title: Microbially produced glucagon-like peptide 1 improves glucose tolerance in mice.
abstract: OBJECTIVE
  The enteroendocrine hormone glucagon-like peptide 1 (GLP-1) is an attractive anti-diabetic therapy. Here, we generated a recombinant Lactococcus lactis strain genetically modified to produce GLP-1 and investigated its ability to improve glucose tolerance in mice on chow or high-fat diet (HFD).
  
  
  METHODS
  We transformed L. lactis FI5876 with either empty vector (pUK200) or murine GLP-1 expression vector to generate LL-UK200 and LL-GLP1, respectively, and determined their potential to induce insulin secretion by incubating primary islets from wild-type (WT) and GLP-1 receptor knockout (GLP1R-KO) mice with culture supernatant of these strains. In addition, we administered these strains to mice on chow or HFD. At the end of the study period, we measured plasma GLP-1 levels, performed intraperitoneal glucose tolerance and insulin tolerance tests, and determined hepatic expression of the gluconeogenic genes G6pc and Pepck.
  
  
  RESULTS
  Insulin release from primary islets of WT but not GLP1R-KO mice was higher following incubation with culture supernatant from LL-GLP1 compared with LL-UK200. In mice on chow, supplementation with LL-GLP1 versus LL-UK200 promoted increased vena porta levels of GLP-1 in both WT and GLP1R-KO mice; however, LL-GLP1 promoted improved glucose tolerance in WT but not in GLP1R-KO mice, indicating a requirement for the GLP-1 receptor. In mice on HFD and thus with impaired glucose tolerance, supplementation with LL-GLP1 versus LL-UK200 promoted a pronounced improvement in glucose tolerance together with increased insulin levels. Supplementation with LL-GLP1 versus LL-UK200 did not affect insulin tolerance but resulted in reduced expression of G6pc in both chow and HFD-fed mice.
  
  
  CONCLUSIONS
  The L. lactis strain genetically modified to produce GLP-1 is capable of stimulating insulin secretion from islets and improving glucose tolerance in mice.
authors.affiliation: Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Tulika
authors.initials: T
authors.lastname: Arora
authors.affiliation: Gut Health and Food Safety Programme, Institute of Food Research, Norwich NR4 7UA, UK.
authors.forename: Udo
authors.initials: U
authors.lastname: Wegmann
authors.affiliation: Gut Health and Food Safety Programme, Institute of Food Research, Norwich NR4 7UA, UK.
authors.forename: Anup
authors.initials: A
authors.lastname: Bobhate
authors.affiliation: Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Ying Shiuan
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Thomas U
authors.initials: TU
authors.lastname: Greiner
authors.affiliation: Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Drucker
authors.affiliation: Gut Health and Food Safety Programme, Institute of Food Research, Norwich NR4 7UA, UK.
authors.forename: Arjan
authors.initials: A
authors.lastname: Narbad
authors.affiliation: Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden; Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: Fredrik.Backhed@wlab.gu.se.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Bäckhed
keywords: DPP4, Dipeptidyl peptidase 4; G-KRB, glucose-Krebs ringer buffer; G6pc, glucose 6 phosphatase, catalytic subunit; GLP-1; GLP-1, Glucagon-like peptide 1; GLP1R-KO, GLP-1 receptor knock out; Glucose tolerance; HFD, high fat diet; IPGTT, Intraperitoneal glucose tolerance test; ITT, Insulin tolerance test; LL-GLP1, GLP-1 producing recombinant strain; LL-UK200, Control vector only strain; Lactococcus lactis; Pepck, phosphoenolpyruvate carboxykinase; Recombinant bacteria; WT, Wild type; cfu, Colony forming unit