Molecular Basis of Cerebral Vasospasm: What Can We Learn from Transcriptome and Temporal Gene Expression Profiling in Intracranial Aneurysm?

Cerebral vasospasm (CV) is a significant complication following aneurysmal subarachnoid hemorrhage (aSAH), and lacks a comprehensive molecular understanding. Given the temporal trajectory of intracranial aneurysm (IA) formation, its rupture, and development of CV, altered gene expression might be a molecular substrate that runs through these clinical events, influencing both disease inception and progression. Utilizing RNA-Seq, we analyzed tissue samples from ruptured IAs with and without vasospasm to identify the dysregulated genes. In addition, temporal gene expression analysis was conducted. We identified seven dysregulated genes in patients with ruptured IA with vasospasm when compared with those without vasospasm. We found 192 common genes when the samples of each clinical subset of patients with IA, that is, unruptured aneurysm, ruptured aneurysm without vasospasm, and ruptured aneurysm with vasospasm, were compared with control samples. Among these common genes, TNFSF13B, PLAUR, OSM, and LAMB3 displayed temporal expression (progressive increase) with the pathological progression of disease that is formation of aneurysm, its rupture, and consequently the development of vasospasm. We validated the temporal gene expression pattern of OSM at both the transcript and protein levels and OSM emerges as a crucial gene implicated in the pathological progression of disease. In addition, RSAD2 and ATP1A2 appear to be pivotal genes for CV development. To the best of our knowledge, this is the first study to compare the transcriptome of aneurysmal tissue samples of aSAH patients with and without CV. The findings collectively provide new insights on the molecular basis of IA and CV and new leads for translational research.

Comparison of propofol and desflurane for postoperative neurocognitive function in patients with aneurysmal subarachnoid hemorrhage: A prospective randomized trial.

Background: Following aneurysmal subarachnoid hemorrhage, 40-50% of survivors experience cognitive dysfunction, which affects their quality of life. Anesthetic agents play a pivotal role in aneurysm surgeries. However, substantial evidence regarding their effects on neurocognitive function is lacking. This study evaluated the effects of propofol and desflurane on postoperative neurocognitive function and serum S-100B levels. Methods: One hundred patients were equally randomized to receive either propofol (Group P) or desflurane (Group D). Cognitive function was assessed using the Montreal Cognitive Assessment scale at three different time points: Preoperatively, at the time of discharge, and one month after surgery. Perioperative serum levels of S-100B were also measured. Results: The preoperative mean cognitive score in Group P was 21.64 + 4.46 and in Group D was 21.66 + 4.07 (P = 0.79). At discharge, a significant decrease in cognitive scores was observed compared to preoperative scores (Group P- 20.91 + 3.94, P = 0.03 and Group D-19.28 + 4.22, P = 0.00); however, scores were comparable between the two groups (P = 0.09). One month following surgery, mean cognitive scores were 22.63 + 3.57 in Group P and 20.74 + 3.89 in Group D, and the difference was significant (P = 0.04). Higher memory and orientation scores were observed in Group P than in Group D at one month (P < 0.05) in the subgroup analysis. Both groups had similar serum S-100B levels. Conclusion: The mean cognitive scores one month after surgery improved significantly with propofol compared with desflurane, but without clinical significance. Individual domain analysis demonstrated that orientation and memory scores were better preserved with propofol.

Dysregulated Genes and Signaling Pathways in the Formation and Rupture of Intracranial Aneurysm.

Intracranial aneurysm (IA) has the potential to rupture. Despite scientific advances, we are still not in a position to screen patients for IA and identify those at risk of rupture. It is critical to comprehend the molecular basis of disease to facilitate the development of novel diagnostic strategies. We used transcriptomics to identify the dysregulated genes and understand their role in the disease biology. In particular, RNA-Seq was performed in tissue samples of controls, unruptured IA, and ruptured IA. Dysregulated genes (DGs) were identified and analyzed to understand the functional aspects of molecules. Subsequently, candidate genes were validated at both transcript and protein level. There were 314 DGs in patients with unruptured IA when compared to control samples. Out of these, SPARC and OSM were validated as candidate molecules in unruptured IA. PI3K-AKT signaling pathway was found to be an important pathway for the formation of IA. Similarly, 301 DGs were identified in the samples of ruptured IA when compared with unruptured IAs. CTSL was found to be a key candidate molecule which along with Hippo signaling pathway may be involved in the rupture of IA. We conclude that activation of PI3K-AKT signaling pathway by OSM along with up-regulation of SPARC is important for the formation of IA. Further, regulation of Hippo pathway through PI3K-AKT signaling results in the down-regulation of YAP1 gene. This along with up-regulation of CTSL leads to further weakening of aneurysm wall and its subsequent rupture.

