Aspirin inhibits the production of proangiogenic 15(S)-HETE by platelet cyclooxygenase-1

Case Report: single low-dose of denosumab as a trigger of MRONJ development in a patient with osteoporosis after bisphosphonate therapy

Both denosumab (DMB) and bisphosphonates (BPs), antiresorptive drugs (ARDs) used for the treatment of osteoporosis and oncological disorders, are known for their potential to cause medication-related osteonecrosis of the jaws (MRONJ). Besides ARDs, statins were recently associated with MRONJ development, especially in patients taking higher doses of statins for a longer period of time. Here, we report a case of a female patient with osteoporosis using statins and treated with alendronate for 3 years who rapidly developed MRONJ stage III after only a single low dose of DMB. After partial maxillectomy complete healing was observed without any recurrence. We performed a literature review of cases with MRONJ triggered by a single low dose of DMB, with or without previous application of other ARDs. Only six similar cases of patients who developed MRONJ after a single low dose of DMB following previous BP therapy have been reported so far. Besides these, literature reports one patient who developed MRONJ after a single dose of DMB following romosozumab treatment and five cases developing MRONJ after a single dose of DMB even without any previous ARD treatment. We suggest that before DMB therapy is initiated, all factors predisposing to MRONJ development should be considered.

Platelet-Rich Plasma in Young and Elderly Humans Exhibits a Different Proteomic Profile

As people age, their ability to resist injury and repair damage decreases significantly. Platelet-rich plasma (PRP) has demonstrated diverse therapeutic effects on tissue repair. However, the inconsistency of patient outcomes poses a challenge to the practical application of PRP in clinical practice. Furthermore, a comprehensive understanding of the specific impact of aging on PRP requires a systematic investigation. We derived PRP from 6 young volunteers and 6 elderly volunteers, respectively. Subsequently, 95% of high-abundance proteins were removed, followed by mass spectrometry analysis. Data are available via ProteomeXchange with the identifier PXD050061. We detected a total of 739 proteins and selected 311 proteins that showed significant differences, including 76 upregulated proteins in the young group and 235 upregulated proteins in the elderly group. Functional annotation and enrichment analysis unveiled upregulation of proteins associated with cell apoptosis, angiogenesis, and complement and coagulation cascades in the elderly. Conversely, IGF1 was found to be upregulated in the young group, potentially serving as the central source of enhanced cell proliferation ability. Our investigation not only provides insights into standardizing PRP preparation but also offers novel strategies for augmenting the functionality of aging cells or tissues.

Unfractionated heparin reverses aspirin inhibition of platelets during coronary artery bypass graft surgery

Unfractionated heparin (UFH) is an effective antithrombotic during surgery but has known adverse effects, in particular on platelets. A marked increase in platelet responsiveness has previously been observed in patients within minutes of receiving UFH, despite adequate inhibition by aspirin prior to heparin. We studied this phenomenon in patients undergoing cardiac artery bypass grafting (n = 17) to determine whether the effects of heparin were systemic or platelet-specific. All patients' platelets were fully inhibited by aspirin prior to surgery, but within 3 min of receiving heparin spontaneous aggregation and responses to arachidonic acid (AA) and ADP increased significantly (p ≥ 0.0002), and activated platelets were found in the circulation. While there was no rise in thromboxane in the plasma following heparin, levels of the major platelet 12-lipoxygenase product, 12-HETE, rose significantly. Mixing experiments demonstrated that the changes caused by heparin resided primarily in the platelets, while addition of AA pathway inhibitors, and analysis of oxylipins provided evidence that, following heparin, aggregating platelets regained their ability to synthesise thromboxane. These findings highlight potentially unrecognised pro-thrombotic and pro-inflammatory changes during CABG surgery, and provide further evidence of adverse effects associated with UFH.

The study of platelet aggregation using a microtiter plate reader ‒ methodological considerations

Optical aggregometry by 96-well plate assay, the microplate method, is a fast, efficient, and readily available method for measuring the pharmacological effects of antiplatelet drugs. Even though recent years have witnessed growing interest in adopting the microplate method for widespread use, it remains in the shadow of the standard light transmission aggregometry (LTA). Regardless of the method used, the results of platelet aggregation depend on a variety of factors and often vary among laboratories worldwide. While several methodological papers have examined the microplate method, no standards have been established, most likely because the approach is not used as a diagnostic tool. Currently, the microplate method is recommended by researchers to be used in conjunction with LTA or as an adjunct to LTA. This raises the question of whether an optimal protocol exists for microplate aggregometry, and what are the key considerations in a good experimental protocol for obtaining reliable results? This article attempts to address these questions by summarizing the knowledge accumulated in this field over the last three decades.

The Potential Preventive and Therapeutic Roles of NSAIDs in Prostate Cancer

Prostate cancer (PC) is the second most common type of cancer and the leading cause of death among men worldwide. Preventing the progression of cancer after treatments such as radical prostatectomy, radiation therapy, and hormone therapy is a major concern faced by prostate cancer patients. Inflammation, which can be caused by various factors such as infections, the microbiome, obesity and a high-fat diet, is considered to be the main cause of PC. Inflammatory cells are believed to play a crucial role in tumor progression. Therefore, nonsteroidal anti-inflammatory drugs along with their effects on the treatment of inflammation-related diseases, can prevent cancer and its progression by suppressing various inflammatory pathways. Recent evidence shows that nonsteroidal anti-inflammatory drugs are effective in the prevention and treatment of prostate cancer. In this review, we discuss the different pathways through which these drugs exert their potential preventive and therapeutic effects on prostate cancer.

Bioactive lipid regulation of platelet function, hemostasis, and thrombosis

Platelets are small, anucleate cells in the blood that play a crucial role in the hemostatic response but are also implicated in the pathophysiology of cardiovascular disease. It is widely appreciated that polyunsaturated fatty acids (PUFAs) play an integral role in the function and regulation of platelets. PUFAs are substrates for oxygenase enzymes cyclooxygenase-1 (COX-1), 5-lipoxygenase (5-LOX), 12-lipoxygenase (12-LOX) and 15-lipoxygenase (15-LOX). These enzymes generate oxidized lipids (oxylipins) that exhibit either pro- or anti-thrombotic effects. Although the effects of certain oxylipins, such as thromboxanes and prostaglandins, have been studied for decades, only one oxylipin has been therapeutically targeted to treat cardiovascular disease. In addition to the well-known oxylipins, newer oxylipins that demonstrate activity in the platelet have been discovered, further highlighting the expansive list of bioactive lipids that can be used to develop novel therapeutics. This review outlines the known oxylipins, their activity in the platelet, and current therapeutics that target oxylipin signaling.

