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Lochhead JJ, Ronaldson PT, Davis TP. The role of oxidative stress in blood-brain barrier disruption during ischemic stroke: Antioxidants in clinical trials. Biochem Pharmacol 2024:116186. [PMID: 38561092 DOI: 10.1016/j.bcp.2024.116186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/19/2024] [Accepted: 03/29/2024] [Indexed: 04/04/2024]
Abstract
Ischemic stroke is one of the leading causes of death and disability. Occlusion and reperfusion of cerebral blood vessels (i.e., ischemia/reperfusion (I/R) injury) generates reactive oxygen species (ROS) that contribute to brain cell death and dysfunction of the blood-brain barrier (BBB) via oxidative stress. BBB disruption influences the pathogenesis of ischemic stroke by contributing to cerebral edema, hemorrhagic transformation, and extravasation of circulating neurotoxic proteins. An improved understanding of mechanisms for ROS-associated alterations in BBB function during ischemia/reperfusion (I/R) injury can lead to improved treatment paradigms for ischemic stroke. Unfortunately, progress in developing ROS targeted therapeutics that are effective for stroke treatment has been slow. Here, we review how ROS are produced in response to I/R injury, their effects on BBB integrity (i.e., tight junction protein complexes, transporters), and the utilization of antioxidant treatments in ischemic stroke clinical trials. Overall, knowledge in this area provides a strong translational framework for discovery of novel drugs for stroke and/or improved strategies to mitigate I/R injury in stroke patients.
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Affiliation(s)
- Jeffrey J Lochhead
- Department of Pharmacology, University of Arizona College of Medicine, Tucson, AZ 85724, USA.
| | - Patrick T Ronaldson
- Department of Pharmacology, University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - Thomas P Davis
- Department of Pharmacology, University of Arizona College of Medicine, Tucson, AZ 85724, USA
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Williams EI, Betterton RD, Stanton JA, Moreno-Rodriguez VM, Lochhead JJ, Davis TP, Ronaldson PT. Oatp (Organic Anion Transporting Polypeptide)-Mediated Transport: A Mechanism for Atorvastatin Neuroprotection in Stroke. Stroke 2023; 54:2875-2885. [PMID: 37750296 PMCID: PMC10615849 DOI: 10.1161/strokeaha.123.043649] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 08/31/2023] [Indexed: 09/27/2023]
Abstract
BACKGROUND Drug discovery for stroke is challenging as indicated by poor clinical translatability. In contrast, HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors (ie, statins) improve poststroke neurological outcomes. This property requires transport across the blood-brain barrier via an endogenous uptake transporter (ie, Oatp1a4 [organic anion transporting polypeptide 1a4]). Our goal was to study Oatp1a4 as a drug delivery mechanism because the blood-brain barrier cannot be assumed to be completely open for all drugs in ischemic stroke. METHODS Male Sprague-Dawley rats (200-250 g) were subjected to middle cerebral artery occlusion (90 minutes) followed by reperfusion for up to 7 days. Atorvastatin (20 mg/kg, IV) was administered 2 hours following intraluminal suture removal. Involvement of Oatp-mediated transport was determined using fexofenadine (3.2 mg/kg, IV), a competitive Oatp inhibitor. Oatp1a4 transport activity was measured by in situ brain perfusion. Infarction volumes/brain edema ratios and neuronal nuclei expression were determined using 2,3,5-triphenyltetrazolium chloride-stained brain tissue slices and confocal microscopy, respectively. Poststroke functional outcomes were assessed via neurological deficit scores and rotarod analysis. RESULTS At 2-hour post-middle cerebral artery occlusion, [3H]atorvastatin uptake was increased in ischemic brain tissue. A single dose of atorvastatin significantly reduced post-middle cerebral artery occlusion infarction volume, decreased brain edema ratio, increased caudoputamen neuronal nuclei expression, and improved functional neurological outcomes. All middle cerebral artery occlusion positive effects of atorvastatin were attenuated by fexofenadine coadministration (ie, an Oatp transport inhibitor). CONCLUSIONS Our data demonstrate that neuroprotective effects of atorvastatin may require central nervous system delivery by Oatp-mediated transport at the blood-brain barrier, a mechanism that persists despite increased cerebrovascular permeability in ischemic stroke. These novel and translational findings support utility of blood-brain barrier transporters in drug delivery for neuroprotective agents.
