Inflammatory mediators in vascular disease: identifying promising targets for intracranial aneurysm research

Microcurrent wave alleviates mouse intracranial arterial dolichoectasia development

Intracranial arterial dolichoectasia (IADE) is associated with the interaction of hypertension and inflammation, and microcurrent can be effective in hypertension. Therefore, this study aimed to investigate the therapeutic effect of microcurrent electrical stimulation in a mouse IADE model. This study randomly categorized 20 mice into five groups: group 1-C (healthy control), group 2-D (IADE model), group 3-M + D (microcurrent administration before nephrectomy and until brain surgery), group 4-D + M (microcurrent administration for 4 weeks following brain surgery), and group 5-M (microcurrent administration for 4 weeks). Cerebral artery diameter and thickness and cerebral arterial wall extracellular matrix components were assessed. Among the five groups, group 2-D showed significantly higher cerebral arterial wall diameter (117.79 ± 17.05 µm) and proportion of collagen (42.46 ± 14.12%) and significantly lower arterial wall thickness (9.31 ± 2.26 µm) and proportion of smooth muscle cell (SMC) and elastin in the cerebral arterial wall (SMC: 38.05 ± 10.32%, elastin: 11.11 ± 6.97%). Additionally, group 4-D + M exhibited a non-significantly lower diameter (100.28 ± 25.99 µm) and higher thickness (12.82 ± 5.17 µm). Group 5-M demonstrated no evidence of toxicity in the liver and brain. The pilot study revealed that microcurrent is effective in preventing IADE development, although these beneficial effects warrant further investigation.

Potential application of peripheral blood biomarkers in intracranial aneurysms

Intracranial aneurysm (IA) counts are increasing yearly, with a high mortality and disability after rupture. Current diagnosis and treatment rely on costly equipment, lacking effective indicators for progression prediction and specific drugs for treatment. Recently, peripheral blood biomarkers, as common clinical test samples, reflecting the immune and inflammatory state of the body in real-time, have shown promise in providing additional information for risk stratification and treatment in IA patients, which may improve their outcomes after aneurysm rupture through anti-inflammatory therapy. Therefore, this paper reviewed the progress of potential biomarkers of IAs, including inflammatory blood indicators, cytokines, and blood lipids, aiming to aid individual management and therapy of aneurysms in clinical practices.

Cerebral Aneurysm and Interleukin-6: a Key Player in Aneurysm Generation and Rupture or Just One of the Multiple Factors?

Intracranial aneurysm (IA) rupture is a common cause of subarachnoid hemorrhage (SAH) with high mortality and morbidity. Inflammatory interleukins (IL), such as IL-6, play an important role in the occurrence and rupture of IA causing SAH. With this review we aim to elucidate the specific role of IL-6 in aneurysm formation and rupture in preclinical and clinical studies. IL-6 is a novel cytokine in that it has pro-inflammatory and anti-inflammatory signaling pathways. In preclinical and clinical studies of IA formation, elevated and reduced levels of IL-6 are reported. Poor post-rupture prognosis and increased rupture risk, however, are associated with higher levels of IL-6. By better understanding the relationships between IL-6 and IA formation and rupture, IL-6 may serve as a biomarker in high-risk populations. Furthermore, by better understanding the IL-6 signaling mechanisms in IA formation and rupture, IL-6 may optimize surveillance and treatment strategies. This review examines the association between IL-6 and IA, while also suggesting future research directions.

Pro-Inflammatory and Anti-Inflammatory Cytokines Levels are Significantly Altered in Cerebrospinal Fluid of Unruptured Intracranial Aneurysm (UIA) Patients

Introduction

Identifying all the relevant “players” in the formation and development of brain aneurysms may help understand the mechanisms responsible for the formation of an aneurysm, as well as in the search for non-invasive targets for aneurysm pharmacotherapy.

Aim

The evaluation of the concentration of pro-inflammatory and anti-inflammatory cytokines in cerebrospinal fluid (CSF) and serum of patients with unruptured intracranial aneurysms (UIA) in comparison to individuals without vascular lesions in the brain.

Methods

The concentration of 27 proteins in the CSF and serum of UIA patients (N = 40) and individuals without vascular lesions in the brain (N = 15) was evaluated using a multiplex ELISA kit (Bio-Plex Pro Human Cytokine 27-Plex Panel).

Results

In the CSF 13 out of 27 proteins evaluated presented a concentration 1.36-fold or greater in UIA patients in comparison to the control group. Significantly higher were IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-7, IL-8, IL-12, IL-13, TNF-α, INF-γ, MCP-1, and VEGF. In the serum none of the proteins evaluated significantly differ between UIA patients and the control group. The correlation coefficient analysis showed that CSF IL-1β, IL-8, and TNF-α positively, while IL-13 negatively correlated with the size of aneurysms. CSF IL-6 and MCP-1 concentrations positively correlated with the number of aneurysms.

Conclusion

In patients with UIA, pro-inflammatory and anti-inflammatory mechanisms are activated simultaneously, because the concentration of promoting and suppressing inflammatory response proteins was significantly higher in CSF of UIA patients compared to the control group. The preventive therapy of brain aneurysm development should be focused on IL-1β, IL-6, IL-8, MCP-1, and TNF-α, the concentration of which in CSF positively correlated with the size and number of aneurysms.

