Atorvastatin decreases cellular proliferation and bone matrix expression in the hypercholesterolemic mitral valve

Potential therapeutic roles of 10-dehydrogingerdione and/or pentoxifylline against calcium deposition in aortic tissues of high dietary cholesterol-fed rabbits

The present study aimed to investigate the inhibitory effects of 10-dehydrogingerdione (10-DHGD) and pentoxifylline (PTX) either individually or in combined form on calcium deposition in high cholesterol diet (HCD)-fed rabbits as compared to atorvastatin (ATOR), and to clarify the underlying mechanisms. Three-months-old male New Zealand white rabbits received either normal chow or HCD for 12 weeks. The latter group was subdivided into five groups and concurrently treated either with vehicle (dyslipidemic control), ATOR, 10-DHGD, PTX or combined 10-DHGD and PTX. Blood samples and aortic tissue were collected for biochemical and histological analyses. HCD-fed rabbits displayed dyslipidemia, inflammation, atherosclerotic lesions, and calcium deposition in aortas as compared to normal group. This was associated with up-regulation of bone morphogenetic protein-2 (BMP-2), wingless-type MMTV integration site family 3A (Wnt3a) mRNA levels and osteopontin expression in their aortic tissue, along with higher serum alkaline phosphatase and osteocalcin levels. Furthermore, a marked decrease in osteoprotegerin, along with a significant increase in receptor activator of NF-κB(RANK) levels, was found in aortic tissue of dyslipidemic rabbits. 10-DHGD and PTX monotherapy significantly modulated the afore-mentioned calcification markers and attenuated aortic calcification to greater extent than ATOR. Combination of 10-DHGD and PTX exerted more anti-calcifying effect than either individual drug. Our findings suggested therapeutic roles of 10-DHGD and PTX against aortic calcium deposition in dyslipidemic rabbits, likely mediated by HDL-raising effect and attenuation of associated inflammation. Combination of 10-DHGD and PTX may represent a promising therapeutic strategy for aortic calcification associated with atherosclerosis.

Inhibition of Aortic Calcification by Policosanol in Dyslipidemic Rabbits Is Enhanced by Pentoxifylline

Policosanol (POL) is a hypocholesterolemic drug of natural origin and has been shown to reduce circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) in healthy participants. Recently, we have reported that POL can attenuate aortic calcification in diabetic dyslipidemic rats; however, the underlying mechanism is not fully elucidated. We aimed to investigate the effect of POL on aortic calcification and whether PCSK9 has a contributory role and also to examine whether the combination of POL with pentoxifylline (PTX) as anti–tumor necrosis factor α would offer additional benefits. Thirty adult male New Zealand rabbits weighing 1.5 to 2 kg were randomly assigned to 5 groups. One group received standard chow diet and served as normal control group (NC). The other 4 groups received 0.5% wt/wt cholesterol-rich diet for 12 weeks and concurrently treated with placebo, POL, PTX, or a combination of POL and PTX. Sera samples and aortic tissue were collected for biochemical measurements and histological assessment. Rabbits fed a cholesterol-rich diet demonstrated dyslipidemia, increased inflammatory state, and elevated serum levels of PCSK9, compared to the NC group. Aortic calcification was evident in dyslipidemic rabbits, represented by increased calcium deposition and osteopontin expression in aortic tissue, along with elevated serum levels of alkaline phosphatase and osteocalcin. Dyslipidemic rabbits showed a significant upregulation of wingless-type MMTV integration site family 3A and bone morphogenetic protein 2 genes in their aortic tissue. Policosanol significantly reduced circulating PCSK9 levels, suppressed calcification markers, and attenuated aortic calcification. Combination of POL with PTX alleviated aortic calcification to a greater extent than either monotherapy, which may be attributed to further suppression of PCSK9 and calcification markers. These findings suggested that POL exerted anticalcifying effect partly via inhibition of PCSK9. Combination of POL and PTX offered additional benefits and might represent a promising therapeutic option for aortic calcification.

SALTIRE-RAAVE: targeting calcific aortic valve disease LDL-density-radius theory

SALTIRE and RAAVE were the first two studies to evaluate the use of statin therapy for impeding calcific aortic valve disease (CAVD). This review presents the findings of low-density lipoprotein (LDL)-density-radius theory as tested using the combined results from the SALTIRE and RAAVE studies. Patients who received statin therapy had a greater degree of LDL cholesterol lowering, seen as the % change in LDL (47 vs 2%, p = 0.012), which in itself was significantly associated with a lesser change in aortic valve area (AVA; p < 0.001 and R(2) = 0.27). The percent change in the AVA for the treated patients was 5% and 15% for the nontreated patients (p = 0.579 and R(2) = 0.03). In summary, these published findings suggest that when applying the LDL-density-radius theory, which combines the cellular biology and the hemodynamics as defined by the continuity equation for AVA, there may be a role for lipid-lowering therapy in contemporary patients with calcific aortic valve disease (CAVD).