Fatty acids negatively regulate platelet function through formation of noncanonical 15-lipoxygenase-derived eicosanoids

The antiplatelet effect of polyunsaturated fatty acids is primarily attributed to its metabolism to bioactive metabolites by oxygenases, such as lipoxygenases (LOX). Platelets have demonstrated the ability to generate 15-LOX-derived metabolites (15-oxylipins); however, whether 15-LOX is in the platelet or is required for the formation of 15-oxylipins remains unclear. This study seeks to elucidate whether 15-LOX is required for the formation of 15-oxylipins in the platelet and determine their mechanistic effects on platelet reactivity. In this study, 15-HETrE, 15-HETE, and 15-HEPE attenuated collagen-induced platelet aggregation, and 15-HETrE inhibited platelet aggregation induced by different agonists. The observed anti-aggregatory effect was due to the inhibition of intracellular signaling including αIIbβ3 and protein kinase C activities, calcium mobilization, and granule secretion. While 15-HETrE inhibited platelets partially through activation of peroxisome proliferator-activated receptor β (PPARβ), 15-HETE also inhibited platelets partially through activation of PPARα. 15-HETrE, 15-HETE, or 15-HEPE inhibited 12-LOX in vitro, with arachidonic acid as the substrate. Additionally, a 15-oxylipin-dependent attenuation of 12-HETE level was observed in platelets following ex vivo treatment with 15-HETrE, 15-HETE, or 15-HEPE. Platelets treated with DGLA formed 15-HETrE and collagen-induced platelet aggregation was attenuated only in the presence of ML355 or aspirin, but not in the presence of 15-LOX-1 or 15-LOX-2 inhibitors. Expression of 15-LOX-1, but not 15-LOX-2, was decreased in leukocyte-depleted platelets compared to non-depleted platelets. Taken together, these findings suggest that 15-oxylipins regulate platelet reactivity; however, platelet expression of 15-LOX-1 is low, suggesting that 15-oxylipins may be formed in the platelet through a 15-LOX-independent pathway.

Pharmacological Utility of PPAR Modulation for Angiogenesis in Cardiovascular Disease

Peroxisome proliferator activated receptors, including PPARα, PPARβ/δ, and PPARγ, are ligand-activated transcription factors belonging to the nuclear receptor superfamily. They play important roles in glucose and lipid metabolism and are also supposed to reduce inflammation and atherosclerosis. All PPARs are involved in angiogenesis, a process critically involved in cardiovascular pathology. Synthetic specific agonists exist for all PPARs. PPARα agonists (fibrates) are used to treat dyslipidemia by decreasing triglyceride and increasing high-density lipoprotein (HDL) levels. PPARγ agonists (thiazolidinediones) are used to treat Type 2 diabetes mellitus by improving insulin sensitivity. PPARα/γ (dual) agonists are supposed to treat both pathological conditions at once. In contrast, PPARβ/δ agonists are not in clinical use. Although activators of PPARs were initially considered to have favorable effects on the risk factors for cardiovascular disease, their cardiovascular safety is controversial. Here, we discuss the implications of PPARs in vascular biology regarding cardiac pathology and focus on the outcomes of clinical studies evaluating their benefits in cardiovascular diseases.

Inhibitory effect of aspirin on inflammation-induced lung metastasis of cancer cells associated with neutrophil infiltration

PURPOSE

Systematic inflammation has been reported to contribute to cancer progression through various mechanisms; however, the exact mechanism is still the subject of research. In this study, we evaluated the influence of systematic inflammation on lung metastasis, using a murine abdominal sepsis model, and assessed its relationship with pneumonia after curative esophagectomy in patients with esophageal cancer.

METHODS

We used a murine abdominal sepsis model given highly metastatic osteosarcoma, to reveal the mechanism of systematic inflammation and its potential for lung metastasis. The therapeutic effect of aspirin (ASA) in preventing distant metastasis was also investigated. Subsequently, we analyzed, retrospectively, the relationship between pneumonia and lung metastasis after esophagectomy in patients who underwent esophagectomy at Keio University between January, 2007 and October, 2020.

RESULTS

Abdominal sepsis provoked lung injury in the acute phase. ASA inhibited the recruitment of neutrophils triggered by the lung injury, and it also suppressed lung metastasis. Our retrospective study revealed that lung metastasis was more frequent in patients with postoperative pneumonia.

CONCLUSIONS

Postoperative acute lung injury is associated with a higher risk of lung metastasis. ASA may be a potential preoperative treatment for inhibiting lung metastasis by preventing the recruitment of neutrophils.

Aspirin modulates production of pro-inflammatory and pro-resolving mediators in endothelial cells

Endothelial cells synthesize biochemical signals to coordinate a response to insults, resolve inflammation and restore barrier integrity. Vascular cells release a variety of vasoactive bioactive lipid metabolites during the inflammatory response and produce pro-resolving mediators (e.g., Lipoxin A4, LXA4) in cooperation with leukocytes and platelets to bring a halt to inflammation. Aspirin, used in a variety of cardiovascular and pro-thrombotic disorders (e.g., atherosclerosis, angina, preeclampsia), potently inhibits proinflammatory eicosanoid formation. Moreover, aspirin stimulates the synthesis of pro-resolving lipid mediators (SPM), so-called Aspirin-Triggered Lipoxins (ATL). We demonstrate that cytokines stimulated a time- and dose-dependent increase in PGI2 (6-ketoPGF1α) and PGE2 formation that is blocked by aspirin. Eicosanoid production was caused by cytokine-induced expression of cyclooxygenase-2 (COX-2). We also detected increased production of pro-resolving LXA4 in cytokine-stimulated endothelial cells. The R-enantiomer of LXA4, 15-epi-LXA4, was enhanced by aspirin, but only in the presence of cytokine challenge, indicating dependence on COX-2 expression. In contrast to previous reports, we detected arachidonate 5-lipoxygenase (ALOX5) mRNA expression and its cognate protein (5-lipoxygenase, 5-LOX), suggesting that endothelial cells possess the enzymatic machinery necessary to synthesize both pro-inflammatory and pro-resolving lipid mediators independent of added leukocytes or platelets. Finally, we observed that, endothelial cells produced LTB4 in the absence of leukocytes. These results indicate that endothelial cells produce both pro-inflammatory and pro-resolving lipid mediators in the absence of other cell types and aspirin exerts pleiotropic actions influencing both COX and LOX pathways.

Celastrol: A lead compound that inhibits SARS-CoV-2 replication, the activity of viral and human cysteine proteases, and virus-induced IL-6 secretion

The global emergence of coronavirus disease 2019 (COVID-19) has caused substantial human casualties. Clinical manifestations of this disease vary from asymptomatic to lethal, and the symptomatic form can be associated with cytokine storm and hyperinflammation. In face of the urgent demand for effective drugs to treat COVID-19, we have searched for candidate compounds using in silico approach followed by experimental validation. Here we identified celastrol, a pentacyclic triterpene isolated from Tripterygium wilfordii Hook F, as one of the best compounds out of 39 drug candidates. Celastrol reverted the gene expression signature from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected cells and irreversibly inhibited the recombinant forms of the viral and human cysteine proteases involved in virus invasion, such as Mpro (main protease), PLpro (papain-like protease), and recombinant human cathepsin L. Celastrol suppressed SARS-CoV-2 replication in human and monkey cell lines and decreased interleukin-6 (IL-6) secretion in the SARS-CoV-2-infected human cell line. Celastrol acted in a concentration-dependent manner, with undetectable signs of cytotoxicity, and inhibited in vitro replication of the parental and SARS-CoV-2 variant. Therefore, celastrol is a promising lead compound to develop new drug candidates to face COVID-19 due to its ability to suppress SARS-CoV-2 replication and IL-6 production in infected cells.

