Abstract WP208: Cd14+ Monocytes Mediate The Immunological Environment In Aneurysmal Subarachnoid Hemorrhage Through Cxcl10 Secretion

Introduction: Robust evidence suggest that aneurysmal subarachnoid hemorrhage (aSAH) triggers a potent respone from innate and adaptive inmunities. An increase in CD8+CD161+ cells has been observed in the acute phase of patients with aSAH. However, the role of this cells is poorly understood.

Methods: Cerebrospinal fluid of patients with aSAH and non-aneurysmal SAH (nasSAH) was analyzed. Single cell RNA sequencing (scRNAseq) of CD8+CD161+ cells sorted from the CSF of patients with aSAH was performed. Specific cell populations were identified based on gene clustering. Additionaly ten genes were identified. The levels of these genes were then quantified with real-time quantitative polymerase chain reaction (RT- qPCR) and were compared in patients with aSAH and patients with naSAH. Finally highly expressed proteins were quantified with ELISA.

Results: Gene clustering suggested that CD14+ monocytes, NK cells and T cells expressed CD8+CD161+ in the CSF of patients with aSAH. Ten differentially expressed genes of clinical interest were then identified: CCL55, CCL7, APOE, SPP1, CXCL8, CXCL10, HMOX1, LTB, MAL, HLA-DRA1/HLA-DRB1 and their mRNA levels were quantied. CXCL10 and HMOX1 levels were higher in aSAH samples than in naSAH (p=0.02 and p=0.076, respectively). CXCL10 was the most significantly different expressed gene in aSAH compared to naSAH samples, and it was chosen for further analysis with ELISA. Protein levels of CXCL10 were higher in patients with aSAH [median(IQR) = 598(635) pg/mL] compared to patients with naSAH [median(IQR) = 31(214) pg/mL, p=0.04].

Conclusion: CD14+ monocytes, NK cells and T cells are CD8+CD161+ in patients with aSAH. CD14+ may be involved in the inflammatory response after aSAH through the expression of the pro-inflammatory cytokine CXCL10.

Abstract WP133: Assessing Aneurysmal Rupture Outcomes Using Automated Quantification Of Hemorrhage Volume

Introduction: Hemorrhage volume affects the risk of developing complications after aneurysmal subarachnoid hemorrhage (aSAH). This volume is quantified subjectively through the Fisher Scale. We developed an automated method to quantify intracranial hemorrhage and determine the risk of complications after aSAH.

Methods: CT scans of patients with aSAH were analyzed. An image-processing algorithm was designed in MATLAB to quantify aSAH volume. The automated algorithm was developed with region-growing and 3D k-means clustering. Two independent raters manually measured hemorrhage volumes using PACS and correlated these measurements with the algorithm measurements in ten patients. Vasospasm and hydrocephalus were identified through chart and imaging review. Hydrocephalus was adjudicated as ventricular enlargement in the setting of aSAH. ROC analysis was performed to evaluate the association between blood volume and the incidence of vasospasm, hydrocephalus and need for a permanent ventriculoperitoneal (VP) shunt.

Results: One hundred and forty-one patients were included in the analysis. The intraclass coefficient correlation (ICC) for inter-rater agreement in PACS was 0.988 (p < 0.001). The ICC for comparing automated versus manual volumes was 0.966 (p < 0.001). Bland-Altman analysis reported a mean difference of -3.14 mL between automated and manual measurements. Hemorrhage volume discriminated for the development of vasospasm (AUC = 0.692), hydrocephalus (AUC = 0.775), and need of permanent VP shunt (AUC = 0.669).

Conclusion: Vasospasm and hydrocephalus were associated with higher volume of aSAH. Patients with higher volume of aSAH at presentation were more likely to require a permanent VP shunt. An objective method to automatically measure aSAH volume can aid in assessing risk of complications among patients with aSAH.