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Affiliation(s)
- Erica I. Williams
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Robert D. Betterton
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Joshua A. Stanton
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | | | - Jeffrey J. Lochhead
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Thomas P. Davis
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Patrick T. Ronaldson
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
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Lochhead JJ, Williams EI, Reddell ES, Dorn E, Ronaldson PT, Davis TP. High Resolution Multiplex Confocal Imaging of the Neurovascular Unit in Health and Experimental Ischemic Stroke. Cells 2023; 12:645. [PMID: 36831312 PMCID: PMC9954836 DOI: 10.3390/cells12040645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/31/2022] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
The neurovascular unit (NVU) is an anatomical group of cells that establishes the blood-brain barrier (BBB) and coordinates cerebral blood flow in association with neuronal function. In cerebral gray matter, cellular constituents of the NVU include endothelial cells and associated pericytes, astrocytes, neurons, and microglia. Dysfunction of the NVU is a common feature of diseases that affect the CNS, such as ischemic stroke. High-level evaluation of these NVU changes requires the use of imaging modalities that can enable the visualization of various cell types under disease conditions. In this study, we applied our confocal microscopy strategy using commercially available labeling reagents to, for the first time, simultaneously investigate associations between endothelial cells, the vascular basal lamina, pericytes, microglia, astrocytes and/or astrocyte end-feet, and neurites in both healthy and ischemic brain tissue. This allowed us to demonstrate ischemia-induced astrocyte activation, neurite loss, and microglial migration toward blood vessels in a single confocal image. Furthermore, our labeling cocktail enabled a precise quantification of changes in neurites and astrocyte reactivity, thereby showing the relationship between different NVU cellular constituents in healthy and diseased brain tissue. The application of our imaging approach for the simultaneous visualization of multiple NVU cell types provides an enhanced understanding of NVU function and pathology, a state-of-the-art advancement that will facilitate the development of more effective treatment strategies for diseases of the CNS that exhibit neurovascular dysfunction, such as ischemic stroke.
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Affiliation(s)
- Jeffrey J. Lochhead
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Erica I. Williams
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Elizabeth S. Reddell
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Emma Dorn
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Patrick T. Ronaldson
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA
| | - Thomas P. Davis
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA
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Williams EI, Betterton R, Stanton JA, Lochhead JJ, Davis TP, Ronaldson PT. Abstract TP205: Organic Anion Transporting Polypeptides: Endogenous Blood-brain Barrier Transporters That Are Required For Statins To Exert Neuroprotective Effects In Ischemic Stroke. Stroke 2023. [DOI: 10.1161/str.54.suppl_1.tp205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Clinical development of new drugs for ischemic stroke has been challenging. In contrast, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (i.e., statins) are routinely administered to stroke patients because they improve neurological outcomes. This property of statins requires delivery across the blood-brain barrier (BBB). We have uncovered a BBB uptake transporter for statins: organic anion transporting polypeptide 1a4 (Oatp1a4). Our goal was to determine whether Oatp-mediated transport at the BBB is a required mechanism for a commonly prescribed statin (i.e., atorvastatin; ATV) to exert neuroprotective effects following ischemic stroke.
