Methotrexate in atherogenesis and cholesterol metabolism

Treating Cardiovascular Disease in the Inflammatory Setting of Rheumatoid Arthritis: An Ongoing Challenge

Despite progress in treating rheumatoid arthritis, this autoimmune disorder confers an increased risk of developing cardiovascular disease (CVD). Widely used screening protocols and current clinical guidelines are inadequate for the early detection of CVD in persons with rheumatoid arthritis. Traditional CVD risk factors alone cannot be applied because they underestimate CVD risk in rheumatoid arthritis, missing the window of opportunity for prompt intervention to decrease morbidity and mortality. The lipid profile is insufficient to assess CVD risk. This review delves into the connection between systemic inflammation in rheumatoid arthritis and the premature onset of CVD. The shared inflammatory and immunologic pathways between the two diseases that result in subclinical atherosclerosis and disrupted cholesterol homeostasis are examined. The treatment armamentarium for rheumatoid arthritis is summarized, with a particular focus on each medication's cardiovascular effect, as well as the mechanism of action, risk-benefit profile, safety, and cost. A clinical approach to CVD screening and treatment for rheumatoid arthritis patients is proposed based on the available evidence. The mortality gap between rheumatoid arthritis and non-rheumatoid arthritis populations due to premature CVD represents an urgent research need in the fields of cardiology and rheumatology. Future research areas, including risk assessment tools and novel immunotherapeutic targets, are highlighted.

Macrophage Membrane-Encapsulated Dopamine-Modified Poly Cyclodextrin Multifunctional Biomimetic Nanoparticles for Atherosclerosis Therapy

Atherosclerotic plaques exhibit high cholesterol deposition and oxidative stress resulting from high reactive oxygen species (ROS). These are the major components in plaques and the main pro-inflammatory factor. Therefore, it is crucial to develop an effective therapeutic strategy that can simultaneously address the multiple pro-inflammatory factors via removing cholesterol and inhibiting the overaccumulated ROS. In this study, we constructed macrophage membrane-encapsulated biomimetic nanoparticles (MM@DA-pCD@MTX), which not only alleviate cholesterol deposition at the plaque lesion via reverse cholesterol transport but also scavenge the overaccumulated ROS. β-Cyclodextrin (β-CD) and the loaded methotrexate (MTX) act synergistically to induce cholesterol efflux for inhibiting the formation of foam cells. Among them, MTX up-regulated the expression of ABCA1, CYP27A1, and SR-B1. β-CD increased the solubility of cholesterol crystals. In addition, the ROS scavenging property of dopamine (DA) was perfectly preserved in MM@DA-pCD@MTX, which could scavenge the overaccumulated ROS to alleviate the oxidative stress at the plaque lesion. Last but not least, MM-functionalized "homing" targeting of atherosclerotic plaques not only enables the targeted drug delivery but also prolongs in vivo circulation time and drug half-life. In summary, MM@DA-pCD@MTX emerges as a potent, multifunctional therapeutic platform for AS treatment, offering a high degree of biosafety and efficacy in addressing the complex pathophysiology of atherosclerosis.

Biomimetic nanoparticles to enhance the reverse cholesterol transport for selectively inhibiting development into foam cell in atherosclerosis

A disorder of cholesterol homeostasis is one of the main initiating factors in the progression of atherosclerosis (AS). Metabolism and removal of excess cholesterol facilitates the prevention of foam cell formation. However, the failure of treatment with drugs (e.g. methotrexate, MTX) to effectively regulate progression of disease may be related to the limited drug bioavailability and rapid clearance by immune system. Thus, based on the inflammatory lesion "recruitment" properties of macrophages, MTX nanoparticles (MTX NPs) camouflaged with macrophage membranes (MM@MTX NPs) were constructed for the target to AS plaques. MM@MTX NPs exhibited a uniform hydrodynamic size around ~ 360 nm and controlled drug release properties (~ 72% at 12 h). After the macrophage membranes (MM) functionalized "homing" target delivery to AS plaques, MM@MTX NPs improved the solubility of cholesterol by the functionalized β-cyclodextrin (β-CD) component and significantly elevate cholesterol efflux by the loaded MTX mediated the increased expression levels of ABCA1, SR-B1, CYP27A1, resulting in efficiently inhibiting the formation of foam cells. Furthermore, MM@MTX NPs could significantly reduce the area of plaque, aortic plaque and cholesterol crystals deposition in ApoE-/- mice and exhibited biocompatibility. It is suggested that MM@MTX NPs were a safe and efficient therapeutic platform for AS.

Research progress on the therapeutic effects of nanoparticles loaded with drugs against atherosclerosis

Presently, there are many drugs for the treatment of atherosclerosis (AS), among which lipid-lowering, anti-inflammatory, and antiproliferative drugs have been the most studied. These drugs have been shown to have inhibitory effects on the development of AS. Nanoparticles are suitable for AS treatment research due to their fine-tunable and modifiable properties. Compared with drug monotherapy, experimental results have proven that the effects of nanoparticle-encapsulated drugs are significantly enhanced. In addition to nanoparticles containing a single drug, there have been many studies on collaborative drug treatment, collaborative physical treatment (ultrasound, near-infrared lasers, and external magnetic field), and the integration of diagnosis and treatment. This review provides an introduction to the therapeutic effects of nanoparticles loaded with drugs to treat AS and summarizes their advantages, including increased targeting ability, sustained drug release, improved bioavailability, reduced toxicity, and inhibition of plaque and vascular stenosis.

The Hypoxia-Adenosine Link during Myocardial Ischemia-Reperfusion Injury

Despite increasing availability and more successful interventional approaches to restore coronary reperfusion, myocardial ischemia-reperfusion injury is a substantial cause of morbidity and mortality worldwide. During myocardial ischemia, the myocardium becomes profoundly hypoxic, thus causing stabilization of hypoxia-inducible transcription factors (HIF). Stabilization of HIF leads to a transcriptional program that promotes adaptation to hypoxia and cellular survival. Transcriptional consequences of HIF stabilization include increases in extracellular production and signaling effects of adenosine. Extracellular adenosine functions as a signaling molecule via the activation of adenosine receptors. Several studies implicated adenosine signaling in cardioprotection, particularly through the activation of the Adora2a and Adora2b receptors. Adenosine receptor activation can lead to metabolic adaptation to enhance ischemia tolerance or dampen myocardial reperfusion injury via signaling events on immune cells. Many studies highlight that clinical strategies to target the hypoxia-adenosine link could be considered for clinical trials. This could be achieved by using pharmacologic HIF activators or by directly enhancing extracellular adenosine production or signaling as a therapy for patients with acute myocardial infarction, or undergoing cardiac surgery.

