LXA4, aspirin-triggered 15-epi-LXA4, and their analogs selectively downregulate PMN azurophilic degranulation

The eicosanoid lipoxin A4(LXA4) is biosynthesized in vivo by cells present at inflammatory sites and appears to be an endogenous anti-inflammatory mediator. Further, in the presence of aspirin, the 15-epimer of LXA4(15-epi-LXA4) is biosynthesized and may mediate some of aspirin’s desirable bioactions. LXA4, 15-epi-LXA4, and their stable analogs inhibit inflammation in established animal models, indicating that these compounds may be useful for treating inflammatory disease states. To investigate the cellular mechanisms by which these lipid mediators downregulate inflammation, we investigated whether these eicosanoids could influence receptor-mediated degranulation of human neutrophils, an event thought to play a major causative role in several inflammatory disease states. LXA4, 15-epi-LXA4, and their stable analogs potently (IC50< 1 nM) and selectively downregulated neutrophil release of azurophilic granule contents but did not affect other neutrophil secretory functions. Thus the cellular basis of action of these natural off-switches to inflammation appears to involve downregulation of neutrophil azurophilic granule release.

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Evidence for an Increased Generation of Prostacyclin in the Microvasculature and an Impairment of the Platelet α-Granule Release in Chronic Renal Failure

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647030 ◽

1988 ◽

Vol 60 (02) ◽

pp. 205-208 ◽

Cited By ~ 21

Author(s):

Paul A Kyrle ◽

Felix Stockenhuber ◽

Brigitte Brenner ◽

Heinz Gössinger ◽

Christian Korninger ◽

...

Keyword(s):

Renal Failure ◽

Chronic Renal Failure ◽

Blood Clotting ◽

Normal Subjects ◽

Chronic Uraemia ◽

Wall Interaction ◽

End Stage ◽

Granule Release

SummaryThe formation of prostacyclin (PGI2) and thromboxane A2 and the release of beta-thromboglobulin (beta-TG) at the site of platelet-vessel wall interaction, i.e. in blood emerging from a standardized injury of the micro vasculature made to determine bleeding time, was studied in patients with end-stage chronic renal failure undergoing regular haemodialysis and in normal subjects. In the uraemic patients, levels of 6-keto-prostaglandin F1α (6-keto-PGF1α) were 1.3-fold to 6.3-fold higher than the corresponding values in the control subjects indicating an increased PGI2 formation in chronic uraemia. Formation of thromboxane B2 (TxB2) at the site of plug formation in vivo and during whole blood clotting in vitro was similar in the uraemic subjects and in the normals excluding a major defect in platelet prostaglandin metabolism in chronic renal failure. Significantly smaller amounts of beta-TG were found in blood obtained from the site of vascular injury as well as after in vitro blood clotting in patients with chronic renal failure indicating an impairment of the a-granule release in chronic uraemia. We therefore conclude that the haemorrhagic diathesis commonly seen in patients with chronic renal failure is - at least partially - due to an acquired defect of the platelet a-granule release and an increased generation of PGI2 in the micro vasculature.

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Investigation of the Interaction of Blood Platelets with the Coagulation System at the Site of Plug Formation In Vivo in Man - Effect of Low-Dose Aspirin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1651063 ◽

1987 ◽

Vol 57 (01) ◽

pp. 062-066 ◽

Cited By ~ 36

Author(s):

P A Kyrle ◽

J Westwick ◽

M F Scully ◽

V V Kakkar ◽

G P Lewis

Keyword(s):

Platelet Activation ◽

Thrombin Generation ◽

Low Dose ◽

Bleeding Time ◽

Blood Platelets ◽

Dose Aspirin ◽

Low Dose Aspirin ◽

Plug Formation ◽

Granule Release

SummaryIn 7 healthy volunteers, formation of thrombin (represented by fibrinopeptide A (FPA) generation, α-granule release (represented by β-thromboglobulin [βTG] release) and the generation of thromboxane B2 (TxB2) were measured in vivo in blood emerging from a template bleeding time incision. At the site of plug formation, considerable platelet activation and thrombin generation were seen within the first minute, as indicated by a 110-fold, 50-fold and 30-fold increase of FPA, TxB2 and PTG over the corresponding plasma values. After a further increase of the markers in the subsequent 3 minutes, they reached a plateau during the fourth and fifth minute. A low-dose aspirin regimen (0.42 mg.kg-1.day-1 for 7 days) caused >90% inhibition of TxB2formation in both bleeding time blood and clotted blood. At the site of plug formation, a-granule release was substantially reduced within the first three minutes and thrombin generation was similarly inhibited. We conclude that (a) marked platelet activation and considerable thrombin generation occur in the early stages.of haemostasis, (b) α-granule release in vivo is partially dependent upon cyclo-oxygenase-controlled mechanisms and (c) thrombin generation at the site of plug formation is promoted by the activation of platelets.