Methods:
Male Sprague-Dawley rats (200-250 g) were subjected to middle cerebral artery occlusion (MCAO; 90 min) followed by reperfusion. ATV (20 mg/kg, i.v.) was administered 2 h following intraluminal suture removal. Involvement of Oatp-mediated transport was determined using fexofenadine (FEX; 3.2 mg/kg, i.v.), a competitive Oatp inhibitor. Oatp1a4 transport activity was measured by
in situ
brain perfusion. Following MCAO/reperfusion, infarction volumes and brain edema ratios were calculated from TTC-stained brain tissue slices. Hippocampal neuronal cell numbers were assessed by immunofluorescence imaging of neuronal nuclei (NeuN) staining. Post-stroke functional outcomes were assessed via neurological deficit scores and rotarod analysis. At 2 h post-MCAO, ATV uptake was increased in ischemic brain tissue. FEX blocked blood-to-brain uptake of ATV, which confirmed involvement of an Oatp-mediated transport mechanism. ATV reduced post-MCAO infarction volume and brain edema ratio, increased hippocampal NeuN staining, and improved neurological outcomes. All positive effects of ATV were attenuated by co-administration of FEX.
Conclusions:
Our data demonstrate ATV requires functional expression of an endogenous BBB transporter (i.e., Oatp1a4) to exert neuroprotective effects and promote post-stroke recovery. These novel and translational findings provide mechanistic evidence on the critical role of BBB transporters in delivery of stroke drugs to the ischemic brain, information that can facilitate therapeutic advancement in clinical trials.
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Betterton RD, Abdullahi W, Williams EI, Lochhead JJ, Brzica H, Stanton J, Reddell E, Ogbonnaya C, Davis TP, Ronaldson PT. Regulation of Blood-Brain Barrier Transporters by Transforming Growth Factor- β/Activin Receptor-Like Kinase 1 Signaling: Relevance to the Brain Disposition of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitors (i.e., Statins). Drug Metab Dispos 2022; 50:942-956. [PMID: 35504656 PMCID: PMC11022862 DOI: 10.1124/dmd.121.000781] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 04/08/2022] [Indexed: 11/22/2022] Open
Abstract
Our laboratory has shown that activation of transforming growth factor- β (TGF- β )/activin receptor-like kinase 1 (ALK1) signaling can increase protein expression and transport activity of organic anion transporting polypeptide 1a4 (Oatp1a4) at the blood-brain barrier (BBB). These results are relevant to treatment of ischemic stroke because Oatp transport substrates such as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (i.e., statins) improve functional neurologic outcomes in patients. Advancement of our work requires determination if TGF- β /ALK1 signaling alters Oatp1a4 functional expression differently across brain regions and if such disparities affect central nervous system (CNS) statin disposition. Therefore, we studied regulation of Oatp1a4 by the TGF- β /ALK1 pathway, in vivo, in rat brain microvessels isolated from cerebral cortex, hippocampus, and cerebellum using the ALK1 agonist bone morphogenetic protein-9 (BMP-9) and the ALK1 inhibitor 4-[6-[4-(1-piperazinyl)phenyl]pyrazolo[1,5-a]pyrimidin-3-yl]quinoline dihydrochloride 193189. We showed that Oatp1a4 protein expression and brain distribution of three currently marketed statin drugs (i.e., atorvastatin, pravastatin, and rosuvastatin) were increased in cortex relative to hippocampus and cerebellum. Additionally, BMP-9 treatment enhanced Oatp-mediated statin transport in cortical tissue but not in hippocampus or cerebellum. Although brain drug delivery is also dependent upon efflux transporters, such as P-glycoprotein and/or Breast Cancer Resistance Protein, our data showed that administration of BMP-9 did not alter the relative contribution of these transporters to CNS disposition of statins. Overall, this study provides evidence for differential regulation of Oatp1a4 by TGF- β /ALK1 signaling across brain regions, knowledge that is critical for development of therapeutic strategies to target Oatps at the BBB for CNS drug delivery. SIGNIFICANCE STATEMENT: Organic anion transporting polypeptides (Oatps) represent transporter targets for brain drug delivery. We have shown that Oatp1a4 statin uptake is higher in cortex versus hippocampus and cerebellum. Additionally, we report that the transforming growth factor- β /activin receptor-like kinase 1 agonist bone morphogenetic protein-9 increases Oatp1a4 functional expression, but not efflux transporters P-glycoprotein and Breast Cancer Resistance Protein, in cortical brain microvessels. Overall, this study provides critical data that will advance treatment for neurological diseases where drug development has been challenging.