Cancer therapy's impact on lipid metabolism: Mechanisms and future avenues

Atherosclerotic cardiovascular disease is a growing threat among cancer patients. Not surprisingly, cancer-targeting therapies have been linked to metabolic dysregulation including changes in local and systemic lipid metabolism. Thus, tumor development and cancer therapeutics are intimately linked to cholesterol metabolism and may be a driver of increased cardiovascular morbidity and mortality in this population. Chemotherapeutic agents affect lipid metabolism through diverse mechanisms. In this review, we highlight the mechanistic and clinical evidence linking commonly used cytotoxic therapies with cholesterol metabolism and potential opportunities to limit atherosclerotic risk in this patient population. Better understanding of the link between atherosclerosis, cancer therapy, and cholesterol metabolism may inform optimal lipid therapy for cancer patients and mitigate cardiovascular disease burden.

Methotrexate effects on adenosine receptor expression in peripheral monocytes of persons with type 2 diabetes and cardiovascular disease

The Cardiovascular Inflammation Reduction Trial (CIRT) was designed to assess whether low-dose methotrexate (LD-MTX) would reduce future cardiac events in patients with metabolic syndrome or type 2 diabetes (T2DM) who are post-myocardial infarction (MI) or have multivessel disease. Our previous work indicates that MTX confers atheroprotection via adenosine A2A receptor (A2AR) activation. In order for A2AR ligation to reduce cardiovascular events, A2AR levels would need to be preserved during MTX treatment. This study was conducted to determine whether LD-MTX alters peripheral blood mononuclear cell (PBMC) adenosine receptor expression in persons at risk for cardiovascular events. Post-MI T2DM CIRT patients were randomized to LD-MTX or placebo (n=10/group). PBMC isolated from blood drawn at enrollment and after 6 weeks were evaluated for expression of adenosine receptors and reverse cholesterol transporters by real-time PCR. Fold change between time points was calculated using factorial analyses of variance. Compared with placebo, the LD-MTX group exhibited a trend toward an increase in A2AR (p=0.06), while A3R expression was significantly decreased (p=0.01) after 6 weeks. Cholesterol efflux gene expression did not change significantly. Persistence of A2AR combined with A3R downregulation indicates that failure of MTX to be atheroprotective in CIRT was not due to loss of adenosine receptors on PBMC (ClinicalTrials.gov identifier: NCT01594333).

Treatment of Cardiovascular Disease in Rheumatoid Arthritis: A Complex Challenge with Increased Atherosclerotic Risk

Rheumatoid arthritis (RA) carries significant risk for atherosclerotic cardiovascular disease (ASCVD). Traditional ASCVD risk factors fail to account for this accelerated atherosclerosis. Shared inflammatory pathways are fundamental in the pathogenesis of both diseases. Considering the impact of RA in increasing cardiovascular morbidity and mortality, the characterization of therapies encompassing both RA and ASCVD management merit high priority. Despite little progress, several drugs discussed here promote remission and or lower rheumatoid disease activity while simultaneously conferring some level of atheroprotection. Methotrexate, a widely used disease-modifying drug used in RA, is associated with significant reduction in cardiovascular adverse events. MTX promotes cholesterol efflux from macrophages, upregulates free radical scavenging and improves endothelial function. Likewise, the sulfonamide drug sulfasalazine positively impacts the lipid profile by increasing HDL-C, and its use in RA has been correlated with reduced risk of myocardial infraction. In the biologic class, inhibitors of TNF-α and IL-6 contribute to improvements in endothelial function and promote anti-atherogenic properties of HDL-C, respectively. The immunosuppressant hydroxychloroquine positively affects insulin sensitization and the lipid profile. While no individual therapy has elicited optimal atheroprotection, further investigation of combination therapies are ongoing.

Modulating Lipoprotein Transcellular Transport and Atherosclerotic Plaque Formation in ApoE-/- Mice via Nanoformulated Lipid-Methotrexate Conjugates

Macrophage inflammation and maturation into foam cells, following the engulfment of oxidized low-density lipoproteins (oxLDL), are major hallmarks in the onset and progression of atherosclerosis. Yet, chronic treatments with anti-inflammatory agents, such as methotrexate (MTX), failed to modulate disease progression, possibly for the limited drug bioavailability and plaque deposition. Here, MTX-lipid conjugates, based on 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), were integrated in the structure of spherical polymeric nanoparticles (MTX-SPNs) or intercalated in the lipid bilayer of liposomes (MTX-LIP). Although, both nanoparticles were colloidally stable with an average diameter of ∼200 nm, MTX-LIP exhibited a higher encapsulation efficiency (>70%) and slower release rate (∼50% at 10 h) compared to MTX-SPN. In primary bone marrow derived macrophages (BMDMs), MTX-LIP modulated the transcellular transport of oxLDL more efficiently than free MTX mostly by inducing a 2-fold overexpression of ABCA1 (regulating oxLDL efflux), while the effect on CD36 and SRA-1 (regulating oxLDL influx) was minimal. Furthermore, in BMDMs, MTX-LIP showed a stronger anti-inflammatory activity than free MTX, reducing the expression of IL-1β by 3-fold, IL-6 by 2-fold, and also moderately of TNF-α. In 28 days high-fat-diet-fed apoE-/- mice, MTX-LIP reduced the mean plaque area by 2-fold and the hematic amounts of RANTES by half as compared to free MTX. These results would suggest that the nanoenhanced delivery to vascular plaques of the anti-inflammatory DSPE-MTX conjugate could effectively modulate the disease progression by halting monocytes' maturation and recruitment already at the onset of atherosclerosis.

The role of interferon-γ in cardiovascular disease: an update

PURPOSE

Cardiovascular disease (CVD) is the leading cause of death, globally, and its prevalence is only expected to rise due to the increasing incidence of co-morbidities such as obesity and diabetes. Medical treatment of CVD is directed primarily at slowing or reversing the underlying atherosclerotic process by managing circulating lipids with an emphasis on control of low-density lipoprotein (LDL) cholesterol. However, over the past several decades, there has been increasing recognition that chronic inflammation and immune system activation are important contributors to atherosclerosis. This shift in focus has led to the elucidation of the complex interplay between cholesterol and cellular secretion of cytokines involved in CVD pathogenesis. Of the vast array of cytokine promoting atherosclerosis, interferon (IFN)-γ is highly implicated and, therefore, of great interest.

METHODS

Literature review was performed to further understand the effect of IFN-γ on the development of atherosclerotic CVD.

