Mitophagy modulation for the treatment of cardiovascular diseases

BACKGROUND

Defects of mitophagy, the selective form of autophagy for mitochondria, are commonly observed in several cardiovascular diseases and represent the main cause of mitochondrial dysfunction. For this reason, mitophagy has emerged as a novel and potential therapeutic target.

METHODS

In this review, we discuss current evidence about the biological significance of mitophagy in relevant preclinical models of cardiac and vascular diseases, such as heart failure, ischemia/reperfusion injury, metabolic cardiomyopathy and atherosclerosis.

RESULTS

Multiple studies have shown that cardiac and vascular mitophagy is an adaptive mechanism in response to stress, contributing to cardiovascular homeostasis. Mitophagy defects lead to cell death, ultimately impairing cardiac and vascular function, whereas restoration of mitophagy by specific compounds delays disease progression.

CONCLUSIONS

Despite previous efforts, the molecular mechanisms underlying mitophagy activation in response to stress are not fully characterized. A comprehensive understanding of different forms of mitophagy active in the cardiovascular system is extremely important for the development of new drugs targeting this process. Human studies evaluating mitophagy abnormalities in patients at high cardiovascular risk also represent a future challenge.

miR-93 and synaptotagmin-7: two novel players in the regulation of autophagy during cardiac hypertrophy

The molecular mechanisms involved in the transition of cardiac hypertrophy to heart failure (HF) are not fully characterized. Autophagy is a catabolic, self-renewal intracellular mechanism, which protects the heart during HF. In the heart of a mouse model of angiotensin-II-induced hypertrophy, Sun and colleagues demonstrated that reduced levels of miR-93 lead to synaptotagmin-7 (Syt-7) upregulation and consequent inhibition of autophagy. miR-93 overexpression or syt-7 inhibition rescues autophagy and maladaptive hypertrophy. This research identifies new players in the pathophysiology of cardiac hypertrophy, opening innovative therapeutic perspectives. miR-93 may also be considered in the future as a novel circulating biomarker for patients at high risk to develop HF.

Effects of two-month treatment with a mixture of natural activators of autophagy on oxidative stress and arterial stiffness in patients with essential hypertension: A pilot study

BACKGROUND AND AIMS

Trehalose, spermidine, nicotinamide, and polyphenols are natural substances that exert pro-autophagic and antioxidant properties. Their role in blood pressure (BP) regulation and preservation of vascular function in essential hypertension is unknown. The aim of this study was to evaluate the effect of a mixture of these agents on BP level, markers of oxidative stress, autophagy, endothelial function, and vascular stiffness in outpatients with grade 1 uncomplicated essential hypertension.

METHODS AND RESULTS

A single-centre, open-label, case-control, pilot study was conducted in adult outpatients (aged ≥18 years) receiving or not the mixture for two months along with the standard therapies. Both at baseline and at the end of the treatment the following clinical parameters were evaluated: brachial seated office BP level, central aortic pressure, pulse wave velocity, augmentation index (AI@75). Both at baseline and at the end of the treatment, a blood sample was drawn for the measurement of: H2O2, HBA%, levels of sNOX2-dp, Atg 5, P62, endothelin 1, and NO bioavailability. The mixture of nutraceuticals did not influence BP levels. Patients receiving the mixture showed a significant decrease of oxidative stress, stimulation of autophagy, increased NO bioavailability and no increase of the AI@75, in contrast to what observed in hypertensive patients not receiving the mixture.

CONCLUSIONS

The supplementation of the trehalose, spermidine, nicotinamide, and polyphenols mixture counteracted hypertension-related arterial stiffness through mechanisms likely dependent on oxidative stress downregulation and autophagy stimulation. These natural activators of autophagy may represent favourable adjuvants for prevention of the hypertensive cardiovascular damage.