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Affiliation(s)
- Robert D Betterton
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Wazir Abdullahi
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Erica I Williams
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Jeffrey J Lochhead
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Hrvoje Brzica
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Joshua Stanton
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Elizabeth Reddell
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Chidinma Ogbonnaya
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Thomas P Davis
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Patrick T Ronaldson
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona
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Lochhead JJ, Yang J, Ronaldson PT, Davis TP. Structure, Function, and Regulation of the Blood-Brain Barrier Tight Junction in Central Nervous System Disorders. Front Physiol 2020; 11:914. [PMID: 32848858 PMCID: PMC7424030 DOI: 10.3389/fphys.2020.00914] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 07/08/2020] [Indexed: 12/16/2022] Open
Abstract
The blood-brain barrier (BBB) allows the brain to selectively import nutrients and energy critical to neuronal function while simultaneously excluding neurotoxic substances from the peripheral circulation. In contrast to the highly permeable vasculature present in most organs that reside outside of the central nervous system (CNS), the BBB exhibits a high transendothelial electrical resistance (TEER) along with a low rate of transcytosis and greatly restricted paracellular permeability. The property of low paracellular permeability is controlled by tight junction (TJ) protein complexes that seal the paracellular route between apposing brain microvascular endothelial cells. Although tight junction protein complexes are principal contributors to physical barrier properties, they are not static in nature. Rather, tight junction protein complexes are highly dynamic structures, where expression and/or localization of individual constituent proteins can be modified in response to pathophysiological stressors. These stressors induce modifications to tight junction protein complexes that involve de novo synthesis of new protein or discrete trafficking mechanisms. Such responsiveness of BBB tight junctions to diseases indicates that these protein complexes are critical for maintenance of CNS homeostasis. In fulfillment of this vital role, BBB tight junctions are also a major obstacle to therapeutic drug delivery to the brain. There is an opportunity to overcome this substantial obstacle and optimize neuropharmacology via acquisition of a detailed understanding of BBB tight junction structure, function, and regulation. In this review, we discuss physiological characteristics of tight junction protein complexes and how these properties regulate delivery of therapeutics to the CNS for treatment of neurological diseases. Specifically, we will discuss modulation of tight junction structure, function, and regulation both in the context of disease states and in the setting of pharmacotherapy. In particular, we will highlight how these properties can be potentially manipulated at the molecular level to increase CNS drug levels via paracellular transport to the brain.
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Ronaldson PT, Lochhead JJ, Davis TP. Abstract TP121: Organic Anion Transporting Polypeptide (Oatp)-Mediated Transport is Required for Statin-Induced Neuroprotection: A Role for Blood-Brain Barrier Transporters in Stroke Treatment. Stroke 2020. [DOI: 10.1161/str.51.suppl_1.tp121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives:
Treatment approaches for stroke include reperfusion therapies (i.e., recombinant tissue plasminogen activator, endovascular thrombectomy); however, many stroke patients still experience disability. This indicates a need to develop neuroprotective treatments that are effective in the setting of successful recanalization. Post-stroke outcomes are improved by treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins). We have shown that the endogenous blood-brain barrier (BBB) uptake transporter Oatp1a4 facilitates blood-to-brain transport of atorvastatin (ATV). The objective of this study was to show that Oatp-mediated transport at the BBB is an absolute requirement for ATV neuroprotective effectiveness in stroke.
