Small Interfering Ribonucleic Acid as Lipid-Lowering Therapy: Inclisiran in Focus.

The PCSK9 (Proprotein Convertase Subtilisin/Kexin type 9) enzyme interferes with the metabolism of low-density lipoprotein (LDL) cholesterol. Inhibition of PCSK9 results in lower LDL cholesterol levels, which can be achieved by different molecular pathways. Monoclonal antibodies targeting circulating PCSK9 have shown strong and persistent effects on lowering the LDL cholesterol level, while reducing the risk of future cardiovascular events. However, this therapy requires once- or twice-monthly administration in the form of subcutaneous injection. This dosing regimen might impact the therapy adherence in cardiovascular patients who often require multiple drugs with different dosing intervals. Small interfering ribonucleic acid (siRNA) represents a promising therapy approach for patients with elevated LDL cholesterol level despite optimized background statin therapy. Inclisiran is a synthesized siRNA which inhibits PCSK9 synthesis in the liver and provides sustained and durable lowering of LDL cholesterol with twice-yearly application and a good tolerability profile. Herein, we present an overview of the current available data and critical review of the major clinical trials which assessed safety and efficacy of inclisiran in different groups of patients with elevated LDL cholesterol level.

Anti-Inflammatory Therapy in Coronary Artery Disease: Where Do We Stand?

Inflammation plays an important role in all stages of atherosclerosis - from endothelial dysfunction, to formation of fatty streaks and atherosclerotic plaque, and its progression to serious complications, such as atherosclerotic plaque rupture. Although dyslipidemia is a key driver of atherosclerosis, pathogenesis of atherosclerosis is now considered interplay between cholesterol and inflammation, with the significant role of the immune system and immune cells. Despite modern therapeutic approaches in primary and secondary cardiovascular prevention, cardiovascular diseases remain the leading cause of mortality worldwide. In order to reduce residual cardiovascular risk, despite the guidelines-guided optimal medical therapy, novel therapeutic strategies are needed for prevention and management of coronary artery disease. One of the innovative and promising approaches in atherosclerotic cardiovascular disease might be inflammation-targeted therapy. Numerous experimental and clinical studies are seeking into metabolic pathways underlying atherosclerosis, in order to find the most suitable pathway and inflammatory marker/s that should be the target for anti-inflammatory therapy. Many anti-inflammatory drugs have been tested, from the well-known broad range anti-inflammatory agents, such as colchicine, allopurinol and methotrexate, to targeted monoclonal antibodies specifically inhibiting a molecule included in inflammatory pathway, such as canakinumab and tocilizumab. To date, there are no approved anti-inflammatory agents specifically indicated for silencing inflammation in patients with coronary artery disease. The most promising results came from the studies which tested colchicine, and studies where the inflammatory-target was NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome/interleukin-1 beta (IL-1 ß )/interleukin-6 (IL-6)/C-reactive protein (CRP) pathway. A growing body of evidence, along with the ongoing clinical studies, suggest that the anti-inflammatory therapy might become an additional strategy in treating atherosclerotic cardiovascular disease. Herein we present an overview of the role of inflammation in atherosclerosis, the most important inflammatory markers chosen as targets of anti-inflammatory therapy, along with the critical review of the major clinical trials which tested non-targeted and targeted anti-inflammatory drugs in patients with atherosclerotic cardiovascular disease.

Involvement of PI3K, Akt and RhoA in Oestradiol Regulation of Cardiac iNOS Expression.

BACKGROUND: Oestradiol is an important regulatory factor with several positive effects on the cardiovascular (CV) system. We evaluated the molecular mechanism of the in vivo effects of oestradiol on the regulation of cardiac inducible nitric oxide (NO) synthase (iNOS) expression and activity. METHODS: Male Wistar rats were treated with oestradiol (40 mg/kg, intraperitoneally) and after 24 h the animals were sacrificed. The concentrations of NO and L-Arginine (L-Arg) were determined spectrophotometrically. For protein expressions of iNOS, p65 subunit of nuclear factor-κB (NFκB-p65), Ras homolog gene family-member A (RhoA), angiotensin II receptor type 1 (AT1R), insulin receptor substrate 1 (IRS-1), p85, p110 and protein kinase B (Akt), Western blot method was used. Coimmunoprecipitation was used for measuring the association of IRS-1 with the p85 subunit of phosphatidylinositol- 3-kinase (PI3K). The expression of iNOS messenger ribonucleic acid (mRNA) was measured with the quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of the tissue was used to detect localization and expression of iNOS in heart tissue. RESULTS: Oestradiol treatment reduced L-Arg concentration (p<0.01), iNOS mRNA (p<0.01) and protein (p<0.001) expression, level of RhoA (p<0.05) and AT1R (p<0.001) protein. In contrast, plasma NO (p<0.05), Akt phosphorylation at Thr308 (p<0.05) and protein level of p85 (p<0.001) increased after oestradiol treatment. CONCLUSION: Our results suggest that oestradiol in vivo regulates cardiac iNOS expression via the PI3K/Akt signaling pathway, through attenuation of RhoA and AT1R.

