Clopidogrel increases expression of chemokines in peripheral blood mononuclear cells in patients with coronary artery disease: results of a double-blind placebo-controlled study

Peripheral Blood RNAs and Left Ventricular Dysfunction after Myocardial Infarction: Towards Translation into Clinical Practice

The treatment and early outcome of patients with acute myocardial infarction (MI) have dramatically improved the past decades, but the incidence of left ventricular (LV) dysfunction post-MI remains high. Peripheral blood RNAs reflect pathophysiological changes during acute MI and the inflammatory process. Therefore, these RNAs are promising new markers to molecularly phenotype patients and improve the early identification of patients at risk of subsequent LV dysfunction. We here discuss the coding and long non-coding RNAs that can be measured in peripheral blood of patients with acute MI and list the advantages and limitations for implementation in clinical practice. Although some studies provide preliminary evidence of their diagnostic and prognostic potential, the use of these makers has not yet been implemented in clinical practice. The added value of RNAs to improve treatment and outcome remains to be determined in larger clinical studies. International consortia are now catalyzing renewed efforts to investigate novel RNAs that may improve post-MI outcome in a precision-medicine approach. Graphical Abstract Peripheral blood RNAs reflect the inflammatory changes in acute MI. A number of studies provide preliminary evidence of their prognostic potential, although the use of these makers has not yet been assessed in clinical practice.

End-stage renal disease is different from chronic kidney disease in upregulating ROS-modulated proinflammatory secretome in PBMCs - A novel multiple-hit model for disease progression

Background

The molecular mechanisms underlying chronic kidney disease (CKD) transition to end-stage renal disease (ESRD) and CKD acceleration of cardiovascular and other tissue inflammations remain poorly determined.

Methods

We conducted a comprehensive data analyses on 7 microarray datasets in peripheral blood mononuclear cells (PBMCs) from patients with CKD and ESRD from NCBI-GEO databases, where we examined the expressions of 2641 secretome genes (SG).

Results

1) 86.7% middle class (molecular weight >500 Daltons) uremic toxins (UTs) were encoded by SGs; 2) Upregulation of SGs in PBMCs in patients with ESRD (121 SGs) were significantly higher than that of CKD (44 SGs); 3) Transcriptomic analyses of PBMC secretome had advantages to identify more comprehensive secretome than conventional secretomic analyses; 4) ESRD-induced SGs had strong proinflammatory pathways; 5) Proinflammatory cytokines-based UTs such as IL-1β and IL-18 promoted ESRD modulation of SGs; 6) ESRD-upregulated co-stimulation receptors CD48 and CD58 increased secretomic upregulation in the PBMCs, which were magnified enormously in tissues; 7) M1-, and M2-macrophage polarization signals contributed to ESRD- and CKD-upregulated SGs; 8) ESRD- and CKD-upregulated SGs contained senescence-promoting regulators by upregulating proinflammatory IGFBP7 and downregulating anti-inflammatory TGF-β1 and telomere stabilizer SERPINE1/PAI-1; 9) ROS pathways played bigger roles in mediating ESRD-upregulated SGs (11.6%) than that in CKD-upregulated SGs (6.8%), and half of ESRD-upregulated SGs were ROS-independent.

Conclusions

Our analysis suggests novel secretomic upregulation in PBMCs of patients with CKD and ESRD, act synergistically with uremic toxins, to promote inflammation and potential disease progression. Our findings have provided novel insights on PBMC secretome upregulation to promote disease progression and may lead to the identification of new therapeutic targets for novel regimens for CKD, ESRD and their accelerated cardiovascular disease, other inflammations and cancers. (Total words: 279).