Methods:
Male and female Sprague-Dawley rats (200-250 g) were subjected to transient middle cerebral artery occlusion (tMCAO) for 90 minutes followed by 22.5 h reperfusion. Sham-operated animals were used as controls. ATV (20 mg/kg, i.v.) was injected 2 h following reperfusion. The role of Oatp-mediated transport was determined using the Oatp transport inhibitor fexofenadine (FEX; 3.2 mg/kg, i.v.) injected at the same time as ATV. Following tMCAO, infarction volume and brain edema ratios were calculated from TTC-stained brain slices. Post-stroke outcomes were assessed via measurement of neurological deficit scores, by the adhesive removal test (i.e., sensorimotor function), and by the rotarod performance test (i.e., motor function).
Results:
In tMCAO animals, ATV reduced (p < 0.01) both infarction volume and brain edema ratio in both sexes. ATV improved neurological deficit scores and well as sensorimotor function and motor performance. In the presence of FEX, ATV had no effect on infarction volume or brain edema ratio. Similarly, positive effects of ATV on post-stroke outcomes were attenuated by FEX.
Conclusions:
Our data indicate that pharmacological inhibition of Oatp-mediated transport at the BBB prevents ATV from exerting neuroprotective effects in rats following tMCAO. Our results also suggest that i.v. ATV administered at an early time point following reperfusion (i.e., 2 h) can provide effective neuroprotection in male and female rats subjected to tMCAO.
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Kumar NN, Lochhead JJ, Pizzo ME, Nehra G, Boroumand S, Greene G, Thorne RG. Delivery of immunoglobulin G antibodies to the rat nervous system following intranasal administration: Distribution, dose-response, and mechanisms of delivery. J Control Release 2018; 286:467-484. [PMID: 30081144 DOI: 10.1016/j.jconrel.2018.08.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/28/2018] [Accepted: 08/02/2018] [Indexed: 12/31/2022]
Abstract
The intranasal route has been hypothesized to circumvent the blood-brain and blood-cerebrospinal fluid barriers, allowing entry into the brain via extracellular pathways along olfactory and trigeminal nerves and the perivascular spaces (PVS) of cerebral blood vessels. We investigated the potential of the intranasal route to non-invasively deliver antibodies to the brain 30 min following administration by characterizing distribution, dose-response, and mechanisms of antibody transport to and within the brain after administering non-targeted radiolabeled or fluorescently-labeled full length immunoglobulin G (IgG) to normal adult female rats. Intranasal [125I]-IgG consistently yielded highest concentrations in the olfactory bulbs, trigeminal nerves, and leptomeningeal blood vessels with their associated PVS. Intranasal delivery also resulted in significantly higher [125I]-IgG concentrations in the CNS than systemic (intra-arterial) delivery for doses producing similar endpoint blood concentrations. Importantly, CNS targeting significantly increased with increasing dose only with intranasal administration, yielding brain concentrations that ranged from the low-to-mid picomolar range with tracer dosing (50 μg) up to the low nanomolar range at higher doses (1 mg and 2.5 mg). Finally, intranasal pre-treatment with a previously identified nasal permeation enhancer, matrix metalloproteinase-9, significantly improved intranasal [125I]-IgG delivery to multiple brain regions and further allowed us to elucidate IgG transport pathways extending from the nasal epithelia into the brain using fluorescence microscopy. The results show that it may be feasible to achieve therapeutic levels of IgG in the CNS, particularly at higher intranasal doses, and clarify the likely cranial nerve and perivascular distribution pathways taken by antibodies to reach the brain from the nasal mucosae.
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Affiliation(s)
- Niyanta N Kumar
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States
| | - Jeffrey J Lochhead
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States
| | - Michelle E Pizzo
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States; Clinical Neuroengineering Training Program, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Geetika Nehra
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States
| | - Sam Boroumand
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States
| | - Gretchen Greene
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States
| | - Robert G Thorne
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, United States; Clinical Neuroengineering Training Program, University of Wisconsin-Madison, Madison, WI 53705, United States; Neuroscience Training Program & Center for Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, United States; Cellular and Molecular Pathology Graduate Training Program, University of Wisconsin-Madison, Madison, WI 53705, United States.