Aspirin sensitivity of PIK3CA-mutated Colorectal Cancer: potential mechanisms revisited

PIK3CA mutations are amongst the most prevalent somatic mutations in cancer and are associated with resistance to first-line treatment along with low survival rates in a variety of malignancies. There is evidence that patients carrying PIK3CA mutations may benefit from treatment with acetylsalicylic acid, commonly known as aspirin, particularly in the setting of colorectal cancer. In this regard, it has been clarified that Class IA Phosphatidylinositol 3-kinases (PI3K), whose catalytic subunit p110α is encoded by the PIK3CA gene, are involved in signal transduction that regulates cell cycle, cell growth, and metabolism and, if disturbed, induces carcinogenic effects. Although PI3K is associated with pro-inflammatory cyclooxygenase-2 (COX-2) expression and signaling, and COX-2 is among the best-studied targets of aspirin, the mechanisms behind this clinically relevant phenomenon are still unclear. Indeed, there is further evidence that the protective, anti-carcinogenic effect of aspirin in this setting may be mediated in a COX-independent manner. However, until now the understanding of aspirin's prostaglandin-independent mode of action is poor. This review will provide an overview of the current literature on this topic and aims to analyze possible mechanisms and targets behind the aspirin sensitivity of PIK3CA-mutated cancers.

Platelet-Derived miR-126-3p Directly Targets AKT2 and Exerts Anti-Tumor Effects in Breast Cancer Cells: Further Insights in Platelet-Cancer Interplay

Among the surrounding cells influencing tumor biology, platelets are recognized as novel players as they release microvesicles (MVs) that, once delivered to cancer cells, modulate signaling pathways related to cell growth and dissemination. We have previously shown that physiological delivery of platelet MVs enriched in miR-126 exerted anti-tumor effects in different breast cancer (BC) cell lines. Here, we seek further insight by identifying AKT2 kinase as a novel miR-126-3p direct target, as assessed by bioinformatic analysis and validated by luciferase assay. Both ectopic expression and platelet MV-mediated delivery of miR-126-3p downregulated AKT2 expression, thus suppressing proliferating and invading properties, in either triple negative (BT549 cells) or less aggressive Luminal A (MCF-7 cells) BC subtypes. Accordingly, as shown by bioinformatic analysis, both high miR-126 and low AKT2 levels were associated with favorable long-term prognosis in BC patients. Our results, together with the literature data, indicate that miR-126-3p exerts suppressor activity by specifically targeting components of the PIK3/AKT signaling cascade. Therefore, management of platelet-derived MV production and selective delivery of miR-126-3p to tumor cells may represent a useful tool in multimodal therapeutic approaches in BC patients.

Profiling oxylipins released from human platelets activated through the GPVI collagen receptor

In addition to haemostasis, platelets are involved in pathological processes, often driven by material released upon activation. Interaction between collagen and glycoprotein VI (GPVI) is a primary platelet stimulus that liberates arachidonic acid and linoleic acid from membrane phospholipids. These are oxidised by cyclooxygenase-1 (COX-1) and 12-lipoxygenase (12-LOX) to eicosanoids and other oxylipins with various biological properties. Using liquid chromatography-tandem mass spectrometry we found that GPVI-stimulated platelets released significant levels of ten oxylipins; the well documented TxA2 and 12-HETE, PGD₂ and PGE_2, as well as 8-, 9-, 11-, and 15-HETE, 9- and 13-HODE.¹ Levels of oxylipins released from washed platelets mirrored those from platelets stimulated in the presence of plasma, indicating generation from intracellular, rather than exogenous AA/LA. Inhibition of COX-1 with aspirin, as expected, completely abolished production of TxA₂ and PGD/E₂, but also significantly inhibited the release of 11-HETE (89 ± 3%) and 9-HODE (74 ± 6%), and reduced 15-HETE and 13-HODE by ∼33 %. Inhibition of 12-LOX by either esculetin or ML355 inhibited the release of all oxylipins apart from 15-HETE. These findings suggest routes to modify the production of bioactive molecules released by activated platelets.

Aspirin and antiplatelet treatments in cancer

Platelets have been hypothesized to promote certain neoplastic malignancies; however, antiplatelet drugs are still not part of routine pharmacological cancer prevention and treatment protocols. Paracrine interactions between platelets and cancer cells have been implicated in potentiating the dissemination, survival within the circulation, and extravasation of cancer cells at distant sites of metastasis. Signals from platelets have also been suggested to confer epigenetic alterations, including upregulating oncoproteins in circulating tumor cells, and secretion of potent growth factors may play roles in promoting mitogenesis, angiogenesis, and metastatic outgrowth. Thrombocytosis remains a marker of poor prognosis in patients with solid tumors. Experimental data suggest that lowering of platelet count may reduce tumor growth and metastasis. On the basis of the mechanisms by which platelets could contribute to cancer growth and metastasis, it is conceivable that drugs reducing platelet count or platelet activation might attenuate cancer progression and improve outcomes. We will review select pharmacological approaches that inhibit platelets and may affect cancer development and propagation. We begin by presenting an overview of clinical cancer prevention and outcome studies with low-dose aspirin. We then review current nonclinical development of drugs targeted to platelet binding, activation, and count as potential mitigating agents in cancer.

Endothelial cyclooxygenase-1 paradoxically drives local vasoconstriction and atherogenesis despite underpinning prostacyclin generation

Endothelial cyclooxygenase-1-derived prostanoids, including prostacyclin, have clear cardioprotective roles associated with their anti-thrombotic potential but have also been suggested to have paradoxical pathological activities within arteries. To date it has not been possible to test the importance of this because no models have been available that separate vascular cyclooxygenase-1 products from those generated elsewhere. Here, we have used unique endothelial-specific cyclooxygenase-1 knockout mice to show that endothelial cyclooxygenase-1 produces both protective and pathological products. Functionally, however, the overall effect of these was to drive pathological responses in the context of both vasoconstriction in vitro and the development of atherosclerosis and vascular inflammation in vivo. These data provide the first demonstration of a pathological role for the vascular cyclooxygenase-1 pathway, highlighting its potential as a therapeutic target. They also emphasize that, across biology, the role of prostanoids is not always predictable due to unique balances of context, products, and receptors.