Myxomatous mitral valve disease bench to bedside: LDL-density-pressure regulates Lrp5

The myxomatous mitral valve is the most common form of valvular heart disease. The pathologic presentation of myxomatous mitral valve disease varies between valve thickness, degree of leaflet prolapse and the presence or absence of flail leaflets. Recent molecular biology studies have confirmed that the myxomatous changes in mitral valve prolapse equals a cartilage phenotype, which is regulated by the Lrp5 receptor. Clinically, echocardiography defines the valve pathology to determine the surgical approach to valve repair or replacement. Furthermore, the timing of surgical valve repair is controversial and is the subject of a current multicenter trial. The results will resolve the timing of whether watchful waiting versus early surgical valve repair decreases morbidity and mortality of this disease process. This review will summarize the current understanding of the cellular and hemodynamic mechanisms of myxomatous mitral valve disease, which may have future implications in the targeted therapy of this disease process.

Oxidative-mechanical stress signals stem cell niche mediated Lrp5 osteogenesis in eNOS(-/-) null mice

Calcific aortic valve disease (CAVD) is the most common indication for valve surgery in the USA. This study hypothesizes that CAVD develops secondary to Wnt3a/Lrp5 activation via oxidative-mechanical stress in eNOS null mice. eNOS(-/-) mice were tested with experimental diets including a control (n=20), cholesterol (n=20), cholesterol + Atorvastatin (n=20). After 23 weeks the mice were tested for the development of aortic stenosis by Echo, Histology, MicroCT, and RTPCR for bone markers. In vitro studies measured Wnt3a secretion from aortic valve endothelial cells and confirmed oxidative stress via eNOS activity. Anion exchange chromatography was performed to isolate the mitogenic protein. Myofibroblast cells were tested to induce bone formation. Cholesterol treated eNOS mice develop severe stenosis with an increase in Wnt3a, Lrp5, Runx2 (threefold increase (P<0.0001) in the bicuspid versus tricuspid aortic valves. Secretion of Wnt3a from aortic valve endothelium in the presence of abnormal oxidative stress was correlated with diminished eNOS enzymatic activity and tissue nitrite levels. Initial characterization of the architecture for a stem cell nice was determined by protein isolation using anion-exchange chromatography and cell proliferation via thymidine incorporation. Osteoblastogenesis in the myofibroblast cell occurred via Lrp5 receptor upregulation in the presence of osteogenic media. Targeting the Wnt3a/Lrp5 pathway in valve calcification and activation of osteogenesis is via an oxidative-mechanical stress in CAVD. These findings provide a foundation for treating this disease process by targeting the cross talk mechanism in a resident stem cell niche.

The role of Lrp5/6 in cardiac valve disease: LDL-density-pressure theory

Atherosclerosis and osteoporosis are the leading causes of mortality and morbidity in the World. Recent epidemiologic studies have demonstrated that these disease processes develop in parallel. Evidence indicates that hyperlipidemia plays a paradoxical role in both disease processes. However, the mechanism is not understood. This prospectus hypothesizes the role of lipids activate atherosclerosis within the bone and the heart to initiate the development of diseases in both of these tissues. The Prospectus on the Lrp 5/6 receptors provides a foundation for the mechanisms involved in the Lrp5/6 mediated disease biology. The LDL-Density-Pressure theory: the Role of Lrp5/6 provides a biological and a hemodynamic approach towards understanding the development of valvular heart disease and the implications in the field of bone molecular biology. This prospectus will review the current literature, provide a basis for the development of valve disease and indicate future therapeutic pathways for this disease process in the future.

