Eicosanoid production from porcine neutrophils and platelets: differential production with various agonists

1997 ◽  
Vol 272 (6) ◽  
pp. C1821-C1828 ◽  
Author(s):  
G. L. Stahl ◽  
D. S. Morse ◽  
S. L. Martin
Keyword(s):  
Human Disease ◽  
Cytochalasin B ◽  
Flow Cytometric Analysis ◽  
Platelet Activating Factor ◽  
Lipid Mediators ◽  
Polymorphonuclear Neutrophils ◽  
Lipoxin A4 ◽  
Flow Cytometric ◽  
A 23187 ◽  
Paf Receptor

Polymorphonuclear neutrophils (PMN) and platelets interact to produce both inflammatory and anti-inflammatory lipid mediators during human disease. Because swine models of human disease are used, it is important to understand the mechanisms involved in the formation of lipid mediators from porcine PMN-platelet interactions. In the present study, we investigated the mechanism of thromboxane (Tx) A2 and lipoxin A4 (LXA4) formation from porcine PMN and platelets, respectively. PMN (10(7)/ml) and platelet (30 x 10(7)/ml) suspensions stimulated with porcine C5a (pC5a), but not recombinant human C5a (rhC5a), significantly enhanced TxB2 formation. After cytochalasin B treatment, pC5a or rhC5a significantly and equally enhanced TxB2 formation from PMN-platelet suspensions. A-23187-induced TxB2 formation from platelets was not significantly augmented by the presence of PMN in these suspensions. A-23187 induced significant LXA4 production from porcine PMN that was not augmented by addition of platelets. Flow cytometric analysis of PMN-platelet suspensions revealed activated platelets adherent to PMN following pC5a stimulation. CV-6209, a platelet-activating factor (PAF) receptor antagonist, dose dependently prevented pC5a-induced platelet adherence to PMN and TxB2 formation. These data demonstrate that 1) porcine PMN alone can biosynthesize LXA4 without the assistance of platelets, which is in sharp contrast to human PMN-platelet interactions, and 2) in the absence of cytochalasin B, pC5a stimulates PAF biosynthesis from porcine PMN, resulting in TxB2 formation from platelets.

Phospholipase A2 activation in human neutrophils requires influx of extracellular Ca2+ and leukotriene B4

1995 ◽  
Vol 268 (1) ◽  
pp. C138-C146 ◽  
Author(s):  
S. Reddy ◽  
R. Bose ◽  
G. H. Rao ◽  
M. Murthy
Keyword(s):  
Ethylene Glycol ◽  
Phospholipase A2 ◽  
Platelet Activating Factor ◽  
Leukotriene B4 ◽  
Lipid Mediators ◽  
Oxidation Products ◽  
Human Neutrophils ◽  
Tetraacetic Acid ◽  
A 23187 ◽  
Transient Elevation

We have demonstrated that phospolipase A2 (PLA2) activation in human neutrophils requires both the influx of extracellular Ca2+ and leukotriene B4 (LTB4). Surprisingly, the eicosanoids (LTB4 and its omega-oxidation products) formed were quantitatively very similar in both thapsigargin (Thap)- and A-23187-stimulated neutrophils. In contrast, Thap had very little effect on the activation of PLA2 when 5-lipoxygenase (5-LO) was blocked by BW755C or MK-886, whereas A-23187 caused a substantial activation. The lack of PLA2 activation in Thap-stimulated neutrophils results from the inhibition of LTB4 formation in the presence of 5-LO inhibitors. It appears that A-23187 activates both LTB4-dependent and -independent PLA2, whereas Thap activates LTB4-dependent PLA2. Experiments with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid demonstrated that activation of Thap-sensitive PLA2 and 5-LO requires the influx of Ca2+. Neither the transient elevation of cytosolic Ca2+ from intracellular stores nor the sustained Ca2+ influx alone without LTB4 appears sufficient to cause the activation of LTB4-dependent PLA2. We suggest that the activation of LTB4-dependent PLA2 involves 1) a sustained elevation of cytosolic Ca2+ coupled to the influx of extracellular Ca2+ and 2) a coupling between LTB4 and its receptor. We conclude that LTB4-dependent PLA2 plays an important role in the poststimulatory formation of lipid mediators such as prostaglandins, leukotrienes, and platelet-activating factor.

