Comparative study of the in vitro immunomodulatory effects of the probiotics Escherichia coli Nissle 1917 and Enterococcus faecalis UGRA10.

A Rodriguez-Nogales1, F Algieri1, T Vezza1, E Ferraro1, N Garrido-Mesa1, ME Rodriguez-Cabezas1, MP Utrilla1, M Martin-Bueno2, E Valdivia2, A Zarzuelo1, M Comalada3, M Maqueda2, J Galvez1. 1University of Granada, Department of Pharmacology, Spain, 2University of Granada, Department of Microbiology, Spain, 3Institute for Research in Biomedicine, Barcelona, Macrophage Biology Group, Spain

Introduction: Probiotics have shown to be beneficial in different disorders, especially in those affecting the gastrointestinal tract, although not all of them display the same biological effects. The immunomodulatory properties ascribed to the probiotics may contribute to their differential effects. The aim of the present study was to compare the in vitro effects of two probiotics Escherichia coli Nissle 1917 and Enterococcus faecalis UGRA10 in two different cell types involved in the immune response: HT-29 cells (as a model of epithelial cells) and RAW 264.7 cells (as a model of macrophage cells).

Material and Methods: Each cell type was incubated for 3 hours with each probiotic at the concentration of 10exp8 colony forming units (CFU) per ml. Then, the cells were stimulated, or not, with LPS (10 µG/ML) for 24 hours. After this, the supernatants were collected and cytokine production (IL-8 in HT-29 cells, and IL-1β or TNFα in RAW 264.7 cells) was determined by ELISA. Also, nitrite levels were determined by the Griess assay. Statistical analyses was carried out with Statgraphics 5.0, with statistical significance set at p<0.05 using a one-way analysis of variance (ANOVA) and post hoc least significance tests.

Results: The results revealed that the incubation of both cell types with E.coli Nissle 1917 promoted an increased production of all the mediators studied when compared with those cells without probiotic incubation (Table 1). However, E. faecalis UGRA10 did not modify IL-8 production in HT-29 cells, whereas it increased the production of IL-1β and TNFα in macrophages, without affecting nitrite levels (Table 1). Typically, the increase production observed after probiotic treatment was lower than that obtained for the LPS control. When cells were incubated with each probiotic before the LPS-stimulation, the production of IL-8, TNFα or nitrites, but not IL-1β, was significantly decreased (Table 1). Of note, the incubation of the macrophage cell line RAW 264.7 with E. faecalis UGRA10 completely abolished the increased generation of nitrites induced with LPS.

Table 1. Effects of E. coli Nissle 1917 (EcN) and E. faecalis UGRA10 on the production of IL-8 (HT-29 cells), IL-1β, TNFα and nitrites (RAW 264.7) both in basal conditions and after LPS stimulation.

Data are expressed as mean ± SEM from at least six different experiments. *p<0.05 vs. No probiotic.

Conclusion: E. coli Nissle 1917 and E. faecalis UGRA10 show immunomodulatory properties, but they do not display the same profile in the two different cell types studied. Whereas E coli Nissle 1917 stimulates both HT-29 and RAW 264.7 in basal conditions, E. faecalis UGRA10 only increased the production of IL-1β and TNFα in macrophages. Both probiotics exert inhibitory effects on the LPS-induced cytokine or nitrite production in these two cell lines, but E. faecalis UGRA10 showed a higher efficacy.