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Detection of Enhanced In Vivo Platelet α-Granule Release in Different Patient Groups - Comparison of β-Thromboglobulin, Platelet Factor 4 and Thrombospondin Assays

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661168 ◽

1984 ◽

Vol 52 (02) ◽

pp. 183-187 ◽

Cited By ~ 31

Author(s):

D A Lane ◽

H Ireland ◽

S Wolff ◽

E Ranasinghe ◽

J Dawes

Keyword(s):

Platelet Factor 4 ◽

Renal Elimination ◽

Elevated Plasma ◽

Platelet Factor ◽

Release Reaction ◽

Heparin Anticoagulation ◽

Patient Groups ◽

Granule Release ◽

Sensitive Marker

SummaryDuring the platelet release reaction β-thromboglobulin (βTG), platelet factor 4 (PF4) and thrombospondin (TSP) are released from the platelet into plasma and assays of these proteins can be used to monitor in vivo platelet activation. We have assessed their relative merits as markers of the in vivo platelet α-granule release reaction in a number of patient groups which have previously been shown to have elevated plasma βTG and/or PF4 levels. It is concluded that in diseases or conditions not complicated by its reduced clearance, βTG is the most sensitive marker of in vivo platelet α-granule release. However, the TSP assay may be the least ambiguous when monitoring the platelet α-granule release reaction in patients with renal failure who are undergoing haemodialysis with heparin anticoagulation. Under these circumstances plasma βTG, but not PF4 or TSP, levels are elevated because of impaired renal catabolism, and the presence of a heparin-releasable reservoir of PF4 on the endothelium complicates the use of the PF4 assay. In liver failure none of these assays may accurately reflect platelet α-granule release because of impaired hepatic or renal elimination of the proteins.

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Nitroxyl Modified Tobacco Mosaic Virus as a Metal-Free High-Relaxivity MRI and EPR Active Superoxide Sensor

10.26434/chemrxiv.6241913 ◽

2018 ◽

Author(s):

Madushani Dharmarwardana ◽

André F. Martins ◽

Zhuo Chen ◽

Philip M. Palacios ◽

Chance M. Nowak ◽

...

Keyword(s):

Tobacco Mosaic Virus ◽

Mosaic Virus ◽

Single Molecule ◽

Biological Fluids ◽

Cellular Respiration ◽

Organic Radical ◽

Paramagnetic Resonance ◽

Metal Free ◽

Disease States

Superoxide overproduction is known to occur in multiple disease states requiring critical care yet non-invasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by “click conjugating” paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced in vivo to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species—in particular superoxide—and are largely unaffected by peroxides and molecular oxygen. Unfortunately, single molecule ORCAs typically offer weak MRI contrast. In contrast, our data confirm that the macromolecular ORCA-TMV conjugates show marked enhancement for T1 contrast at low field (<3.0 T), and T2 contrast at high field (9.4 T). Additionally, we demonstrated that the unique topology of TMV allows for “quenchless fluorescent” bimodal probe for concurrent fluorescence and MRI/EPR imaging, which was made possible by exploiting the unique inner and outer surface of the TMV nanoparticle. <a>Finally, we show TMV-ORCAs do not respond to normal cellular respiration, minimizing the likelihood for background, yet still respond to enzymatically produced superoxide in complicated biological fluids like serum.</a>

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Molecular and Cellular Mechanisms of Metformin in Cervical Cancer

Cancers ◽

10.3390/cancers13112545 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2545

Author(s):

Ya-Hui Chen ◽

Po-Hui Wang ◽

Pei-Ni Chen ◽

Shun-Fa Yang ◽

Yi-Hsuan Hsiao

Keyword(s):