Identification of Biomarkers in Intracranial Aneurysm and Their Immune Infiltration Characteristics

BACKGROUND

Intracranial aneurysm (IA), known as the intracranial "unscheduled bomb," is one of the most dangerous cerebrovascular diseases, with unclear pathogenesis. This study aimed to show the mechanisms and identify the new biological targets by applying bioinformatics analysis.

METHODS

Expression profiling for control superficial temporal artery and IA walls in GSE26969 and GSE75436 datasets were downloaded. By executing the LIMMA package in R software, the differentially expressed genes (DEGs) were filtered, and the functional enrichments were consequently performed. Further cross-linking with the 2483 immune-related genes (IRGs) from the ImmPort database, the differentially expressed IRGs were identified. Based on them, the least absolute shrinkage and selection operator logistic regression and support vector machine-recursive feature elimination algorithms were used to screen the biomarkers, which were validated in the GSE54083 datasets. The CIBERSORT algorithm was applied to evaluate the infiltration of immune cells in tissues.

RESULTS

A total of 668 DEGs were obtained, and the functional enrichment suggested that they were closely related to the immune process. After intersecting them with the IRGs, 90 differentially expressed IRGs emerged, and ADIPOQ and ESM1 were identified as the biomarkers. Besides, we found that the infiltrated immune cells, such as the mast cells resting, might be associated with them.

CONCLUSIONS

We explored the contributing factors involving IA, which may generate a better understanding of the complex interactions among them and inspire a promising strategy for clinical works.

High-Dimensional Immune Profiling by Mass Cytometry Revealed the Circulating Immune Cell Landscape in Patients With Intracranial Aneurysm

Background

Increasing evidence supports a critical role of chronic inflammation in intracranial aneurysm (IA). Understanding how the immunological alterations in IA provides opportunities for targeted treatment. However, there is a lack of comprehensive and detailed characterization of the changes in circulating immune cells in IA.

Objective

To perform a comprehensive and detailed characterization of the changes in circulating immune cells in patients with IA.

Methods

Peripheral blood mononuclear cell samples from IA patients (n = 26) and age-and sex-matched healthy controls (HCs, n = 20) were analyzed using high dimensional mass cytometry, and the frequency and phenotype of immune cell subtypes were assessed.

Results

We identified 28 cell clusters and found that the immune signature of IA consists of cluster changes. IA patients exhibited dysfunction of immunity, with dysregulation of CD4⁺ T-cell clusters, increased B cells and monocytes, and decreased CD8⁺ T cells, DNT cells, and DPT cells. Moreover, compared with findings in HC, IA was associated with enhanced lymphocyte and monocyte immune activation, with a higher expression of HLA-DR, CXCR3, and CX3CR1. In addition, the expression of TLR4, p-STAT3, and the exhaustion marker PD1 was increased in T cells, B cells, and NK cells in IA patients.

Conclusions

Our data provide an overview of the circulating immune cell landscape of IA patients, and reveal that the dysfunction of circulating immunity may play a potential role in the development of IA.

Transcriptome-Based Dissection of Intracranial Aneurysms Unveils an “Immuno-Thermal” Microenvironment and Defines a Pathological Feature-Derived Gene Signature for Risk Estimation

Immune inflammation plays an essential role in the formation and rupture of intracranial aneurysm (IA). However, the current limited knowledge of alterations in the immune microenvironment of IA has hampered the mastery of pathological mechanisms and technological advances, such as molecular diagnostic and coated stent-based molecular therapy. In this study, seven IA datasets were enrolled from the GEO database to decode the immune microenvironment and relevant biometric alterations. The ssGSEA algorithm was employed for immune infiltration assessment. IAs displayed abundant immune cell infiltration, activated immune-related pathways, and high expression of immune-related genes. Several immunosuppression cells and genes were also coordinately upregulated in IAs. Five immune-related hub genes, including CXCL10, IL6, IL10, STAT1, and VEGFA, were identified from the protein-protein interaction network and further detected at the protein level. CeRNA networks and latent drugs targeting the hub genes were predicted for targeted therapy reference. Two gene modules recognized via WCGNA were functionally associated with contractile smooth muscle loss and extracellular matrix metabolism, respectively. In blood datasets, a pathological feature-derived gene signature (PFDGS) for IA diagnosis and rupture risk prediction was established using machine learning. Patients with high PFDGS scores may possess adverse biological alterations and present with a high risk of morbidity or IA rupture, requiring more vigilance or prompt intervention. Overall, we systematically unveiled an “immuno-thermal” microenvironment characterized by co-enhanced immune activation and immunosuppression in IA, which provides a novel insight into molecular pathology. The PFDGS is a promising signature for optimizing risk surveillance and clinical decision-making in IA patients.

