Inflammation and human cerebral aneurysms: current and future treatment prospects

Bacterial DNA in patients with ruptured intracranial aneurysms: Investigating the potential role of periodontal and gut microbiota

BACKGROUND AND OBJECTIVES

Chronic periodontal bacterial infections and disruptions in gut microbiota are responsible for systemic inflammation, which may contribute to the rupture of intracranial aneurysm. This study aimed to assess the presence of bacterial DNA from Fusobacterium nucleatum and Escherichia coli within arterial tissues of intracranial aneurysms.

METHODOLOGY

A comprehensive cross-sectional study was conducted, applying stringent inclusion and exclusion criteria to carefully select the study population from patients admitted to the Division of Neurosurgery at Hospital das Clínicas, University of São Paulo. Samples were collected post-aneurysm microsurgical clipping, preserving their integrity for subsequent DNA extraction. Polymerase chain reaction (PCR) techniques were employed to identify bacterial DNA within these samples.

RESULTS

In total, 36 patient samples underwent a detailed analysis. The presence of Escherichia coli DNA exhibited a statistically significant correlation with the occurrence of ruptured intracranial aneurysms (Qualitative Odds Ratio [OR] 4.3 [1.01 - 23.4] and Quantitative OR 0.99 [0.99-1.0], Student's t-test [P = 0.9]). However, the presence of Fusobacterium nucleatum DNA did not demonstrate a statistically significant correlation with ruptured intracranial aneurysms (Qualitative OR 1.52 [0.4-6.1] and Quantitative OR 0.04 [0.01-5.22 ×108], Student's t-test [P = 0.78]).

CONCLUSION

The identification of Escherichia coli bacterial DNA in arterial tissues was positively associated with the occurrence of ruptured intracranial aneurysms, suggesting a potential role for these microorganisms in aneurysm pathogenesis and rupture. The development of therapeutic and prophylactic strategies can be established through future research endeavors.

Cerebral Aneurysm: Filling the Gap Between Pathophysiology and Nanocarriers

Intracranial aneurysms, characterized by abnormal dilations of cerebral arteries, pose significant health risks due to their potential to rupture, leading to subarachnoid hemorrhage with high mortality and morbidity rates. This paper aim is to explore the innovative application of nanoparticles in treating intracranial aneurysms, offering a promising avenue for enhancing current therapeutic strategies. We took into consideration the pathophysiology of cerebral aneurysms, focusing on the role of hemodynamic stress, endothelial dysfunction, and inflammation in their development and progression. By comparing cerebral aneurysms with other types, such as aortic aneurysms, we identify pathophysiological similarities and differences that could guide the adaptation of treatment approaches. The review highlights the potential of nanoparticles to improve drug delivery, targeting, and efficacy while minimizing side effects. We discuss various nanocarriers, including liposomes and polymeric nanoparticles, and their roles in overcoming biological barriers and enhancing therapeutic outcomes. Additionally, we discuss the potential of specific compounds, such as Edaravone and Tanshinone IIA, when used in conjunction with nanocarriers, to provide neuroprotective and anti-inflammatory benefits. By extrapolating insights from studies on aortic aneurysms, new research directions and therapeutic strategies for cerebral aneurysms are proposed. This interdisciplinary approach underscores the potential of nanoparticles to positively influence the management of intracranial aneurysms, paving the way for personalized treatment options that could significantly improve patient outcomes.

Blockade of the Platelet-Driven CXCL7-CXCR1/2 Inflammatory Axis Prevents Murine Cerebral Aneurysm Formation and Rupture

