Resting and Activated Natural Tregs Decrease in the Peripheral Blood of Patients with Atherosclerosis

Document Type: Original Article

Authors

1 Department of Immunology, Shiraz University of Medical Sciences, Shiraz, Iran

2 Department of Cardiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran

3 Shiraz Institute for Cancer Research, Shiraz University of Medical Sciences, Shiraz, Iran

Abstract

Background: Atherosclerosis is a chronic inflammatory disease affecting large and
medium arteries. CD4+ T cells are known to play a role in the progression of the
disease. CD4+CD25+Foxp3+ natural Treg (nTreg) cells seem to have a protective role
in the disease and their reduction in acute coronary syndrome is recently shown.
Objective: To investigate the frequency of nTreg subsets in the peripheral blood of
patients with atherosclerosis. Methods: Confirmation of atherosclerosis was done by
angiography and 15 ml heparinized blood was obtained from each of the 13 nondiabetic
patients and 13 non-diabetic, non-smoker individuals with normal/insignificant
coronary artery disease which was also confirmed by angiography. Lipid profiles of the
patients and controls were measured at the time of sampling. Mononuclear cells were
used for both RNA extraction and immunophenotyping by real-time PCR and
flowcytometry techniques, respectively. Results: In natural Treg subsets, the frequency
of CD4+CD45RO-CD25+Foxp3lo T-cells (resting nTregs) was greater in controls than
patients (p=0.02). The frequency of CD4+CD45RO+CD25hiFoxp3hi T-cells (activated
nTregs) was significantly higher in controls compared with patients (p=0.02). However,
the frequency of CD4+CD25+CD45RO+Foxp3- T-cells (effector/memory) increased in
patients compared with controls (p=0.01). Both the MFI and gene expression of Foxp3
were higher in control group than in patients (p=0.015 and p=0.017, respectively).
Moreover, the TGF-β gene expression showed a decrease in the peripheral blood
mononuclear cells of patients compared with controls (p=0.03). Conclusion: Decrease
in both subsets of resting and activated nTregs along with a decrease in the expression
of Foxp3 and TGF-β genes in patients with atherosclerosis suggests phenotypic changes
in these subsets, which may as well be correlated with a more inflammatory profile in
their lymphocytes.

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