MST1 mediates doxorubicin-induced cardiomyopathy by SIRT3 downregulation

Heart failure is a major side effect of doxorubicin (DOX) treatment in patients with cancer. However, the mechanisms underlying the development of DOX-induced heart failure need to be addressed. This study aims to test whether the serine/threonine kinase MST1, a major Hippo pathway component, contributes to the development of DOX-induced myocardial injury. C57BL/6J WT mice and mice with cardiomyocyte-specific dominant-negative MST1 (kinase-dead) overexpression received three weekly injections of DOX, reaching a final cumulative dose of 18 mg/kg. Echocardiographic, histological and biochemical analyses were performed six weeks after the first DOX administration. The effects of MST1 inhibition on DOX-induced cardiomyocyte injury were also tested in vitro. MST1 signaling was significantly activated in cardiomyocytes in response to DOX treatment in vitro and in vivo. Wild-type (WT) mice treated with DOX developed cardiac dysfunction and mitochondrial abnormalities. However, these detrimental effects were abolished in mice with cardiomyocyte-specific overexpression of dominant-negative MST1 (DN-MST1) or treated with XMU-MP-1, a specific MST1 inhibitor, indicating that MST1 inhibition attenuates DOX-induced cardiac dysfunction. DOX treatment led to a significant downregulation of cardiac levels of SIRT3, a deacetylase involved in mitochondrial protection, in WT mice, which was rescued by MST1 inhibition. Pharmacological inhibition of SIRT3 blunted the protective effects of MST1 inhibition, indicating that SIRT3 downregulation mediates the cytotoxic effects of MST1 activation in response to DOX treatment. Finally, we found a significant upregulation of MST1 and downregulation of SIRT3 levels in human myocardial tissue of cancer patients treated with DOX. In summary, MST1 contributes to DOX-induced cardiomyopathy through SIRT3 downregulation.

Trehalose, a natural disaccharide, reduces stroke occurrence in the stroke-prone spontaneously hypertensive rat

Cerebrovascular disease, a frequent complication of hypertension, is a major public health issue for which novel therapeutic and preventive approaches are needed. Autophagy activation is emerging as a potential therapeutic and preventive strategy toward stroke. Among usual activators of autophagy, the natural disaccharide trehalose (TRE) has been reported to be beneficial in preclinical models of neurodegenerative diseases, atherosclerosis and myocardial infarction. In this study, we tested for the first time the effects of TRE in the stroke-prone spontaneously hypertensive rat (SHRSP) fed with a high-salt stroke permissive diet (JD). We found that TRE reduced stroke occurrence and renal damage in high salt-fed SHRSP. TRE was also able to decrease systolic blood pressure. Through ex-vivo studies, we assessed the beneficial effect of TRE on the vascular function of high salt-fed SHRSP. At the molecular level, TRE restored brain autophagy and reduced mitochondrial mass, along with the improvement of mitochondrial function. The beneficial effects of TRE were associated with increased nuclear translocation of TFEB, a transcriptional activator of autophagy. Our results suggest that TRE may be considered as a natural compound efficacious for the prevention of hypertension-related target organ damage, with particular regard to stroke and renal damage.

Screening young athletes for diseases at risk of sudden cardiac death: role of stress testing for ventricular arrhythmias

Aims

The athletic preparticipation evaluation (PPE) protocol proposed by the European Society of Cardiology includes history, physical examination and resting electrocardiogram (ECG). The aim of this study was to assess the results of adding constant-load ECG stress testing (EST) to the protocol for the evaluation of ventricular arrhythmias (VA) inducibility.

Methods

We evaluated a consecutive cohort of young athletes with history, physical examination, resting ECG and EST. Athletes with VA induced by EST underwent 24-hour 12-lead Holter monitoring and echocardiography. Cardiac magnetic resonance (CMR) was reserved for those with frequent, repetitive or exercise-worsened VA, and for athletes with echocardiographic abnormalities.

Results

Of 10,985 athletes (median age 15 years, 66% males), 451 (4.1%) had an abnormal history, physical examination or resting ECG and 31 (0.28%) were diagnosed with a cardiac disease and were at risk of sudden cardiac death. Among the remaining 10,534 athletes, VA at EST occurred in 524 (5.0%) and a previously missed at-risk condition was identified in 23 (0.22%); the most common (N = 10) was an echocardiographically silent non-ischaemic left-ventricular fibrosis evidenced by CMR. The addition of EST increased the diagnostic yield of PPE by 75% (from 0.28% to 0.49%) and decreased the positive predictive value by 20% (from 6.9% to 5.5%). During a 32 ± 21 months follow-up, no cardiac arrests occurred among either eligible athletes or non-eligible athletes with cardiovascular disease.

Conclusions

The addition of exercise testing for the evaluation of VA inducibility to history, physical examination and ECG resulted in an increase of the diagnostic yield of PPE at the expense of an increase in false-positive findings.

