The Impact Of Laparoscopy And Laparotomy On NOD1 And NOD2 Signaling Pathways In Children With Appendicitis

Objective: The stress response caused by surgery can lead to damaged immune function, increased susceptibility to pathogenic microorganisms, and rising incidence of postoperative complications and death rate correspondingly. However, further research is required for the exact mechanism of surgical stress. NOD1 and NOD2 are a class of newly-discovered pattern recognition molecules, which play an important role in the innate immune response against intracellular bacteria. This study aims to discuss the effects of stress response caused by different kinds of surgery on NOD1 and NOD2 mediated innate immune response by comparing the changes in NOD1 and NOD2 expression and function at different time points of laparoscopy and laparotomy in children with appendicitis.Methods: 30 children diagnosed with acute appendicitis in general surgery of Suzhou Children’s Hospital Affiliated to Suzhou University between September 2014 and March 2015 were selected and randomly assigned to the laparoscopic appendicectomy(LA) group and the open appendicectomy(OA) group. Peripheral blood samples of 2ml were collected from all patients before, after and at Day 1 after appendectomy. NOD1 and NOD2 gene expressions in peripheral blood mononuclear cells(PBMCs) at each time point were quantified with Real-time PCR. Cytokine(including TNF-ɑ and IL-6) responses of whole blood to NOD1 and NOD2-specific agonists including Tri-DAP and MDP were assessed with ELISA kit. Moreover, the intracellular signaling pathways were examined by Western blotting.Results:1. In group LA, NOD1 and NOD2 did not change much postoperatively. NOD1 levels increased at Day 1 postoperatively. However, in group OA, NOD1 levels significantly decreased postoperatively(P<0.01)and recovered at Day 1 postoperatively. In group LA and group OA, NOD2 did not change much at different time points.2. In group LA and group OA, TNF-ɑ and IL-6 were expressed in blood samples after Tri-DAP and MDP stimulation. Upon Tri-DAP stimulation, the production of TNF-ɑ in group OA decreased postoperatively, and recovered at Day 1 postoperatively. However, there were no significant differences at different time points postoperatively in group LA. There were no significant differences in the production of IL-6 after Tri-DAP and MDP stimulation at different time points between group LA and group OA.3. In group LA, there were no significant changes in the activated degree of NOD1 and NOD2 signaling pathways after Tri-DAP and MDP stimulation at different time points. However, upon Tri-DAP and MDP stimulation, the phosphorylation of RIP2 significantly decreased at postoperative points in group OA.Conclusion: 1. Surgery-related stress response may decrease NOD1 expression levels, but has no effect on NOD2. In contrast to open surgery, laparoscopy surgery can obviously alleviate the stress response of the expression of NOD1.2. Surgery-related stress response can decrease NOD1 induced production of TNF-ɑ, but has no effect on IL-6. In contrast to open surgery, laparoscopy surgery can obviously reduce the effect of surgery-related stress on NOD1 mediated production of TNF-ɑ. Surgery-related stress has no effect on NOD2 mediated cytokine response.3. Open appendectomy can inhibit the activation of NOD1/NOD2/RIP2 signaling pathways upon Tri-DAP and MDP stimulation, while laparoscopy surgery has small effect on the signaling pathways.