Abstract 384: Interleukin-6 Mediates the Altered Platelet Function Associated with Experimental Colonic Inflammation

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Li-Sue S Yan
Keyword(s):  
Platelet Activation ◽  
Platelet Function ◽  
Interleukin 6 ◽  
Blood Platelets ◽  
Critical Role ◽  
Experimental Colitis ◽  
Membrane Expression ◽  
Colonic Inflammation ◽  
Dss Colitis ◽  
Chronic Infusion

Patients with inflammatory bowel disease (IBD) are susceptible to microvascular thrombosis and thromboembolism. The increased incidence of thrombosis is accompanied by enhanced coagulation and abnormalities in platelet function. Clinical studies have also revealed alterations in platelet activation, enhanced platelet-leukocyte interaction, and elevated plasma levels of prothrombotic cytokines, such as IL-6. This study was directed towards determining whether: 1) experimental colitis, induced by 6 days of dextran sodium sulfate (DSS) ingestion, is associated with platelet activation and the formation of platelet-leukocyte aggregates (PLAs), 2) IL-6 deficiency alters these responses to DSS colitis, and 3) the platelet abnormalities observed in DSS mice can be recapitulated by chronic infusion of murine recombinant IL-6. Flow cytometry was used to characterize platelet function in heparin-anticoagulated whole blood. Platelets were identified by characteristic light scattering and membrane expression of CD41. Platelet activation was monitored using the expression of an activation epitope of GPIIb/IIIa integrin (with JON/A antibody). The combination of CD41, CD45.2, Gr-1, F4/80 and isotype control antibodies were used to detect and quantify aggregates of leukocytes, neutrophils and monocytes with platelets in control, wild type (WT) colitic, IL-6 -/- colitic, and WT mice implanted with IL-6 loaded Alzet osmotic minipumps (for 6 days). Our results indicate that DSS colitis is associated with increased numbers of activated platelets and the formation of aggregates of leukocytes (PLA), neutrophils (PNA) and monocytes (PMA) with platelets. These platelet responses to experimental colitis were largely undetected in IL-6 -/- mice. Chronic infusion (at a rate that yielded plasma IL-6 levels similar to those detected in DSS colitic mice) of IL-6 recapitulated the increased platelet activation and formation of PLA, PNA, and PMA observed in DSS-colitic mice. Collectively, these findings show that the altered platelet function detected in human IBD can be reproduced in an animal model of colonic inflammation and that interleukin-6 plays a critical role in the genesis of these platelet abnormalities in the setting of experimental IBD.

scholarly journals Influence of γ-Secretase Inhibitor 24-Diamino-5-Phenylthiazole DAPT on Platelet Activation

2016 ◽  
Vol 38 (2) ◽  
pp. 726-736 ◽  
Author(s):  
Guoxing Liu ◽  
Guilai Liu ◽  
Madhumita Chatterjee ◽  
Anja T. Umbach ◽  
Hong Chen ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Function ◽  
Blood Platelets ◽  
Annexin V ◽  
Negative Regulator ◽  
Ros Generation ◽  
Integrin Activation ◽  
Forward Scatter ◽  
Secretase Inhibitor ◽  
Αiibβ3 Integrin

Background/Aims: DAPT (24-diamino-5-phenylthiazole) inhibits γ-secretase, which cleaves the signaling molecule CD44, a negative regulator of platelet activation and apoptosis. CD44 is a co-receptor for macrophage migration inhibitory factor (MIF) an anti-apoptotic pro-inflammatory cytokine expressed and released from blood platelets. Whether DAPT influences platelet function, remained, however, elusive. Activators of platelets include collagen related peptide (CRP). The present study thus explored whether DAPT modifies the stimulating effect of CRP on platelet function. Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to DAPT (10 µM). Flow cytometry was employed to estimate Orai1 abundance with specific antibodies, cytosolic Ca2+-activity ([Ca2+]i) from Fluo-3 fluorescence, platelet degranulation from P-selectin abundance, integrin activation from αIIbβ3 integrin abundance, generation of reactive oxygen species (ROS) from DCFDA fluorescence, mitochondrial transmembrane potential from TMRE fluorescence, phospholipid scrambling of the cell membrane from annexin-V-binding, relative platelet volume from forward scatter and aggregation utilizing staining with CD9-APC and CD9-PE. Results: Exposure of platelets to 2-5 µg/ml CRP was followed by significant increase of Orai1 abundance, [Ca2+]i, and P-selectin abundance, as well as by αIIbβ3 integrin activation, ROS generation, mitochondrial depolarization, enhanced annexin-V-binding, decreased cell volume, and aggregation. All CRP induced effects were significantly blunted in the presence of DAPT. Conclusions: The γ-secretase inhibitor DAPT counteracts agonist induced platelet activation, apoptosis and aggregation.