Platelet aggregation is intimately associated with vascular inflammation and is commonly seen on routine histology studies of cerebral aneurysms. Platelets, when activated, have been shown to augment neutrophil response and the pro-inflammatory cascade. Platelet-neutrophil complexes have been found to aggravate atherosclerosis through a positive feedback loop. We hypothesized that targeting platelet aggregation and downstream inflammation could be used to prevent aneurysm formation and progression. First, we induced cerebral aneurysm formation in a previously described intracranial aneurysm model via carotid artery ligation, hypertension, and stereotactic elastase injection in C57BL/6 mice and analyzed vessels for lesion and thrombus formation. Raybiotech cytokine arrays were used to analyze 96 cytokines in induced murine aneurysms and 120 cytokines in human tissue samples. Cerebral aneurysm formation and inflammatory pathway were then studied in animals treated with IgG2 antibody (control), anti-GpIb antibody (platelet depletion), 1:10 DMSO:PBS (control), clopidogrel, anti-CXCR1/2 small molecule inhibitor, or anti-CXCL7 antibody. Bleeding assays and flow cytometry were used to evaluate platelet function in treated groups. CD31 + platelet aggregates are a common feature in human and mouse cerebral aneurysm specimens. Platelet ablation in mice prevents cerebral aneurysm formation (20% vs 100% in control antibody-treated mice, n = 5 each, p = 0.0476). Mice treated with 1 mg/kg clopidogrel develop significantly less aneurysms than controls (18% vs 73%, n = 11 and 11, respectively, p = 0.03). Semi-quantitative analysis of 96 different cytokines using Raybiotech arrays shows increased protein expression of CXCL7 in murine cerebral aneurysms when compared to controls. Treatment with clopidogrel results in reciprocal decrease in detected CXCL7. Targeting CXCL7-CXCR1/2 axis with 10 mg/kg reparixin (CXCR1/2 antagonist) significantly decreases cerebral aneurysm formation (11% vs 73%, n = 9 and 11, p = 0.0098) while treatment with 10 mg/kg SB225002 tends to decrease aneurysm formation (36% vs 73%, n = 11 vs n = 7, p = 0.11). Lastly, specific antibody blockade against CXCL7 using anti-CXCL7 antibody at 100 ug/mL significantly decreases cerebral aneurysm formation (29% vs 75%, n = 7 vs n = 8, p = 0.046). Platelet inflammation has an important role in cerebral aneurysm formation. Small molecule inhibitors targeting platelet CXCL7-CXCR1/2 inflammatory axis could be used to prevent cerebral aneurysm formation or progression.

Clopidogrel Is Associated with Reduced Likelihood of Aneurysmal Subarachnoid Hemorrhage: a Multi-Center Matched Retrospective Analysis

Maladaptive inflammation underlies the formation and rupture of human intracranial aneurysms. There is a growing body of evidence that anti-inflammatory pharmaceuticals may beneficially modulate this process. Clopidogrel (Plavix) is a commonly used irreversible P2Y12 receptor antagonist with anti-inflammatory activity. In this paper, we investigate whether clopidogrel is associated with the likelihood of aneurysm rupture in a multi-institutional propensity-matched cohort analysis. Patients presenting for endovascular treatment of their unruptured intracranial aneurysms and those presenting with aneurysm rupture between 2015 and 2019 were prospectively identified at two quaternary referral centers. Patient demographics, comorbidities, and medication usage at the time of presentation were collected. Patients taking clopidogrel or not taking clopidogrel were matched in a 1:1 fashion with respect to location, age, smoking status, aneurysm size, aspirin usage, and hypertension. A total of 1048 patients with electively treated aneurysms or subarachnoid hemorrhages were prospectively identified. Nine hundred twenty-one patients were confirmed to harbor aneurysms during catheter-based diagnostic angiography. A total of 172/921 (19%) patients were actively taking clopidogrel at the time of presentation. Three hundred thirty-two patients were matched in a 1:1 fashion. A smaller proportion of patients taking clopidogrel at presentation had ruptured aneurysms than those who were not taking clopidogrel (6.6% vs 23.5%, p < .0001). Estimated treatment effect analysis demonstrated that clopidogrel usage decreased aneurysm rupture risk by 15%. We present, to the best of our knowledge, the first large-scale multi-institutional analysis suggesting clopidogrel use is protective against intracranial aneurysm rupture. It is our hope that these data will guide future investigation, revealing the pathophysiologic underpinning of this association.