Elevated Glucose-Potassium Ratio Predicts Preoperative Rebleeding in Patients With Aneurysmal Subarachnoid Hemorrhage

Introduction: Recent reports revealed that higher serum glucose-potassium ratio (GPR) levels at admission were significantly associated with poor outcomes at 3 months following aneurysmal subarachnoid hemorrhage (aSAH). This study aimed to investigate the association between GPR and the risk of rebleeding following aSAH. Methods: This single-center retrospective study of patients with aSAH was conducted in our hospital between January 2008 and December 2020. Patients meeting the inclusion criteria were divided into the rebleed group and the non-rebleed group. Univariate and multivariate analyses were implemented to assess the association between risk factors of rebleeding and outcomes. Results: A total of 1,367 patients experiencing aSAH, 744 patients who met the entry criteria in the study [mean age (54.89 ± 11.30) years; 60.50% female patients], of whom 45 (6.05%) developed rebleeding. The patients in the rebleed group had significantly higher GPR levels than those of patients without rebleeding [2.13 (1.56-3.20) vs. 1.49 (1.23-1.87); p < 0.001]. Multivariable analysis revealed that higher mFisher grade and GPR were associated with rebleeding [mFisher grade, odds ratios (OR) 0.361, 95% CI 0.166-0.783, p = 0.01; GPR, OR 0.254, 95% CI 0.13-0.495, p < 0.001]. The receiver operating characteristics (ROCs) analysis described that the suitable cut-off value for GPR as a predictor for rebleeding in patients with aSAH was determined as 2.09 (the area under the curve [AUC] was 0.729, 95% CI 0.696-0.761, p < 0.0001; the sensitivity was 53.33%, and the specificity was 83.98%). Pearson correlation analysis showed a significant positive correlation between GPR and mFisher grade, between GPR and Hunt-Hess grade (mFisher grade r = 0.4271, OR 0.1824, 95% CI 0.3665-0.4842, p < 0.001; Hunt-Hess grade r = 0.4248, OR 0.1836, 95% CI 0.3697-0.4854, p < 0.001). The patients in the poor outcome had significantly higher GPR levels than those of patients in the good outcome [1.87 (1.53-2.42) vs. 1.45 (1.20-1.80); p < 0.001]. Multivariable analysis demonstrated that GPR was an independent predictor for poor prognosis. The AUC of GPR was 0.709 (95% CI 0.675-0.741; p < 0.0001) (sensitivity = 77.70%; specificity = 55.54%) for poor prognosis. Conclusion: Higher preoperative serum GPR level was associated with Hunt-Hess grade, mFisher grade, rebleeding, and unfunctional outcome, and that they predicted preoperative rebleeding and the 90-days outcome of non-diabetic patients with aSAH, who had potentially relevant clinical implications in patients with aSAH.

IL-6 Quotient (The Ratio of Cerebrospinal Fluid IL-6 to Serum IL-6) as a Biomarker of an Unruptured Intracranial Aneurysm

Background

Studies conducted so far have focused mainly on the assessment of IL-6 levels in patients with ruptured brain aneurysms. Carrying out detailed studies in patients with un-ruptured brain aneurysms (UIA) would be extremely important, as it would answer the question of whether IL-6 plays also a role in primary aneurysm formation and growth.

Methods

IL-6, S100, NSE, and albumin concentrations in 67 UIA patients and 17 individuals without vascular lesions in the brain were tested using in vitro diagnostic immunoassays according to the manufacturers' instructions. IL-6 Quotient was calculated by dividing cerebrospinal fluid (CSF) IL-6 by serum IL-6.

Results

We showed that IL-6 Quotient was significantly higher in UIA patients (1.78) compared to the control group (0.87; p<0.001). Multivariate logistic regression analysis demonstrated that a growth in IL-6 Quotient increases the probability of UIA diagnosis. In UIA patients CSF IL-6 concentration was significantly higher (4.55 pg/ml) compared to the serum concentration (2.39 pg/ml; p<0.001). In both the study and control group, the blood-brain barrier was intact, thus the CSF-blood gradient of the IL-6 concentration in UIA patients was likely to be the expression of local synthesis of the cytokine within the central nervous system. Patients with multiple brain aneurysms had significantly higher CSF IL-6 levels (5.08 pg/ml) compared to individuals with a single aneurysm (4.14 pg/ml; p=0.0227).

Conclusion

This totality of the may suggest IL-6 as a biomarker for UIA formation; however, further studies are needed to unequivocally confirm clinical application of IL-6 concentration evaluation.

Non-coding RNAs role in intracranial aneurysm: General principles with focus on inflammation

Intracranial aneurysm (IA) is one of the most challenging vascular lesions in the brain for clinicians. It was reported that 1%-6% of the world's population is affected by IAs. Owing to serious complications arising from these lesions, much attention has been paid to better understand their pathophysiology. Non-coding RNAs including short non-coding RNAs and long non-coding RNAs, have critical roles in modulating physiologic and pathological processes. These RNAs are emerging as new fundamental regulators of gene expression, are related with the progression of IA. Non-coding RNAs act via multiple mechanisms and be involved in vascular development, growth and remodeling. Furthermore, these molecules are involved in the regulation of inflammation, a key process in the formation and rupture of IA. Studying non-coding RNAs can yield a hypothetical mechanism for better understanding IA. The present study aims to focus on the role of these non-coding RNAs in the pathogenesis of IA.