scholarly journals Alteration of platelet function in dogs mediated by interleukin-6

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 398-403
Author(s):  
J Peng ◽  
P Friese ◽  
JN George ◽  
GL Dale ◽  
SA Burstein
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Activation ◽  
Platelet Function ◽  
Interleukin 6 ◽  
Platelet Activating Factor ◽  
Platelet Surface ◽  
Thrombin Activation ◽  
Dog Blood ◽  
And Control ◽  
Twofold Decrease

To determine if interleukin-6 (IL-6) administration influences platelet function, platelet activation was analyzed sequentially in IL-6-treated (80 micrograms/kg/d) and control dogs. Platelet activation was determined in whole blood by flow cytometry by quantitating the binding of a monoclonal antibody to platelet surface P-selectin after stimulation with graded doses of thrombin. Administration of IL-6 resulted in a twofold decrease in the thrombin concentration required for induction of half-maximal P-selectin expression (ED50) compared with control animals. The ED50 returned to normal after cessation of IL- 6 administration. As measured by P-selectin expression, enhanced responsiveness to the strong agonist platelet activating factor (PAF) was also observed in the IL-6-treated dogs. IL-6 had no effect on the susceptibility of platelets to thrombin activation when incubated with anticoagulated dog blood. The data show that, in addition to augmenting the platelet count in normal dogs, IL-6 enhances the sensitivity of platelets to activation in response to thrombin and PAF.

scholarly journals Tamoxifen Directly Disrupts Platelet Angiogenic Potential and Inhibits Platelet-Mediated Metastasis

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4169-4169
Author(s):  
Elisabeth M. Battinelli ◽  
Rajesh Kulenthirarajan ◽  
Joseph E Italiano ◽  
Kelly Johnson
Keyword(s):  
Estrogen Receptor ◽  
Tumor Cells ◽  
Platelet Activation ◽  
Platelet Function ◽  
Critical Role ◽  
Metastatic Spread ◽  
Angiogenic Potential ◽  
Angiogenic Proteins ◽  
The Impact ◽  
Mcf 7

Abstract Platelets, which are mainly known for their role in hemostasis, are now known to play a crucial role in metastasis. Metastatic disease is the cause of roughly 90% of all cancer-related deaths and understanding the mechanisms leading to dissemination of tumor cells to distant sites remains one of the main challenges of cancer research. Tamoxifen is a selective estrogen receptor modulator that is widely used for the treatment and prevention of breast cancer. Interestingly, tamoxifen has demonstrated anti-cancer efficacy in estrogen negative breast cancers suggesting that this drug has additional mechanisms of action. Previously tamoxifen and its metabolites have been shown directly impact platelet function; however, the reported effects have been varied (Vitseva et al,. 2005, Nayak et al., 2011). Because platelets are critical for metastatic spread, we posited that tamoxifen may exert anti-tumor effects by directly altering platelet function. To explore this, we first examined the effect of tamoxifen on platelet activation. P-selectin expression was determined by flow cytometry for platelets pretreated with or without tamoxifen and then activated with ADP or MCF-7 cells. Both ADP and exposure to MCF-7 cells resulted in platelet activation and treatment with tamoxifen lead to a partial inhibition of activation. Platelets are a reservoir for angiogenic proteins that are secreted in a differentially regulated process. We have previously shown that we can manipulate the angiogenic potential of the platelet releasate through physiological (platelet agonists) and pathological activation (MCF-7 tumor cells) (Battinelli et al., 2011). We hypothesized that tamoxifen may impact malignancy by altering the release of angiogenesis regulatory proteins from platelets. To explore the impact of tamoxifen on the angiogenic potential of platelets, we analyzed the releasates from platelets exposed to tamoxifen alone or activated with ADP or MCF-7 cells in conjunction with tamoxifen. Our data reveals that platelets exposed to tamoxifen release significantly decreased amounts of VEGF in response to activation by either the platelet agonist ADP or interaction with tumor cells (MCF-7 cells). Next, in vitro angiogenesis assays were performed to further examine the effect of tamoxifen on the angiogenic potential of platelets. We observed dramatically diminished capillary tube branch point formation and decreased migration in endothelial cell cultures exposed to releasates generated from tamoxifen treated platelets compared to control releasates, demonstrating that tamoxifen inhibits the ability of activated platelets to promote angiogenesis. Platelets play a critical role in aiding the intravasation and extravasation of tumor cells in the circulation and therefore we postulated that tamoxifen could alter the ability of platelets to aid tumor cells in crossing the vascular endothelium. We performed transendothelial migration assays in which platelets were pretreated with tamoxifen or vehicle control, washed and mixed with MCF-7 tumor cells in endothelialized transwells. Platelets significantly increased the number of tumor cells that crossed the endothelial barrier; however this increase was lost when platelets were pretreated with tamoxifen. Overall our results demonstrate that tamoxifen directly alters platelet function, leading to decreased angiogenic and metastatic potential. These studies highlight a previously unknown mechanism of action for tamoxifen and may shed light on the efficacy of tamoxifen in estrogen-receptor negative cancers. Furthermore our work stresses the importance of crosstalk between platelets and cells within the tumor microenvironment for successful angiogenesis and metastatic spread and, ultimately, support the idea of utilizing targeted platelet therapies to inhibit the platelet’s role in malignancy. Disclosures No relevant conflicts of interest to declare.

