Correlation between hyperghrelinemia and carotid artery intima-media thickness in children with Prader-Willi syndrome

Heal the heart through gut (hormone) ghrelin: a potential player to combat heart failure

Ghrelin, a small peptide hormone (28 aa), secreted mainly by X/A-like cells of gastric mucosa, is also locally produced in cardiomyocytes. Being an orexigenic factor (appetite stimulant), it promotes release of growth hormone (GH) and exerts diverse physiological functions, viz. regulation of energy balance, glucose, and/or fat metabolism for body weight maintenance. Interestingly, administration of exogenous ghrelin significantly improves cardiac functions in CVD patients as well as experimental animal models of heart failure. Ghrelin ameliorates pathophysiological condition of the heart in myocardial infarction, cardiac hypertrophy, fibrosis, cachexia, and ischemia reperfusion injury. This peptide also exerts significant impact at the level of vasculature leading to lowering high blood pressure and reversal of endothelial dysfunction and atherosclerosis. However, the molecular mechanism of actions elucidating the healing effects of ghrelin on the cardiovascular system is still a matter of conjecture. Some experimental data indicate its beneficial effects via complex cellular cross talks between autonomic nervous system and cardiovascular cells, some other suggest more direct receptor-mediated molecular actions via autophagy or ionotropic regulation and interfering with apoptotic and inflammatory pathways of cardiomyocytes and vascular endothelial cells. Here, in this review, we summarise available recent data to encourage more research to find the missing links of unknown ghrelin receptor-mediated pathways as we see ghrelin as a future novel therapy in cardiovascular protection.

Prader-Willi syndrome: A model for understanding the ghrelin system

Subsequent to the discovery of ghrelin as the endogenous ligand of growth hormone secretagogue receptor 1a, this unique gut peptide has been found to exert numerous physiological effects, such as appetite stimulation and lipid accumulation via the central regulating mechanisms in the hypothalamus, stimulation of gastric motility, regulation of glucose metabolism and brown fat thermogenesis, and modulation of stress, anxiety, taste sensation, reward-seeking behaviour and the sleep/wake cycle. Prader-Willi syndrome (PWS) has been described as a unique pathological state characterised by severe obesity and high circulating levels of ghrelin. It was hypothesised that hyperghrelinaemia would explain at least a part of the feeding behaviour and body composition of PWS patients, who are characterised by hyperphagia, an obsession with food and food-seeking, and increased adiposity. Initially, the link between hyperghrelinaemia and growth hormone deficiency, which is observed in 90% of the children with PWS, was not fully understood. Over the years, however, the increasing knowledge on ghrelin, PWS features and the natural history of the disease has led to a more comprehensive description of the abnormal ghrelin system and its role in the pathophysiology of this rare and complex neurodevelopmental genetic disease. In the present study, we (a) present the current view of PWS; (b) explain its natural history, including recent data on the ghrelin system in PWS patients; and (c) discuss the therapeutic approach of modulating the ghrelin system in these patients and the first promising results.

Gender-Specific Association of Desacylated Ghrelin with Subclinical Atherosclerosis in the Metabolic Syndrome

OBJECTIVE

Ghrelin, a gastric hormone with pleiotropic effects modulates vascular function and may influence atherosclerosis. Plasma ghrelin is reduced in the metabolic syndrome (MS), which is also characterized by early atherosclerosis. Ghrelin circulates in acylated (AG) and desacylated (DAG) forms. Their relative impact and that of gender on subclinical atherosclerosis in MS is unknown.

AIM OF THE STUDY

To investigate potential associations of total, AG and DAG with carotid atherosclerosis and with gender in the MS.

METHODS

Plasma total ghrelin, AG, DAG and carotid artery IMT (cIMT) were measured in 46 MS patients (NCEP-ATP III criteria, 22M/24F).

RESULTS

Compared with males, females had higher (p <0.05) total and DAG. In the association analysis, age and plasma glucose were positively (p <0.05) correlated with cIMT in all MS patients. The positive (p <0.05) association between cIMT and age was also confirmed in males, while that between cIMT and glucose was significant in women. In contrast, neither total ghrelin nor AG and DAG were associated with cIMT in all MS patients nor in the male subgroup. In females, a negative (p <0.05) association between carotid artery IMT, DAG and glucose was detected, but not between cIMT, total ghrelin and AG. In multivariate modeling, DAG remained negatively (p <0.05) associated with cIMT after adjusting for plasma glucose and cardiovascular risk factors.

CONCLUSIONS

These data indicate a negative independent association between DAG and cIMT in middle-aged women with the MS and suggest a gender-specific modulatory function of DAG in the development of atherosclerosis.

Ghrelin and atherosclerosis

PURPOSE OF REVIEW

The increasing prevalence of metabolic syndrome and the consequent cardiovascular diseases has stimulated an active search for novel risk factors. The hormones regulating energy balance are of special interest as potential risk factor indicators of cardiovascular diseases. Ghrelin provides an attractive target for studies of atherosclerosis being a gastric peptide hormone having multiple functions including orexigenic and growth hormone-releasing effects and is also involved in the regulation of cardiovascular and immunomodulatory system.

RECENT FINDINGS

The aim of the present article is to review recent studies on the role of ghrelin in the atherosclerosis. Ghrelin seems to influence known risk factors of atherosclerosis, endothelial dysfunction, inflammation and oxidation. These themes will be covered by the present article and a summary of clinical studies of ghrelin in atherosclerosis will be given.

SUMMARY

Ghrelin plays a beneficial role in multiple processes of atherogenesis and vascular function. However, ghrelin's effects are not as strong as those of traditional known risk factors.

Plasma ghrelin levels are closely associated with severity and morphology of angiographically-detected coronary atherosclerosis in Chineses patients with diabetes mellitus

AIM

Low plasma ghrelin level was found to be associated with diabetes, and ghrelin was shown to inhibit pro-atherogenic changes in experimental models of atherosclerosis. The aim of this study was to investigate the relationship between plasma ghrelin levels and coronary atherosclerotic lesions in Chinese patients with diabetes.

METHODS

Plasma ghrelin levels were measured using an ELISA kit. The severity of coronary artery disease (CAD) was determined via angiography. Composition of atherosclerotic plaques was detected via coronary CT angiography.

RESULTS

A total of 178 patients with diabetes were recruited. Among the patients, 70 were diagnosed with acute coronary syndrome (ACS), 82 with stable angina pectoris (SAP) and 26 without coronary angiographic finding (controls). A negative correlation was found between ghrelin levels and the severity of the CAD, as determined via the Gensini score (r=-0.2434; P=0.0217). In diabetic patients with CAD and a complex lesion, the plasma ghrelin levels were significantly lower than in those with a simple lesion (ACS group: 3.81 ± 0.49 ng/mL vs 4.72 ± 0.50 ng/mL, P<0.0001; SAP group: 4.21 ± 0.52 ng/mL vs 4.76 ± 0.59 ng/mL, P=0.0397). Angiographically-detected complex lesion was an independent factor associated with ghrelin levels (adjusted beta coefficient=-0.67, 95% CI -0.97 to -0.37, P<0.0001).

CONCLUSION

Low plasma ghrelin level is closely related to angiographically-detected severity and the complex lesion morphology in Chinese diabetic patients with CAD.