Pericyte, but not astrocyte, hypoxia inducible factor-1 (HIF-1) drives hypoxia-induced vascular permeability in vivo.

Background: Ways to prevent disease-induced vascular modifications that accelerate brain damage remain largely elusive. Improved understanding of perivascular cell signalling could provide unparalleled insight as these cells impact vascular stability and functionality of the neurovascular unit as a whole. Identifying key drivers of astrocyte and pericyte responses that modify cell-cell interactions and crosstalk during injury is key.

Pericyte hypoxia-inducible factor-1 (HIF-1) drives blood-brain barrier disruption and impacts acute ischemic stroke outcome.

Pericytes play essential roles in blood-brain barrier integrity and their dysfunction is implicated in neurological disorders such as stroke although the underlying mechanisms remain unknown. Hypoxia-inducible factor-1 (HIF-1), a master regulator of injury responses, has divergent roles in different cells especially during stress scenarios. On one hand HIF-1 is neuroprotective but on the other it induces vascular permeability.

Transcryptomic Analysis of Human Brain-Microvascular Endothelial Response to -Pericytes: Cell Orientation Defines Barrier Function.

Pericytes facilitate blood-brain barrier (BBB) integrity; however, the mechanisms involved remain unclear. Hence, using co-cultures of human cerebral microvascular endothelial cells (ECs) and vascular pericytes (PCs) in different spatial arrangements, as well as PC conditioned media, we investigated the impact of PC-EC orientation and PC-derived soluble factors on EC barrier function. We provide the first evidence that barrier-inducing properties of PCs require basolateral contact with ECs.

Astrocyte-specific hypoxia-inducible factor 1 (HIF-1) does not disrupt the endothelial barrier during hypoxia in vitro.

Background: Astrocytes (AC) are essential for brain homeostasis. Much data suggests that AC support and protect the vascular endothelium, but increasing evidence indicates that during injury conditions they may lose their supportive role resulting in endothelial cell activation and BBB disturbance. Understanding the triggers that flip this switch would provide invaluable information for designing new targets to modulate the brain vascular compartment.

HIF-1α is involved in blood-brain barrier dysfunction and paracellular migration of bacteria in pneumococcal meningitis.

Bacterial meningitis is a deadly disease most commonly caused by Streptococcus pneumoniae, leading to severe neurological sequelae including cerebral edema, seizures, stroke, and mortality when untreated. Meningitis is initiated by the transfer of S. pneumoniae from blood to the brain across the blood-cerebrospinal fluid barrier or the blood-brain barrier (BBB).

Astrocyte glutathione maintains endothelial barrier stability.

Blood-brain barrier (BBB) impairment clearly accelerates brain disease progression. As ways to prevent injury-induced barrier dysfunction remain elusive, better understanding of how BBB cells interact and modulate barrier integrity is needed. Our metabolomic profiling study showed that cell-specific adaptation to injury correlates well with metabolic reprogramming at the BBB.

Furin inhibition prevents hypoxic and TGFβ-mediated blood-brain barrier disruption.

Hypoxic blood-brain barrier (BBB) dysfunction is a common feature of CNS diseases however mechanisms underlying barrier disturbance are still largely unknown. This study investigated the role of transforming growth factor β (TGFβ), a cytokine known to induce expression of the proprotein convertase Furin, in hypoxia-mediated barrier compromise. We show that exposure of brain endothelial cells (ECs) to hypoxia (1% O) rapidly stimulates their migration.

Developmental expression patterns of erythropoietin and its receptor in mouse brainstem respiratory regions.

Erythropoietin (EPO) is a hypoxia-inducible hormone, classically known to enhance red blood cell production upon binding its receptor (EPOR) present on the surface of the erythroid progenitor cells. EPO and its receptor are also expressed in the central nervous system (CNS), exerting several non-hematopoietic actions. EPO also plays an important role in the control of breathing.

Temporary portal vein embolization is as efficient as permanent portal vein embolization in mice.

Background: Temporary portal vein embolization may be a safe alternative to permanent portal vein embolization. Such a new approach could be applied in living-related liver transplantation to increase graft volume before procurement. The impact of temporary portal vein embolization on occluded liver after recanalization, however, has never been assessed.

Direct interaction of beta-amyloid with Na,K-ATPase as a putative regulator of the enzyme function.

By maintaining the Na(+) and K(+) transmembrane gradient mammalian Na,K-ATPase acts as a key regulator of neuronal electrotonic properties. Na,K-ATPase has an important role in synaptic transmission and memory formation. Accumulation of beta-amyloid (Aβ) at the early stages of Alzheimer's disease is accompanied by reduction of Na,K-ATPase functional activity.

Temporal Rac1 - HIF-1 crosstalk modulates hypoxic survival of aged neurons.

