plantarum Msa gene [45]. Moreover, the product of lp_1953 is predicted to be intracellular, which contrasts the predicted subcellular location of all other genes examined

here (secreted or cell envelope associated) [24, 25]. This finding supports the notion that surface-localized proteins or components are the most likely candidate-participants in host-microbe interactions [49, 55]. Thus far, the majority of the known immunomodulating MAMPs known for lactobacilli are extracellular or cell surface associated products such as LTA, exopolysaccharides, and peptidoglycan, although intracellular CpG-containing oligodeoxynucleotides (ODNs) produced by some lactobacilli are able to induce IL-10 selleck production in immune cells [21, 49]. These MAMPs are recognized by specific Pattern Recognition Receptors

(PRRs) such as Toll-like receptors (TLRs) and nucleotide oligomerization domain (NOD)-like receptors [21]. To identify the mechanisms underlying the effects of AIP-based QS-TCSs and the N-acetyl-galactosamine/glucosamine phosphotransferase system on immune cells, the cellular products encoded by the genes in these pathways should be investigated to identify the specific cell types among the PBMCs, which include lymphocytes, monocytes and macrophages, that recognize SIS3 concentration these compounds as well as the specific mechanisms leading to altered cytokine production. Comparisons of mutant and wild-type L. plantarum WCFS1 cells included examination of the effects of culture growth phase on the stimulation of PBMCs. Exponential- and stationary-phase L. plantarum WCFS1

cultures were evaluated Navitoclax nmr because the growth phase of probiotic cells was previously shown to influence the immune responses to probiotic bacteria in vitro [56–59] and in vivo [35]. Using human PBMCs, we found significant growth-phase dependent differences in the immunomodulatory capacities of the wild-type AMP deaminase and mutant L. plantarum cultures. Collectively, the exponential-phase L. plantarum WCFS1 cultures stimulated higher absolute amounts of IL-10 and IL-12 and hence appear to induce heighted immune responses by PBMCs compared with stationary-phase cells. Notably, this result was not due to extensive L. plantarum growth because antibiotics were added to the PBMC growth medium to prevent bacterial overgrowth which would generate artifacts from acidification of the medium causing PBMC cell stress or death. Moreover, intact and lysed L. plantarum strains cells collected from the exponential and stationary phase of growth do not show striking differences in their TLR9 signaling activity and there was not a clear trend among all strains tested (personal observation, M. Meijerink and J. M. Wells). Therefore the higher amounts of cytokines induced by exponential phase bacteria are unlikely to be caused by differential cell lysis resulting in the release of intracellular CpG DNA, a known MAMP recognized by TLR9. Comparisons of wild-type and mutant L.