Treating patients with hypertriglyceridaemia saves lives: triglyceride revisited

Inhibition of cytokine-induced IkappaB kinase activation as a mechanism contributing to the anti-atherogenic activity of tilianin in hyperlipidemic mice

Tilianin has been shown to down-regulate TNF-alpha induced expression of vascular cell adhesion molecules in endothelial cells. In this study, we examined the anti-atherogenic effects and molecular mechanism of tilianin in vitro and in vivo. Male low-density lipoprotein receptor null mice (Ldlr-/-) fed a high cholesterol diet showed significant increases in the size of atherosclerotic lesions, as well as increased plasma levels of total cholesterol, triglycerides, and the pro-inflammatory cytokines TNF-alpha and IL-1beta, when compared with Ldlr-/- mice fed a normal diet. Mice fed the high cholesterol diet supplemented with tilianin showed significantly reduced lesion sizes and reductions in cytokine levels, without significant changes in serum cholesterol levels. Primary cultured peritoneal macrophages from Ldlr-/- mice showed increased level of TNF-alpha andIL-1beta mRNA in response to treatment with lipopolysaccharide; these increases were inhibited by co-treatment with tilianin. Moreover, tilianin inhibited NF-kappaB activation, as determined by electrophoretic mobility shift and NF-kappaB promoter assays. Upstream of NF-kappaB activation, tilianin inhibited IkappaB kinase activation and the subsequent phosphorylation and degradation of IkappaBalpha protein. These results suggest that tilianin ameliorates atherosclerosis by inhibiting the production of the NF-kappaB-dependent pro-inflammatory cytokines, TNF-alpha and IL-1beta, via the inhibition of IkappaB kinase activity.

KR‐31378 ameliorates atherosclerosis by blocking monocyte recruitment in hypercholestrolemic mice

The recruitment of monocytes into the artery wall is a crucial early step in atherogenesis. A novel compound, KR-31378, has been shown to be a neuroprotective agent for ischemia-reperfusion damage in rat brain via its potent antioxidant and antiapoptotic actions. Here, we report the effects of this compound on atherogenesis and possible mechanisms of action. In Ldlr knockout mice fed with a high-fat, high-cholesterol diet, treatment with KR-31378 significantly inhibited fatty streak formation and macrophage accumulation. To address the possibility that KR-31378 may influence the initial stages of atherogenesis, we examined its effect on the adhesion and migration of monocytes to endothelial cells stimulated with tumor necrosis factor-alpha. KR-31378 decreased the adhesion in a dose-dependent manner. The observed decreases in cell adhesion and migration correlated with KR-31378-mediated down-regulation of vascular cell adhesion molecule-1 (VCAM-1) and interleukin (IL)-8. Nuclear factor-kappaB (NF-kappaB) is known to regulate the expression of adhesive and chemotactic molecules including VCAM-1 and IL-8. Indeed, transient transfection experiments, electrophoretic mobility shift assay, and IkappaB degradation assay showed that KR-31378 decreased NF-kappaB activation. These results indicate that KR-31378 potently reduces fatty streak formation by inhibiting NF-kappaB-dependent cellular adhesion and chemotactic molecule expression, which are crucial to monocyte infiltration into the arterial wall during the early stages of atherogenesis.

Gene transfer to induce angiogenesis in myocardial and limb ischaemia

Stimulation of angiogenesis/arteriogenesis by gene transfer methods offers hope for treating patients with myocardial and peripheral limb ischaemia who are not candidates for standard revascularisation procedures. Preclinical studies showed that adenoviral and plasmid vectors encoding various angiogenic cytokines were capable of inducing functionally significant angiogenesis in vitro and in animal models of chronic myocardial ischaemia. Early clinical studies using VEGF121-, FGF-4- and VEGF165-encoding vectors showed a reasonable safety profile with promising results. However, significant advances in vector technology including regulatable and longer-term expression, delivery strategies (local and organ/tissue specific), clinical trial design, and outcome measure development are needed before this investigational treatment becomes reality.

Gene transfer for angiogenesis in coronary artery disease

Angiogenesis is a promising novel therapeutic strategy to provide new venues for blood flow in patients with severe ischemic heart and peripheral vascular disease, who are not candidates for standard revascularization strategies. We describe the underlying mechanisms involved in physiologic and therapeutic angiogenesis, underscoring the relative importance of vasculogenesis, angiogenesis, and arteriogenesis. We then present the various gene transfer vectors including plasmid, viral, and cell-based vectors, and various delivery modalities. The available preclinical data are presented, followed by a description of preliminary clinical experience, with an emphasis on the preliminary nature of these results, which address safety and not efficacy. Finally, we discuss the promises and pitfalls of clinical angiogenesis and gene transfer studies, stressing the importance of proper design of clinical trials and adequate protection of research subjects.

Disorders of lipid metabolism in patients with HIV disease treated with antiretroviral agents: frequency, relationship with administered drugs, and role of hypolipidaemic therapy with bezafibrate

OBJECTIVES

To assess the correlation between antiretroviral treatment and dyslipidaemia in HIV-infected patients, and the role of bezafibrate as a lipid-lowering agent.

