Gut bacterial translocation is correlated with stimulated TLR-4 signaling pathways in a rat model of ACS

Adam Strier, MD3, Ibrahim Matter, MD3, Izhak Srugo, MD3, Nir Bitterman, MD3, Gideon Sroka, MD3, Tatiana Dorfman, MD1, Yulia Pollak, MD2, Igor Sukhotnik, MD3. 3Bnai Zion Medical Center, Haifa, ISRAEL, 1Rambam Healthcare Campus, Haifa, ISRAEL, 2Technion-Israel Institute of Technology, Haifa, Israel.

Objective: Pneumoperitoneum is the basic step in every laparoscopic procedure, and has been established in previous studies as a trigger for bacterial translocation. Toll-like receptor 4 (TLR-4) is responsible for the recognition of bacterial endotoxin or lipopolysaccharide (LPS) and for initiation of gram-negative bacillary septic shock syndrome. Our objective was to determine the effects of elevated intaabdominal pressure (IAP) on bacterial translocation and TLR-4 signaling in a rat model of abdominal compartment syndrome (ACS).

Methods: Male Sprague-Dawley rats were randomly assigned to one of two experimental groups: control animals (CONTR) and ACS animals that were subjected to a 15 mmHg pressure pneumoperitoneum for 30 minutes. Rats were sacrificed 24 hours later. Bacterial translocation (BT) to mesenteric lymph nodes, liver, portal blood and peripheral blood were determined at sacrifice. TLR-4 related  gene and protein (TLR-4, myeloid differentiation factor 88 (Myd88) and TNF-α receptor-associated factor 6 (TRAF6)) expression were determined using Real Time PCR, Western blotting and immunohistochemistry.

Results: About 30 % of control rats exhibited BT toward the mesenteric the lymph nodes (level I),  20% toward the liver and portal blood (level II). ACS rats demonstrated a 80% BT to lymph nodes (Level I) and a 40% BT to  liver portal flow (Level II).  Elevated BT was accompanied by a significant increase in TLR-4 staining in jejunum (51%) and ileum (35.9%), as well as in a number of TRAF6 positive cells in jejunum (2.1%) and ileum (24%) compared to control animals. ACS rats demonstrated a significant increase in TLR4 and MYD88 protein levels compared to control animals.

Conclusions: 24 hours after induction of abdominal compartment in a rat model, elevated bacterial translocation rates were accompanied by a stimulation of TLR4-signaling in intestinal mucosa.

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