In vitro and ex vivo evaluation of the anti-Giardia duodenalis activity of the supernatant of SLAB51 (SivoyTM)

The effects on Giardia duodenalis growth (G), adherence (A), and viability (V) of SivoyTM probiotic supernatant were evaluated in vitro and ex vivo. SivoyTM (101 UFC) was in vitro cultured and the obtained supernatant was filtered, adjusted at pH 7, and added (100 μl/ml) as such (FS) or after heat-treatment to G. duodenalis (5×104) cultures in TYI-S-33 medium. Negative and metronidazole 20 μg/ml (M) treated controls were used. Ex vivo, five- 1 cm long mice duodenal portions were cultivated in standard conditions with 5X105 G. duodenalis trophozoites/ml, while to further five duodenal portions similarly cultured and infected, FS 200μl was added. After 12 and 18h, samples were fixed in 10% buffered formalin and histologically processed to score Giardia infection and cell damage. Cells proliferation/apoptosis were scored by TUNEL, Caspase–3, and Ki67 tests. All data, in triplicate, were statistically evaluated (P< 0.05). Results showed that FS significantly reduced Giardia G and V respect to negative controls but its efficacy was lower than that of M, while the inhibition of A was similar to that of M. Moreover, the effects of FS were significantly lowered by heat-treatment and the reduction was statistically higher at 90°C than at 56°C, indicating a heat-sensitive nature of active FS compounds. In ex vivo trials, in intestinal sections treated with FS respect to untreated controls viable G. duodenalis trophozoites and enterocyte TUNEL+ and Caspase-3 expression were significantly reduced, while enterocyte Ki67 expression was significantly increased, confirming the anti-G. duodenalis activity of FS observed in vitro.