RESULTS

IFN-γ, the sole member of the type II IFN family, is produced by T cells and macrophages, and has been found to induce production of other cytokines and to have multiple effects on all stages of atherogenesis. IFN-γ activates a variety of signaling pathways, most commonly the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, to induce oxidative stress, promote foam cell accumulation, stimulate smooth muscle cell proliferation and migration into the arterial intima, enhance platelet-derived growth factor expression, and destabilize plaque. These are just a few of the contributions of IFN-γ to the initiation and progression of atherosclerotic CVD.

CONCLUSION

Given the pivotal role of IFN-γ in the advancement of CVD, activation of its signaling pathways is being explored as a driver of atherosclerosis. Manipulation of this key cytokine may lead to novel therapeutic avenues for CVD prevention and treatment. A number of therapies are being explored with IFN-γ as the potential target.

Effect of methotrexate treatment on the expression of epidermal-fatty acid-binding protein (E-FABP) and apolipoproteins in patients with psoriasis

Introduction

Epidermal-fatty acid-binding protein (E-FABP) is a marker of transiently amplifying cells which are formed from stem cells in epidermis. Their role is an uptake of fatty acids and metabolism. Psoriatic keratinocytes overexpress E-FABPs, which leads to acanthosis and may explain the lipid’s disturbances in psoriasis.

Aim

Assessment of FABP and apolipoprotein expression in patients treated with methotrexate (MTX).

Material and methods

FABP expression in the lesional and perilesional psoriatic skin from 11 male patients compared to 5 healthy skin samples were evaluated by immunohistochemistry. FABP, apolipoprotein A1 (ApoA1) and B (ApoB) serum levels were assessed by ELISA. These parameters were evaluated before and after treatment with subcutaneous MTX (15 mg/wk for 12 weeks).

Results

Expression of E-FABP was lower in the control group than in the lesional and perilesional psoriatic skin, before and after treatment. After treatment the expression decreased in the lesional and perilesional skin. Serum E-FABP was higher in the control group (482.855 ±240.550 pg/ml) compared to patients, but not statistically significantly. After MTX treatment, a statistically significant reduction was observed in psoriatic patients. ApoA1 levels did not differ in the control and patients groups, both before and after treatment. In contrast, ApoB levels did not differ statistically between the control group (1447.126 ±311.11 ng/ml) and patients before treatment, while they were the lowest after treatment (1081.67 ±117.83 ng/ml vs. 808.306 ±103.72 ng/ml; p < 0.01).

Conclusions

Our study confirms the beneficial effect of MTX, not only as an anti-proliferative effect, but also reducing the cardiovascular risk by decreasing atherogenic ApoB.

The ABC subfamily A transporters: Multifaceted players with incipient potentialities in cancer

Overexpression of ATP-binding cassette (ABC) transporters is a cause of drug resistance in a plethora of tumors. More recent evidence indicates additional contribution of these transporters to other processes, such as tumor cell dissemination and metastasis, thereby extending their possible roles in tumor progression. While the role of some ABC transporters, such as ABCB1, ABCC1 and ABCG2, in multidrug resistance is well documented, the mechanisms by which ABC transporters affect the proliferation, differentiation, migration and invasion of cancer cells are still poorly defined and are frequently controversial. This review, summarizes recent advances that highlight the role of subfamily A members in cancer. Emerging evidence highlights the potential value of ABCA members as biomarkers of risk and response in different tumors, but information is disperse and very little is known about their possible mechanisms of action. The only clear evidence is that ABCA members are involved in lipid metabolism and homeostasis. In particular, the relationship between ABCA1 and cholesterol is becoming evident in different fields of biology, including cancer. In parallel, emerging findings indicate that cholesterol, the main component of cell membranes, can influence many physiological and pathological processes, including cell migration, cancer progression and metastasis. This review aims to link the dispersed knowledge regarding the relationship of ABCA members with lipid metabolism and cancer in an effort to stimulate and guide readers to areas that the writers consider to have significant impact and relevant potentialities.

Adenosine and the Cardiovascular System

Adenosine is an endogenous nucleoside with a short half-life that regulates many physiological functions involving the heart and cardiovascular system. Among the cardioprotective properties of adenosine are its ability to improve cholesterol homeostasis, impact platelet aggregation and inhibit the inflammatory response. Through modulation of forward and reverse cholesterol transport pathways, adenosine can improve cholesterol balance and thereby protect macrophages from lipid overload and foam cell transformation. The function of adenosine is controlled through four G-protein coupled receptors: A₁, A_2A, A_2B and A₃. Of these four, it is the A_2A receptor that is in a large part responsible for the anti-inflammatory effects of adenosine as well as defense against excess cholesterol accumulation. A_2A receptor agonists are the focus of efforts by the pharmaceutical industry to develop new cardiovascular therapies, and pharmacological actions of the atheroprotective and anti-inflammatory drug methotrexate are mediated via release of adenosine and activation of the A_2A receptor. Also relevant are anti-platelet agents that decrease platelet activation and adhesion and reduce thrombotic occlusion of atherosclerotic arteries by antagonizing adenosine diphosphate-mediated effects on the P2Y12 receptor. The purpose of this review is to discuss the effects of adenosine on cell types found in the arterial wall that are involved in atherosclerosis, to describe use of adenosine and its receptor ligands to limit excess cholesterol accumulation and to explore clinically applied anti-platelet effects. Its impact on electrophysiology and use as a clinical treatment for myocardial preservation during infarct will also be covered. Results of cell culture studies, animal experiments and human clinical trials are presented. Finally, we highlight future directions of research in the application of adenosine as an approach to improving outcomes in persons with cardiovascular disease.

NLRP3 Inflammasome and the IL-1 Pathway in Atherosclerosis

Inflammation is an important driver of atherosclerosis, the underlying pathology of cardiovascular diseases. Therefore, therapeutic targeting of inflammatory pathways is suggested to improve cardiovascular outcomes in patients with cardiovascular diseases. This concept was recently proven by CANTOS (Canakinumab Anti-Inflammatory Thrombosis Outcomes Study), which demonstrated the therapeutic potential of the monoclonal IL (interleukin)-1β-neutralizing antibody canakinumab. IL-1β and other IL-1 family cytokines are important vascular and systemic inflammatory mediators, which contribute to atherogenesis. The NLRP3 (NOD [nucleotide oligomerization domain]-, LRR [leucine-rich repeat]-, and PYD [pyrin domain]-containing protein 3) inflammasome, an innate immune signaling complex, is the key mediator of IL-1 family cytokine production in atherosclerosis. NLRP3 is activated by various endogenous danger signals abundantly present in atherosclerotic lesions, such as oxidized low-density lipoprotein and cholesterol crystals. Consequently, NLRP3 inflammasome activation contributes to the vascular inflammatory response driving atherosclerosis development and progression. Here, we review the mechanisms of NLRP3 inflammasome activation and proinflammatory IL-1 family cytokine production in the context of atherosclerosis and discuss treatment possibilities in light of the positive outcomes of the CANTOS trial.

