Rapamycin in cardiovascular medicine

Carrier-Free Trehalose-Based Nanomotors Targeting Macrophages in Inflammatory Plaque for Treatment of Atherosclerosis

Inducing autophagy of macrophages to improve abnormal lipid metabolism is an important way to treat atherosclerosis (AS). Yet, the current application of the mammalian target of rapamycin (mTOR)-dependent autophagy inducers is limited by the side effects and lack of targeting and low biological availability. Herein, a kind of nitric oxide (NO)-driven carrier-free nanomotor based on the reaction between trehalose (Tr, one of the mTOR-independent autophagy inducers), L-arginine (Arg), and phosphatidylserine (PS) is reported. The developed nanomotors use NO as the driving force, which is generated from the reaction between Arg and excessive reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) specifically presenting in the AS microenvironment. The high expression of ROS and iNOS in the AS site can be used as chemoattractants to induce chemotaxis behavior of the nanomotors to achieve the first-step targeting an AS plaque. Subsequently, the "eat me" signal sent by PS is exploited to precisely target to the macrophages in the AS plaque, realizing the plaque-macrophage-targeted effect by this step-by-step strategy. In vitro and in vivo results confirm that the introduction of the concept of carrier-free nanomotors has greatly improved the biological availability of trehalose (the dose can be reduced from 2.5 g kg^-1 in previous reports to 0.01 g kg^-1 in this work). Particularly, consumed ROS and the production of NO during the targeting process also play positive roles, in which the former regulates the M2 polarization of macrophages and the latter promotes the reconstruction of an endothelial barrier, which contributes to the multilink treatment of AS.

Crosstalk between the Akt/mTORC1 and NF-κB signaling pathways promotes hypoxia-induced pulmonary hypertension by increasing DPP4 expression in PASMCs

Abnormal wound healing by pulmonary artery smooth muscle cells (PASMCs) promotes vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Increasing evidence shows that both the mammalian target of rapamycin complex 1 (mTORC1) and nuclear factor-kappa B (NF-κB) are involved in the development of HPH. In this study, we explored the crosstalk between mTORC1 and NF-κB in PASMCs cultured under hypoxic condition and in a rat model of hypoxia-induced pulmonary hypertension (HPH). We showed that hypoxia promoted wound healing of PASMCs, which was dose-dependently blocked by the mTORC1 inhibitor rapamycin (5-20 nM). In PASMCs, hypoxia activated mTORC1, which in turn promoted the phosphorylation of NF-κB. Molecular docking revealed that mTOR interacted with IκB kinases (IKKs) and that was validated by immunoprecipitation. In vitro kinase assays and mass spectrometry demonstrated that mTOR phosphorylated IKKα and IKKβ separately. Inhibition of mTORC1 decreased the level of phosphorylated IKKα/β, thus reducing the phosphorylation and transcriptional activity of NF-κB. Bioinformatics study revealed that dipeptidyl peptidase-4 (DPP4) was a target gene of NF-κB; DPP4 inhibitor, sitagliptin (10-500 μM) effectively inhibited the abnormal wound healing of PASMCs under hypoxic condition. In the rat model of HPH, we showed that NF-κB activation (at 3 weeks) was preceded by mTOR signaling activation (after 1 or 2 weeks) in lungs, and administration of sitagliptin (1-5 mg/kg every day, ig) produced preventive effects against the development of HPH. In conclusion, hypoxia activates the crosstalk between mTORC1 and NF-κB, and increased DPP4 expression in PASMCs that leads to vascular remodeling. Sitagliptin, a DPP4 inhibitor, exerts preventive effect against HPH.

Randomized comparison of the Nobori biolimus A9-eluting stent with the sirolimus-eluting stent in patients with stenosis in native coronary arteries

OBJECTIVES

The aim of this randomized-controlled trial is to compare biolimus A9-eluting stent (Nobori) to sirolimus eluting stent (Cypher).

BACKGROUND

The Nobori coronary stent is coated only abluminally with a biodegradable polymer, poly-lactic acid, and the antiproliferative agent biolimus A9. This stent has been studied in randomized trials versus Taxus Express and Taxus Liberte and showed noninferiority and superiority for in-stent late loss. This is the first randomized trial of Nobori stent versus Cypher stent.