A duplex oligodeoxynucleotide-dendrimer bioconjugate as a novel delivery vehicle for doxorubicin in in vivo cancer therapy

We designed a bioconjugate between duplex oligodeoxynucleotides (dODNs) and a dendrimer (DEN) and demonstrate its feasibility as a novel delivery system for doxorubicin (Dox) in animal tumor models and against cancer cells in vitro. The dODNs-DEN conjugates formed stable complexes with Dox (~184 Dox molecules per conjugate) and the resulting Dox-loaded conjugate exhibited a sustained drug release pattern both in vitro and in vivo. Pharmacokinetic studies showed that Dox-loaded dODNs-DEN conjugates were cleared from plasma much more slowly (up to 5.3h) than was free Dox (0.65h). Furthermore, tumors retained a higher amount of Dox in mice treated with the conjugate group compared to that of free Dox-treated group at the same dosage. In mice bearing 4T1 murine breast tumor allografts, the dendrimer conjugate, at a Dox concentration of 1mg/kg, was more effective than the equivalent concentration of free Dox and tumor size reduction was equivalent to that seen using 4mg/kg free Dox. We observed no severe systemic toxicity or cardiotoxicity in mice treated with the conjugate, as indicated by body weight change and heart tissue histology. These findings indicate that dODNs-DEN conjugates can be used to administer Dox with improved pharmacokinetics, lower toxicity, and an increased ability to concentrate drugs in tumors, compared with free drug, and that such conjugates are effective against tumors in vivo.

Effect of hydroxymethylglutaryl coenzyme-a reductase inhibitors on the long-term progression of rheumatic mitral valve disease

BACKGROUND

At present, no medical therapy is known to affect the progression of rheumatic mitral stenosis (MS). We sought to assess the effect of statin treatment on long-term progression of MS in a large population.

METHODS AND RESULTS

From our 20-year database, we identified all patients with rheumatic MS with > or =2 echocardiographies > or =1 year apart. Exclusion criteria were previous intervention on the mitral valve, more than moderate aortic regurgitation, or symptoms at first examination. The study sample included 315 patients (mean age, 61+/-12 years; 224 women); 35 patients (11.1%) were treated with statins, and 280 (88.9%) were not. Mean follow-up period was 6.1+/-4.0 years (range, 1 to 20). The rate of decrease in mitral valve area was significantly lower in the statin group compared with the untreated group (0.027+/-0.056 versus 0.067+/-0.082 cm(2)/y; P=0.005). The annualized change in mean transmitral gradient was lower in statin-treated patients (0.20+/-0.59 versus 0.58+/-0.96 mm Hg/y; P=0.023). The prevalence of fast MS progression (annual change in mitral valve area >0.08 cm(2)) was significantly lower in the statin group (P=0.008). An increase in systolic pulmonary artery pressure of >10 mm Hg was found in 17% of patients in the statin group versus 40% of untreated patients (P=0.045).

CONCLUSIONS

Our study shows a significantly slower progression of rheumatic MS in patients treated with statins. These findings could have an important impact in the early medical therapy of patients with rheumatic heart disease.

Mechanisms of aortic valve calcification: the LDL-density-radius theory: a translation from cell signaling to physiology

Recent epidemiologic studies have revealed the risk factors associated for vascular atherosclerosis, including the male sex, smoking, hypertension, and elevated serum cholesterol, similar to the risk factors associated with the development of AV stenosis. An increasing number of models of experimental hypercholesterolemia demonstrate features of atherosclerosis in the AV, which are similar to the early stages of vascular atherosclerotic lesions. Experimental and clinical studies demonstrate that the hypercholesterolemic AV develops an atherosclerotic lesion which is proliferative and expresses high levels of osteoblast bone markers which mineralize over time to form bone. Calcification, the end-stage process of the disease, is necessary to understand as a prognostic indicator in the modification of this cellular process before it is too late. In summary, these findings suggest that medical therapies may have a potential role in patients in the early stages of this disease process to slow the progression to severe aortic stenosis and to delay the timing of the need for surgery. The translation of these experimental studies to clinical practice will be important to understand the potential for medical therapy for this disease process.

Medical therapy for rheumatic heart disease: is it time to be proactive rather than reactive?

Rheumatic Heart Disease (RHD) is well known to be an active inflammatory process which develops progressive calcification and leaflet thickening over time. The potential for statin therapy in slowing the progression of valvular heart disease is still controversial. Retrospective studies have shown that medical therapy is beneficial for patients with calcific aortic stenosis and recently for rheumatic valve disease. However, the prospective randomized clinical trials have been negative to date. This article discusses the epidemiologic risk factors, basic science, retrospective and prospective studies in valvular heart disease and a future clinical trial to target RHD with statin therapy to slow the progression of this disease. Recent epidemiological studies have revealed the risk factors associated with valvular disease include male gender, smoking, hypertension and elevated serum cholesterol and are similar to the risk factors for vascular atherosclerosis. An increasing number of models of experimental hypercholesterolemia demonstrate features of atherosclerosis in the aortic valve (AV), which are similar to the early stages of vascular atherosclerotic lesions. Calcification, the end stage process of the disease, must be understood as a prognostic indicator in the modification of this cellular process before it is too late. This is important in calcific aortic stenosis as well as in rheumatic valve disease. There are a growing number of studies that describe similar pathophysiologic molecular markers in the development of rheumatic valve disease as in calcific aortic stenosis. In summary, these findings suggest that medical therapies may have a potential role in patients in the early stages of this disease process to slow the progression of RHD affecting the valves. This review will summarize the potential for statin therapy for this patient population.