Emerging and Current Biologics for the Treatment of Intracranial Aneurysms

The integration of biologics in endovascularly treated intracranial aneurysms is a significant area of focus in an evolving field. By presenting the clinical relevance, pathogenesis, management (historical and current), and emerging biologics themselves, this work provides a broad overview of the current landscape of the biologics under current investigation. Growth factors, cytokines, and biologic-coated coils are compared and described as modalities to increase healing, aneurysm occlusion, and long-term recovery. These emerging biologics may increase the efficacy and durability of less invasive endovascular methods and potentially change standard practice with continued exploration.

Risk factors and predictive indicators of rupture in cerebral aneurysms

Cerebral aneurysms are abnormal dilations of blood vessels in the brain that have the potential to rupture, leading to subarachnoid hemorrhage and other serious complications. Early detection and prediction of aneurysm rupture are crucial for effective management and prevention of rupture-related morbidities and mortalities. This review aims to summarize the current knowledge on risk factors and predictive indicators of rupture in cerebral aneurysms. Morphological characteristics such as aneurysm size, shape, and location, as well as hemodynamic factors including blood flow patterns and wall shear stress, have been identified as important factors influencing aneurysm stability and rupture risk. In addition to these traditional factors, emerging evidence suggests that biological and genetic factors, such as inflammation, extracellular matrix remodeling, and genetic polymorphisms, may also play significant roles in aneurysm rupture. Furthermore, advancements in computational fluid dynamics and machine learning algorithms have enabled the development of novel predictive models for rupture risk assessment. However, challenges remain in accurately predicting aneurysm rupture, and further research is needed to validate these predictors and integrate them into clinical practice. By elucidating and identifying the various risk factors and predictive indicators associated with aneurysm rupture, we can enhance personalized risk assessment and optimize treatment strategies for patients with cerebral aneurysms.

Haemorrhagic Complications After Microsurgical Treatment for Intracranial Aneurysms Under Acetylsalicylic Acid: An Impact Analysis

BACKGROUND

Patients with intracranial aneurysms often have comorbidities that require them to take acetylsalicylic acid (ASA). In recent years, many patients with aneurysms have been prescribed ASA to prevent aneurysm enlargement. ASA is also prescribed to patients with intracranial aneurysms in preparation for surgical revascularization.

METHODS

From 2016 to 2021, 64 patients underwent microsurgical aneurysm clipping without revascularization, and an additional 20 patients underwent extracranial to intracranial (EC-IC) bypass. The following parameters were analysed: the frequency of hemorrhagic complications, the blood loss volume, the duration of surgery and inpatient treatment, the change in hemoglobin level (Hb), hematocrit (Ht), erythrocytes, and clinical outcomes according to the modified Rankin scale (mRS).

RESULTS

At the time of surgery, laboratory-confirmed effect of the ASA was registered in 22 patients (main group). In 42 patients, the ASA was not functional on assay (control group). Hemorrhagic complications were noted in two patients in the ASA group. In both cases, the hemorrhagic component did not exceed 15 ml in volume and did not require additional surgical interventions. Statistical analysis showed no significant differences in hemorrhagic postoperative complications.

CONCLUSION

Taking low doses of acetylsalicylic acid during planned microsurgical clipping of cerebral aneurysms does not affect intraoperative blood loss volume, risk of postoperative hemorrhagic complications, length of stay in the hospital, or functional outcomes.

Peripheral macrophages in the development and progression of structural cerebrovascular pathologies

The human cerebrovascular system is responsible for maintaining neural function through oxygenation, nutrient supply, filtration of toxins, and additional specialized tasks. While the cerebrovascular system has resilience imparted by elaborate redundant collateral circulation from supportive tertiary structures, it is not infallible, and is susceptible to developing structural vascular abnormalities. The causes of this class of structural cerebrovascular diseases can be broadly categorized as 1) intrinsic developmental diseases resulting from genetic or other underlying aberrations (arteriovenous malformations and cavernous malformations) or 2) extrinsic acquired diseases that cause compensatory mechanisms to drive vascular remodeling (aneurysms and arteriovenous fistulae). Cerebrovascular diseases of both types pose significant risks to patients, in some cases leading to death or disability. The drivers of such diseases are extensive, yet inflammation is intimately tied to all of their progressions. Central to this inflammatory hypothesis is the role of peripheral macrophages; targeting this critical cell type may lead to diagnostic and therapeutic advancement in this area. Here, we comprehensively review the role that peripheral macrophages play in cerebrovascular pathogenesis, provide a schema through which macrophage behavior can be understood in cerebrovascular pathologies, and describe emerging diagnostic and therapeutic avenues in this area.