Cervical Cancer ◽

Potential Role ◽

Treatment Options ◽

Cellular Mechanisms ◽

Anticancer Effects ◽

Clinical Benefits ◽

Underlying Mechanisms

Cervical cancer is one of the major gynecologic malignancies worldwide. Treatment options include chemotherapy, surgical resection, radiotherapy, or a combination of these treatments; however, relapse and recurrence may occur, and the outcome may not be favorable. Metformin is an established, safe, well-tolerated drug used in the treatment of type 2 diabetes; it can be safely combined with other antidiabetic agents. Diabetes, possibly associated with an increased site-specific cancer risk, may relate to the progression or initiation of specific types of cancer. The potential effects of metformin in terms of cancer prevention and therapy have been widely studied, and a number of studies have indicated its potential role in cancer treatment. The most frequently proposed mechanism underlying the diabetes–cancer association is insulin resistance, which leads to secondary hyperinsulinemia; furthermore, insulin may exert mitogenic effects through the insulin-like growth factor 1 (IGF-1) receptor, and hyperglycemia may worsen carcinogenesis through the induction of oxidative stress. Evidence has suggested clinical benefits of metformin in the treatment of gynecologic cancers. Combining current anticancer drugs with metformin may increase their efficacy and diminish adverse drug reactions. Accumulating evidence is indicating that metformin exerts anticancer effects alone or in combination with other agents in cervical cancer in vitro and in vivo. Metformin might thus serve as an adjunct therapeutic agent for cervical cancer. Here, we reviewed the potential anticancer effects of metformin against cervical cancer and discussed possible underlying mechanisms.

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Hippocampal Interneurons are Required for Trace Eyeblink Conditioning in Mice

Neuroscience Bulletin ◽

10.1007/s12264-021-00700-0 ◽

2021 ◽

Author(s):

Wei-Wei Zhang ◽

Rong-Rong Li ◽

Jie Zhang ◽

Jie Yan ◽

Qian-Hui Zhang ◽

...

Keyword(s):

Eyeblink Conditioning ◽

Pyramidal Cells ◽

Conditioned Eyeblink ◽

Cellular Mechanisms ◽

Sustained Activity ◽

Early Acquisition ◽

Freely Moving ◽

Trace Eyeblink Conditioning

AbstractWhile the hippocampus has been implicated in supporting the association among time-separated events, the underlying cellular mechanisms have not been fully clarified. Here, we combined in vivo multi-channel recording and optogenetics to investigate the activity of hippocampal interneurons in freely-moving mice performing a trace eyeblink conditioning (tEBC) task. We found that the hippocampal interneurons exhibited conditioned stimulus (CS)-evoked sustained activity, which predicted the performance of conditioned eyeblink responses (CRs) in the early acquisition of the tEBC. Consistent with this, greater proportions of hippocampal pyramidal cells showed CS-evoked decreased activity in the early acquisition of the tEBC. Moreover, optogenetic suppression of the sustained activity in hippocampal interneurons severely impaired acquisition of the tEBC. In contrast, suppression of the sustained activity of hippocampal interneurons had no effect on the performance of well-learned CRs. Our findings highlight the role of hippocampal interneurons in the tEBC, and point to a potential cellular mechanism subserving associative learning.

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Characterization and Reconstitution of Human Lipoyl Synthase (LIAS) Supports ISCA2 and ISCU as Primary Cluster Donors and an Ordered Mechanism of Cluster Assembly

International Journal of Molecular Sciences ◽

10.3390/ijms22041598 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1598

Author(s):

Amber L. Hendricks ◽

Christine Wachnowsky ◽

Brian Fries ◽

Insiya Fidai ◽

James A. Cowan

Keyword(s):

Cluster Assembly ◽

Paramagnetic Resonance ◽

Iron Sulfur Cluster ◽

Sulfur Transfer ◽

Disease States ◽

Isolation And Characterization ◽

Iron Sulfur ◽

Natural Iron ◽

Lipoyl Synthase

Lipoyl synthase (LIAS) is an iron–sulfur cluster protein and a member of the radical S-adenosylmethionine (SAM) superfamily that catalyzes the final step of lipoic acid biosynthesis. The enzyme contains two [4Fe–4S] centers (reducing and auxiliary clusters) that promote radical formation and sulfur transfer, respectively. Most information concerning LIAS and its mechanism has been determined from prokaryotic enzymes. Herein, we detail the expression, isolation, and characterization of human LIAS, its reactivity, and evaluation of natural iron–sulfur (Fe–S) cluster reconstitution mechanisms. Cluster donation by a number of possible cluster donor proteins and heterodimeric complexes has been evaluated. [2Fe–2S]-cluster-bound forms of human ISCU and ISCA2 were found capable of reconstituting human LIAS, such that complete product turnover was enabled for LIAS, as monitored via a liquid chromatography–mass spectrometry (LC–MS) assay. Electron paramagnetic resonance (EPR) studies of native LIAS and substituted derivatives that lacked the ability to bind one or the other of LIAS’s two [4Fe–4S] clusters revealed a likely order of cluster addition, with the auxiliary cluster preceding the reducing [4Fe–4S] center. These results detail the trafficking of Fe–S clusters in human cells and highlight differences with respect to bacterial LIAS analogs. Likely in vivo Fe–S cluster donors to LIAS are identified, with possible connections to human disease states, and a mechanistic ordering of [4Fe–4S] cluster reconstitution is evident.

