Similar Impact of Clopidogrel or Ticagrelor on Carotid Atherosclerotic Plaque Inflammation

Snake Venom Components as Therapeutic Drugs in Ischemic Heart Disease

Ischemic heart disease (IHD), especially myocardial infarction (MI), is a leading cause of death worldwide. Although coronary reperfusion is the most straightforward treatment for limiting the MI size, it has nevertheless been shown to exacerbate ischemic myocardial injury. Therefore, identifying and developing therapeutic strategies to treat IHD is a major medical challenge. Snake venoms contain biologically active proteins and peptides that are of major interest for pharmacological applications in the cardiovascular system (CVS). This has led to their use for the development and design of new drugs, such as the first-in-class angiotensin-converting enzyme inhibitor captopril, developed from a peptide present in Bothrops jararaca snake venom. This review discusses the potential usefulness of snake venom toxins for developing effective treatments against IHD and related diseases such as hypertension and atherosclerosis. It describes their biological effects at the molecular scale, their mechanisms of action according to their different pharmacological properties, as well as their subsequent molecular pathways and therapeutic targets. The molecules reported here have either been approved for human medical use and are currently available on the drug market or are still in the clinical or preclinical developmental stages. The information summarized here may be useful in providing insights into the development of future snake venom-derived drugs.

Pleiotropic effects of clopidogrel

Clopidogrel is a widely prescribed prodrug with anti-thrombotic activity through irreversible inhibition of the P2Y₁₂ receptor on platelets. It is FDA-approved for the clinical management of thrombotic diseases like unstable angina, myocardial infarction, stroke, and during percutaneous coronary interventions. Hepatic clopidogrel metabolism generates several distinct metabolites. Only one of these metabolites is responsible for inhibiting the platelet P2Y₁₂ receptor. Importantly, various non-hemostatic effects of clopidogrel therapy have been described. These non-hemostatic effects are perhaps unsurprising, as P2Y₁₂ receptor expression has been reported in multiple tissues, including osteoblasts, leukocytes, as well as vascular endothelium and smooth muscle. While the "inactive" metabolites have been commonly thought to be biologically inert, recent findings have uncovered P2Y₁₂ receptor-independent effects of clopidogrel treatment that may be mediated by understudied metabolites. In this review, we summarize both the P2Y₁₂ receptor-mediated and non-P2Y₁₂ receptor-mediated effects of clopidogrel and its metabolites in various tissues.

Comparison of the effect of ticagrelor combined with tirofiban versus clopidogrel combined with tirofiban on inflammation response and prognosis of patients with unstable angina pectoris in long term follow-up

To investigate the effect of ticagrelor combined with tirofiban versus clopidogrel combined with tirofiban on inflammation response and prognosis of patients with unstable angina pectoris (UA). The present prospective study included a total of 291 patients who were diagnosed as unstable UA from January 2018 to December 2019. All UA patients were divided into two groups: ticagrelor combined with tirofiban group (n = 159) and clopidogrel combined with tirofiban group (n = 132). Serum levels of C-reactive protein (CRP), interleukin-1β, interleukin-6, tumor necrosis factor-α, and matrix metalloproteinase-9 were measured using commercially available enzyme-linked immunosorbent assay kits. Kaplan-Meier (K-M) curve was performed for analysis of cumulative incidences of major adverse cardiovascular events (MACEs). Both ticagrelor combined with tirofiban and clopidogrel combined with tirofiban significantly decreased the serum levels of inflammatory factors in UA patients. Compared to clopidogrel combined with the tirofiban group, ticagrelor combined with the tirofiban group had a lower platelet aggregation rate and improved cardiac function of UA patients. Besides, ticagrelor combined with tirofiban group had a better prognosis and the K-M curve showed that UA patients treated by ticagrelor and tirofiban had lower incidences of MACEs in one-year follow-up. The treatment of ticagrelor combined with tirofiban significantly attenuated inflammation response and improved the prognosis of UA patients.

Clopidogrel underactivity is a common in patients with acute symptomatic severe carotid stenosis

BACKGROUND

Clopidogrel is commonly used for secondary stroke prevention in patients with large vessel stenosis. Reduced Clopidogrel high on treatment platelet reactivity (CR) can lead to Clopidogrel underactivity (CU) causing acute thrombosis. However, the prevalence of CU among patients with acute symptomatic carotid disease remains unknown. Therefore, we aimed to find the prevalence and identify the predictors for CU among patients with acutely symptomatic carotid stenosis.

