Search

CD4+T cells mediate antigen-specific allograft tolerance, but die in culture without activated lymphocyte derived cytokines. Supplementation of the media with cytokine rich supernatant, from ConA activated spleen cells, preserves the capacity of tolerant cells to transfer tolerance and suppress rejection. rIL-2 or rIL-4 alone are insufficient to maintain these cells, however. We observed that activation of naive CD4+CD25+FOXP3+Treg with alloantigen and the Th2 cytokine rIL-4 induces them to express interleukin-5 specific receptor alpha (IL-5Rα) suggesting that IL-5, a Th2 cytokine that is produced later in the immune response may promote tolerance mediating Treg. This study examined if recombinant IL-5(rIL-5) promoted survival of tolerant CD4+, especially CD4+CD25+T cells. CD4+T cells, from DA rats tolerant to fully allogeneic PVG heart allografts surviving over 100days without on-going immunosuppression, were cultured with PVG alloantigen and rIL-5. The ability of these cells to adoptively transfer tolerance to specific-donor allograft and suppress normal CD4+T cell mediated rejection in adoptive DA hosts was examined. Tolerant CD4+CD25+T cells' response to rIL-5 and expression of IL-5Rα was also assessed. rIL-5 was sufficient to promote transplant tolerance mediating CD4+T cells' survival in culture with specific-donor alloantigen. Tolerant CD4+T cells cultured with rIL-5 retained the capacity to transfer alloantigen-specific tolerance and inhibited naive CD4+T cells' capacity to effect specific-donor graft rejection. rIL-5 promoted tolerant CD4+CD25+T cells' proliferation in vitro when stimulated with specific-donor but not third-party stimulator cells. Tolerant CD4+CD25+T cells expressed IL-5Rα. This study demonstrated that IL-5 promoted the survival of alloantigen-specific CD4+CD25+T cells that mediate transplant tolerance.

We investigated the expression profiles of proteolysis-related genes in Lactobacillus paracasei EG9, a non-starter lactic acid bacterial strain used as an adjunct starter in Gouda-type cheese production. The amino acid sequences of previously reported proteolytic enzymes in lactic acid bacteria were matched against the EG9 genome by translated BLAST search, and 31 candidate genes, including those coding for peptidases, oligopeptide transporters, and cell-envelope proteinases, were listed. The relative expression levels of these genes were evaluated at 0 and 30 days of cheese ripening. On day 0, 27 genes showed significantly up-regulated expression compared with the genes in the stationary phase of the reference cultured cells. On day 30, 25 genes were found to be significantly down-regulated. Our findings suggest that the proteolysis-related genes in EG9 play an important role in the proteolytic process from casein degradation through peptide uptake to free amino acid production during cheesemaking.

Experimental autoimmune neuritis (EAN) induced by peripheral nerve myelin (PNM) is self-limiting and re-immunization with PNM does not re-activate disease. This study showed inhibition of EAN by CD4+CD25+T cells both from sensitized hosts or from naive hosts after ex-vivo activation by PNM and rIL-2. Transfer of naive CD4+CD25+T cells has no effect on EAN, nor did naive CD4+CD25+T cells activated with rIL-2 and renal tubular antigen. Culture of naive CD4+CD25+Treg with rIL-2 and PNM induced mRNA for the IFN-gamma receptor. We showed naive CD4+CD25+T cells activated by specific auto-antigen and rIL-2 produced more potent antigen-specific Treg that may have therapeutic potential.

Meat 'reddening' by bacteria was observed in chilled beef. To identify the reddening bacteria, isolates were inoculated onto beef and the changes in CIE L*a*b* values monitored. As a result, two Pseudomonas spp., including Pseudomonas fragi which is commonly observed in raw meat, were selected and identified as reddening bacteria. The reddening was coincidentally occurred with the appearance of slime, and the increase in thiobarbituric acid-reactive substances (TBARS) was simultaneously suppressed. In myoglobin-containing nutrient broth, it is shown spectroscopically that P. fragi converted metmyoglobin into deoxymyoglobin. It was concluded that the meat reddening was due to the formation of deoxymyoglobin, induced by the very-low-oxygen tension brought about by Pseudomonad's oxygen consumption: This oxygen depletion simultaneously suppressed TBARS increase.

