Central Nervous System Blood Research Articles

Simultaneous and independent detection of C9ORF72 alleles with low and high number of GGGGCC repeats using an optimised protocol of Southern blot hybridisation

BackgroundSizing of GGGGCC hexanucleotide repeat expansions within the C9ORF72 locus, which account for approximately 10% of all amyotrophic lateral sclerosis (ALS) cases, is urgently required to answer fundamental questions about mechanisms of pathogenesis in this important genetic variant. Currently employed PCR protocols are limited to discrimination between the presence and absence of a modified allele with more than 30 copies of the repeat, while Southern hybridisation-based methods are confounded by the somatic heterogeneity commonly present in blood samples, which might cause false-negative or ambiguous results.ResultsWe describe an optimised Southern hybridisation-based protocol that allows confident detection of the presence of a C9ORF72 repeat expansion alongside independent assessment of its heterogeneity and the number of repeat units. The protocol can be used with either a radiolabeled or non-radiolabeled probe. Using this method we have successfully sized the C9ORF72 repeat expansion in lymphoblastoid cells, peripheral blood, and post-mortem central nervous system (CNS) tissue from ALS patients. It was also possible to confidently demonstrate the presence of repeat expansion, although of different magnitude, in both C9ORF72 alleles of the genome of one patient.ConclusionsThe suggested protocol has sufficient advantages to warrant adoption as a standard for Southern blot hybridisation analysis of GGGGCC repeat expansions in the C9ORF72 locus.

Molecular Parallels between Neural and Vascular Development

The human central nervous system (CNS) features a network of ~400 miles of blood vessels that receives >20% of the body's cardiac output and uses most of its blood glucose. Many human diseases, including stroke, retinopathy, and cancer, are associated with the biology of CNS blood vessels. These vessels originate from extrinsic cell populations, including endothelial cells and pericytes that colonize the CNS and interact with glia and neurons to establish the blood-brain barrier and control cerebrovascular exchanges. Neurovascular interactions also play important roles in adult neurogenic niches, which harbor a unique population of neural stem cells that are intimately associated with blood vessels. We here review the cellular and molecular mechanisms required to establish the CNS vascular network, with a special focus on neurovascular interactions and the functions of vascular endothelial growth factors.

Hyaluronan Anchored to Activated CD44 on Central Nervous System Vascular Endothelial Cells Promotes Lymphocyte Extravasation in Experimental Autoimmune Encephalomyelitis

The extravasation of lymphocytes across central nervous system (CNS) vascular endothelium is a key step in inflammatory demyelinating diseases including multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). The glycosaminoglycan hyaluronan (HA) and its receptor, CD44, have been implicated in this process but their precise roles are unclear. We find that CD44(-/-) mice have a delayed onset of EAE compared with wild type animals. Using an in vitro lymphocyte rolling assay, we find that fewer slow rolling (<1 μm/s) wild type (WT) activated lymphocytes interact with CD44(-/-) brain vascular endothelial cells (ECs) than with WT ECs. We also find that CD44(-/-) ECs fail to anchor HA to their surfaces, and that slow rolling lymphocyte interactions with WT ECs are inhibited when the ECs are treated with a pegylated form of the PH20 hyaluronidase (PEG-PH20). Subcutaneous injection of PEG-PH20 delays the onset of EAE symptoms by ~1 day and transiently ameliorates symptoms for 2 days following disease onset. These improved symptoms correspond histologically to degradation of HA in the lumen of CNS blood vessels, decreased demyelination, and impaired CD4(+) T-cell extravasation. Collectively these data suggest that HA tethered to CD44 on CNS ECs is critical for the extravasation of activated T cells into the CNS providing new insight into the mechanisms promoting inflammatory demyelinating disease.