Differences in high on-treatment platelet reactivity between intracoronary and peripheral blood after dual anti-platelet agents in patients with coronary artery disease

The differences of high on-treatment platelet reactivity (HPR) between the coronary arteries and peripheral veins might be associated with poor prediction of adverse cardiovascular events in patients with coronary artery diseases. HPR from the peripheral blood might not adequately reflect the platelet responses in the coronary artery. A total of 21 patients were recruited, and regional differences in HPR were compared between blood samples from the intra-coronary artery (IC), femoral artery (FA), and femoral vein (FV) by light aggregometry (agonists: arachidonic acid, LTA-AA; ADP, LTA-ADP), VerifyNow P2Y12 assays, and a platelet function analyser (PFA-100, collagen and epinephrine cartridge, PFA-CEPI). There were regional differences in the platelet reactivities observed by LTA-AA, VerifyNow P2Y12 assays, and PFACEPI. Platelets from the IC had higher platelet reactivities than those from the FV and FA by the VerifyNow P2Y12 assays but lower reactivities by LTA-AA and PFA-CEPI. HPR values from the blood in the FA were more similar to those from the IC than those from the FV by any test. The monocyte percentages were the only factors associated with differences in HPR between the FV and IC by the VerifyNow P2Y12 assays. Triglyceride levels were associated with the differences in HPR between the FV and IC by LTA-ADP. During the six-month follow-up period, two patients developed cardiovascular events and exhibited differences in HPR between different sites by VerifyNow P2Y12 assays. In conclusions, there were regional differences in HPR in patients with coronary artery diseases, which might prevent the adequate prediction of cardiovascular events.

Platelets in inflammation and atherogenesis

Platelets contribute to processes beyond thrombus formation and may play a so far underestimated role as an immune cell in various circumstances. This review outlines immune functions of platelets in host defense, but also how they may contribute to mechanisms of infectious diseases. A particular emphasis is placed on the interaction of platelets with other immune cells. Furthermore, this article outlines the features of atherosclerosis as an inflammatory vascular disease highlighting the role of platelet crosstalk with cellular and soluble factors involved in atheroprogression. Understanding, how platelets influence these processes of vascular remodeling will shed light on their role for tissue homeostasis beyond intravascular thrombosis. Finally, translational implications of platelet-mediated inflammation in atherosclerosis are discussed.

The role of P2Y₁₂ receptor and activated platelets during inflammation

Platelets play an important role not only during thrombosis, but also in modulating immune responses through their interaction with immune cells and by releasing inflammatory mediators upon activation. The P2Y12 receptor is a Gi-coupled receptor that not only regulates ADP-induced aggregation but can also dramatically potentiate secretion, when platelets are activated by other stimuli. Considering the importance of P2Y12 receptor in platelet function, a class of antiplatelet drugs, thienopyridines, have been designed and successfully used to prevent thrombosis. This review will focus on the role of activated platelets in inflammation and the effects that P2Y12 antagonism exerts on the inflammatory process. A change in platelet functions was noted in patients treated with thienopyridines during inflammatory conditions, suggesting that platelets may modulate the inflammatory response. Further experiments in a variety of animal models of diseases, such as sepsis, rheumatoid arthritis, myocardial infarction, pancreatitis and pulmonary inflammation have also demonstrated that activated platelets influence the inflammatory state. Platelets can secrete inflammatory modulators in a P2Y12-dependent manner, and, as a result, directly alter the inflammatory response. P2Y12 receptor may also be expressed in other cells of the immune system, indicating that thienopyridines could directly influence the immune system rather than only through platelets. Overall the results obtained to date strongly support the notion that activated platelets significantly contribute to the inflammatory process and that antagonizing P2Y12 receptor can influence the immune response.

The platelet P2 receptors in inflammation

In addition to their well characterized and established role in haemostasis and thrombosis, platelets contribute to the pathogenesis of inflammation. Adenine nucleotides are signalling molecules that regulate the function of virtually every cell in the body, by interacting with P2 receptors. Their important role in inflammation is well established. In the last few years, the pro-inflammatory roles of adenine nucleotides interacting with their platelet P2 receptors has emerged. In particular, it was shown that the platelet P2Y12 receptor for ADP significantly contributed to the pro-inflammatory effects of cysteinyl leukotrienes (CysLT) in experimental models of asthma in mice. More importantly, it was recently shown that P2Y12 variants were associated with lung function in a large family-based asthma cohort and that the P2Y12 antagonist prasugrel tended to decrease bronchial hyper-reactivity to mannitol in patients with allergic bronchial asthma in a randomized, placebo controlled trial.

