Current Pharmaceutical Design - Volume 17, Issue 1, 2011

Patients with chronic inflammatory diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus, psoriasis and Crohn's disease have an increased atherosclerotic risk which cannot be explained by traditional cardiovascular risk factors alone. Inflammatory pathways are implicated in this increased vascular risk. The involvement of cytokine-related signaling pathways in inflammatory diseases has prompted the development of many therapeutic strategies aimed at their modulation to limit disease severity and progression. Whether modulation of these pathways would similarly alter the inflammatory processes related to accelerated atherosclerosis remains unknown. In this review we will focus on the role of pro-inflammatory cytokines and their inhibitors in RA, and whether they may be causal in the accelerated atherosclerosis seen in these patients.

Chronic inflammatory disorders constitute a heterogenous group of complex and multifactorial diseases, which are often associated with increased cardiovascular morbidity and mortality, independent of the established cardiovascular risk factors. In keeping with this observation, hypercoagulability is frequently observed in patients suffering from atherosclerosis, chronic obstructive pulmonary disease and rheumatoid arthritis although the physiological significance of activated coagulation remained elusive. However, the identification of protease activated receptors (PAR) seems to provide a link between coagulation activation and disease progression as their activation by coagulation factors triggers a broad range of signaling pathways relevant for chronic inflammatory disorders. In experimental animal models, anticoagulation and/or genetic ablation of PAR signaling affords protection against the perpetuation of atherosclerosis, chronic obstructive pulmonary disease and rheumatoid arthritis. It is thus tempting to speculate that targeting the coagulation-PAR axis might have clinical relevance in the setting of chronic inflammatory disorders. In the current review, we discuss the current knowledge on coagulation activation in inflammatory disorders, we discuss the relationship between atherosclerosis, chronic obstructive pulmonary disease and rheumatoid arthritis and we review the current knowledge on PAR signaling in these disorders.

Increasing evidence points to the fact that plasma HDL cholesterol levels do not always accurately predict HDL function including reverse cholesterol transport and modulation of inflammation. These functions appear to have evolved as part of our innate immune system. HDL is anti inflammatory in healthy individuals in the absence of systemic oxidative stress and inflammation. In those with chronic illnesses such as renal failure however, HDL may become dysfunctional and actually promote inflammation. HDL may be thought of as a shuttle whose size can be estimated by HDL cholesterol levels. The content of the shuttle however, is what determines the anti inflammatory potential of HDL and can change from one, supporting reverse cholesterol transport to one that is less efficient in carrying out this function. Chronic kidney disease (CKD), an inflammatory disorder, is associated with development of accelerated atherosclerosis and premature death from coronary artery disease (CAD). Patients with CKD present with dyslipidemia, oxidative stress and systemic inflammation. Among the abnormalities in lipid metabolism in these patients is reduced levels and protective capacity of HDL. Recent studies have shown that HDL from patients with end stage renal disease is not capable of preventing LDL oxidation and that it induces monocyte migration in artery wall model systems. Treatment of plasma from these patients, with an HDL mimetic peptide improved the anti inflammatory properties of patient's HDL and made LDL more resistant to oxidative modification. Animal models of kidney disease also had proinflammatory HDL and treatment with the peptide mimetic improved markers of inflammation and anti inflammatory capacity of HDL in these animals. Whether HDL mimetic peptides will have therapeutic benefit in patients with renal failure will have to be determined in clinical studies.

Rheumatoid arthritis (RA), a prototypical immune-mediated inflammatory disease, is characterized by increased cardiovascular morbidity and mortality, independent from the established cardiovascular risk factors. The chronic inflammatory state, a hallmark of RA, is considered to be a driving force for accelerated atherogenesis. Concurrent conditions that expedite the atherosclerotic process in RA involve endothelial dysfunction, dyslipidemia and procoagulant changes. These facilitating states can be reversed by retraction of the systemic inflammatory activity. Consequently, aggressive control of disease activity has been suggested to be instrumental for cardiovascular risk reduction. In the present review, we focus on these critical determinant that promote premature atherosclerosis in RA.

Abnormalities of lipid metabolism often lead to pathologic lipid accumulation in the vessel wall, oxidative and chronic inflammatory sequelae and the formation of atherosclerotic lesions, ultimately leading to clinical events. Oxidation of lipoproteins, and in particular low density lipoprotein (LDL), is a seminal even that mediates many pro-atherogenic and pro-inflammatory pathways. Many in vivo mechanisms exist to oxidize LDL, including transition metals such as divalent cations, heme, as well as a number of different enzyme systems, such as lipoxygenases, myeloperoxidase, NADPH oxidases, and nitric oxide synthases. Oxidized LDL is taken up in an unregulated fashion. By macrophages leading to foam cell formation, ultimately generating a potent pro-inflammatory milieu. Minimally modified LDL also induces proinflammatory effects in macrophages, including cytoskeletal rearrangements and macropinocytosis, generation of reactive oxygen species, survival of foam cells, reduced phagocytic capacity toward apoptotic cells, and expression of inflammatory genes, many of these effects mediated through toll-like receptor-4. Using the scientific knowledge gained from understanding these pathways, antibodies binding well-defined oxidation-specific epitopes have been generated and are being used in translational clinical applications. In particular, assays measuring oxidized phospholipids on apolipoprotein B-100 particles (OxPL/apoB) predict the presence and progression of femoral, carotid and coronary artery disease and predict new cardiovascular events independent of established risk factors. Human oxidation-specific antibodies have also been successfully used to image the extent and regression of experimental atherosclerotic lesions using nuclear and magnetic resonance imaging approaches. If validated and translated to humans, this imaging approach may provide a means to non-invasively detect, quantitate and monitor extent of atherosclerosis and potentially image high risk plaques. Further understanding of the role of oxidation of lipoproteins may allow more rational targeted diagnostic and therapeutic modalities in clinical applications.