[Analysis of intracranial saccular aneurysm wall: neuroimaging and histopathological correlates]

BACKGROUND

Contrast enhancement of intracranial aneurysm wall during MRI with targeted visualization of vascular wall correlates with previous aneurysm rupture and, according to some data, may be a predictor of further rupture of unruptured aneurysms.

OBJECTIVE

To analyze possible causes of aneurysm contrast enhancement considering morphological data of aneurysm walls.

MATERIAL AND METHODS

The study included 44 patients with intracranial aneurysms who underwent preoperative MRI between November 2020 and September 2022. Each aneurysm was assessed regarding contrast enhancement pattern. Microsurgical treatment of aneurysm was accompanied by resection of its wall for subsequent histological and immunohistochemical analysis regarding thrombosis, inflammation and neovascularization. Specimens were subjected to histological and immunochemical analysis. Immunohistochemical analysis was valuable to estimate inflammatory markers CD68 and CD3, as well as neurovascularization marker SD31.

RESULTS

Aneurysms with contrast-enhanced walls were characterized by higher number of CD3+, CD68+, CD31+ cells and parietal clots. Intensity of contrast enhancement correlated with aneurysm wall abnormalities.

CONCLUSION

Contrast enhancement of aneurysm wall can characterize various morphological abnormalities.

Increased prevalence of blister aneurysm formation during the COVID-19 pandemic

BACKGROUND

Intracranial blister aneurysms are a rare and an historically difficult to treat subset of aneurysms. They are distinct from typical saccular aneurysms with different pathophysiology and treatment options.

METHODS

A prospectively maintained database of subarachnoid hemorrhage patients was queried for those presenting prior to the pandemic (2017-2019), and those presenting during the height of the pandemic in our locality (2021). Aneurysm characteristics and patient demographics associated with rupture risk/formation were collected.

RESULTS

334 aneurysmal subarachnoid hemorrhage patients were reviewed. 86 of these patients presented in 2021, with a statistically significant increase in the proportion of ruptured ICA blister aneurysms as compared to 2017-2019 (7/86, 8% vs 5/248, p = .02). Mean patient age, presenting grade, other aneurysm location proportions, aneurysm size, and incidence of delayed cerebral ischemia were not different between the groups.

CONCLUSIONS

Patients presenting with SAH during the height of the SARS-CoV-2 pandemic in 2021 were more likely to have ICA blister type aneurysms.

Aspirin and growth, rupture of unruptured intracranial aneurysms: A systematic review and meta-analysis

OBJECTIVES

Aspirin has been suggested as a potential therapeutic strategy to prevent the growth and rupture of unruptured intracranial aneurysms (UIAs), but there is still controversy. The aim of this systematic review and meta-analysis is to determine the association between aspirin use and growth, rupture of UIAs.

METHODS

We performed a systematic literature search of electronic databases to identify cohort and case-control studies investigating the relationship between aspirin use and growth or rupture of UIAs. Pooled odds ratio (OR) with corresponding 95% confidence interval (CI) were calculated using a random effects model. Heterogeneity among studies was quantified using the I² statistic, and potential publication bias was assessed using funnel plots. Sensitivity analysis was performed to verify the robustness of the intention-to-treat results. Subgroup analysis was conducted according to the frequency of aspirin use.