An Assessment of Globe Position Dynamics following Transcranial Lateral and Superior Orbital Wall Resections without Rigid Reconstruction: A Case Series of 55 Patients

Background  There is no consensus exists regarding which reconstructive approach, if any, should be used after performing transcranial lateral orbital wall resections. Rigid reconstruction is often done to prevent enophthalmos; however, it is not clear if this is a risk with extensive orbital wall resections for transcranial surgery. Objective  To assess globe position dynamics in patients that underwent transcranial lateral and superior orbital wall resections without rigid reconstruction to determine if enophthalmos is a significant risk. Methods  Preoperative (PO) and postoperative data were retrospectively collected from the electronic medical records of 55 adult patients undergoing lateral and superior orbital wall resections as part of a skull base approach. The globe positions were assessed radiologically at all available time points and used to track relative globe displacements over time. Results  An evaluation of PO variables identified a relationship between maximum lesion diameters and globe positions dynamics. The composition of globe position presentations in the population remained relatively stable over time, with only 1 out of 55 patients (1.81%) developing postoperative enophthalmos. An assessment of mean globe displacements revealed improvements in the patients presenting with PO exophthalmos, and stability in the patients presenting with normal PO globe positions. Conclusions  Excellent results in long-term postoperative globe position dynamics can be achieved without the use of rigid reconstruction after transcranial lateral and superior orbital wall resections, regardless of the PO globe positioning.

Glucocorticoids Target Ependymal Glia and Inhibit Repair of the Injured Spinal Cord

Following injury, the mammalian spinal cord forms a glial scar and fails to regenerate. In contrast, vertebrate fish spinal cord tissue regenerates significantly to restore function. Cord transection in zebrafish (Danio rerio) initially causes paralysis and neural cell death. Subsequently, ependymal glia proliferate, bipolar glia extend across the lesion, and new neurons are born; axons from spared and nascent neurons extend along trans-lesional glial bridges to restore functional connectivity. Here we report that glucocorticoids, used in the clinical management of spinal cord injury, directly inhibit neural repair by targeting ependymal glia independently of hematogenous cells and microglia. After transecting injury, the glucocorticoid receptor in ependymal glia is regulated differentially in zebrafish (becoming inactive) vs. the rat (becoming active). Glucocorticoid blockade of neural regeneration via a direct effect on ependymal glia has important therapeutic implications for the putative benefit of corticosteroids in early management of spinal cord injury.

Novel zebrafish behavioral assay to identify modifiers of the rapid, nongenomic stress response

When vertebrates face acute stressors, their bodies rapidly undergo a repertoire of physiological and behavioral adaptations, which is termed the stress response. Rapid changes in heart rate and blood glucose levels occur via the interaction of glucocorticoids and their cognate receptors following hypothalamic-pituitary-adrenal axis activation. These physiological changes are observed within minutes of encountering a stressor and the rapid time domain rules out genomic responses that require gene expression changes. Although behavioral changes corresponding to physiological changes are commonly observed, it is not clearly understood to what extent hypothalamic-pituitary-adrenal axis activation dictates adaptive behavior. We hypothesized that rapid locomotor response to acute stressors in zebrafish requires hypothalamic-pituitary-interrenal (HPI) axis activation. In teleost fish, interrenal cells are functionally homologous to the adrenocortical layer. We derived eight frameshift mutants in genes involved in HPI axis function: two mutants in exon 2 of mc2r (adrenocorticotropic hormone receptor), five in exon 2 or 5 of nr3c1 (glucocorticoid receptor [GR]) and two in exon 2 of nr3c2 (mineralocorticoid receptor [MR]). Exposing larval zebrafish to mild environmental stressors, acute changes in salinity or light illumination, results in a rapid locomotor response. We show that this locomotor response requires a functioning HPI axis via the action of mc2r and the canonical GR encoded by nr3c1 gene, but not MR (nr3c2). Our rapid behavioral assay paradigm based on HPI axis biology can be used to screen for genetic and environmental modifiers of the hypothalamic-pituitary-adrenal axis and to investigate the effects of corticosteroids and their cognate receptor interactions on behavior.

