The Molecular Mechanism of NOD2 Activated by MDP in Colorectal Epithelial Cells to Induce Tolerant CXCL1, CXCL2, CXCL3 and CXCL8

ZHANG Zhao¹, CAO Ting¹, HU Ling¹, HU Jinyue²*

(¹Department of Clinical Laboratory, the Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha 410004, China; ²Central Laboratory, the Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha 410004, China)

Abstract:

This study explored the regulatory mechanism of MDP (muramyl dipeptide) activated NOD2 to induce chemokine expression in colorectal epithelial cells. RT-PCR and qRT-PCR were used to detect mRNA levels of chemokines, cytokines and ubiquitin editing enzyme A20. Western blot was used to detect protein level of A20. ELISA was used to detect protein level of chemokine CXCL8 (also called IL-8). The liposome transfection method was used to over-express A20. The results showed that MDP treatment of HCT116 cells induced the expression of chemokines CXCL1, CXCL2, CXCL3 and CXCL8, but did not induce the expression of pro-inflammatory factors TNFα, IL-1β and IL-6. The production of chemokines induced by MDP was tolerent, because the chemokine levels induced by the re-treatment with MDP after a pre-treatment with MDP was decreased significantly compared with the non-pre-treated group. MDP treatment up-regulated A20, but A20 overexpression did not down-regulate the immune response induced by MDP. Meanwhile, IL-1β up-regulated A20, but IL-1β pre-treatment also failed to down-regulate MDP-induced immune response. In conclusion, MDP induces the tolerant expression of CXCL1, CXCL2, CXCL3 and CXCL8 in colorectal epithelial cells, and A20 does not participate in the formation of this tolerance mechanism.

CSTR: 32200.14.cjcb.2021.11.0005