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A sand fly salivary protein acts as a neutrophil chemoattractant

Nature Communications ◽

10.1038/s41467-021-23002-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Anderson B. Guimaraes-Costa ◽

John P. Shannon ◽

Ingrid Waclawiak ◽

Jullyanna Oliveira ◽

Claudio Meneses ◽

...

Keyword(s):

Inflammatory Responses ◽

Calcium Influx ◽

Parasite Burden ◽

Salivary Protein ◽

Sand Fly ◽

Human Neutrophils ◽

Chemotactic Protein ◽

The Impact

AbstractApart from bacterial formyl peptides or viral chemokine mimicry, a non-vertebrate or insect protein that directly attracts mammalian innate cells such as neutrophils has not been molecularly characterized. Here, we show that members of sand fly yellow salivary proteins induce in vitro chemotaxis of mouse, canine and human neutrophils in transwell migration or EZ-TAXIScan assays. We demonstrate murine neutrophil recruitment in vivo using flow cytometry and two-photon intravital microscopy in Lysozyme-M-eGFP transgenic mice. We establish that the structure of this ~ 45 kDa neutrophil chemotactic protein does not resemble that of known chemokines. This chemoattractant acts through a G-protein-coupled receptor and is dependent on calcium influx. Of significance, this chemoattractant protein enhances lesion pathology (P < 0.0001) and increases parasite burden (P < 0.001) in mice upon co-injection with Leishmania parasites, underlining the impact of the sand fly salivary yellow proteins on disease outcome. These findings show that some arthropod vector-derived factors, such as this chemotactic salivary protein, activate rather than inhibit the host innate immune response, and that pathogens take advantage of these inflammatory responses to establish in the host.

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Chloride Movements in Human Neutrophils during Phagocytosis: Characterization and Relationship to Granule Release

The Journal of Immunology ◽

10.4049/jimmunol.179.6.4110 ◽

2007 ◽

Vol 179 (6) ◽

pp. 4110-4124 ◽

Cited By ~ 24

Author(s):

Sara Busetto ◽

Elisa Trevisan ◽

Eva Decleva ◽

Pietro Dri ◽

Renzo Menegazzi

Keyword(s):

Human Neutrophils ◽

Granule Release

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Cellular correlates of gray matter volume changes in magnetic resonance morphometry identified by two-photon microscopy

Scientific Reports ◽

10.1038/s41598-021-83491-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Livia Asan ◽

Claudia Falfán-Melgoza ◽

Carlo A. Beretta ◽

Markus Sack ◽

Lei Zheng ◽

...

Keyword(s):

Magnetic Resonance ◽

Cell Density ◽

Gray Matter ◽

Gray Matter Volume ◽

Cell Nuclei ◽

Cellular Mechanisms ◽

Tissue Volume ◽

Two Photon ◽

Matter Volume

AbstractMagnetic resonance imaging (MRI) of the brain combined with voxel-based morphometry (VBM) revealed changes in gray matter volume (GMV) in various disorders. However, the cellular basis of GMV changes has remained largely unclear. We correlated changes in GMV with cellular metrics by imaging mice with MRI and two-photon in vivo microscopy at three time points within 12 weeks, taking advantage of age-dependent changes in brain structure. Imaging fluorescent cell nuclei allowed inferences on (i) physical tissue volume as determined from reference spaces outlined by nuclei, (ii) cell density, (iii) the extent of cell clustering, and (iv) the volume of cell nuclei. Our data indicate that physical tissue volume alterations only account for 13.0% of the variance in GMV change. However, when including comprehensive measurements of nucleus volume and cell density, 35.6% of the GMV variance could be explained, highlighting the influence of distinct cellular mechanisms on VBM results.

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