Mechanisms of the antiangiogenic effects of aspirin in cancer

Aspirin is an old drug extracted from willow bark and is widely used for the prevention and treatment of cardiovascular diseases. Accumulating evidence has shown that aspirin use may significantly reduce the angiogenesis of cancer; however, the mechanism of the association between angiogenesis and aspirin is complex. Although COX-1 is widely known as a target of aspirin, several studies reveal other antiangiogenic targets of aspirin, such as angiotensin II, glucose transporter 1, heparanase, and matrix metalloproteinase. In addition, some data indicates that aspirin may produce antiangiogenic effects after acting in different cell types, such as endothelial cells, platelets, pericytes, and macrophages. In this review, we concentrate on research regarding the antiangiogenic effects of aspirin in cancer, and we discuss the molecular mechanisms of aspirin and its metabolites. Moreover, we discuss some mechanisms through which aspirin treatment may normalize existing blood vessels, including preventing the disintegration of endothelial adheres junctions and the recruitment of pericytes. We also address the antiangiogenic effects and the underlying mechanisms of aspirin derivatives, which are aimed at improving safety and efficacy.

Regulation of arachidonic acid oxidation and metabolism by lipid electrophiles

Arachidonic acid (AA) is a precursor of enzymatic and non-enzymatic oxidized products such as prostaglandins, thromboxanes, leukotrienes, lipoxins, and isoprostanes. These products may exert signaling or damaging roles during physiological and pathological conditions, some of them being markers of oxidative stress linked to inflammation. Recent data support the concept that cyclooxygenases (COX), lipoxygenases (LOX), and cytochrome P450 (CYP450) followed by cytosolic and microsomal dehydrogenases can convert AA to lipid-derived electrophiles (LDE). Lipid-derived electrophiles are fatty acid derivatives bearing an electron-withdrawing group that can react with nucleophiles at proteins, DNA, and small antioxidant molecules exerting potent signaling properties. This review aims to describe the formation, sources, and electrophilic anti-inflammatory actions of key mammalian LDE.

The multiple effects of aspirin in prostate cancer patients

Aspirin is a commonly used medication with anti-inflammatory and analgesic properties, and it is widely used to reduce the risk of ischaemic heart disease-related events and/or cerebrovascular accidents. However, there is also evidence from epidemiological and interventional studies to suggest that regular aspirin use can reduce the risk of prostate cancer development and progression, and can reduce the risk of disease recurrence following anti-prostate cancer therapy. Aspirin use in African-American men is associated with a reduced incidence of advanced PCa and reduced disease recurrence, and there is evidence from other studies of an association between regular aspirin use and decreased PCa-related mortality. The cyclooxygenase-2 enzyme inhibited by Aspirin and other NSAIDs, and which catalyses prostaglandin synthesis and mediates inflammation, is overexpressed in prostate cancer, therefore inhibition of cyclooxygenase-2 may have direct, and indirect, therapeutic effects. This review explores the evidence suggesting that aspirin use can modify prostate cancer biology and disease characteristics, and explores the potential mechanisms underpinning the observed associations between aspirin use and modification of prostate cancer risk. It also summarises the potential for adjuvant aspirin use to combine with other therapeutic approaches such as radical surgery and radiotherapy.

PRP in wound healing applications

Platelets play a crucial role in hemostasis, tissue regeneration and host defense. Based on these settings, platelet-rich plasma (PRP) and its derivatives are therapeutically used to promote wound healing in several scenarios. This review summarizes the biological mechanisms underlying the most traditional as well as innovative applications of PRP in wound healing. These mechanisms involve the combined action of platelet-derived growth factors and cytokines, together with the role of plasma-derived fibrillar, antioxidant and homeostatic factors. In addition, regenerative treatments with PRP consist of personalized and non-standardized methods. Thus, the quality of PRP varies depending on endogenous factors (e.g., age; gender; concomitant medication; disease-associated systemic factors; nutrition) and exogenous factors (anticoagulants and cellular composition). This review also analyses whether these factors affect the biological mechanisms of PRP in wound healing applications.

Exploratory Genome-Wide Interaction Analysis of Nonsteroidal Anti-inflammatory Drugs and Predicted Gene Expression on Colorectal Cancer Risk

BACKGROUND

Regular use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with lower risk of colorectal cancer. Genome-wide interaction analysis on single variants (G × E) has identified several SNPs that may interact with NSAIDs to confer colorectal cancer risk, but variations in gene expression levels may also modify the effect of NSAID use. Therefore, we tested interactions between NSAID use and predicted gene expression levels in relation to colorectal cancer risk.

METHODS

Genetically predicted gene expressions were tested for interaction with NSAID use on colorectal cancer risk among 19,258 colorectal cancer cases and 18,597 controls from 21 observational studies. A Mixed Score Test for Interactions (MiSTi) approach was used to jointly assess G × E effects which are modeled via fixed interaction effects of the weighted burden within each gene set (burden) and residual G × E effects (variance). A false discovery rate (FDR) at 0.2 was applied to correct for multiple testing.

RESULTS

Among the 4,840 genes tested, genetically predicted expression levels of four genes modified the effect of any NSAID use on colorectal cancer risk, including DPP10 (PG×E = 1.96 × 10-4), KRT16 (PG×E = 2.3 × 10-4), CD14 (PG×E = 9.38 × 10-4), and CYP27A1 (PG×E = 1.44 × 10-3). There was a significant interaction between expression level of RP11-89N17 and regular use of aspirin only on colorectal cancer risk (PG×E = 3.23 × 10-5). No interactions were observed between predicted gene expression and nonaspirin NSAID use at FDR < 0.2.

CONCLUSIONS

By incorporating functional information, we discovered several novel genes that interacted with NSAID use.

IMPACT

These findings provide preliminary support that could help understand the chemopreventive mechanisms of NSAIDs on colorectal cancer.

Analysis of serum polyunsaturated fatty acid metabolites in allergic bronchopulmonary aspergillosis

BACKGROUND

The importance of lipid mediators in allergic diseases has been long recognized, whereas little is known about their role in allergic bronchopulmonary aspergillosis (ABPA). We investigated whether lipid mediators are associated with ABPA.

METHODS

We recruited 12 ABPA patients, 23 asthma patients and 12 healthy control in our study. Serum of 11 ABPA patients were collected before and following treatment. 36 polyunsaturated fatty acid metabolites were measured in serum samples by using liquid chromatography-mass spectrometry. This study was approved by the Ethics Committee of the First Affiliated Hospital of Guangzhou Medical University, with ethics number GYFYY-2016-73.

