Background Image
Table of Contents Table of Contents
Previous Page  32 / 61 Next Page
Information
Show Menu
Previous Page 32 / 61 Next Page
Page Background

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 4, July/August 2021

204

AFRICA

The discrepancy of aromatase expression in epicardial

adipose tissue between CHD and non-CHD patients

Yifan Li, Weiwei Cheng, Bin Zhao, Dongliang Ma, Xing Wei, Shunye Zhang

Abstract

Objectives:

Epicardial adipose tissue (EAT) aromatase

converts androstenedione and other adrenal androgens into

oestrogens. The locally produced oestradiol (E

2

) may have

cardiovascular protective effects. Little is known about the

relationship between EAT aromatase level and coronary heart

disease (CHD). Here, we compared EAT aromatase levels in

CHD versus non-CHD patients and assessed the relation-

ship between EAT aromatase levels and lesion degree in the

coronary arteries.

Methods:

EAT and blood specimens were obtained from

patients undergoing thoracotomy prior to cardiopulmonary

bypass. Serum E

2

levels were obtained from our hospital

laboratory. EAT aromatase expression was determined by

RT-qPCR and ELISA assays. All patients underwent coro-

nary angiography and the level of coronary lesions was evalu-

ated with the SYNTAX score.

Results:

Compared with non-CHD patients, CHD patients

had lower EAT aromatase mRNA and protein levels. In the

CHD patients, EAT aromatase and oestrogen levels nega-

tively correlated with the severity of coronary artery disease.

Conclusion:

Our data revealed that reduced EAT aromatase

levels correlated with coronary atherosclerotic lesions.

Reduced EAT aromatase protein levels may aggravate the

severity of atherosclerosis. Future studies should investigate

the mechanisms regulating aromatase expression in epicardial

fat.

Keywords:

coronary heart disease, epicardial adipose tissue,

aromatase, oestrogen

Submitted 14/1/21, accepted 21/3/21

Published online 7/6/21

Cardiovasc J Afr

2021;

32

: 204–207

www.cvja.co.za

DOI: 10.5830/CVJA-2021-012

Due to the close association between obesity and cardiovascular

diseases such as coronary heart disease (CHD), heart failure,

hypertension, stroke, atrial fibrillation and sudden cardiac

death, the roles of adipose tissue have been widely studied. In

the past 20 years, adipose tissue, which is regarded as the largest

endocrine organ, has been shown to have complex secretory

functions with local and systemic effects.

1

As a consequence

of maladaptive adipose tissue expansion, adipose tissue cells

undergo phenotypic modifications that alter their secretory

output.

2

Adipose tissue can transform steroid precursors into steroid

hormones to influence fat distribution and lipid metabolism.

3

This function of adipose tissue depends on aromatase, an

enzyme encoded by the cytochrome P450 family 19 subfamily

A member 1 (CYP19A1), which catalyses the production of

oestrone and oestradiol (oestrogens) from androstenedione and

testosterone (androgens), respectively.

4

Even with low levels of

aromatase, the abundance of adipose tissue makes it a major

source of oestrogen in postmenopausal women and aging men.

5

The oestrogens generated in this way bind to specific receptors to

exert cardiovascular protection.

6

Both epicardial and visceral adipose tissue (EAT and VAT)

derive from the splanchnopleuritic mesoderm.

7

EAT is wrapped

by the visceral pericardium and directly adheres to the myocardial

surface and coronary arteries.

7

In physiological settings, EAT

accounts for about 20% of the heart’s weight and is mainly

distributed along the coronary artery in the atrioventricular

sulcus, interventricular sulcus, right ventricular free wall and left

ventricular apex, with small amounts around the left and right

atria and auricle. There is no fascial structure between EAT and

the adjacent myocardial and vascular walls.

8

EAT releases factors such as adiponectin, interleukin

(IL)-1

β

, IL-6, tumour necrosis factor (TNF)-

α

and nitric oxide,

which directly infiltrate into the myocardium (paracrine) or go

through the coronary vasa vasorum (vasocrine) to influence the

coronary arteries.

9-11

Currently there is no evidence confirming

the relationship between aromatase levels in EAT and CHD.

Here, we examined the relationship between EAT aromatase

levels and CHD.

Methods

The case group (

n

= 30) (CHD group) comprised male

patients, aged 50 years and older, who underwent coronary

artery bypass grafting due to coronary atherosclerotic heart

disease, with at least one coronary artery stenosis > 90% as

revealed by coronary angiography. The control group (

n

=

30) comprised non-CHD patients, aged 50 years and older,

undergoing thoracotomy due to other cardiac implications,

with no significant stenosis on coronary angiography. Patients

with severe hepatorenal dysfunction or under treatment with

hormones, immunosuppressants, chemotherapy or other special

drugs were excluded from the study.

After coronary angiography in our hospital, three researchers

with senior attending physicians examined the angiography

images and entered the values into the SYNTAX score calculator.

Department of Cardiovascular Surgery, Shanxi

Cardiovascular Hospital, Taiyuan, PR of China

Yifan Li, MD

Weiwei Cheng, MD

Bin Zhao, MD

Dongliang Ma, MD

Xing Wei, MD

Shunye Zhang, MD,

956980086@qq.com