RESULTS

We identified 8 studies comprising 10,518 participants. The risk of bias was low to moderate. The pooled estimate showed that aspirin use was associated with a lower likelihood of growth of UIAs (OR = 0.25, 95% CI = 0.11-0.55; p = 0.0005) without statistical heterogeneity (p for Cochran Q statistic = 0.62, I² = 0%). Likewise, aspirin intake also significant decreased 58% risk of intracranial aneurysms rupture (OR = 0.42, 95% CI = 0.29-0.60; p < 0.00001) with moderate heterogeneity (p for Cochran Q statistic = 0.005, I² = 66%). Similar results were observed in the sensitivity analysis. Pooled OR of aspirin frequency subgroup analysis for less than or equal to 2 times per week was 0.82 (95%CI = 0.40-1.72; I² = 0%), for at least 3 times per week to daily was 0.25 (95%CI = 0.12-053; I² = 0%), for daily was 0.59 (95%CI: 0.47-0.74; I² = 0%), and for unknown was 0.26 (95%CI: 0.15-0.45; I² = 51%).

CONCLUSIONS

The results of this systematic review and meta-analysis indicates a beneficial effect of aspirin on growth and rupture of UIAs.

Decreased contrast enhancement on high-resolution vessel wall imaging of unruptured intracranial aneurysms in patients taking aspirin

OBJECTIVE

Inflammation plays an integral role in the formation, growth, and progression to rupture of unruptured intracranial aneurysms (UIAs). Animal and human studies have suggested that, due to its antiinflammatory effect, aspirin (ASA) may decrease the risks of growth and rupture of UIAs. High-resolution vessel wall imaging (HR-VWI) has emerged as a noninvasive method to assess vessel wall inflammation and UIA instability. To the authors' knowledge, to date no studies have found a significant correlation between patient use of ASA and contrast enhancement of UIAs on HR-VWI.

METHODS

The University of Iowa HR-VWI Project database was analyzed. This database is a compilation of data on patients with UIAs who prospectively underwent HR-VWI on a 3T Siemens MRI scanner. The presence of aneurysmal wall enhancement was objectively defined using the aneurysm-to-pituitary stalk contrast ratio (CRstalk). This ratio was calculated by measuring the maximal signal intensity in the aneurysmal wall and the pituitary stalk on postcontrast T1-weighted images. Data on aneurysm size, morphology, and location and patient demographics and comorbidities were collected. Use of ASA was defined as daily intake of ≥ 81 mg during the previous 6 months or longer. Univariate and multivariate logistic regression analyses were performed to determine factors independently associated with increased contrast enhancement of UIAs on HR-VWI.

RESULTS

In total, 74 patients harboring 96 UIAs were included in the study. The mean patient age was 64.7 ± 12.4 years, and 60 patients (81%) were women. Multivariate analysis showed that age (OR 1.12, 95% CI 1.05-1.19), aneurysm size ≥ 7 mm (OR 21.3, 95% CI 4.88-92.8), and location in the anterior communicating, posterior communicating, and basilar arteries (OR 10.7, 95% CI 2.45-46.5) were significantly associated with increased wall enhancement on HR-VWI. On the other hand, use of ASA was significantly associated with decreased aneurysmal wall enhancement on HR-VWI (OR 0.22, 95% CI 0.06-0.83, p = 0.026).

CONCLUSIONS

The study results establish a correlation between use of ASA daily for ≥ 6 months and significant decreases in wall enhancement of UIAs on HR-VWI. The findings also demonstrate that detection of wall enhancement using HR-MRI may be a valuable noninvasive method for assessing aneurysmal wall inflammation and UIA instability.

Rabbit Elastase Aneurysm: Imaging and Histology Correlates for Inflammation and Healing

OBJECTIVE

Aneurysmal subarachnoid hemorrhage remains a devastating event with poorly understood pathophysiology. Previous studies have suggested that aneurysm wall inflammation may play a part in the development and potential rupture of aneurysms. The rabbit elastase aneurysm model is a well-established model, which produces aneurysms closely mimicking human cerebral aneurysms in flow dynamics and histopathology. The primary aim of this study was to correlate inflammatory changes after aneurysm formation using sequential vessel wall imaging with histopathologic analysis. A secondary aim was to evaluate the potential effect of gender and anti-inflammatory treatment with aspirin on this inflammatory response.