Is neutrophil-lymphocyte ratio a useful tool for predicting outcome in subarachnoid hemorrhage? A systematic review

Ruptured intracranial aneurysms, as the leading cause of spontaneous subarachnoid hemorrhage (aSAH), represents an emergency with high morbi-mortality. The comprehension of the underlying pathology that involves inflammatory and immune responses, through the neutrophil-to-lymphocyte ratio (NLR), could help to predict complications such as delayed cerebral ischemia (DCI) or rebleeding and the functional outcome. Systematic review of English-based literature through PubMed and Biblioteca Vitural em Saúde (BVS) to find papers discussing the use of NLR in the aSAH setting. Area-under-curve (AUC) of receiver operating characteristics (ROC), cutoff value, sensitivity, and specificity were retrieved. From 53 articles included, 4 papers were evaluated after exclusion criteria. Rebleeding could be predicted with a NLR cutoff value of 9.88 (sensitivity 72.3%, specificity 63.3%). The mean cutoff value for DCI was 12.85, with sensitivity 66.3% and specificity 75.8%. Finally, a worse 3-month functional outcome could be predicted with a mean sensitivity of 73.3% and a mean specificity of 54%. NLR is a new issue in scientific community, especially neurosurgery. The current understanding points to a multifactorial process after aSAH that emerges as alterations on the NLR. As a measurement readily available and cost-effect after admission of the patient, its use signals that patients that need expedite surgical treatment or more aggressive treatment for vasospasm. As other medical subspecialties already use this ratio to predict outcomes, the literature reviewed by this paper constitute the earliest clues that higher NLR predicts re-bleeding, DCI, and functional outcome.

Pharmacological inhibition of STAT3 by BP-1-102 inhibits intracranial aneurysm formation and rupture in mice through modulating inflammatory response

As an inhibitor of STAT3, BP-1-102 can regulate the inflammation response caused by vascular smooth muscle cells (VSMCs) by inhibiting the JAK/STAT3/NF-κB pathway, thereby attenuating the symptoms of intracranial aneurysm (IA). IA mouse model was established by stereotactic injection of elastase to evaluate the effect of BP-1-102. The expression levels of smooth muscle markers and matrix metalloproteinases (MMPs) were detected by qRT-PCR, and the levels of inflammatory factors were detected by ELISA and qRT-PCR. The protein levels of the NF-κB signaling pathway factors were examined by Western blot. BP-1-102 reduced blood pressure in aneurysm mice, up-regulated smooth muscle cell markers MHC, SMA, and SM22, and down-regulated the expression of MMP2 and MMP9 in vascular tissues. At the same time, BP-1-102 also down-regulated the expression levels of inflammatory response factors and the NF-κB pathway proteins. In the IA model, BP-1-102 can reduce the expression of inflammatory factors and MMPs bound to NF-κB by inhibiting the activation of the JAK/STAT3/NF-κB pathway proteins, and then restore the vascular wall elastin to reduce blood pressure, thereby treating aneurysm.

Aneurysm Wall Enhancement in Unruptured Intracranial Aneurysms: A Histopathological Evaluation

Background Unruptured intracerebral aneurysm wall enhancement (AWE) on vessel wall magnetic resonance imaging scans may be a promising predictor for rupture-prone intracerebral aneurysms. However, the pathophysiology of AWE remains unclear. To this end, the association between AWE and histopathological changes was assessed in this study. Methods and Results A total of 35 patients with 41 unruptured intracerebral aneurysms who underwent surgical clipping were prospectively enrolled. A total of 27 aneurysms were available for histological evaluation. The macroscopic and microscopic features of unruptured intracerebral aneurysms with and without enhancement were assessed. The microscopic features studied included inflammatory cell invasion and vasa vasorum, which were assessed using immunohistochemical staining with CD68, CD3, CD20, and myeloperoxidase for the former and CD34 for the latter. A total of 21 (51.2%) aneurysms showed AWE (partial AWE, n=7; circumferential AWE, n=14). Atherosclerotic and translucent aneurysms were identified in 17 and 14 aneurysms, respectively. Aneurysm size, irregularity, and atherosclerotic and translucent aneurysms were associated with AWE on univariate analysis (P<0.05). Multivariate logistic regression analysis showed that atherosclerosis was the only factor significantly and independently associated with AWE (P=0.027). Histological assessment revealed that inflammatory cell infiltration, intraluminal thrombus, and vasa vasorum were significantly associated with AWE (P<0.05). Conclusions Though AWE on vessel wall magnetic resonance imaging scans may be associated with the presence of atherosclerotic lesions in unruptured intracerebral aneurysms, inflammatory cell infiltration within atherosclerosis, intraluminal thrombus, and vasa vasorum may be the main pathological features associated with AWE. However, the underlying pathological mechanism for AWE still needs to be further studied.

