Dotan Iris, Rachmilewitz Daniel
IBD Service, Department of Gastroenterology and Liver Diseases, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel.
Curr Opin Gastroenterol. 2005 Jul;21(4):426-30.
Probiotics are live, nonpathogenic bacteria that confer health benefits beyond their nutritional value. In inflammatory bowel disease, where changes in bacterial flora have been demonstrated, there is an increasing interest in modulating the flora with probiotic strains. The beneficial effect of probiotics is demonstrated mainly in pouchitis and ulcerative colitis; however, their mechanisms of action are not well defined. The purpose of this review is to discuss the latest findings related to their mechanism of action.
A decrease in the secretion of pro-inflammatory cytokines, IFN-gamma, TNF-alpha and IL-12, and interference with bacterial adherence to the epithelium has been demonstrated. At the molecular level, an anti-inflammatory effect associated with NF-kappaB inhibition, heat-shock protein induction and proteasome inhibition has been suggested, although NF-kappaB induction has also been demonstrated. Unexpectedly, the beneficial effects described were achieved not only by live bacteria but also by gamma-irradiated nonviable bacteria, bacterial DNA components and probiotic-cultured media.
Understanding the mechanisms responsible for the beneficial effect of probiotics in inflammatory bowel disease and experimental colitis may help understand the role of bacteria in disease pathogenesis. The findings that live probiotics may not be mandatory to be beneficial, and that therapeutic effects may be obtained by systemic, rather than oral administration could have a major impact on the practical use and manufacturing of probiotics.
益生菌是活的非致病性细菌，除了具有营养价值外，还能带来健康益处。在已证实细菌菌群发生变化的炎症性肠病中，人们对用益生菌菌株调节菌群的兴趣日益增加。益生菌的有益作用主要在袋状结肠炎和溃疡性结肠炎中得到证实；然而，它们的作用机制尚不清楚。本综述的目的是讨论与其作用机制相关的最新发现。
已证实促炎细胞因子、干扰素-γ、肿瘤坏死因子-α和白细胞介素-12的分泌减少，以及对细菌黏附上皮的干扰。在分子水平上，尽管也证实了核因子-κB的诱导，但有人提出了与核因子-κB抑制、热休克蛋白诱导和蛋白酶体抑制相关的抗炎作用。出乎意料的是，所述有益效果不仅通过活细菌实现，还通过γ射线照射的非活细菌、细菌DNA成分和益生菌培养基实现。
了解益生菌在炎症性肠病和实验性结肠炎中产生有益作用的机制，可能有助于理解细菌在疾病发病机制中的作用。活益生菌不一定是有益的，且通过全身给药而非口服给药可能获得治疗效果，这些发现可能会对益生菌的实际应用和生产产生重大影响。
