Doxycycline decreases amyloidogenic light chain-induced autophagy in isolated primary cardiac myocytes.

BACKGROUND: Immunoglobulin light chain (AL) cardiac amyloidosis is characterized by extracellular deposition of amyloid fibrils in the heart and is potentially fatal. Untreated, it manifests clinically as heart failure with a precipitous decline and a median survival of <6 months. AL cardiac amyloidosis is associated with impaired extracellular matrix homeostasis in the heart with increased matrix metalloproteinase (MMP) levels. This commmunication provides novel insights into a potential role for doxycycline, a non-selective MMP inhibitor in AL cardiac amyloidosis. METHODS/RESULTS: Adult rat ventricular myocytes stimulated with AL (obtained from cardiac amyloidosis patients) increased MMP-2 and MMP-9 activities (P < .05); the expression of autophagy marker microtubule associated protein 1 LC-3 isoform II (LC3-II) (P < .01), and the autophagy-related proteins ATG-4B (P < .05) and ATG-5 (P < .05) as compared to untreated cardiomyocytes. Doxycycline abrogated MMP activities (P < .0001) and decreased AL-induced autophagy via ATG-5 (P < .05). CONCLUSIONS: These in vitro studies demonstrated that doxycycline, in addition to inhibiting MMP, also modulated AL-induced autophagy in cardiomyocytes and provide potential insights for future therapeutic targets for AL-induced proteotoxicity. Novel therapies for cardiotoxicity and heart failure in AL cardiac amyloidosis remain an important unmet need.

Supplementation with an insoluble fiber obtained from carob pod (Ceratonia siliqua L.) rich in polyphenols prevents dyslipidemia in rabbits through SIRT1/PGC-1α pathway.

PURPOSE: To investigate the mechanism implicated in the effect of an insoluble fiber (obtained from carob pod) rich in polyphenols (IFCP) in lipid metabolism in the liver. METHODS: Male New Zealand rabbits were fed with the following diets for 8 weeks: control diet (CT group), dyslipidemic diet supplemented with 0.5% cholesterol + 14% coconut oil (DL group) and dyslipidemic diet containing 0.5% cholesterol + 14% coconut oil plus 3% IFCP (DL + IFCP group). RESULTS: Dyslipidemic diet with IFCP was able to reduce development of mixed dyslipidemia, liver relative weight and collagen I protein expression compared to DL rabbits. Analyses of the main enzymes implicated in cholesterol and triglycerides metabolism revealed that IFCP increased hepatic concentration of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and cytochrome P450, family 7, subfamily a, polypeptide 1C (CYP7A1) (82.34, 114.42%, respectively) as well as protein expression of LDL receptor (42.48%) in DL rabbits. Importantly, IFCP also increased hepatic lipase (HL) levels (91.43%) and decreased glycerol phosphate acyltransferase (GPAT) and sterol regulatory element-binding protein 1C (SREBP1c) liver expression levels (20.38 and 41.20%, respectively). Finally, sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α) hepatic expression increased in DL + IFCP group compared with DL (159.81 and 48.00%, respectively). CONCLUSIONS: These findings show that IFCP is able to abrogate the deleterious effects of hepatic dyslipidemia by modulating SIRT1 and PGC-1α pathways.

Cardiac macrophages promote diastolic dysfunction.

Macrophages populate the healthy myocardium and, depending on their phenotype, may contribute to tissue homeostasis or disease. Their origin and role in diastolic dysfunction, a hallmark of cardiac aging and heart failure with preserved ejection fraction, remain unclear. Here we show that cardiac macrophages expand in humans and mice with diastolic dysfunction, which in mice was induced by either hypertension or advanced age. A higher murine myocardial macrophage density results from monocyte recruitment and increased hematopoiesis in bone marrow and spleen. In humans, we observed a parallel constellation of hematopoietic activation: circulating myeloid cells are more frequent, and splenic 18F-FDG PET/CT imaging signal correlates with echocardiographic indices of diastolic dysfunction. While diastolic dysfunction develops, cardiac macrophages produce IL-10, activate fibroblasts, and stimulate collagen deposition, leading to impaired myocardial relaxation and increased myocardial stiffness. Deletion of IL-10 in macrophages improves diastolic function. These data imply expansion and phenotypic changes of cardiac macrophages as therapeutic targets for cardiac fibrosis leading to diastolic dysfunction.

