Real-time imaging of intestinal bacterial ?-glucuronidase activity by hydrolysis of a fluorescent probe.

ABSTRACT: Intestinal bacterial ?-glucuronidase (?G) hydrolyzes glucuronidated metabolites to their toxic form in intestines, resulting in intestinal damage. The development of a method to inhibit ?G is thus important but has been limited by the difficulty of directly assessing enzyme activity in live animals. Here, we utilized a fluorescent probe, fluorescein di-?-D-glucuronide (FDGlcU), to non-invasively image the intestinal bacterial ?G activity in nude mice. In vitro cell-based assays showed that the detection limit is 10⁴ colony-forming units/well of ?G-expressing bacteria, and that 7.81 ng/mL of FDGlcU is enough to generate significant fluorescent signal. In whole-body optical images of nude mice, the maximum fluorescence signal for ?G activity in intestines was detected 3?hours after gavage with FDGlcU. Following pretreatment with a bacterial ?G inhibitor, the fluorescence signal was significantly reduced in abdomens and excised intestines images. For a 4-day antibiotic treatment to deplete intestinal bacteria, the FDGlcU-based images showed that the ?G activity was decreased by 8.5-fold on day 4 and then gradually increased after treatment stopped. The results suggested that FDGlcU-based imaging revealed the in vitro and in vivo activity of intestinal bacterial ?G, which would facilitate pharmacodynamic studies of specific bacterial ?G inhibitors in animal studies.

SUBMITTER: Chen M 

PROVIDER: S-EPMC5466677 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature