scholarly journals Citrullinated myelin induces microglial TNFα and inhibits endogenous repair in the cuprizone model of demyelination

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Miranda M. Standiford ◽  
Ethan M. Grund ◽  
Charles L. Howe
Keyword(s):  
Microglial Activation ◽  
Primary Motor Cortex ◽  
Ex Vivo ◽  
Arginine Deiminase ◽  
Calcium Dependent ◽  
Cingulum Bundle ◽  
Normal Chow ◽  
Demyelinating Disorders

Abstract Background Microglia are the primary phagocytes of the central nervous system and are responsible for removing damaged myelin following demyelination. Previous investigations exploring the consequences of myelin phagocytosis on microglial activation overlooked the biochemical modifications present on myelin debris. Such modifications, including citrullination, are increased within the inflammatory environment of multiple sclerosis lesions. Methods Mouse cortical myelin isolated by ultracentrifugation was citrullinated ex vivo by incubation with the calcium-dependent peptidyl arginine deiminase PAD2. Demyelination was induced by 6 weeks of cuprizone (0.3%) treatment and spontaneous repair was initiated by reversion to normal chow. Citrullinated or unmodified myelin was injected into the primary motor cortex above the cingulum bundle at the time of reversion to normal chow and the consequent impact on remyelination was assessed by measuring the surface area of myelin basic protein-positive fibers in the cortex 3 weeks later. Microglial responses to myelin were characterized by measuring cytokine release, assessing flow cytometric markers of microglial activation, and RNAseq profiling of transcriptional changes. Results Citrullinated myelin induced a unique microglial response marked by increased tumor necrosis factor α (TNFα) production both in vitro and in vivo. This response was not induced by unmodified myelin. Injection of citrullinated myelin but not unmodified myelin into the cortex of cuprizone-demyelinated mice significantly inhibited spontaneous remyelination. Antibody-mediated neutralization of TNFα blocked this effect and restored remyelination to normal levels. Conclusions These findings highlight the role of post-translation modifications such as citrullination in the determination of microglial activation in response to myelin during demyelination. The inhibition of endogenous repair induced by citrullinated myelin and the reversal of this effect by neutralization of TNFα may have implications for therapeutic approaches to patients with inflammatory demyelinating disorders.

scholarly journals Sympathetic cardiac hyperinnervation and atrial autonomic imbalance in diet-induced obesity promote cardiac arrhythmias

2013 ◽  
Vol 305 (10) ◽  
pp. H1530-H1537 ◽  
Author(s):  
Belinda H. McCully ◽  
Wohaib Hasan ◽  
Cole T. Streiff ◽  
Jennifer C. Houle ◽  
William R. Woodward ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Parasympathetic Nervous System ◽  
Ex Vivo ◽  
System Control ◽  
Sprague Dawley ◽  
High Fat ◽  
Sprague Dawley Rats ◽  
Normal Chow

Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250–275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Significance of Platelet β-Adrenoceptors for Platelet Responses In Vivo and In Vitro

1992 ◽  
Vol 68 (06) ◽  
pp. 687-693 ◽  
Author(s):  
P T Larsson ◽  
N H Wallén ◽  
A Martinsson ◽  
N Egberg ◽  
P Hjemdahl
Keyword(s):  
Ex Vivo ◽  
High Dose ◽  
Platelet Aggregability ◽  
Adrenoceptor Agonist ◽  
Dose Infusion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThe significance of platelet β-adrenoceptors for platelet responses to adrenergic stimuli in vivo and in vitro was studied in healthy volunteers. Low dose infusion of the β-adrenoceptor agonist isoprenaline decreased platelet aggregability in vivo as measured by ex vivo filtragometry. Infusion of adrenaline, a mixed α- and β-adrenoceptor agonist, increased platelet aggregability in vivo markedly, as measured by ex vivo filtragometry and plasma β-thromboglobulin levels. Adrenaline levels were 3–4 nM in venous plasma during infusion. Both adrenaline and high dose isoprenaline elevated plasma von Willebrand factor antigen levels β-Blockade by propranolol did not alter our measures of platelet aggregability at rest or during adrenaline infusions, but inhibited adrenaline-induced increases in vWf:ag. In a model using filtragometry to assess platelet aggregability in whole blood in vitro, propranolol enhanced the proaggregatory actions of 5 nM, but not of 10 nM adrenaline. The present data suggest that β-adrenoceptor stimulation can inhibit platelet function in vivo but that effects of adrenaline at high physiological concentrations are dominated by an α-adrenoceptor mediated proaggregatory action.

In Vivo Effect of Suloctidil as an Antiplatelet Agent

1979 ◽  
Vol 41 (03) ◽  
pp. 465-474 ◽  
Author(s):  
Marcia R Stelzer ◽  
Thomas S Burns ◽  
Robert N Saunders
Keyword(s):  
Ex Vivo ◽  
Antiplatelet Agent ◽  
Ratio Method ◽  
Platelet Aggregate ◽  
Permanent Effect ◽  
Platelet Aggregates ◽  
5 Ht Uptake ◽  
High Doses

SummaryThe relationship between the effects of suloctidil in vivo as an antiplatelet agent and in vitro as a modifier of platelet serotonin (5-HT) parameters was investigated. Suloctidil was found to be effective in reducing platelet aggregates formation in the retired breeder rat as determined using the platelet aggregate ratio method (PAR) with an ED50 of 16.1 mg/kg 24 hours post administration. In contrast to the hypothesis that 5-HT depletion is involved in the anti-aggregatory mechanism of suloctidil, no correlation was found between platelet 5- HT content and this antiplatelet activity. Reduction of platelet 5-HT content required multiple injections of high doses (100 mg/kg/day) of suloctidil. Suloctidil administration for 8 days at 100 mg/kg/day, which lowered platelet 5-HT content by 50%, resulted in no permanent effect on ex vivo platelet 5-HT uptake or thrombin-induced release, nor alteration in the plasma 5-HT level. However, these platelets exhibited a short-lived, significant increase in percent leakage of 5-HT after 30 minutes of incubation. Therefore, suloctidil treatment at high doses may with time result in platelet 5-HT depletion, however this effect is probably not related to the primary anti-aggregatory activity of the drug.

A Comparative Ex Vivo Study of Plasminogen Activators and Proteases for Fibrinolytic Activity and Side Effects in Rabbits

1977 ◽  
Vol 37 (01) ◽  
pp. 154-161 ◽  
Author(s):  
B. A Janik ◽  
S. E Papaioannou
Keyword(s):  
Side Effects ◽  
Effective Dose ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Plasminogen Activators ◽  
Assay System ◽  
Coagulation Parameters ◽  
Ex Vivo Assay

SummaryUrokinase, streptokinase, Brinase, trypsin, and SN 687, a bacterial exoprotease, have been evaluated in an ex vivo assay system. These enzymes were injected into rabbits and the fibrinolytic activity as well as other coagulation parameters were measured by in vitro techniques. Dose-response correlations have been made using the euglobulin lysis time as a measure of fibrinolytic activity and the 50% effective dose has been determined for each enzyme. Loading doses, equal to four times the 50% effective dose, were administered to monitor potential toxicity revealing that Brinase, trypsin, and SN 687 were very toxic at this concentration.Having established the 50% effective dose for each enzyme, further testing was conducted where relevant fibrinolytic and coagulation parameters were measured for up to two days following a 50% effective dose bolus injection of each enzyme. Our results have demonstrated that urokinase and streptokinase are plasminogen activators specifically activating the rabbit fibrinolytic system while Brinase, trypsin and SN 687 increase the general proteolytic activity in vivo.The advantages of this ex vivo assay system for evaluating relative fibrinolytic potencies and side effects for plasminogen activators and fibrinolytic proteases have been discussed.

Organische Nitrate und Thrombozytenfunktion

1988 ◽  
Vol 08 (02) ◽  
pp. 90-99 ◽  
Author(s):  
H. Schröder ◽  
K. Schrör
Keyword(s):  
Endothelial Cell ◽  
Angina Pectoris ◽  
Ex Vivo

ZusammenfassungOrganische Nitrate unterschiedlicher chemischer Struktur sowie Nitroprussidnatrium und Molsidomin (bzw. ihre biologisch aktiven Metaboliten) können die (primäre) Aggregation und Sekretion von Humanthrombozyten in vitro und ex vivo hemmen. Eine solche Wirkung wird für Molsidomin (SIN-1) und Nitroprussidnatrium in vitro in Konzentrationen beobachtet, die in der gleichen Größenordnung liegen wie die vasodilatierenden Effekte der Substanzen. Dagegen sind für eine direkte Antiplättchenwirkung organischer Nitrate (Glyzeryltrinitrat, Isosorbiddinitr at, Isosorbidmononitrate, Teopranitol) in vitro Konzentrationen erforderlich, die ca. 100- bis 1000fach höher sind als die Plasmaspiegel der Substanzen nach therapeutischer Dosierung bzw. die Konzentrationen, die isolierte Gefäßstreifen relaxieren. Als gemeinsamer Wirkungsmechanismus der direkten thrombozy-tenfunktionshemmenden und gefäßerweiternden Wirkung all dieser Substanzen kann heute eine Stickoxid-(NO)-vermittelte Stimulation der cGMP-Bildung angenommen werden, das aus organischen Nitraten als »Pro-drug« entsteht. Die Freisetzung von NO, eines »endothelial cell-derived relaxing factors« (EDRF) aus Nitroprussidnatrium und SIN-1 erfolgt spontan. Dagegen erfordert die Freisetzung von NO aus organischen Nitraten einen enzymatischen Stoffwechselweg, der in isolierten Thrombozyten nicht vorhanden ist. Eine Antiplättchenwirkung organischer Nitrate in vivo bzw. ex vivo wird daher über die Stimulation eines endothelialen, thrombozyteninhibitorischen Faktors erklärt. Hierbei sind Prostazyklin sowie ein bisher unbekannter Endothel-zellfaktor neben einer synergistischen Wirkung organischer Nitrate mit endogenem Prostazyklin in Diskussion. Eine thrombozytenfunktionshemmen-de Wirkung organischer Nitrate könnte in Kombination mit ihren hämody-namischen Effekten auch für die an-tianginöse Wirkung in der Klinik bedeutsam sein, insbesondere zur Verhinderung vasospastischer Zustände bei der instabilen Angina pectoris.

Repurposing N,N-Dimethylacetamide (DMA), a Pharmaceutical Excipient, as a Prototype Novel Anti-inflammatory Agent for the Prevention and/or Treatment of Preterm Birth

2018 ◽  
Vol 24 (9) ◽  
pp. 989-992 ◽  
Author(s):  
Samir Gorasiya ◽  
Juliet Mushi ◽  
Ryan Pekson ◽  
Sabesan Yoganathan ◽  
Sandra E. Reznik
Keyword(s):  
Preterm Birth ◽  
Ex Vivo ◽  
The United States ◽  
Occurrence Rate ◽  
Pharmaceutical Excipient ◽  
Ongoing Work ◽  
Exciting Line ◽  
Pregnant Mice

Background: Preterm birth (PTB), or birth that occurs before 37 weeks of gestation, accounts for the majority of perinatal morbidity and mortality. As of 2016, PTB has an occurrence rate of 9.6% in the United States and accounts for up to 18 percent of births worldwide. Inflammation has been identified as the most common cause of PTB, but effective pharmacotherapy has yet to be developed to prevent inflammation driven PTB. Our group has discovered that N,N-dimethylacetamide (DMA), a readily available solvent commonly used as a pharmaceutical excipient, rescues lipopolysaccharide (LPS)-induced timed pregnant mice from PTB. Methods: We have used in vivo, ex vivo and in vitro approaches to investigate this compound further. Results: Interestingly, we found that DMA suppresses cytokine secretion by inhibiting nuclear factor-kappa B (NF-κB). In ongoing work in this exciting line of investigation, we are currently investigating structural analogs of DMA, some of them novel, to optimize this approach focused on the inflammation associated with PTB. Conclusion: Successful development of pharmacotherapy for the prevention of PTB rests upon the pursuit of multiple strategies to solve this important clinical challenge.

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