METHODS

We conducted a randomized (3:2), controlled trial comparing Nobori and Cypher, in 335 patients (198 Nobori and 137 Cypher) at 15 centers in Japan. Patients with de-novo lesions in up to two native coronary arteries were considered for enrollment. The primary endpoint was freedom from target vessel failure (TVF), a composite of cardiac death, myocardial infarction, and target vessel revascularization at 9 months.

RESULTS

At 9 months, the primary endpoint of freedom from TVF was 92.6% in Nobori and 93.8% in Cypher arm (noninferiority test P < 0.001). As main secondary endpoints, the in-stent late loss was 0.12 ± 0.30 mm and 0.14 ± 0.34 mm in Nobori and Cypher stents, respectively. Target lesion revascularization was 0.5% in Nobori and 3.9% in Cypher treated patients (P = 0.04). Definite and probable stent thromboses were not recorded in any patient.

CONCLUSIONS

Despite the relatively small number of patients, this well controlled clinical trial confirmed the primary hypothesis of non-inferiority of the Nobori biolimus A9-eluting stent to the Cypher sirolimus-eluting stent for freedom from TVF. Both stents showed excellent midterm results.

Cilostazol Inhibits Vascular Smooth Muscle Cell Proliferation and Reactive Oxygen Species Production through Activation of AMP-activated Protein Kinase Induced by Heme Oxygenase-1

Cilostazol is a selective inhibitor of phosphodiesterase 3 that increases intracellular cAMP levels and activates protein kinase A, thereby inhibiting vascular smooth muscle cell (VSMC) proliferation. We investigated whether AMP-activated protein kinase (AMPK) activation induced by heme oxygenase-1 (HO-1) is a mediator of the beneficial effects of cilostazol and whether cilostazol may prevent cell proliferation and reactive oxygen species (ROS) production by activating AMPK in VSMC. In the present study, we investigated VSMC with various concentrations of cilostazol. Treatment with cilostazol increased HO-1 expression and phosphorylation of AMPK in a dose- and time-dependent manner. Cilostazol also significantly decreased platelet-derived growth factor (PDGF)-induced VSMC proliferation and ROS production by activating AMPK induced by HO-1. Pharmacological and genetic inhibition of HO-1 and AMPK blocked the cilostazol-induced inhibition of cell proliferation and ROS production.These data suggest that cilostazol-induced HO-1 expression and AMPK activation might attenuate PDGF-induced VSMC proliferation and ROS production.

Thrombotic events in patients with cancer receiving antiangiogenesis agents

Tumor-associated neoangiogenesis has recently become a suitable target for antineoplastic drug development. In this overview, we discuss specific drug-associated hemostatic complications, the already known pathogenetic mechanisms involved, and the effect of varying antithrombotic strategies. Multiple agents with angiogenic inhibitory capacity (thalidomide, lenalidomide, bevacizumab, sunitinib, sorafenib, and sirolimus) have obtained US Food and Drug Administration approval, and many others have entered clinical trials. Arterial and venous thromboembolism and hemorrhage have emerged as significant toxicities associated with the use of angiogenesis inhibitors. We present a detailed analysis of the literature on thrombotic complication of antiangiogenic drugs. Close attention to hemostatic complications during antiangiogenic treatment is warranted. Further studies are required to better understand the pathophysiologic mechanisms involved and to define a safe prophylactic strategy.

Immunosuppressive agents: effects on glucose and lipid metabolism

Immunosuppressive therapies are critical elements in successful organ transplantation. Although immunosuppressant drugs are essential in preventing graft rejection and graft maintenance after transplantation, their use is complicated by adverse effects, many being detrimental to graft and even patient long-term survival. Commonly used agents are associated with dysregulated glucose metabolism and dyslipidemia. This article focuses on the effects of immunosuppressive agents on glucose and lipid metabolism. Adrenal effects of these drugs, where known, also are discussed.

Alterations in serum neopterin correlate with thrombolysis in myocardial infarction risk scores in acute coronary syndromes

OBJECTIVES

Using serum neopterin as a marker of macrophage activation, we sought to examine the relationship between serum neopterin levels, thrombolysis in myocardial infarction (TIMI) risk scores, and how different treatments of acute coronary syndromes affect change in neopterin.

