Current Drug Targets - Volume 14, Issue 3, 2013

Myocardial infarction (MI) remains a major cause of morbidity and mortality worldwide. Rapid advances in the treatment of acute MI have significantly improved short-term outcomes in patients, due in large part to successes in preventing myocardial cell death and limiting infarct area during the time of ischemia and subsequent reperfusion. Matrix metalloproteases (MMPs) play key roles in post-MI cardiac remodeling and in the development of adverse outcomes. This review highlights the importance of MMPs in the injury and remodeling response of the left ventricle and also discusses their potential as therapeutic targets Additional pre-clinical and clinical research is needed to further investigate and understand the cardioprotective effects of MMPs inhibitors.

Varicose veins (VVs) are a common venous disease of the lower extremity characterized by incompetent valves, venous reflux, and dilated and tortuous veins. If untreated, VVs could lead to venous thrombosis, thrombophlebitis and chronic venous leg ulcers. Various genetic, hormonal and environmental factors may lead to structural changes in the vein valves and make them incompetent, leading to venous reflux, increased venous pressure and vein wall dilation. Prolonged increases in venous pressure and vein wall tension are thought to increase the expression/activity of matrix metalloproteinases (MMPs). Members of the MMPs family include collagenases, gelatinases, stromelysins, matrilysins, membrane- type MMPs and others. MMPs are known to degrade various components of the extracellular matrix (ECM). MMPs may also affect the endothelium and vascular smooth muscle, causing changes in the vein relaxation and contraction mechanisms. Endothelial cell injury also triggers leukocyte infiltration, activation and inflammation, which lead to further vein wall damage. The vein wall dilation and valve dysfunction, and the MMP activation and superimposed inflammation and fibrosis would lead to progressive venous dilation and VVs formation. Surgical ablation is an effective treatment for VVs, but may be associated with high recurrence rate, and other less invasive approaches that target the cause of the disease are needed. MMP inhibitors including endogenous tissue inhibitors (TIMPs) and pharmacological inhibitors such as zinc chelators, doxycycline, batimastat and marimastat, have been used as diagnostic and therapeutic tools in cancer, autoimmune and cardiovascular disease. However, MMP inhibitors may have side effects especially on the musculoskeletal system. With the advent of new genetic and pharmacological tools, specific MMP inhibitors with fewer undesirable effects could be useful to retard the progression and prevent the recurrence of VVs.

Preeclampsia is an important syndrome complicating pregnancy. While the pathogenesis of preeclampsia is not entirely known, poor placental perfusion leading to widespread maternal endothelial dysfunction is accepted as a major mechanism. It has been suggested that altered placental expression of matrix metalloproteinases (MMPs) may cause shallow cytotrophoblastic invasion and incomplete remodeling of the spiral arteries. MMPs are also thought to link placental ischemia to the cardiovascular alterations of preeclampsia. In fact, MMPs may promote vasoconstriction and surface receptors cleavage affecting the vasculature. Therefore, the overall goal of this review article is to provide an overview of the pathophisiology of preeclampsia, more specifically regarding the role of MMPs in the pathogenesis of preeclampsia and the potential of MMP inhibitors as therapeutic options.

A group of proteases, the matrix metalloproteinases (MMPs) are well known for their capacity to degrade extracellular matrix (ECM) proteins. Particularly MMP-2 and MMP-9 contribute to the degradation and reorganization of the ECM components and are involved in the pathophysiology of cardiovascular remodeling. Imbalanced MMP activity promotes vascular smooth muscle cells and migration and proliferation and endothelial dysfunction, thus resulting in increased cardiovascular stiffness and hypertrophy. Furthermore, MMP-2 cleaves non-ECM protein substrates including cellular receptors and intracellular proteins, thus causing cardiac and vascular dysfunction. It is now becoming clear that increased MMP activity promotes long-lasting cardiovascular structural and functional alterations in both experimental and clinical hypertension, and this alteration may contribute to sustained hypertension and its complications. Other pathogenic mechanisms including activation of the renin-angiotensin-aldosterone system and oxidative stress activate and upregulate MMPs. Therefore, MMP inhibition may prevent the deleterious consequences of hypertension to the cardiovascular system. This review article will focus on growing evidence supporting the relevance of MMPs in hypertension and the effects of MMP inhibitors. Particularly, the effects of doxycycline used as a non selective MMP inhibitor in experimental and clinical studies will be discussed.

