The Effect of Gut Bacterial β‐Glucuronidase on Serum Bilirubin Levels

Abstract

The results of several large population studies have consistently demonstrated an inverse correlation between serum bilirubin levels and the development of cardiovascular and metabolic diseases. The goal of this study was to test the hypothesis that increased bacterial β‐Glucuronidase (β‐glu) activity can increase the levels of serum bilirubin by decreasing conjugation of bilirubin in the gut. Two strains of Lactobacillus acidophilus with different levels of β‐glu activity, NCK 56 (control) and NCK 2136 (constitutive overexpression), were grown and administered to mice once per day for five days. Each mouse was then administered 2 mL of fluid containing 500 million cells/ml via gastric gavage. Plasma samples were obtained prior to and after treatment. Serum bilirubin levels were measured using a specific assay kit via absorption at 700 nm. Serum bilirubin levels were similar in both groups prior to treatment averaging 2.3 +0.1 and 2.1 + 0.2 mg/dL in 56 and 2136 treated mice, respectively (n=3/group, p=0.8). Five day treatment of mice with control 56 L. acidophilus resulted in a significant decrease in serum bilirubin levels to 1.7 + 0.5 mg/dL (p<0.05), while treatment with β‐glu overexpressing L. acidophilus did not change serum bilirubin levels which averaged 2.3 + 0.3 mg/dL. Our results demonstrate that β‐Glu expression by modified L. acidophilus prevented the decrease in bilirubin that is seen upon administration of the control L. acidophilus bacterial strain. Overexpression β‐glu in a different host bacteria species with less reducing activity may provide a way to elevate serum bilirubin levels.Support or Funding InformationHearin Support Foundation, Medical Student Research Program, University of Mississippi Medical Center School of Medicine. National Heart, Lung, and Blood Institute, IP01HL‐051971. National Institute of General Medical Sciences, P20GM‐104357.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.