Intravenous versus inhalational anesthesia trial for outcome following intracranial aneurysm surgery: A prospective randomized controlled study.

BACKGROUND: For maintenance of anesthesia for intracranial aneurysmal neck clipping, both intravenous and inhalational anesthetics are in vogue. We aimed to evaluate the superiority of one agent over the other for long-term neurological outcomes in these patients. METHODS: This prospective assessor-blind randomized study was conducted in 106 patients of 18-65 years of age with World Federation of Neurosurgeons Grade I-II of subarachnoid hemorrhage. After written informed consent, the patients were randomized into - intravenous group (Propofol) and inhalational group (Desflurane). The primary outcome was to study neurological outcome using Glasgow outcome scale (GOS) at 3 months following discharge while secondary outcomes included intraoperative brain condition, intraoperative hemodynamics, duration of hospital stay, Modified Rankin Score (MRS) at discharge, MRS, and Barthel's index at 3 months following discharge and estimation of perioperative biomarkers of brain injury. RESULTS: The GOS at 3 months was 5 (5.00-5.00) in the propofol group and 5 (4.00-5.00) in the desflurane group (P = 0.24). Both the anesthetics were similar in terms of intraoperative hemodynamics, brain relaxation, duration of hospital stay, MRS at discharge and 3 months, and Barthel Index at 3 months (P > 0.05). The perioperative serum interleukin-6 and S100B were comparable among the groups (P > 0.05). CONCLUSION: The long-term neurological outcome of good grade aneurysm patients undergoing craniotomy and clipping remains comparable with the use of either propofol or desflurane. The effect of the two anesthetic agents on the various clinical parameters and the biomarkers of brain injury is also similar.

Effect of General Anesthetics on Caspase-3 Levels in Patients With Aneurysmal Subarachnoid Hemorrhage: A Preliminary Study.

BACKGROUND: General anesthesia has been associated with neuronal apoptosis and activation of caspases. Apoptosis is a crucial factor in early brain injury following aneurysmal subarachnoid hemorrhage (aSAH). We conducted a double-blind, prospective, randomized pilot study to evaluate the effect of 4 anesthetic agents on cerebrospinal fluid (CSF) and serum caspase-3 levels in aSAH patients. MATERIALS AND METHODS: A total of 44 good-grade aSAH patients with preoperative lumbar drain scheduled for surgical clipping or endovascular coiling were randomized to receive maintenance of anesthesia with propofol, isoflurane, sevoflurane, or desflurane. Caspase-3 levels were measured in CSF and serum samples collected at baseline, 1 hour after induction, and 1 hour after cessation of anesthesia. RESULTS: Compared with baseline, there was a decrease in CSF caspase-3 levels and an increase in serum caspase-3 levels 1 hour after exposure to all 4 anesthetic agents; levels returned to baseline values after cessation of anesthesia. Median CSF caspase-3 levels at baseline, 1 hour after anesthesia exposure, and 1 hour after cessation of anesthesia were 0.0679, 0.0004, and 0.0689 ng/mL, respectively (P<0.05). Median serum caspase-3 levels at baseline, 1 hour after anesthesia exposure, and 1-hour after cessation of anesthesia were 0.0028, 0.0682, and 0.0044 ng/mL, respectively (P<0.05). CONCLUSIONS: Propofol, isoflurane, sevoflurane, or desflurane have similar effects on CSF and serum caspase-3. The reduction of intraoperative CSF caspase-3 levels suggests a possible role for general anesthesia in neuroresuscitation by slowing the neuronal apoptotic pathway.

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.