RESULTS

Levels of arachidonic acid (AA), 15(S)-hydroxyeicosatetraenoic acid (HETE), 12(S)-HETE, 8(S)-HETE, 5(S)-HETE, LTB₄, PGB₂, 12(S)-hydroxyeicosapentaenoic acid (HEPE), 12-hydro-xyheptadecatrienoic acid (HHTrE) were significantly higher in ABPA patients than that in HC groups. Compared with asthma group, ABPA group expressed lower levels of 15(S)-hy-droperoxyeicosatetraenoic acid (HPETE), 5(S)-HPETE, 13(S)-hydroperoxyoctadecadienoic acid (HPODE) and 9(S)-HPODE. In APBA patients, AA level was positively correlated with serumtotal IgE (tIgE). The levels of 12(S)-HPETE, 15(S)-HEPE and 12(S)-HEPE correlated with Asp-ergillus fumigatus specific IgE(A. fumigatus sIgE) positively. Peripheral blood eosinophilia correlated with high levels of 12(S)-HETE and 15(S)-HETE. In addition, the serum levels of15(S)-HETE and 12(S)-HETE in ABPA subjects both declined with the decrease of tIgE, A. fumigatus sIgE and sIgG concentrations after treatment.

CONCLUSIONS

We present data regarding the role of polyunsaturated fatty acid metabolites in APBA for the first time. Most of the tested metabolites increased in ABPA when co-mpared with healthy controls and 15(S)-HETE and 12(S)-HETE may play a role in the pat-hogenesis of ABPA. These findings can provide new ideas for diagnosis, therapy and mon-itor of ABPA.

Profiling the eicosanoid networks that underlie the anti- and pro-thrombotic effects of aspirin

Aspirin prevents thrombosis by inhibiting platelet cyclooxygenase (COX)-1 activity and the production of thromboxane (Tx)A₂, a pro-thrombotic eicosanoid. However, the non-platelet actions of aspirin limit its antithrombotic effects. Here, we used platelet-COX-1-ko mice to define the platelet and non-platelet eicosanoids affected by aspirin. Mass-spectrometry analysis demonstrated blood from platelet-COX-1-ko and global-COX-1-ko mice produced similar eicosanoid profiles in vitro: for example, formation of TxA₂, prostaglandin (PG) F_2α, 11-hydroxyeicosatraenoic acid (HETE), and 15-HETE was absent in both platelet- and global-COX-1-ko mice. Conversely, in vivo, platelet-COX-1-ko mice had a distinctly different profile from global-COX-1-ko or aspirin-treated control mice, notably significantly higher levels of PGI₂ metabolite. Ingenuity Pathway Analysis (IPA) predicted that platelet-COX-1-ko mice would be protected from thrombosis, forming less pro-thrombotic TxA₂ and PGE₂. Conversely, aspirin or lack of systemic COX-1 activity decreased the synthesis of anti-aggregatory PGI₂ and PGD₂ at non-platelet sites leading to predicted thrombosis increase. In vitro and in vivo thrombosis studies proved these predictions. Overall, we have established the eicosanoid profiles linked to inhibition of COX-1 in platelets and in the remainder of the cardiovascular system and linked them to anti- and pro-thrombotic effects of aspirin. These results explain why increasing aspirin dosage or aspirin addition to other drugs may lessen antithrombotic protection.

Unexpected effects of long-term treatment with acetylsalicylic acid on late phase of pulmonary metastasis in murine model of orthotopic breast cancer

Long-term administration of acetylsalicylic acid (ASA) was effective in prevention of colorectal cancer, whereas the efficacy of this compound in other cancer types, including breast cancer, has been less convincingly documented. Indeed, the antimetastatic effect of low-dose ASA was observed only in the early intravascular phase of metastasis of breast cancer. In the present work, we characterized the effects of long-term treatment with ASA on the late phase of pulmonary metastasis in a mouse orthotopic 4T1 breast cancer model. Mice were treated with ASA at a dose of 12 mg·kg^-1 of body weight daily starting one week prior to inoculation of 4T1 breast cancer cells, and the treatment was continued throughout progression of the disease. ASA administration decreased platelet TXB₂ production in ex vivo assays but did not change thrombin-induced platelet reactivity. Although the number of metastases in the lungs remained unchanged in ASA-treated mice, infiltration of inflammatory cells was increased concomitantly with higher G-CSF and serotonin concentrations in the lungs. Pulmonary NO production was compromised compared to control 4T1 mice. ASA treatment also evoked an increase in platelet and granulocyte counts and decreased systemic NO bioavailability along with increased markers of systemic oxidant stress such as higher GSSG/lower GSH concentrations in RBC. Analysis of eicosanoids in stirred blood demonstrated that administration of ASA at a dose of 12 mg·kg^-1 to cancer-bearing mice had an effect beyond inhibition of platelet COX-1, suggesting long-term treatment with low-dose aspirin is not a selective murine platelet COX-1/TXA₂ pathway inhibitor in cancer-bearing mice. In summary, quite surprisingly, long-term treatment with low-dose ASA administered until the advanced phase of breast cancer in a murine orthotopic model of 4T1 breast cancer negatively affected the phenotype of the disease.

Clinical blood sampling for oxylipin analysis - effect of storage and pneumatic tube transport of blood on free and total oxylipin profile in human plasma and serum

Quantitative analysis of oxylipins in blood samples is of increasing interest in clinical studies. However, storage after sampling and transport of blood might induce artificial changes in the apparent oxylipin profile due to ex vivo formation/degradation by autoxidation or enzymatic activity. In the present study we investigated the stability of free (i.e. non-esterified) and total oxylipins in EDTA-plasma and serum generated under clinical conditions assessing delays in sample processing and automated transportation: Free cytochrome P450 monooxygenase and 5-lipoxygenase (LOX) formed oxylipins as well as autoxidation products were marginally affected by storage of whole blood up to 4 h at 4 °C, while total (i.e. the sum of free and esterified) levels of these oxylipins were stable up to 24 h and following transport. Cyclooxygenase (COX) products (TxB₂, 12-HHT) and 12-LOX derived hydroxy-fatty acids were prone to storage and transport induced changes due to platelet activation. Total oxylipin patterns were generally more stable than the concentration of free oxylipins. In serum, coagulation induced higher levels of COX and 12-LOX products showing a high inter-individual variability. Overall, our results indicate that total EDTA-plasma oxylipins are the most stable blood oxylipin marker for clinical samples. Here, storage of blood before further processing is acceptable for a period up to 24 hours at 4 °C. However, levels of platelet derived oxylipins should be interpreted with caution regarding potential ex vivo formation.