METHODS

Twenty-seven New Zealand rabbits underwent surgery to create an aneurysm using elastase infusion at the right common carotid artery origin. Vessel wall imaging and histopathologic analysis was obtained at different time points after aneurysm creation. The rabbits were also randomized by gender and to treatment groups with or without aspirin.

RESULTS

Histopathologic analysis revealed 3 distinct phases after aneurysm formation. These phases were an initial inflammatory phase, followed by a regeneration phase, and finally a connective tissue deposition phase. Vessel wall imaging demonstrated 2 distinct imaging patterns. No appreciable differences were seen in histology or imaging when comparing gender or treatment with aspirin.

CONCLUSIONS

Inflammatory changes induced by the rabbit elastase aneurysm model can be correlated with histopathologic findings and observed on noninvasive vessel wall imaging. This may provide a method to study the inflammatory pathway as it pertains to aneurysmal development and subsequent rupture.

Management of Small Unruptured Intracranial Aneurysms: To Treat or Not to Treat?

Unruptured intracranial aneurysms measuring <7 mm in diameter have become increasingly prevalent due to advances in diagnostic imaging. The most feared complication is aneurysm rupture leading to a subarachnoid hemorrhage. Based on the current literature, the 3 main treatments for an unruptured intracranial aneurysm are conservative management with follow-up imaging, endovascular coiling, or surgical clipping. However, there remains no consensus on the best treatment approach. The natural history of the aneurysm and risk factors for aneurysm rupture must be considered to individualize treatment. Models including population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from a prior aneurysm, site of aneurysm score, Unruptured Intracranial Aneurysm Treatment Score, and advanced neuroimaging can assist physicians in assessing the risk of aneurysm rupture. Macrophages and other inflammatory modulators have been elucidated as playing a role in intracranial aneurysm progression and eventual rupture. Further studies need to be conducted to explore the effects of therapeutic drugs targeting inflammatory modulators.

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.

Increased contrast enhancement of the parent vessel of unruptured intracranial aneurysms in 7T MR imaging

BACKGROUND

Inflammation of the arterial wall may lead to aneurysm formation. The presence of aneurysm enhancement on high-resolution vessel wall imaging (HR-VWI) is a marker of wall inflammation and instability. We aim to determine if there is any association between increased contrast enhancement in the aneurysmal wall and its parent artery.

METHODS

Patients with unruptured intracranial aneurysms (UIAs) prospectively underwent 7T HR-VWI. Regions of interest were selected manually and with a semi-automated protocol based on gradient algorithms of intensity patterns. Mean signal intensities in pre- and post-contrast T1-weighted sequences were adjusted to the enhancement of the pituitary stalk and then subtracted to objectively determine: circumferential aneurysmal wall enhancement (CAWE); parent vessel enhancement (PVE); and reference vessel enhancement (RVE). PVE was assessed over regions located 3- and 5 mm from the aneurysm's neck. RVE was assessed in arteries located in a different vascular territory.

RESULTS

Twenty-five UIAs were analyzed. There was a significant moderate correlation between CAWE and 5 mm PVE (Pearson R=0.52, P=0.008), whereas no correlation was found between CAWE and RVE (Pearson R=0.20, P=0.33). A stronger correlation was found between CAWE and 3 mm PVE (Pearson R=0.78, P<0.001). Intra-class correlation analysis demonstrated good reliability between measurements obtained using semi-automated and manual segmentation (ICC coefficient=0.790, 95% CI 0.58 to 0.90).

CONCLUSION

Parent arteries exhibit higher contrast enhancement in regions closer to the aneurysm's neck, especially in aneurysms≥7 mm. A localized inflammatory/vasculopathic process in the wall of the parent artery may lead to aneurysm formation and growth.

Giant intracranial aneurysm following radiation therapy: literature review with a novel case discussion

BACKGROUND

The aim of this paper is to report the results of our review of the literature of published cases of intracranial aneurysms appearing after radiotherapy, and to present our case to add it to the current literature, in order to discuss the role of inflammation.

