RESUMEN

Intestinal epithelial cells can respond to certain bacteria by producing an array of cytokines and chemokines which are associated with host immune responses. Lactobacillus acidophilus NCFM is a characterized probiotic, originally isolated from human feces. This study aimed to test the ability of L. acidophilus NCFM to stimulate cytokine and chemokine production in intestinal epithelial cells and to elucidate the mechanisms involved in their upregulation. In experiments using intestinal epithelial cell lines and mouse models, we observed that L. acidophilus NCFM could rapidly but transiently upregulate a number of effector genes encoding cytokines and chemokines such as interleukin 1α (IL-1α), IL-1ß, CCL2, and CCL20 and that cytokines showed lower expression levels with L. acidophilus NCFM treatment than chemokines. Moreover, L. acidophilus NCFM could activate a pathogen-associated molecular pattern receptor, Toll-like receptor 2 (TLR2), in intestinal epithelial cell lines. The phosphorylation of NF-κB p65 and p38 mitogen-activated protein kinase (MAPK) in intestinal epithelial cell lines was also enhanced by L. acidophilus NCFM. Furthermore, inhibitors of NF-κB (pyrrolidine dithiocarbamate [PDTC]) and p38 MAPK (SB203580) significantly reduced cytokine and chemokine production in the intestinal epithelial cell lines stimulated by L. acidophilus NCFM, suggesting that both NF-κB and p38 MAPK signaling pathways were important for the production of cytokines and chemokines induced by L. acidophilus NCFM.

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RESUMEN

A new microextraction technique termed dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) coupled with flame atomic absorption spectrometry (FAAS) has been developed for the determination of trace cadmium in water, beverage and cereal samples. In the DLLME-SFO, cadmium was first complexed with 8-hydroxyquinoline, and then extracted into a small volume of the extraction solvent (1-dodecanol) with methanol as a dispersive solvent. Then, the extractant was analyzed by FAAS. The main factors affecting the DLLME-SFO, such as the type and volume of the extraction solvent and dispersive solvent, extraction time, sample volume, the amount of chelating agent, and salt addition were optimized. Under the optimum conditions, the established method showed a good linearity within a range of 1-50 ng mL-1, high enhancement factor (133), low limit of detection (0.3 ng mL-1), satisfactory repeatabilities (the relative standard deviation (RSD) = 3.7%, n = 6), and high recoveries (from 91.8 to 104.4%). The method was applied to determine the cadmium in three different samples (water, beverage and cereal samples) and two certified reference materials. The results indicated that the method can be applied for the determination of trace cadmium in real samples with complex matrices.