Apoplectic Silent Crooke Cell Adenoma with Adjacent Pseudoaneurysms: Causation or Bystander?

BACKGROUND

Crooke cell adenomas (CCAs) are rare and potentially aggressive pituitary tumors that often invade the cavernous sinuses. Although clinical presentations of pituitary tumors may include the development of accompanying intracranial aneurysms, there are no documented cases of coexistent intracranial aneurysms and CCAs to date. Herein we describe an apoplectic silent CCA that presented with adjacent cavernous internal carotid artery (ICA) aneurysms.

CASE DESCRIPTION

A 45-year old male patient presented for evaluation of headaches and diplopia. Subsequent imaging series revealed a hemorrhagic pituitary macroadenoma that had invaded the left cavernous sinus and circumferentially involved the ICA. Two pseudoaneurysms were visualized along regions of the ICA directly attached to the tumor. A transnasal transsphenoidal endoscopic approach was used for resection of the tumor, which was identified histologically as a CCA. Endocrine evaluations characterized the tumor as nonfunctional. The patient experienced an excellent recovery with resolution of related symptoms. A pseudoaneurysm was treated with a Pipeline embolization device; however, it persisted at last follow-up.

CONCLUSIONS

CCAs are a poorly characterized and rare pituitary tumor type. In this case, an apoplectic silent CCA invaded the left cavernous sinus and presented with pseudoaneurysms along its involvement of the ICA. Accordingly, the authors speculated that the invasive qualities of this silent corticotroph adenoma may have directly contributed to the development of these aneurysms.

The endocannabinoid gene faah2a modulates stress-associated behavior in zebrafish

The ability to orchestrate appropriate physiological and behavioral responses to stress is important for survival, and is often dysfunctional in neuropsychiatric disorders that account for leading causes of global disability burden. Numerous studies have shown that the endocannabinoid neurotransmitter system is able to regulate stress responses and could serve as a therapeutic target for the management of these disorders. We used quantitative reverse transcriptase-polymerase chain reactions to show that genes encoding enzymes that synthesize (abhd4, gde1, napepld), enzymes that degrade (faah, faah2a, faah2b), and receptors that bind (cnr1, cnr2, gpr55-like) endocannabinoids are expressed in zebrafish (Danio rerio). These genes are conserved in many other vertebrates, including humans, but fatty acid amide hydrolase 2 has been lost in mice and rats. We engineered transcription activator-like effector nucleases to create zebrafish with mutations in cnr1 and faah2a to test the role of these genes in modulating stress-associated behavior. We showed that disruption of cnr1 potentiated locomotor responses to hyperosmotic stress. The increased response to stress was consistent with rodent literature and served to validate the use of zebrafish in this field. Moreover, we showed for the first time that disruption of faah2a attenuated the locomotor responses to hyperosmotic stress. This later finding suggests that FAAH2 may be an important mediator of stress responses in non-rodent vertebrates. Accordingly, FAAH and FAAH2 modulators could provide distinct therapeutic options for stress-aggravated disorders.

Elucidating cannabinoid biology in zebrafish (Danio rerio)

The number of annual cannabinoid users exceeds 100,000,000 globally and an estimated 9% of these individuals will suffer from dependency. Although exogenous cannabinoids, like those contained in marijuana, are known to exert their effects by disrupting the endocannabinoid system, a dearth of knowledge exists about the potential toxicological consequences on public health. Conversely, the endocannabinoid system represents a promising therapeutic target for a plethora of disorders because it functions to endogenously regulate a vast repertoire of physiological functions. Accordingly, the rapidly expanding field of cannabinoid biology has sought to leverage model organisms in order to provide both toxicological and therapeutic insights about altered endocannabinoid signaling. The primary goal of this manuscript is to review the existing field of cannabinoid research in the genetically tractable zebrafish model-focusing on the cannabinoid receptor genes, cnr1 and cnr2, and the genes that produce enzymes for synthesis and degradation of the cognate ligands anandamide and 2-arachidonylglycerol. Consideration is also given to research that has studied the effects of exposure to exogenous phytocannabinoids and synthetic cannabinoids that are known to interact with cannabinoid receptors. These results are considered in the context of either endocannabinoid gene expression or endocannabinoid gene function, and are integrated with findings from rodent studies. This provides the framework for a discussion of how zebrafish may be leveraged in the future to provide novel toxicological and therapeutic insights in the field of cannabinoid biology, which has become increasingly significant given recent trends in cannabis legislation.