Relevance of SGK1 in structural, functional and molecular alterations produced by aldosterone in heart.

Aldosterone regulates sodium (Na+) and potassium (K+) transports in epithelial cells. Besides, aldosterone participates in cardiac alterations associated with hypertension, heart failure, diabetes, and other pathological alterations. One of the main cardiac alterations induced by aldosterone is cardiac hypertrophy in which different mechanisms are involved such as increased cardiomyocyte, calcium concentration, oxidative stress, and inflammatory and fibrotic mediators stimulation. Many epidemiological studies have demonstrated that left ventricular hypertrophy is associated with significantly increased risk of heart failure and malignant arrhythmias. SGK1 is a member of the serine/threonine kinase gene family that plays an important role in the absorption of Na+ and water through the Na+ channel in the apical membrane of tubular epithelial cells. SGK1 has been related to fibrotic mediator increase such as connective tissue growth factor (CTGF) and transforming growth factor-ß (TGF-ß) as well as inflammatory [tumor necrosis factor-α (TNF-α) and interleukin (IL)-1ß] and oxidative (NADPH oxidase) species. It has been shown that aldosterone induces SGK1 gene expression not only in kidneys but also in the heart. Supporting the central role of SGK1 in cardiac alterations induced by aldosterone, treatment with the mineralocorticoid antagonist spironolactone is able to reduce the gene expression of SGK1 in aldosterone-treated rats. Taken together, data suggest the involvement of SGK1 in a complex intracellular signaling, involving fibrotic, inflammatory, and oxidative pathways, which lead to cardiac hypertrophy and fibrosis induced by aldosterone.

Carob pod insoluble fiber exerts anti-atherosclerotic effects in rabbits through sirtuin-1 and peroxisome proliferator-activated receptor-γ coactivator-1α.

The aim of this study was to evaluate the potential effects of an insoluble dietary fiber from carob pod (IFC) (1 g ⋅ kg(-1) ⋅ d(-1) in the diet) on alterations associated with atherosclerosis in rabbits with dyslipidemia. Male New Zealand rabbits (n = 30) were fed the following diets for 8 wk: 1) a control diet (SF412; Panlab) as a control group representing normal conditions; 2) a control supplemented with 0.5% cholesterol + 14% coconut oil (DL) (SF302; Panlab) for 8 wk as a dyslipidemic group; and 3) a control containing 0.5% cholesterol + 14% coconut oil plus IFC (1 g ⋅ kg(-1) ⋅ d(-1)) (DL+IFC) for 8 wk. IFC was administered in a pellet mixed with the DL diet. The DL-fed group developed mixed dyslipidemia and atherosclerotic lesions, which were associated with endothelial dysfunction, inflammation, and fibrosis. Furthermore, sirtuin-1 (SIRT1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) protein expression in the aorta were reduced to 77% and 63% of the control group, respectively (P < 0.05), in these rabbits. Administration of IFC to DL-fed rabbits reduced the size of the aortic lesion significantly (DL, 15.2% and DL+IFC, 2.6%) and normalized acetylcholine-induced relaxation (maximal response: control, 89.3%; DL, 61.6%; DL+IFC, 87.1%; P < 0.05) and endothelial nitric oxide synthase expression (DL, 52% and DL+IFC, 104% of the control group). IFC administration to DL-fed rabbits also reduced cluster of differentiation 36 (DL, 148% and DL+IFC, 104% of the control group; P < 0.05), plasminogen activator inhibitor-1 (DL, 141% and DL+IFC, 107% of the control group), tumor necrosis factor-α (DL, 166% and DL+IFC, 120% of the control group), vascular cell adhesion molecule-1 (DL, 153% and DL+IFC, 110% of the control group), transforming growth factor-ß (DL, 173% and DL+IFC, 99% of the control group), and collagen I (DL, 157% and DL+IFC, 112% of the control group) in the aorta. These effects were accompanied by an enhancement of SIRT1 and PGC-1α (160% and 121% of the control group, respectively; P < 0.05) vascular expression. In summary, we demonstrated for the first time, to our knowledge, that administration of IFC reduces the development of atherosclerosis in rabbits. This effect seems to be related to an improvement in endothelial function and a reduction of inflammation and fibrosis, most probably as a consequence of the reduction of serum concentrations of cholesterol and triglycerides. Increased expression of aortic SIRT1 and PGC-1α could play an important role in the observed effects of IFC in rabbits with dyslipidemia.