PATIENTS AND METHODS

Over the span of 14 months, CR was measured at the time of endovascular procedure in all patients undergoing angiography and stenting because of acute symptomatic carotid stenosis. Only patients treated per institutional protocol with a combination of Clopidogrel and Aspirin were included. CR was measured with VerifyNowP2Y12 reaction units (PRU) and CU was defined as PRU > 208. Patients with CU were compared to those without CU.

RESULTS

Thirty-five patients were included (mean age 71.3 ± 10, 76% men) and twelve (34.3%, mean age 71.8 ± 8.4, 58% men) had CU at the time of endovascular intervention. On univariate analysis more severe carotid stenosis was seen in CU patients (92.6 ± 6.5% vs 81.6 ± 13.6%, p = 0.013) and percent stenosis was independently associated with CU on multivariate analysis (p = 0.023).

CONCLUSIONS

CU is present in 1 of every 3 patients with acutely symptomatic carotid disease. The current results suggest that CR testing should become part of routine care in patients with acutely symptomatic carotid disease.

Molecular imaging of carotid artery atherosclerosis with PET: a systematic review

PURPOSE

To conduct a systematic review of articles on PET imaging of carotid atherosclerosis with emphasis on clinical usefulness and comparison with other imaging modalities.

METHODS

Research articles reporting carotid artery PET imaging with different radiotracers until 30 November 2018 were systematically searched for in Medline/PubMed, Scopus, Embase, Google Scholar, and Cochrane Library. Duplicates were removed, and editorials, case studies, and investigations on feasibility or reproducibility of PET imaging and of patients with end-stage diseases or immunosuppressive medications were omitted. After quality assessment of included articles using Joanna Briggs Institute checklists, all eligible articles were reviewed.

RESULTS

Of 1718 primary hits, 53 studies comprising 4472 patients, aged 47-91 years (78.8% males), were included and grouped under the following headlines: diagnostic performance, risk factors, laboratory findings, imaging modalities, and treatment. ¹⁸F-fluorodeoxyglucose (FDG) (49/53) and ¹⁸F-sodium fluoride (NaF) (5/53) were the most utilized tracers to visualize carotid wall inflammation and microcalcification, respectively. Higher carotid FDG uptake was demonstrated in patients with than without symptomatic carotid atherosclerosis. Normal carotid arteries presented with the lowest FDG uptake. In symptomatic atherosclerosis, carotid arteries ipsilateral to a cerebrovascular event had higher FDG uptake than the contralateral carotid artery. FDG uptake was significantly associated with age, male gender, and body mass index in healthy individuals, and in addition with arterial hypertension, hypercholesterolemia, and diabetes mellitus in patients. Histological assessment indicated a strong correlation between microcalcification and NaF uptake in symptomatic patients. Histological evidence of calcification correlated inversely with FDG uptake, which was associated with increased macrophage and CD68 count, both accounting for increased local inflammatory response.

CONCLUSION

FDG-PET visualizes the inflammatory part of carotid atherosclerosis enabling risk stratification to a certain degree, whereas NaF-PET seems to indicate long-term consequences of ongoing inflammation by demonstrating microcalcification allowing discrimination of atherosclerotic from normal arteries and suggesting clinically significant carotid atherosclerosis.

Promoting vascular healing using nanofibrous ticagrelor-eluting stents

Objective

The current treatment of atherosclerotic coronary heart disease with limus-eluting stents can lead to incomplete endothelialization and substantial impairment of arterial healing relative to treatment with bare-metal stents. The sustained and local delivery of ticagrelor, a reversibly binding P2Y12 receptor inhibitor, using hybrid biodegradable nanofibers/stents, was developed to reduce neointimal formation and endothelial dysfunction.

Methods

In this investigation, a solution of ticagrelor, poly(D,L)-lactide-co-glycolide, and hexafluoro isopropanol was electrospun to fabricate ticagrelor-eluting nanofibrous drug-eluting stents. The in vitro and in vivo ticagrelor concentrations were measured using a high-performance liquid chromatography assay. The effectiveness of ticagrelor-eluting stents was examined relative to that of sirolimus-eluting stents.

Results

Adequate ticagrelor levels were detected for four weeks in vitro. Less HES5-positive labeling was found near the ticagrelor-eluting stented vessels (0.33±0.12) than close to the sirolimus-eluting stented vessels (0.57±0.15) (p<0.05). Four weeks after deployment, the ticagrelor-eluting stent also exhibited an up-regulated local expression of SOD1 in the stenting area (p<0.001). The ticagrelor-eluting stent substantially preserved endothelial function and re-endothelialization, minimized inflammatory responses, and inhibited neointimal hyperplasia.

