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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.zaDOI: 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