The "Janus Face" of Platelets in Cancer

Besides their vital role in hemostasis and thrombosis, platelets are also recognized to be involved in cancer, where they play an unexpected central role: They actively influence cancer cell behavior, but, on the other hand, platelet physiology and phenotype are impacted by tumor cells. The existence of this platelet-cancer loop is supported by a large number of experimental and human studies reporting an association between alterations in platelet number and functions and cancer, often in a way dependent on patient, cancer type and treatment. Herein, we shall report on an update on platelet-cancer relationships, with a particular emphasis on how platelets might exert either a protective or a deleterious action in all steps of cancer progression. To this end, we will describe the impact of (i) platelet count, (ii) bioactive molecules secreted upon platelet activation, and (iii) microvesicle-derived miRNAs on cancer behavior. Potential explanations of conflicting results are also reported: Both intrinsic (heterogeneity in platelet-derived bioactive molecules with either inhibitory or stimulatory properties; features of cancer cell types, such as aggressiveness and/or tumour stage) and extrinsic (heterogeneous characteristics of cancer patients, study design and sample preparation) factors, together with other confounding elements, contribute to “the Janus face” of platelets in cancer. Given the difficulty to establish the univocal role of platelets in a tumor, a better understanding of their exact contribution is warranted, in order to identify an efficient therapeutic strategy for cancer management, as well as for better prevention, screening and risk assessment protocols.

Methods of the Analysis of Oxylipins in Biological Samples

Oxylipins are derivatives of polyunsaturated fatty acids and due to their important and diverse functions in the body, they have become a popular subject of studies. The main challenge for researchers is their low stability and often very low concentration in samples. Therefore, in recent years there have been developments in the extraction and analysis methods of oxylipins. New approaches in extraction methods were described in our previous review. In turn, the old analysis methods have been replaced by new approaches based on mass spectrometry (MS) coupled with liquid chromatography (LC) and gas chromatography (GC), and the best of these methods allow hundreds of oxylipins to be quantitatively identified. This review presents comparative and comprehensive information on the progress of various methods used by various authors to achieve the best results in the analysis of oxylipins in biological samples.

Oxidative pathways of arachidonic acid as targets for regulation of platelet activation

Platelet activation plays an important role in acute and chronic cardiovascular disease states. Multiple pathways contribute to platelet activation including those dependent upon arachidonic acid. Arachidonic acid is released from the platelet membrane by phospholipase A2 action and is then metabolized in the cytosol by specific arachidonic acid oxidation enzymes including prostaglandin H synthase, 12-lipoxygenase, and cytochrome P450 to produce pro- and anti-inflammatory eicosanoids. This review aims to analyze the role of arachidonic acid oxidation on platelet activation, the enzymes that use it as a substrate associated as novel therapeutics target for antiplatelet drugs.

Characterization of supported liquid extraction as a sample pretreatment method for eicosanoids and related metabolites in biological fluids

Sample pretreatment is an important process in liquid chromatography-mass spectrometry-based quantitative lipidomics. Reversed-phase solid phase extraction (RP-SPE) has been widely used for analyzing various types of samples, including aqueous samples such as cell culture media, plasma, serum, urine, and other biological fluids. Because lipid mediators are often protein-bound, prior deproteinization is necessary for their effective recovery. Deproteinization is typically performed by the addition of organic solvents, which requires time-consuming evaporation-reconstitution, or dilution with aqueous solvents before RP-SPE; however, both of these approaches compromise the analytical performance. As a potential alternative, we attempted to utilize supported liquid extraction (SLE), an automation-compatible variant of liquid-liquid extraction, for the determination of eicosanoids and related metabolites in aqueous samples. We screened 81 different sample diluent-eluent conditions and found that the use of 0.1% formic acid-water as the diluent and 0.1% formic acid-methyl acetate as the eluent enabled the optimum recovery of a variety of eicosanoids, except for peptide leukotrienes. The optimized SLE method efficiently removed protein from human plasma, while phospholipids and neutral lipids were modestly recovered. Moreover, the proposed method exhibited a quantitative performance comparable to that of typical ordinary RP-SPE method in the analysis of human platelets stimulated with thrombin receptor-activating peptide 6. Thus, we propose SLE as an attractive option for rapid lipid mediator extraction from aqueous samples.

Modern Methods of Sample Preparation for the Analysis of Oxylipins in Biological Samples

Oxylipins are potent lipid mediators derived from polyunsaturated fatty acids, which play important roles in various biological processes. Being important regulators and/or markers of a wide range of normal and pathological processes, oxylipins are becoming a popular subject of research; however, the low stability and often very low concentration of oxylipins in samples are a significant challenge for authors and continuous improvement is required in both the extraction and analysis techniques. In recent years, the study of oxylipins has been directly related to the development of new technological platforms based on mass spectrometry (LC–MS/MS and gas chromatography–mass spectrometry (GC–MS)/MS), as well as the improvement in methods for the extraction of oxylipins from biological samples. In this review, we systematize and compare information on sample preparation procedures, including solid-phase extraction, liquid–liquid extraction from different biological tissues.

Aspirin blocks formation of metastatic intravascular niches by inhibiting platelet-derived COX-1/thromboxane A2

Because metastasis is associated with the majority of cancer-related deaths, its prevention is a clinical aspiration. Prostanoids are a large family of bioactive lipids derived from the activity of cyclooxygenase-1 (COX-1) and COX-2. Aspirin impairs the biosynthesis of all prostanoids through the irreversible inhibition of both COX isoforms. Long-term administration of aspirin leads to reduced distant metastases in murine models and clinical trials, but the COX isoform, downstream prostanoid, and cell compartment responsible for this effect are yet to be determined. Here, we have shown that aspirin dramatically reduced lung metastasis through inhibition of COX-1 while the cancer cells remained intravascular and that inhibition of platelet COX-1 alone was sufficient to impair metastasis. Thromboxane A2 (TXA2) was the prostanoid product of COX-1 responsible for this antimetastatic effect. Inhibition of the COX-1/TXA2 pathway in platelets decreased aggregation of platelets on tumor cells, endothelial activation, tumor cell adhesion to the endothelium, and recruitment of metastasis-promoting monocytes/macrophages, and diminished the formation of a premetastatic niche. Thus, platelet-derived TXA2 orchestrates the generation of a favorable intravascular metastatic niche that promotes tumor cell seeding and identifies COX-1/TXA2 signaling as a target for the prevention of metastasis.

Prediagnostic Serum Levels of Fatty Acid Metabolites and Risk of Ovarian Cancer in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial

BACKGROUND

Evidence suggests that inflammation increases risk for ovarian cancer. Aspirin has been shown to decrease ovarian cancer risk, though the mechanism is unknown. Studies of inflammatory markers, lipid molecules such as arachidonic acid, linoleic acid, and alpha-linoleic acid metabolites, and development of ovarian cancer are essential to understand the potential mechanisms.

METHODS

We conducted a nested case-control study (157 cases/156 matched controls) within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Unconditional logistic regression was used to estimate the association between prediagnostic serum levels of 31 arachidonic acid/linoleic acid/alpha-linoleic acid metabolites and risk of ovarian cancer.