Conclusion

Ticagrelor-eluting stents may provide an alternative route for treating patients at a high risk of bleeding to preserve endothelial recovery and to reduce smooth muscle proliferation.

Unraveling the Interaction of Aspirin, Ticagrelor, and Rosuvastatin on the Progression of Atherosclerosis and Inflammation in Diabetic Mice

PURPOSE

We explored the effects of rosuvastatin, aspirin, ticagrelor, and clopidogrel, alone or in combinations on the progression of atherosclerosis and inflammasome activation in diabetic mice. Statins and ticagrelor increase the production of 15-epi-lipoxin A₄ via cyclooxygenase-2. Aspirin alone increases 15-epi-lipoxin A₄, but when combined with statins, cyclooxygenase-2 is completely blocked.

METHODS

ApoE^-/-/db⁺/db⁺ double-knockout mice received rosuvastatin (5 mg/kg/day), aspirin (25 mg/kg/day), ticagrelor (300 mg/kg/day), clopidogrel (75 mg/kg/day), or their combination for 14 weeks. Serum 15-epi-lipoxin A₄ levels and aortic wall cholesterol content, IL-1β, IL-6, and TNF-α levels, and plaque area were assessed.

RESULTS

Aspirin, ticagrelor, and rosuvastatin increased 15-epi-lipoxin A₄ levels. The combination of rosuvastatin + ticagrelor provided an additive effect. Aspirin attenuated the effect of both ticagrelor and rosuvastatin. Aspirin, ticagrelor, and rosuvastatin reduced the area of the atherosclerotic plaque. The combination of ticagrelor + rosuvastatin provided additive effects. There was a negative interaction when aspirin was combined with ticagrelor or rosuvastatin. Aspirin, ticagrelor, and rosuvastatin decreased serum IL-1β and IL-6 levels. There was no interaction between aspirin and ticagrelor or aspirin and rosuvastatin, whereas combining rosuvastatin and ticagrelor provided an additive effect. Aspirin, ticagrelor, and rosuvastatin all decreased TNF-α levels. Aspirin attenuated the effect of both ticagrelor and rosuvastatin, and there was no additive effect of combining ticagrelor + rosuvastatin.

CONCLUSIONS

We found an intricate interaction between aspirin, ticagrelor, and rosuvastatin, as aspirin reduced both ticagrelor and rosuvastatin ability to ameliorate inflammation and atherosclerosis. In contrast, we found additive effects when ticagrelor and rosuvastatin were combined.

Ticagrelor, a P2Y12 antagonist, attenuates vascular dysfunction and inhibits atherogenesis in apolipoprotein-E-deficient mice

BACKGROUND AND AIMS

Ticagrelor reduces cardiovascular events in patients with acute coronary syndrome (ACS). Recent studies demonstrated the expression of P2Y12 on vascular cells including endothelial cells, as well as platelets, and suggested its contribution to atherogenesis. We investigated whether ticagrelor attenuates vascular dysfunction and inhibits atherogenesis in apolipoprotein E-deficient (apoe^-/-) mice.

METHODS

Eight-week-old male apoe^-/- mice were fed a western-type diet (WTD) supplemented with 0.1% ticagrelor (approximately 120 mg/kg/day). Non-treated animals on WTD served as control. Atherosclerotic lesions were examined by en-face Sudan IV staining, histological analyses, quantitative RT-PCR analysis, and western blotting. Endothelial function was analyzed by acetylcholine-dependent vasodilation using aortic rings. Human umbilical vein endothelial cells (HUVEC) were used for in vitro experiments.

RESULTS

Ticagrelor treatment for 20 weeks attenuated atherosclerotic lesion progression in the aortic arch compared with control (p < 0.05). Ticagrelor administration for 8 weeks attenuated endothelial dysfunction (p < 0.01). Ticagrelor reduced the expression of inflammatory molecules such as vascular cell adhesion molecule-1, macrophage accumulation, and lipid deposition. Ticagrelor decreased the phosphorylation of JNK in the aorta compared with control (p < 0.05). Ticagrelor and a JNK inhibitor ameliorated impairment of endothelium-dependent vasodilation by adenosine diphosphate (ADP) in wild-type mouse aortic segments. Furthermore, ticagrelor inhibited the expression of inflammatory molecules which were promoted by ADP in HUVEC (p < 0.001). Ticagrelor also inhibited ADP-induced JNK activation in HUVEC (p < 0.05).