Pentraxins are a family of evolutionarily conserved multifunctional pattern-recognition proteins characterized by a cyclic multimeric structure. Based on the primary structure of the subunit, the pentraxins are divided into two groups: short pentraxins and long pentraxins. C-reactive protein (CRP) and serum amyloid P-component (SAP) are the two short pentraxins. The prototype protein of the long pentraxin group is pentraxin 3 (PTX3). CRP and SAP are produced primarily in the liver in response to IL-6, while PTX3 is produced by a variety of tissues and cells and in particular by innate immunity cells in response to proinflammatory signals and Toll-like receptor (TLR) engagement. PTX3 interacts with several ligands, including growth factors, extracellular matrix components and selected pathogens, playing a role in complement activation and facilitating pathogen recognition by phagocytes, acting as a predecessor of antibodies. In addition, PTX3 is essential in female fertility by acting as a nodal point for the assembly of the cumulus oophorus hyaluronanrich extracellular matrix. Here we will concisely review the general properties of PTX3 in the context of the pentraxin superfamily and discuss recent data suggesting that PTX3 plays a cardiovascular protective effect. PTX3 may represent a new marker in vascular pathology which correlates with the risk of developing vascular events.

Platelet activation is a link in the pathophysiology of diseases prone to thrombosis and inflammation. Numerous platelet markers, including mean platelet volume (MPV), have been investigated in connection with both thrombosis and inflammation. This review considers MPV as a prognostic and therapeutic marker as well as the factors influencing its measurement. Established cardiovascular risk factors, such as smoking, hypertension, dyslipidemia, and diabetes, can influence MPV, depending on confounding factors. Low-grade inflammation is one such factor. Evidence, particularly derived from prospective studies and a meta-analysis, suggest a correlation between an increase in MPV and the risk of thrombosis. High MPV associates with a variety of established risk factors, cardio- and cerebrovascular disorders, and low-grade inflammatory conditions prone to arterial and venous thromboses. High-grade inflammatory diseases, such as active rheumatoid arthritis or attacks of familial Mediterranean fever, present with low levels of MPV, which reverse in the course of antiinflammatory therapy. Lifestyle modification, antihypertensive, lipid-lowering and diet therapies can also affect MPV values, but these effects need to be investigated in large prospective studies with thrombotic endpoints.

Omacetaxine mepesuccinate was originally identified more than 35 years ago and initial studies in chronic myeloid leukemia (CML) showed promising activity. It has also been studied in other hematologic and solid tumors as both a single agent and in combination with other treatments. However, the introduction of imatinib and related tyrosine kinase inhibitors (TKIs) abated the clinical development of omacetaxine as a treatment for CML. The advent of resistance to imatinib and other TKIs in CML patients (often due to the presence of an ABL mutation at position 315) has led to a revived clinical interest in omacetaxine in CML patients who failed TKIs. Here we review omacetaxine's mechanism of action (MOA) as a protein translation inhibitor, how its MOA may translate into activity in treatment of cancers, its potential to eradicate leukemia initiating cells and other cancer stem cells and the potential significance of this activity in clinical practice.

Polymersomes are one of the most interesting and versatile architectures among various self assembled systems for drug delivery. The stability and ability to load both hydrophilic and hydrophobic molecules make them excellent candidates to use as drug delivery systems. They demand for certain physicochemical parameters; especially hydrophilic to hydrophobic block ratio of copolymer to form vesicular morphologies. Different amphiphilic copolymers as well as their architectures show differences in the requirement of hydrophilic to hydrophobic block ratio to form polymersomes with various types of morphologies. This review focuses on basic aspects of polymersomes along with a series of copolymers employed for preparation of polymersomes and their potential applications as drug delivery systems.

Nucleic acid aptamers, generated by an in vitro selection procedure named SELEX (Systematic Evolution of Ligands by EXponential enrichment), have been popularly used in various biomedical implementations so far. An adaptation of the conventional SELEX practice to whole living cells was referred to as cell-SELEX, which is very promising in ample sophisticated analytical, therapeutic and diagnostic applications. The current review article would like to provide a survey of contemporary developments in cell-specific aptamers, including methodology, applications and optimization of cell-SELEX.