayed. Both species survived intracellularly for 22 hrs, with no noticeable differences in the numbers of intracellular bacteria recovered from enterocytes cultivated in 20%, 10%, and 5% oxygen.
These in vitro results suggest that augmented bacterial endocytosis by enterocytes might at least partially explain the increased frequency of bacterial translocation associated with tissue ischemia.
阐明缺氧对细菌与肠上皮细胞相互作用的影响。
随机化。
研究实验室。
肠道细菌和培养的人肠上皮细胞HT - 29细胞。
使用在20%、10%或5%氧气环境中培养21天的肠上皮细胞，研究缺氧对细菌内化和细胞内存活的影响。使用处于需氧生长对数期或稳定期的细菌细胞，以及在低氧条件或厌氧条件下生长的处于稳定期的细菌细胞，研究细菌生长条件对肠上皮细胞细菌内化的影响。
将各肠道细菌菌株与HT - 29细胞孵育1小时。随后在肠上皮细胞裂解后对内化细菌的数量进行定量。细菌生长条件（厌氧与需氧以及对数期与稳定期细菌细胞）对鼠伤寒沙门氏菌、奇异变形杆菌和大肠杆菌被肠上皮细胞内化的数量没有明显影响。在20%、10%或5%氧气环境中培养的肠上皮细胞活力>95%。在20%氧气环境中培养的肠上皮细胞汇合，但在缺氧环境中培养的肠上皮细胞不汇合，且与在常氧环境中培养的肠上皮细胞相比数量较少。与在常氧环境中生长的肠上皮细胞相比，在5%和10%氧气环境中培养的肠上皮细胞内化七种肠道细菌菌株（包括两株单核细胞增生李斯特菌、两株粪肠球菌、奇异变形杆菌、大肠杆菌两株）中的每一种的数量更多，这七种细菌菌株中有五种的增加具有统计学意义。检测了单核细胞增生李斯特菌和奇异变形杆菌的细胞内存活情况。两种菌在细胞内均存活22小时，从在20%、10%和5%氧气环境中培养的肠上皮细胞中回收的细胞内细菌数量没有明显差异。
这些体外研究结果表明，肠上皮细胞增强的细菌内吞作用可能至少部分解释了与组织缺血相关的细菌易位频率增加的原因。