CONCLUSIONS

Ticagrelor attenuated vascular dysfunction and atherogenesis through the inhibition of inflammatory activation of endothelial cells. These effects might be a potential mechanism by which ticagrelor decreases cardiovascular events in patients with ACS.

Comparison of Ticagrelor Versus Prasugrel for Inflammation, Vascular Function, and Circulating Endothelial Progenitor Cells in Diabetic Patients With Non-ST-Segment Elevation Acute Coronary Syndrome Requiring Coronary Stenting: A Prospective, Randomized, Crossover Trial

OBJECTIVES

This study compared adenosine-associated pleiotropic effects of the 2 P2Y₁₂ receptor antagonists on vascular function, systemic inflammation, and circulating endothelial progenitor cells (EPCs).

BACKGROUND

Both ticagrelor and prasugrel have potent antiplatelet effects. However, only ticagrelor inhibits cellular uptake of adenosine.

METHODS

Using a randomized, crossover design with 10-week follow-up ticagrelor or prasugrel was administered to type 2 diabetic patients with non-ST-segment elevation acute coronary syndrome requiring stent implantation. A total of 62 patients underwent randomization in a 1:1 ratio to receive ticagrelor or prasugrel for 5 weeks followed by a direct cross over to the alternative treatment for 5 additional weeks. Brachial artery flow-mediated dilation, inflammatory markers, and number of circulating EPCs were compared.

RESULTS

Improvement in brachial artery flow-mediated dilation was greater in the ticagrelor group (0.15 ± 0.19 mm vs. -0.03 ± 0.18 mm; p < 0.001). Moreover, ticagrelor compared with prasugrel decreased interleukin 6 (-0.58 ± 0.43 pg/ml vs. -0.05 ± 0.24 pg/ml; p < 0.001), tumor necrosis factor alpha (-5.62 ± 4.40 pg/ml vs. -0.42 ± 2.64 pg/ml; p < 0.001), and increased adiponectin (2.31 ± 2.00 μg/ml vs. 0.08 ± 1.50 μg/ml; p < 0.001) during 10-week follow-up. Other inflammatory cytokines like high-sensitivity C-reactive protein and soluble vascular cell adhesion molecule-1 were decreased in both groups. Ticagrelor compared with prasugrel significantly increased absolute numbers of circulating EPCs CD34+/KDR+ (42.5 ± 37.8 per μl vs. -28.2 ± 23.7 per μl; p < 0.001), CD34+/CD117+ (51.9 ± 77.2 per μl vs. -66.3 ± 45.2 per μl; p < 0.001), and CD34+/CD133+ (55.2 ± 69.2 per μl vs. -28.0 ± 34.1 per μl; p < 0.001).

CONCLUSIONS

Compared with prasugrel, ticagrelor significantly decreased inflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha and increased circulating EPCs, contributing to improved arterial endothelial function in diabetic non-ST-segment elevation acute coronary syndrome patients. Thus, data support that pleiotropic effects of ticagrelor beyond its potent antiplatelet effects could contribute to additional clinical benefits. (Comparison of Ticagrelor vs. Prasugrel on Inflammation, Arterial Stiffness, Endothelial Function, and Circulating Endothelial Progenitor Cells in Diabetic Patients With Non-ST Elevation Acute Coronary Syndrome [NSTE-ACS] Requiring Coronary Stenting; NCT02487732).

Comparison of the 9-month intra-stent conditions and 2-year clinical outcomes after Resolute zotarolimus-eluting stent implantation between 3-month and standard dual antiplatelet therapy

BACKGROUND

The use of short-duration dual antiplatelet therapy (DAPT) remains controversial. To investigate efficacy and safety of short-duration DAPT, we performed a detailed comparison of intra-stent conditions by optical coherence tomography (OCT) after second-generation drug-eluting stent implantation with short-term and standard DAPT.

