目的:肠内分泌激素胰高血糖素样肽1(GLP-1)是一种有吸引力的抗糖尿病药物。这里,我们产生了重组乳酸乳球菌菌株,该菌株经过基因修饰以产生GLP-1,并研究了其改善饮食或高脂饮食(HFD)小鼠糖耐量的能力.
方法:我们用空载体(pUK200)或鼠GLP-1表达载体转化乳酸乳球菌FI5876,分别产生LL-UK200和LL-GLP1,并通过将野生型(WT)和GLP-1受体敲除(GLP1R-KO)小鼠的原代胰岛与这些菌株的培养上清液一起孵育来确定其诱导胰岛素分泌的潜力。此外,我们将这些菌株施用于chow或HFD的小鼠。在研究期结束时,我们测量了血浆GLP-1水平,进行腹膜内葡萄糖耐量和胰岛素耐量试验,并确定糖异生基因G6pc和Pepck的肝表达。
结果:与LL-UK200相比,用LL-GLP1培养上清液孵育后,WT而非GLP1R-KO小鼠原代胰岛的胰岛素释放更高。在老鼠身上,补充LL-GLP1与LL-UK200促进WT和GLP1R-KO小鼠的GLP-1水平增加;然而,LL-GLP1在WT中促进葡萄糖耐量的改善,但在GLP1R-KO小鼠中没有,表明对GLP-1受体的要求。在HFD的小鼠中,因此葡萄糖耐量受损,补充LL-GLP1与LL-UK200相比,促进了葡萄糖耐量的显着改善以及胰岛素水平的增加。补充LL-GLP1与LL-UK200并不影响胰岛素耐受性,但导致饮食和HFD喂养的小鼠中G6pc的表达降低。
结论:经基因修饰以产生GLP-1的乳酸乳球菌菌株能够刺激胰岛分泌胰岛素并改善小鼠的葡萄糖耐量。
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.