scholarly journals Specific immune modulation of experimental colitis drives enteric alpha-synuclein accumulation and triggers age-related Parkinson-like brain pathology

2020 ◽  
Author(s):  
Stefan Grathwohl ◽  
Emmanuel Quansah ◽  
Nazia Maroof ◽  
Jennifer A Steiner ◽  
Liz Spycher ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Immune Modulation ◽  
Intestinal Inflammation ◽  
Critical Role ◽  
Experimental Colitis ◽  
Alpha Synuclein ◽  
Submucosal Plexus ◽  
Wild Type ◽  
Genetic Ablation ◽  
Dss Colitis

Abstract Background : Intraneuronal accumulation of a-synuclein (αSyn) is key in Parkinson’s disease (PD) pathogenesis. The pathogenic process is suggested to begin in the enteric nervous system decades before diagnosis of PD and then propagate into the brain. The triggers for these events are unclear but, in some patients, colitis might play a critical role. Methods : We administered lipopolysaccharide (LPS) or dextran sulfate sodium (DSS) to assess the effect of different types of experimental colitis on αSyn accumulation in the gut of αSyn transgenic and wild type mice and quantified local gene expression by RT-PCR and level of αSyn accumulation by immunofluorescence imaging. Immune modulation during the DSS colitis paradigm in the αSyn transgenic mice included genetic ablation of Cx3cr1 or treatment with recombinant IL-10. To determine long-term effects of experimental colitis, we induced DSS colitis in young αSyn transgenic mice and aged them under normal conditions up to nine or 21 months before analyzing their brains by immunohistochemistry. In vivo experiments were performed in randomized cohorts. Blinded experimenters performed image analysis and statistical analysis depended on data type (i.e., Student’s t-test, ANOVA, mixed-effects model). Results : We demonstrate that mild sustained or one strong insult of experimental DSS colitis triggers αSyn accumulation in the submucosal plexus of wild type and αSyn transgenic mice, while short-term mild DSS experimental colitis or inflammation induced by LPS does not have such an effect. Lack of macrophage-related Cx3cr1-signalling during DSS colitis increases accumulation of αSyn in the colonic submucosal plexus of αSyn transgenic mice while systemic treatment with immune-dampening IL-10 ameliorates this phenomenon. Additionally, DSS colitis-induced αSyn accumulation in young αSyn transgenic mice persists for months and is exacerbated by lack of Cx3cr1-signaling. Remarkably, experimental colitis at three months of age exacerbates the accumulation of aggregated phospho-Serine 129 αSyn in the midbrain (including the substantia nigra), in 21- but not 9-month-old αSyn transgenic mice. This increase in midbrain αSyn accumulation is accompanied by the loss of tyrosine hydroxylase-immunoreactive nigral neurons. Conclusions : Our data suggest that specific types of intestinal inflammation, mediated by monocyte/macrophage signaling, could play a critical role in the initiation and progression of PD.

scholarly journals M6PR-Specific Targeting of Lysosomal Heparanase Regulates Platelet Hemostatic Function in Mice

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1059-1059
Author(s):  
Nathan Eaton ◽  
Caleb Drew ◽  
Theresa A. Dlugi ◽  
Karin M. Hoffmeister ◽  
Hervé Falet
Keyword(s):  
Platelet Function ◽  
Conflicts Of Interest ◽  
Blood Platelets ◽  
Critical Role ◽  
Fluorescent Microscopy ◽  
Type I ◽  
Dense Granules ◽  
Specific Targeting

