The effects of NOD2 variant frequency on the clinical navigation in the patients under given ERCP because of biliary stricture after liver transplantation

Introduction and aims: Donor age, prolonged cold and warm ischemia time, surgical techniques and development of hepatic artery thrombosis are well-known risk factors for biliary stricture after live donor liver transplantation (LDLT). Although intensive efforts have been made to overcome these problems, biliary stricture is still one of the most important causes of morbidity and mortality after LDLT. Nucleotide-binding oligomerization domain containing 2 (NOD2) is a component of the innate immune system and is expressed in liver, macrophages, dendritic cells as well as in Panet cells of the intestinal epithelium. NOD2 is a member of the NOD-like receptor family that recognizes and responds to bacterial wall peptides. This protein facilitates the balance between the host immune system and intestinal flora elements, regulates the secretion of various antibacterial compounds. In a study, R702W NOD2 variant was reported to be associated with increased risk of bacterial infection after orthotopic liver transplantation. In this study, we investigated the effects of some NOD2 variants (p.G908R, c.3020insC, p.R702W and 1007fs) on endoscopic treatment results and length of hospital stay in patients underwent endoscopic treatment for biliary stricture after LDLT. Materials and Methods: Age, sex, time to ERCP after transplantation, ERCP findings, and hospitalization time of patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) for biliary stricture after LDLT were recorded. Patients included in the study were divided into two groups. Group 1: Discharged in the first 24 hours after ERCP and Group 2: Discharged after the first 24 hours after ERCP. The frequency of four NOD2 variants was investigated between the two groups. Results: In the group discharged after the first 24 hours after ERCP, the number of patients whose stricture could not be passed was significantly higher than the other group (34% vs 0%, p <0.0001). In our study, p.R702W mutation was not detected in any of the patients discharged in the first 24 hours after ERCP, whereas it was detected in 10 patients who were discharged after the first 24 hours after ERCP. The frequency of p.R702W mutation was significantly different between the two groups (p: 0.002). 1007fs mutation was detected in 3 patients in the first 24 hours after ERCP. However, this mutation was detected in 14 patients in the group discharged after the first 24 hours after ERCP. The frequency of 1007fs mutations between the two groups was statistically significant (p: 0.011). Conclusion: Our results suggest that NOD2 variants, especially the p.R702W variant, have a role on the length of hospital stay in liver transplant patients after ERCP procedure. Keywords: Liver transplantation, ERCP, Biliary stricture, NOD2