METHODS

We retrospectively compared serum lipid levels of five groups of 40 patients, each of them treated with either saquinavir hard gel, indinavir, or ritonavir (associated with two nucleoside analogues), or dual nucleoside reverse transcriptase inhibitors (NRTI) with or without a non-nucleoside reverse transcriptase inhibitor (NNRTI), or not treated with antiretrovirals, randomly selected from nearly 1000 HIV-infected patients followed-up for >or= 12 months, while on the relevant therapy. Hypertriglyceridaemia was defined by triglyceride levels >or= 172 mg/dl, and hypercholesterolaemia by cholesterol levels >or= 200 mg/dl. All patients with triglyceridaemia > 300 mg/dl and cholesterolaemia > 220 mg/dl for at least 6 months, and unresponsive to a >or= 3-month diet, started bezafibrate (400 mg/day), and were prospectively followed-up at a <or= 3-month interval, evaluating both efficacy and tolerability of the hypolipidaemic treatment, provided that they did not change their protease inhibitor treatment for reasons other than metabolic abnormalities.

RESULTS

Hypertrygliceridaemia occurred in 75 patients out of 200 (37.5%), but was significantly more frequent and severe with ritonavir vs. indinavir (P<0.001), and in subjects given indinavir vs. all remaining patients (either treated or not) (P<0.001), while isolated saquinavir use was associated with higher tri glyceride levels than NRTI-NNRTI treatment alone, or no antiretroviral therapy (P<0.03). Hypercholesterolaemia was found in 27 subjects (13.5%), and a significantly higher frequency and severity was shown in patients treated with indinavir and ritonavir vs. saquinavir, NRTI-NNRTI, and no anti-HIV therapy (P<0.05 to P<0.001). No appreciable difference was found between patients undergoing NRTI-NNRTI and untreated controls, for all evaluated variables. Bezafibrate was administered once daily for 6-18 months to 49 patients with elevated and diet-resistant hyperlipidaemia due to ritonavir or indinavir (27 and 22 subjects, respectively), and reduced triglyceride and cholesterol levels by 35% and 25%, respectively over 6 months, without differences between the underlying protease inhibitor regimen. Thirty-three patients (67.3%) reached a normal triglyceridaemia after 6-9 months, and normal cholesterol levels were obtained in all subjects. Bezafibrate proved safe and well tolerated.

CONCLUSIONS

Careful monitoring of the serum lipid profile is needed during antiretroviral therapy, including protease inhibitors, to identify the need for a diet and/or an hypolipidaemic treatment, and to prevent clinical sequelae related to long-term dyslipidaemia. Specific guidelines for the management of disorders of lipid metabolism in HIV-infected patients are needed.

Hypertriglyceridemia and the fibrate trials

Epidemiological studies published since 1996 have established that hypertriglyceridemia can predict risk of cardiovascular disease in a manner statistically independent of HDL cholesterol. Nevertheless, the relationship of concentrations of plasma triglycerides to risk of cardiovascular disease remains less than straightforward, partly because triglycerides are carried in lipoproteins of different atherogenicity, partly because hypertriglyceridemia is associated with non-lipid atherogenic and thrombogenic processes. For example, the association of highest risk of cardiovascular disease to moderate rather than to severe hypertriglyceridemia can be understood in terms of the distribution of triglycerides between different classes of plasma lipoproteins. It is counter-intuitive to most clinicians, however, and hence it can result in the misdirection of clinical efforts including drug therapy. Fibrates lower plasma triglycerides, and raise HDL, efficiently and with few immediate side-effects. Central to their mode of action is activation of certain nuclear receptors in cells. There is no necessary connection, however, between that fascinating biochemistry and clinical benefit as defined by reductions in rates of death by coronary artery disease. A review of trials of cholesterol-lowering by diet and drugs, published between 1966 and 1996, included 12 trials of therapy with fibrates or placebo in more than 21000 patients. Overall, these trials indicated no benefit in terms of reduction in risk of coronary deaths. The period since 1996 has seen the publication of four additional trials of treatment of 6144 patients with fibrates or placebo. Two of them were major trials. The VA-HIT was very encouraging, because treatment with gemfibrozil produced a signficant reduction in the combined incidence of fatal and non-fatal coronary events. There was no significant reduction in coronary deaths, however. The results of BIP were frankly disappointing, because they demonstrated no significant effect of treatment with bezafibrate on either the primary end-point of the trial or on rates of coronary death. Clinical indications for the use of fibrates can obviously not be based on biochemical insights, however intriguing in their own right, but they have also not been satisfactorily defined by the randomized clinical trials published to date. Hope remains, however, that some clarification will result from ongoing trials of fibrate treatment of patients with type II diabetes.

Management of dyslipidemia in patients with HIV disease

The epidemiological, etiopathogenetic, laboratory and clinical features of serum lipid abnormalities occurring in the course of HIV disease are still poorly understood (especially when the supporting role of single antiretroviral compounds is considered), while limited literature data are to date available regarding the management of HIV-related dyslipidemia, as well as the efficacy and safety of dietary-exercise programs, and that of selected hypolipidemic agents. At this time, a careful monitoring of serum lipid profile is needed during combination antiretroviral therapy including protease inhibitors, in order to suggest a diet and hypolipidemic treatment when applicable, and to prevent clinical sequelae related to long-term dyslipidemia. The selection of an appropriate hypolipidemic agent is difficult, since no controlled studies are available in this field, and possibly increased risks of pharmacologic interactions, toxicity and impaired patient's adherence should be taken into consideration. Waiting for specific guidelines for the treatment of hypertriglyceridemia and hypercholesterolemia in the setting of HIV infection, all available literature reports dealing with the management of HIV-associated hyperlipidemia are briefly discussed, on the basis of personal clinical experience.