Besides α-granules and dense granules, which play critical roles in and beyond hemostasis, circulating blood platelets and their precursor cells megakaryocytes contain lysosomes, the contents of which are also secreted during platelet activation. In their delivery to the lysosome, acid hydrolases bearing phosphomannosyl residues are trafficked from the trans-Golgi network to the acidic late-endosomal compartment via the mannose 6-phosphate receptor (M6PR) pathway. To determine the role of M6PR-specific targeting of lysosomal enzymes in platelet function, platelet parameters were investigated in M6pr-/- mice lacking the 46-kDa M6PR, the physiological role of which is unclear. M6pr-/- mice had normal platelet count but displayed an increased number of distinct proplatelet-like cells compared to control mice, as determined by immunofluorescent microscopy. Moreover, transmission electron microscopy revealed the presence of abnormal membrane tubulations, elongated and electron-dense granules, and large vacuole-like structures within resting M6pr-/- platelets. M6pr-/- platelets expressed normally major glycoproteins on their surface and von Willebrand factor and fibrinogen in their α-granules. M6pr-/- mice were hyper-thrombotic, as assessed by tail bleeding time, and M6pr-/- platelets adhered to type I collagen with a significantly greater propensity than control platelets under arterial shear in in vitro flow experiments. Heparanase, an endo-β-glucuronidase that cleaves extracellular matrix heparan sulfate proteoglycans, is the most abundant lysosomal enzyme in platelets. Thus, its contribution to the phenotype of M6pr-/- mice was investigated further. Heparanase expression was decreased in the bone marrow megakaryocytes and blood platelets of M6pr-/- mice and increased in M6pr-/- plasma, as evidenced by immunoblot and fluorescent microscopy analysis, consistent with its mistargeting in the absence of M6PR. Interestingly, pharmacological inhibition of heparanase with OGT 2115 normalized the adhesion of M6pr-/- platelets to collagen in vitro, indicating that increased plasma heparanase contributes to the thrombotic phenotype of M6pr-/- mice. Taken together, the data suggest that the M6PR-specific targeting of lysosomal heparanase plays a critical role in platelet function, thereby regulating hemostasis. Disclosures No relevant conflicts of interest to declare.

Incomplete Platelet Dense Granule Formation in Normal Neonates.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3210-3210
Author(s):  
Walter H. Kahr ◽  
Shoma Baidya ◽  
Animitra Das ◽  
Ayca Toprak ◽  
Hilary Christensen ◽  
...  
Keyword(s):  
Cord Blood ◽  
Thin Section ◽  
Platelet Activation ◽  
Platelet Function ◽  
Blood Platelets ◽  
Coagulation Factor ◽  
Dense Granule ◽  
Older Children ◽  
Granule Formation ◽  
Dense Granules

Abstract Platelets are important in maintaining hemostasis in newborns, where bleeding can arise from abnormal platelet function and/or thrombocytopenia. It is well established that plasma coagulation factor concentrations are lower in neonates compared to children and adults, but less is known about the development and function of neonatal platelets. It has been postulated that platelets from neonates, and to a greater extend from premature neonates, are dysfunctional due to low dense granule counts (Blood2006;108:331a), however, other studies have shown normal neonate platelet function. Our previous studies indicated a slightly decreased number of dense granules per platelet in neonates (Blood2005;106:4159–4156). We have now extended these studies to a larger cohort of 19 normal neonatal cord blood samples (gestational age 37.5–40 weeks) from planned Caesarean sections, which were analyzed under optimal sample handling conditions and compared to platelets from 10 children (age 8–10 years). 50 platelets from each subject were evaluated for dense granule content utilizing whole mount and thin section electron microscopy (EM) for the quantification of dense granules (detected via their electron-dense calcium content) and ultrastructural assessment. A subset of samples was tested via flow cytometry for P-selectin expression as a measure of platelet activation, and platelet structural integrity was also assessed using thin section EM. Our data revealed that platelets in neonatal cord blood had a mean dense granule count of 2.3 (SD=2.2) per platelet, compared to 4.4 dense granules per platelet (SD=2.7) in blood from older children; t-test comparisons showed the difference between these groups to be highly significant (P<0.001). Interestingly, 22% of cord blood platelets contained no measurable dense granules, whereas only 3% of platelets from older children where devoid of dense granules. We suspected that the mean dense granule counts of <1 per platelet in neonatal cord blood reported by others may have arisen due to high levels of platelet activation during sample acquisition or handling. In our samples platelet activation as measured by P-selectin expression was similar in both populations and did not exceed 7.5%, and platelet morphology as assessed by thin section EM was also comparable. Our studies confirm that neonatal cord blood platelets contain fewer recognizable dense granules than those found in older children. Two possible explanations for this observation are: normal numbers of dense granules are present in neonatal platelets, but a subset cannot be detected via EM owing to insufficient calcium uptake; there are fewer dense granules in neonatal platelets owing to peculiarities in the development of megakaryocytes, where recent studies have suggested that dense granules originate by an active transport mechanism and move into proplatelets. These possibilities point to the usefulness of studying fetal and neonatal megakaryopoiesis.

