Genetically Engineered Escherichia coli Nissle 1917 Synbiotics Reduce Metabolic Effects Induced by Chronic Consumption of Dietary Fructose

Abstract

Aims: To assess protective efficacy of genetically modified Escherichia coli Nissle 1917 (EcN) on metabolic effects induced by chronic consumption of dietary fructose.

Materials and methods: EcN was genetically modified with fructose dehydrogenase (fdh) gene for conversion of fructose to 5-keto-D-fructose and mannitol-2-dehydrogenase (mtlK) gene for conversion to mannitol, a prebiotic. Charles foster rats weighing 150-200 g were fed with 20% fructose in drinking water for two months. Probiotic treatment of EcN (pqq), EcN (pqq-glf-mtlK), EcN (pqq-fdh) was given once per week 109 cells for two months. Furthermore, blood and liver parameters for oxidative stress, dyslipidemia and hyperglycemia were estimated. Fecal samples were collected to determine the production of short chain fatty acids and pyrroloquinoline quinone (PQQ) production.

Results: EcN (pqq-glf-mtlK), EcN (pqq-fdh) transformants were confirmed by restriction digestion and functionality was checked by PQQ estimation and HPLC analysis. There was significant increase in body weight, serum glucose, liver injury markers, lipid profile in serum and liver, and decrease in antioxidant enzyme activity in high-fructose-fed rats. However the rats treated with EcN (pqq-glf-mtlK) and EcN (pqq-fdh) showed significant reduction in lipid peroxidation along with increase in serum and hepatic antioxidant enzyme activities. Restoration of liver injury marker enzymes was also seen. Increase in short chain fatty acids (SCFA) demonstrated the prebiotic effects of mannitol and gluconic acid.

Conclusions: Our study demonstrated the effectiveness of probiotic EcN producing PQQ and fructose metabolizing enzymes against the fructose induced hepatic steatosis suggesting that its potential for use in treating fructose induced metabolic syndrome.

Fig 1. Effect of probiotic treatment on liver enzyme tests.

(A) ALP (B) AST (C) ALT activity and kidney function tests (D) Urea (E) Creatinine of serum. Values are expressed as mean ± SEM (n = 5–6 each group). ***P≤ 0.001 compared with fructose control, ^@@@P ≤ 0.001 compared to fructose control, ^$ $ $ P ≤ 0.001, ^$ $ P ≤ 0.01 compared to EcN (pqq) group. F: Fructose.

Fig 2. Effect of probiotic treatment on serum lipid profile.

(A) LDL, (B) HDL, (C) VLDL, (D) Cholesterol and (E) Triglycerides; on hepatic lipid profile (F) Cholesterol and (G) Triglycerides; (H) mRNA of Fatty acid synthase and (I) mRNA of Acyl Coenzyme A oxidase. Values are expressed as mean ± SEM (n = 5–6 each group). ***P≤ 0.001 compared with fructose control, ^@@@P ≤ 0.001 compared to fructose control, ^$ $ $ P ≤ 0.001, ^$ $ P ≤ 0.01 compared to EcN (pqq) group, ^### ≤ 0.001. Values are expressed in mg/dl. F: Fructose.

Fig 3

Effect of probiotic treatment on antioxidant status of liver (A), (B) and (C) and blood (D), (E) and (F) in rats. (A and D) Lipid peroxidation (LPO), (B and E) Catalase and (C and F) SOD. Values are expressed as mean ± SEM (n = 5–6 each group). ***P≤ 0.001 compared with fructose control, ^@@@P ≤ 0.001 compared to fructose control, $ $ $ P ≤ 0.001, ^$ $ P ≤ 0.01 compared to EcN (pqq) group. F: Fructose.