Exemestane for primary prevention of breast cancer in postmenopausal women: NCIC CTG MAP.3—A randomized, placebo-controlled clinical trial

LBA504

Background: Limited efficacy and serious toxicities have limited uptake of tamoxifen or raloxifene as preventatives of breast cancer. Aromatase inhibitors (AIs) prevent contralateral breast cancers more than tamoxifen in adjuvant trials and have fewer serious side effects. This is the first report of an AI used in primary prevention. Methods: NCIC CTG MAP.3 is a randomized trial designed to detect a 65% reduction in annual incidence of invasive breast cancer (IBC) on exemestane (E) versus placebo (P). Eligible postmenopausal women had ≥ one of the following risk factors: Gail score >1.66%, prior ADH, ALH, LCIS or DCIS with mastectomy, age over 60. Health-related and menopause-specific quality of life (QOL) were assessed by SF-36 and MENQOL questionnaires. Results: From 2004-2010, 4,560 women were randomized: age 62.5 yrs (37-90); Gail Score 2.3 % (0.6-21); BMI 28.0 kg/m2 (15.9-65.4). Risk factors included: age >60 yrs (49%); Gail score >1.66 (40%); and prior ADH, ALH, LCIS or DCIS with mastectomy (11%). At median follow-up of 35 months there were 11 IBCs on E and 32 on P (annual incidence 0.19% vs 0.55%; HR= 0.35, 95% CI 0.18-0.70, p = 0.002); ductal (10E/27P), lobular (1E/5P). Most tumors were ER positive (7E/27P); Her2/neu negative (10E/26P); TNM stage T1 (8E/28P), N0 (7E/22P), M0 (11E/30P). E was superior in all subgroups: by Gail score, age, BMI, prior LCIS and DCIS. The annual incidence rate of IBC or DCIS was 0.35% E and 0.77% P (HR=0.47;95% CI 0.27-0.79; p = 0.004) based on 64 IBCs or DCISs (20E/44P). Clinical bone fractures, osteoporosis, hypercholesterolemia or cardiovascular events were equal in both arms. No clinically meaningful differences in QOL were detected. Conclusions: Exemestane significantly reduced invasive and pre-invasive breast cancers in postmenopausal women at increased risk for breast cancer with no serious toxicities. Exemestane should be considered a new option for primary prevention of breast cancer. Supported by the Canadian Cancer Society; Pfizer Inc. PEG supported in part by Avon Foundation.

Breast cancer after stopping estrogen plus progestin in postmenopausal women in the women's health initiative

Abstract #64

Background
 Following the Women's Health Initiative (WHI) estrogen plus progestin (E+P) trial report (JAMA 2002;288:321), menopausal hormone therapy use decreased dramatically in the United States. Subsequently, breast cancer incidence also dropped substantially, suggesting possible causality (NEJM 2007;16:1680); however, the etiology remains controversial.
 Methods
 To define effects of stopping E+P on breast cancer incidence more precisely, additional analyses were conducted in the WHI randomized trial of daily conjugated equine estrogens (CEE, 0.625 mg) plus medroxyprogesterone acetate (MPA, 2.5 mg) versus placebo. Furthermore, temporal trends for breast cancer diagnoses in the WHI observational study cohort were examined. Breast cancer risk factors, mammography utilization and calendar time-specific breast cancer incidence were assessed relative to E+P use.
 Results: The time-specific linear hazard ratio (HR) curves examining E+P influence on breast cancer in the E+P clinical trial (CT), and in the observational study (OS, the later adjusted for E+P use during follow-up) are attached.
 
 
 
 In the CT, breast cancer incidence, initially lower in the E+P group, increased with longer duration use but decreased postintervention despite closely comparable mammogram frequency between randomization groups. In the OS, breast cancer incidence was about two-fold higher in E+P users vs non-users (likely reflecting longer duration exposure) but decreased rapidly following year-to-year reductions in E+P use, while differences in mammogram frequency between E+P users and non-users were unchanged.
 Conclusion: These findings suggest that cessation of E+P use is associated with a rapid reduction in breast cancer incidence which is not explained by mammography utilization change and support the hypothesis that the recent reduction in breast cancer incidence seen in certain age groups is predominantly related to a decrease in combined menopausal therapy use.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 64.