RESULTS

Five of the 31 arachidonic acid/linoleic acid/alpha-linoleic acid (free fatty acids) metabolites were positively associated with ovarian cancer risk: 8-HETE [tertile 3 vs. 1: OR 2.53 (95% confidence interval [CI] 1.18-5.39), P _trend 0.02], 12,13-DHOME [2.49 (1.29-4.81), 0.01], 13-HODE [2.47 (1.32-4.60), 0.005], 9-HODE [1.97 (1.06-3.68), 0.03], 9,12,13-THOME [2.25 (1.20-4.21), 0.01]. In analyses by subtype, heterogeneity was suggested for 8-HETE [serous OR (95% CI): 2.53 (1.18-5.39) vs. nonserous OR (95% CI): 1.15 (0.56-2.36), P _het 0.1] and 12,13-EpOME [1.95 (0.90-4.22) vs. 0.82 (0.39-1.73), 0.05].

CONCLUSIONS

Women with increased levels of five fatty acid metabolites (8-HETE, 12,13-DHOME, 13-HODE, 9-HODE, and 9,12,13-THOME) were at increased risk of developing ovarian cancer in the ensuing decade. All five metabolites are derived from either arachidonic acid (8-HETE) or linoleic acid (12,13-DHOME, 13-HODE, 9-HODE, 9,12,13-THOME) via metabolism through the LOX/cytochrome P450 pathway.

IMPACT

The identification of these risk-related fatty acid metabolites provides mechanistic insights into the etiology of ovarian cancer and indicates the direction for future research.

Complex roles of the old drug aspirin in cancer chemoprevention and therapy

The nonsteroidal anti-inflammatory agent aspirin is widely used for preventing and treating cardiovascular and cerebrovascular diseases. In addition, epidemiologic evidences reveal that aspirin may prevent a variety of human cancers, while data on the association between aspirin and some kinds of cancer are conflicting. Preclinical studies and clinical trials also reveal the therapeutic effect of aspirin on cancer. Although cyclooxygenase is a well-known target of aspirin, recent studies uncover other targets of aspirin and its metabolites, such as AMP-activated protein kinase, cyclin-dependent kinase, heparanase, and histone. Accumulating evidence demonstrate that aspirin may act in different cell types, such as epithelial cell, tumor cell, endothelial cell, platelet, and immune cell. Therefore, aspirin acts on diverse hallmarks of cancer, such as sustained tumor growth, metastasis, angiogenesis, inflammation, and immune evasion. In this review, we focus on recent progress in the use of aspirin for cancer chemoprevention and therapy, and integratively analyze the mechanisms underlying the anticancer effects of aspirin and its metabolites. We also discuss mechanisms of aspirin resistance and describe some derivatives of aspirin, which aim to overcome the adverse effects of aspirin.

Eicosanoids in platelets and the effect of their modulation by aspirin in the cardiovascular system (and beyond)

Platelets are important players in thrombosis and haemostasis with their function being modulated by mediators in the blood and the vascular wall. Among these, eicosanoids can both stimulate and inhibit platelet reactivity. Platelet Cyclooxygenase (COX)-1-generated Thromboxane (TX)A₂ is the primary prostanoid that stimulates platelet aggregation; its action is counter-balanced by prostacyclin, a product of vascular COX. Prostaglandin (PG)D₂ , PGE₂ and 12-hydroxyeicosatraenoic acid (HETE), or 15-HETE, are other prostanoid modulators of platelet activity, but some also play a role in carcinogenesis. Aspirin permanently inhibits platelet COX-1, underlying its anti-thrombotic and anti-cancer action. While the use of aspirin as an anti-cancer drug is increasingly encouraged, its continued use in addition to P₂ Y₁₂ receptor antagonists for the treatment of cardiovascular diseases is currently debated. Aspirin not only suppresses TXA₂ but also prevents the synthesis of both known and unknown antiplatelet eicosanoid pathways, potentially lessening the efficacy of dual antiplatelet therapies. LINKED ARTICLES: This article is part of a themed section on Eicosanoids 35 years from the 1982 Nobel: where are we now? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.8/issuetoc.

96-well plate-based aggregometry

While there are many bench and bedside tests to assess platelet reactivity, ex vivo light transmission aggregometry (LTA) remains the gold standard. LTA, however, is expensive, time-consuming and requires dedicated equipment and staff, making it impractical in many situations. In addition, there is significant variability between data generated at different testing sites meaning that tests often need to be repeated if a patient is transferred to the care of a different hospital. As such, there is clearly an unmet need for standardization of platelet testing. Using the principles of LTA, aggregometry can be conducted in 96-well plates with readings being made in a standard plate reader. This approach allows for the assessment of multiple concentrations of agonists, since the volume of platelets required for each test is significantly lower than for LTA. Furthermore, the lyophilization of a set panel of agonists to a 96-well plate to produce a stable assay substrate allows the production of portable, standardized plates that can be used to generate reproducible tests at multiple sites. In this review, we will discuss the methods and uses of 96-well plate aggregometry for both research and the clinic.

Kidney Transplantation in a Patient Lacking Cytosolic Phospholipase A2 Proves Renal Origins of Urinary PGI-M and TX-M

RATIONALE

The balance between vascular prostacyclin, which is antithrombotic, and platelet thromboxane A2, which is prothrombotic, is fundamental to cardiovascular health. Prostacyclin and thromboxane A2 are formed after the concerted actions of cPLA2α (cytosolic phospholipase A2) and COX (cyclooxygenase). Urinary 2,3-dinor-6-keto-PGF1α (PGI-M) and 11-dehydro-TXB2 (TX-M) have been taken as biomarkers of prostacyclin and thromboxane A2 formation within the circulation and used to explain COX biology and patient phenotypes, despite concerns that urinary PGI-M and TX-M originate in the kidney.

OBJECTIVE

We report data from a remarkable patient carrying an extremely rare genetic mutation in cPLA2α, causing almost complete loss of prostacyclin and thromboxane A2, who was transplanted with a normal kidney resulting in an experimental scenario of whole-body cPLA2α knockout, kidney-specific knockin. By studying this patient, we can determine definitively the contribution of the kidney to the productions of PGI-M and TX-M and test their validity as markers of prostacyclin and thromboxane A2 in the circulation.

METHODS AND RESULTS

Metabolites were measured using liquid chromatography-tandem mass spectrometry. Endothelial cells were grown from blood progenitors. Before kidney transplantation, the patient's endothelial cells and platelets released negligible levels of prostacyclin (measured as 6-keto-prostaglandin F1α) and thromboxane A2 (measured as TXB2), respectively. Likewise, the urinary levels of PGI-M and TX-M were very low. After transplantation and the establishment of normal renal function, the levels of PGI-M and TX-M in the patient's urine rose to within normal ranges, whereas endothelial production of prostacyclin and platelet production of thromboxane A2 remained negligible.

CONCLUSIONS

These data show that PGI-M and TX-M can be derived exclusively from the kidney without contribution from prostacyclin made by endothelial cells or thromboxane A2 by platelets in the general circulation. Previous work relying on urinary metabolites of prostacyclin and thromboxane A2 as markers of whole-body endothelial and platelet function now requires reevaluation.

