http://hdl.handle.net/10468/109 Sat, 25 May 2013 10:57:49 GMT 2013-05-25T10:57:49Z http://hdl.handle.net/10468/639 The spingosine-1-phosphate analogue FTY720 impairs mucosal immunity and clearance of the enteric pathogen Citrobacter rodentium Murphy, Carola T.; Hall, Lindsay J.; Hurley, Grainne; Quinlan, Aoife; MacSharry, John; Shanahan, Fergus; Nally, Kenneth; Melgar, Silvia The sphingosine-1-phosphate (S1P) analogue, FTY720, is therapeutically efficacious in multiple sclerosis and in the prevention of transplant rejection. It prevents migration of lymphocytes to sites of pathology by trapping them within the peripheral lymph nodes, the mesenteric lymph nodes (MLNs) and Peyer's patches. However, evidence suggests that its clinical use may increase the risk of mucosal infections. We investigated the impact of FTY720 treatment on susceptibility to gastrointestinal infection with the mouse enteric pathogen, Citrobacter rodentium (C. rodentium). This attaching and effacing bacterium induces a transient bacterial colitis in immunocompetent mice, which resembles human infection with pathogenic Escherichia coli. FTY720 treatment induced peripheral blood lymphopenia, trapped lymphocytes in the MLNs and prevented clearance of bacteria when mice were infected with luciferase-tagged C. rodentium. FTY720-treated C. rodentium-infected mice had enhanced colonic inflammation, with significantly higher colon mass, colonhistopathology and neutrophil infiltration, when compared with vehicle-infected animals. In addition, FTY720-treated infected mice had significantly lower numbers of colonic dendritic cells, macrophages and T cells. Gene expression analysis demonstrated that FTY720-treated infected mice had an impaired innate immuneresponse and a blunted mucosal adaptive immune response including Th1 cytokines. The data demonstrate that the S1P analogue, FTY720, adversely affects the immune response and clearance of C. rodentium. Wed, 01 Aug 2012 00:00:00 GMT http://hdl.handle.net/10468/639 2012-08-01T00:00:00Z http://hdl.handle.net/10468/1109 Comparison of the principal proteins in bovine, caprine, buffalo, equine and camel milk Hinz, Katharina; O'Connor, Paula; Huppertz, Thom; Ross, R. Paul; Kelly, Alan L. Proteomic analysis of bovine, caprine, buffalo, equine and camel milk highlighted significant interspecies differences. Camel milk was found to be devoid of β-lactoglobulin, whereas β-lactoglobulin was the major whey protein in bovine, buffalo, caprine, and equine milk. Five different isoforms of κ-casein were found in camel milk, analogous to the micro-heterogeneity observed for bovine κ-casein. Several spots observed in 2D-electrophoretograms of milk of all species could tentatively be identified as polypeptides arising from the enzymatic hydrolysis of caseins. The understanding gained from the proteomic comparison of these milks may be of relevance both in terms of identifying sources of hypoallergenic alternatives to bovine milk and detection of adulteration of milk samples and products. Wed, 02 May 2012 00:00:00 GMT http://hdl.handle.net/10468/1109 2012-05-02T00:00:00Z http://hdl.handle.net/10468/1110 Proteomic study of proteolysis during ripening of cheddar cheese made from milk over a lactation cycle Hinz, Katharina; O'Connor, Paula; O'Brien, Bernadette; Huppertz, Thom; Ross, R. Paul; Kelly, Alan L. Milk for cheese production in Ireland is predominantly produced by pasture-fed spring-calving herds. Consequently, there are marked seasonal changes in milk composition, which arise from the interactive lactational, dietary and environmental factors. In this study, Cheddar cheese was manufactured on a laboratory scale from milk taken from a spring calving herd, over a 9-month lactation cycle between early April and early December. Plasmin activity of 6-months-old Cheddar cheese samples generally decreased over ripening time. One-dimensional urea-polyacrylamide gel electrophoresis (PAGE) of cheese samples taken after 6 months of ripening showed an extensive hydrolysis of caseins, with the fastest hydrolysis of αs1-caseins in cheeses made in August. A proteomic comparison between cheeses produced from milk taken in April, August and December showed a reduction in levels of β-casein and appearance of additional products, corresponding to low molecular weight hydrolysis products of the caseins. This study has demonstrated that a seasonal milk supply causes compositional differences in Cheddar cheese, and that proteomic tools are helpful in understanding the impact of those differences. Wed, 02 May 2012 00:00:00 GMT http://hdl.handle.net/10468/1110 2012-05-02T00:00:00Z http://hdl.handle.net/10468/844 Dynamic 5-HT2C receptor editing in a mouse model of obesity Schellekens, Harriët; Clarke, Gerard; Jeffery, Ian B.; Dinan, Timothy G.; Cryan, John F. Bartolomucci, Alessandro The central serotonergic signalling system has been shown to play an important role in appetite control and the regulation of food intake. Serotonin exerts its anorectic effects mainly through the 5-HT1B, 5-HT2C and 5-HT6 receptors and these are therefore receiving increasing attention as principal pharmacotherapeutic targets for the treatment of obesity. The 5-HT2C receptor has the distinctive ability to be modified by posttranscriptional RNA editing on 5 nucleotide positions (A, B, C, D, E), having an overall decreased receptor function. Recently, it has been shown that feeding behaviour and fat mass are altered when the 5-HT2C receptor RNA is fully edited, suggesting a potential role for 5-HT2C editing in obesity. The present studies investigate the expression of serotonin receptors involved in central regulation of food intake, appetite and energy expenditure, with particular focus on the level of 5-HT2C receptor editing. Using a leptin-deficient mouse model of obesity (ob/ob), we show increased hypothalamic 5-HT1A receptor expression as well as increased hippocampal 5-HT1A, 5-HT1B, and 5-HT6 receptor mRNA expression in obese mice compared to lean control mice. An increase in full-length 5-HT2C expression, depending on time of day, as well as differences in 5-HT2C receptor editing were found, independent of changes in total 5-HT2C receptor mRNA expression. This suggests that a dynamic regulation exists of the appetite-suppressing effects of the 5-HT2C receptor in both the hypothalamus and the hippocampus in the ob/ob mice model of obesity. The differential 5-HT1A, 5-HT1B and 5-HT6 receptor expression and altered 5-HT2C receptor editing profile reported here is poised to have important consequences for the development of novel anti-obesity therapies. Tue, 20 Mar 2012 00:00:00 GMT http://hdl.handle.net/10468/844 2012-03-20T00:00:00Z