Neurodegenerative diseases are frequently associated with hypoxic conditions. During hypoxia the neuronal cytoskeleton is rapidly reorganized and such abnormalities are directly linked to adverse outcomes. Besides their roles as master regulators of the cytoskeleton, the Rho GTPases are also involved in cellular processes stimulated by hypoxic stress.

1-Deoxysphingolipid-induced neurotoxicity involves N-methyl-d-aspartate receptor signaling.

1-Deoxysphingolipids (1-deoxySL) are atypical and neurotoxic sphingolipids formed by alternate substrate usage of the enzyme serine-palmitoyltransferase. Pathologically increased 1-deoxySL formation causes hereditary sensory and autosomal neuropathy type 1 (HSAN1) - a progressive peripheral axonopathy. However, the underlying molecular mechanisms by which 1-deoxySL acts are unknown.

Differential responses of blood-brain barrier associated cells to hypoxia and ischemia: a comparative study.

Background: Undisturbed functioning of the blood-brain barrier (BBB) crucially depends on paracellular signaling between its associated cells; particularly endothelial cells, pericytes and astrocytes. Hypoxic and ischemic injuries are closely associated with disturbed BBB function and the contribution of perivascular cells to hypoxic/ischemic barrier regulation has gained increased attention. Regardless, detailed information on the basal hypoxic/ischemic responses of the barrier-associated cells is rare and the outcome of such cell-specific responses on BBB modulation is not well understood.

Cytokine-induced sleep: Neurons respond to TNF with production of chemokines and increased expression of Homer1a in vitro.

Interactions of neurons with microglia may play a dominant role in sleep regulation. TNF may exert its somnogeneic effects by promoting attraction of microglia and their processes to the vicinity of dendrites and synapses. We found TNF to stimulate neurons (i) to produce CCL2, CCL7 and CXCL10, chemokines acting on mononuclear phagocytes and (ii) to stimulate the expression of the macrophage colony stimulating factor (M-CSF/Csf1), which leads to elongation of microglia processes.

Deoxysphingolipids, novel biomarkers for type 2 diabetes, are cytotoxic for insulin-producing cells.

Irreversible failure of pancreatic β-cells is the main culprit in the pathophysiology of diabetes, a disease that is now a global epidemic. Recently, elevated plasma levels of deoxysphingolipids, including 1-deoxysphinganine, have been identified as a novel biomarker for the disease. In this study, we analyzed whether deoxysphingolipids directly compromise the functionality of insulin-producing Ins-1 cells and primary islets.

Hypoxia selectively disrupts brain microvascular endothelial tight junction complexes through a hypoxia-inducible factor-1 (HIF-1) dependent mechanism.

The blood-brain barrier (BBB) constitutes a critical barrier for the maintenance of central nervous system homeostasis. Brain microvascular endothelial cells line the vessel walls and express tight junction (TJ) complexes that restrict paracellular passage across the BBB, thereby fulfilling a crucial role in ensuring brain function. Hypoxia, an impaired O(2) delivery, is known to cause BBB dysfunction but the mechanisms that drive this disruption remain unclear.

Epo and non-hematopoietic cells: what do we know?

The hematopoietic growth factor erythropoietin (Epo) circulates in plasma and controls the oxygen carrying capacity of the blood (Fisher. Exp Biol Med (Maywood) 228:1-14, 2003). Epo is produced primarily in the adult kidney and fetal liver and was originally believed to play a role restricted to stimulation of early erythroid precursor proliferation, inhibition of apoptosis, and differentiation of the erythroid lineage.

HIF-1 at the blood-brain barrier: a mediator of permeability?

The importance of the blood-brain barrier (BBB) in maintaining brain homeostasis cannot be better appreciated than during disease states, where disruption of its function is associated with dramatic detrimental clinical outcome. For decades, neuroscientists and neurobiologists investigated most neurological diseases under the prism of a neuro-centric view, considering the contribution of non-neural components of the CNS (BBB, choroid plexus) negligible or even irrelevant. However, recent reviews have highlighted the importance of BBB breakdown in major neurological diseases.

Involvement of oxidative stress in hypoxia-induced blood-brain barrier breakdown.

The blood-brain barrier (BBB) is a cellular barrier formed by specialized brain endothelial cells under the influence of astrocytes and pericytes. Among the several stress factors known to induce BBB breakdown, hypoxia is probably the most represented but also the least understood. Recent evidence of oxidative stress occurring during hypoxia/ischemia situation raises its possible contribution to barrier breakdown.

In vitro modeling of the blood-brain barrier: simplicity versus complexity.

Proper understanding of blood-brain barrier (BBB) regulation is crucial to reduce/prevent its disruption during injury. Since high brain complexity makes interpretation of in vivo data challenging BBB studies are frequently performed using simplified in vitro models. Although such models represent an important and frequently employed alternative for investigation of BBB function and alterations, our ability to translate in vitro findings to in vivo situation remains sub-optimal.