The Therapeutic Potential of Nanoparticles to Reduce Inflammation in Atherosclerosis

Chronic inflammation is one of the main determinants of atherogenesis. The traditional medications for treatment of atherosclerosis are not very efficient in targeting atherosclerotic inflammation. Most of these drugs are non-selective, anti-inflammatory and immunosuppressive agents that have adverse effects and very limited anti-atherosclerotic effects, which limits their systemic administration. New approaches using nanoparticles have been investigated to specifically deliver therapeutic agents directly on atherosclerotic lesions. The use of drug delivery systems, such as polymeric nanoparticles, liposomes, and carbon nanotubes are attractive strategies, but some limitations exist. For instance, nanoparticles may alter the drug kinetics, based on the pathophysiological mechanisms of the diseases. In this review, we will update pathophysiological evidence for the use of nanoparticles to reduce inflammation and potentially prevent atherogenesis in different experimental models.

Accelerated Atherosclerosis in Rheumatoid Arthritis: Mechanisms and Treatment

Background:

Rheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disorder that increases the risk of developing cardiovascular disease. There is accumulating evidence that the RA disease state accelerates the formation of atherosclerotic plaques. Treatments for RA improve joint symptomatology and may reduce inflammation, but consideration of their effects on the cardiovascular system is generally low priority.

Objective:

Since cardiovascular disease is the leading cause of mortality in RA patients, the impact of RA therapies on atherosclerosis is an area in need of attention and the focus of this review.

Results:

The drugs used to treat RA may be analgesics, conventional disease-modifying anti-rheumatic drugs, and/or biologics, including antibodies against the cytokine tumor necrosis factor-α. Pain relievers such as nonselective non-steroidal anti-inflammatory drugs and cyclooxygenase inhibitors may adversely affect lipid metabolism and cyclooxygenase inhibitors have been associated with increased adverse cardiovascular events, such as myocardial infarction and stroke. Methotrexate, the anchor disease-modifying anti-rheumatic drug in RA treatment has multiple atheroprotective advantages and is often combined with other therapies. Biologic inhibitors of tumor necrosis factor-α may be beneficial in preventing cardiovascular disease because tumor necrosis factor-α promotes the initiation and progression of atherosclerosis. However, some studies show a worsening of the lipid profile in RA with blockade of this cytokine, leading to higher total cholesterol and triglycerides.

Conclusion:

Greater understanding of the pharmacologic activity of RA treatments on the atherosclerotic process may lead to improved care, addressing both damages to the joints and heart.

Anti-inflammatory therapy for cardiovascular disease

Chronic subclinical inflammation is a central process in the pathogenesis of cardiovascular disease (CVD) and it has been linked with both the initiation and progression of atherosclerosis. Several pro-inflammatory cytokines, such as the C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) have been described as independent risk factors for coronary heart disease and promoters of atherogenesis. Thus, extensive research is being conducted to assess the role of anti-inflammatory therapy in the primary and secondary prevention of CVD. Our review aims to provide the clinical and scientific data pertaining to the effects of different anti-inflammatory agents administered in patients with CVD.

Patients with Rheumatoid Arthritis Were Associated with a Risk of Rotator Cuff Diseases

Rheumatoid arthritis (RA) commonly causes inflammation in the joints and periarticular structures. The association between RA and rotator cuff (RC) has been reported; however, epidemiological studies on RA and RC tendons are scant. Therefore, we investigated RC disease (RCD) risk and analyzed the effects of RA medication, steroids, and methotrexate, on the risk of RCD for patients with RA. We conducted a retrospective cohort study with a 6-year longitudinal follow-up in Taiwan. Patients who received RA diagnoses between 2004 and 2008 were enrolled in the study cohort. The non-RA control cohort comprised age- and sex-matched controls. Propensity score matching was used for other comorbidities and treatments. The hazard ratios (HRs) and adjusted HRs (aHRs) were estimated after confounders were adjusted for. Effects of steroid and methotrexate use on RCD risk were also analyzed. We enrolled 4521 RA patients (study cohort) and 22,605 matched controls. RCD incidence was 145 and 91 per 100,000 person-years in the RA and control cohorts, respectively. In the RA cohort, the crude HR for RCD was 1.62 (95% confidence interval (CI), 1.41–1.86, p < 0.001), and the aHR was 1.56 (95% CI, 1.36–1.79, p < 0.001). The methotrexate nonusers exhibited an aHR (vs. controls) of 1.61 (95% CI, 1.40–1.85, p < 0.001), but the methotrexate users did not have a significantly higher aHR than the controls. The steroid nonusers had an aHR (vs. controls) of 1.69 (95% CI, 1.46–1.96, p < 0.001), but the aHR of the steroid users was not significantly higher than the control aHR. Patients with RA had a higher risk for RCD compared with the non-RA control cohort. Steroids or methotrexate use significantly reduces the risk of RCD occurrence in patients with RA. Treatment for RCD symptoms and controlling inflammatory process are important to ensure high-quality care for patients with RA.

Targeting Inflammation With Nanosized Drug Delivery Platforms in Cardiovascular Diseases: Immune Cell Modulation in Atherosclerosis

Atherosclerosis (AS) is a disorder of large and medium-sized arteries; it consists in the formation of lipid-rich plaques in the intima and inner media, whose pathophysiology is mostly driven by inflammation. Currently available interventions and therapies for treating atherosclerosis are not always completely effective; side effects associated with treatments, mainly caused by immunodepression for anti-inflammatory molecules, limit the systemic administration of these and other drugs. Given the high degree of freedom in the design of nanoconstructs, in the last decades researchers have put high effort in the development of nanoparticles (NPs) formulations specifically designed for either drug delivery, visualization of atherosclerotic plaques, or possibly the combination of both these and other functionalities. Here we will present the state of the art of these subjects, the knowledge of which is necessary to rationally address the use of NPs for prevention, diagnosis, and/or treatment of AS. We will analyse the work that has been done on: (a) understanding the role of the immune system and inflammation in cardiovascular diseases, (b) the pathological and biochemical principles in atherosclerotic plaque formation, (c) the latest advances in the use of NPs for the recognition and treatment of cardiovascular diseases, (d) the cellular and animal models useful to study the interactions of NPs with the immune system cells.

Analysis of Drug Effects on Primary Human Coronary Artery Endothelial Cells Activated by Serum Amyloid A

Background

RA patients have a higher incidence of cardiovascular diseases compared to the general population. Serum amyloid A (SAA) is an acute-phase protein, upregulated in sera of RA patients.

Aim

To determine the effects of medications on SAA-stimulated human coronary artery endothelial cells (HCAEC).