scholarly journals PAF-acetylhydrolase expressed during megakaryocyte differentiation inactivates PAF-like lipids

Blood ◽  
2009 ◽  
Vol 113 (26) ◽  
pp. 6699-6706 ◽  
Author(s):  
Jason M. Foulks ◽  
Gopal K. Marathe ◽  
Noemi Michetti ◽  
Diana M. Stafforini ◽  
Guy A. Zimmerman ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Platelet Activating Factor ◽  
Lipid Mediators ◽  
Target Cells ◽  
Signaling System ◽  
Human Cd34 ◽  
Paf Acetylhydrolase ◽  
Cd34 Cells ◽  
Paf Receptor ◽  
And Function

Abstract Platelet activating factor (PAF) and PAF-like lipids induce inflammatory responses in target cells. These lipid mediators are inactivated by PAF-acetylhydrolase (PAF-AH). The PAF signaling system affects the growth of hematopoietic CD34+ cells, but roles for PAF-AH in this process are unknown. Here, we investigated PAF-AH function during megakaryopoiesis and found that human CD34+ cells accumulate this enzymatic activity as they differentiate toward megakaryocytes, consistent with the expression of mRNA and protein for the plasma PAF-AH isoform. Inhibition of endogenous PAF-AH activity in differentiated megakaryocytes increased formation of lipid mediators that signaled the PAF receptor (PAFR) in fully differentiated human cells such as neutrophils, as well as megakaryocytes themselves. PAF-AH also controlled megakaryocyte αIIbβ3-dependent adhesion, cell spreading, and mobility that relied on signaling through the PAFR. Together these data suggest that megakaryocytes generate PAF-AH to modulate the accumulation of intracellular phospholipid mediators that may detrimentally affect megakaryocyte development and function.

Association of CXCR2+ granulocytic myeloid derived suppressor cells with the development of cholangiocarcinoma: A possible target for intervention.

2020 ◽  
Vol 38 (4_suppl) ◽  
pp. 565-565
Author(s):  
Nicholas A. Ullman ◽  
Luis I. Ruffolo ◽  
Katherine M. Jackson ◽  
Alexander Chacon ◽  
Rachel Jewell ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Human Disease ◽  
Flow Cytometric Analysis ◽  
Suppressor Cells ◽  
Normal Liver ◽  
Myeloid Derived Suppressor Cells ◽  
Hepatic Tumors ◽  
Liver Malignancy ◽  
Normal Littermate ◽  
Flow Cytometric