METHODS

We searched the PubMed database using combinations of the following MeSH terms: intracranial aneurysm, radiosurgery, radiotherapy, inflammatory changes in aneurysmal walls from 1967 to 2019.

RESULTS

51 studies, for a total cohort of 60 patients, are described. The median latency between the radiation treatment and the diagnosis was 9,83 years, ranging from a minimum of 0,33 to a maximum of 33. The modality of rays' administration was variable, and the dosage ranged from a minimum of 12 grays to a maximum of 177,2 grays. The anterior circulation appeared to be more frequently involved, and the most compromised vessel was the internal carotid artery. Radiation-induced vascular diseases have already been described in literature as well as RT-induced cellular and structural changes such as necrosis, macrophage or mononuclear cell infiltration, and several data support the role of inflammation in the development and remodelling of intracranial aneurysms, that, on one hand, favours them and, on the other, is necessary to their healing after endovascular treatment.

CONCLUSIONS

Our team suggested a new insight in the management of these vascular lesions, which corresponds to a lower threshold when deciding whether or not to treat, and a longer and stricter follow-up.

Intracranial Aneurysm Biomarker Candidates Identified by a Proteome-Wide Study

The scientific basis of intracranial aneurysm (IA) formation, its rupture and further development of cerebral vasospasm is incompletely understood. Aberrant protein expression may drive structural alterations of vasculature found in IA. Deciphering the molecular mechanisms underlying these events will lead to identification of early detection biomarkers and in turn, improved treatment outcomes. To unravel differential protein expression in three clinical subgroups of IA patients: (1) unruptured aneurysm, (2) ruptured aneurysm without vasospasm, (3) ruptured aneurysm who developed vasospasm, we performed untargeted quantitative proteomic analysis of aneurysm tissue and serum samples from three subgroups of IA patients and control subjects. Candidate molecules were then validated in a larger cohort of patients using enzyme-linked immunosorbent assay. A total of 937 and 294 proteins were identified from aneurysm tissue and serum samples, respectively. Several proteins that are known to maintain structural integrity of vasculature were found to be dysregulated in the context of aneurysm. ORM1, a glycoprotein, was significantly upregulated in both tissue and serum samples of unruptured aneurysm patients. We employed a larger cohort of subjects (n = 26) and validated ORM1 as a potential biomarker for screening of unruptured aneurysms. Samples from ruptured aneurysms with vasospasm showed significant upregulation of MMP9, a protease, compared with ruptured aneurysms without vasospasm. We validated MMP9 as a potential biomarker for vasospasm in a larger cohort (n = 52). This study reports the first global proteomic analysis of the entire clinical spectrum of IA. Furthermore, this study suggests ORM1 and MMP9 as potential biomarkers for unruptured aneurysm and cerebral vasospasm, respectively.

Nanotechnology: A Promising Approach for Delivery of Neuroprotective Drugs

Central nervous system (CNS) disorders especially neurodegenerative disorders are the major challenge for public health and demand the great attention of researchers to protect people against them. In past few decades, different treatment strategies have been adopted, but their therapeutic efficacy are not enough and have only shown partial mitigation of symptoms. Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BSCFB) guard the CNS from harmful substances and pose as the major challenges in delivering drugs into CNS for treatment of CNS complications such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), stroke, epilepsy, brain tumors, multiple sclerosis (MS), and encephalitis, etc. Nanotechnology has come out as an exciting and promising new platform of treating neurological disorders and has shown great potential to overcome problems related to the conventional treatment approaches. Molecules can be nanoengineered to carry out multiple specific functions such as to cross the BBB, target specific cell or signaling pathway, respond to endogenous stimuli, and act as a vehicle for gene delivery, support nerve regeneration and cell survival. In present review, the role of nanocarrier systems such as liposomes, micelles, solid lipid nanoparticles (SLNPs), dendrimers, and nanoemulsions for delivery of various neurotherapeutic agents has been discussed, besides this, their mechanism of action, and nanoformulation of different neuroprotective agents like curcumin, edaravone, nerve growth factors in CNS disorders like Alzheimer’s, Parkinsonism, epilepsy, stroke, and brain tumors has been reviewed.

