Fluid Shear Stress Induces Endothelial Cell Injury via Protein Kinase C Alpha-Mediated Repression of p120-Catenin and Vascular Endothelial Cadherin In Vitro

Genetic evidence for the causal association of neuroticism with intracranial aneurysms: A Mendelian randomization study

OBJECTIVE

The aim of this study was to assess the potential causal relationship between neuroticism and 12 neuroticism items with intracranial aneurysms (IAs) and aneurysmal subarachnoid hemorrhage (aSAH) using a two-sample Mendelian randomization (MR) approach.

METHODS

Study data were obtained from the Genome-Wide Association Study (GWAS) pooled dataset, and we extracted summary statistics for neuroticism, 12 neuroticism items, and IAs, which were categorized into ruptured and unruptured aneurysms (IA), aSAH, and unruptured IAs (uIA). Single nucleotide polymorphisms (SNPs) were used as instrumental variables (IVs) to explore the causal relationship between exposure and outcome using five Mendelian randomization methods, with Inverse variance weighted (IVW) as the primary study method. Horizontal multiple validity tests, sensitivity analyses, and inverse MR ensured the stability of the results.

RESULTS

The two-sample MR showed a genetically predictive association between neuroticism and IA [odds ratio (OR) = 1.16; 95 % confidence interval (95 % CI): 1.04-1.30; p = 0.009], aSAH (OR = 1.17; 95 % CI: 1.03-1.33; p = 0.013) and uIA (OR = 1.30; 95 % CI: 1.07-1.59; p = 0.009) were all genetically predictive of association. Ivw showed a positive association between 5 neuroticism items and IA risk, 5 neuroticism items and aSAH risk as well as no genetically predictive association between neuroticism items and uIA. Sensitivity analysis and inverse MR confirmed the robustness of the results.

CONCLUSION

Our Mendelian randomization analysis demonstrated genetic causality between neuroticism and neuroticism items with intracranial aneurysms, aneurysmal subarachnoid hemorrhage, and unruptured intracranial aneurysms, and further studies are needed to confirm these results and explore potential mechanisms of action.

Impinging Flow Mediates Vascular Endothelial Cell Injury through the PKCα/ERK/PPARγ Pathway in vitro

INTRODUCTION

This study aimed to elucidate the mechanisms underlying endothelial injury in the context of intracranial aneurysm formation and development, which are associated with vascular endothelial injury caused by hemodynamic abnormalities. Specifically, we focus on the involvement of PKCα, an intracellular signaling transmitter closely linked to vascular diseases, and its role in activating MAPK. Additionally, we investigate the protective effects of PPARγ, a vasculoprotective factor known to attenuate vascular injury by mitigating the inflammatory response in the vessel wall.

METHODS

The study employs a modified T-chamber to replicate fluid flow conditions at the artery bifurcation, allowing us to assess wall shear stress effects on human umbilical vein endothelial cells in vitro. Through experimental manipulations involving PKCα knockdown and Ca2+ and MAPK inhibitors, we evaluated the phosphorylation status of PKCα, NF-κB, ERK5, ERK1/2, JNK1/2/3, and P38, as well as the expression levels of PPARγ, NF-κB, and MMP2 via Western blot analysis. The cellular localization of phosphorylated NF-κB was determined using immunofluorescence.

RESULTS

Our results showed that impinging flow resulted in the activation of PKCα, followed by the phosphorylation of ERK5, ERK1/2, and JNK1/2/3, leading to a decrease in PPARγ expression, an increase in the expression of NF-κB and MMP2, and the induction of apoptotic injury. Inhibition of PKCα activation or knockdown of PKCα using shRNA leads to a suppression of ERK5, ERK1/2, JNK1/2/3, and P38 phosphorylation, an elevation in PPARγ expression, and a reduction in NF-κB and MMP2 expression, alleviated apoptotic injury. Furthermore, we observe that the regulation of PPARγ, NF-κB, and MMP2 expression is influenced by ERK5 and ERK1/2 phosphorylation, and activation of PPARγ effectively counteracts the elevated expression of NF-κB and MMP2.