Methods

HCAEC were preincubated for 2 h with medications from sterile ampules (dexamethasone, methotrexate, certolizumab pegol, and etanercept), dissolved in medium (captopril) or DMSO (etoricoxib, rosiglitazone, meloxicam, fluvastatin, and diclofenac). Human recombinant apo-SAA was used to stimulate HCAEC at a final 1000 nM concentration for 24 hours. IL-6, IL-8, sVCAM-1, and PAI-1 were measured by ELISA. The number of viable cells was determined colorimetrically.

Results

SAA-stimulated levels of released IL-6, IL-8, and sVCAM-1 from HCAEC were significantly attenuated by methotrexate, fluvastatin, and etoricoxib. Both certolizumab pegol and etanercept significantly decreased PAI-1 by an average of 43%. Rosiglitazone significantly inhibited sVCAM-1 by 58%.

Conclusion

We observed marked influence of fluvastatin on lowering cytokine production in SAA-activated HCAEC. Methotrexate showed strong beneficial effects for lowering released Il-6, IL-8, and sVCAM-1. Interesting duality was observed for NSAIDs, with meloxicam exhibiting opposite-trend effects from diclofenac and etoricoxib. This represents unique insight into specific responsiveness of inflammatory-driven HCAEC relevant to atherosclerosis.

The effect of subcutaneous methotrexate on markers of metabolic syndrome in psoriatic patients - preliminary report

INTRODUCTION

Methotrexate (MTX) has anti-proliferative and anti-inflammatory effects in psoriasis. Moreover, low doses can reduce the risk of developing cardiovascular diseases. It turns out that psoriasis and atherosclerosis have a similar pathogenetic mechanism: the same pro-inflammatory cytokines, Th1 and Th17, are involved in both diseases.

AIM

To evaluate the effects of metabolic markers, protective cytokines (interleukin 10 (IL-10), transforming growth factor β (TGF-β)) and a marker of endothelial damage (endocan) in patients with plaque psoriasis.

MATERIAL AND METHODS

The study included 24 patients aged 27-69 years (9 female, 15 male) with plaque psoriasis. The metabolic syndrome according to the International Diabetes Federation (IDF) was evaluated. The laboratory tests were performed under fasting conditions: C-reactive protein (CRP), glucose, total cholesterol, triglycerides, high-density lipoprotein (HDL), uric acid, endocan, IL-10, and TGF-β. After 12 weeks of treatment with MTX injections 15 mg/week, every patient was assessed with the same laboratory tests.

RESULTS

After treatment we observed a statistically significant increase of endocan and IL-10, but no significant differences in the titer of TGF-β. C-reactive protein was reduced by approximately 54.7%. No improvement of lipid profile was observed, and even a significant increase in triglycerides was noted. Similarly, no significant difference was seen in the case of glucose and uric acid prior to and after treatment.

CONCLUSIONS

Methotrexate in low doses in short-term treatment decreases CRP (anti-inflammatory effect) and increases endocan and IL-10 (potential protective role). Methotrexate is characterized by good efficacy and tolerability in therapy of patients with psoriasis.

Methotrexate might reduce ischemic stroke in patients with rheumatoid arthritis: a population-based retrospective cohort study

AIM

To investigate the effects of hydroxychloroquine, sulfasalazine and methotrexate on ischemic stroke in patients with rheumatoid arthritis (RA).

METHODS

This population-based retrospective cohort study included 7904 RA patients and 15 808 non-RA patients between 2000 and 2010. All of the participants were sampled from the National Health Insurance Research Database (NHIRD) of Taiwan. Using univariate analyses, these two groups of patients were compared to evaluate the differences in disease-modifying anti-rheumatic drugs usage and demographic variables. Cox proportional hazard models and Schoenfeld residuals test were performed to estimate the hazard ratios for ischemic stroke and proportional hazard assumptions of these drugs, respectively.

RESULTS

The mean age of participants was about 53 years old, and about 70% of RA patients were women. The hazard ratio for ischemic stroke was 1.21 (95% CI: 1.10-1.34; P < 0.01) in the case group compared with the control group, and this significant difference persisted throughout the 10-year period. With respect to RA patients, while hydroxychloroquine showed an insignificant protective effect on ischemic stroke, sulfasalazine and methotrexate were found out to have inconsistent effects during these 10 years. The proportional hazard assumption test of methotrexate at > 0.5 defined daily dose (8.75 mg/week) was violated at a significant level after adjustment (P = 0.0002).

CONCLUSIONS

At a dosage of > 0.5 defined daily dose, short-term methotrexate might decrease ischemic stroke risk in RA patients, while hydroxychloroquine and sulfasalazine were neutral.

Current and future therapies for addressing the effects of inflammation on HDL cholesterol metabolism

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Inflammatory processes arising from metabolic abnormalities are known to precipitate the development of CVD. Several metabolic and inflammatory markers have been proposed for predicting the progression of CVD, including high density lipoprotein cholesterol (HDL-C). For ~50 years, HDL-C has been considered as the atheroprotective 'good' cholesterol because of its strong inverse association with the progression of CVD. Thus, interventions to increase the concentration of HDL-C have been successfully tested in animals; however, clinical trials were unable to confirm the cardiovascular benefits of pharmaceutical interventions aimed at increasing HDL-C levels. Based on these data, the significance of HDL-C in the prevention of CVD has been called into question. Fundamental in vitro and animal studies suggest that HDL-C functionality, rather than HDL-C concentration, is important for the CVD-preventive qualities of HDL-C. Our current review of the literature positively demonstrates the negative impact of systemic and tissue (i.e. adipose tissue) inflammation in the healthy metabolism and function of HDL-C. Our survey indicates that HDL-C may be a good marker of adipose tissue health, independently of its atheroprotective associations. We summarize the current findings on the use of anti-inflammatory drugs to either prevent HDL-C clearance or improve the function and production of HDL-C particles. It is evident that the therapeutic agents currently available may not provide the optimal strategy for altering HDL-C metabolism and function, and thus, further research is required to supplement this mechanistic approach for preventing the progression of CVD.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Effects of Pomegranate (Punica Granatum L.) Seed and Peel Methanolic Extracts on Oxidative Stress and Lipid Profile Changes Induced by Methotrexate in Rats

Purpose: Methotrexate (MTX) is prescribed in many diseases and can result in oxidative stress (OS) followed by injuries in some tissues. Antioxidants administration are effective in reducing OS. Pomegranate exhibits high anti-oxidant capacities. This study investigated whether pomegranate seed and peel methanolic extracts (PSE and PPE) could protect against MTX-induced OS and lipid profile changes in rats.

