Duodenal long noncoding RNAs are associated with glycemic control after bariatric surgery in high-fat diet-induced diabetic mice

BACKGROUND

The duodenum plays a role in the mechanism of type 2 diabetes remission after bariatric surgery. Roux-en-Y gastric bypass (RYGB) may change gene expression in the duodenum and metabolism. Long noncoding RNAs (lncRNAs) constitute a novel class of RNAs that regulate gene expression. Little is known about how duodenal lncRNAs respond to RYGB. Logically, studies on the changes of duodenal lncRNAs potentially can lead to an understanding of the mechanisms of bariatric surgery, as well as discovery of antidiabetic drug targets and biomarkers predicting postoperative outcome.

OBJECTIVES

To investigate the expression signature of duodenal lncRNAs associated with glycemic improvement by duodenal-jejunal bypass (DJB), a component of RYGB, on a genome-wide scale in high-fat diet-induced diabetic mice.

SETTING

University medical center.

METHODS

High fat diet-induced diabetic mice were randomized into 2 groups receiving either the DJB or a sham procedure. Microarray was applied to screen the differentially expressed lncRNAs and messenger RNAs (mRNAs) in the duodenum between the DJB and sham groups, and the result was validated by quantitative real-time polymerase chain reaction in another cohort of animals. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to predict the potential lncRNA functions. Based on Pearson correlation analysis, the lncRNA-mRNA and lncRNA-transcription factor (TF) interaction networks were constructed to identify and rank core regulatory lncRNAs and transcription factors.

RESULTS

A total of 301 lncRNAs, including 232 that were upregulated and 69 downregulated (fold change≥2.0), were differentially expressed in the duodenum between the DJB and sham groups. GO enrichment indicated that these lncRNA-coexpressed mRNAs were correlated with biological processes including cell proliferation, digestion, and catabolic and biosynthetic processes. KEGG pathway analysis revealed that in addition to the digestion and absorption signaling pathways, pancreatic secretion- and inflammatory process-related signaling pathways were mostly enriched in the DJB group. In addition, the lncRNA-mRNA interaction network combined with GO and KEGG pathway analysis suggested that as a top-ranked gene, NONMMUG021726 may play an important role in the mechanism of type 2 diabetes remission after DJB.

CONCLUSION

DJB leads to drastic changes in lncRNA and mRNA expressions in the duodenum. The majority of top-ranked lncRNAs and mRNAs have roles in pancreatic secretion and inflammatory processes, implying that bypass of the duodenum may initiate insulin secretion and attenuate inflammation. In addition, modulators of such lncRNAs, most likely NONMMUG021726, have potential to become therapeutic targets or biomarkers for prediction of the outcomes of bariatric surgery.

Duodenal-jejunal bypass attenuates progressive failure of pancreatic islets in streptozotocin-induced diabetic rats

BACKGROUND

Preservation of pancreatic beta cell function has been increasingly appealing in the treatment of type 2 diabetes. Evidence is still limited on how bariatric surgery affects pancreatic beta cell apoptosis.

SETTING

University medical center.

OBJECTIVE

The study aimed to investigate the effect of a major component of Roux-en-Y gastric bypass, duodenal-jejunal bypass, on protecting pancreatic beta cells from progressive loss.

METHODS

Forty-five normal Sprague-Dawley rats were randomly assigned into 3 groups: duodenal-jejunal bypass (DJB) group (n = 16) and sham (S) group (n = 17), based upon the procedure received, and a control (C) group (n = 12) without any procedure performed, to eliminate potential traumatic effects from surgery. Ten days after surgery, streptozotocin (STZ, 45 mg/kg weight) was injected intraperitoneally into each animal, including the control animals, to selectively induce pancreatic beta cell apoptosis. Weight, food intake, plasma glucose level, and the results of an oral glucose tolerance test were measured before surgery, pre-STZ injection, and up to 4 weeks after STZ injection. Plasma insulin and glucagon-like peptide-1 levels were also assayed during oral glucose tolerance test. At the end, pancreatic tissues were sliced and stained for beta cell analysis.

RESULTS

There were no significant differences in weight among all groups at any time points measured, despite rats in the S and C groups consuming more food than those in the DJB group as measured on day 10 (P<.05) and day 20 (P<.01) after STZ injection. Animals undergoing DJB did not experience symptoms typical of uncompensated diabetes, including hyperphagia and progressive weight loss. After STZ injection, fasting plasma glucose levels in the DJB group were significantly lower than those in the C and S groups (P<.001). When challenged by glucose load, DJB rats also had a better glycemic excursion (P<.01) and incretin response compared with C and S rats (P<.05). In addition, pancreatic beta cell size and mass was better preserved in DJB rats (P< .001).

CONCLUSION

DJB is able to protect pancreatic beta cells from apoptosis, which leads to better glycemic control and delayed onset of diabetes. These results imply the necessity of including a DJB component when designing bariatric procedure to achieve a better long-term outcome.