Protective effect of a pomace olive oil concentrated in triterpenic acids in alterations related to hypertension in rats: mechanisms involved.

SCOPE: Despite the amount of information and research on the effects of virgin olive oil and its components in cardiovascular disease, little attention has been paid to the effects of pomace olive oil, an olive oil subproduct traditionally used in Spain. The aim of the present study was to evaluate the potential effects of a pomace olive oil concentrated in triterpenic acids (POCTA) on blood pressure, cardiac hemodynamics, and functional and molecular vascular alterations associated with hypertension in spontaneously hypertensive rats (SHR). METHODS AND RESULTS: The study showed that POCTA attenuated the increase of blood pressure in SHR. This effect was associated with an improvement in endothelium-dependent relaxation, enhancement of vascular expression of endothelial nitric oxide synthase, and reduction of tumor necrosis factor alpha, transforming growth factor beta, and collagen I. Furthermore, POCTA improved cardiac hemodynamics (left ventricular systolic pressure and left ventricular end-diastolic pressure) and decreased relative kidney and lung weights. CONCLUSION: POCTA exerts antihypertensive effects together with vascular and hypertension target organ protection in SHR. Since interest in pomace olive oil has been low, the results of this study contribute to increasing awareness of its biological and nutritional values.

Spironolactone prevents alterations associated with cardiac hypertrophy produced by isoproterenol in rats: involvement of serum- and glucocorticoid-regulated kinase type 1.

Persistent ß-adrenergic receptor stimulation with isoproterenol is associated with cardiac hypertrophy as well as cardiac synthesis of angiotensin II. Serum- and glucocorticoid-regulated kinase type 1 (SGK-1) is a key mediator in structural, functional and molecular cardiac effects of aldosterone in rats. This study was designed to investigate the cardiac effects of the mineralocorticoid receptor antagonist spironolactone on the response to isoproterenol treatment in rats, as well as the involvement of the main mediator of cellular aldosterone action, SGK-1, in the heart. Male Wistar rats received isoproterenol (3 mg kg(-1) day(-1)) or vehicle for 15 days. Half of the animals in each group were simultaneously treated with spironolactone (200 mg kg(-1) day(-1)). Systolic and diastolic blood pressures were not significantly different among groups. Treatment with spironolactone normalized the increased left ventricular end-diastolic pressure observed in isoproterenol-treated rats. Isoproterenol treatment induced cardiac hypertrophy and increased collagen content, both of which were normalized by spironolactone treatment. The mRNA levels of transforming growth factor ß, connective tissue growth factor, matrix metalloprotease 2, matrix metalloprotease inhibitor 2, tumour necrosis factor α, interleukin 1ß, p22phox and xanthine dehydrogenase were increased (P < 0.05) in isoproterenol-treated rats, and this effect was prevented by spironolactone (P < 0.05). Spironolactone also reduced the elevated SGK-1 expression in isoproterenol-treated rats. The observed reduction of the principal mediator of aldosterone cellular actions, SGK-1, by spironolactone in hearts from isoproterenol-treated rats suggests a role of mineralocorticoids in the cardiac hypertrophy, fibrosis, inflammation, oxidation and diastolic dysfunction induced by isoproterenol treatment in rats.