METHODS AND RESULTS

Eighty-two consecutive patients with stable angina pectoris who received Resolute zotarolimus-eluting stents (R-ZESs; Medtronic Cardiovascular, Santa Rosa, CA, USA) were enrolled. Patients were assigned to 3-month (3M group: 41 patients) and standard (standard group: 41 patients) DAPT. In the 3M group, clopidogrel was discontinued 3 months after stent implantation. In the standard group, DAPT was maintained until follow-up OCT. At 9 months, neointimal proliferation was significantly larger in the 3M group, but there were no significant between-group differences in the proportion of uncovered and malapposed strut. The prevalence of abnormal intra-stent tissue (AIT) at 9 months was equivalent between groups. A multiple regression analysis revealed malapposition at 9 months as the strongest independent predictor of AIT at 9 months, and the prevalence of AIT was not associated with DAPT duration. Over 2 years, cardiac events were equal between groups; however, major bleeding was higher tendency in the standard group than in the 3M group.

CONCLUSION

This OCT study indicated that reducing DAPT's duration may provide acceptable arterial healing in patients with implanted R-ZESs.

Effects of ticagrelor on neointimal hyperplasia and endothelial function, compared with clopidogrel and prasugrel, in a porcine coronary stent restenosis model

BACKGROUND

Several investigations have been conducted to evaluate the off-target effects of ticagrelor. The aim of the present study was to evaluate the off-target effects of ticagrelor such as neointimal formation and endothelial function after drug-eluting stent implantation in a porcine restenosis model.

METHODS

A total of 30 pigs were randomly allocated based on the following P2Y₁₂ inhibitor: (1) clopidogrel 300mg loading plus 75mg maintenance (n=10); (2) prasugrel 60mg loading plus 10mg maintenance (n=10); (3) ticagrelor 180mg loading plus 180mg maintenance (n=10). In each group, zotarolimus-eluting stents were implanted in the proximal portion of the left anterior descending artery and left circumflex artery. One month after stenting, the animals underwent follow-up angiography, endothelial function assessment, optical coherence tomography (OCT) and histopathological analysis.

RESULTS

Regarding vasomotor responses to acetylcholine infusion, there were significant vasoconstrictions to maximal acetylcholine infusion in the clopidogrel and prasugrel group compared with those in the ticagrelor group. The mean neointimal area were significantly lower in the ticagrelor group (1.0±0.3 by OCT, 0.9±0.3 by histology), than in the clopidogrel (1.8±0.7, p=0.003, 1.6±0.8, p=0.030) and prasugrel (1.8±0.5, p=0.001, 1.5±0.5, p=0.019) groups. Percentages of moderate to dense peri-strut inflammatory cell infiltration were significantly lower in the ticagrelor group (9.0%) compared with the clopidogrel (17.3%, p<0.001) and prasugrel groups (15.7%, p=0.002). There were no significant differences in all findings between clopidogrel and prasugrel groups.

CONCLUSIONS

Compared to clopidogrel and prasugrel, ticagrelor reduced neointimal formation, endothelial dysfunction, and peri-strut inflammation.

Similar Impact of Clopidogrel or Ticagrelor on Carotid Atherosclerotic Plaque Inflammation

BACKGROUND

Platelets play an important role in inflammation. Inhibitors of the P2Y₁₂ receptor, which is involved in platelet activation, may have a direct effect on carotid atherosclerotic plaque inflammation.

HYPOTHESIS

We compared the effects of clopidogrel and ticagrelor therapy for carotid atherosclerotic plaque inflammation using ¹⁸ F-fluorodeoxyglucose ( ¹⁸ FDG) positron emission tomography (PET) imaging.

METHODS

Fifty patients with acute coronary syndrome and ≥1 ¹⁸ FDG uptake in the carotid artery (target-to-background ratio [TBR] ≥1.6) were randomized to either clopidogrel or ticagrelor groups. Of these, 46 completed PET examinations at baseline and at 6 months. The primary endpoint was the percent change in TBR of the index vessel at the most diseased segment (MDS).

RESULTS

Baseline characteristics were similar between the 2 groups. At 6-month follow-up, low-density lipoprotein cholesterol and C-reactive protein significantly decreased in both groups (P < 0.001). The TBR of the index vessel and aorta significantly decreased in both groups (P < 0.01). The percent change in the MDS TBR of the index vessel was numerically but not significantly lower in the clopidogrel group than in the ticagrelor group (-9.5 ± 14.6% vs -13.5 ± 19.3%; P = 0.427). Likewise, the percent change in the whole-vessel TBR of the index vessel was not different between the 2 groups (P = 0.166). Similar findings were observed for changes in the MDS TBR (P = 0.412) or whole-vessel TBR of the aorta (P = 0.363).

CONCLUSIONS

Carotid atherosclerotic plaque inflammation significantly decreases to a similar degree following 6 months of either clopidogrel or ticagrelor treatment.