Clinical use of gadobutrol for contrast-enhanced magnetic resonance imaging of neurological diseases

Clinical use of gadobutrol for contrast-enhanced magnetic resonance imaging of neurological diseases Kenneth T Cheng1, Hannah Y Cheng2, Kam Leung31Department of Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA; 2Freelance Technical Writer, New Orleans, LA, USA; 3National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USAAbstract: Contrast-enhanced magnetic resonance imaging (CE-MRI) is an important clinical tool for diagnosing neurological diseases. The appropriate use of a suitable MRI contrast agent or contrast pharmaceutical is essential for CE-MRI to produce desirable diagnostic images. Currently, there are seven contrast agents (CAs) or pharmaceuticals approved for clinical imaging of the central nervous system (CNS) in the US, Europe, or Japan. All of the clinically approved CAs are water-soluble gadolinium-based contrast agents (GBCAs) which do not penetrate the CNS blood&ndash;brain barrier (BBB). These agents are used for imaging CNS areas without a BBB, or various pathologies, such as tumors and infection that break down the BBB and allow CAs to enter into the surrounding parenchyma. Clinically, GBCAs are most useful for detecting primary and secondary cerebral neoplastic lesions. Among these CNS GBCAs, gadobutrol (Gd-BT-DO3A, Gadovist&trade;) is a neutral, nonionic, macrocyclic compound that showed promising results from clinical trials of CNS imaging. In comparison with other GBCAs, Gd-BT-DO3A has relatively high in vitro kinetic stability and r1 relaxivity. Gd-BT-DO3A has been recently approved by the US Food and Drug Administration (FDA) in 2011 for CNS imaging. A review of available literature shows that Gd-BT-DO3A exhibits similar safety and clinical efficacy profiles to other GBCAs. Gd-BT-DO3A has the distinguishing feature that it is the only clinical agent commercially available in a formulation of 1.0 M concentration with a relatively higher in vitro T1 shortening per unit volume than other clinical GBCAs which are only available in 0.5 M concentration. This double concentration of Gd-BT-DO3A may allow a relatively higher concentration of the agent to localize in the CNS and produce a better contrast enhancement at the same clinical dose as other GBCAs. Several recent published multicenter clinical trials appeared to support this potential advantage of Gd-BT-DO3A.Keywords: Gadovist, Gd-BT-DO3A, CE-MRI, CNS imaging, MRI contrast agent, gadolinium

Effects of Peripheral Inflammation on the Blood-Spinal Cord Barrier

BackgroundChanges in the blood-central nervous system barriers occur under pathological conditions including inflammation and contribute to central manifestations of various diseases. After short-lasting peripheral and neurogenic inflammation, the evidence is mixed whether there are consistent blood-spinal cord changes. In the current study, we examine changes in the blood-spinal cord barrier after intraplantar capsaicin and λ-carrageenan using several methods: changes in occludin protein, immunoglobulin G accumulation, and fluorescent dye penetration. We also examine potential sex differences in male and female adult rats.ResultsAfter peripheral carrageenan inflammation, but not capsaicin inflammation, immunohistochemistry shows occludin protein in lumbar spinal cord to be significantly altered at 72 hours post-injection. In addition, there is also significant immunoglobulin G detected in lumbar and thoracic spinal cord at this timepoint in both male and female rats. However, acute administration of sodium fluorescein or Evans Blue dyes is not detected in the parenchyma at this timepoint.ConclusionsOur results show that carrageenan inflammation induces changes in tight junction protein and immunoglobulin G accumulation, but these may not be indicative of a blood-spinal cord barrier breakdown. These changes appear transiently after peak nociception and may be indicative of reversible pathology that resolves together with inflammation.

Intensification of Chemotherapeutic Regimens and Hematopoietic Stem Cell Transplantation Are Responsible for Improved Overall Survival in Adult Acute Lymphoblastic Leukemia in a Single Center Over the Last Forty Years