CONCLUSION

These data strongly suggest that P2Y12 may represent an important pharmacological target for the treatment of patients with allergic bronchial asthma.

8-BuS-ATP derivatives as specific NTPDase1 inhibitors

BACKGROUND AND PURPOSE

Ectonucleotidases control extracellular nucleotide levels and consequently, their (patho)physiological responses. Among these enzymes, nucleoside triphosphate diphosphohydrolase-1 (NTPDase1), -2, -3 and -8 are the major ectonucleotidases responsible for nucleotide hydrolysis at the cell surface under physiological conditions, and NTPDase1 is predominantly located at the surface of vascular endothelial cells and leukocytes. Efficacious inhibitors of NTPDase1 are required to modulate responses induced by nucleotides in a number of pathological situations such as thrombosis, inflammation and cancer.

EXPERIMENTAL APPROACH

Here, we present the synthesis and enzymatic characterization of five 8-BuS-adenine nucleotide derivatives as potent and selective inhibitors of NTPDase1.

KEY RESULTS

The compounds 8-BuS-AMP, 8-BuS-ADP and 8-BuS-ATP inhibit recombinant human and mouse NTPDase1 by mixed type inhibition, predominantly competitive with Ki values <1 μM. In contrast to 8-BuS-ATP which could be hydrolyzed by other NTPDases, the other BuS derivatives were resistant to hydrolysis by either NTPDase1, -2, -3 or -8. 8-BuS-AMP and 8-BuS-ADP were the most potent and selective inhibitors of NTPDase1 expressed in human umbilical vein endothelial cells as well as in situ in human and mouse tissues. As expected, as a result of their inhibition of recombinant human NTPDase1, 8-BuS-AMP and 8-BuS-ADP impaired the ability of this enzyme to block platelet aggregation. Importantly, neither of these two inhibitors triggered platelet aggregation nor prevented ADP-induced platelet aggregation, in support of their inactivity towards P2Y1 and P2Y12 receptors.

CONCLUSIONS AND IMPLICATIONS

The 8-BuS-AMP and 8-BuS-ADP have therefore potential to serve as drugs for the treatment of pathologies regulated by NTPDase1.

A Seeming Paradox: Ischemic Stroke in the Context of Idiopathic Thrombocytopenic Purpura

Nowadays, we have a relatively sophisticated standard approach to a patient with acute ischemic stroke, including the sequence of diagnostic methods and treatment modalities. In practice, however, we are occasionally confronted with a patient whose medical history or comorbidities force us to make a decision without the support of guidelines. One such situation is the occurrence of acute ischemic stroke in a patient with known idiopathic thrombocytopenic purpura, where a tendency to use thrombolysis, anticoagulants, or antiplatelet agents collides with the fear of life-threatening bleeding. In this review, we try to outline current understanding of the pathophysiology of "paradoxical" ischemic events in this illness characterized by thrombocytopenia and to summarize clinical experience from case reports dealing with this topic, which could help us to rely on more than individual opinion seen through a purely "neurological" or "hematological" prism.

No effect of clopidogrel activity or cessation on vascular function or markers of inflammation