Methods: Forty-eight rats were randomly divided into 6 groups: control group (normal salin), PSE group (500 mg/kg, orally), PPE group (500 mg/kg, orally), MTX group (10 mg/kg, IM), MTX and PSE group, and MTX and PPE group. Blood samples were taken for analysis in the end of the procedure.

Results: The findings showed a significant reduction in Glutathione peroxidase (GPx) and Superoxide dismutase (SOD), and an enhancement in malondialdehyde (MDA) values after MTX treatment (p < 0.05). SOD and GPx levels reached the levels of the control group in MTX+SPE and MTX+PPE groups. No significant differences were observed in catalase (CAT) and total antioxidant capacity (TAC) levels between groups. The results showed a significant decrease in total cholesterol (TC), low density lipoprotein (LDL), and high density lipoprotein (HDL) in the MTX treated group (p < 0.01). The values of TC, HDL, and LDL became elevated to the normal control levels in the MTX+PSE and MTX+PPE treated groups.

Conclusion: The results showed the OS induced by MTX and the protective effects of PSE and PPE against MTX-induced serum oxidative stress and lipid profile changes in rats.

Redox regulation of NLRP3 inflammasomes: ROS as trigger or effector?

SIGNIFICANCE

Inflammasomes are multiprotein complexes localized within the cytoplasm of the cell that are responsible for the maturation of proinflammatory cytokines such as interleukin-1β (IL-1β) and IL-18, and the activation of a highly inflammatory form of cell death, pyroptosis. In response to infection or cellular stress, inflammasomes are assembled, activated, and involved in host defense and pathophysiology of diseases. Clarification of the molecular mechanisms leading to the activation of this intracellular inflammatory machinery may provide new insights into the concept of inflammation as the root of and route to human diseases.

RECENT ADVANCES

The activation of inflammasomes, specifically the most fully characterized inflammasome-the nucleotide-binding oligomerization domain (NOD)-like receptor containing pyrin domain 3 (NLRP3) inflammasome, is now emerging as a critical molecular mechanism for many degenerative diseases. Several models have been developed to describe how NLRP3 inflammasomes are activated, including K(+) efflux, lysosome function, endoplasmic reticulum (ER) stress, intracellular calcium, ubiquitination, microRNAs, and, in particular, reactive oxygen species (ROS).

CRITICAL ISSUES

ROS may serve as a "kindling" or triggering factor to activate NLRP3 inflammasomes as well as "bonfire" or "effector" molecules, resulting in pathological processes. Increasing evidence seeks to understand how this spatiotemporal action of ROS occurs during NLRP3 inflammasome activation, which will be a major focus of this review.

FUTURE DIRECTIONS

It is imperative to know how this dual action of ROS works during NLRP3 inflammation activation on different stimuli and what relevance such spatiotemporal redox regulation of NLRP3 inflammasomes has in cell or organ functions and possible human diseases.

Systems level metabolic phenotype of methotrexate administration in the context of non-alcoholic steatohepatitis in the rat

Adverse drug reactions (ADRs) represent a significant clinical challenge with respect to patient morbidity and mortality. We investigated the hepatotoxicity and systems level metabolic phenotype of methotrexate (MTX) in the context of a prevalent liver disease; non-alcoholic steatohepatitis (NASH). A nuclear magnetic resonance spectroscopic-based metabonomic approach was employed to analyze the metabolic consequences of MTX (0, 10, 40, and 100 mg/kg) in the urine and liver of healthy rats (control diet) and in a model of NASH (methionine-choline deficient diet). Histopathological analysis confirmed baseline (0 mg/kg) liver necrosis, liver inflammation, and lipid accumulation in the NASH model. Administration of MTX (40 and 100 mg/kg) led to liver necrosis in the control cohort, whereas the NASH cohort also displayed biliary hyperplasia and liver fibrosis (100 mg/kg), providing evidence of the synergistic effect of MTX and NASH. The complementary hepatic and urinary metabolic phenotypes of the NASH model, at baseline, revealed perturbation of multiple metabolites associated with oxidative and energetic stress, and folate homeostasis. Administration of MTX in both diet cohorts showed dose-dependent metabolic consequences affecting gut microbial, energy, nucleobase, nucleoside, and folate metabolism. Furthermore, a unique panel of metabolic changes reflective of the synergistic effect of MTX and NASH was identified, including the elevation of hepatic phenylalanine, urocanate, acetate, and both urinary and hepatic formiminoglutamic acid. This systems level metabonomic analysis of the hepatotoxicity of MTX in the context of NASH provided novel mechanistic insight of potential wider clinical relevance for further understanding the role of liver pathology as a risk factor for ADRs.

Targeting inflammation: impact on atherothrombosis

Atherothrombosis is a worldwide epidemic accounting for an unacceptable toll of deaths and disabilities. Its pathophysiology is complex and hardly referable to a specific mechanism; however, in the last 20 years, a growing amount of evidence has demonstrated that inflammatory processes play a major role from the very beginning to the ultimate complication of atherothrombosis. These evidences are addressing a growing interest toward anti-inflammatory agents as preventive or curative treatments of atherothrombosis. At present, accumulated data are not conclusive, but strong evidence exists in favor of an anti-inflammatory positive effect for several drugs as statins or renin-angiotensin inhibitors. More conclusive data are expected from ongoing trials directly exploring the role of specific cytokines antagonists.

Inflammation and atherosclerosis: disease modulating therapies

OPINION STATEMENT

Advances in the mechanistic understanding of atheroma initiation, repair, progression, and rupture have solidified the pivotal role played by the immune system in the pathophysiology of atherosclerotic vascular disease. These mechanistic findings have been extended into humans, with a strong evidence basis for the independent association between elevated blood markers of inflammation and future cardiovascular (CV) events. Investigations with statins as well as more conventional anti-inflammatory medications provide indirect evidence to support the concept that modifying immune responses can improve CV outcomes; however, robust evidence to support the use of anti-inflammatory treatment strategies to manage atherosclerotic vascular disease is still lacking. Such evidence may emerge from a new wave of clinical trials directly exploring the effects of targeted immune modulation on CV risk. These trials will provide key additional insights into atherosclerosis and will help determine the fate of immune modulation as a new treatment strategy in atherosclerotic vascular disease.

Current approaches for TYMS polymorphisms and their importance in molecular epidemiology and pharmacogenetics

TS is critical for providing the requisite nucleotide precursors in order to maintain DNA synthesis and repair. Furthermore, it is an important target for several drugs such as 5-fluorouracil and methotrexate. However, several mechanisms of resistance to TS inhibitors have been explained as linked to TYMS overexpression. Some authors have described the relationship between genetic polymorphisms on TYMS, in particular rs34743033, rs2853542 and rs34489327, with the development of several diseases and with the clinical response to drug therapy and/or survival. Nevertheless, the obtained results described in the literature are controversial, which has lead to a search strategy to understand the impact of these polymorphisms on molecular epidemiology and pharmacogenetics. With the progress of these scientific areas, early identification of individuals at risk of disease along with improvement in the prediction of patients’ outcome will offer a powerful tool for the translation of TYMS polymorphisms into clinical practice and individualization of treatments.