Abstract 4227 BackgroundAcute lymphoblastic leukemia (ALL) of adults is an infrequent and heterogeneous disease according to presentation pattern, prognosis and treatment. It is widely assumed that age above 30 years, leukocytosis >25 ×109/L, central nervous system involvement and specific cytogenetic disorders such as t(9;22) or MLL rearrangement entail bad prognosis. There are controversial studies on the impact of intensification chemotherapy and hematopoietic stem cell transplantation (HSCT) on survival of these high-risk groups. AimsTo identify biological, clinical and prognostic characteristics in adult ALL patients diagnosed and followed in a single center throughout 40 years as long as the impact on clinical outcome of different consecutive therapeutic approaches, including HSCT, in different periods. Patients and methodsThroughout 1970 to 2011, 230 patients were prospectively registered and retrospectively analyzed. Most patients accomplishing pre-determined criteria received treatment according to PETHEMA or locally developed therapeutic protocols (including HSCT in relapse high-risk patients, since 1978). Critical variables at diagnosis such as age, gender, phenotype (from 1978), cytogenetic (from 1999), white blood cells count (WBC) and central nervous system involvement, were analyzed.Response to induction chemotherapy, relapse rate (RR) and 5 year overall survival (OS) were analyzed in the whole cohort and separately by decade when treatment protocols were different. The clinical impact of HSCT was analyzed on a subgroup of patients homogeneously treated since 1994. Statistical analysis was performed by mean of Chi-square and Kaplan Meier tests, as appropriate. OutcomeTable 1 summarizes the presentation pattern and its prognostic value. At diagnosis features such male gender, age above 30 years, central nervous system involvement, leukocytosis >10×109/L, MLL rearrangement, t(9:22) and complex karyotype entailed a worse prognosis. For the whole cohort the 5 years OS was 30%. CR was achieved in 73% and the RR was 38%. 5 years OS has improved by decades: 11% in the 70s, 24% in the 80s, 30% in the 90s, and 41% in XXI century (p<0,01). Patients selected for intensive chemotherapeutic protocols achieved a similar CR rate in each decade (nearly 80%) while the RR decreased through the years (70s: 68%, 80s: 44%, 90: 42%, 00–11: 25%; p<0,01). Patients treated with chemotherapy plus HSCT achieved in 5 years (from 1994) an OS of 69% in comparison with the 30% obtained in those patients who only received chemotherapy (p<0,01).Table 1Prognostic value of presentation features and impact on outcome of therapeutic options.VariableN° patient/Available casesOverall survival at 5 yearsStatistic significationGenderFemale11135%P <0,05Male11924%Total 230Age (years)Mean 36 (15-86)6138%P<0,0115-204647%20-3012318,5%>30Total 230PhenotypeB13249%NST3825%Unclassifiable60–––Total 230CytogeneticsOS at 2 ys:P<0,01Normal karyotype1679,5%Complex karyotype714,5%MLL rearrangement333%Phi cromosome2252% (30% at 4 ys follow-up)Others1423,5%Total 62WBC at diagnosis<10×109/L7145%P<0,01>10×109/L9926%Total 170CNS involvement at diagnosisYes1717%P<0,05No17843%Total 195TreatmentChemotherapy18923%Chemotherapy + HSCT4155%P<0,01Total 230Group from 1994P<0,01Chemotherapy8030%Chemotherapy + HSCT2969%Total 108HSCT typeAutologous2152%Allogeneic2057,5%NSTotal 41Group from 1994Autologous1080%Allogeneic1961%Total 29Remission status at HSCTCR12663,5%NSCR others952%Refractory/ relapse520%Total 41NS= Not significant. ConclusionMale gender, age above 30, WBC >10×10e9/L, t(9;22), MLL-rearrangement, complex karyotype and CNS involvement conferred poor prognosis in adult ALL. Intensification of chemotherapeutic regimens produced a progressive decrease in relapse rate, leading to an improvement in overall survival over the years. HSCT seems to partially overcome the poor prognosis related to high risk factors. Disclosures:Perez-Simón:Janssen-Cilag: Patents & Royalties.

Initial therapy of mantle cell lymphoma

Mantle cell lymphoma is a well-recognized distinct clinicopathologic subtype of B-cell non-Hodgkin lymphoma. The current World Health Organization (WHO) classification subdivides this entity into aggressive and other variants. The disease has a predilection for older males, and patients typically present at an advanced stage with frequent splenomegaly and extranodal involvement including bone marrow, peripheral blood, gastrointestinal, and occasional central nervous system involvement. Early studies of therapy outcomes in this disease revealed that while response rates where high, relapse was expected after a limited period of time. Prolonged survival was uncommon, with initial median survival rates typically in the 3-4-year range. Those with a high proliferative rate, blastoid morphology, and selected clinical features were recognized as having a worse prognosis. Therapeutic approaches have diverged into aggressive therapies with high response rates and promising progression free survival rates, which may be applied to younger healthy patients, and less aggressive approaches. Aggressive therapies include intensive chemotherapy alone or chemotherapy followed by autologous stem cell transplant, which has been shown to be most effective when applied in first remission. Whether these more intense therapies result in improved survival as compared with less aggressive therapies is not well established. Allogeneic transplant has also been investigated, although high treatment-related mortality and the risk of chronic graft versus host disease and the relatively advanced age of this patient population have tempered enthusiasm for this approach. A number of less aggressive therapies have been shown to produce promising results. Consolidation and maintenance strategies are an active area of investigation. A number of newer agents have shown promising activity in relapsed disease, and are being investigated in the front-line setting. Overall survival rates are improving in this disease, with current studies suggesting a median survival of 5 or more years.

