Modulation of Human DCs by a Lactobacillus Strain Figure 3. Measure of chemokines and IFNc in DCs after exposure to L. paracasei, Salmonella or both. DCs were incubated with the probiotic L. paracasei CNCM I-4034 (Prob) or its cell-free supernatant (CFS), Salmonella (S.typhi), or both. The production of IFNc and the chemokines MCP-1/CCL2, MIP-1a/CCL3, RANTES/CCL5 and MDC/CCL22 was measured. LPS, 20 ng/ml, was used as a positive control. Negative-control cultures contained unstimulated DCs. The data shown are the mean values and SEM of three independent experiments. *p,0.05 compared to controls; #p,0.05 compared to S.typhi. doi:10.1371/journal.pone.0043197.g003 whereas the supernatant of the probiotic increased the secretion of TGF-b1. TGF-b1 plays important roles in preventing diseases and controlling intestinal homeostasis [32]. Therefore, the increased secretion of TGF-b1 by DCs stimulated with probiotics may be one mechanism through which probiotics exert anti-inflammatory effects and contribute to immune tolerance. In fact, it has been suggested that this growth factor is crucial for the maturation of tolerogenic Th3 cells [33,34]. Gene array analysis is a new approach for evaluating the effects of probiotics on immune cells, and it has provided an overall view PLOS ONE | www.plosone.org 5 August 2012 | Volume 7 | Issue 8 | e43197