Circulating Treg cells from patients with cerebral aneurysms displayed deficiency in ICOS expression and function

Inducible costimulator (ICOS) is a member of the CD28 family. When activated, ICOS signalling promotes FOXP3 CNS2 gene demethylation and stabilizes Treg differentiation. Cerebral aneurysm (CA) is the local ballooning of the cerebral vasculature, characterized by higher levels of inflammation mediators and tissue remodelling. FOXP3+ Treg cell dysfunction may contribute to CA pathogenesis. In this study, the expression and function of ICOS in Treg cells was investigated. Circulating CD4+ CD25hi T cells from CA subjects demonstrated significantly lower levels of ICOS expression than circulating CD4+ CD25hi T cells from healthy subjects. In both healthy subjects and CA subjects, FOXP3+ Treg cells were highly concentrated in the ICOS+ fraction of CD4+ CD25hi T cells. Anti-ICOS costimulation, in combination with anti-CD3 and IL-2, significantly increased FOXP3 expression in CD4+ CD25hi ICOS+ T cells but not in CD4+ CD25hi ICOS- T cells. In addition, anti-CD3/IL-2 and anti-ICOS costimulation significantly elevated the expression of IL-10 and TGF-β, decreased the expression of IL-17, and enhanced CD4+ CD25hi ICOS+ T cell-mediated suppression of autologous CD4+ CD25- Tconv proliferation. Interestingly, CD4+ CD25hi ICOS+ T cells from CA subjects presented lower responsiveness toward anti-ICOS costimulation than CD4+ CD25hi ICOS+ T cells from healthy subjects. Overall, these results demonstrated that ICOS signalling could significantly improve FOXP3 expression and enhance Treg functional potency. However, circulating Treg cells from CA patients displayed reduced ICOS expression and lower responsiveness toward anti-ICOS stimulation.

Development and validation of a predictive model for the prognosis in aneurysmal subarachnoid hemorrhage

Background

This study was to conduct a predictive model for the prognosis of aneurysmal subarachnoid hemorrhage (aSAH) and validate the clinical data.

Methods

A total of 235 aSAH patients were enrolled in this study, dividing into the favorable or poor prognosis groups based on Modified Rankin Scale (mRS) at 3 months postoperatively. Multivariate analysis was assessed using binary Logistic regression and Fisher discriminant analysis. The receiver operating characteristic (ROC) curve was used to determine the cut‐off value.

Results

Our findings showed that the high Glasgow Coma Scale (GCS) score 24‐hour after surgery reduced the risk of poor prognosis, and the surgical clipping and elevated neutrophil‐lymphocyte ratio (NLR) increased the risk of poor prognosis. The discriminant function was V = 0.881 × GCS score − 0.523 × NLR − 0.422 × therapeutic approach, and V = −0.689 served as a cut‐off value. When V ≥ −0.689, the good prognosis was considered among these patients with aSAH. The correctness for predicting the prognostic outcomes by self‐validation was 85.11%.

Conclusion

This predictive model established by a discriminant analysis is a useful tool for predicting the prognostic outcomes of aSAH patients, which may help clinicians identify patients at high risk for poor prognosis and optimize treatment after surgery.

Treatment with dimethyl fumarate reduces the formation and rupture of intracranial aneurysms: Role of Nrf2 activation

Oxidative stress and chronic inflammation in arterial walls have been implicated in intracranial aneurysm (IA) formation and rupture. Dimethyl fumarate (DMF) exhibits immunomodulatory properties, partly via activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway which reduces oxidative stress by inducing the antioxidant response element (ARE). This study evaluated the effects of DMF both in vitro, using tumor necrosis factor (TNF)-α-treated vascular smooth muscle cells (VSMC), and in vivo, using a murine elastase model to induce aneurysm formation. The mice were treated with either DMF at 100 mg/kg/day P.O. or vehicle for two weeks. DMF treatment protected VSMCs from TNF-α-induced inflammation as demonstrated by its downregulation of cytokines and upregulation of Nrf2 and smooth muscle cell markers. At higher doses, DMF also inhibited the pro-proliferative action of TNF-α by increasing apoptosis which protected the cells from aponecrosis. In mice, DMF treatment significantly decreased the incidence of aneurysm formation and rupture, at the same time increasing Nrf2 levels. DMF demonstrated a neuroprotective effect in mice with a resultant inhibition of oxidative stress, inflammation, and fibrosis in the cerebrovasculature. This suggests a potential role for DMF as a rescue therapy for patients at risk for formation and rupture of IAs.

In the wall lies the truth: a systematic review of diagnostic markers in intracranial aneurysms

OBJECTIVE

Despite recent advances in molecular biology and genetics, the development of intracranial aneurysms (IA) is still poorly understood. Elucidation of the processes occurring in the IA wall is essential for a better understanding of IA pathophysiology. We sought to analyze the current evidence from histological, molecular and genetic studies of IA.

METHODS

We systematically searched PubMed, Scopus, Web of Science and Cochrane Library for articles published before Mar 1, 2019 reporting on different diagnostic markers in human IA specimens. Expression of the markers in IA wall (vs. healthy arterial wall) and association with the rupture status were analyzed. The quality of the included studies and the level of the evidence for the markers were incorporated into the final data assessment.

RESULTS

We included 123 studies reporting on analyses of 3476 IA (median 19 IA/study) published between 1966 and 2018. Based on microscopic, biochemical, genetic and biomechanical analyses, data on 358 diagnostic targets in the IA wall were collected. We developed a scale to distribute the diagnostic markers according to their specificity for IA or healthy arterial wall, as well as for ruptured or unruptured IA. We identified different functional pathways, which might reflect the intrinsic and extrinsic processes underlying IA pathophysiology.

