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Effect of bile pigments on the compromised gut barrier function in a rat model of bile duct ligation.

Zhou K, Jiang M, Liu Y, Qu Y, Shi G, Yang X, Qin X, Wang X - PLoS ONE (2014)

Bottom Line: Trypsin and chymotrypsin of the gut were also measured to determine how these digestive proteases may relate to the observed effects of bile pigments.Free bilirubin but not bilirubin ditaurate or biliverdin showed significant inhibitions on trypsin and chymotrypsin as well as alleviated changes of histological and biochemical parameters related to gut barrier disruption.Bile may protect the gut from damage through inhibiting digestive proteases like trypsin and chymotrypsin by free bilirubin.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.

ABSTRACT

Background: Studies have shown that the absence of bile in the gut lumen, either by bile duct ligation or bile diversion, induces mucosal injury. However, the mechanism remains elusive. In this study, the role of bile pigments in gut barrier function was investigated in a rat model of bile duct ligation.

Methods: Male Sprague Dawley (SD) rats were used in this study. After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. 1, 2, or 3 days later, the animals were sacrificed and the damage of mucosa was assessed by histological staining as well as biochemical parameters such as changes of diamine oxidase (DAO) and D-lactate (D-Lac) in the blood. Trypsin and chymotrypsin of the gut were also measured to determine how these digestive proteases may relate to the observed effects of bile pigments.

Results: Bile duct ligation (BDL) caused significant increases in gut trypsin and chymotrypsin along with damage of the mucosa as demonstrated by the histological findings under microscope, the reduced expression of tight junction molecules like occludin, and significant changes in DAO and D-lac in the blood. Free bilirubin but not bilirubin ditaurate or biliverdin showed significant inhibitions on trypsin and chymotrypsin as well as alleviated changes of histological and biochemical parameters related to gut barrier disruption.

Conclusion: Bile may protect the gut from damage through inhibiting digestive proteases like trypsin and chymotrypsin by free bilirubin.

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Related in: MedlinePlus

Effect of 0.1 mM bile pigments on the compromised gut barrier function.After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. The serum concentrations of DAO (A) and D-Lac (B) were assayed by spectrophotometric assay after 48 h. Protein expression of occludin (65 kDa) was analyzed by Western blot (C). Occludin bands were normalized by GAPDH and expressed as relative to BDL 48 h group (D). Intestinal slices were stained with HE staining and analyzed by inverted fluorescence microscope, middle small intestine were blindly assessed for the degree of histopathology (E), all photos were captured at ×40 magnification (F). Results are mean ± SD from at least three independent experiments. *p<0.05, **p<0.01 ***p<0.001 vs. respective BDL 48 h group.
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pone-0098905-g005: Effect of 0.1 mM bile pigments on the compromised gut barrier function.After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. The serum concentrations of DAO (A) and D-Lac (B) were assayed by spectrophotometric assay after 48 h. Protein expression of occludin (65 kDa) was analyzed by Western blot (C). Occludin bands were normalized by GAPDH and expressed as relative to BDL 48 h group (D). Intestinal slices were stained with HE staining and analyzed by inverted fluorescence microscope, middle small intestine were blindly assessed for the degree of histopathology (E), all photos were captured at ×40 magnification (F). Results are mean ± SD from at least three independent experiments. *p<0.05, **p<0.01 ***p<0.001 vs. respective BDL 48 h group.

Mentions: After intragastric administration of UCB, bilirubin ditaurate and biliverdin, UCB administration group showed a significantly lower damage. DAO concentrations in UCB administration group reduced by 14.2%, p<0.01, while the serum concentrations of DAO in bilirubin ditaurate and biliverdin groups attained 7% and 11.7% increase, respectively (Figure 5A). In addition, the serum concentration of D-Lac in UCB administration group reduced by 8.2%, p<0.001. D-Lac levels in biliverdin administration group attained 3.6% increase, while no significant changes were observed in bilirubin ditaurate group (Figure 5B). As seen in Fig. 5C and Fig. 5D, the intestinal mucosa showed enhanced expression of occludin in UCB administration group only, as compared to BDL 48 h group (increase of 25.8%, p<0.05). At 48 h of BDL, the middle small intestine tissue pathology was significantly more severe compared to control group, with further aggravation and significantly more severely inflamed in 0.1 mM biliverdin treatment group (Figure 5E and 5F). The UCB treated group showed a remarkable decrease in intestinal histopathological score than BDL group. From this figure, we can see that 0.1 mM UCB but not bilirubin ditaurate or biliverdin displayed the protective effect on intestinal mucosa.


Effect of bile pigments on the compromised gut barrier function in a rat model of bile duct ligation.