A transgenic zebrafish model for monitoring glucocorticoid receptor activity

Gene regulation resulting from glucocorticoid receptor and glucocorticoid response element interactions is a hallmark feature of stress response signaling. Imbalanced glucocorticoid production and glucocorticoid receptor activity have been linked to socioeconomically crippling neuropsychiatric disorders, and accordingly there is a need to develop in vivo models to help understand disease progression and management. Therefore, we developed the transgenic SR4G zebrafish reporter line with six glucocorticoid response elements used to promote expression of a short half-life green fluorescent protein following glucocorticoid receptor activation. Herein, we document the ability of this reporter line to respond to both chronic and acute exogenous glucocorticoid treatment. The green fluorescent protein expression in response to transgene activation was high in a variety of tissues including the brain, and provided single-cell resolution in the effected regions. The specificity of these responses is demonstrated using the partial agonist mifepristone and mutation of the glucocorticoid receptor. Importantly, the reporter line also modeled the temporal dynamics of endogenous stress response signaling, including the increased production of the glucocorticoid cortisol following hyperosmotic stress and the fluctuations of basal cortisol concentrations with the circadian rhythm. Taken together, these results characterize our newly developed reporter line for elucidating environmental or genetic modifiers of stress response signaling, which may provide insights to the neuronal mechanisms underlying neuropsychiatric disorders such as major depressive disorder.

An automated climbing apparatus to measure chemotherapy-induced neurotoxicity in Drosophila melanogaster

We have developed a novel model system in Drosophila melanogaster to study chemotherapy-induced neurotoxicity in adult flies. Neurological deficits were measured using a manual geotactic climbing assay. The manual assay is commonly used; however, it is laborious, time-consuming, subject to human error and limited to observing one sample at a time. We have designed and built a new automated fly-counting apparatus that uses a "video capture-particle counting technology" to automatically measure 10 samples at a time, with 20 flies per sample. Climbing behavior was assessed manually, as in our previous studies, and with the automated apparatus within the same experiment yielding statistically similar results. Both climbing endpoints as well as the climbing rate can be measured in the apparatus, giving the assay more versatility than the manual assay. Automation of our climbing assay reduces variability, increases productivity and enables high throughput drug screens for neurotoxicity.

In vivo genome editing using a high-efficiency TALEN system

The zebrafish (Danio rerio) is increasingly being used to study basic vertebrate biology and human disease using a rich array of in vivo genetic and molecular tools. However, the inability to readily modify the genome in a targeted fashion has been a bottleneck in the field. Here we show that improvements in artificial transcription activator-like effector nucleases (TALENs) provide a powerful new approach for targeted zebrafish genome editing and functional genomic applications^1–5. Using the GoldyTALEN modified scaffold and zebrafish delivery system, we show this enhanced TALEN toolkit demonstrates a high efficiency in inducing locus-specific DNA breaks in somatic and germline tissues. At some loci, this efficacy approaches 100%, including biallelic conversion in somatic tissues that mimics phenotypes seen using morpholino (MO)-based targeted gene knockdowns⁶. With this updated TALEN system, we successfully used single-stranded DNA (ssDNA) oligonucleotides (oligos) to precisely modify sequences at predefined locations in the zebrafish genome through homology-directed repair (HDR), including the introduction of a custom-designed EcoRV site and a modified loxP (mloxP) sequence into somatic tissue in vivo. We further show successful germline transmission of both EcoRV and mloxP engineered chromosomes. This combined approach offers the potential to model genetic variation as well as to generate targeted conditional alleles.