Celecoxib combined with atorvastatin prevents progression of atherosclerosis

Association of pro-inflammatory cytokines, inflammatory proteins with atherosclerosis index in obese male subjects

OBJECTIVES

Investigation the association of pro-inflammatory markers interleukin (IL)-1β and IL- 10 expression, serum levels of C-reactive protein (CRP), cyclooxygenase-2 (COX2), High-density lipoprotein (HDL), Apolipoprotein A1 (ApoA1), and ATP Binding Cassette Subfamily A Member 1 (ABCA1) inflammatory proteins with atherosclerosis index (homocysteine) in normal-weight and obese male subjects.

METHODS

59 males including 30 obese (Body mass index (BMI) of ≥30 kg/m²) and 29 normal-weight (BMI of 18.5-24.9 kg/m²) were joined to this study. Plasma levels of IL-1β and IL-10 (pg/mL), CRP (pg/mL), COX-2 (ng/mL), APOA1 (mg/dL), ABCA1 (ng/mL), HDL, Cholesterol, and Triglyceride (TG) (mg/dL), and homocysteine (µmol/L) was measured. Association of these biomarkers with homocysteine was determined.

RESULTS

Obese subjects had higher serum levels of IL10, IL1β, CRP, COX-2, TG, and cholesterol concentrations (all p<0.05 except IL-10 and cholesterol) and low levels of HDL, APOA1, and ABCA1 (non-significant differences) in comparison to normal-weight group. Homocysteine levels were high in obese men with no significant differences between the two groups. In obese subjects, homocysteine had a significant inverse correlation with APOA1, ABCA1, and HDL, and a strong and moderate positive correlation was found with CRP and TG levels, respectively.

CONCLUSIONS

High level of homocysteine and its correlation with inflammation proteins and markers in obese subjects appear to be contributed with atherosclerosis development.

Involvement of Fatty Acids and Their Metabolites in the Development of Inflammation in Atherosclerosis

Despite all the advances of modern medicine, atherosclerosis continues to be one of the most important medical and social problems. Atherosclerosis is the cause of several cardiovascular diseases, which are associated with high rates of disability and mortality. The development of atherosclerosis is associated with the accumulation of lipids in the arterial intima and the disruption of mechanisms that maintain the balance between the development and resolution of inflammation. Fatty acids are involved in many mechanisms of inflammation development and maintenance. Endothelial cells demonstrate multiple cross-linkages between lipid metabolism and innate immunity. In addition, these processes are linked to hemodynamics and the function of other cells in the vascular wall, highlighting the central role of the endothelium in vascular biology.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

Ameliorative effects of hempseed (Cannabis sativa) against hypercholesterolemia associated cardiovascular changes

BACKGROUND AND AIM

Hypercholesterolemia (HC) is a major risk factor for cardiovascular (CV) diseases, that are the major cause of mortality worldwide. Free radicals mediated oxidative stress is a critical player in HC-associated pathophysiological insults including atherosclerosis. Unwanted side effects associated with statins, COX-2 inhibitors, and other synthetic drugs limit their use. Thus, modulation of oxidative stress during HC using green pharmaceuticals seems an appropriate approach against deleterious CV consequences without noticeable side-effect. In this regard, owing to an abundance of proteins, fiber and optimal ratios of omega 6 PUFA: omega-3 PUFA in Hempseed (HS), we aim to exploit its anti-inflammatory and antioxidant properties to ameliorate HC- associated CV effects.

METHODS AND RESULTS

Comparing the antioxidant capacity of protein and lipid fractions of HS using ABTS and DPPH assays, HS was supplemented to high-fat diets (HFD) induced hypercholesterolemic wistar rats. After treatment schedules, lipid profiles, histological and ultrastructural investigations, gene and protein expressions of inflammatory markers, markers of oxidative stress were studied and correlated with biophysical parameters such as ECG and impedance/conductance across the aorta. HS demonstrating in vitro free radical scavenging activity, ameliorated the signs of HC as seen with improved lipid profiles, aortic tissue damage and ECG patterns compared to HFD groups. HS administration also relieved the COX-2 mediated inflammation, which correlated well with the improved redox status in the tissue.

CONCLUSIONS

Current study evidently demonstrates that the anti-hypercholesterolemic effects of HS are mediated through redox-sensitive modulation of inflammatory pathways.

