Fig. 1.

Experimental design. Macroscopically normal colonic tissue was obtained at surgery from 6 patients with neoplasm. Some tissue fragments were directly frozen (DF) at −80 °C to monitor gene expression changes due to the culture conditions. Colonic tissue fragments were preincubated for 1 h with antibiotics to eradicate indigenous microbiota. Subsequently, the culture medium was replaced with fresh medium containing phorbol 12-myristate 13-acetate (PMA)/ionomycin (IO) to induce inflammation or without PMA/IO (Control sample). Then, the samples were incubated with plain culture medium (Inflamed sample) or culture medium containing 1 × 10⁶ cfu/ml of L. paracasei BL23 (iBL23), L. plantarum 299v (iLP) or the mutant of L. plantarum 299v (iLP(A⁻)), respectively. During the procedure, bacterial counts (10⁶ cfu/ml) of all three strains had no significant variation and only a small proportion of cell lysis occurred in the tissue fragments, as determined by LDH released to the supernatant in each sample (RSL-1, 30 %; RSL-2, 10.2 %; RSL-6, 9.9 %; RSL-7, 10.0 %; RSL-10, 24.4 %; RSL-21, 10.4 %). Tissues were harvested and stored at −80 °C until total RNA was isolated