The platelet adenosine diphosphate (ADP)-receptor blocker clopidogrel is effective in reducing the rate of thrombosis in cardiovascular disease, but may also have nonplatelet activity. However, there is variability in the suppression of platelet function in individuals, leading to the concept of clopidogrel resistance, that is, reduced platelet-suppressing activity. We tested the hypothesis that some of the beneficial effect of clopidogrel may be due to the variable activity of this drug on the vascular system (assessed by plasma markers von Willebrand factor and soluble E-selectin, and functional arterial pulse wave velocity) and inflammation (C-reactive protein and interleukin-6) while 32 patients with coronary artery disease taking 75 mg clopidogrel daily, and again 2 weeks after cessation of clopidogrel therapy. Platelet responsiveness to clopidogrel was assessed by the phosphorylation of intracellular regulatory protein-vasodilator-stimulated phosphoprotein method and aggregometry to ADP. Response to aspirin was assessed using arachidonic acid (AA), and soluble P-selectin and PAC-1 were also measured. While on clopidogrel, there were no relationships between any vascular or inflammatory index and the response to clopidogrel. After stopping clopidogrel, there were no differences in platelet aggregation to AA, or the expression of P-selectin or PAC-1 at rest, or after stimulation by AA, but platelet responses to ADP all increased (p < 0.01). Although soluble P-selectin increased when clopidogrel was stopped (p = 0.006), there were no changes in plasma markers or vascular function. We conclude that 75 mg/day clopidogrel has no effect of markers of vascular function or inflammation.

Influence of genetic variations on levels of inflammatory markers of healthy subjects at baseline and one week after clopidogrel therapy; results of a preliminary study

We aimed to assess the association between the most common polymorphisms of cytochrome P450 (CYP) epoxygenases on the plasma levels of inflammatory markers in a population of healthy subjects. We also sought to determine whether CYP2C19*2 polymorphism is associated with the anti-inflammatory response to clopidogrel. In a population of 49 healthy young males, the baseline plasma levels of inflammatory markers including C-reactive protein, haptoglobin, orosomucoid acid, CD-40 were compared in carriers vs. non-carriers of the most frequent CYP epoxygenase polymorphisms: CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP2C8*2 and CYP2J2*7. Also, the variation of inflammatory markers from baseline to 7 days after administration of 75 mg per day of clopidogrel were compared in carriers vs. non-carriers of CYP2C19* allele and also in responders vs. hypo-responders to clopidogrel, determined by platelet reactivity tests. There was no significant association between epoxygenase polymorphisms and the baseline levels of inflammatory markers. Likewise, CYP2C19* allele was not associated with anti-inflammatory response to clopidogrel. Our findings did not support the notion that the genetic variations of CYP epoxygenases are associated with the level of inflammatory markers. Moreover, our results did not support the hypothesis that CYP2C19*2 polymorphism is associated with the variability in response to the anti-inflammatory properties of clopidogrel.

Pharmacogenomics of anti-platelet therapy focused on peripheral blood cells of coronary arterial disease patients

BACKGROUND

To investigate genes differentially expressed in peripheral blood cells (PBCs) from patients with coronary arterial disease (CAD) under double anti-platelet therapy.

METHODS

Twenty-six CAD patients that were submitted to percutaneous coronary intervention (PCI) were selected to participate in this study. These patients took 100mg/day of acetylsalicylic acid (ASA) and 75mg/day of clopidogrel. Blood samples were collected before PCI to evaluate platelet reactivity using VerifyNow ASA and P2Y12 assays (Accumetrics). The patients were stratified into 4 quartiles based on ASA reaction units (ARUs) and P2Y12 reaction units (PRUs). Quartile 1 (Q1) patients were classified as responders and quartile 4 (Q4) patients as non-responders. Global mRNA expression from Q1 to Q4 was analyzed by microarray using the GeneChip Exon 1.0 ST array (Affymetrix) and was confirmed by RT-qPCR.

RESULTS

Patients with ARU or PRU values within the first quartile (Q1, ARU<390 and PRU<151) were considered responders, while those who had ARU or PRU within the fourth quartile (Q4, ARU>467 and PRU>260) were considered nonresponders. The risk factors associated for CAD showed expected frequencies and no difference was found between Q1 and Q4. Microarray analysis identified 117 genes differentially expressed for ASA and 29 for clopidogrel between Q1 and Q4 groups (p<0.01, FC>1.2).

CONCLUSION

The variation in response to ASA may be related with an increased expression of IGF1 and IGF1R, as well as a response to clopidogrel can be affected by pharmacokinetic change related to the reverse transport pathway by increased expression of ABCC3.