565 Background: Cholangiocarcinoma (CCA) is the second most common primary liver malignancy, with increasing incidence. Currently, surgical resection offers the only chance for cure, however the prognosis remains poor in part due to high rates of unresectability, recurrence, and poor response to conventional therapy. Thus, new systemic therapies represent an unmet medical need. Few preclinical models exist for identifying and testing new targeted or immune based therapies. Here we present our findings of the immune infiltrate in human CCA tumor microenvironment (TME) and a spontaneous murine model that faithfully recapitulates human disease. Methods: Histology and immunohistochemistry (IHC) staining was performed on human CCA and adjacent normal liver. Mice with targeted hepatic Kras activation and loss of p53 (KPPC) spontaneously develop CCA. KPPC hepatic tumors and normal livers from littermate controls underwent histological and gene expression studies. Flow cytometric analysis was performed on bone marrow, spleen, peripheral blood, CCA tumors and normal littermate livers. Results: Digital IHC quantification of archival human CCA specimens demonstrated elevated levels of CD15+CXCR2+ granulocytic myeloid derived suppressor cells (G-MDSC) compared to adjacent normal liver (p = < 0.05). In addition, the CXCR2 ligand, CXCL5, was significantly elevated in CCA tumors compared to adjacent normal liver. In KPPC mice, flow cytometric analysis of hepatic tumors showed an abundance of CD45+ leukocytes comprised of immunosuppressive G-MDSC vs normal littermate controls (p = 0.0007) which recapitulates human disease. qRT-PCR demonstrated significantly increased expression of G-csf, Csf1, Cxcl1, Cxcl2, and Cxcl5 (p = < 0.0001) in CCA KPPC tumors compared to normal livers. Accordingly, granulocytes in KPPC mice were elevated in both the bone marrow and blood compared to normal littermate controls. Conclusions: These data suggest CCA co-opts the ELR+ cytokine/CXCR2 axes to mobilize and recruit immunosuppressive G-MDSC to the TME. Targeted therapy against tumor infiltrating neutrophils can be tested in this pre-clinical model to inform clinical translation.

scholarly journals Effect of Gliotoxin on Human Polymorphonuclear Neutrophils

1998 ◽  
Vol 6 (4) ◽  
pp. 168-175 ◽  
Author(s):  
D. T. Shah ◽  
S. Jackman ◽  
J. Engle ◽  
B. Larsen
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Mononuclear Cells ◽  
Biological Effects ◽  
Flow Cytometric Analysis ◽  
Polymorphonuclear Neutrophils ◽  
Symptomatic Infection ◽  
Flow Cytometric ◽  
Functional Aspects ◽  
Dye Reduction ◽  
And Function

Objectives:Candida albicansis known to produce gliotoxin, which has several prominent biological effects, including immunosuppression. interference with host defenses may arise from the effects of this toxin on leukocyte structure and function.Methods:Flow cytometric analysis revealed that polymorphonuclear leukocytes (PMN) were more sensitive to gliotoxin than were mononuclear cells. Structural and various functional aspects of PMN exposed to gliotoxin were studied.Results:Gliotoxin at (1 μg/mL) did not affect the viability but did diminish PMN chemotaxis and reduced their ability to ingest particles. Other functional aberrations included decreased nitroblue tetrazolium dye reduction, decreased superoxide production, and release of lactoferrin suggesting by degranulation. Gliotoxin also affected the ability of PMN to killEscherichia coli.Conclusions:This study suggests a previously unrecognized potential virulence factor ofC. albicansthat could contribute to persistence of yeast colonization or recurrence of symptomatic infection through diminished host resistance.

scholarly journals Regulation of platelet-activating-factor receptors and the desensitization response in polymorphonuclear neutrophils

1992 ◽  
Vol 288 (1) ◽  
pp. 241-248 ◽  
Author(s):  
J T O'Flaherty ◽  
D P Jacobson ◽  
J F Redman
Keyword(s):  
Actinomycin D ◽  
Platelet Activating Factor ◽  
Receptor Expression ◽  
Polymorphonuclear Neutrophils ◽  
Target Cells ◽  
Surface Compound ◽  
Down Regulation ◽  
High Affinity ◽  
Kinase C ◽  
Paf Receptor