CONCLUSIONS

Multiple histological and molecular markers and the related functional pathways contributing to the development of IA might present promising targets for future therapeutic interventions. Because of small numbers of IA samples in each study, 89% of the analyzed diagnostic markers presented with the lowest level of evidence. This underlines the need for the initiation of a multi-centric prospective histological IA register for pooled data analysis.

Admission Neutrophil-Lymphocyte Ratio Predicts Rebleeding Following Aneurismal Subarachnoid Hemorrhage

OBJECTIVE

The relationship between neutrophil-lymphocyte ratio (NLR) and the occurrence of rebleeding in aneurysmal subarachnoid hemorrhage (aSAH) is poorly understood. Our study aimed to investigate the association between NLR on admission and rebleeding following aSAH.

METHODS

Clinical and laboratorial data from patients with aSAH were retrospectively collected, including leukocyte, neutrophil, lymphocyte, and NLR. Univariate and multivariate analyses were performed to assess for the association of NLR with rebleeding. We performed propensity-score matching analyses to correct imbalances in patient characteristics between the rebleeding group and nonrebleeding group.

RESULTS

Rebleeding occurred in 30 of 716 (4.19%) patients with aSAH in this cohort. Patients with rebleeding had significantly higher NLR comparing with patients without rebleeding (11.27 vs. 5.5; P < 0.05) in the univariate analysis. In the multivariate analysis, NLR was considered as a risk factor of rebleeding (odds ratio, 0.283; 95% confidence interval, 0.130-0.620; P = 0.002), as well as Fisher grade (odds ratio, 0.353, 95% confidence interval, 0.151-0.824; P = 0.016). The area under the curve of the NLR and combined NLR-Fisher grade model was 0.702 and 0.744 (sensitivity was 39.94%, and specificity was 100%) for predicting rebleeding, respectively. After propensity-score matching, the optimal cutoff value for NLR as a predictor for rebleeding following aSAH was determined as 5.4 (sensitivity was 83.33%, and the specificity was 63.33%).

CONCLUSIONS

Higher NLR predicts the occurrence of rebleeding and poor outcome, and NLR combined with Fisher grade significantly improves the prediction of rebleeding following aSAH.

The Relationship of Arterial Wall Enhancement Ratio on MRI with the Degree of Inflammation in a Rabbit Aneurysm Model: A Pilot Study

RATIONALE AND OBJECTIVES

To identify the relationship between enhancement ratio (ER) of aneurysm walls and degrees of inflammation.

MATERIALS AND METHODS

Twenty-five white rabbits were used in this study; all underwent surgery to isolate the right common carotid artery (RCCA). Twenty rabbits underwent an aneurysm creation procedure, and 5 underwent a control procedure. In the aneurysm creation procedure, there was surgical exposure of the origin of RCCA and temporary occlusion with an aneurysm clip. The distal RCCA was ligated, and the trapped segment was infused with elastase for 20 minutes, after which the clip was removed. In the control procedure, the trapped segment was infused with saline. High-resolution magnetic resonance imaging was performed at weeks 2, 3, 4, and 5 after the procedure, and wall ER was calculated. After MRI, aneurysms were harvested and stained with hematoxylin-eosin. Pearson correlation analysis and scatter plots were used to evaluate the relationship between wall ER and the degree of inflammation. The relationships between the wall ER, the number of inflammatory cells and time were analyzed by linear graphs.

RESULTS

Wall ER positively correlated with inflammatory cell count of the aneurysm wall (r = 0.877, p < 0.001). The relationships between wall ER, the number of inflammatory cells, and time increased and then decreased according linear graphs.

CONCLUSION

In this study, the aneurysm wall ER was confirmed to be associated with the degree of inflammation on the rabbit aneurysm model.

Regulatory T cells demonstrate significantly increased functions following stimulation with IL-2 in a Tim-3-dependent manner in intracranial aneurysms

The formation of intracranial aneurysm (IA) is associated with the destruction of various cellular and structural components, which induces pathogenic inflammatory responses that further propagate tissue damage. The regulatory immune system can suppress exacerbated inflammation and offer tissue protection; however, previous studies by others and us have demonstrated that the regulatory T (Treg) cells were functionally impaired in IA patients. Hence, strategies that can improve Treg function in IA patients should be investigated. Based on our previous finding that IL-2 strongly elevated the expression of the checkpoint molecule Tim-3 in Treg cells, we examined the effect of IL-2 in the function of Treg cells from IA patients. External IL-2 significantly improved the proliferation of Treg cells, increased the expression of CTLA-4 and LAG-3, and enhanced Treg-mediated suppression of conventional T cell (Tconv) proliferation. Importantly, compared to the Tim-3^- Treg cells, the Tim-3⁺ Treg cells presented comparable proliferation capacity, but significantly greater expressions of CTLA-4 and LAG-3 and significantly higher capacity to suppress Tconv proliferation. In addition, blocking Tim-3 abrogated IL-2-mediated enhancement of Tim-3⁺ Treg cells. We then investigated the IL-2 level in IA patients, and found that although IA patients and healthy controls presented similar serum IL-2 concentration, the concentrations of IL-1β and TNF-α were significantly higher in IA patients than in healthy controls, signaling a relative reduction in IL-2 abundance. Together, we found that IL-2 could significantly enhance the function of Treg cells from IA patients in a Tim-3-dependent manner.