Ticagrelor, but not clopidogrel and prasugrel, prevents ADP-induced vascular smooth muscle cell contraction: a placebo-controlled study in rats

INTRODUCTION

Off-target effects of novel antiplatelet agents due to their potential clinical benefits are currently an area of intensive investigation. We aimed to compare the effects of different P2Y(12) antagonists on the reactivity of vascular smooth muscle cells.

MATERIALS AND METHODS

Wistar rats (n=30) were pretreated with an investigated drug or placebo. Clopidogrel (50mg/kg, n=7), prasugrel (10mg/kg, n=7), ticagrelor (10mg/kg, n=7) or placebo (n=9) were administered orally 12 and 2 hours before experiments. Constrictions of rat tail arteries induced with a stable analogue of adenosine diphosphate (2-MeS-ADP), phenylephrine and arginine vasopressin were measured as an increase in perfusion pressure. Effects of ticagrelor were assessed in the presence of ticagrelor (1μM/L) added to the perfusion solution as this drug reversibly inhibits the P2Y(12) receptor.

RESULTS

Pretreatment with clopidogrel and prasugrel did not inhibit 2-MeS-ADP-induced contraction while ticagrelor did. Experiments employing endothelium-deprived arteries provided similar results. Clopidogrel and prasugrel did not influence concentration-response curves in the presence of neither phenylephrine nor arginine vasopressin. The curves obtained for both vasopressors in the presence of ticagrelor and 2-MeS-ADP were shifted to the right with a significant reduction in the maximal response.

CONCLUSIONS

Oral administration of ticagrelor, in contrast to clopidogrel and prasugrel, prevents adenosine diphosphate-induced contraction of vascular smooth muscle cells in a rat model. Both the clinical significance and detailed mechanism of our findings warrant further investigation.

Platelets in atherosclerosis

Beyond obvious functions in haemostasis and thrombosis, platelets are considered to be essential in proinflammatory surroundings such as atherosclerosis, allergy, rheumatoid arthritis and even cancer. In atherosclerosis, platelets facilitate the recruitment of inflammatory cells towards the lesion sites and release a plethora of inflammatory mediators, thereby enriching and boosting the inflammatory milieu. Platelets do so by interacting with endothelial cells, circulating leukocytes (monocytes, neutrophils, dendritic cells, T-cells) and progenitor cells. This cross-talk enforces leukocyte activation, adhesion and transmigration. Furthermore, platelets are known to function in innate host defense through the release of antimicrobial peptides and the expression of pattern recognition receptors. In severe sepsis, platelets are able to trigger the formation of neutrophil extracellular traps (NETs), which bind and clear pathogens. The present antiplatelet therapies that target key pathways of platelet activation and aggregation therefore hold the potential to modulate platelet-derived immune functions by reducing cellular interactions of platelets with other immune components and by reducing the secretion of inflammatory proteins into the milieu. The objective of this review is to update and discuss the current perceptions of the platelet immune constituents and their prospect as therapeutic targets in an atherosclerotic setting.

Inhibition of vascular ectonucleotidase activities by the pro-drugs ticlopidine and clopidogrel favours platelet aggregation

BACKGROUND AND PURPOSE

After conversion to their active forms by the liver, ticlopidine and clopidogrel exert antiplatelet effects through irreversible inhibition of the P2Y₁₂ receptor. Concentrations of nucleotides such as ADP, the physiological agonist at platelet P2Y₁ and P2Y₁₂ receptors, are regulated by vascular ectonucleotidases, mainly nucleoside triphosphate diphosphohydrolase (NTPDase)1 and ecto-5'-nucleotidase. Here we evaluate the effect of these pro-drugs on vascular ectonucleotidase activity and on the natural function of these enzymes in regulating platelet aggregation.

EXPERIMENTAL APPROACH

Nucleotidase assays were performed by HPLC and by P(i) determination, using human umbilical vein endothelial cells (HUVEC) and protein extracts from transfected COS-7 cells as sources of enzymes. Platelet aggregation was assayed using human platelet-rich plasma.