Zhou K, Jiang M, Liu Y, Qu Y, Shi G, Yang X, Qin X, Wang X - PLoS ONE (2014)

Effect of 0.1 mM bile pigments on the compromised gut barrier function.After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. The serum concentrations of DAO (A) and D-Lac (B) were assayed by spectrophotometric assay after 48 h. Protein expression of occludin (65 kDa) was analyzed by Western blot (C). Occludin bands were normalized by GAPDH and expressed as relative to BDL 48 h group (D). Intestinal slices were stained with HE staining and analyzed by inverted fluorescence microscope, middle small intestine were blindly assessed for the degree of histopathology (E), all photos were captured at ×40 magnification (F). Results are mean ± SD from at least three independent experiments. *p<0.05, **p<0.01 ***p<0.001 vs. respective BDL 48 h group.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4044053&req=5

pone-0098905-g005: Effect of 0.1 mM bile pigments on the compromised gut barrier function.After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. The serum concentrations of DAO (A) and D-Lac (B) were assayed by spectrophotometric assay after 48 h. Protein expression of occludin (65 kDa) was analyzed by Western blot (C). Occludin bands were normalized by GAPDH and expressed as relative to BDL 48 h group (D). Intestinal slices were stained with HE staining and analyzed by inverted fluorescence microscope, middle small intestine were blindly assessed for the degree of histopathology (E), all photos were captured at ×40 magnification (F). Results are mean ± SD from at least three independent experiments. *p<0.05, **p<0.01 ***p<0.001 vs. respective BDL 48 h group.
Mentions: After intragastric administration of UCB, bilirubin ditaurate and biliverdin, UCB administration group showed a significantly lower damage. DAO concentrations in UCB administration group reduced by 14.2%, p<0.01, while the serum concentrations of DAO in bilirubin ditaurate and biliverdin groups attained 7% and 11.7% increase, respectively (Figure 5A). In addition, the serum concentration of D-Lac in UCB administration group reduced by 8.2%, p<0.001. D-Lac levels in biliverdin administration group attained 3.6% increase, while no significant changes were observed in bilirubin ditaurate group (Figure 5B). As seen in Fig. 5C and Fig. 5D, the intestinal mucosa showed enhanced expression of occludin in UCB administration group only, as compared to BDL 48 h group (increase of 25.8%, p<0.05). At 48 h of BDL, the middle small intestine tissue pathology was significantly more severe compared to control group, with further aggravation and significantly more severely inflamed in 0.1 mM biliverdin treatment group (Figure 5E and 5F). The UCB treated group showed a remarkable decrease in intestinal histopathological score than BDL group. From this figure, we can see that 0.1 mM UCB but not bilirubin ditaurate or biliverdin displayed the protective effect on intestinal mucosa.

Bottom Line: Trypsin and chymotrypsin of the gut were also measured to determine how these digestive proteases may relate to the observed effects of bile pigments.Free bilirubin but not bilirubin ditaurate or biliverdin showed significant inhibitions on trypsin and chymotrypsin as well as alleviated changes of histological and biochemical parameters related to gut barrier disruption.Bile may protect the gut from damage through inhibiting digestive proteases like trypsin and chymotrypsin by free bilirubin.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Heilongjiang Provincial Science and Technology Innovation Team in Higher Education Institutes for Infection and Immunity, Harbin Medical University, Harbin, China.

ABSTRACT

Background: Studies have shown that the absence of bile in the gut lumen, either by bile duct ligation or bile diversion, induces mucosal injury. However, the mechanism remains elusive. In this study, the role of bile pigments in gut barrier function was investigated in a rat model of bile duct ligation.

Methods: Male Sprague Dawley (SD) rats were used in this study. After ligation of bile duct, the animals were administrated with free bilirubin, bilirubin ditaurate, or biliverdin by intragastric gavage. 1, 2, or 3 days later, the animals were sacrificed and the damage of mucosa was assessed by histological staining as well as biochemical parameters such as changes of diamine oxidase (DAO) and D-lactate (D-Lac) in the blood. Trypsin and chymotrypsin of the gut were also measured to determine how these digestive proteases may relate to the observed effects of bile pigments.

Results: Bile duct ligation (BDL) caused significant increases in gut trypsin and chymotrypsin along with damage of the mucosa as demonstrated by the histological findings under microscope, the reduced expression of tight junction molecules like occludin, and significant changes in DAO and D-lac in the blood. Free bilirubin but not bilirubin ditaurate or biliverdin showed significant inhibitions on trypsin and chymotrypsin as well as alleviated changes of histological and biochemical parameters related to gut barrier disruption.

Conclusion: Bile may protect the gut from damage through inhibiting digestive proteases like trypsin and chymotrypsin by free bilirubin.

Show MeSH
Related in: MedlinePlus