SLC22A17 as a Cell Death-Linked Regulator of Tight Junctions in Cerebral Ischemia.

BACKGROUND: Beyond neuronal injury, cell death pathways may also contribute to vascular injury after stroke. We examined protein networks linked to major cell death pathways and identified SLC22A17 (solute carrier family 22 member 17) as a novel mediator that regulates endothelial tight junctions after ischemia and inflammatory stress. METHODS: Protein-protein interactions and brain enrichment analyses were performed using STRING, Cytoscape, and a human tissue-specific expression RNA-seq database. In vivo experiments were performed using mouse models of transient focal cerebral ischemia. Human stroke brain tissues were used to detect SLC22A17 by immunostaining. In vitro experiments were performed using human brain endothelial cultures subjected to inflammatory stress. Immunostaining and Western blot were used to assess responses in SLC22A17 and endothelial tight junctional proteins. Water content, dextran permeability, and electrical resistance assays were used to assess edema and blood-brain barrier (BBB) integrity. Gain and loss-of-function studies were performed using lentiviral overexpression of SLC22A17 or short interfering RNA against SLC22A17, respectively. RESULTS: Protein-protein interaction analysis showed that core proteins from apoptosis, necroptosis, ferroptosis, and autophagy cell death pathways were closely linked. Among the 20 proteins identified in the network, the iron-handling solute carrier SLC22A17 emerged as the mediator enriched in the brain. After cerebral ischemia in vivo, endothelial expression of SLC22A17 increases in both human and mouse brains along with BBB leakage. In human brain endothelial cultures, short interfering RNA against SLC22A17 prevents TNF-α (tumor necrosis factor alpha)-induced ferroptosis and downregulation in tight junction proteins and disruption in transcellular permeability. Notably, SLC22A17 could repress the transcription of tight junctional genes. Finally, short interfering RNA against SLC22A17 ameliorates BBB leakage in a mouse model of focal cerebral ischemia. CONCLUSIONS: Using a combination of cell culture, human stroke samples, and mouse models, our data suggest that SLC22A17 may play a role in the control of BBB function after cerebral ischemia. These findings may offer a novel mechanism and target for ameliorating BBB injury and edema after stroke.

Microvesicles facilitate the differentiation of mesenchymal stem cells into pancreatic beta-like cells via miR-181a-5p/150-5p.

Transplantation of pancreatic islet cells is a promising strategy for the long-term treatment of type 1 diabetes (T1D). The stem cell-derived beta cells showed great potential as substitute sources of transplanted pancreatic islet cells. However, the current efficiency of stem cell differentiation still cannot match the requirements for clinical transplantation. Here, we report that microvesicles (MVs) from insulin-producing INS-1 cells could induce mesenchymal stem cell (MSC) differentiation into pancreatic beta-like cells. The combination of MVs with small molecules, nicotinamide and insulin-transferrin-selenium (ITS), dramatically improved the efficiency of MSC differentiation. Notably, the function of MVs in MSC differentiation requires their entry into MSCs through giant pinocytosis. The MVs-treated or MVs combined with small molecules-treated MSCs show pancreatic beta-like cell morphology and response to glucose stimulation in insulin secretion. Using high throughput small RNA-sequencing, we found that MVs induced MSC differentiation into the beta-like cells through miR-181a-5p/150-5p. Together, our findings reveal the role of MVs or the MV-enriched miR-181a-5p/150-5p as a class of biocompatible reagents to differentiate MSCs into functional beta-like cells and demonstrate that the combined usage of MVs or miR-181a-5p/150-5p with small molecules can potentially be used in making pancreatic islet cells for future clinical purposes.

CSF lipocalin-2 increases early in subarachnoid hemorrhage are associated with neuroinflammation and unfavorable outcome.