Bile resistance is one of the basic characteristics of probiotic bacteria. The aim of this study was to investigate the characteristics of bile resistance in lactococci by studying the relationship between bile resistance and cellular fatty acid composition in lactococcci grown on different media. We determined the bile resistance of 14 strains in lactose-free M17 medium supplemented with either glucose only (GM17) or lactose only (LM17). Gas chromatographic analyses of free lipids extracted from the tested strains were used for determining their fatty acid composition. A correlation analysis of all strains grown in both media revealed significant positive correlations between bile resistance and relative contents of hexadecanoic acid and octadecenoic acid, and negative correlations between bile resistance and relative contents of hexadecenoic acid and C-19 cyclopropane fatty acid. It is also a fact that the fatty acids associated with bile resistance depended on species, strain, and/or growth medium. In L. lactis subsp. cremoris strains grown in GM17 medium, the bile-resistant strains had significantly more octadecenoic acid than the bile-sensitive strains. In LM17 medium, bile-resistant strains had significantly more octadecenoic acid and significantly less C-19 cyclopropane fatty acid than the bile-sensitive strains. In L. lactis subsp. lactis strains, bile resistances of some of the tested strains were altered by growth medium. Some strains were resistant to bile in GM17 medium but sensitive to bile in LM17 medium. Some strains were resistant in both media tested. The strains grown in GM17 medium had significantly more hexadecanoic acid and octadecenoic acid, and significantly less tetradecanoic acid, octadecadienoic acid and C-19 cyclopropane fatty acid than the strains grown in LM17 medium. In conclusion, the fatty acid compositions of the bile-resistant lactococci differed from those of the bile-sensitive ones. More importantly, our data suggest that altering their fatty acid composition (i.e. increased hexadecanoic acid and octadecenoic acid and decreased hexadecenoic acid and C-19 cyclopropane fatty acid) by changing growth conditions may be a useful way to enhance their bile resistance in lactococci.

In a series of in vitro culture experiments using the murine macrophage-like cell line, J774.1, we investigated the ability of 46 different Lactococcus lactis strains to induce production of the cytokines interleukin (IL)-6, IL-12 and tumor necrosis factor (TNF)-alpha. The extent of induction of IL-6, IL-12 and TNF-alpha was strain-specific and was not related to subspecies, biovariety, or the source of the isolate. When incubated with a high concentration of viable cells of some lactococcal strains, J774.1 cells hardly produced cytokines in which case the percentage of J774.1 cells that were double-stained with the apoptosis probe FITC-labeled annexin V and propidium iodide was significantly increased. This finding suggests that perturbation of cytokine induction is due to the cytotoxic effects of these strains. On the other hand, when incubated with living cells of other strains, even at a high concentration, J774.1 cells produced IL-6, IL-12 and TNF-alpha. In these cases, FITC-labeled annexin V interacted with these cells, suggesting that incubation with these strains causes phosphatidylserine to be exposed at the cell surface. The ability of these strains to induce TNF-alpha, but not IL-6 and IL-12, was lost after heat treatment, suggesting that the stimulus required for TNF-alpha induction is heat sensitive and is different from those required for IL-6 and IL-12 induction. The specificity of cytokine induction by different lactococci is discussed in terms of interaction of non-pathogenic bacteria with macrophages, as well as the implications for the use of lactococci as probiotics.

Certain strains of lactic acid bacteria present in commercial cheese starters, characterized by faint transparent colonies on an agar plate containing 1 mg kg −1 crystal violet (CVT), were identified as Lactococcus lactis subsp. (ssp) lactis biovar diacetylactis. The effect of citrate on the growth of these strains (CVT strains) in the presence of glucose was studied, in comparison with L. lactis strains. Molar growth yield from glucose ( Y G , g dry weight/mole of glucose consumed) for CVT strains grown on glucose plus citrate was significantly higher than the control (i.e. without citrate), but not for other L. lactis strains tested. Enhanced Y G was also observed at a pH-controlled experiment, indicating that enhanced Y G did not result from a buffering effect of citrate. CVT strains, in contrast to other strains of the same species, were shown to obtain enough energy to enhance Y G on glucose–citrate mixtures.

A specific monoclonal antibody, M3A, was produced to rapidly purifyLactococcus lactisphosphoglucose isomerase (PGI) for amino acid sequence analysis. M3A recognized theLac. lactisPGI specifically and sensitively with both enzyme-linked immunosorbent assay and Western blot analysis. The enzyme was rapidly purified to a specific activity of 21.8 U/mg with a yield of 20% by a three-step procedure, including M3A-bound Sepharose chromatography. The specific activity of PGI was increased about 64.1-fold from the cell lysate. The molecular mass ofLac. lactisPGI was estimated to be about 50 kDa by SDS–PAGE. The N-terminal amino acid sequence ofLac. lactisPGI exhibited no significant similarity to other PGIs, except for a 52.6% identity toBacillus stearothermophilusPGI A and PGI B. These results suggest that there might be some molecular types of PGI.

Corrigendum to ‘Characterization and classification of Japanese consumer perceptions for beef tenderness using descriptive texture characteristics assessed by a trained sensory panel’ [Meat Science 96 (2014) 994–1002] Keisuke Sasaki ⁎, Michiyo Motoyama , Takumi Narita , Tatsuro Hagi , Koichi Ojima , Mika Oe , Ikuyo Nakajima , Katsuhito Kitsunai , Yosuke Saito , Hikari Hatori , Susumu Muroya , Masaru Nomura , Yuji Miyaguchi , Koichi Chikuni a