Moving beyond JUPITER: will inhibiting inflammation reduce vascular event rates?

The recent JUPITER trial demonstrated that potent statin therapy reduces by 50 % the risk of heart attack and stroke among men and women with low levels of low-density lipoprotein (LDL)-cholesterol who are at increased vascular risk due to elevated levels of C-reactive protein (CRP), a biomarker of low-grade systemic inflammation. In JUPITER, both absolute risk and the absolute risk reduction with statin therapy were related to the level of CRP, whereas no such relationship was observed for LDL-C. Further, on-treatment levels of CRP and LDL-C were independently associated with residual risk, and the genetic determinants of statin-induced CRP reduction differed from the genetic determinants of statin-induced LDL reduction. Despite these data, it is impossible in any statin trial to establish whether the clinical benefits of treatment are due to LDL-reduction alone, to inflammation inhibition, or to a combination of both processes. To address the hypothesis that lowering inflammation will lower vascular event rates, two large-scale placebo controlled trials using targeted anti-inflammatory agents for the secondary prevention of myocardial infarction have been initiated. The first trial, the Canakinumab Anti-Inflammatory Thrombosis Outcomes Study (CANTOS), is evaluating whether interleukin-1β (IL-1β) inhibition as compared to placebo can reduce rates of recurrent myocardial infarction, stroke, and cardiovascular death among stable coronary artery disease patients who remain at high vascular risk due to persistent elevations of hsCRP (≥ 2 mg/L), despite contemporary secondary prevention strategies. The second trial, the Cardiovascular Inflammation Reduction Trial (CIRT) has been funded by the National Heart, Lung, and Blood Institute (NHLBI) and will evaluate whether low dose methotrexate (target dose 20 mg/week) as compared to placebo will reduce major vascular events among a group of post-myocardial infarction patients with either diabetes or metabolic syndrome, groups known to have high risk on the basis of a persistent pro-inflammatory response. Together, CANTOS and CIRT represent a core test of the inflammation hypothesis of atherothrombosis and the exploration of a potential new phase for cardiovascular therapeutics.

Propensity-adjusted association of methotrexate with overall survival in rheumatoid arthritis

OBJECTIVE

While medications used to treat rheumatoid arthritis (RA) may affect survival in RA, few studies take into account the propensity for medication use, which may reflect selection bias in treatment allocation in survival models. We undertook this study to examine the relationship between methotrexate (MTX) use and mortality in RA, after controlling for individual propensity scores for MTX use.

METHODS

We studied 5,626 RA patients prospectively for 25 years to determine the risk of death associated with MTX use, modeled in time-varying Cox regression models. We used the random forest method to generate individual propensity scores for MTX use at study entry and during followup in a time-varying manner; these scores were included in the multivariate model. We also investigated whether selective discontinuation of MTX immediately prior to death altered the risk of mortality, and we examined the association of duration of MTX use with survival.

RESULTS

During followup, 666 patients (12%) died. MTX use was associated with reduced risk of death (adjusted hazard ratio 0.30 [95% confidence interval 0.09-1.03]). Selective MTX cessation immediately before death did not account for the protective association of MTX use with mortality. Only MTX use for >1 year was associated with lower risks of mortality, but associations were not stronger with longer durations of use.

CONCLUSION

MTX use was associated with a 70% reduction in mortality in RA.

Cardiovascular disease event rates in patients with severe psoriasis treated with systemic anti-inflammatory drugs: a Danish real-world cohort study

OBJECTIVES

Psoriasis is a chronic inflammatory disorder associated with cardiovascular morbidity and mortality. Systemic anti-inflammatory drugs, including biological agents, are widely used in the treatment of patients with moderate to severe psoriasis and may attenuate the risk of cardiovascular disease events. We therefore examined the rate of cardiovascular disease events in patients with severe psoriasis treated with systemic anti-inflammatory drugs.

DESIGN, SETTING AND PARTICIPANTS

Individual-level linkage of nationwide administrative databases was used to assess the event rates associated with use of biological agents, methotrexate or other therapies, including retinoids, cyclosporine and phototherapy, in Denmark from 2007 to 2009.

MAIN OUTCOME MEASURE

Death, myocardial infarction and stroke.

RESULTS

A total of 2400 patients with severe psoriasis, including 693 patients treated with biological agents and 799 treated with methotrexate, were identified. Incidence rates per 1000 patient-years and 95% confidence intervals (CIs) for the composite endpoint were 6.0 (95% CI 2.7-13.4), 17.3 (95% CI 12.3-24.3) and 44.5 (95% CI 34.6-57.0) for patients treated with biological agents, methotrexate and other therapies, respectively. Age- and sex-adjusted hazard ratios (HRs) were 0.28 (95% CI 0.12-0.64) and 0.65 (95% CI 0.42-1.00) for patients treated with biological agents and methotrexate, respectively, using other therapies as the reference cohort. Corresponding HRs for a secondary composite endpoint of cardiovascular death, myocardial infarction and stroke were 0.48 (95% CI 0.17-1.38) and 0.50 (95% CI 0.26-0.97).

CONCLUSION

In this nationwide study of patients with severe psoriasis, systemic anti-inflammatory treatment with biological agents or methotrexate was associated with lower cardiovascular disease event rates compared to patients treated with other anti-psoriatic therapies.

Closing the loop on inflammation and atherothrombosis: why perform the CIRT and CANTOS trials?

