Old-age-induced obesity reversed by a methionine-deficient diet or oral administration of recombinant methioninase-producing Escherichia coli in C57BL/6 mice

Obesity increases with aging. Methionine restriction affects lipid metabolism and can prevent obesity in mice. In the present study we observed C57BL/6 mice to double their body weight from 4 to 48 weeks of age and become obese. We evaluated the efficacy of oral administration of recombinant-methioninase (rMETase)-producing E. coli (E. coli JM109-rMETase) or a methionine-deficient diet to reverse old-ageinduced obesity in C57BL/6 mice. Fifteen C57BL/6 male mice aged 12-18 months with old-age-induced obesity were divided into three groups. Group 1 was given a normal diet supplemented with nonrecombinant E. coli JM109 cells orally by gavage twice daily; Group 2 was given a normal diet supplemented with recombinant E. coli JM109-rMETase cells by gavage twice daily; and Group 3 was given a methioninedeficient diet without treatment. The administration of E. coli JM109-rMETase or a methionine-deficient diet reduced the blood methionine level and reversed old-age-induced obesity with significant weight loss by 14 days. There was a negative correlation between methionine levels and negative body weight change. Although the degree of efficacy was higher in the methionine-deficient diet group than in the E. coli JM109rMETase group, the present findings suggested that oral administration of E. coli JM109-rMETase, as well as a methionine-deficient diet, are effective in reversing old-age-induced obesity. In conclusion, the present study provides evidence that restricting methionine by either a low-methionine diet or E. coli JM109-rMETase has clinical potential to treat old-age-induced obesity.