New Trends in Resuscitation

Overall, injuries are the third leading cause of death in the United States, but they affect the younger and most productive segment of our society disproportionately. According to the National Center for Health Statistics, injuries are the number one cause of death and disability under age 44, and more Americans between the ages of 1–34 years are killed by injuries than by all other diseases combined1. The financial impact of injuries is staggering- 50 million injuries that required medical treatment in 2000 will ultimately cost the US society $406 billion, including $80.2 billion in medical care costs and $326 billion in lost productivity2. Analysis of epidemiological data from large trauma centers reveals consistent patterns of death 3–7. Up to half of the deaths occur prior to arrival in a hospital as a result of massive blood loss or central nervous system (CNS) damage. Compared to severe CNS damage, death resulting from bleeding is potentially preventable, and life saving efforts focus on early control of bleeding and adequate resuscitation. Unfortunately, conventional resuscitation methods often exacerbate the underlying cellular injury8. Of the patients that are transported to the hospital, the majority (70–80%) dies within the first 24–48 hours, with a much smaller percentage (<10%) succumbing to late death as a result of sepsis and organ failure. As hemorrhage-related deaths primarily occur in the first six hours after injury5, early delivery of high quality care is of critical importance. Despite hemorrhage being a common problem, the optimal resuscitative strategy remains controversial, with vigorous debates about the type of fluid, volume, rate, route of administration, and end points of resuscitation. This review highlights recent advances in resuscitation strategies as our understanding of the body’s response to hemorrhage and resuscitation has evolved.

Translational pharmacokinetics: challenges of an emerging approach to drug development in stroke

Introduction: There is increasing recognition of the importance of translational pharmacokinetics in stroke research, lack of which has been cited as one of the main contributing factors to failure of Phase III trials.Areas covered: The article reviews the translational issues in administration, distribution and sampling in the pharmacokinetics of putative therapeutic drugs in stroke. In addition, the role of translational pharmacometrics in drug development is discussed. The review uses the anti-inflammatory agent, IL-1 receptor antagonist, as an example. The reader will gain an insight into the pitfalls that are commonplace in translating pharmacokinetics from the preclinical to the clinical scenario. The reader will also gain an understanding of the complexities of blood–central nervous system (CNS) barriers in relation to brain pharmacokinetics and the increasing use of translational pharmacometrics in stroke research.Expert opinion: The translation of preclinical to clinical pharmacokinetics is a discipline that is traditionally overlooked and is likely to be a key factor responsible for failure of clinical trials. With a clear comprehensive insight into the benefits and limitations of translational pharmacokinetics in stroke, translational pharmacokinetics can be safely used to enhance the efficacy of clinical trials in stroke and their likelihood of success.

Definition of leukocyte subsets in primate central nervous system by polychromatic flow cytometry

Haematopoietic immune cell populations play an important role in the pathogenesis of numerous neurological disorders. To better understand the function of resident mononuclear phagocytes and migrating leukocytes in the central nervous system (CNS), the definition of these populations in healthy individuals is crucial. Therefore, the composition of CNS-associated leukocytes, isolated from macaque brain tissue, was assessed using multicolor flow cytometry. We established a combination of antibodies directed against nine different antigens that enabled a precise classification of all major immune cell populations in a single tube. Macrophages, dendritic cells (DCs), B and T lymphocytes, and natural killer (NK) cells were differentiated in CNS and peripheral blood. Additionally, microglia cells were detected in the brain. Using this antibody combination also allowed the discrimination of functionally different subsets among the distinct immunocyte populations, for example, CD8 positive cytotoxic T lymphocytes. About 95% of the leukocytes in the brain are microglia cells. Two additional myeloid cell populations, CD14 positive macrophages and CD11c-positive DCs, were also identified. In contrast to blood, where macrophages are more abundant, DCs outnumbered macrophages in the brain. Among lymphocytes, proportions of CD20 positive B lymphocytes were decreased, and T lymphocytes as well as NK cells were increased in brain compared to blood. Significant changes were also detected for macrophage and T-cell subpopulations. The nonexclusive expression of certain surface makers on different cell populations demanded a simultaneous classification of all intrathecal immune cells. Knowing their exact composition offers new insights on interaction and regulation in inflammatory processes and will be instrumental to monitor alterations in the course of neurological diseases.