An optimised protocol for platelet-rich plasma preparation to improve its angiogenic and regenerative properties

Although platelet-rich plasma (PRP) is used as a source of growth factors in regenerative medicine, its effectiveness remains controversial, partially due to the absence of PRP preparation protocols based on the regenerative role of platelets. Here, we aimed to optimise the protocol by analysing PRP angiogenic and regenerative properties. Three optimising strategies were evaluated: dilution, 4 °C pre-incubation, and plasma cryoprecipitate supplementation. Following coagulation, PRP releasates (PRPr) were used to induce angiogenesis in vitro (HMEC-1 proliferation, migration, and tubule formation) and in vivo (chorioallantoic membrane), as well as regeneration of excisional wounds on mouse skin. Washed platelet releasates induced greater angiogenesis than PRPr due to the anti-angiogenic effect of plasma, which was decreased by diluting PRPr with saline. Angiogenesis was also improved by both PRP pre-incubation at 4 °C and cryoprecipitate supplementation. A combination of optimising variables exerted an additive effect, thereby increasing the angiogenic activity of PRPr from healthy donors and diabetic patients. Optimised PRPr induced faster and more efficient mouse skin wound repair compared to that induced by non-optimised PRPr. Acetylsalicylic acid inhibited angiogenesis and tissue regeneration mediated by PRPr; this inhibition was reversed following optimisation. Our findings indicate that PRP pre-incubation at 4 °C, PRPr dilution, and cryoprecipitate supplementation improve the angiogenic and regenerative properties of PRP compared to the obtained by current methods.

Genomic and lipidomic analyses differentiate the compensatory roles of two COX isoforms during systemic inflammation in mice

Both cyclooxygenase (COX)-1 and COX-2, encoded by Ptgs1 and Ptgs2, function coordinately during inflammation. But the relative contributions and compensations of COX-1 and COX-2 to inflammatory responses remain unanswered. We used three engineered mouse lines where the Ptgs1 and Ptgs2 genes substitute for one another to discriminate the distinct roles and interchangeability of COX isoforms during systemic inflammation. In macrophages, kidneys, and lungs, "flipped" Ptgs genes generate a "reversed" COX expression pattern, where the knock-in COX-2 is expressed constitutively and the knock-in COX-1 is lipopolysaccharide inducible. A panel of eicosanoids detected in serum and kidney demonstrates that prostaglandin (PG) biosynthesis requires native COX-1 and cannot be rescued by the knock-in COX-2. Our data further reveal preferential compensation of COX isoforms for prostanoid production in macrophages and throughout the body, as reflected by urinary PG metabolites. NanoString analysis indicates that inflammatory networks can be maintained by isoform substitution in inflamed macrophages. However, COX-1>COX-2 macrophages show reduced activation of inflammatory signaling pathways, indicating that COX-1 may be replaced by COX-2 within this complex milieu, but not vice versa. Collectively, each COX isoform plays a distinct role subject to subcellular environment and tissue/cell-specific conditions, leading to subtle compensatory differences during systemic inflammation.

Carpe low-dose aspirin: the new anti-cancer face of an old anti-platelet drug

Cancer metastasis is a dynamic process during which cancer cells separate from a primary tumor, migrate through the vessel wall into the bloodstream, and extravasate at distant sites to form secondary colonies. During this process, circulating tumor cells are subjected to shear stress forces from blood flow, and in contact with plasma proteins and blood cells of the immune and hemostatic system, including platelets. Many studies have shown an association between high platelet count and cancer metastasis, suggesting that platelets may play an occult role in tumorigenesis. This mini-review summarizes recent and emerging discoveries of mechanisms by which cancer cells activate platelets and the role of activated platelets in promoting tumor growth and metastasis. Moreover, the review discusses how aspirin has the potential for being clinically used as an adjuvant in cancer therapy.

Effect of Dialysis on Antiplatelet Drug Efficacy in Uremic Patients with Coronary Heart Disease

Background:

Coronary intervention therapy is the main treatment for uremic patients with coronary heart disease. The studies on whether dialysis reduces the efficacy of dual antiplatelet drugs are limited. The aim of this study was to examine the effect of dialysis on antiplatelet drugs in uremic patients with coronary heart disease.

Methods:

This study included 26 uremic patients who had undergone percutaneous coronary intervention in China-Japan Friendship Hospital from November 2015 to May 2017. We examined their thromboelastography results before and after hemodialysis. Self-paired t-tests were employed to analyze changes in the inhibition rate of platelet aggregation.

Results:

The mean inhibition rates of arachidonic acid-induced platelet aggregation before and after hemodialysis were 82.56 ± 2.79% and 86.42 ± 3.32%, respectively (t = −1.278, P = 0.213). The mean inhibition rates of adenosine diphosphate-induced platelet aggregation before and after hemodialysis were 67.87 ± 5.10% and 61.94 ± 5.90%, respectively (t = 1.425, P = 0.167). There was no significant difference in the inhibition rates of platelet aggregation before or after hemodialysis. These results also applied to patients with different sensitivity to aspirin and clopidogrel.

Conclusion:

Dialysis did not affect the antiplatelet effects of aspirin and clopidogrel in uremic patients with coronary heart disease.

MMP-2, MMP-9, and TIMP-4 and Response to Aspirin in Diabetic and Nondiabetic Patients with Stable Coronary Artery Disease: A Pilot Study

Background

High on-aspirin treatment platelets reactivity (HPR) is a significant problem in long-term secondary prevention of cardiovascular events. We hypothesize that imbalance between platelets MMPs/TIMPs results in cardiovascular disorders. We also explored whether chronically elevated blood glucose affects MMP-2/TIMP-4 release from platelets.

Materials and Methods

Seventy patients with stable coronary artery disease, supplemented with aspirin, participated in this pilot study. The presence of HPR and/or diabetes mellitus was considered as the differentiating factor. Light aggregometry, impedance aggregometry, and ELISA tests for TXB2, MMP-2, MMP-9, and TIMP-4 were performed in serum, plasma, platelet-rich plasma, and platelets-poor plasma, as appropriate.

Results

Aspirin-HPR did not affect plasma MMP-2, MMP-9, and TIMP-4. Arachidonic acid-induced aggregation of platelets from aspirin-HPR patients did not lead to increased release of MMP-2, MMP-9, and TIMP-4. Studying patients at the lowest TXB2 serum concentration quartile revealed that high concentration of plasma TIMP-4 and TIMP-4 negatively correlated with TXB2 and platelet aggregation. Diabetics showed an increased plasma MMP-2 as well as an increased MMP-2 in supernatants after platelet aggregation. However, diabetes mellitus did not affect MMP-9 and TIMP-4.

Conclusion

Aspirin-HPR did not affect the translocation and release of MMPs and TIMP-4 from platelets. TIMP-4 may serve as a marker of TXA2-mediated platelet aggregation. Chronically elevated plasma glucose increases plasma MMP-2, and HPR potentiates this phenomenon.