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Lochhead JJ, Ronaldson PT, Davis TP. Hypoxic Stress and Inflammatory Pain Disrupt Blood-Brain Barrier Tight Junctions: Implications for Drug Delivery to the Central Nervous System. AAPS J 2017; 19:910-920. [PMID: 28353217 DOI: 10.1208/s12248-017-0076-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/15/2017] [Indexed: 02/08/2023]
Abstract
A functional blood-brain barrier (BBB) is necessary to maintain central nervous system (CNS) homeostasis. Many diseases affecting the CNS, however, alter the functional integrity of the BBB. It has been shown that various diseases and physiological stressors can impact the BBB's ability to selectively restrict passage of substances from the blood to the brain. Modifications of the BBB's permeability properties can potentially contribute to the pathophysiology of CNS diseases and result in altered brain delivery of therapeutic agents. Hypoxia and/or inflammation are central components of a number of diseases affecting the CNS. A number of studies indicate hypoxia or inflammatory pain increase BBB paracellular permeability, induce changes in the expression and/or localization of tight junction proteins, and affect CNS drug uptake. In this review, we look at what is currently known with regard to BBB disruption following a hypoxic or inflammatory insult in vivo. Potential mechanisms involved in altering tight junction components at the BBB are also discussed. A more detailed understanding of the mediators involved in changing BBB functional integrity in response to hypoxia or inflammatory pain could potentially lead to new treatments for CNS diseases with hypoxic or inflammatory components. Additionally, greater insight into the mechanisms involved in TJ rearrangement at the BBB may lead to novel strategies to pharmacologically increase delivery of drugs to the CNS.
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Affiliation(s)
| | | | - Thomas P Davis
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA.
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Kumar NN, Gautam M, Lochhead JJ, Wolak DJ, Ithapu V, Singh V, Thorne RG. Relative vascular permeability and vascularity across different regions of the rat nasal mucosa: implications for nasal physiology and drug delivery. Sci Rep 2016; 6:31732. [PMID: 27558973 PMCID: PMC4997340 DOI: 10.1038/srep31732] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/25/2016] [Indexed: 12/25/2022] Open
Abstract
Intranasal administration provides a non-invasive drug delivery route that has been proposed to target macromolecules either to the brain via direct extracellular cranial nerve-associated pathways or to the periphery via absorption into the systemic circulation. Delivering drugs to nasal regions that have lower vascular density and/or permeability may allow more drug to access the extracellular cranial nerve-associated pathways and therefore favor delivery to the brain. However, relative vascular permeabilities of the different nasal mucosal sites have not yet been reported. Here, we determined that the relative capillary permeability to hydrophilic macromolecule tracers is significantly greater in nasal respiratory regions than in olfactory regions. Mean capillary density in the nasal mucosa was also approximately 5-fold higher in nasal respiratory regions than in olfactory regions. Applying capillary pore theory and normalization to our permeability data yielded mean pore diameter estimates ranging from 13–17 nm for the nasal respiratory vasculature compared to <10 nm for the vasculature in olfactory regions. The results suggest lymphatic drainage for CNS immune responses may be favored in olfactory regions due to relatively lower clearance to the bloodstream. Lower blood clearance may also provide a reason to target the olfactory area for drug delivery to the brain.