Acute pulmonary embolism is a critical condition associated with increased mortality. Lung embolization causes acute pulmonary hypertension and right ventricle afterload. Global heart ischemia supervenes and may lead to severe shock and death. In this article, we reviewed current literature supporting the idea that abnormal matrix metalloproteinase (MMP) activity contributes to acute pulmonary embolism-induced hemodynamic changes. While low MMP levels are usually found in normal lung tissues, it is well known that inflammation and lung injury increase MMP expression and activity. This is probably due to recruitment and migration of inflammatory cells from the circulation to lung tissues. In addition, recent studies have shown increased MMP levels and activity in the right ventricle from animals with acute pulmonary embolism. Such increases in proteolytic activity were associated with increased cardiac troponin I in serum, suggesting a possible role for MMPs in cardiomyocyte injury during acute pulmonary embolism. These alterations have justified the use of doxycycline as an MMP inhibitor in acute pulmonary embolism. We review current evidence indicating that MMPs are targets in this critical condition. MMP inhibition apparently exerts antihypertensive effects and protects against cardiomyocyte injury caused by acute pulmonary embolism.

Clonazepam was initially licensed as an anti-epileptic agent, but its use in a wide variety of psychiatric conditions, including panic disorder (PD) has now been well established. This overview evaluates the current role of clonazepam alone or in combination with antidepressants and/or behavioral therapy in the treatment of PD. We review the data establishing the use of clonazepam in the treatment of PD as well as new information, particularly confirmation of longterm efficacy and safety. We also discuss a regimen for safely tapered withdrawal of clonazepam, the characteristics of the respiratory subtype of PD, and CO2-induced panic attacks as a diagnostic measure and predictor for therapeutic success. It has been shown that panic attacks can more readily be induced by CO2 in PD patients with the respiratory subtype than those with the non-respiratory subtype. More than 25 years after the first report of efficacy in PD in 1984, clonazepam, alone or combined with selective serotonin reuptake inhibitors (SSRIs) and/or behavioral therapy, remains an important therapeutic modality for the management of PD.

Kisspeptin is a 54-amino acid peptide which is encoded by the KiSS-1 gene and activates the G protein-coupled receptor GPR54. Evidence suggests that this system is a key regulator of mammalian and human reproduction. Animal studies have shown that GPR54-deficient mice have abnormal sexual development. Central and peripheral administration of kisspeptin stimulates the hypothalamic-pituitary-gonadal (HPG) axis whilst pre-administration of a gonadotrophin releasing hormone (GnRH) antagonist abolishes this effect. In humans, inactivating GPR54 mutations cause normosmic hypogonadotrophic hypogonadism whilst activation of GPR54 signalling is associated with premature puberty. In healthy human volunteers, the acute intravenous administration of kisspeptin potently increases plasma luteinising hormone (LH) levels and significantly increases plasma follicle stimulating hormone (FSH) and testosterone without side effects in both males and in females particularly in the preovulatatory phase of the menstrual cycle. In infertility due to hypothalamic amenorrhoea acute administration of kisspeptin results in stimulation of reproductive hormones. The kisspeptin/GPR54 system therefore appears to play an important role in the regulation of reproduction in humans. Hence kisspeptin has potential as a novel tool for the manipulation of the HPG axis and treatment of infertility in humans. This review discusses the evidence highlighting kisspeptin’s key role in human reproduction.

Cardiac diseases remain the leading cause of morbidity and mortality worldwide. Heart functions are regulated by autonomic nervous systems through their transmitters and modulators, binding to cell surface receptors. Among them, the cardiac M3 muscarinic acetylcholine receptor (M3-mAChR) has been studied for more than 2 decades since its first discovery in mammalian heart in 1990s. The location and pathophysiological role of M3-mAChR in the cardiovascular system have been extensively studied and many pathways involved have been uncovered. Gain- and loss-of-function studies have revealed the ubiquitous roles of M3-mAChR in physiological and pathological conditions. Recently, many new findings have been uncovered about the relationship between M3-mAChR and cardiac diseases, including cardiac ischemia, pathological cardiac hypertrophy, cardiac arrhythmias, cardiac conduction and heart failure. Furthermore, the novel potential cardioprotective role of M3-mAChR against heart injury by regulation of microRNAs (miRNAs) has been revealed in the most updated research. In this review, the current new findings on the role of M3-mAChR in heart diseases are updated, the downstream signaling pathways are summarized, perspectives and challenges of M3-mAChR as therapeutic targets are discussed.

Tacrine was the first drug approved by FDA for the treatment of Alzheimer's disease. However, its use was restricted in function of side effects observed in some patients. Investigations on the structural basis by which tacrine inhibits cholinesterases activity brought new perspectives for the design of more potent analogs with fewer side effects. This review discusses the recent advances on the development of tacrine-structure-based compounds capable to target multiple molecules involved in Alzheimer's disease. Detailed information on strategies of molecular modifications commonly used in medicinal chemistry, such as bioisosterism, hybridization, dimerization and simplification is presented as well.