Promoting the advancement of minority women faculty in academic medicine: the National Centers of Excellence in Women's Health

Minority physicians provide care in a manner that promotes patient satisfaction and meets the needs of an increasingly diverse U.S. population. In addition, minority medical school faculty bring diverse perspectives to research and teach cross-cultural care. However, men and women of color remain underrepresented among medical school faculty, particularly in the higher ranks. National data show that although the numbers of women in medicine have increased, minority representation remains essentially static. Studying minority women faculty as a group may help to improve our understanding of barriers to diversification. Six National Centers of Excellence in Women's Health used a variety of approaches in addressing the needs of this group. Recommendations for other academic institutions include development of key diversity indicators with national benchmarks, creation of guidelines for mentoring and faculty development programs, and support for career development opportunities.

Incidence of bladder cancer in areas “at risk”

– Cancer of the bladder is closely correlated to life style and exposure to environmental and occupational chemical substances. This study, based on data taken from the tumour register of the Province of Ragusa for the period 1988–1992, has shown that bladder cancer is higher in terms of incidence and mortality than the national average. Epidemiological data would seem to back up the suspicion that there is a link between bladder cancer and phytopharmaceuticals, which could act as “initiator” and/or “promoter” agents according to the “carcinogenesis in two stages” theory. Further research will also be carried out with specific toxicological studies.

Synthesis and opioid activity of partial retro-inverso analogs of dermorphin

We studied the effect of partial retro-inverso modification of selected peptide bonds of dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2. The modifications concern two consecutive peptide bonds (Phe3-Cly4-Tyr5, I) or a single one (Gly4-Tyr5-, II or Phe3-Gly4, III). All pseudoheptapeptides showed low opioid activity in the in vitro and in vivo tests. Compound III has a biological potency comparable to that of morphine but only 2-5% of original dermorphin when tested in guinea pig ileum preparation and in mice tail-flick assay after intracerebro or subcutaneous administration.

Synthesis and opioid activity of [Sar4]dermorphin-tetrapeptide analogues

The modification of the dermorphin-(1-4)-tetrapeptide structure led to analogues with potent opioid activity in vitro and in vivo. [Sar4]Tetrapeptides such as H2N-CH(NH)-Tyr-D-Ala-Phe-Sar-D-NH-CH(CH3)C6H5 (VII) whose terminal amino group is replaced by the guanidino function and whose C-terminus is amidated by (R)-(+)-alpha-methylbenzylamine, show peripheral and central opioid activities comparable to or higher than those of dermorphin. The potency of VII in the different tests was as follows: guinea-pig ileum (GPI) IC50 = 0.09nM, mouse Vas deferens (MVD) IC50 = 0.69nM, tail-flick ED50 = 8.91 pmol/mouse, i.c.v. and 4.54 mumol/kg, s.c. This dermorphin-(1-4)-tetrapeptide derivative is about 650 and 950 times as active as morphine in the two in vitro tests, respectively. The MVD/GPI potency ratio of the new peptides suggests a mu-type agonist behaviour.

Opioid peptides. Structure-activity relationships of dermorphin endothiotetrapeptides. VII

We describe the synthesis and preliminary in vitro and in vivo pharmacological tests of five endothiotetrapeptide analogues of the opioid heptapeptide dermorphin H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser.-NH2. The modification obtained by substituting Phet for Phe3 or Glyt for Gly4 provided further analogues with significant opioid activity.

Structure-Activity Relationships for Dermorphin-Related Tetrapeptides

The opiate-like activity of six newly synthesized dermorphin-related tetrapeptides was determined in guinea pig ileum, mouse vas deferens and mouse tail-flick tests. Naloxone was a powerful antagonist of all compounds. Moreover, the biological activities of the compounds under examination were correlated in a statistically significant way to the lipophilic character of the C-terminal substituents and to an indicator variable taking into account the presence of an amidic group at the C-terminus.

Pharmacological studies of a series of dermorphin related pentapeptides

Pharmacological activity in vitro and in vivo of 17 pentapeptide analogs of dermorphin (opioid heptapeptide) are reported. Substitutions of the Tyr5 residue afford dermorphin related pentapeptides which are likely to discriminate between mu- and delta-receptors.

Opioid peptides. Structure-activity relationships in [beta-Ala4]dermorphin tetrapeptides. V

We describe the synthesis and preliminary in vitro and in vivo pharmacological tests of six [beta-Ala4]tetrapeptides analogs of the opioid heptapeptide dermorphin H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2. The modification obtained by substituting beta-Ala4 for Gly4 provided further analogues with significant opioid activity.