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Affiliation(s)
- Niyanta N Kumar
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Room #5113, Rennebohm hall, 777 Highland avenue, Madison, WI - 53705, USA
| | - Mohan Gautam
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Room #5113, Rennebohm hall, 777 Highland avenue, Madison, WI - 53705, USA
| | - Jeffrey J Lochhead
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Room #5113, Rennebohm hall, 777 Highland avenue, Madison, WI - 53705, USA
| | - Daniel J Wolak
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Room #5113, Rennebohm hall, 777 Highland avenue, Madison, WI - 53705, USA.,Clinical Neuroengineering Training Program, University of Wisconsin-Madison Biomedical Engineering, Engineering Centers Building, 1550 Engineering Drive, Room #2120, Madison WI - 53706, USA
| | - Vamsi Ithapu
- Department of Computer Sciences, University of Wisconsin-Madison, 5780 Medical Sciences Center, 1300 University Avenue, Madison, WI - 53706, USA
| | - Vikas Singh
- Department of Computer Sciences, University of Wisconsin-Madison, 5780 Medical Sciences Center, 1300 University Avenue, Madison, WI - 53706, USA
| | - Robert G Thorne
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Room #5113, Rennebohm hall, 777 Highland avenue, Madison, WI - 53705, USA.,Clinical Neuroengineering Training Program, University of Wisconsin-Madison Biomedical Engineering, Engineering Centers Building, 1550 Engineering Drive, Room #2120, Madison WI - 53706, USA.,Neuroscience Training Program &Center for Neuroscience, Rooms 9531 &9533, Wisconsin Institutes for Medical Research II, 1111 Highland Ave. Madison, WI - 53705, USA.,Cellular and Molecular Pathology Graduate Training Program, University of Wisconsin-Madison, UW Department of Pathology and Laboratory Medicine 1685 Highland Avenue Madison, WI - 53705, USA
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12
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Lochhead JJ, Thorne RG. Intranasal delivery of biologics to the central nervous system. Adv Drug Deliv Rev 2012; 64:614-28. [PMID: 22119441 DOI: 10.1016/j.addr.2011.11.002] [Citation(s) in RCA: 715] [Impact Index Per Article: 59.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 11/03/2011] [Accepted: 11/07/2011] [Indexed: 12/28/2022]
Abstract
Treatment of central nervous system (CNS) diseases is very difficult due to the blood-brain barrier's (BBB) ability to severely restrict entry of all but small, non-polar compounds. Intranasal administration is a non-invasive method of drug delivery which may bypass the BBB to allow therapeutic substances direct access to the CNS. Intranasal delivery of large molecular weight biologics such as proteins, gene vectors, and stem cells is a potentially useful strategy to treat a variety of diseases/disorders of the CNS including stroke, Parkinson's disease, multiple sclerosis, Alzheimer's disease, epilepsy, and psychiatric disorders. Here we give an overview of relevant nasal anatomy and physiology and discuss the pathways and mechanisms likely involved in drug transport from the nasal epithelium to the CNS. Finally we review both pre-clinical and clinical studies involving intranasal delivery of biologics to the CNS.