Platelet-activating factor (PAF) desensitizes as well as stimulates its various target cells, We find that human polymorphonuclear neutrophils (PMN) exposed to PAF became maximally unresponsive to a second PAF challenge within 15-90 s in assays of Ca2+ mobilization and degranulation. The cells regained full PAF-sensitivity over the ensuing 20-40 min. These effects correlated with changes in PAF receptor availability. PMN treated with PAF, washed in regular buffer and assayed for PAF binding exhibited falls (maximal in 15 s), followed by rises (reaching control levels by 60 min), in the number of high-affinity PAF receptors. However, tracking studies showed that [3H]PAF accumulated on the cell surface for approximately 2 min before being internalized. Regular-buffer washes did not remove this superficial PAF, whereas a washing regimen using excess albumin to adsorb PAF removed 99% of the surface compound. PMN washed by the latter regimen after PAF exposure lost PAF receptors relatively slowly (maximal at approximately 5 min), but the ultimate extent of this loss and the rate at which receptor expression normalized were similar to those of cells washed in regular buffer. Neither cycloheximide nor actinomycin D influenced the course of the receptor changes, but two protein kinase C (PKC) blockers, staurosporine and 1-(5-isoquinolinesulphonyl)piperazine, inhibited the receptor-receptor-depleting actions of PAF. Indeed, a phorbol diester activator of PKC also caused PMN to decrease high-affinity PAF receptor numbers, and the two PKC blockers antagonized this action at concentrations that inhibited PAF-induced PAF receptor losses. We conclude that: (a) PAF induces PMN to down-regulate and then to re-express PAF receptors independently of protein synthesis; (b) these changes are likely to underlie the later stages and reversal of desensitization; (c) the onset (t < or = 2 min) of desensitization, however, precedes receptor down-regulation and must be due to receptor uncoupling from transductional elements; and (d) down-regulation of receptors for PAF appears to be mediated by PKC and/or elements inhibited by PKC blockers.

Hypoxia induces endothelial cells to increase their adherence for neutrophils: role of PAF

1992 ◽  
Vol 263 (3) ◽  
pp. H956-H962 ◽  
Author(s):  
K. A. Milhoan ◽  
T. A. Lane ◽  
C. M. Bloor
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Myocardial Ischemia ◽  
Platelet Activating Factor ◽  
Conditioned Media ◽  
Polymorphonuclear Neutrophils ◽  
Cell Monolayers ◽  
Paf Receptor ◽  
Paf Receptor Antagonist

We investigated the interactions of polymorphonuclear neutrophils (PMN) and endothelial cells in myocardial ischemia using a hypoxia model. We exposed porcine aortic (PAEC) and porcine coronary microvessel (PCMEC) endothelial cells to 2% O2 for 2 h (PO2 = 53 mmHg) and measured the adherence of unstimulated neutrophils (PMN) to both control and hypoxia-conditioned endothelial cell monolayers. Hypoxia conditioning increased PMN adherence to PAEC and PCMEC by 51 and 101%, respectively, above control levels. The increase in PMN adhesion to PAEC was associated with a threefold increase in endothelial cell-associated platelet-activating factor (PAF) compared with control PAEC. The conditioned media from PAEC exposed to hypoxia also contained sixfold more PAF than control conditioned media, and it activated PMN to become adherent to untreated PAEC. The hypoxia-induced PAEC adhesion response was inhibited by preincubating PMN with the specific PAF receptor antagonist, L-659,989. We conclude that PAF is produced by cultured endothelial cells in response to hypoxia and that PAF generation is chiefly responsible for the increased adherence properties of hypoxia-conditioned endothelial cells. This response may play a major role in regulating PMN margination during myocardial ischemia.

scholarly journals Bitis arietans Snake Venom Induces an Inflammatory Response Which Is Partially Dependent on Lipid Mediators

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 594
Author(s):  
Angela Alice Amadeu Megale ◽  
Fernanda Calheta Portaro ◽  
Wilmar Dias Da Silva
Keyword(s):  
Inflammatory Response ◽  
Platelet Activating Factor ◽  
Lipid Mediators ◽  
Mice Model ◽  
Permanent Disability ◽  
Paf Receptor ◽  
Inflammatory Drugs ◽  
Pre Treatment ◽  
Clinical Conditions

