Fig. 1
Immunomodulation by lactic acid bacteria in vitro. a Screening of lactic acid bacteria (LAB) with conditioned medium (CM) for anti-inflammatory activities against LPS-induced TNF-α production in THP-1. Without LPS, a non-detectable amount of TNF-α was observed (lane 1). With 150 ng/ml of LPS treatment, THP-1 cells produced significant amounts of TNF-α (lane 2). Each CM was treated to 5 % of the THP-1 culture volume to assess its inhibitory effects (lane 3, L. reuteri BM36301; lane 4, L. reuteri BM36304; lane 5, L. gasseri BM33601; and lane 6, B. animalis subsp. lactis BM10307). CM from control medium (MRS) was prepared and added in lanes 1 and 2. * indicates p < 0.03 from the t-test between the control (lane 2) and either BM36301 CM-treated (lane 3) or BM10307 CM-treated (lane 6). Bars show averages with standard deviation (SD) from 5 independent assays. b Screening of LAB with live cells for pro-inflammatory activities to induce TNF-α production in THP-1 cells. About 1.5 × 108 bacterial cells from exponentially growing cultures were applied to 6 × 105 THP-1 cells for 6 h. The cell-free supernatants were collected and assessed for the secreted TNF-α by ELISA method. The results show averages with SD from 4 independent experiments. c Summary of in vitro immunomodulation by various lactic acid bacteria