The Dualistic Effect of COX-2-Mediated Signaling in Obesity and Insulin Resistance

Obesity and insulin resistance are two major risk factors for the development of metabolic syndrome, type 2 diabetes and associated cardiovascular diseases (CVDs). Cyclooxygenase (COX), a rate-limiting enzyme responsible for the biosynthesis of prostaglandins (PGs), exists in two isoforms: COX-1, the constitutive form, and COX-2, mainly the inducible form. COX-2 is the key enzyme in eicosanoid metabolism that converts eicosanoids into a number of PGs, including PGD₂, PGE₂, PGF_2α, and prostacyclin (PGI₂), all of which exert diverse hormone-like effects via autocrine or paracrine mechanisms. The COX-2 gene and immunoreactive proteins have been documented to be highly expressed and elevated in adipose tissue (AT) under morbid obesity conditions. On the other hand, the environmental stress-induced expression and constitutive over-expression of COX-2 have been reported to play distinctive roles under different pathological and physiological conditions; i.e., over-expression of the COX-2 gene in white AT (WAT) has been shown to induce de novo brown AT (BAT) recruitment in WAT and then facilitate systemic energy expenditure to protect mice against high-fat diet-induced obesity. Hepatic COX-2 expression was found to protect against diet-induced steatosis, obesity, and insulin resistance. However, COX-2 activation in the epidydimal AT is strongly correlated with the development of AT inflammation, insulin resistance, and fatty liver in high-fat-diet-induced obese rats. This review will provide updated information regarding the role of COX-2-derived signals in the regulation of energy metabolism and the pathogenesis of obesity and MS.

Celecoxib aggravates atherogenesis and upregulates leukotrienes in ApoE-/- mice and lipopolysaccharide-stimulated RAW264.7 macrophages

BACKGROUND AND AIMS

COX-2-selective inhibitors have been associated with an increased risk of cardiovascular complications, and their impact on atherosclerosis (AS) remains controversial. The proinflammatory COX-2 and 5-LO pathways both play essential roles in AS and related cardiovascular diseases. Previous clinical studies have provided evidence of the ability of COX-2-selective inhibitors to shunt AA metabolism from the COX-2 pathway to the 5-LO pathway. In this study, the effects of celecoxib, a selective COX-2 inhibitor, on AS and the COX-2 and 5-LO pathways were investigated in vivo and in vitro.

METHODS

Male ApoE^-/- mice fed a western-type diet for 18 weeks and cultured mouse RAW264.7 macrophages stimulated with 1 μg/mL LPS for 24 h were used in this study.

RESULTS

In ApoE^-/- mice, intragastric administration of celecoxib (80 mg/kg/d) for 18 weeks significantly increased aortic atherosclerotic lesion area but had no effect on hyperlipidemia. In addition, celecoxib significantly lowered TNF-α and PGE₂ levels but increased both LTB₄ and CysLTs levels in aortic tissues. In LPS-stimulated RAW264.7 macrophages, pretreatment with 8 μmol/L celecoxib for 1 h significantly lowered the TNF-α, NO, and PGE₂ levels but increased the LTB₄ and CysLTs levels. Celecoxib also decreased the protein and mRNA expression of COX-2 but increased the expression of 5-LO and LTC₄S in both ApoE^-/- mouse aortic tissues and LPS-stimulated RAW264.7 macrophages.

CONCLUSION

The COX-2-selective inhibitor celecoxib can aggravate atherogenesis, an effect that may be related to upregulation of LTs via a 5-LO pathway shunt.

Up-regulation of COX-2 and mPGES-1 by 27-hydroxycholesterol and 4-hydroxynonenal: A crucial role in atherosclerotic plaque instability

Atherosclerosis is currently understood to be mainly the consequence of a complicated inflammatory process at the different stages of plaque development. Among the several inflammatory molecules involved, up-regulation of the functional cyclooxygenase 2/membrane-bound prostaglandin E synthase 1 (COX-2/mPGES-1) axis plays a key role in plaque development. Excessive production of oxidized lipids, following low-density lipoprotein (LDL) oxidation, is a characteristic feature of atherosclerosis. Among the oxidized lipids of LDLs, the oxysterol 27-hydroxycholesterol (27-OH) and the aldehyde 4-hydroxynonenal (HNE) substantially accumulate in the atherosclerotic plaque, contributing to its progression and instability through a variety of processes. This study shows that 27-OH and HNE promote up-regulation of both the inducible enzymes COX-2 and mPGES-1, leading to increased production of prostaglandin (PG) E₂ and inducible nitric oxide synthase, and the subsequent release of nitric oxide in human promonocytic U937 cells. The study also examined the potential involvement of the functionally coupled COX-2/mPGES-1 in enhancing the production of certain pro-inflammatory cytokines and of matrix metalloproteinase 9 by U937 cells. This enhancement is presumably due to the induction of PGE₂ synthesis, as a result of the up-regulation of the COX-2/mPGES-1, stimulated by the two oxidized lipids, 27-OH and HNE. Induction of PGE₂ synthesis might thus be a mechanism of plaque instability and eventual rupture, contributing to matrix metalloproteinase production by activated macrophages.