Lipocalin-2 mediates neuro-inflammation and iron homeostasis in vascular injuries of the central nervous system (CNS) and is upregulated in extra-CNS systemic inflammation. We postulate that cerebrospinal fluid (CSF) and blood lipocalin-2 levels are associated with markers of inflammation and functional outcome in subarachnoid hemorrhage (SAH). We prospectively enrolled 67 SAH subjects, serially measured CSF and plasma lipocalin-2, matrix metallopeptidase 9 (MMP-9), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) on post-SAH days 1-5 and assessed outcome by modified Rankin Scale (mRS) every 3 months. Unfavorable outcome is defined as mRS > 2. Twenty non-SAH patients undergoing lumbar drain trial were enrolled as controls. Lipocalin-2 was detectable in the CSF and significantly higher in SAH compared to controls (p < 0.0001). Higher CSF LCN2 throughout post-SAH days 1-5 was associated with unfavorable outcome at 3 (p = 0.0031) and 6 months (p = 0.014). Specifically, higher CSF lipocalin-2 on post-SAH days 3 (p = 0.036) and 5 (p = 0.016) were associated with unfavorable 3-month outcome. CSF lipocalin-2 levels positively correlated with CSF IL-6, TNF-α and MMP-9 levels. Higher plasma lipocalin-2 levels over time were associated with worse 6-month outcome. Additional studies are required to understand the role of lipocalin-2 in SAH and to validate CSF lipocalin-2 as a potential biomarker for SAH outcome.

Surgical timing in infective endocarditis complicated by intracranial hemorrhage.

Given the growing incidence of infective endocarditis (IE), understanding the risks and benefits of valvular surgery is critical. This decision is particularly complex for the 1 in 10 cases complicated by intracranial hemorrhage (ICH). While guideline recommendations currently favor early surgery in general, delayed intervention of at least 4 weeks is still recommended for patients with ICH. To date, there are no randomized controlled trials that inform management of patients with an indication for surgery but concomitant ICH, and even reported observational data are rare. This paper reviews the current literature on timing of surgery with a specific focus on cases of ICH. It emphasizes a growing body of literature challenging the current paradigm that surgery within 4 weeks is associated with neurologic deterioration and high mortality rates by demonstrating favorable outcomes for patients with pre-operative ICH who undergo early valvular surgery. Based on these data, we propose a practical management algorithm to facilitate decisions on surgical timing in these complicated cases. Since more rigorous evidence may never be available, clinicians should make patient-specific surgical timing decisions that attempt to balance the competing risks of neurologic versus cardiac complications.

Differential subnetwork of chemokines/cytokines in human, mouse, and rat brain cells after oxygen-glucose deprivation.

Mice and rats are the most commonly used animals for preclinical stroke studies, but it is unclear whether targets and mechanisms are always the same across different species. Here, we mapped the baseline expression of a chemokine/cytokine subnetwork and compared responses after oxygen-glucose deprivation in primary neurons, astrocytes, and microglia from mouse, rat, and human. Baseline profiles of chemokines (CX3CL1, CXCL12, CCL2, CCL3, and CXCL10) and cytokines (IL-1α, IL-1ß, IL-6, IL-10, and TNFα) showed significant differences between human and rodents. The response of chemokines/cytokines to oxygen-glucose deprivation was also significantly different between species. After 4 h oxygen-glucose deprivation and 4 h reoxygenation, human and rat neurons showed similar changes with a downregulation in many chemokines, whereas mouse neurons showed a mixed response with up- and down-regulated genes. For astrocytes, subnetwork response patterns were more similar in rats and mice compared to humans. For microglia, rat cells showed an upregulation in all chemokines/cytokines, mouse cells had many down-regulated genes, and human cells showed a mixed response with up- and down-regulated genes. This study provides proof-of-concept that species differences exist in chemokine/cytokine subnetworks in brain cells that may be relevant to stroke pathophysiology. Further investigation of differential gene pathways across species is warranted.

Early elevation of serum tumor necrosis factor-α is associated with poor outcome in subarachnoid hemorrhage.

OBJECTIVE: Subarachnoid hemorrhage (SAH) is associated with inflammation that may mediate poor outcome in SAH. We hypothesize that elevated serum tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) are associated with vasospasm and poor outcome in SAH. METHODS: In 52 consecutive SAH subjects, we compared TNF-α and IL-6 levels on post-SAH days 0 to 1, 2 to 3, 4 to 5, 6 to 8, and 10 to 14 with respect to vasospasm and to poor outcome at 3 and 6 months. Vasospasm was defined as more than 50% reduction in vessel caliber on angiography. Poor outcome was defined as modified Rankin score greater than 2. RESULTS: Elevated TNF-α on post-SAH days 2 to 3 was associated with poor 3-month outcome (P = 0.0004). Global elevation of TNF-α over time (post-SAH days 0-14) was independently associated with poor 3-month outcome after adjusting for Hunt-and-Hess grade and age (P = 0.02). Neither cross-sectional nor IL-6 levels over time were associated with outcome. Neither TNF-α nor IL-6 levels were associated with vasospasm. CONCLUSIONS: Elevation in serum TNF-α on post-SAH days 2 to 3 and global elevation of TNF-α over time are associated with poor outcome but not with angiographic vasospasm in this small cohort. Future studies are needed to define the role of TNF-α in SAH-related brain injury and its potential as a SAH outcome biomarker.