Orthostatic Hypertension

See related article, pp 167–173 Orthostatic hypertension (OHT) is beneath the radar of many health care professionals. In the clinic, it is generally both unexpected and counterintuitive. After recheck, it may sometimes regress toward the mean. However, at other times the OHT can be dramatic and persistent. Nevertheless, our knowledge about its causes and significance remains circumscribed. It is in many ways the last hemodynamic frontier. Recently, there has been increasing interest in OHT and its possible consequences on health. The spectrum of degree and clinical context of OHT is very broad.1 In some cases, it can be a dramatic physical manifestation of 50 mm Hg or more in a disorder such as baroreflex failure. In other situations, it may only be an incidental physical finding. OHT is usually defined as an increase in blood pressure with upright posture or tilt, but precise criteria have not been established. Furthermore, few studies have entailed direct measurement of blood pressure in people with OHT. Such measurements would more faithfully reflect intraarterial pressure and would avoid the introduction of potential artifacts. Sphygmomanometers can underestimate blood pressure when it is perturbed by pressor reflexes, such as those engaged by upright posture, or if it is increased by pressor agents. Therefore, the magnitude of the blood pressure increase after standing might be even larger than is generally reported in patients with OHT. OHT has been long recognized. Some of the most thoughtful early studies were conducted by David Streeten …

Pericytes regulate the blood–brain barrier

The blood-brain barrier (BBB) consists of specific physical barriers, enzymes and transporters, which together maintain the necessary extracellular environment of the central nervous system (CNS). The main physical barrier is found in the CNS endothelial cell, and depends on continuous complexes of tight junctions combined with reduced vesicular transport. Other possible constituents of the BBB include extracellular matrix, astrocytes and pericytes, but the relative contribution of these different components to the BBB remains largely unknown. Here we demonstrate a direct role of pericytes at the BBB in vivo. Using a set of adult viable pericyte-deficient mouse mutants we show that pericyte deficiency increases the permeability of the BBB to water and a range of low-molecular-mass and high-molecular-mass tracers. The increased permeability occurs by endothelial transcytosis, a process that is rapidly arrested by the drug imatinib. Furthermore, we show that pericytes function at the BBB in at least two ways: by regulating BBB-specific gene expression patterns in endothelial cells, and by inducing polarization of astrocyte end-feet surrounding CNS blood vessels. Our results indicate a novel and critical role for pericytes in the integration of endothelial and astrocyte functions at the neurovascular unit, and in the regulation of the BBB.

Oxysterols in biological systems: The gastrointestinal tract, liver, vascular wall and central nervous system

Oxysterols are oxygenated derivatives of cholesterol generated from exogenous (food) or endogenous (auto-oxidation and enzymatic conversion) sources. Despite their hepatic capacity to transform into bile acids, oxysterols are present in the blood circulation and central nervous system. This review aims to provide a better understanding of the origins and roles of oxysterols under normal and pathophysiological conditions, such as atherosclerosis and Alzheimer's disease. Oxysterols are metabolites of the cholesterol auto-oxidation pathway present in atherosclerotic plaque and are concomitantly endogenous activators of nuclear receptor liver X receptors known to enhance cholesterol efflux. Despite their honourable role in the gastrointestinal tract and central nervous system, oxysterols have, in general, adverse effects in atherogenesis during which they accumulate and trigger cellular and molecular insults that lead to foam cell formation. This study will discuss the paradox that oxysterols are essential for the normal physiology of the hepatic, central nervous and vascular systems, but that they are also bioactive molecules that lead to adverse effects when they accumulate in the vascular wall.

