Pharmacologic targeting of bacterial β-glucuronidase alleviates nonsteroidal anti-inflammatory drug-induced enteropathy in mice.
Small intestinal mucosal injury is a frequent adverse effect caused by nonsteroidal anti-inflammatory drugs (NSAIDs). The underlying mechanisms are not completely understood, but topical (luminal) effects have been implicated. Many carboxylic acid-containing NSAIDs, including diclofenac (DCF), are metabolized to acyl glucuronides (AGs), and/or ether glucuronides after ring hydroxylation, and exported into the biliary tree. In the gut, these conjugates are cleaved by bacterial β-glucuronidase, releasing the potentially harmful aglycone. We first confirmed that DCF-AG was an excellent substrate for purified Escherichia coli β-D-glucuronidase. Using a previously characterized novel bacteria-specific β-glucuronidase inhibitor (Inhibitor-1), we then found that the enzymatic hydrolysis of DCF-AG in vitro was inhibited concentration dependently (IC₅₀ ∼164 nM). We next hypothesized that pharmacologic inhibition of bacterial β-glucuronidase would reduce exposure of enterocytes to the aglycone and, as a result, alleviate enteropathy. C57BL/6J mice were administered an ulcerogenic dose of DCF (60 mg/kg i.p.) with or without oral pretreatment with Inhibitor-1 (10 μg per mouse, b.i.d.). Whereas DCF alone caused the formation of numerous large ulcers in the distal parts of the small intestine and increased (2-fold) the intestinal permeability to fluorescein isothiocyanate-dextran, Inhibitor-1 cotreatment significantly alleviated mucosal injury and reduced all parameters of enteropathy. Pharmacokinetic profiling of DCF plasma levels in mice revealed that Inhibitor-1 coadministration did not significantly alter the C(max), half-life, or area under the plasma concentration versus time curve of DCF. Thus, highly selective pharmacologic targeting of luminal bacterial β-D-glucuronidase by a novel class of small-molecule inhibitors protects against DCF-induced enteropathy without altering systemic drug exposure.
Department of Pharmaceutical Sciences, University of Connecticut School of Pharmacy, Storrs, Connecticut, USA.
Amanda
A
LoGuidice
Bret D
BD
Wallace
Lauren
L
Bendel
Matthew R
MR
Redinbo
Urs A
UA
Boelsterli
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics / Q000633:toxicity*; D004008:Diclofenac / Q000493:pharmacokinetics / Q000633:toxicity*; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D005966:Glucuronidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006023:Glycoproteins / Q000494:pharmacology; D007410:Intestinal Diseases / Q000139:chemically induced* / Q000201:enzymology* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D014456:Ulcer / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D029968:Escherichia coli Proteins; D006023:Glycoproteins; C011473:beta-glucuronidase inhibitor; D004008:Diclofenac; D005966:Glucuronidase