The glucagon-like peptide 2 receptor is expressed in enteric neurons and not in the epithelium of the intestine

Abstracts

pituitary is caused by impairment of glucocorticoid-induced miR449a expression in LBW. doi:10.1016/j.regpep.2012.05.060

Transforming growth factor beta 2 (TGF-β2) effects on lipopolysaccharide (LPS)-induced cytokine secretion in developing intestinal epithelial cells PsIc1 D.N. Nguyena, M.V. Østergaardb, P.T. Sangildb, S.B. Beringb, D. Chattertona a Dairy Technology Group, Department of Food Science, Faculty of Science, University of Copenhagen, Denmark b Department of Human Nutrition, Faculty of Science, University of Copenhagen, Denmark Introduction: TGF-β2 is present in milk and potentially has antiinflammatory effects on the infant intestine by suppressing inflammatory cytokine secretion. It is of interest to enrich infant formulas with TGF-β2 to prevent bacteria-induced inflammatory intestinal disorders. Aims: We investigated TGF-β2 effects on phosphorylation of intracellular SMAD2 (p-SMAD2) and on lipopolysaccharide (LPS)induced pro-inflammatory cytokine secretion (IL-8, IL-6, IL-1β and TNF-α) in the pig intestinal cells PsIc1. Methods: Cells were stimulated with 3–10 ng/ml TGF-β2 for 0– 120 min and lysates were analyzed by Western Immunoblotting for p-SMAD2. For cytokine analyses, cells were conditioned with or without 3 ng/ml TGF-β2 for 48 h before treatments with LPS (0.1– 1 μg/ml) and/or TGF-β2 (3 ng/ml) for another 24 h before analysing supernatants by ELISA. Results: TGF-β2 stimulation increased p-SMAD2 levels, especially at 10 ng/mL TGF-β2 for 1 h. Moreover, TGF-β2 concentration similar to that in breast milk significantly increased LPS-induced IL-8 release while it attenuated IL-1β, TNF-α and IL-6 secretion. 48 h preincubation with TGF-β2 further augmented corresponding IL-8 values and lowered corresponding values of IL-1β and TNF-α, compared to no pre-incubation. Discussion: Signaling data indicate that PsIc1 cells express TGF-β receptors and that TGF-β2 stimulation causes intracellular signaling via SMAD2. Attenuation of IL-6, TNF-α and IL-1β reflects possible anti-inflammatory effects of TGF-β2. Conversely, the IL-8 increase suggests that this cytokine may have other functions rather than proinflammatory roles in PsIc1 cells. Our data confirm that TGF-β2 has potent immuno-regulatory effects in PsIc1 cells that may partially explain the important intestinal bioactivity of natural milk. doi:10.1016/j.regpep.2012.05.061

Although the fatty-acid receptor GPR120 is upregulated in DIO rats and widely expressed in the gut it does not appear to play a key role in the regulation of GLP-1 secretion S. Paulsena, L.K. Larsena, G. Hansena, S. Chelurb, P.J. Larsena, N. Vranga a Rheoscience A/S, Glerupvej 2, DK-2610 Rødovre, Denmark b Aurigene, Bangalore, India Introduction: The G-protein coupled receptor GPR120 is a receptor for long chain fatty acids such as alpha-linolenic acid (ALA). GPR120 receptors stimulation has been shown to include antiinflammatory and insulin-sensitizing effects, to promote glucagon like peptide-1 (GLP-1) secretion, and to play a key role in sensing dietary fat and control energy balance. Aims: We have characterized the expression of GPR120 in the intestine of selectively bred diet induced obese (DIO) and diet

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resistant (DR) rat. Furthermore, we attempted to validate reports of an ALA-dependent release of GLP-1. Methods: For semi-quantitative measures of gene expression and anatomical expression of GPR120 in the rat intestine multiplex PCR and single + double in situ hybridization using riboprobes were performed. To assess the acute effect of ALA on plasma levels of insulin and GLP-1 oral fatty acid tolerance tests were performed on DIO, DR and Sprague Dawley rats. Results: We demonstrated two-fold higher (diet independent) GPR120 mRNA expression in the intestine of DIO-rats compared to DR-rats. In a series of experiments we were unable to detect ALA induced GLP-1 secretion. The anatomical expression of GPR120 showed widely expression of GPR120 by intestinal epithelial cells in both the ileum and colon, but GPR120 expression was not enriched in preproglucagon expressing L-cells. Discussion: Our data indicates that GPR120 does not play a major role in the regulation of GLP-1 secretion from intestinal L-cells. The upregulation in fat tissue and widespread expression in the gut indicates a more general role for GPR120 as a lipid sensor. doi:10.1016/j.regpep.2012.05.062

The glucagon-like peptide 2 receptor is expressed in enteric neurons and not in the epithelium of the intestine N.B. Pedersena,1, J. Pedersena,1, S.W. Brixa, B. Hartmanna, B.L. Petersenb, C. Ørskova, S.S. Poulsena, J.J. Holsta a Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark b Department of Pathology, National University Hospital of Copenhagen, DK-2100 Copenhagen, Denmark 1 Both authors contributed equally to the work. Introduction: Glucagon-like peptide 2 (GLP-2) is a potent intestinotrophic growth factor that has therapeutic potential in the treatment of inflammatory bowel disease and currently is evaluated for the treatment of short bowel syndrome. The effects of GLP-2 are mediated by specific binding to the GLP-2 receptor (GLP-2R) which was cloned more than a decade ago. However, no consensus about the exact receptor localization in the intestine has ever been established. Aims: To establish the quantitative distribution of GLP-2R in the different structures of rat jejunum. Methods and results: By physical tissue fragmentation, we were able to divide gut sections into different compartments consisting of 1) Epithelium alone, 2) Mucosa with lamina propria and epithelium, 3) The external muscle coat including Auerbach's plexus, 4) A compartment enriched for myenteric plexus and 5) Intestine without epithelium (verified by microscopy). Expression of chromogranin A; tubulin, beta 3; actin, gamma 2, smooth muscle, enteric; glial fibrillary acidic protein and Glp2r in these isolated tissue fractions was quantified with qRT-PCR. Expression of the Glp2r was confined to compartments containing enteric neurons and receptor expression was absent in the epithelium. The localization of the receptor was further visualized by immunohistochemistry. Discussion: Our findings provide evidence for the expression and localization of the GLP-2R on enteric neurons and, further they exclude the possibility of receptor expression in the epithelium of rat jejunal mucosa. doi:10.1016/j.regpep.2012.05.063

Reduced incretin effect in truncally vagotomized subjects A. Plamboecka,b, S. Veedfalda,c, C.F. Deaconb, A. Wettergrenc, L.B. Svendsenc, S. Meisnerd, C. Hovendale, J.J. Holstb, F. Knopa, T. Vilsbølla