Normal plasma antithrombin activity in patients with relapsing–remitting and secondary progressive multiple sclerosis

Objective Multiple sclerosis (MS) is an inflammatory disease characterized by multifocal areas of central nervous system (CNS) demyelination. Activation of coagulation factors and fibrin deposition are observed around CNS blood vessels in experimental autoimmune encephalomyelitis, an animal model of MS. Antithrombin (AT) is a potent anticoagulant with remarkable anti-inflammatory properties, and its inhibitory effects on coagulation and inflammation may play a role in the pathogenesis and clinical course of MS. We studied the association between plasma AT activity and clinical forms of MS. Patients and methods A total of 69 patients, 37 with relapsing–remitting and 32 with secondary progressive MS, were included in the study. A control group (CG) of 34 normal subjects was also studied. Plasma AT activity (Stachrom ATIII) was quantified using a chromogenic activity assay with normal reference values ranging from 70% to 120% of AT activity. Results We found no difference between plasma AT levels in patients and those in CG. We also found no association of AT levels with activity of disease, duration of disease progression, level of neurological disability, and treatment. Conclusion We found no association between plasma AT activity and RRMS or SPMS. It remains to be studied whether exists or not an association between abnormal plasma AT activity and other MS forms.

Transport of NSAIDs across the Blood-Brain Barrier in vitro

The migration of substances between blood circulation and central nervous system (CNS) is regulated by the blood-brain barrier (BBB). Small lipophilic molecules such as carbon dioxide, oxygen or ethanol can pass the BBB by passive, transcellular diffusion, while the paracellular transport of hydrophilic substances is restricted by intercellular tight-junctions. Due to accessory transport systems the BBB is able to regulate specifically the permeation of substances (e.g. nutrients) [1].

Drug Interactions with Natural Products at the Blood Brain Barrier

The use of herbal supplements and medicines is rapidly growing as most people consider them as being of natural origin and therefore being safe. However, a significant number of patients combine herbal remedies with prescription medications and there is a growing evidence for interactions of drugs with herbal remedies or single compounds originating from plants. Beside metabolic interactions particularly on the level of barrier tissues being equipped with a multitude of transport proteins such interactions are reason of rising concern. One barrier of particular interest is the blood brain barrier separating blood circulation and central nervous system and protecting the brain from potentially toxic metabolites and xenobiotics. The present review gives a condensed overview about structure and function of the blood-brain barrier and interactions of selected compounds originating from natural products with transport proteins in the barrier.

Developmental Angiogenesis of the Central Nervous System

The vasculature of the central nervous system (CNS) is highly specialized with a blood-brain-barrier, reciprocal neuroepithelial-endothelial cell interactions and extensive pericyte coverage. Developmentally, numerous important signaling pathways participate in CNS angiogenesis to orchestrate the precise timing and spatial arrangement of the complex CNS vascular network. From a therapeutic standpoint, the CNS vasculature has attracted increased attention since many human ailments, such as stroke, retinopathy, cancer and autoimmune disease are intimately associated with the biology of CNS blood vessels. This review focuses on growth factor pathways that have been shown to be important in developmental CNS vascularization through studies of mouse genetic models and human diseases.

After Injection into the Striatum, in Vitro-Differentiated Microglia- and Bone Marrow-Derived Dendritic Cells Can Leave the Central Nervous System via the Blood Stream

The prototypic migratory trail of tissue-resident dendritic cells (DCs) is via lymphatic drainage. Since the central nervous system (CNS) lacks classical lymphatic vessels, and antigens and cells injected into both the CNS and cerebrospinal fluid have been found in deep cervical lymph nodes, it was thought that CNS-derived DCs exclusively used the cerebrospinal fluid pathway to exit from tissues. It has become evident, however, that DCs found in peripheral organs can also leave tissues via the blood stream. To study whether DCs derived from microglia and bone marrow can also use this route of emigration from the CNS, we performed a series of experiments in which we injected genetically labeled DCs into the striata of rats. We show here that these cells migrated from the injection site to the perivascular space, integrated into the endothelial lining of the CNS vasculature, and were then present in the lumen of CNS blood vessels days after the injection. Moreover, we also found these cells in both mesenteric lymph nodes and spleens. Hence, microglia- and bone marrow-derived DCs can leave the CNS via the blood stream.

