Relationship between expression of triggering receptor-1 on myeloid cells in intestinal tissue and intestinal barrier dysfunction in severe acute pancreatitis

Abstract

BACKGROUND: Triggering receptor expressed on myeloid cells-1 (TREM-1) in the intestine was upregulated and correlated with disease activity in inflammatory bowel diseases. Membrane-bound TREM-1 protein is increased in the pancreas, liver and kidneys of patients with severe acute pancreatitis (SAP), suggesting that TREM-1 may act as an important mediator of inflammation and subsequent extra-pancreatic organ injury. This study aimed to investigate the relationship between the expression of TREM-1 in intestinal tissue and intestinal barrier dysfunction in SAP. METHODS: Sixty-four male Wistar rats were randomly divided into a sham operation group (SO group, n=32) and a SAP group (n=32). A SAP model was established by retrograde injection of 5% sodium deoxycholate into the bile-pancreatic duct. Specimens were taken from blood and intestinal tissue 2, 6, 12, and 48 hours after operation respectively. The levels of D-lactate, diamine oxidase (DAO) and endotoxin in serum were measured using an improved spectro-photometric method. The expression levels of TREM-1, interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha) mRNA in terminal ileum were detected by real-time reverse transcription-polymerase chain reaction (RT-PCR). Specimens of the distal ileum were taken to determine pathological changes by a validated histology score. RESULTS: The serum levels of D-lactate, DAO and endotoxin were significantly increased in each subgroup of SAP compared with the SO group (P<0.01, P<0.05). The expression levels of TREM-1, IL-1beta and TNF-alpha mRNA in the terminal ileum in each subgroup of SAP were significantly higher than those in the SO group (P<0.01, P<0.05). The expression level of TREM-1mRNA was positively correlated with IL-1beta and TNF-alpha mRNA (r=0.956, P=0.044; r=0.986, P=0.015), but the correlation was not found between IL-1beta mRNA and TNF-alpha mRNA (P=0.133). Compared to the SO group, the pathological changes were aggravated significantly in the SAP group. CONCLUSIONS: The expression level of TREM-1 in intestinal tissue of rats with SAP was elevated, leading to the release of inflammatory mediators and intestinal mucosal injury. This finding indicates that TREM-l might play an important role in the development of intestinal barrier dysfunction in rats with SAP.