Inhibition of miR-155 attenuates abdominal aortic aneurysm in mice by regulating macrophage-mediated inflammation

The aim of the present study was to identify abdominal aortic aneurysms (AAA)-associated miR-155 contributing to AAA pathology by regulating macrophage-mediated inflammation. Angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE-/-) mice and THP-1 cells model of miR-155 overexpression and deficiency were used in the experiments. The expression of miR-155 was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cytokines were evaluated using enzyme-linked immunoabsorbent assay (ELISA). Western blotting was used to measure the levels of MMP-2, MMP-9, iNOS, and monocyte chemoattractant protein (MCP)-1 proteins. Immunostaining and transwell were used to determine CD68, elastic collagen, proliferation, and migration of vascular smooth muscle cells (VSMCs). The results showed that miR-155 and cytokines were up-regulated in AAA patients or ApoE-/- mice. Overexpression of miR-155 enhanced MMP-2, MMP-9, iNOS, and MCP-1 levels, and stimulated the proliferation and migration of VSMCs. Meanwhile, inhibition of miR-155 had the opposite effect. In addition, histology demonstrated accumulation of CD68 and elastic collagen-positive areas significantly decreased in miR-155 antagomir injection group. In conclusion, the results of the present study suggest that inhibiting miR-155 is crucial to prevent the development of AAA by regulating macrophage inflammation.

Macrophage Polarization in Cerebral Aneurysm: Perspectives and Potential Targets

Cerebral aneurysms (CAs) have become a health burden not only because their rupture is life threatening, but for a series of devastating complications left in survivors. It is well accepted that sustained chronic inflammation plays a crucial role in the pathology of cerebral aneurysms. In particular, macrophages have been identified as critical effector cells orchestrating inflammation in CAs. In recent years, dysregulated M1/M2 polarization has been proposed to participate in the progression of CAs. Although the pathological mechanisms of M1/M2 imbalance in CAs remain largely unknown, recent advances have been made in the understanding of the molecular basis and other immune cells involving in this sophisticated network. We provide a concise overview of the mechanisms associated with macrophage plasticity and the emerging molecular targets.

Genetic association study identifies a functional CNV in the WWOX gene contributes to the risk of intracranial aneurysms

Intracranial aneurysms (IAs) accounts for 85% of hemorrhagic stroke. Genetic factors have been known to play an important role in the development of IAs. A functional CNV (CNV-67048) of human WW domain-containing oxidoreductase (WWOX), which has been identified as a tumor suppressor gene in multiple cancers, was identified to be associated with gliomas risk previously. Here, we hypothesized that the CNV-67048 could also affect susceptibility of IAs. Based on a two-stage, case⁻ control study with a total of 976 patients of IAs and 1,200 matched healthy controls, we found the effect size for per copy deletion was 1.35 (95% CI = 1.16–1.57; P_trend = 1.18 × 10⁻⁴). Compared with the individuals having no deletion, significantly higher risk of IAs was detected for both subjects carrying 1 copy deletion (OR = 1.24, 95% CI = 1.02–1.52) and subjects carrying 2 copy deletion (OR = 1.77, 95% CI = 1.24–2.53). Real-time PCR was used to confirm the abnormal expression of WWOX in tissues of IA patients and influence of genotypes of CNV-67048. The expression level of WWOX in IA tissues was significantly lower than that in corresponding normal tissues (P = 0.004), and the deletion genotypes of CNV-67048 have lower WWOX mRNA levels in both tumor tissues and border tissues (P < 0.01). Our data suggests that the deletion genotypes of CNV-67048 in WWOX predispose their carriers to IAs, which might be a genetic biomarker to predict risk of IAs in Chinese.

Wall enhancement ratio and partial wall enhancement on MRI associated with the rupture of intracranial aneurysms

Objectives

To evaluate the risk factors for rupture of intracranial aneurysms (IAs) using high resolution MRI (HRMRI).

Methods

91 consecutive patients with 106 IAs were reviewed from February 2016 to April 2017. Patients and IAs were divided into ruptured and unruptured groups. In addition to the clinical characteristics of the patients, the features of IAs (eg, shape) were evaluated by CT angiography, whereas wall thickness, enhanced patterns, and enhancement ratio (ER) were evaluated by MRI. Multiple logistic regression analysis was used to identify independent risk factors associated with the rupture of IAs. Receiver operating characteristic curve analysis was performed on the final model, and the optimal thresholds were obtained.

Results

ER (OR 6.638) and partial wall enhancement (PWE) (OR 6.710) were not markers of aneurysms more prone to rupture, but simply were more commonly found in the ruptured aneurysm cohort. The threshold value for ER was 61.5%.

Conclusions

ER (≥61.5%) and IAs with PWE are better predictors of rupture. Increased attentions should be paid to these factors during assessment of IA rupture.