METHODS

We examined serum neopterin concentrations at presentation and 72 h after treatment in 70 patients with acute coronary syndromes (35 with medical therapy, 25 with uncoated coronary stents, and 10 received rapamycin-eluting stents) using a commercially available immunoassay. Serum neopterin levels were determined for 36 patients with stable coronary artery disease. TIMI risk scores were calculated when appropriate (n=58).

RESULTS

Serum neopterin had a strong correlation with the TIMI risk score on admission (P<0.0001). The mean baseline neopterin levels in patients with acute coronary syndromes stratified with TIMI scores between 1 and 7 were the following: patients with TIMI 1 scores had a level of 3.3+/-0.4 nmol/l, TIMI 2 patients 4.6+/-0.6 nmol/l, TIMI 3 patients 5.5+/-1.4 nmol/l, TIMI 4 patients 7.5+/-2.4 nmol/l, TIMI 5 patients 10.8+/-3.3 nmol/l, TIMI 6 patients 17.5+/-4.0 nmol/l, and TIMI 7 patients 23.0+/-7.1 nmol/l. Mean changes in serum neopterin were significantly higher for the uncoated stent group than for each of the other three groups (P<0.05).

CONCLUSIONS

Serum neopterin concentrations have a high correlation with TIMI risk scores and may represent a marker useful in stratifying patients with acute coronary syndromes. Our results also suggest that the use of uncoated coronary stents results in macrophage activation not found with other treatment modalities.

Pharmacological basis of different targets for the treatment of atherosclerosis

The development of atherosclerotic plaque is a highly regulated and complex process which occurs as a result of structural and functional alterations in endothelial cells, smooth muscle cells (SMCs), monocytes/macrophages, T-lymphocytes and platelets. The plaque formation in the coronary arteries or rupture of the plaque in the peripheral vasculature in latter stages of atherosclerosis triggers the onset of acute ischemic events involving myocardium. Although lipid lowering with statins has been established as an important therapy for the treatment of atherosclerosis, partially beneficial effects of statins beyond decreasing lipid levels has shifted the focus to develop newer drugs that can affect directly the process of atherosclerosis. Blockade of renin angiotensin system, augmentation of nitric oxide availability, reduction of Ca(2+) influx, prevention of oxidative stress as well as attenuation of inflammation, platelet activation and SMC proliferation have been recognized as targets for drug treatment to control the development, progression and management of atherosclerosis. A major challenge for future drug development is to formulate a combination therapy affecting different targets to improve the treatment of atherosclerosis.

Immunomodulation of atherosclerosis: implications for vaccine development

A number of studies have shown activation of the immune system throughout various stages of atherosclerosis. Recent observations have suggested that activation of immune responses may promote atherosclerosis on one hand by inducing and perpetuating arterial inflammation, whereas on the other hand, selective activation of certain immune functions may inhibit atherosclerosis and arterial inflammation. These observations suggest the possibility that selective suppression of proatherogenic immune responses or selective activation of antiatherogenic immune responses may provide new approaches for atherosclerosis prevention and treatment. Several antigens activating immune responses affecting development of atherosclerosis have been identified. These immune responses may be modulated by presenting the antigens together with different types of adjuvants as well as through the route of administration. In this review, we summarize recent experimental studies using immunomodulatory approaches for treatment of atherosclerosis.

Testosterone concentrations and sirolimus in male renal transplant patients

Sirolimus damages the testes in animals; however, human data are sparse. We conducted a case-control study to obtain further insight into this issue and compared testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin concentrations in matched renal transplant patients who did or did not receive sirolimus. We found that testosterone values were lower (11.2 +/- 6.3 nmol/L vs. 15.5 +/- 7.7 nmol/L, p < 0.05), in 28 sirolimus-treated patients, compared to 28 non-sirolimus-treated controls. Furthermore, these patients more commonly had testosterone concentrations that were below our reference value for normal men. In contrast, FSH and LH concentrations were higher while prolactin levels were not different. These data are consistent with sirolimus-related testosterone suppression and suggest a need for further studies.