Sustained expression of MCP-1 induced low wall shear stress loading in conjunction with turbulent flow on endothelial cells of intracranial aneurysm.

Cheng Chu,Hongxia Cai,Yanyu Zheng,Xinjiang Zhang,Gang Xu,Ming Yang,Lihong Tao,Hongcan Shi,Zuowei Duan,Xiaoyu Li,Bin Chen,Xiaocong Li

doi:10.1111/jcmm.15868

Abstract

Shear stress was reported to regulate the expression of AC007362, but its underlying mechanisms remain to be explored. In this study, to isolate endothelial cells of blood vessels, unruptured and ruptured intracranial aneurysm (IA) tissues were collected from IA patients. Subsequently, quantitative real‐time PCR (qRT‐PCR), Western blot and luciferase assay were performed to investigate the relationships between AC007362, miRNAs‐493 and monocyte chemoattractant protein‐1 (MCP‐1) in human umbilical vein endothelial cells (HUVECs) exposed to shear stress. Reduced representation bisulphite sequencing (RRBS) was performed to assess the level of DNA methylation in AC007362 promoter. Accordingly, AC007362 and MCP‐1 were significantly up‐regulated while miR‐493 was significantly down‐regulated in HUVECs exposed to shear stress. AC007362 could suppress the miR‐493 expression and elevate the MCP‐1 expression, and miR‐493 was shown to respectively target AC007362 and MCP‐1. Moreover, shear stress in HUVECs led to the down‐regulated DNA methyltransferase 1 (DNMT1), as well as the decreased DNA methylation level of AC007362 promoter. Similar results were also observed in ruptured IA tissues when compared with unruptured IA tissues. In conclusion, this study presented a deep insight into the operation of the regulatory network of AC007362, miR‐493 and MCP‐1 upon shear stress. Under shear stress, the expression of AC007362 was enhanced by the inhibited promoter DNA methylation, while the expression of MCP‐1 was enhanced by sponging the expression of miR‐493.

Highlights

Intracranial aneurysm (IA) is a type of cerebrovascular disorder featured by intracranial artery dilatation induced by endothelial layer defects.[1,2] The rupture of an IA leads to subarachnoid haemorrhage (SAH), a disease featured by high mortality as well as significant disability
MiR-493 and monocyte chemoattractant protein-1 (MCP-1) expression was analysed in human umbilical vein endothelial cells (HUVECs) exposed to shear stress and the results showed that miR-493 expression was dramatically down-regulated by shear stress (Figure 2A)
The results showed that DNA methyltransferase 1 (DNMT1) mRNA expression and the DNA methylation of AC007362 promoter were both remarkably elevated in the group of unruptured IA (Figure 6A,B)

Summary

| INTRODUCTION

Intracranial aneurysm (IA) is a type of cerebrovascular disorder featured by intracranial artery dilatation induced by endothelial layer defects.[1,2] The rupture of an IA leads to subarachnoid haemorrhage (SAH), a disease featured by high mortality as well as significant disability. Upon binding to its receptor, MCP-1 expressed in microglia can trigger their activation while promoting neuro-inflammation, which in turn leads to cognitive disorders.[25] In patients with IA, MCP-1 can recruit and subsequently activate macrophages to attack blood vessel wall.[26] these macrophages will secret various pathological factors including proteinases as well as cytokines.[27,28] The role of MCP-1 in IA pathogenesis has been demonstrated in mice with MCP-1 knock-out.[27,29]. Shear stress may suppress the methylation of promoters of many genes.[32] we hypothesized that shear stress may promote the expression of AC007362 by suppressing its methylation while enhancing the expression of MCP-1 by sponging the expression of miR-493. We collected tissue samples from patients with ruptured small IA and unruptured big IA to compare their expression of AC007362/miR-493/MCP-1

| MATERIALS AND METHODS

| DISCUSSION

| CONCLUSION