PDGF signaling pathway in hepatic fibrosis pathogenesis and therapeutics (Review)

The platelet‑derived growth factor (PDFG) signaling pathway exerts persistent activation in response to a variety of stimuli and facilitates the progression of hepatic fibrosis. Since this pathway modulates a broad spectrum of cellular processes, including cell growth, differentiation, inflammation and carcinogenesis, it has emerged as a therapeutic target for hepatic fibrosis and liver‑associated disorders. The present review exhibits the current knowledge of the role of the PDGF signaling pathway and its pathological profiles in hepatic fibrosis, and assesses the potential of inhibitors which have been investigated in the experimental hepatic fibrosis model, in addition to the clinical challenges associated with these inhibitors.

Dietary Silicon Deficiency Does Not Exacerbate Diet-Induced Fatty Lesions in Female ApoE Knockout Mice

BACKGROUND

Dietary silicon has been positively linked with vascular health and protection against atherosclerotic plaque formation, but the mechanism of action is unclear.

OBJECTIVES

We investigated the effect of dietary silicon on 1) serum and aorta silicon concentrations, 2) the development of aortic lesions and serum lipid concentrations, and 3) the structural and biomechanic properties of the aorta.

METHODS

Two studies, of the same design, were conducted to address the above objectives. Female mice, lacking the apolipoprotein E (apoE) gene, and therefore susceptible to atherosclerosis, were separated into 3 groups of 10-15 mice, each exposed to a high-fat diet (21% wt milk fat and 1.5% wt cholesterol) but with differing concentrations of dietary silicon, namely: silicon-deprived (-Si; <3-μg silicon/g feed), silicon-replete in feed (+Si-feed; 100-μg silicon/g feed), and silicon-replete in drinking water (+Si-water; 115-μg silicon/mL) for 15-19 wk. Silicon supplementation was in the form of sodium metasilicate (feed) or monomethylsilanetriol (drinking water).

RESULTS

The serum silicon concentration in the -Si group was significantly lower than in the +Si-feed (by up to 78%; P < 0.003) and the +Si-water (by up to 84%; P < 0.006) groups. The aorta silicon concentration was also lower in the -Si group than in the +Si-feed group (by 65%; P = 0.025), but not compared with the +Si-water group. There were no differences in serum and aorta silicon concentrations between the silicon-replete groups. Body weights, tissue wet weights at necropsy, and structural, biomechanic, and morphologic properties of the aorta were not affected by dietary silicon; nor were the development of fatty lesions and serum lipid concentrations.

CONCLUSIONS

These findings suggest that dietary silicon has no effect on atherosclerosis development and vascular health in the apoE mouse model of diet-induced atherosclerosis, contrary to the reported findings in the cholesterol-fed rabbit model.

The role of prostaglandin E2 in human vascular inflammation

Prostaglandins (PG) are the product of a cascade of enzymes such as cyclooxygenases and PG synthases. Among PG, PGE2 is produced by 3 isoforms of PGE synthase (PGES) and through activation of its cognate receptors (EP1-4), this PG is involved in the pathophysiology of vascular diseases. Some anti-inflammatory drugs (e.g. glucocorticoids, nonsteroidal anti-inflammatory drugs) interfere with its metabolism or effects. Vascular cells can initiate many of the responses associated with inflammation. In human vascular tissue, PGE2 is involved in many physiological processes, such as increasing vascular permeability, cell proliferation, cell migration and control of vascular smooth muscle tone. PGE2 has been shown to contribute to the pathogenesis of atherosclerosis, abdominal aortic aneurysm but also in physiologic/adaptive processes such as angiogenesis. Understanding the roles of PGE2 and its cognate receptors in vascular diseases could help to identify diagnostic and prognostic biomarkers. In addition, from these recent studies new promising therapeutic approaches like mPGES-1 inhibition and/or EP4-antagonism should be investigated.