Bitis arietans is a snake of medical importance, as it is responsible for more accidents in humans and domestic animals than all other African snakes put together. The accidents are characterized by local and systemic alterations, such as inflammation, cardiovascular and hemostatic disturbances, which can lead victims to death or permanent disability. However, little is known about the envenomation mechanism, especially regarding the inflammatory response, which is related to severe clinical conditions triggered by the venom. Therefore, the aim of the present study was to evaluate the inflammatory response related to the B. arietans envenomation using a peritonitis mice model. By pharmacological interventions and use of mice genetically deficient of the 5-lipoxygenase enzyme (5-LO−/−) or platelet-activating factor (PAF) receptor (PAFR−/− the participation of eicosanoids and PAF in this response was also investigated. The obtained results demonstrated that the venom induces an in vivo inflammatory response, characterized by an early increased vascular permeability, followed by an accumulation of polymorphonuclear (PMN) cells in the peritoneal cavity, accompanied by the production of the eicosanoids LTB4, LTC4, TXB2 and PGE2, as well as the local and systemic production of IL-6 and MCP-1. These inflammatory events were attenuated by the pre-treatment with anti-inflammatory drugs that interfere in lipid mediators’ functions. However, 5-LO−/− mice did not show a reduction of inflammatory response induced by the venom, while PAFR−/− mice showed a reduction in both the PMN leukocytes number and the local and systemic production of IL-6 and MCP-1. This study demonstrated that the Bitis arietans venom contains toxins that trigger an inflammatory process, which is partially dependent on lipid mediators, and may contribute to the envenomation pathology.

Apoptotic Effects of Melittin on 4T1 Breast Cancer Cell Line is associated with Up Regulation of Mfn1 and Drp1 mRNA Expression

2020 ◽  
Vol 20 (7) ◽  
pp. 790-799 ◽  
Author(s):  
Farnaz D. Moghaddam ◽  
Pejman Mortazavi ◽  
Somayeh Hamedi ◽  
Mohammad Nabiuni ◽  
Nasim H. Roodbari
Keyword(s):  
Breast Cancer ◽  
Mrna Expression ◽  
Hemolytic Activity ◽  
Breast Cancer Cells ◽  
Flow Cytometric Analysis ◽  
Control Group ◽  
Flow Cytometric ◽  
4T1 Cells ◽  
4T1 Breast Cancer ◽  
Apoptotic Effects

Background and Purpose: Melittin, as the main ingredient of honeybee venom, that has shown anticancer properties. The present study aimed at investigating the cytotoxic impacts of melittin on 4T1 breast cancer cells. Methods: Hemolytic activity of different concentrations (0.125, 0.25, 0.5, 1, 2, 4, 8μg/ml) of melittin was assayed and then cytotoxicity of selected concentrations of melittin (2, 4, 8, 16, 32, and 64μg/ml), 2 and 4μg/ml of cisplatin and 0.513, 0.295 and 0.123μg/ml of doxorubicin was evaluated on 4T1 cells using MTT assay. We used Morphological evaluation and flow cytometric analysis was used. Real time PCR was also used to determine mRNA expression of Mfn1 and Drp1 genes. Results: All compounds showed anti-proliferative effects on the tumor cell line with different potencies. Melittin had higher cytotoxicity against 4T1 breast cancer cells (IC50= 32μg/ml-72h) and higher hemolytic activity (HD50= 1μg/ml), as compared to cisplatin and doxorubicin. Mellitin at 16 and 32μg/ml showed apoptotic effects on 4T1 cells according to the flow cytometric analysis. The Real time PCR analysis of Drp1 and Mfn1 expression in cells treated with 16μg/ml of melittin revealed an up-regulation in Drp1 and Mfn1 genes mRNA expression in comparison with control group. Treatment with 32μg/ml of melittin was also associated with a rise in mRNA expression of Drp1 and Mfn1 as compared to the control group. Conclusion: The results of this study showed that melittin has anticancer effects on 4T1 cell lines in a dose and time dependent manner and can be a good candidate for further research on breast cancer treatment.

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