Reassessment of statins to retard the progression of aortic stenosis

Aortic valve stenosis is the most common indication for surgical valve replacement in the United States and Europe. For years, this valve lesion was thought to be a passive degenerative disease. In the past decade there have been a number of studies indicating that the risk factors for valvular heart disease are the same as those for vascular atherosclerosis. This correlation with atherosclerosis and valvular heart disease indicates that medical therapy may have a role in slowing the progression of this disease process. Currently, the retrospective studies indicate that medical therapy slows the progression of this disease. The prospective data are currently conflicting in terms of the final outcomes for treating the disease process with medical therapy. This review outlines the growing number of clinical studies implicating the potential for medical therapy in this patient population.

Mitral insufficiency and its different aetiologies: old and new insights for appropriate surgical indications and treatment

Mitral insufficiency, as many other fields in medicine, has witnessed profound changes in terms of knowledge, diagnostic process and therapeutic options. Mitral valve reconstruction has become the treatment of choice in the presence of a regurgitant valve, although numerous preoperative and operative clues have been shown to predict less satisfactory results of valve repair in the long term, calling for a careful revision of postoperative data and search for novel techniques of valve repair or reconsider valve replacement as an acceptable therapy in peculiar cases. Old scenarios, like rheumatic valve disease or acute endocarditis, are continuously under reassessment in an attempt to distinguish patient subsets amenable to tailored therapies, whereas new fields of intervention, like dilated cardiomyopathy, or better appraisal of pathophysiological mechanisms, like ischaemic mitral insufficiency, are emerging and represent new indications for surgical solutions. The most recent advances in the understanding of how some aetiologies and related mechanisms of mitral insufficiency exert substantial influence on the postoperative results represent new tools in the guidance of a more appropriate surgical decision-making.

Human degenerative valve disease is associated with up-regulation of low-density lipoprotein receptor-related protein 5 receptor-mediated bone formation

OBJECTIVES

The goal of this research was to define the cellular mechanisms involved in myxomatous mitral valve disease and calcific aortic valve disease and to redefine the term degenerative valve disease in terms of an active cellular biology.

BACKGROUND

"Degenerative" valvular heart disease is the primary cause of regurgitant and stenotic valvular lesion in the U.S. However, the signaling pathways are not known. We hypothesize that valve degeneration occurs due to an osteoblastic differentiation process mediated by the low-density lipoprotein receptor-related protein 5 (Lrp5) signaling pathway to cause valve thickening.

METHODS

We examined human diseased valves: myxomatous mitral valves (n = 23), calcified tricuspid aortic valves (n = 27), calcified bicuspid aortic valves (n = 23), and control tissue from mitral and aortic valves (n = 40). The valves were examined by reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry for signaling markers important in osteoblast differentiation: Sox9 and Cbfa1 (transcription factors for osteoblast differentiation); Lrp5 and Wnt3 (osteoblast differentiation signaling marker), osteopontin and osteocalcin (osteoblast endochrondral bone matrix proteins), and proliferating cell nuclear antigen (a marker of cell proliferation). Cartilage development and bone formation was measured by Alcian blue stain and Alizarin red stain. Computed Scano MicroCT-40 (Bassersdorf, Switzerland) analysis measured calcium burden.

RESULTS

Low-density lipoprotein receptor-related protein 5, osteocalcin, and other osteochrondrogenic differentiation markers were increased in the calcified aortic valves by protein and gene expression (p > 0.001). Sox9, Lrp5 receptor, and osteocalcin were increased in myxomatous mitral valves by protein and gene expression (p > 0.001). MicroCT was positive in the calcified aortic valves and negative in the myxomatous mitral valves.

CONCLUSIONS

The mechanism of valvular heart disease involves an endochondral bone process that is expressed as cartilage in the mitral valves and bone in the aortic valves. Up-regulation of the Lrp5 pathway may play a role in the mechanism for valvular heart disease.