(PTFS07-05-26) Regional Expression of Lipopolysaccharide-Binding Protein Across the Rat Intestinal Tract and Its Response to Antibiotics

Objectives: Lipopolysaccharide binding protein (LPS-BP) regulates lipopolysaccharide-mediated inflammation. Previously, we reported that colonic LPS-BP expression is modulated by dietary soy protein and is associated with liver inflammation and metabolic dysfunction-associated steatotic liver disease (MASLD). The objective of this study was to characterize the regional expression of LPS-BP along the intestine and its response to antibiotic treatment.

Methods: Twelve female Sprague-Dawley rats were purchased from Charles River Laboratories and maintained on standard chow. At 15 weeks of age, rats were randomly assigned to a control group (n = 6) or an antibiotic-treated group (n = 6) that received either regular water or water containing 1% ampicillin and 0.5% vancomycin for 7 days. At the end of treatment, rats were anesthetized and killed by decapitation. One-centimeter intestinal segments were collected from the duodenum, jejunum, ileum, proximal colon, middle colon, and distal colon. LPS-BP expression was determined by TaqMan quantitative PCR (qPCR) and normalized to 18S rRNA. Data were analyzed by two-way ANOVA followed by Tukey’s multiple comparison test. The University of Arkansas for Medical Sciences/Arkansas Children’s Research Institute Institutional Animal Care and Use Committee approved the animal care protocol and procedures.

Results: In both control and antibiotic-treated groups, LPS-BP expression progressively increased from the proximal intestine (i.e. duodenum) to the distal intestine (i.e. distal colon). Overall, LBP expression was significantly higher in the colon than in the small intestine, and higher in the middle and distal colon than in the proximal colon. Antibiotic treatment did not alter LBP expression in any segment of the small intestine. In contrast, antibiotics significantly increased LBP expression in the proximal colon, middle colon, and distal colon compared with controls (p = 0.02, 0.005, and 0.004, respectively).

Conclusions: LBP expression exhibits a proximal-to-distal gradient along the intestine and may be modulated by the intestinal microbiota.

Funding Sources: This project was supported by a UAMS intramural seed grant to WL.