Cerebral edema and a transtentorial brain herniation syndrome associated with pandemic swine influenza A (H1N1) virus infection.

Acute encephalitis, encephalopathy, and seizures are known rare neurologic sequelae of respiratory tract infection with seasonal influenza A and B virus, but the neurological complications of the pandemic 2009 swine influenza A (H1N1) virus, particularly in adults, are ill-defined. We document two young adults suffering from H1N1-associated acute respiratory distress syndrome and renal failure who developed cerebral edema. The patients acutely developed a transtentorial brain herniation syndrome including a unilateral third nerve palsy (dilated and unresponsive pupils), elevated intracranial pressure, coma, and radiological evidence of diffuse cerebral edema. In both patients, neurological deterioration occurred in the context of hyponatremia and a systemic inflammatory state. These patients illustrate that severe neurologic complications, including malignant cerebral edema, can occur in adults infected with H1N1 virus, and illustrate the need for close neurological monitoring of potential neurological morbidities in future pandemics.

Spinal dural arteriovenous fistula mimicking prostate hyperplasia.

BACKGROUND: Initially described in 1926, spinal dural arteriovenous fistula remains diagnostically challenging. Presenting symptoms are often common complaints in general practice or the emergency department, such as leg weakness or numbness. One of the less recognized early features is that of sphincteric disturbance. OBJECTIVES: To elucidate the underappreciated early feature of urinary sphincter disturbance in spinal arteriovenous fistula. CASE REPORT: We report on 2 patients with early urinary symptoms that mimicked obstructive uropathy, both of whom sought medical attention on several occasions before the diagnosis was reached. The clinical and imaging findings of spinal dural fistula are discussed. CONCLUSION: Atypical presentations of bladder dysfunction in addition to other neurologic complaints in the appropriate patient population should prompt spinal imaging to exclude a spinal dural fistula. Timely diagnosis and treatment can prevent the progression of spinal cord edema to infarction with paraparesis, and permanent bladder and bowel dysfunction.

Amelioration of inflammation and cytotoxicity by dipyridamole in brain endothelial cells.

BACKGROUND: Increasing evidence suggests that beyond its antiplatelet properties, dipyridamole may have pleiotropic effects on other cells within the neurovascular elements of the brain. In this experimental cellular study, we asked whether dipyridamole can ameliorate brain endothelial injury after exposure to inflammatory and metabolic insults. METHODS: Human brain endothelial cells were grown in culture, and exposed to TNFalpha (continuously for 20 h) or subjected to oxygen-glucose deprivation (OGD; 6 h of insult followed by 18 h recovery). Expression of ICAM-1, VCAM-1 and PECAM-1 were measured by immunoblotting. Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in the conditioned media were quantified via zymography. MTT mitochondrial activity was measured to assess endothelial cell viability. RESULTS: Exposure of human brain endothelial cells to TNFalpha (12.5-50 ng/ml) induced a clear increase in protein levels of ICAM-1, VCAM-1 and MMP-9. TNFalpha did not alter PECAM-1. Dipyridamole (1-5 muM) significantly attenuated ICAM-1 and MMP-9 levels after this inflammatory insult. No significant effects of dipyridamole were noted for VCAM-1. Six-hour OGD induced moderate endothelial cell death accompanied by a release of MMP-9. Dipyridamole significantly decreased MMP-9 levels and cell death after this metabolic insult. CONCLUSIONS: These results suggest that dipyridamole may ameliorate brain endothelial injury after inflammation and/or metabolic insults. How these putative cellular mechanisms may relate to clinical outcomes and conditions in stroke patients remains to be elucidated.