Arginase-1 Released into CSF After Aneurysmal Subarachnoid Hemorrhage Decreases Arginine/Ornithine Ratio: a Novel Prognostic Biomarker

Impact of human serum albumin level on symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

To investigate the impact of human serum albumin (HSA) levels on symptomatic cerebral vasospasm (SCVS) in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

We retrospectively reviewed the medical records. SCVS was defined as the development of a new neurological deterioration when the cause was considered to be ischemia attributable to vasospasm after other possible causes of worsening had been excluded. The aSAH patients were divided into two groups: those with SCVS (group 1) and those without SCVS (group 2). The HSA level data on the 1st, 2nd, and 3rd day after admission was collected. Multivariate logistical regression and receiver operating characteristic (ROC) analysis were performed to evaluate the ability of HSA level to predict the development of SCVS.

RESULTS

A total of 270 patients were included in our study, of which 74 (27.4%) developed SCVS. The average and lowest HSA levels were lower in group 1 (P < 0.001). In univariate logistic regression, white blood cell count, neutrophil count, and average and lowest HSA levels were associated with SCVS. After adjustment for age, CT Fisher grade, Hunt-Hess grade, and WFNS grade, both the average and lowest HSA levels remained independent predictors of SCVS (P < 0.001). The CT Fisher grade was confirmed to be an independent predictor of SCVS across each model. ROC analysis revealed that the lowest HSA level was a better predictor for SCVS than average HSA level and CT Fisher grade.

CONCLUSION

Clinicians are encouraged to measure HSA levels for the first 3 days after admission to predict the occurrence of SCVS after aSAH.

Arc regulates brain damage and neuroinflammation via Sirt1 signaling following subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) accounts for only 5 % of all stroke cases, but carries a heavy burden of morbidity and mortality. Activity regulated cytoskeleton associated protein (Arc) is an immediate early gene (IEG)-coded postsynaptic protein that is involved in synaptic plasticity. Increasing evidence and our previous studies have shown that Arc might be involved in the pathological mechanism of various neurological diseases, such as traumatic brain injury (TBI). In this study, we investigated the level of Arc in cerebrospinal fluids (CSF) of aSAH patients and its potential role in brain damage following experimental SAH model. We found that the levels of Arc in aSAH patients' CSF positively correlated with Hunt-Hess (H&H) grades. Knockdown of endogenous Arc expression by small interfere RNA (siRNA) significantly increased brain edema and oxidative stress following SAH. The results of immunostaining in brain sections showed that knockdown of Arc enhanced activation of microglia and astrocytes. In congruent, generation of inflammatory cytokines following SAH was increased by Si-Arc transfection. The results of western blot analysis showed that knockdown of Arc inhibited the expression of Sirt1 and Nrf2, which was accompanied by decreased enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px). In addition, activation of sirtuin 1 (Sirt1) via agonist SRT2104 markedly decreased the brain damage and neuroinflammation induced by Arc knockdown. In conclusion, knockdown of endogenous Arc could aggravate brain damage and neuroinflammation following experimental SAH, and Arc levels in aSAH patients' CSF might be a potential indicator of brain damage and prognosis.

Biomarkers in aneurysmal subarachnoid hemorrhage: A short review

Poor outcomes of aneurysmal subarachnoid hemorrhage (aSAH) can be the result of the initial catastrophic event or the many acute or delayed neurological complications. Recent evidence suggests that some molecules play a critical role in both events, through some unknown pathways involved. Understanding the role of these molecules in these events could allow to improve diagnostic accuracy, guide management, and prevent long-term disability in aSAH. Here we present the studies on aSAH biomarkers present in current medical literature, highlighting their roles and main results.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

Additive prognostic impact of the cerebrospinal fluid arginine/ornithine ratio to established clinical scores in aneurysmal subarachnoid hemorrhage

Cerebrospinal fluid (CSF) metabolites are increasingly recognized as prognostic factors in aneurysmal subarachnoid hemorrhage (SAH). The CSF arginine/ornithine ratio (Arg/Orn) was shown to predict cerebral vasospasms and clinical outcome in SAH. The additive prognostic value of Arg/Orn over established prognostic scores has not been investigated. CSF Arg/Orn and the established prognostic scores SAH, FRESH, SAH-PDS, HAIR, Rosen-McDonald, Hunt and Hess, WFNS and modified Fisher scale were determined in a prospective cohort of patients with aneurysmal SAH. Logistic regression models to predict a favorable outcome, defined as a modified Rankin Scale score of 0-3 at 3  months follow-up, were constructed for each score, both with and without the addition of Arg/Orn. The impact of Arg/Orn was assessed comparing logistic regression models containing the respective score with and without Arg/Orn with the likelihood ratio chi-squared test. CSF Arg/Orn and clinical scores were determined in 38 SAH patients. Arg/Orn was an independent predictor of clinical outcome when added to established prognostic scores (p < 0.05) with the exception of HAIR (p = 0.078). All models were significantly improved if Arg/Orn was added as a covariable (p < 0.05). The results of this study confirm Arg/Orn as an independent prognostic factor and its addition improves established prognostic models in SAH.

Human Borna disease virus 1 encephalitis shows marked pro-inflammatory biomarker and tissue immunoactivation during the course of disease

Human Borna disease virus 1 (BoDV-1) encephalitis is a severe emerging disease with a very high case-fatality rate. While the clinical disease, case definitions, diagnostic algorithms and neuropathology have been described, very little is known about the immunological processes of human BoDV-1 encephalitis. Here, we analyzed serum and cerebrospinal fluid (CSF) samples from 10 patients with fatal BoDV-1 encephalitis for changes of different cytokines, chemokines, growth factors and other biomarkers over time. From one of these individuals, also autoptic formalin-fixed brain tissue was analyzed for the expression of inflammatory biomarkers by mRNA levels and immunostaining; in a further patient, only formalin-fixed brain tissue was available and examined in addition. A marked and increasing immune activation from the initial phase to the last phase of acute BoDV-1 encephalitis is shown in serum and CSF, characterized by cytokine concentration changes (IFNγ, IL-5, IL-6, IL-9, IL-10, IL-12p40, IL-13, IL-18, TGF-β1) with a predominantly pro-inflammatory pattern over time. IFNγ production was demonstrated in endothelial cells, astrocytes and microglia, IL-6 in activated microglia, and TGF-β1 in endothelial cells, activated astrocytes and microglia. This was paralleled by an increase of chemokines (CCL-2, CCL-5, CXCL-10, IL-8) to attract immune cells to the site of infection, contributing to inflammation and tissue damage. Pathologically low growth factor levels (BDNF, β-NGF, PDGF) were seen. Changed levels of arginase and sTREM further fostered the pro-inflammatory state. This dysbalanced, pro-inflammatory state likely contributes importantly to the fatal outcome of human BoDV-1 encephalitis, and might be a key target for possible treatment attempts.