CONCLUSION

Our findings suggest that the PKCα/ERK/PPARγ pathway plays a crucial role in mediating endothelial injury under conditions of impinging flow, with potential implications for vascular diseases and intracranial aneurysm development.

The Association of Morphological Differences of Middle Cerebral Artery Bifurcation and Aneurysm Formation: A Systematic Review and Meta-Analysis

OBJECTIVE

We explored the relationships between morphological parameters of middle cerebral artery (MCA) bifurcations based on imaging and the development of middle cerebral aneurysms. Artery bifurcations can form disordered hemodynamics which can promote the development of aneurysms, whereas the hemodynamic environment at the bifurcation tip is highly reliant on the bifurcation's geometry.

METHODS

We searched 3 electronic databases for all relevant, publicly available publications as of March 18, 2022. Through the screening of abstracts and full texts, a meta-analysis was performed to compare the daughter-to-daughter angle, the inclination angle (γ), and the parent vessel diameter of MCA bifurcations between patients in MCA aneurysm and non-aneurysm controls.

RESULTS

Ten articles describing 1012 patients with MCA aneurysms and 1106 control individuals without aneurysms were included in the analysis. The aneurysm group showed a larger daughter-to-daughter branch angle at MCA bifurcations than the non-aneurysm group (weighted mean difference [WMD] = 42.00; 95% confidence interval [CI], 33.77 to 50.23; P < 0.00001). The daughter-to-daughter angle was also larger in the MCA aneurysm group with than without an aneurysm side branch (WMD = 37.03; 95% CI, 26.57 to 47.50; P < 0.00001), and in the MCA aneurysm group than in the non-aneurysm control group (WMD = 41.87; 95% CI, 29.19 to 54.54; P < 0.00001). The aneurysm group had a larger inclination angle than the control group (WMD = 28.73; 95% CI, 18.78 to 38.69; P < 0.00001). In patients with a MCA aneurysm, the parent vessel of the branch with the MCA aneurysm tended to be smaller in diameter than the contralateral branch without the aneurysm (WMD = -0.12; 95% CI, -0.24 to 0.00; P = 0.05).

CONCLUSIONS

A larger daughter-to-daughter angle and larger inclination angle at MCA bifurcations are closely related to MCA bifurcation aneurysms. The parent vessel diameter is negatively related to MCA bifurcation aneurysms.

Impinging Flow Induces Expression of Monocyte Chemoattractant Protein-1 in Endothelial Cells Through Activation of the c-Jun N-terminal Kinase/c-Jun/p38/c-Fos Pathway

OBJECTIVE

Monocyte chemoattractant protein-1 (MCP-1) is an important regulator of the formation and development of intracranial aneurysms. This study explored the molecular mechanisms underlying the induction of MCP-1 and related inflammatory factors in human umbilical vein endothelial cells (HUVECs) under hemodynamic conditions.

METHODS

A modified T chamber was used to simulate fluid flow at the bifurcation of the artery and wall shear stress on HUVECs in vitro. Changes in HUVECs were analyzed in response to impinging flow. And HUVECs without impinging flow were used as the control group. Protein expression levels of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38, activator protein-1, and MCP-1 were detected by Western blot, and the messenger RNA expression levels of MCP-1, interleukin (IL)-1β, and IL-6 were determined by quantitative reverse transcription polymerase chain reaction.

RESULTS

Under impinging flow, the phosphorylation levels of ERK, JNK, and p38, as well as the protein levels of MCP-1, c-Jun, and c-Fos, increased. The messenger RNA expression of MCP-1, IL-1β, and IL-6 also increased in HUVECs. Pretreatment of the HUVECs with inhibitors of JNK and p38 significantly attenuated the increased expression of MCP-1, IL-1β, and IL-6, while ERK inhibitors had no obvious effect.

CONCLUSIONS

Under impinging flow, MCP-1 and inflammatory factors are regulated through the JNK/c-Jun/p38/c-Fos pathway and participate in EC inflammation.