Novel Vasoconstrictor Formulation to Enhance Intranasal Targeting of Neuropeptide Therapeutics to the Central Nervous System

The intranasal route of drug administration is noninvasive, convenient, and rapidly targets therapeutics to the central nervous system (CNS) using olfactory and trigeminal neural pathways connecting the nasal passages to the brain. The purpose of this research was to enhance intranasal drug targeting to the CNS by incorporating a vasoconstrictor [phenylephrine (PHE)] into nasal formulations containing therapeutic neuropeptides [hypocretin-1 (HC) or the dipeptide L-Tyr-D-Arg (D-KTP)]. Concentrations in CNS tissues, peripheral tissues, and blood were determined at 30 min following intravenous or intranasal administration of (125)I-labeled neuropeptides with and without PHE. Compared with intranasal controls, inclusion of 1% PHE in nasal formulations significantly reduced absorption into the blood for HC (65% reduction) and D-KTP (56% reduction), whereas it significantly increased deposition into the olfactory epithelium by approximately 3-fold for both. PHE (1%) significantly increased delivery to the olfactory bulbs for HC (2.1-fold) and D-KTP (3.0-fold), whereas it significantly reduced concentrations in the trigeminal nerve for HC (65% reduction) and D-KTP (39% reduction) and in most remaining brain regions by approximately 50% for both. The dramatic reduction in blood concentrations with PHE contributed to brain-to-blood concentration ratios that were significantly increased for HC throughout the brain (1.6-6.8-fold) compared with intranasal controls. For D-KTP, 1% PHE significantly increased ratios only in the olfactory bulbs (5.3-fold). With a 5% PHE formulation, D-KTP ratios were significantly increased to additional brain areas (1.5-16-fold). Vasoconstrictor nasal formulations may have particular relevance for CNS therapeutics with adverse side effects where it would be advantageous to limit systemic exposure.

Postulated vasoactive neuropeptide immunopathology affecting the blood&amp;ndash;brain/blood&amp;ndash;spinal barrier in certain neuropsychiatric fatigue-related conditions: A role for phosphodiesterase inhibitors in treatment?

Neuropsychiatric symptoms occur in a number of neurological fatigue-related conditions including multiple sclerosis (MS), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and chronic fatigue syndrome (CFS). These conditions have been attributed variably to neuroinflammatory and neurodegenerative processes. While autoimmune pathology, at least in part, has long been suspected in these conditions proof has been elusive. Autoimmune pathomechanisms affecting the blood-brain barrier (BBB) or blood-spinal barrier (BSB) may predispose the BBB/BSB to 'leakiness' and be a precursor to additional autoimmune events resulting in neuroinflammatory or neurodegenerative processes. The aim of the paper is to postulate immunopathology of the cerebrospinal perivascular compartment involving certain vasoactive neuropeptides, specifically pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP), in the etiology of certain neuropsychiatric fatigue-related conditions such as MS, ALS, PD, and CFS. Vasoactive neuropeptides (VNs) such as PACAP and VIP have critical roles as neurotransmitters, vasodilators including perfusion and hypoxia regulators, and immune and nociception modulators. PACAP and VIP are widely distributed in the central nervous system (CNS) and have key roles in CNS blood vessels including maintaining functional integrity of the BBB and BSB. Autoimmunity affecting these VNs would likely have a detrimental effect on BBB and BSB functioning arguably predisposing to further pathological processes. Virchow-Robin spaces (VRS) are perivascular compartments surrounding small vessels within the CNS which contribute to the BBB and BSB integrity and contain PACAP and VIP receptors. Autoimmunity of these receptors would likely affect BBB and VRS function and therefore may contribute to the etiology of these conditions by affecting CNS and immunological homeostasis, including promoting neuropsychological symptomatology. PACAP and VIP, as potent activators of adenylate cyclase (AC), have a key role in cyclic adenosine monophosphate (cAMP) production affecting regulatory T cell (Treg) and other immune functions. Phosphodiesterase enzymes (PDEs) catalyze cAMP and PDE inhibitors (PDEIs) maintain cAMP levels and have proven and well known therapeutic benefit in animal models such as experimental allergic encephalomyelitis (EAE). Therefore PDEIs may have a role in therapy for certain neuropsychiatric fatigue-related conditions.