Quorum sensing in sourdough Lactobacillus plantarum DC400: induction of plantaricin A (PlnA) under co-cultivation with other lactic acid bacteria and effect of PlnA on bacterial and Caco-2 cells.

This work aimed at showing the effect of pheromone plantaricin A (PlnA) by Lactobacillus plantarum DC400 towards other sourdough lactic acid bacteria and the potential of PlnA to protect the function of the human intestinal barrier. Growth and survival of sourdough lactic acid bacteria were differently affected by co-cultivation with L. plantarum DC400. Compared to mono-cultures, Lactobacillus sanfranciscensis DPPMA174 and Pediococcus pentosaceus 2XA3 showed growth inhibition and decreased viability when co-cultured with L. plantarum DC400. L. sanfranciscensis DPPMA174 induced the highest synthesis of PlnA. Survival of strain DPPMA174 only slightly varied by comparing the addition of PlnA to the culture medium and the co-cultivation with L. plantarum DC400. Compared to mono-culture, the proteome of L. sanfranciscensis DPPMA174 grown in co-culture with L. plantarum DC400 showed the variation of expression of 58 proteins (47 over expressed and 11 repressed). Thirty-four of them were also over expressed or repressed during growth of DPPMA174 with PlnA. Fifty-one of the above 58 proteins were identified. They had a central role in stress response, amino acid, energy and nucleotide metabolisms, membrane transport, regulation of transcription, and cell redox homeostasis. PlnA markedly increased the viability of human Caco-2/TC7 cells and the transepithelial electrical resistance.

Apoptosis induced by oxidized lipids is associated with up-regulation of p66Shc in intestinal Caco-2 cells: protective effects of phenolic compounds.

In this study, we investigated the alterations of the redox balance induced by the lipid fraction of oxLDL in Caco-2 intestinal cells, and the effects of tyrosol and protocatechuic acid, two dietary phenolic compounds. We found that oxidized lipids extracted from oxLDL (LipE) induced oxidative stress by determining, 6 h after treatment, ROS overproduction (about a 100% and a 43% increase of O*2 and H2O2 production, respectively, P<.05: LipE vs. control) and, 12 h after treatment, GSH depletion (about a 26% decrease, P<.05: LipE vs. control), and by impairing the activities of superoxide dismutase, catalase and glutathione peroxidase. In response to the induced oxidative stress, we observed significant overexpression of glutathione peroxidase (6 h after treatment: P<.05), glutathione reductase and gamma-glutamylcysteine synthetase (12 h after treatment: P<.05). Notably, when GSH depletion occurred, p66Shc protein expression increased by about 300% with respect to control (P<.001; LipE vs. control). These effects were fully counteracted by dietary phenolics which inhibited ROS overproduction and GSH consumption, rendered the reactive transcription of glutathione-associated enzymes unnecessary and blocked the intracellular signals leading to the overexpression and rearrangement of p66Shc signalling molecule. Altogether, these results suggest that the impairment of the antioxidant system hijacks intestinal cells towards an apoptotic-prone phenotype via the activation of p66Shc molecule. They also propose a reappraisal of dietary polyphenols as intestinal protecting agents, indicating the antiapoptotic effect as a further mechanism of action of these antioxidant compounds.

Selective adsorption of homocysteine using an HFR-ON LINE technique.

HFR-ON LINE (double chamber HDF with reinfusion of ultrafiltrate regenerated through a charcoal-resin cartridge) is a novel method which combines the processes of diffusion, convection, and adsorbance. We have investigated the effect of such a treatment on the homocysteine (Hcy) levels in ten patients with a mean Hcy level of 57.6 micromol/L (range 24.1-119.7 micromol/L). We have measured the Hcy, folate, and vitamin B12 predialysis and postdialysis, and in the ultrafiltrate precartridge and postcartridge at 10, 120, and 240 min. The mean Hcy levels were 57.6 and 35.3 micromol/L (range 9.9-80.3 micromol/L) (P = 0.005) predialysis and postdialysis, respectively, while folate and vitamin B12 were unchanged. Precartridge and postcartridge Hcy levels were 11.6 vs. 2.5 micromol/L (P = 0.005), 9.3 vs. 3.9 micromol/L (P = 0.005), and 7.7 vs. 4.6 micro mol/L (P = 0.012) at the three time points considered, while folate and vitamin B12 were essentially undetectable. These preliminary data, which need confirmation in a long-term study, seem to indicate that HFR-ON LINE is able to reduce Hcy levels not only through a likely reduction of uremic toxins, but also through an actual removal of Hcy by adsorbance onto the charcoal-resin cartridge.