Effect of ERK1/2 pathway in the expression of MHC-Ⅱof intestinal dendritic cells in viscerally hypersensitive rats

Abstract

To study the phenotypic alteration of intestinal dendritic cells (DC) in a rat model of irritable bowel syndrome (IBS) and the change of mitogen-activated protein kinase (MAPK) signaling pathway, in order to explore the potential mechanism of ERK1/2 pathway mediation in abnormal DC immune response. IBS rat model was established by combining neonatal maternal separation and colorectal distension in 10 SD rats, and 10 healthy rats served as controls. Visceral sensitivity was evaluated with abdominal withdrawal reflex (AWR). Mesenteric lymph node DC (MLNDC) was isolated and purified by magnetic label-based technique after modeling. Expression of surface major histocompatibility complex (MHC)-Ⅱin control rats was determined by flow cytometric analyses. Western-blot was used to determine the expression of MHC-Ⅱ, p-p38, p38, phosphorylated extracellular regulated protein kinase (p-ERK1/2), ERK1/2, phosphorylated c-Jun N-terminal kinase (p-JNK), and JNK in MLNDC. Visceral sensitivity was significantly higher in the IBS group than in the control group. The purity of the OX62 positivity MLNDC following magnetic sorting was about 85.57%±7.67%. MLNDC in the control group expressed high level of MHC-Ⅱ. The expression of MHC-Ⅱ and p-ERK1/2 in MLNDC in the IBS group were higher than those in the control group (1.05±0.13 vs 0.67±0.18, t=-2.973, P=0.041; 3.21±0.48 vs 2.34±0.85, t=-3.130, P=0.035); while there was no significant difference in the expressions of p-JNK and p-p38 compared with the control groups (0.95±0.17 vs 0.76±0.36, t=0.808, P=0.464; 1.07±1.13 vs 1.19±0.91, t=0.137, P=0.897). The intestinal DC in IBS rats show a upregulated expression of MHC-Ⅱ, which may be related to the activation of intracellular ERK1/2 pathway.