Opioid peptides. Analgesic activity of potent dermorphin tetrapeptides. VI

By employing the mouse tail-flick assay the analgesic activity of selected dermorphin tetrapeptides was assessed. The remarkable differences in potency exhibited by peptides after i.c.v. (500-1000 times higher than morphine) and s.c. (nearly comparable to morphine) administration are probably due to peptidase degradation.

Opioid peptides. Structure-activity relationships in dermorphin pentapeptides III

The synthesis and preliminary pharmacological in vitro of seventeen pentapeptide analogs of the opioid peptide dermorphin are reported. Substitution at residue Tyr5 and/or modification of C-terminal are generally well tolerated.

Opioid peptide. Structure-activity relationships in dermorphin tetrapeptide-amides. II

Preliminary pharmacological data and the characterization of sixteen synthetic tetrapeptide-amide analogs of dermorphin (opioid heptapeptide) are reported. N,N-dialkylamides displayed reduced or no activity; on the contrary, derivatization of H-Tyr-D-Ala-Phe-Gly-OH C-terminus by suitable amide moieties (1-adamantanamine, 1-adamantane-methylamino, or D-alpha-methylbenzylamine) produced potent analogues with peripheral and central opioid activities comparable to, or higher than those of dermorphins.

Opioid peptides. Structure-activity relationships in dermorphin tetrapeptides. I

Characterisation and pharmacological data of twelve synthetic tetrapeptide analogs of dermorphin (opioid heptapeptide) are reported. An N-terminal tetrapeptide free acid or ester is less potent that the corresponding amide. Whereas substitution of Gly4 by another aminoacid residue is well tolerated, substitution of D-Ala2 by D- or L-alpha-aminoxypropionic acid causes a complete loss of activity. Finally, guanidination of the tetrapeptides results in an increase of peripheral and central opioid activity.

Synthesis and pharmacological activity of dermorphin and its N-terminal sequences

H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2 (demorphin), and opiate-like peptide, and tri-, tetra-, penta- and hexapeptide-amide analogs, were synthesized by conventional methods in solution, to determine the minimum peptide chain-length, required for analgesic activity.

[Modulation of the effect of morphine on the isolated guinea pig intestine by noradrenaline and serotonin]

The interference of NA and 5-HT on Morphine inhibition on electrically-driven guinea-pig ileum was investigated. The alpha-antagonist Phentolamine (1 gamma/ml) and alpha MT-pretreatment reduced Morphine inhibition on muscle twitch. Similarly, ilea taken from pCPA-pretreated animals were less sensitive to the opioid. In contrast, both NA or 5-HT added either to normal or to amine-depleted tissue enhance Morphine inhibition. Therefore, not only in the brain but also in the guinea-pig ileum NA and 5-HT enhanced opioid effect.

Pseudo-pseudohypoparathyroidism, empty sella syndrome, and hypopituitarism in a young woman

The confluence of pseudo-pseudohypoparathyroidism, empty sella syndrome, and pituitary insufficiency is reported for the first time. The patient, an 18-year-old woman, was evaluated because of primary amenorrhea. Possible relations between the three entities described are discussed and the appearance of pituitary hypofunction in patients with the empty sella syndrome is emphasized.

Large translocation t(3q-;4p+) as probable cause for semisterility

A couple with one phenotypically normal son and two recorded abortions complained of apparent inability to have more children. The father, and also his son, proved to be carriers of the translocation t(3q-;4p+). Almost certainly, the length of the translocated segment, practically the whole 3q, would cause either translocation chromosome by itself to lead to prenatal death. Furthermore, the fertility of the carrier father may be considerably decreased if in a sufficient number of spermatocytes the meiotic orientation of the chain or, less probably, the ring formed by 3, 3q-,4p+, and 4 is such that the two 3-centromeres go to one pole and the two 4-centromeres to the other, not to mention an even more abnormal 1:3 segregation.

Lesch-Nyhan mutation: prenatal detection with amniotic fluid cells

Cells cultured from the amniotic fluid of a 22-week fetus in a heterozygote for the X-linked Lesch-Nyhan mutation, which results in neurological and developmental disorders, lacked sex chromatin and were unable to incorporate hypoxanthine. The diagnosis of a mutant male was confirmed upon birth of enzyme-deficient, hyperuricemic twin boys whose amniotic membrane cells failed to incorporate hypoxanthine.