What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review

Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.

Vessel wall imaging in intracranial aneurysms

High-resolution vessel wall imaging (HR-VWI) is becoming a useful tool in the characterization and identification of unstable unruptured brain aneurysms. However, it has not been validated for clinical use. The current evidence on HR-VWI techniques for characterization of brain aneurysms is described in this review. Specific imaging approaches such as aneurysm wall contrast enhancement, MRI-quantitative susceptibility mapping, and 7T MRI are described in detail.

Lipid-based nanosystem of edaravone: development, optimization, characterization and in vitro/in vivo evaluation

Edaravone (EDR) is a well-recognized lipophilic free radical scavenger for diseases including neurodegenerative disease, cardiovascular disease, and cancer. However, its oral use is restricted due to poor oral bioavailability (BA). The aim of present research was to enable its oral use by developing a lipid-based nanosystem (LNS). The components of LNS including oil, surfactants, and co-surfactants were selected based on their potential to maximize the solubilization in gastrointestinal (GI) fluids, reduce its glucuronidation and improve transmembrane permeability. The liquid LNS (L-LNS) with Capryol™ PGMC (Oil), Cremophor® RH 40:Labrasol®:TPGS 1000 (1:0.8:0.2) (Surfactant) and Transcutol P® (Co-surfactant) were optimized to form microemulsion having droplet size (16.25 nm), polydispersity index (0.039), % Transmittance (99.85%), and self-emulsification time (32 s). It significantly improved the EDR loading as well as its metabolism and permeability profile during transport across the GI tract. To overcome the possible drawbacks of L-LNS, Aerosil® 200 was used to formulate solid LNS (S-LNS), and its concentration was optimized based on flow properties. S-LNS possessed all quality attributes of L-LNS confirmed by solid-state characterization, reconstitution ability, and stability study. The dissolution rate of EDR was significantly enhanced with L-LNS and S-LNS in simulated gastric, and intestinal fluids. The pharmacokinetic study revealed significant improvement in relative BA, Cmax, and t1/2 with L-LNS and S-LNS against EDR suspension. Moreover, S-LNS showed superior cellular uptake and neuroprotective effect compared to EDR in SH-SY5Y695 cell line. An appropriate selection of the components of LNS could enable effective oral delivery of challenging therapeutics that are conventionally used by the parenteral administration.

The efficacy of microsurgery in the treatment of cerebral aneurysm rupture and its effect on NF-κB, MCP-1 and MMP-9

The clinical efficacy of microsurgical neck clipping for the treatment of cerebral aneurysm rupture and its effect on serum nuclear factor κ-light-chain-enhancer of activated β cells (NF-κB), monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase-9 (MMP-9) levels were investigated. A total of 56 patients with first occurrence of cerebral aneurysm rupture were enrolled from June 2015 to June 2016. These patients were divided into control (25 patients) and observation groups (31 patients) according to treatment received. The patients in the control group were treated with interventional embolization and extraventricular drainage, while the patients in the observation group were treated with microsurgical neck clipping. Serum NF-κB, MCP-1 and MMP-9 levels were measured by ELISA prior to the operation and at 6 h post-operation. Clinical effects were compared at the 6-month follow-up. There was no significant difference in the success rate of the operation between the two groups (p>0.05). The incidence of complications in the observation group was significantly lower than that in the control group (p<0.05). The Glasgow Outcome Scale score was significantly improved in the observation group (p<0.05) compared with the control group. Serum NF-κB, MMP-9 and MCP-1 were significantly decreased in both groups at 6 and 24 h after operation, but the observational group showed significantly lower levels for all three proteins than the control group (p<0.05). The application of early microsurgical neck clipping for the treatment of cerebral aneurysm rupture can reduce complications and improve clinical prognosis, and this may be related to a decrease in serum inflammatory response-related factors (NF-κB and MCP-1) and MMP-9.