scholarly journals Alteration of platelet function in dogs mediated by interleukin-6

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 398-403 ◽  
Author(s):  
J Peng ◽  
P Friese ◽  
JN George ◽  
GL Dale ◽  
SA Burstein
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Activation ◽  
Platelet Function ◽  
Interleukin 6 ◽  
Platelet Activating Factor ◽  
Platelet Surface ◽  
Thrombin Activation ◽  
Dog Blood ◽  
And Control ◽  
Twofold Decrease

Abstract To determine if interleukin-6 (IL-6) administration influences platelet function, platelet activation was analyzed sequentially in IL-6-treated (80 micrograms/kg/d) and control dogs. Platelet activation was determined in whole blood by flow cytometry by quantitating the binding of a monoclonal antibody to platelet surface P-selectin after stimulation with graded doses of thrombin. Administration of IL-6 resulted in a twofold decrease in the thrombin concentration required for induction of half-maximal P-selectin expression (ED50) compared with control animals. The ED50 returned to normal after cessation of IL- 6 administration. As measured by P-selectin expression, enhanced responsiveness to the strong agonist platelet activating factor (PAF) was also observed in the IL-6-treated dogs. IL-6 had no effect on the susceptibility of platelets to thrombin activation when incubated with anticoagulated dog blood. The data show that, in addition to augmenting the platelet count in normal dogs, IL-6 enhances the sensitivity of platelets to activation in response to thrombin and PAF.

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

1987 ◽  
Vol 57 (01) ◽  
pp. 062-066 ◽  
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.

Interleukin-6 and Malondialdehyde in Women with Preterm Birth

2019 ◽  
Vol 15 (2) ◽  
pp. 207-212
Author(s):  
Vinita Verma ◽  
Hina Oza ◽  
Riddhi Thaker ◽  
Sunil Kumar
Keyword(s):  
Oxidative Stress ◽  
Preterm Birth ◽  
Interleukin 6 ◽  
Critical Role ◽  
Serum Levels ◽  
Maternal Serum ◽  
Full Term ◽  
Mortality And Morbidity ◽  
Term Birth ◽  
Weak Negative Correlation

Background: Preterm Birth (PTB) is one of the main causes of neonatal death and infant mortality and morbidity. The pro-inflammatory cytokine interleukin-6 (IL-6) is a major proinflammatory mediator of the host response to infection and malondialdehyde (MDA) is a marker of oxidative stress. Objective : To evaluate potential associations between IL-6 and MDA levels in women with preterm birth. Method: A total of 150 women (66 with full-term and 84 with PTB) were enrolled in this case-control study. Predesigned performas were filled through questionnaire interviews to collect data on personal, demographic, occupational, lifestyle and reproductive history. Blood samples were collected within 36 hours of delivery. Serum concentrations of IL-6 and MDA were determined in mothers with full-term and preterm birth. Results: The mean age was marginally higher; whereas BMI was slightly lower in cases (PTB) as compared to controls (full-term) subjects. Serum IL-6 and MDA levels were significantly higher in subjects with PTB than full-term birth. The data were further analyzed with respect to underweight, normal and overweight/obese BMI. In all the BMI categories, the levels of IL-6 and MDA were higher in PTB cases. Among the PTB categories, the levels of IL-6 and MDA were highest in moderate to late preterm birth. A significant positive correlation was found between IL-6 and MDA levels. There was a weak negative correlation between either IL-6 or MDA and the number of gestational weeks. Conclusion : Elevated maternal serum levels of Interleukin-6 and Malondialdehyde in preterm as compared to full-term birth might suggest that inflammation and oxidative stress play a critical role in PTB.

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