KEY RESULTS

Each pro-drug inhibited endothelial ectonucleotidase activities and decreased their ability to block platelet aggregation in vitro. At their therapeutic concentrations, ticlopidine (60 µM) and clopidogrel (20 µM) inhibited ADP hydrolysis by HUVEC by about 80%, and AMP hydrolysis by one-third. Accordingly, these compounds showed a mixed-type inhibition of recombinant human NTPDase1 with an apparent K(i) (K(i,app) ) of 10 µM (clopidogrel) and 14 µM (ticlopidine). Recombinant rat ecto-5'-nucleotidase, but not its human orthologue, was inhibited by ticlopidine with a K(i,app) of 4.5 mM.

CONCLUSIONS AND IMPLICATIONS

These pro-drugs facilitated platelet aggregation via the inhibition of vascular NTPDase1 in vitro. Further studies should be performed to assess whether this effect also occurs in vivo, especially at the beginning of treatment, before sufficient levels of active metabolites are produced by the liver.

Platelets as immune mediators: their role in host defense responses and sepsis

Platelets occupy a central role at the interface between thrombosis and inflammation. At sites of vascular damage, adherent platelets physically and functionally interact with circulating leukocytes. Activated platelets release soluble factors into circulation that may have local and systemic effects on blood and vascular cells. Platelets can also interact with a wide variety of microbial pathogens. Emerging evidence from animal models suggests that platelets may participate in a wide variety of processes involving tissue injury, immune responses and repair that underlie diverse diseases such as atherosclerosis, autoimmune disorders, inflammatory lung and bowel disorders, host-defense responses and sepsis. In this review, we summarize the general mechanisms by which platelets may contribute to immune function, and then discuss evidence for their role in host defense responses and sepsis from preclinical and clinical studies.

Clinical outcomes of patients with diabetic nephropathy randomized to clopidogrel plus aspirin versus aspirin alone (a post hoc analysis of the clopidogrel for high atherothrombotic risk and ischemic stabilization, management, and avoidance [CHARISMA] trial)

No prospective randomized trial has specifically examined the long-term outcomes of clopidogrel use in patients with chronic kidney disease. This study aimed to determine the risks and benefits of long-term clopidogrel administration in patients with diabetic nephropathy, the most common form of chronic kidney disease. We performed a post hoc analysis of the CHARISMA trial, which randomly assigned patients without active acute coronary syndrome, but with established atherosclerotic disease (symptomatic) or multiple risk factors for atherosclerotic disease (asymptomatic), to clopidogrel plus aspirin versus placebo plus aspirin. All CHARISMA patients (n = 15,603) were separated into the 3 groups: nondiabetic patients, diabetic patients without nephropathy, and diabetic patients with nephropathy. Within each group, outcomes of patients randomly assigned to clopidogrel were compared with those of patients randomly assigned to placebo. Outcomes in the prespecified CHARISMA subgroups of asymptomatic and symptomatic patients were also compared with respect to study drug assignment and nephropathy status. Patients with nephropathy who received clopidogrel had no difference in bleeding, but experienced significantly increased cardiovascular (CV) and overall mortality compared with those randomly assigned to placebo. There were no differences in bleeding, overall mortality, or CV mortality for nondiabetic or diabetic patients without nephropathy who received clopidogrel versus placebo. In the asymptomatic cohort, patients with nephropathy randomly assigned to clopidogrel had significantly increased overall and CV mortality compared with placebo, whereas asymptomatic patients without nephropathy randomly assigned to clopidogrel had no significant mortality difference compared with placebo. In conclusion, this post hoc analysis suggested that clopidogrel may be harmful in patients with diabetic nephropathy. Additional studies are needed to investigate this possible interaction.

Association between the efficacy of dual antiplatelet therapy and the development of in-stent neointimal hyperplasia in porcine coronary arteries

OBJECTIVE

We set out to compare the effectiveness of platelet aggregation therapy in association with the development of in-stent neointimal hyperplasia in porcine coronary arteries.