Inflammation contributes to all phases of the atherothrombotic process, patients with elevated inflammatory biomarkers such as high-sensitivity C-reactive protein (hsCRP) have increased cardiovascular risk, and recent work directly implicates the interleukin-1 (IL-1) and interleukin-6 (IL-6) pathways in atherogenesis. Yet, it remains unknown whether targeted inhibition of inflammation will reduce cardiovascular event rates. To address directly this fundamental hypothesis, our research group has initiated two large-scale, randomized, placebo-controlled trials using targeted anti-inflammatory agents for the secondary prevention of myocardial infarction. The first trial, the Cardiovascular Inflammation Reduction Trial (CIRT), has been funded by the NHLBI and will evaluate whether low-dose methotrexate (target dose, 20 mg/wk) as compared to placebo will reduce major vascular events among a group of post-myocardial infarction patients with either diabetes or metabolic syndrome, groups known to have high risk on the basis of a persistent pro-inflammatory response. CIRT is based, in part, on observational evidence of reduced vascular event rates among those treated with methotrexate in the setting of rheumatoid arthritis or psoriatic arthritis and on the ability of methotrexate to reduce TNF, IL-6, and CRP levels. The second trial, the Canakinumab Anti-Inflammatory Thrombosis Outcomes Study (CANTOS), will evaluate whether interleukin-1β (IL-1β) inhibition as compared to placebo can reduce rates of recurrent myocardial infarction, stroke, and cardiovascular death among stable coronary artery disease patients who remain at high vascular risk due to persistent elevations of hsCRP (_2 mg/L) despite contemporary secondary prevention strategies. Canakinumab is a human monoclonal antibody that selectively neutralizes IL-1β, a pro-inflammatory cytokine that plays multiple roles in the atherothrombotic process and that undergoes activation by the NLRP3 inflammasome, a process promoted by cholesterol crystals that in turn leads directly to increased production of IL-1 and IL-6. Together, CIRT and CANTOS will enroll more than 25,000 patients worldwide and provide a fundamental test of the inflammatory hypothesis of atherothrombosis.

Molecular imaging of atherosclerosis for improving diagnostic and therapeutic development

Despite recent progress, cardiovascular and allied metabolic disorders remain a worldwide health challenge. We must identify new targets for therapy, develop new agents for clinical use, and deploy them in a clinically effective and cost-effective manner. Molecular imaging of atherosclerotic lesions has become a major experimental tool in the last decade, notably by providing a direct gateway to the processes involved in atherogenesis and its complications. This review summarizes the current status of molecular imaging approaches that target the key processes implicated in plaque formation, development, and disruption and highlights how the refinement and application of such tools might aid the development and evaluation of novel therapeutics.

Non-Fas(CD95/APO1)-mediated apoptosis of activated T cells inhibits the development of atherosclerosis

Atherosclerosis is a chronic systemic inflammatory disease. The innate and adaptive immune response might be involved in atherogenesis. Methotrexate (MTX) induces apoptosis of activated T cells by a CD95-independent pathway. The aim of this study was to analyse the effect of immunomodulation by MTX in the development of early atherosclerotic vascular lesions in an animal model. Four-week old male C57BL6 LDL-receptor-deficient mice were fed a diet rich in saturated fat (82%) and cholesterol (2.8%). Thirty animals were given a weekly intramuscular injection of MTX, establishing three subgroups: 10, 30 and 50 mg/kg. Ten further mice were used as an immunocompetent control group. Aortic thickening was significantly inhibited in all MTX-treated groups compared with the control group at 30 days (0.46 ± 0.003 mm(2) in the control group vs 0.31 ± 0.002, 0.14 ± 0.009 and 0.16 ± 0.006 mm(2) in the low-, intermediate- and high-dose group, respectively; P = 0.01) and at 60 days. The aortic lumen/total area ratio was also increased in the MTX-treated groups (0.82 ± 0.06 in the control group vs 0.88 ± 0.07, 0.86 ± 0.05 and 0.88 ± 0.04, respectively; P = 0.02). Immunosuppression by MTX inhibits the development of atherosclerotic lesions in arterial vessels in mice, which highlights the crucial role of the immune system in atherogenesis.

Endothelial dysfunction in rheumatic autoimmune diseases

Rheumatic autoimmune diseases have been associated with accelerated atherosclerosis and various types of vasculopathies. Atherosclerosis is an inflammatory condition which starts as a "response to injury" favoring endothelial dysfunction which is associated with increased expression of adhesion molecules, pro-inflammatory cytokines, pro-thrombotic factors, oxidative stress upregulation and abnormal vascular tone modulation. Endothelial dysfunction in rheumatic autoimmune diseases involves innate immune responses, including macrophages and dendritic cells expression of scavenger and toll-like receptors for modified or native LDL as well as neutrophil and complement activation, and dysregulation of adaptive immune responses, including proliferation of autoreactive T-helper-1 lymphocytes and defective function of dendritic and regulatory T cells. Specific differences for endothelial function among different disorders include: a) increased amounts of pro-atherogenic hormones, decreased amounts of anti-atherogenic hormones and increased insulin resistance in rheumatoid arthritis; b) autoantibodies production in systemic lupus erythematosus and antiphospholipid syndrome; c) smooth muscle cells proliferation, destruction of internal elastic lamina, fibrosis and coagulation and fibrinolytic system dysfunction in systemic sclerosis. Several self-antigens (i.e. high density lipoproteins, heat shock proteins, β2-glycoprotein1) and self-molecules modified by oxidative events (i.e. low density lipoproteins and oxidized hemoglobin) have been identified as targets of autoimmune responses. Endothelial dysfunction leads to accelerated atherosclerosis in rheumatoid arthritis, systemic lupus erythematosus and spondyloarthropaties whereas obliterative vasculopathy is associated with systemic sclerosis. In this paper, we will briefly review the most relevant information upon endothelial dysfunction and inflammatory mechanisms in atherosclerosis and we will summarize the similarities and differences in vascular disease patterns underlying different rheumatic autoimmune diseases.

Regulation of foam cells by adenosine

Macrophages rely on reverse cholesterol transport mechanisms to rid themselves of excess cholesterol. By reducing accumulation of cholesterol in the artery wall, reverse cholesterol transport slows or prevents development of atherosclerosis. In stable macrophages, efflux mechanisms balance influx mechanisms, and accumulating lipids do not overwhelm the cell. Under atherogenic conditions, inflow of cholesterol exceeds outflow, and the cell is ultimately transformed into a foam cell, the prototypical cell in the atherosclerotic plaque. Adenosine is an endogenous purine nucleoside released from metabolically active cells by facilitated diffusion and generated extracellularly from adenine nucleotides. Under stress conditions, such as hypoxia, a depressed cellular energy state leads to an acute increase in the extracellular concentration of adenosine. Extracellular adenosine interacts with 1 or more of a family of G protein-coupled receptors (A(1), A(2A), A(2B), and A(3)) to modulate the function of nearly all cells and tissues. Modulation of adenosine signaling participates in regulation of reverse cholesterol transport. Of particular note for the development of atherosclerosis, activation of A(2A) receptors dramatically inhibits inflammation and protects against tissue injury. Potent antiatherosclerotic effects of A(2A) receptor stimulation include inhibition of macrophage foam cell transformation and upregulation of the reverse cholesterol transport proteins cholesterol 27-hydroxylase and ATP binding cassette transporter A1. Thus, A(2A) receptor agonists may correct or prevent the adverse effects of inflammatory processes on cellular cholesterol homeostasis. This review focuses on the importance of extracellular adenosine acting at specific receptors as a regulatory mechanism to control the formation of foam cells under conditions of lipid loading.