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Affiliation(s)
- Jeffrey J Lochhead
- Pharmaceutical Sciences Division, University of Wisconsin-Madison School of Pharmacy, Madison, WI 53705, USA
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Lochhead JJ, McCaffrey G, Sanchez-Covarrubias L, Finch JD, Demarco KM, Quigley CE, Davis TP, Ronaldson PT. Tempol modulates changes in xenobiotic permeability and occludin oligomeric assemblies at the blood-brain barrier during inflammatory pain. Am J Physiol Heart Circ Physiol 2011; 302:H582-93. [PMID: 22081706 DOI: 10.1152/ajpheart.00889.2011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Our laboratory has shown that λ-carrageenan-induced peripheral inflammatory pain (CIP) can alter tight junction (TJ) protein expression and/or assembly leading to changes in blood-brain barrier xenobiotic permeability. However, the role of reactive oxygen species (ROS) and subsequent oxidative stress during CIP is unknown. ROS (i.e., superoxide) are known to cause cellular damage in response to pain/inflammation. Therefore, we examined oxidative stress-associated effects at the blood-brain barrier (BBB) in CIP rats. During CIP, increased staining of nitrosylated proteins was detected in hind paw tissue and enhanced presence of protein adducts containing 3-nitrotyrosine occurred at two molecular weights (i.e., 85 and 44 kDa) in brain microvessels. Tempol, a pharmacological ROS scavenger, attenuated formation of 3-nitrotyrosine-containing proteins in both the hind paw and in brain microvessels when administered 10 min before footpad injection of λ-carrageenan. Similarly, CIP increased 4-hydroxynoneal staining in brain microvessels and this effect was reduced by tempol. Brain permeability to [(14)C]sucrose and [(3)H]codeine was increased, and oligomeric assemblies of occludin, a critical TJ protein, were altered after 3 h CIP. Tempol attenuated both [(14)C]sucrose and [(3)H]codeine brain uptake as well as protected occludin oligomers from disruption in CIP animals, suggesting that ROS production/oxidative stress is involved in modulating BBB functional integrity during pain/inflammation. Interestingly, tempol administration reduced codeine analgesia in CIP animals, indicating that oxidative stress during pain/inflammation may affect opioid delivery to the brain and subsequent efficacy. Taken together, our data show for the first time that ROS pharmacological scavenging is a viable approach for maintaining BBB integrity and controlling central nervous system drug delivery during acute inflammatory pain.
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Affiliation(s)
- Jeffrey J Lochhead
- Dept. of Medical Pharmacology, College of Medicine, Univ. of Arizona, 1501 North Campbell Ave., P.O. Box 245050, Tucson, AZ 85724-5050, USA
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McCaffrey G, Willis CL, Staatz WD, Nametz N, Quigley CA, Hom S, Lochhead JJ, Davis TP. Occludin oligomeric assemblies at tight junctions of the blood-brain barrier are altered by hypoxia and reoxygenation stress. J Neurochem 2009; 110:58-71. [PMID: 19457074 DOI: 10.1111/j.1471-4159.2009.06113.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hypoxic (low oxygen) and reperfusion (post-hypoxic reoxygenation) phases of stroke promote an increase in microvascular permeability at tight junctions (TJs) of the blood-brain barrier (BBB) that may lead to cerebral edema. To investigate the effect of hypoxia (Hx) and reoxygenation on oligomeric assemblies of the transmembrane TJ protein occludin, rats were subjected to either normoxia (Nx, 21% O(2), 60 min), Hx (6% O(2), 60 min), or hypoxia/reoxygenation (H/R, 6% O(2), 60 min followed by 21% O(2), 10 min). After treatment, cerebral microvessels were isolated, fractionated by detergent-free density gradient centrifugation, and occludin oligomeric assemblies associated with plasma membrane lipid rafts were solubilized by perfluoro-octanoic acid (PFO) exclusively as high molecular weight protein complexes. Analysis by non-reducing and reducing sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis/western blot of PFO-solubilized occludin revealed that occludin oligomeric assemblies co-localizing with 'TJ-associated' raft domains contained a high molecular weight 'structural core' that was resistant to disassembly by either SDS or a hydrophilic reducing agent ex vivo, and by Hx and H/R conditions in vivo. However, exposure of PFO-solubilized occludin oligomeric assemblies to SDS ex vivo revealed the non-covalent association of a significant amount of dimeric and monomeric occludin isoforms to the disulfide-bonded inner core, and dispersal of these non-covalently attached occludin subunits to lipid rafts of higher density in vivo was differentially promoted by Hx and H/R. Our data suggest a model of isoform interaction within occludin oligomeric assemblies at the BBB that enables occludin to simultaneously perform a structural role in inhibiting paracellular diffusion, and a signaling role involving interactions of dimeric and monomeric occludin isoforms with a variety of regulatory molecules within different plasma membrane lipid raft domains.
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Affiliation(s)
- Gwen McCaffrey
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85745, USA.
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