METHODS

Thirty-two pigs underwent coronary stenting with bare-metal stents under general anaesthesia. One hundred milligrams of aspirin and loading doses of either 300 mg clopidogrel (group C, n=13) or 2 x 500 mg ticlopidine (group T, n=19) were administered before intervention. During the follow-up, the animals received a daily dose of 100 mg aspirin and 75 mg clopidogrel or 2 x 250 mg ticlopidine, respectively. After 4 weeks, the histopathological and histomorphometric parameters of the explanted stented coronaries were assessed. Levels of circulating cytokines and platelet activation factors were measured. ADP-induced and collagen-induced aggregation was measured immediately before stenting and then every 3rd day. The aggregation profiles were calculated and correlated with the histological parameters.

RESULTS

The fibrin deposition scores and inflammation scores were higher in group T than in group C, with similar injury scores. Endothelialization was complete in both groups. A significantly lower neointimal area (1.08+/-0.36 vs. 1.58+/-0.5, group C vs. T, P=0.026) and percentage of area stenosis (29.8+/-12.1 vs. 44.3+/-16.3, group C vs. T, P=0.032) were observed in group C. The loading dose of clopidogrel significantly reduced the platelet activation parameters before the first angiography as compared with ticlopidone. Clopidogrel treatment resulted in a significantly better aggregation profile relative to ticlopidine (mean ADP-induced aggregation: 28.4+/-9.1 vs. 52.5+/-12.0%, P<0.001). Significant (P<0.05) positive linear correlations were observed between the ADP-induced aggregation profile and the neointimal area (r=0.584), percentage of area stenosis (r=0.666), inflammation (r=0.476) and fibrin deposition (r=0.496).

CONCLUSION

The effectiveness of dual antiplatelet therapy plays an important role in the inhibition of in-stent neointimal hyperplasia.

Cerebral infarction in idiopathic thrombocytopenic purpura: a case report

Cerebral infarction is a rare but recognised complication of idiopathic thrombocytopenic purpura. With traditional therapies including antiplatelets precluded in such patients and little guidance in the literature, the optimal treatment strategy is unknown. This report describes a case of ischaemic stroke in a patient with idiopathic thrombocytopenic purpura and deteriorating neurology. A successful outcome was made possible using a sequential approach initially improving platelet levels with steroids and intravenous immunoglobulin and then commencing antiplatelet agents. A possible mechanism for thrombosis in idiopathic thrombocytopenic purpura is considered.

Novel uses for anti-platelet agents as anti-inflammatory drugs

An alteration in the character and function of platelets is manifested in patients with inflammatory diseases, and these alterations have been dissociated from the well-characterized involvement of platelets in thrombosis and haemostasis. Recent evidence reveals platelet activation is sometimes critical in the development of inflammation. The mechanisms by which platelets participate in inflammation are diverse, and offer numerous opportunities for future drug intervention. There is now acceptance that platelets act as innate inflammatory cells in immune responses, with roles as sentinel cells undergoing surveillance, responding to microbial invasion, orchestrating leukocyte recruitment, and migrating through tissue, causing damage and influencing repair processes in chronic disease. Some of these processes are targeted by drugs that are being developed to target platelet participation in atherosclerosis. The actions of platelets therefore influence the pathogenesis of diverse inflammatory diseases in various body compartments, encompassing parasitic and bacterial infection, allergic inflammation (especially asthma and rhinitis), and non-atopic inflammatory conditions, for example, chronic obstructive pulmonary disease (COPD), rheumatoid arthritis (RA), inflammatory bowel disease (IBD) and atherosclerosis. This review will first discuss the evidence for platelet activation in these various inflammatory diseases, and secondly discuss the mechanisms by which this pathogenesis occurs and the various anti-platelet agents which have been developed to combat platelet activation in atherosclerosis and their potential future use for the treatment of other inflammatory diseases.