Dynamic adaptive changes of the ileum transposed to the proximal small intestine in rats

Abstract

Background Ileal transposition (IT) is an experimental surgery to investigate the role of the distal ileum in Roux-en-Y gastric bypass (RYGB) surgery. To systematically investigate the dynamic adaptation process of the ileum after IT, we performed transcriptome analyses of the transposed ileum compared with the ileum in situ at different postoperative time points. Methods Sprague-Dawley rats fed a chow diet underwent IT or sham surgery. One and 4 weeks after IT or sham surgery, total RNA was extracted from the ileal tissue and subjected to transcriptome analyses using microarray. Results Principal component analysis showed that the difference between weeks 1 and 4 was the largest, and the differences between the IT and sham groups were larger in week 4 than in week 1. We identified 1792 differentially expressed genes (DEGs) between IT and sham ileal tissues, including 659 and 1133 DEGs in weeks 1 and 4, respectively. Interestingly, only 45 and 24 DEGs were commonly up- or downregulated in weeks 1 and 4, indicating a marked transition during the adaptation process. Functional enrichment and network analyses showed that structural adaptation predominantly occurred in week 1, while metabolic and immune adaptations predominantly occurred in week 4. These analyses further revealed potential components that modulate structural adaptation (e.g., extracellular matrix) in week 1 and metabolic (e.g., glucose transporter) and immune (e.g., Th17 cells) adaptations in week 4. Conclusions The transposed distal ileum underwent dynamic adaptation processes that may help explain the metabolic changes after RYGB.