B. Aladegbami1, Y. Xie2, J. Guo1, C. Erwin1, N. Davidson2, B. Warner1 1Washington University,Pediatric Surgery,St. Louis, MO, USA 2Washington University,Gastroenterology,St. Louis, MO, USA
Introduction: Following massive small bowel resection (SBR), an important adaptive process occurs that is characterized by increased enterocyte proliferation, increased vessel density and an expanded mucosal surface area. CXCL5 is a proangiogenic chemokine and CXCL5 Knock out mice (CXCL5-KO) undergo normal structural adaptation but have impaired angiogenesis and a perturbed profile of intestinal absorption. The goal of this study was to further characterize the role of CXCL5 in intestinal triglyceride absorption and to understand its effect on body composition and metabolism.
Methods: CXCL5 knockout mice and C57BL/6 wild type (WT) mice were subjected to 50% proximal small bowel resection (N= 10 and 7, respectively). On post-operative day 14 (POD14) Pluronic F127 was injected via tail vein and mice were then gavaged enterally with mixture of 20 % intralipid, corn oil and radioactive 3[H]-triolein in order to measure triglyceride (TG) absorption. Serum was collected at 1, 2 and 3 hours’ time point and remnant intestine was sectioned into 9 equal segments for analysis. Indirect calorimetry was used to measure metabolic activity and body composition determined by MRI.
Result: CXCL5-KO mice showed a decreased level of radiation (TG absorption) in the serum at the 1 (CXCL5-KO: 5482.5±1407.1; WT: 15481±4351.6, p =0.03) and 2 (CXCL5-KO: 8964.7±1118.6; WT: 16413±1126.8 p =0.01) hours’ time point. Total TG increased 57 fold in WT at 3 hours, but only 37 fold in CXCL5-KO (p=0.015). In addition, CXCL5-KO mice showed a non-significant but higher level of radiolabeled TG in the intestine when compared to WT (Area under the curve CXCL5-KO: 0.35; WT: 0.11, p =0.07 (NS)). These findings are all consistent with a delayed TG absorption profile and a compensatory increase in production by the Liver.
CXCL5-KO mice had no difference in respiratory exchange ratio, locomotion, and body composition when compared to WT both pre- and postoperatively. However there was a consistent decrease in respiratory exchange ratio, locomotion and lean body mass in all post-surgical mice when compared to their pre-operative levels.
Conclusion: Our results suggest a potential function of CXCL5 and/or angiogenesis in the regulation intestinal triglyceride absorption. However, this effect does not translate to a difference in whole body metabolism and body composition in the early postoperative period.