Elevated High Sensitivity C-Reactive Protein Increases the Risk of Microalbuminuria in Subjects With Cardiovascular Disease Risk Factors

Microalbuminuria is an early biomarker of kidney injury, the aim of this study was to investigate the impact of high sensitivity C-reactive protein (hs-CRP) on microalbuminuria in adults with cardiovascular disease (CVD) risk factors. A total of 5667 subjects who voluntarily attended annual health screenings in the Third Xiangya Hospital of Central South University were included in the study. Logistic regression was used to determine the validity of hs-CRP to predict the presence of microalbuminuria. In the unadjusted regression analysis, male gender (OR 2.23), age (OR 1.71), smoking status (OR 1.48), obesity (OR 2.41), hypertension(OR 4.03), diabetes (OR 4.61), hyperuricemia (OR 1.83), and high hs-CRP(OR 1.61) were associated with microalbuminuria. Multivariate logistic regression analysis showed that the adjusted odds ratios (OR) of diabetes, hypertension, male, abdominal obesity, and high hs-CRP for microalbuminuria were 2.71, 2.57, 1.51, 1.28 and 1.41 in all subjects, respectively (P < 0.01). ROC analysis indicated that the cut-off for hs-CRP with better properties for screening of microalbuminuria was identified as ≥0.85 mg/L. The ORs of microalbuminuria were 1.97, 1.49, 1.32 and 1.71 times in male, abdominal obesity, diabetes and hypertension subjects with hs-CRP ≥ 0.85 mg/L, respectively, compared with those without elevated hs-CRP (P < 0.01). Elevated hs-CRP level was associated with microalbuminuria independent of cardiovascular risk factors. In addition, elevated hs-CRP increased the risk of developing microalbuminuria in subjects with CVD risk factors, indicating that chronic inflammation could amplify the deterioration of kidney by effect of CVD risk factors.

SP600125 Attenuates Nicotine-Related Aortic Aneurysm Formation by Inhibiting Matrix Metalloproteinase Production and CC Chemokine-Mediated Macrophage Migration

Nicotine, a major chemical component of cigarettes, plays a pivotal role in the development of abdominal aortic aneurysm (AAA). c-Jun N-terminal kinase (JNK) has been demonstrated to participate in elastase-induced AAA. This study aimed to elucidate whether the JNK inhibitor SP600125 can attenuate nicotine plus angiotensin II- (AngII-) induced AAA formation and to assess the underlying molecular mechanisms. SP600125 significantly attenuated nicotine plus AngII-induced AAA formation. The expression of matrix metalloproteinase- (MMP-) 2, MMP-9, monocyte chemoattractant protein- (MCP-) 1, and regulated-on-activation, normal T-cells expressed and secreted (RANTES) was significantly upregulated in aortic aneurysm lesions but inhibited by SP600125. In vitro, nicotine induced the expression of MCP-1 and RANTES in both RAW264.7 (mouse macrophage) and MOVAS (mouse vascular smooth muscle) cells in a dose-dependent manner; expression was upregulated by 0.5 ng/mL nicotine but strongly downregulated by 500 ng/mL nicotine. SP600125 attenuated the upregulation of MCP-1 and RANTES expression and subsequent macrophage migration. In conclusion, SP600125 attenuates nicotine plus AngII-induced AAA formation likely by inhibiting MMP-2, MMP-9, MCP-1, and RANTES. The expression of chemokines in MOVAS cells induced by nicotine has an effect on RAW264.7 migration, which is likely to contribute to the development of nicotine-related AAA.

Biology of Saccular Cerebral Aneurysms: A Review of Current Understanding and Future Directions

Understanding the biology of intracranial aneurysms is a clinical quandary. How these aneurysms form, progress, and rupture is poorly understood. Evidence indicates that well-established risk factors play a critical role, along with immunologic factors, in their development and clinical outcomes. Much of the expanding knowledge of the inception, progression, and rupture of intracranial aneurysms implicates inflammation as a critical mediator of aneurysm pathogenesis. Thus, therapeutic targets exploiting this arm of aneurysm pathogenesis have been implemented, often with promising outcomes.

Lymphocytes influence intracranial aneurysm formation and rupture: role of extracellular matrix remodeling and phenotypic modulation of vascular smooth muscle cells

BACKGROUND

Intracranial aneurysms (IA) are increasingly recognized as a disease driven by chronic inflammation. Recent research has identified key mediators and processes underlying IA pathogenesis, but mechanistic understanding remains incomplete. Lymphocytic infiltrates have been demonstrated in patient IA tissue specimens and have also been shown to play an important role in abdominal aortic aneurysms (AAA) and related diseases such as atherosclerosis. However, no study has systematically examined the contribution of lymphocytes in a model of IA.

METHODS

Lymphocyte-deficient (Rag1) and wild-type (WT; C57BL/6 strain) mice were subjected to a robust IA induction protocol. Rates of IA formation and rupture were measured, and cerebral artery tissue was collected and utilized for histology and gene expression analysis.

RESULTS

At 2 weeks, the Rag1 group had significantly fewer IA formations and ruptures than the WT group. Histological analysis of unruptured IA tissue showed robust B and T lymphocyte infiltration in the WT group, while there were no differences in macrophage infiltration, IA diameter, and wall thickness. Significant differences in interleukin-6 (IL-6), matrix metalloproteinases 2 (MMP2) and 9 (MMP9), and smooth muscle myosin heavy chain (MHC) were observed between the groups.

CONCLUSIONS

Lymphocytes are key contributors to IA pathogenesis and provide a novel target for the prevention of IA progression and rupture in patients.