Hepatoprotective effect of fullerenol/doxorubicin nanocomposite in acute treatment of healthy rats.

In our recent studies we have designed fullerenol/doxorubicin nanocomposite (FNP/DOX) as the new drug nanocarrier. This research has demonstrated that this novel nanocomposite has had better implications on the liver tissue in vivo (Wistar rats treated intraperitoneally), than treatment based only on DOX. FNP/DOX has been characterised by DLS, TEM and AFM measurements which have shown that DOX loaded onto FNP did not influence fullerenol nanoparticle's size. FNP/DOX affected oxidative status in blood causing a significant decrease of catalase and SOD activity in comparison to DOX, implicating the reduction in oxidative stress. qRT-PCR results on the mRNA level of antioxidative enzymes (catalase and MnSOD) revealed that the effect of oxidative stress is significantly reduced by the treatment with FNP/DOX (p < .05). The ultrastructural analysis of the liver tissue has revealed that FNP/DOX nanocomposite generated considerably less damage in the liver tissue, than DOX applied at the same dose. Hence, our results have indicated that FNP, within FNP/DOX nanocomposite, exhibits protective effects to the liver tissue of the healthy rats.

Suppression of methionine-induced colon injury of young rats by cysteine and N-acetyl-L-cysteine.

Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxidative stress in the gut. The production of free radicals is important in the colon damage caused by methionine. This study aimed at evaluating the effect of the use of L-cysteine and N-acetyl-L-cysteine on the colon morphometry of young rats treated with methionine. A total number of 32 male rats were distributed in a randomized experimental design in 4 groups: control group treated with saline; methionine group; cysteine + methionine group, and N-acetyl-L-cysteine + methionine group. After 21 days of treatment, rats were sacrificed and the colon samples were taken for histological and biochemical analysis. Methionine load increased depth of crypts, the lamina muscularis mucosae thickness, the mucosal height, and the number of cells in lamina propria (p < 0.01). Combination of methionine with L-cysteine (C group) and with N-acetyl-L-cysteine (N group) reversed methionine effects. Methionine treatment increased the GPx activity and MDA concentration, while L-cysteine and N-acetyl-L-cysteine increased the catalase activity compared to methionine group. It was concluded that the use of L-cysteine and N-acetyl-L-cysteine was beneficial to decrease intestinal mucosal height and oxidative damage when methionine was used in combination with them.

Fullerenol/doxorubicin nanocomposite mitigates acute oxidative stress and modulates apoptosis in myocardial tissue.

Fullerenol (C60(OH)24) is present in aqueous solutions in the form of polyanion nanoparticles with particles' size distribution within the range from 15 to 42 nm. In this research it is assumed that these features could enable fullerenol nanoparticles (FNPs) to bind positively charged molecules like doxorubicin (DOX) and serve as drug carriers. Considering this, fullerenol/doxorubicin nanocomposite (FNP/DOX) is formed and characterized by ultra-performance liquid chromatography tandem mass spectrometry, dynamic light scattering, atomic force microscopy and transmission electron microscopy. Measurements have shown that DOX did not significantly affect particle size (23 nm). It is also assumed that FNP/DOX could reduce the acute cardiotoxic effects of DOX in vivo (Wistar rats treated i.p.). In this study, quantitative real time polymerase chain reaction results have shown that treatment with DOX alone caused significant increase in mRNA levels of catalase (p < 0.05) enzyme indicating the presence of oxidative stress. This effect is significantly reduced by the treatment with FNP/DOX (p < 0.05). Furthermore, mRNA levels of antiapoptotic enzyme (Bcl-2) are significantly increased (p < 0.05) in all treated groups, particularly where FNP/DOX was applied, suggesting cell resistance to apoptosis. Moreover, ultrastructural analysis has shown the absence of myelin figures within the mitochondria in the heart tissue with FNP/DOX treatment, indicating reduction of oxidative stress. Hence, our results have implied that FNP/DOX is generally less harmful to the heart compared to DOX.

Coronary thrombi neovascularization in patients with ST-elevation myocardial infarction - clinical and angiographic implications.