Atherosclerosis and rheumatoid arthritis: more than a simple association

In the last decades a large amount of evidence linked rheumatoid arthritis (RA) to atherosclerosis. In fact, RA patients have an increased risk of cardiovascular events that is not fully explained by other classic cardiovascular risk factors. RA and atherosclerosis may share several common pathomechanisms and inflammation undoubtedly plays a primary role. The proinflammatory cytokines such as tumor necrosis factor alpha and interleukin-6, involved in the pathogenesis of RA, are also independently predictive of subsequent cardiovascular disease (CVD). In RA, inflammation alters HDL constituents and the concentration of LDL and HDL, thus facilitating atherosclerosis and CVD events. On the other hand, also the increase of oxidative processes, frequently observed in RA, induces atherosclerosis. Interestingly, some genetic polymorphisms associated with RA occurrence enhance atherosclerosis, however, other polymorphisms associated with RA susceptibility do not increase CVD risk. Several other mechanisms may influence atherosclerotic processes in RA. Moreover, atherosclerosis may be directly mediated also by underlying autoimmune processes, and indirectly by the occurrence of metabolic syndrome and impaired physical activity. Finally, the effects of RA therapies on cardiovascular system in general and on atherosclerosis in particular are really wide and different. However, the starting point of every RA treatment is that disease control, or better remission, is the best way we have for the reduction of CVD occurrence.

Statin treatment is associated with reduced toll-like receptor 4 immunohistochemical expression on carotid atherosclerotic plaques: a novel effect of statins

Toll-like receptor 4 (TLR4) has been recently implicated in inflammatory pathways involved in carotid plaque destabilization. Given that statins have plaque stabilization and inflammation reduction effects, we investigated whether TLR4 expression on carotid atherosclerotic plaques correlates with statin intake. Carotid atherosclerotic plaques were obtained on 140 patients (preoperative statin intake, n = 70). TLR4 immunohistochemical expression was investigated in endothelial cells (ECs), macrophages (MACs) and smooth muscle cells (SMCs) of carotid atheroma. TLR4 positivity, over-expression and intensity of immunostaining were compared in statin versus no-statin users. The results of this study showed that statin users had a significantly lower expression of TLR4 in ECs (P = 0.02, 0.001, 0.006 for TLR4 positivity, increased intensity and over-expression, respectively). Similarly, TLR4 positivity was less pronounced in carotid plaque MACs of statin users (P = 0.03). No carotid specimen with increased EC TLR4 intensity or over-expression was observed among statin users. The prevalence of any cerebrovascular accident was 61.4% in the 'no statin' versus 18.6% in the 'statin' group (odds ratio for statin use: 0.14, 95% CI: 0.07-0.31, P < 0.001). In conclusion, statin treatment is associated with attenuated TLR4 expression on human carotid atherosclerotic plaques and a reduced risk of carotid-related cerebrovascular events. TLR4 may potentially mediate statins' plaque stabilization effects. Further investigation is necessary.

Novel biphasic role of LipoxinA(4) on expression of cyclooxygenase-2 in lipopolysaccharide-stimulated lung fibroblasts

Fibroblasts are important to host defence and immunity, can also as initiators of inflammation as well. As the endogenous “braking signal”, Lipoxins can regulate anti-inflammation and the resolution of inflammation. We investigated the effect of lipoxinA₄ on the expression of cyclooxygenase-2 in lipopolysaccharide-stimulated lung fibroblasts. We demonstrated that the expression of cyclooxygenase-2 protein was significantly increased and peaked initially at 6 hours, with a second increase, with maximal levels occurring 24 hours after lipopolysaccharide challenge. ProstaglandinE₂ levels also peaked at 6 hours, and prostaglandinD₂ levels were increased at both 6 and 24 hours. Exogenous lipoxinA₄ inhibited the first peak of cyclooxygenase-2 expression as well as the production of prostaglandinE₂ induced by lipopolysaccharide in a dose-dependent manner. In contrast, exogenous lipoxinA₄ increased the second peak of cyclooxygenase-2 expression as well as the production of prostaglandinD₂ induced by lipopolysaccharide in a dose-dependent manner. LipoxinA₄ receptor mRNA expression was markedly stimulated by lipopolysaccharide but inhibited by lipoxinA₄. We present evidence for a novel biphasic role of lipoxinA₄ on the expression of cyclooxygenase-2 in lipopolysaccharide-stimulated lung fibroblasts, whereby LXA₄ has an anti-inflammatory and proresolving activity in lung fibroblasts following LPS stimulation.