TH1 lymphocytes in the perivascular adipose tissue correlate with plaque composition and increase the risk of intraplaque haemorrhages in coronary arteries: an autopsy study
Authors: Farias-Itao D S , Pasqualucci C A , Andrade R A , Silva L F F , Estevam M Y , Campo A B , Suemoto C K 
Published: October 2021

Abstract

Background
Inflammation in the perivascular adipose tissue (PvAT) might play a role in coronary artery disease. The T helper 1 (Th1) lymphocytes are the most popular T helper (Th) lymphocytes in atherosclerotic plaques and are proatherogenic. However, the association between the Th1 and Th lymphocytes in the PvAT with coronary atherosclerosis composition was not previously investigated in humans.

Purpose
We investigated the correlation between Th CD4+ and Th1 CD4+CXCR3+ lymphocytes in the PvAT with atherosclerotic plaque composition.

Methods
Human coronary arteries were freshly dissected with adjacent PvAT. The most important atherosclerotic plaque was selected of the main coronary arteries and was stained with hematoxylin-eosin, Masson's trichrome, and Verhöeff. We calculated the percentage of arterial obstruction, intima-media thickness, the minimum fibrous cap thickness, and the percentual of collagen, smooth muscle cells (SMC), fibrous cap, calcification, lipid, necrosis, and intraplaque hemorrhage. The atherosclerotic plaques were classified in stable and unstable plaques (hemorrhages and thrombus). The density of Th lymphocytes (CD4+), Th1 (CD4+CXCR3+), and the ratio of Th1/Th were detected using the immunohistochemistry double staining technique. The densities and the ratio Th1/Th were correlated with plaque composition using linear, negative binomial, or Poisson regressions models with clustering for multiple measures in the same individual and adjusted for age, sex, hypertension, diabetes, body mass index, sedentary lifestyle, smoking, and alcohol consumption.

Results
We evaluated a sample of 126 coronary arteries from 58 subjects. The individuals were older (70.4±14.3 years old), sex was equally distributed, 74% had hypertension, and 40% diabetes. In multivariate analysis, the Th lymphocytes were negatively correlated with calcification content (β=−0.21, 95% CI: −0.41; −0.006, p=0.043). The Th1 lymphocytes were not correlated with plaque composition; however, the increase of Th1 density in relation to Th lymphocytes was negatively correlated with SMC (β=−35.6, 95% CI: −68.5; −2.83, p=0.03) and the fibrous cap content (β=−11.6, 95% CI: −19.1; −4.05, p=0.003). Additionally, the higher proportion of Th1/Th lymphocytes increased the risk of intraplaque haemorrhages compared to stable coronary plaques (OR=15.5, 95% CI: 1.23; 196.4, p=0.03).

Conclusions
The increase of pro-inflammatory Th1 lymphocytes in the PvAT was correlated to the decrease of components in atherosclerotic plaques related to plaque stabilization, such as SMC and fibrous cap content. Additionally, the increase in the proportion of pro-inflammatory Th1 lymphocytes in the PvAT also increases the risk of intraplaque haemorrhages in coronary arteries.

Funding Acknowledgement
Type of funding sources: Foundation. Main funding source(s): São Paulo Research Foundation (FAPESP) Figure 1Figure 2