INTRODUCTION: Coronary artery thrombosis in ST-elevation myocardial infarction (STEMI) is a dynamic process often preceded by episodes of silent plaque rupture and subocclusive thrombosis. Thrombus organization is achieved by ingrowth of endothelial and smooth muscle cells. Clinical significance and impact of thrombus neovascularization on primary percutaneous coronary intervention (pPCI) outcome remain unclear. Therefore we investigated composition and neovascularization of thrombi aspirated during pPCI and their association with clinical and angiographic parameters of STEMI patients. METHODS: Aspirated thrombi retrieved from 84 STEMI patients were classified as fresh (<1 day), lytic (1-5 days) or organized (>5 days). Thrombus neovascularization was evaluated immunohistochemically using CD34, CD31 and VEGF antibodies. CD34 and CD31 immunopositive (CD34/CD31+) cells were organized as single, clusters and microvessels. VEGF positivity was graded as low or high, based on thrombus surface immunopositive area. RESULTS: CD34/CD31+ cells were present in 67% of all aspirated thrombi. Thrombus CD34/CD31 positivity was associated with previous history of angina pectoris (χ(2)=6.142, p=0.013) and lower myocardial blush grade (MBG<3, χ(2)=12.602, p<0.001). Organization of CD34/CD31+ cells showed inverse association with the extent of VEGF positivity (χ(2)=10.607, p=0.005). Fresh thrombi were associated with shorter ischemic time (U=237.5, p=0.002) and MBG 3 (χ(2)=6.379, p=0.012). CONCLUSIONS: Older thrombus age and neovascularization are associated with suboptimal myocardial perfusion in STEMI patients. Thrombus VEGF expression is inversely associated with degree of CD34+ cell organization. Therefore, neovascularization of aspirated thrombi may indicate the duration of thrombosis, coronary microcirculation status and outcome in STEMI patients.

Effects of fullerenol C60(OH)24 nanoparticles on a single-dose doxorubicin-induced cardiotoxicity in pigs: an ultrastructural study.

Cardioprotective effects of fullerenol C60(OH)24 nanoparticles (FNP) were investigated in pigs after a single treatment with doxorubicin (DOX). Semithin and ultrathin sections of myocardial tissue routinely prepared for transmission electron microscopy were analyzed. Extensive intracellular damage was confirmed in cardiomyocytes of DOX-treated animals. By means of ultrastructural analysis, a certain degree of parenchymal degeneration was confirmed even in animals treated with FNP alone, including both the oral and the intraperitoneal application of the substance. The cardioprotective effects of FNP in animals previously treated with DOX were recognized to a certain extent, but were not fully confirmed at the ultrastructural level. Nevertheless, the myocardial morphology of DOX-treated animals improved after the admission of FNP. Irregular orientation of myofibrils, myofibrillar disruption, intracellular edema, and vacuolization were reduced, but not completely eliminated. Reduction of these cellular alterations was achieved if FNP was applied orally 6 h prior to DOX treatment in a dose of 18 mg/kg. However, numerous defects, including the inner mitochondrial membrane and the plasma membrane disruption of certain cells persisted. In FNP/DOX-treated animals, the presence of multinuclear cells with mitosis-like figures resembling metaphase or anaphase were observed, indicating that DOX and FNP could have a complex influence on the cell cycle of cardiomyocytes. Based on this experiment, further careful increase in dosage may be advised to enhance FNP-induced cardioprotection. These investigations should, however, always be combined with ultrastructural analysis. The FNP/DOX interaction is an excellent model for the investigation of cardiomyocyte cell death and cell cycle mechanisms.

The internal thoracic artery as a transitional type of artery: a morphological and morphometric study.

Coronary artery by-pass grafting (CABG) with arterial grafts is widely accepted as the procedure of choice in the treatment of coronary ischemic disease. It brings back focus on morphological studies of arteries used as conduits in this procedure. One of the most frequently used CABG grafts is the internal thoracic artery with an excellent graft prognosis and patency rate. The aim of the study was a detailed morphological and morphometric description of the internal thoracic artery with an emphasis on its basic histological structure and its changes in aging and atherosclerosis. Therefore, 42 full-length arteries were obtained during forensic autopsies from 27 persons, aged between 20 and 81 years, who had died from non-vascular causes. The arteries were classified into three different age groups. Analysis of the serial arterial segments has shown that the internal thoracic artery is an artery of the transitional type whose media is organized into two layers: the internal, muscular layer and the external layer with spirally oriented elastic lamellae and smooth muscle cells in between. The number of elastic lamellae progressively decreases throughout the length of the examined arteries. As opposed to previous assumptions, we have proven that the grade of atherosclerosis is independent of the number of elastic lamellae in the external media. Perfectly formed elastic lamellae are not a persistent feature of the internal thoracic artery, as previously claimed. We have confirmed that the thickness of elastic lamellae decreases, while the number and the size of their fenestrations steadily increase with aging.