Lopez Mariela, Li Nan, Kataria Jasmeet, Russell Michael, Neu Josef
Department of Pediatrics, University of Florida, Gainesville, FL 32610-0296, USA.
J Nutr. 2008 Nov;138(11):2264-8. doi: 10.3945/jn.108.093658.
Probiotics are widely used in the treatment and prevention of gastrointestinal problems. However, in some immune-compromised populations, the administration of live microorganisms may not be appropriate. A potential alternative to live microorganisms is to inactivate them as long as the beneficial function is retained. We hypothesized that UV-inactivated Lactobacillus rhamnosus GG (LGG) could downregulate interleukin-8 (IL-8) production in intestinal epithelial cells stimulated by the pathogenic ligand, flagellin, using similar mechanisms as live LGG. Caco-2 cells were pretreated with live or UV-inactivated LGG at 10(11) colony-forming units/L and stimulated by flagellin at a dose of 500 mug/L. IL-8 production was measured by ELISA, inhibitor of kappaB (IkappaB) and ubiquitinated-IkappaB (Ub-IkappaB) expression by immunoblotting and nuclear factor (NF) kappaB localization by immunofluorescence staining. Flagellin induced a 17-fold increase in IL-8 production compared with control (P < 0.05), whereas pretreatment with either live LGG or UV-inactivated LGG resulted in 66 and 59% decreases, respectively, compared with the flagellin group (P < 0.05). Flagellin-induced NFkappaB nuclear translocation was prevented by both live and UV-inactivated LGG. Flagellin decreased IkappaB, which was reversed by either live or UV-inactivated LGG (P < 0.05). UV-inactivated LGG decreased Ub-IkappaB expression (P < 0.05), although live LGG had no effect. This study supports the concept that UV-inactivated and live LGG are equally effective in decreasing IL-8 production in the intestinal epithelium. Although the mechanism involves different pathways, both alter cytoplasmic IkappaB, thereby inhibiting NFkappaB nuclear translocation.
益生菌广泛用于胃肠道问题的治疗和预防。然而，在一些免疫功能低下的人群中，施用活微生物可能并不合适。只要保留有益功能，活微生物的一种潜在替代方法是将它们灭活。我们假设紫外线灭活的鼠李糖乳杆菌GG（LGG）可以使用与活LGG类似的机制，下调由致病配体鞭毛蛋白刺激的肠上皮细胞中白细胞介素-8（IL-8）的产生。将Caco-2细胞用10¹¹集落形成单位/升的活LGG或紫外线灭活的LGG预处理，并以500微克/升的剂量用鞭毛蛋白刺激。通过酶联免疫吸附测定（ELISA）测量IL-8的产生，通过免疫印迹法检测κB抑制蛋白（IkappaB）和泛素化的IkappaB（Ub-IkappaB）的表达，并通过免疫荧光染色检测核因子（NF）κB的定位。与对照相比，鞭毛蛋白诱导IL-8产生增加了17倍（P<0.05），而与鞭毛蛋白组相比，用活LGG或紫外线灭活的LGG预处理分别导致IL-8产生减少66%和59%（P<0.05）。活LGG和紫外线灭活的LGG均能阻止鞭毛蛋白诱导的NFκB核易位。鞭毛蛋白使IkappaB减少，而活LGG或紫外线灭活的LGG均可使其恢复（P<0.05）。紫外线灭活的LGG降低了Ub-IkappaB的表达（P<0.05），而活LGG则无此作用。本研究支持以下观点：紫外线灭活的LGG和活LGG在降低肠上皮细胞中IL-8产生方面同样有效。虽然其机制涉及不同途径，但两者均改变细胞质中的IkappaB，从而抑制NFκB核易位。
